Identification of microRNAs 758 and 33b as potential modulators of ABCA1 expression in human atherosclerotic plaques

RNA interference-based therapies for atherosclerosis: Recent advances and future prospects

Atherosclerosis represents a pathological state that affects the arterial system of the organism. This chronic, progressive condition is typified by the accumulation of atheroma within arterial walls. Modulation of RNA molecules through RNA-based therapies has expanded the range of therapeutic options available for neurodegenerative diseases, infectious diseases, cancer, and, more recently, cardiovascular disease (CVD). Presently, microRNAs and small interfering RNAs (siRNAs) are the most widely employed therapeutic strategies for targeting RNA molecules, and for regulating gene expression and protein production. Nevertheless, for these agents to be developed into effective medications, various obstacles must be overcome, including inadequate binding affinity, instability, challenges of delivering to the tissues, immunogenicity, and off-target toxicity. In this comprehensive review, we discuss in detail the current state of RNA interference (RNAi)-based therapies.

The potential role and mechanism of circRNAs in foam cell formation

Atherosclerosis is a significant risk factor for coronary heart disease (CHD) and myocardial infarction (MI). Atherosclerosis develops during foam cell generation, which is caused by an imbalance in cholesterol uptake, esterification, and efflux. LOX-1, SR-A1, and CD36 all increased cholesterol uptake. ACAT1 and ACAT2 promote free cholesterol (FC) esterification to cholesteryl esters (CE). The hydrolysis of CE to FC was aided by nCEH. FC efflux was promoted by ABCA1, ABCG1, ADAM10, and apoA-I. SR-BI promotes not only cholesterol uptake but also FC efflux. Circular RNAs (circRNAs), which are single-stranded RNAs with a closed covalent circular structure, have emerged as promising biomarkers and therapeutic targets for atherosclerosis due to their highly tissue, cell, and disease state-specific expression profiles. Numerous studies have shown that circRNAs regulate foam cell formation, acting as miRNA sponges to influence atherosclerosis development by regulating the expression of SR-A1, CD36, ACAT2, ABCA1, ABCG1, ADAM10, apoA-I, SR-B1. Several circRNAs, including circ-Wdr91, circ 0004104, circRNA0044073, circRNA_0001805, circDENND1B, circRSF1, circ 0001445, and circRNA 102682, are potential biomarkers for atherosclerosis to better evaluate cardiovascular risk. It is difficult to deliver synthetic therapeutic circRNAs to the desired target tissues. Nanotechnology, such as GA-RM/GZ/PL, may be an important solution to this problem. In this review, we focus on the potential role and mechanism of circRNA/miRNA axis in foam cell formation in the hopes of discovering new targets for the diagnosis, prevention, and treatment of atherosclerosis.

Grapefruit Juice Flavanones Modulate the Expression of Genes Regulating Inflammation, Cell Interactions and Vascular Function in Peripheral Blood Mononuclear Cells of Postmenopausal Women

Grapefruit is a rich source of flavanones, phytochemicals suggested excreting vasculoprotective effects. We previously showed that flavanones in grapefruit juice (GFJ) reduced postmenopausal women’s pulse-wave velocity (PWV), a measure of arterial stiffness. However, mechanisms of flavanone action in humans are largely unknown. This study aimed to decipher molecular mechanisms of flavanones by multi-omics analysis in PBMCs of volunteers consuming GFJ and flavanone-free control drink for 6 months. Modulated genes and microRNAs (miRNAs) were identified using microarrays. Bioinformatics analyses assessed their functions, interactions and correlations with previously observed changes in PWV. GFJ modified gene and miRNA expressions. Integrated analysis of modulated genes and miRNA-target genes suggests regulation of inflammation, immune response, cell interaction and mobility. Bioinformatics identified putative mediators of the observed nutrigenomic effect (STAT3, NF-κB) and molecular docking demonstrated potential binding of flavanone metabolites to transcription factors and cell-signaling proteins. We also observed 34 significant correlations between changes in gene expression and PWV. Moreover, global gene expression was negatively correlated with gene expression profiles in arterial stiffness and hypertension. This study revealed molecular mechanisms underlying vasculoprotective effects of flavanones, including interactions with transcription factors and gene and miRNA expression changes that inversely correlate with gene expression profiles associated with cardiovascular risk factors.

Pathogenic role of microRNAs in atherosclerotic ischemic stroke: Implications for diagnosis and therapy

Ischemic stroke resulting from atherosclerosis (particularly in the carotid artery) is one of the major subtypes of stroke and has a high incidence of death. Disordered lipid homeostasis, lipid deposition, local macrophage infiltration, smooth muscle cell proliferation, and plaque rupture are the main pathological processes of atherosclerotic ischemic stroke. Hepatocytes, macrophages, endothelial cells and vascular smooth muscle cells are the main cell types participating in these processes. By inhibiting the expression of the target genes in these cells, microRNAs play a key role in regulating lipid disorders and atherosclerotic ischemic stroke. In this article, we listed the microRNAs implicated in the pathology of atherosclerotic ischemic stroke and aimed to explain their pro- or antiatherosclerotic roles. Our article provides an update on the potential diagnostic use of miRNAs for detecting growing plaques and impending clinical events. Finally, we provide a perspective on the therapeutic use of local microRNA delivery and discuss the challenges for this potential therapy.

