MicroRNA expression signature in human abdominal aortic aneurysms

Roles and Mechanisms of miRNAs in Abdominal Aortic Aneurysm: Signaling Pathways and Clinical Insights

PURPOSE OF REVIEW

Abdominal aortic aneurysm refers to a serious medical condition that can cause the irreversible expansion of the abdominal aorta, which can lead to ruptures that are associated with up to 80% mortality. Currently, surgical and interventional procedures are the only treatment options available for treating abdominal aortic aneurysm patients. In this review, we focus on the upstream and downstream molecules of the microRNA-related signaling pathways and discuss the roles, mechanisms, and targets of microRNAs in abdominal aortic aneurysm modulation to provide novel insights for precise and targeted drug therapy for the vast number of abdominal aortic aneurysm patients.

RECENT FINDINGS

Recent studies have highlighted that microRNAs, which are emerging as novel regulators of gene expression, are involved in the biological activities of regulating abdominal aortic aneurysms. Accumulating studies suggested that microRNAs modulate abdominal aortic aneurysm development through various signaling pathways that are yet to be comprehensively summarized. A total of six signaling pathways (NF-κB signaling pathway, PI3K/AKT signaling pathway, MAPK signaling pathway, TGF-β signaling pathway, Wnt signaling pathway, and P53/P21 signaling pathway), and a total of 19 miRNAs are intimately associated with the biological properties of abdominal aortic aneurysm through targeting various essential molecules. MicroRNAs modulate the formation, progression, and rupture of abdominal aortic aneurysm by regulating smooth muscle cell proliferation and phenotype change, vascular inflammation and endothelium function, and extracellular matrix remodeling. Because of the broad crosstalk among signaling pathways, a comprehensive analysis of miRNA-mediated signaling pathways is necessary to construct a well-rounded upstream and downstream regulatory network for future basic and clinical research of AAA therapy.

CD147 monoclonal antibody attenuates abdominal aortic aneurysm formation in angiotensin II-Infused apoE-/- mice

BACKGROUND

Abdominal aortic aneurysm (AAA) is a life threatening vascular disease. Our previous study reported the upregulation of CD147 expression in human aortic aneurysms.

OBJECTIVE

In this study, we injected apoE-/- mice intraperitoneally with CD147 monoclonal antibody or IgG control antibody to observe its effect on Angiotensin II (AngII) induced AAA formation.

METHODS

ApoE-/- mice were randomly divided into an AngⅡ+CD147 antibody group (n = 20) and an AngⅡ+IgG antibody group (n = 20). The Alzet osmotic minipump was implanted subcutaneously into the backs of mice to infuse AngII (1000 ng/kg/min) for 28 days and subsequently treated with CD147 monoclonal antibody or control IgG mAb (10 μg/mouse/day) beginning one day after surgery. Body weight, food intake, drinking volume and blood pressure were measured weekly throughout the study. After 4 weeks of injection, routine bloodwork measuring liver function, kidney function and lipid levels were recorded. Hematoxylin and eosin (H&E), Masson's trichrome, and Elastic van Gieson (EVG) staining were used to evaluate the pathological changes in blood vessels. In addition, Immunohistochemical assay was used to detect infiltration of inflammatory cells. Tandem mass tag (TMT)-based proteomic analysis was used to define differentially expressed proteins (DEPs) using a p-value < 0.05 and fold change > 1.2 or < 0.83 as the threshold. Subsequently, we conducted protein-protein interaction (PPI) network and GO enrichment analysis to determine the core biological function altered after CD147 antibody injection.

RESULTS

The CD147 monoclonal antibody suppresses Ang II-induced AAA formation in apoE-/- mice and reduced aortic expansion, elastic lamina degradation, and inflammatory cells accumulation. Bioinformatics analysis showed that Ptk6, Itch, Casp3, and Oas1a were the hub DEPs. These DEPs in the two group were mainly involved in collagen fibril organization, extracellular matrix organization, and muscle contraction. These data robustly demonstrated that CD147 monoclonal antibody suppresses Ang II-induced AAA formation through reduction of inflammatory response and regulation of the above defined hub proteins and biological processes. Thus, the CD147 monoclonal antibody might be a promising target in the treatment of abdominal aortic aneurysm.

Novel pharmacological approaches in abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a severe vascular disease and a major public health issue with an unmet medical need for therapy. This disease is featured by a progressive dilation of the abdominal aorta, boosted by atherosclerosis, ageing, and smoking as major risk factors. Aneurysm growth increases the risk of aortic rupture, a life-threatening emergency with high mortality rates. Despite the increasing progress in our knowledge about the etiopathology of AAA, an effective pharmacological treatment against this disorder remains elusive and surgical repair is still the unique available therapeutic approach for high-risk patients. Meanwhile, there is no medical alternative for patients with small aneurysms but close surveillance. Clinical trials assessing the efficacy of antihypertensive agents, statins, doxycycline, or anti-platelet drugs, among others, failed to demonstrate a clear benefit limiting AAA growth, while data from ongoing clinical trials addressing the benefit of metformin on aneurysm progression are eagerly awaited. Recent preclinical studies have postulated new therapeutic targets and pharmacological strategies paving the way for the implementation of future clinical studies exploring these novel therapeutic strategies. This review summarises some of the most relevant clinical and preclinical studies in search of new therapeutic approaches for AAA.

New Insight into Mechanisms of Cardiovascular Diseases: An Integrative Analysis Approach to Identify TheranoMiRNAs

MiRNAs regulate both physiological and pathological heart functions. Altered expression of miRNAs is associated with cardiovascular diseases (CVDs), making miRNAs attractive therapeutic strategies for the diagnosis and treatment of heart diseases. A recent publication defined, for the first time, the term theranoMiRNA, meaning the miRNAs that may be used both for diagnosis and treatment. The use of in silico tools may be considered fundamental for these purposes, clarifying several molecular aspects, suggesting future directions for in vivo studies. This study aims to explore different bioinformatic tools in order to clarify miRNA interactions with candidate genes, demonstrating the need to use a computational approach when establishing the most probable associations between miRNAs and target genes. This study focused on the functions of miR-133a-3p, miR-21-5p, miR-499a-5p, miR-1-3p, and miR-126-3p, providing an up-to-date overview, and suggests future lines of research in the identification of theranoMiRNAs related to CVDs. Based on the results of the present study, we elucidated the molecular mechanisms that could be linked between miRNAs and CVDs, confirming that these miRNAs play an active role in the genesis and development of heart damage. Given that CVDs are the leading cause of death in the world, the identification of theranoMiRNAs is crucial, hence the need for a definition of in vivo studies in order to obtain further evidence in this challenging field of research.

Circulating miRNAs as biomarkers for diagnosis, surveillance and post-operative follow-up of abdominal aortic aneurysms

OBJECTIVE

To provide a summary of the current state of research in English medical literature on circulating miRNAs, as biomarkers for AAA. Additionally, for the most commonly mentioned circulating miRNAs in the literature, to attempt a documentation of the biological mechanisms underlying their role in AAA development.

METHODS

A literature search was undertaken in the MEDLINE database. Only reports that involved peripheral blood samples (whole blood, plasma, serum) were included. The following terms were used in combination: microrna, mirna, abdominal aortic aneurysm, human, circulating, plasma, serum, endovascular and EVAR.

RESULTS

A total of 25 reports, published from 2012 to 2022 were included with a total of 1259 patients with AAA, predominantly men (N= 1040, 90%). Six of these reports recruited healthy donors who underwent ultrasound screening for AAA as control samples. The majority of studies were undertaken in plasma samples and the most preferred microRNA profiling method was Real - Time quantitative polymerase chain reaction (qRT-PCR). The following nine miRNAs (out of a total of 76) were studied in more than two references: miR-145, miR-24, miR-33, miR-125, let-7, miR-15, miR-191, miR-29 and miR-133.

