Coagulation Abnormalities and Thrombosis in Patients Infected With SARS-CoV-2 and Other Pandemic Viruses

Role of microbiota-derived corisin in coagulation activation during SARS-CoV-2 infection

BACKGROUND

Coagulopathy is a major cause of morbidity and mortality in COVID-19 patients. Hypercoagulability in COVID-19 results in deep vein thrombosis, thromboembolic complications, and diffuse intravascular coagulation. Microbiome dysbiosis influences the clinical course of COVID-19. However, the role of dysbiosis in COVID-19-associated coagulopathy is not fully understood.

OBJECTIVES

The present study tested the hypothesis that the microbiota-derived proapoptotic corisin is involved in the coagulation system activation during SARS-CoV-2 infection.

METHODS

This cross-sectional study included 47 consecutive patients who consulted for symptoms of COVID-19. A mouse acute lung injury model was used to recapitulate the clinical findings. A549 alveolar epithelial, THP-1, and human umbilical vein endothelial cells were used to evaluate procoagulant and anticoagulant activity of corisin.

RESULTS

COVID-19 patients showed significantly high circulating levels of corisin, thrombin-antithrombin complex, D-dimer, tumor necrosis factor-α, and monocyte-chemoattractant protein-1 with reduced levels of free protein S compared with healthy subjects. The levels of thrombin-antithrombin complex, D-dimer, and corisin were significantly correlated. A monoclonal anticorisin-neutralizing antibody significantly inhibited the inflammatory response and coagulation system activation in a SARS-CoV-2 spike protein-associated acute lung injury mouse model, and the levels of corisin and thrombin-antithrombin complex were significantly correlated. In an in vitro experiment, corisin increased the tissue factor activity and decreased the anticoagulant activity of thrombomodulin in epithelial, endothelial, and monocytic cells.

CONCLUSION

The microbiota-derived corisin is significantly increased and correlated with activation of the coagulation system during SARS-CoV-2 infection, and corisin may directly increase the procoagulant activity in epithelial, endothelial, and monocytic cells.

Combined coagulation and inflammation markers as predictors of venous thrombo-embolism and death in COVID-19

Background

The COVID-19 pandemic related to SARS-CoV-2 virus was responsible for global pandemic. The severe form of the disease was linked to excessive activation of immune pathways together with a systemic cytokine storm response and thrombotic venous or arterial complications. Factors predicting severe outcomes including venous and/or pulmonary thrombosis (VT) and death were identified, but the prognostic role of their combination was not addressed extensively.

Objectives

We investigated the role of prognostic factors from the coagulation or inflammatory pathways to better understand the outcome of the disease.

Methods

For this, we prospectively studied 167 SARS-CoV-2-positive patients from admission in intensive care units (ICU) or emergency departments from four academic hospitals over a 14-month period. Besides standard biology, we assessed serum concentrations of inflammatory markers, coagulation factors and peripheral blood cells immunophenotyping.

Results

Thirty-nine patients (23.3%) developed VT and 30 patients (18%) died. By univariate analysis, C-reactive protein (CRP) level > 150 mg/L, interleukin-6 (IL-6) ≥ 20 pg/mL, D-dimers > 1,500 μg/L, ADAMTS13 activity ≤ 50%, Von.

Conclusion

A combination of coagulation and inflammatory markers can refine the prognostication of severe outcome in COVID-19, and could be useful for the initial evaluation of other types of viral infection.

Nonlinear relationship between platelet count and 30-day in-hospital mortality in ICU acute respiratory failure patients: a multicenter retrospective cohort study

BACKGROUND

Limited evidence exists regarding the link between platelet count and 30-day in-hospital mortality in acute respiratory failure (ARF) patients. Thus, this study aims to investigate this association among ICU patients experiencing acute respiratory failure.

METHODS

We conducted a retrospective cohort study across multiple centers, utilizing data from the US eICU-CRD v2.0 database covering 22,262 patients with ARF in the ICU from 2014 to 2015. Our aim was to investigate the correlation between platelet count and 30-day in-hospital mortality using binary logistic regression, subgroup analyses, and smooth curve fitting.

RESULTS

The 30-day in-hospital mortality rate was 19.73% (4393 out of 22,262), with a median platelet count of 213 × 109/L. After adjusting for covariates, our analysis revealed an inverse association between platelet count and 30-day in-hospital mortality (OR = 0.99, 95% CI 0.99, 0.99). Subgroup analyses supported the robustness of these findings. Furthermore, a nonlinear relationship was identified between platelet count and 30-day in-hospital mortality, with the inflection point at 120 × 109/L. Below the inflection point, the effect size (OR) was 0.89 (0.87, 0.91), indicating a significant association. However, beyond this point, the relationship was not statistically significant.

CONCLUSION

This study establishes a clear negative association between platelet count and 30-day in-hospital mortality among ICU patients with ARF. Furthermore, we have identified a nonlinear relationship with saturation effects, indicating that among ICU patients with acute respiratory failure, the lowest 30-day in-hospital mortality rate occurs when the baseline platelet count is approximately 120 × 109/L.

Overall haemostatic potential assay for prediction of outcomes in venous and arterial thrombosis and thrombo-inflammatory diseases

Thromboembolic diseases including arterial and venous thrombosis are common causes of morbidity and mortality globally. Thrombosis frequently recurs and can also complicate many inflammatory conditions through the process of 'thrombo-inflammation,' as evidenced during the COVID-19 pandemic. Current candidate biomarkers for thrombosis prediction, such as D-dimer, have poor predictive efficacy. This limits our capacity to tailor anticoagulation duration individually and may expose lower risk individuals to undue bleeding risk. Global coagulation assays, such as the Overall Haemostatic Potential (OHP) assay, that investigate fibrin generation and fibrinolysis, may provide a more accurate and functional assessment of hypercoagulability. We present a review of fibrin's critical role as a central modulator of thrombotic risk. The results of our studies demonstrating the OHP assay as a predictive biomarker in venous thromboembolism, chronic renal disease, diabetes mellitus, post-thrombotic syndrome, and COVID-19 are discussed. As a comprehensive and global measurement of fibrin generation and fibrinolytic capacity, the OHP assay may be a valuable addition to future multi-modal predictive tools in thrombosis.

Extracellular vesicles alter trophoblast function in pregnancies complicated by COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and resulting coronavirus disease (COVID-19) causes placental dysfunction, which increases the risk of adverse pregnancy outcomes. While abnormal placental pathology resulting from COVID-19 is common, direct infection of the placenta is rare. This suggests that pathophysiology associated with maternal COVID-19, rather than direct placental infection, is responsible for placental dysfunction and alteration of the placental transcriptome. We hypothesized that maternal circulating extracellular vesicles (EVs), altered by COVID-19 during pregnancy, contribute to placental dysfunction. To examine this hypothesis, we characterized maternal circulating EVs from pregnancies complicated by COVID-19 and tested their effects on trophoblast cell physiology in vitro . We found that the gestational timing of COVID-19 is a major determinant of circulating EV function and cargo. In vitro trophoblast exposure to EVs isolated from patients with an active infection at the time of delivery, but not EVs isolated from Controls, altered key trophoblast functions including hormone production and invasion. Thus, circulating EVs from participants with an active infection, both symptomatic and asymptomatic cases, can disrupt vital trophoblast functions. EV cargo differed between participants with COVID-19 and Controls, which may contribute to the disruption of the placental transcriptome and morphology. Our findings show that COVID-19 can have effects throughout pregnancy on circulating EVs and circulating EVs are likely to participate in placental dysfunction induced by COVID-19.

[COVID-19 in the intensive care unit]

The acute respiratory failure as well as ARDS (acute respiratory distress syndrome) have challenged clinicians since the initial description over 50 years ago. Various causes can lead to ARDS and therapeutic approaches for ARDS/ARF are limited to the support or replacement of organ functions and the prevention of therapy-induced consequences. In recent years, triggered by the SARS-CoV-2 pathogen, numerous cases of acute lung failure (C-ARDS) have emerged. The pathophysiological processes of classical ARDS and C-ARDS are essentially similar. In their final stages of inflammation, both lead to a disruption of the blood-air barrier. Treatment strategies for C-ARDS, like classical ARDS, focus on supporting or replacing organ functions and preventing consequential damage. This article summarizes the treatment strategies in the intensive care unit.

