Summary
Vascular injury in acute coronary syndromes (ACS) involves a complex cross-talk between
inflammatory mediators, platelets and thrombosis, where the interaction between platelets
and coagulation factors (e. g. thrombin) is a central link between thrombosis and
inflammation. In ACS, aspirin at antiplatelet doses exhibits anti-inflammatory effects
as seen from the decrease in inflammation markers such as CRP, M-CSF, MCP-1 and others.
These actions probably occur subsequent to inhibition of platelet COX-1-dependent
thromboxane formation and its action as a multipotent autocrine and paracrine agent.
This likely involves inhibition of thrombin formation as well as inhibition of secondary
pro-inflammatory mediators, such as sphingosine-1-phosphate. Experimental and limited
clinical data additionally suggest antiinflammatory effects of aspirin independent
of its antiplatelet action. For example, aspirin at antiplatelet doses might acetylate
COX-2 in vascular cells, directing the activity of the enzyme into a 15-lipoxygenase
which by transcellular metabolism results in the formation of 15-epi-lipoxin (‘aspirin-triggered
lipoxin’), an antiinflammatory mediator. Furthermore, aspirin stimulates eNOS via
lysine-acetylation, eventually resulting in induction of heme oxygenase (HO-1), which
improves the antioxidative potential of vascular cells. All of these effects have
been seen at antiplatelet doses of 100–300 mg/day, equivalent to peak plasma levels
of 10–30 μM. Many more potentially antiinflammatory mechanisms of aspirin have been
described, mostly salicy-late-related, at low to medium millimolar concentrations
and, therefore, are of minor clinical interest. Altogether, there is a wealth of data
supporting antiiflammatory effects of aspirin in ACS, but studies generating direct
evidence for antiinflammatory effects in ACS remain to be done.
Keywords
Aspirin - platelet pharmacology - thromboxane - inflammatory mediators - thrombin