Symptom Burden, Coagulopathy and Heart Disease after Acute SARS- CoV-2 Infection in Primary Practice - Results from the Study of HEarT DiseAse and ImmuNiTy After COVID-19 in Ireland (SETANTA) (preprint)

Purpose: The aim of SETANTA (Study of HEarT DiseAse and ImmuNiTy After COVID-19 in Ireland) study was to investigate symptom burden and incidence of cardiac abnormalities after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/COVID-19 and correlate these results with immunological response and biomarkers of coagulation.  Methods: SETANTA was a prospective, single-arm observational cross-sectional study in a primary practice setting, prospectively registered with ClinicalTrials.gov identifier: NCT04823182. Patients with recent COVID-19 infection ≥6 weeks and ≤12 months before enrolment were enrolled. Primary outcomes of interest were markers of cardiac injury detected by cardiac magnetic resonance imaging (MRI), including left ventricular ejection fraction, late gadolinium enhancement and pericardial abnormalities, and serum biomarker levels. Results: 100 patients (n= 129 approached) were included, 64% were female. Mean age was 45.2 years. The median (interquartile range) time interval between COVID-19 infection and enrolment was 189 [125, 246] days. 83% had at least one persistent symptom. 96% had positive serology for prior SARS-CoV-2 infection. Late gadolinium enhancement, pericardial effusion, was present in 2.2% and 8.3% respectively; left ventricular ejection fraction was below the normal reference limit in 17.4% of patients. Von Willebrand factor antigen was elevated in 32.7% of patients. Fibrinogen and D-Dimer levels were raised in 10.2% and 11.1% of patients, respectively.  Conclusion: In a cohort of primary practice patients recently recovered from SARS-CoV-2 infection, prevalence of persistent symptoms and markers of abnormal coagulation were high, despite a lower frequency of abnormalities on cardiac MRI compared with prior reports of patients assessed in a hospital setting.  Trial Registration: Clinicaltrials.gov, NCT04823182 (prospectively registered on 30th March 2021)

Resolving the developmental mechanisms of coagulation abnormalities characteristic of SARS-CoV2 based on single-cell transcriptome analysis (preprint)

The COVID-19 outbreak caused by the SARS-CoV-2 virus has developed into a global health emergency. In addition to causing respiratory symptoms following SARS-CoV-2 infection, COVID-19-associated coagulopathy (CAC) is the main cause of death in patients with severe COVID-19. In this study, we performed single-cell sequencing analysis of the right ventricular free wall tissue from healthy donors, patients who died in the hypercoagulable phase of CAC, and patients in the fibrinolytic phase of CAC. Among these, we collected 61,187 cells, which were enriched in 24 immune cell subsets and 13 cardiac-resident cell subsets. We found that in response to SARS-CoV-2 infection, CD9highCCR2high monocyte-derived mo promoted hyperactivation of the immune system and initiated the extrinsic coagulation pathway by activating CXCR-GNB/G-PI3K-AKT. This sequence of events is the main process contributing the development of coagulation disorders subsequent to SARS-CoV-2 infection. In the characteristic coagulation disorder caused by SARS-CoV-2, excessive immune activation is accompanied by an increase in cellular iron content, which in turn promotes oxidative stress and intensifies intercellular competition. This induces cells to alter their metabolic environment, resulting in an increase in sugar uptake, such as that via the glycosaminoglycan synthesis pathway, in CAC coagulation disorders. In addition, high levels of reactive oxygen species generated in response elevated iron levels promote the activation of unsaturated fatty acid metabolic pathways in endothelial cell subgroups, including vascular endothelial cells. This in turn promotes the excessive production of the toxic peroxidation by-product malondialdehyde, which exacerbates both the damage caused to endothelial cells and coagulation disorders.

