verlukast and Inflammation

Insufficient oxygen delivery to organs leads to tissue dysfunction and cell death. Reperfusion, although vital to organ survival, initiates an inflammatory response that may both aggravate local tissue injury and elicit remote organ damage. Polymorphonuclear neutrophil (PMN) trafficking to remote organs following ischaemia/reperfusion (I/R) is associated with the release of lipid mediators, including leucotriene (LT) B4 , cysteinyl-LTs (CysLTs) and platelet-activating factor (PAF). Yet, their potentially cooperative role in regulating I/R-mediated inflammation has not been thoroughly assessed. The present study aimed to determine the cooperative role of lipid mediators in regulating PMN migration, tissue oedema and injury using selective receptor antagonists in selected models of I/R and dermal inflammation. Our results show that rabbits, pre-treated orally with BIIL 284 and/or WEB 2086 and MK-0571, were protected from remote tissue injury following I/R or dermal inflammation in an additive or synergistic manner when the animals were pre-treated with two drugs concomitantly. The functional selectivity of the antagonists towards their respective agonists was assessed in vitro, showing that neither BIIL 284 nor WEB 2086 prevented the inflammatory response to IL-8, C5a and zymosan-activated plasma stimulation. However, these agonists elicited LTB4 biosynthesis in isolated rabbit PMNs. Similarly, a cardioprotective effect of PAF and LTB4 receptor antagonists was shown following myocardial I/R in mice. Taken together, these results underscore the intricate involvement of LTB4 and PAF in each other's responses and provide further evidence that targeting both LTs and PAF receptors provides a much stronger anti-inflammatory effect, regulating PMN migration and oedema formation.

Topics: Amidines; Animals; Azepines; Biological Assay; Carbamates; Dermis; Disease Models, Animal; Extravasation of Diagnostic and Therapeutic Materials; Extremities; Inflammation; Leukotriene B4; Leukotrienes; Male; Mice; Mice, Inbred C57BL; Myocardial Ischemia; Neutrophil Infiltration; Platelet Activating Factor; Platelet Membrane Glycoproteins; Propionates; Quinolines; Rabbits; Receptors, G-Protein-Coupled; Receptors, Leukotriene; Reperfusion Injury; Triazoles

Inflammatory mediators are released from injured tissues being responsible for the first steps of inflammatory processes. Multidrug efflux transporters, members of the ATP-binding cassette (ABC) family, are ubiquitously expressed. ABCC molecules transport several endogenous substances, including leukotriene C4 (LTC4) and PGE2, which are involved in zymosan-induced inflammation. The present study investigated the role played by ABCC transporters on zymosan-induced peritonitis in mice. Most of the resident peritoneal cells were macrophages, based on their morphology and membrane-activated complex 3 expression. RT-PCR demonstrated that these cells expressed ABCC, and ABCC activity was analyzed in vivo via the s.c. injection of ABCC inhibitors [probenecid (PROB) 200 mg/kg or MK571 20 mg/kg], followed by an i.v. injection of carboxyfluorescein diacetate (CFDA), an ABCC fluorescent substrate. Both inhibitors increased CFDA accumulation, suggesting ABCC impairment. Moreover, ABCC reversors decreased zymosan-induced plasma exudation by 86.6 +/- 7.4 and 97.6 +/- 2.3%, a feature related to a diminished secretion of LTC(4) (65.1+/-11 and 47.8+/-9.9%) and PGE(2) (under basal levels). Cell migration was inhibited similarly. Furthermore, PROB and MK571 inhibited IL-1ss by 83.4 +/- 13 and 71.2 +/- 13.4% and TNF-alpha content by 47 +/- 4.5 and 28.9 +/- 0.8%, respectively. NO metabolites and reactive oxygen species production were also reduced. The present results suggest that ABCC molecules have a relevant role in the acute inflammatory response produced by zymosan in mice.

