Wnt5a, TLR2 and TLR4 are elevated in advanced human atherosclerotic lesions

Significance of the Wnt signaling pathway in coronary artery atherosclerosis

Introduction

The progression of coronary atherosclerosis is an active and regulated process. The Wnt signaling pathway is thought to play an active role in the pathogenesis of several cardiovascular diseases; however, a better understanding of this system in atherosclerosis is yet to be unraveled.

Methods

In this study, real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting were used to quantify the expression of Wnt3a, Wnt5a, and Wnt5b in the human coronary plaque, and immunohistochemistry was used to identify sites of local expression. To determine the pathologic significance of increased Wnt, human vascular smooth muscle cells (vSMCs) were treated with Wnt3a, Wnt5a, and Wnt5b recombinant proteins and assessed for changes in cell differentiation and function.

Results

RT-PCR and Western blotting showed a significant increase in the expression of Wnt3a, Wnt5a, Wnt5b, and their receptors in diseased coronary arteries compared with that in non-diseased coronary arteries. Immunohistochemistry revealed an abundant expression of Wnt3a and Wnt5b in diseased coronary arteries, which contrasted with little or no signals in normal coronary arteries. Immunostaining of Wnt3a and Wnt5b was found largely in inflammatory cells and myointimal cells. The treatment of vSMCs with Wnt3a, Wnt5a, and Wnt5b resulted in increased vSMC differentiation, migration, calcification, oxidative stress, and impaired cholesterol handling.

Conclusions

This study demonstrates the upregulation of three important members of canonical and non-canonical Wnt signaling pathways and their receptors in coronary atherosclerosis and shows an important role for these molecules in plaque development through increased cellular remodeling and impaired cholesterol handling.

Atherosclerosis and Toll-Like Receptor4 (TLR4), Lectin-Like Oxidized Low-Density Lipoprotein-1 (LOX-1), and Proprotein Convertase Subtilisin/Kexin Type9 (PCSK9)

Atherosclerosis is a leading cause of death in the world. A significant body of evidence suggests that inflammation and various players are implicated and have pivotal roles in the formation of atherosclerotic plaques. Toll-like receptor 4 (TLR4) is linked with different stages of atherosclerosis. This receptor is highly expressed in the endothelial cells (ECs) and atherosclerotic plaques. TLR4 activation can lead to the production of inflammatory cytokines and related responses. Lectin-like oxidized low-density lipoprotein-1 (LOX-1), an integral membrane glycoprotein with widespread expression on the ECs, is involved in atherosclerosis and has some common pathways with TLR4 in atherosclerotic lesions. In addition, proprotein convertase subtilisin/kexin type9 (PCSK9), which is a regulatory enzyme with different roles in cholesterol uptake, is implicated in atherosclerosis. At present, TLR4, PCSK9, and LOX-1 are increasingly acknowledged as key players in the pathogenesis of atherosclerotic cardiovascular diseases. Herein, we presented the current evidence on the structure, functions, and roles of TLR4, PCSK9, and LOX-1 in atherosclerosis.

Wnt Signaling in Atherosclerosis: Mechanisms to Therapeutic Implications

Atherosclerosis is a vascular disease in which inflammation plays a pivotal role. Receptor-mediated signaling pathways regulate vascular inflammation and the pathophysiology of atherosclerosis. Emerging evidence has revealed the role of the Wnt pathway in atherosclerosis progression. The Wnt pathway influences almost all stages of atherosclerosis progression, including endothelial dysfunction, monocyte infiltration, smooth muscle cell proliferation and migration, and plaque formation. Targeting the Wnt pathway to treat atherosclerosis represents a promising therapeutic approach that remains understudied. Blocking Wnt signaling utilizing small molecule inhibitors, recombinant proteins, and/or neutralizing antibodies ameliorates atherosclerosis in preclinical models. The Wnt pathway can be potentially manipulated through targeting Wnt ligands, receptors, co-receptors, and downstream signaling molecules. However, there are challenges associated with developing a real world therapeutic compound that targets the Wnt pathway. This review focuses on the role of Wnt signaling in atherosclerosis development, and the rationale for targeting this pathway for the treatment of atherosclerosis.

The inhibition of Wnt signaling attenuates RANKL-induced osteoclastogenic macrophage activation

Abdominal aortic aneurysms (AAAs) have been linked to the activation of osteoclastogenic macrophages. Reports have suggested that Wnt signaling has a dual effect of proliferation and differentiation during osteoclastogenesis. The Wnt/β-Catenin pathway is a critical regulator of cell pluripotency, cell survival, and cell fate decisions. It regulates cell proliferation and differentiation through transcriptional co-activators, CBP, and p300, respectively. The inhibition of β-catenin suppresses proliferation but induces differentiation of osteoclast precursor cells. This study aimed to examine the effect of ICG-001, a β-catenin/CBP-specific Wnt signaling inhibitor, on osteoclastogenesis by inhibiting proliferation without inducing differentiation. To induce osteoclastogenesis, RAW 264.7 macrophages were stimulated with a soluble receptor activator of NF-κB ligand (RANKL). The effect of Wnt signaling inhibition was examined by treating macrophages with or without ICG-001 during RANKL stimulation. The activation and differentiation of macrophages were examined through western blotting, quantitative PCR, and tartrate-resistant acid phosphate (TRAP) staining in vitro. The relative expression level of the nuclear factor of activated T-cells cytoplasmic 1 protein was significantly suppressed by ICG-001 treatment. The relative expression levels of mRNA of TRAP, cathepsin K, and matrix metalloproteinase-9 were significantly lower in the ICG-001-treated group. The number of TRAP-positive cells decreased in the ICG-001-treated group relative to the non-treated group. The inhibition of Wnt signaling pathway via ICG-001 suppressed osteoclastogenic macrophage activation. Our previous studies have shown the importance of osteoclastogenic macrophage activation in AAA. Further research to examine the therapeutic potential of ICG-001 on AAA is warranted.

Correlation between serum Dickkopf-1 (DKK1) levels and coronary artery stenosis

BACKGROUND AND AIMS

To study the correlation between the level of serum Dickkopf-1 (DKK1) and the degree of coronary artery stenosis in patients with coronary atherosclerotic heart disease.

