Dual role of matrix metalloproteinases (matrixins) in intimal thickening and atherosclerotic plaque rupture

Leptin upregulates smooth muscle cell expression of MMP-9 to promote plaque destabilization by activating AP-1 via the leptin receptor/MAPK/ERK signaling pathways

Leptin has been reported to be expressed in carotid atherosclerotic plaques, where it can promote lesion instability. Matrix metalloproteinases (MMPs) produced by smooth muscle cells (SMCs) are known to contribute to the weakening of atherosclerotic plaques via the degradation of extracellular matrix (ECM) proteins. The present study investigated whether leptin promotes plaque rupture by increasing the expression of MMP in SMCs in vivo and in vitro. In vivo, the neointima/media ratio and expression of MMP in the carotid artery of ob/ob mice were measured following carotid ligation and systemic administration of leptin. In vitro, the effect of leptin treatment on the expression of MMP in isolated SMCs and the underlying signaling pathways were investigated by gelatin zymography and western blot analysis. The results demonstrated that leptin treatment significantly increased the neointima/media ratio and expression of MMP-9 in the carotid artery of mice following carotid ligation. In vitro, leptin also significantly increased the expression and activity of MMP-9 in cultured SMCs in a dose-dependent manner. Leptin also increased the production of MMP-9 by activating leptin receptor and mitogen-activated protein kinases, including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), which in turn enhanced the binding of the transcription factor activator protein-1 (AP-1) to the MMP-9 promoter. The inhibition of leptin-activated phosphorylation of ERK and JNK suppressed the leptin-stimulated expression of AP-1 and MMP-9. Leptin treatment induced the expression of MMP-9 in SMCs, suggesting that leptin may have substantial involvement in plaque rupture by promoting the degradation of ECM.

Mesenchymal Stem Cell Therapy for Ischemic Tissues

Ischemic diseases such as myocardial infarction, ischemic stroke, and critical limb ischemia are immense public health challenges. Current pharmacotherapy and surgical approaches are insufficient to completely heal ischemic diseases and are associated with a considerable risk of adverse effects. Alternatively, human mesenchymal stem cells (hMSCs) have been shown to exhibit immunomodulation, angiogenesis, and paracrine secretion of bioactive factors that can attenuate inflammation and promote tissue regeneration, making them a promising cell source for ischemic disease therapy. This review summarizes the pathogenesis of ischemic diseases, discusses the potential therapeutic effects and mechanisms of hMSCs for these diseases, and provides an overview of challenges of using hMSCs clinically for treating ischemic diseases.

The expression of MMP-1 and MMP-9 is up-regulated by smooth muscle cells after their cross-talk with macrophages in high glucose conditions

Patients with diabetes mellitus have an increased risk of myocardial infarction and coronary artery disease-related death, exhibiting highly vulnerable plaques. Many studies have highlighted the major role of macrophages (MAC) and smooth muscle cells (SMC) and the essential part of metalloproteases (MMPs) in atherosclerotic plaque vulnerability. We hypothesize that in diabetes, the interplay between MAC and SMC in high glucose conditions may modify the expression of MMPs involved in plaque vulnerability. The SMC-MAC cross-talk was achieved using trans-well chambers, where human SMC were grown at the bottom and human MAC in the upper chamber in normal (NG) or high (HG) glucose concentration. After cross-talk, the conditioned media and cells were isolated and investigated for the expression of MMPs, MCP-1 and signalling molecules. We found that upon cross-talk with MAC in HG, SMC exhibit: (i) augmented expression of MMP-1 and MMP-9; (ii) significant increase in the enzymatic activity of MMP-9; (iii) higher levels of soluble MCP-1 chemokine which is functionally active and involved in MMPs up-regulation; (iv) activated PKCα signalling pathway which, together with NF-kB are responsible for MMP-1 and MMP-9 up-regulation, and (v) impaired function of collagen assembly. Taken together, our data indicate that MCP-1 released by cell cross-talk in diabetic conditions binds to CCR2 and triggers MMP-1 and MMP-9 over-expression and activity, features that could explain the high vulnerability of atherosclerotic plaque found at diabetic patients.

Serum cardiovascular risk biomarkers in pre-pubertal obese children

BACKGROUND

Childhood obesity is associated with premature cardiovascular complications. However, little is known about the effect of a family-based behavioural intervention on the relationship between arterial function, blood pressure and biomarkers in pre-pubertal children with obesity.

DESIGN

This was a single centre randomized controlled trial (RCT) including 74 children randomized to a 6-month behavioural intervention to treat obesity. In 48 children (13 controls and 35 interventions), we assessed: serum level of cytokine (CCL2), adiponectin, and neutrophil product (MMP-8), as well as carotid intima-media thickness, flow-mediated dilation (FMD), nitroglycerin-mediated dilation; arterial stiffness (incremental elastic modulus, Einc), pulse wave velocity (PWV), resting and 24-hour blood pressure (BP).

RESULTS

At baseline, resting systolic BP was positively associated with MMP-8 levels which was significantly higher in children with hypertension (P = 0.033). Biochemical markers were not related to endothelial function at baseline, but they globally increased after 6 months in the intervention group. The significant increase of CCL2 levels in the intervention group was associated with a decrease in diastolic BP. Furthermore, adiponectin change was positively related to a change in FMD and negatively to change in Einc and PWV.

CONCLUSIONS

The usefulness of serum biomarkers for the detection of cardiovascular diseases is not well established in children. In our population, MMP-8 concentration was higher in hypertensive children. Furthermore, behavioural interventions resulted in a paradoxical increase in some biomarkers in children, with potentially beneficial effects detected with CCL2 changes. Caution should be taken when using nonspecific serum biomarkers for the clinical monitoring of children with obesity.

Matrix metalloproteinases in pro-atherosclerotic arterial remodeling

Matrix metalloproteinases (MMPs) is a family of Zn²⁺ endopeptidases that process various components of the extracellular matrix. These enzymes are also involved in activation and inhibition of signaling cascades through proteolytic cleavage of surface receptors. Moreover, MMPs play a key role in tissue remodeling and and repair. Dysregulation of MMPs is observed in patholofgical conditions, including atherosclerosis, which is associated with hyperactivation of MMPs, aberrant tissue remodeling and neovascularization of the growing atherosclerotic plaques. This makes MMPs interesting therapeutic targets that can be employed for developing novel therapies to treat atherosclerosis and its complications. Currently, a growing number of synthetic MMP inhibitors is available. In this review, we will discuss the role of these enzymes in atherosclerosis pathology and the ways of their pothential therapeutic use.

MMP-9 gene rs3918242 polymorphism increases risk of stroke: A meta-analysis

The association between matrix metalloproteinase-9 (MMP-9) gene rs3918242 polymorphism and the risk of stroke has been investigated, but the findings have been found to be contradictory. Thus, this association was assessed by meta-analysis. Potential studies were searched throughout PubMed, Embase, and CNKI. Pooled odds ratios and 95% confidence intervals were calculated. Sixteen original studies analyzing this association were included, involving 3647 stroke patients and 3685 unrelated controls. It was confirmed that MMP-9 gene rs3918242 polymorphism increased the risk of stroke. Stratification analysis of ethnicity revealed an increased risk of stroke among Asians, but not among Caucasians. Subgroup analysis by the type of stroke showed that MMP-9 gene rs3918242 polymorphism increased the risk of ischemic stroke. Sensitivity analysis did not draw different findings. In conclusion, MMP-9 gene rs3918242 polymorphism increases the risk of stroke.

