DIFFERENTIAL INTERACTION OF TWO STRAINS OF BIFIDOBACTERIUM WITH HUMAN DENDRITIC CELLS

ASSAD, SABRINA; PAGOTTO, R; MINNAARD J; PEREZ PF; BOLLATI-FOGOLIN M

Congreso; XIII Congreso Argentino de Microbiología General; 2018

Microorganisms belonging to the genus Bifidobacterium have demonstrated health promoting effects (probiotic) in humans. Modulation of host defense response and immunoregulation are some of the proposed mechanisms that involve crosstalk between relevant cell populations such as intestinal epithelial cells (IEC) and dendritic cells (DC). Previous studies showed a strain dependent interaction of bifidobacteria with cultured phagocytic cells (THP-1) demonstrating a higher internalization of Bifidobacterium bifidum CIDCA 5310 when compared with B. adolescentis CIDCA 5317. Also, bifidobacteria stimulation leads to the expression of HLADR and TLR2 on THP-1 cells. The present study focus on the effect of these strains on the phagocytic activity of human DC and activation in cocultures with IEC. Bacteria were cultured (24 h; 37°C) in MRS broth in anaerobic conditions. For DC activation studies, HT-29-NF-κB-hrGFP reporter cells, cultured on a transwell filter (3μm pore diameter), and monocyte-derived differentiated DC were cultured in RPMI 1640 + 10% (v/v) foetal bovine serum (48 h, 37°C, 5% CO2). Inserts were transferred to plates containing DC and the apical surface was stimulated with 30 bacteria per cell (18 h at 37°C, 5% CO2). Cell response was evaluated by flow cytometry (MFI: mean fluorescence intensity of HLADR, CD86, CD80 and CD40 markers). For the activation of NF-κB, green fluorescent protein (GFP, %) was assessed in HT-29-NF-κB-hrGFP. Lipopolysaccharide from E. coli (LPS, 0.5 μg/ml) was used as positive control. DC phagocytic activity of FITC-labeled bacteria was evaluated by flow cytometry. Trypan blue (TB) was used for quenching non-internalized bacteria.Co-stimulatory molecules expression showed that bifidobacteria modulated HLA-DR and CD86. B. bifidum CIDCA 5310 strain increased significantly (P