Differential Expression of miRNA-223 in Coronary In-Stent Restenosis

Objective: In-stent restenosis (ISR) is an unfavorable complication that occurs in patients after coronary stenting. Despite the progress with advent of modern DES and new antiplatelet agents, restenosis still hampers PCI short- and long-term results. The aim of this study was to investigate whether circulating miRNA-223, which is associated with HDL particles and involved in cholesterol efflux pathway, have diagnostic capability for determining ISR. Methods: This case–control study comprised 21 ISR and 26 NISR patients. The level of miRNA-223 expression was evaluated by TaqMan Real-Time PCR, quantified by the comparative method (fold change) and normalized to U6 expression. Results: Patients in ISR and NISR groups were not different in terms of demographic, clinical, and biochemical parameters, except that the percentage of patients who had DES was significantly greater in the NISR group (88.9%) in comparison with the ISR group (50%). The serum expression of miRNA-223 in ISR patients was 3.277 ± 0.9 times greater than that in NISR group (p = 0.016). In addition, the results of binary logistic regression demonstrated that the high level of serum miRNA-223 was strongly and positively associated with the ISR risk (OR: 17.818, 95% CI: 1.115–284.623, p = 0.042) after adjustment for age, sex, HDL-C, LDL-C, FBS, and statin consumption. Conclusion: Elevated serum level of miRNA-223 might be helpful in predicting the occurrence of ISR. Further confirmation in future large-scale studies is warranted.

Genomic Variants and Multilevel Regulation of ABCA1, ABCG1, and SCARB1 Expression in Atherogenesis

Atheroprotective properties of human plasma high-density lipoproteins (HDLs) are determined by their involvement in reverse cholesterol transport (RCT) from the macrophage to the liver. ABCA1, ABCG1, and SR-BI cholesterol transporters are involved in cholesterol efflux from macrophages to lipid-free ApoA-I and HDL as a first RCT step. Molecular determinants of RCT efficiency that may possess diagnostic and therapeutic meaning remain largely unknown. This review summarizes the progress in studying the genomic variants of ABCA1, ABCG1, and SCARB1, and the regulation of their function at transcriptional and post-transcriptional levels in atherosclerosis. Defects in the structure and function of ABCA1, ABCG1, and SR-BI are caused by changes in the gene sequence, such as single nucleotide polymorphism or various mutations. In the transcription initiation of transporter genes, in addition to transcription factors, long noncoding RNA (lncRNA), transcription activators, and repressors are also involved. Furthermore, transcription is substantially influenced by the methylation of gene promoter regions. Post-transcriptional regulation involves microRNAs and lncRNAs, including circular RNAs. The potential biomarkers and targets for atheroprotection, based on molecular mechanisms of expression regulation for three transporter genes, are also discussed in this review.

Genetics and regulation of HDL metabolism

The inverse association between plasma HDL cholesterol (HDL-C) levels and risk for cardiovascular disease (CVD) has been demonstrated by numerous epidemiological studies. However, efforts to reduce CVD risk by pharmaceutically manipulating HDL-C levels failed and refused the HDL hypothesis. HDL-C levels in the general population are highly heterogeneous and are determined by a combination of genetic and environmental factors. Insights into the causes of HDL-C heterogeneity came from the study of monogenic HDL deficiency syndromes but also from genome wide association and Μendelian randomization studies which revealed the contribution of a large number of loci to low or high HDL-C cases in the general or in restricted ethnic populations. Furthermore, HDL-C levels in the plasma are under the control of transcription factor families acting primarily in the liver including members of the hormone nuclear receptors (PPARs, LXRs, HNF-4) and forkhead box proteins (FOXO1-4) and activating transcription factors (ATFs). The effects of certain lipid lowering drugs used today are based on the modulation of the activity of specific members of these transcription factors. During the past decade, the roles of small or long non-coding RNAs acting post-transcriptionally on the expression of HDL genes have emerged and provided novel insights into HDL regulation and new opportunities for therapeutic interventions. In the present review we summarize recent progress made in the genetics and the regulation (transcriptional and post-transcriptional) of HDL metabolism.

