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Neutrophilic granulocytes (NG) are the main drivers of pathological inflammation in COVID-19. Objective. To specify the mechanisms of immunopathogenesis of COVID-19 based on a comparative immunological study of the number and phenotype of CD16+SD62L+CD11b+CD63- and CD16+SD62L+CD11b+CD63+ subsets with an assessment of their effector functions against changing profile of NG-associated cytokines IL-8, IL-18, IL-17A, VEGF-A, IFNalpha, and IFNgamma. Patients and methods. In patients with moderate-to-severe and severe COVID-19, we determined IL-1beta, TNFalpha, IL-6, IL-8, IL-18, IL-17A, VEGF-A, IFNalpha, and IFNgamma (ELISA), the phenotype of CD16+SD62L+CD11b+CD63- and CD16+SD62L+CD11b+CD63+ subsets, NF-kappaB-NG (CYTOMICS FC500), phagocytically active NG (%), neutrophil extracellular traps (NETs), NG in apoptosis, and the activity of NADPH oxidase. Results. In COVID-19 against the background of IFNalpha and IFNgamma production blockade and high levels of NG-associated IL-8, IL-18, IL-17A, VEGF-A, a reduction in the number of mature and functionally active CD16brightSD62LbrightCD11bbrightCD63-NG subsets was revealed, as well as an increase in the number of CD16dimSD62LdimSD11bbrightCD63-NG subsets with an immunosuppressive phenotype and CD16brightSD62LbrightSD11bbrightCD63bright-NG subsets with high cytotoxic activity and ability to form NETs, a decrease in the percentage of phagocytically active NG and an increase in the activity of NADPH oxidase, NETs, and NG in apoptosis. Conclusion. IFNalpha deficiency provokes a hyperergic response of NG-associated cytokines, which leads to the formation of uncontrolled immune inflammation involving NG subsets with an immunosuppressive and cytotoxic phenotype, exacerbating the course of COVID-19. The use of recombinant IFNalpha-2b with antioxidants (Viferon) in the early stages of the disease can help to restore immune homeostasis, normalize the level of NG-associated cytokines, reduce NERTs, and achieve good clinical efficacy.Copyright © 2022, Dynasty Publishing House. All rights reserved.
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Background/Objectives: Despite intensive research of the novel coronavirus SARS-CoV-2 and COVID-2019 caused by it, factors affecting the severity of the disease remains poorly understood. Clinical manifestations of COVID-2019 may vary from asymptomatic form to pneumonia, acute respiratory distress syndrome (ARDS) and multiorgan failure. Features of individual genetic landscape of patients can play an important role in development of the pathological process of COVID-19. In this regard the purpose of this study was to investigate the influence of polymorphic variants in genes (ADD1, CAT, IL17F, IL23R, NOS3, IFNL3, IL6, F2, F13A1, ITGB3, HIF1A, MMP12, VEGFA), associated with cardiovascular, respiratory and autoimmune pathologies, on the severity of COVID-19 and post-COVID syndrome in patients from Russia. Method(s): The study included 200 patients recovered from COVID-19. Two groups of patients were formed in accordance with clinical manifestations: with mild and moderate forms of the disease. The polymorphic variants were analysed with real-time PCR using commercial kits (Syntol). Result(s): 13 SNPs (rs4961;rs1001179;rs612242;rs11209026;rs2070744;rs8099917;rs1800795;rs1799963;rs5985;rs5918;rs11549465;rs652438;rs699947) were genotyped and comparative analysis of allele frequency distribution was carried out in two groups of patients recovered from COVID-2019. Conclusion(s): Identification of polymorphic variants in genome associated with severity of pathological processes in patients infected with SARS-CoV-2 can contribute to the identification of individuals with an increased risk of severe infection process and can also serve as a basis for developing personalized therapeutic approaches to the treatment of post-COVID syndrome.
