EXTRACELLULAR-MATRIX PROTEINS IN HUMAN BILE AND GALLSTONES

Objective: To investigate the presence of extracellular matrix (ECM) p roteins in human bile and gallstones and to determine whether they pla y a role in gallstone formation. Methods: ECM components [procollagen- lll-peptide (P-III-P), laminin, and hyaluronic acid] in bile from pati ents with (n=22) and without (n=6) gallstone disease were investigated by immunoassay. Bile, gallstones, and serum were assayed for extracel lular matrix components in an additional 19 patients with gallstone di sease and gallstones were analysed in a third set of 26 patients. The expression of hyaluronic acid synthetase in bile duct and gall bladder epithelia was investigated by immunocytochemistry. Results: Hyaluroni c acid levels were significantly elevated in hepatic and gall bladder bile, but not in the serum of patients with compared with those withou t gallstone disease (137 versus 81 mu g/l, respectively; P<0.05). No d ifferences were found between hepatic and gall bladder bile. Procollag en-III-peptide and laminin were detected in the hepatic bile of patien ts in both groups. Laminin levels were higher in gall bladder bile tha n in serum in all patients and measurable amounts of hyaluronic acid w ere found in gallstones. The amount of hyaluronic acid was inversely c orrelated to the volume of the gallstone, i.e., the smallest gallstone s contained the highest levels of hyaluronic acid. No procollagen-III- peptide or laminin was found in the gallstones. Immunocytochemistry of the epithelial cells of bile duct and gall bladder mucosa stained str ongly for hyaluronic acid synthetase. Conclusions: Hyaluronic acid as a progenitor of ECM can be detected in bile and is significantly eleva ted in patients with gallstone disease. Small gallstones contain more hyaluronic acid than large stones, suggesting that hyaluronic acid may play a role in gallstone formation, particularly since it is produced by the epithelial lining of bile ducts and is found in gall bladder m ucosa.