METHODS AND RESULTS

In 2018, general data and biochemical indexes of 311 patients who underwent coronary angiography were recorded. Before procedure, arterial blood was drawn and the concentrations of DKK1, retinol binding protein 4 (RBP4), plasminogen activator inhibitor (PAI-1) were measured. Based on coronary angiography results, subjects were divided into a coronary heart disease (CHD) group; and a non-coronary heart disease (non-CHD)group. The CHD group was divided into three subgroups: the low Gensini score; the middle Gensini score; and the high Gensini score subgroups. Compared with those of the non-CHD group, DKK1, RBP4 and PAI-1 of the CHD group were significantly higher, while the OC was lower. DKK1,RBP4 and PAI-1 levels of the middle and high Gensini subgroups were significantly higher, compared with that of the low Gensini subgroup. Differences between osteocalcin (OC), beta-isomerized C-terminal telopeptidase (β-CTX), and 25(OH)₂D₃ of the three subgroups were not significant. Correlation between DKK1 and the inflammatory factors, RBP4 and PAI-1, was positive. Correlation between DKK1 and β - CTX, 25(OH)₂D₃ and OC was not significant. DKK1 was a risk factor for CHD. The degree of coronary artery stenosis was related to DKK1 concentration.

CONCLUSIONS

Serum DKK1 levels in coronary heart disease patients were significantly higher, and positively correlated with the degree of coronary artery stenosis. DKK1 level is an independent risk factor for coronary heart disease.

Lipopolysaccharides and Cellular Senescence: Involvement in Atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the vascular walls related to aging. Thus far, the roles of cellular senescence and bacterial infection in the pathogenesis of atherosclerosis have been speculated to be independent of each other. Some types of macrophages, vascular endothelial cells, and vascular smooth muscle cells are in a senescent state at the sites of atherosclerotic lesions. Likewise, bacterial infections and accumulations of lipopolysaccharide (LPS), an outer-membrane component of Gram-negative bacteria, have also been observed in the atherosclerotic lesions of patients. This review introduces the integration of these two potential pathways in atherosclerosis. Previous studies have suggested that LPS directly induces cellular senescence in cultured monocytes/macrophages and vascular cells. In addition, LPS enhances the inflammatory properties (senescence-associated secretory phenotype [SASP]) of senescent endothelial cells. Thus, LPS derived from Gram-negative bacteria could exaggerate the pathogenesis of atherosclerosis by inducing and enhancing cellular senescence and the SASP-associated inflammatory properties of specific vascular cells in atherosclerotic lesions. This proposed mechanism can provide novel approaches to preventing and treating this common age-related disease.

WNT-5a and SOST Levels in Gingival Crevicular Fluid Depend on the Inflammatory and Osteoclastogenic Activities of Periodontal Tissues

Background and Objectives: Wnt signaling leads to stimulation of osteoblasts and it reduces osteoclastogenesis and bone resorption via the regulation of the osteprotegrin and receptor activator of nuclear factor kappa-Β ligan (RANKL). Wnt signaling pathways are regulated by their physiological antagonists such as sclerostin (SOST) as well as WNT-5a. The aim of this study was to determine the total amount of Sclerostin and WNT-5a in the gingival crevicular fluid (GCF) in sites with a continuum from a healthy to diseased periodontium. Materials and Methods: In this cross-sectional study, a total of 20 patients with generalized periodontitis, 10 subjects with gingivitis as well as 14 individuals with a healthy periodontium were recruited upon clinical and radiographic periodontal examination. In patients diagnosed with periodontitis, GCF samples were collected from periodontitis, gingivitis and healthy sites, while gingivitis patients provided samples from gingivitis and healthy sites. In healthy patients, only healthy sites were sampled. Protein total amount of SOST and WNT-5a were quantified by sandwich enzyme-linked immunosorbent assay (ELISA). Results: A total of 108 GCF samples were collected from a total of 44 individuals. When all periodontitis (n = 51), gingivitis (n = 12) and healthy (n = 45) sites were analyzed regardless of the patient diagnosis, periodontitis sites demonstrated significantly elevated WNT-5a total amounts (p = 0.03) when compared to gingivitis sites. Gingivitis sites demonstrated a trend of more total SOST (p = 0.09) when compared to periodontitis and healthy sites. Within each patient diagnostic category, sites showed similar SOST and WNT-5a total amounts (p > 0.05). Conclusions: WNT-5a levels in GCF depend on the stage of periodontitis sites. SOST trended higher in the GCF of gingivitis sites but similar in chronic periodontitis and healthy sites. WNT-5a and SOST play a crucial role in periodontal tissue remodeling and depend on the inflammatory and osteoclastogenic activities.

Regulatory T Cell-Related Gene Biomarkers in the Deterioration of Atherosclerosis

Background: Regulatory T cells (Tregs) have shown to be protective against the development of atherosclerosis, a major pathological cause for cardiovascular events. Here, we aim to explore the roles of Tregs-related genes in atherosclerosis deterioration. Methods and Results: We downloaded the gene expression profile of 29 atherosclerotic samples from the Gene Expression Omnibus database with an accession number of GSE28829. The abundance of Tregs estimated by the CIBERSORT algorithm was negatively correlated with the atherosclerotic stage. Using the limma test and correlation analysis, a total of 159 differentially expressed Tregs-related genes (DETregRGs) between early and advanced atherosclerotic plaques were documented. Functional annotation analysis using the DAVID tool indicated that the DETregRGs were mainly enriched in inflammatory responses, immune-related mechanisms, and pathways such as complement and coagulation cascades, platelet activation, leukocyte trans-endothelial migration, vascular smooth muscle contraction, and so on. A protein-protein interaction network of the DETregRGs was then constructed, and five hub genes (PTPRC, C3AR1, CD53, TLR2, and CCR1) were derived from the network with node degrees ≥20. The expression patterns of these hub DETregRGs were further validated in several independent datasets. Finally, a single sample scoring method was used to build a gene signature for the five DETregRGs, which could distinguish patients with myocardial infarction from those with stable coronary disease. Conclusion: The results of this study will improve our understanding about the Tregs-associated molecular mechanisms in the progression of atherosclerosis and facilitate the discovery of novel biomarkers for acute cardiovascular events.

miR-141-3p Reduces Cell Migration and Proliferation in an In Vitro Modelof Atherosclerosis by Targeting Wnt5a

BACKGROUND

Atherosclerosis (AS) is a type of chronic vascular disease that is also a leading cause of numerous cardiovascular diseases in humans. The biomolecules responsible for the roles of microRNA (miR)-141-3p during AS development are less understood.

METHODS

The relation between Wnt5a and miR-141-3p was predicted using bioinformatics software TargetScan 7.1, and confirmed via dual luciferase reporter assay. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunoblotting were conducted for examining miR-141-3p and Wingless and Int-1 (Wnt)5a expression levels. Additionally, transwell migration and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays were conducted for analyzing cell migration and proliferation, respectively.

