Matrix metalloproteinase 12 accelerates the initiation of atherosclerosis and stimulates the progression of fatty streaks to fibrous plaques in transgenic rabbits

The anti-atherosclerotic effect of chronic AT1 receptor blocker treatment also depends on the ACE2/Ang(1-7)/Mas axis

Blockade of AT1-receptors by telmisartan (TEL) has anti-atherosclerotic efficacy. We investigated to what extent the ACE2/Ang1-7/Mas axis-dependent mechanism contributes to the TEL-induced protection of endothelial function. Atherosclerosis was induced in C57BL/6 N, Mas-knock out (ko), and Ace2-ko mice by AAV-PCSK9DY (2 ×1011 VG) injections plus Western diet (WD) feeding (12w). Mice were treated (12w) with TEL or vehicle. Controls received no PCSK9DY, chow-feeding, and vehicle-treatment. In the aortae of mice, the plaque burden was determined, RNAseq analyses were performed and functional properties were assessed by quantifying the mechanical properties of the endothelial surface by Atomic Force Microscopy. Regardless of strain, plaque burden and total cholesterol were increased upon AAV-PCSK9DY+WD but decreased by TEL. Cortical stiffness was also enhanced in all strains by AAV-PCSK9DY+WD but reduced under TEL only in the C57BL/6 N, while remaining still high in both knockout strains. Plasma NO negatively correlated with cortical stiffness in C57BL/6 N, but not in transgenic mice. TNFα plasma levels and aortic MMP12 expression was increased in PCSK9DY/WD vehicle-treated controls and was normalized by TEL in C57BL/6 N but not in Mas-ko and Ace2-ko mice. We conclude that TEL-induced reduction of endothelial stiffness occurred only in the C57BL/6 N but not in the Mas-ko and Ace2-ko mice. We suggest that the protective TEL effect is partly due to an Ang(1-7)/ACE2/Mas axis mediated mechanism. Since Mmp12 has well-known proatherogenic properties but was not altered in the two transgenic mouse lines, follow-up studies are required to further elucidate the correlation between Mmp12 and the Ang(1-7)/ACE2/Mas axis with respect to atherosclerosis.

Matrix metalloproteinase-driven epithelial-mesenchymal transition: implications in health and disease

Epithelial-mesenchymal transition (EMT) is a process in which epithelial cells, defined by apical-basal polarity and tight intercellular junctions, acquire migratory and invasive properties characteristic of mesenchymal cells. Under normal conditions, EMT directs essential morphogenetic events in embryogenesis and supports tissue repair. When dysregulated, EMT contributes to pathological processes such as organ fibrosis, chronic inflammation, and cancer progression and metastasis. Matrix metalloproteinases (MMPs)-a family of zinc-dependent proteases that degrade structural components of the extracellular matrix-sit at the nexus of this transition by dismantling basement membranes, activating pro-EMT signaling pathways, and cleaving adhesion molecules. When normally regulated, MMPs promote balanced ECM turnover and support the cyclical remodeling necessary for proper development, wound healing, and tissue homeostasis. When abnormally regulated, MMPs drive excessive ECM turnover, thereby promoting EMT-related pathologies, including tumor progression and fibrotic disease. This review provides an integrated overview of the molecular mechanisms by which MMPs both initiate and sustain EMT under physiological and disease conditions. It discusses how MMPs can potentiate EMT through TGF-β and Wnt/β-catenin signaling, disrupt cell-cell junction proteins, and potentiate the action of hypoxia-inducible factors in the tumor microenvironment. It discusses how these pathologic processes remodel tissues during fibrosis, and fuel cancer cell invasion, metastasis, and resistance to therapy. Finally, the review explores emerging therapeutic strategies that selectively target MMPs and EMT, ranging from CRISPR/Cas-mediated interventions to engineered tissue inhibitors of metalloproteinases (TIMPs), and demonstrates how such approaches may suppress pathological EMT without compromising its indispensable roles in normal biology.

