Is the mechanism of COVID-19 coagulopathy still a rabbit’s hole?

The pathophysiology of COVID-19 is an enigma with its severity often determined by the extent of coagulopathy. Several regulatory pathways targeted by the SARS-CoV-2 include the renin-angiotensin system, von Willebrand Factor, and most importantly, the complement pathway. This article discusses these pathways to help design potential future therapies.     

Systemic host inflammatory and coagulation response in the Dengue virus primo-infection

BACKGROUND: Dengue virus infection has been rising in tropical countries. Clinical manifestations range from fever and general malaise to hemorrhagic manifestations and death. The role of endothelial damage and cytokines has not been well established for dengue infection. OBJECTIVE: Determine the profile of the pro-inflammatory cytokines and several markers of coagulopathy of dengue infection. METHODS: Patients admitted between September 2000 and April 2001, who met the WHO dengue diagnosis criteria, were enrolled. Blood samples were collected at 0, 6, 12, 24, 48, 72 h and 5 and 7 days after hospitalization. Profile of pro-inflammatory cytokines, markers of coagulopathy, protein C, protein S, d-dimer, prothrombin time, activated partial thromboplastin time, fibrinogen and activated protein C levels were determined. RESULTS: Thirty-three patients were enrolled. Median (range) age was 31 (13-70) years; 51.5% (17/33) were female. Ten of 33 (30%) presented with hemorrhagic manifestations. Patients were classified: Grade 1: 23/33 (70%), Grade II: 10/33 (30%). At study entry IL-6 was the most elevated, followed by IL-8 and TNF alpha. IL-10 was not elevated. No significant differences (P < 0.05) were demonstrated in the levels of any of the haemostatic or cytokine markers by disease severity (Grade I versus Grade II patients). CONCLUSION: The systemic host inflammatory and coagulation activation response occurs early in patients with dengue viral infection in the absence of severe hemorrhagic manifestations, and provides the basis for considering future clinical study in the use of recombinant human activated protein C to treat patients with severe sepsis from dengue infection.     

Heparanase as a potential player in SARS-CoV-2 infection and induced coagulopathy

During the current formidable COVID-19 pandemic, it is appealing to address ideas that may invoke therapeutic interventions. Clotting disorders are well recognized in patients infected with severe acute respiratory syndrome (SARS) caused by a novel coronavirus (SARS-CoV-2), which lead to severe complications that worsen the prognosis in these subjects.Increasing evidence implicate Heparan sulfate proteoglycans (HSPGs) and Heparanase in various diseases and pathologies, including hypercoagulability states. Moreover, HSPGs and Heparanase are involved in several viral infections, in which they enhance cell entry and release of the viruses.Herein we discuss the molecular involvement of HSPGs and heparanase in SARS-CoV-2 infection, namely cell entry and release, and the accompanied coagulopathy complications, which assumedly could be blocked by heparanase inhibitors such as Heparin and Pixatimod.     

A catalog for transcripts in the venom gland of the Agkistrodon acutus: identification of the toxins potentially involved in coagulopathy

Agkistrodon acutus is a special agkistrodon halys, only distributed in Southern China, with a few exceptions in Vietnam. It is a cherished element used in traditional Chinese medicine. In order to produce a global panorama of gene expression in the Agkistrodon acutus venom gland, a non-normalized cDNA library was constructed, and 8696 high quality 5' end expressed sequenced tags (ESTs) were sequenced and analyzed. The initial sequences were assembled into 2855 clusters. Of these clusters, only 45.60% clusters matched known sequence and 54.40% had no match to any known sequence in GenBank. Except for putative cellular proteins (1184 clusters), the remaining 118 clusters (40.16% of all ESTs) corresponded to sequences associated with diverse toxin function. According to expression abundance, the major toxin components were metalloproteinases (32.08%) and C-type lectin (5.22%), and other components including bradykinin-potentiating peptide (0.90%), serine proteases (0.51%), nucleotidase and nuclease (0.41%), phospholipase A2 (0.30%), disintegrin (0.05%), cytokine-like molecules (0.06%), and other proteins (0.63%). The majority of these components are thought to be responsible for coagulopathy after A. acutus bites. We have therefore generated a comprehensive catalog of the A. acutus venom gland described so far. Gene expression from the very specialized secretory tissue, especially for those involved in coagulopathy, can be surveyed and provide important information in finding novel toxins.     

糖尿病肾病致凝血异常的研究

糖尿病(DM)已成为世界性的常见病,其发病率高,并且随着生活水平的改善,其发病率必然还会进一步加剧。血管病变是DM的重要并发症之一,糖尿病肾病(DN)是糖尿病常见且严重的微血管并发症,与血栓形成密切相关。糖尿病肾病的进展伴随着体内凝血活性和抗凝活性的失调,同时激活自身免疫系统,发生炎症反应。炎症应答过程中释放的炎症因子损伤肾小球内皮细胞,导致抗凝活性减弱。DN患者体内血细胞激活,微粒形成增多会加强凝血活性。此外,纤溶酶抑制剂(PAI-1)与纤溶酶激活剂(t PA)的失衡会引起纤溶系统紊乱。这三个方面引起DN患者体内的高凝状态加重,并因此加速肾功能恶化,导致肾小球率过滤降低,系膜基质增多,最终引起肾小球硬化及终末期肾脏疾病。本文就糖尿病肾病致凝血异常的发生机制做一综述。     

Therapeutic plasma exchange in treating multi-organ injury at the later stage of mushroom poisoning: Three case reports

Ingestion of Amanita phalloides, a deadly wild mushroom, can cause multi-organic injury. The value of therapeutic plasma exchange (TPE) in treating mushroom poisoning was controversial, especially for those patients at the later stage. We reported three cases of acute liver injury, coagulopathy, and hepatic encephalopathy secondary to mushroom poisoning at the later stage. Therapeutic plasma exchange (TPE) session was repeated 2~5 times depending on the patients’ conditions. Pathological plasma ranging from 1600 to 1800 mL was exchanged for each session with fresh frozen plasma and normal saline based on the patients’ body weight. Patients’ liver function, coagulation function, and clinical symptoms were immediately improved upon TPE treatment. TPE is a reliable therapy for patients with acute liver injury, coagulopathy, and hepatic encephalopathy secondary to mushroom poisoning at the later stage of poisoning.     