RESULTS

miR-141-3p was decreased in oxidized low-density lipoprotein (ox-LDL)-treated human vascular smooth muscle cells (VSMCs). Pretreatment with miR-141-3p mimic inhibited cell migration and proliferation in ox-LDL-induced VSMCs. Wnt5a was verified to act as the target of miR-141-3p in VSMCs. pcDNA3-Wnt5a partially reversed the effects of miR-141-3p mimic in ox-LDL-stimulated VSMCs.

CONCLUSION

miR-141-3p mimic decreased the damage in an AS model by targeting Wnt5a, thereby presenting a novel potential therapeutic target for treating AS.

The Interplay of WNT and PPARγ Signaling in Vascular Calcification

Vascular calcification (VC), the ectopic deposition of calcium phosphate crystals in the vessel wall, is one of the primary contributors to cardiovascular death. The pathology of VC is determined by vascular topography, pre-existing diseases, and our genetic heritage. VC evolves from inflammation, mediated by macrophages, and from the osteochondrogenic transition of vascular smooth muscle cells (VSMC) in the atherosclerotic plaque. This pathologic transition partly resembles endochondral ossification, involving the chronologically ordered activation of the β-catenin-independent and -dependent Wingless and Int-1 (WNT) pathways and the termination of peroxisome proliferator-activated receptor γ (PPARγ) signal transduction. Several atherosclerotic plaque studies confirmed the differential activity of PPARγ and the WNT signaling pathways in VC. Notably, the actively regulated β-catenin-dependent and -independent WNT signals increase the osteochondrogenic transformation of VSMC through the up-regulation of the osteochondrogenic transcription factors SRY-box transcription factor 9 (SOX9) and runt-related transcription factor 2 (RUNX2). In addition, we have reported studies showing that WNT signaling pathways may be antagonized by PPARγ activation via the expression of different families of WNT inhibitors and through its direct interaction with β-catenin. In this review, we summarize the existing knowledge on WNT and PPARγ signaling and their interplay during the osteochondrogenic differentiation of VSMC in VC. Finally, we discuss knowledge gaps on this interplay and its possible clinical impact.

Oxidized Low-Density Lipoprotein Induces WNT5A Signaling Activation in THP-1 Derived Macrophages and a Human Aortic Vascular Smooth Muscle Cell Line

The pathogenesis of atherosclerosis is complex, evolves, and involves many cell types. Macrophages and vascular smooth muscle cells (VSMCs) are critically involved in atherosclerosis development and progression. Several studies have shown that WNT5A protein is abundantly expressed in human atherosclerotic lesions; however, the mechanism and role of WNT signaling pathway activation is not clearly known. Using THP-1 derived macrophages, and human aortic VSMC cells, we evaluated in vitro how oxidized low-density lipoprotein (oxLDL) and WNT5A signaling interact in these two cell lines. We used western blot, scratch assay, metabolic proliferation assay, as well as immunostaining to analyze the effect of Wnt signaling activation. The results demonstrated that oxLDL, as well as WNT5A (control), induced Disheveled-2 (DVL2) activation and Kif26b degradation, indicating activation of non-canonical Wnt signaling. We found that oxLDL and WNT5A induced FZD5-ROR2 co-localization at the cellular membrane in vitro in THP-1 derived macrophages. Box5 (FZD5 receptor antagonist) inhibited oxLDL-induced DVL2/JNK activation secondary to newly secreted WNT protein from THP-1 derived macrophages. We found that WNT3A (canonical Wnt) and WNT5A showed different roles in this VSMC cell line. These findings indicate that WNT5A is upregulated by oxLDL, promotes foam cell formation, and affects VSMC phenotype and migration in these two cell lines. Also, in these cell lines FZD5 signaling seems to be necessary for lipid accumulation and, through this mechanism, WNT5A could modulate foam cell formation. Thus, our results suggest that WNT5A may contribute to the pathogenesis of vascular disease through modulating macrophage and VSMC behavior.

Adipokines: New Potential Therapeutic Target for Obesity and Metabolic, Rheumatic, and Cardiovascular Diseases

Besides its role as an energy storage organ, adipose tissue can be viewed as a dynamic and complex endocrine organ, which produces and secretes several adipokines, including hormones, cytokines, extracellular matrix (ECM) proteins, and growth and vasoactive factors. A wide body of evidence showed that adipokines play a critical role in various biological and physiological functions, among which feeding modulation, inflammatory and immune function, glucose and lipid metabolism, and blood pressure control. The aim of this review is to summarize the effects of several adipokines, including leptin, diponectin, resistin, chemerin, lipocalin-2 (LCN2), vaspin, omentin, follistatin-like 1 (FSTL1), secreted protein acidic and rich in cysteine (SPARC), secreted frizzled-related protein 5 (SFRP5), C1q/TNF-related proteins (CTRPs), family with sequence similarity to 19 member A5 (FAM19A5), wingless-type inducible signaling pathway protein-1 (WISP1), progranulin (PGRN), nesfatin-1 (nesfatin), visfatin/PBEF/NAMPT, apelin, retinol binding protein 4 (RPB4), and plasminogen activator inhibitor-1 (PAI-1) in the regulation of insulin resistance and vascular function, as well as many aspects of inflammation and immunity and their potential role in managing obesity-associated diseases, including metabolic, osteoarticular, and cardiovascular diseases.

Newly Discovered Adipokines: Pathophysiological Link Between Obesity and Cardiometabolic Disorders

With the increasing prevalence of obesity, obesity-related problems such as cardiometabolic disorders (CMD), are also rapidly increasing. To prevent and alleviate the progressive course of CMD, it is important to discover the pathophysiological mechanisms between obesity and CMD. Adipose tissue is now recognized as an active endocrine organ that releases adipokines. Adipokines play a pivotal role in chronic low-grade inflammation, oxidative stress, and impaired insulin signaling, contributing to metabolic derangement and leading to CMD. Recent studies have provided substantial evidence supporting the association between adipokines and CMD. In this review, we highlight the pathophysiological action of adipokines in CMD that includes metabolic syndrome, type 2 diabetes, non-alcoholic fatty liver disease, and cardiovascular diseases. We focused on translational and clinical research of novel adipokines associated with metabolic and cardiovascular regulation. Exploration of the role of these adipokines connecting obesity and CMD may provide a perspective on adipokine-based therapeutic implications for CMD.

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.

