MicroRNAs as Early Biomarkers in Obesity and Related Metabolic and Cardiovascular Diseases

The increasing prevalence of obesity has significant implications for healthcare, more particularly since it is a major risk factor for type 2 diabetes and cardiovascular diseases. However, not every obese patient is at the same risk of developing future metabolic and cardiovascular complications. Therefore, there is an urgent need for novel biomarkers for early identification of obese patients at high risk. Possible candidate biomarkers are microRNAs, which are highly conserved non-coding RNA molecules of approximately 22 nucleotides that exert post-transcriptional effects on gene expression. They are expressed in a tissue- and cell-type specific manner, play essential roles in many biological and pathological processes and are released in human peripheral blood in a disease-specific manner where they remain stable due to association with lipoprotein and phospholipids. All these characteristics suggest that they are putative diagnostic biomarkers. This review summarizes microRNAs with a functional role in the pathogenesis of atherosclerosis, myocardial infarction, ischemia/reperfusion injury and cardiac remodeling. It emphasizes those which have already been deregulated in association with obesity-related risk factors clustered in the metabolic syndrome. It demonstrates that several microRNAs which have been claimed to be biomarkers for cardiovascular diseases have already been deregulated in association with metabolic disorders prior to cardiovascular diseases. Finally, it summarizes which of these functionally validated microRNAs are deregulated in the circulation making them easily accessible for detection and thus into candidate biomarkers for early diagnosis of obesity-induced cardiovascular events.