Biliary proteins and their redox status changes in gallstone patients

P>Background Proteins might act as pronucleating agents of cholesterol crystallization in bile. However, little is known about the redox status of biliary proteins in humans and their interaction with crystallization of biliary cholesterol. Materials and methods Gallbladder biles were obtained at cholecystectomy from 86 symptomatic patients with either cholesterol gallstones (32 multiple and 32 solitary stones) or pigment stones (n = 22), and studied for protein redox status [carbonyl and sulfhydryl (PSH) concentrations], total lipid and protein levels and cholesterol saturation index (CSI). First appearance of cholesterol crystals in ultrafiltered bile (crystal observation time, COT) was studied with polarizing light microscopy during 21 days. Results Patients with cholesterol stones had significantly shorter COT (3 days vs. > 21 days, P < 0 center dot 05), higher CSI (149 +/- 10% vs. 97 +/- 7%, P < 0 center dot 05) and higher total biliary proteins (1 center dot 96 +/- 0 center dot 1 mg mL-1 vs. 0 center dot 55 +/- 0 center dot 1 mg mL-1, P < 0 center dot 05) than patients with pigment stones. Patients with cholesterol stones had significantly lower (P < 0 center dot 05) level of protein sulfhydryl concentrations (18 +/- 4 nmol mg-1 protein vs. 49 +/- 16 nmol mg-1 protein), while total lipid and carbonyl proteins concentrations were similar between cholesterol and pigment stone patients. Crystallization probability was influenced by the number/type of gallstones (multiple > solitary > pigment stones, P = 0 center dot 009) and total protein concentration (high > low levels, P = 0 center dot 004). COT was negatively correlated with total protein content (r = -0 center dot 45, P = 0 center dot 03). Conclusions Biles with cholesterol stones show high CSI and total protein concentration, and rapid COT, which is even faster in patients with multiple stones and high protein concentration. Low PSH levels in cholesterol stone patients point to a biochemical shift, potentially able to affect cholesterol crystallization.