Hepatic Stem/Progenitor Cell Activation Differs between Primary Sclerosing and Primary Biliary Cholangitis.

Primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) are human primary cholangiopathies characterized by the damage of mature cholangiocytes and by the appearance of ductular reaction (DR) as the results of hepatic progenitor cell activation. This study evaluated the differences in progenitor cell niche activation between these two cholangiopathies. Liver tissue was obtained from healthy liver donors (n = 5) and from patients with PSC (n = 20) or PBC (n = 20). DR, progenitor cell phenotype, and signaling pathways were investigated by IHC analysis and immunofluorescence. Our results indicated that DR was more extended, appeared earlier, and had a higher proliferation index in PBC compared with PSC. In PBC, DR was strongly correlated with clinical prognostic scores. A higher percentage of sex determining region Y-box (SOX)9+ and cytokeratin 19+ cells but fewer features of hepatocyte fate characterized progenitor cell activation in PBC versus PSC. Lower levels of laminin and neurogenic locus notch homolog protein 1 but higher expression of wingless-related integration site (WNT) family pathway components characterize progenitor cell niche in PSC compared with PBC. In conclusion, progenitor cell activation differs between PSC and PBC and is characterized by a divergent fate commitment and different signaling pathway predominance. In PBC, DR represents a relevant histologic prognostic marker.