Beyond Borders of the Cell: How Extracellular Vesicles Shape COVID-19 for People with Cystic Fibrosis

The interaction between extracellular vesicles (EVs) and SARS-CoV-2, the virus causing COVID-19, especially in people with cystic fibrosis (PwCF) is insufficiently studied. EVs are small membrane-bound particles involved in cell-cell communications in different physiological and pathological conditions, including inflammation and infection. The CF airway cells release EVs that differ from those released by healthy cells and may play an intriguing role in regulating the inflammatory response to SARS-CoV-2. On the one hand, EVs may activate neutrophils and exacerbate inflammation. On the other hand, EVs may block IL-6, a pro-inflammatory cytokine associated with severe COVID-19, and protect PwCF from adverse outcomes. EVs are regulated by TGF-β signaling, essential in different disease states, including COVID-19. Here, we review the knowledge, identify the gaps in understanding, and suggest future research directions to elucidate the role of EVs in PwCF during COVID-19.

Critical roles of PAI-1 in lipopolysaccharide-induced acute lung injury

PURPOSE

Plasminogen activator inhibitor-1 (PAI-1) is the main inhibitor of fibrinolytic systems. The effect of PAI-1 on inflammatory response is still inconsistent. Our study was conducted to investigate its effects on inflammation to clarify the role of PAI-1 in acute lung injury (ALI) induced by lipopolysaccharide (LPS).

MATERIAL AND METHODS

ALI models were established in wild-type (WT) and PAI-1 knockout (KO) mice by LPS intervention for 48 ​h. Lung histopathology, wet-dry ratio, total cell count and TNF-α concentration in bronchoalveolar lavage fluid (BALF), and inflammation related proteins were detected. Flow cytometry was used to sort neutrophils, macrophages, regulatory T cells (Treg) and T helper cell 17 (Th17). RNA sequencing was performed to find differentially expressed genes. Masson staining and immunohistochemistry were used to analyze pulmonary fiber deposition and proliferation.

RESULTS

Compared with ALI (WT) group, the wet-dry ratio, the total number of BALF cells, the concentration of TNF-α in BALF, and the expression of pp65 in the lung tissue was increased in ALI (PAI-1 KO) group, with increased proportion of neutrophils, decreased proportion of macrophages and decreased proportion of Treg/Th17 in the lung tissue. Collagen fiber deposition and PCNA expression were lighter in ALI (PAI-1 KO) group than ALI (WT) group. PPI analysis showed that PAI-1 was closely related to TNF, IL-6, IL-1β, Smad2/3 and mainly concentrated in the complement and coagulation system, TNF-α and IL-17 signaling pathways.

CONCLUSIONS

PAI-1 KO could aggravate ALI induced by LPS at 48 ​h. PAI-1 may be an important target to improve the prognosis of ALI.

Thrombosis in Critically Ill Influenza Patients: Incidence and Risk Factors

Influenza infection is associated with a risk of thrombosis. Whether factors associated with reduced thrombosis might also be associated with reduced risk in patients with severe influenza is unknown. To investigate risk factors associated with thrombosis in patients with severe influenza. We used a cohort data set to identify adults diagnosed with severe influenza. Univariable and multivariable logistic regression models explored potential risk factors for thrombosis events in patients with severe influenza. Cox regression analysis was used to examine the risk factors for mortality in patients with severe influenza. A total of 854 patients with severe influenza were included in the analysis. The incidence of VTE was 9.37% (80/854). Multivariable regression analysis showed that previous aspirin medication (OR: 0.37; 95%CI: 0.14-0.84; P = .029) could reduce the risk factor of thrombosis in patients with severe influenza. Compared with patients in the non-thrombosis group, patients in the thrombosis group required more mechanical ventilation (P < .001), tracheostomy (P < .001), ECMO (P = .046), and high-frequency ventilation (P = .004). The incidence of co-infection was higher in the thrombosis group compared to the non-thrombosis group (P = .025). Univariable Cox regression analysis showed that previous aspirin medication (HR 0.52, 95%CI: 0.33-0.82, P = .005) and previous statin medication (HR 0.54, 95%CI: 0.34-0.87, P = .011) were risk factors for 60-day mortality in patients with severe influenza. Patients with severe influenza are at high risk for thrombosis. The effect of aspirin on thrombosis in patients with severe influenza needs further investigation.

COVID-19 induced ischemic stroke and mechanisms of viral entry in brain and clot formation: a systematic review and current update

Background: Coronavirus disease 2019, caused by SARS-CoV-2 (SCV-2) was stated as a pandemic on March 11 2020 by World Health Organization (WHO), and since then, it has become a major health issue worldwide. It mainly attacks the respiratory system with various accompanying complications, including cardiac injury, renal failure, encephalitis and Stroke.Materials and Methods: The current systematic review has been compiled to summarize the available literature on SCV-2 induced ischemic Stroke and its subtypes. Further, the mechanisms by which the virus crosses the blood-brain barrier (BBB) to enter the brain have also been explored. The role of CRP and D-dimer as potent prognostic markers was also explored. The literature search was carried out comprehensively on Google scholar, PubMed, SCOP US, Embase and Cochrane databases by following guidelines.Results: All the studies were reviewed thoroughly by authors and disagreements were resolved by consensus and help of the senior authors. The most common subtype of the IS was found to be large artery atherosclerosis in SCV-2 induced IS. Hypertension emerged as the most significant risk factor. The mechanism resulting in elevated levels of CRP and D-dimer have also been discussed. However, there is a scarcity of definitive evidence on how SCV-2 enters the human brain. The available literature based on various studies demonstrated that SCV-2 enters through the nasopharyngeal tract via olfactory cells to olfactory neurons, astrocytes and via choroid plexus through endothelial cells. Further, disruption of gut-brain axis has been also discussed.Conclusion: Data available in the literature is not adequate to come to a conclusion. Therefore, there is a need to carry out further studies to delineate the possible association between SCV-2 induced IS.

Epidemiology, pathogenesis, and management of Coronavirus disease 2019-associated stroke

The Coronavirus disease 2019 (COVID-19) epidemic has triggered a huge impact on healthcare, socioeconomics, and other aspects of the world over the past three years. An increasing number of studies have identified a complex relationship between COVID-19 and stroke, although active measures are being implemented to prevent disease transmission. Severe COVID-19 may be associated with an increased risk of stroke and increase the rates of disability and mortality, posing a serious challenge to acute stroke diagnosis, treatment, and care. This review aims to provide an update on the influence of COVID-19 itself or vaccines on stroke, including arterial stroke (ischemic stroke and hemorrhagic stroke) and venous stroke (cerebral venous thrombosis). Additionally, the neurovascular mechanisms involved in SARS-CoV-2 infection and the clinical characteristics of stroke in the COVID-19 setting are presented. Evidence on vaccinations, potential therapeutic approaches, and effective strategies for stroke management has been highlighted.

Acute blood biomarker profiles predict cognitive deficits 6 and 12 months after COVID-19 hospitalization

Post-COVID cognitive deficits, including 'brain fog', are clinically complex, with both objective and subjective components. They are common and debilitating, and can affect the ability to work, yet their biological underpinnings remain unknown. In this prospective cohort study of 1,837 adults hospitalized with COVID-19, we identified two distinct biomarker profiles measured during the acute admission, which predict cognitive outcomes 6 and 12 months after COVID-19. A first profile links elevated fibrinogen relative to C-reactive protein with both objective and subjective cognitive deficits. A second profile links elevated D-dimer relative to C-reactive protein with subjective cognitive deficits and occupational impact. This second profile was mediated by fatigue and shortness of breath. Neither profile was significantly mediated by depression or anxiety. Results were robust across secondary analyses. They were replicated, and their specificity to COVID-19 tested, in a large-scale electronic health records dataset. These findings provide insights into the heterogeneous biology of post-COVID cognitive deficits.

Endotheliitis and cytokine storm as a mechanism of clot formation in COVID-19 ischemic stroke patients: A histopathologic study of retrieved clots

BACKGROUND

Studies during the COVID-19 pandemic have demonstrated an association between COVID-19 virus infection and the development of acute ischemic stroke, particularly large vessel occlusion (LVO). Studying the characteristics and immunohistochemistry of retrieved stroke emboli during mechanical thrombectomy for LVO may offer insights into the pathogenesis of LVO in COVID-19 patients. We examined retrieved COVID-19 emboli from the STRIP, EXCELLENT, and RESTORE registries and compared their characteristics to a control group.

