Immunomodulatory effects of different strains of Lactococcus lactis in DSS-induced colitis.

Inflammatory bowel diseases (IBD) are gastrointestinal disorders characterized by a breakdown in intestinal homeostasis by inflammatory immune responses to luminal antigens. Novel strategies for ameliorating IBD have been proposed in many studies using animal models. Our group has demonstrated that administration of Lactococcus lactis NCDO 2118 can improve clinical parameters of colitis induced by oral administration of dextran sulphate sodium (DSS). However, it is not clear whether other strains of L. lactis can yield the same effect. The objective of present study was to analyze the effects of three different L. lactis strains (NCDO2118, IL1403 and MG1363) in the development of DSS-induced colitis in C57BL/6 mice. Acute colitis was induced in C57/BL6 mice by the administration of 2% DSS during 7 consecutive days. Body weight loss and shortening of colon length were observed in DSS-treated mice, and none of L. lactis strains had an impact in these clinical signs of colitis. On the other hand, all strains improved the global macroscopical disease index and prevented goblet cells depletion as well as the increase of intestinal permeability. TNF-α production was reduced in gut mucosa of L. lactis DSS-treated mice indicating a modulation of a critical pro-inflammatory response by all strains tested. However, only L. lactis NCDO2118 and MG1363 induced a higher frequency of CD11c+CD11b-CD103+ tolerogenic dendritic cells in lymphoid organs of mice at steady state. We conclude that all tested strains of L. lactis improved the clinical scores and parameters of colitis, which confirm their anti-inflammatory properties in this model of colitis.

Probiotic Propionibacterium freudenreichii requires SlpB protein to mitigate mucositis induced by chemotherapy.

Propionibacterium freudenreichii CIRM-BIA 129 (P. freudenreichii wild type, WT) is a probiotic bacterium, which exerts immunomodulatory effects. This strain possesses extractable surface proteins, including SlpB, which are involved in anti-inflammatory effect and in adhesion to epithelial cells. We decided to investigate the impact of slpB gene mutation on immunomodulation in vitro and in vivo. In an in vitro assay, P. freudenreichii WT reduced expression of IL-8 (p<0.0001) and TNF-α (p<0.0001) cytokines in LPS-stimulated HT-29 cells. P. freudenreichii ΔslpB, lacking the SlpB protein, failed to do so. Subsequently, both strains were investigated in vivo in a 5-FU-induced mucositis mice model. Mucositis is a common side effect of cytotoxic chemotherapy with 5-FU, characterized by mucosal injury, inflammation, diarrhea, and weight loss. The WT strain prevented weight loss, reduced inflammation and consequently histopathological scores. Furthermore, it regulated key markers, including Claudin-1 (cld1, p<0.0005) and IL-17a (Il17a, p<0.0001) genes, as well as IL-12 (p<0.0001) and IL-1ß (p<0.0429) cytokines levels. Mutant strain displayed opposite regulatory effect on cld1 expression and on IL-12 levels. This work emphasizes the importance of SlpB in P. freudenreichii ability to reduce mucositis inflammation. It opens perspectives for the development of probiotic products to decrease side effects of chemotherapy using GRAS bacteria with immunomodulatory surface protein properties.

Dietary supplementation with omega-3 fatty acid attenuates 5-fluorouracil induced mucositis in mice.

BACKGROUND: Studies showed the positive effects of omega-3 fatty acid (n-3 FA) for the treatment of inflammatory bowel disease as it alleviated the symptoms and promoted better mucosal integrity. The objective of this study was to determine whether a diet with the addition of n-3 FA helps control the inflammation observed in 5-fluorouracil (5-FU) induced mucositis. METHODS: BALB/c mice were randomly divided into four groups as follows: 1: control (CTL), fed a standard chow diet; 2: CTL + n-3 FA - n-3 FA, fed a diet with n-3; 3: mucositis (MUC), fed a standard chow diet and subjected to mucositis; and 4: MUC+ n-3 FA, fed a diet with n-3 FA and subjected to mucositis. On the 8th day, the animals of the MUC and MUC + n-3 FA groups received an intraperitoneal injection of 300 mg/kg 5-FU for mucositis induction. After 24 h or 72 h, all mice were euthanized and evaluated for intestinal permeability, bacterial translocation, intestinal histology and apoptosis. RESULTS: Mice that received the diet with n-3 FA and a 5-FU injection showed less weight loss compared to the animals of the MUC group (p < 0.005). Decreased intestinal permeability and bacterial translocation were also observed in animals fed n-3 FA, and these mice underwent mucositis compared to the MUC group (p < 0.005). These data were associated with mucosal integrity and a reduced number of apoptotic cells in the ileum mucosa compared to the mice that received the control diet and 5-FU injection. CONCLUSION: Together, these results show that omega-3 fatty acid decreases the mucosal damage caused by 5-FU-induced mucositis.