Plasma cyclophilin a is a novel biomarker for coronary artery disease

Background: Oxidative stress induces secretion of cyclophilin A (CyPA) from vascular smooth muscle cells and it plays a crucial role in the pathogenesis of atherosclerosis in mice. Therefore, we tested our hypothesis that plasma CyPA levels are increased in patients with coronary artery diseases (CAD). Methods and Results: In 320 consecutive patients undergoing coronary angiography, we examined the relationship between plasma CyPA levels and the severity of CAD. We measured plasma CyPA by an immunoassay based on the sandwich technique. Plasma CyPA levels were significantly higher in patients with significant coronary stenosis compared to those without it (P<0.001). A positive correlation was noted between plasma CyPA levels and significant coronary stenosis. The average number of stenotic coronary arteries and the need for coronary intervention were significantly increased in the quartiles of higher CyPA levels (both P<0.001). Indeed, the plasma CyPA level significantly correlated with the presence of CAD (adjusted odds ratio for CAD, 6.20; 95% confidence interval, 3.14-12.27; P<0.001). Interestingly, plasma levels of CyPA increased according to the number of atherosclerotic risk factors, all of which induce oxidative stress. Furthermore, plasma levels of CyPA significantly reduced after medical treatment of risk factors. Finally, CyPA was strongly expressed in coronary atherosclerotic plaque in patients with myocardial infarction. Conclusions: Plasma CyPA level is a novel biomarker for oxidative stress and CAD in humans.