Allergic airway disease is known to cause significant morbidity due to impaired mucociliary clearance, however the mechanism that leads to the mucus dysfunction is not entirely understood. Interleukin 13 (IL-13), a key mediator of Type 2 (T2) inflammation, profoundly alters the ion transport properties of airway epithelium. However, these electrophysiological changes cannot explain the thick, tenacious airway mucus that characterizes the clinical phenotype. Here we report that IL-13 dramatically increases the airway surface liquid (ASL) viscosity in cultured primary human bronchial epithelial cells and thereby inhibits mucus clearance. These detrimental rheological changes require ATP12A, a non-gastric H+/K+-ATPase that secretes protons into the ASL. ATP12A knockdown or inhibition prevented the IL-13 dependent increase in ASL viscosity but did not alter the ASL pH. We propose that ATP12A promotes airway mucus dysfunction in individuals with T2 inflammatory airway diseases and that ATP12A may be a novel therapeutic target to improve mucus clearance.

Acute lung injury, referred to as the acute chest syndrome, is a major cause of morbidity and mortality in patients with sickle cell disease (SCD), which often occurs in the setting of a vaso-occlusive painful crisis. P-selectin antibody therapy reduces hospitalization of SCD patients by almost 50%, suggesting that an unknown P-selectin-independent mechanism promotes remaining vaso-occlusive events. In SCD patients, intra-erythrocytic polymerization of mutant hemoglobin promotes ischemia-reperfusion injury and hemolysis, which leads to the development of sterile inflammation. Using intravital microscopy in transgenic, humanized SCD mice and in vitro studies with blood from SCD patients, we reveal for the first time that the sterile inflammatory milieu in SCD promotes caspase-4/11-dependent activation of neutrophil-Gasdermin-D (GSDMD), which triggers P-selectin-independent shedding of neutrophil extracellular traps (NETs) in the liver. Remarkably, these NETs travel intravascularly from liver to lung, where they promote neutrophil-platelet aggregation and the development of acute lung injury. This study introduces a novel paradigm that liver to lung embolic translocation of NETs promotes pulmonary vascular vaso-occlusion, and identifies a new GSDMD-mediated, P-selectin-independent mechanism of lung injury in SCD.