The Wnt pathways in vascular disease: lessons from vascular development

The evolving roles of Wnt signaling in stem cell proliferation and differentiation, the development of human diseases, and therapeutic opportunities

The evolutionarily conserved Wnt signaling pathway plays a central role in development and adult tissue homeostasis across species. Wnt proteins are secreted, lipid-modified signaling molecules that activate the canonical (β-catenin dependent) and non-canonical (β-catenin independent) Wnt signaling pathways. Cellular behaviors such as proliferation, differentiation, maturation, and proper body-axis specification are carried out by the canonical pathway, which is the best characterized of the known Wnt signaling paths. Wnt signaling has emerged as an important factor in stem cell biology and is known to affect the self-renewal of stem cells in various tissues. This includes but is not limited to embryonic, hematopoietic, mesenchymal, gut, neural, and epidermal stem cells. Wnt signaling has also been implicated in tumor cells that exhibit stem cell-like properties. Wnt signaling is crucial for bone formation and presents a potential target for the development of therapeutics for bone disorders. Not surprisingly, aberrant Wnt signaling is also associated with a wide variety of diseases, including cancer. Mutations of Wnt pathway members in cancer can lead to unchecked cell proliferation, epithelial-mesenchymal transition, and metastasis. Altogether, advances in the understanding of dysregulated Wnt signaling in disease have paved the way for the development of novel therapeutics that target components of the Wnt pathway. Beginning with a brief overview of the mechanisms of canonical and non-canonical Wnt, this review aims to summarize the current knowledge of Wnt signaling in stem cells, aberrations to the Wnt pathway associated with diseases, and novel therapeutics targeting the Wnt pathway in preclinical and clinical studies.

Endothelial Dysfunction in Cardiorenal Conditions: Implications of Endothelial Glucocorticoid Receptor-Wnt Signaling

The endothelium constitutes the innermost lining of the blood vessels and controls blood fluidity, vessel permeability, platelet aggregation, and vascular tone. Endothelial dysfunction plays a key role in initiating a vascular inflammatory cascade and is the pivotal cause of various devastating diseases in multiple organs including the heart, lung, kidney, and brain. Glucocorticoids have traditionally been used to combat vascular inflammation. Endothelial cells express glucocorticoid receptors (GRs), and recent studies have demonstrated that endothelial GR negatively regulates vascular inflammation in different pathological conditions such as sepsis, diabetes, and atherosclerosis. Mechanistically, the anti-inflammatory effects of GR are mediated, in part, through the suppression of Wnt signaling. Moreover, GR modulates the fatty acid oxidation (FAO) pathway in endothelial cells and hence can influence FAO-mediated fibrosis in several organs including the kidneys. This review summarizes the relationship between GR and Wnt signaling in endothelial cells and the effects of the Wnt pathway in different cardiac and renal diseases. Available data suggest that GR plays a significant role in restoring endothelial integrity, and research on endothelial GR-Wnt interactions could facilitate the development of novel therapies for many cardiorenal conditions.

Assessing the Association between Psoriasis and Cardiovascular Ischemia: An Investigation of Vascular Endothelial Growth Factor, Cutaneous Angiogenesis, and Arterial Stiffness

Background

Vascular endothelial growth factor (VEGF)-mediated angiogenesis's role in developing psoriasis and cardiovascular events has been established. However, the interplay between the two diseases regarding this cytokine remains an understudied area.

Aim and Objectives

This case-control study aimed to investigate the relationship between VEGF-mediated angiogenesis and cardiovascular ischemia in patients with psoriasis.

Materials and Methods

The study included 200 clinically diagnosed treatment-naïve cases of psoriasis and 200 controls. The VEGF level, cutaneous vascularity, and cardiovascular ischemia were measured between cases and controls. Cutaneous vascularity was assessed using non-invasive imaging technique such as laser doppler imaging (LDI) and measuring skin blood flow measurement (SBFM). Cardiovascular ischemia was evaluated using noninvasive techniques by measuring carotid intima-media thickness (CIMT) and pulse-wave velocity (PWV). The arterial vasa vasorum was evaluated using ultrasound imaging.

Results

The study found a significant correlation between psoriasis severity and levels of VEGF (P < 0.001). Cases had significantly higher CIMT and PWV levels (P = 0.001 and <0.001, respectively). There was a significant positive correlation between the severity of psoriasis and the levels of cutaneous angiogenesis (r = 0.7, P < 0.001).

Conclusion

According to this study, patients with psoriasis are at a higher risk of developing cardiovascular ischemia due to excessive angiogenesis associated with the condition. VEGF plays a key role in atheroma formation in psoriasis patients.

Roles of Vascular Smooth Muscle Cells in Atherosclerotic Calcification

The accumulation of calcium in atherosclerotic plaques is a prominent feature of advanced atherosclerosis, and it has a strong positive correlation with the total burden of atherosclerosis. Atherosclerotic calcification usually appears first at the necrotic core, indicating that cell death and inflammatory processes are involved in calcification. During atherosclerotic inflammation, various cell types, such as vascular smooth muscle cells, nascent resident pericytes, circulating stem cells, or adventitial cells, have been assumed to differentiate into osteoblastic cells, which lead to vascular calcification. Among these cell types, vascular smooth muscle cells are considered a major contributor to osteochondrogenic cells in the atherosclerotic milieu. In this review, we summarize the molecular mechanisms underlying the osteochondrogenic switch of vascular smooth muscle cells in atherosclerotic plaques.

TCF7L1 Accelerates Smooth Muscle Cell Phenotypic Switching and Aggravates Abdominal Aortic Aneurysms

Phenotypic switching of vascular smooth muscle cells is a central process in abdominal aortic aneurysm (AAA) pathology. We found that knockdown TCF7L1 (transcription factor 7-like 1), a member of the TCF/LEF (T cell factor/lymphoid enhancer factor) family of transcription factors, inhibits vascular smooth muscle cell differentiation. This study hints at potential interventions to maintain a normal, differentiated smooth muscle cell state, thereby eliminating the pathogenesis of AAA. In addition, our study provides insights into the potential use of TCF7L1 as a biomarker for AAA.

Non-canonical WNT signalling in cardiovascular disease: mechanisms and therapeutic implications

WNT signalling comprises a diverse spectrum of receptor-mediated pathways activated by a large family of WNT ligands and influencing fundamental biological processes. WNT signalling includes the β-catenin canonical pathway and the non-canonical pathways, namely the planar cell polarity and the calcium-dependent pathways. Advances over the past decade have linked non-canonical WNT signalling with key mechanisms of atherosclerosis, including oxidative stress, endothelial dysfunction, macrophage activation and vascular smooth muscle cell phenotype regulation. In addition, non-canonical WNT signalling is involved in crucial aspects of myocardial biology, from fibrosis to hypertrophy and oxidative stress. Importantly, non-canonical WNT signalling activation has complex effects in adipose tissue in the context of obesity, thereby potentially linking metabolic and vascular diseases. Tissue-specific targeting of non-canonical WNT signalling might be associated with substantial risks of off-target tumorigenesis, challenging its therapeutic potential. However, novel technologies, such as monoclonal antibodies, recombinant decoy receptors, tissue-specific gene silencing with small interfering RNAs and gene editing with CRISPR-Cas9, might enable more efficient therapeutic targeting of WNT signalling in the cardiovascular system. In this Review, we summarize the components of non-canonical WNT signalling, their links with the main mechanisms of atherosclerosis, heart failure and arrhythmias, and the rationale for targeting individual components of non-canonical WNT signalling for the treatment of cardiovascular disease.

Arterial Stiffness and the Canonical WNT/β-catenin Pathway

PURPOSE OF REVIEW

Arterial stiffness (AS) was mainly associated with cardiovascular morbidity and mortality in a hypertensive patient. Some risk factors contribute to the development of AS, such as aging, high blood pressure, vascular calcification, inflammation, and diabetes mellitus. The WNT/β-catenin pathway is implicated in numerous signaling and regulating pathways, including embryogenesis, cell proliferation, migration and polarity, apoptosis, and organogenesis. The activation of the WNT/β-catenin pathway is associated with the development of these risk factors.

RECENT FINDINGS

Aortic pulse wave velocity (PWV) is measured to determine AS, and in peripheral artery disease patients, PWV is higher than controls. An augmentation in PWV by 1 m/s has been shown to increase the risk of cardiovascular events by 14%. AS measured by PWV is characterized by the deregulation of the WNT/β-catenin pathway by the inactivation of its two inhibitors, i.e., DKK1 and sclerostin. Thus, this review focuses on the role of the WNT/β-catenin pathway which contributes to the development of arterial stiffness.

