Elevated Tissue Expression of Thrombomodulatory Factors Correlates with Acute Symptomatic Carotid Plaque Phenotype

ObjectivesThrombomodulatory factors have been implicated in plaque instability. The aim was to examine the relationship between thrombomodulatory gene expression, timing of clinical events and plaque histology.Design of StudyPlaques were obtained from 40 consecutive patients undergoing carotid endarterectomy and divided into three groups (group 1, early symptomatic, within 1 month; group 2, late symptomatic, 1–6 months and group 3, asymptomatic). Total RNA was isolated to determine the expression of tissue plasminogen activator (t-PA), urokinase plasminogen activator (u-PA), plasminogen activator inhibtor-1 (PAI-1), tissue factor (TF), tissue factor pathway inhibitor (TFPI), thrombomodulin (TM), CD68 and vascular endothelial-cadherin (VE-Cadherin).ResultsExpression of t-PA, PAI-1, TF, TFPI, TM, CD68 and VE-cadherin were significantly increased in the early symptomatic group (p = 0.019, 0.028, 0.018, 0.025, 0.038, 0.016 and 0.027 respectively), but the level of gene expression in the late symptomatic group was indistinguishable from the asymptomatic group. The incidence of plaque rupture and intraplaque haemorrhage was significantly increased in the early symptomatic groups (58% versus 18%/18% group 2/3, and 55% versus 6%/9% respectively, p < 0.05 for both).ConclusionsExpression of thrombomodulatory genes is increased in unstable plaques, though levels after 1 month are comparable to asymptomatic plaques. This transient rise may influence plaque instability, and rapid resolution mirrors the clinical reduction in risk of further thrombo-embolic events.