Human biliary beta-glucuronidase activity before and after relief of bile duct obstruction: is it the major role in the formation of pigment gallstones?

BACKGROUND AND AIMS: The bacterial beta-glucuronidase (bBG) can deconjugate conjugated bilirubin to form calcium bilirubinate gallstone. Yet, the role of the human biliary beta-glucuronidase (hBG) in the pathogenesis of pigment gallstone formation still remains unsolved.

METHODS: Hepatic bile was collected from bile-duct-obstructed patients on the day of, and 3 days after, biliary drainage. Patients were divided into pigment-stone (PS) group (n = 34) and stone-free (SF) group (n = 29). All patients of the PS group had the complication of cholangitis. The concentrations of bile contents and the activities of bBG and hBG were measured.

RESULTS: The activities of hBG and bBG in bile obtained on the day of biliary drainage were higher in the PS group than in the SF group (activities corrected for bile salt concentration: hBG 128.7 +/- 340.0 vs 13.1 +/- 25.0 U/mmol; bBG 12.5 +/- 22.2 vs 4.6 +/- 7.7 U/mmol, P < 0.05). This difference disappeared after biliary drainage. The changes of enzyme activity in the bile of the SF group were unremarkable before and after biliary drainage. The mean concentrations of bile pigments and free calcium in the PS group were lower than those in the SF group.

CONCLUSIONS: An increase in the activity of hBG may be a secondary response, developed after bile duct inflammation because it was elevated only when the bile duct obstruction was associated with infection.