Formononetin Mediates α7nAChR to Inhibit Macrophage Polarization and Ameliorate Atherosclerotic Plaque

Objective: To explore the molecular mechanism of α7 nicotinic acetylcholine receptor (α7nAChR) mediated by Formononetin (FMN) in inhibiting macrophage inflammatory polarization and stabilizing atherosclerotic plaque. Methods: SiRNA α7nAChR was transfected into THP-1-induced M0 cells and treated with FMN. Oil Red O staining was used to evaluate macrophage lipid deposition. RT-qPCR was used to detect α7nAChR, COX-2, IL-1β, IL-6, HO-1, and SHIP1 expression in M1 and M2 macrophages. Western blot was used to detect α7nAChR, iNOS, CD206, CD68, p-JAK2, and p-STAT3 protein expression in M1 and M2 macrophages. Results: Compared with the control group, FMN-mediated α7nAChR reduced lipid deposition in M1 and M2 macrophages. RT-qPCR results showed that FMN intervention significantly downregulated COX-2 and IL-1β expression in M1 (P < 0.05). α7nAChR expression significantly reduced COX-2, IL-6, and IL-1β expression in M2 (P < 0.05) and significantly increased HO-1 and SHIP1 expression (P < 0.05). FMN-mediated α7nAChR significantly decreased the expression of iNOS, CD68, p-JAK2, and p-STAT3 in M1 and M2 macrophages and significantly increased the expression of CD206 protein by Western blot (P < 0.05). Discussion: This study, for the first time, elucidated the mechanism of FMN regulating macrophage polarization through the α7nAChR/JAK2/STAT3 axis, providing new experimental evidence for the role of the cholinergic anti-inflammatory pathway in cardiovascular diseases. However, there are some limitations, such as the limited applicability of the THP-1 cell line, the need to strengthen the dose correlation study, the bioavailability and solubility limiting clinical translation, and the lack of human toxicological data. Conclusion: FMN effectively modulates macrophage polarization through inhibition of the JAK/STAT signaling pathway while promoting α7nAChR expression.