Quantification of cholesterol nucleation promoting activity in human gallbladder bile

Area of Science:

• Biochemistry
• Gastroenterology
• Pathophysiology

Background:

• Cholesterol gallstone formation is a complex process.
• Bile composition, particularly cholesterol saturation and nucleation activity, plays a critical role.
• Existing methods for assessing gallstone risk factors are limited.

Purpose of the Study:

• To develop and validate a simple method for quantifying cholesterol nucleation promoting activity in bile.
• To assess the utility of this method in differentiating patients with and without cholesterol gallstones.
• To evaluate the role of nucleation promoting activity in the pathogenesis of cholesterol gallstones.

Main Methods:

• A novel assay was developed using serial dilutions of gallbladder bile mixed with supersaturated model bile.
• Nucleation time (NT) was determined for each mixture.
• The greatest dilution significantly shortening NT was defined as the nucleation promoting activity titre (NPAT).
• NPAT was measured in bile samples from patients with cholesterol gallstones and control subjects.

Main Results:

• The developed method accurately quantifies nucleation promoting activity, independent of original lipid content.
• All tested bile samples exhibited nucleation promoting activity.
• Patients with cholesterol gallstones showed significantly elevated NPAT compared to controls (p = 0.01).

Conclusions:

• The nucleation promoting activity titre (NPAT) is a valuable metric for assessing gallstone risk.
• Elevated NPAT, alongside cholesterol saturation index, is crucial in cholesterol gallstone disease pathogenesis.
• This assay can identify individuals with normal cholesterol saturation but high NPAT, who are at risk for gallstone formation.