Research update on the association between SFRP5, an anti-inflammatory adipokine, with obesity, type 2 diabetes mellitus and coronary heart disease

Secreted frizzled-related protein 5 (SFRP5), an anti-inflammatory adipokine secreted by adipocytes, has been demonstrated to exert its anti-inflammatory effect via antagonizing the non-canonical wingless-type family member 5A (WNT5A) signalling pathways. The WNT5A protein, as a potent pro-inflammatory signalling molecule, is strongly involved in a variety of inflammatory disorders such as obesity, type 2 diabetes mellitus (T2DM) and atherosclerosis. In this review, we systematically outlined the current understanding on the roles of SFRP5 in the pathogenesis of three inflammatory diseases including obesity, T2DM and coronary heart disease (CHD). Our review might stimulate future research using SFRP5 as a promising novel therapeutic target for the treatment of obesity, T2DM and CHD.

Expression of Sfrp5/Wnt5a in human epicardial adipose tissue and their relationship with coronary artery disease

Secreted frizzled-related protein 5 (Sfrp5) primarily acts in combination with wingless-type family member 5a (Wnt5a), to inhibits chronic inflammation and repress atherosclerosis and other metabolic disorders. Epicardial adipose tissue (EAT), surrounding the heart and coronary arteries, has been found to be highly related to the progression of coronary artery disease through adipokines production. However, little is known about EAT-derived Sfrp5 and Wnt5a in humans. We aimed to investigate whether the EAT-derived Sfrp5/Wnt5a levels are altered in patients with CAD. Fifty-eight patients with CAD and 29 patients without CAD who underwent cardiac surgery were enrolled. Serum samples and paired adipose biopsies from EAT and subcutaneous adipose tissue (SAT) were collected, and Sfrp5 and Wnt5a levels were detected. Correlation and multivariate regression analyses were performed to determine the relationship between Sfrp5/Wnt5a expression and CAD and other clinical risk factors. According to the results, the CAD group had lower Sfrp5 and higher Wnt5a levels in EAT and serum (all p < 0.05). Serum Sfrp5 levels were significantly lower in CAD patients with impaired myocardial function. EAT Sfrp5 mRNA levels and serum Sfrp5 levels were both negatively associated with the presence of CAD, after adjustment for known biomarkers, EAT mRNA and serum Wnt5a levels correlated positively with the presence of CAD. Thus, we concluded that low Sfrp5 and high Wnt5a levels are associated with the presence of CAD, independent of other conventional risk factors.

Role of the Wnt signalling pathway in the development of endothelial disorders in response to hyperglycaemia

INTRODUCTION

Diabetes mellitus (DM) is the most common metabolic disease. A WHO report from 2016 indicates that 422 million people worldwide suffer from DM or hyperglycaemia because of impaired glucose metabolism. Chronic hyperglycaemia leads to micro- and macrovessel damage, which may result in life-threatening complications. The Wnt pathway regulates cell proliferation and survival by modulating the expression of genes that control cell differentiation. Three linked Wnt pathways have been discovered thus far: a β-catenin-dependent pathway and two pathways independent of β-catenin - the planar cell polarity pathway and calcium-dependent pathway. The Wnt pathway regulates genes associated with inflammation, cell cycle, angiogenesis, fibrinolysis and other molecular processes.

AREAS COVERED

This review presents the current state of knowledge regarding the contribution of the Wnt pathway to endothelial ageing under hyperglycaemic conditions and provides new insights into the molecular basis of diabetic endothelial dysfunction.

CONCLUSION

The β-catenin-dependent pathway is a potential target in the prophylaxis and treatment of early-stage diabetes-related vascular complications. However, the underlying molecular mechanisms remain largely undetermined and require further investigation.

WNT Signaling in Disease

Developmental signaling pathways control a vast array of biological processes during embryogenesis and in adult life. The WNT pathway was discovered simultaneously in cancer and development. Recent advances have expanded the role of WNT to a wide range of pathologies in humans. Here, we discuss the WNT pathway and its role in human disease and some of the advances in WNT-related treatments.

Sfrp5/Wnt Pathway: A Protective Regulatory System in Atherosclerotic Cardiovascular Disease

Adipose tissue stores energy and is the largest endocrine organ in the body, producing several adipokines. However, among these adipokines, few play a role in the positive metabolism that promotes good health. Secreted frizzled-related protein (Sfrp)-5, an antagonist that directly binds to Wnt, has attracted interest due to its favorable effects on atherosclerotic cardiovascular disease (ASCVD). This review focuses on Sfrp5 biology and the roles of the Sfrp5/Wnt system in ASCVD.

Sphingomyelin Synthase 2 Promotes Endothelial Dysfunction by Inducing Endoplasmic Reticulum Stress

Endothelial dysfunction (ED) is an important contributor to atherosclerotic cardiovascular disease. Our previous study demonstrated that sphingomyelin synthase 2 (SMS2) promotes ED. Moreover, endoplasmic reticulum (ER) stress can lead to ED. However, whether there is a correlation between SMS2 and ER stress is unclear. To examine their correlation and determine the detailed mechanism of this process, we constructed a human umbilical vein endothelial cell (HUVEC) model with SMS2 overexpression. These cells were treated with 4-PBA or simvastatin and with LiCl and salinomycin alone. The results showed that SMS2 can promote the phosphorylation of lipoprotein receptor-related protein 6 (LRP6) and activate the Wnt/β-catenin pathway and that activation or inhibition of the Wnt/β-catenin pathway can induce or block ER stress, respectively. However, inhibition of ER stress by 4-PBA can decrease ER stress and ED. Furthermore, when the biosynthesis of cholesterol is inhibited by simvastatin, the reduction in intracellular cholesterol coincides with a decrease in ER stress and ED. Collectively, our results demonstrate that SMS2 can activate the Wnt/β-catenin pathway and promote intracellular cholesterol accumulation, both of which can contribute to the induction of ER stress and finally lead to ED.

Cardiovascular Outcomes of Romosozumab and Protective Role of Alendronate

Osteoporosis and cardiovascular diseases are major public health issues. Bone and cardiovascular remodeling share multiple biological markers and pathways. Medical intervention, such as using romosozumab, an antisclerostin antibody, improves the clinical outcome of osteoporosis. However, blocking sclerostin leads to Wnt (wingless/integrated) activation and participation in the cardiovascular remodeling process, which could potentially lead to adverse events. Based on the opposing roles of bisphosphonates and the Wnt pathway on endothelial dysfunction, lipid accumulation and calcification of the vessel walls, the combination of romosozumab and bisphosphonates could be a new therapeutic approach to reducing the risks of adverse cardiovascular events in romosozumab receivers. Visual Overview- An online visual overview is available for this article.

