Fibrinolytic Cascade Research Articles

Impact of Estetrol Combined with Drospirenone on Blood Coagulation and Fibrinolysis in Patients with Endometriosis: A Multicenter, Randomized, Open-Label, Active-Controlled, Parallel-Group Study.

Venous thromboembolism is a serious safety concern in women using combined oral contraceptives; ethinyl estradiol (EE) is widely used as an estrogen. Estetrol (E4) is a native estrogen with selective tissue activity and exclusively produced by the fetal liver. This study used a multicenter, randomized, open-label, active-controlled, parallel-group design to evaluate the effects of E4 combined with drospirenone (DRSP) on coagulation and fibrinolysis in Japanese patients with endometriosis. Participants were randomized to receive either E4 15 mg/DRSP 3 mg or EE 20 µg/DRSP 3 mg for 12 weeks. E4/DRSP and EE/DRSP were administered orally once a day in a cyclic regimen, ie, 24-day active use followed by a 4-day hormone-free period, and a flexible extended regimen, respectively, and blood coagulation and fibrinolysis markers were measured. The effect on coagulation and fibrinolysis was considerably less in the E4/DRSP group than in the EE/DRSP group. Major anticoagulant proteins, protein S (free, total) and tissue factor pathway inhibitor (free), were reduced following EE/DRSP treatment. Consequently, thrombin generation determined by the activated protein C sensitivity ratio was increased by approximately 4-fold in the EE/DRSP group than in the E4/DRSP group. Eventually, the fibrinolysis cascade was triggered to compensate for disturbed coagulation, and D-dimer levels were 4.7-fold higher in the EE/DRSP group than in the E4/DRSP group. This study demonstrated that the effect of E4/DRSP on the blood coagulation and fibrinolysis cascades was significantly less than that of EE/DRSP in participants with endometriosis, a disease of women of advanced and reproductive age (jRCT2080225090, https://jrct.niph.go.jp/en-latest-detail/jRCT2080225090).

Fibrin and Fibrinolytic Enzyme Cascade in Thrombosis: Unravelling the Role.

Blood clot formation in blood vessels (thrombosis) is a major cause of life-threatening cardiovascular diseases. These clots are formed by αA-, βB-, and ϒ-peptide chains of fibrinogen joined together by isopeptide bonds with the help of blood coagulation factor XIIIa. These clot structures are altered by various factors such as thrombin, platelets, transglutaminase, DNA, histones, and red blood cells. Various factors are used to dissolve the blood clot, such as anticoagulant agents, antiplatelets drugs, fibrinolytic enzymes, and surgical operations. Fibrinolytic enzymes are produced by microorganisms (bacteria, fungi, etc.): streptokinase of Streptococcus hemolyticus, nattokinase of Bacillus subtilis YF 38, bafibrinase of Bacillus sp. AS-S20-I, longolytin of Arthrobotrys longa, versiase of Aspergillus versicolor ZLH-1, etc. They act as a thrombolytic agent by either enhancing the production of plasminogen activators (tissue or urokinase types), which convert inactive plasminogen to active plasmin, or acting as plasmin-like proteins themselves, forming fibrin degradation products which cause normal blood flow again in blood vessels. Fibrinolytic enzymes may be classified in two groups, as serine proteases and metalloproteases, based on their catalytic properties, consisting of a catalytic triad responsible for their fibrinolytic activity having different physiochemical properties (such as molecular weight, pH, and temperature). The analysis of fibrinolysis helps to detect hyperfibrinolysis (menorrhagia, renal failure, etc.) and hypofibrinolysis (diabetes, obesity, etc.) with the help of various fibrinolytic assays such as a fibrin plate assay, fibrin microplate assay, the viscoelastic method, etc. These fibrinolytic activities serve as a key aspect in the recognition of numerous cardiovascular diseases and can be easily produced on a large scale with a short generation time by microbes and are less expensive.

