Colorectal cancer (CRC) is a common malignant tumor of the digestive system. According to global cancer statistics in 2020, the incidence and mortality of CRC both rank third among all malignant tumors (1). The pathogenesis of CRC is associated with multiple factors, including genetic predisposition, environmental influences, lifestyle, and the gut microbiota. Notably, dysbiosis of the gut microbiota or infection with certain bacteria, such as Helicobacterpylori (H. pylori), can increase the risk of colorectal tumors (2). In addition, Gut microbiota linked to obesity is implicated in the pathogenesis of colorectal cancer (3). This is an important issue that warrants considerable attention.

Colorectal adenomas (CRA) mainly include two major categories: conventional adenomas(CAs) and sessile serrated adenomas (SSAs). CAs are further subdivided into tubular adenomas, villous adenomas, and tubulovillous (mixed) adenomas, each with distinct histological characteristics and malignant potential. SSAs are characterized by a unique serrated glandular architecture and a higher rate of malignant transformation, distinguishing them from CAs. Both types of adenomas carry a risk of malignant progression (4) and are recognized as precancerous lesions. Timely detection and intervention can reduce the risk of CRC development. Although colorectal cancer (CRC) treatment employs a multidisciplinary, multimodal integrated strategy (5), a proportion of patients present with advanced disease at diagnosis, having missed the optimal window for radical treatment. Consequently, their overall prognosis is significantly worse than that of early-stage patients (Stage I patients exhibit a > 90% 5-year survival rate) (6). Thus, there is an urgent need to identify novel tumor biomarkers that can predict tumor progression and serve as potential therapeutic targets.

The tumor microenvironment (TME) is a complex and dynamic ecosystem with high heterogeneity, Macrophages within the TME, known as tumor-associated macrophages (TAMs), are important immune effector cells primarily derived from peripheral blood monocytes and tissue-resident macrophages. TAMs consist mainly of two subsets, M1 and M2 (7). The M1 phenotype generally inhibits tumor growth, whereas the M2 phenotype promotes tumor growth. The balance between both subsets determines the nature of the immune response in the TME.

Cell surface markers of TAMs primarily include CD68 (pan-macrophage), CD86 (M1-like macrophage markers), and CD163 (M2-like macrophage markers) (8, 9). In the TME of CRC, the polarization state of TAMs is associated with cancer-specific survival, and M1-like/M2-like TAMs phenotypes exhibit distinct prognostic implications (10). Targeting TAMs as a therapeutic strategy has already become an effective approach to inhibit tumor progression (11). Nonetheless, the mechanisms by which TAMs evolve within the TME during the malignant progression of CRA are still not completely understood.

H.pylori infection can promote tumor development by influencing TAMs polarization in the TME. For example, sit. et al. (12) found that H.pylori phospholipase A regulates macrophage autophagy and apoptosis via the TNFR1-mediated p38 signaling pathway. Lu et al. (13) reported that interactions between reactive oxygen species and hypoxia-inducible factor-1α modulate H.pylori–induced macrophage polarization through the Akt/mTOR pathway. In addition, H.pylori infection can upregulate the expression of indoleamine 2,3-dioxygenase in macrophages, thereby inducing M2-like polarization (14). M2-like TAMs secrete various growth factors, enabling tumor cells to evade immune surveillance and elimination. Therefore, further investigation of the impact of H.pylori infection on TAMs polarization in CRA and CRC tissues is warranted.

In this study, we analyzed the expression of CD163⁺ and CD86⁺ TAMs in CRA and CRC tissues and examined their correlation with H.pylori infection, with the aim of providingreferences for clinical research.

The transition from CRA to CRC is a prolonged process that requires several decades. Therefore, early detection and resection of precancerous lesions are critical for preventing progression of CRC. TAMs have been implicated in the pathogenesis of H.pylori-related gastric malignancies (18). Wei et al. demonstrated that H.pylori can activate the JAK1/STAT1 signaling pathway in macrophages, leading to CCL3 secretion and subsequent gastric mucosal damage (19). Furthermore, H.pylori promotes gastric carcinogenesis by enhancing interleukin (IL)-6-mediated autocrine and paracrine loops between macrophages and gastric epithelial cells (20). Recent studies have also linked H.pylori infection to an elevated risk of CRC (21–24). Notably, CRC incidence decreases significantly following H.pylori eradication (25). Ralser et al. found that Helicobacter pylori infection accelerates tumorigenesis, concomitant with depletion of regulatory T (Treg) cells and pro-inflammatory T cells, goblet cell deficiency, and STAT3 pathway activation (26). Luo et al. further reported that H.pylori-induced temperate phage expansion and microbiota interactions may contribute to CRC pathogenesis (27). Our study found that H.pylori infection rates were highest in CRC patients, followed by those with CRA, and lowest in the normal group, suggesting a positive correlation between infection and disease severity. This supports the hypothesis that H. pylori may play a role in CRC development.

CD163 is predominantly expressed on monocytes and tissue macrophages, Prior studies indicate that CD163⁺ TAMs may induce regulatory T cell expansion via IL-10/TGF-sl thereby exhausting effector T cells. Numerous studies have reported that CD163 is increased in different cancers and is associated with poor prognosis due to its tumor-promoting functions (28–30). For example, Lira et al. demonstrated that M2-like macrophages facilitate cervical cancer progression via the STAT3/NF-κB pathway (31), whereas Ito et al. showed that in CRC, M2-like macrophages enhance their resistance to oxidative stress through the Nrf2/HO-1 axis, promoting survival in the TME (32). CD86 is an immunophenotype associated with antitumor immune modulation, Evidence suggests that CD86⁺ TAMs may inhibit CD8⁺ T cell activation through PD-L1 co-expression. Teng et al. reported that CASC19 transferred from M1-like macrophages to colon cancer cells via exosomes inhibited tumor cell proliferation and migration by targeting miR-410-3p (33). A reduction in M1-like macrophages infiltration has also been associated with poor prognosis in right-sided CRC patients (34). This study revealed progressively elevated CD163⁺ and CD86⁺ TAMs levels in colorectal tissues: normal mucosa < CRA < CRC, suggesting their potential involvement in immune modulation during tumor progression. These findings offer insights for developing potential immunotherapeutic and prognostic strategies in CRC.