Caffeine prevents restenosis and inhibits vascular smooth muscle cell proliferation through the induction of autophagy

Caffeine is among the most highly consumed substances worldwide, and it has been associated with decreased cardiovascular risk. Although caffeine has been shown to inhibit the proliferation of vascular smooth muscle cells (VSMCs), the mechanism underlying this effect is unknown. Here, we demonstrated that caffeine decreased VSMC proliferation and induced macroautophagy/autophagy in an in vivo vascular injury model of restenosis. Furthermore, we studied the effects of caffeine in primary human and mouse aortic VSMCs and immortalized mouse aortic VSMCs. Caffeine decreased cell proliferation, and induced autophagy flux via inhibition of MTOR signaling in these cells. Genetic deletion of the key autophagy gene Atg5, and the Sqstm1/p62 gene encoding a receptor protein, showed that the anti-proliferative effect by caffeine was dependent upon autophagy. Interestingly, caffeine also decreased WNT-signaling and the expression of two WNT target genes, Axin2 and Ccnd1 (cyclin D1). This effect was mediated by autophagic degradation of a key member of the WNT signaling cascade, DVL2, by caffeine to decrease WNT signaling and cell proliferation. SQSTM1/p62, MAP1LC3B-II and DVL2 were also shown to interact with each other, and the overexpression of DVL2 counteracted the inhibition of cell proliferation by caffeine. Taken together, our in vivo and in vitro findings demonstrated that caffeine reduced VSMC proliferation by inhibiting WNT signaling via stimulation of autophagy, thus reducing the vascular restenosis. Our findings suggest that caffeine and other autophagy-inducing drugs may represent novel cardiovascular therapeutic tools to protect against restenosis after angioplasty and/or stent placement.

Exploration of the Crucial Genes and Molecular Mechanisms Mediating Atherosclerosis and Abnormal Endothelial Shear Stress

Background

Abnormal endothelial shear stress (ESS) is a significant risk factor for atherosclerosis (AS); however, the genes and pathways between ESS and AS are poorly understood. Here, we screened hub genes and potential regulatory targets linked to the progression of AS induced by abnormal ESS.

Methods

The microarray data of ESS and AS were downloaded from the Gene Expression Omnibus (GEO) database. The coexpression modules related to shear stress and AS were identified with weighted gene coexpression network analysis (WGCNA). Coexpression genes in modules obtained from GSE28829 and GSE160611 were considered as SET1. The results were validated in validation set by differential gene analysis. The limma package in R was used to identify differentially expressed genes (DEGs). The common DEGs of GSE100927 and GSE103672 were regarded as SET2. Next, Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was conducted. Protein-protein interaction (PPI) enrichment analysis was assembled, and hub genes were identified using MCODE and ClueGO in Cytoscape. ROC curve analyses were conducted to assess the ability of common hub genes to distinguish samples of atherosclerotic plaque from normal arterial. The expression of common hub gene was verified in ox-LDL-induced foam cells and GSE41571.

Results

We identified three gene modules (the blue, tan, and cyan modules) related to AS and three shear stress-related modules (the brown, red, and pink modules). A total of 129 genes in SET1 and 476 genes in SET2 were identified. CCRL2, LGALS9, and PLCB2 were identified as common hub genes and validated in the GSE100927, GSE28829, and GSE41571. ROC analysis indicates the expression of CCRL2, LGALS9, and PLCB2 could effectively distinguish the atherosclerotic plaque and normal arterial. The expression level of CCRL2, LGALS9, and PLCB2 increases with the accumulation of lipid increased.

Conclusion

We identified CCRL2, LGALS9, and PLCB2 as key genes associated with abnormal ESS and AS and may provide potential prevention and treatment target of AS induced by abnormal ESS.

Fibrotic Signaling in Cardiac Fibroblasts and Vascular Smooth Muscle Cells: The Dual Roles of Fibrosis in HFpEF and CAD

Patients with heart failure with preserved ejection fraction (HFpEF) and atherosclerosis-driven coronary artery disease (CAD) will have ongoing fibrotic remodeling both in the myocardium and in atherosclerotic plaques. However, the functional consequences of fibrosis differ for each location. Thus, cardiac fibrosis leads to myocardial stiffening, thereby compromising cardiac function, while fibrotic remodeling stabilizes the atherosclerotic plaque, thereby reducing the risk of plaque rupture. Although there are currently no drugs targeting cardiac fibrosis, it is a field under intense investigation, and future drugs must take these considerations into account. To explore similarities and differences of fibrotic remodeling at these two locations of the heart, we review the signaling pathways that are activated in the main extracellular matrix (ECM)-producing cells, namely human cardiac fibroblasts (CFs) and vascular smooth muscle cells (VSMCs). Although these signaling pathways are highly overlapping and context-dependent, effects on ECM remodeling mainly act through two core signaling cascades: TGF-β and Angiotensin II. We complete this by summarizing the knowledge gained from clinical trials targeting these two central fibrotic pathways.

Vascular smooth muscle cells in atherosclerosis: time for a re-assessment

Vascular smooth muscle cells (VSMCs) are key participants in both early and late-stage atherosclerosis. VSMCs invade the early atherosclerotic lesion from the media, expanding lesions, but also forming a protective fibrous cap rich in extracellular matrix to cover the 'necrotic' core. Hence, VSMCs have been viewed as plaque-stabilizing, and decreased VSMC plaque content-often measured by expression of contractile markers-associated with increased plaque vulnerability. However, the emergence of lineage-tracing and transcriptomic studies has demonstrated that VSMCs comprise a much larger proportion of atherosclerotic plaques than originally thought, demonstrate multiple different phenotypes in vivo, and have roles that might be detrimental. VSMCs down-regulate contractile markers during atherosclerosis whilst adopting alternative phenotypes, including macrophage-like, foam cell-like, osteochondrogenic-like, myofibroblast-like, and mesenchymal stem cell-like. VSMC phenotypic switching can be studied in tissue culture, but also now in the media, fibrous cap and deep-core region, and markedly affects plaque formation and markers of stability. In this review, we describe the different VSMC plaque phenotypes and their presumed cellular and paracrine functions, the regulatory mechanisms that control VSMC plasticity, and their impact on atherogenesis and plaque stability.

Serum sclerostin level and its relation to subclinical atherosclerosis in the polycystic ovary syndrome phenotypes: A prospective controlled study

Objective

We aim to study the relationship between atherosclerosis and serum sclerostin levels in different phenotypes of polycystic ovary syndrome (PCOS).

Materials and Methods

A total of 134 women with PCOS and 33 age-matched controls participated in this study. Women with PCOS were further divided into subgroups based on their PCOS phenotypes: phenotype A (n=35), phenotype B (n=33), phenotype C (n=31), and phenotype D (n=35). Metabolic parameters, hormonal parameters, carotid intima-media thickness (CIMT), and sclerostin levels were compared among the PCOS phenotypes.

Results

Statistically significant differences occurred among groups regarding follicle-stimulating hormone, luteinizing hormone, estradiol, total cholesterol, low-density lipoprotein, Ferriman-Gallwey score, total testosterone, and free androgen index. The mean CIMT was statistically higher in all PCOS phenotypes than in controls. In subgroup comparison, phenotypes A and B had a higher body mass index (BMI) adjusted CIMT than other phenotypes, respectively (p=0.005). Serum sclerostin levels were higher in PCOS patients than in controls. A concentration of ≥6.297 ng/mL showed a sensitivity of 56% and a specificity of 69.7% to predict PCOS. The BMI-adjusted sclerostin level was significantly higher in phenotype C (20.3±0.7 ng/mL) than in other phenotypes.

Conclusion

Patients with phenotypes A and B seem to have an increased risk for atherosclerosis. Although sclerostin was higher in PCOS patients, we could not demonstrate the relation between sclerostin and atherosclerosis in different PCOS phenotypes.

