VX‐765 ameliorates renal injury and fibrosis in diabetes by regulating caspase‐1‐mediated pyroptosis and inflammation

INTRODUCTION: As a lytic inflammatory cell death, pyroptosis has been recently described but has not been unequivocally elucidated in diabetic nephropathy (DN). VX‐765 is a safe and effective inhibitor of caspase‐1, that was well tolerated in a phase II clinical trial in patients with epilepsy, but its application in DN is still undefined. MATERIALS AND METHODS: Immunoblot, co‐immunoprecipitation, confocal microscope and flow cytometry were used to analyze the effects of glucose on pyroptosis in renal tubular epithelia (HK‐2). In vitro, selective caspase‐1 inhibitors VX‐765 and Z‐YVAD‐FMK were administered. Pyroptosis and fibrogenesis were determined by immunoblot, ELISA, cytotoxicity assay and flow cytometry. In vivo, diabetic mice were administered with 100 mg/kg VX‐765. Renal function, pathological changes, and the expressions of NLRC4, GSDMD, IL‐1β, collagen I, fibronectin and CD45 in renal cortex were evaluated. RESULTS: We identified NLRC4 as a sensor for caspase‐1 activation. Moreover, we provided morphological and molecular evidence for pyroptosis in glucose‐stressed tubular cells, including ballooned cell membrane, caspase‐1 immunoreactivity, GSDMD cleavage, and the release of inflammatory cytokine and cellular contents. All these effects were prevented by treatment with VX‐765 or Z‐YVAD‐FMK, confirming that caspase‐1 effectively regulates the occurrence of pyroptosis in HK‐2 cells. In vivo, treatment of diabetic animals with VX‐765 ameliorated renal function, suppressed inflammatory cell infiltration and pyroptosis‐associated protein expression, and mitigated tubulointerstitial fibrosis. CONCLUSIONS: This work revealed that caspase‐1‐mediated pyroptosis drives renal inflammation and fibrosis in diabetes. Our results are the first demonstration of VX‐765 representing a promising therapeutic opportunity for alleviating the progression of DN.