Mitochondria-targeted hydrogen sulfide donor reduces atherogenesis by changing macrophage phenotypes and increasing UCP1 expression in vascular smooth muscle cells

Atherosclerosis is a leading cause of morbidity and mortality in the Western countries. Mounting evidence points to the role of mitochondrial dysfunction in the pathogenesis of atherosclerosis. Recently, it has been shown that mitochondrial hydrogen sulfide (H2S) can complement the bioenergetic role of Krebs cycle leading to improved mitochondrial function. However, controlled, direct delivery of H2S to mitochondria was not investigated as a therapeutic strategy in atherosclerosis. Therefore, the aim of our study was to comprehensively evaluate the influence of prolonged treatment with mitochondrial H2S donor AP39 on the development of atherosclerotic lesions in apolipoprotein E knockout (apoE-/-) mice. Our results indicated that AP39 reduced atherosclerosis in apoE-/- mice and stabilized atherosclerotic lesions through decreased total macrophage content and increased collagen depositions. Moreover, AP39 reduced proinflammatory M1-like macrophages and increased anti-inflammatory M2-like macrophages in atherosclerotic lesions. It also upregulated pathways related to mitochondrial function, such as cellular respiration, fatty acid β-oxidation and thermogenesis while downregulated pathways associated with immune system, platelet aggregation and complement and coagulation cascades in the aorta. Furthermore, treatment with AP39 increased the expression of mitochondrial brown fat uncoupling protein 1 (UCP1) in vascular smooth muscle cells (VSMCs) in atherosclerotic lesions and upregulated mRNA expression of other thermogenesis-related genes in the aorta but not perivascular adipose tissue (PVAT) of apoE-/- mice. Finally, AP39 treatment decreased markers of activated endothelium and increased endothelial nitric oxide synthase (eNOS) expression and activation. Taken together, mitochondrial H2S donor AP39 could provide potentially a novel therapeutic approach to the treatment/prevention of atherosclerosis.

ECM Microenvironment in Vascular Homeostasis: New Targets for Atherosclerosis

Alterations in vascular extracellular matrix (ECM) components, interactions, and mechanical properties influence both the formation and stability of atherosclerotic plaques. This review discusses the contribution of the ECM microenvironment in vascular homeostasis and remodeling in atherosclerosis, highlighting Cartilage oligomeric matrix protein (COMP) and its degrading enzyme ADAMTS7 as examples, and proposes potential avenues for future research aimed at identifying novel therapeutic targets for atherosclerosis based on the ECM microenvironment.

Development of a Microminipig Model of Atherosclerosis for the Evaluation of a HMGCR Inhibitor

BACKGROUND/AIM

Atherosclerosis is known as a major risk factor for cardiovascular disease, and development of an animal model of atherosclerosis is required to investigate its clinical pathogenesis. We studied the optimal amount of cholesterol in the diet and the optimal experimental period for development of a Microminipig model of atherosclerosis for the evaluation of a hydroxymethylglutaryl-CoA reductase (HMGCR) inhibitor (atorvastatin).

MATERIALS AND METHODS

Eighteen male animals (3-4 months old) were divided into 3 groups. Group 1 consisted of control animals receiving a normal chow diet, Group 2 animals received a high fat (12% w/w) and low cholesterol (0.1% w/w) diet (HFLCD), and Group 3 animals received HFLCD+statin for 12 weeks. Animals received statin at 3 mg/kg body weight per day. HFLCD did not down-regulate the hepatic expression of HMGCR mRNA.

RESULTS

HFLCD increased body, omentum, and mesenteric adipose tissue weight, and induced hypercholesterolemia and atherosclerotic lesions in the abdominal aorta. HFLCD+statin inhibited hypercholesterolemia and atherosclerotic lesions, but not obesity.

CONCLUSION

A microminipig atherosclerosis model induced by HFLCD can be used in the evaluation of HMGCR inhibitors for the treatment of hypercholesterolemia and atherosclerosis.

