The protective rather than prothrombotic fibrinogen in COVID-19 and other inflammatory states

Efficacy of a Multistrain Synbiotic Treatment in Acute and Post-Acute COVID-19 Patients: A Double-Blind, Placebo-Controlled Randomized Trial

BACKGROUND AND AIMS

Several studies reported the effect of COVID-19 on inducing gut dysbiosis, which is also correlated with disease severity. This study aims to investigate the effect of a nutraceutical formula on the shift of microbiota profiles and, secondly, on the clinical-pathological parameters of acute and post-acute COVID-19 patients.

METHODS

In this randomised, double-blind, placebo-controlled trial conducted at National Institute for Infectious diseases (INMI) Lazzaro Spallanzani (Italy), 52 patients were randomly assigned (1:1) to receive a multistrain synbiotic formula (Kebirah®) or placebo orally for 35 days at COVID-19 diagnosis. Health professionals, investigators, and patients were masked to group assignments. The V3-V4 hypervariable region of 16S rRNA gene sequencing was employed to study the gut microbiota composition in the two groups.

RESULTS

Supplementation with Kebirah® prevented the decrease in the Shannon diversity index of gut microbiota, which was instead observed in patients receiving the placebo. In addition, decreases in lymphocyte count and haemoglobin levels were observed only in the placebo group and not in the treated group, which was also characterised by an amelioration of the gut microbial profile, with an enrichment in beneficial bacteria and a preservation of species diversity.

CONCLUSIONS

Our data suggest that modulating the gut microbiota in acute disease through administration of a specific symbiotic formula could be a useful strategy in the frame of SARS-CoV-2 infections.

Changes in Hematological and Hemorheological Parameters Following Mild COVID-19: A 4-Month Follow-Up Study

BACKGROUND

Coronavirus Disease 2019 (COVID-19) was described to affect red blood cells (RBC) in both severe and mild disease courses. The aim of this study was to investigate whether hematological and hemorheological changes that were previously described for COVID-19 patients after the acute infection state are still prominent after another 4 months to assess potential long-term effects.

METHODS

Hematological and RBC rheological parameters, including deformability and aggregation, were measured 41 days after infection in COVID-19 patients and non-COVID control (T0) and 4 months later in COVID-19 patients (T1).

RESULTS

The data confirm alterations in hematological parameters, mainly related to cell volume and hemoglobin concentration, but also reduced deformability and increased aggregation at T0 compared to control. While RBC deformability seems to have recovered, hemoglobin-related parameters and RBC aggregation were still impaired at T1. The changes were thus more pronounced in male COVID-19 patients.

CONCLUSION

COVID-19-related changes of the RBC partly consist of several months and might be related to persistent symptoms reported by many COVID-19 patients.

The role of IL-6, ferritin, and coagulopathy in Covid-19 clinical progression

Background In COVID-19, the release of pro-inflammatory mediators in the cytokine storm, primarily interleukin-6 (IL-6), has been hypothesized to induce pulmonary intravascular coagulation. However, the relationship between IL-6 and coagulopathy remains unclear in COVID-19 progression. We aimed to investigate the correlation of IL-6 with D-dimer, fibrinogen, prothrombin time (PT), and ferritin. Furthermore, we also analyzed the effect of those parameters on the worsening of COVID-19 patients. Methods A prospective cohort study was conducted in moderate and severe COVID-19 patients from June 2020 to January 2021. A serial evaluation of IL-6, D-dimer, fibrinogen, ferritin, and PT was performed and correlated with the patient's condition at admission and on the 14th day. The outcomes (improvement, worsening, or discharged patients) were recorded during the study. Results Of 374 patients, 73 study subjects (61 severe and 12 moderate COVID-19) were included in this study. A total of 35 out of 61 severe and one out of 12 moderate illness subjects had experienced worsening. Spearman-rank correlation of IL-6 with with ferritin, D-dimer, fibrinogen, and PT was 0.08 ( p=0.5), -0.13 ( p=0.27), 0.01 ( p=0.91), and 0.03 ( p=0.77), respectively. In ROC analysis, D-dimer (74,77%) and IL-6 (71,32%) were the highest among other variables (>60%). Conclusions In COVID-19 patients, there was a correlation between elevated IL-6 and D-dimer levels with disease deterioration. There was no correlation between elevated IL-6 levels with ferritin, D-dimer, fibrinogen, and PT levels. Therefore, changes in IL-6 and D-dimer can predict worsening in moderate and severe COVID-19 patients.