Fine-particulate matter aggravates cigarette smoke extract-induced airway inflammation via Wnt5a-ERK pathway in COPD

Background

Exposure to environmental particulate matter (PM) ≤2.5 μm in diameter (PM_2.5) and smoking are common contributors to COPD, and pertinent research implicates both factors in pulmonary inflammation. Using in vivo mouse and in vitro human cellular models, we investigated the joint impact of PM_2.5 pollution, and cigarette smoke (CS) in mice or cigarette-smoke extract (CSE) in cells on COPD inflammation, and explored potential mechanisms.

Methods

Tissue changes in lungs of C57BL/6 mice exposed to PM_2.5 and CS were studied by light microscopy, H&E, immunochemistry, and immunofluorescence-stained sections. Levels of inflammatory factors induced by PM_2.5/CS in mice and PM_2.5/CSE in 16HBE cells were also monitored by quantitative reverse-transcription (qRT)-PCR and ELISA. Expression of genes related to the Wnt5a-signaling pathway was assessed at transcriptional and protein levels using immunofluorescence, qRT-PCR, and Western blotting.

Results

Inflammatory response to combined exposure of PM_2.5 and CS or CSE in mouse and 16HBE cells surpassed responses incited separately. Although separate PM_2.5 and CS/CSE exposure upregulated the expression of Wnt5a (a member of the Wnt-secreted glycoprotein family), combined PM_2.5 and CS/CSE exposure produced a steeper rise in Wnt5a levels. Use of a Wnt5a antagonist (BOX5) successfully blocked related inflammatory effects. ERK phosphorylation appeared to mediate the effects of Wnt5a in the COPD model, promoting PM_2.5 aggravation of CS/CSE-induced airway inflammation.

Conclusion

Our findings suggest that combined PM_2.5 and CS/CSE exposure induce airway inflammation and Wnt5a expression in vivo in mice and in vitro in 16HBE cells. Furthermore, PM_2.5 seems to aggravate CS/CSE-induced inflammation via the Wnt5a–ERK pathway in the context of COPD.

Cinnamon extract combined with high-intensity endurance training alleviates metabolic syndrome via non-canonical WNT signaling

OBJECTIVES

The incidence of metabolic syndrome (MetS) in menopausal women is one of the main health care concerns. MetS clusters are related to an imbalance in pro- and anti-inflammatory adipokines such as secreted frizzled-related protein 5 (SFRP5) and wingless-type mammary tumor virus integration site family, member 5A (WNT5A). WNT5A induces an inflammatory state to induce insulin resistance and further pathologic consequences. Recent strategies to prevent progression of MetS to diabetes have focused on conservative treatments such as exercise and herbal medicine. The aim of this study was to investigate the mechanistic effects of cotreatment with cinnamon extract and 12-wk high-intensity endurance training on MetS components considering the non-canonical WNT5A signaling.

METHOD

Thirty-two female ovariectomized Wistar rats were divided into the following four groups (n = 8/group): exercise (Ova+Exe), cinnamon extract (Ova+Cin), exercise with cinnamon extract (Ova+Exe+Cin) and saline (Ova+Sal). One group of rats undergoing surgery without removal of the ovaries was considered as a sham. After 3 mo of experimental intervention, waist circumference, serum concentrations of glucose, insulin, lipid profile, tumor necrosis factor-α, WNT5A, and SFRP5 were measured.

RESULTS

Data showed a significant reduction in serum glucose, low-density lipoprotein, homeostasis model assessment estimate of insulin resistance, and tumor necrosis factor-α, but an increase in SFRP5 level in Ova+Exe, Ova+Cin and Ova +Exe+Cin groups compared with Ova+Sal group (P < 0.05). Serum WNT5A significantly was reduced only in Ova+Exe+Cin group (P = 0.02).

CONCLUSION

The present study indicated that high-endurance training combined with aqueous cinnamon extract supplementation for 12 wk more efficiently alleviated insulin resistance and metabolic dysfunctions via reduction in noncanonical WNT signaling in ovariectomized rats.

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.

Effect of SFRP5 (Secreted Frizzled-Related Protein 5) on the WNT5A (Wingless-Type Family Member 5A)-Induced Endothelial Dysfunction and Its Relevance With Arterial Stiffness in Human Subjects

OBJECTIVE

SFRP5 (secreted frizzled-related protein 5) is an endogenous inhibitor of WNT5A (wingless-type family member 5a), which has been implicated in atherosclerosis. However, contradictory results have been reported about the role of SFRP5 in atherosclerosis. We aimed to investigate whether SFRP5 could restore WNT5A-induced endothelial dysfunction in vitro and ex vivo. In addition, we sought to determine whether the serum concentration of SFRP5 is associated with atherosclerosis in humans.

APPROACH AND RESULTS

We measured endothelium-dependent vasorelaxation in the isolated thoracic aorta of Sprague-Dawley rats. In addition, we measured intracellular nitric oxide (NO) in human endothelial cells. The protein abundance of total and phosphorylated JNK (c-Jun N-terminal kinase), AKT (protein kinase B), and endothelial NO synthase was analyzed in human endothelial cells. Circulating SFRP5 and WNT5A levels and brachial-ankle pulse wave velocity were measured in 282 human subjects with type 2 diabetes mellitus. SFRP5 dose dependently restored Wnt5-induced impaired vasorelaxation in rat thoracic aorta by an endothelial NO synthase-dependent mechanism. SFRP5 treatment restored the WNT5A-induced reduction of NO production via endothelial NO synthase in human endothelial cells. WNT5A-induced changes in the phosphorylation of JNK, AKT, and endothelial NO synthase were ameliorated with SFRP5 administration. In humans with type 2 diabetes mellitus, the serum SFRP5 concentration positively correlated with brachial-ankle pulse wave velocity (r=0.146; P=0.024). Multivariate linear regression analysis demonstrated that the serum SFRP5 concentration was independently associated with brachial-ankle pulse wave velocity after adjustment for potential confounders [B (SE)=7.40 (3.35); P=0.028].

CONCLUSIONS

Our data suggest the possible compensatory action of SFRP5 against atherosclerosis under conditions of metabolic dysfunction.

Inflammation: A Novel Therapeutic Target/Direction in Atherosclerosis

Over the past two decades, the viewpoint of atherosclerosis has been replaced gradually by a lipid-driven, chronic, low-grade inflammatory disease of the arterial wall. Current treatment of atherosclerosis is focused on limiting its risk factors, such as hyperlipidemia or hypertension. However, treatment targeting the inflammatory nature of atherosclerosis is still very limited and deserves further attention to fight atherosclerosis successfully. Here, we review the current development of inflammation and atherosclerosis to discuss novel insights and potential targets in atherosclerosis, and to address drug discovery based on anti-inflammatory strategy in atherosclerotic disease.