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Background: Although our understanding of immunopathology in the risk and severity of COVID-19 disease is evolving, a detail of immune response in long-term consequences of COVID-19 infection remains unclear. Recently, few studies have detailed the immune and cytokine profiles associated with PASC. However, dysregulation of immune system driving pulmonary PASC is still largely unknown. Method(s): To characterize the immunological features of PPASC, we performed droplet-based scRNA-sequencing using 10X genomics to study the transcriptomic profiles of peripheral blood mononuclear cells (PBMCs) from participants naive to SARS-CoV-2 (NP, n=2) and infected with SARS-CoV-2 with chronic pulmonary symptoms (PPASC, n=2). Result(s): Analysis of more than 34,000 PBMCs by integrating our dataset with previously reported control datasets generated cell distribution and identified 11 immune cell types based on canonical gene expression. The proportion of myeloid-lineage cells (CD14+monocyte, CD16+monocyte, and dendritic cells) and platelets were increased in PPASC compared with those of NP. Specifically, PPASC displayed up-regulation of VEGFA and transcription factors, such as ATF2, ELK, and SMAD in myeloid-lineage cells. Also, TGF-beta and WNT signaling pathways were up-regulated in these cell population. Cell-cell interaction analysis identified that myeloid-lineage cells in PPASC participated in regulation of fibrosis and immune response, such as VEGFA (increased) and MIF (decreased) interactions. Conclusion(s): Together, this study provides high-resolution insights into immune landscape in PPASC. Our results emphasize differences in myeloid lineage-mediated fibrosis and immunity between PPASC and NP, suggesting they could act as potential pathological drivers of PPASC. (Figure Presented).
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Neutrophilic granulocytes (NG) are the main drivers of pathological inflammation in COVID-19. Objective. To specify the mechanisms of immunopathogenesis of COVID-19 based on a comparative immunological study of the number and phenotype of CD16+SD62L+CD11b+CD63- and CD16+SD62L+CD11b+CD63+ subsets with an assessment of their effector functions against changing profile of NG-associated cytokines IL-8, IL-18, IL-17A, VEGF-A, IFNalpha, and IFNgamma. Patients and methods. In patients with moderate-to-severe and severe COVID-19, we determined IL-1beta, TNFalpha, IL-6, IL-8, IL-18, IL-17A, VEGF-A, IFNalpha, and IFNgamma (ELISA), the phenotype of CD16+SD62L+CD11b+CD63- and CD16+SD62L+CD11b+CD63+ subsets, NF-kappaB-NG (CYTOMICS FC500), phagocytically active NG (%), neutrophil extracellular traps (NETs), NG in apoptosis, and the activity of NADPH oxidase. Results. In COVID-19 against the background of IFNalpha and IFNgamma production blockade and high levels of NG-associated IL-8, IL-18, IL-17A, VEGF-A, a reduction in the number of mature and functionally active CD16brightSD62LbrightCD11bbrightCD63-NG subsets was revealed, as well as an increase in the number of CD16dimSD62LdimSD11bbrightCD63-NG subsets with an immunosuppressive phenotype and CD16brightSD62LbrightSD11bbrightCD63bright-NG subsets with high cytotoxic activity and ability to form NETs, a decrease in the percentage of phagocytically active NG and an increase in the activity of NADPH oxidase, NETs, and NG in apoptosis. Conclusion. IFNalpha deficiency provokes a hyperergic response of NG-associated cytokines, which leads to the formation of uncontrolled immune inflammation involving NG subsets with an immunosuppressive and cytotoxic phenotype, exacerbating the course of COVID-19. The use of recombinant IFNalpha-2b with antioxidants (Viferon) in the early stages of the disease can help to restore immune homeostasis, normalize the level of NG-associated cytokines, reduce NERTs, and achieve good clinical efficacy.Copyright © 2022, Dynasty Publishing House. All rights reserved.
