Abstract
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.
Highlights
Malnutrition affects the immune response, causing a decrease of defence mechanisms and making the host more susceptible to infections
probiotic fermented milk (PFM) or Bacterial free supernatant (BFS) supplementation on body weight, intestinal microbiota and translocation to the liver The results showed that the weight in the mice of Malnourished Control (MC) group decreased significantly compared to Well nourished control (WC) group
The animals that were re-nourished with milk, PFM or BFS showed body weight gain compared to MC group (Figure 2A)
Summary
Malnutrition affects the immune response, causing a decrease of defence mechanisms and making the host more susceptible to infections. Malnutrition is a systemic alteration, potentially reversible, caused by imbalance between the nutrient intake and energy requirements [1]. It is related mainly with decrease of the growth and development, reduced capacity for learning and depression of the immune system [2]. The function of the immune cells diminishes according to the severity of the malnutrition, which depends on the degree of nutrients imbalance, the interaction between nutrients and the age of the host [5]. The protein-energy malnutrition (PEM) is classified according to weight loss in: slight (10-25%), moderate (25%-39%) and severe (> 40%) Their consequences include loss of weight and delay in the growth, often associated with diverse clinical syndromes accompanied by mineral or vitamin deficiencies and immune deficiencies. The PEM can be reversed with an appropriate renutrition, which can restore all gastrointestinal and immune functions, regenerate the intestinal mucosa, and improve its microbiota
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