The utility of serum amyloid A and other acute-phase reactants determination in ambulatory care COVID-19 patients

Background

The unpredictable course of Coronavirus Disease 19 (COVID-19) is making good severity assessment tools crucial. This study aimed to assess the usefulness of serum amyloid A (SAA) and other acute-phase reactants (APRs) in ambulatory care COVID-19 patients and identified relationships between these markers and disease outcomes.

Methods

From August to November 2020, patients seen in the outpatient department of the Clinic for Infectious and Tropical Diseases (Belgrade, Serbia) with confirmed COVID-19 were included. Patients were classified into mild, moderate, and severe disease groups based on World Health Organization criteria. SAA, C-reactive protein (CRP), interleukin-6 (IL-6), procalcitonin (PCT), ferritin, fibrinogen, D-dimer, albumin, and transferrin were measured. The median values of all APRs were compared between COVID-19 severity groups, hospitalized and non-hospitalized patients, and survivors and non-survivors. The Receiver operator characteristic (ROC) curve analysis was used for the classification characteristics assessment of individual APRs for the severity of illness, hospitalization, and survival.

COVID-19 Biomarkers at the Crossroad between Patient Stratification and Targeted Therapy: The Role of Validated and Proposed Parameters

Clinical knowledge about SARS-CoV-2 infection mechanisms and COVID-19 pathophysiology have enormously increased during the pandemic. Nevertheless, because of the great heterogeneity of disease manifestations, a precise patient stratification at admission is still difficult, thus rendering a rational allocation of limited medical resources as well as a tailored therapeutic approach challenging. To date, many hematologic biomarkers have been validated to support the early triage of SARS-CoV-2-positive patients and to monitor their disease progression. Among them, some indices have proven to be not only predictive parameters, but also direct or indirect pharmacological targets, thus allowing for a more tailored approach to single-patient symptoms, especially in those with severe progressive disease. While many blood test-derived parameters quickly entered routine clinical practice, other circulating biomarkers have been proposed by several researchers who have investigated their reliability in specific patient cohorts. Despite their usefulness in specific contexts as well as their potential interest as therapeutic targets, such experimental markers have not been implemented in routine clinical practice, mainly due to their higher costs and low availability in general hospital settings. This narrative review will present an overview of the most commonly adopted biomarkers in clinical practice and of the most promising ones emerging from specific population studies. Considering that each of the validated markers reflects a specific aspect of COVID-19 evolution, embedding new highly informative markers into routine clinical testing could help not only in early patient stratification, but also in guiding a timely and tailored method of therapeutic intervention.

Global Hemostasis Potential in COVID-19 Positive Patients Performed on St-Genesia Show Hypercoagulable State

BACKGROUND

At the dawn of the pandemic, severe forms of COVID-19 were often complicated by thromboembolisms. However, routine laboratory tests cannot be used to predict thromboembolic events. The objective of this study was to investigate the potential value of the thrombin generation test (TGT) in predicting hypercoagulability and thrombotic risk in the aforementioned set of patients.

METHODS

The study panel comprised 52 patients divided into two groups (26 COVID-19 positive and 26 COVID-19 negative); COVID-19-positive patients were further grouped in "severe" (n = 11) and "non-severe" (n = 15) categories based on clinical criteria. The routine blood tests and TGT of these patients were retrospectively analyzed.

RESULTS

All 26 COVID-19-positive patients showed decreased lymphocyte, monocyte and basophil counts and increased lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine transaminase (ALT) compared with control patients. Conversely, we did not observe statistically significant differences between severe and non-severe patients despite anecdotal variations in the distribution patterns. TGT without thrombomodulin (TM) addition showed statistically significant differences in the thrombin peak heights between COVID-19-positive and negative patients. After addition of TM, peak height, Endogenous Thrombin Potential (ETP) and velocity index were increased in all COVID-19-positive patients while the percentage of inhibition of ETP was reduced. These trends correlated with the severity of disease, showing a greater increase in peak height, ETP, velocity index and a drastic reduction in the percentage of ETP inhibition in more severely affected patients.

CONCLUSIONS

Our data suggest that all COVID-19 patients harbor a hypercoagulable TGT profile and that this is further pronounced in severely affected patients.

