Olfactory Receptor Activation Reduces Platelet Reactivity and Arterial Thrombosis Through Actin Cytoskeleton Remodeling

BACKGROUND: Despite antiplatelet therapy, some patients remain at high ischemic risk because of drug nonresponsiveness or high residual platelet reactivity). We aimed to target an orphan platelet GPCR (G protein-coupled receptor) from the OR (olfactory receptor) family as a novel antithrombotic strategy. METHODS: Using an engineered reporter cell line expressing human OR2L13, an orphan GPCR implicated in limiting platelet reactivity, we conducted a high-throughput screen of 8000 nonodorant bioactive compounds with counterscreen validation. Subsequent studies assessed platelet function in healthy subjects and patients with coronary artery and peripheral artery disease. Phospho-proteomics revealed key signaling pathways, whereas ex vivo and in vivo assays evaluated the impact of a lead compound on platelet signaling, biomechanics, and thrombosis in both arterial and venous vasculature. RESULTS: We identified 6 OR2L13-specific agonists that suppressed platelet aggregation and α-granule exocytosis through multiple receptors, suggesting a shared downstream mediator. The lead agonist (CCF0054500) phosphorylated platelet HSP27 (heat shock protein 27), disrupting the actin cytoskeleton and reducing clot retraction (clot area, 70.6 versus 5.2; P<0.0001), an effect reversed by HSP27 inhibition. In a murine arterial injury model, CCF0054500 decreased platelet accumulation by 88.9% (P<0.0003) without affecting fibrin generation or hemostasis. In a myocardial infarction model with high residual platelet reactivity, CCF0054500 lowered platelet reactivity (P<0.0001) and improved left ventricular function (P=0.0007). CONCLUSIONS: We describe and characterize the first nonolfactory probe for the purpose of inhibiting platelet activation and thrombosis through downstream HSP27 in a comprehensive investigation using a first-of-its-kind platelet inhibitor targeting an orphan platelet GPCR.