Molecular pathology of acute respiratory distress syndrome, mechanical ventilation and abnormal coagulation in severe COVID-19 (preprint)

Systemic inflammation in critically ill patients can lead to serious consequences such as acute respiratory distress syndrome (ARDS), a condition characterized by the presence of lung inflammation, edema, and impaired gas exchange, associated with poor survival. Understanding molecular pathobiology is essential to improve critical care of these patients. To this end, we use multimodal profiles of SARS-CoV-2 infected hospitalized participants to the Biobanque Quebecoise de la COVID-19 (BQC-19) to characterize endophenotypes associated with different degrees of disease severity. Proteomic, metabolomic, and genomic characterization supported a role for neutrophil-associated procoagulant activity in severe COVID-19 ARDS that is inversely correlated with sphinghosine-1 phosphate plasma levels. Fibroblast Growth Factor Receptor (FGFR) and SH2-containing transforming protein 4 (SHC4) signaling were identified as molecular features associated with endophenotype 6 (EP6). Mechanical ventilation in EP6 was associated with alterations in lipoprotein metabolism. These findings help define the molecular mechanisms related to specific severe outcomes, that can be used to identify early unfavorable clinical trajectories and treatable traits to improve the survival of critically ill patients.

Association of mortality and aspirin use for COVID-19 residents at VA Community Living Center Nursing Homes (preprint)

Background/Objectives: Coronavirus disease 2019 (COVID-19) is associated with a hypercoagulable state and increased thrombotic risk in infected individuals. Several complex and varied coagulation abnormalities were proposed for this association1 .Acetylsalicylic acid(ASA, aspirin) is known to have inflammatory, antithrombotic properties and its use was reported as having potency to reduce RNA synthesis and replication of some types of coronaviruses including human coronavirus-299E (CoV-229E) and Middle East Respiratory Syndrome (MERS)-CoV 2,3. We hypothesized that chronic low dose aspirin use may decrease COVID-19 mortality relative to ASA non-users. Methods: This is a retrospective, observational cohort analysis of residents residing at Veterans Affairs Community Living Centers from December 13, 2020, to September 18, 2021, with a positive SARS-CoV-2 PCR test. Low dose aspirin users had low dose (81mg) therapy (10 of 14 days) prior to the positive COVID date and were compared to aspirin non-users (no ASA in prior 14 days). The primary outcome was mortality at 30 and 56 days post positive test and hospitalization within 14 days of positive test result. Results: We identified 1.823 residents who had SARS-CoV-2 infection and 1,687 residents were eligible as a final analytic sample after excluding high dose and intermittent/partial dose aspirin users. Overall mean age was 72.28+/-11.66 years and 3.3% (n=67) female in the final analytic sample. Among the 511 (30.3%) residents taking chronic low dose aspirin, 30-day mortality after an initial SARS-CoV-2 test establishing infection was 6.46% (n=33) compared to 10.29% (n=121) of non-users (SMD >0.1). 56-day mortality after initial SARS-CoV-2 test establishing infection was 9.0% (n=46) compared to 13.18% (n=155) not taking low dose aspirin (SMD >0.1). Cox proportional hazards model showed that aspirin use was independently associated with a reduced risk of 30 days of mortality (adjusted HR, 0.60, 95% CI, 0.40-0.90) and 56 days of mortality (adjusted HR, 0.67, 95% CI, 0.47-0.95) Conclusion: In this retrospective observational study of VA Community Living Center residents infected with SARS-CoV-2, low dose aspirin use for primary or secondary prevention of cardiovascular events is associated with lower COVID-19 mortality and fewer breakthrough cases. Although additional randomized controlled trials are required to understand these associations and the potential implications more fully for improving care, aspirin remains a medication with known side effects and clinical practice should not change based on these findings.