Fibrinogen, Fibrin, and Fibrin Degradation Products in COVID-19

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is the highly pathogenic and highly transmissible human coronavirus that is the causative agent for the worldwide COVID-19 pandemic. COVID-19 manifests predominantly as a respiratory illness with symptoms consistent with viral pneumonia, but other organ systems (e.g., kidney, heart, brain) can also become perturbed in COVID-19 patients. Accumulating data suggest that significant activation of the hemostatic system is a common pathological manifestation of SARS-CoV-2 infection. The clotting protein fibrinogen is one of the most abundant plasma proteins. Following activation of coagulation, the central coagulation protease thrombin converts fibrinogen to fibrin monomers, which selfassemble to form a matrix, the primary structural component of the blood clot. Severe COVID-19 is associated with a profound perturbation of circulating fibrinogen, intra- and extravascular fibrin deposition and persistence, and fibrin degradation. Current findings suggest high levels of fibrinogen and the fibrin degradation product D-dimer are biomarkers of poor prognosis in COVID-19. Moreover, emerging studies with in vitro and animal models indicate fibrin(ogen) as an active player in COVID-19 pathogenesis. Here, we review the current literature regarding fibrin(ogen) and COVID-19, including possible pathogenic mechanisms and treatment strategies centered on clotting and fibrin(ogen) function.

[Characteristic and prognosis of patients with non-EBV infection-associated hemophagocytic lymphohistiocytosis]

Objective: To explore the clinical characteristics and outcomes of patients with non-Epstein-Barr virus (EBV) infection-associated hemophagocytic lymphohistiocytosis (IAHLH) . Methods: Clinical data of 48 patients diagnosed with non-EBV IAHLH in Beijing Friendship Hospital from January 2015 to March 2021 were collected, and the clinical characteristics, treatment, curative effect and prognosis of the patients were analyzed retrospectively. Results: This study included 48 patients, 28 males and 20 females, with a median (range) age of 34.5 (2-74) years. Pathogens that cause IAHLH were as follows: virus (16 cases, 33.3%) , bacteria (17 cases, 35.4%) , parasitic agents (13 cases, 27.1%) , and fungi (2 cases, 4.2%) . The median time from onset to diagnosis of hemophagocytic syndrome (HLH) was 40 (10-160) days. The median (range) time duration from prodrome to the definite diagnosis of IAHLH was 67 (23-270) days. The clinical characteristics were fever (48 cases, 100%) , splenomegaly (34 cases, 70.8%) , cytopenia (38 cases, 79.1%) , elevated ferritin (45 cases, 93.8%) , elevated fasting triglyceride levels (7 cases, 14.6%) , hypofibrinogenemia (17 cases, 35.4%) , decrease natural killer cell activity (26 in 44 cases, 59.1%) , and elevated sCD25 (35 cases, 74.5%) . Twenty-five patients (52.1%) had adenopathy. Once a certain pathogen was identified as the causative factor of hemophagocytic lymphohistiocytosis (HLH) , cytotoxic agents and glucocorticoids were withdrawn, and specific pathogen-directed treatment was initiated. After treatment, 36 cases (75.0%) achieved complete response, and 14 of 15 patients (93.3%) with parasitic and fungal HLH got a response; however, the response rate of patient with bacterial and viral HLH was only 66.7% (22 of 33 patients) . The estimated 5-year overall survival rate was 72.3% (95%CI 50.3%-69.8%) . The adverse prognostic factors were total bilirubin over the upper limit of normal (OR=20.0, 95%CI 1.1-378.3, P=0.046) and pathogenic infection not fully controlled (OR=19.9, 95%CI 2.9-134.5, P=0.002) . Conclusion: Non-EBV IAHLH has a good prognosis. When diagnosed, cytotoxic agents and glucocorticoids should be tapered off, and pathogen-targeted therapy should be critically administered to clear the triggering infection.

Immunothrombosis Biomarkers for Distinguishing Coronavirus Disease 2019 Patients From Noncoronavirus Disease Septic Patients With Pneumonia and for Predicting ICU Mortality

Supplemental Digital Content is available in the text.

