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Targeting the anionic region of human protease-activated receptor 4 inhibits platelet aggregation and thrombosis
M M Mumaw1, M de la Fuente, D N Noble
1Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA.
Insights
A new antibody, CAN12, effectively targets the protease-activated receptor 4 (PAR4) anionic cluster, inhibiting platelet aggregation and arterial thrombosis without affecting hemostasis. This offers a promising new antiplatelet therapy.
Area of Science:
- Biochemistry
- Pharmacology
- Hematology
Background:
- Platelet activation and aggregation are complex processes targeted by antiplatelet therapies.
- Current acute coronary syndrome treatments carry bleeding risks.
Purpose of the Study:
- To assess the protease-activated receptor 4 (PAR4) anionic cluster as an antiplatelet target using a polyclonal antibody (CAN12).
Main Methods:
- Western blotting, ex vivo aggregation, and secretion assays were used to evaluate CAN12's interaction with PAR4 and its effect on platelet activation.
- In vivo studies utilized the Rose Bengal arterial thrombosis model and two hemostasis models.
Main Results:
- CAN12 demonstrated interaction with human PAR4, delaying its cleavage and inhibiting thrombin-induced platelet aggregation and secretion dose-dependently.
- In vivo, CAN12 successfully inhibited arterial thrombosis while not impacting hemostasis in two independent models.
Conclusions:
- Targeting the extracellular anionic cluster on PAR4 represents a novel and viable antiplatelet therapeutic strategy.
- CAN12 shows potential as a safe and effective antiplatelet agent with a reduced bleeding risk profile.
Background:
Human platelet activation and aggregation is a complex process. To date, many therapies have been developed targeting proteins that mediate this process to prevent unwanted activation. However, the current standard of care for acute coronary syndromes still has limitations, including bleeding risk.
Objective:
To evaluate the protease-activated receptor 4 (PAR4) anionic cluster as a viable antiplatelet target by using a polyclonal antibody (CAN12).
Methods:
We used western blotting, aggregation and secretion ex vivo to evaluate the ability of CAN12 to interact with PAR4 and inhibit platelet activation. The effects of CAN12 in vivo were evaluated with the Rose Bengal arterial thrombosis model and two models of hemostasis.
Results:
CAN12 was able to interact with human PAR4 and delay PAR4 cleavage. In addition, CAN12 inhibited thrombin-induced human platelet aggregation and secretion in a dose-dependent manner. The specificity of CAN12 was agonist-dependent. In vivo, we determined that CAN12 was able to inhibit arterial thrombosis, and, using two independent methods, we found that CAN12 did not influence hemostasis.
Conclusion:
Targeting the extracellular anionic cluster on PAR4 is a viable novel strategy as an antiplatelet therapy.
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