P-STAT3-dependent SPP1 transcription in cholangiocytes drives hepatic stellate cells activation in congenital hepatic fibrosis.

Congenital hepatic fibrosis (CHF) is a rare inherited liver disorder caused by mutations in the polycystic kidney and hepatic disease-1 gene (PKHD1), leading to progressive hepatic fibrosis. In our study, single-cell RNA sequencing of a CHF patient carrying compound heterozygous PKHD1 mutations revealed markedly intercellular communication between cholangiocytes and hepatic stellate cells (HSCs) via the secreted phosphoprotein 1 (SPP1)-integrin α8β1 axis. The CRISPR-Cas9-generated Pkhd1 knockout mouse model (Pkhd1del3-4/del3-4) was generated and recapitulated bile duct hyperplasia and fibrosis. We validated that PKHD1 deficiency led to progressive upregulation of SPP1 in cholangiocytes. Co-culture experiments demonstrated that PKHD1-deficient cholangiocytes secrete OPN, activating PI3K/Akt signaling in HSCs and promoting their activation. Mechanistically, phosphorylated STAT3 (p-STAT3) was identified as a direct transcriptional activator of SPP1. Importantly, cholangiocyte-specific knockdown of Spp1 via AAV8 significantly attenuated hepatic fibrosis in vivo. Collectively, our findings demonstrate that reduced PKHD1 expression in cholangiocytes promotes hepatic fibrosis by activating the p-STAT3-SPP1 pathway, and targeting this axis may offer a potential therapeutic strategy.