| Summary: | 碩士 === 高雄醫學大學 === 醫學研究所 === 99 === Background: Lactobacillus and Bifidobacterium are the most common microbes used as probiotics. Although probiotics are good for mucosal immunity in the gut, it remains unclear how Lactobacillus and Bifidobacterium affect the naive CD4+ T cells differentiation, which is critical in intestinal mucosal immunity.
Materials and methods: Three strains of Lactobacillus, L. paracasei 33, L. casei 01 and L. paracasei D11a, and three strains of Bifidobacterium, B. lactis Bb12, B. lactis HN019, and B. longum, were used in this study. Multiplicity of infection (MOI) 30 of each strain was applied to the experiments. The splenocytes were isolated from C57BL/ 6 mice. Culture supernatant was collected for ELISA. Cell pellets were collected from real-time PCR analysis of the critical transcription factors for naive CD4+ T cells differentiation.
Results: We examined the expression of the 8 cytokines, namely IFNγ, TNFα, IL-4, 5, 6, 10, 12 and 17, after the six strains of probiotics were co-cultured with splenocytes for 12, 24 and 48 hrs. No expression of IL4, IL5 and TGFβ was detected in both groups, whereas the levels of IL-6 and 17 were similar in both groups. The level of IL12 was higher in Lactobacillus group than Bifidobacterium group at each time point (p<0.05). The expression of IL-10, IFNγ, and TNFα reached significantly high level at 48 hrs in both Lactobacillus and Bifidobacterium groups. This was compatible with the 8-fold higher expression of T-bet, which is a Th1 cell specific transcription factor, at 48 hrs.
Conclusion: Both Lactobacillus and Bifidobacterium induce murine splenocytes toward Th1 expression, especially after 48 hrs’ co-culture. Transcription factors, including GATA3, RORγt and FOXP3, were inhibited after 48 hrs’ co-culture. However, whether these results collectively exert pro-inflammatory or immunosuppressive effects in vivo awaits further validation.
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