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Purpose of Study: COVID pneumonia caused by SARS-CoV-2 can result in a depletion of surfactant & lung injury, which resembles neonatal respiratory distress syndrome. Exogenous surfactant has shown promise as a therapeutic option in intubated hospitalized patients. Our preliminary data in human lung organoids (LOs) with a deficiency of surfactant protein B (SP-B) showed an increased viral load compared to normal LOs. Single cell RNA sequencing (scRNAseq) revealed that SP-B-deficient cells showed increased viral entry genes (ACE2 receptor) & dysregulated inflammatory markers emanating from the lung cells themselves. Our objective was to determine: (1) cell-specific transcriptional differences between normal & SP-B deficient human lung cells after infection with SARS-CoV-2 and (2) a therapeutic role of SP-B protein & surfactant in COVID-19 pneumonia. Methods Used: We used normal and SP-B mutant (homozygous, frameshift, loss of function mutation p.Pro133GlnfsTer95, previously known as 121ins2) human induced pluripotent stem cells (hiPSC) and differentiated them into 3D proximal lung organoids. The organoids were infected with the delta variant of SARS-CoV-2 for 24 hours at an MOI of 1. Infected and uninfected organoids were fixed in trizol in triplicate and underwent processing for bulk RNA sequencing. We tested for differentially expressed genes using the program DEseq. We also plated normal iPSC derived lung organoids as a monolayer and pre-treated them with 1mg/ml of Poractant alfa or 5 uM of recombinant SP-B protein. The delta strain of SARS-CoV-2 was added to the 96 wells at an MOI of 0.1 for one hour with shaking, then an overlay with DMEM/CMC/FBS was added and left on for 23 hours. The plate was fixed and stained for nucleocapsid (NC) protein. Summary of Results: Bioinformatic analysis of the bulk RNA sequencing data showed an increase in the multiple cytokines and chemokines in the SP-B mutant LOs compared to control. We also saw differential gene expression patterns in the SP-B mutant LOs including a reduction in SFTPC, FOXA2, and NKX2-1 and an increase in IL1A, VEGFA, PPARG and SMAD3. In the exogenous surfactant experiments, there was a decrease in total expression of viral NC in the Poractant alfa & rSP-B-treated cells compared to SARS-CoV-2 infection alone (p<0.001). Conclusion(s): Surfactant modulates the viral load of SARS-CoV-2 infection in the human lung. Deficiency in SP-B results in the dysregulation of the lung epithelial inflammatory signaling pathways resulting in worsening infections.
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Background: Systemic and pulmonary uncontrolled activation of pro-inflammatory pathways following severe acute respiratory syndrome coronavirus 2 (Sars-Cov-2) infection can lead to development of serious short- and long-term complications such as ARDS and lung fibrosis. Mounting evidence reveals a positive correlation between cytokine overexpression in bronchoalveolar lavage fluid (BALF) and the severity of respiratory involvement in Sars-Cov-2 patients. We aimed to compare levels of metalloprotease 9 (MMP9) and fibrogenic Growth factors (VEGF, a-CTGF, FGF, PDGF) in BALF of intermediate medicine ward (IMW) Sars-Cov-2 and Intensive Care Unit (ICU) mechanically ventilated patients. Method(s): Sars-Cov-2 infection was diagnosed by Reverse transcriptase-polymerase chain reaction (RT-PCR) on respiratory samples. 10 IMW and 10 ICU patients were enrolled. ELISA assay was used to quantify growth factors and MMP9 on UV rays inactivated BAL fluid samples. Result(s): BALFs collected from ICU patients showed higher levels of Connective Tissue Growth Factor (CTGF;p<0.05) and MMP-9 (p<0,05) whereas inward patients with moderate pneumonia displayed higher titles of Vascular Endothelial Growth Factor (VEGF;p<0,05). FGF values were below detection limit in 90% of samples. No statistical difference in Platelet Derived Growth Factor (PDGF) levels were found between the two groups. Conclusion(s): Analogously to what observed for pro-inflammatory cytokines, early alveolar expression of MMP9 and CTGF are associated to a more severe outcome and might play a role in determining fibrotic evolution while VEGF does not seem to play a major role.
