CIDCA   05380
CENTRO DE INVESTIGACION Y DESARROLLO EN CRIOTECNOLOGIA DE ALIMENTOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Study of the immunomodulatory effect of kefiran on THP1 cells infected with Bacillus cereus.
Autor/es:
LARROUYET, M.L; MINNAARD, J; ABRAHAM, A.G. AND PÉREZ, P
Lugar:
Tucuman
Reunión:
Simposio; IV International Symposium on Lactic Acid Bacteria. Food, Health and Applications.; 2013
Resumen:
Kefiran, an exopolysaccharide produce by kefir granules, is a neutral, ramified glucogalactane, non-digestible, water-soluble, with demonstrated ability to modulate immune response both in vitro and in vivo. The interaction with phagocytic cells could contribute to gain further insight on the immunomodulatory effect of kefiran. The aim of this work was to assess the effect of kefiran on the expression of HLA-DR in a human monocytic cell line (THP-1 cells). THP-1 cells were incubated with phorbol myristate acetate (PMA) 200 nM, kefiran 800 mg/L or vegetative cells of Bacillus cereus B10502 (20 bacteria/THP-1 cell ? 100 µg/ml chloranphenicol). Expression of HLA-DR was assessed by flow cytometry. Interaction between bacteria and THP-1 cells was studied by flow cytometry by labeling bacteria with CFDA-SE. The presence of kefiran leads to modification in the pattern of interaction between bacteria and monocytes as evidenced by the presence of two sub-populations showing different levels of green fluorescence (FL1-H). Cell activation was evidenced by morphological changes (increase of FSC and SSC values) as well as by the increase of the ratio of cells expressing HLA-DR. Indeed, whereas the ratio of HLA-DR (+) cells was 3.4 % after PMA stimulation these values increased to 6.4 % when cells were incubated with both PMA and kefiran. In another series of experiments where cells stimulated with PMA were incubated with B. cereus; the presence of kefiran increases the percentage of HLA-DR (+) cells from 15.3 to 21.8 %. Interestingly, kefiran was able to increase the ratio of HLA-DR (+) cells even when incubations were conducted with B. cereus in the absence of PMA (values of 3.1 and 4.0 % for B. cereus and B. cereus + kefiran, respectively). To determine whether the effects are related to a general property of polysaccharides, the same experiments were performed with dextran of high molecular weight. Noteworthy, dextran did not modify the expression of HLA-DR in THP1 cells stimulated with B. cereus. Results of the present study demonstrate that kefiran is able to modify the interaction between B. cereus and cultured human phagocytic cells. These changes lead to the modulation of the response of phagocytic cells to chemical and bacterial stimuli. These findings provide further insight on the mechanisms responsible of the biological effects of kefiran as a functional ingredient of foods.