Hereditary angioedema with an acute attack resolved after bone marrow transplantation for acute myeloid leukemia: a case report

BackgroundHereditary angioedema (HAE), which is caused by C1-inhibitor (C1-INH) deficiency or dysfunction, is a rare and potentially life-threatening disease. In patients with HAE, excess production of bradykinin causes acute unpredictable recurrent attacks of angioedema in localized regions, including the larynx and intestines. Given the fact that HAE is an autosomal dominant disease, C1-INH produced in patients with HAE is 50% of that produced in healthy individuals. However, most patients with HAE present plasma C1-INH function of < 25% owing to the chronic consumption of C1-INH by kallikrein–kinin, contact, complement, coagulation, and fibrinolysis cascades. Recently, several therapeutic options have been developed for acute attacks and prophylaxis in the treatment of HAE; however, currently, there is no curative therapy for HAE.Case presentationHere we report the case of a 48-year-old male patient who presented with a long-standing history of HAE and underwent bone marrow transplantation (BMT) for acute myeloid leukemia (AML) at the age of 39 years and has been in complete remission of AML and HAE thereafter. Notably, after BMT, his C1-INH function gradually increased as follows: < 25%, 29%, 37%, and 45.6%. Since his 20 s, he intermittently presented with an acute attack of HAE once every 3 months from the initial attack. Further, after undergoing BMT, the number of acute attacks decreased to twice within 4 years until the age of 45 years, and subsequently, the patient has been free of acute attacks. C1-INH is mainly synthesized by hepatocytes, but it is known to be partially produced and secreted from peripheral blood monocytes, macrophages, endothelial cells, and fibroblasts. We speculate that the C1-INH function may be increased by extrahepatic production of C1-INH, possibly synthesized by differentiated cells derived from hematopoietic and mesenchymal stem cells after BMT.ConclusionsThis case report supports efforts to focus on extrahepatic production of C1-INH in the next strategy of new treatment development for HAE.

EFFICACY OF TOPICAL TRANEXAMIC ACID TO REDUCE BLOOD LOSS AFTER CORONARY ARTERY BYPASS GRAFTING (CABG)

Background: Coronary Artery Bypass Grafting (CABG) with the use of cardiopulmonary bypass technique has a coagulopathy issue. Many factors act on the coagulation process such as heparin level, thrombocytopenia, increased fibrinolysis and acquired platelet dysfunction. The human body responds to stress with dramatic resilience. For example, bleeding diathesis is common with on pump, after injury clotting mechanisms are immediately activated to reduce blood loss, the blood volume is restored by shifting the fluids from extracellular compartment and redistribution of blood flow occurs. Fibrinolytic cascade is activated with CPB usage. Before it was thought that excessive bleeding after CPB was due to platelet dysfunction and depletion. Recently, it was suggested by many lines of information that fibrinolytic cascade activation leads to bleeding during postoperative period. Multiple agents like Tranexamic acid and Aminocaproic acid etc are anti-fibrinolytic agents that can be administered to minimize the bleeding postoperatively.&#x0D; Objectives: To compare the efficacy of topical application of Tranexamic acid to reduce blood loss after Coronary Artery Bypass Grafting (CABG).&#x0D; Methods: It is randomized controlled trial. This research program was carried out at the Unit of Cardiothoracic &amp; Vascular Surgery, Institute of Shaikh Zayed Hospital, Lahore from December 6th, 2017 to December 5th, 2018. First patient evaluated on 11th December 2017. Seventy patients were enrolled, who were eligible for this study, achieving the inclusion criteria. Two groups of the selected population were made by randomization. Group A comprised 35 patients to whom 1 gm of diluted Tranexamic Acid using 100 ml normal saline solution is poured to the pericardial cavity. Group B involved 35 patients as well, whom were given standard of care treatment which in this case is 100 ml normal saline. Since 100ml normal saline did not contain any active ingredient for treatment, therefore it was considered as placebo. Intervention (Placebo or TXA) was considered efficacious if it resulted in blood loss of less than 500ml in 72 hours from immediately post-op to 72 hours post-op. The efficacy of drugs within groups is compared by the use of Chi-square test. Independent sample t-test was applied for data analysis of blood loss with p-value ≤0.05 being taken as significant.&#x0D; Results: In our study, total70patients were enrolled. Group-A (Tranexamic Acid) and Group-B (Placebo) were made. In group-A, there were 30 (85.7%) male and 5(14.3%) female patients. In group-B, 28(80.0%) were male and 7(20.0%) were female. In our study population, mean age of patients were 52.4±9.9 years and 53.6±10.1 years in group A&amp;B respectively. In group-A, there were 22(62.9%) patients in which the intervention showed efficacy (blood loss &lt;500ml), while only 09(25.7%) patients in group-B showed blood loss of &lt;500ml, p-value of 0.002 being statistically significant.&#x0D; Conclusion: Topical application of Tranexamic Acid reduces blood loss after Coronary Artery Bypass Grafting (CABG).

