Specific Inhibition of the NLRP3 Inflammasome as an Antiinflammatory Strategy in Cystic Fibrosis

Abstract

Abstract Rationale Cystic fibrosis (CF) pulmonary disease is characterized by chronic infection with Pseudomonas aeruginosa and sustained neutrophil-dominant inflammation. The lack of effective antiinflammatory therapies for people with CF (PWCF) represents a significant challenge. Objectives To identify altered immunometabolism in the CF neutrophil and investigate the feasibility of specific inhibition of the NLRP3 (NOD-, LRR-, and pyrin domain–containing protein 3) inflammasome as a CF antiinflammatory strategy in vivo. Methods Key markers of increased aerobic glycolysis, known as a Warburg effect, including cytosolic PKM2 (pyruvate kinase M2), phosphorylated PKM2, succinate, HIF-1α (hypoxia-inducible factor-1α), lactate, and the 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 control subjects (n = 12), PWCF (n = 16), and PWCF after double-lung transplantation (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. Measurements and Main Results CF neutrophils display increased aerobic glycolysis in the systemic circulation. This effect is driven by low-level endotoxemia, unaffected by CFTR (cystic fibrosis transmembrane conductance regulator) modulation, and resolves after transplant. The increased pro–IL-1β produced is processed to its mature active form in the LPS-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). Conclusions CF neutrophil immunometabolism is altered in response to inflammation. NLRP3 inflammasome inhibition may have an antiinflammatory and anti-infective role in CF.