Heat-killed Lactobacillus gasseri can enhance immunity in the elderly in a double-blind, placebo-controlled clinical study.

This double-blind, placebo-controlled clinical trial was conducted to test whether Lactobacillus gasseri TMC0356 (TMC0356) can modify the immune response in the elderly. Heat-killed TMC0356 or placebo was orally administered to 28 healthy subjects aged 50-70 years old for 4 weeks at a dosage of 1.0×10(9) cfu/day. Peripheral blood mononuclear cells (PBMCs) were collected from the subjects before and after the study completion, together with general health and blood examination records. Isolated PBMCs were examined for the number of T cells, CD8(+)CD28(+) cells, native T cells, B cells, natural killer (NK) cells and the ratios of CD4/CD8 T cells and native/memory T cells. NK cell activation and concanavalin A-induced lymphocyte transformation of the isolated PBMCs were also examined. The number of CD8(+) T cells significantly increased in the subjects after TMC0356 oral administration (P<0.05). Furthermore, the population of CD8(+)CD28(+) T cells and the amount of lymphocyte transformation both significantly decreased in PBMCs from the placebo group (P<0.05). However, such changes were not observed in the subjects exposed to TMC0356. These results suggest that TMC0356 can increase the number of CD8(+) T cells and reduce CD28 expression loss in CD8(+) T cells of the elderly. The effect of TMC0356 on immune responses in the elderly may enhance their natural defence mechanisms against pathogenic infections.

Oral administration of lactobacilli from human intestinal tract protects mice against influenza virus infection.

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.

Intranasal administration of Lactobacillus rhamnosus GG protects mice from H1N1 influenza virus infection by regulating respiratory immune responses.

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)-1 beta, 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.