The Role of Matrix Metalloproteinase in Inflammation with a Focus on Infectious Diseases

Matrix metalloproteinases (MMPs) are involved in extracellular matrix remodeling through the degradation of extracellular matrix components and are also involved in the inflammatory response by regulating the pro-inflammatory cytokines TNF-α and IL-1β. Dysregulation in the inflammatory response and changes in the extracellular matrix by MMPs are related to the development of various diseases including lung and cardiovascular diseases. Therefore, numerous studies have been conducted to understand the role of MMPs in disease pathogenesis. MMPs are involved in the pathogenesis of infectious diseases through a dysregulation of the activity and expression of MMPs. In this review, we discuss the role of MMPs in infectious diseases and inflammatory responses. Furthermore, we present the potential of MMPs as therapeutic targets in infectious diseases.

CXCR6 Mediates Pressure Overload-Induced Aortic Stiffness by Increasing Macrophage Recruitment and Reducing Exosome-miRNA29b

Aortic stiffness is an independent risk factor for aortic diseases such as aortic dissection which commonly occurred with aging and hypertension. Chemokine receptor CXCR6 is critically involved in vascular inflammation and remodeling. Here, we investigated whether and how CXCR6 plays a role in aortic stiffness caused by pressure overload. CXCR6^-/- and WT mice underwent transverse aortic constriction (TAC) surgery for 8 weeks. CXCR6 deficiency significantly improved TAC-induced aortic remodeling and endothelial dysfunction by decreasing CD11c⁺ macrophage infiltration, suppressing VCAM-1 and ICAM-1, reducing collagen deposition, and downregulating MMP12 and osteopontin in the aorta. Consistently, blocking the CXCL16/CXCR6 axis also reduced aortic accumulation of CD11c⁺ macrophages and vascular stiffness but without affecting the release of TNF-α and IL-6 from the aorta. Furthermore, pressure overload inhibited aortic release of exosomes, which could be reversed by suppressing CXCR6 or CXCL16. Inhibition of exosome release by GW4869 significantly aggravated TAC-induced aortic calcification and stiffness. By exosomal microRNA microarray analysis, we found that microRNA-29b was significantly reduced in aortic endothelial cells (AECs) receiving TAC. Intriguingly, blocking the CXCL16/CXCR6 axis restored the expression of miR-29b in AECs. Finally, overexpression of miR-29b significantly increased eNOS and reduced MMPs and collagen in AECs. By contrast, antagonizing miR-29b in vivo further enhanced TAC-induced expressions of MMP12 and osteopontin, aggravated aortic fibrosis, calcification, and stiffness. Our study demonstrated a key role of the CXCL16/CXCR6 axis in macrophage recruitment and macrophage-mediated aortic stiffness under pressure overload through an exosome-miRNAs-dependent manner.

Genetically modified rabbit models for cardiovascular medicine

Genetically modified (GM) rabbits are outstanding animal models for studying human genetic and acquired diseases. As such, GM rabbits that express human genes have been extensively used as models of cardiovascular disease. Rabbits are genetically modified via prokaryotic microinjection. Through this process, genes are randomly integrated into the rabbit genome. Moreover, gene targeting in embryonic stem (ES) cells is a powerful tool for understanding gene function. However, rabbits lack stable ES cell lines. Therefore, ES-dependent gene targeting is not possible in rabbits. Nevertheless, the RNA interference technique is rapidly becoming a useful experimental tool that enables researchers to knock down specific gene expression, which leads to the genetic modification of rabbits. Recently, with the emergence of new genetic technology, such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), clustered regularly interspaced short palindromic repeats (CRISPR), and CRISPR-associated protein 9 (CRISPR/Cas9), major breakthroughs have been made in rabbit gene targeting. Using these novel genetic techniques, researchers have successfully modified knockout (KO) rabbit models. In this paper, we aimed to review the recent advances in GM technology in rabbits and highlight their application as models for cardiovascular medicine.

