Actin cytoskeleton stabilization inhibits NLRP3 inflammasome activation and mitigates renal inflammation and fibrosis in obstructive nephropathy.

Abstract

Obstructive nephropathy is characterized by progressive renal inflammation and tubular injury, in which the NLRP3 inflammasome plays a pivotal role. However, the contribution of cytoskeletal dynamics to inflammasome activation remains poorly understood. In this study, we investigated whether stabilizing the actin cytoskeleton using Bis-T-23, a filamentous actin (F-actin) stabilizer, could alleviate renal injury by suppressing NLRP3 signaling. In a unilateral ureteral obstruction (UUO) mouse model, Bis-T-23 treatment significantly reduced tubular dilation, interstitial fibrosis, and immune cell infiltration. Transcriptomic profiling revealed marked downregulation of inflammation-related pathways, including TNF, IL-17, and NOD-like receptor signaling. At the molecular level, Bis-T-23 inhibited NLRP3 inflammasome activation, as evidenced by decreased levels of NLRP3, cleaved caspase-1, IL-1β, and IL-18 in both renal tissue and tubular epithelial cells. In vitro, TNFα/TGFβ1 co-stimulation induced a pro-fibrotic and pro-inflammatory phenotype in tubular cells, characterized by ZO-1 disruption, α-SMA upregulation, and enhanced NLRP3 expression, all of which were reversed by Bis-T-23. Furthermore, Bis-T-23 impaired ASC speck formation and disrupted NLRP3-ASC interactions, suggesting a direct blockade of inflammasome assembly. These findings identify cytoskeletal stabilization as a novel upstream mechanism for NLRP3 regulation and highlight Bis-T-23 as a potential therapeutic candidate for mitigating tubular inflammation in obstructive kidney disease.