SGLT2 inhibitors prevent LPS-induced M1 macrophage polarization and alleviate inflammatory bowel disease by downregulating NHE1 expression

Abstract

Background: Classically activated M1 macrophages, characterized by aberrant glycolysis and secretion of inflammatory cytokines, play pivotal roles in inflammatory diseases, including inflammatory bowel disease (IBD). Recently, sodium-glucose co-transporter 2 (SGLT2) inhibitors were shown to suppress Na⁺/H⁺ exchanger 1 (NHE1) and Na⁺/Ca²⁺ exchanger 1 (NCX1) activity, regulating downstream intracellular Ca²⁺ concentrations in cardiomyocytes. However, whether SGLT2 inhibitors regulate M1 macrophage polarization by downregulating NHE1 and NCX1 remains unknown.

Methods: We analyzed cellular responses to SGLT2 inhibitors using mouse bone marrow-derived macrophages and peritoneal macrophages treated with lipopolysaccharide (LPS). To induce IBD, we used a dextran sulfate sodium salt-induced colitis mouse model.

Results: We observed that NHE1 and NCX1 were overexpressed in LPS-treated macrophages, leading to M1 macrophage polarization. Mechanistically, NHE1 and NCX1-mediated Ca²⁺ accumulation in the macrophage resulted in enhanced glycolysis by promoting PI3K/AKT/mTORC1 signaling. SGLT2 inhibitors suppressed both the expression levels and activities of NHE1 and NCX1, and consequently downregulated PI3K/AKT/mTORC1 signaling and glycolysis in LPS-treated macrophages. We observed inhibition of LPS-stimulated M1 polarization and cytokine production by SGLT2 inhibitors in vitro, ex vivo, and in an IBD mouse model.

Conclusions: NHE1 promotes M1 macrophage polarization and SGLT2 inhibitors are a novel strategy to treat M1 macrophage-mediated inflammatory diseases, including IBD.

Keywords: Glycolysis; Inflammatory bowel disease; Macrophage; NHE1; SGLT2 inhibitors.