IMPORTANCE:

Coronavirus disease 2019 patients have an increased risk of thrombotic complications that may reflect immunothrombosis, a process characterized by blood clotting, endothelial dysfunction, and the release of neutrophil extracellular traps. To date, few studies have investigated longitudinal changes in immunothrombosis biomarkers in these patients. Furthermore, how these longitudinal changes differ between coronavirus disease 2019 patients and noncoronavirus disease septic patients with pneumonia are unknown.

OBJECTIVES:

In this pilot observational study, we investigated the utility of immunothrombosis biomarkers for distinguishing between coronavirus disease 2019 patients and noncoronavirus disease septic patients with pneumonia. We also evaluated the utility of the biomarkers for predicting ICU mortality in these patients.

DESIGN, SETTING, AND PARTICIPANTS:

The participants were ICU patients with coronavirus disease 2019 (n = 14), noncoronavirus disease septic patients with pneumonia (n = 19), and healthy age-matched controls (n = 14).

MAIN OUTCOMES AND MEASURES:

Nine biomarkers were measured from plasma samples (on days 1, 2, 4, 7, 10, and/or 14). Analysis was based on binomial logit models and receiver operating characteristic analyses.

RESULTS:

Cell-free DNA, d-dimer, soluble endothelial protein C receptor, protein C, soluble thrombomodulin, fibrinogen, citrullinated histones, and thrombin-antithrombin complexes have significant powers for distinguishing coronavirus disease 2019 patients from healthy individuals. In comparison, fibrinogen, soluble endothelial protein C receptor, antithrombin, and cell-free DNA have significant powers for distinguishing coronavirus disease 2019 from pneumonia patients. The predictors of ICU mortality differ between the two patient groups: soluble thrombomodulin and citrullinated histones for coronavirus disease 2019 patients, and protein C and cell-free DNA or fibrinogen for pneumonia patients. In both patient groups, the most recent biomarker values have stronger prognostic value than their ICU day 1 values.

CONCLUSIONS AND RELEVANCE:

Fibrinogen, soluble endothelial protein C receptor, antithrombin, and cell-free DNA have utility for distinguishing coronavirus disease 2019 patients from noncoronavirus disease septic patients with pneumonia. The most important predictors of ICU mortality are soluble thrombomodulin/citrullinated histones for coronavirus disease 2019 patients, and protein C/cell-free DNA for noncoronavirus disease pneumonia patients. This hypothesis-generating study suggests that the pathophysiology of immunothrombosis differs between the two patient groups.

The relation between fibrinogen level, neutrophil activity and nucleosomes in the onset of disseminated intravascular coagulation in the critically ill

BACKGROUND

Nucleosomes and neutrophil extracellular traps (NETs) are important in the pathophysiology of disseminated intravascular coagulation (DIC). Fibrinogen, as an acute phase reactant, may be protective by engaging neutrophils. We hypothesize that DIC can occur when NET formation becomes uncontrolled in relation to low fibrinogen levels.

PATIENTS/METHOD

The ratio of both circulating nucleosomes and human neutrophil elastase alpha-1-antitrypsine complexes (HNE-a1ATc) to fibrinogen was correlated to thrombocytopenia, DIC and organ failure in 64 critically ill coagulopathic patients.

RESULTS

A high nucleosome to fibrinogen ratio correlated with thrombocytopenia and organ failure (ρ -0.391, p 0.01 and ρ 0.556, p 0.01, respectively). A high HNE-a1ATc to fibrinogen ratio correlated with thrombocytopenia, DIC and organ failure (ρ -0.418, p 0.01, ρ 0.391, p 0.01 and ρ 0.477, p 0.01 respectively).

CONCLUSION

These findings support the hypothesis that fibrinogen is protective against DIC by counterbalancing excessive neutrophil activation.

Predictive value of D-dimer/albumin ratio and fibrinogen/albumin ratio for in-hospital mortality in patients with COVID-19

INTRODUCTION

Due to the high mortality of coronavirus disease 2019 (COVID-19), there are difficulties in the managing emergency department. We investigated whether the D-dimer/albumin ratio (DAR) and fibrinogen/albumin ratio (FAR) predict mortality in the COVID-19 patients.

METHODS

A total of 717 COVID-19 patients who were brought to the emergency department from March to October 2020 were included in the study. Levels of D-dimer, fibrinogen and albumin, as well as DAR, FAR, age, gender and in-hospital mortality status of the patients, were recorded. The patients were grouped by in-hospital mortality. Statistical comparison was conducted between the groups.