Podocyte Glucocorticoid Receptors Are Essential for Glomerular Endothelial Cell Homeostasis in Diabetes Mellitus

Background Proteinuria and glomerular segmental fibrosis are inevitable complications of diabetic nephropathy though their mechanisms are poorly understood. Understanding the clinical characteristics and pathogenesis of proteinuria and glomerular segmental fibrosis in diabetic nephropathy is, therefore, urgently needed for patient management of this severe disease. Methods and Results Diabetes mellitus was induced in podocyte-specific glucocorticoid receptor knockout (GRPKO) mice and control littermates by administration of streptozotocin. Primary podocytes were isolated and subjected to analysis of Wnt signaling and fatty acid metabolism. Conditioned media from primary podocytes was transferred to glomerular endothelial cells. Histologic analysis of kidneys from diabetic GRPKO mice showed worsened fibrosis, increased collagen deposition, and glomerulomegaly indicating severe glomerular fibrosis. Higher expression of transforming growth factor-βR1 and β-catenin and suppressed expression of carnitine palmitoyltransferase 1A in nephrin-positive cells were found in the kidneys of diabetic GRPKO mice. Podocytes isolated from diabetic GRPKO mice demonstrated significantly higher profibrotic gene expression and suppressed fatty acid oxidation compared with controls. Administration of a Wnt inhibitor significantly improved the fibrotic features in GRPKO mice. The glomerular endothelium of diabetic GRPKO mice demonstrated the features of endothelial-to-mesenchymal transition. Moreover, endothelial cells treated with conditioned media from podocytes lacking GR showed increased expression of α-smooth muscle actin, transforming growth factor-βR1 and β-catenin levels. Conclusions These data demonstrate that loss of podocyte GR leads to upregulation of Wnt signaling and disruption in fatty acid metabolism. Podocyte-endothelial cell crosstalk, mediated through GR, is important for glomerular homeostasis, and its disruption likely contributes to diabetic nephropathy.

MiR-93 inhibits the vascular calcification of chronic renal failure by suppression of Wnt/β-catenin pathway

OBJECTIVE

To explore the effect of miR-93-mediated Wnt/β-catenin pathway on the vascular calcification (VC) of chronic renal failure (CRF).

METHODS

SD rats were utilized to construct CRF models and divided into Control, CRF, CRF + LV (lentiviral vector)-miR-93 and CRF + LV-Con groups. Renal tissues collected from rats were performed hematoxylin and eosin (HE) staining and Masson staining, while the abdominal aorta was dissected for alizarin red staining and Von Kossa staining. VC-related genes were determined by qRT-PCR while Wnt/β-catenin pathway-related proteins were examined by Western blotting.

RESULTS

As compared to Control group, the serum levels of blood urea nitrogen (BUN), serum creatinine (Scr), phosphorus (P), cystatin C (Cys-C) and 24-h urea protein (24 h Upro), and the scores of renal interstitial lesion and fibrotic area in rats from CRF group were elevated, with the increased calcified area of aorta as well as the enhanced calcium content and ALP. Meanwhile, rats in the CRF group had up-regulated expression of OPN, OCN, RUNX2 and BMP-2 and down-regulated expression of miR-93. As for the expression of Wnt/β-catenin pathway, rats in the CRF group had sharp increases in the protein expression of TCF4 and β-catenin, while α-SMA was down-regulated. However, changes of the above were reversed in rats from CRF + LV-miR-93 group, and TCF4 was confirmed to be a target gene of miR-93.

CONCLUSION

MiR-93, via inhibiting the activity of Wnt/β-catenin pathway by targeting TCF4, can improve the renal function of CRF rats, thereby mitigating the vascular calcification of CRF.

Impaired lipophagy in endothelial cells with prolonged exposure to oxidized low‑density lipoprotein

Oxidative stress induces the formation of oxidized low-density lipoprotein (ox-LDL), which accelerates the development of atherosclerosis and the rupture of atherosclerotic plaques by promoting lipid accumulation and inhibiting autophagy in vascular cells. Lipophagy is known to be involved in maintaining the balance of neutral lipid metabolism; however, the phenomenon of lipophagy deficiency in ox-LDL-treated endothelial cells (ECs) remains to be elucidated. It has been demonstrated that lipid accumulation caused by ox-LDL inhibits autophagy, which promotes apoptosis in ECs. The aim of the present study was to investigate the association between decreased autophagy and lipid accumulation in ECs treated with ox-LDL. Electron microscopy demonstrated that the formation of autolipophagosomes was decreased in ox-LDL-treated human umbilical vein ECs compared with that in the LDL-treated group and was accompanied by a decrease in the autophagy-associated proteins via western blotting analysis. Using laser focal colocalization detection, decreased lipid processing was observed in the lysosomes of ox-LDL-treated ECs, which indicated that lipophagy may be attenuated and subsequently result in lipid accumulation in ox-LDL-treated ECs.

Sclerostin and Vascular Pathophysiology

There is cumulating evidence for a contribution of Wnt signaling pathways in multiple processes involved in atherosclerosis and vascular aging. Wnt signaling plays a role in endothelial dysfunction, in the proliferation and migration of vascular smooth muscle cells (VSMCs) and intimal thickening. Moreover, it interferes with inflammation processes, monocyte adhesion and migration, as well as with foam cell formation and vascular calcification progression. Sclerostin is a negative regulator of the canonical Wnt signaling pathway and, accordingly, the consequence of increased sclerostin availability can be disruption of the Wnt signalling cascade. Sclerostin is becoming a marker for clinical and subclinical vascular diseases and several lines of evidence illustrate its role in the pathophysiology of the vascular system. Sclerostin levels increase with aging and persist higher in some diseases (e.g., diabetes, chronic kidney disease) that are known to precipitate atherosclerosis and enhance cardiovascular risk. Current knowledge on the association between sclerostin and vascular diseases is summarized in this review.

Reduction of Secreted Frizzled-Related Protein 5 Drives Vascular Calcification through Wnt3a-Mediated Rho/ROCK/JNK Signaling in Chronic Kidney Disease

Vascular calcification (VC) is commonly associated with bone loss in patients with chronic kidney disease (CKD). The Wingless-related integration site (Wnt) regulates osteoblast activation through canonical signaling pathways, but the common pathophysiology of these pathways during VC and bone loss has not been identified. A rat model of adenine-induced CKD with VC was used in this study. The rats were fed 0.75% adenine (2.5% protein, 0.92% phosphate) with or without intraperitoneal injection of calcitriol (0.08 µg/kg/day) for 4 weeks. Angiotensin II (3 µM)-induced VC was achieved in high phosphate medium (3 mM) through its effect on vascular smooth muscle cells (VSMCs). In an mRNA profiler polymerase chain reaction assay of the Wnt signaling pathway, secreted frizzled-related protein 5 (sFRP5) levels were significantly decreased in the CKD rat model compared with the control group. The repression of sFRP5 on VSMC trans-differentiation was mediated through Rho/Rho-associated coiled coil containing protein kinase (ROCK) and c-Jun N-terminal kinase (JNK) pathways activated by Wnt3a. In a proof of concept study conducted with patients with CKD, serum sFRP5 concentrations were significantly lower in subjects with VC than in those without VC. Our findings suggest that repression of sFRP5 is associated with VC in the CKD environment via activation of the noncanonical Wnt pathway, and thus that sFRP5 might be a novel therapeutic target for VC in CKD.

atherosclerosis: gone with the Wnt?

Atherosclerosis, a pathology affecting large and medium-sized arteries, is the major cause of cardiovascular morbidity/mortality in industrialized countries. During atherosclerosis, cells accumulate large amounts of cholesterol through the uptake of modified low-density lipoprotein particles to form foam cells. This accumulation forms the basis for the development of the disease and for a large spectrum of other diseases in various organs. Massive research efforts have yielded valuable information about the underlying molecular mechanisms of atherosclerosis. In particular, newer discoveries on the early stage of lesion formation, cholesterol accumulation, reverse cholesterol transport, and local inflammation in the vascular wall have opened unanticipated horizons of understanding and raised novel questions and therapeutic opportunities. In this review, we focus on Wnt signaling, which has received little attention so far, yet affects lysosomal function and signalling pathways that limit cholesterol accumulation. This occurs in different tissues and cell types, including smooth muscle cells, endothelial cells and macrophages in the arterial wall, and thus profoundly impacts on atherosclerotic disease development and progression.

Wnt Pathway Gene Expression Is Associated With Arterial Stiffness

Background

Animal and in vitro experiments implicate the Wnt pathway in cardiac development, fibrosis, vascular calcification, and atherosclerosis, but research in humans is lacking. We examined peripheral blood Wnt pathway gene expression and arterial stiffness in 369 healthy African ancestry men (mean age, 64 years).

Methods and Results

Gene expression was assessed using a custom Nanostring nCounter gene expression panel (N=43 genes) and normalized to housekeeping genes and background signal. Arterial stiffness was assessed via brachial‐ankle pulse‐wave velocity. Fourteen Wnt genes showed detectable expression and were tested individually as predictors of pulse‐wave velocity using linear regression, adjusting for age, height, weight, blood pressure, medication use, resting heart rate, current smoking, alcohol intake, and sedentary lifestyle. Adenomatous polyposis coli regulator of Wnt signaling pathway (APC), glycogen synthase kinase 3β (GSK3B), and transcription factor 4 (TCF4) were significantly associated with arterial stiffness (P<0.05 for all). When entered into a single model, APC and TCF4 expression remained independently associated with arterial stiffness (P=0.04 and 0.003, respectively), and each explained ≈3% of the variance in pulse‐wave velocity.

