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Key Event Title
|Level of Biological Organization|
Key Event Components
|abnormal blood coagulation||blood||occurrence|
Key Event Overview
AOPs Including This Key Event
|Homo sapiens||Homo sapiens||Moderate||NCBI|
|All life stages||Moderate|
Key Event Description
Coagulation is a process that responds to injury by the rapid formation of a clot. Activation of coagulation factor proteins are involved in coagulation. In the extrinsic pathway, platelets, upon the contact with collagen in the injured blood vessel wall, release thromboxane A2 (TXA2) and adenosine 2 phosphates (ADP), leading to the clot formation. Extravascular tissue factor (TF) binds to plasma factor VIIa (FVIIa) and promotes the activation of FXa. Activated FXa assembles with cofactors FVa and FVIIIa on the surface of aggregated platelets, which lead to generation of thrombin (FIIa). Thrombin catalyzes the production of fibrin (FG) which creates a clot. The binding of prekallikrein and high-molecular weight kininogen activate FXIIa in the intrinsic pathway. Many regulators are involved in coagulation system. Plasmin is one of the modulators required for dissolution of the fibrin clot. Plasmin is activated by tissue plasminogen activator (tPA) and urokinase plasminogen activation (uPA). SERPINs inhibit thrombin, plasmin and tPA. For example, SERPINE1 or plasminogen activator inhibitor-1 (PAI-1) inhibits tPA/uPA and results in hypofibrinolysis [Bernard I,et al. Viruses. 2021; 13(1):29.]. In addition, SERPING1 inhibits FXII, and thus down-regulation of SERPING1 lifts suppression of FXII of the intrinsic coagulation cascade [Garvin et al. eLife 2020;9:e59177]. Protein C, protein S and thrombomodulin degrade FVa and FVIIIa. [Ref. IPA, Coagulation System, version60467501, release date: 2020-11-19]
How It Is Measured or Detected
Coagulation and inflammatory parameters are measured in COVID-19 patients [Di Nisio et al. 2021]. Coagulation parameters include platelet count, prothrombin time, activated partial thromboplastin time, D-dimer, fibrinogen, antithrombin III [Di Nisio et al. 2021]. These parameters are measured in the blood.
In vitro systems
Whole human blood model for testing the activation of coagulation and complement system, as well as clot formation [Ekstrand-Hammarström, B. et al. Biomaterials 2015, 51, 58-68, Ekdahl, K.N., et al. Nanomedicine: Nanotechnology, Biology and Medicine 2018, 14, 735-744, Ekdahl, K.N., et al. Science and Technology of Advanced Materials, 20:1, 688-698,]
Domain of Applicability
The KE is applicable to broad species/life stage/sex.
- Bernard I, Limonta D, Mahal LK, Hobman TC. Endothelium Infection and Dysregulation by SARS-CoV-2: Evidence and Caveats in COVID-19. Viruses. 2021; 13(1):29. DOI: https://doi.org/10.3390/v13010029
- Garvin et al. A mechanistic model and therapeutic interventions for COVID-19 involving a RAS-mediated bradykinin storm. eLife 2020;9:e59177. DOI: https://doi.org/10.7554/eLife.59177
- Di Nisio, Marcello et al. Interleukin-6 receptor blockade with subcutaneous tocilizumab improves coagulation activity in patients with COVID-19 European Journal of Internal Medicine, Volume 83, 34 - 38 DOI: https://doi.org/10.1016/j.ejim.2020.10.020
- Ekstrand-Hammarström, B.; Hong, J.; Davoodpour, P.; Sandholm, K.; Ekdahl, K.N.; Bucht, A., Nilsson, B. TiO2 nanoparticles tested in a novel screening whole human blood model of toxicity trigger adverse activation of the kallikrein system at low concentrations. Biomaterials 2015, 51, 58-68 DOI:https://doi.org/10.1016/j.biomaterials.2015.01.031
- Ekdahl, K.N.; Davoodpour, P.; Ekstrand-Hammarström, B.; Fromell, K.; Hamad, O.A.; Hong, J.; Bucht, A.; Mohlin, C.; Seisenbaeva, G.A.; Kessler, V.G., Nilsson, B. Contact (kallikrein/kinin) system activation in whole human blood induced by low concentrations of α-Fe2O3 nanoparticles. Nanomedicine: Nanotechnology, Biology and Medicine 2018, 14, 735-744 [DOI: https://doi.org/10.1016/j.nano.2017.12.008]
- Kristina N Ekdahl, Karin Fromell, Camilla Mohlin, Yuji Teramura & Bo Nilsson (2019) A human whole-blood model to study the activation of innate immunity system triggered by nanoparticles as a demonstrator for toxicity, Science and Technology of Advanced Materials, 20:1, 688-698, DOI: 10.1080/14686996.2019.1625721