Small but smart: MicroRNAs orchestrate atherosclerosis development and progression

Implications of miR-148a-3p/p35/PTEN signaling in tau hyperphosphorylation and autoregulatory feedforward of Akt/CREB in Alzheimer's disease

Existing studies have revealed that microRNAs (miRNAs) have a role in cognitive deficits in Alzheimer's disease (AD). However, the function and pathophysiological mechanism of deregulated miRNAs underlying AD pathology remain to be investigated. The present study aimed to clarify the role and mechanism of miR-148a-3p in AD. RNA sequencing, qRT-PCR, and western blot analysis were used to identify the aberrant expression and signaling of miR-148a-3p within cells, mice, and patients with AD. Molecular biology techniques involving luciferase reporter assays, gene overexpression and silencing, chromatin immunoprecipitation, and adeno-associated virus-based miRNA overexpression were used to explore the biological function and mechanisms of miR-148a-3p. Downregulation of miR-148a-3p was identified in AD. Upregulation of miR-148a-3p was found to protect neuronal cells against Aβ-associated tau hyperphosphorylation by directly targeting p35/CDK5 and PTEN/p38 mitogen-activated protein kinase (MAPK) pathways. A mutual regulatory link between miR-148a-3p and PTEN using a feedforward arrangement was confirmed via promotion of transcription and expression of miR-148a-3p by way of the PTEN/Akt/CREB pathway. Significantly, in vivo targeting of miR-148a-3p signaling ameliorated cognitive deficits by decreasing p35/PTEN-elicited tau hyperphosphorylation, accompanied by feedforward transduction of the PTEN/Akt/CREB pathway. In conclusion, the present study implicated the miR-148a-3p/p35/PTEN pathway as an essential contributor to tau hyperphosphorylation and feedforward regulation in AD.

Profiling of Primary and Mature miRNA Expression in Atherosclerosis-Associated Cell Types

[Figure: see text].

Acute ischemic stroke biomarkers: a new era with diagnostic promise?

Stroke is considered as the first cause of neurological dysfunction and second cause of death worldwide. Recombinant tissue plasminogen activator is the only chemical treatment for ischemic stroke approved by the US Food and Drug Administration. It was the only standard of care for a long time with a very narrow therapeutic window, which usually ranges from 3 to 4.5 h of stroke onset; until 2015, when multiple trials demonstrated the benefit of mechanical thrombectomy during the first 6 h. In addition, recent trials showed that mechanical thrombectomy can be beneficial up to 24 h if the patients meet certain criteria including the presence of magnetic resonance imaging/computed tomography perfusion mismatch, which allows better selectivity and higher recruitment of eligible stroke patients. However, magnetic resonance imaging/computed tomography perfusion is not available in all stroke centers. Hence, physicians need other easy and available diagnostic tools to select stroke patients eligible for mechanical thrombectomy. Moreover, stroke management is still challenging for physicians, particularly those dealing with patients with "wake-up" stroke. The resulting brain tissue damage of ischemic stroke and the subsequent pathological processes are mediated by multiple molecular pathways that are modulated by inflammatory markers and post-transcriptional activity. A considerable number of published works suggest the role of inflammatory and cardiac brain-derived biomarkers (serum matrix metalloproteinase, thioredoxin, neuronal and glial markers, and troponin proteins) as well as different biomarkers including the emerging roles of microRNAs. In this review, we assess the accumulating evidence regarding the current status of acute ischemic stroke diagnostic biomarkers that could guide physicians for better management of stroke patients. Our review could give an insight into the roles of the different emerging markers and microRNAs that can be of high diagnostic value in patients with stroke. In fact, the field of stroke research, similar to the field of traumatic brain injury, is in immense need for novel biomarkers that can stratify diagnosis, prognosis, and therapy.

Interaction Between microRNA and DNA Methylation in Atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease accompanied by complex pathological changes, such as endothelial dysfunction, foam cell formation, and vascular smooth muscle cell proliferation. Many approaches, including regulating AS-related gene expression in the transcriptional or post-transcriptional level, contribute to alleviating AS development. The DNA methylation is a crucial epigenetic modification in regulating cell function by silencing the relative gene expression. The microRNA (miRNA) is a type of noncoding RNA that plays an important role in gene post-transcriptional regulation and disease development. The DNA methylation and the miRNA are important epigenetic factors in AS. However, recent studies have found a mutual regulation between these two factors in AS development. In this study, recent insights into the roles of miRNA and DNA methylation and their interaction in the AS progression are reviewed.

