Probiotic effects of Lactobacillus casei on DSS-induced ulcerative colitis in mice.

We tested the effect of Lactobacillus casei strain Shirota (LcS) on the murine model of ulcerative colitis induced by dextran sodium sulphate. The effect of LcS was tested either as a prophylactic 10 days before the onset of the disease, simultaneously with ulcerative colitis induction or continued 10 days after the disease was induced. LcS was not able to prevent the disease induction in any of the experiments. However, important clinical parameters including blood anemia indicators, body weight, and organ weight were improved in the animals receiving LcS as compared with the ulcerative colitis-induced controls. Increased colonic epithelial regeneration in the LcS treated animals was observed in the chronic stage. The results seemed better for the simultaneous short LcS treatment where some parameters remained similar to the PBS controls, including disease activity scores measured in the acute stage. We can conclude that although LcS alone cannot prevent the induction of ulcerative colitis by dextran sodium sulphate, it can improve the clinical condition of the mice. This could imply important biological consequences for the human situation. Further studies including LcS or other probiotic bacteria together with the available treatment are encouraged.

Comparison of faecal Lactobacillus populations in experimental animals from different breeding facilities and possible consequences for probiotic studies.

AIMS: The effect of probiotic lactobacilli is likely dependent on the indigenous Lactobacillus strains in the intestinal tract. Since a substantial number of probiotic studies is performed in rodents, we compared the Lactobacillus strains of different rat and mouse populations in three animal facilities. METHODS AND RESULTS: SDS-PAGE and 16S rDNA analysis of cultured faecal lactobacilli revealed that different Lactobacillus strains were detected in genetically similar Wistar rats bred at different locations. Further, within the same animal facility host genetics did not affect the types of the predominant lactobacilli strains. CONCLUSIONS: Our results show that the environmental background of laboratory animals rather than host genetics determines the indigenous Lactobacillus strains that are found. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings underline the importance of microflora analysis in probiotic studies.