Inflammasome-mediated IL-1ß production in humans with cystic fibrosis.

BACKGROUND: Inflammation and infection are major determinants of disease severity and consequently, the quality of life and outcome for patients with cystic fibrosis (CF). Interleukin-1 beta (IL-1ß) is a key inflammatory mediator. Secretion of biologically active IL-1ß involves inflammasome-mediated processing. Little is known about the contribution of IL-1ß and the inflammasomes in CF inflammatory disease. This study examines inflammasome-mediated IL-1ß production in CF bronchial epithelial cell lines and human patients with CF. RESULTS: Bronchial epithelial cell lines were found to produce negligible amounts of basal or stimulated IL-1ß compared to hematopoeitic cells and they did not significantly upregulate caspase-1 activity upon inflammasome stimulation. In contrast, peripheral blood mononuclear cells (PBMCs) from both CF and healthy control subjects produced large amounts of IL-1ß and strongly upregulated caspase-1 activity upon inflammasome stimulation. PBMCs from CF patients and controls displayed similar levels of caspase-1 activation and IL-1ß production when stimulated with inflammasome activators. This IL-1ß production was dependent on NF-κB activity and could be enhanced by priming with LPS. Finally, chemical inhibition of CFTR activity in control PBMCs and THP-1 cells did not significantly alter IL-1ß or IL-8 production in response to P. aeruginosa. CONCLUSION: Hematopoeitic cells appear to be the predominant source of inflammasome-induced pro-inflammatory IL-1ß in CF. PBMCs derived from CF subjects display preserved inflammasome activation and IL-1ß secretion in response to the major CF pathogen Pseudomonas aeruginosa. However, our data do not support the hypothesis that increased IL-1ß production in CF subjects is due to an intrinsic increase in NF-κB activity through loss of CFTR function.