Specific matrix metalloproteinases and calcification factors are associated with the vulnerability of human carotid plaque

The rupture of atherosclerotic plaque provokes the majority of acute cerebrovascular events. Studies have demonstrated that various matrix metalloproteinases (MMPs) may promote atherosclerotic plaque progression and rupture. However, results have been incongruous and the mechanisms of this remain obscured. Therefore, in the current study, carotid plaques were characterized by assessing the levels of MMPs and calcification factors, and evaluating their association with plaque vulnerability. Human carotid plaques were obtained from carotid endarterectomies, and classified into stable and vulnerable groups by ultrasonography and histological analyses. The mRNA and protein levels of MMPs, vascular endothelial growth factor (VEGF), bone sialoprotein 2 (BSP) and osteopontin were investigated by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. Immunohistochemistry was used to localize MMP-2 and MMP-14 in stable and vulnerable plaques. The activation of various associated signaling pathways was also investigated using western blotting. The mRNA levels of MMP-2, -7, -9 and -14 were elevated in vulnerable plaques, among which expression of MMP-2 and -14 were the highest. Consistent with the mRNA levels, the protein levels of MMP-2 and -14 were also elevated. Immunohistochemistry also demonstrated positive staining of MMP-2 and MMP-14 in vulnerable plaques. Factors that indicate neovascularization and calcification, including VEGF and BSP, were concurrently elevated in vulnerable plaques. In addition, the protein levels of extracellular regulated kinase (ERK) and protein kinase C (PKC) were upregulated in vulnerable plaques. The current study provides novel insights into the MMP profiles of vulnerability plaques, and may assist in the development of novel methods for the diagnosis of plaque vulnerability and the prevention of plaque rupture.

Matrix Metalloproteinase-1 Gene Polymorphism Associated with Ultrasound-Assessed Carotid Thickness among Older Adults

BACKGROUND AND AIM

Due to the high incidence of vascular diseases, it is necessary to identify new circulating or structural markers for predicting risk for chronic diseases. Some studies suggest that MMP1 gene polymorphisms are associated with the enzyme expression levels in situ (e.g., in atherosclerotic plaques).

OBJECTIVES

Thus, the study of this polymorphism may help understanding the pathophysiology of coronary disease.

METHODS

We performed cross-sectional clinical and laboratory evaluations (including measurement of intima-media thickness of carotid arteries) and genotyping of the MMP1 SNP rs495366 (A/G) in 366 elderly people.

RESULTS

No significant differences between genotypes were noted for biochemical, metabolic, inflammatory, or clinical variables except for a significant difference in intima-media thickness for the left carotid artery and a trend toward significance for the right counterpart.

CONCLUSION

Carriers of the allele associated with lower MMP1 expression (allele A) presented greater carotid thickness. We suggest that the phenomenon can be explained by impaired remodeling of the arterial wall (poor degradation of collagen fibers in this scenario), yielding carotid wall thickening and a greater intrinsic risk for cerebrovascular events.

Gene therapy with antisense oligonucleotides silencing c-myc reduces neointima formation and vessel wall thickness in a mouse model of vein graft disease

Gene therapy for avoiding intimal hyperplasia of vein grafts after coronary artery bypass grafting is still discussed controversially. A promising application of gene therapy in vein grafts is the use of antisense oligonucleotides to block the expression of genes encoding cell cycle regulatory proteins in vascular smooth muscle cells. C-myc, either directly or by regulating the expression of other proteins, controls cell proliferation, apoptosis and cell survival, tissue remodeling, angiogenesis, cell metabolism, production of inflammatory and anti-inflammatory cytokines, and also participates in cell transformation. Forty C57BL/6J mice underwent interposition of the inferior vena cava from isogenic donor mice into the common carotid artery using a previously described cuff technique. Twenty mice received periadventitial administration of antisense oligonucleotides directed against c-myc (treatment group), the other twenty mice received no treatment (control group). All vein grafts were harvested two weeks after surgery, dehydrated, wax embedded, cut into slides of 2 μm thickness, stained and histologically and immunohistochemically examined under light microscope. In our study, we could show the promising effects of antisense oligonucleotide treatment in a mouse model of vein graft disease including the significant reduction of neointimal, media and total vessel wall thickness with a significantly lower percentage of SMA positive cells, elastic fibres and acid mucopolysaccharides in the neointima and media, a decreased vascularization, and a lower expression of PDGFR ß, MMP-9 and VEGF-A positive cells throughout the whole vein graft wall.

An electrospun poly(ε-caprolactone) scaffold modified with matrix metalloproteinase for cellularization and vascularization

Rapid in vivo cellularization of implanted grafts is crucial to tissue regeneration in tissue engineering. The compositions and structures of the extracellular matrix (ECM) are important in regulating cell attachment, proliferation and migration. ECM remodeling, especially degradation, is closely related to cell migration under physiological and pathological conditions. Matrix metalloproteinases-1 (MMP-1, Collagenase I) could degrade collagen I in the ECM. So we put forward the hypothesis that ECM degradation regulated by MMP-1 might facilitate rapid cellularization in tissue engineering. In the cell invasion test, collagenase of certain concentration (0.01 mg mL^-1) could significantly promote the migration of smooth muscle cells (SMCs). Then electrospun poly(ε-caprolactone) (PCL) grafts were modified with collagenase through immobilization by hydrophobin (HFBI). Surface characterization of the material confirmed the successful immobilization of collagenase. The ingrowth of SMCs into the collagenase-modified membrane was more than that into the untreated membrane. Results of subcutaneous implantation in rats indicated that the modified graft was beneficial for vascularization by promoting capillary formation. The results showed that the collagenase modified grafts could enhance SMC migration and this strategy may be a promising and attractive method for cellularization and vascularization in tissue engineering.

Effects of Resistance Training on Matrix Metalloproteinase Activity in Skeletal Muscles and Blood Circulation During Aging

Aging is a complex, multifactorial process characterized by the accumulation of deleterious effects, including biochemical adaptations of the extracellular matrix (ECM). The purpose of this study was to investigate the effects of 12 weeks of resistance training (RT) on metalloproteinase 2 (MMP-2) activity in skeletal muscles and, MMP-2 and MMP-9 activity in the blood circulation of young and old rats. Twenty-eight Wistar rats were randomly divided into four groups (n = 7 per group): young sedentary (YS); young trained (YT), old sedentary (OS), and old trained (OT). The stair climbing RT consisted of one training session every 2 other day, with 8–12 dynamic movements per climb. The animals were euthanized 48 h after the end of the experimental period. MMP-2 and MMP-9 activity was measured by zymography. There was higher active MMP-2 activity in the lateral gastrocnemius and flexor digitorum profundus muscles in the OT group when compared to the OS, YS, and YT groups (p ≤ 0.001). Moreover, there was higher active MMP-2 activity in the medial gastrocnemius muscle in the OT group when compared to the YS and YT groups (p ≤ 0.001). The YS group presented lower active MMP-2 activity in the soleus muscle than the YT, OS, OT groups (p ≤ 0.001). With respect to active MMP-2/9 activity in the bloodstream, the OT group displayed significantly reduced activity (p ≤ 0.001) when compared to YS and YT groups. In conclusion, RT up-regulates MMP-2 activity in aging muscles, while down-regulating MMP-2 and MMP-9 in the blood circulation, suggesting that it may be a useful tool for the maintenance of ECM remodeling.

