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NLRP3 Inflammasome Activation Contributes to Aldosterone-induced Podocyte Injury

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Renal Physiology

Published online on

Abstract

Aldosterone (Aldo) has been shown as an important contributor of podocyte injury. However, the underlying molecular mechanisms are still elusive. Recently, the pathogenic role of NLRP3 inflammasome in mediating renal tubular damage was identified while its role in podocyte injury still needs evidence. Thus the present study was undertaken to investigate the role of NLRP3 inflammasome in Aldo-induced podocyte damage. In vitro, exposure of podocytes to Aldo enhanced NLRP3, caspase-1 and IL-18 expressions in dose- and time-dependent manners, indicating an activation of NLRP3 inflammasome, which was significantly blocked by a mineralocorticoid receptor antagonist Eplerenone (EPL) or an antioxidant NAC. Silencing NLRP3 by a siRNA approach strikingly attenuated Aldo-induced podocyte apoptosis and nephrin protein downregulation in line with the blockade of caspase-1 and IL-18. In vivo, since day 5 of Aldo-infusion, NLRP3 inflammasome activation and podocyte injury evidenced by nephrin reduction occurred concurrently. More importantly, immunofluorescence analysis showed a significant induction of NLRP3 in podocytes of glomeruli following Aldo infusion. In the mice with NLRP3 gene deletion, Aldo-induced downregulation of nephrin and podocin, podocyte foot processes, and albuminuria was remarkably improved, indicating an amelioration of podocyte injury. Finally, we observed a striking induction of NLRP3 in glomeruli and renal tubules in line with an enhanced urinary IL-18 output in nephrotic syndrome patients with MCD or FSGS. Together, these results demonstrated an important role of NLRP3 inflammasome in mediating the podocyte injury induced by Aldo.