The liver is the largest solid intra-abdominal organ and is involved in several homeastictic processes. One key role of the hepatocytes is the production of bile. Of all solutes in bile, bile salts arguably have the most profound impact on digestion and intestinal signalling. Lucas Maillette de Buy Wenniger throws light on the way that the biliary epithelium protects itself against toxic bile salts. His primary focus is also on immune-mediated disease of the biliary tree in general and immunoglobulin G4-related pancreaticobiliary disease in particular.