TNF-alpha release in endotoxemia contributes to neutrophil-dependent pulmonary edema.
We examined whether the generation of tumor necrosis factor (TNF-alpha) after lipopolysaccharide (LPS) challenge contributes to increases in lung vascular permeability and water content. Guinea pig lungs perfused at constant flow with Ringer-albumin solution (0.5 g/100 ml) were challenged for 120 min with LPS (Escherichia coli; final concentration 33 ng/ml; n = 5). Lung effluent samples were assayed for TNF-alpha activity using the modified L-929 fibroblast cytolytic assay. TNF-alpha concentrations increased in a time-dependent manner with a peak value of 100 +/- 20 pg/ml noted 90-120 min after LPS. Human neutrophils [polymorphonuclear leukocytes (PMN; 2 x 10(7)] added to the perfusion solution after endotoxin challenge (n = 5) produced a threefold increase in lung tissue myeloperoxidase (MPO) activity over control values. PMN, added after LPS and activated using phorbol 12-myristate 13-acetate (PMA; 5 x 10(-9) M; n = 6), produced three- to sixfold increases in mean pulmonary arterial pressure (Ppa) and pulmonary capillary pressure (Pcap), wet weight-to-dry weight ratio (W/D), and the pulmonary capillary filtration coefficient (Kf,c) over control values (P < 0.05). Activation of PMN with PMA in non-LPS-challenged lungs produced only threefold increases in Ppa and Pcap and did not change W/D and Kf,c. Infusion of an anti-TNF-alpha antibody before the LPS challenge reduced by approximately 50% the increases in Ppa, Pcap, MPO content, Kf,c, and lung wet weight gain (P < 0.05). Therefore, endotoxin-induced TNF-alpha generation in lungs significantly contributes to pulmonary sequestration of PMN. Activation of the sequestered PMN increases pulmonary vascular permeability and tissue water content.
Horgan
M J
MJ
Department of Pediatrics, Albany Medical College of Union University, New York 12208.
Palace
G P
GP
Everitt
J E
JE
Malik
A B
AB
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004731:Endotoxins / Q000097:blood* / Q000502:physiology*; D004926:Escherichia coli; D006168:Guinea Pigs; D008070:Lipopolysaccharides / Q000494:pharmacology; D008168:Lung / Q000378:metabolism / Q000473:pathology; D009504:Neutrophils / Q000502:physiology*; D011654:Pulmonary Edema / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D011669:Pulmonary Wedge Pressure / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000502:physiology*
D004731:Endotoxins; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D013755:Tetradecanoylphorbol Acetate