Signaling Pathways Involved in TNF-alpha Inhibition in PBMC by Lactobacillus reuteri

MECHOUD MA; MATEOS MV; SALVADOR GA; FONT DE VALDEZ G; RODRIGUEZ AV

Puerto Madryn

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2010

Lactobacillus strains have the capacity to modify cytokines production in different cells. However, the molecular mechanism involved in this effect is not yet fully understood. Previous investigations in our laboratory showed that L. reuteri CRL 1098 reduced TNF-α production in human peripheral blood mononuclear cells (PBMC), and this effect depended on membrane rafts integrity. The aim of this work was to investigate the signaling pathways involved in the decreased TNF-α production induced by L. reuteri CRL 1098 in PBMC. Using Western blot techniques it was demonstrated that when PBMC were co-incubated with L. reuteri cell-free supernatant, Lck protein migrated from rafts to non-rafts regions of the membrane. Also, different signaling proteins were modified after the incubation with the bacterial supernatant: increased levels of PI3K, pERK ½, and p-p38 were observed. Citoplasmic fraction of p65 NF-κB decreased while nuclear fraction of p65 NF-κB increased, indicating that this transcription factor could be partially responsible for TNF-α diminution. We postulate that L. reuteri could interfere with the ability of NF-kB to bind to DNA targets. These results provide clues to understand the mechanisms by which L. reuteri reduces TNF-α production in PBMC and demonstrate for the first time, interaction between non-pathogenic bacteria with membrane rafts.