INVESTIGADORES
PEREZ Pablo Fernando
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. F.
Reunión:
Simposio; IV Simposio Internacional de Bacterias Lácticas.; 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 lead
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.