Oxidized LDL-regulated microRNAs for evaluating vascular endothelial function: molecular mechanisms and potential biomarker roles in atherosclerosis

As a simple monolayer, vascular endothelial cells can respond to physicochemical stimuli. In addition to promoting the formation of foam cells, oxidized low-density lipoprotein (ox-LDL) contributes to the atherosclerotic process through different mechanisms, including endothelial cell dysfunction. As conserved noncoding RNAs, microRNAs (miRNAs) naturally lie in different genomic positions and post-transcriptionally regulate the expression of many genes. They participate in integrated networks formed under stress to maintain cellular homeostasis, vascular inflammation, and metabolism. These small RNAs constitute therapeutic targets in different diseases, including atherosclerosis, and their role as biomarkers is crucial given their detectability even years before the emergence of diseases. This review was performed to investigate the role of ox-LDL-regulated miRNAs in atherosclerosis, their molecular mechanisms, and their application as biomarkers of vascular endothelial cell dysfunction.

Increased expression of cyclooxygenase-2 in synovium tissues and synovial fluid from patients with knee osteoarthritis is associated with downregulated microRNA-758-3p expression

Cyclooxygenase-2 (COX-2) is a common factor in inflammation, and its specific regulatory mechanism has not been fully elucidated. The present study aimed to investigate COX-2 mRNA and protein expression levels in synovium tissues and synovial fluid from patients with knee osteoarthritis (KOA), and determine the molecular mechanism by which microRNA (miRNA/miR)-758 regulates KOA via COX-2. A total of 37 patients with KOA and 29 patients with acute knee trauma (control group) were enrolled in the present study. Reverse transcription-quantitative PCR analysis was performed to detect miR-758-3p and COX-2 mRNA expression, while western blotting and ELISA were performed to detect COX-2 protein expression in synovium and synovial fluid, respectively. The dual-luciferase reporter assay was performed to verify the interaction between miR-758-3p and the 3'-untraslated region (UTR) of COX-2 mRNA. Synovial cells were transfected with agomiR-758-3p, and the MTT assay was performed to assess cell proliferation. The results demonstrated that COX-2 expression was higher in patients with KOA than those with acute knee trauma. Conversely, miR-758-3p expression was lower in patients with KOA than those with acute knee trauma. Notably, miR-758-3p interacted with the 3'-UTR of COX-2 mRNA to regulate its expression. Overexpression of miR-758-3p inhibited the expression and release of COX-2, as well as the proliferation of human KOA synovial cells. Taken together, these results suggest that COX-2 expression is upregulated in synovium tissues and synovial fluid from patients with KOA, which is associated with downregulated miR-758-3p expression. In addition, miR-758-3p affects the proliferation of synovial cells and the expression of relevant proteins in these cells, thus promoting the occurrence and development of KOA.

MicroRNA regulation of cholesterol metabolism

MicroRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level. Since many microRNAs have multiple mRNA targets, they are uniquely positioned to regulate the expression of several molecules and pathways simultaneously. For example, the multiple stages of cholesterol metabolism are heavily influenced by microRNA activity. Understanding the scope of microRNAs that control this pathway is highly relevant to diseases of perturbed cholesterol metabolism, most notably cardiovascular disease (CVD). Atherosclerosis is a common cause of CVD that involves inflammation and the accumulation of cholesterol-laden cells in the arterial wall. However, several different cell types participate in atherosclerosis, and perturbations in cholesterol homeostasis may have unique effects on the specialized functions of these various cell types. Therefore, our review discusses the current knowledge of microRNA-mediated control of cholesterol homeostasis, followed by speculation as to how these microRNA-mRNA target interactions might have distinctive effects on different cell types that participate in atherosclerosis.

The Contribution of MicroRNAs to the Inflammatory and Neoplastic Characteristics of Erdheim-Chester Disease

The pathogenesis of histiocytic neoplasms is driven by mutations activating the MAPK/ERK pathway, but little is known about the transcriptional and post-transcriptional alterations involved in these neoplasms. We analyzed microRNA (miRNA) expression in plasma samples and tissue biopsies of Erdheim-Chester disease (ECD) and Langerhans cell histiocytosis (LCH) patients. In silico analysis revealed a potential role of miRNAs in regulating gene expression in these neoplasms as compared with healthy controls (HC). NanoString analysis revealed 101 differentially expressed plasma miRNAs in 16 ECD patients as compared with 11 HC, 95% of which were downregulated. MiRNAs-15a-5p, -15b-5p, -21-5p, -107, -221-3p, -320e, -630, and let-7 family miRNAs were further evaluated by qRT-PCR in an extended cohort of 32 ECD patients, seven LCH and 15 HC. Six miRNAs (let-7a, let-7c, miR-15a-5p, miR-15b-5p, miR-107 and miR-630) were highly expressed in LCH plasma and tissue samples as compared with ECD. Pathway enrichment analysis indicated the miRNA contribution to inflammatory and pro-survival signaling pathways. Moreover, the let-7 family members were downregulated in untreated ECD patients as compared with HC, while treatment with MAPK/ERK signaling inhibitors for 16 weeks resulted in their upregulation, which was in parallel with the radiologic response seen by PET-CT. The study highlights the potential contribution of miRNA to the inflammatory and neoplastic characteristics of ECD and LCH.

