AC inhibitors(University of Minnesota)

Adiponectin receptor (AdipoR) agonists protect against glomerular inflammation and injury in obesity-related glomerulopathy (ORG), but their molecular mechanisms remain unclear. Given the implication of the ceramide signaling pathway in the pathogenesis of ORG, the present study tested whether AdipoR agonists target acid ceramidase (AC) to inhibit NLRP3 inflammasome activation in podocytes, thereby blocking glomerular inflammation and injury during obesity. Confocal microscopy showed that adiponectin attenuated visfatin-induced NLRP3 inflammasome activation and IL-1β-containing multivesicular body (MVB) formation in podocytes. Nanoparticle tracking analysis revealed that adiponectin suppressed visfatin-induced extracellular vesicle release, an effect dependent on AC activity. Structured illumination microscopy demonstrated that visfatin reduced lysosome-MVB interaction in podocytes, which was restored by adiponectin via enhancement of TRPML1 channel-mediated Ca²⁺ release. The rescue of lysosome-MVB interaction and TRPML1 channel activity by adiponectin was mimicked by the AC enhancer but interfered with by the AC inhibitor. In vivo, high-fat diet (HFD) treatment induced NLRP3 inflammasome activation and T cell infiltration in glomeruli and increased urinary extracellular vesicle excretion in mice, which were exaggerated by podocyte-specific Smpd1 gene (gene code of acid sphingomyelinase) overexpression in Smpd1^trg/Podo^cre mice compared with WT/WT mice. AdipoRon, a synthetic AdipoR agonist, reduced HFD-induced glomerular inflammation in both WT/WT and Smpd1^trg/Podo^cre mice, but its effect was blocked by AC inhibition. Moreover, podocyte-specific Smpd1 gene overexpression aggravated HFD-induced podocyte injury, proteinuria, and glomerular sclerosis, which were mitigated by AdipoRon in an AC-dependent manner. Additionally, we found that the protective actions of AdipoRon may be mainly attributed to the activation of AdipoR1, but not AdipoR2. Taken together, our findings suggest that AC activation mediates the protective effects of AdipoR agonists against glomerular inflammation and injury in ORG, highlighting AC as a potential therapeutic target. SIGNIFICANCE STATEMENT: This study identifies acid ceramidase as a key mediator of adiponectin receptor agonist action in podocytes, linking its activation to suppression of NLRP3 inflammasome and extracellular vesicle release, and highlighting a novel therapeutic target in obesity-related kidney disease.