Mitochondrial DNA released by Biliary Epithelial Cells enhances inflammation in Biliary Atresia through the cGAS-STING-NF-κB pathway.

BACKGROUND & AIMS: Biliary atresia (BA), the leading cause of infant cholangiopathy, features progressive inflammation and fibrosis with undefined pathogenesis. In BA, biliary epithelial cells (BECs) act as both targets and drivers of hepatic inflammation. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, a cytosolic DNA-sensing system linking cellular stress to inflammation, may contribute to BA pathogenesis. This study investigated whether cGAS-STING activation in BECs promotes disease progression. METHODS: cGAS-STING expression and localization were assessed in BA and control livers by qRT-PCR, Western blotting, immunohistochemistry and immunofluorescence. Oxidative injury in human intrahepatic BECs (HIBECs) was modeled with H2O2. Mitochondrial DNA (mtDNA) depletion with ethidium bromide (EtBr), cGAS/STING inhibitors (RU.521, H151), and the STING agonist (ADU-S100) were used to investigate mechanisms. Coenzyme Q10 (CoQ10) was evaluated in vitro using biliary organoids and in vivo in a Rhesus rotavirus (RRV)-induced neonatal mouse model of BA. RESULTS: In BA livers, cGAS and STING were unregulated and activated in CK19+ BECs, accompanied by NF-κB activation without detectable IRF3 phosphorylation. HIBECs exposed to H2O2 showed mtDNA release, cGAMP accumulation, STING activation, and p65 phosphorylation, selectively increasing CXCL10 and IL-32, which were markedly attenuated by mtDNA depletion or cGAS/STING inhibition. CoQ10 suppressed the mtDNA-STING-NF-κB axis in vitro, and ameliorated liver injury while improving survival in vivo. CONCLUSIONS: mtDNA leakage activates the cGAS-STING-NF-κB pathway in BECs, driving a CXCL10/IL-32-dominant inflammatory response. CoQ10 mitigates this process and injury, supporting cGAS-STING modulation and mitochondrial stabilization as promising therapeutic strategies for BA.