Circulating Wnt inhibitory factor 1 levels are associated with development of cardiovascular disease

BACKGROUND AND AIMS

Wnt signaling is involved in atherosclerotic plaque formation directly and indirectly by modulating cardiovascular risk factors. We investigated whether circulating concentrations of Wnt inhibitors are associated with cardiovascular events in subjects with intermediate cardiovascular risk.

METHODS

904 non-diabetic subjects participating in the SAPHIR study were assessed. In the SAPHIR study, middle-aged women without overt atherosclerotic disease at study entry were followed up for 10 years. 88 patients of our study cohort developed cardiovascular disease at follow-up (CVD group). Subjects of the CVD group were 1:2 case-control matched for age, sex, BMI and smoking behavior with subjects without overt cardiovascular disease after a 10 year-follow-up (control group). 18 patients of the CVD group and 19 subjects of the control group were retrospectively excluded due to fulfilling exclusion criteria. Baseline circulating sclerostin, dickkopf (DKK)-1, secreted frizzled-related protein (SFRP)-1 and Wnt inhibitory factor (WIF)-1 levels were assessed by ELISA.

RESULTS

Baseline systemic SFRP-1 and WIF-1 levels were significantly higher in patients with cardiovascular events (n = 70) when compared to healthy controls (n = 157) while DKK-1 and sclerostin levels were similar in both groups. Logistic regression analysis revealed WIF-1 as a significant predictor of future cardiovascular events.

CONCLUSIONS

Our data suggest that increased SFRP-1 and WIF-1 levels precede the development of symptomatic atherosclerotic disease. Assessment of systemic WIF-1 levels, which turned out to be independently associated with CVD, might help to early identify patients at intermediate cardiovascular risk.

Blocking Wnt5a signaling decreases CD36 expression and foam cell formation in atherosclerosis

BACKGROUND AND AIMS

Wnt5a is a highly studied member of the Wnt family and recently has been implicated in the pathogenesis of atherosclerosis, but its precise role is unknown. Foam cell development is a critical process to atherosclerotic plaque formation. In the present study, we investigated the role of noncanonical Wnt5a signaling in the development of foam cells.

METHODS

Human carotid atherosclerotic tissue and THP-1-derived macrophages were used to investigate the contribution of Wnt5a signaling in the formation of foam cells. Immunohistochemistry was used to evaluate protein expression of scavenger receptors and noncanonical Wnt5a receptors [frizzled 5 (Fz5) and receptor tyrosine kinase-like orphan receptor 2 (Ror2)] in human atherosclerotic macrophages/foam cells. Changes in protein expression in response to Wnt5a stimulation/inhibition were determined by Western blot, and lipid accumulation was evaluated by fluorescent lipid droplet staining.

RESULTS

Wnt5a (P<.05), Fz5 (P<.01), and Ror2 (P<.01) were significantly expressed in advanced atherosclerotic lesions compared to less advanced lesions (N=10). Wnt5a, Fz5, and Ror2 were expressed in macrophages/foam cells within the plaque. In vitro studies revealed that Wnt5a significantly increased the expression of the lipid uptake receptor CD36 (P<.05) but not the lipid efflux receptor ATP-binding cassette transporter (P>.05). rWnt5a also significantly increased lipid accumulation in THP-1 macrophages (P<.05). Furthermore, inhibition of Wnt5a signaling with Box5 prevented lipid accumulation (P<.01) and prevented CD36 up-regulation (P<.01).

CONCLUSIONS

These results suggest a direct role for Wnt5a signaling in the pathogenesis of atherosclerosis, specifically the accumulation of lipid in macrophages and the formation of foam cells.

Biological functions of macrophage-derived Wnt5a, and its roles in human diseases

Wnt5a is implicated in development and tissue homeostasis by activating β-catenin-independent pathway. Excessive production of Wnt5a is related to some human diseases. Macrophage recruitment is a character of inflammation and cancer, therefore macrophage-derived Wnt5a is supposed to be a player in these conditions. Actually, macrophage-derived Wnt5a maintains macrophage immune function, stimulates pro-inflammatory cytokine release, and induces angiogenesis and lymphangiogenesis. Furthermore, macrophage-derived Wnt5a is involved in insulin resistance, atherosclerosis and cancer. These findings indicate that macrophage-derived Wnt5a may be a target in the treatment of these diseases. Notably, unlike macrophages, the exact role of macrophage-derived Wnt5a in bacterial infection remains largely unknown.

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.

Interrelationship of canonical and non-canonical Wnt signalling pathways in chronic metabolic diseases

Chronic diseases account for approximately 45% of all deaths in developed countries and are particularly prevalent in countries with the most sophisticated and robust public health systems. Chronic metabolic diseases, specifically lifestyle-related diseases pertaining to diet and exercise, continue to be difficult to treat clinically. The most prevalent of these chronic metabolic diseases include obesity, diabetes, non-alcoholic fatty liver disease, chronic kidney disease and cardiovascular disease and will be the focus of this review. Wnt proteins are highly conserved glycoproteins best known for their role in development and homeostasis of tissues. Given the importance of Wnt signalling in homeostasis, aberrant Wnt signalling likely regulates metabolic processes and may contribute to the development of chronic metabolic diseases. Expression of Wnt proteins and dysfunctional Wnt signalling has been reported in multiple chronic diseases. It is interesting to speculate about an interrelationship between the Wnt signalling pathways as a potential pathological mechanism in chronic metabolic diseases. The aim of this review is to summarize reported findings on the contrasting roles of Wnt signalling in lifestyle-related chronic metabolic diseases; specifically, the contribution of Wnt signalling to lipid accumulation, fibrosis and chronic low-grade inflammation.

