Increased biliary group II phospholipase A2 and altered gallbladder bile in patients with multiple cholesterol stones

Multiple cholesterol stones are associated with more biliary complications and show more rapid cholesterol nucleation than solitary stones. Group II phospholipase A2 (PLA2-II) may play a critical role in the process of mucosal inflammation, which in turn may produce pronucleating agents. PLA2-II concentrations in gallbladders and gallbladder bile from patients with different types of gallstone disease were assayed to correlate PLA2-II with alterations in biliary composition.

PLA2-II protein concentrations were assayed immunoradiometrically using monoclonal antibodies against human splenic PLA2-II.

Immunoreactive PLA2-II levels in gallbladder bile were significantly higher in patients with multiple cholesterol stones (68.2 +/- 6.3 ng/dL, mean +/- SEM; n = 24) than in those with solitary stones (24.9 +/- 2.8; n = 20; P < 0.01), those with multiple pigment stones (24.2 +/- 3.7; n = 18; P < 0.01), or control subjects (13.4 +/- 1.7; n = 19; P < 0.01). Increased biliary immunoreactive PLA2-II levels in multiple cholesterol stones were associated with a concomitant increase in the lysophosphatidylcholine to phosphatidylcholine ratio; free arachidonate, protein, and hexosamine concentrations; and gallbladder bile viscosity. The gallbladders showed an increased PLA2-II protein mass and steady-state messenger RNA levels, which was associated with increased prostaglandin E2 levels.

Increased biliary PLA2-II may be of pathogenetic importance in multiple cholesterol stones, probably through potentiating gallbladder mucosal inflammation with associated biliary alterations favoring cholesterol crystal formation.