Conclusions

The current study establishes a novel association between in vivo expression of the Wnt pathway genes, APC and TCF4, with arterial stiffness in African ancestry men, a population at high risk of hypertensive vascular disease.

Admission Levels of DKK1 (Dickkopf-1) Are Associated With Future Cardiovascular Death in Patients With Acute Coronary Syndromes

Objective- The Wnt/wingless signaling antagonist DKK1 (dickkopf-1) regulates platelet-mediated inflammation and may contribute to plaque destabilization. We hypothesized that DKK1 would be associated with cardiovascular outcomes. Approach and Results- We determined DKK1 levels in serum samples obtained before randomization, at discharge, and 1 and 6 months in a subset of 5165 patients with acute coronary syndromes in the PLATO trial (Platelet Inhibition and Patient Outcomes; NCT00391872). The median (interquartile range) DKK1 concentrations were 0.61 (0.20-1.27) ng/mL at baseline and increased during follow-up. The hazard ratio (95% CIs) for the composite end point (cardiovascular death, nonprocedural spontaneous myocardial infarction, or stroke) during 1 year of follow-up, per 50% increase in baseline DKK1 concentration, was 1.06 (1.02-1.10), P=0.0011, and remained significant in fully adjusted analysis with 14 conventional clinical and demographic and 6 biochemical variables, including NT-proBNP (N-terminal pro-B-type natriuretic peptide), hs-TnT (high-sensitivity troponin T), and GDF-15 (growth differentiation factor 15; 1.05 [1.00-1.09]; P=0.028). This association was mainly driven by the association with cardiovascular death, where a gradual increase in event rates was observed with increasing quartiles of DKK1 (2.7%, 3.0%, 4.3%, and 5.0%) and remained significant and unmodified in fully adjusted analysis (hazard ratio, 1.10 [1.04-1.17]; P=0.002). Change in DKK1 and levels at 1 month were unrelated to outcomes. A modifying effect of ticagrelor on DKK1 discharge levels was observed but not associated with prognosis. Conclusions- In patients with acute coronary syndromes treated with dual antiplatelet treatment, admission DKK1 levels were independently associated with a composite of cardiovascular death, myocardial infarction, or stroke and with cardiovascular death alone.

Serum leptin, a potential predictor of long-term angiographic progression in Takayasu's arteritis

Aim

In patients with Takayasu's arteritis (TA), current biomarkers that properly reflect the progression of the vascular structure remain absent. We aimed to determine the serum leptin level to investigate its relationship with imaging changes and assess its value as a predictor for long‐term radiological progression.

Method

This study included 34 untreated TA patients and 40 age‐matched healthy controls. At baseline and during the 5‐year follow‐up, we assessed disease activity using Kerr's criteria and Indian Takayasu Clinical Activity Score (ITAS2010) and monitored laboratory biomarkers as well as imaging findings. Serum leptin levels were measured by enzyme‐linked immunosorbent assay.

Results

The baseline serum leptin levels were significantly higher in TA patients than in healthy controls. Leptin was significantly positively correlated with triglyceride and high‐density lipoprotein cholesterol levels and negatively correlated with fibrinogen and C‐reactive protein levels. Patients were subdivided into three groups based on their baseline leptin level. During a 5‐year follow‐up, patients in the high and medium leptin groups showed more radiological progression compared to those in the low leptin group. Cox proportional hazard regression analysis showed that a high serum leptin level was a positive predictor of radiological progression.

Conclusion

Leptin is a potential biomarker for assessing TA structural progression. Untreated patients with elevated serum leptin levels are at a higher risk of progression in the aorta. Thus, the leptin level can be a predictor of long‐term radiological progression.

Ending Restenosis: Inhibition of Vascular Smooth Muscle Cell Proliferation by cAMP

Increased vascular smooth muscle cell (VSMC) proliferation contributes towards restenosis after angioplasty, vein graft intimal thickening and atherogenesis. The second messenger 3′ 5′ cyclic adenosine monophosphate (cAMP) plays an important role in maintaining VSMC quiescence in healthy vessels and repressing VSMC proliferation during resolution of vascular injury. Although the anti-mitogenic properties of cAMP in VSMC have been recognised for many years, it is only recently that we gained a detailed understanding of the underlying signalling mechanisms. Stimuli that elevate cAMP in VSMC inhibit G₁-S phase cell cycle progression by inhibiting expression of cyclins and preventing S-Phase Kinase Associated Protein-2 (Skp2-mediated degradation of cyclin-dependent kinase inhibitors. Early studies implicated inhibition of MAPK signalling, although this does not fully explain the anti-mitogenic effects of cAMP. The cAMP effectors, Protein Kinase A (PKA) and Exchange Protein Activated by cAMP (EPAC) act together to inhibit VSMC proliferation by inducing Cyclic-AMP Response Element Binding protein (CREB) activity and inhibiting members of the RhoGTPases, which results in remodelling of the actin cytoskeleton. Cyclic-AMP induced actin remodelling controls proliferation by modulating the activity of Serum Response Factor (SRF) and TEA Domain Transcription Factors (TEAD), which regulate expression of genes required for proliferation. Here we review recent research characterising these mechanisms, highlighting novel drug targets that may allow the anti-mitogenic properties of cAMP to be harnessed therapeutically to limit restenosis.

Simvastatin promotes endothelial dysfunction by activating the Wnt/β‑catenin pathway under oxidative stress

Atherosclerosis is a major pathogenic factor in patients with cardiovascular diseases, and endothelial dysfunction (ED) plays a primary role in its occurrence and development. Simvastatin is a lipid‑lowering drug, which is commonly used to prevent or treat risk factors of cardiovascular diseases with a significant anti‑atherogenic effect. However, its impact on endothelial cells under conditions of oxidative stress and broader mechanisms of action remain unclear. The present study evaluated the effect of simvastatin on human umbilical vein endothelial cells (HUVECs) under oxidative stress with H2O2, and the associated mechanisms. At a high dose (1 µM), simvastatin exacerbated H2O2‑induced endothelial cell dysfunction. Moreover, inhibition of the Wnt/β‑catenin pathway by salinomycin significantly suppressed the simvastatin‑associated HUVEC dysfunction. Western blot analysis further demonstrated that simvastatin promoted the phosphorylation of low‑density lipoprotein receptor‑related protein 6 (LRP6) and activated the Wnt/β‑catenin pathway. Simvastatin also activated endoplasmic reticulum (ER) stress, which was reversed by salinomycin treatment. Based on these results, it was hypothesized that simvastatin may promote ER stress by facilitating LRP6 phosphorylation and the subsequent activation of the Wnt/β‑catenin pathway, thereby enhancing H2O2‑induced ED. Therefore, high‑dose simvastatin treatment could have potential toxic side effects, indicating the need for close clinical management, monitoring and patient selection.

Inhibition of Vascular Calcification

Objective- Vascular calcification is a major risk factor for rupture of atherosclerotic plaques. High expression of BMP2 (bone morphogenetic protein 2) in lesions suggests its importance in vascular calcification during atherosclerosis. Teniposide is a Topo II (DNA topoisomerase II) inhibitor and is used for cancer treatment. Previously, we reported that teniposide activated macrophage ABCA1 (ATP-binding cassette transporter A1) expression and free cholesterol efflux indicating Topo II inhibitors may demonstrate antiatherogenic properties. Herein, we investigated the effects of teniposide on the development of atherosclerosis and vascular calcification in apoE^-/- (apoE deficient) mice. Approach and Results- apoE^-/- mice were fed high-fat diet containing teniposide for 16 weeks, or prefed high-fat diet for 12 weeks followed by high-fat diet containing teniposide for 4 weeks. Atherosclerosis and vascular calcification were determined. Human aortic smooth muscle cells were used to determine the mechanisms for teniposide-inhibited vascular calcification. Teniposide reduced atherosclerotic lesions. It also substantially reduced vascular calcification without affecting bone structure. Mechanistically, teniposide reduced vascular calcification by inactivating BMP2/(pi-Smad1/5/8 [mothers against decapentaplegic homolog 1, 5, and 8])/RUNX2 (runt-related transcription factor 2) axis in a p53-dependent manner. Furthermore, activated miR-203-3p by teniposide functioned as a link between activated p53 expression and inhibited BMP2 expression in inhibition of calcification. Conclusions- Our study demonstrates that teniposide reduces vascular calcification by regulating p53-(miR-203-3p)-BMP2 signaling pathway, which contributes to the antiatherogenic properties of Topo II inhibitors.