The potential of heparin-induced extracorporeal LDL/fibrinogen precipitation (H.E.L.P.)-apheresis for patients with severe acute or chronic COVID-19.

Patients with long COVID and acute COVID should benefit from treatment with H.E.L.P. apheresis, which is in clinical use for 37 years. COVID-19 can cause a severe acute multi-organ illness and, subsequently, in many patients the chronic illness long-COVID/PASC. The alveolar tissue and adjacent capillaries show inflammatory and procoagulatory activation with cell necrosis, thrombi, and massive fibrinoid deposits, namely, unsolvable microthrombi, which results in an obstructed gas exchange. Heparin-induced extracorporeal LDL/fibrinogen precipitation (H.E.L.P.) apheresis solves these problems by helping the entire macro- and microcirculation extracorporeally. It uses unfractionated heparin, which binds the spike protein and thereby should remove the virus (debris). It dissolves the forming microthrombi without bleeding risk. It removes large amounts of fibrinogen (coagulation protein), which immediately improves the oxygen supply in the capillaries. In addition, it removes the precursors of both the procoagulatory and the fibrinolytic cascade, thus de-escalating the entire hemostaseological system. It increases myocardial, cerebral, and pulmonary blood flow rates, and coronary flow reserve, facilitating oxygen exchange in the capillaries, without bleeding risks. Another factor in COVID is the “cytokine storm” harming microcirculation in the lungs and other organs. Intervention by H.E.L.P. apheresis could prevent uncontrollable coagulation and inflammatory activity by removing cytokines such as interleukin (IL)-6, IL-8, and TNF-α, and reduces C-reactive protein, and eliminating endo- and ecto-toxins, without touching protective IgM/IgG antibodies, leukocyte, or platelet function. The therapy can be used safely in combination with antiviral drugs, antibiotics, anticoagulants, or antihypertensive drugs. Long-term clinical experience with H.E.L.P. apheresis shows it cannot inflict harm upon patients with COVID-19.

Indices of complement activation and coagulation changes in trauma patients

ObjectivesEarly complementopathy and coagulopathy are shown often after trauma. However, the prevalence of any interplay between complement cascade (ComC) and coagulation cascade (CoaC) after trauma remains unclear. This study intended...

Chemerin Forms: Their Generation and Activity.

Chemerin is the product of the RARRES2 gene which is secreted as a precursor of 143 amino acids. That precursor is inactive, but proteases from the coagulation and fibrinolytic cascades, as well as from inflammatory reactions, process the C-terminus of chemerin to first activate it and then subsequently inactivate it. Chemerin can signal via two G protein-coupled receptors, chem1 and chem2, as well as be bound to a third non-signaling receptor, CCRL2. Chemerin is produced by the liver and secreted into the circulation as a precursor, but it is also expressed in some tissues where it can be activated locally. This review discusses the specific tissue expression of the components of the chemerin system, and the role of different proteases in regulating the activation and inactivation of chemerin. Methods of identifying and determining the levels of different chemerin forms in both mass and activity assays are reviewed. The levels of chemerin in circulation are correlated with certain disease conditions, such as patients with obesity or diabetes, leading to the possibility of using chemerin as a biomarker.

Brain proteome profiling implicates the complement and coagulation cascade in multiple system atrophy brain pathology.