In silico Prediction of miRNA Interactions With Candidate Atherosclerosis Gene mRNAs

The involvement of genes and miRNAs in the development of atherosclerosis is a challenging problem discussed in recent publications. It is necessary to establish which miRNAs affect the expression of candidate genes. We used known candidate atherosclerosis genes to predict associations. The quantitative characteristics of interactions of miRNAs with mRNA candidate genes were determined using the program, which identifies the localization of miRNA binding sites in mRNA, the free energy interaction of miRNA with mRNA. In mRNAs of GAS6 and NFE2L2 candidate genes, binding sites of 21 miRNAs and of 15 miRNAs, respectively, were identified. In IRS2 mRNA binding sites of 25 miRNAs were located in a cluster of 41 nt. In ADRB3, CD36, FASLG, FLT1, PLA2G7, and PPARGC1A mRNAs, clusters of miR-466, ID00436.3p-miR, and ID01030.3p-miR BS were identified. The organization of overlapping miRNA binding sites in clusters led to their compaction and caused competition among the miRNAs. The binding of 53 miRNAs to the mRNAs of 14 candidate genes with free energy interactions greater than -130 kJ/mole was determined. The miR-619-5p was fully complementary to ADAM17 and CD36 mRNAs, ID01593.5p-miR to ANGPTL4 mRNA, ID01935.5p-miR to NFE2L2, and miR-5096 to IL18 mRNA. Associations of miRNAs and candidate atherosclerosis genes are proposed for the early diagnosis of this disease.

MicroRNA‑125a‑mediated regulation of the mevalonate signaling pathway contributes to high glucose‑induced proliferation and migration of vascular smooth muscle cells

Hyperglycemia contributes to the excessive proliferation and migration of vascular smooth muscle cells (VSMC), which are closely associated with atherosclerosis. MicroRNAs (miRNAs/miRs) constitute a novel class of gene regulators, which have important roles in various pathological conditions. The aim of the present study was to identify miRNAs involved in the high glucose (HG)‑induced VSMC phenotype switch, and to investigate the underlying mechanism. miRNA sequencing and reverse transcription‑quantitative PCR results indicated that inhibition of miR‑125a expression increased the migration and proliferation of VSMCs following HG exposure, whereas the overexpression of miR‑125a abrogated this effect. Furthermore, dual‑luciferase reporter assay results identified that 3‑hydroxy‑3-methyglutaryl‑coA reductase (HMGCR), one of the key enzymes in the mevalonate signaling pathway, is a target of miR‑125a. Moreover, HMGCR knockdown, similarly to miR‑125a overexpression, suppressed HG‑induced VSMC proliferation and migration. These results were consistent with those from the miRNA target prediction programs. Using a rat model of streptozotocin‑induced diabetes mellitus, it was demonstrated that miR‑125a expression was gradually downregulated, and that the expressions of key enzymes in the mevalonate signaling pathway in the aortic media were dysregulated after several weeks. In addition, it was found that HG‑induced excessive activation of the mevalonate signaling pathway in VSMCs was suppressed following transfection with a miR‑125a mimic. Therefore, the present results suggest that decreased miR‑125a expression contributed to HG‑induced VSMC proliferation and migration via the upregulation of HMGCR expression. Thus, miR‑125a‑mediated regulation of the mevalonate signaling pathway may be associated with atherosclerosis.

