Gut Microbiota-Isoallolithocholic Acid Crosstalk Promotes Calcium Oxalate Kidney Stone Formation via PARP1-Mediated Parthanatos.

Bile acids have been implicated in calcium oxalate (CaOx) nephrolithiasis. Here, we employ multi-omics approaches to identify isoallolithocholic acid (isoalloLCA) as the key bile acid elevated in the feces, serum, kidney, and urine of CaOx rats, confirmed by spatial metabolomics. 16S sequencing and metagenomic analyses indicate that elevated isoalloLCA levels in CaOx rats or individuals are likely of microbial origin. Mechanistically, isoalloLCA binds to PARP1 via specific molecular interactions validated by surface plasmon resonance and cellular thermal shift assays. Knockdown of PARP1 by adeno-associated virus microinjection or pharmacological inhibition with PARP1 inhibitor AZD5305 significantly attenuates isoalloLCA-mediated crystal deposition, renal tubular injury, and mitochondrial functional impairment in both the CaOx rat and mouse models. Furthermore, the antibiotic-mediated depletion of the gut microbiota in mice markedly reduced isoalloLCA levels, whereas fecal microbiota transplantationut contributes to isoalloLCA-mediated CaOx stone formation, demonstrating a causal link between gut microbiota and isoalloLCA. In vitro, isoalloLCA promoted oxalate-induced renal tubular epithelial cell injury and parthanatos via targeting PARP1, including DNA damage, excessive PARP1 activation, PAR accumulation, mitochondrial damage, nuclear translocation of AIF and MIF. These findings establish the microbiota-isoalloLCA-PARP1-parthanatos axis in CaOx nephrolithiasis and identify PARP1 as a promising therapeutic target for kidney stone management.