METHODS

We identified COVID-positive LVO patients from the STRIP, RESTORE, and EXCELLENT studies who underwent mechanical thrombectomy. These patients were matched to a control group controlling for stroke etiology based on Trial of Org 10172 in Acute Stroke Treatment criteria. All clots were stained with Martius Scarlet Blue (MSB) along with immunohistochemistry for interleukin-6 (IL-6), C-reactive protein (CRP), von Willebrand factor (vWF), CD66b, fibrinogen, and citrullinated Histone H3. Clot composition was compared between groups.

RESULTS

Nineteen COVID-19-positive patients and 38 controls were included. COVID-19-positive patients had a significantly higher percentage of CRP and vWF. There was no difference in IL-6, fibrin, CD66b, or citrullinated Histone H3 between groups. Based on MSB staining, there was no statistically significant difference regarding the percentage of red blood cells, white blood cells, fibrin, and platelets.

CONCLUSIONS

Our study found higher concentrations of CRP and vWF in retrieved clots of COVID-19-positive stroke patients compared to COVID-19-negative controls. These findings support the potential role of systemic inflammation as indicated by elevated CRP and endothelial injury as indicated by elevated vWF as precipitating factors in thrombus development in these patients.

Changes in the Fibrinolytic System of Patients Infected with Severe Acute Respiratory Syndrome Coronavirus 2

INTRODUCTION

In this study, coagulation and fibrinolysis parameters and their association with disease severity were investigated in coronavirus disease (COVID-19) patients.

MATERIALS AND METHODS

COVID-19 patients (n = 446) admitted to our institute between 21 February 2021 and 17 March 2022, were recruited. Clinical data and staging were collected from all patients. Blood samples were collected and analyzed for several parameters of fibrinolysis and coagulation, including alpha-2-antiplasmin(α2AP) and plasminogen, thrombin activatable fibrinolysis inhibitor (TAFI), tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), D-dimer, and fibrinogen levels.

RESULTS

The TAFI, fibrinogen, and tPA levels were significantly higher in participants who died compared to that of patients who recovered (p < 0.001). However, PAI-1, tPA, and TAFI were significantly higher in patients admitted to the ICU than those of the healthy controls (p < 0.001 for PAI-1 and tPA; p = 0.0331 for TAFI). Our results showed that stage C and D COVID-19 patients had significantly higher levels of PAI-1 (p = 0.003). Furthermore, stage D COVID-19 patients had significantly higher tPA and TAFI values (p = 0.003).

CONCLUSIONS

Hypofibrinolysis was the most prevalent condition among patients with severe COVID-19. In this study, several coagulation markers were elevated, making them suitable prognostic markers for hypofibrinolysis.

Molecular Mechanisms Responsible for Diabetogenic Effects of COVID-19 Infection-Induction of Autoimmune Dysregulation and Metabolic Disturbances

The COVID-19 pandemic has revealed a significant association between SARS-CoV-2 infection and diabetes, whereby individuals with diabetes are more susceptible to severe disease and higher mortality rates. Interestingly, recent findings suggest a reciprocal relationship between COVID-19 and diabetes, wherein COVID-19 may contribute to developing new-onset diabetes and worsen existing metabolic abnormalities. This narrative review aims to shed light on the intricate molecular mechanisms underlying the diabetogenic effects of COVID-19. Specifically, the review explores the potential role of various factors, including direct damage to β-cells, insulin resistance triggered by systemic inflammation, and disturbances in hormonal regulation, aiming to enhance our understanding of the COVID-19 impact on the development and progression of diabetes. By analysing these mechanisms, the aim is to enhance our understanding of the impact of COVID-19 on the development and progression of diabetes. The binding of SARS-CoV-2 to angiotensin-converting enzyme 2 (ACE2) receptors, which are present in key metabolic organs and tissues, may interfere with glucometabolic pathways, leading to hyperglycaemia, and potentially contribute to the development of new disease mechanisms. The virus's impact on β-cells through direct invasion or systemic inflammation may induce insulin resistance and disrupt glucose homeostasis. Furthermore, glucocorticoids, commonly used to treat COVID-19, may exacerbate hyperglycaemia and insulin resistance, potentially contributing to new-onset diabetes. The long-term effects of COVID-19 on glucose metabolism are still unknown, necessitating further research into the possibility of developing a novel type of diabetes. This article provides a comprehensive overview of the current understanding of the interaction between COVID-19 and diabetes, highlighting potential areas for future research and therapeutic interventions.

Cardiovascular and haematological pathology in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): A role for viruses

ME/CFS is a debilitating chronic condition that often develops after viral or bacterial infection. Insight from the study of Long COVID/Post Acute Sequelae of COVID-19 (PASC), the post-viral syndrome associated with SARS-CoV-2 infection, might prove to be useful for understanding pathophysiological mechanisms of ME/CFS. Disease presentation is similar between the two conditions, and a subset of Long COVID patients meet the diagnostic criteria for ME/CFS. Since Long COVID is characterized by significant vascular pathology - including endothelial dysfunction, coagulopathy, and vascular dysregulation - the question of whether or not the same biological abnormalities are of significance in ME/CFS arises. Cardiac abnormalities have for a while now been documented in ME/CFS cohorts, with recent studies demonstrating major deficits in cerebral blood flow, and hence vascular dysregulation. A growing body of research is demonstrating that ME/CFS is accompanied by platelet hyperactivation, anomalous clotting, a procoagulant phenotype, and endothelial dysfunction. Endothelial damage and dysregulated clotting can impair substance exchange between blood and tissues, and result in hypoperfusion, which may contribute to the manifestation of certain ME/CFS symptoms. Here we review the ME/CFS literature to summarize cardiovascular and haematological findings documented in patients with the condition, and, in this context, briefly discuss the potential role of previously-implicated pathogens. Overall, cardiac and haematological abnormalities are present within ME/CFS cohorts. While atherosclerotic heart disease is not significantly associated with ME/CFS, suboptimal cardiovascular function defined by reduced cardiac output, impaired cerebral blood flow, and vascular dysregulation are, and these abnormalities do not appear to be influenced by deconditioning. Rather, these cardiac abnormalities may result from dysfunction in the (autonomic) nervous system. Plenty of recently published studies are demonstrating significant platelet hyperactivity and endothelial dysfunction in ME/CFS, as well as anomalous clotting processes. It is of particular importance to determine to what extent these cardiovascular and haematological abnormalities contribute to symptom severity, and if these two systems can be targeted for therapeutic purposes. Viral reservoirs of herpesviruses exist in ME/CFS, and most likely contribute to cardiovascular and haematological dysfunction directly or indirectly. This review highlights the potential of studying cardiac functioning, the vasculature, and coagulation system in ME/CFS.

Immunomodulatory Agents for Coronavirus Disease-2019 Pneumonia

Morbidity and mortality from COVID-19 is due to severe inflammation and end-organ damage caused by a hyperinflammatory response. Multiple immunomodulatory agents to attenuate this response have been studied. Corticosteroids, specifically dexamethasone, have been shown to reduce mortality in hospitalized patients who require supplemental oxygen. Interleukin-6 antagonist, tocilizimab, and Janus kinase inhibitors have also been shown to reduce mortality. However, patients who have severe pulmonary end-organ damage requiring mechanical ventilation or extracorporeal membrane oxygenation appear not to benefit from immunomodulatory therapies. This highlights the importance of appropriate timing to initiate immunomodulatory therapies in the management of severe COVID-19 disease.

