Signaling Through FcγRIIA and the C5a-C5aR Pathway Mediate Platelet Hyperactivation in COVID-19.

Patients with COVID-19 present with a wide variety of clinical manifestations. Thromboembolic events constitute a significant cause of morbidity and mortality in patients infected with SARS-CoV-2. Severe COVID-19 has been associated with hyperinflammation and pre-existing cardiovascular disease. Platelets are important mediators and sensors of inflammation and are directly affected by cardiovascular stressors. In this report, we found that platelets from severely ill, hospitalized COVID-19 patients exhibited higher basal levels of activation measured by P-selectin surface expression and had poor functional reserve upon in vitro stimulation. To investigate this question in more detail, we developed an assay to assess the capacity of plasma from COVID-19 patients to activate platelets from healthy donors. Platelet activation was a common feature of plasma from COVID-19 patients and correlated with key measures of clinical outcome including kidney and liver injury, and APACHEIII scores. Further, we identified ferritin as a pivotal clinical marker associated with platelet hyperactivation. The COVID-19 plasma-mediated effect on control platelets was highest for patients that subsequently developed inpatient thrombotic events. Proteomic analysis of plasma from COVID-19 patients identified key mediators of inflammation and cardiovascular disease that positively correlated with in vitro platelet activation. Mechanistically, blocking the signaling of the FcγRIIa-Syk and C5a-C5aR pathways on platelets, using antibody-mediated neutralization, IgG depletion or the Syk inhibitor fostamatinib, reversed this hyperactivity driven by COVID-19 plasma and prevented platelet aggregation in endothelial microfluidic chamber conditions. These data identified these potentially actionable pathways as central for platelet activation and/or vascular complications and clinical outcomes in COVID-19 patients. In conclusion, we reveal a key role of platelet-mediated immunothrombosis in COVID-19 and identify distinct, clinically relevant, targetable signaling pathways that mediate this effect.

Neutrophil-Dependent Immunity During Pulmonary Infections and Inflammations.

Rapid recruitment of neutrophils to an inflamed site is one of the hallmarks of an effective host defense mechanism. The main pathway through which this happens is by the innate immune response. Neutrophils, which play an important part in innate immune defense, migrate into lungs through the modulation actions of chemokines to execute a variety of pro-inflammatory functions. Despite the importance of chemokines in host immunity, little has been discussed on their roles in host immunity. A holistic understanding of neutrophil recruitment, pattern recognition pathways, the roles of chemokines and the pathophysiological roles of neutrophils in host immunity may allow for new approaches in the treatment of infectious and inflammatory disease of the lung. Herein, this review aims at highlighting some of the developments in lung neutrophil-immunity by focusing on the functions and roles of CXC/CC chemokines and pattern recognition receptors in neutrophil immunity during pulmonary inflammations. The pathophysiological roles of neutrophils in COVID-19 and thromboembolism have also been summarized. We finally summarized various neutrophil biomarkers that can be utilized as prognostic molecules in pulmonary inflammations and discussed various neutrophil-targeted therapies for neutrophil-driven pulmonary inflammatory diseases.

Mesenchymal Stem Cells in the Treatment of COVID-19, a Promising Future.

Mesenchymal stem cells (MSCs) are multipotent adult stem cells present in virtually all tissues; they have a potent self-renewal capacity and can differentiate into multiple cell types. They also affect the ambient tissue by the paracrine secretion of numerous factors in vivo, including the induction of other stem cells' differentiation. In vitro, the culture media supernatant is named secretome and contains soluble molecules and extracellular vesicles that retain potent biological function in tissue regeneration. MSCs are considered safe for human treatment; their use does not involve ethical issues, as embryonic stem cells do not require genetic manipulation as induced pluripotent stem cells, and after intravenous injection, they are mainly found in the lugs. Therefore, these cells are currently being tested in various preclinical and clinical trials for several diseases, including COVID-19. Several affected COVID-19 patients develop induced acute respiratory distress syndrome (ARDS) associated with an uncontrolled inflammatory response. This condition causes extensive damage to the lungs and may leave serious post-COVID-19 sequelae. As the disease may cause systemic alterations, such as thromboembolism and compromised renal and cardiac function, the intravenous injection of MSCs may be a therapeutic alternative against multiple pathological manifestations. In this work, we reviewed the literature about MSCs biology, focusing on their function in pulmonary regeneration and their use in COVID-19 treatment.

