Abstract
To maintain homeostasis of the immune system is considered important for the prevention of influenza A virus infection. Aberrant systemic inflammation is frequently induced by influenza A virus infection, and the severity of the symptoms is associated with pathogenicity of the virus. Lactic acid bacteria are known to have a positive effect in maintaining the immune system. Furthermore, preparations of a lactic acid bacteria strain, Enterococcus faecalis FK-23 (FK-23), have been reported to exert preferable homeostatic effects on immune diseases such as allergic rhinitis and early asthmatic responses. In this study, we examined the efficacy of the water-soluble fraction of lysed and heat-treated FK-23 (SLFK) against a lethal influenza A virus challenge. Mice were orally administered SLFK from day −7 to day 20, and intranasally infected with influenza virus A/Puerto Rico/8/34 (H1N1) at 103 PFU on day 0. The survival rate of SLFK-administered mice after influenza A virus infection was significantly improved compared with that of control mice. In addition, the mRNA expression level of the anti-inflammatory cytokine interleukin-10 (IL-10) in lung tissues was enhanced by the oral administration of SLFK after influenza A virus infection. These observations suggest that the oral administration of SLFK exerts a protective effect against influenza virus infection through the activation of the anti-inflammatory response.
References
1.Abe SOhashi KUchida KIkeda TKimura SYamaguchi H. Antitumor, antimicrobial activities of enterococcal preparation orally administered to miceAnn NY Acad Sci1993685372-374. 1. Abe S, Ohashi K, Uchida K, Ikeda T, Kimura S, and Yamaguchi H: Antitumor and antimicrobial activities of enterococcal preparation orally administered to mice. Ann NY Acad Sci 1993 685:372–374.
Crossref PubMed Google Scholar
2. Allen ICScull MAMoore CB et al. The NLRP3 inflammasome mediates in vivo innate immunity to influenza A virus through recognition of viral RNAImmunity200930556-565. 2. Allen IC, Scull MA, Moore CB, et al.: The NLRP3 inflammasome mediates in vivo innate immunity to influenza A virus through recognition of viral RNA. Immunity 2009;30:556–565.
Crossref PubMed Google Scholar
3. Bridges CBThompson WWMeltzer MI et al. Effectiveness and cost-benefit of influenza vaccination of healthy working adults: A randomized controlled trialJAMA20002841655-1663. 3. Bridges CB, Thompson WW, Meltzer MI, et al.: Effectiveness and cost-benefit of influenza vaccination of healthy working adults: A randomized controlled trial. JAMA 2000;284:1655–1663.
Crossref PubMed Google Scholar
4.Carrat FValleron AJ. Anti-influenza vaccine. Bibliographic reviewRev Mal Respir199411239-255. 4. Carrat F, and Valleron AJ: Anti-influenza vaccine. Bibliographic review. Rev Mal Respir 1994;11:239–255.
References