Study on changes of heme oxygenase-1 expression in patients with coronary heart disease

Background: Heme oxygenase (HO) is a rate-limiting enzyme of endogenetic carbon monoxide (CO) that degrades heme into carbon monoxide, bilirubin, and iron. These products have important physiologic effects: bilirubin is a potent antioxidant that can act against ischemia/reperfusion injury; there is a negative correlation between the content of HO-1 and the incidence of coronary heart disease (CHD). Hypothesis: This study was undertaken to investigate the changes of HO-1 in patients with CHD. Methods: Thirty-five patients with acute myocardial infarction (AMI), 40 patients with unstable angina pectoris (UAP, diagnosed by coronary angiography), and 30 patients with stable angina pectoris (AP, diagnosed by coronary angiography) were selected for the study; another 30 patients with normal coronary artery (diagnosed by coronary angiography) were selected as controls. The levels of HO-1 protein expression in monocyte and lymphocyte in the subjects were tested by immunohistochemistry and western blot. Computer picture analyzing systems were also used to measure the levels of HO-1 protein expression. Results: Heme oxygenase-1 protein is located in cell plasma. The levels of HO-1 protein expression in patients with CHD were significantly higher than in those without CHD (p < 0.01). There were significant differences of HO-1 expression among the three groups of patients with CHD. The group with AMI was the highest, followed by the group with UAP and finally by the group with AP. Conclusions: There is a higher expression of HO-1 in patients with CHD. The levels of HO-1 protein are associated with the severity of CHD.