HDAC inhibitors promote pancreatic stellate cell apoptosis and relieve pancreatic fibrosis by upregulating miR-15/16 in chronic pancreatitis

In chronic pancreatitis, PSCs are activated by proinflammatory cytokines to induce pancreatic fibrogenesis. HDAC inhibition protected against the pancreatic fibrosis and the apoptosis of PSCs through induced apoptosis and depressed inflammation. In our study, we found that miR-15 and miR-16 decreased significantly in chronic pancreatitis and HDAC inhibition could recover the levels of these two miRNAs. HDAC regulated the transcription of miR-15 and miR-16, which then modulate the apoptosis and fibrosis of PSCs. And we proved that Bcl-2 and Smad5 were the target genes of miR-15 and miR-16, which illustrated how HDAC inhibition alleviated the apoptosis and fibrogenesis of PSCs in chronic pancreatitis. These results suggested that HDAC inhibition protects against CP by promoting apoptosis and TGF-β/Smads signaling pathways, and indicated that HDAC inhibition is a potential therapy to alleviate CP patients in clinic, and these need to be explored further.

MicroRNAs as the actors in the atherosclerosis scenario

Atherosclerosis is considered as the most common cardiovascular disease and a leading cause of global mortality, which develops through consecutive steps. Various cellular and molecular biomarkers such as microRNAs are identified to be involved in atherosclerosis progression. MicroRNAs are a group of endogenous, short, non-coding RNAs, which are able to bind to specific sequences on target messenger RNAs and thereby modulate gene expression post-transcriptionally. MicroRNAs are key players in wide range of biological processes; thus, their expression level is regulated in pathophysiological conditions. Ample evidences including in vitro and in vivo studies approved a critical role of microRNAs in epigenetic and the sequential processes of atherosclerosis from risk factors to plaque formation, progression, and rupture. Based on these findings, miRNAs seems to be promising candidates for therapeutic approach. This review summarizes the role of miRNAs in atherosclerosis development, epigenetic, and therapy. Moreover, the application of exosomes in miRNA delivery, and/or their prognostic and diagnostic values are also discussed.

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.

MicroRNAs 342 and 450 together with NOX-4 activity and their association with coronary artery disease in diabetes

BACKGROUND

Dysregulation of miRNAs has been associated with many clinical conditions, including coronary artery disease (CAD). MiRNAs roles in patients with type 2 diabetes mellitus (T2D) with or without CAD, however, have not been clearly understood. Therefore we studied the expression of miRNAs 342 and 450 and the activity of the NADPH oxidase 4 (NOX-4), and their association with anthropometric and biochemical parameters of hyperglycaemia and dyslipidaemia.

SUBJECTS AND METHODS

Blood was collected from 200 outpatient subjects, divided into four groups of 50 individuals including control, T2D, CAD, and T2D with CAD. CAD was further divided based on CAD with angina, CAD clots, and CAD ischaemia to differentiate the primary cause of CAD. We measured the miRNAs 342 and 450 expression and NOX-4 activity, in addition to routine parameters.

RESULTS

The expression of miRNAs 342 and 450 and NOX-4 activity was significantly different between groups. Furthermore, they presented significant correlations with routine parameters, providing evidence of a potentially beneficial role in stratifying the risk for CAD in patients with T2D.

CONCLUSION

The results of this study suggest that the expression of miRNAs 342 and 450 and NOX-4 activity may help identify those individuals with T2D at high risk for developing CAD as well as the prognosis in those with established CAD.

Multi-Omics Approaches to Study Long Non-coding RNA Function in Atherosclerosis

Atherosclerosis is a complex inflammatory disease of the vessel wall involving the interplay of multiple cell types including vascular smooth muscle cells, endothelial cells, and macrophages. Large-scale genome-wide association studies (GWAS) and the advancement of next generation sequencing technologies have rapidly expanded the number of long non-coding RNA (lncRNA) transcripts predicted to play critical roles in the pathogenesis of the disease. In this review, we highlight several lncRNAs whose functional role in atherosclerosis is well-documented through traditional biochemical approaches as well as those identified through RNA-sequencing and other high-throughput assays. We describe novel genomics approaches to study both evolutionarily conserved and divergent lncRNA functions and interactions with DNA, RNA, and proteins. We also highlight assays to resolve the complex spatial and temporal regulation of lncRNAs. Finally, we summarize the latest suite of computational tools designed to improve genomic and functional annotation of these transcripts in the human genome. Deep characterization of lncRNAs is fundamental to unravel coronary atherosclerosis and other cardiovascular diseases, as these regulatory molecules represent a new class of potential therapeutic targets and/or diagnostic markers to mitigate both genetic and environmental risk factors.