BackgroundMultiple system atrophy (MSA) is a rare, progressive, neurodegenerative disorder presenting glia pathology. Still, disease etiology and pathophysiology are unknown, but neuro-inflammation and vascular disruption may be contributing factors to the disease progression. Here, we performed an ex vivo deep proteome profiling of the prefrontal cortex of MSA patients to reveal disease-relevant molecular neuropathological processes. Observations were validated in plasma and cerebrospinal fluid (CSF) of novel cross-sectional patient cohorts.MethodsBrains from 45 MSA patients and 30 normal controls (CTRLs) were included. Brain samples were homogenized and trypsinized for peptide formation and analyzed by high-performance liquid chromatography tandem mass spectrometry (LC–MS/MS). Results were supplemented by western blotting, immuno-capture, tissue clearing and 3D imaging, immunohistochemistry and immunofluorescence. Subsequent measurements of glial fibrillary acid protein (GFAP) and neuro-filament light chain (NFL) levels were performed by immunoblotting in plasma of 20 MSA patients and 20 CTRLs. Finally, we performed a proteome profiling of 144 CSF samples from MSA and CTRLs, as well as other parkinsonian disorders. Data were analyzed using relevant parametric and non-parametric two-sample tests or linear regression tests followed by post hoc tests corrected for multiple testing. Additionally, high-throughput bioinformatic analyses were applied.ResultsWe quantified more than 4,000 proteins across samples and identified 49 differentially expressed proteins with significantly different abundances in MSA patients compared with CTRLs. Pathway analyses showed enrichment of processes related to fibrinolysis and complement cascade activation. Increased fibrinogen subunit β (FGB) protein levels were further verified, and we identified an enriched recognition of FGB by IgGs as well as intra-parenchymal accumulation around blood vessels. We corroborated blood–brain barrier leakage by a significant increase in GFAP and NFL plasma levels in MSA patients that correlated to disease severity and/or duration. Proteome profiling of CSF samples acquired during the disease course, confirmed increased total fibrinogen levels and immune-related components in the soluble fraction of MSA patients. This was also true for the other atypical parkinsonian disorders, dementia with Lewy bodies and progressive supra-nuclear palsy, but not for Parkinson’s disease patients.ConclusionOur results implicate activation of the fibrinolytic cascade and immune system in the brain as contributing factors in MSA associated with a more severe disease course.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00018-022-04378-z.

Role of Plasminogen Activation System in Platelet Pathophysiology: Emerging Concepts for Translational Applications.

Traditionally, platelets have been exclusively considered for their procoagulant and antifibrinolytic effects during normal activation of hemostasis. Effectively, activated platelets secrete coagulation factors, expose phosphatidylserine, and promote thrombin and fibrin production. In addition to procoagulant activities, platelets confer resistance of thrombi to fibrinolysis by inducing clot retraction of the fibrin network and release of huge amounts of plasminogen activator inhibitor-1, which is the major physiologic inhibitor of the fibrinolytic cascade. However, the discovery of multiple relations with the fibrinolytic system, also termed Plasminogen Activation System (PAS), has introduced new perspectives on the platelet role in fibrinolysis. Indeed, the activated membrane surface of platelets provides binding sites on which fibrinolytic enzymes can be activated. This review discusses the evidence of the profibrinolytic properties of platelets through the description of PAS components and related proteins that are contained in or bind to platelets. Our analyses of literature data lead to the conclusion that in the initial phase of the hemostatic process, antifibrinolytic effects prevail over profibrinolytic activity, but at later stages, platelets might enhance fibrinolysis through the engagement of PAS components. A better understanding of spatial and temporal characteristics of platelet-mediated fibrinolysis during normal hemostasis could improve therapeutic options for bleeding and thrombotic disorders.

Abstract 1122‐000005: Plasminogen Activator Inhibitor‐1 5G/5G Polymorphism – Do We Know All About It?

