GSE202676
Bulk RNA-seq in cholangiocytes from mouse model of primary biliary cholangitis
Background & Aims: Late-stage primary biliary cholangitis (PBC) is defined by bile duct loss, ductular reaction, peribiliary inflammation and fibrosis. Loss of anion exchanger 2 (AE2), the 'bicarbonate umbrella' and ductulo-canalicular junctions (DCJ) are hypothesized to promote PBC progression. The secretin (Sct)/secretin receptor (SR) axis controls cystic fibrosis transmembrane receptor (CFTR) activation and AE2 opening, and controls choleresis. We aimed to define the impact of Sct/SR signaling on biliary secretory processes and subsequent injury in late-stage PBC mouse model and human samples. Methods: Female and male wild-type (WT) and dominant-negative transforming growth factor beta receptor II (dnTGFßRII, late-stage PBC model) at 32 wks of age were treated with Sct for 1 wk or 8 wks. Pathways mediated by Sct were identified by RNA-seq in isolated cholangiocytes. Sct/SR/CFTR/AE2 expression and MUC1 levels were evaluated in human control and late-stage PBC. Results: Biliary Sct, SR, CFTR and AE2 expression is reduced in late-stage PBC mouse models and human samples. Sct treatment decreased bile duct loss, ductular reaction, inflammation and fibrosis in late-stage PBC models, as well as hepatic bile acid release and DCJ formation. RNA-seq identified that Sct promoted mature epithelial cell marker expression, specifically anterior grade 2 (Agr2, expressed only in cholangiocytes). Late-stage PBC models and human samples had reduced biliary MUC1, which was enhanced with Sct treatment. Conclusion: Loss of the Sct/SR pathway in late-stage PBC results in a faulty 'bicarbonate umbrella' and reduced Agr2 and mucin production. Sct restores cholangiocyte secretory processes and DCJ formation through enhanced mature cholangiocyte phenotypes and healthy bile duct growth. The Sct/SR axis may be a therapeutic target for late-stage PBC patients. Overall design: intrahepatic cholangiocytes analyzed from WT, WT+secretin 8 wk, PBC model (dnTGFBRII), and PBC model + secretin 8 wk. WT cholangiocytes are the control sample. We analyzed male and female samples separately. 6-8 mice per treatment group were pooled to extract cholangiocytes, and total RNA from this pooled population of cholangiocytes was sequenced in triplicate at GeneWiz using an Illumina platform.