Introduction

Front. Immunol.

Frontiers in Immunology

Front. Immunol.

1664-3224

Frontiers Media S.A.

10.3389/fimmu.2023.1103592

Immunology

Review

Porphyromonas gingivalis regulates atherosclerosis through an immune pathway

Ruan

Qijun

¹ ^† Guan

Peng

¹ ^† Qi

Weijuan

¹ Li

Jiatong

¹ Xi

Mengying

¹ Xiao

Limin

¹ Zhong

Sulan

¹ Ma

Dandan

² ^* Ni

Jia

¹ ^*

¹ Department of Periodontics, Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, China ² Department of Endodontics, Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, China

Edited by: Aditi Chopra, Manipal College of Dental Sciences, Manipal, India

Reviewed by: Krzysztof Guzik, Jagiellonian University, Poland; Sasanka Chukkapalli, Texas A&M University College Station, United States

*Correspondence: Dandan Ma, mdd@smu.edu.cn; Jia Ni, 441569008@qq.com

†These authors have contributed equally to this work and share first authorship

This article was submitted to Inflammation, a section of the journal Frontiers in Immunology

14 03 2023

2023

1103592

22 11 2022 01 03 2023

2023

Ruan, Guan, Qi, Li, Xi, Xiao, Zhong, Ma and Ni

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Atherosclerosis (AS) is a chronic inflammatory disease, involving a pathological process of endothelial dysfunction, lipid deposition, plaque rupture, and arterial occlusion, and is one of the leading causes of death in the world population. The progression of AS is closely associated with several inflammatory diseases, among which periodontitis has been shown to increase the risk of AS. Porphyromonas gingivalis (P. gingivalis), presenting in large numbers in subgingival plaque biofilms, is the “dominant flora” in periodontitis, and its multiple virulence factors are important in stimulating host immunity. Therefore, it is significant to elucidate the potential mechanism and association between P. gingivalis and AS to prevent and treat AS. By summarizing the existing studies, we found that P. gingivalis promotes the progression of AS through multiple immune pathways. P. gingivalis can escape host immune clearance and, in various forms, circulate with blood and lymph and colonize arterial vessel walls, directly inducing local inflammation in blood vessels. It also induces the production of systemic inflammatory mediators and autoimmune antibodies, disrupts the serum lipid profile, and thus promotes the progression of AS. In this paper, we summarize the recent evidence (including clinical studies and animal studies) on the correlation between P. gingivalis and AS, and describe the specific immune mechanisms by which P. gingivalis promotes AS progression from three aspects (immune escape, blood circulation, and lymphatic circulation), providing new insights into the prevention and treatment of AS by suppressing periodontal pathogenic bacteria.

porphyromonas gingivalis atherosclerosis immune escape blood circulation lymphatic circulation

National Natural Science Foundation of China10.13039/501100001809

1 Introduction

P. gingivalis, a Gram-negative anaerobic bacterium, is the “dominant flora” in periodontitis (1, 2). P. gingivalis can stimulate the host immune response through virulence factors, including its structural components (fimbriae, LPS, etc.) and secretory components (gingipains and OMVs) (3). P. gingivalis fimbriae can enhance the inflammatory response and evade host immune clearance (4). P. gingivalis LPS is an important virulence factor with lipid A as its immune core, triggering a signaling pathway closely related to lipid A variants (5). P. gingivalis gingipains are powerful protein hydrolysers that assist P. gingivalis to evade host immunity (6). P. gingivalis OMVs are outer membrane vesicles containing multiple virulence factors that can circulate widely throughout the body and access areas of tissue not accessible to whole bacteria, thereby triggering an inflammatory response (7). P. gingivalis and its virulence factors can promote the development of a variety of systemic diseases such as cardiovascular disease, diabetes, Alzheimer’s disease, etc (8).

AS is a chronic inflammatory pathological change occurring in the walls of medium to large arteries, characterized by immune cell infiltration and lipid deposition, and poses a serious threat to human life and health. Recent single-cell sequencing studies have revealed abundant heterogeneity of immune cells in the AS plaque environment. For example, three macrophage subpopulations were identified in human and mouse AS plaques, including inflammatory, resident-like (TREM2^hi), and TREM2^hi macrophages. Among them, TREM2^hi macrophages are a foam-like, anti-inflammatory type of macrophages and exhibit an osteoclast-like gene expression profile that may be associated with plaque calcification (9, 10). Similar studies point to the presence of a cluster in mouse AS plaques that matches the core marker profile of B1 cells (CD43^highB220^negCD11b^high) but shows enriched TNF signaling and cell adhesion pathways that may be key cell types for promoting AS (11). Previously unknown clusters of naive T cells and ApoB⁺ T cells have also been found in plaques and are closely associated with vascular inflammation, but the exact mechanism is not yet clear (12). Another study found that vascular smooth muscle cells (VSMCs) phenotype-switching mechanisms play an important role in AS. During AS development, VSMCs can give rise to a novel intermediate cell with multidirectional differentiation potential, which can either differentiate into macrophage-like or fibrocartilage-like cells or revert to VSMCs (13). VSMCs and endothelial cells (ECs) in the core of human arterial AS lesions were found to drive cellular transdifferentiation through multiple genes, whereas VSMCs and ECs in the adjacent zone were involved in immune cell recruitment through C3 and MHC II molecules, respectively (14). More in-depth studies using single-cell sequencing pointed out that DHRS9 in macrophages is a key factor in AS formation (15), and CXCL3, GK, FPR1, and LST1 in monocytes are closely associated with plaque instability (16). The application of single-cell sequencing technology has deepened the understanding of cellular heterogeneity in AS lesions, and provided an important theoretical basis for further investigation of AS pathogenesis and the development of targeted therapeutic drugs. In addition, single-cell sequencing studies have the advantage of investigating the mechanisms of interaction between two or more cells in tissues, such as between immune cells and tissue cells, yet no relevant studies have been seen.

Existing researches show that P. gingivalis promotes AS progression through immune responses (17, 18). On the one hand, P. gingivalis evades host innate and adaptive immunity and, in various forms, circulates with blood and lymph and colonizes the arterial vessel wall, directly inducing local inflammation and lesions in blood vessels. On the other hand, after evading host immunity, P. gingivalis persistently stimulates the host immune response, induces systemic inflammatory mediators and autoimmune antibody production, disorders of lipid levels, and promotes AS progression. In this paper, we review the recent evidence on P. gingivalis promoting AS and the related immune response mechanisms to elucidate the potential mechanism of action and association between P. gingivalis and AS, and provide theoretical guidance for further in-depth studies.

2 Evidence of correlation between <italic>P. gingivalis</italic> and AS 2.1 Clinical studies

The American Heart Association (AHA) supports an independent association between periodontal disease (PD) and atherosclerotic vascular disease, but not a causal relationship between the two (19). Subsequent studies in the last decade also lack evidence to date for a causal relationship between PD and AS. Current clinical studies have mainly elaborated on the correlation between PD and AS by detecting the colonization of periodontal pathogens in AS plaques and serum levels of AS-associated inflammatory markers.

Clinical studies have shown that abundant P. gingivalis colonization can be detected in AS plaques of different artery types. A Meat analysis based on 1791 patients showed that P. gingivalis specifically localized to coronary AS plaques but not to other organs (20). A study of 58 patients with moderate or severe periodontitis with AS using a 16sRNA assay found P. gingivalis detection rates of 26.7% in carotid arteries and 39.3% in coronary arteries (21). Also using the detection method of 16sRNA assay, some studies have pointed out that the detection rate of periodontal pathogens including P. gingivalis in carotid AS lesions is only 21% (22). Another study using metagenomics techniques noted that P. gingivalis colonization was detected in the coronary or femoral arteries of 42 patients with AS who participated in the study and that P. gingivalis accounted for nearly 80% of all colonized bacterial species, but the study was notably deficient in that it did not assess the periodontal status of the participants (23). Some scholars believe that the difference in the detection rate of P. gingivalis in AS plaques may be due to demographic, geographical, and ethnic differences, as well as different sampling methods and laboratory testing methods of clinical samples, but there are no related statistical and methodological differences (24). The colonization and invasion of P. gingivalis into the arterial wall allows P. gingivalis to acquire a “privileged niche”. This “privileged niche” not only helps P. gingivalis to obtain proteins and iron substrates from the host but also separates P. gingivalis from humoral and cellular immunity, thus inducing endothelial dysfunction and promoting AS progression (25) ( Table 1 ).

Table 1

Clinical Research Evidence of P. gingivalis and AS.

Research Type	Country	Research Object	Sample Type	Result	References
Meta analysis	/	1791 AS patients	Coronary artery, carotid artery	P. gingivalis is one of the bacteria peculiar to AS plaque	(20)
Clinical research	America	42 AS patients	Coronary artery, femoral artery	P. gingivalis accounts for nearly 80% of all bacterial species colonized in AS plaque	(23)
Clinical research	Serbia	58 AS patients with periodontitis	Coronary artery, carotid artery	P. gingivalis was detected in 26.7% of carotid arteries and 39.3% of coronary arteries	(21)
Clinical research	France	45 AS patients with periodontitis	Carotid artery	The detection rate of periodontal pathogens including P. gingivalis in AS lesions was only 21%	(22)
Clinical research	Sweden	42 healthy people, 89 periodontitis patients	Serum	The IgG antibody titer of anti-P. gingivalis in the serum of patients with periodontitis is at a long-term stable high level	(26)
Clinical research	Columbia	22 patients with gingivitis, 22 patients with periodontitis	Serum	Serum E-selectin, MPO, and ICAM-1 levels in patients with periodontitis increased	(27)
Clinical research	Britain	120 patients with severe periodontitis	Serum	Periodontal treatment reduces the level of inflammatory factors in the blood and improves the endothelial function of arteries	(28)
Clinical research	Brazil	69 patients with coronary heart disease severe and periodontitis	Serum	Periodontal treatment maintained a relatively normal blood concentration of markers of vascular inflammation but did not improve arterial vascular conditions	(29)
Clinical research	South Korea	247696 healthy adults aged 40 and over	/	Daily brushing and regular dental maintenance reduce AS risk	(30)
Clinical research	America	15792 participants aged 45-64	/	Regular dental care and care significantly reduce the risk of AS	(31)
Clinical research	America	8999 participants aged 20-85	/	The incidence rate of cardiovascular diseases in patients with poor periodontal treatment prognosis is 1.28 times higher than that in patients with a good prognosis	(32)

In patients with periodontitis, the presence of P. gingivalis colonization in the arterial vessel wall, as well as significantly higher serum anti-P. gingivalis antibody titers (26, 33) and inflammatory factor levels (27, 34) may lead to a concomitant increase in AS risk (35, 36). In contrast, routine oral maintenance and periodontal treatment significantly reduced the levels of AS-related inflammatory factors in the serum of the patient and significantly improved the endothelial function of the patient’s arterial vessels, leading to a consequent reduction in the risk of AS.

Several recent large population studies have evaluated the effect of routine oral maintenance and periodontal treatment on the progression of AS, and have reached similar conclusions. A Korean follow-up study based on 247,696 healthy adults aged 40 years and older showed that brushing more than once a day and regular professional dental cleanings reduced the risk of cardiovascular events, including AS, by 9% and 14%, respectively (30). A U.S. study of atherosclerosis risk in communities (ARIC) based on 15,792 participants aged 45-64 years over 15 years showed that regular dental care and attention significantly reduced the risk of AS (31). Another U.S. study based on 8,999 participants aged 20-85 years with 16.8 years of follow-up noted that the incidence of cardiovascular disease, including AS, was 1.28 times higher in those with a poor prognosis for periodontal treatment than in those with a good prognosis for periodontal treatment (32). A study of 120 patients with severe periodontitis showed lower levels of inflammatory factors in the blood after 24 hours of periodontal treatment compared to usual oral care, and a significant improvement in endothelial function of the arteries at six months (28). Plasma levels of AS-related risk molecules, including inflammatory factors (CRP, IL-6, TNF-α), thrombotic molecules (fibrinogen), and metabolic markers (triglycerides, TC, HDL-C, HbA1c, A-FABP), were significantly reduced within six months after periodontal treatment means to eliminate periodontal inflammation (37–40). However, it has also been shown that periodontal treatment, while maintaining relatively normal blood concentrations of vascular inflammatory markers, did not improve arterial vascular status in a short-term follow-up within three months after periodontal treatment and did not indicate an AS risk-reducing effect (29) ( Table 1 ).

Based on the above clinical basis, we can speculate that P. gingivalis may promote AS by colonizing the arterial wall and causing abnormal serum inflammatory factor levels; however, there is still insufficient evidence from clinical studies on P. gingivalis and AS. Comparative studies on the colonization of P. gingivalis in the arterial canal wall before and after periodontal treatment are lacking. Current epidemiological data focus on medium-sized arteries such as coronary, carotid, and femoral arteries, however, the lack of studies on large arteries such as the aorta may be significantly associated with the availability of experimental samples. In addition, PD and AS each have multiple complex and critical risk factors that are pervasive and powerful contributors and difficult to fully exclude, including age, smoking, and diabetes mellitus (41). Therefore, future studies should increase the consideration of multiple confounding factors, including the criteria for admission to PD, standardized treatment regimens for PD, recurrence of PD and evolution of AS, and other important risk factors.

2.2 Animal studies

Animal studies have shown that ApoE^-/- mice with oral P. gingivalis infection have elevated serum levels of cellular inflammatory factors (42) and significantly increased vascular reactivity (43), and P. gingivalis was detected to colonize the aorta, damaging the arterial endothelium (44) and increasing AS plaque (45). In addition, numerous studies have demonstrated that serum inflammatory mediators and lipoprotein levels were significantly abnormal in oral P. gingivalis-infected ApoE^-/- mice, such as NLRP3, IL-6, IL-1β, TNF-α, intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule 1 (VCAM-1), monocyte chemotactic protein(MCP), P-selectin, E-selectin, low-density lipoprotein (LDL), HDL, etc (46, 47) ( Table 2 ).

Table 2

Animal Research Evidence of P. gingivalis and AS.

Time	Animal Type	Modeling method	Sample Type	Result	References
2011	C57BL/6 ApoE^-/- mice	Oral infection with P. gingivalis	Serum,spleen	Promote the release of systemic pro-inflammatory cytokines and accelerate the progress of AS	(42)
2011	C57BL/6 wild-type,ApoE^-/- mice	Oral infection with P. gingivalis	Serum, aorta	Enhance arterial reactivity mediated by α-adrenoceptor	(43)
2014	ApoE^null B6.129P2-Apoe^tm1Unc/J mice	Oral infection with P. gingivalis	Serum, aorta	Promote the colonization of viable aortic bacteria and increase inflammation	(45)
2015	ApoE^-/- B6.129P2-Apoe^tm1Unc/J mice	Oral infection with complex (P.g,T.d,T.f,F.n)	Serum, aorta	Disturb the serum lipid profile and promote the progress of AS	(46)
2015	C.KOR Apoe^shl mice	Oral infection with P. gingivalis	Serum, aorta	Increase the area of aortic plaque significantly, NLRP3 inflammasome played an important role	(47)
2021	C57BL/6 ApoE^-/- mice	Oral infection with P. gingivalis	Serum, aorta, liver	Promote vascular endothelial dysfunction	(44)
2010	ICR mice	Intravenous injection with P. gingivalis	Femoral artery	Promote the hyperplasia of arterial intima, and is related to the over-expression of S100A9 and SMemb on the surface of smooth muscle cells	(48)
2016	C57BL/6J wild-type mice	Subcutaneous inoculation with P. gingivalis、ligation of coronary artery	Heart	Increase the risk of heart rupture significantly	(49)
2016	B57BL/6 wild-type,B57BL/6-Tlr4^lps-del mice	Intravenous injection with P. gingivalis GroEL	Serum, aorta	Increase expression of VCAM-1, ICAM-1, TLR4, and LOX-1 in the aorta	(50)
2017	C57BL/6 ApoE^-/- mice	Intravenous injection with P. gingivalis	Serum, aorta, heart, liver	Abnormal lipid profiles were found in serum, heart, aorta, and liver	(51)
2020	C57BL/6 ApoE^-/- mice	Intravenous injection with P. gingivalis	Serum, aorta	Increase expression of oxidative stress markers and inflammatory factors in serum and aorta	(52)
2014	C.KOR-Apoe^shl mice	Sublingual immune with P. gingivalis rGroEL	Serum, aortic, spleen	Reduce AS lesions in the aortic sinus significantly, and decrease serum levels of CRP, MCP-1, and ox-LDL.	(53)
2018	LDLR^-/- mice	subcutaneous injection with P. gingivalis Rgp44	Serum, aorta	Generate protective IgM for ox-LDL to reduce AS risk	(54)
2020	ApoE^-/- mice	Nasal Immune with P. gingivalis GroEL Derived Pep14	Serum, aorta,liver	Reduce AS risk by promoting IFN- γ secretion and/or inhibiting Th17-mediated immune response	(55)
2021	ApoE^-/- mice	Nasal immune with inactive P. gingivalis	Aorta	Reduce plaque area of AS significantly, and the effect was similar to that of statins	(56)

In addition to oral infection with P. gingivalis, some studies have also infected mice by subcutaneous inoculation or intravenous P. gingivalis injection. Animal studies have shown that subcutaneous inoculation with P. gingivalis accelerates AS and leads to a significant increase in mortality from cardiac rupture (49). Intravenous P. gingivalis injection revealed significant intimal hyperplasia and VSMCs proliferation in the aorta of mice (48). After intravenous P. gingivalis injection, ApoE^-/- mice showed increased expression of oxidative stress markers and inflammatory factors in serum and aorta (52), and abnormal lipid profiles were found in serum, heart, aorta, and liver (51). Intravenous injection of recombinant P. gingivalis heat shock protein GroEL into C57BL/6 mice on a high-fat diet resulted in stronger expression of VCAM-1, ICAM-1, TLR4, and lectin-like ox-LDL receptor (LOX-1) (50) ( Table 2 ).