RESULTS

Of the patients included in the study, 371 (51.7%) were male, and their median age was 64 years (50-74). There was in-hospital mortality in 126 (17.6%) patients. The area under the curve (AUC) and odds ratio values obtained by DAR to predict in-hospital mortality were higher than the values obtained by the all other parameters (AUC of DAR, albumin, D-dimer, FAR and fibrinogen: 0.773, 0.766, 0.757, 0.703 and 0.637, respectively; odds ratio of DAR > 56.36, albumin < 4.015, D-dimer > 292.5, FAR > 112.33 and fibrinogen > 423:7.898, 6.216, 6.058, 4.437 and 2.794, respectively). In addition; patients with concurrent DAR > 56.36 and FAR > 112.33 had an odds ratio of 21.879 with respect to patients with concurrent DAR < 56.36 and FAR < 112.33.

CONCLUSION

DAR may be used as a new marker to predict mortality in COVID-19 patients. In addition, the concurrent high DARs and FARs were found to be more valuable in predicting in-hospital mortality than either separately.

Serial markers of coagulation and inflammation and the occurrence of clinical pulmonary thromboembolism in mechanically ventilated patients with SARS-CoV-2 infection; the prospective Maastricht intensive care COVID cohort

Background

The incidence of pulmonary thromboembolism is high in SARS-CoV-2 patients admitted to the Intensive Care. Elevated biomarkers of coagulation (fibrinogen and D-dimer) and inflammation (c-reactive protein (CRP) and ferritin) are associated with poor outcome in SARS-CoV-2. Whether the time-course of fibrinogen, D-dimer, CRP and ferritin is associated with the occurrence of pulmonary thromboembolism in SARS-CoV-2 patients is unknown. We hypothesise that patients on mechanical ventilation with SARS-CoV-2 infection and clinical pulmonary thromboembolism have lower concentrations of fibrinogen and higher D-dimer, CRP, and ferritin concentrations over time compared to patients without a clinical pulmonary thromboembolism.

Methods

In a prospective study, fibrinogen, D-dimer, CRP and ferritin were measured daily. Clinical suspected pulmonary thromboembolism was either confirmed or excluded based on computed tomography pulmonary angiography (CTPA) or by transthoracic ultrasound (TTU) (i.e., right-sided cardiac thrombus). In addition, patients who received therapy with recombinant tissue plasminogen activator were included when clinical instability in suspected pulmonary thromboembolism did not allow CTPA. Serial data were analysed using a mixed-effects linear regression model, and models were adjusted for known risk factors (age, sex, APACHE-II score, body mass index), biomarkers of coagulation and inflammation, and anticoagulants.

Results

Thirty-one patients were considered to suffer from pulmonary thromboembolism ((positive CTPA (n = 27), TTU positive (n = 1), therapy with recombinant tissue plasminogen activator (n = 3)), and eight patients with negative CTPA were included. After adjustment for known risk factors and anticoagulants, patients with, compared to those without, clinical pulmonary thromboembolism had lower average fibrinogen concentration of − 0.9 g/L (95% CI: − 1.6 – − 0.1) and lower average ferritin concentration of − 1045 μg/L (95% CI: − 1983 – − 106) over time. D-dimer and CRP average concentration did not significantly differ, 561 μg/L (− 6212–7334) and 27 mg/L (− 32–86) respectively. Ferritin lost statistical significance, both in sensitivity analysis and after adjustment for fibrinogen and D-dimer.

Conclusion

Lower average concentrations of fibrinogen over time were associated with the presence of clinical pulmonary thromboembolism in patients at the Intensive Care, whereas D-dimer, CRP and ferritin were not. Lower concentrations over time may indicate the consumption of fibrinogen related to thrombus formation in the pulmonary vessels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-021-00286-7.

Lessons learnt from COVID-19 coagulopathy

The coronavirus disease 2019 (COVID‐19) pandemic has already left an indelible mark in human lives. Despite the havoc it created, this pandemic also saw significant advances in the management of an infectious disease wherein worldwide collaborative efforts from health care professionals have been unprecedented. One of the commonest complications recognised early in the pandemic is the development of coagulopathy. In this review, the lessons learnt from COVID‐19 coagulopathy are summarised with some perspectives on future clinical and research strategies. These include how local versus systemic coagulopathy can matter, how we can put D‐dimers to effective use, exhort more input into identifying a simple platelet activation marker, rethink the role of fibrinogen, look differently at lupus anticoagulant and heparin‐induced thrombocytopenia, bring back disseminated intravascular coagulation into our differential diagnosis slate and most importantly channel more funding into haemostasis and thrombosis research.

