The intestinal microbiota has been widely investigated nowadays, especially for its high population density, wide diversity and complexity of interactions. It is well know that bacterial cells are able to influence on immunological, nutritional, and physiological processes in the host. The culture-independent methods, based on the sequence diversity of the 16S ribosomal RNA gene, enabled the analysis of the microbiota composition and its relationship with some health disorders. This work aims to investigate the effect of potential beneficial microorganisms on fecal microbiota composition and host mRNA response, in different stages of chemically induced colitis in mice in order to determine the possible mechanisms associated. Colitis will be induced by 3% dextran sulfate sodium (DSS), being studied two phases of colitis: acute (14 days) and chronic (28 days). The animals will then be randomly assigned into five groups (n=10): Group C: healthy animals that do not receive the microorganisms under study; Group CL: animals with colitis that do not receive the microorganisms under study; Group CLC: animals with colitis that receive a mixture of probiotics strains (E. faecium CRL 183, L. helveticus 416 and B. longum ATCC 15707); Group CLF: animal with colitis that receive the fermented product (E. faecium CRL 183, L. helveticus 416 and B. longum ATCC 15707); Group CLP: animals with colitis that receive the potential probiotic strains (Lactobacillus spp. and Bifidobacterium spp.) isolated from their own faeces (individualized treatment). The intestinal microbiota composition will be monitored by independent growth technique (qPCR) before, during and after ingestion the microorganisms under study. At the end of each stage of colitis, the animals will be euthanized and the large intestine will be removed to perform host mRNA responses (gene transcript levels of the inflammatory mediators).
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