CSE inhibition prevents LPS-induced IL-12 synthesis by MoDCs and monocytes. (A) CSE inhibition does not prevent LPS-induced up-regulation of maturation markers. Human monocytes were differentiated for 5 days into MoDCs with IL-4 and GM-CSF, and maturation was induced by LPS for 24 hours with or without PPG (32mM) and analyzed by flow cytometry after gating on viable cells. Black bars represent LPS; and white bars, LPS + PPG. Data are from 3 independent experiments and are the mean ± SEM relative expression of indicated markers compared with immature MoDCs (gray bars). (B) Immature MoDCs were generated as in panel A, and maturation was induced by LPS for 24 hours, in the presence of increasing doses of PPG, after which time supernatants were analyzed by ELISA. Results represent the mean ± SEM relative cytokine secretion compared with secretion without PPG. ● represents IL-12p70 (n = 5); ■, IL-12-p40 (n = 10); ▴, IL-10 (n = 4); and itrif], IL-6 (n = 2) secretion. In these experiments, according to individual donors, IL-12p40 synthesis by LPS-treated MoDCs ranged from 7735 to 44 800 pg/mL, IL-12p70 from 481 to 31 300 pg/mL, IL-6 from 5185 to 14 600 pg/mL, and IL-10 from 5238 to 21 300 pg/mL. **P < .01. (C) Monocytes were differentiated during 4 days with IL-4 and GM-CSF, and transfected with an siRNA specific for CSE (siCSE) or a scrambled negative control siRNA (siC) for 24 hours Then, transfected cells were matured by LPS challenge for 24 hours, and supernatants were analyzed. Results represent the relative secretion of IL-12p40 compared with siC⁻ and are the mean ± SEM of 4 independent experiments. In these experiments, LPS-treated MoDCs from the SiC- group secreted IL-12p40 from 270 pg/mL to 17 300 pg/mL. **P < .01. (D) Maturation of MoDCs was induced by LPS challenge for 24 hours in the presence of buffer (LPS), GYY4137 (GYY; H₂S donor; 47μM), PPG, or combination of PPG (32mM) and GYY4137 (PPG + GYY), and supernatants were analyzed. Results represent the secretion mean ± SD of IL-12p40 (pg/mL) of duplicates from 1 experiment representative of 3 independent experiments. (E) Same experiment as in panel D, but SAS, a X_c⁻ cystine transporter inhibitor, was added (500μM). Black bars represent IL-12p40; and white bars, IL-12p70. Results represent the mean ± SEM relative secretion of 4 independent experiments. In these experiments, LPS-treated MoDCs secreted IL-12p40 from 14 800 to 43 700 pg/mL and IL-12p70 from 480 to 21 300 pg/mL. *P < .05. (F) Same experiment as in panels D and E, in THP-1 cells. Results represent the mean ± SEM of 2 independent experiments. In these experiments, LPS-treated THP-1 secreted IL-12p40 from 231 to 370 pg/mL