Brothers in Arms: ABCA1- and ABCG1-Mediated Cholesterol Efflux as Promising Targets in Cardiovascular Disease Treatment

Atherosclerosis is a leading cause of cardiovascular disease worldwide, and hypercholesterolemia is a major risk factor. Preventive treatments mainly focus on the effective reduction of low-density lipoprotein cholesterol, but their therapeutic value is limited by the inability to completely normalize atherosclerotic risk, probably due to the disease complexity and multifactorial pathogenesis. Consequently, high-density lipoprotein cholesterol gained much interest, as it appeared to be cardioprotective due to its major role in reverse cholesterol transport (RCT). RCT facilitates removal of cholesterol from peripheral tissues, including atherosclerotic plaques, and its subsequent hepatic clearance into bile. Therefore, RCT is expected to limit plaque formation and progression. Cellular cholesterol efflux is initiated and propagated by the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. Their expression and function are expected to be rate-limiting for cholesterol efflux, which makes them interesting targets to stimulate RCT and lower atherosclerotic risk. This systematic review discusses the molecular mechanisms relevant for RCT and ABCA1 and ABCG1 function, followed by a critical overview of potential pharmacological strategies with small molecules to enhance cellular cholesterol efflux and RCT. These strategies include regulation of ABCA1 and ABCG1 expression, degradation, and mRNA stability. Various small molecules have been demonstrated to increase RCT, but the underlying mechanisms are often not completely understood and are rather unspecific, potentially causing adverse effects. Better understanding of these mechanisms could enable the development of safer drugs to increase RCT and provide more insight into its relation with atherosclerotic risk. SIGNIFICANCE STATEMENT: Hypercholesterolemia is an important risk factor of atherosclerosis, which is a leading pathological mechanism underlying cardiovascular disease. Cholesterol is removed from atherosclerotic plaques and subsequently cleared by the liver into bile. This transport is mediated by high-density lipoprotein particles, to which cholesterol is transferred via ATP-binding cassette transporters ABCA1 and ABCG1. Small-molecule pharmacological strategies stimulating these transporters may provide promising options for cardiovascular disease treatment.

CircRSF1 contributes to endothelial cell growth, migration and tube formation under ox-LDL stress through regulating miR-758/CCND2 axis

AIMS

Compelling evidences demonstrate that informative RNAs play essential role in therapy of atherosclerosis. Here, we attempted to study the role of hsa_circ_0000345 (circRSF1) in endothelial cell damage through competing endogenous RNA pathway.

MATERIALS AND METHODS

Expression of circRSF1, miRNA-758-3p (miR-758) and cyclin D2 (CCND2) was detected using RT-qPCR and western blotting, and the cross-talk among them was identified using dual-luciferase reporter assay and RNA immunoprecipitation. The low-density lipoprotein cholesterol (LDL-C) level was measured with enzyme-linked immunosorbent assay. Cell growth was measured by MTS assay, flow cytometry and caspase-3 activity assay kit. Migration and tube formation were determined by scratch migration assay and tube formation assay, respectively.

KEY FINDINGS

CircRSF1 and CCND2 were downregulated, whereas miR-758 was upregulated in serum of patients with atherosclerosis and oxidized low-density lipoprotein (ox-LDL)-treated human aortic endothelial cells (HAECs). Moreover, levels of circRSF1, miR-758 and CCND2 were correlated with circulating LDL-C level. Restoring circRSF1 and silencing miR-758 could improve cell viability, tube formation and migration of HAECs under ox-LDL treatment, as well as attenuated apoptotic rate and caspase-3 activity. However, miR-758 upregulation counteracted the promotion of circRSF1 on cell growth, migration and tube formation in ox-LDL-induced HAECs; so did CCND2 deletion on effect of miR-758 silence. Notably, circRSF1 and CCND2 could competitively bound to miR-758, and circRSF1 positively regulated CCND2 expression via miR-758.

SIGNIFICANCE

CircRSF1 could protect against ox-LDL-induced endothelial cell injury in vitro via miR-758/CCND2 axis, suggesting circRSF1 as a potential target for the treatment of atherosclerosis.

Small Things Matter: Relevance of MicroRNAs in Cardiovascular Disease

MicroRNAs (miRNAs) are short sequences of non-coding RNA that play an important role in the regulation of gene expression and thereby in many physiological and pathological processes. Furthermore, miRNAs are released in the extracellular space, for example in vesicles, and are detectable in various biological fluids, such as serum, plasma, and urine. Over the last years, it has been shown that miRNAs are crucial in the development of several cardiovascular diseases (CVDs). This review discusses the (patho)physiological implications of miRNAs in CVD, ranging from cardiovascular risk factors (i.e., hypertension, diabetes, dyslipidemia), to atherosclerosis, myocardial infarction, and cardiac remodeling. Moreover, the intriguing possibility of their use as disease-specific diagnostic and prognostic biomarkers for human CVDs will be discussed in detail. Finally, as several approaches have been developed to alter miRNA expression and function (i.e., mimics, antagomirs, and target-site blockers), we will highlight the miRNAs with the most promising therapeutic potential that may represent suitable candidates for therapeutic intervention in future translational studies and ultimately in clinical trials. All in all, this review gives a comprehensive overview of the most relevant miRNAs in CVD and discusses their potential use as biomarkers and even therapeutic targets.