Thromboembolic events associated with immune checkpoint inhibitors: A real-world study of data from the food and drug administration adverse event reporting system (FAERS) database.

BACKGROUND: Although there have been a few studies reporting thromboembolic events (TEEs) in patients treated with immune checkpoint inhibitors (ICIs), the detailed profile of the TEEs and the prothrombotic effects of ICIs remain mostly unknown. METHODS: Data from January 2004 to December 2019 in the FAERS database were retrieved. We investigated the clinical characteristics of the TEEs and conducted disproportionality analysis by using reporting odds ratios (ROR) to compare ICIs with the full database and other anti-cancer agents. RESULTS: We identified 1855 reports of TEEs associated with ICIs. Affected patients tended to be male (59.68%) and older than 65 (47.12%). The case-fatality rate of the reported TEEs was high (38%). The median time to onset (TTO) of all cases was 42 (interquartile range [IQR] 15-96) days and the median TTO of fatal cases (31 [IQR 13-73] days) was significantly shorter than non-fatal cases (50 [IQR 20-108] days, p = 0.000002). ICIs showed increased risks of VTE (ROR 2.81, 95% CI 2.69-2.95) and ATE (ROR 1.44, 95% CI 1.37-1.52) compared with the full database. Compared with protein kinase inhibitors, ICIs showed an increased risk of VTE (ROR 1.23, 95% CI 1.17-1.29), but only anti-PD-L1 showed an increased risk of cerebral ATE (ROR 1.38, 95% CI 1.08-1.76). Compared with chemotherapy, ICIs showed an increased risk of PE (ROR 1.14, 95% CI 1.07-1.21). CONCLUSIONS: Our study suggested ICIs tend to increase risks of VTE and ATE. The poor clinical outcome and early onset of these events should attract clinical attention.

Antiphospholipid antibodies in critically ill COVID-19 patients with thromboembolism: cause of disease or epiphenomenon?

Coronavirus 2019 disease (COVID-19) is associated with coagulation dysfunction that predisposes patients to an increased risk for both arterial (ATE) and venous thromboembolism (VTE) and consequent poor prognosis; in particular, the incidence of ATE and VTE in critically ill COVID-19 patients can reach 5% and 31%, respectively. The mechanism of thrombosis in COVID-19 patients is complex and still not completely clear. Recent literature suggests a link between the presence of antiphospholipid antibodies (aPLs) and thromboembolism in COVID-19 patients. However, it remains uncertain whether aPLs are an epiphenomenon or are involved in the pathogenesis of the disease.

Inhibition of hypoxia inducible factor 1 by YC-1 attenuates tissue plasminogen activator induced hemorrhagic transformation by suppressing HMGB1/TLR4/NF-κB mediated neutrophil infiltration in thromboembolic stroke rats.

Hemorrhagic transformation (HT) is a frequent complication of ischemic stroke after thrombolytic therapy and seriously affects the prognosis of stroke. Due to the limited therapeutic window and hemorrhagic complications, tissue plasminogen activator (t-PA) is underutilized in acute ischemic stroke. Currently, there are no clinically effective drugs to decrease the incidence of t-PA-induced HT. Hypoxia-inducible factor 1 (HIF-1) is an important transcription factor that maintains oxygen homeostasis and mediates neuroinflammation under hypoxia. However, the effect of HIF-1 on t-PA-induced HT is not clear. The aim of this study was to investigate the role of HIF-1 in t-PA-induced HT by applying YC-1, an inhibitor of HIF-1. In the present study, we found that HIF-1 expression was significantly increased in ischemic brain tissue after delayed t-PA treatment and was mainly localized in neurons and endothelial cells. Inhibition of HIF-1 by YC-1 improved infarct volume and neurological deficits. YC-1 inhibited matrix metalloproteinase protein expression, increased tight junction protein expression, and ameliorated BBB disruption and the occurrence of HT. Furthermore, YC-1 suppressed the release of inflammatory factors, neutrophil infiltration and the activation of the HMGB1/TLR4/NF-κB signaling pathway. These results demonstrated that inhibition of HIF-1 could protect BBB integrity by suppressing HMGB1/TLR4/NF-κB-mediated neutrophil infiltration, thereby reducing the risk of t-PA-induced HT. Thus, HIF-1 may be a potential therapeutic target for t-PA-induced HT.

