Specific Inhibition of the NLRP3 Inflammasome as an Anti-Inflammatory Strategy in Cystic Fibrosis.

Abstract

Cystic fibrosis (CF) pulmonary disease is characterized by chronic infection with Pseudomonas aeruginosa and sustained neutrophil-dominant inflammation. The lack of effective anti-inflammatory therapies for people with CF (PWCF) represents a significant challenge.To identify altered immunometabolism in the CF neutrophil, and investigate the feasibility of specific inhibition of the NLR family, pyrin domain-containing protein 3 (NLRP3) inflammasome as a CF anti-inflammatory strategy in vivo.Key markers of increased aerobic glycolysis, known as a Warburg effect, including cytosolic pyruvate kinase M2 (PKM2), phosphorylated PKM2, succinate, HIF-1α, lactate and the interleukin (IL)-1β precursor pro-IL-1β, as well as caspase-1 activity and processing of pro-IL-1β to IL-1β by the NLRP3 inflammasome, were measured in neutrophils from blood and airway secretions from healthy controls (n=12), PWCF (n=16) and PWCF post-double-lung transplant (n=6). The effects of specific inhibition of NLRP3 on airway inflammation and bacterial clearance in a murine CF model were subsequently assessed in vivo.CF neutrophils display increased aerobic glycolysis in the systemic circulation. This effect is driven by low-level endotoxemia, unaffected by CFTR modulation, and resolves post-transplant. The increased pro-IL-1β produced is processed to its mature active form in the lipopolysaccharide-rich CF lung by the NLRP3 inflammasome via caspase-1. Specific NLRP3 inhibition in vivo with MCC950 inhibited IL-1β in the lungs of CF mice (P<0.0001), resulting in significantly reduced airway inflammation and improved Pseudomonas clearance (P<0.0001).CF neutrophil immunometabolism is altered in response to inflammation. NLRP3 inflammasome inhibition may have an anti-inflammatory and anti-infective role in CF.