Pilot study to evaluate hypercoagulation and inflammation using rotational thromboelastometry and calprotectin in COVID-19 patients. (preprint)

IntroductionAbnormal coagulation and inflammation are hallmarks of SARs-COV-19. Stratifying affected patients on admission to hospital may help identify those who are risk of developing severe disease early on. ROTEM is a point of care test that can be used to measure abnormal coagulation and calprotectin is a measure of inflammation. AimAssess if ROTEM can measure hypercoagulability on admission and identify those who will develop severe disease early on. Assess if calprotectin can measure inflammation and if there is a correlation with ROTEM and calprotectin. MethodsCOVID-19 patients were recruited on admission and ROTEM testing was undertaken daily for a period of 7 days. Additionally inflammatory marker calprotectin was also tested. Results33 patients were recruited to the study out of which 13 were admitted to ITU and 20 were treated on the ward. ROTEM detected a hypercoagulable state on admission but did not stratify between those admitted to a ward or escalated to ITU. Calprotectin levels were raised but there was no statistical difference (p=0.73) between groups. Significant correlations were observed between FIBA5 (p<0.00), FIBCFT (p<0.00), FIBMCF (p<0.00) and INMCF (p<0.00) and calprotectin. ConclusionCOVID19 patients were hypercoagulable in admission. The correlations between ROTEM and calprotectin underline the interactions between inflammation and coagulation.

Vascular dysregulation following SARS-CoV-2 infection involves integrin signaling through a VE-Cadherin mediated pathway (preprint)

The vascular barrier is heavily injured following SARS-CoV-2 infection and contributes enormously to life-threatening complications in COVID-19. This endothelial dysfunction is associated with the phlogistic phenomenon of cytokine storms, thrombotic complications, abnormal coagulation, hypoxemia, and multiple organ failure. The mechanisms surrounding COVID-19 associated endotheliitis have been widely attributed to ACE2-mediated pathways. However, integrins have emerged as possible receptor candidates for SARS-CoV-2, and their complex intracellular signaling events are essential for maintaining endothelial homeostasis. Here, we showed that the spike protein of SARS-CoV-2 depends on its RGD motif to drive barrier dysregulation through hijacking integrin V{beta}3. This triggers the redistribution and internalization of major junction protein VE-Cadherin which leads to the barrier disruption phenotype. Both extracellular and intracellular inhibitors of integrin V{beta}3 prevented these effects, similarly to the RGD-cyclic peptide compound Cilengitide, which suggests that the spike protein - through its RGD motif - binds to V{beta}3 and elicits vascular leakage events. These findings support integrins as an additional receptor for SARS-CoV-2, particularly as integrin engagement can elucidate many of the adverse endothelial dysfunction events that stem from COVID-19.

Capturing a crucial 'disorder-to-order transition' at the heart of the coronavirus molecular pathology - triggered by highly persistent, interchangeable salt-bridges (preprint)

The COVID-19 origin debate has greatly been influenced by Genome comparison studies of late, revealing the seemingly sudden emergence of the Furin-Like Cleavage Site at the S1/S2 junction of the SARS-CoV-2 Spike (FLCS_Spike) containing its 681_PRRAR_685 motif, absent in other related respiratory viruses. Being the rate-limiting (i.e., the slowest) step, the host Furin cleavage is instrumental in the abrupt increase in transmissibility in COVID-19, compared to earlier onsets of respiratory viral diseases. In such a context, the current paper entraps a disorder-to-order transition of the FLCS_Spike (concomitant to an entropy arrest) upon binding to Furin. The interaction clearly seems to be optimized for a more efficient proteolytic cleavage in SARS-CoV-2. The study further shows the formation of dynamically interchangeable and persistent networks of salt-bridges at the Spike-Furin interface in SARS-CoV-2 involving the three arginines (R682, R683, R685) of the FLCS_Spike with several anionic residues (E230, E236, D259, D264, D306) coming from Furin, strategically distributed around its catalytic triad. Multiplicity and structural degeneracy of plausible salt-bridge network archetypes seems the other key characteristic features of the Spike-Furin binding in SARS-CoV-2 allowing the system to breathe - a trademark of protein disorder transitions. Interestingly, with respect to the homologous interaction in SARS-CoV (2002/2003) taken as a baseline, the Spike-Furin binding events generally in the coronavirus lineage seems to have a preference for ionic bond formation, even with lesser number of cationic residues at their potentially polybasic FLCS_Spike patches. The interaction energies are suggestive of a characteristic metastabilities attributed to Spike-Furin interactions generally to the coronavirus lineage - which appears to be favorable for proteolytic cleavages targeted at flexible protein loops. The current findings not only offer novel mechanistic insights into the coronavirus molecular pathology and evolution but also add substantially to the existing theories of proteolytic cleavages.