Introduction : The etiology of ischemic stroke is heterogeneous, and it has been proposed that different stroke subtypes might have different genetic architecture 1,2. The plasminogen activator inhibitor‐1 (PAI‐1) has been of particular interest due to its role in thrombotic diseases. Several polymorphisms have been found for this gene, with some having protective effect while others increase the risk of ischemic and hemorrhagic strokes 3,4. The protective role appears to be due to the role of PAI‐1 in fibrinolytic cascade and that PAI‐1 also inhibit plasmin‐dependent metalloproteinases activation. We hereby, present a case of ischemic stroke in young adult and its association with our gene of interest. Methods : Case: We present a case of 43‐year‐old woman with past medical history significant for Acetylcholine Receptor (AChR) antibody positive Myasthenia Gravis diagnosed in 1993 status post thymectomy (1994), currently on prednisone and intravenous immunoglobulin every two weeks (failed cyclosporine and mycophenolate mofetil). She had two events in 2018 where she reported episodic right sided numbness and weakness that lasted for few hours. Stroke workup was done, and she was found to have focal moderate to severe stenosis of the left middle cerebral artery (MCA) on CT angiography (figure 1) with very subtle left hypoperfusion in the MCA on the brain single‐photon emission computerized tomography scan. She underwent catheter angiogram (figure 1) showing severe stenosis involving the mid and distal M1 segment of the left MCA and nondominant proximal A1 segment left anterior cerebral artery (ACA). There were robust leptomeningeal collaterals from the left anterior and left posterior cerebral arteries. She also reported history of two miscarriages in the first trimester. Hypercoagulable workup was done and all of those were negative including: SLE profile, Lupus anticoagulant, ANA comprehensive panel, Cryoglobulin, Anticardiolipin antibody, Antithrombin III, Antithrombin antigen, protein C, protein S, Factor VIII activity, Factor V Leiden. She also had rheumatoid arthritis factor, Homocysteine, sedimentation rate, and C‐reactive protein done which were unremarkable. Genetic workup showed that she is PAI‐1 5G/5G homozygous. She has been stable since 2018 without new focal neurological events and is on Aspirin monotherapy and Statin. Results : The genetics for stroke disease are very complicated and yet to be discovered fully. The association between PA‐1 5G/5G and intracranial stenosis has not been reported previously. New genetic associations will need to be increasingly considered as we assess our cerebrovascular diseases and stroke patients Conclusions : • With the current knowledge, ischemic stroke have polygenic basis but no single common “stroke gene” has been identified yet. • Here we present a case suggesting that PAI‐1 5G/5G genotype is may be associated with an independent risk of intracranial atherosclerosis.

The role of SERPIN citrullination in thrombosis

Aberrant protein citrullination is associated with many pathologies; however, the specific effects of this modification remain unknown. We have previously demonstrated that serine protease inhibitors (SERPINs) are highly citrullinated in rheumatoid arthritis (RA) patients. These citrullinated SERPINs include antithrombin, antiplasmin, and t-PAI, which regulate the coagulation and fibrinolysis cascades. Notably, citrullination eliminates their inhibitory activity. Here, we demonstrate that citrullination of antithrombin and t-PAI impairs their binding to their cognate proteases. By contrast, citrullination converts antiplasmin into a substrate. We recapitulate the effects of SERPIN citrullination using invitro plasma clotting and fibrinolysis assays. Moreover, we show that citrullinated antithrombin and antiplasmin are increased and decreased in a deep vein thrombosis (DVT) model, accounting for how SERPIN citrullination shifts the equilibrium toward thrombus formation. These data provide a direct link between increased citrullination and the risk of thrombosis in autoimmunity and indicate that aberrant SERPIN citrullination promotes pathological thrombus formation.

Supra-Physiological Concentrations of C1 Esterase Inhibitor Enhance Thrombin Generation in the Presence of Thrombomodulin

Introduction. Human C1-esterase inhibitor (C1INH) is a multifunctional plasma glycoprotein with a broad spectrum biological activities, best known for its role in regulation of the classical complement pathway, contact activation system and its essential roles in the coagulation and fibrinolytic cascades [1,2]. The main targets of C1INH are C1 esterase, Factors XIa and XIIa, kallikrein, thrombin and plasmin. Low levels of functional C1INH in plasma are considered to be the primary cause for hereditary angioedema (HAE) with symptoms of swelling in the face, throat, hands, feet and abdomen. HAE patients receive replacement therapy with plasma-derived C1INH products recently licensed in the US and EU for prophylactic and acute treatment of HAE [1]. Studies suggest that supra-physiological doses of C1INH can promote thrombotic events.. To date the use of C1INH at plasma concentrations exceeding normal have been proposed in a range of disease states including renal transplant, myocardial infarction and acute lung injury. However, the mechanism and concentration required to augment the risk of thromboembolic events remains unclear and therefore raises questions about the safety of high dose C1INH therapy. We evaluated all possible sites of the C1INH concentration-dependent interaction with the coagulation system and here we focus on a hypothesis that supra-physiological concentrations of C1INH alter the anticoagulant protein C system. To study the interactive role of C1INH and the protein C pathway we performed thrombin generation assays (TGA) on plasmas from both male and female healthy donors in the presence of supra-physiologic concentrations of C1INH and increasing concentrations of thrombomodulin (TM).Methods. Platelet poor plasma (PPP) was isolated by centrifugation from blood of 20 healthy donors and mixed with 16 IU/ml of C1INH or with the same volume of buffer. The used C1INH concentration was 16 times bigger than normal values. Concentrations of TM added to the plasma samples were equal to 3, 6, 9, 12 and 15 nM. 4.5 pm tissue factor-induced thrombin generation was performed by continuous measurement of thrombin proteolytic activity of thrombin-specific substrate Z-Gly-Gly-Arg-AMC added to PPP before induction of coagulation. Thrombin peak was calculated using Origin software. Wilcoxon and sign paired tests with P=0.05 were used to obtain statistics.Results and conclusions. C1INH significantly reduced thrombin peak up to 2 times in the absence and at the lowest concentrations of TM (3 and 6 nM). Addition of 9 nM TM caused disappearance of the difference between the samples with and without C1INH. Finally, in the presence of 12 and 15 nM of TM, C1INH significantly enhanced thrombin peak (Figure 1A, B). Figure 1B demonstrates that reducing C1INH concentration can bring the thrombin peak back to the values obtained without C1INH presence. These results indicate that presence of TM crucially change the action of C1INH on coagulation and explains how supra-physiological concentrations of coagulation inhibitor may cause thrombosis in certain clinical situations.Figure 1. A: Effect of elevation of C1INH concentration on thrombin peak. Statistics was obtained using Wilcoxon (*) and Sign (**) paired tests with P value equal to 0.05 from 20 healthy donors. B: Representative dependence of thrombin peak on TM concentration with and without the presence of 16 IU/ml C1INH. C: representative dependence of Thrombin peak on C1INH concentration in the presence of TM.