Association between matrix metalloproteinase 9 C-1562T polymorphism and the risk of coronary artery disease: an update systematic review and meta-analysis

Polymorphism (rs3918242) in the MMP9 gene has been reported to be associated with coronary artery disease (CAD). This study aims to investigate a more accurate estimation of the relationship between CAD and rs3918242 polymorphism by a meta-analysis method. We systematically searched studies on the association of rs3918242 polymorphism and CAD in PubMed, Web of Science, the Cochrane Library, Wanfang Data and CNKI. We used Stata 12.0 and RevMan 5.3 software to perform the meta-analyses. A total of 37 case-control studies involving 13,035 CAD patients and 11,372 non-CAD controls were included. A statistically significant association between rs3918242 polymorphism and CAD was observed in allelic model (Odds ratio (OR) 1.34; 95% confidence interval (CI) 1.20–1.50; p < 0.00001), recessive model (OR 1.43; 95% CI 1.17–1.75; p = 0.0004), and in dominant model ( OR 1.36; 95% CI 1.20–1.53; p < 0.00001). Moreover, we also found that there is a statistically significant association between rs3918242 polymorphism and myocardial infarction (MI) in Asians with allelic model (OR 1.66; 95% CI 1.29–2.14; p < 0.0001), recessive model (OR 2.29; 95% CI 1.44–3.63; p = 0.004), and dominant (OR 1.74; 95% CI 1.29–2.35; p = 0.0003) model. A similar result in Caucasians with allelic model (OR 1.14; 95% CI 1.02–1.27; p = 0.02), and in dominant (OR 1.17; 95% CI 1.04–1.32; p = 0.01) model. Our meta-analysis suggested that the MMP9 T allele is a risk factor for CAD and MI.

Exposure of tropoelastin to peroxynitrous acid gives high yields of nitrated tyrosine residues, di-tyrosine cross-links and altered protein structure and function

Elastin is an abundant extracellular matrix protein in elastic tissues, including the lungs, skin and arteries, and comprises 30-57% of the aorta by dry mass. The monomeric precursor, tropoelastin (TE), undergoes complex processing during elastogenesis to form mature elastic fibres. Peroxynitrous acid (ONOOH), a potent oxidising and nitrating agent, is formed in vivo from superoxide and nitric oxide radicals. Considerable evidence supports ONOOH formation in the inflamed artery wall, and a role for this species in the development of human atherosclerotic lesions, with ONOOH-damaged extracellular matrix implicated in lesion rupture. We demonstrate that TE is highly sensitive to ONOOH, with this resulting in extensive dimerization, fragmentation and nitration of Tyr residues to give 3-nitrotyrosine (3-nitroTyr). This occurs with equimolar or greater levels of oxidant and increases in a dose-dependent manner. Quantification of Tyr loss and 3-nitroTyr formation indicates extensive Tyr modification with up to two modified Tyr per protein molecule, and up to 8% conversion of initial ONOOH to 3-nitroTyr. These effects were modulated by bicarbonate, an alternative target for ONOOH. Inter- and intra-protein di-tyrosine cross-links have been characterized by mass spectrometry. Examination of human atherosclerotic lesions shows colocalization of 3-nitroTyr with elastin epitopes, consistent with TE or elastin modification in vivo, and also an association of 3-nitroTyr containing proteins and elastin with lipid deposits. These data suggest that exposure of TE to ONOOH gives marked chemical and structural changes to TE and altered matrix assembly, and that such damage accumulates in human arterial tissue during the development of atherosclerosis.

Smooth muscle cell-specific Tgfbr1 deficiency attenuates neointimal hyperplasia but promotes an undesired vascular phenotype for injured arteries

Neointimal hyperplasia (NIH) and inward wall remodeling cause arterial restenosis and failure of bypass vein grafts. Previous studies from our group suggest that transforming growth factor (TGF) β promotes these pathologies via regulating cell kinetics at the early stage and matrix metabolism at the late stage. Although these temporal TGFβ effects may result from its signaling in different cell groups, the responsible cell type has not been identified. In the current study, we evaluated the effect of smooth muscle cell (SMC)‐specific TGFβ signaling through its type I receptor TGFBR1 on NIH and wall remodeling of the injured femoral arteries (FAs). An inducible Cre/loxP system was employed to delete SMC Tgfbr1 (Tgfbr1^iko). Mice not carrying the Cre allele (Tgfbr1^f/f) served as controls. The injured FAs were evaluated on d3, d7, and d28 postoperatively. Tgfbr1^iko attenuated NIH by 92%, but had insignificant influence on arterial caliber when compared with Tgfbr1^f/f controls on d28. This attenuation correlated with greater cellularity and reduced collagen content. Compared with Tgfbr1^f/fFAs, however, Tgfbr1^ikoFAs exhibited persistent neointimal cell proliferation and cell apoptosis, with both events at a greater rate on d28. Tgfbr1^ikoFAs additionally contained fewer SMCs and more inflammatory infiltrates in the neointima and displayed a thicker adventitia than did Tgfbr1^f/fFAs. More MMP9 proteins were detected in the adventitia of Tgfbr1^ikoFAs than in that of Tgfbr1^f/f controls. Our results suggest that disruption of SMC Tgfbr1 inhibits arterial NIH in the short term, but the overall vascular phenotype may not favor long‐term performance of the injured arteries.

FOXO3a (Forkhead Transcription Factor O Subfamily Member 3a) Links Vascular Smooth Muscle Cell Apoptosis, Matrix Breakdown, Atherosclerosis, and Vascular Remodeling Through a Novel Pathway Involving MMP13 (Matrix Metalloproteinase 13)

OBJECTIVE

Vascular smooth muscle cell (VSMC) apoptosis accelerates atherosclerosis and promotes breakdown of the extracellular matrix, but the mechanistic links between these 2 processes are unknown. The forkhead protein FOXO3a (forkhead transcription factor O subfamily member 3a) is activated in human atherosclerosis and induces a range of proapoptotic and other transcriptional targets. We, therefore, determined the mechanisms and consequences of FOXO3a activation in atherosclerosis and arterial remodeling after injury.

APPROACH AND RESULTS

Expression of a conditional FOXO3a allele (FOXO3aA3ER) potently induced VSMC apoptosis, expression and activation of MMP13 (matrix metalloproteinase 13), and downregulation of endogenous TIMPs (tissue inhibitors of MMPs). mmp13 and mmp2 were direct FOXO3a transcriptional targets in VSMCs. Activation of endogenous FOXO3a also induced MMP13, extracellular matrix degradation, and apoptosis, and MMP13-specific inhibitors and fibronectin reduced FOXO3a-mediated apoptosis. FOXO3a activation in mice with VSMC-restricted FOXO3aA3ER induced MMP13 expression and activity and medial VSMC apoptosis. FOXO3a activation in FOXO3aA3ER/ApoE^-/- (apolipoprotein E deficient) mice increased atherosclerosis, increased necrotic core and reduced fibrous cap areas, and induced features of medial degeneration. After carotid artery ligation, FOXO3a activation increased VSMC apoptosis, VSMC proliferation, and neointima formation, all of which were reduced by MMP13 inhibition.

CONCLUSIONS

FOXO3a activation induces VSMC apoptosis and extracellular matrix breakdown, in part, because of transcriptional activation of MMP13. FOXO3a activation promotes atherosclerosis and medial degeneration and increases neointima after injury that is partly dependent on MMP13. FOXO3a-induced MMP activation represents a direct mechanistic link between VSMC apoptosis and matrix breakdown in vascular disease.

The Endocannabinoid System and Heart Disease: The Role of Cannabinoid Receptor Type 2

Decades of research has provided evidence for the role of the endocannabinoid system in human health and disease. This versatile system, consisting of two receptors (CB1 and CB2), their endogenous ligands (endocannabinoids), and metabolic enzymes has been implicated in a wide variety of disease states, ranging from neurological disorders to cancer. CB2 has gained much interest for its beneficial immunomodulatory role that can be obtained without eliciting psychotropic effects through CB1. Recent studies have shed light on a protective role of CB2 in cardiovascular disease, an ailment which currently takes more lives each year in Western countries than any other disease or injury. By use of CB2 knockout mice and CB2-selective ligands, knowledge of how CB2 signaling affects atherosclerosis and ischemia has been acquired, providing a major stepping stone between basic science and translational clinical research. Here, we summarize the current understanding of the endocannabinoid system in human pathologies and provide a review of the results from preclinical studies examining its function in cardiovascular disease, with a particular emphasis on possible CB2-targeted therapeutic interventions to alleviate atherosclerosis.

