Probiotic Treatment in vivo in Experimental Animals and in Man
To date only very few in vivo studies have been reported. In the experimental animal, treatment with Helicobacter felis-infected conventional mice with the spent culture supernatant of L. acidophilus strain LB inhibited the colonization of the stomach by the pathogen, although not for the long term (64). The application of the probiotic L. casei GG to conventional mice infected with Streptococcus enterica serovar Typhimurium significantly reduced the fecal cell counts of the pathogen adhesion of probiotic microorganisms to intestinal mucus of gnotobiotic mice (65).
Japanese investigators fed mice with bifidobacteria for 12 days and showed significantly high levels of fecal total lgA compared to the control group. Also, the levels of anti-p-Iactoglobulin IgA in milk and fecal extracts were significantly higher in the bifidobacteria-fed group than in control group (66). These findings were believed to be due to protection against food antigens, since the intake of bifidobacteria can enhance local production of IgA in milk and the intestine, which may help to protect from exposure to food antigens (66).
The oral administration of L. rhamnosus, L. acidophilus and B. lactis to healthy mice results in an enhanced formation of serum antibodies. The degree of enhancement was increased by consuming B. lactis in an oligosaccharide-rich substrate (67), as well as a significant increase in the phagocytotic activity of peripheral blood leukocytes and peritoneal macrophages, compared with the control mice.
Dieleman et al. (68), have recently investigated the ability of L. rhamnosus GG in the prevention of colitis in transgenic rats monoassociated with Bacteroides vulgatus and investigated whether Lactobacillus GG or L. plantarum 299v may treat established colitis in specific pathogen-free transgenic rats and prevent recurrent disease after antibiotics were stopped. Germ-free B27 transgenic rats were monoassociated with B. vulgatus for 4 weeks following 2 weeks of colonization with Lactobacillus GG or no bacteria. Specific pathogenfree HLA-B27 transgenic rats received oral vancomycin and imipenem for 2 weeks: or water alone, followed by 4 weeks of treatment with oral Lactobacillus GG, L. plantarum 299v, or water only. Oral vancomycin and imipenem resulted in undetectable levels of Bacteroides spp., that may selectively induce colitis in HLA-B27 transgenic mice. Disease activity was quantified by blinded gross and histological scores, cecal myeloperoxidase activity, and levels of IL-1 p, TNF, transforming growth factor-p (TGF-P) and IL-10. Lactobacillus GG did not prevent colitis in B. vulgatus co-associated transgenic rats or treat established disease in specific pathogen-free rats. Lactobacillus GG prevented colitis relapse in antibiotic-treated rats with significantly decreased gross cecal inflammation and histological scores, as well as cecal myeloperoxidase, IL-1p, and TNF. CecallL-10 was increased. L. plantarum 299v did not have any effect. This demonstrates the selective protective effects of two Lactobacillus species.
In man, a follow-up formula containing viable bifidobacteria was given to healthy Japanese children. Fecal levels of totallgA and antipoliovirus IgA during intake of the formula were significantly higher than those before intake (69). The consumption of formula containing viable B. lactis Bb12 for 20 days significantly increased the levels of total IgA and antipoliovirus IgA in feces of children aged 1531 months (69).
Feeding children with a formula supplemented with bifidobacteria may provide protection against symptomatic rotavirus infection (11). The immune response to probiotic bacteria depends on the strain used, and they are only effective at a sufficiently high dosage.
More recently, Hideki Ishikawa et al. (70) studied the effect of Bifidobacteria-fermented milk on ulcerative colitis. Two groups were observed: a Bifidobacteria-fermented milk group, which was administred 100 ml Bifidobacteria-fermented milk per day for 1 year and a control group. Colonoscopies were performed, as were measures of general blood markers and examinations of the intestinal flora, including the analysis of fecal organic acids. Results showed an exacerbation ulcerative colitis symptoms in three out of 11 patients in the Bifidobacteria-fermented milk group, compared to nine out of 10 in the control group. This shows a significant reduction in exacerbations in the Bifidobacteria-fermented milk group. There were no differences in colonoscopic findings between the two groups at the end of the study. Furthermore, the analysis of microflora and the organic acids in the feces showed a significant reduction in the relative proportion of B. vulgatus in Bacteroidaceae and butyrate concentration, respectively, due to Bifidobacteria-fermented milk supplementation. It was concluded that that supplementation with Bifidobacteria-fermented milk was successful in maintaining remission in ulcerative colitis, and may have preventive effects on the relapse of this disease.