HEREDITARY THROMBOPHILIA IN RECURRENT IVF FAILURE

Background: The predominant part of IVF cycles results in embryo transfer, but only about one third of all cycles reach clinically achieved pregnancy. This is evidence that most embryos failed in an early stage of pregnancy achievement. Recurrent implantation failure after IVF procedures emphasize the clinical importance of this crucial step in assisted reproductive technology. Repeated unsuccessful IVF attempts force efforts to investigate the firm mechanism of the implantation and to find approach to increase pregnancy outcome success. Plenty of factors have been recognized to affect either success, or failure rate of IVF embryo transfer. Maternal side factors include age, parity, hormonal levels before stimulation, antral follicles count, endometrial thickness and quality of transformed endometrium. Other factors, having functions in coagulation and fibrinolysis cascades, were found to be connected with the transformation processes in the endometrium during the implantation.Aim of work: The aim from this study is to evaluate the relation between hereditary thrombophilia and recurrent IVF failure. This will be done by comparing the prevalence of thrombophilia factors mutation in patients with repeated IVF failure and in normal population.Methods: Thirty patients with recurrent IVF failure underwent genetic testing of thrombophilia markers by PCR: Factor II prothrombin mutation, Factor V leiden mutation (FVL), and Methylene tetrahydrofolate reductase (MTHFR) mutation.Results: 13.3% were tested positive for factor V mutation G1619A, 56.7% were positive for MTHFR c667t mutation. While in healthy normal Mediterranean population the percentage of mutation were 3.7% for FVL mutation and 11.1% for MTHFR mutation.Conclusion: hereditary thrombophilia may be considered as a factor in recurrent IVF failure, proper management is to be considered.

Fibrinolysis in Traumatic Brain Injury: Diagnosis, Management, and Clinical Considerations.

Posttraumatic coagulopathy involves disruption of both the coagulation and fibrinolytic pathways secondary to tissue damage, hypotension, and inflammatory upregulation. This phenomenon contributes to delayed complications after traumatic brain injury (TBI), including intracranial hemorrhage progression and systemic disseminated intravascular coagulopathy. Development of an early hyperfibrinolytic state may result in uncontrolled bleeding and is associated with increased mortality in patients with TBI. Although fibrinolytic assays are not routinely performed in the assessment of posttraumatic coagulopathy, circulating biomarkers such as D-dimer and fibrin degradation products have demonstrated potential utility in outcome prediction. Unfortunately, the relatively delayed nature of these tests limits their clinical utility. In contrast, viscoelastic tests are able to provide a rapid global assessment of coagulopathy, although their ability to reliably identify disruptions in the fibrinolytic cascade remains unclear. Limited evidence supports the use of hypertonic saline, cryoprecipitate, and plasma to correct fibrinolytic disruption; however, some studies suggest more harm than benefit. Recently, early use of tranexamic acid in patients with TBI and confirmed hyperfibrinolysis has been proposed as a strategy to further improve clinical outcomes. Moving forward, further delineation of TBI phenotypes and the clinical implications of fibrinolysis based on phenotypic variation is needed. In this review, we summarize the clinical aspects of fibrinolysis in TBI, including diagnosis, treatment, and clinical correlates, with identification of targeted areas for future research efforts.