CONCLUSION

The nine miRNAs described in this study, are implicated in known pathogenetic mechanisms of AAA such as atherosclerosis, vascular smooth muscle cell phenotype switch and apoptosis, vascular inflammation, extracellular matrix degradation and lipid metabolism. Identifying disease-specific miRNAs, in combination with other clinical parameters, as indicators of AAA, is crucial for early diagnosis as well as follow-up of AAAs. For future research on miRNAs as AAA biomarkers, strict case and control group definitions, sample acquisition protocols, and miRNA expression profiling techniques are warranted.

The abdominal aortic aneurysm-related disease model based on machine learning predicts immunity and m1A/m5C/m6A/m7G epigenetic regulation

Introduction: Abdominal aortic aneurysms (AAA) are among the most lethal non-cancerous diseases. A comprehensive analysis of the AAA-related disease model has yet to be conducted. Methods: Weighted correlation network analysis (WGCNA) was performed for the AAA-related genes. Machine learning random forest and LASSO regression analysis were performed to develop the AAA-related score. Immune characteristics and epigenetic characteristics of the AAA-related score were explored. Results: Our study developed a reliable AAA-related disease model for predicting immunity and m1A/m5C/m6A/m7G epigenetic regulation. Discussion: The pathogenic roles of four model genes, UBE2K, TMEM230, VAMP7, and PUM2, in AAA, need further validation by in vitro and in vivo experiments.

MicroRNAs as Biomarkers for Predicting Complications following Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a high mortality hemorrhagic stroke that affects nearly 30,000 patients annually in the United States. Approximately 30% of aSAH patients die during initial hospitalization and those who survive often carry poor prognosis with one in five having permanent physical and/or cognitive disabilities. The poor outcome of aSAH can be the result of the initial catastrophic event or due to the many acute or delayed neurological complications, such as cerebral ischemia, hydrocephalus, and re-bleeding. Unfortunately, no effective biomarker exists to predict or diagnose these complications at a clinically relevant time point when neurologic injury can be effectively treated and managed. Recently, a number of studies have demonstrated that microRNAs (miRNAs) in extracellular biofluids are highly associated with aSAH and complications. Here we provide an overview of the current research on relevant human studies examining the correlation between miRNAs and aSAH complications and discuss the potential application of using miRNAs as biomarkers in aSAH management.

Inhibition of miR-188-5p Suppresses Progression of Experimental Abdominal Aortic Aneurysms

ABSTRACT

Abdominal aortic aneurysm (AAA) is an aging-related degenerative disease. miR-188-5p was reported to induce cell senescence and play a key role in aging-related disease. Therefore, in this study, we investigated miR-188-5p expression during progression in experimental AAAs. Furthermore, we investigated whether inhibition of miR-188-5p could suppress AAA progression. Experimental AAAs were created in 9-12-week-old male C57BL/6J mice by transient intra-aortic infusion of porcine pancreatic elastase. Expression of miR-188-5p levels were assessed in aneurysmal and control aortae during the progression of aneurysm. For inhibition experiment, miR-188 inhibiting group mice were injected with AAV2-miR188-5p sponge through tail vein and control group mice were injected with AAV2-CMV-GFP. Influences on experimental AAA progression were assessed by measurements of aortic diameter and histopathologic analysis at sacrifice. Meanwhile, immunohistochemistry and fluorescence in situ hybridization were used to determine the inflammatory cells infiltration and colocalization of miR-188-5p in aortic sections. Expression of miR-188-5p is upregulated during progression of AAA. Importantly, miR-188-5p inhibition treatment prevented enlargement of experimental aneurysms. Meanwhile, miR-188-5p inhibition regimens attenuated medial elastin degradation, smooth muscle cell depletion, and mural angiogenesis and the accumulation of macrophages, T cells, and angiogenesis. Furthermore, colocalization of miR188-5p with CD68 and CD3 was observed, which suggest miR-188-5p was expressed mainly in infiltrated macrophages and T cells. Expression of miR-188-5p is increased in experimental AAAs. Treatment with miR-188-5p inhibition limits experimental AAA progression, with histologic evidence of reduced neovessels and attenuated mural leukocyte infiltration. These findings underscore the potential significance of miR-188-5p in aneurysm pathogenesis and as a target for suppression of AAA disease.

Identification of Novel microRNA Profiles Dysregulated in Plasma and Tissue of Abdominal Aortic Aneurysm Patients

microRNAs (miRNAs) are small RNAs that regulate different biological processes. Our objective was to identify miRNAs dysregulated in plasma and tissue of patients with abdominal aortic aneurysm (AAA) and explore new potential targets involved in AAA. Fifty-seven subjects were recruited for a plasma study (30 AAA patients, 16 healthy volunteers and 11 patients with atherosclerosis). The expression level of 179 miRNAs was screened in plasma from a subset of samples, and dysregulated miRNAs were validated in the entire study population. Dysregulated miRNAs were also quantified in aortic tissue of 21 AAA patients and 8 organ donors. Applying a gene set enrichment analysis, an interaction map of dysregulated miRNAs and their targets was built, and selected targets were quantified in tissue samples. miR-27b-3p and miR-221-3p were overexpressed in plasma of AAA patients compared with healthy controls, 1.6 times and 1.9 times, respectively. In AAA tissue, six miRNAs (miR-1, miR-27b-3p, miR-29b-3p, miR-133a-3p, miR-133b, and miR-195-5p) were underexpressed from 1.6 to 4.8 times and four miRNAs (miR-146a-5p, miR-21-5p, miR-144-3p, and miR-103a-3p) were overexpressed from 1.3 to 7.2 times. Thrombospondin-2, a target of miR-195-5p, was increased in AAA tissue and negatively correlated with the expression of miR-195-5p, suggesting their involvement in a common regulatory mechanism.

Dysregulation of microRNA Modulatory Network in Abdominal Aortic Aneurysm

Abdominal artery aneurysm (AAA) refers to abdominal aortic dilatation of 3 cm or greater. AAA is frequently underdiagnosed due to often asymptomatic character of the disease, leading to elevated mortality due to aneurysm rupture. MiRNA constitute a pool of small RNAs controlling gene expression and is involved in many pathologic conditions in human. Targeted panel detecting altered expression of miRNA and genes involved in AAA would improve early diagnosis of this disease. In the presented study, we selected and analyzed miRNA and gene expression signatures in AAA patients. Next, generation sequencing was applied to obtain miRNA and gene-wide expression profiles from peripheral blood mononuclear cells in individuals with AAA and healthy controls. Differential expression analysis was performed using DESeq2 and uninformative variable elimination by partial least squares (UVE-PLS) methods. A total of 31 miRNAs and 51 genes were selected as the most promising biomarkers of AAA. Receiver operating characteristics (ROC) analysis showed good diagnostic ability of proposed biomarkers. Genes regulated by selected miRNAs were determined in silico and associated with functional terms closely related to cardiovascular and neurological diseases. Proposed biomarkers may be used for new diagnostic and therapeutic approaches in management of AAA. The findings will also contribute to the pool of knowledge about miRNA-dependent regulatory mechanisms involved in pathology of that disease.

Cell-free microRNA-21: biomarker for intracranial aneurysm rupture

Background

Deregulation of miRNA-21 expression has been reported to be associated with vascular smooth muscle behavior and cytoskeletal stability. This study is aimed to investigate the density of serum miRNA-21 in patients with different phases of intracranial aneurysms (IAs) and explore its warning function for IA rupture.

