Pulmonary endothelial NEDD9 and the prothrombotic pathophenotype of acute respiratory distress syndrome due to SARS‐CoV‐2 infection

Abstract The pathobiology of in situ pulmonary thrombosis in acute respiratory distress syndrome (ARDS) due to severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) infection is incompletely characterized. In human pulmonary artery endothelial cells (HPAECs), hypoxia increases neural precursor cell expressed, developmentally downregulated 9 (NEDD9) and induces expression of a prothrombotic NEDD9 peptide (N9P) on the extracellular plasma membrane surface. We hypothesized that the SARS‐CoV‐2–ARDS pathophenotype involves increased pulmonary endothelial N9P. Paraffin‐embedded autopsy lung specimens were acquired from patients with SARS‐CoV‐2–​​​​​​ARDS (n = 13), ARDS from other causes (n = 10), and organ donor controls (n = 5). Immunofluorescence characterized the expression of N9P, fibrin, and transcription factor 12 (TCF12), a putative binding target of SARS‐CoV‐2 and known transcriptional regulator of NEDD9. We performed RNA‐sequencing on normal HPAECs treated with normoxia or hypoxia (0.2% O2) for 24 h. Immunoprecipitation‐liquid chromatography‐mass spectrometry (IP‐LC‐MS) profiled protein–protein interactions involving N9P relevant to thrombus stabilization. Hypoxia increased TCF12 messenger RNA significantly compared to normoxia in HPAECs in vitro (+1.19‐fold, p = 0.001; false discovery rate = 0.005), and pulmonary endothelial TCF12 expression was increased threefold in SARS‐CoV‐2–ARDS versus donor control lungs (p