Expression of COX-1 and COX-2 mRNAs in atherosclerotic plaques

Inflammation is a characteristic of atherosclerotic plaques. Prostaglandins are inflammatory mediators whose production is controlled by cyclooxygenase (COX). There are two isoforms: COX-1 and COX-2. COX-1 is relatively stable while COX-2 is induced in inflammatory states. In order to evaluate their possible contribution to atherosclerotic plaque inflammation, we measured their relative levels in postmortem plaque and adjacent normal arterial tissue. Eleven pairs of atherosclerotic plaque and adjacent normal arterial tissue were obtained from postmortem specimens. Total RNA was extracted and relative levels of COX-1 and COX-2 determined by the technique of RT-PCR. COX-2 levels were 4.8-fold higher in plaque tissue than in normal artery. COX-1 levels were only 1.1-fold higher. There was no relationship between sex, age, postmortem delay or cause of death and COX-2 or COX-1 levels. COX-2 levels are sharply upregulated in atherosclerotic plaques, indicating that it may be a significant contributor to plaque inflammation. Accordingly, COX-2 inhibitors may reduce the degree of inflammation and protect against future cardiovascular events.