Topics: Animals; Antigens, Differentiation; Bronchodilator Agents; Cell Movement; Chemotaxis, Leukocyte; Edema; Eicosanoids; Inflammation; Interleukin-1beta; Lipopolysaccharides; Luminescence; Macrophage Activation; Macrophages, Peritoneal; Male; Mice; Monocytes; Multidrug Resistance-Associated Proteins; Peritonitis; Propionates; Quinolines; Respiratory Burst; Tumor Necrosis Factor-alpha; Zymosan

Cysteinyl leukotrienes (CysLTs) contribute to the development of airway obstruction and inflammation in asthma; however little information is available on the role of these molecules in the pathophysiology of respiratory syncytial virus (RSV) bronchiolitis. This study was designed to evaluate the effects of RSV infection on CysLTs production in a well-established mouse infection model. Furthermore, we assessed the effect of anti-inflammatory agents (a leukotriene receptor antagonist, MK-571, and dexamethasone) on the functional and immune changes induced by RSV infection. Six to 8-wk-old BALB/c mice were infected with human RSV (strain A2). Measurements of airway function were performed using whole body plethysmography. Lung inflammation was assessed by cell counts, measurement of cytokines and CysLTs in bronchoalveolar lavage fluid (BALF) in the absence and presence of treatment with MK-571 or dexamethasone. RSV infection produced a marked increase in CysLTs in the BALF and lung tissue, recruitment of neutrophils and lymphocytes into the airways, increased IFN-gamma levels and airway hyperresponsiveness (AHR). Treatment with MK-571 decreased RSV-induced AHR without affecting the cellular and inflammatory responses to RSV. Dexamethasone decreased AHR and markedly reduced the recruitment of inflammatory cells and production of IFN-gamma. Our findings suggest CysLTs play an important role in the pathogenesis of RSV-induced airway dysfunction. Treatment with MK-571 decreases RSV-induced AHR but does not appear to alter the lung inflammatory responses to RSV. In contrast, dexamethasone decreases RSV-induced AHR but interferes with recruitment of inflammatory cells, resulting in decreased Th1 cytokines (a potentially Th2-prone environment) in this model. These studies support recent reports on the beneficial effects of CysLT receptor antagonist in human trials and provide a model for investigating the role of CysLTs in RSV bronchiolitis.

Topics: Animals; Anti-Inflammatory Agents; Asthma; Bronchial Hyperreactivity; Bronchoalveolar Lavage Fluid; Bronchoconstriction; Cysteine; Dexamethasone; Disease Models, Animal; Female; Inflammation; Interferon-gamma; Leukotrienes; Lymphocyte Count; Lymphocytes; Macrophages; Membrane Proteins; Mice; Mice, Inbred BALB C; Neutrophil Infiltration; Propionates; Quinolines; Receptors, Leukotriene; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human

The cysteinyl leukotrienes (cys-LTs) LTC(4), LTD(4), and LTE(4) are a class of peptide-conjugated lipids formed from arachidonic acid and released during activation of mast cells (MCs). We now report that human cord-blood-derived MCs (hMCs) express the CysLT1 receptor, which responds not only to inflammation-derived cys-LTs, but also to a pyrimidinergic ligand, UDP. hMCs express both CysLT1 protein and transcript, and respond to LTC(4), LTD(4), and UDP with concentration-dependent calcium fluxes, each of which is blocked by a competitive CysLT1 receptor antagonist, MK571. Stably transfected Chinese hamster ovary cells expressing the CysLT1 receptor also exhibit MK571-sensitive calcium flux to all three agonists. Both hMCs and CysLT1 transfectants stimulated with UDP are desensitized to LTC(4), but only partially to LTD(4). Priming of hMCs with IL-4 for 5 days enhances their sensitivity to each agonist, but preferentially lowers their threshold for activation by LTC(4) and UDP (approximately 3 log(10)-fold shifts in dose-response for each agonist) over LTD(4) (1.3 log(10)-fold shift), without altering CysLT1 receptor mRNA or surface protein expression, implying the likely induction of a second receptor with CysLT1-like dual ligand specificity. hMCs thus express the CysLT1 receptor, and possibly a closely related IL-4-inducible receptor, which mediate dual activation responses to cys-LTs and UDP, providing an apparent intersection linking the inflammatory and neurogenic elements of bronchial asthma.

Topics: Amino Acid Sequence; Animals; CHO Cells; Cricetinae; Humans; Inflammation; Leukotriene Antagonists; Mast Cells; Membrane Proteins; Molecular Sequence Data; Propionates; Pyrimidines; Quinolines; Receptors, Leukotriene; RNA, Messenger; Sequence Alignment; Transfection