Semaglutide Attenuates Inflammatory Macrophage Polarization and Promotes Changes Associated with Mitochondrial...

Background/Objectives: Chronic metabolic inflammation is associated with pro-inflammatory macrophage activation and mitochondrial dysfunction. Semaglutide, a widely used GLP-1 receptor agonist, has been reported to possess systemic anti-inflammatory properties, but its action on human macrophages, especially in the context of mitochondrial regulation, remains poorly understood. The aim of the study was to evaluate the direct effect of semaglutide on macrophage polarization and to investigate the roles of cAMP signaling and mitochondrial regulation in this process. Methods: THP-1 and U-937 monocytic cell lines were differentiated into macrophages and polarized into the M1-like phenotype using LPS/IFN-γ. Cells were treated with 100 nM semaglutide in the presence or absence of the adenylyl cyclase inhibitor SQ22536. Intracellular cAMP levels, mRNA expression of macrophage markers and key regulators of mitochondrial biogenesis (SIRT1 and PGC-1α), and levels of pro- and anti-inflammatory cytokines were determined. The COX-1/SDH-A and mtDNA/nDNA ratios were analyzed as markers of mitochondrial biogenesis. Results: Semaglutide induced cAMP accumulation in M0- and M1-like macrophages derived from both cell lines. This response was significantly attenuated by GLP-1R antagonist exendin(9-39), supporting the presence of functional GLP-1R signaling. Semaglutide supplementation during inflammatory polarization resulted in reduced levels of pro-inflammatory markers (CD80/CD86, TNF-α, IL-6) and increased expression of M2-associated genes CD206 and CD163 and secretion of the anti-inflammatory cytokine IL-10. Semaglutide also increased SIRT1 and PGC-1α expression, the COX-1/SDH-A ratio, and the mtDNA/nDNA ratio, suggesting activation of processes associated with mitochondrial biogenesis. All of the effects of semaglutide described above were attenuated by SQ22536, supporting an important contribution of cAMP signaling to these responses. Conclusions: Semaglutide acts directly on human monocytic cell line-derived macrophages, attenuating the M1-like program and promoting a shift toward a less inflammatory phenotype. These effects strongly depend on cAMP signaling and are accompanied by increased expression of SIRT1 and PGC-1α and mitochondrial changes consistent with enhanced biogenesis.