NLRP3 inflammasome and interleukin-1 contributions to COVID-19-associated coagulopathy and immunothrombosis.

Immunothrombosis - immune-mediated activation of coagulation - is protective against pathogens, but excessive immunothrombosis can result in pathological thrombosis and multiorgan damage, as in severe Coronavirus Disease 2019 (COVID-19). The NACHT-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome produces major proinflammatory cytokines of the interleukin (IL)-1 family, IL-1ß and IL-18, and induces pyroptotic cell death. Activation of the NLRP3 inflammasome pathway also promotes immunothrombotic programs including release of neutrophil extracellular traps and tissue factor by leukocytes, and prothrombotic responses by platelets and the vascular endothelium. NLRP3 inflammasome activation occurs in patients with COVID-19 pneumonia. In preclinical models, NLRP3 inflammasome pathway blockade restrains COVID-19-like hyperinflammation and pathology. Anakinra, recombinant human IL-1 receptor antagonist, showed safety and efficacy, and is approved for the treatment of hypoxemic COVID-19 patients with early signs of hyperinflammation. The non-selective NLRP3 inhibitor colchicine reduced hospitalization and death in a subgroup of COVID-19 outpatients, but is not approved for the treatment of COVID-19. Additional COVID-19 trials testing NLRP3 inflammasome pathway blockers are inconclusive or ongoing. We herein outline the contribution of immunothrombosis to COVID-19-associated coagulopathy, and review preclinical and clinical evidence suggesting an engagement of the NLRP3 inflammasome pathway in the immunothrombotic pathogenesis of COVID-19. We also summarize current efforts to target the NLRP3 inflammasome pathway in COVID-19, and discuss challenges, unmet gaps and the therapeutic potential that inflammasome-targeted strategies may provide for inflammation-driven thrombotic disorders including COVID-19.

Venous thromboembolism secondary to hospitalization for COVID-19: patient management and long-term outcomes.

Background: Venous thromboembolism (VTE) is a complication of COVID-19 in hospitalized patients. Little information is available on long-term outcomes of VTE in this population. Objectives: We aimed to compare the characteristics, management strategies, and long-term clinical outcomes between patients with COVID-19-associated VTE and patients with VTE provoked by hospitalization for other acute medical illnesses. Methods: This is an observational cohort study, with a prospective cohort of 278 patients with COVID-19-associated VTE enrolled between 2020 and 2021 and a comparison cohort of 300 patients without COVID-19 enrolled in the ongoing START2-Register between 2018 and 2020. Exclusion criteria included age <18 years, other indications to anticoagulant treatment, active cancer, recent (<3 months) major surgery, trauma, pregnancy, and participation in interventional studies. All patients were followed up for a minimum of 12 months after treatment discontinuation. Primary end point was the occurrence of venous and arterial thrombotic events. Results: Patients with VTE secondary to COVID-19 had more frequent pulmonary embolism without deep vein thrombosis than controls (83.1% vs 46.2%, P <.001), lower prevalence of chronic inflammatory disease (1.4% and 16.3%, P <.001), and history of VTE (5.0% and 19.0%, P <.001). The median duration of anticoagulant treatment (194 and 225 days, P = 0.9) and the proportion of patients who discontinued anticoagulation (78.0% and 75.0%, P = 0.4) were similar between the 2 groups. Thrombotic event rates after discontinuation were 1.5 and 2.6 per 100 patient-years, respectively (P = 0.4). Conclusion: The risk of recurrent thrombotic events in patients with COVID-19-associated VTE is low and similar to the risk observed in patients with VTE secondary to hospitalization for other medical diseases.