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Objective To analyze the medication rules of related epidemic disease prescription in Treatise on Febrile Diseases based on data mining, and the mechanism of "Chaihu (Bupleuri Radix)-Huangqin (Scutellariae Radix)” as the core drugs in the treatment of coronavirus disease 2019 (COVID-19) by network pharmacology, in order to explore the contemporary value of classical prescriptions in the treatment of epidemic diseases. Methods The prescriptions for treating epidemic diseases in Treatise on Febrile Diseases were screened, and the medication rules such as drug frequency, flavor and meridian tropism as well as correlation, apriori algorithm were analyzed by using software such as R language. The mechanism of the core drugs in the medication pattern in the treatment of COVID-19 was explored by the network pharmacology. A "disease-drug-ingredient-target” network was constructed on the selected components and targets with Cytoscape. The key targets were introduced into String database for network analysis of protein-protein interaction (PPI), and gene ontology (GO) functional analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis were conducted in R language. Results A total of 61 prescriptions for treating epidemic diseases in Treatise on Febrile Diseases were included, including 52 traditional Chinese medicines (TCMs). In the top 20 high-frequency drugs, warm drugs, spicy drugs and qitonifying drugs were mainly used, mostly in the spleen and lung meridian. Chaihu (Bupleuri Radix) and Huangqin (Scutellariae Radix) herb pair had the strongest correlation. A total of five clusters were excavated: supplemented formula of Xiaochaihu Decoction (小柴胡汤), Sini Decoction (四逆汤), supplemented formule of Maxing Shigan Decoction (麻杏石甘汤), Fuling Baizhu Decoction (茯苓白术汤) and Dachengqi Decoction (大承气汤). A total of 45 active ingredients, 189 action targets of Bupleuri Radix-Scutellariae Radix herb pair, and 543 targets of COVID-19 were obtained from TCMSP and Genecards, and 64 intersection targets were generated. The results of the network analysis showed that the main components of core drugs pair against COVID-19 may be quercetin, wogonin, kaempferol baicalein, acacetin etc., and the core targets may be VEGFA, TNF, IL-6, TP53, AKT1, CASP3, CXCL8, PTGS2, etc. A total of 1871 related entries and 164 pathways were obtained by GO and KEGG enrichment analysis, respectively. Conclusion In Treatise on Febrile Diseases, the treatment of epidemic diseases mainly chose pungent, warm, spleen-invigorating and qi-tonifying herbs, such as Xiaochaihu Decoction, Sini Decoction and Dachengqi Decoction, etc. It was found that Bupleuri Radix-Scutellariae Radix core herb pair prevent and treat COVID-19 through multi-target targets such as PTGS2, IL-6 and TNF. The ancient prescriptions for treating epidemic disease in Treatise on Febrile Diseases may have significant reference value for the prevention and treatment of new epidemic diseases today. © 2023 Editorial Office of Chinese Traditional and Herbal Drugs. All rights reserved.
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In our study, we aimed to evaluate the significance of specific cytokines in blood plasma as predictive markers of COVID-associated mortality. Materials and methods. In plasma samples of 29 patients with PCR-confirmed COVID-19 we measured the concentrations of 47 molecules. These molecules included: interleukins and selected pro-inflammatory cytokines (IL-1alpha, IL-1beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-9, IL-12 (p40), IL-12 (p70), IL-13, IL-15, IL-17A/CTLA8, IL-17-E/IL-25, IL-17F, IL-18, IL-22, IL-27, IFNalpha2, IFNgamma, TNFalpha, TNFbeta/Lymphotoxin-alpha(LTA));chemokines (CCL2/MCP-1, CCL3/MIP-1alpha, CCL4/MIP-1beta, CCL7/MCP-3, CCL11/Eotaxin, CCL22/MDC, CXCL1/GROalpha, CXCL8/IL-8, CXCL9/MIG, CXCL10/IP-10, CX3CL1/Fractalkine);anti-inflammatory cytokines (IL-1Ra, IL-10);growth factors (EGF, FGF-2/FGF-basic, Flt-3 Ligand, G-CSF, M-CSF, GM-CSF, PDGF-AA, PDGFAB/BB, TGFalpha, VEGF-A);and sCD40L. We used multiplex analysis based on xMAP technology (Luminex, USA) using Luminex MagPix. As controls, we used plasma samples of 20 healthy individuals. Based on the results, we applied Receiver Operating Characteristic (ROC) analysis and Area Under Curve (AUC) values to compare two different predictive tests and to choose the optimal division point for disease outcome (survivors/non-survivors). To find optimal biomarker combinations, we as used cytokines concentrations as dependent variables to grow a regression tree using JMP 16 Software.Results. Out of 47 studied cytokines/chemokines/growth factors, we picked four pro-inflammatory cytokines as having high significance in evaluation of COVID-19 outcome: IL-6, IL-8, IL-15, and IL-18. Based on the results received, we assume that the highest significance in terms of predicting the outcome of acute COVID-19 belongs to IL-6 and IL-18. Conclusion. Analyzing concentrations of IL-6 and IL-18 before administering treatment may prove valuable in terms of outcome prognosis. Copyright © Arsentieva N.A. et al., 2022.