Doxycycline Decreases Atherosclerotic Lesions in the Aorta of ApoE-⁄- and Ovariectomized Mice with Correlation to Reduced MMP-2 Activity

Atherogenic events promote changes in vessel walls, with alteration of the redox state, and increased activity of matrix metalloproteinases (MMPs). Thus, this study aims to evaluate aortic remodeling, MMP activity, and reactive oxygen species (ROS) levels after treatment with doxycycline in ApoE-⁄- and ovariectomized mice (OVX). Female ApoE-⁄--knockout mice (5 weeks) were submitted to ovariectomy surgery to induce experimental menopause. They then received chow enriched with 1% cholesterol to induce hypercholesterolemia. The animals were divided into two experimental groups: ApoE-⁄-/OVX vehicle and ApoE-⁄-/OVX doxycycline (30 mg/kg) administered by gavage once a day for 28 days (15th to the 18th week of life). Blood samples were collected to measure total cholesterol and fractions. The aorta was used for morphometry and to measure the activity and expression of MMP-2 and ROS levels. The ApoE-⁄-/OVX doxycycline group showed no change in total and fraction cholesterol levels. However, there was a reduction in ROS levels, MMP-2 expression, and activity that correlated with a decrease in atherosclerotic lesions relative to the ApoE-⁄-/OVX vehicle (p > 0.05). Therefore, we conclude that doxycycline in ApoE-⁄-/OVX animals promotes a reduction in atherosclerotic lesions by reducing ROS and MMP-2 activity and expression.

Systemic deficiency of vitronectin is associated with aortic inflammation and plaque progression in ApoE-Knockout mice

Optimal cell spreading and interplay of vascular smooth muscle cells (VSMC), inflammatory cells, and cell adhesion molecules (CAM) are critical for progressive atherosclerosis and cardiovascular complications. The role of vitronectin (VTN), a major cell attachment glycoprotein, in the pathogenesis of atherosclerosis remains elusive. In this study, we attempt to examine the pathological role of VTN in arterial plaque progression and inflammation. We found that, relative expression analysis of VTN from the liver of Apolipoprotein E (ApoE) Knockout mice revealed that atherosclerotic progression induced by feeding mice with high cholesterol diet (HCD) causes a significant downregulation of VTN mRNA as well as protein after 60 days. Promoter assay confirmed that cholesterol modulates the expression of VTN by influencing its promoter. Mimicking VTN reduction with siRNA in HCD fed ApoE Knockout mice, accelerated athero-inflammation with an increase in NF-kB, ICAM-1, and VCAM-1 at the site of the plaque along with upregulation of inflammatory proteins like MCP-1 and IL-1β in the plasma. Also, matrix metalloprotease (MMP)-9 and MMP-12 expression were increased and collagen content was decreased in the plaque, in VTN deficient condition. This might pose a challenge to plaque integrity. Human subjects with acute coronary syndrome or having risk factors of atherosclerosis have lower levels of VTN compared to healthy controls suggesting a clinical significance of plasma VTN in the pathophysiology of coronary artery disease. We establish that, VTN plays a pivotal role in cholesterol-driven atherosclerosis and aortic inflammation and might be a useful indicator for atherosclerotic plaque burden and stability.

Matrix Metalloproteinase-9 Gene Polymorphism and Its Methylation in Stroke Patients

Background

Genetic and environmental factors, along with hypertension, diabetes mellitus and smoking cause accelerated atherosclerosis and, eventually, stroke. Matrix metalloproteinase-9 (MMP-9) are inflammatory mediators of the endoproteinase family, and their polymorphism and methylation are associated with the development of atherosclerosis and stroke. This study explores this association in the Indian population.

Objective

To study the association of MMP gene polymorphism and methylation with the risk of stroke.

Methods

A case-control study was conducted on 100 admitted patients (both genders) diagnosed with ischaemic stroke. Another 100 healthy subjects, not suffering from any chronic illness or stroke, were taken as controls. All participants were genotyped for rs3918242 (MMP-9) by polymerase chain reaction (PCR) and restriction fragment length polymorphism. Methylation of the MMP-9 gene-promoter region was assessed by methylation-specific PCR.

Results

The case (mean age = 61.3 ± 7.36 years old) and control (mean age = 60.68 ± 7.1 years old) groups were age-matched. Among cases, 61 patients were smokers, 55 were diabetic and 53 were hypertensive. A significant risk of ischaemic stroke was associated with the CT genotype (adjusted odds ratio [aOR] = 7.09; P < 0.001), TT genotype (aOR = 19.75; P < 0.001) and T allele (aOR = 10.71; P < 0.001). MMP-9 methylation decreased the risk of stroke (aOR = 0.23; P < 0.001).