Von Willebrand factor and ADAMTS13 activity as clinical severity markers in patients with COVID-19

The coronavirus disease 2019 (COVID-19) increases thrombotic risk. The mechanisms that lead to this prothrombotic state are not well established. The main aim was to evaluate the von Willebrand factor (VWF) antigen and plasma ADAMTS13 activity as endothelial injury markers in COVID-19. We present a prospective study in COVID-19 patients recruited in our institution. VWF antigen, ADAMTS13 activity, D-dimer, and fibrinogen were measured during the first week once COVID-19 was diagnosed. Fifty COVID-19 inpatients [44% in the intensive care unit (ICU)] and 102 COVID-19 outpatients were enrolled. Thirty age and gender matched non-COVID-19 ward inpatients and 30 non-COVID-19 healthy individuals were recruited. The COVID-19 inpatients had higher D-dimer, fibrinogen, and VWF antigen levels and a lower ADAMTS13 activity compared with the COVID-19 outpatients (p < 0.05). ICU patients had higher D-dimer and VWF antigen levels compared with the ward patients and the lowest ADAMTS13 activity (p < 0.05). An imbalance in VWF antigen/ADAMTS13 ratio was observed in COVID-19, reaching the highest in ICU patients. In contrast to other ward non-COVID-19 inpatients, a significative reduction in ADAMTS13 activity was observed in all COVID-19 patients. There is an increase in VWF antigen and an ADAMTS13 activity reduction in COVID-19 related to disease severity and could predict poor clinical outcomes. The ADAMTS13 activity reduction could be a marker associated with COVID-19 compared to other non-critical medical conditions.

Modulation of Hemostasis in COVID-19; Blood Platelets May Be Important Pieces in the COVID-19 Puzzle

Although the precise pathogenesis of coronavirus disease 2019 (COVID-19) currently remains unknown, its complex nature is gradually being revealed. COVID-19 is a disease caused by the SARS-CoV-2 virus and leads to respiratory dysfunction. Studies on hemostatic parameters have showed that COVID-19 significantly affects the disruption of the coagulation system and may contribute to coagulation and thrombotic events. A relevant cause of hemostasis disorders is inflammation and cytokine storms, which cause, for example, endothelial dysfunction in blood vessels. In order to prevent and treat states of hypercoagulability and thrombosis, the administration of anticoagulants, e.g., heparin, is recommended. The present mini-review describes the relationship between hemostasis and COVID-19, and discusses whether this relationship may cast light on the nature of COVID-19. The present short manuscript also examines the relationship between blood platelets and COVID-19. In addition, the paper explores the potential use of antiplatelet drugs in COVID-19 cases. The studies were identified by searching electronic databases, including PubMed and SCOPUS.

Fibrinogen Dysregulation is a Prominent Process in Fatal Conditions of COVID-19 Infection; a Proteomic Analysis

INTRODUCTION

Molecular pathophysiology of COVID-19 is not completely known. Expression changes in patients' plasma proteins have revealed new information about the disease. Introducing the key targeted plasma protein in fatal conditions of COVID-19 infection is the aim of this study.

METHODS

Significant differentially expressed proteins (DEPs) in the plasma of cases with a fatal condition of COVID-19 were extracted from an original article. These proteins were included in a network via STRING database along with 100 first neighbor proteins to determine central nodes of the network for analyzing.

RESULTS

Queried and added proteins were included in a scale free network. Three hub nodes were identified as critical target proteins. The top queried hub proteins were chains of fibrinogen; Fibrinogen Alpha chain (FGA), Fibrinogen gamma chain (FGG), and Fibrinogen beta chain (FGB), which are related to the coagulation process.

CONCLUSIONS

It seems that fibrinogen dysregulation has a deep impact on the fatality of COVID-19 infection.

