Figure 7. EVs enhance DC phagocytosis of bacteria.

1×10⁵ DCs were co-incubated with 2.5×10⁶ pHrodo-labeled B. breve NutRes 200, L. rhamnosus NutRes 1 or pHrodo Red Dextran as a control for DC phagocytic capacity at 37°C. (A) Medium was supplemented with increasing concentrations of HS, HS-D or HS-D reconstituted with the serum EV fraction (HS-recon). After 3H, DCs were collected and analyzed for fluorescence using flow cytometery. Degree of phagocytosis is determined as an increase in mean fluorescence index (MFI). EV depletion significantly reduced B. breve phagocytosis at 1 and 5% supplementation compared to HS (^*P<0.05). Phagocytosis of L. rhamnosus was reduced to background level (dotted line) upon EV depletion at 1%, 5% and 10% supplementation compared to HS (^**P<0.01, ^*P<0.05, ^*P<0.05, respectively). Reconstitution of HS-D with EVs normalized the phagocytic response compared to HS. Data are represented as mean ± SEM n = 2. Experiment was repeated at least twice with similar results. (B) Medium was supplemented with 5% of the indicated serum fractions and 30 µg/ml pHrodo Red Dextran. After 1 hour DCs were harvested and MFI determined. Medium as well as all serum fractions increased dextran uptake compared to DCs alone (DC). No differences in dextran uptake could be measured between medium and the different serum fractions. Data are represented as mean ± SEM n = 4.