Conclusion

MMP-9 gene-1562C/T polymorphism (SNP rs3918242) (single-nucleotide polymorphism [SNP] rs3918242) is a potential marker to predict ischaemic stroke and constitutes a significant proportion of the general population. Its polymorphism predisposes to ischaemic stroke, while its methylation is protective.

Disparate effects of MMP and TIMP modulation on coronary atherosclerosis and associated myocardial fibrosis

Matrix metalloproteinase (MMP) activity is tightly regulated by the endogenous tissue inhibitors (TIMPs), and dysregulated activity contributes to extracellular matrix remodelling. Accordingly, MMP/TIMP balance is associated with atherosclerotic plaque progression and instability, alongside adverse post-infarction cardiac fibrosis and subsequent heart failure. Here, we demonstrate that prolonged high-fat feeding of apolipoprotein (Apo)e-deficient mice triggered the development of unstable coronary artery atherosclerosis alongside evidence of myocardial infarction and progressive sudden death. Accordingly, the contribution of select MMPs and TIMPs to the progression of both interrelated pathologies was examined in Apoe-deficient mice with concomitant deletion of Mmp7, Mmp9, Mmp12, or Timp1 and relevant wild-type controls after 36-weeks high-fat feeding. Mmp7 deficiency increased incidence of sudden death, while Mmp12 deficiency promoted survival, whereas Mmp9 or Timp1 deficiency had no effect. While all mice harboured coronary disease, atherosclerotic burden was reduced in Mmp7-deficient and Mmp12-deficient mice and increased in Timp1-deficient animals, compared to relevant controls. Significant differences in cardiac fibrosis were only observed in Mmp-7-deficient mice and Timp1-deficient animals, which was associated with reduced capillary number. Adopting therapeutic strategies in Apoe-deficient mice, TIMP-2 adenoviral-overexpression or administration (delayed or throughout) of a non-selective MMP inhibitor (RS-130830) had no effect on coronary atherosclerotic burden or cardiac fibrosis. Taken together, our findings emphasise the divergent roles of MMPs on coronary plaque progression and associated post-MI cardiac fibrosis, highlighting the need for selective therapeutic approaches to target unstable atherosclerosis alongside adverse cardiac remodelling while negating detrimental adverse effects on either pathology, with targeting of MMP-12 seeming a suitable target.

Reversal of elastase-induced abdominal aortic aneurysm following the delivery of nanoparticle-based pentagalloyl glucose (PGG) is associated with reduced inflammatory and immune markers

OBJECTIVE

An Abdominal aortic aneurysm (AAA), a deadly disease in elderly population, is featured by expansion of aortic diameter, degradation and weakening of vasculature. Its common and significant characteristics are disarray and inflammation in vasculature. We tested the hypothesis that the reversal of abdominal aortic aneurysm by pentagalloyl glucose-loaded nanoparticles (PGG-NPs) therapy that targets degraded elastin suppresses inflammatory and immune markers to ameliorate the pathophysiology of the disease in advance stage aneurysm in a porcine pancreatic elastase (PPE)-induced mouse model of AAA.

METHODS AND RESULTS

After induction of aneurysm in pathogen-free C57BL/6 male mice by applying PPE peri-adventitially to the abdominal aorta, once a week for two doses of intravenous injections of pentagalloyl glucose-loaded nanoparticles (PGG-NPs) conjugated with elastin targeted antibody were used to reverse the aneurysms. We showed that PGG-NPs therapy could suppress infiltration of macrophages, CD8 and CD4 subsets of T cells, matrix metalloproteinases (MMPs), inflammatory cytokines interferon (IFN-γ) and interleukin (IL)-6 at the local and systemic level. Moreover, such PGG-NPs therapy increases the induction of anti-inflammatory cytokines IL-13, IL-27 and IL-10 at the local and systemic level. The therapy also led to remodeling of elastic lamina at the aneurysm site.

CONCLUSION

Nanoparticles-loaded pentagalloyl glucose therapy can be an effective treatment option against advanced stage aneurysms to reverse the disease by ameliorating inflammation and restoring arterial homeostasis.

