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Home / Equine Research Bank / Front Vet Sci / Unfractionated and Low-Molecular-Weight Heparin and the Phos...
Frontiers in veterinary science2016; 3; 99; doi: 10.3389/fvets.2016.00099

Unfractionated and Low-Molecular-Weight Heparin and the Phosphodiesterase Inhibitors, IBMX and Cilostazol, Block Ex Vivo Equid Herpesvirus Type-1-Induced Platelet Activation.

Abstract: Equid herpes virus type-1 (EHV-1) is a major pathogen of horses, causing abortion storms and outbreaks of herpes virus myeloencephalopathy. These clinical syndromes are partly attributed to ischemic injury from thrombosis in placental and spinal vessels. The mechanism of thrombosis in affected horses is unknown. We have previously shown that EHV-1 activates platelets through virus-associated tissue factor-initiated thrombin generation. Activated platelets participate in thrombus formation by providing a surface to localize coagulation factor complexes that amplify and propagate thrombin generation. We hypothesized that coagulation inhibitors that suppress thrombin generation (heparins) or platelet inhibitors that impede post-receptor thrombin signaling [phosphodiesterase (PDE) antagonists] would inhibit EHV-1-induced platelet activation ex vivo. We exposed platelet-rich plasma (PRP) collected from healthy horses to the RacL11 abortigenic and Ab4 neuropathogenic strains of EHV-1 at 1 plaque-forming unit/cell in the presence or absence of unfractionated heparin (UFH), low-molecular-weight heparin (LMWH) or the PDE inhibitors, 3-isobutyl-1methylxanthine (IBMX), and cilostazol. We assessed platelet activation status in flow cytometric assays by measuring P-selectin expression. We found that all of the inhibitors blocked EHV-1- and thrombin-induced platelet activation in a dose-dependent manner. Platelet activation in PRP was maximally inhibited at concentrations of 0.05 U/mL UFH and 2.5 μg/mL LMWH. These concentrations represented 0.1-0.2 U/mL anti-factor Xa activity measured in chromogenic assays. Both IBMX and cilostazol showed maximal inhibition of platelet activation at the highest tested concentration of 50 μM, but inhibition was lower than that seen with UFH and LMWH. Our results indicate that heparin anticoagulants and strong non-selective (IBMX) or isoenzyme-3 selective (cilostazol) PDE antagonists inhibit ex vivo EHV-1-induced platelet activation. These drugs have potential as adjunctive therapy to reduce the serious complications associated with EHV-1-induced thrombosis. Treatment trials are warranted to determine whether these drugs yield clinical benefit when administered to horses infected with EHV-1.
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Publication Date: 2016-11-17 PubMed ID: 27909693PubMed Central: PMC5112437DOI: 10.3389/fvets.2016.00099Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research investigates how coagulation inhibitors (heparins) and platelet inhibitors (phosphodiesterase antagonists) can block platelet activation caused by Equid herpes virus type-1 (EHV-1). The findings suggest that these drugs, including unfractionated heparin, low-molecular-weight heparin, and phosphodiesterase inhibitors such as IBMX and cilostazol, could potentially be used to avoid serious complications related to EHV-1-induced thrombosis in horses.

Study Background and Aim

  • The study primarily addresses EHV-1, a harmful pathogen among horses that leads to disorders such as abortion storms and herpes virus myeloencephalopathy. Such conditions are partially due to ischemic damage resulting from thrombosis in the spinal and placental vessels.
  • The exact mechanism triggering the thrombosis in such cases was not known prior to this research. Previous studies revealed that EHV-1 stimulates platelets through virus-associated tissue factor-initiated thrombin generation, which leads to thrombus formation.
  • The present study hypothesized that thrombin generation could be suppressed using coagulation inhibitors (heparins), or post-receptor thrombin signaling could be impeded using platelet inhibitors, like phosphodiesterase (PDE) antagonists. Thus, the paper aims to analyze whether these inhibitors can prevent EHV-1-induced platelet activation.

Research Methodology

  • Platelet-rich plasma (PRP) was collected from healthy horses and exposed to RacL11 abortigenic and Ab4 neuropathogenic strains of EHV-1. This process was carried out at 1 plaque-forming unit per cell, with or without the presence of unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), and the PDE inhibitors, 3-isobutyl-1methylxanthine (IBMX) and cilostazol.
  • The activation status of the platelets was evaluated using flow cytometric assays by measuring P-selectin expression. These measures served to identify the extent of the action of these coagulation and platelet inhibitors.

Key Findings

  • Results showed that all inhibitors managed to block EHV-1 and thrombin-induced platelet activation in a dose-dependent manner. Optimal inhibition of platelet activation in PRP was observed at concentrations of 0.05 U/mL UFH and 2.5 μg/mL LMWH.
  • Both IBMX and cilostazol showed maximal suppression of platelet activation at the highest tested concentration of 50 μM. However, the degree of inhibition was lower than that observed with UFH and LMWH.
  • These results confirmed the hypothesis that heparin anticoagulants and potent non-selective (IBMX) or isoenzyme-3 selective (cilostazol) PDE antagonists can block EHV-1-induced platelet activation.

Implications and Next Steps

  • The study concludes that the drugs investigated demonstrate potential as adjunctive therapies to mitigate serious implications related to EHV-1-induced thrombosis in horses.
  • Given these findings, further treatment trials are necessary to establish whether administering these drugs to horses infected with EHV-1 would result in any clinical benefit.

Cite This Article

APA
Stokol T, Serpa PBS, Zahid MN, Brooks MB. (2016). Unfractionated and Low-Molecular-Weight Heparin and the Phosphodiesterase Inhibitors, IBMX and Cilostazol, Block Ex Vivo Equid Herpesvirus Type-1-Induced Platelet Activation. Front Vet Sci, 3, 99. https://doi.org/10.3389/fvets.2016.00099

Publication

Frontiers in veterinary science
ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 3
Pages: 99

Researcher Affiliations

Stokol, Tracy
  • Department of Population Medicine and Diagnostic Sciences, Cornell University , Ithaca, NY , USA.
Serpa, Priscila Beatriz da Silva
  • Department of Population Medicine and Diagnostic Sciences, Cornell University , Ithaca, NY , USA.
Zahid, Muhammad N
  • Department of Population Medicine and Diagnostic Sciences, Cornell University , Ithaca, NY , USA.
Brooks, Marjory B
  • Department of Population Medicine and Diagnostic Sciences, Cornell University , Ithaca, NY , USA.

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