title: Oral administration of heat-killed Lactobacillus pentosus strain b240 augments protection against influenza virus infection in mice.
abstract: Host-defense mechanisms against influenza virus (IFV) infection involve both innate and acquired immunities. Among other components, secretory immunoglobulin A (SIgA) in the airway mucosa plays a particularly pivotal role in preventing IFV infection. Among 150 strains of lactic acid bacteria, Lactobacillus pentosus strain b240 (b240) has the highest IgA-inducing potency in mouse Peyer's patch cells. We previously reported a practical new finding that oral ingestion of nonviable heat-killed b240 elevates salivary IgA secretion in humans. The present study aimed to determine if nonviable b240 can prevent IFV infection in mice. In a BALB/c mouse model infected with lethal levels of IFV A/PR8/34 (H1N1), oral administration of b240 for 3 weeks by gavage prior to IFV infection significantly prolonged the survival period. For IFV infection at nonlethal levels, the infectious titers of IFV in the lungs 7 days after infection were significantly reduced after similar b240 administration. Both anti-IFV IgA and immunoglobulin G titers in bronchoalveolar lavage fluid and plasma on day 7 were significantly higher in the b240-treated group than the control group. The augmentation of the anti-IFV immune response by b240 application was preliminarily confirmed by the elevated production of IFV-driven T-cell factors during mixed lymphocyte reactions with b240-primed splenocytes. These results suggest that oral nonviable heat-killed b240 intake can facilitate protection against IFV infection.
authors.affiliation: Biomedical Laboratory, Division of Biomedical Research, Kitasato Institute Medical Center Hospital, Kitasato University, Saitama, Japan.
authors.forename: Noritada
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Takao
authors.initials: T
authors.lastname: Saito
authors.forename: Takayuki
authors.initials: T
authors.lastname: Uematsu
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Kishi
authors.forename: Masamichi
authors.initials: M
authors.lastname: Toba
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kohda
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002460:Cell Line; D004285:Dogs; D004847:Epithelial Cells / Q000821:virology; D005260:Female; D006358:Hot Temperature; D007111:Immunity, Cellular / Q000276:immunology; D018928:Immunity, Mucosal / Q000276:immunology; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity; D007778:Lactobacillus / Q000276:immunology*; D008168:Lung / Q000276:immunology / Q000821:virology; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009976:Orthomyxoviridae Infections / Q000276:immunology / Q000517:prevention & control*
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G