Ursodeoxycholic acid reduces lipid peroxidation and mucin secretagogue activity in gallbladder bile of patients with cholesterol gallstones.

BACKGROUND: Recently it has been postulated that gallbladder mucin hypersecretion observed in the pathogenesis of cholesterol gallstone disease may be induced by biliary lipid peroxidation. Ursodeoxycholic acid treatment reduces mucin concentration and the formation of cholesterol crystals in the gallbladder bile of patients with cholesterol gallstones and this effect might be mediated by a decrease of biliary lipid peroxidation. MATERIAL AND METHODS: In a double-blind, placebo-controlled trial patients with symptomatic cholesterol gallstones received either ursodeoxycholic acid (750 mg daily) (n = 10) or placebo (n = 12) 10-12 days prior to cholecystectomy. As a marker for lipid peroxidation malondialdehyde was measured in bile together with mucin concentration. In addition, the mucin secretagogue activity of the individual bile samples was assessed in cultured dog gallbladder epithelial cells. RESULTS: Ursodeoxycholic acid therapy resulted in a significant reduction of lipid peroxidation in bile as determined by the biliary malondialdehyde concentration (1.36 +/- 0.28 vs. 2.05 +/- 0.38 micromol L(-1); P < 0.005) and the malondialdehyde (micromol L(-1))/total bile acid (mmol L(-1)) ratio (0.02 +/- 0.005 vs. 0.06 +/- 0.01; P < 0.001). Furthermore, a decrease in mucin concentrations (0.7 +/- 0.3 vs. 1.3 +/- 0.5 mg mL(-1); P < 0.005) and of the mucin secretagogue activity of gallbladder bile (0.9 +/- 0.2 vs. 2.2 +/- 0.3 times control; P < 0.001) was observed. CONCLUSIONS: The reduction of lipid peroxidation and mucin secretagogue activity of gallbladder bile induced by ursodeoxycholic acid treatment may contribute to the beneficial effects of this drug on gallbladder bile composition and symptoms in cholesterol gallstone patients.

Lipid peroxidation and mucin secretagogue activity in bile of gallstone patients.

BACKGROUND: Chronic inflammation of the gallbladder wall and mucin hypersecretion are considered to be important factors in the pathogenesis of cholesterol gallstone disease. The aim of the study was to compare mucin concentration and mucin secretagogue activity with lipid peroxidation in gallbladder bile of patients with cholesterol or pigment stones. MATERIAL AND METHODS: We studied mucin concentration and, as a marker of lipid peroxidation, malondialdehyde concentration in 11 rapid (1 to 3 days) and eight non-nucleating (> 21 days) gallbladder biles of patients with cholesterol or pigment stones. Furthermore, the mucin secretagogue activity of rapid and non-nucleating gallbladder biles, as well as 1-5 micromol L(-1) malondialdehyde on cultured gallbladder epithelial cells, was determined. RESULTS: Our data show an increased malondialdehyde (7.2 +/- 1.8 vs. 3.8 +/- 0.5 micromol L(-1), P = 0.01) and mucin concentration (0.9 +/- 0.09 vs. 0.41 +/- 0.03 mg mL(-1), P = 0.01) and an increased mucin secretagogue activity (2.0 +/- 0.5 vs. 1.1 +/- 0.3 mucin secretion/control, P = 0.04) and cholesterol saturation index (1.2 +/- 0.1 vs. 08 +/- 0.1, P = 0.04) in rapid as compared to non-nucleating gallbladder biles. Malondialdehyde stimulated mucin secretion of cultured gallbladder epithelial cells in a concentration dependent manner. CONCLUSIONS: Our results support a promoting effect of gallbladder mucin hypersecretion by lipid peroxidation leading to rapid formation of cholesterol crystals in gallbladder bile. These findings suggest that besides hypersecretion of cholesterol in bile, chronic inflammation of the gallbladder wall is implicated in the pathogenesis of cholesterol gallstone disease.

Apolipoprotein E polymorphism and lithogenic factors in gallbladder bile.

