CONICET | Buscador de Institutos y Recursos Humanos

Probiotic bacteria viability is a requirement to be considered for the selection of probiotics at the intestinal level. Aims: To compare the interaction of viable and non-viable probiotic bacteria with the intestine to determined the time of permanence in the gut and evaluate their behaviors in the intestinal mucosal immune system. Methodology: Viable and non-viable Lactobacillus casei (L.c), Lactobacillus acidophilus and Lactobacillus delbrueckii subsp. bulgaricus (L.b) were labeled with fluorescein isotiocyanate and administered to BALB/c mice by intragastric intubation. Samples of small intestine (SI) for L.c and L.B and large intestine (LI) for L.a, were extracted at different times, they included in paraffin and observed with fluorescent microscopy. L.c. was studied by transmission electronic microscopy (TEM) 10 minutes after its administration by using an antibody conjugated with colloidal gold. IgA+ cells and TNFa, IFNg, IL-12, IL-2, IL-10 and IL-4 cytokines were determined. Results: Antigens from viable L.c and L.b were observed in the Peyers patches (PP) at 5 minutes and the fluorescence was observed in lamina propria (LP) and PP until 72 hours after their administration. Antigens from L.a were observed in nodule and LP of LI. Fluorescent antigens from non-viable bacteria were observed in the base of intestine, a few in PP, nodule and LP. By TEM L.c was observed in the light of intestine or adhered to the villi; it was found bacterial antigen in the cytoplasm and lysosome of the enterocytes and in the intercellular spaces. Only viable bacteria stimulated the intestinal mucosal immune system. Conclusion: Bacteria viability is important to stimulate the mucosal immune response since the antigen promote in the inductor site of the immune system was greater than non-viable bacteria. The stimulus induced by viable bacteria warrants a good response on the intestinal mucosal immune system.

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