The matrix environmental and cell mechanical properties regulate cell migration and contribute to the invasive phenotype of cancer cells

The minimal structural unit of a solid tumor is a single cell or a cellular compartment such as the nucleus. A closer look inside the cells reveals that there are functional compartments or even structural domains determining the overall properties of a cell such as the mechanical phenotype. The mechanical interaction of these living cells leads to the complex organization such as compartments, tissues and organs of organisms including mammals. In contrast to passive non-living materials, living cells actively respond to the mechanical perturbations occurring in their microenvironment during diseases such as fibrosis and cancer. The transformation of single cancer cells in highly aggressive and hence malignant cancer cells during malignant cancer progression encompasses the basement membrane crossing, the invasion of connective tissue, the stroma microenvironments and transbarrier migration, which all require the immediate interaction of the aggressive and invasive cancer cells with the surrounding extracellular matrix environment including normal embedded neighboring cells. All these steps of the metastatic pathway seem to involve mechanical interactions between cancer cells and their microenvironment. The pathology of cancer due to a broad heterogeneity of cancer types is still not fully understood. Hence it is necessary to reveal the signaling pathways such as mechanotransduction pathways that seem to be commonly involved in the development and establishment of the metastatic and mechanical phenotype in several carcinoma cells. We still do not know whether there exist distinct metastatic genes regulating the progression of tumors. These metastatic genes may then be activated either during the progression of cancer by themselves on their migration path or in earlier stages of oncogenesis through activated oncogenes or inactivated tumor suppressor genes, both of which promote the metastatic phenotype. In more detail, the adhesion of cancer cells to their surrounding stroma induces the generation of intracellular contraction forces that deform their microenvironments by alignment of fibers. The amplitude of these forces can adapt to the mechanical properties of the microenvironment. Moreover, the adhesion strength of cancer cells seems to determine whether a cancer cell is able to migrate through connective tissue or across barriers such as the basement membrane or endothelial cell linings of blood or lymph vessels in order to metastasize. In turn, exposure of adherent cancer cells to physical forces, such as shear flow in vessels or compression forces around tumors, reinforces cell adhesion, regulates cell contractility and restructures the ordering of the local stroma matrix that leads subsequently to secretion of crosslinking proteins or matrix degrading enzymes. Hence invasive cancer cells alter the mechanical properties of their microenvironment. From a mechanobiological point-of-view, the recognized physical signals are transduced into biochemical signaling events that guide cellular responses such as cancer progression after the malignant transition of cancer cells from an epithelial and non-motile phenotype to a mesenchymal and motile (invasive) phenotype providing cellular motility. This transition can also be described as the physical attempt to relate this cancer cell transitional behavior to a T1 phase transition such as the jamming to unjamming transition. During the invasion of cancer cells, cell adaptation occurs to mechanical alterations of the local stroma, such as enhanced stroma upon fibrosis, and therefore we need to uncover underlying mechano-coupling and mechano-regulating functional processes that reinforce the invasion of cancer cells. Moreover, these mechanisms may also be responsible for the awakening of dormant residual cancer cells within the microenvironment. Physicists were initially tempted to consider the steps of the cancer metastasis cascade as single events caused by a single mechanical alteration of the overall properties of the cancer cell. However, this general and simple view has been challenged by the finding that several mechanical properties of cancer cells and their microenvironment influence each other and continuously contribute to tumor growth and cancer progression. In addition, basement membrane crossing, cell invasion and transbarrier migration during cancer progression is explained in physical terms by applying physical principles on living cells regardless of their complexity and individual differences of cancer types. As a novel approach, the impact of the individual microenvironment surrounding cancer cells is also included. Moreover, new theories and models are still needed to understand why certain cancers are malignant and aggressive, while others stay still benign. However, due to the broad variety of cancer types, there may be various pathways solely suitable for specific cancer types and distinct steps in the process of cancer progression. In this review, physical concepts and hypotheses of cancer initiation and progression including cancer cell basement membrane crossing, invasion and transbarrier migration are presented and discussed from a biophysical point-of-view. In addition, the crosstalk between cancer cells and a chronically altered microenvironment, such as fibrosis, is discussed including the basic physical concepts of fibrosis and the cellular responses to mechanical stress caused by the mechanically altered microenvironment. Here, is highlighted how biophysical approaches, both experimentally and theoretically, have an impact on classical hallmarks of cancer and fibrosis and how they contribute to the understanding of the regulation of cancer and its progression by sensing and responding to the physical environmental properties through mechanotransduction processes. Finally, this review discusses various physical models of cell migration such as blebbing, nuclear piston, protrusive force and unjamming transition migration modes and how they contribute to cancer progression. Moreover, these cellular migration modes are influenced by microenvironmental perturbances such as fibrosis that can induce mechanical alterations in cancer cells, which in turn may impact the environment. Hence, the classical hallmarks of cancer need to be refined by including biomechanical properties of cells, cell clusters and tissues and their microenvironment to understand mechano-regulatory processes within cancer cells and the entire organism.

Sclerostin is expressed in the atherosclerotic plaques of patients who undergoing carotid endarterectomy

BACKGROUND

Sclerostin (SC) is a monomeric glycoprotein expressed by osteocytes that affects bone formation. Recent studies have suggested a potential role for this protein in the pathophysiology of vascular diseases. The aim of the present study was to investigate SC expression in atherosclerotic plaques of patients affected by severe atherosclerotic disease who underwent carotid endarterectomy. We also evaluated possible differences in SC expression between patients with and without type 2 diabetes (T2D).

METHODS

This was a cross-sectional study involving 46 patients aged 55 to 80 years (mean, 71.1 ± 6.7 years, 36 men, 15 patients with T2D) who underwent carotid endarterectomy. Immunohistochemical levels of SC were evaluated in the atherosclerotic plaques by double-staining immunochemistry, and serum SC levels were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Sclerostin was present in the atherosclerotic plaques of all subjects investigated and increased significantly in the media compared with the intima (P < 0.0001) as well as in vascular smooth muscle cells (VSMCs) compared with the infiltrating macrophages (P < 0.0001). However, no significant difference in SC expression was observed between patients with and without T2D. No correlation was found between serum and immunohistochemical levels of SC; significantly increased SC serum levels were detected in males compared with females (P = 0.049).

CONCLUSIONS

We have demonstrated, for the first time, the expression of SC in VSMCs of atherosclerotic plaques, suggesting a potential role for this protein in the development of atherosclerosis. Further studies are needed to understand if the role played by SC is detrimental or protective in the atherosclerotic disease process.

The Interplay of SIRT1 and Wnt Signaling in Vascular Calcification

Vascular calcification is a major health risk and is highly correlated with atherosclerosis, diabetes, and chronic kidney disease. The development of vascular calcification is an active and complex process linked with a multitude of signaling pathways, which regulate promoters and inhibitors of osteogenesis, the balance of which become deregulated in disease conditions. SIRT1, a protein deacetylase, known to be protective in inhibiting oxidative stress and inflammation within the vessel wall, has been shown as a possible key player in modulating the cell-fate determining canonical Wnt signaling pathways. Suppression of SIRT1 has been reported in patients suffering with cardiovascular pathologies, suggesting that the sustained acetylation of osteogenic factors could contribute to their activation and in turn, lead to the progression of calcification. There is clear evidence of the synergy between β-Catenin and elevated Runx2, and with Wnt signaling being β-Catenin dependent, further understanding is needed as to how these molecular pathways converge and interact, in order to provide novel insight into the mechanism by which smooth muscle cells switch to an osteogenic differentiation programme. Therefore, this review will describe the current concepts of pathological soft tissue mineralization, with a focus on the contribution of SIRT1 as a regulator of Wnt signaling and its targets, discussing SIRT1 as a potential target for manipulation and therapy.

The effects of pigment epithelium-derived factor on atherosclerosis: putative mechanisms of the process

Cardiovascular disease (CVD) is a leading cause of death worldwide. Atherosclerosis is believed to be the major cause of CVD, characterized by atherosclerotic lesion formation and plaque disruption. Although remarkable advances in understanding the mechanisms of atherosclerosis have been made, the application of these theories is still limited in the prevention and treatment of atherosclerosis. Therefore, novel and effective strategies to treat high-risk patients with atherosclerosis require further development. Pigment epithelium-derived factor (PEDF), a glycoprotein with anti-inflammatory, anti-oxidant, anti-angiogenic, anti-thrombotic and anti-tumorigenic properties, is of considerable interest in the prevention of atherosclerosis. Accumulating research has suggested that PEDF exerts beneficial effects on atherosclerotic lesions and CVD patients. Our group, along with colleagues, has demonstrated that PEDF may be associated with acute coronary syndrome (ACS), and that the polymorphisms of rs8075977 of PEDF are correlated with coronary artery disease (CAD). Moreover, we have explored the anti-atherosclerosis mechanisms of PEDF, showing that oxidized-low density lipoprotein (ox-LDL) reduced PEDF concentrations through the upregulation of reactive oxygen species (ROS), and that D-4F can protect endothelial cells against ox-LDL-induced injury by preventing the downregulation of PEDF. Additionally, PEDF might alleviate endothelial injury by inhibiting the Wnt/β-catenin pathway. These data suggest that PEDF may be a novel therapeutic target for the treatment of atherosclerosis. In this review, we will summarize the role of PEDF in the development of atherosclerosis, focusing on endothelial dysfunction, inflammation, oxidative stress, angiogenesis and cell proliferation. We will also discuss its promising therapeutic implications for atherosclerosis.

