iPSC-based drug discovery identified the Hippo signaling pathway as a therapeutic target in the fibrosis of NPHP1-deficient nephronophthisis.

BACKGROUND: Nephronophthisis (NPH) is an autosomal recessive kidney disease, and NPHP1 is the most frequently affected gene. Tubulointerstitial fibrosis is the major phenotype of NPHP1-deficient NPH. The pathophysiology of NPHP1-deficient NPH is unclear because models representing the disease pathophysiology are lacking. Herein, we aimed to create a novel pathological model of NPH using 3D kidney organoids derived from human-induced pluripotent stem cells (iPSCs) and elucidated the pathophysiology while searching for therapeutic candidates. METHODS: NPHP1-deficient kidney organoids were generated from iPSCs. Fibrosis was induced by treatment with IL-1β. The effects of the Hippo signaling pathway inhibitors as therapeutic candidates were assessed. Fibrotic status was evaluated using immunofluorescence and quantitative PCR. RESULTS: NPHP1(-/-) kidney organoids were generated from iPSCs. Fibrosis induction with IL-1β considerably increased the expression of fibronectin and transcription of fibrosis-related genes in NPHP1(-/-) organoids. Long-term culture of NPHP1(-/-) organoids induced substantial fibrogenesis compared with wild-type organoids. Co-immunoprecipitation analysis revealed the binding of NPHP1 to LATS1/2-the main constituents of the Hippo pathway. IL-1β administration increased the expression of the key Hippo pathway genes in NPHP1(-/-) organoids. By contrast, the Hippo pathway inhibitors ameliorated IL-1β-induced fibrogenesis in NPHP1(-/-) organoids. Because one of the inhibitors, verteporfin, is in clinical use, its practical availability is expected from a drug-repositioning perspective. CONCLUSIONS: Hippo signaling pathway is involved in the fibrotic changes associated with NPHP1-deficient NPH and the Hippo pathway inhibitors could be therapeutic agents. CLINICAL TRIAL NUMBER: Not applicable.