Platelets and matrix metalloproteinases

Matrix metalloproteinases (MMPs) and their inhibitors essentially contribute to a variety of pathophysiologies by modulating cell migration, tissue degradation and inflammation. Platelet-associated MMP activity appears to play a major role in these processes. First, platelets can concentrate leukocyte-derived MMP activity to sites of vascular injury by leukocyte recruitment. Second, platelets stimulate MMP production in e.g. leukocytes, endothelial cells, or tumour cells by direct receptor interaction or/and by paracrine pathways. Third, platelets synthesise and secrete a variety of MMPs including MMP-1, MMP-2, MMP-3, and MMP-14 (MT1-MMP), and potentially MMP-9 as well as the tissue inhibitors of metalloproteinase (TIMPs). This review focuses on platelet-derived and platelet-induced MMPs and their inhibitors.

Stabilisation of atherosclerotic plaques

Plaque rupture and subsequent thrombotic occlusion of the coronary artery account for as many as three quarters of myocardial infarctions. The concept of plaque stabilisation emerged about 20 years ago to explain the discrepancy between the reduction of cardiovascular events in patients receiving lipid lowering therapy and the small decrease seen in angiographic evaluation of atherosclerosis. Since then, the concept of a vulnerable plaque has received a lot of attention in basic and clinical research leading to a better understanding of the pathophysiology of the vulnerable plaque and acute coronary syndromes. From pathological and clinical observations, plaques that have recently ruptured have thin fibrous caps, large lipid cores, exhibit outward remodelling and invasion by vasa vasorum. Ruptured plaques are also focally inflamed and this may be a common denominator of the other pathological features. Plaques with similar characteristics, but which have not yet ruptured, are believed to be vulnerable to rupture. Experimental studies strongly support the validity of anti-inflammatory approaches to promote plaque stability. Unfortunately, reliable non-invasive methods for imaging and detection of such plaques are not yet readily available. There is a strong biological basis and supportive clinical evidence that low-density lipoprotein lowering with statins is useful for the stabilisation of vulnerable plaques. There is also some clinical evidence for the usefulness of antiplatelet agents, beta blockers and renin-angiotensin-aldosterone system inhibitors for plaque stabilisation. Determining the causes of plaque rupture and designing diagnostics and interventions to prevent them are urgent priorities for current basic and clinical research in cardiovascular area.

Local honokiol application inhibits intimal thickening in rabbits following carotid artery balloon injury

Honokiol is a natural bioactive product with anti-tumor, anti-inflammatory, anti-oxidative, anti-angiogenic and neuroprotective properties. The present study aimed to investigate the effects of honokiol treatment on intimal thickening following vascular balloon injury. The current study determined that perivascular honokiol application reduced intimal thickening in rabbits 14 days after carotid artery injury, it may inhibit vascular smooth muscle cell (VSMCs) proliferation and reduce collagen deposition in local arteries. The findings of the presents study also suggested that honikiol may increase the mRNA expression levels of matrix metalloproteinase‑1 (MMP‑1), MMP‑2 and MMP‑9 and decrease tissue inhibitor of metalloproteinase‑1 (TIMP‑1) mRNA expression in the rabbit arteries. Additionally, perivascular honokiol application inhibited intimal thickening, possibly via inhibition of the phosphorylation of SMAD family member 2/3.

Activation and inflammation of the venous endothelium in vein graft disease

The long saphenous vein is the most commonly used conduit in coronary artery bypass graft (CABG) surgery when bypassing multiple diseased arteries; however, its use is complicated by the development of vascular inflammation, intimal hyperplasia and accelerated atherosclerosis leading to compromised graft efficacy. Despite refinement of surgical techniques to improve graft patency, late vein graft failure remains a significant problem. Moreover, there is a lack of pharmacological interventions proven to be effective in the treatment of late vein graft failure. A greater understanding of the molecular nature of the disease and the interactions between endothelial and smooth muscle cells as a result of alterations in local haemodynamics may assist with designing future beneficial pharmacological interventions. Venous endothelial cells (ECs) are physiologically adapted to chronic low shear stress; however, once the graft is implanted into the arterial circulation, they become suddenly exposed to acute high levels of shear stress. A small number of in vitro and ex vivo studies have demonstrated that acute high shear stress is associated with the activation of a pro-inflammatory profile in saphenous vein ECs, which may be mediated by mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signalling pathways. The impact of acute changes in shear stress on venous ECs and the role of ECs in the development of intimal hyperplasia remains incomplete and is the subject of this review.

Oxysterols and 4-hydroxy-2-nonenal contribute to atherosclerotic plaque destabilization

A growing bulk of evidence suggests that cholesterol oxidation products, known as oxysterols, and 4-hydroxy-2-nonenal (HNE), the major proatherogenic components of oxidized low density lipoproteins (oxLDLs), significantly contribute to atherosclerotic plaque progression and destabilization, with eventual plaque rupture. These oxidized lipids are involved in various key steps of this complex process, mainly thanks to their ability to induce inflammation, oxidative stress, and apoptosis. This review summarizes the current knowledge of the effects induced by these compounds on vascular cells, after their accumulation in the arterial wall and in the atherosclerotic plaque.

Matrix Metalloproteinases, Vascular Remodeling, and Vascular Disease

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that degrade various proteins in the extracellular matrix (ECM). Typically, MMPs have a propeptide sequence, a catalytic metalloproteinase domain with catalytic zinc, a hinge region or linker peptide, and a hemopexin domain. MMPs are commonly classified on the basis of their substrates and the organization of their structural domains into collagenases, gelatinases, stromelysins, matrilysins, membrane-type (MT)-MMPs, and other MMPs. MMPs are secreted by many cells including fibroblasts, vascular smooth muscle (VSM), and leukocytes. MMPs are regulated at the level of mRNA expression and by activation through removal of the propeptide domain from their latent zymogen form. MMPs are often secreted in an inactive proMMP form, which is cleaved to the active form by various proteinases including other MMPs. MMPs degrade various protein substrates in ECM including collagen and elastin. MMPs could also influence endothelial cell function as well as VSM cell migration, proliferation, Ca²⁺ signaling, and contraction. MMPs play a role in vascular tissue remodeling during various biological processes such as angiogenesis, embryogenesis, morphogenesis, and wound repair. Alterations in specific MMPs could influence arterial remodeling and lead to various pathological disorders such as hypertension, preeclampsia, atherosclerosis, aneurysm formation, as well as excessive venous dilation and lower extremity venous disease. MMPs are often regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP ratio often determines the extent of ECM protein degradation and tissue remodeling. MMPs may serve as biomarkers and potential therapeutic targets for certain vascular disorders.

Surface modification of endovascular stents with rosuvastatin and heparin-loaded biodegradable nanofibers by electrospinning

This study describes the development of drug-loaded nanofibrous scaffolds as a nanocoating for endovascular stents for the local and sustained delivery of rosuvastatin (Ros) and heparin (Hep) to injured artery walls after endovascular procedures via the electrospinning process.

PURPOSE

The proposed hybrid covered stents can promote re-endothelialization; improve endothelial function; reduce inflammatory reaction; inhibit neointimal hyperplasia of the injured artery wall, due to well-known pleiotropic actions of Ros; and prevent adverse events such as in-stent restenosis (ISR) and stent thrombosis (ST), through the antithrombotic action of Hep.