Fatal intracardiac and pulmonary arterial thromboembolic damage following ABO-incompatible living donor liver transplantation for autoimmune hepatitis: A case report.

RATIONALE: We present the case of a patient with autoimmune hepatitis who suffered fatal intracardiac and pulmonary arterial thromboembolic complications after ABO-incompatible living donor liver transplantation (ABOi LDLT) with splenectomy. PATIENT CONCERNS: A 46-year-old female (blood type B+) with autoimmune hepatitis and hepatitis B carrier status underwent elective ABOi LDLT. The donor liver was from a 51-year-old male living donor (blood type A+). A splenectomy was performed without bleeding complications. Intraoperatively, the patients hemodynamic condition was acceptable, with no evidence of thromboembolism on transesophageal echocardiography (TEE). DIAGNOSIS: Postoperatively, her platelet count increased from 15.0 to 263.0 (× 109/L) and thromboelastographic parameters indicated hypercoagulable state. She suffered acute circulatory collapse, respiratory distress and, eventually, a decline in mental status. The attending physicians in the intensive care unit (ICU) immediately performed resuscitation. INTERVENTIONS: The patient underwent emergency exploratory surgery. Intraoperatively, hypotension, bradycardia and arrhythmia developed, together with high central venous pressure. Assessment of cardiac structure and function using rescue TEE incidentally identified multiple, huge thromboembolic clots in the cardiac chambers; therefore, the patient underwent cardiac thromboembolectomy, including cardiopulmonary bypass with hypothermia therapy. OUTCOMES: Due to severe cardiac and respiratory distress, the patient required venoarterial extracorporeal membrane oxygenation (VAECMO) in the operating room and ICU. Despite continuous resuscitation in the ICU and maintenance of VAECMO, she suffered severe hypotension and massive bleeding that eventually led to death. LESSONS: In patients with autoimmune hepatitis, risk factors for thromboembolism should be rigorously controlled during the peak period of reactive thrombocytosis after ABOi LDLT with splenectomy.

Anti-protein C antibodies and acquired protein C resistance in SLE: novel markers for thromboembolic events and disease activity?

OBJECTIVES: Risk factors for thromboembolism in SLE are poorly understood. We hypothesized a possible role for protein C, based on its dual activity in inflammation and haemostasis and on the evidence of an association between acquired activated protein C (APC) resistance (APCR) and high-avidity anti-protein C antibodies (anti-PC) with a severe thrombotic phenotype in venous thrombosis APS patients. METHODS: In a cross-sectional study of 156 SLE patients, the presence and avidity of IgG anti-PC was established by in house-ELISA, and APCR to exogenous recombinant human APC (rhAPC) and Protac (which activates endogenous protein C) was assessed by thrombin generation-based assays. Associations with aPL profile, thrombotic history and disease activity (BILAG and SLEDAI-2K) were also established. RESULTS: Anti-PC were detected in 54.5% of patients and APCR in 59%. Anti-PC positivity was associated with APCR to both rhAPC (P <0.0001) and Protac (P =0.0001). High-avidity anti-PC, detected in 26.3% of SLE patients, were associated with APCR in patients with thrombosis only (P <0.05), and with the development of thrombosis over time (range: 0-52 years; P =0.014). High-avidity anti-PC levels correlated with SLEDAI-2K (P =0.033) and total BILAG (P =0.019); SLEDAI-2K correlated inversely with APCR to Protac (P =0.004). CONCLUSION: Anti-PC occur in patients with SLE, independently of aPL profile, and are associated with APCR. High-avidity anti-PC are associated with thrombosis and with active disease and might prove a novel marker to monitor the risk of thrombosis and disease progression in SLE.

Angiotensin-converting enzyme 2 (ACE2): COVID 19 gate way to multiple organ failure syndromes.