Methods

A total of 16 in 200 IA patients were selected and categorized into 4 groups based on the phase of IA. Microarray study was carried out using serum miRNA and differentially expressed miRNAs were identified. Another 24 samples from a cohort of 360 patients were added and real-time polymerase chain reaction (RT-PCR) was performed on expanded sample size (n = 40) for miRNA-21 validation. Potential gene targets of miRNA-21 were screened out from Gene Ontology (GO) database and literatures.

Results

Microarray study identified 77 miRNAs with significantly different expression levels between experimental groups and the control group. RT-PCR assays validated significant downregulation of miRNA-21 in experimental groups, among which miRNA-21 expression level of daughter aneurysm group decreased the most. Bioinformatic analyses revealed that several target genes related with miRNA-21 may be involved in IA formation and rupture.

Conclusions

This study suggested that miRNA-21 had a protective effect for intracranial vascular wall against remodeling and warning function for intracranial aneurysm rupture. Significant suppression of serum miRNA-21 in IA patients may provide diagnostic clues for aneurysm rupture and guide clinical intervention.

MicroRNA-331 and microRNA-151-3p as biomarkers in patients with ST-segment elevation myocardial infarction

We sought to analyse plasma levels of peripheral blood microRNAs (miRs) as biomarkers of ST-segment-elevation myocardial infarction (STEMI) due to type-1 myocardial infarction as a model situation of vulnerable plaque (VP) rupture. Samples of 20 patients with STEMI were compared both with a group of patients without angina pectoris in whom coronary angiogram did not reveal coronary atherosclerotic disease (no coronary atherosclerosis-NCA) and a group of patients with stable angina pectoris and at least one significant coronary artery stenosis (stable coronary artery disease-SCAD). This study design allowed us to identify miRs deregulated in the setting of acute coronary artery occlusion due to VP rupture. Based on an initial large scale miR assay screening, we selected a total of 12 miRs (three study miRs and nine controls) that were tested in the study. Two of the study miRs (miR-331 and miR-151-3p) significantly distinguished STEMI patients from the control groups, while ROC analysis confirmed their suitability as biomarkers. Importantly, this was observed in patients presenting early with STEMI, even before the markers of myocardial necrosis (cardiac troponin I, miR-208 and miR-499) were elevated, which suggests that the origin of miR-331 and miR-151-3p might be in the VP. In conclusion, the study provides two novel biomarkers observed in STEMI, which may be associated with plaque rupture.

miR-146a regulates inflammation and development in patients with abdominal aortic aneurysms by targeting CARD10

BACKGROUND

We present the expression of miR-146a in abdominal aortic aneurysms (AAA) patients, and its mechanism for regulating inflammation and development in AAA patients.

METHODS

The expression of miR-146a in serum, PBMC, and abdominal aorta tissues was measured in AAA patients.

RESULTS

We found that level of miR-146a in the serum and its expression in AAA tissues were significantly higher than that in healthy people or normal abdominal aorta tissues. Pearson's method analysis showed that miRNA-146a in the serum of AAA patients was negatively correlated with serum TNF-α, IFN-γ and CRP, and was positively correlated with serum IL-10. The luciferase reporter gene system confirmed that miR-146a targeted inhibition of CARD10 expression in THP-1 and human umbilical vein endothelial cells (HUVECs), and miR-146a was negatively correlated with the expression of CARD10 in the tissues/PBMC of AAA patients. In PBMC of healthy people, over-expression of miR-146a by transferring miR-146a-mimic could increase the expression of SIRT1 but decreased the expression of p65 and the level of TNF-α secretion. Moreover, HUVECs cellular activity change by TNF-α in a dose-dependent manner.

CONCLUSIONS

These results suggested that miR-146a suppressed the inflammation of peripheral blood in AAA patients by targeting CARD10, and miR-146a blocked the progression of AAA through CARD10/SIRT1/p65 pathway.

Let-7f: A New Potential Circulating Biomarker Identified by miRNA Profiling of Cells Isolated from Human Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a progressive vascular disease responsible for 1–4% of the deaths in elderly men. This study aimed to characterize specific microRNA (miRNA) expression in aneurysmal smooth muscle cells (SMCs) and macrophages in order to identify circulating miRNAs associated with AAA. We screened 850 miRNAs in aneurysmal SMCs, M1 and M2 macrophages, and in control SMCs isolated by micro-dissection from aortic biopsies using microarray analysis. In all, 92 miRNAs were detected and 10 miRNAs were selected for validation by qRT-PCR in isolated cells (n = 5), whole control and aneurysmal aorta biopsies (n = 13), and plasma from patients (n = 24) undergoing AAA (over 50 mm) repair matched to patients (n = 18) with peripheral arterial disease (PAD) with atherosclerosis but not AAA. Seven miRNAs were modulated similarly in all aneurysmal cells. The Let-7f was downregulated in aneurysmal cells compared to control SMCs with a significant lower expression in M1 compared to M2 macrophages (0.1 fold, p = 0.03), correlated with a significant downregulation in whole aneurysmal aorta compared to control aorta (0.2 fold, p = 0.03). Significant levels of circulating let-7f (p = 0.048) were found in AAA patients compared to PAD patients with no significant correlation with aortic diameter (R² = 0.03). Our study underlines the utility of profiling isolated aneurysmal cells to identify other miRNAs for which the modulation of expression might be masked when the whole aorta is used. The results highlight let-7f as a new potential biomarker for AAA.

Dysregulation of microRNAs and target genes networks in human abdominal aortic aneurysm tissues

BACKGROUND

Abdominal aortic aneurysm (AAA) is a pathological enlargement of infrarenal aorta close to the aortic bifurcation, and it is an important cause of mortality in the elderly. Therefore, the biomarker identification for early diagnosis is of great interest for clinical benefit. It is known that microRNAs (miRNAs) have important roles via target genes regulation in many diseases. This study aimed to identify miRNAs and their target genes involved in the pathogenesis of AAA.

METHODS

Tissue samples were obtained from patients who underwent AAA surgery and from organ donors (control group). Quantitative PCR Array was applied to assess 84 genes and 384 miRNAs aiming to identify differentially expressed targets (AAA n = 6, control n = 6), followed by validation in a new cohort (AAA n = 18, control n = 6) by regular qPCR. The functional interaction between validated miRNAs and target genes was performed by the Ingenuity Pathway Analysis (IPA) software.

RESULTS

The screening cohort assessed by PCR array identified 10 genes and 59 miRNAs differentially expressed (≥2-fold change, p<0.05). Among these, IPA identified 5 genes and 9 miRNAs with paired interaction. ALOX5, PTGIS, CX3CL1 genes, and miR-193a-3p, 125b-5p, 150-5p maintained a statistical significance in the validation cohort. IPA analysis based on the validated genes and miRNAs revealed that eicosanoid and metalloproteinase/TIMP synthesis are potentially involved in AAA.

CONCLUSION

Paired interactions of differentially expressed ALOX5, PTGIS, CX3CL1 genes, and miR-193b-3p, 125b-5p, 150-5p revealed a potentially significant role of the eicosanoid synthesis and metalloproteinase/TIMP pathways in the AAA pathogenesis.

DAB2IP Expression in Abdominal Aortic Aneurysm: EZH2 and mir-363-3p as Potential Mediators

BACKGROUND/AIM

Nine genetic loci have been associated with abdominal aortic aneurysm (AAA) susceptibility, including DAB2IP. This gene is playing a role in apoptosis, cell proliferation and epithelial-to-mesenchymal transition in cancers. This study aimed to elucidate the differential expression levels of DAB2IP in AAA tissues and investigate whether mir-363-3p and EZH2 can be considered as potential mediators of its expression.