BACKGROUND: Associations between the polymorphism of apolipoprotein E, which plays an important role in cholesterol metabolism and cholesterol gallstone formation, have been reported recently. Patients with the apo E4 isoform showed increased numbers and cholesterol contents of their stones, a higher frequency of cholesterol crystals in bile, increased susceptibility to gallstone fragmentation by extracorporeal shock-wave lithotripsy and an increase in recurrence rate after dissolution. A recent study, however, showed that fast cholesterol crystallization in bile is associated with multiple stones but not with apo E4. Therefore the mechanism for an increased risk of gallstone formation in patients with the apo E4 isoform still remains under debate. DESIGN: To clarify this issue we investigated 37 patients with gallstones (10 with the apo E4 allele and 27 without the allele). Gallbladder biles were examined for total cholesterol and other lipids, cholesterol saturation index, crystal observation time, crystal mass, total protein and mucin. Moreover, number of gallstones and cholesterol in gallstones was compared in both groups. RESULTS: The crystal observation time (2.5 vs. 2.0 days, median) and the cholesterol saturation index (1.34 +/- 0.45 vs. 1.43 +/- 0.74) did not differ significantly between the apo E4 and the non apo E4 group. Total biliary lipids (11.6 +/- 3.8 vs. 9.3 +/- 3.9 g 100 mL-1, P = 0.126) and total biliary cholesterol (21.8 +/- 9.7 vs. 15.7 +/- 7 mmol L-1, P = 0.067) tended to be elevated in the apo E4 group. Crystal mass (3.60 +/- 4.10 vs. 2.38 +/- 2.70 mmol L-1), biliary total protein (8.6 +/- 3.5 vs. 8.3 +/- 6.6 mg mL-1) and mucin (0.55 +/- 0.38 vs. 0.66 +/- 0.67 mg mL-1), number (solitary/multiple) of gallstones and cholesterol in gallstones were not different in both groups of patients. CONCLUSIONS: In comparison to the non apo E4 patients the apo E4 group showed a trend to elevated biliary cholesterol whereas crystal observation time, cholesterol saturation index, crystal mass, number of gallstones, cholesterol content of gallstones and total protein and mucin were not different. These findings do not suggest an association of the apo E isoform and the formation of cholesterol gallstones

Mucin and phospholipids determine viscosity of gallbladder bile in patients with gallstones.

AIM: An increased viscosity of gallbladder bile has been considered an important factor in the pathogenesis of gallstone disease. Besides lipids and proteins, mucin has been suggested to affect the viscosity of bile. To further clarify these issues we compared mucin, protein and the lipid componEnts of hepatic and gallbladder bile and its viscosity in patients with gallstones. METHODS: Viscosity of bile (mPa.s) was measured using rotation viscosimetry in regard to the non Newtonian property of bile at low shear rates. RESULTS: Biliary viscosity was markedly higher in gallbladder bile of patients with cholesterol (5.00 +/- 0.60 mPa.s, mean +/- SEM, r= 28) and mixed stones (3.50 +/- 0.68 mPa.s; r= 8) compared to hepatic bile (0.92 +/- 0.06 mPa.s, r= 6). A positive correlation between mucin and viscosity was found in gallbladder biles (r = 0.65; P < 0.001) but not in hepatic biles. The addition of physiologic and supraphysiologic amounts of mucin to gallbladder bile resulted in a dose dependent non linear increase of its viscosity. A positive correlation was determined between phospholipid concentration and viscosity (r = 0.34, P < 0.005) in gallbladder biles. However, no correlation was found between total protein or the other lipid concentrations and viscosity in both gallbladder and hepatic biles. CONCLUSION: The viscosity of gallbladder bile is markedly higher than that of hepatic bile in patients with gallstones. The concentration of mucin is the major determinant of biliary viscosity and may contribute by this mechanism to the role of mucin in the pathogenesis of gallstones.

Composition and immunofluorescence studies of biliary "sludge" in patients with cholesterol or mixed gallstones.

BACKGROUND/AIMS: Gallbladder bile from patients with cholesterol or mixed gallstones frequently contains biliary "sludge", a suspension of cholesterol monohydrate crystals and pigment granules embedded in mucin and proteins. The composition of biliary "sludge" and the preferential localization of mucin and proteins could be an indicator for its potential role in gallstone formation. METHODS: Ultracentrifugation (100000 g/l h) was used to precipitate "sludge" from bile, and the concentration difference of its main components between native bile and ultracentrifuged bile samples was calculated. After purification of the sediment, immunolocalization was performed for the detection of mucin, IgA, albumin, aminopeptidase, and anionic polypeptide fraction using polyclonal and monoclonal antibodies. RESULTS: The amount of sludge in gallbladder bile was 4.26 mg/ml-0.78 (mean+/-SEM) in patients with cholesterol and 2.51 mg/ml+/-0.39 in patients with mixed stones and cholesterol was the main component (48.9+/-4.6% and 44.4+/-7.1%). The sediment appeared as a mixture of vesicular aggregates and pigment particles which were linked by a gel matrix of mucin containing cholesterol crystals. While anionic polypeptide fraction and aminopeptidase were associated to pigments, IgA was uniformly spread in the crystalline parts of "core-like" structures, and albumin, when it was present, appeared as randomly located small spots. CONCLUSIONS: Our study demonstrates that the cholesterol content and the distribution pattern of mucin and different proteins is similar in the sediments of biliary "sludge" to that previously shown in cholesterol and mixed gallstones. This suggests that biliary "sludge" represents an early stage of gallstone formation in these patients.