Some recent studies have also conducted experiments on the relationship between P. gingivalis-related vaccines and AS. Heated ultrasound P. gingivalis-prepared vaccine significantly reduced AS plaque area in ApoE^-/- mice on the background of high-fat diet and oral P. gingivalis infection employing nasal immunization, with effects comparable to those of statins (56). Similarly, sublingual immunization with P. gingivalis GroEL (53) or nasal immunization with its derivative peptide 14 (Pep14) (55) achieved inhibition of AS plaque formation. In addition, subcutaneous immunization of LDLR^-/- mice with the A hemagglutinin domain (Rgp44) of P. gingivalis promotes the production of protective IgM against ox-LDL and reduces the risk of AS (54). There are few studies on the relationship between P. gingivalis-related vaccines and AS, and the mechanism of action is not fully understood and needs to be further investigated ( Table 2 ).

Oral infection with P. gingivalis can lead to dysregulated intestinal flora (57), and dysregulated intestinal flora can also promote AS progression through metabolism-dependent pathways (58). Among them, Trimethylamine-N-oxide (TAMO) is one of the most important metabolites associated with dysregulated intestinal flora (59, 60). TMAO promotes foam cell production by upregulating macrophage CD36 and SR-A1 expression which impairs macrophage cholesterol reversal transport function (61). TMAO promotes the release of pro-inflammatory mediators through the activation of mitogen-activated protein kinase, extracellular signal-associated kinase, and NF-κB cascade pathways, which in turn induces an inflammatory response in ECs and VSMCs (62–64). TMAO exacerbates AS progression by promoting the release of intracellular Ca²⁺, leading to platelet aggregation and thrombosis (65).

However, there are still limitations in the establishment of current animal models. Intravenous injection of planktonic state P. gingivalis in an infectious manner not only hardly mimics the characteristics of inflammation triggered by normal plaque biofilm but also may lead to a sharp increase in the level of P. gingivalis in the circulatory system and trigger a strong stress response. Thus, the type and degree of the inflammatory response induced by intravenous P. gingivalis may not match the chronic state of infection in a real situation. Certainly, the intravenous approach may apply to the study model of acute systemic bacterial infections.

It is noteworthy that both clinical and animal studies have used 16srRNA, metagenomics sequencing to detect P. gingivalis g gene fragments in the arterial wall to determine colonization. But these techniques are impossible to assess the activity status and reproduction of P. gingivalis after colonization or to determine whether the gene fragments are from intact bacteria or P. gingivalis OMVs. These are limitations of the current assays. The activity of P. gingivalis colonized in the arterial wall or the different virulence factors released by dead bacteria may directly influence the degree of local inflammatory response in the vessel wall. In vitro studies have pointed out that live P. gingivalis induces monocyte adhesion to the endothelium and promotes the vascular inflammatory response by promoting the expression of adhesion molecules and pro-inflammatory factors in ECs, whereas heat-killed P. gingivalis does not trigger these effects (66, 67). Therefore, the conclusion that P. gingivalis colonizes the arterial vessel wall cannot yet be directly correlated with vascular inflammation using these techniques. Further culture and characterization of strains of AS tissue are needed to explore P. gingivalis activity after colonization. This is a central part of the follow-up study.

3 Pathogenicity of <italic>P. gingivalis</italic> and pathogenesis of AS 3.1 Pathogenicity of <italic>P. gingivalis</italic>

P. gingivalis is the “dominant flora” in periodontitis, which can reshape the symbiotic colonization of periodontal tissues and induce dysbiosis of periodontal microbial homeostasis (2). During disease development, P. gingivalis interacts with the host immune system through its unique virulence factors, resulting in a unique and complex pathogenic mechanism, such as induction of inflammatory response, activation of the complement system, promotion of apoptosis, and other biological processes (1). In addition, the virulence factors of P. gingivalis can interact with various host receptors to reshape the survival environment or escape host immune killing, allowing them to persist in host tissues (3).

3.1.1 <italic>P. gingivalis</italic> gingipains

P. gingivalis gingipains have potent proteolytic activity and play a key role in disrupting the host immune response. P. gingivalis gingipains include arginine-specific gingipains (RgpA and RgpB), and lysine-specific gingipains (Kgp). P. gingivalis gingipains cause host immune dysregulation and inflammatory responses to occur by activating matrix metalloproteinases, inactivating immunosuppressants, degrading immunomodulatory factors, and cleaving immune cell receptors (6). P. gingivalis gingipains degrade the junctional adhesion molecule (JAM1) of gingival epithelial cells, disrupting epithelial barrier function and increasing the ability of bacteria and their products such as LPS and peptidoglycan (PGN) to locally invade and penetrate the peripheral blood (68). P. gingivalis gingipains selectively degrade the macrophage surface innate immune receptor CD14, resulting in the hyporesponsiveness to bacterial challenge (69). P. gingivalis gingipains can degrade neutrophil-derived α-defensins and β-defensins, disrupting the host’s innate immune function and facilitating bacterial escape (70). In addition, P. gingivalis gingipains have a significant disruptive effect on the complement system. On the one hand, P. gingivalis gingipains inhibited the bactericidal effect of the complement system by degrading C3, C4, and C5 to inhibit complement activation and the formation of membrane attack complexes (71). On the other hand, P. gingivalis gingipains release the allergenic toxin C5a by cleaving complement C5, causing stronger inflammation (72). C5a induced by P. gingivalis gingipains can also subtly evade immune clearance via the C5aR-TLR2 crosstalk pathway (73).

3.1.2 <italic>P. gingivalis</italic> LPS

P. gingivalis LPS consists of lipid A, core oligosaccharide, and O-specific polysaccharide (6). P. gingivalis LPS can trigger innate immune responses by activating TLRs (74). The virulence properties of P. gingivalis LPS are determined by lipid A properties, thus different properties of lipid A can lead to different innate immune responses and the production of inflammatory factors. P. gingivalis LPS₁₆₉₀ with penta-acylated lipid A mainly activates the NF-κB signaling pathway, while P. gingivalis LPS_1435/1449 with tetra-acylated lipid A mainly induces p38/MAPK and ERK1/2 signaling pathways (74). P. gingivalis LPS induces M1-type polarization in macrophages and promotes the expression of several pro-inflammatory factors, such as TNF-α, IL-1β, and IL-6 (75). P. gingivalis LPS promotes the progression of periodontal inflammation by inducing pyroptosis in gingival fibroblasts (76). P. gingivalis LPS triggers mitochondria-mediated apoptosis by regulating XBP1 expression (77). P. gingivalis LPS promotes platelet proliferation and thrombosis by activating platelet Cdc42 (78).

3.1.3 <italic>P. gingivalis</italic> fimbriae

The fimbriae of P. gingivalis are divided into long fimbriae (FimA) and short fimbriae (Mfa1), both of which have enhanced inflammatory responses and evasion of host immune clearance, although each has its mechanism of action with the host. FimA acts through the characteristic P. gingivalis peptidilarginine deiminase (PPAD)-dependent activation of TLR2, induction of NF-ĸB and MAPK signaling pathways, and promotion of pro-inflammatory factor production (79). FimA interacts with complement receptor 3 (CR3) in macrophages, leading to ERK1/2 phosphorylation and inhibition of IL-12 production to promote the survival of P. gingivalis (80). FimA induces cAMP-dependent protein kinase A (PKA) activation via instigating macrophage CXCR4/TLR2 co-association, which in turn inhibits TLR2-mediated antimicrobial responses (81). The binding of FimA to CXCR4 induces CR3 activation via phosphatidylinositol-3 kinase (PI3K) and inhibits the antibacterial response in macrophages (82). Similar to FimA, Mfa1 induces the production of pro-inflammatory factors through the activation of TLRs (83, 84). Mfa1 inhibits the autophagy of DCs through the DC-SIGN-TLR2 crosstalk pathway, evading intracellular killing and leading to long-term survival within DCs (85).

3.2 Pathogenesis of AS

AS is a chronic cardiovascular disease that threatens human health and is characterized by lipid deposition in parts of the artery, accompanied by VSMCs and fibrous matrix proliferation, which gradually forms an AS plaque. AS is often considered a chronic inflammatory disease because inflammation plays an important role in all stages of AS development (86). The AS-associated inflammation is mainly mediated by pro-inflammatory factors, inflammatory signaling pathways, bioactive lipids, and adhesion molecules (87).

The main triggers of AS are endothelial damage, abnormal lipid metabolism, and hemodynamic impairment. In the early stages of AS, these pathological factors activate ECs (88). When ECs are activated, they express a variety of pro-inflammatory factors and adhesion molecules, including MCP-1, IL-8, ICAM-1, VCAM-1, E-selectin, and P-selectin, which attract lymphocytes and monocytes that bind to ECs and infiltrate the arterial wall, promoting the progression of the inflammatory response (89). Among them, pro-inflammatory monocytes expressing high levels of Ly6C or Gr-1 preferentially accumulate at damaged endothelial sites (90). Immune cells residing in the vessel wall participate in the inflammatory response process in the vessel wall together with the attracted immune cells. Large amounts of LDL are modified to ox-LDL and accumulate in the vessel wall, while macrophages in the vessel wall take up ox-LDL and convert it to foam cells, leading to the formation of AS plaques (91). Other types of immune cells, such as dendritic cells (DCs), T cells, B cells, and neutrophils are also involved in the progression of the inflammatory response within the plaque (92). In the advanced stages of AS, large numbers of macrophages and pro-inflammatory factors infiltrate the vessel wall, secrete matrix metalloproteinases (MMPs), and degrade collagen fibers in the extracellular matrix, leading to plaque rupture, hemorrhage, and thrombosis (89).

3.3 Pathogen-associated molecular patterns and damage-associated molecular patterns play a “bridging” role between <italic>P. gingivalis</italic> and AS

PAMPs are conserved pathogenic molecular structures shared by pathogenic microorganisms, while DAMPs are substances released into the intercellular space or blood circulation upon stimulation of tissues or cells (93). These substances bridge the gap between periodontitis and AS, allowing us to further understand the relationship between oral and systemic diseases (94).

P. gingivalis contains multiple PAMPs, including LPS and PGN, which initiate the inflammatory response of innate immunity by relying on the recognition of host cell pattern-recognition receptors (PRRs), such as NLRs and TLRs. P. gingivalis LPS induces the release of pro-inflammatory factors by activating NF-κB and MAPK signaling pathways in macrophages (95). P. gingivalis LPS promotes high expression of angiotensin II (Ang II) and IL-6 in ECs and accelerates ECs dysfunction (67). P. gingivalis LPS promotes monocyte chemotaxis and adhesion by increasing the expression of chemotactic and adhesion molecules in ECs through Akt and NF-κB signaling pathways (96). PGN promotes ICAM-1 production by monocytes through the activation of TLR2 and NF-κB pathways and induces monocyte migration and adhesion to the vascular endothelium (97). PGN promotes the upregulation of VCAM-1 through the NOD1-RIP2-NF-κB axis, inducing myeloid cells to recruit to the endothelium and leading to endothelial dysfunction (98). PGN can also mediate the over-expression of adhesion molecules in ECs through innate peptidoglycan recognition protein 1 (99). PGN induces the production of pro-inflammatory cytokines through TLR2 and CD14 and increases the susceptibility of AS plaques (100).

Meanwhile, periodontal pathogens further promote the progression of AS by activating inflammatory caspases that induce cell death and release various DAMPs, such as HSP60, cardiolipin, alarmins (S100 protein), and high mobility group box 1 (HMGB1) (101). HSP60 promotes immune cell migration and adhesion to the endothelium by stimulating the expression of E-selectin, VCAM-1, and ICAM-1 in ECs, and also induces endothelial inflammatory responses by activating TLRs (mainly TLR4) in innate immune cells (macrophages, DCs) (102). HSP60 induces DCs maturation and activates Th1 and Th17 cells in an MHC-II-dependent manner, promoting the release of pro-inflammatory mediators (103). HSP60 induces the activation of specific CD4⁺CD25⁺CD45RO⁺ T cells, which bind to ECs expressing HSP60 and adhesion molecules (VCAM-1 and E-selectin), forming susceptible sites of AS lesions (104). HSP60 induces the proliferation of VSMCs via TLR2 and TLR4 (105). The released cardiolipin may be oxidized by P. gingivalis to become oxidized cardiolipin (106, 107). Oxidized cardiolipin increases the expression levels of ICAM-1 and VCAM-1 in ECs and induces migration and adhesion of immune cells. At the same time, oxidized cardiolipin could also activate 5-lipoxygenase and induce leukotriene B4 production by increasing intracellular calcium concentration in macrophages and neutrophils, promoting inflammatory responses and exacerbating AS progression (108). P. gingivalis could promote VSMCs from contractile phenotype to synthetic phenotype by upregulating the expression of S100A9 in VSMCs (109). The circular RNA PPP1CC of P. gingivalis could promote VSMCs pyroptosis through the HMGB1/TLR9/AIM2 axis, which in turn increases AS plaque vulnerability (110).

4 Immune mechanism of <italic>P. gingivalis</italic> to promote AS progression

Immunity is an important line of defense of the organism against pathogenic invasion. P. gingivalis expresses a variety of virulence factors that stimulate host immune responses and play an important role in promoting AS progression. On the one hand, P. gingivalis evades host innate and adaptive immunity, internalizes in host tissues, and, in various forms, circulates with blood and lymph and colonizes arterial vessel walls, causing local inflammation and lesions; on the other hand, P. gingivalis persistently stimulates host immune responses in the process of host immune evasion and systemic dissemination, inducing systemic inflammatory mediators and disruption of lipid levels, and promoting AS progression. Based on the possible key role of P. gingivalis-associated PAMPs and DAMPs in promoting AS progression, the following literature will be reviewed from three aspects involving immune response: immune escape, blood circulation, and lymphatic circulation.

4.1 Immune escape

Immune escape is an important pathway for P. gingivalis to invade and survive in the host for a long time. A recent paper has reviewed P. gingivalis evasion of host immune killing through various pathways but did not elucidate the possible potential association and mechanism of P. gingivalis with AS during immune evasion (111). In this section, we will review the potential associations and mechanisms of P. gingivalis with AS during immune evasion in terms of dysregulation of the complement system and disruption of immune cell function.

4.1.1 <italic>P. gingivalis</italic> interferes with the function of the complement system

The complement system is a major part of the innate immune system and is activated by the hydrolytic cascade reaction of serine proteases. In inflamed vessels, the complement system can be activated by conjugates of CRP and modified LDL (112), inducing apoptosis of ECs, promoting the proliferation of VSMCs, inducing the release of procoagulant and adhesive factors, recruiting immune cells, and accelerating AS progression (113).

Studies suggest that the virulence factors of P. gingivalis may promote AS progression by interfering with the function of the complement system and, in turn, by promoting AS progression. P. gingivalis gingipains cleave complement C5 into biologically active C5a and C5b fragments (114, 115) and induce M1-type polarization of macrophages via the C5a pathway to promote inflammatory factor secretion (116). C5a is present in AS plaques and acts as a pro-AS molecule (117–119). In the early plaque formation stage, C5a activates mast cells in the arterial wall, promotes secretion of fibrinogen activator inhibitor (PAI-1), inhibits fibrinolysis and extracellular protein hydrolysis, and accelerates thrombus and AS plaque formation (120, 121). In the advanced stage of AS, C5a induces apoptosis of ECs and VSMCs, and expression of MMP1 and MMP9 in plaques, leading to VSMCs-dependent collagen loss, fibrous cap thinning, and plaque rupture (118, 122, 123). In addition, C5a accumulation enhanced NLRP3 inflammatory vesicle activation in AS plaques and decreased plaque stability (124). In contrast, a significant reduction in AS plaque area was observed after treatment of ApoE^-/- mice with C5aR antagonists (125, 126). Notably, P. gingivalis cleavage of C5 produced large amounts of C5a, which activated C5aR, triggered cross-talk signal between TLR2 and C5aR (127), suppressed macrophage immune function, increased P. gingivalis survival, and led to ubiquitinated degradation of myeloid differentiation factor (Myd88) (127–129), which is also a positive regulator of foam cell formation in AS (130). Therefore, it is speculated that the crosstalk between TLR2-C5aR may be closely related to the promotion of foam cell formation by P. gingivalis. However, it has not been reported yet and needs further in-depth study.

The above studies suggest that P. gingivalis gingipains may promote AS plaque formation and rupture by interfering with complement C5a function ( Figure 1 ). However, the current studies on the promotion of AS development by P. gingivalis through interference with the complement system are very limited, mainly focusing on the effects of P. gingivalis gingipains with C5a. However, whether similar effects and mechanisms exist for other virulence factors of P. gingivalis, whether other components of the complement system are involved in AS progression, and whether P. gingivalis-mediated TLR2-C5aR crosstalk is associated with foam cell formation is not fully understood and need to be further investigated in depth.

Figure 1

P. gingivalis induces immune escape and promotes AS progression (1). P. gingivalis degrades complement C5, promotes PAI-1 secretion by mast cells, and induces apoptosis of ECs and VSMCs (2). P. gingivalis inhibits phagosome-lysosome fusion in neutrophils, induces the formation of NETs, and increases secretion of MPO (3). P. gingivalis inhibits NO formation in macrophages and promotes M1-type polarization and activation of NLRP3 (4). P. gingivalis inhibits the antigen presentation process and induces Th17/Treg imbalance. (Created with BioRender.com).

4.1.2 <italic>P. gingivalis</italic> inhibits the antimicrobial function of immune cells

P. gingivalis inhibits the phagocytosis, surveillance, and clearance functions of immune cells through various mechanisms, evades host immune killing, survives in the host for a long time, repeatedly stimulates the body’s immune system, leads to a persistent low-level inflammatory state in the host, and promotes the progression of AS.

4.1.2.1 Neutrophils

Neutrophils are a class of innate immune cells that are the first to reach the site of P. gingivalis infection and can constitute an important barrier against P. gingivalis by producing proteases, antimicrobial peptides, and extracellular traps (NETs) (131, 132), as well as being important regulators of vascular inflammation (133).

It was found that P. gingivalis can evade immune killing by neutrophils. P. gingivalis activates the non-MyD88-dependent TLR2-PI3K signaling pathway in neutrophils, which both reduces the phagocytosis of P. gingivalis by neutrophils and blocks intracellular phagosome-lysosome fusion, thereby increasing the intracellular survival of P. gingivalis (129). It was also noted that P. gingivalis stimulated neutrophils to form NETs in a gingipains-dependent manner, but the antimicrobial components (histone protease, LL-37, etc.) in the formed NETs were hydrolyzed by gingipains, resulting in the lack of antimicrobial activity of NETs and the inability to achieve P. gingivalis clearance (132). In addition, the OMVs secreted by P. gingivalis can coat the neutrophils without being internalized, while the gingipains carried can degrade LL-37 and myeloperoxidase (MPO), which have secreted antimicrobial particle activity, and thus achieve the effect of avoiding neutrophil killing from a distance (134). The above pathways provide an opportunity for P. gingivalis to evade neutrophil immune killing, however, the efficacy of the various pathways has not been conclusively established.

