The effect of fermented milk supplemented with whey protein concentrate on the serum lipid level of rats was investigated. The serum total cholesterol level for the group fed fermented milk with both Lactobacillus casei TMC0409 and Streptococcus thermophilus TMC 1543 was significantly lower than that of the control group (P<0.05) in rats. Furthermore, the effect of the longterm intake of this fermented milk on the serum lipid level of twenty healthy adult men was investigated. During the 8-wk study, the volunteers consumed 200 ml of fermented milk or placebo in the morning and evening. Blood samples were drawn for analysis three times, just before taking the experimental diet, and after 4 wk and 8 wk of consumption. After 8 wk, the high density lipoprotein cholesterol level for the fermented milk group showed a significant rise after 4 wk (P<0.05), whereas that of the placebo group showed no change even after 4 wk (P>0.05). The triglyceride level for the fermented milk group lowered significantly after 4 wk (<0.05), whereas that of the placebo group showed no change even after 4 wk (P>0.05). The atherogenic index [(total cholesterol - high density lipoprotein cholesterol)/high-density lipoprotein cholesterol] for the fermented milk group decreased significantly from 4.24 to 3.52 (P<0.05). The systolic blood pressure lowered significantly by the intake of fermented milk (P<0.05) On the other hand, such effect was not observed in the placebo group (P>0.05). These results indicate potential of the development of fermented milk with multiple therapeutic effects.

Aims:  To investigate whether intranasal Lactobacillus administration protects host animals from influenza virus (IFV) infection by enhancing respiratory immune responses in a mouse model. Methods and Results:  After 3 days of intranasal exposure to Lactobacillus rhamnosus GG (LGG), BALB/c mice were infected with IFV A/PR/8/34 (H1N1). Mice treated with LGG showed a lower frequency of accumulated symptoms and a higher survival rate than control mice (P < 0·05). The YAC‐1 cell‐killing activity of lung cells isolated from mice treated with LGG was significantly greater than those isolated from control mice (P < 0·01). Intranasal administration of LGG significantly increased mRNA expression of interleukin (IL)‐1β, tumour necrosis factor (TNF) and monocyte chemotactic protein (MCP)‐1 (P < 0·01). Conclusions:  These results suggest that intranasal administration of LGG protects the host animal from IFV infection by enhancing respiratory cell‐mediated immune responses following up‐regulation of lung natural killer (NK) cell activation. Significance and Impact of Study:  We have demonstrated that probiotics might protect host animals from viral infection by stimulating immune responses in the respiratory tract.

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This study investigated whether heat-killed Lactobacillus protects host animal against influenza virus infection and stimulates their immunity. Heat-killed Lactobacillus gasseri TMC0356 was orally administered to BALB/c mice for 19 days; the mice were intranasally infected with Flu A/PR/8/34 (H1N1) on day 14, and clinical symptoms were monitored. After 6 days, the mice were sacrificed, and pulmonary virus titres were determined. Splenic activation of natural killer (NK) cells and the mRNA expression of cytokines and other immune molecules in the lung and Peyer's patch (PP) were analysed. Clinical symptom scores of mice orally fed TMC0356 ameliorated significantly (P < 0.01); their pulmonary virus titres decreased significantly compared with those of control mice (P < 0.05); their mRNA expression of interleukin (IL)-12, IL-15 and IL-21 in PP and the pulmonary mRNA expression of IFN-γ, TNF, IL-12a, IL-12rbl, IL-2rb and perforin 1 increased significantly (P < 0.05). Oral administration of heat-killed lactobacilli may protect against influenza virus infection by stimulating local and systemic immune responses. Cellular components of lactobacilli may be pivotal in protecting against viral infection by enhancing gut and respiratory immune responses.

Aims:  Our study was conducted to evaluate the potent protective effects of oral administration of probiotic Lactobacillus strains against influenza virus (Flu) infection in a mouse model. Method and Results:  Lyophilized Lactobacillus rhamnosus GG (LGG) and Lactobacillus gasseri TMC0356 (TMC0356) were orally administered to BALB/c mice for 19 days. The test mice were intranasally infected with Flu A/PR/8/34 (H1N1) on day 14, and any changes in clinical symptoms were monitored. After 6 days of infection, the mice were killed and pulmonary virus titres were determined. The clinical symptom scores of mice administered oral LGG and TMC0356 were significantly ameliorated, compared to those of the control mice (P < 0·01). The pulmonary virus titres of the mice fed LGG and TMC0356 were also significantly decreased compared to those of control mice (P < 0·05). Conclusions:  These results indicate that oral administration of lactobacilli, such as LGG and TMC0356, might protect a host animal against Flu infection. Significance and Impact of the Study:  These results demonstrate that oral administration of selected lactobacilli might protect host animals from Flu infection by interactions with gut immunity.