VENOUS THROMBOEMBOLISM SECONDARY TO HOSPITALIZATION FOR COVID-19 DISEASE: PATIENT MANAGEMENT AND LONG-TERM OUTCOMES

Background Venous thromboembolism (VTE) is a complication of COVID-19 in hospitalized patients. Little information is available on long-term outcomes of VTE in this population. We compared characteristics, management strategies, and long-term clinical outcomes between patients with COVID-19 associated VTE and patients with VTE provoked by hospitalization for other acute medical illnesses. Methods Observational cohort study, with a prospective cohort of 278 COVID-19 patients with VTE enrolled between 2020 and 2021 and a comparison cohort of 300 non-COVID-19 patients enrolled in the ongoing START2-registry between 2018 and 2020. Exclusion criteria included age <18 years, other indications to anticoagulant treatment, active cancer, recent (<3 months) major surgery, trauma, pregnancy, participation in interventional studies. All patients were followed-up for a minimum of 12 months after treatment discontinuation. Primary endpoint was the occurrence of venous and arterial thrombotic events. Results Patients with VTE secondary to COVID-19 had more frequently PE without DVT than controls (83.1% vs 46.2%, p<0.001) and a lower prevalence of chronic inflammatory disease (1.4% and 16.3%,p<0.001) and history of VTE (5.0% and 19.0%, p<0.001). The median duration of anticoagulant treatment (194 and 225 days, p=n.s.) and the proportion of patients who discontinued anticoagulation (78.0% and 75.0%, p=n.s.) were similar between the two groups. Thrombotic event rates after discontinuation were 1.5 and 2.6 per 100 patient-years, respectively (p=n.s.). Conclusions The risk of recurrent thrombotic events in patients with COVID-19 associated VTE is low and similar to the risk observed in patients with VTE secondary to hospitalization for other medical diseases.

Use of placebo in clinical trials in COVID-19 pandemic times: considerations on pros, cons, challenges and limitations.

The ongoing coronavirus disease 2019 (COVID-19) pandemic has placed tremendous strain on health systems throughout the world. This has led to many clinical trials being launched in order to try to find ways to combat the disease. The unprecedented nature of the pandemic has been reflected in the methods used in some of these trials. Placebo-controlled randomized trials are considered the gold-standard, however, there are inherent challenges in the use of placebo, especially during COVID-19. We herein review the pros, cons, challenges and limitations of using placebo in clinical trials investigating treatments for COVID-19. We also discuss the importance of viewing research critically, examining the potential impact of placebo use or lack thereof, on blinding and possible biases. This becomes important as we assess the responses to the pandemic in preparation for a future pandemic. Although placebo-controlled clinical trials are the gold standard for clinical research, they may not be practically or ethically feasible during a pandemic. Choices accomplished to design many COVID-19 trials might reflect the unprecedently trying environment in which they were made. However, critical evaluation of the methodology and practice of scientific research remains a crucial part of the scientific process. Even when conducted as randomized double-blinded studies, residual biases may exist and interfere with the study conduct and interpretation of the data. A critical review of all data, remains essential to thoroughly assess the impact of a research study.

Eosinopenia as Predictor of Poor Outcome in Hospitalized COVID-19 Adult Patients from Waves 1 and 2 of 2020 Pandemic.

During SARS-CoV-2 infection, eosinopenia may reflect a hyperactive immune response. In this study of hospitalized COVID-19 patients, we aimed to better understand the prognostic value of severe eosinopenia (absolute eosinophil count = 0 G/L) and decipher its underlying mechanisms. We retrospectively analyzed the records of COVID-19 patients hospitalized from March to June 2020 in three university hospitals in Marseille, France. We assessed the association between severe eosinopenia and a composite poor outcome in these patients, including the need for oxygen supplementation at >6 L/min, ICU admission, and in-hospital death. Among the 551 COVID-19 patients included in this study, severe eosinopenia was found in 228 (51%) of them on admission to hospital and was associated with a composite poor outcome using multivariate analysis (OR = 2.58; CI95 [1.77−3.75]; p < 0.0001). We found a significant association between the presence of severe eosinopenia on admission and the elevation in C-reactive protein, ferritin, IP-10, and suPAR. The histological findings in a series of 37 autopsies from patients who died from severe COVID-19 and presented with severe eosinopenia showed no pulmonary eosinophil trapping. Severe eosinopenia can be a reliable biomarker associated with a composite poor outcome in hospitalized COVID-19 adult patients. It may reflect the magnitude of immune hyperactivation during severe-to-critical COVID-19.

