Abstract
ABSTRACT
Background
Tumor‐associated macrophages (TAMs) play a pivotal role in shaping the inflammatory microenvironment of colorectal polyps. MiR‐146a‐5p has been implicated in innate immune regulation, but its function in TAM polarization and polyp pathogenesis remains unclear.
Methods
Forty paired colorectal polyp and adjacent normal tissues were analyzed for miR‐146a‐5p, IRAK1, and macrophage markers (CD86/CD206) by qRT‐PCR and immunohistochemistry. THP‐1‐derived macrophages were polarized to M1 or M2 phenotypes, transfected with miR‐146a‐5p mimic/inhibitor, si‐IRAK1, or IRAK1 overexpression plasmids, and treated with polyp‐conditioned medium (Polyp‐CM) where indicated. Macrophage polarization was evaluated by flow cytometry, qRT‐PCR, ELISA, and Western blot. Dual‐luciferase reporter assays in HEK293T cells validated direct targeting of IRAK1 by miR‐146a‐5p. Rescue experiments assessed the functional contribution of IRAK1 and NF‐κB signaling to M1 polarization.
Results
MiR‐146a‐5p was significantly downregulated in polyp tissues, whereas IRAK1 and M1 macrophage markers (CD86, iNOS) were upregulated, with a strong negative correlation between miR‐146a‐5p and IRAK1. Overexpression of miR‐146a‐5p in macrophages suppressed M1 polarization, decreased pro‐inflammatory cytokines (TNF‐α, IL‐6), and reduced NF‐κB activation, while miR‐146a‐5p inhibition enhanced these responses. Dual‐luciferase assays confirmed IRAK1 as a direct target of miR‐146a‐5p. Silencing IRAK1 or inhibiting NF‐κB rescued the pro‐M1 effects induced by miR‐146a‐5p loss. Conversely, IRAK1 overexpression promoted M1 polarization, which was attenuated by miR‐146a‐5p co‐expression. Polyp‐CM experiments corroborated these effects under tumor‐mimicking inflammatory conditions.
Conclusion
These findings suggest that the miR‐146a‐5p/IRAK1/NF‐κB axis may represent a potential therapeutic target for modulating macrophage‐mediated inflammatory responses in colorectal polyps.