METHODS

Biodegradable nanofibers were prepared by dissolving cellulose acetate (AC) and Ros in N,N-dimethylacetamide (DMAc) and acetone-based solvents. The polymeric solution was electrospun (e-spun) into drug-loaded AC nanofibers onto three different commercially available stents (Co-Cr stent, Ni-Ti stent, and stainless steel stent), resulting in nonwoven matrices of submicron-sized fibers. Accordingly, Hep solution was further used for fibrous coating onto the engineered Ros-loaded stent. The functional encapsulation of Ros and Hep drugs into polymeric scaffolds further underwent physicochemical analysis. Morphological characterization took place via scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses, while scaffolds' wettability properties were obtained by contact angle (CA) measurements.

RESULTS

The morphology of the drug-loaded AC nanofibers was smooth, with an average diameter of 200-800 nm, and after CA measurement, we concluded to the superhydrophobic nature of the engineered scaffolds. In vitro release rates of the pharmaceutical drugs were determined using a high-performance liquid chromatography assay, which showed that after the initial burst, drug release was controlled slowly by the degradation of the polymeric materials.

CONCLUSION

These results imply that AC nanofibers encapsulated with Ros and Hep drugs have great potential in the development of endovascular grafts with anti-thrombogenic properties that can accelerate the re-endothelialization, reduce the neointimal hyperplasia and inflammatory reaction, and improve the endothelial function.

Interleukin-18, matrix metalloproteinase-22 and -29 are independent risk factors of human coronary heart disease

BACKGROUND

Coronary heart disease (CHD) is characterized by arterial wall inflammation and matrix degradation. Matrix metalloproteinase (MMP)-22 and -29 and pro-inflammatory cytokine interleukin-18 (IL18) are present in human hearts. IL18 may regulate MMP-22 and -29 expression, which may correlate with CHD progression.

METHODS AND RESULTS

Immunoblot analysis showed that IL18 induced MMP-22 expression in human aortic smooth muscle cells. The Mann Whitney test from a prospective study of 194 CHD patients and 68 non-CHD controls demonstrated higher plasma levels of IL18, MMP-22 and -29 in CHD patients than in the controls. A logistic regression test suggested that plasma IL18 (odds ratio (OR)=1.131, P=0.007), MMP-22 (OR=1.213, P=0.040), and MMP-29 (OR=1.198, P=0.033) were independent risk factors of CHD. Pearson's correlation test showed that IL18 (coefficient (r)=0.214, P=0.045; r=0.246, P=0.031) and MMP-22 (r=0.273, P=0.006; r=0.286, P=0.012) were associated with the Gensini score before and after adjusting for potential confounding factors. The multivariate Pearson's correlation test showed that plasma MMP-22 levels correlated positively with high-sensitive-C-reactive protein (hs-CRP) (r=0.167, P=0.023), and MMP-29 levels correlated negatively with triglyceride (r=-0.169, P=0.018). Spearman's correlation test indicated that plasma IL18 levels associated positively with plasma MMP-22 (r=0.845, P<0.001) and MMP-29 (r=0.548, P<0.001).

CONCLUSIONS

Our observations suggest that IL18, MMP-22 and -29 serve as biomarkers and independent risk factors of CHD. Increased systemic IL18 in CHD patients may contribute to elevated plasma MMP-22 and -29 levels in these patients.

Crosstalk Between Enzyme Matrix Metalloproteinases 2 and 9 and Regulatory T Cell Immunity in the Global Burden of Atherosclerosis

Changes in immune and inflammatory responses may play a crucial role in the development and progression of atherosclerosis, as an autoimmune, chronic and progressive inflammatory disease. Immunological activity and vascular inflammation during atherosclerosis can be modulated by autoimmune responses against self-antigens, according to changeable risk factors (cholesterol, oxidized low-density lipoprotein (ox-LDL) in the vascular wall, fatty acids, etc.), and accompanied by accumulation of leucocytes and proinflammatory cytokines, which stimulate the transcription of matrix metalloproteinases (MMPs), whose concentration are increased in foam cell-rich regions. Regulatory T cells (Tregs) represent a unique subpopulation of T cells specialized in the regulation of immune response and in the suppression of proatherogenic T cells. The aim of our study was to examine the interactions between the concentration of enzyme matrix metalloproteinases 2 and 9 (MMP-2 and 9) in urine and the percentage of Tregs in peripheral blood of two groups of patients: with carotid artery stenosis (CAS), undergoing surgery and with mild atherosclerosis (A) from general practice. The method of enzyme immunoassay (ELISA) was used to determine enzyme MMP expression, and Tregs was examined by flow cytometric analysis. Our data have showed a large increase in the enzyme MMP-2 and 9 in the urine of CAS and A patients in comparison with healthy controls and indicated this method as an easy marker for the monitoring of the development of atherosclerosis. Simultaneously, the diminished number of Tregs in the same patients pointed the importance of these regulatory mechanisms in the etiopathogenesis of atherosclerosis and possible Tregs-mediated therapy.

Sex-related differences in serum matrix metalloproteinase-9 screening non-calcified and mixed coronary atherosclerotic plaques in outpatients with chest pain

The objective of this study is to evaluate the clinical feasibility of serum matrix metalloproteinase-9 (MMP-9) for screening plaque composition as assessed by coronary computed tomography angiography (CCTA) in outpatients with chest pain,and the effects of sex on this feasibility. Eight hundred and sixty-two consecutive outpatients with chest pain were divided into three groups according to the results of CCTA: non-plaque (NP, n = 474), calcified plaques (CPs, n = 179), non-calcified and mixed plaques (NCPs and MPs, n = 209). We found that serum MMP-9 levels were significantly higher in patients with NCPs and MPs compared to those with either NP or CPs, especially in women (649.7 ± 279.8 vs. 485.7 ± 231.6 ng/mL or 515.7 ± 274.5 ng/mL, P < 0.001). MMP-9 showed better identification of NCPs and MPs than other related factors and was an independent predictor for NCPs and MPs both in women and men. The receiver operating characteristic analysis indicated a substantial superiority in women with area under the curve of 0.75 (95% CI 0.69-0.82, P < 0.01), compared with men of 0.59 (95% CI 0.53-0.65, z = 3.71, P < 0.01). The diagnostic tests revealed a moderate risk of the presence of NCPs and MPs with MMP-9 ≥531.6 ng/mL in female patients.

Impact of lipoprotein apheresis with dextran-sulfate adsorption on the expression of genes involved in cardiovascular health in the blood of patients with homozygous familial hypercholesterolemia

Lipoprotein apheresis (LA) with dextran sulfate adsorption (DSA) is a reliable method to decrease LDL-cholesterol (C) concentrations in patients with homozygous familial hypercholesterolemia (HoFH). The objective of the present study was to investigate the impact of LA with DSA on the mRNA expression of genes associated with cardiovascular health in the whole blood of HoFH patients. Blood samples were collected before and after LA treatment with DSA in 9 HoFH patients. Microarray analyses were performed to measure the whole blood expression of >30 000 annotated genes pre- and post-LA. Concomitant reductions in LDL-C (median -73.8%, range: -55.9 to -82.0, P = .0001) and lipoprotein (a) concentrations (median -74.1%, range -65.6 to -84.1, P = .003) were induced with LA treatment. LA with DSA did not impact the whole blood mRNA expression of most key genes involved in cardiovascular health, including those associated with cholesterol, fatty acid and lipoprotein metabolism. However, LA with DSA significantly upregulated the whole blood expression of early growth response protein (EGR)1 (1.94-fold, P = .02), EGR3 (1.56-fold, P = .0008) and B-cell lymphoma 3-encoded protein (BCL3; 1.25-fold, P = .03). In conclusion, this study demonstrated that a single LA treatment with DSA has very limited impact on the whole blood expression of a broad spectrum of genes associated with cardiovascular health. Our results suggest that contact between blood cells and the primary membrane or extracorporeal circulation could upregulate the expression of EGR1, EGR3, BCL3, and MMP9 in blood cells.