Interleukin-1 and the NLRP3 inflammasome in COVID-19: Pathogenetic and therapeutic implications.

A hyperinflammatory response during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection crucially worsens clinical evolution of coronavirus disease 2019 (COVID-19). The interaction between SARS-CoV-2 and angiotensin-converting enzyme 2 (ACE2) triggers the activation of the NACHT, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome. Enhanced inflammasome activity has been associated with increased disease severity and poor prognosis. Evidence suggests that inflammasome activation and interleukin-1ß (IL-1ß) release aggravate pulmonary injury and induce hypercoagulability, favoring progression to respiratory failure and widespread thrombosis eventually leading to multiorgan failure and death. Observational studies with the IL-1 blockers anakinra and canakinumab provided promising results. In the SAVE-MORE trial, early treatment with anakinra significantly shortened hospital stay and improved survival in patients with moderate-to-severe COVID-19. In this review, we summarize current evidence supporting the pathogenetic role of the NLRP3 inflammasome and IL-1ß in COVID-19, and discuss clinical trials testing IL-1 inhibition in COVID-19.

Targeting the NLRP3 inflammasome in cardiovascular diseases.

The NACHT, leucine-rich repeat (LRR), and pyrin domain (PYD)-containing protein 3 (NLRP3) inflammasome is an intracellular sensing protein complex that plays a major role in innate immunity. Following tissue injury, activation of the NLRP3 inflammasome results in cytokine production, primarily interleukin(IL)-1ß and IL-18, and, eventually, inflammatory cell death - pyroptosis. While a balanced inflammatory response favors damage resolution and tissue healing, excessive NLRP3 activation causes detrimental effects. A key involvement of the NLRP3 inflammasome has been reported across a wide range of cardiovascular diseases (CVDs). Several pharmacological agents selectively targeting the NLRP3 inflammasome system have been developed and tested in animals and early phase human studies with overall promising results. While the NLRP3 inhibitors are in clinical development, multiple randomized trials have demonstrated the safety and efficacy of IL-1 blockade in atherothrombosis, heart failure and recurrent pericarditis. Furthermore, the non-selective NLRP3 inhibitor colchicine has been recently shown to significantly reduce cardiovascular events in patients with chronic coronary disease. In this review, we will outline the mechanisms driving NLRP3 assembly and activation, and discuss the pathogenetic role of the NLRP3 inflammasome in CVDs, providing an overview of the current and future therapeutic approaches targeting the NLRP3 inflammasome.

Direct oral anticoagulant plasma levels in hospitalized COVID-19 patients treated with dexamethasone.

Direct oral anticoagulants (DOACs) are not recommended in COVID-19 patients receiving dexamethasone because of potential drug-drug and drug-disease interactions affecting anticoagulant concentration and activity. To evaluate short- and long-term pharmacokinetic interactions, serial through and peak DOAC plasma levels were prospectively measured during and after dexamethasone therapy, as well as during the acute phase and after recovery from COVID-19 in hospitalized, non-critically ill patients undergoing treatment with DOACs. Thirty-three (18 males, mean age 79 years) consecutive patients received DOACs (17 apixaban, 12 rivaroxaban, 4 edoxaban) for atrial fibrillation (n = 22), venous thromboembolism (n = 10), and acute myocardial infarction (n = 1). Twenty-six patients also received dexamethasone at a dose of 6 mg once daily for a median of 14 days. Trough DOAC levels on dexamethasone were within and below expected reference ranges respectively in 87.5 and 8.3% of patients, with no statistically significant differences at 48-72 h and 14-21 days after dexamethasone discontinuation. Peak DOAC levels on dexamethasone were within expected reference ranges in 58.3% of patients, and below ranges in 33.3%, of whom over two thirds had low values also off dexamethasone. No significant differences in DOAC levels were found during hospitalization and after resolution of COVID-19. Overall, 28 patients were discharged alive, and none experienced thrombotic or bleeding events. In this study, dexamethasone administration or acute COVID-19 seemed not to affect DOAC levels in hospitalized, non-critically ill COVID-19 patients.