The influence of new SARS-CoV-2 variant Omicron (B.1.1.529) on vaccine efficacy, its correlation to Delta Variants: a computational approach (preprint)

The newly discovered COVID variant B.1.1.529 in Botswana has more than 30 mutations in spike and many other in non-spike proteins, far more than any other SARS-CoV-2 variant accepted as a variant of concern by the WHO and officially named Omicron, and has sparked concern among scientists and the general public. Our findings provide insights into structural modification caused by the mutations in the Omicrons receptor-binding domain and look into the effects on interaction with the hosts neutralising antibodies CR3022, B38, CB6, P2B-2F6, and REGN, as well as ACE2R using an in silico approach. We have employed secondary structure prediction, structural superimposition, protein disorderness, molecular docking, and MD simulation to investigate host-pathogen interactions, immune evasion, and transmissibility caused by mutations in the RBD region of the spike protein of the Omicron variant and compared it to the Delta variants (AY.1, AY.2, & AY.3) and wild type. Computational analysis revealed that the Omicron variant has a higher binding affinity for the human ACE2 receptor than the wild and Delta (AY.1 and AY.2 strains), but lower than the Delta AY.3 strain. MD simulation and docking analysis suggest that the omicron and Delta AY.3 were found to have relatively unstable and compact RBD structures and hampered interactions with antibodies more than wild and Delta (AY.1 and AY.2), which may lead to relatively more pathogenicity and antibody escape. In addition, we observed lower binding affinity of Omicron for human monoclonal antibodies (CR3022, B38, CB6, and P2B2F6) when compared to wild and Delta (AY.1 & AY.2). However, the binding affinity of Omicron RBD variants for CR3022, B38, and P2B2F6 antibodies is lower as compared to Delta AY.3, which might promote immune evasion and reinfection and needs further experimental investigation.

Dysregulation of circulating protease activity in Covid-19-associated superinfection (preprint)

Infection by SARS-CoV-2 and subsequent COVID-19 can cause viral sepsis and septic shock. Several complications have been observed in patients admitted to the intensive care unit (ICU) with COVID-19, one of those being bacterial superinfection. Based on prior evidence that dysregulated systemwide proteolysis is associated with death in bacterial septic shock, we investigated whether protease activity and proteolysis could be elevated in COVID-19-induced sepsis with bacterial superinfection. In particular, we sought to assess the possible implications on the regulation of protein systems, such as for instance the proteins and enzymes involved in the clotting cascade. Blood samples collected at multiple time points during the ICU stay of four COVID-19 patients were analyzed to quantify: a) the circulating proteome and peptidome by mass spectrometry; b) plasma enzymatic activity of trypsin-like substrates and five clotting factors (plasmin, thrombin, factor VII, factor IX, factor X) by a fluorogenic assay. Of the four patients, one was diagnosed with bacterial superinfection on day 7 after beginning of the study and later died. The other three patients all survived (ICU length-of-stay 11.25+-6.55 days, hospital stay of 15.25+-7.18 days). Spikes in protease activity (factor VII, trypsin-like activity) were detected on day 7 for the patient who died. Corresponding increases in the total intensity of peptides derived by hydrolysis of plasma proteins, especially of fibrinogen degradation products, and a general reduction of coagulation proteins, were measured as well. A downregulation of endogenous enzymatic inhibitors, in particular trypsin inhibitors, characterized the non-surviving patient throughout her ICU stay. Enzymatic activity was stable in the patients who survived. Our study highlights the potential of multiomics approaches, combined with quantitative analysis of enzymatic activity, to i) shed light on proteolysis as a possible pathological mechanism in sepsis and septic shock, including COVID-19-induced sepsis; ii) provide additional insight into malfunctioning protease-mediated systems, such as the coagulation cascade; and iii) describe the progression of COVID-19 with bacterial superinfection.

