Stroke is a cerebrovascular disease that can include focal or global brain tissue impairment due to vascular dysfunction brought on by a variety of reasons (24). Hemorrhagic and ischemic stroke are its two primary varieties. Stroke is a serious risk to a patient’s health and life because of its high incidence, disability, recurrence, and fatality rates (25). New data emphasizes how important NETs are to the pathophysiology of stroke. A focused or global disruption of the cerebral blood supply can result from the migration of peripheral thrombi or the creation of local thrombi, which can cause an ischemic stroke. The impacted brain tissue sustains irreparable damage as a result (26, 27).

Ischemic damage activates an immunological response, allowing immune cells to migrate and infiltrate the brain parenchyma. Within 24 hours of ischemia, active neutrophils and the production of NETs have been seen in ischemic brain tissue, according to studies. NETs secrete a variety of cytotoxic proteases, including histones, myeloperoxidase (MPO), and elastase, which can directly cause endothelial cell damage, increase vascular permeability, and disrupt the blood-brain barrier (BBB) (28, 29). In 2019, Kim et al. discovered that high-mobility group box 1 (HMGB1) is implicated in NET-mediated neuronal injury in ischemic stroke. HMGB1 can cause NET formation through the CXCR4 and TLR4 signaling pathways (30). NETs also contribute to the formation of thrombus by providing a scaffold, promoting the coagulation cascade, and participating in the stroke’s pathological process. Demyanets et al. demonstrated that NETs enhance the coagulation cascade by linking vWF and TFPI, which contributes to thrombosis stabilization (31). Coagulation factor XII is activated by the DNA backbone of NETs in the absence of platelets, and along with coagulation factor XI, it supports the coagulation cascade and the generation of thrombin (32). Furthermore, NET-related changes have been seen in the thrombus structure of ischemic stroke patients as well as individuals with other vascular disorders such coronary artery disease and peripheral artery disease. These changes have been found to have a considerable impact on thrombus stability (33). Furthermore, NETs have been linked to changes in cerebral revascularization and vascular remodeling following ischemic stroke (19).

Intracerebral hemorrhage (ICH) is a frequent cerebrovascular condition, and neuroinflammation is thought to play an important role in its pathogenesis. In experimental ICH models, neutrophil infiltration is considerable in both the core and periphery of hematomas (34). Neutrophil extracellular traps (NETs) have also been discovered as significant factors to the pathogenesis of ICH. An experimental ICH rat model revealed that using DNAse 1 to break down NETs enhanced the fibrinolysis of hematomas induced by tPA, reduced brain swelling, lowered cell death, and improved functional outcomes. They found that NETs impaired the action of tPA in breaking down clots in rats with ICH, and targeting NETs could be a new option to improve fibrinolytic therapy after ICH (35). Wang et al. (36) found that NETs could aggravate tissue plasminogen activator (tPA)-induced brain damage in stroke patients by inhibiting cyclic GMP-AMP synthase (cGAS) (36). Furthermore, RNase has been demonstrated to suppress NET formation in a mouse model of subarachnoid hemorrhage, indicating its potential therapeutic efficacy (37).

In summary, NETs play a pivotal role in ischemic brain injury, and targeting NETs may represent a promising therapeutic strategy for stroke. Despite substantial proof from clinical and animal studies clarifying the mechanisms and roles of NETs in stroke, few NET-targeting treatments have been implemented in clinical practice. More research is critically needed to close the gap and promote treatment development.

NETs play a pivotal role in autoimmune diseases, particularly in central nervous system (CNS) autoimmune disorders such as multiple sclerosis (MS), autoimmune encephalitis, and neuropsychiatric systemic lupus erythematosus (NPSLE) (19, 38, 39). In these conditions, NETs act as reservoirs for autoantibodies, exacerbating autoimmune responses by promoting the production and deposition of autoantibodies (19). Furthermore, NETs can exacerbate the inflammatory environment by activating the complement system and promoting the production of pro-inflammatory cytokines, ultimately causing brain tissue damage. For example, in multiple sclerosis, NETs have been found to be strongly correlated with disease activity and severity (38, 39). Studies have shown that NET biomarkers in MS patients’ serum are significantly enhanced, and that they correlate favorably with disease relapse and progression. Further research has revealed that NETs can directly damage neurons and glial cells, contributing to disease exacerbation (19). According to studies on SLE murine models, the activation of the BBB by anti-NR2A/B antibodies results in higher expression of endothelial cell adhesion molecules, which aids in the recruitment, rolling, adhesion, and transmigration of neutrophils, ultimately causing more NETosis within the spinal canal. The release of NETs into the spinal canal contributes to neurotoxicity by causing neuronal cell death, which subsequently leads to the neuropsychiatric symptoms of SLE (40, 41).

