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PLoS Comput Biol ; 17(3): e1008810, 2021 03.
Article in English | MEDLINE | ID: covidwho-1121603


Abnormal coagulation and an increased risk of thrombosis are features of severe COVID-19, with parallels proposed with hemophagocytic lymphohistiocytosis (HLH), a life-threating condition associated with hyperinflammation. The presence of HLH was described in severely ill patients during the H1N1 influenza epidemic, presenting with pulmonary vascular thrombosis. We tested the hypothesis that genes causing primary HLH regulate pathways linking pulmonary thromboembolism to the presence of SARS-CoV-2 using novel network-informed computational algorithms. This approach led to the identification of Neutrophils Extracellular Traps (NETs) as plausible mediators of vascular thrombosis in severe COVID-19 in children and adults. Taken together, the network-informed analysis led us to propose the following model: the release of NETs in response to inflammatory signals acting in concert with SARS-CoV-2 damage the endothelium and direct platelet-activation promoting abnormal coagulation leading to serious complications of COVID-19. The underlying hypothesis is that genetic and/or environmental conditions that favor the release of NETs may predispose individuals to thrombotic complications of COVID-19 due to an increase risk of abnormal coagulation. This would be a common pathogenic mechanism in conditions including autoimmune/infectious diseases, hematologic and metabolic disorders.

COVID-19/complications , COVID-19/genetics , Extracellular Traps/genetics , Lymphohistiocytosis, Hemophagocytic/complications , Lymphohistiocytosis, Hemophagocytic/genetics , Models, Biological , SARS-CoV-2/genetics , Thrombosis/etiology , Thrombosis/genetics , Algorithms , Cell Degranulation/genetics , Computational Biology , Gene Expression Regulation , Gene Regulatory Networks , Genetic Predisposition to Disease , Humans , Pandemics , Protein Interaction Maps , Pulmonary Embolism/etiology , Pulmonary Embolism/genetics , Viral Proteins/genetics
Cells ; 9(9)2020 08 26.
Article in English | MEDLINE | ID: covidwho-730306


Natural killer cells are important in the control of viral infections. However, the role of NK cells during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has previously not been identified. Peripheral blood NK cells from SARS-CoV and SARS-CoV-2 naïve subjects were evaluated for their activation, degranulation, and interferon-gamma expression in the presence of SARS-CoV and SARS-CoV-2 spike proteins. K562 and lung epithelial cells were transfected with spike proteins and co-cultured with NK cells. The analysis was performed by flow cytometry and immune fluorescence. SARS-CoV and SARS-CoV-2 spike proteins did not alter NK cell activation in a K562 in vitro model. On the contrary, SARS-CoV-2 spike 1 protein (SP1) intracellular expression by lung epithelial cells resulted in NK cell-reduced degranulation. Further experiments revealed a concomitant induction of HLA-E expression on the surface of lung epithelial cells and the recognition of an SP1-derived HLA-E-binding peptide. Simultaneously, there was increased modulation of the inhibitory receptor NKG2A/CD94 on NK cells when SP1 was expressed in lung epithelial cells. We ruled out the GATA3 transcription factor as being responsible for HLA-E increased levels and HLA-E/NKG2A interaction as implicated in NK cell exhaustion. We show for the first time that NK cells are affected by SP1 expression in lung epithelial cells via HLA-E/NKG2A interaction. The resulting NK cells' exhaustion might contribute to immunopathogenesis in SARS-CoV-2 infection.

Betacoronavirus/chemistry , Coronavirus Infections/immunology , Histocompatibility Antigens Class I/metabolism , Killer Cells, Natural/immunology , Lymphocyte Activation/genetics , NK Cell Lectin-Like Receptor Subfamily C/metabolism , Pneumonia, Viral/immunology , Spike Glycoprotein, Coronavirus/metabolism , Blood Donors , Bronchi/cytology , COVID-19 , Cell Degranulation/genetics , Coculture Techniques , Coronavirus Infections/metabolism , Coronavirus Infections/virology , Epithelial Cells/metabolism , Humans , Interferon-gamma/metabolism , K562 Cells , Pandemics , Pneumonia, Viral/metabolism , Pneumonia, Viral/virology , RNA, Viral/genetics , SARS Virus/chemistry , SARS-CoV-2 , Severe Acute Respiratory Syndrome/immunology , Severe Acute Respiratory Syndrome/metabolism , Severe Acute Respiratory Syndrome/virology , Spike Glycoprotein, Coronavirus/genetics , Transfection