MATERIALS AND METHODS

18 AAA samples and 15 non-aneurysmatic controls were collected. Relative mRNA expression levels of DAB2IP, EZH2 and mir-363-3p were measured using qPCR.

RESULTS

DAB2IP was significant up-regulated (~2.29 fold) in AAA tissues, while EZH2 and mir-363-3p were down-regulated (3.28 and 3.62-fold, respectively). A limited negative correlation was found between the DAB2IP and EZH2 expression and between DAB2IP and the mir-363-3p.

CONCLUSION

An increased expression of DAB2IP in AAA tissues was shown. We suggest 2 potential mediators of DAB2IP expression in abdominal aortic aneurysm, EZH2 and mir-363-3p.

Involvement of the MiR-181b-5p/HMGB1 Pathway in Ang II-induced Phenotypic Transformation of Smooth Muscle Cells in Hypertension

Phenotypic transformation of vascular smooth muscle cells (VSMCs) contributes to vascular remodeling in hypertension. High mobility group box-1 (HMGB1) has been reported to be involved in several pathogenic processes including VSMC proliferation and migration. The present study was designed to determine the role of HMGB1 in VSMC phenotypic transformation in hypertension. First, we demonstrated that HMGB1 was elevated in a model of Ang II-induced VSMC phenotypic transformation, which showed down-regulation of contractile proteins and up-regulation of synthetic proteins. Knockdown of HMGB1 and losartan could block the phenotypic transformation. Next, we identified three potential miRNAs for upstream regulation of HMGB1 by bioinformatic analysis; only miR-181b-5p was significantly down-regulated in Ang II-treated cells. Co-treating the cells with miR-181b-5p mimics suppressed HMGB1 expression as well as the phenotypic transformation, migration, and proliferation. Furthermore, the luciferase reporter gene assay confirmed the direct interaction between miR-181b-5p and HMGB1. Finally, to extend these cell-based studies to clinical patients, we demonstrated that plasma miR-181b-5p levels were decreased, while Ang II and HMGB1 levels, as well as the intima-media thickness (IMT) were increased in hypertensive patients; these effects were reversed following the administration of angiotensin receptor blockers. Based on these observations, we conclude that the down-regulation of miR-181b-5p leads to the elevation of HMGB1 levels in hypertensive patients, which accounts, at least partially, for VSMCs phenotypic transformation and vascular remodeling. Our findings also highlight that the plasma levels of miR-181b-5p and HMGB1 may serve as novel biomarkers for vascular remodeling in the hypertensive patients.

Role of Noncoding RNAs in the Pathogenesis of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a local dilatation of the abdominal aortic vessel wall and is among the most challenging cardiovascular diseases as without urgent surgical intervention, ruptured AAA has a mortality rate of >80%. Most patients present acutely after aneurysm rupture or dissection from a previously asymptomatic condition and are managed by either surgery or endovascular repair. Patients usually are old and have other concurrent diseases and conditions, such as diabetes mellitus, obesity, and hypercholesterolemia making surgical intervention more difficult. Collectively, these issues have driven the search for alternative methods of diagnosing, monitoring, and treating AAA using therapeutics and less invasive approaches. Noncoding RNAs-short noncoding RNAs (microRNAs) and long-noncoding RNAs-are emerging as new fundamental regulators of gene expression. Researchers and clinicians are aiming at targeting these microRNAs and long noncoding RNAs and exploit their potential as clinical biomarkers and new therapeutic targets for AAAs. While the role of miRNAs in AAA is established, studies on long-noncoding RNAs are only beginning to emerge, suggesting their important yet unexplored role in vascular physiology and disease. Here, we review the role of noncoding RNAs and their target genes focusing on their role in AAA. We also discuss the animal models used for mechanistic understanding of AAA. Furthermore, we discuss the potential role of microRNAs and long noncoding RNAs as clinical biomarkers and therapeutics.

MicroRNA expression profile of HCT-8 cells in the early phase of Cryptosporidium parvum infection

Background

Cryptosporidium parvum is an important zoonotic parasitic disease worldwide, but the molecular mechanisms of the host–parasite interaction are not fully understood. Noncoding microRNAs (miRNAs) are considered key regulators of parasitic diseases. Therefore, we used microarray, qPCR, and bioinformatic analyses to investigate the intestinal epithelial miRNA expression profile after Cryptosporidium parvum infection.

Results

Twenty miRNAs were differentially expressed after infection (four upregulated and 16 downregulated). Further analysis of the differentially expressed miRNAs revealed that many important cellular responses were triggered by Cryptosporidium parvum infection, including cell apoptosis and the inflammatory and immune responses.

Conclusions

This study demonstrates for the first time that the miRNA expression profile of human intestinal epithelium cells is altered by C. parvum infection. This dysregulation of miRNA expression may contribute to the regulation of host biological processes in response to C. parvum infection, including cell apoptosis and the immune responses. These results provide new insight into the regulatory mechanisms of host miRNAs during cryptosporidiosis, which may offer potential targets for future C. parvum control strategies.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5410-6) contains supplementary material, which is available to authorized users.

Elucidating the contributory role of microRNA to cardiovascular diseases (a review)

Cardiovascular diseases encompassing atherosclerosis, aortic aneurysms, restenosis, and pulmonary arterial hypertension, remain the leading cause of morbidity and mortality worldwide. In response to a range of stimuli, the dynamic interplay between biochemical and biomechanical mechanisms affect the behaviour and function of multiple cell types, driving the development and progression of cardiovascular diseases. Accumulating evidence has highlighted microRNAs (miRs) as significant regulators and micro-managers of key cellular and molecular pathophysiological processes involved in predominant cardiovascular diseases, including cell mitosis, motility and viability, lipid metabolism, generation of inflammatory mediators, and dysregulated proteolysis. Human pathological and clinical studies have aimed to identify select microRNA which may serve as biomarkers of disease and their progression, which are discussed within this review. In addition, I provide comprehensive coverage of in vivo investigations elucidating the modulation of distinct microRNA on the pathophysiology of atherosclerosis, abdominal aortic aneurysms, restenosis, and pulmonary arterial hypertension. Collectively, clinical and animal studies have begun to unravel the complex and often diverse effects microRNAs and their targets impart during the development of cardiovascular diseases and revealed promising therapeutic strategies through which modulation of microRNA function may be applied clinically.

The regulatory role of microRNAs in angiogenesis-related diseases

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at a post-transcriptional level via either the degradation or translational repression of a target mRNA. They play an irreplaceable role in angiogenesis by regulating the proliferation, differentiation, apoptosis, migration and tube formation of angiogenesis-related cells, which are indispensable for multitudinous physiological and pathological processes, especially for the occurrence and development of vascular diseases. Imbalance between the regulation of miRNAs and angiogenesis may cause many diseases such as cancer, cardiovascular disease, aneurysm, Kawasaki disease, aortic dissection, phlebothrombosis and diabetic microvascular complication. Therefore, it is important to explore the essential role of miRNAs in angiogenesis, which might help to uncover new and effective therapeutic strategies for vascular diseases. This review focuses on the interactions between miRNAs and angiogenesis, and miRNA-based biomarkers in the diagnosis, treatment and prognosis of angiogenesis-related diseases, providing an update on the understanding of the clinical value of miRNAs in targeting angiogenesis.