The role of NETs in autoimmune encephalitis is also gaining increasing attention. In a study investigating the pathogenesis of anti-NMDAR encephalitis, Qiao et al. identified NETosis in the serum of patients with anti-NMDAR encephalitis (42). Neutrophils from the peripheral blood of individuals with anti-NMDAR encephalitis showed a higher propensity to generate NETs than healthy controls. These individuals had elevated levels of TNF-α, IL-6, and IL-8, which were positively correlated with H3Cit levels. This suggests that NETs are important regulators of the immunoinflammatory processes that underlie anti-NMDAR encephalitis. NET research in autoimmune encephalitis is still in its infancy, nevertheless. Even while certain NET mechanisms in this context have been discovered, there are still a lot of unanswered questions. In order to provide new approaches for the treatment of autoimmune encephalitis, future research is required to clarify the precise molecular pathways of NETs in the pathophysiology of autoimmune encephalitis and to pinpoint particular therapeutic targets against NETs.

Recent studies suggest that NETs may play a role in the pathogenesis of neurodegenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD) (16, 43, 44). Although the precise mechanisms remain incompletely understood, it is hypothesized that NETs contribute to pathological processes such as inflammatory responses and oxidative stress. Research has indicated that the deposition of β-amyloid (Aβ), a characteristic clinical feature of Alzheimer’s disease, is linked to the creation of NET (45). Aβ can cause neutrophil activation and the development of NETs (16, 19). NET constituents including DNA and histones have the ability to attach to Aβ and form complexes that worsen oxidative stress and inflammatory reactions. Additionally, NETs may hasten neuronal degeneration by encouraging the release of oxidative stress products and pro-inflammatory cytokines. The study by Leon et al. revealed an elevation in neutrophil levels in AD brains and in the murine APP/PS1 model (46). In mouse models of Alzheimer’s disease, findings suggest that vascular alterations may encourage neutrophil adhesion and NETosis, with MPO from neutrophils possibly leading to oxidative stress in the vascular system (46).

There is growing evidence that NETs may also play a role in the pathophysiology of Parkinson’s disease. Degeneration of dopaminergic neurons in the substantia nigra and the development of Lewy bodies are hallmarks of Parkinson’s disease (43). Researchers noted that in tissue sections from primary amyloidosis patients, amyloid fibrils significantly prompted NETs release, which relied heavily on the NADPH oxidase system (47). NETs may increase oxidative stress and inflammatory reactions, which could lead to neuronal degeneration. The development of PD is believed to be closely tied to inflammation caused by microglia. Previous research has indicated that CADM3 is involved in the adhesion of inflammatory cells to endothelial cells and in microglia-mediated inflammation (48). According to Qiang et al., CADM3 might play a role in the progression of PD via NETs (43). The research further demonstrated that the co-DEGs of GPR78, CADM3, and CACNA1E connect NETs with Parkinson’s disease and established a nomogram model for diagnosing PD based on these genes. An association between NETs and PD exists, and the expression of genes GPR78, CADM3, and CACNA1E might serve as biomarkers for PD related to NETs. Therefore, in neurodegenerative diseases, reducing inflammation and oxidative stress by preventing NET formation or encouraging the removal of preexisting NET structures may slow the course of the disease.

The formation of immunothrombosis after traumatic brain injury (TBI) is a critical pathophysiological mechanism contributing to poor outcomes (49). Numerous studies have indicated the possible involvement of NETs in TBI pathology, despite the fact that the relationship between NETs and immunothrombosis in TBI remains unclear (7). Unfavorable prognoses are frequently the result of circulatory disruptions, cerebral blood vessel damage, and blood-brain barrier impairment after traumatic brain injury. After traumatic brain injury (TBI), studies show a large rise in NETs in brain tissues, where they are strongly linked to thrombus formation and inflammatory reactions. The release of NETs by neutrophils is linked to poorer outcomes in TBI and stroke by hindering revascularization and vascular remodeling (23). Coagulopathy is a major factor in the deaths and disabilities linked to TBI. The generation of NETs was driven by HMGB1 from activated platelets, contributing to the procoagulant activity observed in TBI. Moreover, coculture experiments demonstrated that NETs compromised the endothelial barrier and led these cells to adopt a procoagulant phenotype (50). Thus, exploring the processes of NETs in TBI may offer new therapeutic approaches to enhance results as well as deeper understanding of the pathophysiology alterations that occur after TBI.

In brain tumors, the formation and release of neutrophil extracellular traps (NETs) are closely associated with tumor malignancy, invasiveness, and prognosis (7, 19). Research by Zhang et al. showed that platelets from glioma patients were more likely to induce NET formation than those from healthy individuals, contributing to the hypercoagulable state in these patients (51). In another glioma study, it was observed that high-grade glioma caused more neutrophil infiltration and NETs formation than low-grade glioma. Excessive NETs production enhanced the proliferation, migration, and invasion of glioma cells. Moreover, their findings indicate that NETs generated by neutrophils infiltrating tumors facilitate communication between glioma development and the tumor microenvironment by modulating the HMGB1/RAGE/IL-8 pathway (52). Initial evidence suggested that NET-associated proteins like elastase, proteinase-3, and cathepsin G facilitate brain tumor invasion by breaking down extracellular matrix structures (20). Current research has highlighted the role of NETs in brain tumors, but additional studies are required to understand the molecular mechanisms and aid in developing precise targeted treatments.