Bifidobacteria increase phagocytic activity of THP-1 cells.

ASSAD, S. E; ROLNY, I. S; MINNAARD, J Y PÉREZ, P. F.

Congreso; XI Congreso Argentino de Microbiologia General (SAMIGE); 2015

Bifidobacteria are potentially probiotic bacteria which colonize the intestine of infants and adults. One of the key steps in the immunomodulatory effects is the interaction of bacteria with phagocytic cells. Previous results showed that the interaction of bifidobacteria with cultured phagocytic cells is strain dependent and higher ratio of phagocytic cells internalizes Bifidobacterium bifidum CIDCA 5310 as compared with B. adolescentis CIDCA 5317. The present study aimed at evaluating the effect of these strains on the phagocytic activity of THP1 cells by using latex beads as a model of abiotic particles. Monocytic THP1 cells were differentiated with phorbol myristate acetate (PMA) 200 nm in DMEM (10% fetal bovine serum) for 3 days at 37°C in 5% CO2 atmosphere. B. bifidum CIDCA 5310 (hydrophobic strain) and B. adolescentis CIDCA 5317 (non-hydrophobic strain) were cultured (48h; 37°C) in MRS broth in anaerobic conditions. Heat treated (121°C - 15 min), UV treated (30 min) and untreated bacteria were suspended in DMEM and incubated with FITC-labeled latex beads and THP1 cells at multiplicity of infection (MOI)=10 bacteria/cell for 1h at 37°C 5% CO2. Different beads/monocyte ratios (BM) were used. Association (phagocytosed + adhered beads) and phagocytosis were evaluated by flow cytometry by means of the uptake index (UI) = FL1(+) cells x mean fluorescence intensity. For quenching of non-internalized beads trypan blue was used. In addition, confocal laser microscopy was performed to gain further insight on the interaction of beads with THP1 cells. Beads uptake at BM=10 was significantly increased (p