Anti-prothrombin autoantibodies enriched after infection with SARS-CoV-2 and influenced by strength of antibody response against SARS-CoV-2 proteins (preprint)

Antiphospholipid antibodies (aPL), assumed to cause antiphospholipid syndrome (APS), are notorious for their heterogeneity and detect phospholipids and phospholipid-binding proteins. The persistent presence of Lupus anticoagulant and/or aPL against cardiolipin and/or {beta}2 glycoprotein I have been shown to be independent risk factors for vascular thrombosis and pregnancy morbidity in APS. Among others, viral infections have been proposed to trigger the production of aPL while mostly being considered non-pathogenic. Yet, the potential pathogenicity of infection-associated aPL has gained momentum since an increasing number of patients infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been described with coagulation abnormalities and hyperinflammation, together with the presence of aPL. Here, we present data from a multicentric, mixed-severity study including three cohorts of individuals who contracted SARS-CoV-2 as well as non-infected blood donors. We simultaneously measured 10 different criteria and non-criteria aPL (IgM and IgG) by using a line immunoassay. Further, IgG antibody response against three SARS-CoV-2 proteins was investigated using tripartite automated blood immunoassay technology. Our analyses revealed that select non-criteria aPL are enriched concomitant to or after an infection with SARS-CoV-2. Linear mixed-effect models suggest an association of aPL to prothrombin (PT) with the strength of the antibody response against SARS-CoV-2 and further influenced by SARS-CoV-2 disease severity and sex of the individuals. In conclusion, our study is the first to report an association between disease severity, anti-SARS-CoV-2 immunoreactivity and aPL against PT in patients with SARS-CoV-2.

Are TFPI and β-TG indicators of severity in COVID-19? (preprint)

Background: Thromboembolic complications have been reported as a life-theratening major pathologic event in severe coronavirus disease 2019 (COVID-19) affecting the lung as evidenced by autopsy reports of alveolar damage and pulmonary intravascular microthrombi. The new coronavirus (CoV) does not appear to have intrinsic procoagulant effects itself. The coagulation changes in COVID-19 are likely a result of the inflammatory response. Significant inflammation is present in COVID-19, based on elevated interleukin-6 (IL-6). This inflammation associated with COVID-19 results in coagulopathy, based on elevated D-dimer (DD). An endotheliopathy appears to contribute to microvascular thrombosis in COVID-19. The aim of this study is to confirm the coagulation abnormalities in 100 severe COVID-19 patients having lung involvement and their association with the severity and prognosis. Methods: Inflammation, endothelial and coagulation indicators were performed and compared between severe and mild disease. Results: IL-6 and TNF-a, and TF and VWF,  exceeded in severe COVID-19 patients as well as D-dimer, TAT, and Fibrinogen. As PF4 has a rapid removal from plasma, we also measured b-TG levels which exceeded the plasma levels of PF4  in severe COVID-19 patients as well as increased platelet adhesion was observed. Shortened CT and CFT, high MCF and low LY at 30 minutes were present in 100% of severe COVID-19 patients compared with mild COVID-19 patients. Conclusions: It is reported that TFPI is a natural anticoagulant that lowes inflammation and coagulation. Therefore, we measured TFPI levels which exceeded without shutdown of the inflammation and coagulation documenting the clinical severity of severe COVID-19 patients. 

