Endotoxin–Induced Mortality in Bile Duct—Ligated Rats After Administration of Reconstituted High–Density Lipoprotein

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Abstract
Cholestatic patients have substantial morbidity because of increased susceptibility to endotoxin (lipopolysaccharide [LPS]). Although reconstituted high–density lipoprotein (rHDL) can bind and neutralize LPS, cholestasis is associated with a near complete absence of HDL. Effects of rHDL infusion on the outcome of LPS–induced inflammatory responses in cholestatic rats were determined. Bile duct–ligated (BDL) and sham rats were treated with rHDL or saline and challenged with LPS. Distribution of cholesterol over the lipoprotein subclasses changed by ligation: levels in low–density lipoprotein (LDL) and very low–density lipoprotein (VLDL) were increased 2–fold and 5–fold, respectively, and were decreased in HDL 2–fold. rHDL treatment did not affect cholesterol distribution. LPS was mainly found in the HDL fraction, and ligation affected only levels of HDL–bound LPS (50% decrease; P < .05). Although rHDL infusion effectively normalized the lipoprotein–bound LPS distribution, it resulted in increased sensitivity (mortality: 88% in the ligation + rHDL group versus 44% in the ligation + saline group, 25% in the sham + saline group, and 0% in the sham + rHDL group, P < .05). In accordance with these results, plasma tumor necrosis factor (TNF) was significantly highest in the BDL + rHDL group at several hours after LPS challenge as well as the accumulation of LPS in the liver (P < .05). rHDL infusion leads to increased LPS–induced mortality in cholestatic rats. These results sharply contrast with the protective effects of rHDL suppletion in experimental endotoxemia in animals and human volunteers without biliary obstruction and suggest that there may be danger in administration of rHDL to cholestatic patients.