Centro de referencia para lactobacilos, Universidad Nacional de Tucumán, Tucumán, Argentina
The intestinal ecosystem is a very complex network of interactions between prokaryotic and eukaryotic cells. In this microenvironment coexist in a perfect equilibrium, a large number of bacteria (1010-1011g/feces) and the immune cells associated to the intestinal mucosa. The characteristics of the intestinal ecosystem avoid the colonization for pathogens (barrier effect) In other hand, probiotic bacteria strains or functional foods, can influence the microbiota, favoring the growth of beneficial microorganisms, and the mucosal immune response associated to the gut. Probiotics or fermented milks (that contain live microorganisms with probiotic characteristics) by definition can exert a beneficial effect in addition to its nutritional properties. One of the important questions is how we must select the right probiotic strain to improve the Immune System ,and what biomarker/s should be selected?. Taking into account these considerations, and the fact that there are many reports about the beneficial effect exerted of some probiotic strains; we analyzed the effect of two probiotic strain by in vivo, ex vivo and in vitro assay comparatively with a commensal strain, and a probiotic fermented milk (PFM) in an experimental model using healthy mouse We tried to find a special behavior of the strains assayed or the PFM, in order to select an immunological marker. We established, that the most important biomarkers as predictive for beneficial effect on the mucosal and systemic immune response is the anti-inflammatory capacity observed with the probiotic strains assayed and the PFM. We also demonstrated that the main immune response induced is the Innate Immune response (by activation of macrophage and dendritic cells) and that the increase observed in the systemic response against a proteic antigen,was through the activation of the immune cells to induce chemokine expression or release, in distant sites from the gut, as they are the spleen cells. One of the most important fact that we demonstrated is, that the increase in the number of IgA producing cells in the small intestine would not be the proper biomarker, due to that this increase is also mediated for the oral administration of commensal bacteria. The role of the soluble fraction, free of bacteria from the PFM assayed, in the capacity to activate the gut immune system, was also analyzed. We demonstrated the importance of this matrix and the fermentation process, in the immunomodulation of the gut immune system. These previous results led us to analyze comparatively, the effect of the whole probiotic strains assayed with the cell wall purified of each one on intestinal epithelia cell (IEC) .We observed by electronic microscopy and staining determination that one of the strain assayed had polysaccharide structure in its cell wall. We observed the importance of this polysaccharide fraction in the activation to the IEC and in the signals to the immune cells when we stimulated with the cell wall purified, in comparison with the whole bacterium. The behavior of the cell wall of the other probiotic strain assayed was similar to the whole bacterium. According these results we believe that the key cell as parameter to establish an immunological biomarker is the intestinal epithelial cell. References: Chaves S, Perdigón G, de Moreno A. Yoghurt consumption prevents the intestinal inflammation recurrence and regulates the immune cells implicated in the acute inflammatory process. J. Food Prot 2011; 74(5):801-11. Maldonado Galdeano C, Novotny Nuñez I ,de Moreno de LeBlan A, Carmuega E, Weill R, Perdigon G. Impact of a probiotic fermented milk in the gut ecosystem and in the systemic immunity using a nonsevere protein-energy-malnutrition model in mice”. Gastroenterology 2011;11(1):64 (http://www.ncbi.nlm.nih.gov/ pubmed/21615956. Fermented or unfermented milk using bifidobacterium animalis subsp. lactis HN019: Technological approach determines the probiotic modulation of mucosal cellular immunity. Bogsan, L. Ferreira, C. Maldonado, G. Perdigon, S.R. Almeida, M.N. Oliveira. ISSN: 0963-9969. Food Research International 2014;64: 283-288. G. Stimulation of innate immune cells induced by probiotics: participation of toll- like receptors. Maldonado Galdeano C., Lemme Dumit J.M., Thieblemont N., Carmuega E. and Perdigon G. Clin Cell Immunol 2015; 6:1. Maldonado Galdeano C, Novotny Nunez I, Carmuega E, de Moreno de LeBlanc A, Perdigón G. Role of probiotics and functional foods in health: gut immune stimulation by two probiotic strains and a potential probiotic yoghurt. Endoc Metab Immune Disord Drug Targets 2015; 15(1): 37-45.