Concanavalin A-binding cholesterol crystallization inhibiting and promoting activity in bile from patients with Crohnʹs disease compared to patients with ulcerative colitis

Background/Aims: Crohnʹs disease is a risk factor for gallstone formation. In contrast, patients with ulcerative colitis have an incidence of gallstone formation comparable to the general population. The reason for this difference is not known. The aim of this study was to elucidate the factors controlling cholesterol crystallization in gallbladder bile of Crohnʹs disease and ulcerative colitis patients. Methods: Gallbladder bile was obtained by aspiration during bowel resections (26 Crohnʹs disease patients, 20 ulcerative colitis patients). Biliary lipid composition, crystal detection time and the effect of extraction of the concanavalin A-binding fraction on crystal formation were determined. Results: Cholesterol crystals were present in seven of the 26 bile samples of Crohnʹs disease-patients and one of the 20 ulcerative colitis patients. Four of the bile samples of Crohnʹs disease patients were fast nucleating. None of the 20 ulcerative colitis patients had fast nucleating bile. Lipid composition, total lipid concentration and CSI were not significantly different between the two groups. In Crohnʹs disease patients extraction of concanavalin A-binding fraction decreased crystallization in 10 bile samples but accelerated crystallization in one bile sample. In eight bile samples from ulcerative colitis patients crystallization increased after concanavalin A-binding fraction extraction. Conclusions: Compared to ulcerative colitis patients, gallbladder bile of Crohnʹs disease patients showed increased cholesterol crystallization despite comparable lipid composition and cholesterol saturation index. This difference is caused by increased cholesterol crystallization-promoting activity. Bile from ulcerative colitis patients contains a Con A-binding factor which inhibits cholesterol crystallization.