leukotriene-b4 and Pleural-Effusion

Leukotriene B(4) (LTB(4)) plays a crucial role in the recruitment of neutrophils into the pleural space. We identified for the first time the mechanisms by which LTB(4) interacts with mesothelial cells and recruits neutrophils in the pleural compartment. Primary pleural mesothelial cells express both the proinflammatory receptor for LTB(4) BLT2, and the anti-inflammatory receptor for LTB(4), PPARalpha. Parapneumonic pleural effusions highly increase BLT2 expression and, via BLT2 activation, increase the adhesion between mesothelial cells and neutrophils and the expression of ICAM-1 on mesothelial cells. The block of PPARalpha further increases both cell adhesion and ICAM-1 expression. BLT2 activation promotes the activation, on mesothelial cells, of STAT-1 but not the activation of NF-kappaB transcription factor. The increase of ICAM-1 expression is achieved via increased tyrosine phosphorylation activity since herbimycin, a tyrosine kinase inhibitor, reduces and since Na orthovanadate, a tyrosine phosphatase inhibitor, further increases ICAM-1 expression. This study demonstrates that pleural mesothelial cells, expressing both proinflammatory and anti-inflammatory LTB(4) receptors, are able to mount an integrated response to LTB(4) with a prevalence of BLT2 activities in the presence of an inflammatory milieu within the pleura.

Topics: Adult; Aged; Blotting, Western; Cell Adhesion; Cells, Cultured; Chemotaxis, Leukocyte; Epithelium; Flow Cytometry; Humans; Inflammation; Intercellular Adhesion Molecule-1; Leukotriene B4; Middle Aged; Neutrophil Infiltration; Pleura; Pleural Effusion; Pneumonia; PPAR alpha; Receptors, Leukotriene B4

The pleural space is a virtual compartment between the lung and chest wall that becomes filled with fluid and inflammatory cells during a variety of respiratory diseases. Here, we study the potential role of the eicosanoid metabolite leukotriene B4 (LTB4) in disparate diseases leading to acute (pneumonia) or chronic (tuberculosis, cancer) inflammation of the pleural space. LTB4 concentrations were significantly higher in pleural fluid due to pneumonia, tuberculosis and cancer with respect to congestive heart failure and correlated with neutrophil elastase, which is used as an indication of state of activation of neutrophils in the pleural space. Moreover, pleural LTB4 was biologically active, as an anti-LTB4 antibody partially neutralized the chemotactic activity of parapneumonic, tuberculous and cancer effusions. Macrophages, neutrophils, lymphocytes, mesothelial cells and cancer cells all expressed mRNA for 5-lipoxygenase, the enzyme that initiates leukotriene synthesis leading to the production of LTB4, in exudative pleural effusions. Upon stimulation in transudative pleural effusions, pleural macrophages produced, in a time-dependent fashion, a significantly higher concentration of LTB4 than mesothelial cells. These studies demonstrate that different cell types are capable of producing LTB4 in the inflamed pleural space and that this mediator may play a crucial role in the recruitment of neutrophils into the pleural space.

Topics: Adult; Aged; Arachidonate 5-Lipoxygenase; Chemotaxis, Leukocyte; Epithelium; Gene Expression; Hot Temperature; Humans; Leukotriene B4; Lipopolysaccharides; Macrophage Activation; Middle Aged; Neoplasms; Neutrophil Infiltration; Neutrophils; Pancreatic Elastase; Pleural Effusion; Pneumonia; RNA, Messenger; Tuberculosis, Pulmonary

Leukotrienes (LTs) and prostaglandins (PGs) amplify acute inflammation, whereas lipoxins (LXs) have unique anti-inflammatory actions. Temporal analyses of these eicosanoids in clinical and experimental exudates showed early coordinate appearance of LT and PG with polymorphonuclear neutrophil (PMN) recruitment. This was followed by LX biosynthesis, which was concurrent with spontaneous resolution. Human peripheral blood PMNs exposed to PGE2 (as in exudates) switched eicosanoid biosynthesis from predominantly LTB4 and 5-lipoxygenase (5-LO)-initiated pathways to LXA4, a 15-LO product that "stopped" PMN infiltration. These results indicate that first-phase eicosanoids promote a shift to anti-inflammatory lipids: functionally distinct lipid-mediator profiles switch during acute exudate formation to "reprogram" the exudate PMNs to promote resolution.