However, it should not be overlooked that P. gingivalis still has a continuous stimulatory effect on neutrophils after evading immune killing, causing neutrophils to develop immune tolerance and inhibiting phagocytosis of P. gingivalis, while possibly promoting the progression of AS. P. gingivalis LPS-tolerant neutrophils have reduced phagocytosis of P. gingivalis, but significantly increased NETs formation and increased extracellular MPO levels, which may be related to neutrophils’ immune reconstitution (135). However, as already mentioned, P. gingivalis gingipains can degrade MPO (134). The “antagonism” between the pathogenicity of evaded phagocytosed P. gingivalis and the antimicrobial capacity of tolerant neutrophils determines the final fate of P. gingivalis. Furthermore, it has been shown that excess NETs promote plaque instability by directly inducing the death of ECs (136, 137), and that plasma MPO levels are positively correlated with the risk of AS (138). It is suggested that P. gingivalis may accelerate the progression of AS by promoting the production of NETs and MPO by tolerogenic neutrophils ( Figure 1 ). P. gingivalis gingipain R and some host-derived proteases inhibit the nonphlogistical clearance of apoptotic cells by macrophages through hydrolytic modification of apoptotic neutrophil surface protein ligands, leading to local accumulation of apoptotic neutrophils and secondary necrosis (139). The process of nonphlogistical clearance of apoptotic cells by macrophages is called “efferocytosis” and defective efferocytosis exacerbates AS progression (140).

4.1.2.2 Macrophages

Macrophages are a class of intrinsic immune cells with strong phagocytic capacity and antigen-presenting function, which can exert antimicrobial effects by phagocytosing P. gingivalis and P. gingivalis-infected cells, secreting pro-inflammatory cytokines (141), and are also major players in the formation of foam cells and mediating AS plaque stability (142).

It was found that P. gingivalis can undergo repeated cycling behavior in and out of cells in macrophages and successfully avoid macrophage killing (143), which may be related to the following mechanisms. First, the high heme concentration in the inflammatory environment can convert P. gingivalis surface lipid A to a tetraacylated form without TLR4 agonistic activity, limiting macrophage activation (144–146). Second, various specific virulence factors of P. gingivalis play an important role in interfering with macrophage immune responses. P. gingivalis gingipains degrade caspase-1, IL-1β, and CD14, inhibit the activation of a TLR2/4 signaling pathway in macrophages (69, 147), and suppress the bactericidal effect of inflammasomes (148). P. gingivalis FimA (long or major fimbriae) bind to CXCR4, both through PI3K signaling activates CR3 on macrophages contributing to P. gingivalis immune evasion (82, 149), and also induces cAMP-dependent protein kinase A (PKA) signaling, inhibits TLR2/1-mediated NF-κB activation and NO production, suppresses macrophage activation, and improves P. gingivalis survival and virulence (81). P. gingivalis sialidase inhibits macrophage IL-12 expression (150), thereby suppressing NK cell activation and the Th1 to Th2 phenotype switch, which in turn reduces the clearance of P. gingivalis (151). In addition, besides inhibiting the endocytic digestion of macrophages, P. gingivalis can also inhibit the autophagy of macrophages to a certain extent, leading to the immune escape of P. gingivalis. It has been shown that P. gingivalis can induce autophagy in macrophages and promote the clearance of P. gingivalis by macrophages (152). However, it has also been shown that different P. gingivalis LPS variants (LPS₁₆₉₀, LPS_1435/1449) exert different promoting or inhibiting effects on autophagy. Among them, the dominance of different P. gingivalis LPS variants depend on factors such as temperature, growth cycle, and heme chloride level (5, 153). LPS₁₆₉₀ induces macrophages to produce giant LC3-positive vesicles and melanoregulin puncta (cargo sorting protein), promoting lysosome maturation and autophagic response, while the presence of LPS_1435/1449 significantly inhibited the above effects (154). Therefore, it is speculated that the different occupancy of LPS₁₆₉₀ and LPS_1435/1449 in P. gingivalis may regulate the autophagy of macrophages and thus affect the survival of P. gingivalis. However, this has not been reported and needs to be further investigated in depth.

P. gingivalis, which survives in macrophages, induces inflammatory vesicle activation and M1-type polarization in macrophages (155). Animal studies have shown that oral inoculation of P. gingivalis can activate NLRP3 inflammasomes in macrophages in AS plaques in a gingipains-independent manner, promote the release of IL-1β and TNF-α, and accelerate AS progression (47, 148). In vitro studies have revealed that P. gingivalis LPS may induce M1-type polarization of macrophages via pattern recognition receptor triggering receptors expressed on myeloid cells-1(TREM-1) and its downstream signaling pathways to promote the secretion of multiple inflammatory factors and accelerate AS progression (75, 156, 157) ( Figure 1 ). However, recent studies have also indicated that P. gingivalis LPS-induced tolerant macrophages represent an intermediate state between M1/M2 polarization and function as M2-like cells to limit the inflammatory response (158), suggesting that P. gingivalis LPS tolerant macrophages may be closely related to tissue repair. This may be related to the different macrophage sources, stimulation factors, and temporal phases, and needs to be analyzed in further studies. In addition, the foam-like, anti-inflammatory TREM2^hi macrophage subpopulation identified by recent single-cell sequencing studies may be associated with plaque calcification (9). However, no studies related to P. gingivalis and TREM2^hi macrophage subsets have been reported. As a key cell type in host immune response and AS plaque formation, macrophages may have important intersections with multiple immune and metabolic mechanisms, but there is no uniform conclusion yet, and further in-depth studies are needed.

4.1.2.3 T cells

T cells are the main performers of adaptive immunity in the body and are also important regulators of AS plaque formation, development, and late stability (159). Notably, the hypoxic and ischemic environment of AS plaques may also have an impact on T cell metabolic status and function, which in turn affects AS progression (160, 161).

It is suggested that P. gingivalis may evade T cell immune killing by inhibiting antigen presentation function and thus T cell activation, proliferation, and antimicrobial function. In terms of inhibiting antigen presentation, P. gingivalis promotes IL-10 secretion by macrophages, downregulates the expression of MHC-II molecules (162), and promotes PD-L1 and PD-1 binding on the surface of macrophages and CD4⁺ T cells, inhibiting antigen presentation and T cell activation (162–164). In addition, P. gingivalis interferes with DCs autophagy and apoptotic processes by activating the Akt/mTOR axis, thereby promoting survival in DCs and inhibiting P. gingivalis processing and presentation by DCs (165, 166). In addition to inhibiting antigen presentation function, P. gingivalis can also directly inhibit T cell activation and proliferation. P. gingivalis and its Rgp-gingipains inhibit T cell proliferation by suppressing protein kinase C (PKC) and p38 phosphorylation and inhibiting transcription factor activator protein-1 (AP-1), thereby downregulating IL-2 gene expression and accumulation (167). In addition, P. gingivalis may inhibit the development and proliferation of Treg cells by decreasing the secretion of TGF-β1, which may be mainly related to the type II FimA of P. gingivalis (34). However, this study did not compare the effects of other types of FimA at the same time, and the mechanism has not been clarified, which needs further in-depth study. Based on the above study, we found that P. gingivalis suppressed host adaptive immunity from the process of inhibiting antigen presentation, T cell proliferation, and activation, providing a possibility for the long-term survival of P. gingivalis in the host.

AS is also regulated by T-lymphocyte subsets. Among them, Th17 cells have pro-atherogenic effects and Treg cells have anti-atherogenic effects (168), thus Th17/Treg balance is closely related to AS progression. A clinical study with 1251 patients suggested that P. gingivalis may regulate tryptophan and kynurenine metabolism by inhibiting indoleamine 2,3 dioxygenase (IDO) activity in antigen-presenting cells, thereby promoting Th17 and inhibiting Treg proliferation, resulting in Th17/Treg imbalance and accelerating AS progression (169), but this mechanism needs to be further confirmed by in vitro experiments ( Figure 1 ). Animal studies suggest that oral infection with P. gingivalis may promote Th17/Treg imbalance by increasing IL-6 expression in DCs, resulting in increasing plaque size and decreasing stability in AS (170). However, the role of P. gingivalis with other T cell subsets (e.g. γδ T cells, naive T cells, ApoB⁺ T cells) as well as Th cell subsets (e.g. Th9 and Th22) is unknown and needs to be further investigated in depth (12, 168).

In summary, P. gingivalis evades host immune cell killing through various pathways, survives in the host for a long time, induces a prolonged state of low inflammation (171), and provides an opportunity to promote the progression of AS. Although the molecular mechanism regarding the selective inhibition of immune elimination by P. gingivalis without suppressing the inflammatory response remains unclear, this phenomenon suggests a potentially significant threat following P. gingivalis evasion of immune killing. Therefore, targeting the inhibition or enhancement of one of the key links may provide a new strategy to enhance the body’s immunity and combat AS.

4.2 Blood circulation

P. gingivalis may enter the blood circulation locally from the oral cavity and then undergo systemic dissemination. Notably, P. gingivalis circulating with the blood may colonize the arterial endothelium, induce endothelial damage, recruit and activate platelets, promote foam cell formation and vessel wall calcification, and eventually lead to plaque rupture (172, 173) ( Figure 2 ).

Figure 2

The process of P. gingivalis promoting AS with blood circulation. (1) P. gingivalis spreads to the vascular endothelium mainly in four forms with blood circulation. (2) P. gingivalis spreads by secreting gingipains breaking intercellular junction protein, being captured and released by ECs. (3) P. gingivalis stimulates ECs to produce chemokines and EMV _pg , which recruit monocytes and induce senescence in adjacent ECs, respectively. (4) P. gingivalis mediates monocyte adhesion to the vascular endothelium. (5) P. gingivalis promotes lipid uptake and inhibits lipid efflux from subendothelial macrophages. (6) P. gingivalis activates platelets, promotes coagulation, and induces adhesion with leukocytes to form platelet-leukocyte aggregates. (7) P. gingivalis induces proliferation and calcification of VSMCs. (8) P. gingivalis induces monocytes to secrete MMP-9, promoting AS plaque rupture. (Created with BioRender.com).

4.2.1 Pathways of <italic>P. gingivalis</italic> into the blood circulation

The pathways of P. gingivalis into the blood circulation include three main parts, which are oral physical injury, disruption of interepithelial cell junctions by virulence factors, and immune escape.

Oral mucosal damage caused by physical stimuli such as daily activities (brushing, flossing) and oral treatments (periodontal therapy, tooth extraction) can lead to bacteremia (174). Inflammatory periodontal tissue swelling and bleeding states may also lead to the infiltration of oral bacteria into the bloodstream (175). P. gingivalis’ various virulence factors play an important role in disrupting gingival epithelial junctional structures. P. gingivalis gingipains degrade E-cadherin, JAM1, and ocludin, which maintain gingival epithelial integrity and barrier function (68, 176, 177). P. gingivalis LPS reduces E-cadherin expression in the gingival epithelium by inducing the production of TNF-α and ROS production reduces E-cadherin expression in the gingival epithelium (178). P. gingivalis and its LPS may lead to a dramatic decrease in the expression of endogenous grainyhead-like 2 (GRHL2), an epithelial-specific transcription factor that regulates the expression of connexins (179). The P. gingivalis that enters the bloodstream also needs to evade the killing effect of various host immune cells and immune responses before it can successfully survive and multiply in the host, triggering a persistent host inflammatory response.

Systemic dissemination can occur after P. gingivalis has successfully entered the bloodstream and evaded host immune killing. There are four ways for P. gingivalis to disseminate with the blood circulation: first, it is planktonic; second, it binds to the CR1 immune adhesion receptor on the erythrocyte membrane (180); third, it binds to the SIGN receptor on DCs and enters the DCs and survives intracellularly (181); fourth, it survives in macrophages and can enter and exit the cells repeatedly (143). P. gingivalis in the oral cavity can follow the above four ways to reach the AS lesion site ( Figure 2 ).

4.2.2 <italic>P. gingivalis</italic> induces vascular endothelial dysfunction

P. gingivalis-induced dysfunction of vascular ECs is the first step in promoting AS (182, 183). Activation and dysfunction of ECs occur in AS-prone areas when stimulated by abnormal lipids, pro-inflammatory mediators, promoting secretion of pro-adhesive cytokines (184), which in turn leads to AS. Endothelial dysfunction includes changes in tissue function of contraction, spreading, barrier (185) and phenotypic changes in ECs (184). P. gingivalis and its virulence factors induce endothelial dysfunction in three main ways ( Figure 2 ).

4.2.2.1 <italic>P. gingivalis</italic> directly disrupts the connecting proteins and barrier function between ECs

P. gingivalis gingipains directly damage the vascular endothelium by degrading the endothelial adhesion molecules PECAM-1 and VE-cadherin (186, 187). Because PECAM-1 and VE-cadherin are essential for maintaining endothelial integrity and continuity, degradation of these proteins would lead to loss of endothelial integrity, increase permeability, and increase risk of direct contact of irritant molecules with deeper tissues of the vessel wall, triggering vascular inflammation (188, 189). P. gingivalis gingipains also hydrolyze Plasminogen Activator Inhibitor-1(PAI-1) produced by ECs, which in turn delays vascular endothelial wound healing (190). In the AS study, PAI-1 promoted the expression of Vitronectin (VN) in VSMCs by binding to LDL receptor-related protein 1(LRP1) (191), which in turn induced ECs migration and regulated vascular remodeling and healing (192, 193). Then, whether P. gingivalis inhibits vascular endothelial self-healing through hydrolysis of PAI-1 remains to be investigated.

4.2.2.2 <italic>P. gingivalis</italic> affects the biological function of ECs

P. gingivalis not only enters and survives in ECs mediated by ICAM-1 but also releases from ECs and infects neighboring cells (194, 195). Repeated stimulation with P. gingivalis increases the expression of pro-inflammatory molecules (IL-6, MCP-1, GM-CSF) and vasoconstrictor molecules (Ang II) in ECs, increases monocyte adhesion to the endothelium and inhibits endothelial diastolic function (67). Similarly, a systemic Th1-type immune response occurred in mice immunized with P. gingivalis antigen, increasing the sensitivity of ECs to AngII and exacerbating the inhibition of endothelial diastolic function (196). However, the immunization method using intraperitoneal injection of P. gingivalis in this study failed to realistically mimic the natural infection state, and the mechanism of action of the Th1-type immune response and vascular endothelial sensitivity has not been fully clarified. P. gingivalis reduces NO production and inhibits endothelial diastolic function by inhibiting activation of the GSK-3β/BH4/eNOS/Nrf2 pathway in ECs (197). In addition, P. gingivalis-induced ERS occurring in ECs could both promote apoptosis and also induce an autophagic response to inhibit apoptosis (198, 199), and this paradoxical phenomenon may be related to the potential mechanism of P. gingivalis-promoting AS, but the further in-depth study is still needed.

P. gingivalis regulates the cytosolic molecules and intracellular pathways of ECs. In terms of cytosolic molecules, P. gingivalis GroEL upregulates TLR-4 expression on the cytosolic membrane of ECs, leading to hypersensitivity of ECs to P. gingivalis GroEL (50), promoting the expression of adhesion molecules (ICAM-1, VCAM-1), inducing monocyte adhesion and infiltration, and promoting AS progression (200). However, it has also been shown that TLR4 plays a protective role in AS progression (201), but the actual role of TLR4 still needs to be elucidated in the highly variable and dynamic inflammatory environment induced by P. gingivalis. Deeper studies revealed that P. gingivalis-induced inflammatory responses almost disappeared when targeted to inhibit the adapter MAL or TRAM of the Toll/IL-1 receptor (TIR) domain on ECs (202). In terms of intracellular pathways, P. gingivalis inhibits ECs proliferation, and promotes endothelial-mesenchymal transitions and apoptosis in a TLR-NF-κB axis dependent manner, compromising endothelial integrity and leading to the loss of ECs’ ability to repair themselves (203). Endothelial-mesenchymal transition means that activated ECs can be transformed into ectopic cell types, such as ECs into fibroblasts and calcified cells, promoting AS progression (204, 205). P. gingivalis LPS induces the secretion of multiple pro-inflammatory factors by macrophages in the vessel wall. These pro-inflammatory factors promote endothelial-mesenchymal transition in ECs by activating the p38-Erk1/2-p65 signaling pathway in ECs (206). In addition, P. gingivalis induces persistent oxidative stress and inflammatory responses in ECs through the NF-kB-BMAL1-NF-kB signaling loop with positive feedback (207). P. gingivalis LPS promotes the angiogenic function of endothelial progenitor cells through the Akt/FoxO1 signaling pathway (208). The enhanced angiogenic function of endothelial progenitor cells promotes AS plaque expansion and progression, as well as increases the incidence of subsequent complications such as bleeding, rupture, and thrombosis (209). Deeper studies have shown that P. gingivalis promotes mitochondrial mtDNA damage, increased mtROS production, and leads to endothelial dysfunction by inducing phosphorylation and translocation of mitochondrial dynamin-related protein (Drp1) in ECs (210).

The mortality and type of death of P. gingivalis-induced ECs were influenced by the lipid load and inflammatory status of ECs. mortality was higher in the P. gingivalis-induced ox-LDL pretreatment group than in the TNF-α pretreatment group, and apoptosis occurred mainly in the ox-LDL pretreatment group, whereas necrosis occurred mainly in the TNF-α pretreatment group. It suggests a synergistic relationship between P. gingivalis infection and AS risk factors (dyslipidemia, systemic inflammation), which together promote endothelial injury and accelerate AS progression (211). In addition, P. gingivalis stimulated ECs to produce microvesicular (EMV _Pg ) shedding, while EMV _Pg may induce the conversion of adjacent endothelium to a senescent phenotype through JNK/AKT and STAT signaling pathways, promoting endothelial injury (212). It indicates that EMV _Pg has significant autocrine pro-inflammatory properties. However, current studies are very limited, and it is expected to be a new indicator of vascular inflammation.