Is cardiovascular disease in patients with diabetes associated with serum levels of MMP-2, LOX, and the elastin degradation products ELM and ELM-2?

BACKGROUND

Diabetes mellitus type 2 (T2DM) is a significant risk factor for the development of cardiovascular diseases (CVDs). In a previous microarray study of internal mammary arteries from patients with and without T2DM, we observed several elastin-related genes with altered mRNA-expression in diabetic patients, namely matrix metalloproteinase 2 (MMP-2), lysyl oxidase (LOX) and elastin itself. In this study we investigate whether the serum concentrations of elastin-related proteins correlate to signs of CVD in patients with T2DM.

METHODS

Blood samples from 302 type 2 diabetic patients were analysed for MMP-2, LOX, and the elastin degradation products ELM and ELM2. The results were investigated for correlations to signs of CVD in different vascular territories, as determined by myocardial perfusion scintigraphy, carotid artery thickness and ankle-brachial blood pressure index.

RESULTS

T2DM patients with peripheral arterial disease (low ankle-brachial index) (PAD) display higher levels of MMP-2 and ELM compared to patients without PAD. However, none of the proteins or degradation products correlated with myocardial ischemia or a combined measure of CVD-signs, including myocardial ischemia, increased carotid thickness and decreased ankle-brachial blood pressure.

CONCLUSIONS

Our results suggest that the diabetic environment affects the circulating amounts of MMP-2 and ELM in patients with PAD. However, the same connection could not be seen in diabetic patients with CVD broadly identified in three vascular territories. LOX and ELM-2 did not correlate to any type of CVD. Overall, serum levels of elastin-related molecules are only remotely related to CVD in type 2 diabetes.

A novel workflow combining plaque imaging, plaque and plasma proteomics identifies biomarkers of human coronary atherosclerotic plaque disruption

Background

Atherosclerotic plaque rupture is the culprit event which underpins most acute vascular syndromes such as acute myocardial infarction. Novel biomarkers of plaque rupture could improve biological understanding and clinical management of patients presenting with possible acute vascular syndromes but such biomarker(s) remain elusive. Investigation of biomarkers in the context of de novo plaque rupture in humans is confounded by the inability to attribute the plaque rupture as the source of biomarker release, as plaque ruptures are typically associated with prompt down-stream events of myocardial necrosis and systemic inflammation.

Methods

We developed a novel approach to identify potential biomarkers of plaque rupture by integrating plaque imaging, using optical coherence tomography, with both plaque and plasma proteomic analysis in a human model of angioplasty-induced plaque disruption.

Results

We compared two pairs of coronary plaque debris, captured by a FilterWire Device, and their corresponding control samples and found matrix metalloproteinase 9 (MMP9) to be significantly enriched in plaque. Plaque contents, as defined by optical coherence tomography, affect the systemic changes of MMP9. Disruption of lipid-rich plaque led to prompt elevation of plasma MMP9, whereas disruption of non-lipid-rich plaque resulted in delayed elevation of plasma MMP9. Systemic MMP9 elevation is independent of the associated myocardial necrosis and systemic inflammation (measured by Troponin I and C-reactive protein, respectively). This information guided the selection of a subset of subjects of for further label free proteomics analysis by liquid chromatography tandem mass spectrometry (LC–MS/MS). We discovered five novel, plaque-enriched proteins (lipopolysaccharide binding protein, Annexin A5, eukaryotic translocation initiation factor, syntaxin 11, cytochrome B5 reductase 3) to be significantly elevated in systemic circulation at 5 min after plaque disruption.

Conclusion

This novel approach for biomarker discovery in human coronary artery plaque disruption can identify new biomarkers related to human coronary artery plaque composition and disruption.

Electronic supplementary material

The online version of this article (doi:10.1186/s12014-017-9157-x) contains supplementary material, which is available to authorized users.

Statistical Permutation-based Artery Mapping (SPAM): a novel approach to evaluate imaging signals in the vessel wall

BACKGROUND

Cardiovascular diseases are the leading cause of death worldwide. A prominent cause of cardiovascular events is atherosclerosis, a chronic inflammation of the arterial wall that leads to the formation of so called atherosclerotic plaques. There is a strong clinical need to develop new, non-invasive vascular imaging techniques in order to identify high-risk plaques, which might escape detection using conventional methods based on the assessment of the luminal narrowing. In this context, molecular imaging strategies based on fluorescent tracers and fluorescence reflectance imaging (FRI) seem well suited to assess molecular and cellular activity. However, such an analysis demands a precise and standardized analysis method, which is orientated on reproducible anatomical landmarks, ensuring to compare equivalent regions across different subjects.

METHODS

We propose a novel method, Statistical Permutation-based Artery Mapping (SPAM). Our approach is especially useful for the understanding of complex and heterogeneous regional processes during the course of atherosclerosis. Our method involves three steps, which are (I) standardisation with an additional intensity normalization, (II) permutation testing, and (III) cluster-enhancement. Although permutation testing and cluster enhancement are already well-established in functional magnetic resonance imaging, to the best of our knowledge these strategies have so far not been applied in cardiovascular molecular imaging.

RESULTS

We tested our method using FRI images of murine aortic vessels in order to find recurring patterns in atherosclerotic plaques across multiple subjects. We demonstrate that our pixel-wise and cluster-enhanced testing approach is feasible and useful to analyse tracer distributions in FRI data sets of aortic vessels.

CONCLUSIONS

We expect our method to be a useful tool within the field of molecular imaging of atherosclerotic plaques since cluster-enhanced permutation testing is a powerful approach for finding significant differences of tracer distributions in inflamed atherosclerotic vessels.

The Role of Matrix Metalloproteinases in Development, Repair, and Destruction of the Lungs

Normal gas exchange after birth requires functional lung alveolar units that are lined with epithelial cells, parts of which are intricately fused with microvascular capillaries. A significant phase of alveolar lung development occurs in the perinatal period, continues throughout early stages in life, and requires activation of matrix-remodeling enzymes. Failure to achieve an optimum number of alveoli during lung maturation can cause several untoward medical consequences including disabling obstructive and/or restrictive lung diseases that limit physiological endurance and increase mortality. Several members of the matrix metalloproteinase (MMP) family are critical in lung remodeling before and after birth; however, their resurgence in response to environmental factors, infection, and injury can also compromise lung function. Therefore, temporal expression, regulation, and function of MMPs play key roles in developing and maintaining adequate oxygenation under steady state, as well as in diseased conditions. Broadly, with the exception of MMP2 and MMP14, most deletional mutations of MMPs fail to perturb lung development; however, their individual absence can alter the pathophysiology of respiratory diseases. Specifically, under stressed conditions such as acute respiratory infection and allergic inflammation, MMP2 and MMP9 can play a protective role through bacterial clearance and production of chemotactic gradient, while loss of MMP12 can protect mice from smoke-induced lung disease. Therefore, better understanding of the expression and function of MMPs under normal lung development and their resurgence in response respiratory diseases could provide new therapeutic options in the future.