Phosphatidylserine inside out: inflammation and coagulation abnormalities in COVID-19 (preprint)

COVID-19, caused by the virus SARS-CoV-2, is a significant challenge to health systems worldwide. Its severity appears to be most likely caused by acute inflammation and widespread intravascular coagulation. A recent review examines the molecular basis underlying coagulation and inflammation in COVID-19. Phosphatidylserine (PtdSer) typically lies in the inner leaflet of the plasma membrane in healthy cells. Under some physiological conditions, PtdSer exposure on the outer leaflet of platelets promotes coagulation factor aggregation. However, in pathophysiological conditions, PtdSer exposure may cause excessive activation of coagulation and in viral infections, this may increase infectivity and viral spread. Evidence suggests that SARS-CoV-2 exposure may upregulate PtdSer on cell surfaces throughout the body. causing disseminated coagulation throughout the body. In addition, the virus may upregulate the activity of the protein ADAM-17, which has roles in protecting the heart but can also promote inflammation. This level of inflammation can be connected to acute respiratory distress syndrome (ARDS), another leading cause of death among patients with COVID-19. Although more clinical evidence is needed to confirm a causal connection between SARS-CoV-2 infection and PtdSer translocation better understanding of these mechanisms will help to identify new therapeutic targets against COVID-19.

The role of rotational thromboelastometry (ROTEM) in understanding the coagulation problems in COVID-19 associated critical illness (preprint)

In critically ill patients with COVID-19, concomitant abnormalities of coagulation have been seen with an unusually high incidence. Standard coagulation tests are limited in their ability accurately to reflect the severity of the pro-thrombotic phenotype observed in severe COVID-19 infections. In this narrative review we consider the role of rotational thromboelastometry (ROTEM) as a near bedside test allowing a more comprehensive assessment of haemostatic function in the context of COVID-19 infection. Comprehensive literature search was conducted on PubMed, revealing 13 publications on the subject. The coagulopathy of this disease process appears to be insufficiently represented with often normal conventional coagulation test parameters. Whilst not the perfect substitute for in vivo coagulation, studies utilising rotational thromboelastometry assays in COVID-19 patients have demonstrated increased maximum clot firmness (consistent with hyper-coagulability) and reduced maximum lysis (consistent with “fibrinolytic shutdown”). ROTEM appears to be a possible tool for risk stratification and to monitor the potential modulation of fibrinogen-dependent coagulation processes with enhanced anti-coagulation strategies. Precisely how these coagulation abnormalities can be modified by optimum, individualised medical interventions to improve clinical outcome, however, remains unclear.

COVID-19 Associated Coagulopathy Is a Reversible Phenomenon - 3-Month Follow Up Reveals Normalization of Coagulation Status Associated With Complete Venous Recanalization in Patients After Severe COVID-19 (preprint)

Background: COVID 19 is associated with a hypercoagulable state and frequent thromboembolic complications. For how long this acquired abnormality lasts potentially requiring preventive measures, such as anticoagulation remains to be delineated.Methods: We used viscoelastic rotational thrombelastometry (ROTEM) in a single center cohort of 13 critical ill patients and performed follow up examinations three months after discharge from ICU.Results: We found clear signs of a hypercoagulable state due to severe hypofibrinolysis and a high rate of thromboembolic complications during the phase of acute illness. Three month follow up revealed a normalization of the initial coagulation abnormality together without evidence of venous thrombosis in all thirteen patients. Conclusion: In our cohort the coagulation profile was completely normalized three months after COVID-19. It thus appears reasonable that anticoagulation can be discontinued beyond this timepoint in patients with complete venous reperfusion.

Identification of potential coagulation pathway abnormalities in SARS-Cov-2 infection; insights from bioinformatics analysis (preprint)

Abnormal coagulation parameters have been explored in a significant number of severe COVID-19 patients, linked to poor prognosis and increased risk of organ failure. Here, to uncover the potential abnormalities in coagulation pathways, we analyzed the RNA-seq data (GEO147507) obtained from the treatment of three pulmonary epithelial cell lines with SARS-CoV-2. The significant differentially expressed genes (DEGs) were subjected to Enrichr database for KEGG pathway enrichment analysis and gene ontology (GO) functional annotation. The STRING database was used to generate PPI networks for identified DEGs. We found three upregulated procoagulant genes (SERPINE1, SERPINA5, and SERPINB2) belong to the serine protease inhibitor (serpin) superfamily that inhibit tissue plasminogen activator (t-PA) and urokinase plasminogen activator (u-PA) in the fibrinolysis process. In conclusion, we suggest the fibrinolysis process, especially the blockage of t-PA and u-PA inhibitors, a potential target for more study in treating coagulopathy in severe COVID-19 cases.