4.2.2.3 <italic>P. gingivalis</italic> induces migration and adhesion of immune cells to the endothelium

P. gingivalis LPS promotes vascular inflammation and promotes AS progression through the expression of the chemokine RANTES in ECs (213, 214), which can induce leukocyte infiltration to sites of inflammation and is positively correlated with plaque instability (215, 216). P. gingivalis promotes the expression of lectin-like oxidized low-density lipoprotein on the cytosol of ECs and monocytes by promoting receptor-1 (LOX-1) expression, which in turn regulates ligand expression of MCP-1, ICAM-1 and E-selectin on ECs and receptor expression of CCR2 and integrin αMβ2 on monocytes, inducing monocyte migration and adhesion to ECs (217). Similarly, P. gingivalis and its outer membrane vesicles promote the expression of chemotactic proteins (CXCL1, CXCL2, and CXCL8) and adhesion molecules (e.g. E-selectin) in ECs (218). In addition, P. gingivalis promotes the secretion of macrophage migration inhibitory factor (MIF) by ECs, while MIF binds to the CD74/CXCR4 receptor complex on ECs, increases ICAM-1 expression, and promotes monocyte-ECs adhesion (219, 220). Immune cells migrate and adhere to the endothelium and then secrete multiple inflammatory factors, inducing endothelial dysfunction and promoting AS progression.

4.2.3 <italic>P. gingivalis</italic> induces pro-coagulant effects

When vascular ECs are activated or endothelial dysfunction is present, platelets adhere to the vessel wall and are activated, releasing large amounts of chemokines that mediate the recruitment of circulating leukocytes, platelets, and coagulation factors to the vascular endothelium, promoting local inflammation and coagulation and accelerating the progression of AS (221, 222).

P. gingivalis activates and aggregates platelets by increasing the intraplatelet Ca2⁺ concentration, accelerating blood clotting and thrombosis. P. gingivalis gingipains also have a hydrolytic effect on chemokines (RANTES, MIF) released after platelet activation, inhibiting the recruitment of immune cells, preventing the clearance of P. gingivalis by immune cells, and producing persistent stimulation (223). Platelets activated by P. gingivalis express P-selectin on their surface, which binds to the receptor P-selectin glycoprotein-1 on leukocytes, forming platelet-leukocyte aggregates that not only converge a variety of leukocytes (neutrophils, monocytes) to the site of inflammation and clear bacteria but also induce a coagulation-inflammatory series of responses (224). Further studies have indicated that P. gingivalis induces increased platelet-neutrophil aggregate formation, enhances platelet-neutrophil interactions, and induces the release of NETs, which in turn promotes late thrombosis in AS (225, 226). However, no studies on the effects of P. gingivalis on other types of leukocyte-platelet interactions have been seen.

In addition, P. gingivalis virulence factors promote coagulation. P. gingivalis LPS activates platelet GTPase Cdc42 and accelerates actin assembly, which in turn induces platelet shape change and proliferation and promotes coagulation (78). P. gingivalis LPS promotes platelet secretion of platelet factor 4 (PF4), which is known to recruit immune cells and promote AS (221, 227). P. gingivalis gingipains promote P-selectin expression in platelets, which in turn promotes the adhesion of leukocytes and platelets to the endothelium, thereby promoting AS progression (228) ( Figure 2 ).

4.2.4 <italic>P. gingivalis</italic> induces foam cell formation

Macrophages are capable of uptake and clearance of modified lipoproteins. P. gingivalis increases intracellular lipid accumulation by interfering with lipid metabolic processes in macrophages and promotes the conversion of macrophages into “foam cells” (229, 230). The formation and accumulation of subendothelial foam cells is a key process in the formation of AS (142). The mechanism of P. gingivalis-induced foam cell formation is divided into three main parts ( Figure 2 ):

4.2.4.1 <italic>P. gingivalis</italic> induces lipid modification or peroxidation

P. gingivalis gingipains induce lipid modification and peroxidation of LDL/VLDL through hydrolysis of ApoE and ApoB-100 and enhancement of oxidative stress pathways (231, 232), while LDL receptors in the liver do not recognize modified LDL/VLDL, resulting in circulating LDL/VLDL is not cleared and continues to accumulate, promoting elevated lipids (233). Similarly, Pep19, a peptide derived from P. gingivalis GroEL, can also induce LDL peroxidation (234). P. gingivalis can also induce oxidation of HDL, where the oxidized HDL not only loses its protective function against AS but also promotes the release of TNF-α and MMP-9 from monocytes, triggering a pro-inflammatory response (235). An increase in circulating modified or peroxidized lipids is an important prerequisite for triggering foam cells, and macrophage cells initiate repair mechanisms to increase the uptake of lipids (142).

4.2.4.2 <italic>P. gingivalis</italic> promotes lipid uptake by macrophages

Macrophage uptake of lipids is positively correlated with the number and function of scavenger receptors (CD36/SR-B2) (236). P. gingivalis promotes lipid uptake through the trans-activation of the CD36 promoter via the ERK/NF-κB pathway, which in turn upregulates CD36 expression in macrophages (237). In addition, P. gingivalis released large amounts of IL-1β in the form of activated CD36/SR-B2-TLR2, which in turn promoted lipid uptake by macrophages (238). Interestingly, the study also showed that IL-1β produced by P. gingivalis-activated CD36/SR-B2-TLR2 promoted cell pyroptosis, while ox-LDL inhibited IL-1β production and prevented cell pyroptosis in a CD36/SR-B2-dependent manner. Thus, macrophages in the vessel wall were stimulated by multiple stimuli of P. gingivalis LPS, ox-LDL, and IL-1β to increase lipid uptake and promote foam cell formation, but at the same time foam cells in the vessel wall were allowed to persist because pyroptosis was inhibited (238). This study provides a comprehensive analysis of the complex mechanisms underlying foam cell formation and survival in the vessel wall, suggesting that CD36/SR-B2 plays a diverse role in P. gingivalis-mediated AS and may be one of the important targets for regulating AS.

It was also found that the cytosolic mechanosensitive channel TRPV4 plays a key role in mediating P. gingivalis-promoted lipid uptake by macrophages. Under the stimulation of P. gingivalis LPS, the activity of the mechanosensitive channel TRPV4 in macrophages was significantly increased, the Ca²⁺ internal channel was activated, and the uptake of ox-LDL was increased. And this process was independent of the CD36 expression level (239). It is suggested that TRPV4 is another important uptake pathway independent of the scavenger receptor.

In addition, P. gingivalis can also affect the expression and function of fatty acid binding proteins in macrophages. It was shown that P. gingivalis upregulates the expression of fatty acid binding protein 4 (FABP4) through activation of the JNK pathway and forms a positive feedback loop that promotes lipid uptake and increases intracellular lipid accumulation by macrophages (240, 241).

4.2.4.3 <italic>P. gingivalis</italic> inhibits lipid efflux from macrophages

P. gingivalis LPS promotes lipid accumulation in macrophages by activating the JNK-c-Jun/AP-1 pathway to up-regulate CD36 (lipid uptake) expression, while down-regulating ATP-binding cassette transporterA1 (lipid efflux) expression by enhancing calpain activity (230). Secondly, P. gingivalis may inhibit cholesterol efflux by activating NF-κB and JNK signaling pathways, which in turn upregulates lysosomal integral membrane protein 2 (LIMP2) expression levels in macrophages (242). In addition, P. gingivalis inhibited the activity of cholesterol efflux-related enzymes (ABCG1 and CYP46A1) and promoted lipid accumulation in macrophages by enhancing Ca²⁺ signaling and promoting ROS production (243). Current studies on the inhibition of lipid efflux from macrophages by P. gingivalis are relatively limited. It mainly involves the functions of membrane transport proteins and receptors, and related enzymes, and its effects are attributed to the triggering and persistence of inflammatory signaling pathways.

4.2.5 <italic>P. gingivalis</italic> induces vascular calcification

Vascular calcification is the pathological deposition of hydroxyapatite minerals in the vascular system in the vessel wall, which in turn promotes AS progression. VSMCs are the key cell type involved in vascular calcification and exhibit phenotypic conversion. Various immune cells infiltrate the lesion in the early stages of AS formation, producing pro-inflammatory factors and regulatory molecules that induce the migration of contractile phenotype VSMCs, originally located in the interstitial layer, to the intimal layer and convert to a synthetic phenotype that contributes to the deposition of hydroxyapatite minerals in the vessel wall (244). VSMCs of the synthetic phenotype in the intimal layer are the first cells to appear at the site of impending AS lesions (245).

P. gingivalis promotes calcium deposition in VSMCs and promotes the transdifferentiation of VSMCs to osteoblast-like cells (246). It is hypothesized that various inflammatory cytokines (TNF-α, IL-β) induced by P. gingivalis promote vascular calcification by upregulating the expression of osteogenic-related genes (ALP, RUNX2) in VSMCs (247, 248), but further validation is needed. In addition, different virulence factors of P. gingivalis also play an important role in inducing vascular calcification. P. gingivalis LPS stimulates VSMCs proliferation and calcification, leading to vascular calcification (249). P. gingivalis gingipains induce VSMCs proliferation and conversion to synthetic type, increase bone bridge protein (OPN) expression, and promote vascular calcification (250). P. gingivalis OMVs promote vascular calcification by activating the ERK1/2- Runx2 signaling pathway to promote calcification in VSMCs (251).

In recent years, some studies using complex cell models to simulate the complex environment in vivo have also emerged. P. gingivalis LPS promoted calcification in VSMCs co-cultured with human periodontal ligament cells. This study indicates that the calcification effect is not only derived from the stimulation of P. gingivalis LPS, but also the secretion of various pro-inflammatory factors by P. gingivalis LPS-stimulated human periodontal ligament cells (252). This study somewhat mimics the in vivo environment in which periodontitis and cardiovascular disease coexist. There is also one that simulates the relationship between P. gingivalis and the calcification of VSMCs under hyperglycemic conditions. Under hyperglycemic conditions, P. gingivalis enhanced smad1/5/8-runx2 signaling by activating TLR-4 and ERK1/2-p38 signaling and promoting bone morphogenetic protein 4 (BMP4) autocrine regulation, which in turn induced calcification in VSMCs (253) ( Figure 2 ).

4.2.6 <italic>P. gingivalis</italic> promotes plaque rupture

When AS is advanced, immune cells recruited by P. gingivalis infiltrate the vessel wall and secrete MMPs, such as MMP-1 and MMP-9, which degrade the collagen fibers of the plaque fibrous cap, leading to plaque rupture and bleeding (254).

P. gingivalis Mfa-1(short or minor fimbriae) induces differentiation of blood monocytes into DCs and promotes the expression of MMP-9 which in turn increases the risk of plaque rupture (255). Similarly, P. gingivalis LPS promoted MMP-9 expression and activity in monocytes (256). In addition, P. gingivalis gingipains hydrolyze the complement component C5, leading to local accumulation of C5a accumulation (114, 257). C5a is the only biologically active fragment following the action of P. gingivalis gingipains that induces increased expression of MMP1 and MMP9 in macrophages in plaques (114, 118), leading to degradation of the extracellular matrix and rupture of plaques (123). Studies on the promotion of AS plaque rupture by P. gingivalis are scarce and remain to be investigated ( Figure 2 ).

4.3 Lymphatic circulation

The initial lymphatic vessels, the beginning segment of the lymphatic tract, lacking continuous basement membrane and perivascular wall cells, may serve as an ideal pathway for pathogen transmission through the lymphatic circulation (258–260). P. gingivalis may enter the submandibular and submental lymph nodes through the initial lymphatic vessels, and they may subsequently drain down the superficial/deep jugular lymph nodes to the jugular venous trunk for further metastasis to more distant organs, such as AS plaques, liver, etc (261). P. gingivalis that circulates with lymph may accelerate AS progression by inhibiting T cell and B cell activation and cholesterol reversal of transport function and promoting Th17/Treg imbalance in the spleen.

4.3.1 <italic>P. gingivalis</italic> inhibits the immune function of the lymphatic system

DCs, as the cells with the highest antigen-presenting capacity, are important for the activation of T and B cells in the lymphatic system. P. gingivalis gingipains hydrolyze the chemokine CCL21 in periodontal tissue and inhibit the entry of DCs into the initial lymphatic vessels (262, 263), which in turn reduces the activation of T and B cells in the lymphatic system by DCs (264). At the same time, P. gingivalis enters and survives in DCs by binding to SIGN receptors on DCs through its fimbriae, which helps P. gingivalis evade immune killing by the lymphatic system and promotes AS progression (255). P. gingivalis that survives in DCs does not affect CCR7 expression on the cytosol, but significantly upregulates CXCR4 expression (265). CCR7 mediates the homing of DCs to secondary lymphoid organs, whereas CXCR4 mediates the migration of DCs to sites of active vascular remodeling, such as AS (266). Thus, P. gingivalis may “hijack” DCs and enrich intracellular P. gingivalis-containing DCs in inflammatory vascular sites.

E. coli LPS can impair the recruitment of immune cells (DCs, macrophages) associated with lymphatic vessels and reduce the contractility of lymphatic vessels, affecting the function of the lymphatic pump (267). However, whether P. gingivalis LPS has similar functions has not been reported and needs to be urgently investigated.

4.3.2 <italic>P. gingivalis</italic> attenuates the cholesterol reversal function of lymphatic vessels

Lymphatic vessels can efficiently reverse cholesterol transport from multiple tissues (268), including the arterial wall, a process that is positively dependent on HDL uptake and transport by scavenger receptor class B type I (SR-BI) on lymphatic ECs (269). The density of capillary lymphatic vessels present in AS lesions increase with plaque progression (270), and proliferating capillary lymphatic vessels may inhibit AS progression by reversing cholesterol transport (271). P. gingivalis may generate large amounts of ROS by interfering with the function of the mitochondrial respiratory chain, leading to endoplasmic reticulum stress (ERS). Subsequently, it triggers an unfolded protein response (UPR), which promotes CHOP gene expression and suppresses SR-BI expression (272–274). This in turn inhibits the process of cholesterol reversal in the arterial wall and accelerates the progression of AS. However, there is a lack of direct studies on the inhibition of SR-BI expression on lymphoid ECs by P. gingivalis.

SR-BI is present in the liver, macrophages, and ECs. In addition to its function of uptake and transport of HDL, SR-BI also has an induced anti-inflammatory effect (275). For example, SR-BI binding to HDL inhibits the NF-κB pathway, decreases the inflammatory response of macrophages to LPS, and significantly reduces the secretion of various pro-inflammatory factors (276). However, the role of SR-BI in P. gingivalis promoting AS and its mechanism need further study.

4.3.3 <italic>P. gingivalis</italic> induces Th17/Treg imbalance in the spleen

The spleen is a peripheral lymphoid organ dominated by T cells and B cells, and is the center of cellular and humoral immunity in the body. (277). Among them, Th17 promotes AS progression, while Treg inhibits AS progression. Therefore, Th17/Treg balance can control inflammation and may play an important role in plaque stability (278).

The DNA genome of P. gingivalis can be found in the spleen of Apoe^shl mice orally infected with P. gingivalis (47), and P. gingivalis promotes Th17 proliferation and differentiation by upregulating the expression of IL-6 in DCs in the spleen, leading to Th17/Treg imbalance, increasing plaque area and decreasing plaque stability (170). Intravenous administration of P. gingivalis to ApoE^-/- mice showed a significant increase in Th17 and Th17-related molecules in the spleen and heart, as well as a significant increase in AS plaque area (279). In addition, P. gingivalis LPS did not induce the expression of NK cell CD69 in the spleen (280), which in turn promoted Th17 differentiation and inhibited Treg differentiation, leading to Th17/Treg imbalance (281), but the mechanism needs to be further investigated.

5 Conclusion and outlook

In recent years, the relationship between P. gingivalis and AS has received increasing attention. P. gingivalis can occur immune escape, promote local inflammation and plaque formation in blood vessels, inhibit immune defense and cholesterol transport function of the lymphatic system, and promote the progression of AS. This paper summarizes the recent research results related to the promotion of AS by P. gingivalis through immune response and provides new insights to further reveal the potential mechanisms and associations between P. gingivalis and AS.

In addition, this paper shows the different cell subpopulations associated with AS discovered by single-cell sequencing technology in recent years, which updates the understanding of the nature and function of cell subpopulations in AS. It provides the conditions to precisely grasp the cellular level of AS pathogenesis. However, unfortunately, single-cell sequencing studies on P. gingivalis and AS have not been reported yet. It is believed that shortly, the use of single-cell sequencing technology will certainly provide important theoretical support for the prevention and treatment of P. gingivalis to accelerate the progression of AS.

Author contributions

QR and PG wrote the manuscript. WQ, JL, MX, LX and SZ made the figures and edited the manuscript. DM, and JN administrated and supervised the whole research project. All authors have read and agreed to the published version of the manuscript. All authors contributed to the article and approved the submitted version.

Funding

This work was supported by National Natural Science Foundation of China (No. 81970930), Chinese Medicine Research Projects in Guangdong Province (No.20222144), Hygiene and Health Appropriate Technology Promotion Project in Guangdong Province (No. 202106241649075233), The Research Incubation Program of Southern Medical University Dental Hospital (No. PY2021015), Postdoctoral Research Fund of Southern Medical University Dental Hospital (No. PY2018031).

Acknowledgments

Figures were created with BioRender software (https://biorender.com/).

