CHOLESTATIC LIVER-INJURY INCREASES CIRCULATING TNF-ALPHA AND IL-6 ANDMORTALITY AFTER ESCHERICHIA-COLI ENDOTOXEMIA

We employed a bile duct ligation (BDL) model of cholestatic liver inju ry to test the hypothesis that this form of preexisting hepatic dysfun ction alters the kinetics of circulating TNF-alpha and IL-6 after Esch erichia coli endotoxemia, thereby augmenting mortality and lung injury by a TNF-alpha:leukotriene (LT) axis of inflammation. Male rats were catheterized 13 d after BDL or sham surgery and studied while awake 18 to 24 h later. Cholestasis after BDL was confirmed by baseline serum bilirubin (BDL = 7.34 +/- 0.72 mg/dl, mean +/- SEM, n = 17 versus Sham = 0.25 +/- 0.07, n = 20; p < 0.005) and histopathology. Sham and BDL animals received E. coli lipopolysaccharide serotype O55:B5 (LPS, 5 mg /kg i.v.) or 0.9% NaCl (NS) ending at t = 0 and were monitored over 24 h for vital signs and hemodynamics. In parallel studies, lipoxygenase inhibition was performed using diethylcarbamazine or the 5-lipoxygena se activating-protein inhibitor MK-886. Blood was collected at baselin e and at t = 1.5, 3.5, and 24 h for formed elements and for serum endo toxin, TNF-alpha, IL-6, bilirubin, and alanine aminotransferase (ALT). Organs were evaluated at 24 h for histopathology, including neutrophi l (PMN) densities and wet/dry weight (W/D) ratios. Cholestasis reduced survival after otherwise nonlethal endotoxemia, with seven of 11 BDL + LPS rats dying within 24 h versus no deaths in BDL + NS (n = 6), Sha m + LPS (n = 14), or Sham + NS (n = 6) animals (p < 0.01). Despite equ ivalent serum endotoxin between groups, circulating TNF-alpha was 8-fo ld higher in BDL + LPS than in Sham + LPS rats at 1.5 and 3.5 h (p < 0 .001), whereas serum TNF-alpha did not differ between BDL + NS and Sha m + NS rats. IL-6 likewise was increased differentially by 1.5 h in BD L + LPS animals (11.98 +/- 2.42 ng/ml) versus Sham + LPS rats (3.05 +/ - 0.58 ng/ml, p < 0.05). Hypothermia, bradycardic hypotension, and leu kopenia were most severe and prolonged in BDL + LPS rats, which also h ad significantly higher ALT values, W/D ratios, and organ PMN counts. LT inhibition failed to reduce BDL-related differences in serum cytoki nes or survival after endotoxemia. Thus, cholestasis augments inflamma tory responses to gram-negative endotoxemia, sensitizing the host to e nhanced fluid flux in multiple organs and to mortality by a LT-indepen dent mechanism.