Several studies have suggested a link between H.pylori infection and macrophage polarization. Peng et al. found that H.pylori induced indoleamine 2,3-dioxygenase expression and M2-like polarization (14). Lu et al. reported that in all stages of gastric lesions, patients who are H.pylori-positive showed higher expression of CD86 and CD206 compared with H. pylori-negative individuals (13). our study found elevated levels of CD163⁺ and CD86⁺ TAMs in H.pylori-infected patients. This suggests that H.pylori may recruit TAMs through specific pathways, with testable hypotheses including: (i) H.pylori drives Treg-mediated immunosuppression by recruiting CD163⁺ TAMs, verifiable via mIF assessing spatial co-localization between CCL19⁺ epithelial cells and CD163⁺ TAMs; (ii) CD86⁺ TAMs in CRC patients lose antigen-presenting capacity and undergo transformation into a ‘pseudo-activated’ state, testable through flow-sorted CD86⁺ TAMs co-cultured with CD8⁺ T cells followed by PD-1 expression analysis. Thus, elevated CD163⁺CD86⁺ TAM levels may associate with T-cell dysfunction, though their causality and H.pylori’s direct role require further validation.

Zhang et al. found that CD163⁺ macrophages promote polyp progression in pediatric patients by inhibiting T-cell responses via TGF-β production (35). Peyravian et al. showed that CD86 expression positively correlated with dysplasia in polyps (36). Our univariate analysis indicated that patients with adenomas ≥1 cm or multiple adenomas exhibited significantly higher expression of both CD163⁺ and CD86⁺ TAMs. Multivariate regression further confirmed this relationship: CD163⁺ TAMs (β = 7545.441, 95% CI: 5575.552 ~ 9515.329) and CD86⁺ TAMs (β = 4488.870, 95% CI: 3477.967 ~ 5499.773) were significantly increased in patients with larger adenomas. Our univariate analysis found that in CRC patients, lower differentiation, advanced TNM stage, and lymph node metastasis were associated with higher expression of CD163⁺ TAM and lower expression of CD86⁺ TAM. Consistent with previous studies (37, 38). These results suggest that TAMs expression reflect disease severity and may contribute to assess malignancy risk. The M2-like/M1-like macrophages ratio is a useful prognostic indicator, Fadhil et al. reported higher M2-like/M1-like macrophages ratios in breast cancer patients than in controls (39), and Parekh et al. found similar results in advanced oral submucous fibrosis and squamous cell carcinoma (40). Our study further demonstrated a progressive increase in the CD68⁺CD163⁺/CD68⁺CD86⁺ ratio from normal tissue through CRA to CRC, highlighting the role of macrophage phenotypic switching and imbalance in TME homeostasis during carcinogenesis. Additionally, the body mass index is a known risk factor for CRC incidence and mortality (41). Obesity may enhance macrophage activation by suppressing miR-192 expression (42). In CRC groups, patients with obesity exhibited higher CD163⁺ TAM expression. Multivariate regression confirmed this association in CRC (β = 16405.198, 95% CI: 11878.446 ~ 20931.949), suggesting that obesity-induced TME changes may contribute to CD163⁺ TAM enrichment and tumorigenesis.

This study also has several limitations:(i) The single-center, cross-sectional design precludes determination of the temporal sequence and causal relationships between H.pylori infection and TAMs;(ii) The relatively small sample size in the CRC cohort may compromise the precision and statistical power of the multivariate regression model. Although stepwise regression was employed to mitigate overfitting, the findings should be interpreted with caution and validated in larger cohorts;(iii) Elevated H.pylori prevalence (~90%) in the CRC cohort risks overestimating its effects on TAMs polarization, compromising findings’ generalizability;(iv) Reliance on UBT as the sole detection method may introduce non-differential misclassification, potentially attenuating effect sizes. Due to sample size limitations, we could not quantify bias severity by excluding high-risk misclassified subsets. Future studies should incorporate H.pylori stool antigen testing to comprehensively enhance diagnostic accuracy; (v) the coverage of macrophage marker panels was limited; (vi) residual confounding factors were not fully controlled, in addition, multiple comparisons introduced statistical inference risks.

Future studies should: (i) Validate and refine the TAMs differentiation model in expanded prospective cohorts stratified by H.pylori infection status; (ii) Establish a multimodal H.pylori detection framework integrating stool antigen testing, PCR genotyping, and culture verification; (iii) Spatially resolve TAM-tumor cell crosstalk networks under H.pylori-positive conditions using transcriptomics; (iv) Verify H.pylori-mediated TAMs regulation via flow-sorted subpopulations and organoid co-cultures targeting candidate pathways identified in (3).

In conclusion, this study found that CD163⁺ and CD86⁺ TAMs are significantly increased in CRC and are associated with H. pylori infection. Their expression correlates with lesion severity, indicating a potential role in CRC pathogenesis. However, further studies are warranted to elucidate their exact mechanisms in colorectal tumor development and progression.