Bile Acids in Polycystic Liver Diseases: Triggers of Disease Progression and Potential Solution for Treatment.

Polycystic liver diseases (PLDs) are a group of genetic hereditary cholangiopathies characterized by the development and progressive growth of cysts in the liver, which are the main cause of morbidity. Current therapies are based on surgical procedures and pharmacological strategies, which show short-term and modest beneficial effects. Therefore, the determination of the molecular mechanisms of pathogenesis appears to be crucial in order to find new potential targets for pharmacological therapy. Ductal plate malformation during embryogenesis and abnormal cystic cholangiocyte growth and secretion are some of the key mechanisms involved in the pathogenesis of PLDs. However, the discovery of the presence of bile acids in the fluid collected from human cysts and the intrahepatic accumulation of cytotoxic bile acids in an animal model of PLD (i.e. polycystic kidney (PCK) rat) suggest a potential role of impaired bile acid homeostasis in the pathogenesis of these diseases. On the other hand, ursodeoxycholic acid (UDCA) has emerged as a new potential therapeutic tool for PLDs by promoting the inhibition of cystic cholangiocyte growth in both PCK rats and highly symptomatic patients with autosomal dominant polycystic kidney disease (ADPKD: most common type of PLD), and improving symptoms. Chronic treatment with UDCA normalizes the decreased intracellular calcium levels in ADPKD human cholangiocytes in vitro, which results in the reduction of their baseline-stimulated proliferation. Moreover, UDCA decreases the liver concentration of cytotoxic bile acids in PCK rats and the bile acid-dependent enhanced proliferation of cystic cholangiocytes. Here, the role of bile acids in the pathogenesis of PLDs and the potential therapeutic value of UDCA for the treatment of these diseases are reviewed and future lines of investigation in this field are proposed.