MicroRNA‑26a protects vascular smooth muscle cells against H2O2‑induced injury through activation of the PTEN/AKT/mTOR pathway

Abdominal aortic aneurysm (AAA) is a common disease, which is characterized by the apoptosis of vascular smooth muscle cells (VSMCs). In previous years, microRNAs (miRNAs) have been associated with AAA and functionally implicated in the pathogenesis of this disease. However, the role of miRNAs in the apoptosis of VSMCs remains to be fully elucidated. The present study aimed to elucidate the role and mechanism of miRNAs in protecting against hydrogen peroxide (H₂O₂)-induced apoptosis in VSMCs. The expression of miRNAs in peripheral blood from patients diagnosed with AAA was analyzed using a microarray and reverse transcription polymerase chain reaction. A VSMC injury model induced by H₂O₂ was used to determine the potential role of miR-26a against cell injury. Cell viability, cell apoptosis and reactive oxygen species (ROS) generation were determined by a CCK8 assay, flow cytometry and a 2′,7′-DCF diacetate assay, respectively. It was observed that miRNA (miR)-26a (miR-26a-1-5p) was significantly downregulated in peripheral blood samples from patients with AAA. It was revealed that H₂O₂ treatment dose-dependently inhibited cell viability, enhanced apoptosis and induced the production of ROS, which indicated the success of the model establishment. It was also observed that miR-26a was downregulated in the VSMCs following H₂O₂ stimulation. The upregulation of miR-26a attenuated H₂O₂-induced cell injury, as evidenced by the enhancement of cell viability, and inhibition of the activity of caspase-3, apoptosis and ROS production. In addition, phosphatase and tensin homolog (PTEN), a well-known regulator of the AKT/mammalian target of rapamycin (mTOR) pathway, was found to be a direct target of miR-26a in the VSMCs and this was validated using a luciferase reporter assay. Overexpression of PTEN by pcDNA-PTEN plasmids markedly eliminated the protective effects of the overexpression of miR-26a on H₂O₂-induced cell injury. Finally, it was found that miR-26a mediated its anti-apoptotic action by reactivation of the AKT/mTOR pathway, as demonstrated by the upregulation of phosphorylated (p-)AKT and p-mTOR, and the Akt inhibitor API-2 reversing the protective effects on VSMCs mediated by miR-26a. These results indicated that miR-26a protected VSMCs against H₂O₂-induced injury through activation of the PTEN/AKT/mTOR pathway, and miR-26a may be considered as a potential prognostic biomarker and therapeutic target in the treatment of AAA.

The interaction of IGF-1/IGF-1R and hydrogen sulfide on the proliferation of mouse primary vascular smooth muscle cells

Hydrogen sulfide (H₂S) is mostly produced by cystathionine-gamma-lyase (CSE) in vascular system and it inhibits the proliferation of vascular smooth muscle cells (SMCs). Insulin-like growth factor-1 (IGF-1), via its receptor (IGF-1R), exerts multiple physiological and pathophysiological effects on the vasculature, including stimulating SMC proliferation and migration, and inhibiting SMC apoptosis. Since H₂S and IGF-1/IGF-1R have opposite effects on SMC proliferation, it becomes imperative to better understand the interaction of these two signaling mechanisms on SMC proliferation. SMCs isolated from small mesenteric arteries of CSE knockout (KO) and wild-type (WT) mice were used in the present study. The effects of IGF-1 and H₂S on SMC proliferation were evaluated with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and bromodeoxyuridine (BrdU) assays. Protein expression was determined by western blot, and H₂S-induced protein S-sulfhydration was assessed with a modified biotin switch assay. We found that IGF-1 dose-dependently increased the proliferation of both WT-SMCs and KO-SMCs, and this effect was more significant in KO-SMCs. Supplement of sodium hydrosulfide (NaHS) inhibited IGF-1-induced cell proliferation, while this effect was abolished by blocking IGF-1/IGF-1R signaling with picropodophyllin (PPP) or knocking out of the expression of IGF-1R. H₂S significantly down-regulates the expression of IGF-1R, stimulates IGF-1R S-sulfhydration, and attenuates the binding of IGF-1 with IGF-1R. This study provides novel insight on the involvement of IGF-1/IGF-1R in H₂S-inhibited SMC proliferation and suggests H₂S-based innovative treatment strategies for proliferative cardiovascular diseases such as atherosclerosis.

miRNA‑504 inhibits p53‑dependent vascular smooth muscle cell apoptosis and may prevent aneurysm formation

Abdominal aortic aneurysm (AAA) is a common disease that is associated with the proliferation and apoptosis of vascular smooth muscle cells (VSMCs). VSMCs are regulated by microRNAs (miRNA). The aim of the present study was to identify miRNA sequences that regulate aortic SMCs during AAA. miRNA-504 was identified using a miRNA PCR array and by reverse transcription-quantitative polymerase chain reaction analysis, and its expression levels were observed to be downregulated in the aortic cells derived from patients with AAA when compared with controls. Transfection of SMCs with pMSCV-miRNA-504 vector was performed, and cell proliferation and the expression levels of proliferating cell nuclear antigen (PCNA), replication factor C subunit 4 (RFC4), B-cell lymphoma-2 (Bcl-2) and caspase-3/9 were measured by western blotting. The mechanisms underlying the effects of miRNA-504 was then analyzed. The results demonstrated that overexpression of miRNA-504 significantly upregulated the expression levels of PCNA, RFC4 and Bcl-2, while caspase-3/9 expression was significantly inhibited when compared with non-targeting controls. In addition, miRNA-504 overexpression was observed to promote the proliferation of SMCs. The expression level of the tumor suppressor, p53, which is known to be a direct target of miRNA-504, was inhibited following transfection of SMCs with pMSCV-miRNA-504. In addition, the expression of the downstream targets of p53, p21 and Bcl-like protein-4, were significantly reduced following overexpression of miRNA-504. These results revealed the anti-apoptotic role of miRNA-504 in SMCs derived from patients with AAA via direct targeting of p53.

Aneurysm-Specific miR-221 and miR-146a Participates in Human Thoracic and Abdominal Aortic Aneurysms

Altered microRNA expression is implicated in cardiovascular diseases. Our objective was to determine microRNA signatures in thoracic aortic aneurysms (TAAs) and abdominal aortic aneurysms (AAAs) compared with control non-aneurysmal aortic specimens. We evaluated the expression of fifteen selected microRNA in human TAA and AAA operative specimens compared to controls. We observed significant upregulation of miR-221 and downregulation of miR-1 and -133 in TAA specimens. In contrast, upregulation of miR-146a and downregulation of miR-145 and -331-3p were found only for AAA specimens. Upregulation of miR-126 and -486-5p and downregulation of miR-30c-2*, -155, and -204 were observed in specimens of TAAs and AAAs. The data reveal microRNA expression signatures unique to aneurysm location and common to both thoracic and abdominal pathologies. Thus, changes in miR-1, -29a, -133a, and -221 are involved in TAAs and miR-145, -146, and -331-3p impact AAAs. This work validates prior studies on microRNA expression in aneurysmal diseases.

Circulating microRNAs signature correlates with positive [18F]fluorodeoxyglucose-positron emission tomography in patients with abdominal aortic aneurysm

BACKGROUND

Prediction of abdominal aortic aneurysm (AAA) rupture is a challenging issue. Small noncoding microRNAs (miRNAs) are potent regulators of gene expression and are considered as valuable circulating biomarkers. Recently, [¹⁸F]fluorodeoxyglucose (FDG) uptake detected by positron emission tomography (PET) in AAA was correlated with cellular and molecular alterations involved in wall instability and its potential rupture. Our study aimed at identifying circulating miRNAs correlated with a positive PET that could help discriminate patients at high risk of rupture.

METHODS

The level of 372 miRNAs was evaluated by polymerase chain reaction array in plasma from 35 AAA patients displaying no FDG uptake (A0) and 22 patients with a positive PET uptake (A+). The modulated miRNAs were validated by quantitative polymerase chain reaction and measured in aneurysmal tissues from both groups of patients.

