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 demonstrated in atherosclerotic arteries. In the present study this was correlated with symptoms arising from a carotid plaque. Methods: Carotid plaques from 12 asymptomatic patients were compared with 11 plaques from patients who had had neurological symptoms within the preceding 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 and COX‐2 staining was measured by computerized planimetry in entire cross‐sections and in specific areas of the plaque. Results: There was a significant association between cap thinning and plaque rupture with symptoms (P = 0·003). The percentage area of positive staining in entire cross‐sections for both COX‐1 and COX‐2 was significantly greater 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) regions 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 plaques. COX may contribute to plaque rupture and the onset of symptoms. © 2001 British Journal of Surgery Society Ltd