IL-1b Production in Cystic Fibrosis Figure 4. PBMCs from CF patients and controls show similar increases in caspase-1 activity upon inflammasome activation. PBMCs from CF patients (n = 6) and healthy controls (n = 6) were primed with LPS (10 ng/ml) for 5 hours prior to stimulation with ATP (5 mM) for 1 hour or Poly(dA:dT) (1 mg/ml) for 3 hours. PBMCs were stimulated with P. aeruginosa strain PAO1 for 3 hours. A representative histogram of the % caspase-1- active cells is shown in (A) with the averaged values shown in (B). doi:10.1371/journal.pone.0037689.g004 were performed alongside inhibition of CFTR activity by CFTRinh172 in response to PAO1 at 4 hours after stimulation (Fig. 7a). Our results indicate that Bay11-7082 prevents produc- tion of pro-IL-1b whereas CFTRinh172 does not seem to affect it. This was further corroborated by the ability Bay11-7082 to inhibit IkBa degradation at 0.5, 1, and 1.5 hours post PAO1 stimulation (Fig. 7b). Disruption of CFTR activity does not increase IL-1b production in PBMCs and THP-1 cells A previous study has indicated a role for chloride ion concentration in suppression of NLRP3 inflammasome activation [34]. To determine whether CFTR dysfunction alters IL-1b production, THP-1 cells and PBMCs from CF patients and healthy controls were treated with the CFTR inhibitor, CFTRinh172, prior to simulation with live P. aeruginosa. Treatment with CFTRinh172 did not alter IL-1b or IL-8 production in control subjects or CF patients (Fig. 8a–b). Similarly, IL-1b production was not different in monocyte-derived macrophages or THP-1 reporter cells treated with CFTRinh172 (Fig. 8c–d). IL-8 (Fig. 8e) and NF-kB activity (Fig. 8f) were also unchanged in CFTRinh172-treated THP-1 reporter cells. Discussion Levels of IL-1b are increased in the BALF of CF patients but the cellular source of this cytokine and its production in the context of targeted inflammasome activation are still unclear. We first studied airway epithelial cells due to their role in barrier function, proximity to infection, and ability to produce high levels of pro-inflammatory cytokines. However, we found that bronchial PLoS ONE | www.plosone.org 5 May 2012 | Volume 7 | Issue 5 | e37689