BackgroundMalnutrition affects the immune response, causing a decrease of defence mechanisms and making the host more susceptible to infections. Probiotics can reconstitute the intestinal mucosa and stimulate local and systemic immunity. The aim of this work was evaluate the effects of a probiotic fermented milk as a complement of a re-nutrition diet, on the recovery of the intestinal barrier, and mucosal and systemic immune functions in a murine model of non-severe protein-energy-malnutrition. Its potential protection against Salmonella enterica serovar Typhimurium (S. Typhimurium) infection was also analyzed.MethodsMice were undernourished and divided into 3 groups according to the dietary supplement received during re-nutrition (milk, probiotic fermented milk or its bacterial free supernatant) and compared to well-nourished and malnourished mice. They were sacrificed previous to the re-nutrition and 5 days post re-nutrition. The phagocytic activity of macrophages from spleen and peritoneum and the changes in the intestinal histology and microbiota were evaluated. Different immune cell populations and cytokine productions were analyzed in the small intestine tissues. The effect of the re-nutrition supplements on the systemic immunity using OVA antigen and against an infection with S. Typhimurium was also studied.ResultsProbiotic fermented milk was the most effective re-nutrition diet that improved the intestinal microbiota. Its administration also increased the number of IgA+ cells, macrophages and dendritic cells. The production of different cytokine (IFN-γ, TNF-α, IL-12) by these cells and the phagocytic activity in peritoneum and spleen was also increased. This re-nutrition diet also stimulated the systemic immune response against OVA antigen which was diminished after the malnutrition period and also improved the host response against S. Typhimurium, decreasing the spread of pathogenic bacteria to the liver and the spleen. The importance of the metabolites released during milk fermentation was also demonstrated through the analysis of the bacterial free supernatant obtained from the probiotic fermented milk, but the whole product showed the best effects in the parameters evaluated in this study.ConclusionsThe administration of probiotic fermented milk as a dietary supplement during the re-nutrition process in a murine immunodeficiency model by malnutrition could be a good adjuvant diet to improve the gut and systemic immune response for the protection against Salmonella infection.

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Protein -energy malnutrition (PEM) causes a significant impairment of the immune system, the thymus being one of the most affected organs. It has been demonstrated that the administration of probiotic fermented milk (PFM) recovered the intestinal barrier, histological alterations and mucosal and systemic immune functions in a non-severe malnutrition model using BALB/c mice. The aim of the present study was to evaluate, in the same model of malnutrition, the effect of a PFM added to a re-nutrition diet on the recovery of the thymus, analysing histological and functional alterations caused by malnutrition. Mice were undernourished and divided into three groups according to the dietary supplement received during re-nutrition: milk, PFM or its bacterial-free supernatant (BFS). They were compared with well-nourished and malnourished mice. PFM was the most effective re-nutrition supplement to improve the histology of the thymus, decreasing cellular apoptosis in this organ and recovering the percentage of CD4 þ /CD8 2 single-positive thymocytes. Immature doublepositive thymocytes were increased in the malnourished control (MC). The production of different cytokines in the thymus was increased in mice given PFM, compared with the mice that received other dietary supplements and MC. Mice given the BFS presented an improvement in the thymus similar to those that received milk. We demonstrated the importance of the whole PFM supplementation on the histological and functional recovery of the thymus in a non-severe PEM model.

We used water-soluble Chitosan obtained by Maillard reaction with glucosamine to microencapsulate soy genistein (Ge) and preserve its biological activity for oral administration. Release of Ge was pH dependent with a super Case II mechanism at pH 1.2 and an anomalous transport with non-Fickian kinetics at pH 6.8. Microencapsulated Ge retained its antioxidant properties in vitro and its daily administration to mice attenuated clinical signs of acute colitis, limited inflammatory reaction and reduced oxidative stress and tissue injury as well. Remarkably, after feeding microencapsulated Ge the production of IL-10 in colonic tissue was restored to levels of untreated controls. According to statistical multivariate analysis, this cytokine was the parameter with the highest influence on the inflammatory/oxidative status. Microencapsulation of Ge with derivatized Chitosan becomes an interesting alternative to develop therapeutic approaches for oxidative inflammatory diseases; our findings suggest that the soy isoflavone could be incorporated into any functional food for application in intestinal inflammation.