In Silico and In Vitro Evaluation of Some Amidine Derivatives as Hit Compounds towards Development of Inhibitors against Coronavirus Diseases

Coronaviruses, including SARS-CoV-2, SARS-CoV, MERS-CoV and influenza A virus, require the host proteases to mediate viral entry into cells. Rather than targeting the continuously mutating viral proteins, targeting the conserved host-based entry mechanism could offer advantages. Nafamostat and camostat were discovered as covalent inhibitors of TMPRSS2 protease involved in viral entry. To circumvent their limitations, a reversible inhibitor might be required. Considering nafamostat structure and using pentamidine as a starting point, a small set of structurally diverse rigid analogues were designed and evaluated in silico to guide selection of compounds to be prepared for biological evaluation. Based on the results of in silico study, six compounds were prepared and evaluated in vitro. At the enzyme level, compounds 10-12 triggered potential TMPRSS2 inhibition with low micromolar IC50 concentrations, but they were less effective in cellular assays. Meanwhile, compound 14 did not trigger potential TMPRSS2 inhibition at the enzyme level, but it showed potential cellular activity regarding inhibition of membrane fusion with a low micromolar IC50 value of 10.87 µM, suggesting its action could be mediated by another molecular target. Furthermore, in vitro evaluation showed that compound 14 inhibited pseudovirus entry as well as thrombin and factor Xa. Together, this study presents compound 14 as a hit compound that might serve as a starting point for developing potential viral entry inhibitors with possible application against coronaviruses.

Endotheliopathy in Acute COVID-19 and Long COVID

The pulmonary endothelium is a highly regulated organ that performs a wide range of functions under physiological and pathological conditions. Since endothelial dysfunction has been demonstrated to play a direct role in sepsis and acute respiratory distress syndrome, its role in COVID-19 has also been extensively investigated. Indeed, apart from the COVID-19-associated coagulopathy biomarkers, new biomarkers were recognised early during the pandemic, including markers of endothelial cell activation or injury. We systematically searched the literature up to 10 March 2023 for studies examining the association between acute and long COVID-19 severity and outcomes and endothelial biomarkers.

Extracellular vesicles in COVID-19 prognosis, treatment, and vaccination: an update

The lethality of the COVID 19 pandemic became the trigger for one of the most meteoric races on record in the search for strategies of disease control. Those include development of rapid and sensitive diagnostic methods, therapies to treat severe cases, and development of anti-SARS-CoV-2 vaccines, the latter responsible for the current relative control of the disease. However, the commercially available vaccines are still far from conferring protection against acquiring the infection, so the development of more efficient vaccines that can cut the transmission of the variants of concerns that currently predominate and those that will emerge is a prevailing need. On the other hand, considering that COVID 19 is here to stay, the development of new diagnosis and treatment strategies is also desirable. In this sense, there has recently been a great interest in taking advantage of the benefits offered by extracellular vesicles (EVs), membrane structures of nanoscale size that carry information between cells participating in this manner in many physiological homeostatic and pathological processes. The interest has been focused on the fact that EVs are relatively easy to obtain and manipulate, allowing the design of natural nanocarriers that deliver molecules of interest, as well as the information about the pathogens, which can be exploited for the aforementioned purposes. Studies have shown that infection with SARS-CoV-2 induces the release of EVs from different sources, including platelets, and that their increase in blood, as well as some of their markers, could be used as a prognosis of disease severity. Likewise, EVs from different sources are being used as the ideal carriers for delivering active molecules and drugs to treat the disease, as well as vaccine antigens. In this review, we describe the progress that has been made in these three years of pandemic regarding the use of EVs for diagnosis, treatment, and vaccination against SARS-CoV-2 infection. KEY POINTS: • Covid-19 still requires more effective and specific treatments and vaccines. • The use of extracellular vesicles is emerging as an option with multiple advantages. • Association of EVs with COVID 19 and engineered EVs for its control are presented.

Renal Allograft Cortical Necrosis in a COVID-19 Positive Patient

The incidence of acute kidney injury (AKI) has been reported to be higher in kidney transplant recipients infected with SARS-CoV-2 compared with the general population. Here, we report a case of cortical necrosis in the graft kidney due to COVID infection in a patient with stable graft function over the years. The patient was started on hemodialysis and treated with steroids, and anticoagulants for COVID infection. Later, he had gradual improvement in his graft function and became dialysis independent on follow up.

Peripheral blood mononuclear cell tissue factor (F3 gene) transcript levels and circulating extracellular vesicles are elevated in severe coronavirus 2019 (COVID-19) disease

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with excessive coagulation, thrombosis, and mortality.

OBJECTIVE

To provide insight into mechanisms that contribute to excessive coagulation in coronavirus 2019 (COVID-19) disease.

PATIENTS/METHODS

Blood from COVID-19 patients was investigated for coagulation-related gene expression and functional activities.

RESULTS

Single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells from severe COVID-19 patients revealed a 5.2-fold increase in tissue factor (TF [F3 gene]) transcript expression levels (P < .05), the trigger of extrinsic coagulation; a 7.7-fold increase in C1-inhibitor (SERPING1 gene; P < .01) transcript expression levels, an inhibitor of intrinsic coagulation; and a 4.4-fold increase in anticoagulant thrombomodulin (TM [THBD gene]) transcript expression levels (P < .001). Bulk RNA-seq analysis of sorted CD14⁺ monocytes on an independent cohort of COVID-19 patients confirmed these findings (P < .05). Indicative of excessive coagulation, 41% of COVID-19 patients' plasma samples contained high D-dimer levels (P < .0001); of these, 19% demonstrated extracellular vesicle TF activity (P = .109). COVID-19 patients' ex vivo plasma-based thrombin generation correlated positively with D-dimer levels (P < .01). Plasma procoagulant extracellular vesicles were elevated ∼9-fold in COVID-19 patients (P < .01). Public scRNA-seq data sets from bronchoalveolar lung fluid and our peripheral blood mononuclear cell scRNA-seq data show CD14⁺ monocytes/macrophages TF transcript expression levels are elevated in severe but not mild or moderate COVID-19 patients.

CONCLUSIONS

Beyond local lung injury, SARS-CoV-2 infection increases systemic TF (F3) transcript levels and elevates circulating extracellular vesicles that likely contribute to disease-associated coagulation, thrombosis, and related mortality.

The intersection of obesity and (long) COVID-19: Hypoxia, thrombotic inflammation, and vascular endothelial injury

The role of hypoxia, vascular endothelial injury, and thrombotic inflammation in worsening COVID-19 symptoms has been generally recognized. Damaged vascular endothelium plays a crucial role in forming in situ thrombosis, pulmonary dysfunction, and hypoxemia. Thrombotic inflammation can further aggravate local vascular endothelial injury and affect ventilation and blood flow ratio. According to the results of many studies, obesity is an independent risk factor for a variety of severe respiratory diseases and contributes to high mechanical ventilation rate, high mortality, and slow recovery in COVID-19 patients. This review will explore the mechanisms by which obesity may aggravate the acute phase of COVID-19 and delay long COVID recovery by affecting hypoxia, vascular endothelial injury, and thrombotic inflammation. A systematic search of PubMed database was conducted for papers published since January 2020, using the medical subject headings of "COVID-19" and "long COVID" combined with the following keywords: "obesity," "thrombosis," "endothelial injury," "inflammation," "hypoxia," "treatment," and "anticoagulation." In patients with obesity, the accumulation of central fat restricts the expansion of alveoli, exacerbating the pulmonary dysfunction caused by SARS-CoV-2 invasion, inflammatory damage, and lung edema. Abnormal fat secretion and immune impairment further aggravate the original tissue damage and inflammation diffusion. Obesity weakens baseline vascular endothelium function leading to an early injury and pre-thrombotic state after infection. Enhanced procoagulant activity and microthrombi promote early obstruction of the vascular. Obesity also prolongs the duration of symptoms and increases the risk of sequelae after hospital discharge. Persistent viral presence, long-term inflammation, microclots, and hypoxia may contribute to the development of persistent symptoms, suggesting that patients with obesity are uniquely susceptible to long COVID. Early interventions, including supplemental oxygen, comprehensive antithrombotic therapy, and anti-inflammatory drugs, show effectiveness in many studies in the prevention of serious hypoxia, thromboembolic events, and systemic inflammation, and are therefore recommended to reduce intensive care unit admission, mortality, and sequelae.