Fibrinolytic Serine Proteases, Therapeutic Serpins and Inflammation: Fire Dancers and Firestorms.

The making and breaking of clots orchestrated by the thrombotic and thrombolytic serine protease cascades are critical determinants of morbidity and mortality during infection and with vascular or tissue injury. Both the clot forming (thrombotic) and the clot dissolving (thrombolytic or fibrinolytic) cascades are composed of a highly sensitive and complex relationship of sequentially activated serine proteases and their regulatory inhibitors in the circulating blood. The proteases and inhibitors interact continuously throughout all branches of the cardiovascular system in the human body, representing one of the most abundant groups of proteins in the blood. There is an intricate interaction of the coagulation cascades with endothelial cell surface receptors lining the vascular tree, circulating immune cells, platelets and connective tissue encasing the arterial layers. Beyond their role in control of bleeding and clotting, the thrombotic and thrombolytic cascades initiate immune cell responses, representing a front line, “off-the-shelf” system for inducing inflammatory responses. These hemostatic pathways are one of the first response systems after injury with the fibrinolytic cascade being one of the earliest to evolve in primordial immune responses. An equally important contributor and parallel ancient component of these thrombotic and thrombolytic serine protease cascades are the serine protease inhibitors, termed serpins. Serpins are metastable suicide inhibitors with ubiquitous roles in coagulation and fibrinolysis as well as multiple central regulatory pathways throughout the body. Serpins are now known to also modulate the immune response, either via control of thrombotic and thrombolytic cascades or via direct effects on cellular phenotypes, among many other functions. Here we review the co-evolution of the thrombolytic cascade and the immune response in disease and in treatment. We will focus on the relevance of these recent advances in the context of the ongoing COVID-19 pandemic. SARS-CoV-2 is a “respiratory” coronavirus that causes extensive cardiovascular pathogenesis, with microthrombi throughout the vascular tree, resulting in severe and potentially fatal coagulopathies.

Physiology of Midkine and Its Potential Pathophysiological Role in COVID-19.

SARS-CoV2 infection not only causes abnormal severe pneumonia but also induces other relevant pathophysiological effects on several tissues and organs. In this regard, the clinical complications observed in COVID-19 include acute coronary syndrome, pulmonary thromboembolism, myocarditis and, in the severe cases, the occurrence of disseminated intravascular coagulation. Literature on COVID-19 highlighted the central role of the Renin Angiotensin Aldosterone System in the determinism of SARS-CoV2 cellular internalization in the target tissues. Lung degeneration and respiratory distress appear to be dependent on the perturbance of physiological mechanisms, such as the uncontrolled release of pro-inflammatory cytokines, a dysregulation of the fibrinolytic coagulative cascade and the hyperactivation of immune effector cells. In this mini review, we address the physiology of Midkine, a growth factor able to bind heparin, and its pathophysiological potential role in COVID-19 determinism. Midkine increases in many inflammatory and autoimmune conditions and correlates with several dysfunctional immune-inflammatory responses that appear to show similarities with the pathophysiological elicited by SARS-CoV2. Midkine, together with its receptor, could facilitate the virus entry, fostering its accumulation and increasing its affinity with Ace2 receptor. We also focus on Netosis, a particular mechanism of pathogen clearance exerted by neutrophils, which under certain pathological condition becomes dysfunctional and can cause tissue damage. Moreover, we highlight the mechanism of autophagy that the new coronavirus could try to escape in order to replicate itself, as well as on pulmonary fibrosis induced by hypoxia and on the release of cytokines and mediators of inflammation, correlating the interplay between Midkine and SARS-CoV2.

Mesoglycan exerts its fibrinolytic effect through the activation of annexin A2.

