Molecular biological study of leukotoxin and its diol-induced cell activation and injury -experimental model of ARDS-

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We previously reported that leukotoxin (Lx), an epoxide of linolate, which activated pulmonary vascular endothelial nitric oxide synthase and xanthine oxidase, producing nitric oxide and OィイD22ィエD2-respectively, potentially injured cells. We wondered whether Lx could activate neutrophils and alveolar macrophage, inflammatory phagocytic cells. We also wondered whether epoxide-diol of Lx, a Lx-diol which was reported to be an important cellular toxic substance, realy exert its toxicity in pulmonary vascular endothelial cells. To answer these questions we tested the experiments using human neutrophils (PMN), rat alveolar macrophage (Mac), human pulmonary artery endothelial cell (HPAEC) and chinese hamster ovary cell (CHO). Lx and Lx-diol caused potent chemotaxis of PMN via pertussis toxin-sensitive signal transduction without expression of CDIIb or CD18 adhesion molecules or production of peroxides. Lx, however, did not activate Mac in terms of production of nitric oxide or OィイD22ィエD2- with slight enhanced production of TNFα.Lx and its diol caused slight injury of HPAEC, however, when cell glutathione contents were depleted Lx exerted more potent cytotoxicity. TSO, another epoxide, also exerted cytotoxicity in CHO whereas TSO-induced cytotoxicity was attenuated in human soluble epoxide hydrolase (hsEH) cDNA transfected CHO. Since TSO-diol injured glutathione-depleted hsEH cDNA transfected CHO, glutathione was an essential substance against epoxide-diol-induced injury. Our current study suggests inflammation provoking effects of Lx and its diol and further suggests glutathione-depleted pathological state such an acute lung injury including ARDS may augment cytotoxicity of Lx and Lx-diol.