IMMUNOMODULATORY EFFECT OF Lactobacillus reuteri CRL 1098 DEPENDS ON RAFTS INTEGRITY: INTRACELLULAR SIGNALING PATHWAYS INVOLVED IN MODULATION OF CYTOKINE PRODUCTION

MECHOUD, M.; FONT DE VALDEZ, G.; RODRIGUEZ A.V.

Tucumán

Simposio; III Simposio Internacional de Bacterias Lácticas. II Encuentro Red BAL Argentina; 2009

CERELA

Unregulated cytokines production can have detrimental effects in human health. Excess as well as lack of production of cytokines from immune cells can result in a variaty of diseases. Thus, the control of cytokine production is important in regulating inflammatory reactions. Although various strains of probiotics induce anti-inflammatory effects in vitro and in vivo models, the mediators and mechanisms responsible for their effects have not yet been explored. Previous studies in our laboratory showed that L. reuteri CRL 1098 reduced the production of the pro-inflammatory cytokine TNF-á by human peripheral blood mononuclear cells (PBMC); this effect depended on integrity of cholesterol-enriched membrane called lipid rafts. TNF-á inhibition induced by L. reuteri was increased when rafts were disrupted by depleting cellular cholesterol with 10 mM methyl-â-cyclodextrin (MâCD) treatment. The aim of the present study was to investigate the effects of L. reuteri CRL 1098 on the production of the regulatory cytokine IL-10, in control and disrupted-rafts PBMC, to evaluate a net anti-inflammatory effect of the bacteria. Because of ERK1/2 and p38 kinases are key in the mitogen-activated protein kinase (MAPK) signaling pathways, which regulate a variety of cellular responses, we also investigated the effect of L. reuteri on the activity of these two kinases. The effect of L. reuteri CRL 1098 on IL-10 production by PBMC was evaluated by performing co-cultures of L. reuteri or its supernatant with control or disrupted-rafts PBMC at different times of incubation. IL-10 was detected in co-culture supernatants by ELISA. Kinases activities in the cell lysates were measured by ELISA. When L. reuteri CRL 1098 or its supernatant were incubated with PBMC, no significant modification on IL-10 production was observed after 4 and 6 h incubation, with respect to control or disrupted-rafts cells. Taking together these results, with the previous one of diminished TNF-á production, L. reuteri CRL 1098 exerts an anti-inflammatory effect on PBMC. L. reuteri supernatant produced no modifications on p38 activity neither in control or disrupted-rafts PBMC, indicating that this intracellular signaling pathway is not involved in the cellular response to L. reuteri. In contrast, ERK1/2 activity by PBMC was modified in co-cultures with L. reuteri supernatant, resulting in a diminished ERK1/2 activity. Therefore, this intracellular signaling pathway may be involved in the cellular response to L. reuteri CRL 1098. These results provide clues to understand the molecular mechanisms by which L. reuteri CRL 1098 produces the immunomodulatory effect on PBMC. Further studies are needed in order to understand how integrity of membrane lipid rafts influences cellular response.