Topics: Animals; Arachidonate 15-Lipoxygenase; Base Sequence; Dinoprostone; DNA, Complementary; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lipid Metabolism; Lipids; Lipoxins; Male; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Molecular Structure; Neutrophils; Pleural Effusion; RNA, Messenger; Signal Transduction

We evaluated the effects of a new non-steroidal anti-inflammatory drug (NSAID), d-2-[4-(3-methyl-2-thienyl)phenyl]propionic acid (M-5011), and indomethacin on the production of arachidonate metabolites and pro-inflammatory cytokines in male Sprague-Dawley rats with monosodium urate crystal (MSU)-induced pleurisy. Levels of tumor necrosis factor (TNF), interleukin (IL)-1 and IL-6 in the pleural exudate were determined by biological assays, while prostaglandin E2 (PGE2), leukotriene B4 (LTB4) and cytokine-induced chemoattractant-1 (CINC-1) levels were quantified by enzyme immunoassays. Orally administered M-5011 (5 mg/kg) decreased the pleural exudate volume at 3 and 4 hr after MSU injection. Indomethacin (10 mg/kg) decreased the volume at 3-5 hr. These drugs reduced the number of leukocytes in the pleural cavity at 6 hr. Both NSAIDs also reduced the content of PGE2 in the exudate without affecting LTB4 levels. Increased productions of both IL-6 and CINC-1 in the exudate were reduced by pretreatment with M-5011 or indomethacin, and TNF levels in the exudate were increased by pretreatment of these drugs. Thus, M-5011 inhibits the production of both IL-6 and CINC-1 at lower doses than those of indomethacin, and the inhibitory effect of M-5011 on CINC-1, but not IL-6, may partly contribute to the inhibition of leukocyte infiltration in rats with MSU-induced pleurisy.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cell Line; Cytokines; Dinoprostone; Exudates and Transudates; Humans; Indomethacin; Leukotriene B4; Male; Phenylpropionates; Pleura; Pleural Effusion; Pleurisy; Rats; Rats, Sprague-Dawley; Uric Acid

Des-Phe8-Arg9-BK could be detected in the entire course of rat carrageenin pleurisy up to 24 h, together with a reduction of the residual levels of high molecular weight kininogen and prekallikrein. On the basis of this continuous release of bradikinin, prostaglandin E2 was released up to 5 h in the pleural exudate and enhanced the plasma leakage. In rat cardiac infarction, the initial increase in the number of polymorphonuclear leukocytes in the cardiac tissue was accompanied by leukotriene B4 in the tissue and this was followed by the second increase and activation of the complement system.

Topics: Animals; Bradykinin; Cell Movement; Dinoprostone; Inflammation; Kallikreins; Leukocyte Count; Leukotriene B4; Neutrophils; Pleural Effusion; Rats; Time Factors

Quercetin reduced the concentration of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) in the pleural exudate induced in rats by 1% carrageenan given intrapleurally. Leucocyte migration in the exudate was also reduced by the flavonoid. Inhibition of eicosanoids and leucocytes in the exudate was dose-related. Quercetin also reduced LTB4 synthesis in cells stimulated with ionophore A23187, either ex-vivo or in-vitro. A similar, though less active, mode of action was found with quercitrin, while apigenin and luteolin reduced leucocyte accumulation and PGE2 formation, but not LTB4-formation.

Topics: Animals; Cell Movement; Dinoprostone; Flavonoids; Leukocytes; Leukotriene B4; Male; Pleural Effusion; Prostaglandins E; Rats; Rats, Inbred Strains

Leukotriene B4 (LTB4) has been implicated as a mediator in the inflammatory process by virtue of its potent chemotactic activity. At present, very little is known of the stability of this compound in vivo; therefore, the present study was designed to determine the half-life and metabolic fate of radiolabeled LTB4 during a 2-hr intrapleural incubation in rats with acute carrageenan pleurisy. After injection of 0.2 ml of 1% sodium carrageenan (Viscarin), inflammation was allowed to develop for 4 hr. A small polyethylene cannula was then inserted into the chest, and 0.1 microCi of [14C]LTB4 was injected into the chest. Samples for radioactivity determination were taken at 0, 1, 2, 3, 4, 5, 7, 10, 15, 20, 30, 45, 60, 90 and 120 min via the cannula, and at 120 min the entire content of the chest was collected. The half-life for the disappearance of radioactivity from the chest was 45.8 +/- 3.5 min. The 120-min samples were treated with acetone to precipitate protein and extracted with Sep-Paks. The extracts were analyzed by reversed phase high performance liquid chromatography using an ultraviolet detector set at 269 nm and a radioactivity detector. An additional experiment was run using multi-[3H]LTB4, and the only major metabolites detected were omega-hydroxylated compounds. It can be concluded from these results that LTB4 is relatively stable in vivo and could be present for long enough at the inflammatory site to have an influence upon inflammatory cell migration.

Topics: Animals; Carrageenan; Cell Movement; Chromatography, High Pressure Liquid; Female; Half-Life; Kinetics; Leukotriene B4; Pleural Effusion; Pleurisy; Rats