Abstract Neutrophils provide a critical defense against pathogens in CF, but neutrophil responses may contribute to lung destruction and early death in CF. Neutrophil extracellular traps (NETs) kill microorganisms such as P. aeruginosa, and NET components are increased in CF sputum. There is a knowledge gap, however, regarding the signaling required for NETosis and how NETs impact functions of human airway epithelia relevant to CF. Our central hypothesis is that CF neutrophils have an increased propensity to form NETs and that NETs contribute to airway epithelial cell injury in death in CF. To test this hypothesis, we will first generate homozygous corrected CFTRdel508 iPS neutrophils using CRISPR/Cas genetic editing strategies for ?isogenic? comparisons of the impact of CFTR. This is a novel approach as human neutrophils cannot be genetically modified. Then in Aim 1, we will examine the regulation of NETosis and identify required pathways. We will also compare kinetics of NETosis and the composition of NETs between uncorrected and corrected CFTRdel508 iPS neutrophils. In Aim 2, we will determine the impact of NETosis on CF epithelial cell functions, including tight junction integrity, cytokine expression and cell death. Next, we will ascertain how NETosis alters the airway epithelial transcriptome, particularly expression of genes relevant to barrier function, cytokine signaling and cell death. The contribution of this work will be to identify and reveal the biology of novel, specific immunomodulatory targets in CF that could limit perpetuation of inflammation and prevent progressive lung destruction in CF. Completion of these Aims will also generate new insight into how NETs affect epithelial cell functions and the regulation of NETosis in human neutrophils, which is important for many common diseases involving NETs. Finally, completion of this project will provide crucial training to Dr. Hudock in genetic editing, airway cell biology and transcriptomics that will help her develop an independent career.