Abstract
The effects of heat-treated Lactobacillus (Lb.) crispatus KT-11 on influenza virus infection and macrophage cytokine production in mice were investigated. The mice were orally administered saline containing heat-treated Lb. crispatus KT-11 (0, 1 or 10mg). Then, the mice were intranasally inoculated with influenza H1N1 virus and assessed for survival rate and changes in body weight. The mouse macrophage cell line RAW264 was cultured in the presence of heat-treated lactic acid bacteria for 48 hours. Cytokine levels in the cell culture supernatant were determined using ELISA. The area under the curve of changes in body weight (AUCW) in mice infected with influenza virus and orally administrated heat-treated Lb. crispatus KT-11 (1mg) was significantly higher than that in mice not administered any bacterium (control group). The concentrations of IFNα, TNFα, IL-1α and IL-6 were higher in the RAW264 cells cultured with heat-treated Lb. crispatus KT-11 than in control (non-addition of bacteria) or in those with other heat-treated bacteria. These results suggest that heat-treated Lb. crispatus KT-11 enhances macrophage cytokine production and protects against influenza virus infection.