From Endothelium to Lipids, Through microRNAs and PCSK9: A Fascinating Travel Across Atherosclerosis

Lipids and endothelium are pivotal players on the scene of atherosclerosis and their interaction is crucial for the establishment of the pathological processes. The endothelium is not only the border of the arterial wall: it plays a key role in regulating circulating fatty acids and lipoproteins and vice versa it is regulated by these lipidic molecules thereby promoting atherosclerosis. Inflammation is another important element in the relationship between lipids and endothelium. Recently, proprotein convertase subtilisin/kexin type 9 (PCSK9) has been recognized as a fundamental regulator of LDL-C and anti-PCSK9 monoclonal antibodies have been approved for therapeutic use in hypercholesterolemia, with the promise to subvert the natural history of the disease. Moreover, growing experimental and clinical evidence is enlarging our understanding of the mechanisms through which this protein may facilitate the genesis of atherosclerosis, independently of its impact on lipid metabolism. In addition, environmental stimuli may affect the post-transcriptional regulation of genes through micro-RNAs, which in turn play a key role in orchestrating the crosstalk between endothelium and cholesterol. Advances in experimental research, with development of high throughput techniques, have led, over the last century, to a tremendous progress in the understanding and fine tuning of the molecular mechanisms leading to atherosclerosis. Identification of pivotal keystone molecules bridging lipid metabolism, endothelial dysfunction and atherogenesis will provide the mechanistic substrate to test valuable targets for prediction, prevention and treatment of atherosclerosis-related disease.

High dose rosuvastatin increases ABCA1 transporter in human atherosclerotic plaques in a cholesterol-independent fashion

BACKGROUND

ATP-binding cassette A1 (ABCA1) and G1 (ABCG1) mediate cholesterol efflux from lipid-laden macrophages, thus promoting anti-atherosclerotic outcomes. The mechanism(s) linking treatment with statins and ABCA1/ABCG1 in human atherosclerosis are not fully understood and require further investigation. Therefore, we studied whether short-term treatment with low- or high-dose rosuvastatin may affect ABCA1 and ABCG1 expression in human atherosclerotic plaques.

METHODS

Seventy patients with severe stenosis of the internal carotid artery were randomized to receive low (10 mg/day) or high (40 mg/day) dose rosuvastatin for 12 weeks before elective endarterectomy. As controls, we analyzed a reference group of 10 plaques from subjects with hypercholesterolemia but not receiving statin treatment and an additional set of 11 plaques collected from normocholesterolemic patients. On atherosclerotic plaques, ABCA1 and ABCG1 expression was evaluated at RNA level by qPCR and at protein level by immunoblotting and immunohistochemistry.

RESULTS

Both rosuvastatin doses were associated with lower plaque ABCA1 mRNA levels and with a trend toward reduction for ABCG1. However, ABCA1 protein was paradoxically higher in patients treated with high-dose rosuvastatin and was associated with lower levels of miR-33b-5p, a microRNA known as a regulator of ABCA1. Multivariate analyses showed that the effect is cholesterol-independent. Finally, no effects were found for ABCG1 protein.

CONCLUSIONS

High-dose rosuvastatin increases macrophage ABCA1 protein levels in human atherosclerotic plaque despite mRNA reduction in a mechanism unrelated to plasma cholesterol reduction and potentially involving miR-33b-5p. This pathway may reflect an additional feature contributing to the anti-atherosclerotic effect for high-dose rosuvastatin.

TRIAL REGISTRATION

ISRCTN16590640.

MiR-758-3p suppresses proliferation, migration and invasion of hepatocellular carcinoma cells via targeting MDM2 and mTOR

Hepatocelluar carcinoma (HCC) is one of the most frequently diagnosed cancers worldwide and among the leading causes of cancer-related death. Although deregulation of microRNAs has been frequently described in HCC, imperfection is known about the precise molecular mechanisms by which microRNAs modulate the process of tumorogenesis and behavior of cancer cells. In this study, we demonstrated that miR-758-3p could suppress cell proliferation, migration and invasion in hepatocellular carcinoma cells. We screened and identified two novel miR-758-3p targets, MDM2 and mTOR. Up-regulation of miR-758-3p could specifically and markedly down-regulate the expression of MDM2 and mTOR. Additionally, miR-758-3p over-expression displayed significant suppression in HCC development. To identify the mechanisms, we further investigated the P53 and mTOR pathway and found that p-p70S6 kinase(Ser371), p-p70 S6 kinase(Thr389) and p-4E-BP1were dramatically down-regulated after miR-758-3p transfection, while an enhanced expression of P53, AKT and PRAS40 were visualized, thus suggesting that the role of miR-758-3p in HCC progression may be associated with MDM2-p53 and mTOR signaling pathways. Collectively, our results indicate that miR-758-3pserves as a tumor suppressor and plays a crucial role in inhibiting the proliferation, migration and invasion of HCC via targeting MDM2 and mTOR and implicate its potential application in cancer therapy.