Matrix Metalloproteinase MMP-12 Promotes Macrophage Transmigration Across Intestinal Epithelial Tight Junctions and Increases Severity of Experimental Colitis

BACKGROUND AND AIMS

Matrix metalloproteinases [MMPs] play an important role in extracellular matrix regulation during cell growth and wound healing. Increased expression of MMP-12 [human macrophage elastase] has been reported in inflammatory bowel disease [IBD] which is characterised by the loss of epithelial tight junction [TJ] barrier function and an excessive inflammatory response. The aim of this study was to investigate the role of MMP-12 in intestinal TJ barrier function and inflammation.

METHODS

Wild type [WT] and MMP-12-/- mice were subjected to experimental acute or chronic dextran sodium sulphate [DSS] colitis. The mouse colonic permeability was measured in vivo by recycling perfusion of the entire colon and ex vivo by Ussing chamber studies.

RESULTS

DSS administration increased colonic permeability through modulation of TJ proteins and also increased MMP-12 expression in the colonic mucosa of WT mice. The acute as well as chronic DSS-induced increase in colonic TJ permeability and the severity of DSS colitis was found to be markedly attenuated in MMP-12-/- mice. The resistance of MMP-12-/- mice to DSS colitis was characterised by reduced macrophage infiltration and transmigration, and reduced basement membrane laminin degradation. Further in vitro and in vivo studies show that macrophage transmigration across the epithelial layer is MMP-12 dependent and the epithelial TJ barrier is compromised during macrophage transmigration. Conclusions: Together, these data demonstrate that MMP-12 mediated degradation of basement membrane laminin, macrophage transmigration, and associated loss of intestinal TJ barrier are key pathogenic factors for intestinal inflammation.

Senescence-induced inflammation: an important player and key therapeutic target in atherosclerosis

Inflammation is a hallmark and potent driver of pathological vascular remodelling in atherosclerosis. However, current anti-inflammatory therapeutic strategies have shown mixed results. As an alternative perspective on the conundrum of chronic inflammation emerging evidence points towards a small subset of senescent cells as a critical player and central node driving atherosclerosis. Senescent cells belonging to various cell types are a dominant and chronic source of a large array of pro-inflammatory cytokines and various additional plaque destabilizing factors, being involved with various aspects of atherosclerosis pathogenesis. Antagonizing these key agitators of local chronic inflammation and plaque instability may provide a causative and multi-purpose therapeutic strategy to treat atherosclerosis. Anti-senescence treatment options with translational potential are currently in development. However, several questions and challenges remain to be addressed before these novel treatment approaches may enter the clinical setting.

Targeting the Extracellular Matrix in Abdominal Aortic Aneurysms Using Molecular Imaging Insights

This review outlines recent preclinical and clinical advances in molecular imaging of abdominal aortic aneurysms (AAA) with a focus on molecular magnetic resonance imaging (MRI) of the extracellular matrix (ECM). In addition, developments in pharmacologic treatment of AAA targeting the ECM will be discussed and results from animal studies will be contrasted with clinical trials. Abdominal aortic aneurysm (AAA) is an often fatal disease without non-invasive pharmacologic treatment options. The ECM, with collagen type I and elastin as major components, is the key structural component of the aortic wall and is recognized as a target tissue for both initiation and the progression of AAA. Molecular imaging allows in vivo measurement and characterization of biological processes at the cellular and molecular level and sets forth to visualize molecular abnormalities at an early stage of disease, facilitating novel diagnostic and therapeutic pathways. By providing surrogate criteria for the in vivo evaluation of the effects of pharmacological therapies, molecular imaging techniques targeting the ECM can facilitate pharmacological drug development. In addition, molecular targets can also be used in theranostic approaches that have the potential for timely diagnosis and concurrent medical therapy. Recent successes in preclinical studies suggest future opportunities for clinical translation. However, further clinical studies are needed to validate the most promising molecular targets for human application.