Sphingomyelin synthase 2 promotes H2O2-induced endothelial dysfunction by activating the Wnt/β-catenin signaling pathway

Atherosclerosis (AS) is the primary cause of various cardiovascular and cerebrovascular diseases and has high morbidity and mortality rates. Oxidative stress-induced endothelial cells (ECs) dysfunction is the pathological basis of AS. In addition, sphingomyelin (SM) and the Wnt/β-catenin signaling pathway are considered to be closely associated with AS; however, the specific mechanism is not clear. Therefore, the present study investigated whether SM may induce ECs dysfunction through the Wnt/β-catenin signaling pathway. Firstly, a sphingomyelin synthase 2 (SMS2) overexpression cell model was constructed. It was identified that the expression of SMS2 was increased when ECs were treated with H₂O₂. In addition, these results demonstrated that SMS2 overexpression promoted apoptosis and macrophage adhesion of H₂O₂-induced ECs, thereby increasing the expression of β-catenin. Furthermore, SMS activity was inhibited with Dy105, combined with simultaneous treatment with LiCl or H₂O₂. This additionally confirmed that Dy105 significantly inhibited SMS activity and decreased the level of ECs dysfunction and β-catenin content; however, LiCl served a key role in activating the Wnt/β-catenin signaling pathway to promote ECs dysfunction. Collectively, these results suggested that SMS2 overexpression may promote ECs dysfunction by activating the Wnt/β-catenin signaling pathway, while Dy105 may inhibit the evolution of oxidative stress-induced dysfunction.

Senescent Microvesicles: A Novel Advance in Molecular Mechanisms of Atherosclerotic Calcification

Atherosclerosis, a chronic inflammatory disease that causes the most heart attacks and strokes in humans, is the leading cause of death in the developing world; its principal clinical manifestation is coronary artery disease. The development of atherosclerosis is attributed to the aging process itself (biological aging) and is also associated with the development of chronic diseases (premature aging). Both aging processes produce an increase in risk factors such as oxidative stress, endothelial dysfunction and proinflammatory cytokines (oxi-inflamm-aging) that might generate endothelial senescence associated with damage in the vascular system. Cellular senescence increases microvesicle release as carriers of molecular information, which contributes to the development and calcification of atherosclerotic plaque, as a final step in advanced atherosclerotic plaque formation. Consequently, this review aims to summarize the information gleaned to date from studies investigating how the senescent extracellular vesicles, by delivering biological signalling, contribute to atherosclerotic calcification.

Cortistatin inhibits arterial calcification in rats via GSK3β/β-catenin and protein kinase C signalling but not c-Jun N-terminal kinase signalling

AIM

Cortistatin (CST) is a newly discovered endogenous active peptide that exerts protective effects on the cardiovascular system. However, the relationship between CST and aortic calcification and the underlying mechanism remain obscure. Therefore, we investigated effects of CST on aortic calcification and its signalling pathways.

METHODS

Calcium content and alkaline phosphatase (ALP) activity were measured using the o-cresolphthalein colorimetric method and ALP assay kit respectively. Protein expression of smooth muscle (SM)-ɑ-actin, osteocalcin (OCN), β-catenin, glycogen synthase kinase 3β (GSK3β), p-GSK3β, protein kinase C (PKC), p-PKC, c-Jun N-terminal kinase (JNK) and p-JNK was determined using Western blotting.

RESULTS

In aorta from a rat vitamin D3 calcification model, CST abrogated calcium deposition and pathological damage, decreased the protein expression of OCN and β-catenin and increased SM-ɑ-actin expression. In a rat cultured vascular smooth muscular cell (VSMC) calcification model induced by β-glycerophosphate (β-GP), CST inhibited the increase in ALP activity, calcium content and OCN protein and the decrease in SM-α-actin expression. CST also inhibited the β-GP-induced increase in p-GSK3β and β-catenin protein (both P < .05). The inhibitory effects of CST on ALP activity, calcium deposition and β-catenin protein were abolished by pretreatment with lithium chloride, a GSK3β inhibitor. CST promoted the protein expression of p-PKC by 68.5% (P < .01), but not p-JNK. The ability of CST to attenuate β-GP-induced increase in ALP activity, calcium content and OCN expression in the VSMC model was abolished by pretreatment with the PKC inhibitor Go6976.

CONCLUSION

These results indicate that CST inhibits aortic calcification and osteogenic differentiation of VSMCs likely via the GSK3β/β-catenin and PKC signalling pathways, but not JNK signalling pathway.

ClC-2 knockdown prevents cerebrovascular remodeling via inhibition of the Wnt/β-catenin signaling pathway

BACKGROUND

Mishandling of intracellular chloride (Cl-) concentration ([Cl-]i) in cerebrovascular smooth muscle cells is implicated in several pathological processes, including hyperplasia and remodeling. We investigated the effects of ClC-2-mediated Cl- efflux on the proliferation of human brain vascular smooth muscle cells (HBVSMCs) induced by angiotensin II (AngII).

METHODS

Cell proliferation and motility were determined using the CCK-8, bromodeoxyuridine staining, wound healing and invasion assays. ClC-2, PCNA, Ki67, survivin and cyclin D1 expression, and β-catenin and GSK-3β phosphorylation were examined using western blotting. Histological analyses were performed using hematoxylin and eosin staining and α-SMA staining.

RESULTS

Our results showed that AngII-induced HBVSMC proliferation was accompanied by a decrease in [Cl-]i and an increase in ClC-2 expression. Inhibition of ClC-2 by siRNA prevented AngII from inducing the efflux of Cl-. AngII-induced HBVSMC proliferation, migration and invasion were significantly attenuated by ClC-2 downregulation. The inhibitory effects of ClC-2 knockout on HBVSMC proliferation and motility were associated with inactivation of the Wnt/β-catenin signaling pathway, as evidenced by inhibition of β-catenin phosphorylation and nuclear translocation, and decrease of GSK-3β phosphorylation and survivin and cyclin D1 expression. Recombinant Wnt3a treatment markedly reversed the effect of ClC-2 knockdown on HBVSMC viability. An in vivo study revealed that knockdown of ClC-2 with shRNA adenovirus ameliorated basilar artery remodeling by inhibiting Wnt/β-catenin signaling in AngII-treated mice.

CONCLUSION

This study demonstrates that blocking ClC-2-mediated Cl- efflux inhibits AngII-induced cerebrovascular smooth muscle cell proliferation and migration by inhibiting the Wnt/β-catenin pathway. Our data indicate that downregulation of ClC-2 may be a viable strategy in the prevention of hyperplasia and remodeling of cerebrovascular smooth muscle cells.

Understanding the role of non-coding RNA (ncRNA) in stent restenosis

Coronary heart disease (CHD) is one of the leading disorders with the highest mortality rate. Percutaneous angioplasty and stent implantation are the currently available standard methods for the treatment of obstructive coronary artery disease. However, the stent being an exogenous substance causes several complications by promoting the proliferation of vascular smooth muscle cells, immune responses and neointima formation after implantation, leading to post-stent restenosis (ISR) and late thrombosis. The prevention of these adverse vascular events is important to achieve long-term proper functioning of the heart after stent implantation. Non-coding ribonucleic acids (ncRNAs) are RNA molecules not translated into proteins, theyhave a great potential in regulating endothelial cell and vascular smooth muscle function as well as inflammatory reactions. In this review, we outline the regulatory functions of different classes of ncRNA in cardiovascular disease and propose ncRNAs as new targets for stent restonosis treatment.

eNOS S-nitrosylation mediated OxLDL-induced endothelial dysfunction via increasing the interaction of eNOS with β‑catenin

Protein S-nitrosylation plays an important role in the progression of cardiovascular diseases. eNOS can be S-nitrosylated in endothelial cells, and this modification reversibly attenuates enzyme activity. Under physiological conditions, eNOS directly interacts with β‑catenin. However, whether and how eNOS S-nitrosylation regulates the β‑catenin signal pathway and participates in endothelial dysfunction remains unknown. Here, we show that OxLDL induces the S-nitrosylation of eNOS, which enhances the interaction between eNOS and β‑catenin, transcriptional activity of β‑catenin, cell migration and adhesion molecule expression in endothelial cells. In addition, these effects are partially abolished after eNOS is mutated at Cys94 and Cys99, but not Cys441, in endothelial cells. Furthermore, OxLDL increases iNOS expression. The specific iNOS inhibitor 1400 W decreases eNOS S-nitrosylation and the association of eNOS and β‑catenin, thereby blocking the β‑catenin signal pathway to alleviate OxLDL-induced endothelial dysfunction. Taken together, OxLDL induces eNOS S-nitrosylation at Cys94 and Cys99 via an iNOS-dependent manner, which may increase β‑catenin activation and trigger endothelial injury. This study describes a novel mechanism of endothelial dysfunction.

