Mitochondrial enzyme HIBADH protects against calcium oxalate nephrolithiasis by modulating oxidative stress and...

Calcium oxalate (CaOx) nephrolithiasis, as one of the most common types of kidney stones, poses a major threat to human health. This study aimed to investigate the role of 3-hydroxyisobutyrate dehydrogenase (HIBADH) in the pathogenesis of CaOx nephrolithiasis. CaOx nephrolithiasis models were established in rats via 1 % ethylene glycol and 2 % ammonium chloride induction and in HK-2 cells using calcium oxalate monohydrate (COM, 100 μg/mL). HIBADH expression was modulated through plasmid transfection and siRNA knockdown in vitro, and AAV2/9-mediated gene transfer in vivo. Multiple parameters were assessed, including cell crystal adhesion, apoptosis, cell cycle distribution, oxidative stress markers (SOD, MDA, MitoSOX fluorescence), and mitochondrial function (ATP level, mitochondrial membrane potential), using various techniques such as crystal adhesion assay, flow cytometry, western blot, qRT-PCR, and fluorescence microscopy. Kidney tissues were analyzed through H&E, Von Kossa, and PAS staining. Results demonstrated that HIBADH expression was significantly downregulated in CaOx nephrolithiasis rats and COM-treated HK-2 cells. In vitro, HIBADH overexpression reduced cell crystal adhesion and apoptosis, promoted cell cycle progression, mitigated mitochondria-involved cellular oxidative stress, and enhanced mitochondrial function in COM-induced HK-2 cells. In vivo, AAV2/9-mediated HIBADH overexpression attenuated crystal deposits and tubular injury, reduced apoptosis, and mitigated mitochondria-involved cellular oxidative stress in kidney tissues. The mitochondria-targeted antioxidant Mito-TEMPO counteracted the effects of HIBADH silencing, highlighting the role of mitochondrial function in HIBADH's protective mechanism. This study identifies HIBADH as a critical regulator in CaOx nephrolithiasis, exerting its protective effects through modulation of mitochondrial function and mitochondria-involved cellular oxidative stress, cell crystal adhesion, and apoptosis. Our findings elucidate the link between mitochondrial metabolism and kidney stone formation, positioning HIBADH as a key protective factor and a promising candidate with therapeutic potential for CaOx nephrolithiasis.