CFTR modulators exert subset-specific phenotype remodeling on circulating neutrophils in cystic fibrosis

A key aspect of cystic fibrosis pathophysiology is the significant role played by neutrophils, central to the inflammatory response in cystic fibrosis airways. Neutrophil-dominated inflammation greatly influences clinical outcomes, including airway damage and lung function decline. People with cystic fibrosis have an increase in circulating neutrophils that exhibit numerous functional and phenotypic abnormalities. We used spectral flow cytometry to delineate the expression of 24 cell surface markers on neutrophils from 24 healthy donors and 45 adults with cystic fibrosis, before and after elexacaftor-tezacaftor-ivacaftor treatment. This comprehensive analysis examined phenotypic markers associated with fundamental neutrophil functions, including differentiation, maturity, activation, antimicrobial activities (degranulation, pathogen sensing and chemotaxis), metabolism, and immunomodulation. Prior to treatment, neutrophils from adults with cystic fibrosis displayed a phenotype suggestive of immune activation and metabolic aberration. Treatment with elexacaftor-tezacaftor-ivacaftor normalized a FPR1high/CXCR2high subset, an observation consistent with enhanced pathogen-sensing capacity. The treatment, however, failed to restore fully normal phenotypes in cystic fibrosis neutrophils but rather induced the modulation of a PD-L1high/CD114high/GLUT-1high subset of mature neutrophils with an increased expression of PD-L1 and adhesion molecules such as CD11c and CD11b. Taken together, our data reveal a specific immunophenotypic signature of neutrophils in cystic fibrosis that is further modified by treatment with elexacaftor-tezacaftor-ivacaftor, suggesting the opportunity for developing adjunctive therapies to enhance beneficial antimicrobial subsets while simultaneously mitigating immunosuppressive phenotypes, thereby opening new perspectives for immune modulation in cystic fibrosis treatment.