Evaluation of Serum RANKL and OPG Levels in Acute Coronary Syndrome

Acute coronary syndrome (ACS) is a common disease, and a major determinant of morbidity and mortality in all races, ethnicities, and cultures. Numerous inflammatory mediators seem to play a pathogenic role in coronary artery disease (CAD), promoting atherogenesis and plaque destabilization, leading to thrombus formation with development of ACS. The pleiotropic effects of the receptor activator of nuclear factor-kappa B ligand /osteoprotegerin (RANKL/OPG) system, such as modulation of cell survival, mineralization and inflammation, make it an interesting candidate mediator in the progression and destabilization of atherosclerotic lesions.
This study was performed to investigate the role of RANKL and OPG and their relative ratio (RANKL\OPG) in pathogenesis of ACS, as well as to study the differences in median serum levels of RANKL, OPG and RANKL / OPG ratio according to some demographic and clinical features. Sixty patients with ACS were enrolled in this study, those patients were divided into two groups: 31 patients were with unstable angina (UA) and 29 patients were with myocardial infarction (MI), the latter group also subdivided into [18 with ST segment elevation myocardial infarction (STEMI) and 11 with non-ST-segment elevation myocardial infarction (NSTEMI)], their ages range from 25-83 years. Twenty apparently healthy volunteers their ages and sexes were matched with the patients were also participated in the study. Enzyme-linked immunosorbent assay was carried out for estimation the serum levels of RANKL and OPG in the studied groups. The current data indicated that there were no significant differences (p>0.05) in median serum levels of RANKL between ACS patients and healthy control group.
In addition the comparison among the three groups of patients (NSTEM1, STEM1 and UA) showed no significant differences (p>0.05) in median serum level of RANKL. Whereas the median serum level of OPG was significantly higher (p<0.001) in ACS patients than that in healthy control. Furthermore; there was significant increase (p<0.05; p<0.001) in median serum level of OPG in the three patients groups as compared to healthy control group. On the other hand, there were no significant differences (p>0.05) in median serum levels of OPG among patients groups. In contrast the ratio of RANKL / OPG was significantly increase (P<0.001) in healthy control as compared to ACS patients. The median RANKL / OPG ratios in NSTEM1, STEM1 and UA patients groups were significantly lower (P<0.001) when compared to the ratio in healthy control. Meanwhile there were no significant differences in ratio among patients groups (p>0.05).
Regarding the differences in median serum levels of RANKL, OPG and RANKL / OPG ratio in ACS patients according to gender type, family history, smoking habit and troponin enzyme, the present results showed that there were no significant differences (p>0.05) in median serum levels of RANKL, OPG and RANKL / OPG ratio in ACS patients in respect to above demographic and clinical features. These findings indicated that there was high significant elevation in serum level of OPG in ACS patients. In addition the present data enforce the clinical utility of OPG in atherosclerosis and suggested that RANKL/OPG ratio could be a better biomarker for CAD.