RESULTS

Six circulating miRNAs were found significantly modulated in A+ vs A0 patients. They were significantly correlated not only between them but also with the intensity of FDG uptake. Two of them correlated also with the AAA diameter. These miRNAs displayed significant discriminating power between the A+ and A0 groups as determined by receiver operating characteristic curves. Three downregulated circulating miRNAs (miR-99b-5p, miR-125b-5p, and miR-204-5p) were also significantly reduced in the aneurysmal tissue, specifically in the FDG-uptake site, compared with a negative zone in the same aneurysm and with A0 aneurysms. They were further significantly inversely correlated with the expression, at the positive uptake site, of some of their potential gene targets, most notably matrix metalloproteinase 13.

CONCLUSIONS

Six miRNAs were identified as potential new circulating biomarkers of PET+ AAA. Three of these were similarly modulated in the metabolically active aneurysmal wall and might be directly involved in AAA instability.

Abdominal Aortic Aneurysm-Associated MicroRNA-516a-5p Regulates Expressions of Methylenetetrahydrofolate Reductase, Matrix Metalloproteinase-2, and Tissue Inhibitor of Matrix Metalloproteinase-1 in Human Abdominal Aortic Vascular Smooth Muscle Cells

BACKGROUND

MicroRNAs (miRNAs or miRs) have been highlighted to be involved in abdominal aortic aneurysm (AAA) with the emergence of recent miRNA microarray profiling studies. miR-516a-5p has been shown to be significantly overexpressed in vascular smooth muscle cells (VSMCs) from human AAA tissues from our previous microarray study, suggesting its crucial association with AAA. In addition, further bioinformatics analysis predicted methylenetetrahydrofolate reductase (MTHFR), which regulates homocysteine (Hcy) metabolism and is proposed to be a risk gene for AAA formation and to be the downregulation target of miR-516a-5p. However, the pathogenic role of miR-516a-5p in VSMCs for AAA formation remains unresolved. This study aims to investigate the role of miR-516a-5p in human VSMCs for AAA pathogenesis.

METHODS

miR-516a-5p was stably overexpressed and knocked down in VSMCs explant cultured from human abdominal aortic tissues by means of lentiviral system. The MTHFR protein expression was first examined by Western blotting. In addition, the protein expressions of several key components involved in AAA pathogenic features are as follows: matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and TIMP-2 for elastin degradation; collagen type 1 alpha 1 for compensatory collagen synthesis; monocyte chemoattractant protein-1 for inflammation, were also evaluated. Apoptotic level of VSMCs was examined by terminal deoxynucleotidyl transferase dUTP nick end labeling assay.

RESULTS

Results showed that protein expression of MTHFR was significantly downregulated on miR-516a-5p overexpression (P < 0.05) in VSMCs, whereas it was significantly upregulated on miR-516a-5p knockdown (P < 0.05). Of all the AAA key components investigated, only MMP-2 and TIMP-1 protein expressions were found altered. A significant increase in MMP-2 (P < 0.05) and decrease in TIMP-1 (P < 0.05) expressions were observed on miR-516a-5p overexpression in VSMCs. Apoptosis was not promoted on miR-516a-5p overexpression or knockdown in VSMCs.

CONCLUSIONS

Our findings suggested that miR-516a-5p may regulate MTHFR, MMP-2, and TIMP-1 expressions in human VSMCs, possibly promoting the disruption of Hcy metabolism and proteolytic degradation of elastin for AAA formation.

Genetic and Epigenetic Regulation of Aortic Aneurysms

Aneurysms are characterized by structural deterioration of the vascular wall leading to progressive dilatation and, potentially, rupture of the aorta. While aortic aneurysms often remain clinically silent, the morbidity and mortality associated with aneurysm expansion and rupture are considerable. Over 13,000 deaths annually in the United States are attributable to aortic aneurysm rupture with less than 1 in 3 persons with aortic aneurysm rupture surviving to surgical intervention. Environmental and epidemiologic risk factors including smoking, male gender, hypertension, older age, dyslipidemia, atherosclerosis, and family history are highly associated with abdominal aortic aneurysms, while heritable genetic mutations are commonly associated with aneurysms of the thoracic aorta. Similar to other forms of cardiovascular disease, family history, genetic variation, and heritable mutations modify the risk of aortic aneurysm formation and provide mechanistic insight into the pathogenesis of human aortic aneurysms. This review will examine the relationship between heritable genetic and epigenetic influences on thoracic and abdominal aortic aneurysm formation and rupture.

MicroRNA-129-5p inhibits vascular smooth muscle cell proliferation by targeting Wnt5a

Aberrant smooth muscle cells (SMCs) play important roles in the formation of abdominal aortic aneurysm (AAA). Although the molecular mechanism of AAA formation has been investigated, there is a lack of understanding concerning the role of microRNAs (miRNAs) in AAA, which the current study aimed to address. Firstly, miRNA array analysis was performed in order to compare the miRNA profiles in a mouse model of AAA with those in normal control mice, and differentially expressed miRNAs were identified. miR-129-5p was selected for further analysis, and was used to transfect human SMCs. The results of an MTT assay revealed that miR-129-5p inhibited the proliferation of SMCs, and flow cytometry indicated that apoptosis was induced. Bioinformatic analysis predicted that Wnt5a was the potential target gene of miR-129-5p, and this was verified by luciferase assay. In summary, miR-129-5p inhibits cellular proliferation, induces apoptosis and modulates the Wnt5a signaling pathway in SMCs.

Epigenetics and Peripheral Artery Disease

The term epigenetics is usually used to describe inheritable changes in gene function which do not involve changes in the DNA sequence. These typically include non-coding RNAs, DNA methylation and histone modifications. Smoking and older age are recognised risk factors for peripheral artery diseases, such as occlusive lower limb artery disease and abdominal aortic aneurysm, and have been implicated in promoting epigenetic changes. This brief review describes studies that have associated epigenetic factors with peripheral artery diseases and investigations which have examined the effect of epigenetic modifications on the outcome of peripheral artery diseases in mouse models. Investigations have largely focused on microRNAs and have identified a number of circulating microRNAs associated with human peripheral artery diseases. Upregulating or antagonising a number of microRNAs has also been reported to limit aortic aneurysm development and hind limb ischemia in mouse models. The importance of DNA methylation and histone modifications in peripheral artery disease has been relatively little studied. Whether circulating microRNAs can be used to assist identification of patients with peripheral artery diseases and be modified in order to improve the outcome of peripheral artery disease will require further investigation.

Micro-RNAs in abdominal aortic aneurysms: insights from animal models and relevance to human disease

Abdominal aortic aneurysm (AAA) is a major health concern and may be associated with high rates of mortality linked to acute complications. Diagnosis and treatment are, respectively, based on imaging and surgical techniques. Drug-based therapies are still mostly ineffective, which highlight a real unmet need. Major pathophysiological mechanisms leading to aneurysm formation involve inflammatory processes, degradation of the extracellular matrix, and loss of smooth muscle cells. However, the precise cellular and molecular pathways are still poorly understood. Recently, microRNAs have emerged as major intracellular players in a wide range of biological processes, and their stability in extracellular medium within microvesicles has led to propose them as mediators of intercellular crosstalk and as potential biomarkers and therapeutic targets in a variety of disease settings. To date, several studies have been performed to address the involvement of micro-RNAs (miRs) in aneurysm formation and complications. Here, we discuss the roles and implications of miRs in animal models and their relevance to human AAA.

