Platelet monocyte aggregates and monocyte chemoattractant protein-1 are not inhibited by aspirin in critical limb ischaemia.

Abstract

Platelet monocyte aggregates (PMA) and monocyte chemoattractant protein-1 (MCP-1) play a significant role in atherosclerotic disease but the effect of aspirin and their role in peripheral arterial disease (PAD) requires further investigation. We have compared p-selectin, PMA and MCP-1 in patients with PAD treated with aspirin (75 mgs daily), with age matched controls not treated with aspirin. Using flow cytometry and ELISA, P-selectin, PMA and MCP-1 were compared in 3 populations; healthy controls (n=12), intermittent claudication (n=19) and critical limb ischaemia (CLI), (n=10). P-selectin was significantly higher in CLI patients (3.48% positive) compared to the claudicants (1. 36% positive) and the controls (1.76% positive). PMA levels were significantly higher for CLI population (44.5% positive) compared to the claudicants (20.48% positive) and the controls (28.33% positive). MCP-1 levels expression was significantly higher for the CLI patients (175.4 pg/mL) compared to the claudicants (76.1 pg/mL) and the controls (117.0 pg/mL). Despite aspirin treatment CLI patients have higher platelet activation and MCP-1 expression than controls and claudicants. With increasing severity of disease aspirin is unable to suppress markers of platelet activation and pro-atherosclerotic chemokine expression which may represent another form of aspirin resistance.