Potential immunomodulation of THP1 cells by Bifidobacterium bifidum strain CIDCA 5310.

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

Simposio; V Simposio Internacional de Bacterias Lácticas (SIBAL 2016).; 2016

Bifidobacteriaare a major component of the intestinal microbiota in humans. Due to theirbeneficial effects they are widely used as probiotics.Previous studies have shownthat differences in the surface of Bifidobacteriumstrains correlate with the pattern of interaction with epithelial cells. Owingto the central role of phagocytic cells in the innate immunity, the interactionbetween those cells and a selected strain, Bifidobacteriumbifidum CIDCA 5310 (hydrophobic, adherent to Caco-2 cells and autoaggregative)was studied.Monocytic THP1 cells were differentiatedwith 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.Tostudy the effect on the phagocytic activity of THP1 cells, bacteria were co-incubatedwith cells at MOI (multiplicity of infection) = 2, 10 or 20 bacteria/cell for1h at 37°C5% CO2. Phagocytosis wasevaluated by flow cytometry. For quenching of non-internalized bacteria, trypanblue 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 cellresponse (mean expression index) was evaluated by flow cytometry (labeling ofHLADr and TLR2), and intracellular localization was studied by labeling with LysotrackerDND-99 (lysosomal) or Transferrin Alexa594 (recycling endosomes,non-lysosomal). High expression of HLADr and TLR2 wasobserved 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 lasermicroscopy showed high percentages of localization in lysosomes (63.80 ± 0.42%) and low percentage in recycling endosomes (9.40 ± 1.83%).to evaluate the effectof CIDCA 5310 on the phagocytic activity, latex beads were used and uptakeindex (UI) = FL1(+) cells x mean fluorescence intensity, was measured. Heattreated (121°C - 15 min), UV treated (30 min) and untreated bacteria wereincubated with FITC-labeled latex beads (10 beads/monocyte) and THP1 cellsat MOI=10 bacteria/cell for 1h at 37°C5% CO2. Beads uptake was significantly increased (p<0.05) in thepresence of viable strain CIDCA 5310 MOI 10 (UI: 1807 ± 265.41) as comparedwith controls without bacteria (UI: 1007 ± 155.43). No effects were observed with heat orUV-killed bacteria. Our results show thatstrain CIDCA 5310 is able to modulate the activityof professional phagocytic cells.