Excessive angiogenesis associated with psoriasis as a cause for cardiovascular ischaemia

Psoriasis, a common disease affecting 2%-3% of the UK population, produces significant impairment of quality of life and is an immense burden on sufferers and their families. Psoriasis is associated with significant cardiovascular comorbidity and the metabolic syndrome. Angiogenesis, a relatively under-researched component of psoriasis, is a key factor in pathogenesis of psoriasis and also contributes to the development of atherosclerosis. Vascular endothelial growth factor (VEGF) is a well-established mediator of pathological angiogenesis which is upregulated in psoriasis. It is possible that, in patients with psoriasis, cutaneous angiogenesis may be both a marker for systemic vascular pathology and a novel therapeutic target. In this viewpoint study, the role of VEGF-mediated angiogenesis as a cause for cardiovascular events in patients with psoriasis is explored.

WNT Signaling in Cardiac and Vascular Disease

WNT signaling is an elaborate and complex collection of signal transduction pathways mediated by multiple signaling molecules. WNT signaling is critically important for developmental processes, including cell proliferation, differentiation and tissue patterning. Little WNT signaling activity is present in the cardiovascular system of healthy adults, but reactivation of the pathway is observed in many pathologies of heart and blood vessels. The high prevalence of these pathologies and their significant contribution to human disease burden has raised interest in WNT signaling as a potential target for therapeutic intervention. In this review, we first will focus on the constituents of the pathway and their regulation and the different signaling routes. Subsequently, the role of WNT signaling in cardiovascular development is addressed, followed by a detailed discussion of its involvement in vascular and cardiac disease. After highlighting the crosstalk between WNT, transforming growth factor-β and angiotensin II signaling, and the emerging role of WNT signaling in the regulation of stem cells, we provide an overview of drugs targeting the pathway at different levels. From the combined studies we conclude that, despite the sometimes conflicting experimental data, a general picture is emerging that excessive stimulation of WNT signaling adversely affects cardiovascular pathology. The rapidly increasing collection of drugs interfering at different levels of WNT signaling will allow the evaluation of therapeutic interventions in the pathway in relevant animal models of cardiovascular diseases and eventually in patients in the near future, translating the outcomes of the many preclinical studies into a clinically relevant context.

Mast cells emerge as mediators of atherosclerosis: Special emphasis on IL-37 inhibition

In atherosclerosis lipoproteins stimulate the innate immune response, leading to the release of inflammatory cytokines and chemokines. Hypercholesterolemia may activate the synthesis and release of inflammatory cytokines such as IL-1, which induces TNF release in mast cells (MCs). IL-1 and IL-1 family members orchestrate a broadening list of inflammatory diseases, including atherosclerosis. MCs are implicated in the pathophysiology of several diseases including allergy and inflammation. Activated MCs, located perivascularly, contribute to inflammation in atherosclerosis by producing inflammatory cytokines. MC IL-1-activation leads to the immediate release of inflammatory chemical mediators and TNF, and late inflammatory compounds such as cytokines. MCs can be activated by exogenous cytokines, antigens, microbial products (LPS) and neurotransmitters and generate IL-1 beta, TNF and several other inflammatory cytokines/chemokines along with PGD2, leukotrienes, histamine and proteases. MCs activated with IL-1 induce selective release of IL-6 without degranulation. TNF emerges as one of the most potent inflammatory cytokines involved in the response due to LDL. Cytokines, such as IL-1, IL-6, IL-33 and TNF, are generated in the inflammatory sites by both macrophages and MCs, mediating atherosclerosis. IL-37 (IL-1 family member 7) binds IL-18Ra chain and acts by an intracellular mechanism down-regulating the expression of pro-inflammatory signals cJun, MAP kinase p38a, STAT transcription factors and p53. Blocking IL-1 with IL-37 alleviates the symptoms in patients with inflammatory diseases including arteriosclerosis. The impact of IL-37 on inflammatory cytokines mediating atherosclerosis is beneficial and protective. However, more studies are needed to better define this mechanism and the safety and tolerability of IL-37.

Pigment epithelium-derived factor alleviates endothelial injury by inhibiting Wnt/β-catenin pathway

Background

Oxidized low-density lipoprotein (ox-LDL) can induce endothelial injury and plays a vital role in the procession and development of atherosclerosis. Little is known regarding whether Wnt/β-catenin pathway is involved in ox-LDL-induced endothelial injury or whether it further promotes atherosclerosis via increased oxidative stress. This study aimed to investigate the role of Wnt/β-catenin pathway in ox-LDL-induced vascular endothelial injury and determine whether pigment epithelium-derived factor (PEDF) could alleviate ox-LDL-induced endothelial injury by inhibiting Wnt/β-catenin pathway.

Methods

Injury of human umbilical vein endothelial cells (HUVECs) was evaluated with an MTT assay, by monitoring lactate dehydrogenase (LDH) release and determining the apoptotic ratio. The expression of β-catenin (non-phosphorylated-β-catenin), disheveled-1 (Dvl-1) and Cyclin D1 was analyzed with western blotting and quantitative real-time PCR. Oxidative stress status was assessed by measuring the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide (NO).

Results

Exposure of HUVECs to ox-LDL led to a decrease in cell viability and an increase in LDH release and apoptosis with concomitant enhancement of oxidative stress, as assessed by increased ROS and MDA generation, as well as decreased SOD activity and NO levels. Similar to lithium chloride (LiCl, a Wnt/β-catenin pathway activator), ox-LDL up-regulated the expression of β-catenin, Dvl-1 and Cyclin D1, markers of Wnt/β-catenin pathway activation. However, ox-LDL-induced activation of Wnt/β-catenin pathway, as well as ox-LDL-induced cell injury and oxidative stress, were synergistically promoted by LiCl and mitigated by Dickkopf 1 (DKK-1), an inhibitor of Wnt/β-catenin pathway. Additionally, ox-LDL-induced HUVEC injury and apoptosis, oxidative stress and activation of Wnt/β-catenin pathway were suppressed by PEDF, while they were further strengthened by a small interfering RNA of PEDF.

Conclusion

Wnt/β-catenin pathway may mediate ox-LDL-induced endothelial injury via oxidative stress, and PEDF ameliorates endothelial injury by suppressing Wnt/β-catenin pathway and subsequently reducing oxidative stress.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0407-8) contains supplementary material, which is available to authorized users.

Wnt signaling pathway in retinal vascularization

Wnt-signaling, a ubiquitous pathway that directs differentiation, cell polarity, and tissue specificity, has been implicated as an important gene-expression pathway in retinal development. An increasing body of evidence supports the importance of Wnt-signaling, and specifically, norrin-mediated Wnt-signaling in retinal development and retinal maintenance. Gene mutations affecting the Wnt-signaling pathways result in a variety of inherited vitreoretinopathies. Additionally, there is growing evidence that prematurity and associated retinopathy are associated with alterations in the Wnt-signaling pathways. Further investigations may allow for improved diagnoses, management, and therapies in the future.

The Urotensin II System and Carotid Atherosclerosis: A Role in Vascular Calcification

BACKGROUND AND AIMS

The aims of the present study were to determine the expression of urotensin II (UII), urotensin-II related peptide (URP), and their receptor (UT) in stable and unstable carotid atherosclerosis, and determine the effects of UII on human aortic smooth muscle cell (SMCs) calcification.

METHODS AND RESULTS

We examined UII, URP, and UT protein expression in 88 carotid endarterectomy specimens using immunohistochemistry. Expression of UII, URP, and UT was more evident in unstable compared to stable plaques (P < 0.05). Multivariate Spearman correlation analyses revealed significant positive correlations between UII, URP and UT overall staining and presence of calcification, severity of stenosis and inflammation (P < 0.05). Subjects undergoing carotid endarterectomy had significantly higher plasma UII levels, as assessed by ELISA, when compared with normolipidemic healthy control subjects (P < 0.05). Incubation of human aortic SMCs cultured in phosphate media with varying concentrations of UII resulted in a significant increase in calcium deposition and alkaline phosphatase activity. UII also significantly increased β-catenin translocation and expression of ALPL, BMP2, ON, and SOX9 (P < 0.05). Incubation of cells with phosphate medium alone increased the expression of the pre-UT and mature UT (P < 0.01), and addition of UII had a synergistic effect on pre-UT protein expression (P < 0.001) compared to phosphate medium alone.

