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Published on: November 28, 2019
MiR-146a-5p Suppresses M1 Polarization of Tumor-Associated Macrophages via IRAK1/NF-κB Signaling in Colorectal Polyps
Peng Song1, Lianhui Wu1, Huabin Qiu1
1Digestive Endoscopy Room Sanming First Hospital Affiliated to Fujian Medical University Sanming China.
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.
Insights
MicroRNA-146a-5p (miR-146a-5p) is reduced in colorectal polyps, promoting M1 macrophage polarization via IRAK1/NF-κB signaling. Restoring miR-146a-5p may target polyp inflammation.
Area of Science:
- Immunology
- Molecular Biology
- Gastroenterology
Background:
- Tumor-associated macrophages (TAMs) influence colorectal polyp inflammation.
- The role of miR-146a-5p in TAM polarization and polyp development is unclear.
Purpose of the Study:
- Investigate miR-146a-5p's function in TAM polarization within colorectal polyps.
- Determine the molecular mechanisms linking miR-146a-5p, IRAK1, and M1 macrophage polarization.
Main Methods:
- Analyzed miR-146a-5p, IRAK1, and macrophage markers in polyp tissues.
- Utilized THP-1 derived macrophages, transfected with miR-146a-5p mimics/inhibitors, si-IRAK1, or IRAK1 plasmids.
- Assessed macrophage polarization, cytokine production, and NF-κB activation.
- Validated IRAK1 as a direct miR-146a-5p target using dual-luciferase assays.
Main Results:
- MiR-146a-5p was downregulated, while IRAK1 and M1 markers (CD86, iNOS) were upregulated in polyps.
- Overexpressing miR-146a-5p suppressed M1 polarization and pro-inflammatory cytokine release.
- IRAK1 was confirmed as a direct miR-146a-5p target; silencing IRAK1 or inhibiting NF-κB rescued M1 polarization.
Conclusions:
- The miR-146a-5p/IRAK1/NF-κB pathway regulates M1 macrophage polarization in colorectal polyps.
- This axis represents a potential therapeutic target for modulating inflammation in colorectal polyps.