Non-coding RNAs in cardiovascular diseases: diagnostic and therapeutic perspectives

Recent research has demonstrated that the non-coding genome plays a key role in genetic programming and gene regulation during development as well as in health and cardiovascular disease. About 99% of the human genome do not encode proteins, but are transcriptionally active representing a broad spectrum of non-coding RNAs (ncRNAs) with important regulatory and structural functions. Non-coding RNAs have been identified as critical novel regulators of cardiovascular risk factors and cell functions and are thus important candidates to improve diagnostics and prognosis assessment. Beyond this, ncRNAs are rapidly emgerging as fundamentally novel therapeutics. On a first level, ncRNAs provide novel therapeutic targets some of which are entering assessment in clinical trials. On a second level, new therapeutic tools were developed from endogenous ncRNAs serving as blueprints. Particularly advanced is the development of RNA interference (RNAi) drugs which use recently discovered pathways of endogenous short interfering RNAs and are becoming versatile tools for efficient silencing of protein expression. Pioneering clinical studies include RNAi drugs targeting liver synthesis of PCSK9 resulting in highly significant lowering of LDL cholesterol or targeting liver transthyretin (TTR) synthesis for treatment of cardiac TTR amyloidosis. Further novel drugs mimicking actions of endogenous ncRNAs may arise from exploitation of molecular interactions not accessible to conventional pharmacology. We provide an update on recent developments and perspectives for diagnostic and therapeutic use of ncRNAs in cardiovascular diseases, including atherosclerosis/coronary disease, post-myocardial infarction remodelling, and heart failure.

Stem cell properties of peripheral blood endothelial progenitors are stimulated by soluble CD146 via miR-21: potential use in autologous cell therapy

Cell-based therapies constitute a real hope for the treatment of ischaemic diseases. One of the sources of endothelial progenitors for autologous cell therapy is Endothelial Colony Forming Cells (ECFC) that can be isolated from peripheral blood. However, their use is limited by their low number in the bloodstream and the loss of their stem cell phenotype associated with the acquisition of a senescent phenotype in culture. We hypothesized that adding soluble CD146, a novel endothelial growth factor with angiogenic properties, during the isolation and growth procedures could improve their number and therapeutic potential. Soluble CD146 increased the number of isolated peripheral blood ECFC colonies and lowered their onset time. It prevented cellular senescence, induced a partial mesenchymal phenotype and maintained a stem cell phenotype by stimulating the expression of embryonic transcription factors. These different effects were mediated through the induction of mature miR-21. When injected in an animal model of hindlimb ischaemia, sCD146-primed ECFC isolated from 40 ml of blood from patients with peripheral arterial disease were able to generate new blood vessels and restore blood flow. Treatment with sCD146 could thus constitute a promising strategy to improve the use of autologous cells for the treatment of ischaemic diseases.

Antioxidants in the Fight Against Atherosclerosis: Is This a Dead End?

PURPOSE OF REVIEW

The purpose of this review is to focus on the outcome of recent antioxidant interventions using synthetic and naturally occurring molecules established as adjuvant strategies to lipid-lowering or anti-inflammatory therapies designed to reduce the risk of cardiovascular disease.

RECENT FINDINGS

To date, accumulated evidence regarding oxidation as a pro-atherogenic factor indicates that redox biochemical events involved in atherogenesis are indeed a very attractive target for the management of cardiovascular disease in the clinic. Nevertheless, although evidence indicates that redox reactions are important in the initiation and progression of atherosclerosis, oxidation with a pro-atherogenic context does not eliminate the fact that oxidation participates in many cases as an essential messenger of important cellular signaling pathways. Therefore, disease management and therapeutic goals require not only high-precision and high-sensitivity methods to detect in plasma very low amounts of reducing and oxidizing molecules but also a much better understanding of the normal processes and metabolic pathways influenced and/or controlled by oxidative stress. As several methodologies have been specifically described for the quantification of the total antioxidant capacity and the oxidation state of diverse biological systems, a successful way to carefully study how redox reactions influence atherosclerosis can be achieved. Since there is still a lack of standardization with many of these methods, clinical trials studying antioxidant capacity have been difficult to compare and therefore difficult to use in order to reach a conclusion. We believe a comprehensive analysis of new knowledge and its relationship with the presence of plasma antioxidants and their reducing capacity will undoubtedly open new ways to understand and develop new therapeutic pathways in the fight not only against atherosclerosis but also against other degenerative diseases.