Diagnosis and treatment of coagulopathy following percutaneous cryoablation of liver tumors: Experience in 372 patients

Coagulopathy after liver cryoablation was first reported many years ago; the cause is local platelet trapping and destruction within the margin of the cryolesion. However, the prognosis and therapeutic effects of coagulopathy remain unclear. This study retrospectively reviewed clinical data from 372 patients (525 sessions) who underwent liver cryoablation in our hospital during the past 4.5 years. Small tumors (major diameter < 6 cm) were treated with a single complete ablation; massive tumors (major diameter 6–10 cm or >10 cm) were divided into two or three parts that were dealt with in turn. Platelet counts decreased to an average of (46.12 ± 68.13) × 10⁹/L after each session of cryoablation. The decline was most evident in patients with high pretreatment platelet counts, while those with low pretreatment counts had the highest risk of coagulopathy. Change in platelet count was not correlated with the diameter of the tumor. Slight coagulopathy (platelet count (70–100) × 10⁹/L) can resolve without treatment within 1 week and administration of recombinant human interleukin-11 can assist recovery from severe coagulopathy (platelet count < 70 × 10⁹/L).     

脓毒症致凝血异常发生机制的研究进展

脓毒症是由感染引起的全身炎症反应综合征,其病情凶险,死亡率高。凝血异常是脓毒症的主要特点之一,是多方面因素共同作用的结果。在脓毒症的发生发展过程中,炎症因子既可以激活凝血级联反应又可以抑制抗凝系统和纤维蛋白溶解系统,最终导致其凝血活性增强,炎症诱导的凝血紊乱进一步促进和加重炎症反应。而脓毒症患者的高凝状态可导致静脉血栓栓塞甚至DIC的发生,引起了研究者们的广泛关注。本文将就脓毒症致凝血异常发生机制的研究进展做一综述。     

BJ-PI2, A non-hemorrhagic metalloproteinase from Bothrops jararaca snake venom

Background

Envenoming by Bothrops jararaca can result in local pain, edema, hemorrhage and necrosis, partially mediated by snake venom metalloproteinases (SVMPs). Here, we describe the characterization of BJ-PI2, a P-I class SVMP from B. jararaca venom, and its local tissue actions.

Methods

BJ-PI2 was purified by a combination of gel filtration, anion-exchange chromatography and reverse phase HPLC, and identified by mass spectrometry. Clotting and fibrin(ogen)olytic activities were assayed using conventional methods. Hemorrhagic activity and changes in vascular permeability were examined in rat dorsal skin. Myonecrosis and inflammatory activity were examined in mouse gastrocnemius muscle.

Results

BJ-PI2 was a 23.08 kDa single-chain polypeptide. Tryptic fragments showed highest homology with SVMP insularinase A from Bothrops insularis, but also with B. jararaca SVMP bothrojaractivase; less similarity was observed with B. jararaca SVMPs BJ-PI and jararafibrases II and IV. BJ-PI2 did not clot fibrinogen or rat citrated plasma but had α- and β-fibrinogenolytic activity (inhibited by EDTA and 1,10-phenanthroline but not by PMSF) and attenuated coagulation after plasma recalcification. BJ-PI2 had fibrinolytic activity. BJ-PI2 increased the vascular permeability of rat dorsal skin (inhibited by 1,10-phenanthroline). BJ-PI2 was not hemorrhagic or myonecrotic but caused migration of inflammatory cells. In contrast, venom was strongly hemorrhagic and myonecrotic but caused less infiltration of inflammatory cells.

Conclusions

BJ-PI2 is a non-hemorrhagic, non-myonecrotic, non-coagulant P-I class SVMP that may enhance vascular permeability and inflammatory cell migration in vivo.

General significance

BJ-PI2 contributes to enhanced vascular permeability and inflammatory cell migration after envenoming, but not to venom-induced hemorrhage and necrosis.     

Role of SARS-CoV-2 -induced cytokines and growth factors in coagulopathy and thromboembolism

Severe COVID-19 patients frequently present thrombotic complications which commonly lead to multiorgan failure and increase the risk of death. Severe SARS-CoV-2 infection induces the cytokine storm and is often associated with coagulation dysfunction. D-dimer, a hallmark of venous thromboembolism (VTE), is observed at a higher level in the majority of hospitalized COVID-19 patients. The precise molecular mechanism of the disproportionate effect of SARS-CoV-2 infection on the coagulation system is largely undefined. SARS-CoV-2 –induced endotheliopathy and, induction of cytokines and growth factors (GFs) most likely play important roles in platelet activation, coagulopathy, and VTE. Generally, viral infections lead to systemic inflammation and induction of numerous cytokines and GFs and many of them are reported to be associated with increased VTE. Most importantly, platelets play key thromboinflammatory roles linking coagulation to immune mediators in a variety of infections including response to viral infection. Since the pathomechanism of coagulopathy and VTE in COVID-19 is largely undefined, herein we highlight the association of dysregulated inflammatory cytokines and GFs with thrombotic complications and coagulopathy in COVID-19.