BACKGROUND: Globally, the current medical emergency for novel coronavirus 2019 (COVID-19) leads to respiratory distress syndrome and death. PURPOSE: This review highlighted the effect of COVID-19 on systemic multiple organ failure syndromes. This review is intended to fill a gap in information about human physiological response to COVID-19 infections. This review may shed some light on other potential mechanisms and approaches in COVID -19 infections towards systemic multiorgan failure syndromes. FINDING: SARS-CoV-2 intervened mainly in the lung with progression to pneumonia and acute respiratory distress syndrome (ARDS) via the angiotensin-converting enzyme 2(ACE2) receptor. Depending on the viral load, infection spread through the ACE2 receptor further to various organs such as heart, liver, kidney, brain, endothelium, GIT, immune cell, and RBC (thromboembolism). This may be aggravated by cytokine storm with the extensive release of proinflammatory cytokines from the deregulating immune system. CONCLUSION: The widespread and vicious combinations of cytokines with organ crosstalk contribute to systemic hyper inflammation and ultimately lead to multiple organ dysfunction (Fig. 1). This comprehensive study comprises various manifestations of different organs in COVID-19 and may assist the clinicians and scientists pertaining to a broad approach to fight COVID 19.

Alteraciones de la coagulación en la COVID-19.

Infection with the SARS-CoV-2 virus and the development of all manifestations of COVID-19, predisposes to arterial and venous thromboembolic disease. The coagulation system can be activated by various viruses, including SARS-CoV-2. Vascular endothelial damage, added to the development of disseminated intravascular coagulation, affects the prognosis and mortality from this disease. Treatment is aimed at the prevention, early detection and timely interventions of all coagulation disorders generated by COVID-19. The recommended anticoagulant is low molecular weight heparin, taking into account creatinine clearance, and if major invasive procedures will be performed, unfractionated heparin is a safe option.

La infección por el virus SARS-CoV-2 y el desarrollo de todas las manifestaciones de COVID-19 predisponen a la enfermedad tromboembólica arterial y venosa. El sistema de coagulación puede ser activado por diversos virus, entre ellos el SARS-CoV-2. El daño endotelial vascular, sumado al desarrollo de coagulación intravascular diseminada, afecta el pronóstico y la mortalidad de esta enfermedad. El tratamiento está dirigido a la prevención, la detección temprana y las intervenciones oportunas de todas las alteraciones de la coagulación generadas por la COVID-19. El anticoagulante recomendado es la heparina de bajo peso molecular, tomando en cuenta el aclaramiento de creatinina, y si se realizarán procedimientos invasivos mayores, la heparina no fraccionada es una opción segura.

Sphingosine-1-phosphate in anti-neutrophil cytoplasmic antibody-associated vasculitis: coagulation-related clinical indicators and complications.

BACKGROUND: Sphingosine-1-phosphate (S1P) plays a significant role in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). METHODS: We collected the plasma samples from 40 patients with AAV and 10 healthy volunteers. The plasma levels of S1P were tested by enzyme-linked immunosorbent assay (ELISA). The levels of serum creatinine (Scr) were tested by rate method, and then the estimated glomerular filtration rate (eGFR) of the patients was calculated from the Scr, age, and gender. Prothrombin time (PT), partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (FIB), fibrinogen reduction product (FDP), D-dimer and C-reactive protein (CRP) were tested by turbidimetric inhibition immunoassays. Platelets (PLTs) were tested by fluorescently labeled electrical impedance method. RESULTS: The plasma levels of S1P were significantly higher in AAV patients than in healthy volunteers. Correlation analysis showed that plasma levels of S1P were negatively correlated with glomerular filtration (P=0.022, r = -0.306), and positively correlated with circulating levels of Birmingham vasculitis activity score (BVAS), PLT and D-dimer, (P=0.004, r = 0.443; P<0.001, r = 0.654; P=0.006, r = 0.427). The 40 patients with AAV were classified into three groups: the thromboembolism group (with complications of cerebral infarction and myocardial infarction, n=6), cerebral ischemia group (n=4), and cerebral hemorrhage group (n=2). The plasma levels of S1P were highest in the thromboembolism group and lowest in the cerebral hemorrhage group (P=0.003). CONCLUSIONS: Plasma levels of S1P were associated with circulating levels of D-dimer, PLT and BVAS in the patients with AAV. Hence, plasma S1P level can be used as a biomarker to predict coagulation-related complications in AAV.