Role of microRNA in Development of Instability of Atherosclerotic Plaques

MicroRNAs are small noncoding single-stranded RNAs that regulate gene expression. Today, we see an increasing number of studies highlighting the important role of microRNAs in the development and progression of cardiovascular diseases caused by atherosclerotic lesions of arteries. We review the available scientific data on association of the expression of these biomolecules with instability of atherosclerotic plaques in animal models and humans. We made special emphasis on miR-21, -100, -127, -133, -143/145, -221/222, and -494 because they were analyzed in more than one study. We discuss the possibility of microRNAs using in the diagnosis and therapy of atherosclerosis and its complications.

The Potential Role of Platelet-Related microRNAs in the Development of Cardiovascular Events in High-Risk Populations, Including Diabetic Patients: A Review

Platelet activation plays a pivotal role in the development and progression of atherosclerosis, which often leads to potentially fatal ischemic events at later stages of the disease. Platelets and platelet microvesicles (PMVs) contain large amounts of microRNA (miRNA), which contributes largely to the pool of circulating miRNAs. Hence, they represent a promising option for the development of innovative diagnostic biomarkers, that can be specific for the underlying etiology. Circulating miRNAs can be responsible for intracellular communication and may have a biological effect on target cells. As miRNAs associated to both cardiovascular diseases (CVD) and diabetes mellitus can be measured by means of a wide array of techniques, they can be exploited as an innovative class of smart disease biomarkers. In this manuscript, we provide an outline of miRNAs associated with platelet function and reactivity (miR-223, miR-126, miR-197, miR-191, miR-21, miR-150, miR-155, miR-140, miR-96, miR-98) that should be evaluated as novel biomarkers to improve diagnostics and treatment of CVD.

miR-155 Promotes ox-LDL-Induced Autophagy in Human Umbilical Vein Endothelial Cells

As an evolutionarily conserved metabolic process, autophagy is involved in the process of atherosclerosis (AS). MicroRNA-155 (miR-155), a multifunctional miRNA, plays an important role in many physiological and pathological conditions, including AS and autophagy. However, the effect of miR-155 on the regulation of autophagy in endothelial cells has not been reported to date. Therefore, the objective of our study was to investigate the role of miR-155 in autophagy induced by oxidized low-density lipoprotein (ox-LDL) in human umbilical vein endothelial cells (HUVECs). Our results demonstrated that ox-LDL induced autophagy in HUVECs and increased the expression of miR-155 significantly. Overexpression of miR-155 improved autophagic activity, whereas low expression of miR-155 inhibited autophagic activity. Therefore, the data demonstrated that miR-155 has a modulating effect on the autophagy of vascular endothelial cells.

miR-143 Induces the Apoptosis of Prostate Cancer LNCap Cells by Suppressing Bcl-2 Expression

Background

Prostate cancer has become a serious threat to the life of patients. microRNAs are small non-coding RNA molecules that regulate the growth and apoptosis of cells. We aimed to investigate the regulation and mechanism of microRNA (miR-143) in the proliferation and apoptosis of prostate cancer LNCap cells.

Material/Methods

miR-143 and control scramble miRNA were synthesized and respectively transfected into LNCap cells. The proliferation and apoptosis were detected by MTT assay, flow cytometry, and caspase-3 activity assay. The intracellular expression of Bcl-2 was determined by Western blot. Further, LNCap cells were transfected with small interfering RNA (siRNA) targeting Bcl-2 (siBcl-2) or plasmid expressing Bcl-2, followed by transfection of miR-143 or control miRNA. Bcl-2 expression was detected by Western blot, and cell apoptosis was measured by caspase-3 activity assay.

