title: The serine protease inhibitor camostat inhibits influenza virus replication and cytokine production in primary cultures of human tracheal epithelial cells.
abstract: BACKGROUND
  Serine proteases act through the proteolytic cleavage of the hemagglutinin (HA) of influenza viruses for the entry of influenza virus into cells, resulting in infection. However, the inhibitory effects of serine protease inhibitors on influenza virus infection of human airway epithelial cells, and on their production of inflammatory cytokines are unclear.
  
  
  METHODS
  Primary cultures of human tracheal epithelial cells were treated with four types of serine protease inhibitors, including camostat, and infected with A/Sendai-H/108/2009/(H1N1) pdm09 or A/New York/55/2004(H3N2).
  
  
  RESULTS
  Camostat reduced the amounts of influenza viruses in the supernatants and viral RNA in the cells. It reduced the cleavage of an influenza virus precursor protein, HA0, into the subunit HA1. Camostat also reduced the concentrations of the cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α in the supernatants. Gabexate and aprotinin reduced the viral titers and RNA levels in the cells, and aprotinin reduced the concentrations of TNF-α in the supernatants. The proteases transmembrane protease serine S1 member (TMPRSS) 2 and HAT (human trypsin-like protease: TMPRSS11D), which are known to cleave HA0 and to activate the virus, were detected at the cell membrane and in the cytoplasm. mRNA encoding TMPRSS2, TMPRSS4 and TMPRSS11D was detectable in the cells, and the expression levels were not affected by camostat.
  
  
  CONCLUSIONS
  These findings suggest that human airway epithelial cells express these serine proteases and that serine protease inhibitors, especially camostat, may reduce influenza viral replication and the resultant production of inflammatory cytokines possibly through inhibition of activities of these proteases.
authors.affiliation: Department of Advanced Preventive Medicine for Infectious Disease, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan. Electronic address: myamaya@med.tohoku.ac.jp.
authors.forename: Mutsuo
authors.initials: M
authors.lastname: Yamaya
authors.affiliation: Department of Infectious Diseases, Yamagata University Faculty of Medicine, Yamagata 990-9585, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Shimotai
authors.affiliation: Division of Oncology, Kobe City Medical Center General Hospital, Kobe 650-0047, Japan; Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
authors.forename: Yukimasa
authors.initials: Y
authors.lastname: Hatachi
authors.affiliation: Department of Advanced Preventive Medicine for Infectious Disease, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
authors.forename: Nadine
authors.initials: N
authors.lastname: Lusamba Kalonji
authors.affiliation: Department of Advanced Preventive Medicine for Infectious Disease, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan; Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Tando
authors.affiliation: Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kitajima
authors.affiliation: Department of Behavioal Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Matsuo
authors.affiliation: Department of Advanced Preventive Medicine for Infectious Disease, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kubo
authors.affiliation: Medicine and Science in Sports and Exercise, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Nagatomi
authors.affiliation: Department of Infectious Diseases, Yamagata University Faculty of Medicine, Yamagata 990-9585, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Hongo
authors.affiliation: Virus Research Center, Clinical Research Division, Sendai National Hospital, Sendai 983-8520, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Homma
authors.affiliation: Virus Research Center, Clinical Research Division, Sendai National Hospital, Sendai 983-8520, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Nishimura
mesh_terms: D000368:Aged; D000818:Animals; D007611:Aprotinin / Q000494:pharmacology; D002478:Cells, Cultured; D004285:Dogs; D004847:Epithelial Cells / Q000187:drug effects / Q000821:virology; D004952:Esters; D005260:Female; D016670:Gabexate / Q000031:analogs & derivatives* / Q000494:pharmacology; D006146:Guanidines; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification; D053122:Influenza A Virus, H3N2 Subtype / Q000302:isolation & purification; D007251:Influenza, Human / Q000188:drug therapy* / Q000821:virology; D061985:Madin Darby Canine Kidney Cells; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D014132:Trachea / Q000166:cytology / Q000821:virology; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D004952:Esters; D006146:Guanidines; D012367:RNA, Viral; D015842:Serine Proteinase Inhibitors; C034532:camostat; D016670:Gabexate; D007611:Aprotinin
keywords: Airway epithelial cell; Camostat; Cell culture; Influenza; Interleukin; Serine protease