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Objective To explore the application pattern and mechanism of medicine and food homologous traditional Chinese medicine (TCM) against modern viral diseases. Methods The method of literature mining was applied based on the characteristics of modern viral diseases, combining with ancient books and modern prescriptions for the prevention and treatment of viral diseases to build a relevant prescription database. Then SPSS and R language were used to analyze the high-frequency medicine and food homologous TCM and high confidence medicine and food homologous prescriptions in these prescriptions, and cluster analysis was carried out. The antiviral characteristic active ingredients of high-frequency medicinal and food homologous TCN were identified and analyzed, and the action mechanism of active ingredients against modern viral diseases was evaluate by network pharmacology. Results In the prevention and treatment of modern viral diseases, Gancao (Glycyrrhizae Radix et Rhizoma)-Chenpi (Citri Reticulatae Pericarpium)-Fuling (Poria) had the highest confidence, Glycyrrhizae Radix et Rhizoma-Jiegeng (Platycodonis Radix) had the highest support. At the same time, the prescriptions were clustered and analyzed to obtain Jinyinhua (Lonicerae Japonicae Flos)-Huangqi (Astragali Radix)-Huoxiang (Agastache rugosa), Glycyrrhizae Radix et Rhizoma-Xingren (Armeniacae Semen Amarum)-Poria-Platycodonis Radix-Citri Reticulatae Pericarpium, Ganjiang (Zingiberis Rhizoma)-Renshen (Ginseng Radix et Rhizoma), Zisu (Perilla frutescens)-Gegen (Puerariae Lobatae Radix), Lugen (Phragmitis Rhizoma)-Sangye (Mori Folium), Shengjiang (Zingiberis Rhizoma Recens)-Dazao (Jujubae Fructus) clustering new prescription. The core action targets of EGFR, CASP3, VEGFA, STAT3, MMP9, HSP90AA1, mTOR, PTGS2, MMP2, TLR4, MAPK14, etc were identified. The action mechanism involved human cytomegalovirus infection, coronavirus disease-coronavirus disease 2019 (COVID-19), etc. The core action pathway were phosphatidylinositol-3/kinase protein kinase B (PI3K/Akt) signal pathway, mitogen activated protein kinase (MAPK) signal pathway, interleukin-17 (IL-17) signal pathway, Janus kinase/signal transducer and activator of transcription (JAK/STAT) signal pathway, etc. Conclusion Through data mining, six new prescriptions for preventing and controlling modern viral diseases were obtained, and the mechanism of action was preliminarily discussed, which provided some reference for the research and development of medicine and food homologous TCM prescriptions for the prevention and treatment of viral epidemics and related health products.
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Objectives: Coronavirus disease 2019 (COVID-19) has had a global impact and is spreading quickly. ChuanKeZhi injection (CKZI) is widely used in asthma patients. In this paper, we aimed to explore active compounds of CKZ and determine potential mechanisms against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through network pharmacology, molecular docking and dynamic simulation studies. Materials and Methods: We used the Systematic Pharmacology Database and Analysis Platform of Traditional Chinese Medicine (TCMSP) to screen active compounds and potential target proteins of CKZ. COVID-19 target genes were screened via the American National Center for Biotechnology Information (NCBI) gene database and human gene database (GeenCards). The protein interaction network was constructed by the Protein Interaction Network Database (Search Tool for the Retrieval of Interacting Genes/Proteins (STRING)) platform. GO enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed by the Metascape database. The main active compounds of CKZ were docked with angiotensin-converting enzyme 2 (ACE2), spike protein S1, and SARS-CoV-2-3CL pro and also docked with hub targets. We performed molecular dynamics (MD) simulation studies for validation. Results: We finally obtained 207 CKZ potential targets and 4681 potential COVID-19 targets. Key targets included mainly AKT1, TNF, IL6, VEGFA, IL1B, TP53, JUN, CASP3, etc. There were 217 Gene Ontology (GO) items in the GO enrichment analysis (p < 0.05). The main KEGG pathways included the advanced glycation end products (AGE)- receptor for AGE (RAGE) signalling pathway in diabetic complications, rheumatoid arthritis, chemical carcinogenesis-receptor activation, alcoholic liver disease, etc. Molecular docking and dynamics simulation studies both exhibited great binding capacity. Conclusions: Network pharmacology, molecular docking and dynamics simulation studies were used to identify the potential and key targets, pharmacological functions, and therapeutic mechanisms of CKZI in the treatment of COVID-19. CKZI may be an effective and safe drug in COVID-19 treatment. However, further work is needed for validation.