Differential effects of Wnt5a on the proliferation, differentiation and inflammatory response of keratinocytes

The predominant role of Wnt family member 5A (Wnt5a) is to induce non-canonical Wnt signalling pathways, including the Wnt‑Ca2+ and Wnt‑planar cell polarity pathways. Enhanced Wnt5a expression is involved in the formation of psoriatic plaques; however, its mechanistic role remains to be determined. In the present study, the effects of Wnt5a expression on HaCaT keratinocytes were investigated. HaCaT cells were cultured in medium supplemented with 0, 40 or 80 ng/ml Wnt5a for 24 h. Cell proliferation, the cell cycle, gene expression and inflammatory responses were investigated using Cell‑Counting Kit‑8 assays, flow cytometry analyses, reverse transcription‑quantitative polymerase chain reaction analyses and enzyme‑linked immunosorbent assays, respectively. Wnt5a treatment was revealed to suppress cell proliferation in HaCaT cells. Furthermore, Wnt5a was also demonstrated to increase the proportion of HaCaT cells arrested at the G2/M phase of the cell cycle, but reduce the proportion of HaCaT cells arrested at G0/G1 phase cells. In addition, the expression levels of the differentiation markers, including filaggrin, keratin 1 and keratin 10 were revealed to be downregulated in HaCaT cells. Expression of the canonical Wnt signalling genes (β‑catenin and cyclin D1) and proliferation markers, such as Ki‑67 and proliferating cell nuclear antigen in HaCaT cells were also revealed to be downregulated. However, the expression levels of inflammatory response markers (interferon‑γ, interleukin‑8 and interleukin‑17A) were revealed to be upregulated in HaCaT cells following Wnt5a treatment. These findings suggest that Wnt5a expression may be involved in the inhibition of cell differentiation and the induction of an inflammatory response in patients with psoriasis.

Recent advances and clinical insights into the use of proteomics in the study of atherosclerosis

INTRODUCTION

The application of new proteomics methods may help to identify new diagnostic/predictive molecular markers in an attempt to improve the clinical management of atherosclerosis. Areas covered: Technological advances in proteomics have enhanced its sensitivity and multiplexing capacity, as well as the possibility of studying protein interactions and tissue structure. These advances will help us better understand the molecular mechanisms at play in atherosclerosis as a biological system. Moreover, this should help identify new predictive/diagnostic biomarkers and therapeutic targets that may facilitate effective risk stratification and early diagnosis, with the ensuing rapid implementation of treatment. This review provides a comprehensive overview of the novel methods in proteomics, including state-of-the-art techniques, novel biological samples and applications for the study of atherosclerosis. Expert commentary: Collaboration between clinicians and researchers is crucial to further validate and introduce new molecular markers to manage atherosclerosis that are identified using the most up to date proteomic approaches.

WIF1 prevents Wnt5A mediated LIMK/CFL phosphorylation and adherens junction disruption in human vascular endothelial cells

Background

Wnt5A is released by activated macrophages and elevated levels have been detected in sepsis patients with severe systemic inflammation. However, the signalling and functional effects of Wnt5A in the vascular endothelial cells (VEC) remained unclear. Recently, we showed that Wnt5A affects barrier function in human VEC through Ryk interaction. Wnt5A/Ryk signalling activates LIMK to inactivate the actin depolymerisation factor CFL by phosphorylation, promotes actin polymerisation and disrupts endothelial adherens junctions.

Findings

Here, we investigate the antagonistic effect of the Ryk specific secreted Wnt antagonist Wnt inhibitory factor (WIF)-1 on Wnt5A-mediated activation/inactivation of LIMK/CFL, and adherens junction disruption in human VEC. In human coronary artery endothelial cells (HCAEC), treatment with Wnt5A enhanced the phosphorylation of LIMK and CFL that was significantly prevented by WIF1. The presence of WIF1 suppressed Wnt5A-mediated disruption of β-catenin and VE-cadherin adherens junctions in HCAEC, thereby preventing barrier dysfunction caused by Wnt5A.

Conclusion

We conclude that WIF1 or molecules with similar properties could be potent tools for the prevention of vascular leakage due to Wnt5A-mediated actin cytoskeleton remodeling in diseases associated with systemic inflammation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12950-017-0157-4) contains supplementary material, which is available to authorized users.

Dynamic biochemical tissue analysis detects functional L-selectin ligands on colon cancer tissues

A growing body of evidence suggests that L-selectin ligands presented on circulating tumor cells facilitate metastasis by binding L-selectin presented on leukocytes. Commonly used methods for detecting L-selectin ligands on tissues, e.g., immunostaining, are performed under static, no-flow conditions. However, such analysis does not assay for functional L-selectin ligands, specifically those ligands that promote adhesion under shear flow conditions. Recently our lab developed a method, termed dynamic biochemical tissue analysis (DBTA), to detect functional selectin ligands in situ by probing tissues with L-selectin-coated microspheres under hemodynamic flow conditions. In this investigation, DBTA was used to probe human colon tissues for L-selectin ligand activity. The detection of L-selectin ligands using DBTA was highly specific. Furthermore, DBTA reproducibly detected functional L-selectin ligands on diseased, e.g., cancerous or inflamed, tissues but not on noncancerous tissues. In addition, DBTA revealed a heterogeneous distribution of functional L-selectin ligands on colon cancer tissues. Most notably, detection of L-selectin ligands by immunostaining using HECA-452 antibody only partially correlated with functional L-selectin ligands detected by DBTA. In summation, the results of this study demonstrate that DBTA detects functional selectin ligands to provide a unique characterization of pathological tissue.

The Wnt Blows: On the Functional Role of Wnt Signaling in Mycobacterium tuberculosis Infection and Beyond

In recent years, it has become apparent that the Wnt signaling pathway, known for its essential functions in embryonic development and tissue homeostasis, exerts immunomodulatory functions during inflammation and infection. Most functional studies indicate that Wnt5a exerts pro-inflammatory functions on its cellular targets, which include various types of immune and non-immune cells. Wnt5a expression has also been linked to the pathogenesis of chronic inflammatory diseases. Activation of beta-catenin-dependent Wnt signaling, e.g., by Wnt3a, has however been shown to limit inflammation by interfering with the nuclear factor kappa-light chain-enhancer of activated B-cells (NF-kappaB) pathway. This review focuses on the regulation of Wnt5a, Wnt3a, and the recently identified Wnt6 and their functional role in bacterial infections with a primary focus on pulmonary tuberculosis, a leading infectious cause of morbidity and mortality worldwide.

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.