Matrix Metalloproteinase Inhibitors as Investigational and Therapeutic Tools in Unrestrained Tissue Remodeling and Pathological Disorders

Matrix metalloproteinases (MMPs) are zinc-dependent proteolytic enzymes that degrade various proteins in the extracellular matrix (ECM). MMPs may also regulate the activity of membrane receptors and postreceptor signaling mechanisms and thereby affect cell function. The MMP family includes collagenases, gelatinases, stromelysins, matrilysins, membrane-type MMPs, and other MMPs. Inactive proMMPs are cleaved by other MMPs or proteases into active MMPs, which interact with various protein substrates in ECM and cell surface. MMPs regulate important biological processes such as vascular remodeling and angiogenesis and may be involved in the pathogenesis of cardiovascular disorders such as hypertension, atherosclerosis, and aneurysm. The role of MMPs is often assessed by measuring their mRNA expression, protein levels, and proteolytic activity using gel zymography. MMP inhibitors are also used to assess the role of MMPs in different biological processes and pathological conditions. MMP activity is regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP balance could determine the net MMP activity, ECM turnover, and tissue remodeling. Also, several synthetic MMP inhibitors have been developed. Synthetic MMP inhibitors include a large number of zinc-binding globulins (ZBGs), in addition to non-ZBGs and mechanism-based inhibitors. MMP inhibitors have been proposed as potential tools in the management of osteoarthritis, cancer, and cardiovascular disorders. However, most MMP inhibitors have broad-spectrum actions on multiple MMPs and could cause undesirable musculoskeletal side effects. Currently, doxycycline is the only MMP inhibitor approved by the Food and Drug Administration. New generation biological and synthetic MMP inhibitors may show greater MMP specificity and fewer side effects and could be useful in targeting specific MMPs, reducing unrestrained tissue remodeling, and the management of MMP-related pathological disorders.

Molecular imaging of the extracellular matrix in the context of atherosclerosis

This review summarizes the current status of molecular imaging of the extracellular matrix (ECM) in the context of atherosclerosis. Apart from cellular components, the ECM of the atherosclerotic plaque plays a relevant role during the initiation of atherosclerosis and its' subsequent progression. Important structural and signaling components of the ECM include elastin, collagen and fibrin. However, the ECM not only plays a structural role in the arterial wall but also interacts with different cell types and has important biological signaling functions. Molecular imaging of the ECM has emerged as a new diagnostic tool to characterize biological aspects of atherosclerotic plaques, which cannot be characterized by current clinically established imaging techniques, such as X-ray angiography. Different types of molecular probes can be detected in vivo by imaging modalities such as magnetic resonance imaging (MRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT). The modality specific signaling component of the molecular probe provides information about its spatial location and local concentration. The successful introduction of molecular imaging into clinical practice and guidelines could open new pathways for an earlier detection of disease processes and a better understanding of the disease state on a biological level. Quantitative in vivo molecular parameters could also contribute to the development and evaluation of novel cardiovascular therapeutic interventions and the assessment of response to treatment.

Drug Treatment of Hypertension: Focus on Vascular Health

Hypertension, the most common preventable risk factor for cardiovascular disease and death, is a growing health burden. Serious cardiovascular complications result from target organ damage including cerebrovascular disease, heart failure, ischaemic heart disease and renal failure. While many systems contribute to blood pressure (BP) elevation, the vascular system is particularly important because vascular dysfunction is a cause and consequence of hypertension. Hypertension is characterised by a vascular phenotype of endothelial dysfunction, arterial remodelling, vascular inflammation and increased stiffness. Antihypertensive drugs that influence vascular changes associated with high BP have greater efficacy for reducing cardiovascular risk than drugs that reduce BP, but have little or no effect on the adverse vascular phenotype. Angiotensin converting enzyme ACE inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) improve endothelial function and prevent vascular remodelling. Calcium channel blockers also improve endothelial function, although to a lesser extent than ACEIs and ARBs. Mineralocorticoid receptor blockers improve endothelial function and reduce arterial stiffness, and have recently become more established as antihypertensive drugs. Lifestyle factors are essential in preventing the adverse vascular changes associated with high BP and reducing associated cardiovascular risk. Clinicians and scientists should incorporate these factors into treatment decisions for patients with high BP, as well as in the development of new antihypertensive drugs that promote vascular health.

Expression of a metalloproteinase family of ADAMTS in human vulnerable carotid lesions

AIMS

ADAMTS family of metalloproteases (a disintegrin and metalloprotease with thrombospondin motifs) possesses high proteolytic activity especially regarding proteoglycans. Their expression pattern in carotid plaques is as-yet unknown. The aim of the study was therefore the analysis of expression of ADAMTS1, 4, 5, and 13 and their inhibitors TIMP-1 and TIMP-3 in stable and unstable carotid plaques.

METHODS

Atherosclerotic plaques were collected from 40 patients (29 men, 11 women, mean age 70 years) undergoing carotid endarterectomy. The specimens were categorized into two groups (stable/unstable) according to Redgrave und Rothwell (The Oxford Plaque Study, 2008). SYBR Green-based real-time PCR, histology, and immunohistochemistry were performed.

RESULTS

All ADAMTS tested in our study were expressed in both stable and unstable plaques, especially in smooth muscle cells (SMCs) and macrophages. Analysis of the expression pattern on mRNA level showed significant higher expression of ADAMTS1 in unstable plaques compared with stable plaques (1.7-fold, P = 0.049). The expression of ADAMTS4 and 5 was also increased in unstable lesions; however, these changes were not statistically significant (1.2-fold, P = 0.667 and 1.6-fold, P = 0.077). Expression of TIMP-1 was significantly reduced in unstable plaques compared with stable ones (1.9-fold, P = 0.014).

CONCLUSION

SMCs seem to be an important source of ADAMTS analyzed in our study. Furthermore, expression of ADAMTS1 was found to be increased in unstable carotid lesions and might potentially contribute to plaque vulnerability.

Evidence for the Involvement of Matrix-Degrading Metalloproteinases (MMPs) in Atherosclerosis

Atherosclerosis leads to blockage of arteries, culminating in myocardial infarction, and stroke. The involvement of matrix-degrading metalloproteinases (MMPs) in atherosclerosis is established and many studies have highlighted the importance of various MMPs in this process. MMPs were first implicated in atherosclerosis due to their ability to degrade extracellular matrix components, which can lead to increased plaque instability. However, more recent work has highlighted a multitude of roles for MMPs in addition to breakdown of extracellular matrix proteins. MMPs are now known to be involved in various stages of plaque progression: from initial macrophage infiltration to plaque rupture. This chapter summarizes the development and progression of atherosclerotic plaques and the contribution of MMPs. We provide data from human studies showing the effect of MMP polymorphisms and the expression of MMPs in both the atherosclerotic plaque and within plasma. We also discuss work in animal models of atherosclerosis that show the effect of gain or loss of function of MMPs. Together, the data provided from these studies illustrate that MMPs are ideal targets as both biomarkers and potential drug therapies for atherosclerosis.

Role of simvastatin and RORα activity in the macrophage apoptotic pathway

Objective:

Atherosclerosis is a chronic inflammatory condition and is one of the main causes of death worldwide. Macrophages play important roles in the formation of atherosclerotic plaques. Apoptosis is progressively observed while plaques develop, although the precise mechanisms and outcomes of apoptosis in atherosclerosis development and progression are still contradictory. This study was conducted to explore the effects of simvastatin and retinoic acid receptor-related orphan receptor alpha (RORa) ligands on apoptosis in human acute monocytic leukemia (THP-1) macrophage cells.

Methods:

Briefly, the occupancy of RORa in the promoter regions of apoptotic pathway genes was demonstrated in THP-1 cell lines using chromatin immunoprecipitation (ChIP) analysis. In order to modulate RORa activity, THP-1 macrophage cells were treated with specific ligands (CPG52608 and SR1001) and then viability as well as count of THP-1 macrophage cells were analyzed.

Results:

We observed that simvastatin and both RORa ligands had a tendency to decrease THP-1 macrophage cell viability in culture. When compared with non-treated controls, simvastatin significantly decreased cell viability (p=0.04) and cell count (p=0.03). However, this negative effect of simvastatin seemed to be partly prevented by RORa ligands. In addition, bioinformatics analysis of ChIP-on-chip data demonstrated that several genes that are involved in the apoptotic pathway were likely RORa target genes. These genes were involved in the regulation of apoptosis through various pathways.

