Changes in Sputum Viscoelastic Properties and Airway Inflammation in Primary Ciliary Dyskinesia are Comparable to Cystic Fibrosis on Elexacaftor/Tezacaftor/Ivacaftor Therapy

Background: Primary ciliary dyskinesia (PCD) and cystic fibrosis (CF) are muco-obstructive lung diseases that are both caused by genetically determined defects in mucociliary clearance, which triggers a cascade that evolves into a ‘vicious vortex’ of airway mucus plugging, chronic polymicrobial infection and neutrophilic inflammation. However, knowledge on the relative severity of airway mucus dysfunction and chronic inflammation remains limited. The aim of this study was therefore to compare sputum viscoelastic properties, inflammation markers and the proteome between patients with PCD and patients with CF before and under elexacaftor/tezacaftor/ivacaftor (ETI) therapy. Methods: We compared sputum rheology, inflammation markers and the proteome in 42 clinically stable adolescent and adult patients with PCD, 40 patients with CF with at least one F508del allele, aged 12 years and older, before (baseline) and 3 months after initiation of ETI, and 15 age-matched healthy controls. Results: The elastic modulus (G’) and viscous modulus (G’’) of PCD sputum was increased compared to healthy controls ( P