CONCLUSIONS

Upregulation of UII, URP, and UT in unstable carotid endarterectomy plaques and plasma, and the stimulatory effect of UII on vascular smooth muscle cell calcification suggest that the UII system may play a role in the pathogenesis of vascular calcification and stability of atherosclerosis.

Convergent Signaling Pathways Controlled by LRP1 (Receptor-related Protein 1) Cytoplasmic and Extracellular Domains Limit Cellular Cholesterol Accumulation

The low density lipoprotein receptor-related protein 1 (LRP1) is a ubiquitously expressed cell surface receptor that protects from intracellular cholesterol accumulation. However, the underlying mechanisms are unknown. Here we show that the extracellular (α) chain of LRP1 mediates TGFβ-induced enhancement of Wnt5a, which limits intracellular cholesterol accumulation by inhibiting cholesterol biosynthesis and by promoting cholesterol export. Moreover, we demonstrate that the cytoplasmic (β) chain of LRP1 suffices to limit cholesterol accumulation in LRP1(-/-) cells. Through binding of Erk2 to the second of its carboxyl-terminal NPXY motifs, LRP1 β-chain positively regulates the expression of ATP binding cassette transporter A1 (ABCA1) and of neutral cholesterol ester hydrolase (NCEH1). These results highlight the unexpected functions of LRP1 and the canonical Wnt5a pathway and new therapeutic potential in cholesterol-associated disorders including cardiovascular diseases.

Kindlin-2 siRNA inhibits vascular smooth muscle cell proliferation, migration and intimal hyperplasia via Wnt signaling

It is known that vascular smooth muscle cell (VSMC) proliferation and migration leads to intimal hyperplasia in cases of atherosclerosis and restenosis. In the present study, we investigated the effects of kindlin-2 on VSMC proliferation, migration and intimal hyperplasia, and the underlying mechanisms. The left common carotid artery of Sprague‑Dawley rats were subjected to balloon injury in order to induce intimal hyperplasia, and then transfected with kindlin-2 small interfering RNA (siRNA) lentivirus or negative control siRNA lentivirus. We noted that the degree of intimal hyperplasia 4 weeks after balloon injury was significantly reduced in arteries transfected with kindlin-2 siRNA lentivirus (P<0.05). In vitro, kindlin-2 siRNA suppressed VSMC proliferation and migration induced by Wnt3a (100 ng/ml). Western blot analyses and RT-qPCR revealed that kindlin-2 regulated Wnt/β-catenin signaling and thereby modulated the expression of β-catenin target genes, including c-myc and cyclin D1. This study demonstrated that kindlin-2 plays a critical role in VSMC proliferation, migration and intimal hyperplasia via Wnt signaling. Therefore, blocking the activity of kindlin-2 represents a novel therapeutic strategy for vascular injury.

Upregulation of Dickkopf1 by oscillatory shear stress accelerates atherogenesis

Numerous clinical studies have highlighted the pivotal role Dickkopf (DKK) 1 plays in atherosclerosis, but the underlying mechanisms remain unknown. The present study was designed to explore the contribution of DKK1 to the development of atherosclerosis under oscillatory shear stress. Oscillatory shear stress applied to endothelial cells induced DKK1 expression, which peaked at 6 h. siRNA knockdown or silencing DKK1 by lentiviral gene delivery counteracted the increased monocyte adhesion and impaired endothelial tight junction induced by oscillatory shear stress, thereby attenuating atherogenesis in ApoE-/- mice. As well, activation of endothelial proteinase-activated receptor 1 (PAR1) and its downstream transcription factor, cAMP response element-binding protein (CREB), was critical to the increased expression of DKK1 under oscillatory shear stress. We provide evidence that DKK1 contributes to the development of atherosclerosis under conditions of oscillatory shear stress. A better understanding of the role played by DKK1 in atherogenesis may provide clinicians with opportunities to prevent atherosclerosis.

KEY MESSAGE

Disturbed oscillatory flow increases DKK1 expression. DKK1 knockdown attenuates OSS-induced monocyte adhesion and endothelial impairment. Genetic silencing of DKK1 limits atherogenesis in ApoE-/- mice. Activation of the PAR1/CREB pathway contributes to the upregulation of DKK1 via OSS. DKK1 is a promising candidate with respect to the treatment of atherosclerosis.

Wnt signaling in atherosclerosis

Atherosclerosis is a disease of the vascular wall that forms the basis for a large spectrum of pathologies of various organs and tissues. Although massive research efforts in the last decades have yielded valuable information about its underlying molecular mechanisms, this has not led to a translation into effective therapeutic interventions that can stop the progression or even can induce regression of atherosclerosis. This underscores the importance of investigations on the involvement of novel signaling pathways in the development and progression of this condition. In this review we focus on the role of Wnt signaling in atherosclerosis. Experimental evidence is presented that Wnt signaling is involved in many aspects of the development and progression of vascular lesions including endothelial dysfunction, macrophage activation and the proliferation and migration of vascular smooth muscle cells. Subsequently, we will discuss the role of Wnt signaling in myocardial infarction and stroke, two common pathologies resulting from the progression of atherosclerotic lesions towards an unstable phenotype. Despite the fact that the published data sometimes are ambiguous or even conflicting, a picture is emerging that an attenuation of Wnt signaling is beneficial for the cardiovascular system that is compromised by atherosclerosis.

Global gene expression profiling of telangiectasial tissue from patients with hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), the most common inherited vascular disorder, is predominantly caused by mutations in ENG and ACVRL1, which are part of the transforming growth factor beta (TGF-β) signaling pathway. HHT is characterized by the presence of mucocutaneous telangiectases and arteriovenous malformations in visceral organs, primarily the lungs, brain and liver. The most common symptom in HHT is epistaxis originating from nasal telangiectasia, which can be difficult to prevent and can lead to severe anemia. The clinical manifestations of HHT are extremely variable, even within family members, and the exact mechanism of how endoglin and ALK1 haploinsufficiency leads to HHT manifestations remains to be identified.

OBJECTIVES

The purpose of this study was to detect significantly differentially regulated genes in HHT, and try to elucidate the pathways and regulatory mechanisms occurring in the affected tissue of HHT patients, in order to further characterize this disorder and hypothesize on how telangiectases develop. By microarray technology (Agilent G3 Human GE 8x60), we performed global gene expression profiling of mRNA transcripts from HHT nasal telangiectasial (n = 40) and non-telangiectasial (n = 40) tissue using a paired design. Comparing HHT telangiectasial and non-telangiectasial tissue, significantly differentially expressed genes were detected using a paired t-test. Gene set analysis was performed using GSA-SNP. In the group of ENG mutation carriers, we detected 67 differentially expressed mRNAs, of which 62 were down-regulated in the telangiectasial tissue. Gene set analysis identified the gene ontology (GO) terms vasculogenesis, TGF-β signaling, and Wnt signaling as differentially expressed in HHT1. Altered Wnt signaling might be related to HHT pathogenesis and a greater understanding of this may lead to the discovery of therapeutic targets in HHT.

Association of circulating sclerostin with vascular calcification in Afro-Caribbean men

OBJECTIVE

Sclerostin, a Wingless (Wnt) pathway antagonist, is an established regulator of bone mineralization in humans but its potential importance in the regulation of vascular calcification is less clear. Therefore, our objective was to assess the relationship of serum sclerostin levels with coronary and aortic artery calcification (CAC and AAC, respectively) in Afro-Caribbean men on the island of Tobago.

METHODS

Serum sclerostin levels and computed tomography of CAC and AAC were measured in 191 men (age mean(SD): 62.9(8.0)years) recruited without regard to health status. Multivariable logistic regression models were used to assess the cross-sectional association of sclerostin with prevalent arterial calcification.

RESULTS

Mean(SD) sclerostin was 45.2 pmol/L (15.6 pmol/L). After adjusting for risk factors including age, physical and lifestyle characteristics, comorbidities, lipoproteins and kidney function, 1 SD greater sclerostin level was associated with a 1.61-times (95%CI 1.02-2.53) greater odds of having CAC. Sclerostin was not associated with AAC in any model.

CONCLUSIONS

This is the first study to show that, among Afro-Caribbean men, greater serum sclerostin concentrations were associated with prevalence and extent of CAC. Further studies are needed to better define the role of the Wnt signaling pathway in arterial calcification in humans.