Differences in monocyte miRNA profiles between patients with coronary artery disease and healthy controls

Cardiovascular disease (CVD) is the leading cause of human morbidity and mortality worldwide, underscoring the need to improve diagnostic strategies. Monocytes play a major role in the initiation, propagation, and progression of CVD. MicroRNAs are endogenous small non-coding RNAs that control gene expression and are expressed in a tissue and disease-specific manner. Therefore they have been proposed to be useful biomarkers. The aim of this study was to investigate whether differences in miRNA expression levels in monocytes can be found (i) between patients with premature CVD and healthy controls, (ii) within healthy controls after and before aspirin and statin administration, and (iii) between current, former and non smokers. In this case-control study we measured expression levels of monocyte miRNAs using microarrays from 40 male patients with premature CVD and 40 age-matched healthy males (CTRL_without_medication). CVD was defined as one of the following cardiovascular diseases: myocardial infarction, (un)stable angina, ischemic stroke, transient ischemic attack (TIA) or peripheral artery disease as diagnosed by a medical specialist. Premature CVD was defined as a history of CVD before 51 years of age. Controls were eligible for participation if they did not have a personal or family history for premature CVD and did not use any medication. Most CVD patients use aspirin and statins as secondary prevention. The influence of these drugs on miRNA profiles is unknown. To assess the possible influence of medication on miRNA expression and to control for medication as confounding factor, we asked 27 volunteers in our control cohort to also use these drugs. We administered simvastatin 40 mg, once daily, for 6 weeks and during the last two weeks we added 100mg of acetyl salicylic acid, once daily. Blood samples including isolated platelets were collected at baseline (CVD and CTRL_without_medication) and after six weeks of medication use (CTRL_after_medication). Since circulating monocytes undergo phenotypical changes in the presence of cigarette smoke, we also assessed the influence of smoking status on miRNA expression. Smokers were defined as individuals that are currently smoking; non-smokers were defined as individuals that had never smoked or stopped smoking more than 5 years ago; former smokers were defined as smokers that stopped smoking less than 5 years ago.