Effect of Lactobacillus fermentum to alleviate symptoms of DSS-induced inflammatory bowel disease

학위논문 (석사)-- 서울대학교 대학원 : 보건대학원 환경보건학과, 2018. 8. 고광표.We identified and evaluated immunometabolic functions of novel Lactobacillus fermentum strains (KBL374, KBL375) isolated from healthy Korean stools. When human peripheral blood mononuclear cells PBMCs were treated with these L. fermentum KBL374 or KBL375 strains, pro-inflammatory cytokines such as IL-2, IFN-γ, IL-4, and IL-17A etc were reduced and anti-inflammatory cytokine such as IL-10 were elevated. When these strains were orally administered into DSS-induced colitis mice model, both L. fermentum KBL374 and KBL375 showed beneficial effects in terms of colon length, cecum weight and histological scores. As consistent with PBMC data in human, both L. fermentum KBL374 and KBL375-treated mice demonstrated reduced Th1-, Th2- and Th17-type cytokine levels and increased IL-10 levels compared to DSS control group in the colon. In addition, administration of L. fermentum KBL374 or KBL375 in mice increased CD4+CD25+Foxp3+Treg populations in MLN. Furthermore, both L. fermentum KBL374 and KBL375 were demonstrated to modulate the innate immune response by improving gut barrier functions and reducing leukocyte infiltration. In addition to regulate the immune response, the administration of L. fermentum KBL374 or KBL375 reshaped and increased the composition of diversity of gut microbiota. In particular, L. fermentum KBL375 increased abundance of beneficial microorganisms such as Lactobacillus spp. and Akkermansia spp. We observed through the results of this study that both L. fermentum KBL374 and KBL375 alleviate inflammatory diseases such as IBD in the gut by regulating immune responses and altering the composition of gut microbiota and metabolite.I. Introduction . 1 II. Materials and Methods . 4 1. Bacterial strains preparation. 4 2. Preparation and treatment of PBMC 6 3. Experimental colitis in vivo .. 7 4. Histological analysis 8 5. Real-time PCR 10 6. Myeloperoxidase (MPO) measurement 14 7. Measurement of cytokine in protein level 15 8. Flow cytometry anlaysis. 16 9. Taxanomic and functional analysis of gut microbiota. 17 10. Metabolic analysis using Ultra Performance Liquid Chromatography (UPLC). 19 11. Statistical analysis. 21 III. Results . 22 1. Lactobacillus fermentum Spp. differentially induce cytokine production in PBMC 22 2. L. fermentum KBL374 and KBL375 alleviate the symptoms of DSS-induced colitis in vivo . 26 3. Administration of L. fermentum KBL374 and KBL375 decreases AMP and increases tight junction related genes in colon 30 4. L. fermentum KBL374 and KBL375 reduce leukocyte recruitment in colon 34 5. L. fermentum KBL374 and KBL375 down-regulate protein levels and mRNA expression of Th1-, Th2- and Th17-type cytokines in the colon 37 6. The effect of L. fermentum KBL374 and KBL375 on T regulatory cells population in MLN. 40 7. L. fermentum KBL374 and KBL375 administration significantly change community structure of the cecal microbiota. 43 8. L. fermentum KBL374 and KBL375 administration alter the cecal microbiota at genus level 45 9. L. fermentum KBL374 and KBL375 change in function of amino acid metabolism. 50 IV. Discussion 54 V. Reference . 63 VI. Appendix 68 VII. 국문초록. 74Maste