The potential role of microvascular pathology in the neurological manifestations of coronavirus infection.

Human coronaviruses are highly pathogenic viruses that pose a serious threat to human health. Examples include the severe acute respiratory syndrome outbreak of 2003 (SARS-CoV-1), the Middle East Respiratory Syndrome (MERS-CoV) outbreak of 2012, and the current SARS-CoV-2 (COVID-19) pandemic. Herein, we review the neurological manifestations of coronaviruses and discuss the potential pathogenic role of blood-brain barrier dysfunction. We present the hypothesis that pre-existing vascular damage (due to aging, cardiovascular disease, diabetes, hypertension or other conditions) facilitates infiltration of the virus into the central nervous system (CNS), increasing neuro-inflammation and the likelihood of neurological symptoms. We also discuss the role of a neuroinflammatory cytokine profile in both blood-brain barrier dysfunction and macrovascular disease (e.g. ischemic stroke and thromboembolism). Future studies are needed to better understand the involvement of the microvasculature in coronavirus neuropathology, and to test the diagnostic potential of minimally-invasive screening tools (e.g. serum biomarkers, fluorescein retinal angiography and dynamic-contrast MRI).

Is COVID-19 associated thrombosis caused by overactivation of the complement cascade? A literature review.

Severe acute respiratory syndrome coronavirus 2 is responsible for the current COVID-19 pandemic resulting in an escalating number of cases and fatalities worldwide. Preliminary evidence from these patients, as well as past coronavirus epidemics, indicates that those infected suffer from disproportionate complement activation as well as excessive coagulation, leading to thrombotic complications and poor outcome. In non-coronavirus cohorts, evidence has accumulated of an interaction between the complement and coagulation systems, with one amplifying activation of the other. A pressing question is therefore if COVID-19 associated thrombosis could be caused by overactivation of the complement cascade? In this review, we summarize the literature on thrombotic complications in COVID-19, complement activation in coronavirus infections, and the crosstalk between the complement and coagulation systems. We demonstrate how the complement system is able to activate the coagulation cascade and platelets, inhibit fibrinolysis and stimulate endothelial cells. We also describe how these interactions see clinical relevance in several disorders where overactive complement results in a prothrombotic clinical presentation, and how it could be clinically relevant in COVID-19.

Entangling COVID-19 associated thrombosis into a secondary antiphospholipid antibody syndrome: Diagnostic and therapeutic perspectives (Review).

The severe acute respiratory syndrome coronavirus 2 (SARS­CoV­2) is a novel ß coronavirus that is the etiological agent of the pandemic coronavirus disease 2019 (COVID­19) that at the time of writing (June 16, 2020) has infected almost 6 million people with some 450,000 deaths. These numbers are still rising daily. Most (some 80%) cases of COVID­19 infection are asymptomatic, a substantial number of cases (15%) require hospitalization and an additional fraction of patients (5%) need recovery in intensive care units. Mortality for COVID­19 infection appears to occur globally between 0.1 and 0.5% of infected patients although the frequency of lethality is significantly augmented in the elderly and in patients with other comorbidities. The development of acute respiratory distress syndrome and episodes of thromboembolism that may lead to disseminated intravascular coagulation (DIC) represent the primary causes of lethality during COVID­19 infection. Increasing evidence suggests that thrombotic diathesis is due to multiple derangements of the coagulation system including marked elevation of D­dimer that correlate negatively with survival. We propose here that the thromboembolic events and eventually the development of DIC provoked by SARS­CoV­2 infection may represent a secondary anti­phospholipid antibody syndrome (APS). We will apply both Baconian inductivism and Cartesian deductivism to prove that secondary APS is likely responsible for coagulopathy during the course of COVID­19 infection. Diagnostic and therapeutic implications of this are also discussed.

Immune Responses and Anti-inflammatory Strategies in a Clinically Relevant Model of Thromboembolic Ischemic Stroke with Reperfusion.