Conclusion:

In summary, our study suggest that simvastatin-mediated macrophage apoptosis might be modulated by SR1001 administration. However, involvement of RORa in this modulation through potential apoptotic target genes remains elusive.

Impact of Statin Therapy on Plasma MMP-3, MMP-9, and TIMP-1 Concentrations: A Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Trials

Tissue inhibitors of metalloproteinases (TIMPs) and matrix metalloproteinases (MMPs) are associated with the development of atherosclerosis and cardiovascular disease. Statin therapy has been shown to modulate MMPs and TIMP-1 levels, but clinical findings have not been conclusive. This study aimed to systematically review the clinical findings on the impact of statin therapy on plasma MMP-9, MMP-3, and TIMP-1 levels and calculate an effect size for the mentioned effect through a meta-analysis of available data. A total of 10 eligible studies with 11 treatment arms were included in the meta-analysis. Statin therapy had no significant effect on plasma MMP-9 (standardized mean difference [SMD]: −0.23, 95% confidence interval [CI]: −0.69 to 0.24, P = .345) nor MMP-3 concentrations (SMD: −0.004, 95% CI: −0.60 to 0.59, P = .990). However, meta-analysis demonstrated that statin therapy significantly decreases plasma TIMP-1 levels (SMD: −0.30, 95% CI: −0.56 to −0.03, P = .029). Random-effects meta-regression indicated that neither treatment duration nor changes in low-density lipoprotein cholesterol levels are associated with changes in plasma MMP-9 levels following statin therapy. The results of the present meta-analysis suggested a significant reduction in plasma concentrations of TIMP-1, but not MMP-9 and MMP-3, following statin therapy.

Perlecan/HSPG2 and matrilysin/MMP-7 as indices of tissue invasion: tissue localization and circulating perlecan fragments in a cohort of 288 radical prostatectomy patients

Prostate cancer (PCa) cells use matrix metalloproteinases (MMPs) to degrade tissue during invasion. Perlecan/HSPG2 is degraded at basement membranes, in reactive stroma and in bone marrow during metastasis. We previously showed MMP-7 efficiently degrades perlecan. We now analyzed PCa tissue and serum from 288 prostatectomy patients of various Gleason grades to decipher the relationship between perlecan and MMP-7 in invasive PCa. In 157 prostatectomy specimens examined by tissue microarray, perlecan levels were 18% higher than their normal counterparts. In Gleason grade 4 tissues, MMP-7 and perlecan immunostaining levels were highly correlated with each other (average correlation coefficient of 0.52) in PCa tissue, regardless of grade. Serial sections showed intense, but non-overlapping, immunostaining for MMP-7 and perlecan at adjacent borders, reflecting the protease-substrate relationship. Using a capture assay, analysis of 288 PCa sera collected at prostatectomy showed elevated levels of perlecan fragments, with most derived from domain IV. Perlecan fragments in PCa sera were associated with overall MMP-7 staining levels in PCa tissues. Domain IV perlecan fragments were present in stage IV, but absent in normal, sera, suggesting perlecan degradation during metastasis. Together, perlecan fragments in sera and MMP-7 in tissues of PCa patients are measures of invasive PCa.

Distribution of Matrix Metalloproteinases in Human Atherosclerotic Carotid Plaques and Their Production by Smooth Muscle Cells and Macrophage Subsets

Purpose

In this study, the potential of matrix metalloproteinase (MMP) sense for detection of atherosclerotic plaque instability was explored. Secondly, expression of MMPs by macrophage subtypes and smooth muscle cells (SMCs) was investigated.

Procedures

Twenty-three consecutive plaques removed during carotid endarterectomy were incubated in MMPSense™ 680 and imaged with IVIS® Spectrum. mRNA levels of MMPs, macrophage markers, and SMCs were determined in plaque specimens, and in in vitro differentiated M1 and M2 macrophages.

Results

There was a significant difference between autofluorescence signals and MMPSense signals, both on the intraluminal and extraluminal sides of plaques. MMP-9 and CD68 messenger RNA (mRNA) expression was higher in hot spots, whereas MMP-2 and αSMA expression was higher in cold spots. In vitro M2 macrophages had higher mRNA expression of MMP-1, MMP-9, MMP-12, and TIMP-1 compared to M1 macrophages.

Conclusion

MMP-9 is most dominantly MMP present in atherosclerotic plaques and is produced by M2 rather than M1 macrophages.

Chemokine-Like Receptor 1 Regulates the Proliferation and Migration of Vascular Smooth Muscle Cells

Background

We aimed to explore how chemokine-like receptor 1 (CMKLR1) influences the proliferation and migration of vascular smooth muscle cells (VSMCs).

Material/Methods

Normal VSMCs, negative control VSMCs interfered by CMKLR1 gene, and VSMCs with stable knockdown of CMKLR1 gene were divided into the control group, PDGF group, negative-shRNA group, and CMKLR1-shRNA group. Both cell number counting and BrdU incorporation assays were employed to investigate the proliferation status of VSMCs. Transwell migration assay was used to measure the migration status of VSMCs. Inflammation markers, including cytokines IL-1β, IL-6, TNF-α, and chemokines MCP-1 in VSMCs, were detected by real-time quantitative RT-PCR. Western blotting assay was used to detect protein expressions of the MAPK pathway in VSMCs.

Results

The number of VSMCs and the OD value of BrdU in PDGF group were significantly higher than those in the control group (both P<0.05). Compared with the control and negative-shRNA group, the CMKLR1-shRNA group exhibited significantly reduced VSMCs number and BrdU OD value (both P<0.05). Transwell migration assay indicated that PDGF-BB promoted whereas CMKLR1-shRNA inhibited the migration of VSMCs. The expression of IL-1β, IL-6, TNF-α, and MCP-1 were up-regulated in the PDGF group but down-regulated in the CMKLR1-shRNA group. Compared with normal VSMCs, the protein level of p-ERK1/2 was up-regulated in VSMCs treated with PDGF-BB, while it was down-regulated in the CMKLR1-shRNA group.

Conclusions

CMKLR1 exacerbated the proliferation and migration of VSMCs by activating ERK1/2.

Intravenous transfusion of endothelial progenitor cells that overexpress vitamin D receptor inhibits atherosclerosis in apoE-deficient mice

Endothelial progenitor cells (EPCs) are widely used for angiogenic therapies, as well as predictive biomarkers to assess cardiovascular disease risk. However, it is unknown that whether overexpressed vitamin D receptor (VDR) in EPCs could help EPCs counteracting atherosclerotic risks. Here, we study intravenous transplantation of genetically modified EPCs over-expressing VDR in regulating endothelial dysfunction and spontaneously arising atherosclerotic plaques of ApoE-deficient mice. Firstly, we found that over-expression of VDR in EPCs could reduce atherosclerotic plaque formation in transplanted ApoE-/- mice. In addition, the concentration of serum HDL-C in ovVDR-EPCs group was much higher than that in control groups (ApoE-/- mice without injection or injected with fresh medium or adenovirus vector). While concentrations of serum total cholesterol, LDL-C, apoB and Lp (a) were negatively correlated with the expression level of VDR. What's more, improved serum concentration of NO and elevated serum and vessel wall expression of eNOS were observed in ovVDR-EPCs group. Furthermore, reduced expression and activity of MMP2, and elevated expression and activity of TIMP2 were detected in ovVDR-EPCs group. Taken together, intravenous transfusion of EPCs that overexpress VDR significantly inhibited atherosclerosis in ApoE-deficient mice and could be used as a potential method for angiogenic therapy.