Caracterização e avaliação das propriedades probióticas de lactococcus lactis NCDO 2118

Abstract

The prevalence of inflammatory bowel diseases (IBD) has increased in countries that adopt Western lifestyle, including Brazil. The two main IBD associated diseases are Ulcerative Colitis and Crohns Disease. Discovered nearly 100 years ago, the etiology of these diseases is not yet fully understood; however, there is growing evidence that IBD results from abnormal immune responses to the gut microbiota in individuals with genetic predisposition, resulting in a chronic inflammation in the gastrointestinal tract. The treatments currently available are accompanied by serious side effects. Recent studies have demonstrated the potential therapeutic use of probiotic bacteria in the treatment of these diseases, and many probiotics, have generat promising results. Most of them belong to the Lactic Acid Bacteria (LAB) group, which makes part of our healthy microbiota. However, little is known about the effects of transiting dairy bacteria that make part of our diet, including Lactococcus lactis. In this study we aimed to evaluate the immunomodulatory potential of three strains of L. lactis and analyzed their probiotic potential in the prevention of colitis in murine model. Firstly, we analyzed the potential immune modulatory effects of three L. lactis strains (L. lactis subsp. cremoris MG1363, L. lactis subsp. lactis IL1403 and L. lactis subsp. lactis NCDO 2118) in vitro. The supernatant and the L. lactis cells were co-cultured with intestinal epithelial cells (Caco-2 cells) in the presence of the proinflammatory cytokine IL1-. Only one strain, L. lactis NCDO 2118, was able to reduce the IL1--induced IL-8 secretion in Caco-2 cells, suggesting a potential anti-inflammatory effect for this strain. In vivo, this strain was administered for 4 days to C57BL/6 mice during a remission period between a first and second course of colitis induced by dextran sulfate sodium. L. lactis NCDO 2118 treatment resulted in a milder form of recurrent colitis than observed in mice administered medium during this same period. Administration was associated with early increase in IL-6 production and maintenance of IL-10 in colonic tissue. Mice fed with L. lactis NCDO 2118 had an increased number of regulatory T cells bearing surface TGF- in the form of latency-associated peptide (CD4+LAP+) in mesenteric lymph node and spleen as well as the number of tolerogenic dendritic cells. The results of this study allowed us to identify a new probiotic strain which may represent an alternative for IBD treatment.