Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in countless infections and caused millions of deaths since its emergence in 2019. Coronavirus disease 2019 (COVID-19)-associated mortality is caused by uncontrolled inflammation, aberrant immune response, cytokine storm, and an imbalanced hyperactive immune system. The cytokine storm further results in multiple organ failure and lung immunopathology. Therefore, any potential treatments should focus on the direct elimination of viral particles, prevention strategies, and mitigation of the imbalanced (hyperactive) immune system. This review focuses on cytokine secretions of innate and adaptive immune responses against COVID-19, including interleukins, interferons, tumor necrosis factor-alpha, and other chemokines. In addition to the review focus, we discuss potential immunotherapeutic approaches based on relevant pathophysiological features, the systemic immune response against SARS-CoV-2, and data from recent clinical trials and experiments on the COVID-19-associated cytokine storm. Prompt use of these cytokines as diagnostic markers and aggressive prevention and management of the cytokine storm can help determine COVID-19-associated morbidity and mortality. The prophylaxis and rapid management of the cytokine storm appear to significantly improve disease outcomes. For these reasons, this study aims to provide advanced information to facilitate innovative strategies to survive in the COVID-19 pandemic.

The Role of Cytokines and Chemokines in Severe Acute Respiratory Syndrome Coronavirus 2 Infections

Background A better understanding of COVID-19 immunopathology is needed to identify the most vulnerable patients and improve treatment options. Objective We aimed to identify immune system cell populations, cytokines, and inflammatory markers related to severity in COVID-19. Methods 139 hospitalized patients with COVID-19−58 mild/moderate and 81 severe/critical—and 74 recovered patients were included in a prospective longitudinal study. Clinical data and blood samples were obtained on admission for laboratory markers, cytokines, and lymphocyte subsets study. In the recovered patients, lymphocyte subsets were analyzed 8–12 weeks after discharge. Results A National Early Warning Score 2 >2 (OR:41.4; CI:10.38–167.0), ferritin >583 pg/mL (OR:16.3; CI: 3.88–69.9), neutrophil/lymphocyte ratio >3 (OR: 3.5; CI: 1.08–12.0), sIL-2rα (sCD25) >512 pg/mL (OR: 3.3; CI: 1.48–7.9), IL-1Ra >94 pg/mL (OR: 3.2; IC: 1.4–7.3), and IL-18 >125 pg/mL (OR: 2.4; CI: 1.1–5.0) were associated with severe/critical COVID-19 in the multivariate models used. Lower absolute values of CD3, CD4, CD8, and CD19 lymphocytes together with higher frequencies of NK cells, a CD4 and CD8 activated (CD38+HLA-DR+) memory T cell and effector memory CD45RA+ (EMRA) phenotype, and lower T regulatory cell frequencies were found in severe/critical patients relative to mild/moderate and recovered COVID-19 patients. A significant reduction in Th1, Tfh1, and Tc1 with higher Th2, Tfh2, Tc2, and plasma cell frequencies was found in the most severe cases. Conclusion A characteristic hyperinflammatory state with significantly elevated neutrophil/lymphocyte ratio and ferritin, IL-1Ra, sIL-2rα, and IL-18 levels together with a “low T1 lymphocyte signature” was found in severe/critical COVID-19 patients.

Hyperinflammatory State and Low T1 Adaptive Immune Response in Severe and Critical Acute COVID-19 Patients

Myeloid dysregulation and therapeutic intervention in COVID-19.

Recent advances in passive immunotherapies for COVID-19: The Evidence-Based approaches and clinical trials

COVID-19 is a multisystem disease caused by SARS-CoV-2 and is associated with an imbalance between the coagulation and fibrinolytic systems. Systemically, hypercoagulation, hypofibrinolysis and fibrin-clot resistance to fibrinolysis predispose patients to thrombotic and thromboembolic events. In the lungs, the virus triggers alveolar and interstitial fibrin deposition, endothelial dysfunction, and pulmonary intravascular coagulation, all events intrinsically associated with activation of inflammation and organ injury. Adding to the pathogenesis of COVID-19, there is a positive feedback loop by which local fibrin deposition in the lungs can fuel inflammation and consequently dysregulates coagulation, a process known as immunothrombosis. Therefore, fibrinolysis plays a central role in maintaining hemostasis and tissue homeostasis during COVID-19 by cleaning fibrin clots and controlling feed-forward products of coagulation. In addition, components of the fibrinolytic system have important immunomodulatory roles, as evidenced by studies showing the contribution of Plasminogen/Plasmin (Plg/Pla) to the resolution of inflammation. Herein, we review clinical evidence for the dysregulation of the fibrinolytic system and discuss its contribution to thrombosis risk and exacerbated inflammation in severe COVID-19. We also discuss the current concept of an interplay between fibrinolysis and inflammation resolution, mirroring the well-known crosstalk between inflammation and coagulation. Finally, we consider the central role of the Plg/Pla system in resolving thromboinflammation, drawing attention to the overlooked consequences of COVID-19-associated fibrinolytic abnormalities to local and systemic inflammation.

Current Drug Targets (CDT) special issue on Covid-19 and Coagulopathy Fibrinolysis in COVID-19: impact on clot lysis and modulation of inflammation.

Background Patients with severe COVID-19 seem to have a compromised antiviral response and hyperinflammation. Neutrophils are critical players in COVID-19 pathogenesis. IL-17A plays a major role in protection against extracellular pathogens and neutrophil attraction and activation. We hypothesized that secukinumab, an anti-IL17A monoclonal antibody, could mitigate the deleterious hyperinflammation in COVID-19. Methods BISHOP was an open-label, single-center, phase-II controlled trial. Fifty adults hospitalized Covid-19 patients, confirmed by a positive SARS-CoV-2 RT-PCR, were randomized 1:1 to receive 300mg of secukinumab subcutaneously at day-0 (group A) plus standard of care (SoC: antiviral drugs, antimicrobials, corticosteroids, and/or anticoagulants) or SoC alone (group B). A second dose of 300mg of secukinumab could be administered on day-7, according to staff judgment. The primary endpoint was ventilator-free days at day-28 (VFD-28). Secondary efficacy and safety outcomes were also explored. Findings An intention-to-treat analysis showed no difference in VFD-28: 23.7 (95%CI 19.6-27.8) in group A vs. 23.8 (19.9-27.6) in group B, p=0.62; There was also no difference in hospitalization time, intensive care unit demand, the incidence of circulatory shock, acute kidney injury, fungal or bacterial co-infections, and severe adverse events. Pulmonary thromboembolism was less frequent in group A (4.2% vs. 26.2% p=0.04). There was one death in each group. Viral clearance, defined by the viral load fold change (2-ΔΔCT) in upper airways, between day-0 and day-7, was also similar: 0.17 (0.05-0.56) in group A vs. 0.24 (0.10-0.57) in group B. Interpretation The efficacy of secukinumab in the treatment of Covid19 was not demonstrated. No difference between groups in adverse events and no unexpected events were observed. Funding Novartis Brazil supported this research providing expert input in the development of the project, drug supply, data management, and monitoring.

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Alessandra Dias Costa e Silva

Papers

Blockade of Interleukin Seventeen (IL-17A) with Secukinumab in Hospitalized COVID-19 patients - the BISHOP study.