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Objetivos: a imunotrombose consiste no processo que envolve a ativação concomitante da imunidade inata, hemostasia e endotélio como parte da resposta a patógenos, e vem sendo colocada no centro da fisiopatologia da Covid-19. Um elemento menos explorado da imunotrombose é a ruptura da barreira endotelial (BE), que permite o acesso dos leucócitos aos tecidos inflamados. Entre os reguladores da integridade da BE destacam-se as vias que envolvem a angiopoietina (Ang) 1 e 2 e seu receptor Tie2, e a via do VEGF-A/VE-caderina (VEC). Além deste papel, foi recentemente demonstrado que a ativação da via Ang/Tie2 inibe a ativação endotelial e a expressão de fator tecidual, estabilizando o endotélio no estado quiescente. Neste estudo determinamos os níveis circulantes de mediadores da integridade da BE na Covid-19, e exploramos sua associação com a gravidade da doença, assim como com a ativação da hemostasia através de um painel abrangente de biomarcadores. Materiais e métodos: as amostras foram obtidas de 30 pacientes internados por Covid-19 devido à hipoxemia e achados tomográficos típicos, e recrutados para um estudo clínico (REBEC: U1111-1250-1843). As amostras foram coletadas em até 24h do diagnóstico, antes de qualquer intervenção terapêutica. Os níveis de reguladores da BE foram medidos por métodos imunológicos (Elisa ou multiplex), e o de biomarcadores da hemostasia por kits comerciais específicos. Um grupo de 30 indivíduos saudáveis pareados por idade e sexo foram utilizados como controle. Dados clínicos e laboratoriais foram obtidos dos prontuários digitais. Resultados: o tempo médio de internação foi de 12,9 ± 9,8 dias, e 12 pacientes (40%) necessitaram de UTI. O dímero D médio foi de 3.609 ± 14.440 ng/mL. Os níveis circulantes de todos reguladores da integridade da BE encontraram-se aumentados em pacientes, quando comparado com controles (Ang1: 463.2 ± 194.6 vs 237.4 ± 104.9 pg/mL, p < 0.0001;Ang2: 1.926 (1.275-3.134) vs 1.215 (9-1.444) pg/mL, p < 0.0001;Tie2: 10.753 ± 2.377 vs 8.603 ± 1.851 pg/mL, p < 0.0001 e VEGF-A: 94.7 (73.4-116.0) vs 45.9 (39.7-57.0), p < 0.0001. Além disso, os níveis de alguns destes reguladores se associaram significativamente a desfechos de relevância clínica, a saber: (i) extensão da lesão pulmonar na tomografia: Ang2 e VEGF-A;(ii) tempo de internação em UTI: VEGF-A. Interessantemente, observamos correlações consistentes e significativas entre os níveis de reguladores da BE a proteínas envolvidas na ativação da hemostasia (fibrinogênio, VWF: Ag, uPAR, PAI-1 e P-selectina). Discussão: o interesse no estudo de reguladores da integridade da BE na Covid-19 já se justifica pelo fato de a doença envolver tanto o comprometimento da barreira alvéolo-capilar quanto a ativação da angiogênese, como demonstrado por outros autores. Nossos resultados reforçam a relevância destas vias através da associação observada com desfechos clínicos. Além disso, os resultados mostram pela primeira vez uma associação entre mediadores da integridade da BE e um painel amplo de biomarcadores da ativação da hemostasia, sugerindo um crosstalk entre estas vias na Covid-19, como demonstrado recentemente no contexto da sepse. Conclusões: nossos resultados apontam que a via Ang/Tie2 deve ser considerada um alvo terapêutico atrativo na Covid-19, por representar um elemento central da imunotrombose nestes pacientes.
