Biological signals induced by probiotics and commensal bacteria on the gut immune system

PERDIGÓN GABRIELA; MALDONADO GALDEANO, CAROLINA

Conferencia; International Conference and Exhibition on Probiotics; 2012

The intestinal ecosystem is a very complex network of interactions between prokaryotic ? eukaryotic or eukaryotic ? 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 mucosa responsible of the mucosal immune response. This microbiota is very stable and avoids the colonization of pathogenic bacteria (barrier effect) Probiotics bacteria and functional food can influence not only the microbiota, favoring the growth of beneficial microorganisms, but also the mucosal immune system associated to the gut. The improvement of the immune status of the host is one of the beneficial properties attributed to the probiotics. Previous results in our laboratory using mouse as experimental model, showed that the effect induced by a probiotic strain Lactobacillus casei CRL 431was through the innate immunity. This bacterium is able to interact with the epithelial and immune cells, increase IgA secreting cells, cytokines and receptors as CD206 and TLR2 These Studies were performed comparatively with commensal bacteria We determined the effect of non pathogenic Gram (+), bacteria and a Gram(+) probiotic strain on the inductor site (PP) and effector site (lamina propria) of the intestine.We demonstrated that commensal bacteria were able to induce an immunostimulation less than those obtained with probiotic bacteria and that the lipoteichoic acid (LTA) is not the only structure implicated in the immunostimulation. To understand these differences observed in the gut: we analyzed comparatively the signals induced by probiotic and commensal bacteria to activate the transcriptional factors NFAT (through the calcineurine enzyme), NFkB and TLR-9. Both probiotic and commensal bacteria activated the NFAT, but TLR9 was only increased by probiotic and NFkB was more activated by probiotic than commensal bacteria. Increases of co-stimulatory molecules expression by probiotic administration were also observed. We studied the importance in the signals induced through TLRs in knockout animals for TLRs. We demonstrated that the main metabolic via of signal for probiotics to activate the Immune System is through TLR, different to commensal bacteria that induce a slight stimulation for this way. Conclusions: Probiotics and commensal bacteria activate NFkB to promote the production of certain cytokines, as well as.NFAT and TLR9 to stimulate the mucosal response., however the level of activation was more effective for probiotic than commensal bacteria.The most important via of signals used by probiotic is from TLRs.