miR-758-5p regulates cholesterol uptake via targeting the CD36 3'UTR

miR-758-3p plays an important role via regulting ABCA1-mediated cholesterol efflux in atherosclerosis. However, the mechanism of miR-758-5p in cholesterol metabolism is still unclear. Here, we revealed that miR-758-5p decreased total cholesterol accumulation in THP-1 macrophage derived foam cells through markedly reducing cholesterol uptake, and no effect on the cholesterol efflux. Interestingly, computational analysis suggests that CD36 may be a target gene of miR-758-5p. Our study further demonstrated that miR-758-5p decreased CD36 expression at both protein and mRNA levels via targeting the CD36 3'UTR in THP-1 macrophage derived foam cells. The present present study concluded that miR-758-5p decreases lipid accumulation of foam cell via regulating CD36-mediated the cholesterol uptake. Therefore, targeting miR-758-5p may offer a promising strategy to treat atherosclerotic vascular disease.

Upregulation of microRNA-206 induces apoptosis of vascular smooth muscle cells and decreases risk of atherosclerosis through modulating FOXP1

Forkhead box protein subfamily P (FOXP) 1 has an important role in the control of gene transcription and is also reported to function as a tumor suppressor. The aim of the present study was to explore the regulatory mechanisms of atherosclerosis by investigating the function of microRNA-206 (miR-206) and the regulatory association between miR-206 and its potential target gene, FOXP1, in vascular smooth muscle cells (VSMCs). Bioinformatics tools were utilized to identify FOXP1 as a target of miR-206. Luciferase reporter analysis was used to confirm this relationship and to identify the miR-206 binding site in the FOXP1 3′-untranslated region. It was demonstrated that the relative survival rate of VSMCs was suppressed by miR-206 compared with scramble controls. Furthermore, reduced expression of miR-206 in atherosclerosis tissue samples was observed, and the mRNA and protein expression levels of FOXP1 were upregulated in atherosclerosis tissue samples, both compared with the controls, indicating a negative correlation between miR-206 and FOXP1. Additionally, when treated with miR-206 mimics, the relative survival rate of VSMCs was notably reduced, which was rescued by overexpression of FOXP1. These findings increased the understanding of the regulatory role of miR-206 in atherosclerosis in VSMCs via targeting the FOXP1 gene; therefore, intervention with miR-206 as a therapeutic technique may be a strategy for atherosclerosis treatment in the future.

Atherosclerosis revisited from a clinical perspective: still an inflammatory disease?

Compelling experimental results have substantiated the immune-driven inflammatory nature of atherosclerosis. Most of the scientific advances over the past decades have been achieved by relying on transgenic animal models that have been employed with increasing levels of sophistication. However, recent failures in translating various anti-inflammatory therapeutic strategies for use in humans might raise some skepticism with regards to an inflammatory causality underlying human atherosclerosis. By applying a dialectical approach, this Perspective aims to challenge and deduce the nature of atherosclerosis by reviewing results exclusively derived from human studies and recent clinical trials, as "things may not always be, what they appear".

A comparison of microRNA expression profiles from splenic hemangiosarcoma, splenic nodular hyperplasia, and normal spleens of dogs

Background

Splenic masses are common in older dogs; yet diagnosis preceding splenectomy and histopathology remains elusive. MicroRNAs (miRNAs) are short, non-coding RNAs that play a role in post-transcriptional regulation, and differential expression of miRNAs between normal and tumor tissue has been used to diagnose neoplastic diseases. The objective of this study was to determine differential expression of miRNAs by use of RNA-sequencing in canine spleens that were histologically confirmed as hemangiosarcoma, nodular hyperplasia, or normal.

Results

Twenty-two miRNAs were found to be differentially expressed in hemangiosarcoma samples (4 between hemangiosarcoma and both nodular hyperplasia and normal spleen and 18 between hemangiosarcoma and normal spleen only). In particular, mir-26a, mir-126, mir-139, mir-140, mir-150, mir-203, mir-424, mir-503, mir-505, mir-542, mir-30e, mir-33b, mir-365, mir-758, mir-22, and mir-452 are of interest in the pathogenesis of hemangiosarcoma.

