CO077 | PLATELET MIR-144-5P REGULATES COX-1/2 EXPRESSION AND MODULATES ASPIRIN RESPONSE IN PATIENTS WITH CARDIOMETABOLIC RISK

P. Simeone¹, R. Liani¹, V. Abbonante², M. Alfonsetti¹, M. Frezza¹, P. Lanuti¹, A. Recchiuti³, A. Balduini², F. Santilli¹ | ¹Department of Medicine and Aging, and Center for Advanced Studies and Technology (CAST), "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; ²Department of Molecular Medicine, University of Pavia, Pavia, Italy; ³Department of Medical, Oral, and Biotechnological Science, Center for Advanced Studies and Technology (CAST), "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy

Background and Aims. Interindividual variability in response to low-dose aspirin (ASA) contributes to residual platelet activation and thrombotic risk. Platelet microRNAs (miRNAs) may modulate ASA pharmacodynamics, but mechanistic insights remain limited. To investigate whether platelet miR-144-5p regulates cyclooxygenase (COX)-1/2 expression and modulates ASA response in cardiometabolic patients.
Methods. Two hundred ASA-treated patients were stratified into tertiles of serum thromboxane B₂ (sTXB₂) slope, an ex vivo marker of COX-1 recovery. Platelet and extracellular vesicle miR-144-5p levels were quantified by RT-qPCR and correlated with biochemical and clinical variables. Functional studies were performed in megakaryocytic (DAMI) and endothelial (HUVEC) cells transfected with miR-144-5p mimics or inhibitors to assess COX-1/2 regulation.
Results. Patients with poor ASA response (3rd tertile of sTXB₂ slope) exhibited reduced platelet miR-144-5p (p=0.027) and higher COX-1 mRNA/protein levels (p≤0.027), whereas miR-144-5p was enriched in platelet-derived extracellular vesicles. Platelet miR-144-5p was inversely correlated with sTXB₂ (ρ=-0.235, p=0.007) and COX-1/2 mRNA expression. In DAMI (human megakaryocyte) cells, ASA exposure upregulated miR-144-5p cells; in addition, miR-144-5p overexpression suppressed, and inhibition enhanced, COX-1 protein levels. Similar effects were observed in HUVECs, where miR-144-5p downregulated both COX-1 and COX-2. Among our patients, platelet miR-144-5p was lower in those with obesity, dyslipidemia, and metabolic dysfunction-associated steatotic liver disease, conditions known to affect aspirin response.
Conclusions. Platelet miR-144-5p directly regulates COX-1/2 expression and contributes to interindividual variability in ASA response. Low platelet miR-144-5p identifies patients with accelerated COX-1 recovery and residual thromboxane generation, providing a mechanistic basis for precision antiplatelet therapy and potential miRNA-targeted interventions.