Association of heme-oxygenase 1, hemopexin, and heme levels with markers of disease severity in COVID-19

Heme-oxygenase 1 (HO-1) is an enzyme with well-known anti-inflammatory and antioxidant properties, whose levels have been previously associated with disease severity in the context of sterile and infectious diseases. Moreover, the heme/HO-1 pathway has been associated with prothrombotic changes in other diseases. Accordingly, the potential of modulating HO-1 levels for the treatment of COVID-19 was extensively speculated during the COVID-19 pandemic, but very few actual data were generated. The aim of our study was to explore the association of HO-1, heme, and hemopexin (HPX) levels with COVID-19 severity and with markers of inflammation and coagulation activation. The study was conducted in 30 consecutive patients with COVID-19 admitted due to hypoxemia, and 30 healthy volunteers matched by sex, age, and geographic region. HO-1 and HPX levels were measured by enzyme immunoassay (ELISA) and heme levels were measured by a colorimetric method. A comprehensive panel of coagulation and fibrinolysis activation was also used. Patients with COVID-19 presented increased levels of HO-1 when compared to controls (5741 ± 2696 vs 1953 ± 612 pg/mL, respectively, P < 0.0001), as well as a trend toward increased levels of HPX (3.724 ± 0.880 vs 3.254 ± 1.022 mg/mL, respectively; P = 0.06). In addition, HO-1 and HPX levels reduced from admission to day + 4. HO-1 levels were associated with duration of intensive care unit stay and with several markers of coagulation activation. In conclusion, modulation of HO-1 could be associated with the prothrombotic state observed in COVID-19, and HO-1 could also represent a relevant biomarker for COVID-19. New independent studies are warranted to explore and expand these findings.

Does COVID-19 infection increase the risk of pulmonary embolism in ambulatory patients with deep vein thrombosis

OBJECTIVES

Coronavirus disease 2019 (COVID-19) can lead to systemic coagulation activation and thrombotic complications including venous thromboembolism. This study compares the development of pulmonary embolism, post-thrombotic syndrome, and clinical outcomes of COVID-19 and non-COVID-19 patients with deep vein thrombosis (DVT).

METHODS

One hundred and eight patients diagnosed with acute deep vein thrombosis (DVT) between June 2020 and February 2021 in our institution were included in this retrospective study. Thirty-nine patients had been previously diagnosed with COVID-19 and specified as the COVID-19 group. Sixty-nine patients did not have COVID-19 and specified as the non-COVID-19 group. Mean ages of both groups were 64.3 ± 15.8 and 60.1 ± 19.7 years, respectively (p = .37).

RESULTS

The median duration from the onset of the COVID-19 to diagnosis of DVT was 22 (2-120) days in the COVID-19 group. The patients of two groups were mostly treated outpatient at rates of 94.9% vs 94.2%, respectively (p = .88). Pulmonary embolism was seen in six patients (15.4%) in the COVID-19 group and in three patients (4.3%) in the non-COVID-19 group (p = .04). Kaplan-Meir curves showed that patients with COVİD-19 had significantly higher pulmonary embolism than those without COVID-19 (p = .015). The recurrence rate of DVT was 2.6% in the COVID-19 group (n = 1), and 4.3% in the non-COVID-19 group (n = 3), indicating no statistically significant difference (p = .63). Mortality was seen in six patients (15.4%) in the COVİD-19 group, and in seven patients (10.1%) in the non-COVID-19 group. According to the Kaplan-Meir method, 10 months survival rates were 73.9 ± 10% in the COVID-19 group, and 66.3 ± 12.8% in the non-COVID-19 group with no statistical significance (p = .218).

CONCLUSIONS

Our data draw attention to the fact that deep vein thrombosis should not be considered a safe and self-limited condition. Efficient preventive measures such as mobilization and prophylactic drug use should be considered to prevent DVT during the management of COVID-19.

Dissecting Platelet's Role in Viral Infection: A Double-Edged Effector of the Immune System

Platelets play a major role in the processes of primary hemostasis and pathological inflammation-induced thrombosis. In the mid-2000s, several studies expanded the role of these particular cells, placing them in the "immune continuum" and thus changing the understanding of their function in both innate and adaptive immune responses. Among the many receptors they express on their surface, platelets express Toll-Like Receptors (TLRs), key receptors in the inflammatory cell-cell reaction and in the interaction between innate and adaptive immunity. In response to an infectious stimulus, platelets will become differentially activated. Platelet activation is variable depending on whether platelets are activated by a hemostatic or pathogen stimulus. This review highlights the role that platelets play in platelet modulation count and adaptative immune response during viral infection.

Additional risk factors improve mortality prediction for patients hospitalized with influenza pneumonia: a retrospective, single-center case-control study

BACKGROUND

Severe influenza, especially influenza pneumonia, causes large numbers of deaths each year. Some patients who develop severe influenza have no known risk factors. In this study we investigated risk factors for mortality of patients with influenza A-related pneumonia who have different basic conditions. We also evaluated the power of pneumonia severity assessment tools in Chinese patients hospitalized with influenza A-related pneumonia. Together, these results could provide a basis for a screening method that has improved ability for the early identification of critical patients who will have poor prognoses in clinical practice.

METHODS

This single-center, retrospective case-control study included 152 adult patients with severe influenza over six influenza seasons. Data for diagnoses and demographics, as well clinical data, laboratory findings, treatment methods, 30-day and 60-day outcomes of the patients were collected. Patients who had any of the risk factors for severe influenza were included in the high-risk group, and those that had no known risk factors were included in the low-risk group.

RESULTS

The PSI, CURB-65 and PIRO-CAP tools all underestimated the mortality rate of patients hospitalized with influenza A-related pneumonia, and this underestimate was more pronounced for low-risk patients. D-dimer (Odds ratio [OR] = 1.052, 95% confidence interval [CI] 1.001-1.106, p = 0.045) and direct bilirubin (OR = 1.143, 95%CI 1.049-1.246, p = 0.002) were independent risk factors for mortality of patients with influenza A-related pneumonia. When used in combination with ferritin and D-dimer, the area under receiver operator characteristic curve (AUC_ROC) was 0.851 (95%CI 0.780-0.922, p < 0.001), 0.840 (95%CI 0.763-0.916, p < 0.001) and 0.829 (95%CI 0.748-0.911, p < 0.001) for PSI, CURB-65 and PIRO-CAP, respectively, which was higher than that obtained using PSI, CURB-65 and PIRO-CAP alone.

CONCLUSIONS

The findings demonstrate that currently used community-acquired pneumonia (CAP) scoring systems could underestimate the risk of influenza A-related pneumonia mortality. D-dimer was shown to be an independent risk factor of mortality for influenza A-related pneumonia in hospitalized patients, and a combination of D-dimer with ferritin could improve the predictive value of PSI, CURB-65 and PIRO-CAP for adverse prognoses of patients with influenza A-related pneumonia.

SARS-CoV-2 Spike protein activates TMEM16F-mediated platelet procoagulant activity

Thrombosis of the lung microvasculature is a characteristic of COVID-19 disease, which is observed in large excess compared to other forms of acute respiratory distress syndrome and thus suggests a trigger for thrombosis that is endogenous to the lung. Our recent work has shown that the SARS-CoV-2 Spike protein activates the cellular TMEM16F chloride channel and scramblase. Through a screening on >3,000 FDA/EMA approved drugs, we identified Niclosamide and Clofazimine as the most effective molecules at inhibiting Spike-induced TMEM16 activation. As TMEM16F plays an important role in stimulating the procoagulant activity of platelets, we investigated whether Spike directly affects platelet activation and pro-thrombotic function and tested the effect of Niclosamide and Clofazimine on these processes. Here we show that Spike, present either on the virion envelope or on the cell plasma membrane, promotes platelet activation, adhesion and spreading. Spike was active as a sole agonist or, even more effectively, by enhancing the function of known platelet activators. In particular, Spike-induced a marked procoagulant phenotype in platelets, by enhancing Ca²⁺ flux, phosphatidylserine externalization on the platelet outer cell membrane, and thrombin generation. Eventually, this increased thrombin-induced clot formation and retraction. Both Niclosamide and Clofazimine blocked this Spike-induced procoagulant response. These findings provide a pathogenic mechanism to explain lung thrombosis-associated with severe COVID-19 infection. We propose that Spike, present in SARS-CoV-2 virions or exposed on the surface of infected cells in the lungs, enhances the effects of inflammation and leads to local platelet stimulation and subsequent activation of the coagulation cascade. As platelet TMEM16F is central in this process, these findings reinforce the rationale of repurposing Niclosamide for COVID-19 therapy.

Potential Treatment of COVID-19 with Traditional Chinese Medicine: What Herbs Can Help Win the Battle with SARS-CoV-2?

