Empagliflozin attenuates inflammation levels in autoimmune myocarditis through the STAT3 pathway and macrophage phenotype transformation

To investigate the anti-inflammatory actions and molecular mechanisms of the sodium/glucose cotransporter 2 (SGLT-2) inhibitor empagliflozin on autoimmune myocarditis. The experimental autoimmune myocarditis (EAM) mouse model was constructed using peptides, and the therapeutic effects of empagliflozin on cardiac inflammation and fibrosis were observed using hematoxylin and eosin (HE), Sirius red staining, and Masson's trichome staining. Western blotting was used to identify the actions of empagliflozin on the surface marker expression levels of M2 macrophages and inflammatory factors. In vitro, experiments were completed using lentiviral overexpression of SGLT-2 in macrophages. Macrophage inflammation and anti-inflammatory models were constructed using lipopolysaccharide and interleukin-4, respectively. Enzyme-linked immunosorbent assay, immunofluorescence staining, and reverse-transcription polymerase chain reaction were applied to detect the effects of empagliflozin on the levels of inflammatory factors and macrophage surface markers. Western blotting was used to identify variability in SGLT-2 expression and the role of empagliflozin on the signal transducer and activator of the transcription 3 (STAT3) pathway. The Genomic Spatial Event 142564 dataset was studied in an EAM mouse model. We selected single-cell sequencing results from day 0 and day 21 of modeling to visualize differentially expressed genes. Immune cell infiltration correlation analysis was implemented to explore the expression of inflammatory factors and phenotypic markers. Empagliflozin increased the expression of the M2 macrophage surface marker CD206 and reduced the level of inflammatory factors in the EAM mouse model while reducing the levels of inflammation and fibrosis. In vitro experiments revealed that the phosphorylation of STAT3 pathway was enhanced after macrophages were polarized to M1 phenotype by LPS, the phosphorylation of STAT3 pathway was inhibited after empagliflozin intervention, and the levels of inflammatory factors were decreased. Empagliflozin can reduce the level of inflammation in autoimmune myocarditis through the STAT3 pathway and macrophage phenotype transformation. These results indicate the expression of SGLT-2 can be a target for autoimmune myocarditis therapy.