The Contribution of Endothelial Dysfunction in Systemic Injury Subsequent to SARS-Cov-2 Infection (preprint)

Abstract: SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) infection is associated, alongside with lung infection and respiratory disease, to cardiovascular dysfunction that occurs at any stage of the disease. This includes ischemic heart disease, arrhythmias, and cardiomyopathies. The common pathophysiological link between SARS-CoV-2 infection and the cardiovascular events is represented by coagulation abnormalities and disruption of factors released by endothelial cells which contribute in maintaining the blood vessels into an anti-thrombotic state. Thus, early alteration of the functionality of endothelial cells, which may be found soon after SARS-CoV-2 infection, seems to represent the major target of SARS CoV-2 disease state and accounts for the systemic vascular dysfunction that leads to detrimental effect in terms of hospitalization and death accompanying the disease. In particular, the molecular interaction of SARS-CoV-2 with ACE2 receptor located in endothelial cell surface, either at the pulmonary and systemic level, leads to early impairment of endothelial function which, in turn, is followed by vascular inflammation and thrombosis of peripheral blood vessels. This highlights systemic hypoxia and further aggravates the vicious circle that compromises the development of the disease leading to irreversible tissue damage and death of patients with SARS CoV-2 infection. The review aims to assess some recent advances to define the crucial role of endothelial dysfunction in the pathogenesis of vascular complications accompanying SARS-CoV-2 infection. In particular, the molecular mechanisms associated to the interaction of SARS CoV-2 with ACE2 receptor located on the endothelial cells are highlighted to support its role in compromising endothelial cell functionality. Finally, the consequences of endothelial dysfunction in enhancing pro-inflammatory and pro-thrombotic effects of SARS-CoV-2 infection are assessed in order to identify early therapeutic interventions able to reduce the impact of the disease in high-risk patients.

The relationship between cardiac injury, inflammation and coagulation in predicting COVID-19 outcome (preprint)

Introduction: High sensitivity troponin T (hsTnT) is a strong predictor of adverse outcome during SARS-CoV-2 infection. However, its determinants remain partially unknown. We aimed to assess the relationship between severity of inflammatory response/coagulation abnormalities and hsTnT in Coronavirus Disease 2019 (COVID-19). We then explored the relevance of these pathways in defining mortality and complications risk and the potential effects of the treatments to attenuate such risk.Methods: In this single-center, prospective, observational study we enrolled 266 consecutive patients hospitalized for SARS-CoV-2 pneumonia. Primary endpoint was in-hospital COVID-19 mortality. Results: hsTnT, even after adjustment for confounders, was associated with mortality. D-dimer and CRP presented stronger associations with hsTnT than PaO2. Changes of hsTnT, D-dimer and CRP were related but only D-dimer was associated with mortality. Moreover, low molecular weight heparin showed attenuation of the mortality in the whole population, particularly in subjects with higher hsTnT.Conclusions: D-dimer possessed a strong relationship with hsTnT and mortality. Anticoagulation treatment showed greater benefits with regard to mortality. These findings suggest a major role of SARS-CoV-2 coagulopathy in hsTnT elevation and its related mortality in COVID-19. A better understanding of the mechanisms related to COVID-19 might pave the way to therapy tailoring in these high-risk individuals.

