Differences in the detection of cyclo-oxygenase 1 and 2 proteins in symptomatic and asymptomatic carotid plaques

Background: The expression of cyclo-oxygenase (COX) 1 and 2 has been demons trated in atherosclerotic arteries. In the present study this was correlate d with symptoms arising from a carotid plaque. Methods: Carotid plaques from 12 asymptomatic patients were compared with 1 1 plaques from patients who had had neurological symptoms within the preced ing 30 days. Sections were stained with haematoxylin and eosin, elastin van Gieson and goat antihuman antibodies to COX-1 and COX-2. Plaque morphology was correlated with neurological symptoms. The area with positive COX-1 an d COX-2 staining was measured by computerized planimetry in entire cross-se ctions and in specific areas of the plaque. Results: There was a significant association between cap thinning and plaqu e rupture with symptoms (P = 0.003). The percentage area of positive staini ng in entire cross-sections for both COX-1 and COX-2 was significantly grea ter in symptomatic plaques (P = 0.001 and 0.0004 respectively). Staining in symptomatic plaques was significantly greater in the cap (COX-1: P = 0.001 ; COX-2: P = 0.0001) and shoulder (COX-1: P = 0.008; COX-2: P = 0.007) regi ons of the plaque. COX-1 expression in the sclerotic area was not increased (P = 0.15) although COX-2 staining was significantly greater (P = 0.04). Conclusion: Both COX-1 and COX-2 detection was increased in symptomatic pla ques. COX may contribute to plaque rupture and the onset of symptoms.