Irisin alleviates the pyroptosis of β cells in <scp>T2DM</scp> by inhibiting <scp>NLRP3</scp> inflammasome through regulating <scp>miR</scp>‐19b‐3p/<scp>SOCS3</scp>/<scp>STAT3</scp> axis mediated autophagy

The purpose of this study was to analyze the mechanism by which irisin affects β-cell pyroptosis in type 2 diabetes mellitus (T2DM). The in vivo T2DM model was established by raised with high-fat diet and intraperitoneally injection of streptozocin. Min6 cells were divided into four groups: negative control (NC), high glucose (HG), HG + irisin, and HG + irisin+3-MA. The cell viability was determined by CCK-8 assay. Dual-luciferase gene reporter assay was conducted to confirm the binding between miR-19b-3p and SOCS3. The expression level of FNDC5 and GSDMD was visualized using the immunofluorescence assay. The protein level of FNDC5, Beclin1, LC3II/I, NLRP3, cleaved-caspase-1, GSDMD-N, STAT3, p-STAT3, and SOCS3 was determined by Western blotting. The secretion of irisin, lactate dehydrogenase (LDH), and insulin was checked by ELISA. In vivo results showed that pathological changes in islet tissues with declined number of β cells, elevated FBG value, decreased FIN and HOMA-β value, elevated autophagy-associated proteins expressions, and activated NLRP3 signaling in T2DM mice, which were dramatically reversed by FNDC5 overexpression. Furthermore, the declined level of miR-19b-3p and p-STAT3, as well as the upregulation of SOCS3, was greatly rescued by FNDC5 overexpression. The in vitro data confirmed the binding site between SOCS3 and miR-19b-3p. SOCS3 was downregulated and p-STAT3 was upregulated in miR-19b-3p mimic-treated Min6 cells. In HG-stimulated Min6 cells, the elevated cell viability, increased production of insulin, decreased release of LDH, and inactivated NLRP3 signaling induced by irisin were abolished by miR-19b-3p inhibitor and STAT3 inhibitor. The increased level of autophagy-related proteins and activated SOCS3/STAT3 axis induced by irisin in HG-stimulated Min6 cells were abolished by miR-19b-3p inhibitor. The inhibitory effect of irisin against NLRP3 signaling in HG-stimulated Min6 cells was abrogated by 3-MA. In conclusion, irisin alleviated the pyroptosis of β cells in T2DM by inhibiting NLRP3 signaling through miR-19b-3p/SOCS3/STAT3 axis mediated autophagy.