Mesoglycan is a drug based on a mixture of glycosaminoglycans mainly used for the treatment of blood vessel diseases acting as antithrombotic and profibrinolytic drugs. Besides the numerous clinical studies, there isno information about its function on the fibrinolytic cascade. Here, we have elucidated the mechanism of action by which mesoglycan induces the activation of plasmin from endothelial cells. Surprisingly, by a proteomic analysis, we found that, following mesoglycan treatment, these cells show a notable amount of annexin A2 (ANXA2) at the plasma membrane. This protein has been widely associated with fibrinolysis and appears able to move to the membrane when phosphorylated. In our model, this translocation has proven to enhance cell migration, invasion, and angiogenesis. Furthermore, the interaction of mesoglycan with syndecan 4 (SDC4), a coreceptor belonging to the class of heparan sulfate proteoglycans, represents the upstream event of the ANXA2 behavior. Indeed, the activation of SDC4 triggers the motility of endothelial cells culminating in angiogenesis. Interestingly, mesoglycan can induce the release of plasmin in endothelial cell supernatants only in the presence of ANXA2. This evaluation suggests that mesoglycan triggers the formation of a chain mechanism starting from the activation of SDC4, and the related cascade of events, including src complex and PKCα activation, promoting the phosphorylation of ANXA2 and its translocation to plasma membrane. This indicates a connection among mesoglycan, SDC4-(PKCα-src), and ANXA2 which, in turn, links the tissue plasminogen activator bringing it closer to plasminogen. This latter is so cleaved to release the plasmin and degrade fibrin sleeves.

Yersinia pestis Plasminogen Activator.

The Gram-negative bacterium Yersinia pestis causes plague, a fatal flea-borne anthropozoonosis, which can progress to aerosol-transmitted pneumonia. Y. pestis overcomes the innate immunity of its host thanks to many pathogenicity factors, including plasminogen activator, Pla. This factor is a broad-spectrum outer membrane protease also acting as adhesin and invasin. Y. pestis uses Pla adhesion and proteolytic capacity to manipulate the fibrinolytic cascade and immune system to produce bacteremia necessary for pathogen transmission via fleabite or aerosols. Because of microevolution, Y. pestis invasiveness has increased significantly after a single amino-acid substitution (I259T) in Pla of one of the oldest Y. pestis phylogenetic groups. This mutation caused a better ability to activate plasminogen. In paradox with its fibrinolytic activity, Pla cleaves and inactivates the tissue factor pathway inhibitor (TFPI), a key inhibitor of the coagulation cascade. This function in the plague remains enigmatic. Pla (or pla) had been used as a specific marker of Y. pestis, but its solitary detection is no longer valid as this gene is present in other species of Enterobacteriaceae. Though recovering hosts generate anti-Pla antibodies, Pla is not a good subunit vaccine. However, its deletion increases the safety of attenuated Y. pestis strains, providing a means to generate a safe live plague vaccine.

Is It the Missing Piece for Coronavirus Disease 2019, Acute Respiratory Distress Syndrome, and Venovenous Extracorporeal Membrane Oxygenation?

Is It the Missing Piece for Coronavirus Disease 2019, Acute Respiratory Distress Syndrome, and Venovenous Extracorporeal Membrane Oxygenation?

Hyperthrombotic Milieu in COVID-19 Patients.

COVID-19 infection has protean systemic manifestations. Experience from previous coronavirus outbreaks, including the current SARS-CoV-2, has shown an augmented risk of thrombosis of both macrovasculature and microvasculature. The former involves both arterial and venous beds manifesting as stroke, acute coronary syndrome and venous thromboembolic events. The microvascular thrombosis is an underappreciated complication of SARS-CoV-2 infection with profound implications on the development of multisystem organ failure. The telltale signs of perpetual on-going coagulation and fibrinolytic cascades underscore the presence of diffuse endothelial damage in the patients with COVID-19. These parameters serve as strong predictors of mortality. While summarizing the alterations of various components of thrombosis in patients with COVID-19, this review points to the emerging evidence that implicates the prominent role of the extrinsic coagulation cascade in COVID-19-related coagulopathy. These mechanisms are triggered by widespread endothelial cell damage (endotheliopathy), the dominant driver of macro- and micro-vascular thrombosis in these patients. We also summarize other mediators of thrombosis, clinically relevant nuances such as the occurrence of thromboembolic events despite thromboprophylaxis (breakthrough thrombosis), current understanding of systemic anticoagulation therapy and its risk–benefit ratio. We conclude by emphasizing a need to probe COVID-19-specific mechanisms of thrombosis to develop better risk markers and safer therapeutic targets.