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

References 1 Reyes

. Porphyromonas gingivalis. Trends Microbiol (2021) 29(4):376–7. doi: 10.1016/j.tim.2021.01.010 2 Olsen

Lambris

Hajishengallis

. Porphyromonas gingivalis disturbs host-commensal homeostasis by changing complement function. J Oral Microbiol (2017) 9(1):1340085. doi: 10.1080/20002297.2017.1340085 3 Chopra

Bhat

Sivaraman

. Porphyromonas gingivalis adopts intricate and unique molecular mechanisms to survive and persist within the host: a critical update. J Oral Microbiol (2020) 12(1):1801090. doi: 10.1080/20002297.2020.1801090 4 Jia

Han

Guo

Luo

Liu

. Pathogenesis of important virulence factors of porphyromonas gingivalis via toll-like receptors. Front Cell Infect Microbiol (2019) 9:262. doi: 10.3389/fcimb.2019.00262 5 Olsen

Singhrao

. Importance of heterogeneity in porhyromonas gingivalis lipopolysaccharide lipid a in tissue specific inflammatory signalling. J Oral Microbiol (2018) 10(1):1440128. doi: 10.1080/20002297.2018.1440128 6 Lunar Silva

Cascales

. Molecular strategies underlying porphyromonas gingivalis virulence. J Mol Biol (2021) 433(7):166836. doi: 10.1016/j.jmb.2021.166836 7 Xie

. Biogenesis and function of porphyromonas gingivalis outer membrane vesicles. Future Microbiol (2015) 10(9):1517–27. doi: 10.2217/fmb.15.63 8 Carter

France

Crean

Singhrao

. The porphyromonas gingivalis/Host interactome shows enrichment in GWASdb genes related to alzheimer's disease, diabetes and cardiovascular diseases. Front Aging Neurosci (2017) 9:408. doi: 10.3389/fnagi.2017.00408 9 Cochain

Vafadarnejad

Arampatzi

Pelisek

Winkels

Ley

. Single-cell RNA-seq reveals the transcriptional landscape and heterogeneity of aortic macrophages in murine atherosclerosis. Circ Res (2018) 122(12):1661–74. doi: 10.1161/CIRCRESAHA.117.312509 10 Willemsen

de Winther

. Macrophage subsets in atherosclerosis as defined by single-cell technologies. J Pathol (2020) 250(5):705–14. doi: 10.1002/path.5392 11 Winkels

Ehinger

Vassallo

Buscher

Dinh

Kobiyama

. Atlas of the immune cell repertoire in mouse atherosclerosis defined by single-cell RNA-sequencing and mass cytometry. Circ Res (2018) 122(12):1675–88. doi: 10.1161/CIRCRESAHA.117.312513 12 Winkels

Wolf

. Heterogeneity of T cells in atherosclerosis defined by single-cell RNA-sequencing and cytometry by time of flight. Arterioscler Thromb Vasc Biol (2021) 41(2):549–63. doi: 10.1161/ATVBAHA.120.312137 13 Pan

Xue

Auerbach

Fan

Bashore

Cui

. Single-cell genomics reveals a novel cell state during smooth muscle cell phenotypic switching and potential therapeutic targets for atherosclerosis in mouse and human. Circulation (2020) 142(21):2060–75. doi: 10.1161/CIRCULATIONAHA.120.048378 14 Alsaigh

Evans

Frankel

Torkamani

. Decoding the transcriptome of calcified atherosclerotic plaque at single-cell resolution. Commun Biol (2022) 5(1):8–9. doi: 10.1038/s42003-022-04056-7 15 Xu

Zhou

Cheng

Xiang

. Identifying potential signatures for atherosclerosis in the context of predictive, preventive, and personalized medicine using integrative bioinformatics approaches and machine-learning strategies. EPMA J (2022) 13(3):433–49. doi: 10.1007/s13167-022-00289-y 16 Qin

Gan

Liang

Lai

Dai

. Identification of monocyte-associated genes related to the instability of atherosclerosis plaque. Oxid Med Cell Longev (2022) 2022:3972272. doi: 10.1155/2022/3972272 17 Czerniuk

Surma

Romanczyk

Nowak

Wojtowicz

Filipiak

. Unexpected relationships: Periodontal diseases: Atherosclerosis-plaque destabilization? from the teeth to a coronary event. Biol (Basel) (2022) 11(2):4–7. doi: 10.3390/biology11020272 18 Zhang

Xie

Huang

Chen

Yin

. The effects of porphyromonas gingivalis on atherosclerosis-related cells. Front Immunol (2021) 12:766560. doi: 10.3389/fimmu.2021.766560 19 Lockhart

Bolger

Papapanou

Osinbowale

Trevisan

Levison

. Periodontal disease and atherosclerotic vascular disease: Does the evidence support an independent association?: a scientific statement from the American heart association. Circulation (2012) 125(20):2520–44. doi: 10.1161/CIR.0b013e31825719f3 20 Chhibber-Goel

Singhal

Bhowmik

Vivek

Parakh

Bhargava

. Linkages between oral commensal bacteria and atherosclerotic plaques in coronary artery disease patients. NPJ Biofilms Microbiomes (2016) 2:7. doi: 10.1038/s41522-016-0009-7 21 Pavlic

Peric

Kalezic

Madi

Bhat

Brkic

. Identification of periopathogens in atheromatous plaques obtained from carotid and coronary arteries. BioMed Res Int (2021) 2021:9986375. doi: 10.1155/2021/9986375 22 Brun

Nuzzo

Prouvost

Diallo

Hamdan

Meseguer

. Oral microbiota and atherothrombotic carotid plaque vulnerability in periodontitis patients. A cross-sectional study. J Periodontal Res (2021) 56(2):339–50. doi: 10.1111/jre.12826 23 Mougeot

Stevens

Paster

Brennan

Lockhart

Mougeot

. Porphyromonas gingivalis is the most abundant species detected in coronary and femoral arteries. J Oral Microbiol (2017) 9(1):1281562. doi: 10.1080/20002297.2017.1281562 24 Kregielczak

Dorocka-Bobkowska

Slomski

Oszkinis

Krasinski

. Periodontal status and the incidence of selected bacterial pathogens in periodontal pockets and vascular walls in patients with atherosclerosis and abdominal aortic aneurysms. PloS One (2022) 17(8):e0270177. doi: 10.1371/journal.pone.0270177 25 Kozarov

. Bacterial invasion of vascular cell types: Vascular infectology and atherogenesis. Future Cardiol (2012) 8(1):123–38. doi: 10.2217/fca.11.75 26 Papapanou

Neiderud

Disick

Lalla

Miller

Dahlen

. Longitudinal stability of serum immunoglobulin G responses to periodontal bacteria. J Clin Periodontol (2004) 31(11):985–90. doi: 10.1111/j.1600-051X.2004.00599.x 27 Ramirez

Parra

Gutierrez

Arce

Jaramillo

Ariza

. Biomarkers of cardiovascular disease are increased in untreated chronic periodontitis: a case control study. Aust Dent J (2014) 59(1):29–36. doi: 10.1111/adj.12139 28 Tonetti

D'Aiuto

Nibali

Donald

Storry

Parkar

. Treatment of periodontitis and endothelial function. N Engl J Med (2007) 356(9):911–20. doi: 10.1056/NEJMoa063186 29 Saffi

MAL

Rabelo-Silva

Polanczyk

Furtado

Montenegro

Ribeiro

IWJ

. Periodontal therapy and endothelial function in coronary artery disease: A randomized controlled trial. Oral Dis (2018) 24(7):1349–57. doi: 10.1111/odi.12909 30 Park

Kim

Kang

Yoon

Lee

Yun

. Improved oral hygiene care attenuates the cardiovascular risk of oral health disease: A population-based study from Korea. Eur Heart J (2019) 40(14):1138–45. doi: 10.1093/eurheartj/ehy836 31 Sen

Giamberardino

Moss

Morelli

Rosamond

Gottesman

. Periodontal disease, regular dental care use, and incident ischemic stroke. Stroke (2018) 49(2):355–62. doi: 10.1161/STROKEAHA.117.018990 32 Holmlund

Lampa

Lind

. Poor response to periodontal treatment may predict future cardiovascular disease. J Dent Res (2017) 96(7):768–73. doi: 10.1177/0022034517701901 33 Lakio

Antinheimo

Paju

Buhlin

Pussinen

Alfthan

. Tracking of plasma antibodies against aggregatibacter actinomycetemcomitans and porphyromonas gingivalis during 15 years. J Oral Microbiol (2009) 1:6–7. doi: 10.3402/jom.v1i0.1979 34 Yang

Liu

Huang

Xie

. Porphyromonas gingivalis infection reduces regulatory T cells in infected atherosclerosis patients. PLoS One (2014) 9(1):e86599. doi: 10.1371/journal.pone.0086599 35 Joshi

Bapat

Anderson

Dawson

Cherukara

Hijazi

. Serum antibody response against periodontal bacteria and coronary heart disease: Systematic review and meta-analysis. J Clin Periodontol (2021) 48(12):1570–86. doi: 10.1111/jcpe.13550 36 Liljestrand

Paju

Pietiainen

Buhlin

Persson

Nieminen

. Immunologic burden links periodontitis to acute coronary syndrome. Atherosclerosis (2018) 268:177–84. doi: 10.1016/j.atherosclerosis.2017.12.007 37 Teeuw

Slot

Susanto

Gerdes

Abbas

D'Aiuto

. Treatment of periodontitis improves the atherosclerotic profile: A systematic review and meta-analysis. J Clin Periodontol (2014) 41(1):70–9. doi: 10.1111/jcpe.12171 38 Li

Tse

Yiu

Zhang

Jin

. Periodontal therapy decreases serum levels of adipocyte fatty acid-binding protein in systemically healthy subjects: A pilot clinical trial. J Periodontal Res (2013) 48(3):308–14. doi: 10.1111/jre.12009 39 Fu

Gong

Yang

. Effects of periodontal therapy on serum lipid profile and proinflammatory cytokines in patients with hyperlipidemia: A randomized controlled trial. Clin Oral Investig (2016) 20(6):1263–9. doi: 10.1007/s00784-015-1621-2 40 D'Aiuto

Gkranias

Bhowruth

Khan

Orlandi

Suvan

. Systemic effects of periodontitis treatment in patients with type 2 diabetes: A 12 month, single-centre, investigator-masked, randomised trial. Lancet Diabetes Endocrinol (2018) 6(12):954–65. doi: 10.1016/S2213-8587(18)30038-X 41 Aarabi

Eberhard

Reissmann

Heydecke

Seedorf

. Interaction between periodontal disease and atherosclerotic vascular disease–fact or fiction? Atherosclerosis (2015) 241(2):555–60. doi: 10.1016/j.atherosclerosis.2015.04.819 42 Miyauchi

Maekawa

Aoki

Miyazawa

Tabeta

Nakajima

. Oral infection with porphyromonas gingivalis and systemic cytokine profile in C57BL/6. KOR-ApoE shl mice J Periodontal Res (2012) 47(3):402–8. doi: 10.1111/j.1600-0765.2011.01441.x 43 Pereira

Vasquez

Stefanon

Meyrelles

. Oral p. gingivalis infection alters the vascular reactivity in healthy and spontaneously atherosclerotic mice. Lipids Health Dis (2011) 10:80. doi: 10.1186/1476-511X-10-80 44 Parvaneh

Witting

Moradi

Eroglu

Freedman

. Periodontitis induces endothelial dysfunction in mice. Sci Rep (2021) 11(1):14993. doi: 10.1038/s41598-021-94418-8 45 Velsko

Chukkapalli

Rivera

Lee

Chen

Zheng

. Active invasion of oral and aortic tissues by porphyromonas gingivalis in mice causally links periodontitis and atherosclerosis. PLoS One (2014) 9(5):e97811. doi: 10.1371/journal.pone.0097811 46 Chukkapalli

Velsko

Rivera-Kweh

Zheng

Lucas

Kesavalu

. Polymicrobial oral infection with four periodontal bacteria orchestrates a distinct inflammatory response and atherosclerosis in ApoE null mice. PLoS One (2015) 10(11):e0143291. doi: 10.1371/journal.pone.0143291 47 Yamaguchi

Kurita-Ochiai

Kobayashi

Suzuki

Ando

. Activation of the NLRP3 inflammasome in porphyromonas gingivalis-accelerated atherosclerosis. Pathog Dis (2015) 73(4):1–7. doi: 10.1093/femspd/ftv011 48 Hokamura

Inaba

Nakano

Nomura

Yoshioka

Taniguchi

. Molecular analysis of aortic intimal hyperplasia caused by porphyromonas gingivalis infection in mice with endothelial damage. J Periodontal Res (2010) 45(3):337–44. doi: 10.1111/j.1600-0765.2009.01242.x 49 Shiheido

Maejima

Suzuki

Aoyama

Kaneko

Watanabe

. Porphyromonas gingivalis, a periodontal pathogen, enhances myocardial vulnerability, thereby promoting post-infarct cardiac rupture. J Mol Cell Cardiol (2016) 99:123–37. doi: 10.1016/j.yjmcc.2016.03.017 50 Huang

Shih

Tsao

Lin

Shih

Chiang

. The GroEL protein of porphyromonas gingivalis regulates atherogenic phenomena in endothelial cells mediated by upregulating toll-like receptor 4 expression. Am J Transl Res (2016) 8(2):384–404. 51 Xuan

Shi

Liu

Luan

Cai

. Porphyromonas gingivalis Infection Accelerates Atherosclerosis Mediated by Oxidative Stress and Inflammatory Responses in ApoE-/- Mice. Clin Lab (2017) 63(10):1627–37. doi: 10.7754/Clin.Lab.2017.170410 52 Xuan

Cai

Wang

Shi

Qiu

Luan

. [Effect of porphyromonas gingivalis infection on atherosclerosis in apolipoprotein-e knockout mice]. Beijing Da Xue Xue Bao Yi Xue Ban (2020) 52(4):743–9. doi: 10.19723/j.issn.1671-167X.2020.04.028 53 Hagiwara

Kurita-Ochiai

Kobayashi

Hashizume-Takizawa

Yamazaki

Yamamoto

. Sublingual vaccine with GroEL attenuates atherosclerosis. J Dent Res (2014) 93(4):382–7. doi: 10.1177/0022034514523784 54 Kyrklund

Kummu

Kankaanpaa

Akhi

Nissinen

Turunen

. Immunization with gingipain a hemagglutinin domain of porphyromonas gingivalis induces IgM antibodies binding to malondialdehyde-acetaldehyde modified low-density lipoprotein. PLoS One (2018) 13(1):e0191216. doi: 10.1371/journal.pone.0191216 55 Joo

Cha

Kim

Lee

Choi

. Atheroprotective nasal immunization with a heat shock protein 60 peptide from porphyromonas gingivalis. J Periodontal Implant Sci (2020) 50(3):159–70. doi: 10.5051/jpis.2020.50.3.159 56 Ha

Kim

Han

Sung

Seo

. Anti-atherosclerotic vaccination against porphyromonas gingivalis as a potential comparator of statin in mice. PeerJ (2021) 9:e11293. doi: 10.7717/peerj.11293 57 Kato

Yamazaki

Nakajima

Date

Kikuchi

Hase

. Oral administration of porphyromonas gingivalis alters the gut microbiome and serum metabolome. mSphere (2018) 3(5):1–9. doi: 10.1128/mSphere.00460-18 58 Qian

Zhang

Sun

. Update on gut microbiota in cardiovascular diseases. Front Cell Infect Microbiol (2022) 12:1059349. doi: 10.3389/fcimb.2022.1059349 59 Tang

Wang

Levison

Koeth

Britt

. Intestinal microbial metabolism of phosphatidylcholine and cardiovascular risk. N Engl J Med (2013) 368(17):1575–84. doi: 10.1056/NEJMoa1109400 60 Wang

Roberts

Buffa

Levison

Zhu

Org

. Non-lethal inhibition of gut microbial trimethylamine production for the treatment of atherosclerosis. Cell (2015) 163(7):1585–95. doi: 10.1016/j.cell.2015.11.055 61 Wang

Klipfell

Bennett

Koeth

Levison

Dugar

. Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease. Nature (2011) 472(7341):57–63. doi: 10.1038/nature09922 62 Liu

Han

Yang

. Trimethylamine-n-oxide (TMAO) increased aquaporin-2 expression in spontaneously hypertensive rats. Clin Exp Hypertens (2019) 41(4):312–22. doi: 10.1080/10641963.2018.1481420 63 Seldin

Meng

Zhu

Wang

Hazen

. Trimethylamine n-oxide promotes vascular inflammation through signaling of mitogen-activated protein kinase and nuclear factor-κB. J Am Heart Assoc (2016) 5(2):1. doi: 10.1161/JAHA.115.002767 64 Ke

Zhao

Liu

Zeng

. Gut flora-dependent metabolite trimethylamine-n-oxide accelerates endothelial cell senescence and vascular aging through oxidative stress. Free Radic Biol Med (2018) 116:88–100. doi: 10.1016/j.freeradbiomed.2018.01.007 65 Zhu

Gregory

Org

Buffa

Gupta

Wang

. Gut microbial metabolite TMAO enhances platelet hyperreactivity and thrombosis risk. Cell (2016) 165(1):111–24. doi: 10.1016/j.cell.2016.02.011 66 Roth

Moser

Roth-Walter

Giacona

Harja

Papapanou

. Infection with a periodontal pathogen increases mononuclear cell adhesion to human aortic endothelial cells. Atherosclerosis (2007) 190(2):271–81. doi: 10.1016/j.atherosclerosis.2006.03.018 67 Viafara-Garcia

Morantes

Chacon-Quintero

Castillo

Lafaurie

Buitrago

. Repeated porphyromonas gingivalis W83 exposure leads to release pro-inflammatory cytokynes and angiotensin II in coronary artery endothelial cells. Sci Rep (2019) 9(1):19379. doi: 10.1038/s41598-019-54259-y 68 Takeuchi

Sasaki

Yamaga

Kuboniwa

Matsusaki

Amano

. Porphyromonas gingivalis induces penetration of lipopolysaccharide and peptidoglycan through the gingival epithelium via degradation of junctional adhesion molecule 1. PLoS Pathog (2019) 15(11):e1008124. doi: 10.1371/journal.ppat.1008124 69 Wilensky

Tzach-Nahman

Potempa

Shapira

Nussbaum

. Porphyromonas gingivalis gingipains selectively reduce CD14 expression, leading to macrophage hyporesponsiveness to bacterial infection. J Innate Immun (2015) 7(2):127–35. doi: 10.1159/000365970 70 Carlisle

Srikantha

Brogden

. Degradation of human alpha- and beta-defensins by culture supernatants of porphyromonas gingivalis strain 381. J Innate Immun (2009) 1(2):118–22. doi: 10.1159/000181015 71 Potempa

Banbula

Travis

. Role of bacterial proteinases in matrix destruction and modulation of host responses. Periodontol (2000) 2000:24:153–92. doi: 10.1034/j.1600-0757.2000.2240108.x 72 Liang

Krauss

Domon

McIntosh

Hosur

. The C5a receptor impairs IL-12-dependent clearance of porphyromonas gingivalis and is required for induction of periodontal bone loss. J Immunol (2011) 186(2):869–77. doi: 10.4049/jimmunol.1003252 73 Hajishengallis

