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Bile salt-induced cholesterol crystal formation from model bile vesicles: a time course study
B J van de Heijning1, M F Stolk, K J van Erpecum
1Department of Gastroenterology, Utrecht University Hospital, The Netherlands.
Journal of Lipid Research
|June 1, 1994
Summary
Cholesterol crystal formation in gallstones is influenced by bile salt properties. Hydrophobic bile salts accelerate cholesterol nucleation and precipitation from vesicles, highlighting the dynamic nature of gallstone pathogenesis.
Area of Science:
- Biochemistry
- Gastroenterology
- Lipid Metabolism
Background:
- Cholesterol crystal precipitation from vesicles is a key step in cholesterol gallstone formation.
- The kinetics and mechanisms of cholesterol crystallization remain poorly understood.
Purpose of the Study:
- To investigate the time course of cholesterol crystal precipitation and lipid exchange in a model bile system.
- To determine the influence of different bile salts on cholesterol crystallization kinetics.
Main Methods:
- Model bile vesicles were incubated with various bile salts (deoxycholate, chenodeoxycholate, cholate, ursodeoxycholate).
- Vesicle integrity was assessed using carboxyfluorescein leakage and optical absorbance.
- Cholesterol nucleation and lipid distribution were quantified over time using ultracentrifugation.
Main Results:
- Hydrophobic bile salts (deoxycholate, chenodeoxycholate) induced rapid nucleation and cholesterol precipitation.
- Vesicle cholesterol/phospholipid ratio transiently increased with mixed micelle formation, then decreased as crystals precipitated.
- The hydrophilic bile salt (ursodeoxycholate) showed minimal micellization and no nucleation.
Conclusions:
- Bile salt hydrophobicity and micelle-forming capacity are critical determinants of cholesterol crystallization kinetics.
- The dynamic changes in lipid distribution over time play a pivotal role in cholesterol crystal formation.
- These findings provide insights into the pathogenesis of cholesterol gallstones.