Vallon, Volker

Renal water reabsorption is classically regulated by vasopressin V2 receptor (V2R) signaling through cyclic AMP and protein kinase A, driving apical accumulation of aquaporin-2 (AQP2). However, collecting duct water handling is also modulated by vasopressin-independent mechanisms. Here, we examined intracellular soluble urate as a vasopressin-independent regulator of AQP2 trafficking. Intracellular urate accumulation in collecting duct cells was mediated by enhanced apical urate uptake via GLUT9b and reduced apical urate efflux through ABCG2, triggering phosphodiesterase-4 activation, reduced cAMP, and downstream AMP-activated protein kinase (AMPK) activation. The resulting AQP2 accumulation at the apical membrane was independent of V2R signaling, required ongoing endocytosis, and was associated with features of postendocytic apical trafficking of internalized AQP2. In vivo ABCG2 inhibition with probenecid increased apical AQP2 abundance and markedly attenuated tolvaptan-induced polyuria in both wild-type and Pkd1 RC/RC autosomal dominant polycystic kidney disease (ADPKD) mice in a uricase-independent manner while preserving tolvaptan’s ADPKD-modifying efficacy. In a phase II trial with tolvaptan-treated patients with ADPKD, probenecid reduced urine volume and nocturia frequency. Together, these findings support a vasopressin-independent urate/AMPK/AQP2 pathway that regulates renal water handling and, in a preclinical ADPKD model, can uncouple cyst growth attenuation from the dose-limiting aquaretic effects of V2R antagonism.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disorder and a leading cause of kidney failure worldwide. Disease progression is driven by cyst expansion, tubular injury, and maladaptive metabolic and hemodynamic changes. Tolvaptan remains the only US Food and Drug Administration–approved disease-modifying therapy, however its tolerability and safety profile highlight the need for additional strategies. Sodium-glucose cotransporter 2 inhibitors (SGLT2is), initially developed for glycemic control, have demonstrated robust kidney-protective and cardioprotective effects across diverse patient populations, including those without diabetes. By lowering intraglomerular pressure, metabolic reprogramming, and attenuating hypoxic microenvironment and inflammation, SGLT2is target mechanisms that are relevant to ADPKD. However, concerns that SGLT2i may provoke osmotic diuresis and activate vasopressin led to systematic exclusion of patients with ADPKD from pivotal outcome trials. The 2025 Kidney Disease Improving Global Outcomes ADPKD guidelines explicitly advise against the use of SGLT2i for slowing kidney function decline in ADPKD. In this review, we examine mechanistic intersections between SGLT2i and ADPKD pathophysiology, summarize available preclinical and early clinical data, and discuss ongoing large trials designed to address safety and efficacy of SGLT2i in patients with ADPKD. We also highlight the importance of genetic heterogeneity, as most ongoing trials are enriched for rapid progressors carrying PKD1 or PKD2 pathogenic variants, while other genotypes such as DNAJB11 , ALG8 , and ALG9 , often associated with greater interstitial fibrosis, are underrepresented. Substratification of patients by genotype, risk of progression, and comorbidities will be essential to guide precision application of SGLT2i. Whether SGLT2i can ultimately be positioned as an adjunctive or standalone therapy for ADPKD remains unresolved.