leukotriene-c4 and Pleural-Effusion

In noninfected rats, challenge with allergen following local IgE sensitization induced a pleurisy marked by intense protein exudation that plateaued from 30 min to 4 h after challenge, reducing thereafter. Infection of rats with Angiostrongylus costaricensis induced a 5-fold increase in blood eosinophil numbers by 25 days postinfection, whereas the numbers of eosinophils in the pleural cavity ranged from normal to a weak increase. In infected rats, identically sensitized, challenge with Ag induced a much shorter duration of pleural edema with complete resolution by 4 h, but no change in the early edema response. In parallel, infection increased the number of eosinophils recovered from the pleural cavity at 4 h, but not at 30 min, following allergen challenge. Pretreatment with IL-5 (100 IU/kg, i.v.) also increased eosinophil numbers in blood and, after allergen challenge, shortened the duration of the pleural edema and increased pleural eosinophil numbers. There were increases in the levels of both PGE2 and lipoxin A4 (LXA4) in pleural exudate. Selective cyclooxygenase (COX)-2 inhibitors, NS-398, meloxicam, and SC-236, did not alter pleural eosinophilia, but reversed the curtailment of the edema in either infected or IL-5-pretreated rats. Pretreatment of noninfected animals with the PGE analogue, misoprostol, or two stable LXA4 analogues did not alter the magnitude of pleural exudation response, but clearly shortened its duration. These results indicate that the early resolution of allergic pleural edema observed during A. costaricensis infection coincided with a selective local eosinophilia and seemed to be mediated by COX-2-derived PGE2 and LXA4.

Topics: Administration, Oral; Angiostrongylus; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antigens, Helminth; Corticosterone; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprostone; Edema; Eosinophilia; Exudates and Transudates; Female; Hydroxyeicosatetraenoic Acids; Hypersensitivity; Injections, Intraperitoneal; Injections, Intravenous; Interleukin-5; Isoenzymes; Kinetics; Leukotriene C4; Lipoxins; Male; Misoprostol; Pleural Effusion; Pleurisy; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Strongylida Infections

The effect of fat-rich diets on the acute inflammatory response was examined. Male Wistar rats aged 21 days were fed, for 6 weeks, with a control diet (4% fat content), or a control diet supplemented with coconut or soybean oils (15% fat content). Carrageenan-induced paw oedema and pleurisy were evaluated. Prostaglandin (PG) E2 and leukotriene (LT) C4/D4 concentrations were determined in the pleural exudate (ELISA). Pleural samples were tested for their effect on cutaneous vascular permeability of control rats and the effect of a LTD4 receptor antagonist (L660-711; 10 mg/kg; i.v.) examined. Relative to controls, rats fed both fat-rich diets presented a significant reduction in protein leakage and oedema formation without affecting the number of migrating leukocytes. Production of LTC4/D4 in pleural exudate was significantly increased from 1.8 +/- 0.2 ng/ml in controls to 2.8 +/- 0.2 and 3.0 +/- 0.3 ng/ml in animals fed coconut and soybean oil enriched diets, respectively, without changes in PGE2 production. The activity of these samples on cutaneous vascular permeability was 50% reduced, returning to control values after treatment of testing animals with a LTD4 receptor antagonist. Rats fed fat-rich diets presented a reduced inflammatory response due, at least in part, to the LTC4/D4 mediated vasoconstrictor effect.

Topics: Acute-Phase Reaction; Animals; Capillary Permeability; Carrageenan; Coconut Oil; Dietary Fats; Dinoprostone; Edema; Enzyme-Linked Immunosorbent Assay; Exudates and Transudates; Hindlimb; Leukotriene Antagonists; Leukotriene C4; Leukotriene D4; Male; Plant Oils; Pleural Effusion; Pleurisy; Propionates; Quinolines; Rats; Rats, Wistar; Skin; Soybean Oil