Traditional Chinese medicine (TCM) has been successfully applied worldwide in the treatment of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the pharmacological mechanisms underlying this success remain unclear. Hence, the aim of this review is to combine pharmacological assays based on the theory of TCM in order to elucidate the potential signaling pathways, targets, active compounds, and formulas of herbs that are involved in the TCM treatment of COVID-19, which exhibits combatting viral infections, immune regulation, and amelioration of lung injury and fibrosis. Extensive reports on target screening are elucidated using virtual prediction via docking analysis or network pharmacology based on existing data. The results of these reports indicate that an intricate regulatory mechanism is involved in the pathogenesis of COVID-19. Therefore, more pharmacological research on the natural herbs used in TCM should be conducted in order to determine the association between TCM and COVID-19 and account for the observed therapeutic effects of TCM against COVID-19.

Spike Protein Subunits of SARS-CoV-2 Alter Mitochondrial Metabolism in Human Pulmonary Microvascular Endothelial Cells: Involvement of Factor Xa

BACKGROUND

Mitochondria have been involved in host defense upon viral infections. Factor Xa (FXa), a coagulating factor, may also have influence on mitochondrial functionalities. The aim was to analyze if in human pulmonary microvascular endothelial cells (HPMEC), the SARS-CoV-2 (COVID-19) spike protein subunits, S1 and S2 (S1+S2), could alter mitochondrial metabolism and what is the role of FXA.

METHODS

HPMEC were incubated with and without recombinants S1+S2 (10 nmol/L each).

RESULTS

In control conditions, S1+S2 failed to modify FXa expression. However, in LPS (1 μg/mL)-incubated HPMEC, S1+S2 significantly increased FXa production. LPS tended to reduce mitochondrial membrane potential with respect to control, but in higher and significant degree, it was reduced when S1+S2 were present. LPS did not significantly modify cytochrome c oxidase activity as compared with control. Addition of S1+S2 spike subunits to LPS-incubated HPMEC significantly increased cytochrome c oxidase activity with respect to control. Lactate dehydrogenase activity was also increased by S1+S2 with respect to control and LPS alone. Protein expression level of uncoupled protein-2 (UCP-2) was markedly expressed when S1+S2 were added together to LPS. Rivaroxaban (50 nmol/L), a specific FXa inhibitor, significantly reduced all the above-mentioned alterations induced by S1+S2 including UCP-2 expression.

CONCLUSIONS

In HPMEC undergoing to preinflammatory condition, COVID-19 S1+S2 spike subunits promoted alterations in mitochondria metabolism suggesting a shift from aerobic towards anaerobic metabolism that was accompanied of high FXa production. Rivaroxaban prevented all the mitochondrial metabolic changes mediated by the present COVID-19 S1 and S2 spike subunits suggesting the involvement of endogenous FXa.

Tissue Factor and COVID-19: An Update

The coronavirus 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Infection with SARS-CoV-2 is associated with acute respiratory distress syndrome, thrombosis and a high rate of mortality. Thrombotic events increase with severity. Tissue factor (TF) expression is increased during viral and bacterial infections. This review summarizes studies that have examined TF expression in response to SARS-CoV-2 infection. SARS-CoV-2 virus and its proteins upregulate TF mRNA, protein and activity in a variety of cells, including bronchial epithelial cells, neutrophils, monocytes, macrophages, endothelial cells and adventitial fibroblasts. COVID-19 patients have increased TF expression in lungs, bronchoalveolar lavage fluid and circulating extracellular vesicles. The increase in TF was associated with coagulation activation markers, thrombosis, inflammatory markers, severity of disease and mortality. Taken together, the studies suggest that TF plays a central role in thrombosis in COVID- 19. TF may be a useful prognostic marker and therapeutic target to reduce thrombosis and inflammation.

Thrombosis of Medium-Sized and Large Arteries During Covid-19 Infection: Results of the COVIVASC Study

BACKGROUND

COVID-19 infection is associated not only with venous thromboses but also with arterial thromboses (COV-ATs) in relation with an endothelial dysfunction, a coagulopathy and rhythm disorders. The incidence, the topography, and the prognosis of COV-ATs remain poorly known. The objective of this study was to report the overall experience of the Greater Paris University Hospitals (Assistance Publique - Hopitaux de Paris, AP-HP) during the first pandemic wave of COVID-19 infection.

METHODS

After approval by the ethics committee, a study using the AP-HP clinical data warehouse was carried out between March and May 2020. Overall, 124,609 patients had a polymerase chain reaction for COVID-19 in our hospitals, of which 25,345 were positive. From 20,710 exploitable stays, patients tested positive for COVID who presented an episode of acute COV-AT (except coronary and intracranial arteries) were selected on the basis of the French medical classification for clinical procedures codes. The data are presented as absolute values with percentages and/or means with standard deviation.

RESULTS

Over the studied period, 60 patients (aged 71±14 years, 42 men) presented a COV-AT at the time of their hospitalization, an incidence of 0.2%. The arterial complication occurred 3±7 days after the COVID infection and was inaugural in 30% of the cases (n = 18). The sites of COV-AT were the lower extremities (n = 35%, 58%), the abdominal aorta (n = 10%, 17%), the thoracic aorta (n = 7%, 12%), the upper limbs (n = 7%, 12%), the cerebral arteries (n = 7%, 12%), the digestive arteries (n = 6%, 10%), the renal arteries (n = 2%, 3%), and the ophthalmic artery (n = 1%, 2%). Multiple COV-ATs were observed in 13 patients (22%). At the time of diagnosis, 20 (33%) patients were in intensive care, including six (10%) patients who were intubated. On computed tomography angiography, COVID lesions were classified as moderate and severe in 25 (42%) and 21 (35%) cases, respectively. Revascularization was attempted in 27 patients (45%), by open surgery in 16 cases, using endovascular techniques in 8 cases and with a hybrid approach in three cases. Six patients (22%) required reinterventions. The duration of hospitalization was 12±9 days. Early mortality (in-hospital or at 30 days) was 30% (n = 18). Nine (15%) patients presented severe nonlethal ischemic complications.

CONCLUSIONS

Arterial involvement is rare during COVID-19 infection. The aorta and the arteries of the limbs are the privileged sites. The morbi-mortality of these patients is high. Future studies will have to determine if the systematization of anticoagulation therapy decreases the incidence and the severity of the condition.

Tissue factor in COVID-19-associated coagulopathy

Evidence of micro- and macro-thrombi in the arteries and veins of critically ill COVID-19 patients and in autopsies highlight the occurrence of COVID-19-associated coagulopathy (CAC). Clinical findings of critically ill COVID-19 patients point to various mechanisms for CAC; however, the definitive underlying cause is unclear. Multiple factors may contribute to the prothrombotic state in patients with COVID-19. Aberrant expression of tissue factor (TF), an initiator of the extrinsic coagulation pathway, leads to thrombotic complications during injury, inflammation, and infections. Clinical evidence suggests that TF-dependent coagulation activation likely plays a role in CAC. Multiple factors could trigger abnormal TF expression and coagulation activation in patients with severe COVID-19 infection. Proinflammatory cytokines that are highly elevated in COVID-19 (IL-1β, IL-6 and TNF-α) are known induce TF expression on leukocytes (e.g. monocytes, macrophages) and non-immune cells (e.g. endothelium, epithelium) in other conditions. Antiphospholipid antibodies, TF-positive extracellular vesicles, pattern recognition receptor (PRR) pathways and complement activation are all candidate factors that could trigger TF-dependent procoagulant activity. In addition, coagulation factors, such as thrombin, may further potentiate the induction of TF via protease-activated receptors on cells. In this systematic review, with other viral infections, we discuss potential mechanisms and cell-type-specific expressions of TF during SARS-CoV-2 infection and its role in the development of CAC.

Ischemic Stroke Due to Heparin-induced Thrombocytopenia during Severe COVID-19 Infection

A 53-year-old woman with severe coronavirus disease 2019 (COVID-19) pneumonia was admitted and treated with intravenous unfractionated heparin for thromboprophylaxis under general anesthesia with mechanical ventilation. She developed right hemiparesis after hospitalization due to a large hemorrhagic infarction. Her platelet count decreased from 243,000/μL at administration to 121,000/μL. Anti-platelet factor 4-heparin antibody testing was positive according to a latex immunoturbidimetric assay. She was therefore diagnosed with heparin-induced thrombocytopenia. We immediately stopped the heparin and started argatroban; the platelet count recovered, and thrombosis did not relapse. Physicians should consider heparin-induced thrombocytopenia as a cause of ischemic stroke in patients with COVID-19 infection.

