title: Leukotriene E4: perspective on the forgotten mediator.
abstract: Leukotriene (LT) E(4) mediates many of the principal features of bronchial asthma, such as bronchial constriction, hyperresponsiveness, eosinophilia, and increased vascular permeability. Furthermore, it is the most stable of the cysteinyl leukotrienes (CysLTs) and can be active at the site of release for a prolonged time after its synthesis. There might be several reasons why LTE(4) has been forgotten. LTE(4) demonstrated low affinity for CysLT(1) and CysLT(2) receptors in equilibrium competition assays. It was less potent than other CysLTs in functional assays, such as calcium flux, in cells transfected with CysLT(1) and CysLT(2). The introduction of CysLT(1) antagonists into clinical practice diverted interest into CysLT(1)-related mechanisms, which were mediated mainly by LTD(4). However, experiments with animal models and human studies have revealed that LTE(4) has unique characteristics that cannot be explained by the current knowledge of CysLT(1) and CysLT(2). These activities include its potency relative to other CysLTs to increase airway responsiveness to histamine, to enhance eosinophilic recruitment, and to increase vascular permeability. Asthmatic airways also demonstrate marked in vivo relative hyperresponsiveness to LTE(4), especially in patients with aspirin-sensitive respiratory disease. This has stimulated a search for additional LT receptors that would respond preferentially to LTE(4) stimulation.
authors.affiliation: MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, King's College London, London, United Kingdom. tak.lee@kcl.ac.uk
authors.forename: Tak H
authors.initials: TH
authors.lastname: Lee
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Woszczek
authors.forename: Sophie P
authors.initials: SP
authors.lastname: Farooque
mesh_terms: D000818:Animals; D001241:Aspirin / Q000009:adverse effects; D001249:Asthma / Q000188:drug therapy / Q000276:immunology*; D016535:Bronchial Hyperreactivity / Q000188:drug therapy / Q000276:immunology*; D004342:Drug Hypersensitivity / Q000188:drug therapy / Q000276:immunology*; D006632:Histamine; D006801:Humans; D017997:Leukotriene C4 / Q000276:immunology; D017998:Leukotriene D4 / Q000276:immunology; D017999:Leukotriene E4 / Q000276:immunology*; D016210:Methacholine Chloride; D018077:Receptors, Leukotriene / Q000276:immunology; D012867:Skin / Q000187:drug effects / Q000276:immunology / Q000473:pathology
chemical_list: D018077:Receptors, Leukotriene; D016210:Methacholine Chloride; D017997:Leukotriene C4; D017998:Leukotriene D4; D017999:Leukotriene E4; D006632:Histamine; D001241:Aspirin