SOLUBLE FACTORS OF L. reuteri CRL1098 MODULATE THE IMMUNE RESPONSE OF LPS-CHALLENGED RAW 264.7 CELLS

GRIET M; JUAREZ GE; FONT DE VALDEZ G; RODRIGUEZ AV

Mendoza

Congreso; 48th Annual Meeting Argentine Society for Biochemistry and Molecular Biology Research; 2012

SAIB

Soluble factors produced by probiotic bacteria such as lactobacilli can modulate the immune system responses. Previous studies in our laboratory showed the immunomodulatory capacity of Lactobacillus reuteri CRL 1098 and its supernatant on peripheral blood mononuclear cells. In this work we investigate the nature of the soluble factors responsible of immune modulation and its effect on lipopolysaccharide-treated RAW 264.7 cell line. L. reuteri survival and extracellular protein production in RPMI 1640 media were evaluated. The cytotoxicity of the bacteria culture supernatant was determined by MTT assay. The cytokines and nitric oxide (NO) produced by RAW 264.7 cells were measured by ELISA and Griess assay respectively. L. reuteri was able to survive 8 h at 37ºC in RPMI 1640 medium producing 12 µg/ml of protein at exponential growth phase. A dilution of 1:3 of the bacterial supernatant does not exert toxic effects on RAW 264.7 cells after 24 h of incubation at 37 ºC. A sub- cytotoxic dose of L. reuteri supernatant was pre-incubated with 1x106 cells before LPS challenge; results showed that the levels of TNF-α, IL-6 and NO were significantly lower (34, 65 and 58% respectively) than the LPS control cells, while IL-10 release was not affected. A peptide ‹10 kDa and ›3 kDa is responsible of immunomodulatory effect.