Understanding the pathogenesis of abdominal aortic aneurysms

An aortic aneurysm is a dilatation in which the aortic diameter is ≥3.0 cm. If left untreated, the aortic wall continues to weaken and becomes unable to withstand the forces of the luminal blood pressure resulting in progressive dilatation and rupture, a catastrophic event associated with a mortality of 50-80%. Smoking and positive family history are important risk factors for the development of abdominal aortic aneurysms (AAA). Several genetic risk factors have also been identified. On the histological level, visible hallmarks of AAA pathogenesis include inflammation, smooth muscle cell apoptosis, extracellular matrix degradation and oxidative stress. We expect that large genetic, genomic, epigenetic, proteomic and metabolomic studies will be undertaken by international consortia to identify additional risk factors and biomarkers, and to enhance our understanding of the pathobiology of AAA. Collaboration between different research groups will be important in overcoming the challenges to develop pharmacological treatments for AAA.

Aneurysm miRNA Signature Differs, Depending on Disease Localization and Morphology

Limited comprehension of aneurysm pathology has led to inconclusive results from clinical trials. miRNAs are key regulators of post-translational gene modification and are useful tools in elucidating key features of aneurysm pathogenesis in distinct entities of abdominal and popliteal aneurysms. Here, surgically harvested specimens from 19 abdominal aortic aneurysm (AAA) and 8 popliteal artery aneurysm (PAA) patients were analyzed for miRNA expression and histologically classified regarding extracellular matrix (ECM) remodeling and inflammation. DIANA-based computational target prediction and pathway enrichment analysis verified our results, as well as previous ones. miRNA-362, -19b-1, -194, -769, -21 and -550 were significantly down-regulated in AAA samples depending on degree of inflammation. Similar or inverse regulation was found for miR-769, 19b-1 and miR-550, -21, whereas miR-194 and -362 were unaltered in PAA. In situ hybridization verified higher expression of miR-550 and -21 in PAA compared to AAA and computational analysis for target genes and pathway enrichment affirmed signal transduction, cell-cell-interaction and cell degradation pathways, in line with previous results. Despite the vague role of miRNAs for potential diagnostic and treatment purposes, the number of candidates from tissue signature studies is increasing. Tissue morphology influences subsequent research, yet comparison of distinct entities of aneurysm disease can unravel core pathways.

miR-146b-5p promotes VSMC proliferation and migration

Vascular smooth muscle cells (VSMCs) play pivotal roles in the development of vascular diseases. While microRNAs are important in vascular pathologies, a few is known about their functional roles in VSMC phenotypes. We profiled microRNA expression in PDGF-BB treated VSMCs and found microRNA-146b-5p (miR-146b-5p) was upregulated. Inhibition of miR-146b-5p blocked in response to PDGF while reducing VSMC proliferation and migration. These studies implicate miR-146b-5p as necessary for PDGF-induced VSMC phenotype transition. Downstream miR-146b-5p targets modulating VSMC phenotypes will be further identified. Our study will help to understand the role of VSMCs in the pathology of vascular diseases.

MicroRNAs: Novel Players in Aortic Aneurysm

An aortic aneurysm (AA) is a common disease with potentially life-threatening complications. Despite significant improvements in the diagnosis and treatment of AA, the associated morbidity and mortality remain high. MicroRNAs (miRNAs, miR) are small noncoding ribonucleic acids that negatively regulate gene expression at the posttranscriptional level by inhibiting mRNA translation or promoting mRNA degradation. miRNAs are recently reported to be critical modulators for vascular cell functions such as cell migration, contraction, differentiation, proliferation, and apoptosis. Increasing evidences suggest crucial roles of miRNAs in the pathogenesis and progression of cardiovascular diseases such as coronary artery disease, heart failure, arterial hypertension, and cardiac arrhythmias. Recently, some miRNAs, such as miR-24, miR-155, miR-205, miR-712, miR-21, miR-26a, miR-143/145, miR-29, and miR-195, have been demonstrated to be differentially expressed in the diseased aortic tissues and strongly associated with the development of AA. In the present paper, we reviewed the recent available literature regarding the role of miRNAs in the pathogenesis of AA. Moreover, we discuss the potential use of miRNAs as diagnostic and prognostic biomarkers and novel targets for development of effective therapeutic strategies for AA.

Immunohistochemical analysis of the natural killer cell cytotoxicity pathway in human abdominal aortic aneurysms

Our previous analysis using genome-wide microarray expression data revealed extreme overrepresentation of immune related genes belonging the Natural Killer (NK) Cell Mediated Cytotoxicity pathway (hsa04650) in human abdominal aortic aneurysm (AAA). We followed up the microarray studies by immunohistochemical analyses using antibodies against nine members of the NK pathway (VAV1, VAV3, PLCG1, PLCG2, HCST, TYROBP, PTK2B, TNFA, and GZMB) and aortic tissue samples from AAA repair operations (n = 6) and control aortae (n = 8) from age-, sex- and ethnicity-matched donors from autopsies. The results confirmed the microarray results. Two different members of the NK pathway, HCST and GRZB, which act at different steps in the NK-pathway, were actively transcribed and translated into proteins in the same cells in the AAA tissue demonstrated by double staining. Furthermore, double staining with antibodies against CD68 or CD8 together with HCST, TYROBP, PTK2B or PLCG2 revealed that CD68 and CD8 positive cells expressed proteins of the NK-pathway but were not the only inflammatory cells involved in the NK-pathway in the AAA tissue. The results provide strong evidence that the NK Cell Mediated Cytotoxicity Pathway is activated in human AAA and valuable insight for future studies to dissect the pathogenesis of human AAA.

Transcriptional (ChIP-Chip) Analysis of ELF1, ETS2, RUNX1 and STAT5 in Human Abdominal Aortic Aneurysm

We investigated transcriptional control of gene expression in human abdominal aortic aneurysm (AAA). We previously identified 3274 differentially expressed genes in human AAA tissue compared to non-aneurysmal controls. Four expressed transcription factors (ELF1, ETS2, STAT5 and RUNX1) were selected for genome-wide chromatin immunoprecipitation. Transcription factor binding was enriched in 4760 distinct genes (FDR < 0.05), of which 713 were differentially expressed in AAA. Functional classification using Gene Ontology (GO), KEGG, and Network Analysis revealed enrichment in several biological processes including “leukocyte migration” (FDR = 3.09 × 10⁻⁰⁵) and “intracellular protein kinase cascade” (FDR = 6.48 × 10⁻⁰⁵). In the control aorta, the most significant GO categories differed from those in the AAA samples and included “cytoskeleton organization” (FDR = 1.24 × 10⁻⁰⁶) and “small GTPase mediated signal transduction” (FDR = 1.24 × 10⁻⁰⁶). Genes up-regulated in AAA tissue showed a highly significant enrichment for GO categories “leukocyte migration” (FDR = 1.62 × 10⁻¹¹), “activation of immune response” (FDR = 8.44 × 10⁻¹¹), “T cell activation” (FDR = 4.14 × 10⁻¹⁰) and “regulation of lymphocyte activation” (FDR = 2.45 × 10⁻⁰⁹), whereas the down-regulated genes were enriched in GO categories “cytoskeleton organization” (FDR = 7.84 × 10⁻⁰⁵), “muscle cell development” (FDR = 1.00 × 10⁻⁰⁴), and “organ morphogenesis” (FDR = 3.00 × 10⁻⁰⁴). Quantitative PCR assays confirmed a sub-set of the transcription factor binding sites including those in MTMR11, DUSP10, ITGAM, MARCH1, HDAC8, MMP14, MAGI1, THBD and SPOCK1.