Lambris

. Complement and dysbiosis in periodontal disease. Immunobiology (2012) 217(11):1111–6. doi: 10.1016/j.imbio.2012.07.007 74 Xu

Zhou

Wang

Liang

. Roles of porphyromonas gingivalis and its virulence factors in periodontitis. Adv Protein Chem Struct Biol (2020) 120:45–84. doi: 10.1016/bs.apcsb.2019.12.001 75 Veloso

Fernández

Astorga

González-Quintanilla

Castro

Escobar

. Lipopolysaccharide from porphyromonas gingivalis, but not from porphyromonas endodontalis, induces macrophage M1 profile. Int J Mol Sci (2022) 23(17):1. doi: 10.3390/ijms231710011 76 Li

Cai

Qiao

Jiang

Wang

. The effect of porphyromonas gingivalis lipopolysaccharide on the pyroptosis of gingival fibroblasts. Inflammation (2021) 44(3):846–58. doi: 10.1007/s10753-020-01379-7 77 Lv

Zeng

Zhang

. Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) influences adipocytes injuries through triggering XBP1 and activating mitochondria-mediated apoptosis. Adipocyte (2021) 10(1):28–37. doi: 10.1080/21623945.2020.1856527 78 Senini

Amara

Paul

Kim

. Porphyromonas gingivalis lipopolysaccharide activates platelet Cdc42 and promotes platelet spreading and thrombosis. J Periodontol (2019) 90(11):1336–45. doi: 10.1002/JPER.18-0596 79 Wielento

Bereta

Łagosz-Ćwik

Eick

Lamont

Grabiec

. TLR2 activation by porphyromonas gingivalis requires both PPAD activity and fimbriae. Front Immunol (2022) 13:823685. doi: 10.3389/fimmu.2022.823685 80 Hajishengallis

Shakhatreh

Wang

Liang

. Complement receptor 3 blockade promotes IL-12-mediated clearance of porphyromonas gingivalis and negates its virulence in vivo. J Immunol (2007) 179(4):2359–67. doi: 10.4049/jimmunol.179.4.2359 81 Hajishengallis

Wang

Liang

Triantafilou

. Pathogen induction of CXCR4/TLR2 cross-talk impairs host defense function. Proc Natl Acad Sci U S A (2008) 105(36):13532–7. doi: 10.1073/pnas.0803852105 82 Hajishengallis

McIntosh

Nishiyama

Yoshimura

. Mechanism and implications of CXCR4-mediated integrin activation by porphyromonas gingivalis. Mol Oral Microbiol (2013) 28(4):239–49. doi: 10.1111/omi.12021 83 Takahashi

Cueno

Kamio

Iinuma

Hasegawa

Imai

. Porphyromonas gingivalis Mfa1 fimbria putatively binds to TLR2 and induces both IL-6 and IL-8 production in human bronchial epithelial cells. Biochem Biophys Res Commun (2022) 589:35–40. doi: 10.1016/j.bbrc.2021.12.003 84 Takayanagi

Kikuchi

Hasegawa

Naiki

Goto

Okada

. Porphyromonas gingivalis Mfa1 induces chemokine and cell adhesion molecules in mouse gingival fibroblasts via toll-like receptors. J Clin Med (2020) 9(12):1. doi: 10.3390/jcm9124004 85 El-Awady

Miles

Scisci

Kurago

Palani

Arce

. Porphyromonas gingivalis evasion of autophagy and intracellular killing by human myeloid dendritic cells involves DC-SIGN-TLR2 crosstalk. PLoS Pathog (2015) 10(2):e1004647. doi: 10.1371/journal.ppat.1004647 86 Libby

. Inflammation in atherosclerosis. Nature (2002) 420(6917):868–74. doi: 10.1038/nature01323 87 Zhu

Xian

Wang

Chen

Han

. Research progress on the relationship between atherosclerosis and inflammation. Biomolecules (2018) 8(3):1. doi: 10.3390/biom8030080 88 Tabas

García-Cardeña

Owens

. Recent insights into the cellular biology of atherosclerosis. J Cell Biol (2015) 209(1):13–22. doi: 10.1083/jcb.201412052 89 Libby

Buring

Badimon

Hansson

Deanfield

Bittencourt

. Atherosclerosis. Nat Rev Dis Primers (2019) 5(1):56. doi: 10.1038/s41572-019-0106-z 90 Swirski

Nahrendorf

Libby

. Mechanisms of myeloid cell modulation of atherosclerosis. Microbiol Spectr (2016) 4(4):3. doi: 10.1128/microbiolspec.MCHD-0026-2015 91 Geovanini

Libby

. Atherosclerosis and inflammation: overview and updates. Clin Sci (Lond) (2018) 132(12):1243–52. doi: 10.1042/CS20180306 92 Libby

. Inflammation in atherosclerosis-no longer a theory. Clin Chem (2021) 67(1):131–42. doi: 10.1093/clinchem/hvaa275 93 Zindel

Kubes

. DAMPs, PAMPs, and LAMPs in immunity and sterile inflammation. Annu Rev Pathol (2020) 15:493–518. doi: 10.1146/annurev-pathmechdis-012419-032847 94 Zhu

Huang

Zhao

. PAMPs and DAMPs as the bridge between periodontitis and atherosclerosis: The potential therapeutic targets. Front Cell Dev Biol (2022) 10:856118. doi: 10.3389/fcell.2022.856118 95 Nativel

Couret

Giraud

Meilhac

d'Hellencourt

Viranaïcken

. Porphyromonas gingivalis lipopolysaccharides act exclusively through TLR4 with a resilience between mouse and human. Sci Rep (2017) 7(1):15789. doi: 10.1038/s41598-017-16190-y 96 Wang

Liu

Zhang

Ouyang

Wang

Jiang

. Crosstalk between akt and NF-κB pathway mediates inhibitory effect of gas6 on monocytes-endothelial cells interactions stimulated by p. gingivalis-LPS J Cell Mol Med (2020) 24(14):7979–90. doi: 10.1111/jcmm.15430 97 Xie

Cai

Wang

. Interleukin-37 suppresses ICAM-1 expression in parallel with NF-κB down-regulation following TLR2 activation of human coronary artery endothelial cells. Int Immunopharmacol (2016) 38:26–30. doi: 10.1016/j.intimp.2016.05.003 98 González-Ramos

Paz-García

Rius

Del Monte-Monge

Rodríguez

Fernández-García

. Endothelial NOD1 directs myeloid cell recruitment in atherosclerosis through VCAM-1. FASEB J (2019) 33(3):3912–21. doi: 10.1096/fj.201801231RR 99 Jin

Huang

Shu

Liu

Dai

. Peptidoglycan recognition protein 1 attenuates atherosclerosis by suppressing endothelial cell adhesion. J Cardiovasc Pharmacol (2021) 78(4):615–21. doi: 10.1097/FJC.0000000000001100 100 Nijhuis

van der Graaf

Melief

Schoneveld

de Kleijn

Laman

. IgM antibody level against proinflammatory bacterial peptidoglycan is inversely correlated with extent of atherosclerotic disease. Atherosclerosis (2004) 173(2):245–51. doi: 10.1016/j.atherosclerosis.2003.12.005 101 Jun

Jung

Choi

. Treponema denticola, porphyromonas gingivalis, and tannerella forsythia induce cell death and release of endogenous danger signals. Arch Oral Biol (2017) 73:72–8. doi: 10.1016/j.archoralbio.2016.09.010 102 Krishnan-Sivadoss

Mijares-Rojas

Villarreal-Leal

Torre-Amione

Knowlton

Guerrero-Beltrán

. Heat shock protein 60 and cardiovascular diseases: An intricate love-hate story. Med Res Rev (2021) 41(1):29–71. doi: 10.1002/med.21723 103 Rahman

Steuer

Gillgren

Végvári

Liu

Frostegård

. Malondialdehyde conjugated with albumin induces pro-inflammatory activation of T cells isolated from human atherosclerotic plaques both directly and Via dendritic cell-mediated mechanism. JACC Basic Transl Sci (2019) 4(4):480–94. doi: 10.1016/j.jacbts.2019.03.009 104 Almanzar

Öllinger

Leuenberger

Onestingel

Rantner

Zehm

. Autoreactive HSP60 epitope-specific T-cells in early human atherosclerotic lesions. J Autoimmun (2012) 39(4):441–50. doi: 10.1016/j.jaut.2012.07.006 105 de Graaf

Kloppenburg

Kitslaar

Bruggeman

Stassen

. Human heat shock protein 60 stimulates vascular smooth muscle cell proliferation through toll-like receptors 2 and 4. Microbes Infect (2006) 8(7):1859–65. doi: 10.1016/j.micinf.2006.02.024 106 Schenkein

Papapanou

Genco

Sanz

. Mechanisms underlying the association between periodontitis and atherosclerotic disease. Periodontol 2000 (2020) 83(1):90–106. doi: 10.1111/prd.12304 107 Bochkov

Oskolkova

Birukov

Levonen

Binder

Stöckl

. Generation and biological activities of oxidized phospholipids. Antioxid Redox Signal (2010) 12(8):1009–59. doi: 10.1089/ars.2009.2597 108 Wan

Hua

Thiagarajan

Frostegård

Haeggström

. Oxidized but not native cardiolipin has pro-inflammatory effects, which are inhibited by annexin A5. Atherosclerosis (2014) 235(2):592–8. doi: 10.1016/j.atherosclerosis.2014.05.913 109 Inaba

Hokamura

Nakano

Nomura

Katayama

Nakajima

. Upregulation of S100 calcium-binding protein A9 is required for induction of smooth muscle cell proliferation by a periodontal pathogen. FEBS Lett (2009) 583(1):128–34. doi: 10.1016/j.febslet.2008.11.036 110 Liu

Wang

Liao

Zhou

Zhu

. Circular RNA PPP1CC promotes porphyromonas gingivalis-lipopolysaccharide-induced pyroptosis of vascular smooth muscle cells by activating the HMGB1/TLR9/AIM2 pathway. J Int Med Res (2021) 49(3):300060521996564. doi: 10.1177/0300060521996564 111 Zheng

Fan

Zhang

Sun

Lin

. Porphyromonas gingivalis survival skills: Immune evasion. J Periodontal Res (2021) 56(6):1007–18. doi: 10.1111/jre.12915 112 Torzewski

Enzymatically modified

LDL

. Atherosclerosis and beyond: paving the way to acceptance. Front Biosci (Landmark Ed) (2018) 23(7):1257–71. doi: 10.2741/4642 113 Vlaicu

Tatomir

Rus

Mekala

Mircea

Niculescu

. The role of complement activation in atherogenesis: The first 40 years. Immunol Res (2016) 64(1):1–13. doi: 10.1007/s12026-015-8669-6 114 Wingrove

DiScipio

Chen

Potempa

Travis

Hugli

. Activation of complement components C3 and C5 by a cysteine proteinase (gingipain-1) from porphyromonas (Bacteroides) gingivalis. J Biol Chem (1992) 267(26):18902–7. doi: 10.1016/S0021-9258(19)37046-2 115 Ricklin

Hajishengallis

Yang

Lambris

. Complement: a key system for immune surveillance and homeostasis. Nat Immunol (2010) 11(9):785–97. doi: 10.1038/ni.1923 116 Hou

Liu

Pan

Zheng

. Gingipain of porphyromonas gingivalis manipulates M1 macrophage polarization through C5a pathway. In Vitro Cell Dev Biol - Animal (2017) 53(7):593–603. doi: 10.1007/s11626-017-0164-z 117 An

Ren

Zhang

. Role of C5a-C5aR axis in the development of atherosclerosis. Sci China Life Sci (2014) 57(8):790–4. doi: 10.1007/s11427-014-4711-5 118 Speidl

Kastl

Hutter

Katsaros

Kaun

Bauriedel

. The complement component C5a is present in human coronary lesions in vivo and induces the expression of MMP-1 and MMP-9 in human macrophages in vitro. FASEB J (2011) 25(1):35–44. doi: 10.1096/fj.10-156083 119 Speidl

Exner

Amighi

Kastl

Zorn

Maurer

. Complement component C5a predicts future cardiovascular events in patients with advanced atherosclerosis. Eur Heart J (2005) 26(21):2294–9. doi: 10.1093/eurheartj/ehi339 120 Wezel

Quax

Kuiper

Bot

. The role of mast cells in atherosclerosis. Hamostaseologie (2015) 35(2):113–20. doi: 10.5482/HAMO-14-08-0034 121 Wojta

Huber

Valent

. New aspects in thrombotic research: complement induced switch in mast cells from a profibrinolytic to a prothrombotic phenotype. Pathophysiol Haemost Thromb (2003) 33(5-6):438–41. doi: 10.1159/000083842 122 Patel

Thelander

Hernandez

Montenegro

Hassing

Burton

. ApoE(-/-) mice develop atherosclerosis in the absence of complement component C5. Biochem Biophys Res Commun (2001) 286(1):164–70. doi: 10.1006/bbrc.2001.5276 123 Wezel

de Vries

Lagraauw

Foks

Kuiper

Quax

. Complement factor C5a induces atherosclerotic plaque disruptions. J Cell Mol Med (2014) 18(10):2020–30. doi: 10.1111/jcmm.12357 124 Niyonzima

Bakke

Gregersen

Holm

Sandanger

Orrem

. Cholesterol crystals use complement to increase NLRP3 signaling pathways in coronary and carotid atherosclerosis. EBioMedicine (2020) 60:102985. doi: 10.1016/j.ebiom.2020.102985 125 An

Liu

Zhang

Gao

Zhao

. Overexpression of complement component C5a accelerates the development of atherosclerosis in ApoE-knockout mice. Oncotarget (2016) 7(35):56060–70. doi: 10.18632/oncotarget.11180 126 Manthey

Thomas

Shiels

Zernecke

Woodruff

Rolfe

. Complement C5a inhibition reduces atherosclerosis in ApoE-/- mice. FASEB J (2011) 25(7):2447–55. doi: 10.1096/fj.10-174284 127 Wang

Krauss

Domon

Hosur

Liang

Magotti

. Microbial hijacking of complement-toll-like receptor crosstalk. Sci Signal (2010) 3(109):ra11. doi: 10.1126/scisignal.2000697 128 Maekawa

Krauss

Abe

Jotwani

Triantafilou

. Porphyromonas gingivalis manipulates complement and TLR signaling to uncouple bacterial clearance from inflammation and promote dysbiosis. Cell Host Microbe (2014) 15(6):768–78. doi: 10.1016/j.chom.2014.05.012 129 Makkawi

Hoch

Burns

Hosur

Hajishengallis

Kirschning

. Porphyromonas gingivalis stimulates TLR2-PI3K signaling to escape immune clearance and induce bone resorption independently of MyD88. Front Cell Infect Microbiol (2017) 7:359. doi: 10.3389/fcimb.2017.00359 130 Shaik-Dasthagirisaheb

Huang

Baer

Gibson

3rd . Role of MyD88-dependent and MyD88-independent signaling in porphyromonas gingivalis-elicited macrophage foam cell formation. Mol Oral Microbiol (2013) 28(1):28–39. doi: 10.1111/omi.12003 131 Herrero-Cervera

Soehnlein

Kenne

. Neutrophils in chronic inflammatory diseases. Cell Mol Immunol (2022) 19(2):177–91. doi: 10.1038/s41423-021-00832-3 132 Bryzek

Ciaston

Dobosz

Gasiorek

Makarska

Sarna

. Triggering NETosis via protease-activated receptor (PAR)-2 signaling as a mechanism of hijacking neutrophils function for pathogen benefits. PLoS Pathog (2019) 15(5):e1007773. doi: 10.1371/journal.ppat.1007773 133 Silvestre-Roig

Braster

Ortega-Gomez

Soehnlein

. Neutrophils as regulators of cardiovascular inflammation. Nat Rev Cardiol (2020) 17(6):327–40. doi: 10.1038/s41569-019-0326-7 134 du Teil Espina

van der Horst

Hirschfeld

Lopez-Alvarez

Mulder

. Coating and corruption of human neutrophils by bacterial outer membrane vesicles. Microbiol Spectr (2022) 10(5):e0075322. doi: 10.1128/spectrum.00753-22 135 Gu

Liu

Zhu

Qiu

Sun

. Effects of endotoxin tolerance induced by porphyromonas gingivalis lipopolysaccharide on inflammatory responses in neutrophils. Inflammation (2020) 43(5):1692–706. doi: 10.1007/s10753-020-01243-8 136 Moschonas

Tselepis

. The pathway of neutrophil extracellular traps towards atherosclerosis and thrombosis. Atherosclerosis (2019) 288:9–16. doi: 10.1016/j.atherosclerosis.2019.06.919 137 Saffarzadeh

Juenemann

Queisser

Lochnit

Barreto

Galuska

. Neutrophil extracellular traps directly induce epithelial and endothelial cell death: a predominant role of histones. PLoS One (2012) 7(2):e32366. doi: 10.1371/journal.pone.0032366 138 Zhang

Brennan

Aviles

Pearce

Penn

. Association between myeloperoxidase levels and risk of coronary artery disease. JAMA (2001) 286(17):2136–42. doi: 10.1001/jama.286.17.2136 139 Guzik

Bzowska

Smagur

Krupa

Sieprawska

Travis

. A new insight into phagocytosis of apoptotic cells: proteolytic enzymes divert the recognition and clearance of polymorphonuclear leukocytes by macrophages. Cell Death Differ (2007) 14(1):171–82. doi: 10.1038/sj.cdd.4401927 140 Doran

Yurdagul

Jr. Tabas

. Efferocytosis in health and disease. Nat Rev Immunol (2020) 20(4):254–67. doi: 10.1038/s41577-019-0240-6 141 Papadopoulos

Shaik-Dasthagirisaheb

Huang

Viglianti

Henderson

Kantarci

. Immunologic environment influences macrophage response to porphyromonas gingivalis. Mol Oral Microbiol (2017) 32(3):250–61. doi: 10.1111/omi.12168 142 Chistiakov

Melnichenko

Myasoedova

Grechko

Orekhov

. Mechanisms of foam cell formation in atherosclerosis. J Mol Med (Berl) (2017) 95(11):1153–65. doi: 10.1007/s00109-017-1575-8 143 Werheim

