Abstract
Rationale. Massive neutrophil recruitment and their secreted products are hallmarks of cystic fibrosis (CF) airway disease. We previously described that healthy neutrophils store key inflammasome components and release Il-1ß, found at high levels in CF airways (Bakele et al, 2014). Moreover, a recent study identified that inflammasomes, usually thought to be cytosolic multi-protein complexes, could be secreted and act as extracellular danger signal to amplify inflammation (Baroja-Mazo et al, 2014).
Aims. We attempt to characterize neutrophil inflammasome components and their release to evaluate the potential impact in CF lung disease.
Methods. We activated inflammasomes in isolated neutrophils and PBMCs (LPS +/- ATP or Nigericin) and also performed autocrine/paracrine stimulation to evaluate the impact on neutrophil/PBMC activity. Collected supernatants were analysed by western blot, enzymatic assays and ELISA to detect secreted inflammasome proteins and caspases' activity and Il-1ß levels. Finally, we assessed inflammasome activity in CF neutrophils and fluids, which we compared to healthy control samples.
Results. We demonstrated that human neutrophils release distinct oligomeric inflammasome-associated particles. These secreted complexes remained enzymatically active, interacted physically with caspase-1 and amplified the inflammatory response. In addition, we described inflammasome modulation in CF samples.
Conclusions. These findings support a model where neutrophils release inflammasome components as an endogenous danger signal and therefore amplify the inflammatory response, suggesting potential anti-inflammatory therapeutic strategies in CF.
- Copyright ©the authors 2016