Adventitial Tertiary Lymphoid Organs as Potential Source of MicroRNA Biomarkers for Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is an inflammatory disease associated with marked changes in the cellular composition of the aortic wall. This study aims to identify microRNA (miRNA) expression in aneurysmal inflammatory cells isolated by laser microdissection from human tissue samples. The distribution of inflammatory cells (neutrophils, B and T lymphocytes, mast cells) was evaluated in human AAA biopsies. We observed in half of the samples that adventitial tertiary lymphoid organs (ATLOs) with a thickness from 0.5 to 2 mm were located exclusively in the adventitia. Out of the 850 miRNA that were screened by microarray in isolated ATLOs (n = 2), 164 miRNAs were detected in ATLOs. The three miRNAs (miR-15a-3p, miR-30a-5p and miR-489-3p) with the highest expression levels were chosen and their expression quantified by RT-PCR in isolated ATLOs (n = 4), M1 (n = 2) and M2 macrophages (n = 2) and entire aneurysmal biopsies (n = 3). Except for the miR-30a-5p, a similar modulation was found in ATLOs and the two subtypes of macrophages. The modulated miRNAs were then evaluated in the plasma of AAA patients for their potential as AAA biomarkers. Our data emphasize the potential of miR-15a-3p and miR-30a-5p as biomarkers of AAA but also as triggers of ATLO evolution. Further investigations will be required to evaluate their targets in order to better understand AAA pathophysiology.

The potential role of DNA methylation in abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is a complex disorder that has a significant impact on the aging population. While both genetic and environmental risk factors have been implicated in AAA formation, the precise genetic markers involved and the factors influencing their expression remain an area of ongoing investigation. DNA methylation has been previously used to study gene silencing in other inflammatory disorders and since AAA has an extensive inflammatory component, we sought to examine the genome-wide DNA methylation profiles in mononuclear blood cells of AAA cases and matched non-AAA controls. To this end, we collected blood samples and isolated mononuclear cells for DNA and RNA extraction from four all male groups: AAA smokers (n = 11), AAA non-smokers (n = 9), control smokers (n = 10) and control non-smokers (n = 11). Methylation data were obtained using the Illumina 450k Human Methylation Bead Chip and analyzed using the R language and multiple Bioconductor packages. Principal component analysis and linear analysis of CpG island subsets identified four regions with significant differences in methylation with respect to AAA: kelch-like family member 35 (KLHL35), calponin 2 (CNN2), serpin peptidase inhibitor clade B (ovalbumin) member 9 (SERPINB9), and adenylate cyclase 10 pseudogene 1 (ADCY10P1). Follow-up studies included RT-PCR and immunostaining for CNN2 and SERPINB9. These findings are novel and suggest DNA methylation may play a role in AAA pathobiology.

Identification of microRNAs associated with abdominal aortic aneurysms and peripheral arterial disease

BACKGROUND

MicroRNAs are crucial in the regulation of cardiovascular disease and represent potential therapeutic targets to decrease abdominal aortic aneurysm (AAA) expansion. The aim of this study was to identify circulating microRNAs associated with AAA.

METHODS

Some 754 microRNAs in whole-blood samples from 15 men with an AAA and ten control subjects were quantified using quantitative reverse transcriptase-PCR. MicroRNAs demonstrating a significant association with AAA were validated in peripheral blood and plasma samples of men in the following groups (40 in each): healthy controls, controls with peripheral arterial disease (PAD), men with a small AAA (30-54 mm), those with a large AAA (over 54 mm), and those following AAA repair. MicroRNA expression was also assessed in aortic tissue.

RESULTS

Twenty-nine differentially expressed microRNAs were identified in the discovery study. Validation study revealed that let-7e (fold change (FC) -1·80; P = 0·001), miR-15a (FC -2·24; P < 0·001) and miR-196b (FC -2·26; P < 0·001) were downregulated in peripheral blood from patients with an AAA, and miR-411 was upregulated (FC 5·90; P = 0·001). miR-196b was also downregulated in plasma from the same individuals (FC -3·75; P = 0·029). The same miRNAs were similarly expressed differentially in patients with PAD compared with healthy controls. Validated and predicted microRNA targets identified through miRWalk revealed that these miRNAs were all regulators of AAA-related genes (vascular cell adhesion molecule 1, intercellular cell adhesion molecule 1, DAB2 interacting protein, α1-antitrypsin, C-reactive protein, interleukin 6, osteoprotegerin, methylenetetrahydrofolate reductase, tumour necrosis factor α).

CONCLUSION

In this study, circulating levels of let-7e, miR-15a, miR-196b and miR-411 were differentially expressed in men with an AAA compared with healthy controls, but also differentially expressed in men with PAD. Modulation of these miRNAs and their target genes may represent a new therapeutic pathway to affect the progression of AAA and atherosclerosis.

Exploring the association between interleukin-1β and its interacting proteins in Alzheimer's disease

Alzheimer’s disease (AD) is an age-associated progressive neurodegenerative disorder which is of clinical concern. The association between the nervous and immune system is defined as an neuroimmunological theory that supports a model of pathology or treatment for AD. Interleukin (IL)-1β has a pro-inflammatory function in AD; however, the mechanism of its dysregulation in AD remains unknown. It is therefore of significance to understand the molecular mechanisms of IL-1β and how it may regulate AD. Proteins, which have been previously reported to be associated with IL-1β in AD, have been used in the present study as nodes to illustrate a net of protein interaction in Cytoscape. The Kyoto Encyclopedia of Genes and Genomes was used to further analyze the association of these proteins with the pathology of AD. The present study identified and subsequently compared two AD and six IL-1β pathways with the network produced in Cytoscape. The present study identified important mechanisms in the pathology of AD and constructed two novel networks using Cytoscape.

Genome-wide microRNA changes in human intracranial aneurysms

Background

Intracranial aneurysms are pathological dilatations of the cerebral artery, while rupture of intracranial aneurysms causes life-threatening subarachnoid hemorrhage. The molecular mechanisms of pathogenesis of intracranial aneurysms are poorly understood. MicroRNAs have fundamental roles in modulating vascular biology and disease. In the present study, we carried out a genome-wide characterization on expressions of microRNAs, and performed integrative analyses in conjunction with changes of the transcriptome in human intracranial aneurysms.

Methods

Genome-wide microRNA screening was performed in 6 intracranial aneurysmal samples and 6 normal superficial temporal arteries. Each case and control pair was individually matched with gender, age (±5 years), and high blood pressure history. Microarray analysis was performed using Agilent Human miRNA arrays.

Results

As compared to normal arteries, we identified 157 microRNAs that were differentially expressed in the aneurysmal tissue (P < 0.05 and fold change ≥ 2), including 72 upregulated and 85 downregulated. The changed microRNAs included endothelium-enriched microRNAs such as members of the let-7 family, miR-17, miR-23b, miR-126, hsa-miR-24-1 and miR-222, and vascular smooth muscle-enriched miRNAs such as miR-143 and miR-145. Moreover, miR-1, miR-10a, miR-125b, and miR-26a, which were implicated in modulating vascular smooth muscle cell functions such as proliferation, apoptosis and shift of phenotype, were also changed. In contrast, microRNAs involved in monocyte and macrophage functions, such as miR-155, miR-146a, miR-223, and miR-124a, were not significantly changed. Bioinformatic analysis revealed that the changed microRNAs were associated with several biological processes related to aneurysm formation, including inflammation, dysregulation of extracellular matrix, smooth muscle cell proliferation, programmed cell death, and response to oxidative stress. Interestingly, we found that a subset of the potential microRNA target genes belonged to the protein translation machinery, including various eukaryotic translation initiation factors and ribosomal proteins, and this finding was highly correlated with our previous transcriptome data showing that multiple genes of the ribosomal proteins and translation initiation and elongation factors were significantly downregulated in human intracranial aneurysms.

Conclusions

Our results support that dysregulated microRNAs may have a pathogenic role in intracranial aneurysms. Disruption of the protein translation process may have a pathogenic role in the development of intracranial aneurysms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-014-0188-x) contains supplementary material, which is available to authorized users.