Resveratrol Downmodulates Neutrophil Extracellular Trap (NET) Generation by Neutrophils in Patients with Severe COVID-19

The formation of microthrombi in lung autopsies indicates the involvement of NETs in the immunopathogenesis of severe COVID-19. Therefore, supplements inhibiting NET formation, in association with drugs with fewer adverse effects, should be a relevant strategy to attenuate the disease. Resveratrol (RESV) is a natural polyphenol with an important antiviral and antioxidant role. To modulate neutrophils from patients infected with SARS-CoV-2, we evaluated the in vitro effect of RESV on NET formation. Herein, we investigated 190 patients hospitalized with moderate, severe, and critical symptoms at Hospital das Clínicas, Brazil. We observed that neutrophilia in patients with severe COVID-19 infection is composed of neutrophils with activated profile able to release NET spontaneously. Notably, RESV decreased the neutrophil-activated status and the release of free DNA, inhibiting NET formation even under the specific PMA stimulus. At present, there is no evidence of the role of RESV in neutrophils from patients with COVID-19 infection. These findings suggest that adjunctive therapies with RESV may help decrease the inflammation of viral or bacterial infection, improving patient outcomes.

COVID-19-Related ARDS: Key Mechanistic Features and Treatments

Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome historically characterized by the presence of severe hypoxemia, high-permeability pulmonary edema manifesting as diffuse alveolar infiltrate on chest radiograph, and reduced compliance of the integrated respiratory system as a result of widespread compressive atelectasis and fluid-filled alveoli. Coronavirus disease 19 (COVID-19)-associated ARDS (C-ARDS) is a novel etiology caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that may present with distinct clinical features as a result of the viral pathobiology unique to SARS-CoV-2. In particular, severe injury to the pulmonary vascular endothelium, accompanied by the presence of diffuse microthrombi in the pulmonary microcirculation, can lead to a clinical presentation in which the severity of impaired gas exchange becomes uncoupled from lung capacity and respiratory mechanics. The purpose of this review is to highlight the key mechanistic features of C-ARDS and to discuss the implications these features have on its treatment. In some patients with C-ARDS, rigid adherence to guidelines derived from clinical trials in the pre-COVID era may not be appropriate.

Early-stage COVID-19 pandemic observations on pulmonary embolism using nationwide multi-institutional data harvesting

We introduce a multi-institutional data harvesting (MIDH) method for longitudinal observation of medical imaging utilization and reporting. By tracking both large-scale utilization and clinical imaging results data, the MIDH approach is targeted at measuring surrogates for important disease-related observational quantities over time. To quantitatively investigate its clinical applicability, we performed a retrospective multi-institutional study encompassing 13 healthcare systems throughout the United States before and after the 2020 COVID-19 pandemic. Using repurposed software infrastructure of a commercial AI-based image analysis service, we harvested data on medical imaging service requests and radiology reports for 40,037 computed tomography pulmonary angiograms (CTPA) to evaluate for pulmonary embolism (PE). Specifically, we compared two 70-day observational periods, namely (i) a pre-pandemic control period from 11/25/2019 through 2/2/2020, and (ii) a period during the early COVID-19 pandemic from 3/8/2020 through 5/16/2020. Natural language processing (NLP) on final radiology reports served as the ground truth for identifying positive PE cases, where we found an NLP accuracy of 98% for classifying radiology reports as positive or negative for PE based on a manual review of 2,400 radiology reports. Fewer CTPA exams were performed during the early COVID-19 pandemic than during the pre-pandemic period (9806 vs. 12,106). However, the PE positivity rate was significantly higher (11.6 vs. 9.9%, p < 10^-4) with an excess of 92 PE cases during the early COVID-19 outbreak, i.e., ~1.3 daily PE cases more than statistically expected. Our results suggest that MIDH can contribute value as an exploratory tool, aiming at a better understanding of pandemic-related effects on healthcare.

Thromboprophylaxis for children hospitalized with COVID-19 and MIS-C

Background

Limited data exist about effective regimens for pharmacological thromboprophylaxis in children with acute coronavirus disease 2019 (COVID‐19) and multisystem inflammatory syndrome in children (MIS‐C).

Objectives

Study the outcomes of institutional thromboprophylaxis protocol for primary venous thromboembolism (VTE) prevention in children hospitalized with acute COVID‐19/MIS‐C.

Methods

This single‐center retrospective cohort study included consecutive children (aged less than 21 years) with COVID‐19/MIS‐C who received tailored intensity thromboprophylaxis, primarily with low‐molecular‐weight heparin, from April 2020 through October 2021. Thromboprophylaxis was given to those with moderate to severe disease based on the World Health Organization scale and exposure to two or more VTE risk factors. Therapeutic intensity was considered for severe illness. Clinical recovery along with D‐dimer improvement determined thromboprophylaxis duration. Outcomes were incident VTEs, bleeding, and mortality.

Results

Among 211 hospitalizations, 45 (21.3%) received thromboprophylaxis (COVID‐19, 16; MIS‐C, 29). Median age was 14.8 years (interquartile range [IQR], 8.9–16.1). Among 35 (77.8%) with severe illness, 27 (60.0%) required respiratory support, and 19 (42.2%) required an intensive care unit stay. Median hospitalization was 6 days (IQR, 5.0–10.5). Median thromboprophylaxis duration was 19 days (IQR, 6.0–31.0) with therapeutic intensity in 24 (53.3%) and prophylactic in 21 (46.7%). Outcomes were as follows: VTE, 1 (2.2%); death, 1 (2.2%, unrelated to bleeding/thrombosis); major/clinically relevant nonmajor bleeding, 0; and minor bleeding, 7 (15.5%). D‐dimer was elevated in a majority at diagnosis (median, 2.3; IQR, 1.2–3.3 mg/ml fibrinogen‐equivalent units) and was noninformative in assessing disease severity. D‐dimer normalized at thromboprophylaxis discontinuation.

Conclusions

Our experience of using clinically directed thromboprophylaxis with tailored intensity approach for children hospitalized with COVID‐19 and MIS‐C favors its inclusion in current standard of care. The role of D‐dimer in directing thromboprophylaxis management deserves further evaluation.

D,L-Lysine-Acetylsalicylate + Glycine (LASAG) Reduces SARS-CoV-2 Replication and Shows an Additive Effect with Remdesivir

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing the coronavirus disease-19 (COVID-19) is still challenging healthcare systems and societies worldwide. While vaccines are available, therapeutic strategies are developing and need to be adapted to each patient. Many clinical approaches focus on the repurposing of approved therapeutics against other diseases. However, the efficacy of these compounds on viral infection or even harmful secondary effects in the context of SARS-CoV-2 infection are sparsely investigated. Similarly, adverse effects of commonly used therapeutics against lifestyle diseases have not been studied in detail. Using mono cell culture systems and a more complex chip model, we investigated the effects of the acetylsalicylic acid (ASA) salt D,L-lysine-acetylsalicylate + glycine (LASAG) on SARS-CoV-2 infection in vitro. ASA is commonly known as Aspirin^® and is one of the most frequently used medications worldwide. Our data indicate an inhibitory effect of LASAG on SARS-CoV-2 replication and SARS-CoV-2-induced expression of pro-inflammatory cytokines and coagulation factors. Remarkably, our data point to an additive effect of the combination of LASAG and the antiviral acting drug remdesivir on SARS-CoV-2 replication in vitro.

Circulating tissue factor-positive extracellular vesicles and their association with thrombosis in different diseases

Tissue factor (TF) is a procoagulant protein released from activated host cells, such as monocytes, and tumor cells on extracellular vesicles (EVs). TF + EVs are observed in the circulation of patients with various types of diseases. In this review, we will summarize the association between TF + EVs and activation of coagulation and survival in different types of diseases, including cancer, sepsis, and infections with different viruses, such as human immunodeficiency virus (HIV), influenza A virus (IAV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We will also discuss the source of TF + EVs in various diseases. EVTF activity is associated with thrombosis in pancreatic cancer patients and coronavirus disease 2019 patients (COVID-19) and with disseminated intravascular coagulation in cancer patients. EVTF activity is also associated with worse survival in patients with cancer and COVID-19. Monocytes are the major sources of TF + EVs in sepsis, and viral infections, such as HIV, Ebola virus, and SARS-CoV-2. In contrast, alveolar epithelial cells are the major source of TF + EVs in bronchoalveolar lavage fluid in COVID-19 and influenza A patients. These studies indicate that EVTF activity could be used as a biomarker to identify patients that have an increased risk of coagulopathy and mortality.

