ABSTRACT
Endothelial dysfunction accompanies the microvascular thrombosis commonly observed in severe COVID-19. Constitutively, the endothelial surface is anticoagulant, a property maintained at least in part via signaling through the Tie2 receptor. During inflammation, the Tie2 antagonist angiopoietin-2 (Angpt-2) is released from endothelial cells and inhibits Tie2, promoting a prothrombotic phenotypic shift. We sought to assess whether severe COVID-19 is associated with procoagulant endothelial dysfunction and alterations in the Tie2/angiopoietin axis. Primary HUVECs treated with plasma from patients with severe COVID-19 upregulated the expression of thromboinflammatory genes, inhibited the expression of antithrombotic genes, and promoted coagulation on the endothelial surface. Pharmacologic activation of Tie2 with the small molecule AKB-9778 reversed the prothrombotic state induced by COVID-19 plasma in primary endothelial cells. Lung autopsies from patients with COVID-19 demonstrated a prothrombotic endothelial signature. Assessment of circulating endothelial markers in a cohort of 98 patients with mild, moderate, or severe COVID-19 revealed endothelial dysfunction indicative of a prothrombotic state. Angpt-2 concentrations rose with increasing disease severity, and the highest levels were associated with worse survival. These data highlight the disruption of Tie2/angiopoietin signaling and procoagulant changes in endothelial cells in severe COVID-19. Our findings provide rationale for current trials of Tie2-activating therapy with AKB-9778 in COVID-19.
Subject(s)
COVID-19 Drug Treatment , Endothelial Cells/drug effects , Protective Agents/pharmacology , Receptor, TIE-2/metabolism , Adult , Aged , Aged, 80 and over , Angiopoietin-2/metabolism , Aniline Compounds , Female , Gene Expression , Humans , Lung , Male , Middle Aged , Receptor, TIE-2/genetics , SARS-CoV-2 , Signal Transduction , Sulfonic Acids , Vascular Diseases/metabolism , Young AdultABSTRACT
PURPOSE: The purpose of the study was to examine the impact of the first wave of COVID-19 on National Health Service (NHS) 18F-fluorodeoxyglucose positron emission tomography computed tomography (FDG PET-CT) scanning activity across England. METHODS: Monthly FDG PET-CT scanning activity was collected from 41/48 NHS England provider sites. Data from 31/41 sites were stratified by nononcology/oncology, cancer type, with lung cancer and lymphoma split into specific indications, turn-around times and delays due to radiotracer. RESULTS: In April and May 2020, a 32 and 31% decrease in activity was observed, a larger decrease for noncancer compared with cancer FDG PET-CT. In June 2020, activity started to recover with 6% fewer scans recorded compared with June 2019. Of the six most common indications, lung and oesophageal cancer had the largest decrease in activity and slowest recovery. Lymphoma and melanoma showed the smallest decrease and fastest recovery. Lung cancer scans for initial diagnosis/staging saw the largest fall and slowest recovery compared with scans for known lung cancer. There was no percentage increase in overall turn-around time compared with the same months in 2019, and no increase in turn-around time of more than 7 working days due to FDG supply during April and May 2020 compared with the 3 previous months. CONCLUSIONS: There is no correlation between FDG PET-CT activity (fall and recovery) in England and the ability to provide the service by NHS England. It most likely reflects a combination of changes in health-seeking behaviour, NHS health policy and a decrease in the use of investigations that carry a high risk of COVID-19 transmission.