Managing thrombus formation with EL2-5HTVac: A selective vaccination-based approach targeting the platelet serotonin...

Cardiovascular disease is the leading global cause of death, largely attributable to thrombotic events that can result in conditions like myocardial infarction and stroke. The serotonin 2A receptor (5-HT_2AR) has been identified as a key mediator in platelet aggregation and thrombogenesis, making it a promising target for antithrombotic therapies. Current 5-HT_2AR antagonists, however, have been limited by nonselectivity and adverse effects. This study introduces a novel vaccine designed to target the ligand-binding domain of 5-HT_2AR, which resides in the second extracellular loop (EL2). This vaccine, referred to as "EL2-5HTVac," is expected to provide a long-lasting and selective therapeutic approach without the complications of increased bleeding risk. In this study, we demonstrate that EL2-5HTVac induces a robust immune response with a significant elevation in EL2-specific antibodies in comparison with the controls. Furthermore, vaccinated mice exhibited prolonged occlusion times in a FeCl₃-induced carotid artery thrombosis model without extending tail bleeding times, indicating a favorable safety profile. The EL2-5HTVac also effectively inhibited the serotonin-induced platelet shape change. Additionally, it also blocked serotonin-enhanced ADP-induced platelet aggregation, suggesting an ability to prevent serotonin-facilitated amplification of platelet activation. These findings suggest that EL2-5HTVac offers a dual advantage of thromboprotection and maintenance of hemostasis, potentially overcoming limitations of existing antithrombotic strategies. Future studies should focus on the long-term efficacy and safety of EL2-5HTVac, as well as the feasibility of a vaccination-based approach in larger animal models for eventual clinical application. SIGNIFICANCE STATEMENT: This study documents the utility of a vaccine as a potential antithrombotic agent. The vaccine can prevent thrombus formation without affecting hemostasis (causing bleeding).