Liver-lung interactions during E. coli endotoxemia. TNF-alpha:leukotriene axis.

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Abstract
The liver modulates host responses to endotoxemia by production and clearance of tumor necrosis factor alpha (TNF-alpha) and eicosanoid lipoxygenation products. Reductions in liver blood flow (QL) are common during endotoxemia, but it is unknown whether the kinetics of TNF-alpha and leukotrienes (LTs) are thereby altered to amplify lung inflammation. To test this hypothesis, reductions in QL were modeled by an end-to-side portacaval shunt (PCS) in Sprague-Dawley rats. Conscious animals received 2.5 mg/kg of intravenous E. coli lipopolysaccharide (LPS) serotype 055:B5 (PCS + LPS; n = 17) or saline (n = 5). Responses were compared with those in sham-operated rats (sham + LPS; n = 13) and NSS-challenged control rats (n = 5). Cardiopulmonary changes, serum TNF-alpha, and formed elements were determined at t = 0, 1.5, 3.5, and 24 h, when organ wet/dry ratios (W/D) were measured with TNF-alpha, LTB4, and polymorphonuclear neutrophils (PMN) in bronchoalveolar lavage fluid (BALF). In PCS + LPS rats, mortality was 59% and serum TNF-alpha peaked at 1.5 h (2,784 +/- 658 U/ml, mean +/- SEM) coincident with the onset of hypotension. Despite equivalent endotoxemia and liver- and lung-associated TNF-alpha in sham + LPS rats at 1.5 h, peak serum TNF-alpha was 38% less and mortality was 15% (p < 0.05). Cardiac, hepatic, and cecal W/D were likewise increased in PCS + LPS versus sham + LPS rats, as were BALF PMNs (p < 0.05). In parallel studies, the disappearance kinetics of infused rTNF-alpha were not altered in nonendotoxemic PCS animals, implicating enhanced lung uptake of LPS and systemic export of TNF-alpha in PCS + LPS rats.(ABSTRACT TRUNCATED AT 250 WORDS)

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