Senior

Shaffer

Cuadra

. Oral pathogen porphyromonas gingivalis can escape phagocytosis of mammalian macrophages. Microorganisms (2020) 8(9):1. doi: 10.3390/microorganisms8091432 144 Slocum

Coats

Hua

Kramer

Papadopoulos

Weinberg

. Distinct lipid a moieties contribute to pathogen-induced site-specific vascular inflammation. PLoS Pathog (2014) 10(7):e1004215. doi: 10.1371/journal.ppat.1004215 145 Reife

Coats

Al-Qutub

Dixon

Braham

Billharz

. Porphyromonas gingivalis lipopolysaccharide lipid a heterogeneity: differential activities of tetra- and penta-acylated lipid a structures on e-selectin expression and TLR4 recognition. Cell Microbiol (2006) 8(5):857–68. doi: 10.1111/j.1462-5822.2005.00672.x 146 Herath

Darveau

Seneviratne

Wang

Jin

. Tetra- and penta-acylated lipid a structures of porphyromonas gingivalis LPS differentially activate TLR4-mediated NF-kappaB signal transduction cascade and immuno-inflammatory response in human gingival fibroblasts. PLoS One (2013) 8(3):e58496. doi: 10.1371/journal.pone.0058496 147 Castro

Collighan

Lambert

Dias

Chauhan

Bland

. Porphyromonas gingivalis gingipains cause defective macrophage migration towards apoptotic cells and inhibit phagocytosis of primary apoptotic neutrophils. Cell Death Dis (2017) 8(3):e2644. doi: 10.1038/cddis.2016.481 148 Okano

Ashida

Suzuki

Shoji

Nakayama

Suzuki

. Porphyromonas gingivalis triggers NLRP3-mediated inflammasome activation in macrophages in a bacterial gingipains-independent manner. Eur J Immunol (2018) 48(12):1965–74. doi: 10.1002/eji.201847658 149 Hajishengallis

Wang

Bagby

Nelson

. Importance of TLR2 in early innate immune response to acute pulmonary infection with porphyromonas gingivalis in mice. J Immunol (2008) 181(6):4141–9. doi: 10.4049/jimmunol.181.6.4141 150 Yang

Pan

Tong

Zhao

. Sialidase deficiency in porphyromonas gingivalis increases IL-12 secretion in stimulated macrophages through regulation of CR3, IncRNA GAS5 and miR-21. Front Cell Infect Microbiol (2018) 8:100. doi: 10.3389/fcimb.2018.00100 151 Trinchieri

. Interleukin-12 and the regulation of innate resistance and adaptive immunity. Nat Rev Immunol (2003) 3(2):133–46. doi: 10.1038/nri1001 152 Park

Jeong

Chung

. Porphyromonas gingivalis induces autophagy in THP-1-derived macrophages. Mol Oral Microbiol (2017) 32(1):48–59. doi: 10.1111/omi.12153 153 Curtis

Percival

Devine

Darveau

Coats

Rangarajan

. Temperature-dependent modulation of porphyromonas gingivalis lipid a structure and interaction with the innate host defenses. Infect Immun (2011) 79(3):1187–93. doi: 10.1128/IAI.00900-10 154 Blasi

Korostoff

Dhingra

Reyes-Reveles

Shenker

Shahabuddin

. Variants of porphyromonas gingivalis lipopolysaccharide alter lipidation of autophagic protein, microtubule-associated protein 1 light chain 3, LC3. Mol Oral Microbiol (2016) 31(6):486–500. doi: 10.1111/omi.12141 155 Lin

Huang

Zhan

Tan

. Macrophages: A communication network linking porphyromonas gingivalis infection and associated systemic diseases. Front Immunol (2022) 13:952040. doi: 10.3389/fimmu.2022.952040 156 Liu

Yang

Zhou

Zhao

. [Porphyromonas gingivalis lipopolysaccharide regulates macrophage polarization via triggering receptors expressed on myeloid cells-1]. Zhonghua Kou Qiang Yi Xue Za Zhi (2021) 56(2):175–81. doi: 10.3760/cma.j.cn112144-20200210-00042 157 Yang

Chen

Zhao

. [Expression of triggering receptors expressed by myeloid cells-1 in macrophages stimulated by porphyromonas gingivalis-lipopolysaccharide]. Hua Xi Kou Qiang Yi Xue Za Zhi (2018) 36(5):475–81. doi: 10.7518/hxkq.2018.05.003 158 Gu

Jia-Lu

Liu

Cao

Sun

. Endotoxin tolerance induced by porphyromonas gingivalis lipopolysaccharide alters macrophage polarization. Microb Pathog (2022) 164:105448. doi: 10.1016/j.micpath.2022.105448 159 Tabas

Lichtman

. Monocyte-macrophages and T cells in atherosclerosis. Immunity (2017) 47(4):621–34. doi: 10.1016/j.immuni.2017.09.008 160 Xu

Chaudhury

Zhang

Savoldo

Metelitsa

Rodgers

. Glycolysis determines dichotomous regulation of T cell subsets in hypoxia. J Clin Invest. (2016) 126(7):2678–88. doi: 10.1172/JCI85834 161 Angelin

Gil-de-Gomez

Dahiya

Jiao

Guo

Levine

. Foxp3 reprograms T cell metabolism to function in low-glucose, high-lactate environments. Cell Metab (2017) 25(6):1282–93.e7. doi: 10.1016/j.cmet.2016.12.018 162 Gaddis

Maynard

Weaver

Michalek

Katz

. Role of TLR2-dependent IL-10 production in the inhibition of the initial IFN-gamma T cell response to porphyromonas gingivalis. J Leukoc Biol (2013) 93(1):21–31. doi: 10.1189/jlb.0512220 163 Mittal

Cho

Ishido

Roche

. Interleukin 10 (IL-10)-mediated immunosuppression: March-i induction regulates antigen presentation by macrophages but not dendritic cells. J Biol Chem (2015) 290(45):27158–67. doi: 10.1074/jbc.M115.682708 164 Kuol

Stojanovska

Nurgali

Apostolopoulos

. PD-1/PD-L1 in disease. Immunotherapy (2018) 10(2):149–60. doi: 10.2217/imt-2017-0120 165 Meghil

Tawfik

Elashiry

Rajendran

Arce

Fulton

. Disruption of immune homeostasis in human dendritic cells via regulation of autophagy and apoptosis by porphyromonas gingivalis. Front Immunol (2019) 10:2286. doi: 10.3389/fimmu.2019.02286 166 Meghil

Ghaly

Cutler

. A tale of two fimbriae: How invasion of dendritic cells by porphyromonas gingivalis disrupts DC maturation and depolarizes the T-Cell-Mediated immune response. Pathogens (2022) 11(3):5–6. doi: 10.3390/pathogens11030328 167 Khalaf

Bengtsson

. Altered T-cell responses by the periodontal pathogen porphyromonas gingivalis. PLoS One (2012) 7(9):e45192. doi: 10.1371/journal.pone.0045192 168 Saigusa

Winkels

Ley

. T Cell subsets and functions in atherosclerosis. Nat Rev Cardiol (2020) 17(7):387–401. doi: 10.1038/s41569-020-0352-5 169 Yang

Hao

Liu

Huang

. Th17/Treg balance and indoleamine 2,3 dioxygenase activity in periodontitis-associated atherosclerotic patients. J Int Med Res (2022) 50(2):3000605221080877. doi: 10.1177/03000605221080877 170 Yang

Zhang

Yao

Liu

Miao

. Porphyromonas gingivalis oral infection promote T helper 17/Treg imbalance in the development of atherosclerosis. J Dent Sci (2017) 12(1):60–9. doi: 10.1016/j.jds.2016.10.003 171 Kramer

Genco

. Microbiota, immune subversion, and chronic inflammation. Front Immunol (2017) 8:255. doi: 10.3389/fimmu.2017.00255 172 Bale

Doneen

Vigerust

. High-risk periodontal pathogens contribute to the pathogenesis of atherosclerosis. Postgrad Med J (2017) 93(1098):215–20. doi: 10.1136/postgradmedj-2016-134279 173 McNicol

Israels

. Mechanisms of oral bacteria-induced platelet activation. Can J Physiol Pharmacol (2010) 88(5):510–24. doi: 10.1139/Y10-029 174 Forner

Larsen

Kilian

Holmstrup

. Incidence of bacteremia after chewing, tooth brushing and scaling in individuals with periodontal inflammation. J Clin Periodontol (2006) 33(6):401–7. doi: 10.1111/j.1600-051X.2006.00924.x 175 Cekici

Kantarci

Hasturk

Van Dyke

. Inflammatory and immune pathways in the pathogenesis of periodontal disease. Periodontol 2000 (2014) 64(1):57–80. doi: 10.1111/prd.12002 176 Katz

Sambandam

Michalek

Balkovetz

. Characterization of porphyromonas gingivalis-induced degradation of epithelial cell junctional complexes. Infect Immun (2000) 68(3):1441–9. doi: 10.1128/IAI.68.3.1441-1449.2000 177 Katz

Yang

Zhang

Potempa

Travis

Michalek

. Hydrolysis of epithelial junctional proteins by porphyromonas gingivalis gingipains. Infect Immun (2002) 70(5):2512–8. doi: 10.1128/IAI.70.5.2512-2518.2002 178 Abe-Yutori

Chikazawa

Shibasaki

Murakami

. Decreased expression of e-cadherin by porphyromonas gingivalis-lipopolysaccharide attenuates epithelial barrier function. J Periodontal Res (2017) 52(1):42–50. doi: 10.1111/jre.12367 179 Chen

Alshaikh

Kim

Chun

Mehrazarin

. Porphyromonas gingivalis impairs oral epithelial barrier through targeting GRHL2. J Dent Res (2019) 98(10):1150–8. doi: 10.1177/0022034519865184 180 Belstrøm

Holmstrup

Damgaard

Borch

Skjødt

Bendtzen

. The atherogenic bacterium porphyromonas gingivalis evades circulating phagocytes by adhering to erythrocytes. Infect Immun (2011) 79(4):1559–65. doi: 10.1128/IAI.01036-10 181 Meghil

Cutler

. Oral microbes and mucosal dendritic cells, "Spark and flame" of local and distant inflammatory diseases. Int J Mol Sci (2020) 21(5):2–7. doi: 10.3390/ijms21051643 182 Pirro

Bianconi

Paciullo

Mannarino

Bagaglia

Sahebkar

. Lipoprotein(a) and inflammation: A dangerous duet leading to endothelial loss of integrity. Pharmacol Res (2017) 119:178–87. doi: 10.1016/j.phrs.2017.02.001 183 Deshpande

Khan

Genco

. Invasion of aortic and heart endothelial cells by porphyromonas gingivalis. Infect Immun (1998) 66(11):5337–43. doi: 10.1128/IAI.66.11.5337-5343.1998 184 Gimbrone

Jr. Garcia-Cardena

. Endothelial cell dysfunction and the pathobiology of atherosclerosis. Circ Res (2016) 118(4):620–36. doi: 10.1161/CIRCRESAHA.115.306301 185 Xu

Ilyas

Little

Kamato

Zheng

. Endothelial dysfunction in atherosclerotic cardiovascular diseases and beyond: From mechanism to pharmacotherapies. Pharmacol Rev (2021) 73(3):924–67. doi: 10.1124/pharmrev.120.000096 186 Farrugia

Stafford

Potempa

Wilkinson

Chen

Murdoch

. Mechanisms of vascular damage by systemic dissemination of the oral pathogen porphyromonas gingivalis. FEBS J (2021) 288(5):1479–95. doi: 10.1111/febs.15486 187 Farrugia

Stafford

Murdoch

. Porphyromonas gingivalis outer membrane vesicles increase vascular permeability. J Dent Res (2020) 99(13):1494–501. doi: 10.1177/0022034520943187 188 Morris

Puri

Olive

Carvalho

Berk

Walder

. Endothelial dysfunction in neuroprogressive disorders-causes and suggested treatments. BMC Med (2020) 18(1):305. doi: 10.1186/s12916-020-01749-w 189 Mussbacher

Schossleitner

Kral-Pointner

Salzmann

Schrammel

Schmid

. More than just a monolayer: the multifaceted role of endothelial cells in the pathophysiology of atherosclerosis. Curr Atheroscler Rep (2022) 24(6):483–92. doi: 10.1007/s11883-022-01023-9 190 Song

Tada

Nishioka

Nemoto

Imamura

Potempa

. Porphyromonas gingivalis gingipains-mediated degradation of plasminogen activator inhibitor-1 leads to delayed wound healing responses in human endothelial cells. J Innate Immun (2022) 14(4):306–19. doi: 10.1159/000519737 191 Luo

Luo

Fay

. Plasminogen activator inhibitor-1 regulates the vascular expression of vitronectin. J Thromb Haemost (2017) 15(12):2451–60. doi: 10.1111/jth.13869 192 Vaughan

. PAI-1 and atherothrombosis. J Thromb Haemost (2005) 3(8):1879–83. doi: 10.1111/j.1538-7836.2005.01420.x 193 Ismail

Shaker

Bajou

. The plasminogen-activator plasmin system in physiological and pathophysiological angiogenesis. Int J Mol Sci (2021) 23(1):8–9. doi: 10.3390/ijms23010337 194 Reyes

Getachew

Dunn

Progulske-Fox

. Porphyromonas gingivalis W83 traffics via ICAM1 in microvascular endothelial cells and alters capillary organization in vivo. J Oral Microbiol (2020) 12(1):1742528. doi: 10.1080/20002297.2020.1742528 195 Li

Michel

Cohen

Decarlo

Kozarov

. Intracellular survival and vascular cell-to-cell transmission of porphyromonas gingivalis. BMC Microbiol (2008) 8:26. doi: 10.1186/1471-2180-8-26 196 Czesnikiewicz-Guzik

Nosalski

Mikolajczyk

Vidler

Dohnal

Dembowska

. Th1-type immune responses to porphyromonas gingivalis antigens exacerbate angiotensin II-dependent hypertension and vascular dysfunction. Br J Pharmacol (2019) 176(12):1922–31. doi: 10.1111/bph.14536 197 Sampath

Okoro

Gipson

Chukkapalli

Farmer-Dixon

Gangula

. Porphyromonas gingivalis infection alters Nrf2-phase II enzymes and nitric oxide in primary human aortic endothelial cells. J Periodontol (2021) 92(7):54–65. doi: 10.1002/JPER.20-0444 198 Hirasawa

Kurita-Ochiai

. Porphyromonas gingivalis induces apoptosis and autophagy via ER stress in human umbilical vein endothelial cells. Mediators Inflamm (2018) 2018:1967506. doi: 10.1155/2018/1967506 199 Durand

Scoazec

Lafont

Boddaert

Al Hajzen

Addad

. In vivo induction of endothelial apoptosis leads to vessel thrombosis and endothelial denudation: A clue to the understanding of the mechanisms of thrombotic plaque erosion. Circulation (2004) 109(21):2503–6. doi: 10.1161/01.CIR.0000130172.62481.90 200 Pan

Lei

Chen

Yan

. Rosiglitazone impedes porphyromonas gingivalis-accelerated atherosclerosis by downregulating the TLR/NF-kappaB signaling pathway in atherosclerotic mice. Int Immunopharmacol (2014) 23(2):701–8. doi: 10.1016/j.intimp.2014.10.026 201 Hayashi

Papadopoulos

Gudino

Weinberg

Barth

Madrigal

. Protective role for TLR4 signaling in atherosclerosis progression as revealed by infection with a common oral pathogen. J Immunol (2012) 189(7):3681–8. doi: 10.4049/jimmunol.1201541 202 Bugueno

Benkirane-Jessel

Huck

. Implication of Toll/IL-1 receptor domain containing adapters in porphyromonas gingivalis-induced inflammation. Innate Immun (2021) 27(4):324–42. doi: 10.1177/17534259211013087 203 Xie

Tang

Sun

Mei

Zhao

. Porphyromonas gingivalis disrupts vascular endothelial homeostasis in a TLR-NF-κB axis dependent manner. Int J Oral Sci (2020) 12(1):28. doi: 10.1038/s41368-020-00096-z 204 Chen

Qin

Baeyens

Afolabi

Budatha

. Endothelial-to-mesenchymal transition drives atherosclerosis progression. J Clin Invest. (2015) 125(12):4514–28. doi: 10.1172/JCI82719 205 Cho

Lee

Chang

Lee

Kim

. Endothelial to mesenchymal transition represents a key link in the interaction between inflammation and endothelial dysfunction. Front Immunol (2018) 9:294. doi: 10.3389/fimmu.2018.00294 206 Suh

Kim

Bostrom

Wang

Kim

Park

. Periodontitis-induced systemic inflammation exacerbates atherosclerosis partly via endothelial-mesenchymal transition in mice. Int J Oral Sci (2019) 11(3):21. doi: 10.1038/s41368-019-0054-1 207 Xie

Tang

Nie

Zhang

Zhou

. BMAL1-downregulation aggravates porphyromonas gingivalis-induced atherosclerosis by encouraging oxidative stress. Circ Res (2020) 126(6):e15–29. doi: 10.1161/CIRCRESAHA.119.315502 208 Deng

Gong

Chen

Zhang

Chen

Cheng

. Porphyromonas gingivalis lipopolysaccharide affects the angiogenic function of endothelial progenitor cells via Akt/FoxO1 signaling. J Periodontal Res (2022) 57(4):859–68. doi: 10.1111/jre.13024 209 Li Calzi

Neu

Shaw

Kielczewski

Moldovan

Grant

. EPCs and pathological angiogenesis: when good cells go bad. Microvasc Res (2010) 79(3):207–16. doi: 10.1016/j.mvr.2010.02.011 210 Xu

Dong

Luo

Liu

Gao

Pan

. Porphyromonas gingivalis infection promotes mitochondrial dysfunction through Drp1-dependent mitochondrial fission in endothelial cells. Int J Oral Sci (2021) 13(1):28. doi: 10.1038/s41368-021-00134-4 211 Bugueno

Khelif

Seelam

Morand

Tenenbaum

Davideau

. Porphyromonas gingivalis differentially modulates cell death profile in ox-LDL and TNF-alpha pre-treated endothelial cells. PLoS One (2016) 11(4):e0154590. doi: 10.1371/journal.pone.0154590 212 Bugueno

