Inhibition of RIP1-RIP3-mediated necroptosis attenuates renal fibrosis via Wnt3 alpha/beta-catenin/GSK-3 beta signaling in unilateral ureteral obstruction

Renal fibrosis represents the final common outcome of chronic kidney disease of virtually any etiology. However, the mechanism underlying the evolution of renal fibrosis remains to be addressed. This study sought to clarify whether RIP1-RIP3-mediated necroptosis is involved in renal fibrosis via Wnt3 alpha/beta-catenin/GSK-3 beta signaling in vitro and in a rat model of unilateral ureteral obstruction (UUO). Rats with UUO were administered RIP inhibitors (necrostatin-1 or GSK872) or beta-catenin/TCF inhibitor ICG-001 daily for 7 consecutive days. UUO caused significant renal tubular necrosis and overexpression of RIP1-RIP3-MLKL axis proteins, and was accompanied by activation of the NLRP3 inflammasome and renal fibrosis. Oxidative stress caused by UUO was closely associated with endoplasmic reticulum stress and mitochondrial dysfunction, which resulted in apoptotic cell death via Wnt3 alpha/beta-catenin/GSK-3 beta signaling. All of these effects were abolished by an RIP inhibitor (necrostatin-1 or GSK872) or ICG-001. In H2O2-treated HK-2 cells, both RIP inhibitor and ICG-001 decreased intracellular reactive oxygen species production and apoptotic cells, but increased cell viability. Activated Wnt3 alpha/beta-catenin/GSK-3 beta signaling was decreased by either RIP inhibitor or ICG-001. Our findings suggest that RIP1-RIP3-mediated necroptosis contributes to the development of renal fibrosis via Wnt3 alpha/beta-catenin/GSK-3 beta signaling in UUO and may be a therapeutic target for protection against renal scarring of other origins.