MiR-146a-5p Contributes to Microglial Polarization Transitions Associated With AGEs
Yinqiong Huang1, Xiaoyun Lin2, Xiahong Lin3
1Department of Endocrinology, Centre of Neurological and Metabolic Research, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, 360000, China. yinqiongh@fjmu.edu.cn.
Abstract:
M1/M2 polarization transitions of microglial phenotypes determine the states of neuroinflammation, which is critical in the pathophysiology of diabetic encephalopathy. This study aims to investigate the effects of advanced glycation end products (AGEs) on the microglial polarization state, the role of miR-146a-5p in the regulation of microglial polarization, and the underlying signaling pathways. BV-2 cells were incubated with N-ε-carboxymethyl lysine (CML), one kind of Advanced Glycation End Products (AGEs), to induce polarization. CD11b and iNOS and CD206 and Arg-1 were used to evaluate M1 and M2 microglia, respectively. The mRNA and protein expression levels of miR-146a-5p, transcription factor NF-κB, and inflammasome NLRP3 were measured. High and low expression of miR-146a-5p in the BV-2 cell line was generated by lentivirus transfection technology. RAGE, TLR-4, and NF-κB antagonists were applied to evaluate the underlying signaling pathways. Compared with the control group, CML upregulated the M1 phenotype and downregulated the M2 phenotype. These effects were reversed by overexpression of miR-146a. Furthermore, the expression of inflammasome NLRP3 and NF-κB was upregulated in the CML group and was reduced after miR-146a overexpression. And then overexpression of miR-146a effects was reversed by inhibition miR-146a expression. An NF-κB antagonist (PDTC), a RAGE antagonist (FPS-ZMI), and a TLR-4 antagonist (TLI-095) all reversed the polarization state induced by CML. In summary, CML induced polarization transitions to M1 phenotype and promoted inflammasome NLRP3 expression in BV-2 cells. The RAGE or TLR-4/miR-146a/NLRP3/NF-кB pathway might participate in the regulation of CML-induced BV-2 polarization.
Insights
Advanced glycation end products (AGEs) like CML promote M1 microglial polarization in diabetic encephalopathy. miR-146a-5p overexpression reverses this, suggesting a therapeutic target for neuroinflammation.
Area of Science:
- Neuroscience
- Immunology
- Endocrinology
Background:
- Microglial M1/M2 polarization dictates neuroinflammation, crucial in diabetic encephalopathy.
- Advanced glycation end products (AGEs) are implicated in diabetic complications, including brain dysfunction.
Purpose of the Study:
- To investigate AGEs' impact on microglial polarization.
- To elucidate the role of miR-146a-5p in AGE-induced microglial changes.
- To identify underlying signaling pathways, including RAGE, TLR-4, NLRP3, and NF-κB.
Main Methods:
- BV-2 microglial cells were treated with N-ε-carboxymethyl lysine (CML), an AGE, to induce polarization.
- Microglial M1/M2 markers (CD11b, iNOS, CD206, Arg-1) were assessed.
- miR-146a-5p, NF-κB, and NLRP3 expression were quantified.
- Lentivirus vectors modulated miR-146a-5p levels; pathway antagonists (RAGE, TLR-4, NF-κB) were used.
Main Results:
- CML treatment shifted BV-2 cells towards the M1 phenotype and suppressed the M2 phenotype.
- miR-146a-5p overexpression counteracted CML-induced M1 polarization and M2 suppression.
- CML upregulated NLRP3 and NF-κB; miR-146a-5p overexpression reduced their expression.
- RAGE, TLR-4, and NF-κB antagonists reversed CML-mediated microglial polarization.
Conclusions:
- CML induces M1 microglial polarization and NLRP3 inflammasome activation in BV-2 cells.
- The RAGE/TLR-4/miR-146a-5p/NLRP3/NF-κB pathway is implicated in CML-induced microglial polarization.
- Targeting miR-146a-5p may offer a strategy to mitigate AGE-induced neuroinflammation in diabetic encephalopathy.
