Effects of seven potential probiotic strains on specific immune responses in healthy adults: a double-blind, randomized, controlled trial.

This pilot study investigated the immunomodulatory properties of seven probiotic strains. Eighty-three healthy volunteers aged 18-62 years consumed 2 x 10(10) CFU of bacteria or a placebo (maltodextrin) over 3 weeks (D0-D21). Subjects received an oral cholera vaccine at D7 and at D14; blood and saliva samples were collected at D0, D21 and D28. Serum samples were analyzed for specific IgA, IgG and IgM, and saliva samples were analyzed for specific IgA only, by ELISA. Statistical analyses were based on Wilcoxon's signed-rank test (intragroup analyses) and exact median t-test (intergroup analyses). Salivary analysis showed no difference in specific IgA concentrations between groups. Serum analysis indicated an effect of some of the tested strains on specific humoral responses. Between D0 and D21, IgG increased in two probiotic groups, for example, Bifidobacterium lactis Bl-04 and Lactobacillus acidophilus La-14, compared with controls (P=0.01). Trends toward significant changes in immunoglobulin serum concentrations compared with controls (P<0.1) were found for six out of the seven probiotic strains. In conclusion, some strains of probiotics demonstrated a faster immune response measured with serum immunoglobulin indicators, especially IgG, although overall vaccination was not influenced. Specific strains of probiotics may thus act as adjuvants to the humoral immune response following oral vaccination.

Correlation between in vitro and in vivo immunomodulatory properties of lactic acid bacteria.

AIM: To investigate the correlation between in vitro and in vivo immunomodulation potential of the probiotic strain and its ability to prevent experimental colitis in mice. METHODS: In vitro immunomodulation was assessed by measuring interleukin (IL)-12p70, IL-10, tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) release by human peripheral blood mononuclear cells (PBMCs) after 24 h stimulation with 13 live bacterial strains. A murine model of acute TNBS-colitis was next used to evaluate the prophylactic protective capacity of the same set of strains. RESULTS: A strain-specific in vivo protection was observed. The strains displaying an in vitro potential to induce higher levels of the anti-inflammatory cytokine IL-10 and lower levels of the inflammatory cytokine IL-12, offered the best protection in the in vivo colitis model. In contrast, strains leading to a low IL-10/IL-12 cytokine ratio could not significantly attenuate colitis symptoms. CONCLUSION: These results show that we could predict the in vivo protective capacity of the studied lactic acid bacteria (LAB) based on the cytokine profile we established in vitro. The PBMC-based assay we used may thus serve as a useful primary indicator to narrow down the number of candidate strains to be tested in murine models for their anti-inflammatory potential.

Lactobacillus strains isolated from the vaginal microbiota of healthy women inhibit Prevotella bivia and Gardnerella vaginalis in coculture and cell culture.

The purpose of this study was to investigate how human vaginal isolates of Lactobacillus acidophilus, Lactobacillus jensenii, Lactobacillus gasseri and Lactobacillus crispatus inhibit the vaginosis-associated pathogens Gardnerella vaginalis and Prevotella bivia. Results show that all the strains in coculture condition reduced the viability of G. vaginalis and P. bivia, but with differing degrees of efficacy. The treatment of G. vaginalis- and P. bivia-infected cultured human cervix epithelial HeLa cells with L. gasseri strain KS120.1 culture or cell-free culture supernatant (CFCS) results in the killing of the pathogens that are adhering to the cells. The mechanism of the killing activity is not attributable to low pH and the presence of lactic acid alone, but rather to the presence of hydrogen peroxide and proteolytic enzyme-resistant compound(s) present in the CFCSs. In addition, coculture of G. vaginalis or P. bivia with L. gasseri KS120.1 culture or KS120.1 bacteria results in inhibition of the adhesion of the pathogens onto HeLa cells.

Vaginal Lactobacillus isolates inhibit uropathogenic Escherichia coli.

The purpose of this study was to investigate the antibacterial activities of Lactobacillus jensenii KS119.1 and KS121.1, and Lactobacillus gasserii KS120.1 and KS124.3 strains isolated from the vaginal microflora of healthy women, against uropathogenic, diffusely adhering Afa/Dr Escherichia coli (Afa/Dr DAEC) strains IH11128 and 7372 involved in recurrent cystitis. We observed that some of the Lactobacillus isolates inhibited the growth and decreased the viability of E. coli IH11128 and 7372. In addition, we observed that adhering Lactobacillus strains inhibited adhesion of E. coli IH11128 onto HeLa cells, and inhibited internalization of E. coli IH11128 within HeLa cells.