Zobairi El-Ghazouani

Batool

El Itawi

Anglès-Cano

Benkirane-Jessel

. Porphyromonas gingivalis triggers the shedding of inflammatory endothelial microvesicles that act as autocrine effectors of endothelial dysfunction. Sci Rep (2020) 10(1):1778. doi: 10.1038/s41598-020-58374-z 213 Qi

Zhao

Chen

Meng

. [Effects of porphyromnonas gingivalis lipopolysaccharide on the expression of RANTES and fractalkine in human urnbilical vein endothelial cells]. Hua Xi Kou Qiang Yi Xue Za Zhi (2016) 34(2):194–9. doi: 10.7518/hxkq.2016.02.018 214 Braunersreuther

Steffens

Arnaud

Pelli

Burger

Proudfoot

. A novel RANTES antagonist prevents progression of established atherosclerotic lesions in mice. Arterioscler Thromb Vasc Biol (2008) 28(6):1090–6. doi: 10.1161/ATVBAHA.108.165423 215 Marino

Silva

Santos

Pinto

Gazinelli

Teixeira

. CC-chemokine receptors: a potential therapeutic target for trypanosoma cruzi-elicited myocarditis. Mem Inst Oswaldo Cruz. (2005) 100 Suppl 1:93–6. doi: 10.1590/s0074-02762005000900015 216 Lv

Jing

Zhong

Fang

Yang

. Assessment of RANTES levels as the indicators of plaque vulnerability in rabbit models of atherosclerosis. Pathol Res Pract (2014) 210(12):1031–7. doi: 10.1016/j.prp.2014.03.012 217 Li

Liu

Chu

Zhong

Xie

. LOX-1 regulates p. gingivalis-induced monocyte migration and adhesion to human umbilical vein endothelial cells. Front Cell Dev Biol (2020) 8:596. doi: 10.3389/fcell.2020.00596 218 Ho

Guo

Chunga

Goodwin

Xie

. Characterization of innate immune responses of human endothelial cells induced by porphyromonas gingivalis and their derived outer membrane vesicles. Front Cell Infect Microbiol (2016) 6:139. doi: 10.3389/fcimb.2016.00139 219 Wu

Hou

Liu

. Porphyromonas gingivalis-induced MIF regulates intercellular adhesion molecule-1 expression in EA.hy926 cells and monocyte-endothelial cell adhesion through the receptors CD74 and CXCR4. Inflammation (2019) 42(3):874–83. doi: 10.1007/s10753-018-0942-0 220 Xu

Pan

Hou

. Porphyromonas gingivalis ATCC 33277 promotes intercellular adhesion molecule-1 expression in endothelial cells and monocyte-endothelial cell adhesion through macrophage migration inhibitory factor. BMC Microbiol (2018) 18(1):16. doi: 10.1186/s12866-018-1156-1 221 Bakogiannis

Sachse

Stamatelopoulos

Stellos

. Platelet-derived chemokines in inflammation and atherosclerosis. Cytokine (2019) 122:154157. doi: 10.1016/j.cyto.2017.09.013 222 Chen

Fletcher

Gheorghe

Oyoyo

Boskovic

. Platelet plug formation in whole blood is enhanced in the presence of porphyromonas gingivalis. Mol Oral Microbiol (2020) 35(6):251–9. doi: 10.1111/omi.12314 223 Klarstrom Engstrom

Khalaf

Kalvegren

Bengtsson

. The role of porphyromonas gingivalis gingipains in platelet activation and innate immune modulation. Mol Oral Microbiol (2015) 30(1):62–73. doi: 10.1111/omi.12067 224 Zhan

Meng

Wang

Hou

. Platelet activation and platelet-leukocyte interaction in generalized aggressive periodontitis. J Leukoc Biol (2016) 100(5):1155–66. doi: 10.1189/jlb.4A1115-526RR 225 Chen

Fletcher

Payne

Aka

Thornburg

Gheorghe

. Platelet and neutrophil responses to porphyromonas gingivalis in human whole blood. Mol Oral Microbiol (2021) 36(3):202–13. doi: 10.1111/omi.12336 226 Etulain

Martinod

Wong

Cifuni

Schattner

Wagner

. P-selectin promotes neutrophil extracellular trap formation in mice. Blood (2015) 126(2):242–6. doi: 10.1182/blood-2015-01-624023 227 Brousseau-Nault

Kizhakkedathu

Kim

. Chronic periodontitis is associated with platelet factor 4 (PF4) secretion: A pilot study. J Clin Periodontol (2017) 44(11):1101–11. doi: 10.1111/jcpe.12771 228 Jockel-Schneider

Kobsar

Stellzig-Eisenhauer

Vogel

Stork

Frantz

. Wild-type isolates of porphyromonas gingivalis derived from periodontitis patients display major variability in platelet activation. J Clin Periodontol (2018) 45(6):693–700. doi: 10.1111/jcpe.12895 229 Pollreisz

Huang

Roth

Cheng

Kebschull

Papapanou

. Enhanced monocyte migration and pro-inflammatory cytokine production by porphyromonas gingivalis infection. J Periodontal Res (2010) 45(2):239–45. doi: 10.1111/j.1600-0765.2009.01225.x 230 Li

Wang

Xiang

Chen

Yang

. Porphyromonas gingivalis lipopolysaccharide increases lipid accumulation by affecting CD36 and ATP-binding cassette transporter A1 in macrophages. Oncol Rep (2013) 30(3):1329–36. doi: 10.3892/or.2013.2600 231 Lonn

Ljunggren

Klarstrom-Engstrom

Demirel

Bengtsson

Karlsson

. Lipoprotein modifications by gingipains of porphyromonas gingivalis. J Periodontal Res (2018) 53(3):403–13. doi: 10.1111/jre.12527 232 Miyakawa

Honma

Kuramitsu

. Interaction of porphyromonas gingivalis with low-density lipoproteins: implications for a role for periodontitis in atherosclerosis. J Periodontal Res (2004) 39(1):1–9. doi: 10.1111/j.1600-0765.2004.00697.x 233 Hashimoto

Kadowaki

Tsukuba

Yamamoto

. Selective proteolysis of apolipoprotein b-100 by arg-gingipain mediates atherosclerosis progression accelerated by bacterial exposure. J Biochem (2006) 140(5):713–23. doi: 10.1093/jb/mvj202 234 Joo

Cha

Chung

Lee

Kim

Choi

. Peptide 19 of porphyromonas gingivalis heat shock protein is a potent inducer of low-density lipoprotein oxidation. J Periodontol (2017) 88(2):e58–64. doi: 10.1902/jop.2016.160402 235 Kim

Cha

Kim

Kwon

Lee

Choi

. Porphyromonas gingivalis accelerates atherosclerosis through oxidation of high-density lipoprotein. J Periodontal Implant Sci (2018) 48(1):60–8. doi: 10.5051/jpis.2018.48.1.60 236 Park

. CD36, a scavenger receptor implicated in atherosclerosis. Exp Mol Med (2014) 46:e99. doi: 10.1038/emm.2014.38 237 Liang

Liu

Chen

Zhou

. Porphyromonas gingivalis infected macrophages upregulate CD36 expression via ERK/NF-kappaB pathway. Cell Signal (2016) 28(9):1292–303. doi: 10.1016/j.cellsig.2016.05.017 238 Brown

Kennedy

Morton

Febbraio

. CD36/SR-B2-TLR2 dependent pathways enhance porphyromonas gingivalis mediated atherosclerosis in the ldlr KO mouse model. PLoS One (2015) 10(5):e0125126. doi: 10.1371/journal.pone.0125126 239 Gupta

Goswami

Alharbi

Biswas

Rahaman

. TRPV4 is a regulator in p. gingivalis lipopolysaccharide-induced exacerbation of macrophage foam cell formation. Physiol Rep (2019) 7(7):e14069. doi: 10.14814/phy2.14069 240 Furuhashi

. Fatty acid-binding protein 4 in cardiovascular and metabolic diseases. J Atheroscler Thromb (2019) 26(3):216–32. doi: 10.5551/jat.48710 241 Furuhashi

Fuseya

Murata

Hoshina

Ishimura

Mita

. Local production of fatty acid-binding protein 4 in Epicardial/Perivascular fat and macrophages is linked to coronary atherosclerosis. Arterioscler Thromb Vasc Biol (2016) 36(5):825–34. doi: 10.1161/ATVBAHA.116.307225 242 Yang

Xia

Liu

Luo

. Porphyromonas gingivalis facilitated the foam cell formation via lysosomal integral membrane protein 2 (LIMP2). J Periodontal Res (2021) 56(2):265–74. doi: 10.1111/jre.12812 243 Rho

Kim

Joo

Lee

Park

. Periodontal pathogens promote foam cell formation by blocking lipid efflux. J Dent Res (2021) 100(12):1367–77. doi: 10.1177/00220345211008811 244 Durham

Speer

Scatena

Giachelli

Shanahan

. Role of smooth muscle cells in vascular calcification: implications in atherosclerosis and arterial stiffness. Cardiovasc Res (2018) 114(4):590–600. doi: 10.1093/cvr/cvy010 245 Doran

Meller

McNamara

. Role of smooth muscle cells in the initiation and early progression of atherosclerosis. Arterioscler Thromb Vasc Biol (2008) 28(5):812–9. doi: 10.1161/ATVBAHA.107.159327 246 Park

Kim

Park

Kim

Bae

. Infection of porphyromonas gingivalis increases phosphate-induced calcification of vascular smooth muscle cells. Cells (2020) 9(12):4–7. doi: 10.3390/cells9122694 247 Park

Kim

Hwang

Kim

Bae

. Inhibition of gastrin-releasing peptide attenuates phosphate-induced vascular calcification. Cells (2020) 9(3):5–9. doi: 10.3390/cells9030737 248 Lencel

Hardouin

Magne

. Do cytokines induce vascular calcification by the mere stimulation of TNAP activity? Med Hypotheses (2010) 75(6):517–21. doi: 10.1016/j.mehy.2010.07.011 249 Liu

Deng

Zhang

Song

Chen

Lou

. Porphyromonas gingivalis lipopolysaccharide stimulation of vascular smooth muscle cells activates proliferation and calcification. J Periodontol (2016) 87(7):828–36. doi: 10.1902/jop.2016.150602 250 Cao

Luo

Zhong

. Gingipains from porphyromonas gingivalis promote the transformation and proliferation of vascular smooth muscle cell phenotypes. Int J Clin Exp Med (2015) 8(10):18327–34. 251 Yang

Guo

Jia

. Porphyromonas gingivalis-derived outer membrane vesicles promote calcification of vascular smooth muscle cells through ERK1/2-RUNX2. FEBS Open Bio (2016) 6(12):1310–9. doi: 10.1002/2211-5463.12151 252 Li

Deng

Shang

Liu

Song

Sun

. Effect of porphyromonas gingivalis lipopolysaccharide on calcification of human umbilical artery smooth muscle cells co-cultured with human periodontal ligament cells. Exp Ther Med (2021) 21(6):655. doi: 10.3892/etm.2021.10988 253 Chen

Lin

Chien

Chang

Chen

. Regulation of calcification in human aortic smooth muscle cells infected with high-glucose-treated porphyromonas gingivalis. J Cell Physiol (2018) 233(6):4759–69. doi: 10.1002/jcp.26268 254 Babaniamansour

Mohammadi

Babaniamansour

Aliniagerdroudbari

. The relation between atherosclerosis plaque composition and plaque rupture. J Med Signals Sens (2020) 10(4):267–73. doi: 10.4103/jmss.JMSS_48_19 255 Carrion

Scisci

Miles

Sabino

Zeituni

. Microbial carriage state of peripheral blood dendritic cells (DCs) in chronic periodontitis influences DC differentiation, atherogenic potential. J Immunol (2012) 189(6):3178–87. doi: 10.4049/jimmunol.1201053 256 Chen

Kuo

Lin

Hung

Chiu

Chiang

. Porphyromonas gingivalis lipopolysaccharide and gingival fibroblast augment MMP-9 expression of monocytic U937 cells through cyclophilin a. J Periodontol (2022) 93(3):449–57. doi: 10.1002/JPER.19-0740 257 Popadiak

Potempa

Riesbeck

Blom

. Biphasic effect of gingipains from porphyromonas gingivalis on the human complement system. J Immunol (2007) 178(11):7242–50. doi: 10.4049/jimmunol.178.11.7242 258 Jackson

. Leucocyte trafficking via the lymphatic vasculature- mechanisms and consequences. Front Immunol (2019) 10:471. doi: 10.3389/fimmu.2019.00471 259 Alitalo

. The lymphatic vasculature in disease. Nat Med (2011) 17(11):1371–80. doi: 10.1038/nm.2545 260 Voisin

Nourshargh

. Neutrophil trafficking to lymphoid tissues: physiological and pathological implications. J Pathol (2019) 247(5):662–71. doi: 10.1002/path.5227 261 Amodini Rajakaruna

Umeda

Uchida

Furukawa

Yuan

Suzuki

. Possible translocation of periodontal pathogens into the lymph nodes draining the oral cavity. J Microbiol (2012) 50(5):827–36. doi: 10.1007/s12275-012-2030-8 262 Kuroshima

Sawa

Yamaoka

Notani

Yoshida

Inoue

. Expression of cys-cys chemokine ligand 21 on human gingival lymphatic vessels. Tissue Cell (2004) 36(2):121–7. doi: 10.1016/j.tice.2003.10.004 263 Papadakou

Bletsa

Yassin

Karlsen

Wiig

Berggreen

. Role of hyperplasia of gingival lymphatics in periodontal inflammation. J Dent Res (2017) 96(4):467–76. doi: 10.1177/0022034516681762 264 Tal

Lim

Gurevich

Milo

Shipony

. DC Mobilization from the skin requires docking to immobilized CCL21 on lymphatic endothelium and intralymphatic crawling. J Exp Med (2011) 208(10):2141–53. doi: 10.1084/jem.20102392 265 Miles

Zakhary

El-Awady

Scisci

Carrion

O'Neill

. Secondary lymphoid organ homing phenotype of human myeloid dendritic cells disrupted by an intracellular oral pathogen. Infect Immun (2014) 82(1):101–11. doi: 10.1128/IAI.01157-13 266 Murad

HAS

Rafeeq

Alqurashi

TMA

. Role and implications of the CXCL12/CXCR4/CXCR7 axis in atherosclerosis: still a debate. Ann Med (2021) 53(1):1598–612. doi: 10.1080/07853890.2021.1974084 267 Chakraborty

Zawieja

Wang

Lee

Wang

von der Weid

. Lipopolysaccharide modulates neutrophil recruitment and macrophage polarization on lymphatic vessels and impairs lymphatic function in rat mesentery. Am J Physiol Heart Circ Physiol (2015) 309(12):H2042–57. doi: 10.1152/ajpheart.00467.2015 268 Martel

Fulp

Platt

Gautier

Westerterp

. Lymphatic vasculature mediates macrophage reverse cholesterol transport in mice. J Clin Invest. (2013) 123(4):1571–9. doi: 10.1172/JCI63685 269 Lim

Thiam

Yeo

Bisoendial

Hii

McGrath

. Lymphatic vessels are essential for the removal of cholesterol from peripheral tissues by SR-BI-mediated transport of HDL. Cell Metab (2013) 17(5):671–84. doi: 10.1016/j.cmet.2013.04.002 270 Rademakers

van der Vorst

Daissormont

Otten

Theodorou

Theelen

. Adventitial lymphatic capillary expansion impacts on plaque T cell accumulation in atherosclerosis. Sci Rep (2017) 7:45263. doi: 10.1038/srep45263 271 Martel

Randolph

. Atherosclerosis and transit of HDL through the lymphatic vasculature. Curr Atheroscler Rep (2013) 15(9):354. doi: 10.1007/s11883-013-0354-4 272 Wang

Luan

Chen

Zhao

Guo

. Mitochondrial polymorphisms and dysfunction related to aggressive periodontitis: a pilot study. Oral Dis (2014) 20(5):490–8. doi: 10.1111/odi.12163 273 Choi

Spooner

DeGuzman

Koutouzis

Ojcius

Yilmaz

. Porphyromonas gingivalis-nucleoside-diphosphate-kinase inhibits ATP-induced reactive-oxygen-species via P2X7 receptor/NADPH-oxidase signalling and contributes to persistence. Cell Microbiol (2013) 15(6):961–76. doi: 10.1111/cmi.12089 274 Sun

Zhang

Liu

. Endoplasmic reticulum stress affects lipid metabolism in atherosclerosis Via CHOP activation and over-expression of miR-33. Cell Physiol Biochem (2018) 48(5):1995–2010. doi: 10.1159/000492522 275 Linton

Tao

Linton

Yancey

. SR-BI: A multifunctional receptor in cholesterol homeostasis and atherosclerosis. Trends Endocrinol Metab (2017) 28(6):461–72. doi: 10.1016/j.tem.2017.02.001 276 Song

Kim

Park

Kim

Choi

Cho

. SR-BI mediates high density lipoprotein (HDL)-induced anti-inflammatory effect in macrophages. Biochem Biophys Res Commun (2015) 457(1):112–8. doi: 10.1016/j.bbrc.2014.12.028 277 Lewis

Williams

Eisenbarth

. Structure and function of the immune system in the spleen. Sci Immunol (2019) 4(33):1. doi: 10.1126/sciimmunol.aau6085 278 He

Liang

. Th17/Treg imbalance and atherosclerosis. Dis Markers (2020) 2020:8821029. doi: 10.1155/2020/8821029 279 Cai

Kobayashi

Hashizume-Takizawa

Kurita-Ochiai

. Porphyromonas gingivalis infection enhances Th17 responses for development of atherosclerosis. Arch Oral Biol (2014) 59(11):1183–91. doi: 10.1016/j.archoralbio.2014.07.012 280 Wang

Zhang

Jin

. Porphyromonas gingivalis lipopolysaccharide induced proliferation and activation of natural killer cells in vivo. Molecules (2016) 21(8):1–5. doi: 10.3390/molecules21081086 281 Tsilingiri

de la Fuente

Relano

Sanchez-Diaz

Rodriguez

Crespo

. Oxidized low-density lipoprotein receptor in lymphocytes prevents atherosclerosis and predicts subclinical disease. Circulation (2019) 139(2):243–55. doi: 10.1161/CIRCULATIONAHA.118.034326