Human relevance of blocking the Rac1-TRPC5 pathway as a podocyte-protective strategy for progressive kidney diseases

Podocyte injury and the appearance of proteinuria are key features of progressive kidney diseases including focal segmental glomerulosclerosis (FSGS). Genetic deletion or selective inhibition of TRPC5 channels with small-molecule inhibitors protects podocytes in rodent models of disease; however, less is known about the human relevance and translatability of TRPC5 inhibition into effective drug development programs. Here, we investigate the effect of TRPC5 inhibition in puromycin aminonucleoside (PAN)-treated human iPSC-derived podocytes and kidney organoids.A single i.p. injection of PAN (50mg/kg) was given to wild-type Sprague-Dawley rats (Male, 4-5 weeks, Charles River). AC1903 was administered twice a day for 7 days after PAN injection. 24-hour urine albumin levels were measured on day 7. Human iPS cells were used to generate podocyte and kidney organoid. PAN treatment was used to induce human podocyte injury in these in vitro model systems. PAN treatment triggered the Rac1-TRPC5 injury pathway in human iPSC-derived podocyte cultures and kidney organoids. The TRPC5 inhibitor AC1903 reversed the effects of PAN-induced injury providing the first evidence for therapeutic applicability of TRPC5 inhibition to human podocytes in both 2D and 3D culture systems. Cross-validation in rats with PAN-induced nephrosis, an established model of podocyte injury and progressive kidney disease, confirmed that inhibition of TRPC5 by AC1903 was sufficient to protect podocyte cytoskeletal proteins and suppress proteinuria. Taken together, our results confirmed the relevance of the TRPC5-Rac1 pathway in human kidney tissue thus highlighting the potential of this therapeutic strategy for patients.