Contact and intrinsic coagulation pathways are activated and associated with adverse clinical outcomes in COVID-19

Coagulation activation is a prominent feature of severe acute respiratory syndrome coronavirus 2 (COVID-19) infection. Activation of the contact system and intrinsic pathway has increasingly been implicated in the prothrombotic state observed in both sterile and infectious inflammatory conditions. We therefore sought to assess activation of the contact system and intrinsic pathway in individuals with COVID-19 infection. Baseline plasma levels of protease:serpin complexes indicative of activation of the contact and intrinsic pathways were measured in samples from inpatients with COVID-19 and healthy individuals. Cleaved kininogen, a surrogate for bradykinin release, was measured by enzyme-linked immunosorbent assay, and extrinsic pathway activation was assessed by microvesicle tissue factor-mediated factor Xa (FXa; MVTF) generation. Samples were collected within 24 hours of COVID-19 diagnosis. Thirty patients with COVID-19 and 30 age- and sex-matched controls were enrolled. Contact system and intrinsic pathway activation in COVID-19 was demonstrated by increased plasma levels of FXIIa:C1 esterase inhibitor (C1), kallikrein:C1, FXIa:C1, FXIa:α1-antitrypsin, and FIXa:antithrombin (AT). MVTF levels were also increased in patients with COVID-19. Because FIXa:AT levels were associated with both contact/intrinsic pathway complexes and MVTF, activation of FIX likely occurs through both contact/intrinsic and extrinsic pathways. Among the protease:serpin complexes measured, FIXa:AT complexes were uniquely associated with clinical indices of disease severity, specifically total length of hospitalization, length of intensive care unit stay, and extent of lung computed tomography changes. We conclude that the contact/intrinsic pathway may contribute to the pathogenesis of the prothrombotic state in COVID-19. Larger prospective studies are required to confirm whether FIXa:AT complexes are a clinically useful biomarker of adverse clinical outcomes.

Aberrant Fibrin Clot Structure Visualized Ex Vivo in Critically Ill Patients With Severe Acute Respiratory Syndrome Coronavirus 2 Infection

OBJECTIVES

Disseminated fibrin-rich microthrombi have been reported in patients who died from COVID-19. Our objective is to determine whether the fibrin clot structure and function differ between critically ill patients with or without COVID-19 and to correlate the structure with clinical coagulation biomarkers.

DESIGN

A cross-sectional observational study. Platelet poor plasma was used to analyze fibrin clot structure; the functional implications were determined by quantifying clot turbidity and porosity.

SETTING

ICU at an academic medical center and an academic laboratory.

PATIENTS

Patients admitted from July 1 to August 1, 2020, to the ICU with severe acute respiratory syndrome coronavirus 2 infection confirmed by reverse transcription-polymerase chain reaction or patients admitted to the ICU with sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood was collected from 36 patients including 26 ICU patients with COVID-19 and 10 ICU patients with sepsis but without COVID-19 at a median of 11 days after ICU admission (interquartile range, 3-16). The cohorts were similar in age, gender, body mass index, comorbidities, Sequential Organ Failure Assessment (SOFA) score, and mortality. More patients with COVID-19 (100% vs 70%; p = 0.003) required anticoagulation. Ex vivo fibrin clots formed from patients with COVID-19 appeared to be denser and to have smaller pores than those from patients with sepsis but without COVID-19 (percent area of fluorescent fibrin 48.1% [SD, 16%] vs 24.9% [SD, 18.8%]; p = 0.049). The turbidity and flow-through assays corroborated these data; fibrin clots had a higher maximum turbidity in patients with COVID-19 compared with patients without COVID-19 (0.168 vs 0.089 OD units; p = 0.003), and it took longer for buffer to flow through these clots (216 vs 103 min; p = 0.003). In patients with COVID-19, d-dimer levels were positively correlated with percent area of fluorescent fibrin (ρ = 0.714, p = 0.047). Denser clots (assessed by turbidity and thromboelastography) and higher SOFA scores were independently associated with delayed clot lysis.

CONCLUSIONS

We found aberrant fibrin clot structure and function in critically ill patients with COVID-19. These findings may contribute to the poor outcomes observed in COVID-19 patients with widespread fibrin deposition.

The Role of Heparin in COVID-19: An Update after Two Years of Pandemics

Coronavirus disease 2019 (COVID-19) is associated with an increased risk of venous thromboembolism (VTE) and coagulopathy, especially in critically ill patients. Endothelial damage induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is emerging as a crucial pathogenetic mechanism for the development of complications in an acute phase of the illness and for several postdischarge sequalae. Heparin has been shown to have a positive impact on COVID-19 due to its anticoagulant function. Moreover, several other biological actions of heparin were postulated: a potential anti-inflammatory and antiviral effect through the main protease (Mpro) and heparansulfate (HS) binding and a protection from the damage of vascular endothelial cells. In this paper, we reviewed available evidence on heparin treatment in COVID-19 acute illness and chronic sequalae, focusing on the difference between prophylactic and therapeutic dosage.

Role of LL-37 in thrombotic complications in patients with COVID-19

Blood clot formation induced by dysfunctional coagulation is a frequent complication of coronavirus disease 2019 (COVID-19) and a high-risk factor for severe illness and death. Neutrophil extracellular traps (NETs) are implicated in COVID-19-induced immunothrombosis. Furthermore, human cathelicidin, a NET component, can perturb the interaction between the SARS-CoV-2 spike protein and its ACE2 receptor, which mediates viral entry into cells. At present, however, the levels of cathelicidin antimicrobial peptides after SARS-CoV-2 infection and their role in COVID-19 thrombosis formation remain unclear. In the current study, we analyzed coagulation function and found a decrease in thrombin time but an increase in fibrinogen level, prothrombin time, and activated partial thromboplastin time in COVID-19 patients. In addition, the cathelicidin antimicrobial peptide LL-37 was upregulated by the spike protein and significantly elevated in the plasma of patients. Furthermore, LL-37 levels were negatively correlated with thrombin time but positively correlated with fibrinogen level. In addition to platelet activation, cathelicidin peptides enhanced the activity of coagulation factors, such as factor Xa (FXa) and thrombin, which may induce hypercoagulation in diseases with high cathelicidin peptide levels. Injection of cathelicidin peptides promoted the formation of thrombosis, whereas deletion of cathelicidin inhibited thrombosis in vivo. These results suggest that cathelicidin antimicrobial peptide LL-37 is elevated during SARS-CoV-2 infection, which may induce hypercoagulation in COVID-19 patients by activating coagulation factors.

Molecular analysis of vascular gene expression

A State of the Art lecture entitled "Molecular Analysis of Vascular Gene Expression" was presented at the ISTH Congress in 2021. Endothelial cells (ECs) form a critical interface between the blood and underlying tissue environment, serving as a reactive barrier to maintain tissue homeostasis. ECs play an important role in not only coagulation, but also in the response to inflammation by connecting these two processes in the host defense against pathogens. Furthermore, ECs tailor their behavior to the needs of the microenvironment in which they reside, resulting in a broad display of EC phenotypes. While this heterogeneity has been acknowledged for decades, the contributing molecular mechanisms have only recently started to emerge due to technological advances. These include high-throughput sequencing combined with methods to isolate ECs directly from their native tissue environment, as well as sequencing samples at a high cellular resolution. In addition, the newest technologies simultaneously quantitate and visualize a multitude of RNA transcripts directly in tissue sections, thus providing spatial information. Understanding how ECs function in (patho)physiological conditions is crucial to develop new therapeutics as many diseases can directly affect the endothelium. Of particular relevance for thrombotic disorders, EC dysfunction can lead to a procoagulant, proinflammatory phenotype with increased vascular permeability that can result in coagulopathy and tissue damage, as seen in a number of infectious diseases, including sepsis and coronavirus disease 2019. In light of the current pandemic, we will summarize relevant new data on the latter topic presented during the 2021 ISTH Congress.