Cholangiocyte death in ductopenic cholestatic cholangiopathies: Mechanistic basis and emerging therapeutic strategies

Abstract

Among hepatic diseases, cholestatic ductopenic cholangiopathies are poorly studied, and they are rarely given the importance they deserve, especially considering their high incidence in clinical practice. Although cholestatic ductopenic cholangiopathies have different etiologies and pathogenesis, all have the same target (the cholangiocyte) and similar mechanistic basis of cell death. Cholestatic cholangiopathies are characterized, predominantly, by obstructive or functional damage in the biliary epithelium, resulting in an imbalance between proliferation and cholangiocellular death; this leads to the progressive disappearance of bile ducts, as has been shown to occur in primary sclerosing cholangitis, primary biliary cholangitis, low-phospholipid-associated cholelithiasis syndrome, cystic fibrosis-related liver disease, and drug-induced ductopenia, among other biliary disorders. This review summarizes the features of the more common ductopenic syndromes and the cellular mechanisms involved in cholengiocellular death, with focus on the main forms of cholangiocyte death described so far, namely apoptosis, autophagy, necrosis, and necroptosis. It also emphasizes the importance to study in depth the molecular mechanisms of cholengiocyte death to make possible to counteract them with therapeutic purposes. These therapeutic strategies are limited in number and efficacy at present, and this is why it is important to find complementary, safe strategies to stimulate cholangiocellular proliferation in order favor bile duct replenishment as well. Successful in finding appropriate treatments would prevent the patient from having liver transplantation as the only therapeutic alternative.