Pathologic features of hepatolithiasis in Japan

A national survey of pathologic features of hepatolithiasis was conducted in Japan. The significance of hepatobiliary lesions in the pathogenesis of hepatolithiasis was evaluated in 31 autopsy livers and 242 surgically resected livers. Eighty-two percent shared several morphologic and clinical features, eg, the presence of multiple calcium bilirubinate or brown pigment stones within the intrahepatic duct and a characteristic hepatobiliary morphology. These cases were distributed throughout Japan without distinct geographic differences. The stones were found in the left and/or right hepatic duct and/or their tributaries. The ducts that contained stones had uneven dilatation of their lumena with focal stenosis. The walls of the involved ducts were thickened mainly by fibrosis. The hepatic parenchyma associated with stones within intrahepatic bile ducts showed mild to severe atrophy and fibrosis. Histologically, the ducts that contained stones showed fibrosis, proliferation of mucous and serous glands, and inflammatory cell infiltration in their walls and the periductal tissue. A large amount of mucus secreted from the affected ducts was seen within the biliary sludge and calcium bilirubinate stones were found in the involved ductal lumena. These findings suggest that the large amount of mucus and the formation of unevenly dilated ductal lumena may be important in the formation of intrahepatic calculi because these factors may favor nucleation and promote local bile stasis, thereby accentuating the ductal changes and stone formation (a vicious cycle).

Biliary proteins

The study of biliary proteins has grown enormously in the last 10 years. Although much has been recently learned about the nature, origin and hepatobiliary transport of these proteins, little is known of their function in bile or their effect on its physical state. This review will focus on description of the proteins and mechanisms by which they are secreted into bile.

Role of gallbladder mucin in pathophysiology of gallstones

A critical step in the formation of cholesterol gallstones in nucleation (i.e., the formation of cholesterol monohydrate crystals from supersaturated bile). The rate of nucleation of cholesterol depends upon a critical balance between pronucleating and antinucleating factors in bile. Mucin, a high molecular weight glycoprotein secreted by the gallbladder and biliary duct epithelium, is a pronucleating agent in experimental and human gallstone disease. Gallbladder mucin shares with other epithelial mucins the ability to bind lipids and bile pigment. The hydrophobic binding sites in the polypeptide core of mucin may provide a favorable environment for nucleation of cholesterol monohydrate from supersaturated bile. In nearly all animal models of cholelithiasis, mucin hypersecretion is prominent. The stimulus for gallbladder mucin hypersecretion appears to be a component of lithogenic bile. Prostaglandins regulate mucin release in gallbladder epithelium in vitro and probably in vivo. In the cholesterol-fed prairie dog, blockage of mucin release with aspirin inhibits gallstone formation. These findings suggest that inhibition of mucin release may prevent cholesterol stone formation during high-risk periods or after dissolution therapy with bile salts.