Contemporary low-dose aspirin does not consistently increase fibrinogen acetylation or modify clot phenotype despite effective platelet thromboxane suppression.
Does aspirin modulate fibrin clot properties through fibrinogen acetylation at clinically relevant doses?
The clinical relevance of aspirin-mediated fibrinogen acetylation remains uncertain, as contemporary low-dose aspirin does not consistently modify clot phenotype.
Fibrin clot architecture is increasingly recognized as a determinant of thrombotic phenotype and a potentially modifiable endpoint in vascular pharmacology. Aspirin is established as an antiplatelet agent through irreversible cyclooxygenase-1 acetylation and thromboxane A₂ suppression. Beyond this canonical pathway, aspirin has been proposed to modulate fibrin clot properties through nonenzymatic Nε-lysine acetylation of fibrinogen. Experimental studies in purified, recombinant, and selected ex vivo systems suggest effects on fibrin polymerization, factor XIIIa-dependent cross-linking, clot permeability, viscoelasticity, and fibrinolysis, with aspirin-sensitive lysines identified across fibrinogen chains. However, clinical relevance remains uncertain. At clinically relevant exposure, fibrinogen acetylation appears generally low, and contemporary low-dose aspirin does not consistently increase acetylation or modify clot phenotype despite effective platelet thromboxane suppression. Disease-related modifications, including glycation, carbamylation, oxidation, and nitration, may further reshape fibrin structure and influence aspirin responsiveness. This review examines the biochemical rationale, experimental evidence, disease-context dependency, and limitations of aspirin-mediated fibrinogen acetylation as a proposed extra-platelet mechanism. Its biological significance will require quantitative evidence of site occupancy, residue-specific function, physiological aspirin exposure, standardized clot assays, and integration with disease-specific modifiers of fibrin phenotype.
Nerini et al. (Wed,) reported a review. Aspirin was evaluated. Contemporary low-dose aspirin does not consistently increase fibrinogen acetylation or modify clot phenotype despite effective platelet thromboxane suppression.