Results

Transfection of miR-143 significantly inhibited the proliferation of LNCap cells (P=0.0073), increased the percentage of externalized phosphatidylserine (P=0.0042), activated the caspase-3 (P=0.0012), and decreased the expression of Bcl-2 (P=0.012) when compared with the control miRNA group. The expression of Bcl-2 was significantly reduced after siBcl-2 transfection. The apoptosis in the siBcl-2+miR-143 group was significantly increased compared with that in the miR-143 group (P=0.036), whereas there was no significant difference in the apoptosis between the siBcl-2+miRNA and miRNA groups. The expression of Bcl-2 was obviously higher after the transfection of Bcl-2-expressing plasmid. The apoptosis in Bcl-2+miR-143 group was significantly reduced compared with the miR-143 group (P=0.031), whereas no significant difference in the apoptosis was detected between the miRNA and Bcl-2+miRNA groups.

Conclusions

Transfection of miR-143 induces the apoptosis of prostate cancer LNCap cells by down-regulating Bcl-2 expression, suggesting that Bcl-2 might be a potential therapeutic target for prostate cancer.

MiR-206 Suppresses the Progression of Coronary Artery Disease by Modulating Vascular Endothelial Growth Factor (VEGF) Expression

Background

We investigated whether microRNA-206 (miR-206) is abnormally expressed in patients with coronary artery disease (CAD). The potential mechanism by which miR-206 may regulate CAD progression was also studied.

Material/Methods

A total of 78 CAD patients in the case group and 65 subjects in the control group were enrolled in this study so that the correlation between miR-206 and CAD could be accurately determined. Serum total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides were detected using a biochemistry analyzer. MiR-206 and vascular endothelial growth factor (VEGF) expression levels were tested using either reverse transcription polymerase chain reaction or western blot. Associations between miR-206 expression and different clinicopathological features of CAD patients were also analyzed. CAD cells were transfected with miR-206 mimic (miR-206), its negative control (miR-NC), miR-206 inhibitor (anti-miR-206), and its negative control (anti-miR-NC), respectively. Flow cytometry was conducted to explore the function of miR-206 in CAD cell apoptosis after transfection. Moreover, transwell assay was carried out to study the migratory ability of endothelial progenitor cells (EPCs) in CAD patients.

Results

MiR-206 expression was enriched in both diseased EPCs and plasma of CAD patients. No significant correlation was found between decrease in miR-206 expression and different clinicopathological features. In addition, miR-206 significantly suppressed the viability and invasion of EPCs in CAD patients, and it promoted the apoptosis of their EPCs. Moreover, we found that miR-206 is able to inhibit VEGF expression.

Conclusions

As suggested by our study, MiR-206 can be a novel benign biomarker for CAD because it may regulate VEGF expression.

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".

Liver microRNAs: potential mediators and biomarkers for metabolic and cardiovascular disease?

Recent discoveries have revealed that microRNAs (miRNAs) play a key role in the regulation of gene expression. In this review, we summarize the rapidly evolving knowledge about liver miRNAs (including miR-33, -33*, miR-223, -30c, -144, -148a, -24, -29, and -122) and their link to hepatic lipid metabolism, atherosclerosis and cardiovascular disease, non-alcoholic fatty liver disease, metabolic syndrome, and type-2 diabetes. With regards to its biomarker potential, the main focus is on miR-122 as the most abundant liver miRNA with exquisite tissue specificity. MiR-122 has been proposed to play a central role in the maintenance of lipid and glucose homeostasis and is consistently detectable in serum and plasma. This miRNA may therefore constitute a novel biomarker for cardiovascular and metabolic diseases.

Modulation of Host miRNAs by Intracellular Bacterial Pathogens

MicroRNAs (miRNAs) are short non-coding RNAs that regulate the expression of protein coding genes of viruses and eukaryotes at the post-transcriptional level. The eukaryotic genes regulated by miRNAs include those whose products are critical for biological processes such as cell proliferation, metabolic pathways, immune response, and development. It is now increasingly recognized that modulation of miRNAs associated with biological processes is one of the strategies adopted by bacterial pathogens to survive inside host cells. In this review, we present an overview of the recent findings on alterations of miRNAs in the host cells by facultative intracellular bacterial pathogens. In addition, we discuss how the altered miRNAs help in the survival of these pathogens in the intracellular environment.