title: In vitro therapeutic effect of epigallocatechin gallate on nicotine-induced impairment of resistance to Legionella pneumophila infection of established MH-S alveolar macrophages.
abstract: Epigallocatechin gallate (EGCg), a major form of tea catechins, has a variety of biological activities. Tobacco smoking, nicotine in particular, is one of the risk factors for respiratory infections. In the present study, a possible immunotherapeutic effect of EGCg on the nicotine-induced impairment of alveolar macrophages regarding antimicrobial activity, as well as immune function, was examined. The treatment of MH-S macrophages with nicotine significantly enhanced Legionella pneumophila replication in the cells and selectively down-regulated the production of interleukin (IL)-6, IL-12, and tumor necrosis factor (TNF)-alpha induced by infection but did not alter IL-10 production. The EGCg treatment of nicotine-suppressed macrophages reconstituted the resistance to the infection. Furthermore, EGCg diminished the nicotine-induced inhibition of cytokine production. Experiments with TNF-alpha treatment, neutralization of cytokines with antibodies, and analysis of interferon (IFN)-gamma messenger RNA showed that the mechanism of the EGCg-induced recovery of anti-L. pneumophila activity impaired by nicotine may be due to the recovery of TNF-alpha and IFN-gamma production by the macrophages.
authors.affiliation: Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, Tampa, FL 33612-4799, USA.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Matsunaga
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Klein
authors.forename: Herman
authors.initials: H
authors.lastname: Friedman
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology*; D002460:Cell Line; D016207:Cytokines / Q000096:biosynthesis; D007371:Interferon-gamma / Q000494:pharmacology; D016952:Legionella pneumophila / Q000254:growth & development / Q000276:immunology*; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000276:immunology / Q000382:microbiology; D051379:Mice; D009538:Nicotine / Q000633:toxicity*; D013662:Tea; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D016207:Cytokines; D013662:Tea; D014409:Tumor Necrosis Factor-alpha; D009538:Nicotine; D007371:Interferon-gamma; D002392:Catechin; C045651:epigallocatechin gallate