title: Live  Legionella pneumophila  induces MUC5AC production by airway epithelial cells independently of intracellular invasion.
abstract: The airway epithelium is the initial barrier against airborne pathogens, and it plays many roles in host airway defense.  Legionella pneumophila  is an intracellular pathogen that causes rapidly advancing pneumonia and is sometimes life-threatening. Here, we evaluated the role of the airway epithelial cells in the defense against L. pneumophila by examining mucus production in vitro. The production of MUC5AC, a major mucin protein, was not induced by formalin- or ultraviolet-killed L. pneumophila, but it was induced by live L. pneumophila. Similarly, nuclear factor-kappaB (NF-κB) was activated only by live L. pneumophila. Inhibitors of ERK and JNK, but not p38, dose-dependently inhibited the induction of MUC5AC by live L. pneumophila. Inhibition of intracellular invasion by cytochalasin D did not affect MUC5AC production. Taken together, the results suggest that live L. pneumophila induces MUC5AC production via the ERK-JNK and NF-κB pathways without internalization of bacteria and that the airway epithelium produces mucin as part of the immune response against L. pneumophila.
authors.affiliation: Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1, Sakamoto, Nagasaki, Japan.
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Morinaga
authors.forename: Katsunori
authors.initials: K
authors.lastname: Yanagihara
authors.forename: Nobuko
authors.initials: N
authors.lastname: Araki
authors.forename: Yohei
authors.initials: Y
authors.lastname: Migiyama
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nagaoka
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Harada
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamada
authors.forename: Hiroo
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nishino
authors.forename: Koichi
authors.initials: K
authors.lastname: Izumikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kakeya
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kohno
authors.forename: Shimeru
authors.initials: S
authors.lastname: Kamihira
mesh_terms: D004847:Epithelial Cells / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D006801:Humans; D055633:Immune System Phenomena / Q000502:physiology; D016952:Legionella pneumophila / Q000472:pathogenicity / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D055271:Mucin 5AC / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism
chemical_list: D055271:Mucin 5AC; D016328:NF-kappa B