Human miR-221/222 in Physiological and Atherosclerotic Vascular Remodeling

A cluster of miR-221/222 is a key player in vascular biology through exhibiting its effects on vascular smooth muscle cells (VSMCs) and endothelial cells (ECs). These miRNAs contribute to vascular remodeling, an adaptive process involving phenotypic and behavioral changes in vascular cells in response to vascular injury. In proliferative vascular diseases such as atherosclerosis, pathological vascular remodeling plays a prominent role. The miR-221/222 cluster controls development and differentiation of ECs but inhibits their proangiogenic activation, proliferation, and migration. miR-221/222 are primarily implicated in maintaining endothelial integrity and supporting quiescent EC phenotype. Vascular expression of miR-221/222 is upregulated in initial atherogenic stages causing inhibition of angiogenic recruitment of ECs and increasing endothelial dysfunction and EC apoptosis. In contrast, these miRNAs stimulate VSMCs and switching from the VSMC "contractile" phenotype to the "synthetic" phenotype associated with induction of proliferation and motility. In atherosclerotic vessels, miR-221/222 drive neointima formation. Both miRNAs contribute to atherogenic calcification of VSMCs. In advanced plaques, chronic inflammation downregulates miR-221/222 expression in ECs that in turn could activate intralesion neoangiogenesis. In addition, both miRNAs could contribute to cardiovascular pathology through their effects on fat and glucose metabolism in nonvascular tissues such as adipose tissue, liver, and skeletal muscles.

The complement system and toll-like receptors as integrated players in the pathophysiology of atherosclerosis

Despite recent medical advances, atherosclerosis is a global burden accounting for numerous deaths and hospital admissions. Immune-mediated inflammation is a major component of the atherosclerotic process, but earlier research focus on adaptive immunity has gradually switched towards the role of innate immunity. The complement system and toll-like receptors (TLRs), and the crosstalk between them, may be of particular interest both with respect to pathogenesis and as therapeutic targets in atherosclerosis. Animal studies indicate that inhibition of C3a and C5a reduces atherosclerosis. In humans modified LDL-cholesterol activate complement and TLRs leading to downstream inflammation, and histopathological studies indicate that the innate immune system is present in atherosclerotic lesions. Moreover, clinical studies have demonstrated that both complement and TLRs are upregulated in atherosclerotic diseases, although interventional trials have this far been disappointing. However, based on recent research showing an intimate interplay between complement and TLRs we propose a model in which combined inhibition of both complement and TLRs may represent a potent anti-inflammatory therapeutic approach to reduce 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.

TLR4 rs1927911, but not TLR2 rs5743708, is associated with atherosclerotic cerebral infarction in the Southern Han population: a case-control study

The objective of this study was to explore the association of toll-like receptor (TLR) 4 rs1927911 and TLR2 rs5743708 with atherosclerotic cerebral infarction (ACI) and their effects on blood pressure, fasting blood glucose, and blood lipids in the Han population of Hunan Province. TLR4 rs1927911 and TLR2 rs5743708 were detected by polymerase chain reaction and restriction fragment length polymorphism in 170 patients with ACI and 149 healthy controls. Our results indicated that the genotype and allele frequencies of TLR4 rs1927911 were significantly different between ACI patients and controls, whereas those of TLR2 rs5743708 were not significantly different between the 2 groups. For TLR4 rs1927911, blood pressure, fasting blood sugar, and serum lipid levels were not significantly different among different genotypes in the ACI and control groups. The rs1927911 polymorphism of the TLR4 gene may be a risk factor for ACI in the Southern Han population of Hunan Province; however, it may not be associated with blood pressure, fasting blood sugar, or blood lipids.

Wnt5a: a player in the pathogenesis of atherosclerosis and other inflammatory disorders

OBJECTIVE

The objective of this article is to review the current literature on Wnt5a and its signaling mechanism, along with its role in atherosclerosis. In addition, the significance of Wnt5a as a diagnostic marker and a potential therapeutic target is reviewed. Wnt5a, a secreted glycoprotein, belongs to a family of highly conserved proteins that regulate important processes such as cell fate specification, embryonic development, cell proliferation, migration, and differentiation in a variety of organisms. The complexity of Wnt5a signaling lies in the fact that Wnt5a can bind to different classes of frizzled receptors, receptor tyrosine kinase-like orphan receptor 2, as well as co-receptors such as low density lipoprotein receptor-related protein 5/6. Wnt5a signals primarily through the non-canonical pathway, where it mediates cell proliferation, adhesion, and movement. However, the role of Wnt5a in canonical signaling is still unresolved. Depending on the receptor availability, Wnt5a can serve to activate or inhibit the canonical Wnt signaling pathway. Due to the promiscuous nature of Wnt5a, it has been extremely difficult to fully understand its signaling mechanism. Wnt5a has recently emerged as a macrophage effector molecule that triggers inflammation. Perturbations in Wnt5a signaling have been reported in several inflammatory diseases, particularly in sepsis, rheumatoid arthritis, and atherosclerosis.

CONCLUSION

Both existing and emerging evidence suggests that the expression of Wnt5a is always up-regulated in these, and possibly other inflammatory disorders. This knowledge can be useful for targeting Wnt5a and/or its receptor and downstream signaling molecules for therapeutic intervention in inflammatory disorders.

siRNA-mediated silencing of Wnt5a regulates inflammatory responses in atherosclerosis through the MAPK/NF-κB pathways

Previous studies have demonstrated that the aberrant expression of Wnt5a occurs in atherosclerotic lesions. However, the precise role of Wnt5a in the pathogenesis of atherosclerosis remains largely unknown. The present study was undertaken to determine whether the RNA interference of Wnt5a in vivo by adenovirus (Ad)-mediated small interfering RNA (siRNA) transfection is capable of inhibiting the progression of atherosclerosis. Recombinant adenovirus carrying siRNA targeting Wnt5a (Ad-Wnt5a siRNA) was designed. Male apolipoprotein E-deficient (ApoE(-/-)) mice were fed a high-fat diet to induce the pathogenesis of atherosclerosis. Mice were randomly divided into 3 groups (n=15 in each group): the mock group, which received treatment with phosphate-buffered saline (PBS); the Ad-NC group, which received treatment with Ad-non-specific siRNA; and the Ad-Wnt5a siRNA group, which received treatment with Ad-Wnt5a siRNA. Treatment with Ad-Wnt5a siRNA markedly inhibited the mRNA and protein expression of Wnt5a in the aortic tissues. The knockdown of Wnt5a had no significant effect on blood lipid levels, but it suppressed atherosclerotic development and increased plaque stability, which was determined by hematoxylin and eosin staining, picrosirius red staining and Oil Red O staining. Furthermore, the mRNA and protein expression of inflammatory cytokines, including monocyte chemotactic protein-1 (MCP-1), cyclooxygenase-2 (COX-2), matrix metalloproteinase (MMP)-2 and MMP-9 was significantly downregulated in the Ad-Wnt5a siRNA group. In addition, the knockdown of Wnt5a inhibited the nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. These results demonstrate that Ad-mediated Wnt5a silencing in vivo attenuates the development of atherosclerotic disease by reducing inflammatory mediators involved in the MAPK/NF-κB pathways.