The poor clinical relevance of experimental models of stroke contributes to the translational failure between preclinical and clinical studies testing anti-inflammatory molecules for ischemic stroke. Here, we (i) describe the time course of inflammatory responses triggered by a thromboembolic model of ischemic stroke and (ii) we examine the efficacy of two clinically tested anti-inflammatory drugs: Minocycline or anti-CD49d antibodies (tested in stroke patients as Natalizumab) administered early (1 h) or late (48 h) after stroke onset. Radiological (lesion volume) and neurological (grip test) outcomes were evaluated at 24 h and 5 days after stroke. Immune cell responses peaked 48 h after stroke onset. Myeloid cells (microglia/macrophages, dendritic cells, and neutrophils) were already increased 24 h after stroke onset, peaked at 48 h, and remained increased-although to a lesser extent-5 days after stroke onset. CD8+ and CD4+ T-lymphocytes infiltrated the ipsilateral hemisphere later on (only from 48 h). These responses occurred together with a progressive blood-brain barrier leakage at the lesion site, starting 24 h after stroke onset. Lesion volume was maximal 24-48 h after stroke onset. Minocycline reduced both lesion volume and neurological deficit only when administered early after stroke onset. The blockade of leukocyte infiltration by anti-CD49d had no impact on lesion volume or long-term neurological deficit, independently of the timing of treatment. Our data are in accordance with the results of previous clinical reports on the use of Minocycline and Natalizumab on ischemic stroke. We thus propose the use of this clinically relevant model of thromboembolic stroke with recanalization for future testing of anti-inflammatory strategies for stroke.

Cardiovascular, thromboembolic and renal outcomes in IgA vasculitis (Henoch-Schönlein purpura): a retrospective cohort study using routinely collected primary care data.

BACKGROUND: IgA vasculitis (IgAV, Henoch-Schönlein purpura) is a small-vessel vasculitis most common in children but also occurring in adults. Case series have suggested that IgAV may be associated with cardiovascular disease and venous thromboembolism, but this has not been evaluated in population-based studies. Renal disease and hypertension are possible complications of the disease with unknown incidence. METHODS: Using a large UK primary care database, we conducted an open retrospective matched cohort study of cardiovascular, venous thrombotic and renal outcomes in adult-onset and childhood-onset IgAV. Control participants were selected at a 2:1 ratio, matched for age and sex. Adjusted HRs (aHRs) were calculated using Cox proportional hazards models. RESULTS: 2828 patients with adult-onset IgAV and 10 405 patients with childhood-onset IgAV were compared with age-matched and sex-matched controls. There was significantly increased risk of hypertension (adult-onset aHR 1.42, 95% CI 1.19 to 1.70, p < 0.001; childhood-onset aHR 1.52, 95% CI 1.22 to 1.89, p < 0.001) and stage G3-G5 chronic kidney disease (adult-onset aHR 1.54, 95% CI 1.23 to 1.93, p < 0.001; childhood-onset aHR 1.89, 95% CI 1.16 to 3.07, p=0.010). There was no evidence of association with ischaemic heart disease, cerebrovascular disease or venous thromboembolism. All-cause mortality was increased in the adult-onset IgAV cohort compared with controls (aHR 1.27, 95% CI 1.07 to 1.50, p=0.006). CONCLUSIONS: Patients with IgAV are at increased risk of hypertension and chronic kidney disease (CKD) compared with individuals without IgAV; analysis restricted to adult-onset IgAV patients showed increased mortality. Appropriate surveillance and risk factor modification could improve long-term outcomes in these patients.

Under crossfire: thromboembolic risk in systemic lupus erythematosus.

Cerebral and cardiovascular ischaemic events are frequent complications of SLE and constitute primary causes of permanent damage. However, the pathogenic determinants of an increased thromboembolic risk in patients with SLE are only partially understood. Atherosclerosis constitutes fertile soil for the development of thrombosis and shows disproportionately high prevalence and progression rates in patients with SLE. aPLs are independent risk factors for acute thrombosis but can also prompt long-term vascular inflammation. Aberrant interactions among immune cells and dysfunctions in the deployment of the coagulation cascade have historically been less explored in SLE, but recent evidence suggests they can also play a critical role at the crossroads between inflammation and haemostasis. In this review we discuss how different prothrombotic mechanisms can be prompted by and synergize with SLE-specific pathogenic events and speculate about novel potential directions for research and drug development.