Conclusions

Findings of this study confirm the hypothesis that miRNA expression profiles are different between canine splenic hemangiosarcoma, nodular hyperplasia, and normal spleens. A large portion of the differentially expressed miRNAs have roles in angiogenesis, with an additional group of miRNAs being dysregulated in vascular disease processes. Two other miRNAs have been implicated in cancer pathways such as PTEN and cell cycle checkpoints. The finding of multiple miRNAs with roles in angiogenesis and vascular disease is important, as hemangiosarcoma is a tumor of endothelial cells, which are driven by angiogenic stimuli. This study shows that miRNA dysregulation is a potential player in the pathogenesis of canine splenic hemangiosarcoma.

Truths and controversies concerning the role of miRNAs in atherosclerosis and lipid metabolism

PURPOSE OF REVIEW

Better tools are sorely needed for both the prevention and treatment of cardiovascular diseases, which account for more than one-third of the deaths in Western countries. MicroRNAs typically regulate the expression of several mRNAs involved in the same biological process. Therapeutic manipulation of miRNAs could restore the expression of multiple players within the same physiologic pathway, and ideally offer better curative outcomes than conventional approaches that target only one single player within the pathway. This review summarizes available studies on the prospective value of targeting miRNAs to prevent dyslipidemia and atherogenesis.

RECENT FINDINGS

Silencing the expression of miRNAs that target key genes involved in lipoprotein metabolism in vivo with antisense oligonucleotides results in the expected de-repression of target mRNAs in liver and atherosclerotic plaques. However, the consequences of long-term antimiRNA treatment on both circulating lipoproteins and athero-protection are yet to be established.

SUMMARY

A number of studies have demonstrated the efficacy of miRNA mimics and inhibitors as novel therapeutic tools for treating dyslipidemia and cardiovascular diseases. Nevertheless, concerns over unanticipated side-effects related to de-repression of additional targets should not be overlooked for miRNA-based therapies.

MicroRNAs in lipid metabolism and atherosclerosis

Numerous studies have examined the role of microRNAs (miRNAs) in cell homeostasis and cardiovascular disease and have markedly improved our understanding of RNA biology in general and the potential role of miRNAs in atherosclerosis. In atherosclerosis, several miRNAs, such as miR-33a,b, miR-92a, miR-126 and others, have been identified that are relevant mediators of pathological processes, including regulation of cholesterol and lipid biosynthesis, lipoprotein metabolism and cholesterol efflux, but also immune responses, endothelial cell biology and vascular function. Further understanding of the specific roles of miRNAs in the distinct cell types involved in atherosclerosis initiation, progression and resolution may reveal new intervention strategies for the prevention and treatment of atherosclerotic cardiovascular disease.

Macrophage miRNAs in atherosclerosis

The discovery of endogenous microRNAs (miRNAs) in the early 1990s has been followed by the identification of hundreds of miRNAs and their roles in regulating various biological processes, including proliferation, apoptosis, lipid metabolism, glucose homeostasis and viral infection Esteller (2011), Ameres and Zamore (2013) [1,2]. miRNAs are small (~22 nucleotides) non-coding RNAs that function as "rheostats" to simultaneously tweak the expression of multiple genes within a genetic network, resulting in dramatic functional modulation of biological processes. Although the last decade has brought the identification of miRNAs, their targets and function(s) in health and disease, there remains much to be deciphered from the human genome and its complexities in mechanistic regulation of entire genetic networks. These discoveries have opened the door to new and exciting avenues for therapeutic interventions to treat various pathological diseases, including cardiometabolic diseases such as atherosclerosis, diabetes and obesity. In a complex multi-factorial disease like atherosclerosis, many miRNAs have been shown to contribute to disease progression and may offer novel targets for future therapy. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

miRNAs and High-Density Lipoprotein metabolism

Altered lipoprotein metabolism plays a key role during atherogenesis. For over 50years, epidemiological data have fueled the proposal that HDL-cholesterol (HDL-c) in circulation is inversely correlated to cardiovascular risk. However, the atheroprotective role of HDL is currently the focus of much debate and remains an active field of research. The emerging picture from research in the past decade suggests that HDL function, rather than HDL-c content, is important in disease. Recent developments demonstrate that miRNAs play an important role in fine-tuning the expression of key genes involved in HDL biogenesis, lipidation, and clearance, as well as in determining the amounts of HDL-c in circulation. Thus, it has been proposed that miRNAs that affect HDL metabolism might be exploited therapeutically in patients. Whether HDL-based therapies, alone or in combination with LDL-based treatments (e.g. statins), provide superior outcomes in patients has been recently questioned by human genetics studies and clinical trials. The switch in focus from "HDL-cholesterol" to "HDL function" opens a new paradigm to understand the physiology and therapeutic potential of HDL, and to find novel modulators of cardiovascular risk. In this review we summarize the current knowledge on the regulation of HDL metabolism and function by miRNAs. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

Small but smart: MicroRNAs orchestrate atherosclerosis development and progression