The role of IL-6 and IL-6 blockade in COVID-19.

INTRODUCTION: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces a dysregulated hyperinflammatory response. AREAS COVERED: Authors review evidence on IL-6 and IL-6 blockade in coronavirus disease 2019 (COVID-19) and discuss the pathophysiological and prognostic roles of this cytokine and the clinical impact of pharmacological blockade of IL-6 . The material includes original articles and reviews published from March 2020 to March 2021 and searched on PubMed, medRxiv, and bioRxiv. EXPERT OPINION: IL-6 is one of the most prominent pro-inflammatory cytokines. Increased levels are recorded in COVID-19 patients, especially those with severe-to-critical disease. Evidence is accumulating on the relevance of IL-6 as a prognostic marker in COVID-19. Since IL-6 is a druggable target for several inflammatory diseases, pharmacological blockers of the IL-6 signaling pathway were repurposed to blunt the abnormal SARS-CoV-2-induced cytokine release. Data are limited to few randomized controlled trials that reported encouraging, though not conclusive, results, indicating the usefulness of IL-6 blockade early in the course of the disease in patients with hyperinflammation and no or limited organ damage. Further research is warranted to explore the role of IL-6 in different COVID-19 phenotypes and identify subgroups of patients who may mostly benefit from IL-6 pathway inhibition.

Interleukin-6 receptor blockade with subcutaneous tocilizumab improves coagulation activity in patients with COVID-19.

BACKGROUND: Many COVID-19 patients develop a hyperinflammatory response which activates blood coagulation and may contribute to the occurrence of thromboembolic complications. Blockade of interleukin-6, a key cytokine in COVID-19 pathogenesis, may improve the hypercoagulable state induced by inflammation. The aim of this study was to evaluate the effects of subcutaneous tocilizumab, a recombinant humanized monoclonal antibody against the interleukin-6 receptor on coagulation parameters. METHODS: Hospitalized adult patients with laboratory-confirmed moderate to critical COVID-19 pneumonia and hyperinflammation, who received a single 324 mg subcutaneous dose of tocilizumab on top of standard of care were enrolled in this analysis. Coagulation parameters were measured before tocilizumab and at day 1, 3, and 7 after treatment. All patients were followed-up for 35 days after admission or until death. RESULTS: 70 patients (mean age 60 years, interquartile range 52-75) were included. Treatment with tocilizumab was associated with a reduction in D-dimer levels (-56%; 95% confidence interval [CI], -68% to -44%), fibrinogen (-48%; 95%CI, -60% to -35%), C-reactive protein (-93%; 95%CI, -99% to -87%), prothrombin time (-4%; 95%CI,-9% to 0.8%), and activated thromboplastin time (-4%; 95%CI,-8.7% to 0.8%), and an increase in platelet count (34%; 95%CI, 23% to 45%). These changes occurred already one day after treatment with sustained reductions throughout day 7. The improvement in coagulation was consistently observed in patients receiving prophylactic or therapeutic dose anticoagulants, and was paralleled by a rapid improvement in respiratory function. CONCLUSIONS: Subcutaneous tocilizumab was associated with significant improvement of blood coagulation parameters independently of thromboprophylaxis dose.

Low-dose subcutaneous tocilizumab to prevent disease progression in patients with moderate COVID-19 pneumonia and hyperinflammation.