Endothelial Cells and SARS-CoV-2: An Intimate Relationship (preprint)

Angiotensin-converting enzyme 2 (ACE2) is an important player of the renin-angiotensin-aldosterone system (RAAS) in regulating the conversion of angiotensin II into angiotensin (1-7). While expressed on the surface of human cells, such as lung, heart, kidney, neurons, and endothelial cells (EC), ACE2 is the entry receptor for SARS-CoV-2. Here, we would like to highlight that ACE2 is predominant on the EC membrane. Many of coronavirus disease 2019 (COVID-19) symptoms have been associated with the large recruitment of immune cells, directly affecting EC. Additionally, cytokines, hypoxia, and complement activation can trigger the activation of EC leading to the coagulation cascade. The EC dysfunction plus the inflammation due to SARS-CoV-2 infection may lead to abnormal coagulation, actively participating in thrombo-inflammatory processes resulting in vasculopathy and indicating poor prognosis in patients with COVID-19. Considering the intrinsic relationship between EC and the pathophysiology of SARS-CoV-2, EC-associated therapies such as anticoagulants, fibrinolytic drugs, immunomodulators, and molecular therapies have been proposed. In this review, we will discuss the role of EC in the lung inflammation and edema, in the disseminate coagulation process, ACE2 positive cancer patients, and current and future EC-associated therapies to treat COVID-19.

Increased number of pulmonary megakaryocytes in COVID-19 patients with diffuse alveolar damage. An autopsy study with clinical correlation and review of the literature. (preprint)

Megakaryocytes are normally present in the lung where they play a role in platelet homeostasis. The latter are well known to participate in the pathogenesis of lung damage, particularly in acute lung injury. Although megakaryocytes are usually not mentioned as a characteristic histopathologic finding associated to acute pulmonary injury, a few studies point out that their number is increased in the lungs of patients with diffuse alveolar damage. In this autopsy study we have observed a relevant number of pulmonary megakaryocytes in COVID-19 patients dying with acute respiratory distress syndrome. We have studied pulmonary tissue samples of 18 patients most of which died after prolonged disease and use of mechanical ventilation. Most samples showed fibroproliferative or fibrotic diffuse alveolar damage and an increased number of megakaryocytes. In six, thrombi of the pulmonary microcirculation were seen. We compare our findings with previous published autopsy reports, mainly focusing on the description of megakaryocytes. Our patients showed abnormal coagulation parameters with high levels of fibrinogen, D-dimers and variable thrombocytopenia. Since the lung is considered an active site of megakariopoiesis, a prothrombotic status leading to platelet activation, aggregation and consumption may trigger a compensatory pulmonary response. An increased number of pulmonary megakaryocytes suggests and supports a relation with the thrombotic events so often seen in COVID-19. Regardless of its etiology, future studies of patients dying with acute pulmonary injury should include pulmonary megakaryocytes as a histologic variable of interest.

Coagulopathy in patients with Coronavirus Disease 2019 (COVID-19): A systematic review and meta-analysis (preprint)

Patients with COVID-19 frequently manifest coagulation abnormalities and thrombotic events. In this meta-analysis, we aimed to explore the role of coagulopathy on the severity differences in patients with COVID-19. We conducted systematic literature search via Pubmed, Embase, Cochrane, WanFang Database, CNKI, and medRxiv from December 1, 2019 to May 1, 2020, to identify all original studies that reports on coagulation parameters (D-dimer, PLT, PT, APTT, and FIB) during COVID-19 infection. Thereafter, we compared the coagulation parameters between less severe and more severe cases. All Statistical analyses were performed via Stata14.0 software. A total of 3,952 confirmed COVID-19 infected patients were included from 25 studies. Patients with severe COVID-19 infection exhibited significantly higher levels of D-dimer, PT, and FIB (SMD 0.83, 95% CI: 0.70-0.97, I2 56.9%; SMD 0.39, 95% CI: 0.14-0.64, I2 77.9%; SMD 0.35, 95% CI: 0.17-0.53, I2 42.4% respectively). However, difference in PLT and APTT levels between less severe and more severe patients was not statistically significant (SMD-0.26, 95% CI: -0.56-0.05, I2 82.2%; SMD-0.14,95% CI: -0.45-0.18, I2 75.5% respectively) This meta-analysis revealed coagulopathy is associated with the severity of COVID-19. Notably, D-dimer, PT, and FIB are the dominant parameters that should be considered in evaluating coagulopathy in COVID-19 patients.