MicroRNAs (miRNAs) are short non-coding RNA able to bind specific sequences on target messenger RNAs (mRNAs) and thereby to post-transcriptionally modulate gene expression. Being expressed in all vertebrate cell types, miRNAs have emerged as key players in a wide array of biological processes, including cell proliferation, differentiation and apoptosis. Over the past decade, knowledge concerning the contribution of miRNAs to human pathology has grown with an astonishing pace. In particular, a major involvement of miRNAs in atherosclerosis as a leading cause of global mortality has been supported by ample evidence from in vitro, in vivo and clinical studies. This review aims to summarize and highlight current concepts of miRNA function in the continuum of atherogenesis ranging from risk factors (i.e. dyslipidemia, diabetes, hypertension), to endothelial dysfunction up to the events leading to plaque rupture. Areas in need for further research and potential perspectives for translational applications will be scrutinized. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

MicroRNAs and High-Density Lipoprotein Cholesterol Metabolism

MicroRNAs (miRNAs) are small non-protein-coding RNAs that negatively regulate gene expression. They bind to the 3'-untranslated region of specific mRNAs and inhibit translation or promote mRNA degradation. Dyslipidemia/hyperlipidemia is a well-accepted risk factor for the development of atherosclerosis. The pathogenesis factors involved in lipid abnormalities are being examined extensively, and there is emerging evidence linking miRNAs to lipid metabolism. Among them, recent studies, including ours, have demonstrated that miRNAs control the expression of genes associated with high-density lipoprotein (HDL) cholesterol (HDL-C) metabolism, including ABCA1, ABCG1, and scavenger receptor class B, type I. Moreover, HDL-C itself was proved to carry miRNAs and deliver them to several different types of cells. In this review, we describe the current understanding of the functions of miRNAs in HDL metabolism and their potential in therapy for treating cardiometabolic diseases.

MicroRNA profiling in migraine without aura: pilot study

BACKGROUND AND PURPOSE

MicroRNAs (miRNAs) are short, non-coding RNAs whose deregulation has been shown in several human diseases, including pain states and diseases associated with increased cardiovascular (CV) risk. This study aimed at identifying differentially expressed circulating miRNAs in patients with 'migraine without aura' (MO), a pain condition whose link with CV risk remains debated.

METHODS

Fifteen female MO patients and 13 matching healthy controls underwent a circulating microRNA expression profiling. MiR-22, miR-26a, miR-26b, miR-27b, miR-29b, let-7b, miR-181a, miR-221, miR-30b, and miR-30e were selected for validation by quantitative real-time polymerase chain reaction.

RESULTS

In migraineurs versus controls, four miRNAs were differentially expressed: miR-27b was significantly up-regulated (q < 0.004), while miR-181a, let-7b, and miR-22 were significantly down-regulated (q ≤ 0.01). MiR-22 and let-7b down-regulation was also confirmed in circulating blood monocytes. A logistic regression model based on microRNA expression profile showed a high accuracy for identifying migraine (AUC of ROC curve: 0.956; P < 0.001).

CONCLUSION

A specific circulating miRNAs profile is associated with migraine without aura. Remarkably, the same miRNAs are known to be modulated in the setting of atherosclerosis and stroke in humans. This study represents a first step towards further characterization of MO diagnosis/pathophysiology, also in relation to its link with cardiovascular risk.

Mechanistic Role of MicroRNAs in Coupling Lipid Metabolism and Atherosclerosis

MicroRNAs (miRNAs, miRs) represent a group of powerful and versatile posttranscriptional regulators of gene expression being involved in the fine control of a plethora of physiological and pathological processes. Besides their well-established crucial roles in the regulation of cell cycle, embryogenesis or tumorigenesis, these tiny molecules have also been shown to participate in the regulation of lipid metabolism. In particular, miRs orchestrate cholesterol and fatty acids synthesis, transport, and degradation and low-density and high-density lipoprotein (LDL and HDL) formation. It is thus not surprising that they have also been reported to affect the development and progression of several lipid metabolism-related disorders including liver steatosis and atherosclerosis. Mounting evidence suggests that miRs might represent important "posttranscriptional hubs" of lipid metabolism, which means that one miR usually targets 3'-untranslated regions of various mRNAs that are involved in different steps of one precise metabolic/signaling pathway, e.g., one miR targets mRNAs of enzymes important for cholesterol synthesis, degradation, and transport. Therefore, changes in the levels of one key miR affect various steps of one pathway, which is thereby promoted or inhibited. This makes miRs potent future diagnostic and even therapeutic tools for personalized medicine. Within this chapter, the most prominent microRNAs involved in lipid metabolism, e.g., miR-27a/b, miR-33/33*, miR-122, miR-144, or miR-223, and their intracellular and extracellular functions will be extensively discussed, in particular focusing on their mechanistic role in the pathophysiology of atherosclerosis. Special emphasis will be given on miR-122, the first microRNA currently in clinical trials for the treatment of hepatitis C and on miR-223, the most abundant miR in lipoprotein particles.