Lavage with leukotriene B4 induces lung generation of tumor necrosis factor-alpha that in turn mediates neutrophil diapedesis.
In experimental models of acute respiratory failure, leukotriene (LT) B4 is generated in the lungs, followed by a 2- to 3-hour delay before there is substantial neutrophil (PMN) accumulation and increased permeability. This study tests whether lavage with LTB4 induces tumor necrosis factor (TNF) synthesis by the lungs that in turn mediates PMN diapedesis. Anesthetized rats underwent lavage with 0.1 ml LTB4 (10(-6) mol/L) into a lung segment. This led to localized TNF synthesis measured in bronchoalveolar lavage fluid with peak concentrations of 580 pg/ml after 1 1/2 hours and 120 pg/ml after 3 hours. These values were higher than after lavage with 0.1 ml saline solution: 0.7 and 4.3 pg/ml, respectively (both p < 0.05). There was a delay before PMN accumulated in bronchoalveolar lavage fluid (x 10(4)). After 30 minutes, the numbers were 2.2 PMN/ml, whereas at 4 hours there was a rise to 40 PMN/ml and at 5 hours 60 PMN/ml, higher than after saline lavage (all p < 0.05). Pretreatment of rats by lavage into airways with actinomycin D, 12 ng in 0.1 ml, minimized LTB4-induced TNF synthesis after 1 1/2 and 3 hours (38 and 51 pg/ml), as well as the delayed diapedesis after 4 hours (12 PMN/ml) (all p < 0.05). Similarly, pretreatment of other rats by lavage with TNF-alpha antiserum (rabbit antimurine), but not normal serum, limited LTB4-induced diapedesis (13 PMN/ml) (p < 0.05). Interestingly, administration of the protein synthesis inhibitor actinomycin D by lavage 10 minutes after LTB4 did not prevent TNF generation after 1 1/2 or 3 hours (490 and 440 pg/ml). However, this agent did limit PMN diapedesis after 4 hours (14 PMN/ml) (p < 0.05), an event possibly caused by limiting later synthesis of endothelial adhesion proteins, a thesis consistent with the findings that pretreatment of rats by lavage with actinomycin D was without any effect on N-formyl-methionyl-phenylalanine (10(-8) mol/L)-induced diapedesis. This agent is known to induce PMN migration without need for synthesis of endothelial adhesion proteins. The data indicate that lavage with LTB4 induces local TNF-alpha generation that in turn mediates a delayed PMN diapedesis. This event is likely regulated by endothelial synthesis of adhesion proteins.
Department of Surgery, Brigham and Women's Hospital, Boston, MA 02115.
G
G
Goldman
R
R
Welbourn
L
L
Kobzik
C R
CR
Valeri
D
D
Shepro
H B
HB
Hechtman
D000818:Animals; D001681:Biological Assay; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D015815:Cell Adhesion Molecules / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology; D007975:Leukotriene B4 / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009504:Neutrophils / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D007507:Therapeutic Irrigation; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000502:physiology*
D015815:Cell Adhesion Molecules; D014409:Tumor Necrosis Factor-alpha; D007975:Leukotriene B4