Potential Immunomodulation of THP-1 Cells by Bifidobacterium bifidum strain CIDCA 5310

ASSAD, SABRINA; PÉREZ, PABLO F.; ROLNY, IVANNA S; MINNAARD, JESSICA

San Miguel de Tucumán

Simposio; V International Symposium on Lactic Acid Bacteria. Benefitting from Lactic Acid Bacteria Progress in Health and Food; 2016

Bifidobacteria are a major component of the intestinal microbiota in humans. Due to their beneficial effects they are widely used as probiotics.Previous studies have shown that differences in the surface of Bifidobacterium strains correlate with the pattern of interaction with epithelial cells. Owing to the central role of phagocytic cells in the innate immunity, the interaction between those cells and a selected strain, Bifidobacterium bifidum CIDCA 5310 (hydrophobic, adherent to Caco-2 cells and autoaggregative) was studied.Monocytic THP1 cells were differentiated with phorbol myristate acetate in DMEM (10% fetal bovine serum) for 3 days at 37°C in 5% CO2. Strain CIDCA 5310 was cultured (48h; 37°C) in MRS broth in anaerobic conditions.To study the effect on the phagocytic activity of THP1 cells, bacteria were co-incubated with cells at MOI (multiplicity of infection) = 2, 10 or 20 bacteria/cell for 1h at 37°C 5% CO2. Phagocytosis was evaluated by flow cytometry. For quenching of non-internalized bacteria, trypan blue was used. High percentages of phagocytosis were found for MOI 2 (655.10 ± 88.85), 10 (2224.08 ± 463.82) and 20 (5195.54 ± 126.76).At MOI 10 cell response (mean expression index) was evaluated by flow cytometry (labeling of HLADr and TLR2), and intracellular localization was studied by labeling with Lysotracker DND-99 (lysosomal) or Transferrin Alexa594 (recycling endosomes, non-lysosomal). High expression of HLADr and TLR2 was observed when cells were incubated overnight with strain CIDCA 5310, 5806.90 ± 100.11 (HLADr) and 1832.05 ± 268.10 (TLR2). Values for untreated controls were 3721.48 ± 460.93 (HLADr) and 1401.21 ± 4.30 (TLR2). Confocal laser microscopy showed high percentages of localization in lysosomes (63.80 ± 0.42%) and low percentage in recycling endosomes (9.40 ± 1.83%).to evaluate the effect of CIDCA 5310 on the phagocytic activity, latex beads were used and uptake index (UI) = FL1(+) cells x mean fluorescence intensity, was measured. Heat treated (121°C - 15 min), UV treated (30 min) and untreated bacteria were incubated with FITC-labeled latex beads (10 beads/monocyte) and THP1 cells at MOI=10 bacteria/cell for 1h at 37°C 5% CO2. Beads uptake was significantly increased (p