AIM: This study aimed to evaluate the safety and efficacy profile of low-dose tocilizumab (TCZ), to prevent disease progression, subcutaneously administered to patients with moderate COVID-19 pneumonia and hyperinflammation. METHODS: Clinical characteristics and outcomes were retrospectively analysed of patients - with laboratory-confirmed bilateral COVID-19 pneumonia, hyperinflammation (C-reactive protein (CRP) ≥20 mg/dL), no hypoxaemia (oxygen saturation >90%), and no contraindications to TCZ - who were treated with subcutaneous TCZ (324 mg) administered within 48 h from hospitalization on top of standard of care (SOC). They were compared with matched controls treated with SOC only before TCZ was available at the institution. Clinical data were available for all patients until death or until day 35 for those discharged from hospital. FINDINGS: Ten consecutive patients (six males, median age 55 years) treated with TCZ on top of SOC, and ten patients (six males, median age 56 years) treated with SOC only were included. TCZ was well-tolerated with no clinically relevant adverse events. TCZ was associated with a reduction in CRP at day 1 (-50%, IQR -28 to -80) and day 3 (-89%, IQR -79 to -96; p = 0.005 for within-group), whereas there was no significant change in CRP values in the SOC group (p < 0.001 for between-group comparisons at both time points). TCZ resulted in a parallel improvement in oxygenation, as assessed by the ratio of partial pressure of oxygen to fraction of inspired oxygen (P/F) ratio, which increased at day 1 (+11%, IQR +6 to +16; p = 0.005 for within-group and p = 0.006 for between-group comparisons), and day 3 (+23%, IQR +16 to +34; p = 0.005 for within-group and p = 0.003 for between-group comparisons). None of the TCZ-treated patients had disease progression, defined as requirement of oxygen therapy or mechanical ventilation, whereas progression occurred in five (50%) patients among the SOC group. CONCLUSIONS: Low-dose subcutaneous TCZ may be a safe and promising therapeutic option administered on top of SOC to prevent disease progression in hospitalised patients with moderate COVID-19 and hyperinflammation.

Acute complications and mortality in hospitalized patients with coronavirus disease 2019: a systematic review and meta-analysis.

BACKGROUND: The incidence of acute complications and mortality associated with COVID-19 remains poorly characterized. The aims of this systematic review and meta-analysis were to summarize the evidence on clinically relevant outcomes in hospitalized patients with COVID-19. METHODS: MEDLINE, EMBASE, PubMed, and medRxiv were searched up to April 20, 2020, for studies including hospitalized symptomatic adult patients with laboratory-confirmed COVID-19. The primary outcomes were all-cause mortality and acute respiratory distress syndrome (ARDS). The secondary outcomes included acute cardiac or kidney injury, shock, coagulopathy, and venous thromboembolism. The main analysis was based on data from peer-reviewed studies. Summary estimates and the corresponding 95% prediction intervals (PIs) were obtained through meta-analyses. RESULTS: A total of 44 peer-reviewed studies with 14,866 COVID-19 patients were included. In general, risk of bias was high. All-cause mortality was 10% overall (95% PI, 2 to 39%; 1687/14203 patients; 43 studies), 34% in patients admitted to intensive care units (95% PI, 8 to 76%; 659/2368 patients; 10 studies), 83% in patients requiring invasive ventilation (95% PI, 1 to 100%; 180/220 patients; 6 studies), and 75% in patients who developed ARDS (95% PI, 35 to 94%; 339/455 patients; 11 studies). On average, ARDS occurred in 14% of patients (95% PI, 2 to 59%; 999/6322 patients; 23 studies), acute cardiac injury in 15% (95% PI, 5 to 38%; 452/2389 patients; 10 studies), venous thromboembolism in 15% (95% PI, 0 to 100%; patients; 3 studies), acute kidney injury in 6% (95% PI, 1 to 41%; 318/4682 patients; 15 studies), coagulopathy in 6% (95% PI, 1 to 39%; 223/3370 patients; 9 studies), and shock in 3% (95% PI, 0 to 61%; 203/4309 patients; 13 studies). CONCLUSIONS: Mortality was very high in critically ill patients based on very low-quality evidence due to striking heterogeneity and risk of bias. The incidence of clinically relevant outcomes was substantial, although reported by only one third of the studies suggesting considerable underreporting. TRIAL REGISTRATION: PROSPERO registration ID for this study is CRD42020177243 ( https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=177243 ).