Gut microbiota of breast-fed infants are generally rich in bifidobacteria. Recent studies show that infant gut-associated bifidobacteria can assimilate human milk oligosaccharides (HMOs) specifically among the gut microbes. Nonetheless, little is known about how bifidobacterial-rich communities are shaped in the gut. Interestingly, HMOs assimilation ability is not related to the dominance of each species. Bifidobacterium longum susbp. longum and Bifidobacterium breve are commonly found as the dominant species in infant stools; however, they show limited HMOs assimilation ability in vitro. In contrast, avid in vitro HMOs consumers, Bifidobacterium bifidum and Bifidobacterium longum subsp. infantis, are less abundant in infant stools. In this study, we observed altruistic behaviour by B. bifidum when incubated in HMOs-containing faecal cultures. Four B. bifidum strains, all of which contained complete sets of HMO-degrading genes, commonly left HMOs degradants unconsumed during in vitro growth. These strains stimulated the growth of other Bifidobacterium species when added to faecal cultures supplemented with HMOs, thereby increasing the prevalence of bifidobacteria in faecal communities. Enhanced HMOs consumption by B. bifidum-supplemented cultures was also observed. We also determined the complete genome sequences of B. bifidum strains JCM7004 and TMC3115. Our results suggest B. bifidum-mediated cross-feeding of HMOs degradants within bifidobacterial communities.
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.
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.
The altered gut microbiota through supplementation of fermented milk containing the study probiotics may be a prospective target for protection against JCP, with beneficial effects on blood lipid levels.
Lactobacillus GG (LGG) and L. gasseri TMC0356 (TMC0356) were investigated for their ability to alleviate nasal blockage associated with allergic rhinitis using a guinea pig model. The increases in sRaw at 10 min and 5 hr after the exposure of the nasal mucosa to OVA were significantly alleviated in the guinea pigs orally administrated with LGG and TMC0356 compared with those of the control (P<0.05 and P<0.01). The total numbers of leukocytes, particularly eosinophils and neutrophils from the nasal cavity lavage fluid, and the OVA‐specific IgE concentration in the serum were also decreased in the guinea pigs orally administrated with LGG and TMC0356, although the decreases were not statistically significant. These results suggest that LGG and TMC0356 can alleviate antigen‐induced nasal blockage in earlyphase and late‐phase inflammatory responses associated with allergic rhinitis.
Lactobacillus GG and L. gasseri TMC0356 were examined for their potential to alter the immune responses of murine PP cells in vitro and in vivo. Lactobacillus GG and L. gasseri TMC0356 characteristically stimulated the production of IL-12, IL-6, IFN-γ and IgA from isolated PP cells in vitro. Anatomical analysis indicated uptake of these bacteria by the PP tissue after giving orally in mice. Isolated PP cells exposed to Lactobacillus GG in vivo secreted more IFN-γ, IL-6 and total IgA, whereas those exposed to L. gasseri TMC0356 in vivo did not exhibit altered immune responses in terms of cytokine and IgA production. Therefore, these two bacteria might exhibit different immunodulatory effects in host animals by strain-dependent interaction with gut-associated lymphoid tissues in vivo.
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.
Lactobacillus rhamnosus GG, Lactobacillus paracasei TMC0409, Streptococcus thermophilus TMC1543 and whey proteins were used to prepare fermented milk. For the experiment aP2 -agouti transgenic mice were pre-treated with a high-sucrose/high-fat diet for 6 weeks to induce obesity. The obese mice were fed a diet containing 1·2 % Ca and either non-fat dried milk (NFDM) or probiotic-fermented milk (PFM) with nutritional energy restriction for 6 weeks. The animals were examined after the treatment for changes in body weight, fat pad weight, fatty acid synthase (FAS) activity, lypolysis, the expression levels of genes related to lipid metabolism, insulin sensitivity in adipocytes and skeletal muscle and the presence of biomarkers for oxidative and inflammatory stress in plasma. It was found that the PFM diet significantly reduced body weight, fat accumulation, and adipocyte FAS activity, and increased adipocyte lipolysis as compared with the effects of the NFDM diet (P,0·05). The adipose tissue gene expression of 11b-hydroxysteroid dehydrogenase 1 (11b-HSD1) was significantly suppressed in mice that were fed PFM as compared with those that were fed NFDM (P,0·05). PFM caused a greater up-regulation of skeletal muscle PPARa, PPARd, uncoupling protein 3 (UCP3) and GLUT4 expression and a significant decrease in the plasma concentration of insulin, malondialdehyde, TNF-a, monocyte chemotactic protein-1 and C-reactive protein as compared with the effects of NFDM (P, 0·05). Fermentation of milk with selected probiotics and supplementation of milk with whey proteins may thus enhance anti-obesity effects of Ca and dairy products by the suppression of adipose tissue lipogenesis, activation of fat oxidation in skeletal muscle and reduction of oxidative and inflammatory stress.
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