SARS-Cov-2 Spike Protein Causes Human Lung Endothelial Inflammation

Patients with COVID-19 often present with pulmonary inflammation and blood coagulopathy, with severe cases advancing to acute respiratory distress syndrome (ARDS) and multiple organ failure. Although the pathogenesis is not completely understood, endothelial inflammation is suspected to be a major causative factor for the systemic manifestations of COVID-19. In this study, we investigated the direct effects of SARS-Cov-2 spike protein on pulmonary microvascular endothelial cells (ECs) isolated from the small airway region of viable human lungs. We verified the expression of angiotensin-converting enzyme 2 (Ace-2), the receptor for SARS-Cov-2 spike protein, in pulmonary ECs using flow cytometry analysis and immunofluorescence labeling. Treating ECs with recombinant spike protein caused increased F-actin stress fibers, enhanced phosphorylation of myosin light chain 2, and disruption of adherens junction continuity. In addition to the junction and cytoskeletal changes, spike protein-treated ECs showed increased expression of intercellular adhesion molecule 1 and enhanced adherence for monocytic cells. Interestingly, there was a significant accumulation of von Willebrand factor long strands on the cell surface in ECs isolated from COVID-19 positive human lungs, as well as on ECs from normal human lungs following spike protein treatment. In conclusion, we demonstrate that the SARS-Cov-2 spike protein is capable of directly activating human lung ECs and promoting inflammation/coagulopathy.

Cholangiopathy After Severe COVID-19: Clinical Features and Prognostic Implications.

INTRODUCTION: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 virus, is a predominantly respiratory tract infection with the capacity to affect multiple organ systems. Abnormal liver tests, mainly transaminase elevations, have been reported in hospitalized patients. We describe a syndrome of cholangiopathy in patients recovering from severe COVID-19 characterized by marked elevation in serum alkaline phosphatase (ALP) accompanied by evidence of bile duct injury on imaging. METHODS: We conducted a retrospective study of COVID-19 patients admitted to our institution from March 1, 2020, to August 15, 2020, on whom the hepatology service was consulted for abnormal liver tests. Bile duct injury was identified by abnormal liver tests with serum ALP > 3x upper limit of normal and abnormal findings on magnetic resonance cholangiopacreatography. Clinical, laboratory, radiological, and histological findings were recorded in a Research Electronic Data Capture database. RESULTS: Twelve patients were identified, 11 men and 1 woman, with a mean age of 58 years. Mean time from COVID-19 diagnosis to diagnosis of cholangiopathy was 118 days. Peak median serum alanine aminotransferase was 661 U/L and peak median serum ALP was 1855 U/L. Marked elevations of erythrocyte sedimentation rate, C-reactive protein, and D-dimers were common. Magnetic resonance cholangiopacreatography findings included beading of intrahepatic ducts (11/12, 92%), bile duct wall thickening with enhancement (7/12, 58%), and peribiliary diffusion high signal (10/12, 83%). Liver biopsy in 4 patients showed acute and/or chronic large duct obstruction without clear bile duct loss. Progressive biliary tract damage has been demonstrated radiographically. Five patients were referred for consideration of liver transplantation after experiencing persistent jaundice, hepatic insufficiency, and/or recurrent bacterial cholangitis. One patient underwent successful living donor liver transplantation. DISCUSSION: Cholangiopathy is a late complication of severe COVID-19 with the potential for progressive biliary injury and liver failure. Further studies are required to understand pathogenesis, natural history, and therapeutic interventions.

Extracellular vesicles: new players in regulating vascular barrier function.

Extracellular vesicles (EVs) have attracted rising interests in the cardiovascular field not only because they serve as serological markers for circulatory disorders but also because they participate in important physiological responses to stress and inflammation. In the circulation, these membranous vesicles are mainly derived from blood or vascular cells, and they carry cargos with distinct molecular signatures reflecting the origin and activation state of parent cells that produce them, thus providing a powerful tool for diagnosis and prognosis of pathological conditions. Functionally, circulating EVs mediate tissue-tissue communication by transporting bioactive cargos to local and distant sites, where they directly interact with target cells to alter their function. Recent evidence points to the critical contributions of EVs to the pathogenesis of vascular endothelial barrier dysfunction during inflammatory response to injury or infection. In this review, we provide a brief summary of the current knowledge on EV biology and advanced techniques in EV isolation and characterization. This is followed by a discussion focusing on the role and mechanisms of EVs in regulating blood-endothelium interactions and vascular permeability during inflammation. We conclude with a translational perspective on the diagnostic and therapeutic potential of EVs in vascular injury or infectious diseases, such as COVID-19.