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Background: the pathogenesis of severe COVID-19 involves the deregulated activation of different compartments of immunothrombosis, which are otherwise important for pathogen eradication and tissue repair. Coagulation activation, angiogenesis and alterations of endothelial barrier (EB) are elements of immunothrombosis that have been shown to be involved in the pathogenesis of COVID-19. Angiopoietins (Ang) 1 and 2 and their receptor Tie2 and VEGF-A are well-known pro-angiogenic mediators that, during inflammation also mediate EB disruption. Recently, it has also been demonstrated that the Ang/Tie2 pathway is involved in coagulation activation. Here we explored whether increased levels of angiogenesis/EB regulators (which have been previously associated with disease severity in COVID-19) are also associated with both EB disruption and coagulation activation in this condition. Methods: the study population consisted of 30 patients with COVID-19 confirmed by RT-PCR and presenting typical CT findings admitted due to hypoxemia. Thirty sex- and age-matched healthy individuals were recruited at the same time, from the same geographic region. Patients were part of a clinical trial (REBEC: U1111-1250-1843) but samples were obtained before any study intervention, within 24 hours from diagnosis confirmation. Circulating levels of angiogenesis/EB regulation mediators and coagulation biomarkers were measured by commercial assays (immunological or functional). Monolayers of endothelial cells from umbilical veins (HUVECs) or lung (HULECs) were used for measurement of EB integrity using an impedance sensor system (ECIS, Electric Cell-substrate Impedance Sensing System). Cells were stimulated with serum from patients or healthy individuals and EB integrity was continuously monitored for 36 hours. Clinical outcomes were obtained from the digital medical records. Results: mean length of hospital stay (LOS) was 12.9 ± 9.8 days. Twelve patients (40%) required intensive care (ICU) and 28/30 patients survived. Mean D-dimer was 3,609 ± 14,440 ng/mL. Circulating levels of Ang1, Ang2, sTie2 and VEGF-A were all significantly increased in patients compared to healthy individuals (Ang1: 463.2 ± 194.6 vs 237.4 ± 104.9 pg/mL, p<0.0001;Ang2: 1,926 (1,275 - 3,134) vs 1,215 (9 - 1,440 pg/mL), p<0.0001;Tie2: 10,753 ± 2,377 vs 8,603 ± 1,851 pg/mL, p<0.0001 and VEGF-A: 94.7 (73.4 - 116.0) vs 45.9 (39.7 - 57.0 pg/mL), p<0.0001.). In contrast, soluble VE-cadherin levels were decreased in patients compared to healthy individuals (1,234 ± 318 vs 1,539 ± 363 ng/mL, P=0.001). Serum from COVID-19 patients induced decreases of EB integrity in monolayers of both HUVECs and HULECs as early as 15 minutes, lasting up to 5 hours after stimulation (figure 1). The magnitude of EB disruption was correlated with clinically relevant outcomes such as time of ICU stay and LOS (figure 1). Interestingly, levels of Ang1, Ang2 and soluble VE-cadherin levels were also significantly correlated with the magnitude of EB disruption, as well as with biomarkers of coagulation activation such as fibrinogen, Von Willebrand Factor antigen levels, PAI-1, P-selectin and urokinase receptor (uPAR). Conclusions: Ang-1/Ang-2 mediated Tie2 signaling has been shown to be important for the fine regulation of barrier integrity and coagulation activation at the endothelial level, which are two critical elements of immunothrombosis. Our results provide evidence supporting that the interplay between these processes can play a role in the mechanisms driving COVID-19 severity, and suggest that targeting the Ang/Tie2 and VEGF-A pathways could be attractive strategies to modulate not only changes of the alveolar-capillary barrier, but also of coagulation activation in COVID-19. Figure 1. In (a), endothelial barrier (EB) integrity of HUVEC monolayers upon stimulation by serum from COVID-19 patients and healthy individuals (n=27-30 per group). The lower the normalized resistance, the higher the magnitude of EB disruption. Significant differences (* to ****) are evident from 15 min to 5 hours (An va corrected for multiple comparisons). In the lower panels, the correlation of EB disruption with clinically relevant outcomes such as length of hospital stay (b) and days of intensive care (c) are shown. Negative correlations (Spearman test) indicate that the magnitude of EB disruption is associated with worse outcomes. [Formula presented] Disclosures: No relevant conflicts of interest to declare.