2,8-Dihydroxyadenine disrupts epithelial integrity and alters kidney cell phenotype in vitro

Adenine phosphoribosyltransferase (APRT) deficiency is an autosomal recessive disorder that causes accumulation of 2,8-dihydroxyadenine (DHA) in the urinary tract, leading to kidney stones and chronic kidney disease (CKD). Progression to end-stage kidney disease can occur without timely treatment. The xanthine oxidoreductase inhibitors, allopurinol and febuxostat, block DHA generation and halt or delay stone formation and CKD progression. Some patients do not tolerate xanthine oxidoreductase inhibitor treatment, necessitating new therapeutic approaches. This study aimed to investigate how DHA influences structural and molecular changes in HK-2, HEK293, and MDCK kidney cells. DHA exposure reduced cell viability and impaired migration in all cell lines. Increased expression of the adhesion protein CD44 was observed adjacent to DHA crystals in HEK293 and HK-2 cells. Transepithelial electrical resistance measurements in MDCK cells indicated reduced epithelial integrity following DHA exposure. RNA sequencing of DHA-treated HK-2 cells revealed gene expression changes, with upregulation of TNF-α and mTORC1 signaling and downregulation of epithelial to mesenchymal transition and oxidative phosphorylation. Functional enrichment analysis highlighted pathways related to cell cycle regulation, inflammation, and metabolic processes. These findings show that dose-dependent DHA toxicity interrupts cell migration and epithelial integrity. CD44 may contribute to crystal adhesion, and thus, represents a potential therapeutic target in DHA crystal nephropathy. KEY MESSAGES: DHA reduces kidney cell viability and migration in a dose-dependent manner. DHA disrupts epithelial integrity in MDCK cells, lowering TEER values. CD44 expression increases adjacent to DHA crystals with increased DHA concentration. RNA sequencing shows that DHA upregulates TNF-α, mTORC1, and stress pathways. DHA alters gene expression, affecting inflammation, metabolism, and EMT.