Figure 5. PGE2 augmentation limits bacterial growth but increases pro-inflammatory cytokine secretion and cellular toxicity.
(A) Addition of exogenous PGE2 suppresses Mtb growth in microspheres in a dose-dependent manner. Mtb-infected PBMCs (black line), 0.2 µg/ml PGE2 (green line), 2 µg/ml PGE2 (red line), 20 µg/ml PGE2 (blue line). (B) Colony counts of microspheres decapsulated at day 24 and then plated on Middlebrook 7H11 agar correlate with luminescence. (C, D and E) PGE2 increases secretion of IL-6 and IL-8, but significantly decreases IFN-γ secretion, from Mtb-infected microspheres. (F) Cellular toxicity is increased in PGE2 treated microspheres at day 3, analyzed by LDH release, and (G) total cell viability was reduced at day 7, analyzed by CytoTox-Glo assay. (H) PGE2 reduces caspase 3/7 activity at day 7. *p<0.05, **p<0.01, ***p<0.001.