Thrombin-Fibrin(ogen) Interactions, Host Defense and Risk of Thrombosis

Fibrinogen is a well-known risk factor for arterial and venous thrombosis. Its function is not restricted to clot formation, however, as it partakes in a complex interplay between thrombin, soluble plasma fibrinogen, and deposited fibrin matrices. Fibrinogen, like thrombin, participates predominantly in hemostasis to maintain vascular integrity, but executes some important pleiotropic effects: firstly, as observed in thrombin generation experiments, fibrin removes thrombin from free solution by adsorption. The adsorbed thrombin is protected from antithrombins, notably α2-macroglobulin, and remains physiologically active as it can activate factors V, VIII, and platelets. Secondly, immobilized fibrinogen or fibrin matrices activate monocytes/macrophages and neutrophils via Mac-1 interactions. Immobilized fibrin(ogen) thereby elicits a pro-inflammatory response with a reciprocal stimulating effect of the immune system on coagulation. In contrast, soluble fibrinogen prohibits recruitment of these immune cells. Thus, while fibrin matrices elicit a procoagulant response, both directly by protecting thrombin and indirectly through the immune system, high soluble fibrinogen levels might protect patients due to its immune diminutive function. The in vivo influence of the 'protective' plasma fibrinogen versus the 'pro-thrombotic' fibrin matrices on thrombosis should be explored in future research.

Hemostasis in Coronavirus Disease 2019-Lesson from Viscoelastic Methods: A Systematic Review

Hemostatic unbalance is often observed in patients with coronavirus disease 2019 (COVID-19), and patients with severe disease are at high risk of developing thromboembolic complications. Viscoelastic methods (VEMs), including thrombelastography (TEG) and thromboelastometry (TEM), provide data on the nature of hemostatic disturbance. In this systematic review, we assessed the performance of TEG and TEM in the assessment of blood coagulation and fibrinolysis in patients with COVID-19. PubMed, Scopus, Web of Science Core Collection, medRxiv, and bioRxiv were systematically searched for clinical studies evaluating TEG and/or TEM variables in COVID-19 individuals. Ten studies, with a total of 389 COVID-19 patients, were included, and VEMs were performed in 292 of these patients. Most patients (90%) presented severe COVID-19 and required mechanical ventilation. TEG and TEM variables showed that these patients displayed hypercoagulability and fibrinolysis shutdown, despite the use of appropriate thromboprophylaxis. However, the mechanism underlying these phenomena and their clinical significance in COVID-19 patients who developed thrombosis are still not clear. Further studies are warranted if VEMs might help to identify those at highest risk of thrombotic events and who therefore may derive the greatest benefit from antithrombotic therapy.

Coronavirus-induced coagulopathy during the course of disease

BACKGROUND

A significant proportion of patients with coronavirus disease 19 (COVID-19) suffer from excessive coagulation activation and coagulopathy which is associated with an increased risk of venous and arterial thromboembolism and adverse outcome. Our study investigates coagulation markers and the incidence of thromboembolic events in COVID-19 patients receiving recommended anticoagulation strategies.

METHODS

In a retrospective single-center analysis at the University Hospital Zurich, Switzerland, we investigated 31 adult COVID-19 patients between April 6th and May 13th, 2020 and with at least one laboratory assessment of the coagulation markers prothrombin time/Quick, thrombin time, fibrinogen and D-dimers. For antithrombotic prophylaxis low-molecular-weight-heparin or unfractionated heparin was administered and two patients with heparin-induced thrombocytopenia received argatroban.

RESULTS

We analyzed 31 patients (68% male, mean age 60± SD 15 years). 22 (71%) of these required intensive care unit treatment, 5 (16%) were hospitalized in a ward, and 4 (13%) were outpatients. Mean fibrinogen levels were markedly elevated to 6.4± SD 1.8g/l, with a peak in the third week of the disease and no significant decrease over time. D-dimers were elevated to a mean value of 5.1±4.4mg/l with peak levels of 6.8±5.3mg/l in the fourth week of disease, and a subsequent decrease. Platelet count (308±136G/l) and PT/Quick (85±22%) showed no significant changes over time. Sensitivity analyses for patients treated in the ICU showed that D-dimer levels were higher in this group. The results of other sensitivity analyses were comparable. Thromboembolic events were diagnosed in 4 (13%) patients and 5 (16%) patients died during the observation period.

CONCLUSION

We find coagulation alterations in COVID-19 patients indicating significant hypercoagulability. These alterations are visible despite antithrombotic treatment, and peak around week 3-4 of the disease.