Immune response of non-pathogenic Gram(+) and Gram(-) bacteria in inductive sites of the intestinal mucosa. Study of the pathway of signaling involved.

DOGI, C.A; WEILL, F; LEONI, J; PERDIGÓN, G.

IMMUNOBIOLOGY.

ELSEVIER GMBH

Año: 2010 vol. 215 p. 60 - 69

0171-2985

The gutassociated lymphoidtissue(GALT) is anatomical and functionally divided ininductive andeffectors sites. In previous Works we demonstrated thatnon-pathogenic bacteria withprobiotic characteristics canimprove the gut mucosal immune system,with an increase in the number of IgA and cytokines producing cells in the effector site of the intestine. In the present work we studied the effect of non-pathogenic Gram(+),Gram(-) bacteria and a Gram(+)  probiotic strain on the inductor site(PP) after the oral administration to BALB/c mice. We alsos tudied some signals induced by the assayed strain in the effectors site,such as the enzyme calcineurin and TLR-9 asaway to  understand the mechanisms induced in such bacterial stimulation.The implicance of the lipoteichoic acid (LTA) in the immunostimulation was analyzed. All strains increased thenumber of IFN-g and TNF-a(+) cells,but not of IL-10(+) cells in the total population of PP.The release of IFN-g and TNF-a was only induced by LPS stimulation.All assayed strains increased the number of calcineurin(+) cells, while only Gram(+) strains increased the number of TLR-9(+) cells. The immuno stimulatory properties of the purified LTA from Gram(+) strains was evaluated on a monocyte–macrophage U937 cell line.These cells showed capacity to releaseTNF-a and IL-10 in response to all LTA assayed in a dose-dependen tway. Gram(+) strains induced signals through the calcineurin enzyme able to  activate the transcriptional factor NFAT and throughTLR-9. The LTA molecule fromGram(+) strains would not be the only structure involved in the immunostimulatory properties observed,specially for the probiotic strain.