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.