Search

Objective: MicroRNAs are important intracellular regulators of gene expression, but also circulate in the blood being protected by extracellular vesicles, proteins, or high-density lipoprotein (HDL). Here, we evaluate the regulation and potential function of HDL- and low-density lipoprotein-bound miRs isolated from healthy subjects and patients with coronary artery disease., Approach and Results: HDL-bound miRs with known effects in the cardiovascular system were analyzed in HDL isolated from healthy subjects (n=10), patients with stable coronary artery disease (n=10), and patients with an acute coronary syndrome (n=10). In HDL from healthy subjects, miR-223 was detected at concentrations >10 000 copies/µg HDL, and miR-126 and miR-92a at about 3000 copies/µg HDL. Concentrations of most miRs were substantially higher in HDL as compared with low-density lipoprotein. However, HDL-bound miR-223 contributed to only 8% of the total circulating miRs. The signatures of miRs varied only slightly in HDL derived from patients with coronary artery disease. We did not observe a significant uptake of HDL-bound miRs into endothelial cells, smooth muscle cells, or peripheral blood mononuclear cells. However, patient-derived HDL transiently reduced miR expression particularly when incubated with smooth muscle and peripheral blood mononuclear cells., Conclusions: Circulating miRs are detected in HDL and to a lesser extent in low-density lipoprotein, and the miR-signatures are only slightly altered in patients with coronary artery disease. Lipoprotein-bound miRs were not efficiently delivered to endothelial, smooth muscle, and peripheral blood mononuclear cells suggesting that the lipoprotein-associated pool of miRs is not regulating the function of the studied cells in vitro.

Background: Chronic heart failure (CHF) is associated with a 4-fold increased risk for osteoporotic fractures. Therefore, we sought to identify the pathophysiological link between chronic heart failure and catabolic bone remodeling., Methods and Results: In a total cohort of 153 subjects (123 patients with CHF, 30 patients with coronary artery disease and preserved cardiac function) as well as mice with heart failure, bone marrow (BM) plasma levels of the catabolic receptor activator of NF-κB ligand (RANKL), and its antagonist, osteoprotegerin were measured. The osteoclast inducing activity of BM plasma was tested in cell culture. BM plasma levels of RANKL and of the ratio RANKL/osteoprotegerin were significantly elevated in patients with CHF. On multivariate regression analysis, parameters of severity and duration of heart failure were independent determinants of elevated BM plasma RANKL levels. BM plasma levels of RANKL were directly correlated with the systemic marker of bone turnover C-telopeptide of type 1 collagen (r=0.6; P<0.001). Alterations in BM plasma levels of RANKL/osteoprotegerin were confirmed in a mouse model of postinfarction heart failure. Stimulation of human mesenchymal cells with BM plasma obtained from CHF patients increased the formation of osteoclasts, and this effect was blocked by the RANKL inhibition., Conclusions: CHF is associated with a profound and selective elevation of the bone resorption stimulating RANKL within the BM microenvironment. These data for the first time disclose a direct pathophysiological pathway linking CHF with catabolic bone remodeling associated with an increased osteoporotic fracture risk., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifiers: NCT 00289822, NCT 00284713, NCT 00326989, NCT 00962364.

Rationale: MicroRNAs are small RNAs that control gene expression. Besides their cell intrinsic function, recent studies reported that microRNAs are released by cultured cells and can be detected in the blood., Objective: To address the regulation of circulating microRNAs in patients with stable coronary artery disease., Methods and Results: To determine the regulation of microRNAs, we performed a microRNA profile using RNA isolated from n=8 healthy volunteers and n=8 patients with stable coronary artery disease that received state-of-the-art pharmacological treatment. Interestingly, most of the highly expressed microRNAs that were lower in the blood of patients with coronary artery disease are known to be expressed in endothelial cells (eg, miR-126 and members of the miR-17 approximately 92 cluster). To prospectively confirm these data, we detected selected microRNAs in plasma of 36 patients with coronary artery disease and 17 healthy volunteers by quantitative PCR. Consistent with the data obtained by the profile, circulating levels of miR-126, miR-17, miR-92a, and the inflammation-associated miR-155 were significantly reduced in patients with coronary artery disease compared with healthy controls. Likewise, the smooth muscle-enriched miR-145 was significantly reduced. In contrast, cardiac muscle-enriched microRNAs (miR-133a, miR-208a) tend to be higher in patients with coronary artery disease. These results were validated in a second cohort of 31 patients with documented coronary artery disease and 14 controls., Conclusions: Circulating levels of vascular and inflammation-associated microRNAs are significantly downregulated in patients with coronary artery disease.