Elevated Epithelial Splicing Regulatory Protein 1 Expression in Biliary Atresia Indicates Its Potential as a Molecular Marker.

Cholangiopathies encompass a wide range of chronic liver diseases that target biliary epithelial cells, leading to significant morbidity and mortality due to their progressive nature, limited treatment options, and complex clinical management. Currently, clinically validated biomarkers capable of distinguishing obstructive cholangiopathies, such as biliary atresia (BA), from other cholangiopathies are lacking, hindering timely intervention. RNA-binding proteins (RBPs) have been increasingly linked to human diseases but their roles in cholangiopathies remain underexplored. We assessed the expression of the RBP epithelial splicing regulatory protein 1 (ESRP1) in murine models of cholangiopathies and in the human system. Our findings demonstrate that ESRP1 is highly and specifically expressed in cholestatic liver injury models, including bile duct-ligated, diethoxycarboncyl-1,4-dihydrocollidine-treated, and Mdr2-/- mice when compared with other liver injury models. Importantly, ESRP1 is markedly elevated in the livers of patients with BA and cystic fibrosis-related liver disease, localizing to cholangiocytes and peri-biliary hepatic cells, but is minimal in primary sclerosing cholangitis and primary biliary cholangitis. Moreover, patient-derived BA organoids and biliatresone-treated healthy organoids also display ESRP1 expression. Bioinformatics analysis further implicates ESRP1 in key cholangiopathy-associated pathways, warranting deeper mechanistic investigation. Thus, ESRP1 holds potential as a molecular marker for obstructive cholangiopathies, warranting further mechanistic studies.