Blackcurrant (Ribes nigrum L.) Extract Exerts Potential Vasculoprotective Effects in Ovariectomized Rats, Including Prevention of Elastin Degradation and Pathological Vascular Remodeling

Estrogen exerts cardioprotective effects in menopausal women. Phytoestrogens are plant-derived substances exhibiting estrogenic activity that could beneficially affect vascular health. We previously demonstrated that blackcurrant (Ribes nigrum L.) extract (BCE) treatment exerted beneficial effects on vascular health via phytoestrogenic activity in ovariectomized (OVX) rats, which are widely used as menopausal animal models. Here, we examined whether BCE treatment reduced elastin degradation and prevented pathological vascular remodeling in OVX rats fed a regular diet (OVX Control) or a 3% BCE-supplemented diet (OVX BCE), compared with sham surgery rats fed a regular diet (Sham) for 3 months. The results indicated a lower staining intensity of elastic fibers, greater elastin fragmentation, and higher α-smooth muscle actin protein expression in OVX Control rats than in OVX BCE and Sham rats. Pathological vascular remodeling was only observed in OVX Control rats. Additionally, we investigated matrix metalloproteinase (MMP)-12 mRNA expression levels to elucidate the mechanism underlying elastin degradation, revealing significantly upregulated MMP-12 mRNA expression in OVX Control rats compared with that in Sham and OVX BCE rats. Together, we identify BCE as exerting a vascular protective effect through reduced MMP-12 expression and vascular smooth muscle cell proliferation. To our knowledge, this is the first report indicating that BCE might protect against elastin degradation and pathological vascular remodeling during menopause.

Genetically Modified Rabbits for Cardiovascular Research

Rabbits are one of the most used experimental animals for investigating the mechanisms of human cardiovascular disease and lipid metabolism because they are phylogenetically closer to human than rodents (mice and rats). Cholesterol-fed wild-type rabbits were first used to study human atherosclerosis more than 100 years ago and are still playing an important role in cardiovascular research. Furthermore, transgenic rabbits generated by pronuclear microinjection provided another means to investigate many gene functions associated with human disease. Because of the lack of both rabbit embryonic stem cells and the genome information, for a long time, it has been a dream for scientists to obtain knockout rabbits generated by homologous recombination-based genomic manipulation as in mice. This obstacle has greatly hampered using genetically modified rabbits to disclose the molecular mechanisms of many human diseases. The advent of genome editing technologies has dramatically extended the applications of experimental animals including rabbits. In this review, we will update genetically modified rabbits, including transgenic, knock-out, and knock-in rabbits during the past decades regarding their use in cardiovascular research and point out the perspectives in future.

Outside-in signaling by femoral cuff injury induces a distinct vascular lesion in adipose triglyceride lipase knockout mice

Genetic deficiency of adipose triglyceride lipase (ATGL), a rate-limiting enzyme for intracellular triglyceride (TG) hydrolysis, causes TG-deposit cardiomyovasculopathy (TGCV), a recently identified rare cardiovascular disorder (ORPHA code: 565612) in humans. One of the major characteristics of TGCV is a novel type of diffuse and concentric coronary atherosclerosis with ATGL-deficient smooth muscle cells (SMCs). Patients with TGCV have intractable coronary artery disease. Therefore, it is crucial to investigate the mechanisms underlying vascular lesions in ATGL deficiency using animal models. Cuff injury is an experimental procedure to induce vascular remodeling with neointimal formation with SMCs after placing a cuff around the adventitial side of the artery without direct influence on endothelium. We report the effect of cuff injury on femoral arteries of ATGL-knockout (ATGL⁻/⁻) mice. Cuff-induced concentric neointimal formation with migrating SMCs was exacerbated in ATGL⁻/⁻ mice, mimicking atherosclerotic lesions in patients with TGCV. In the media, cell death of SMCs and loss of elastic fibers increased. Perivascular infiltrating cells expressing tumor necrosis factor-α (TNF-α) were more prominent in ATGL⁻/⁻ mice than in wild-type (WT) mice. In Boyden chamber experiments, a greater number of ATGL⁻/⁻ SMCs migrated in response to TNF-α compared to WT SMCs. These data, for the first time, demonstrated that outside-in signaling by cuff-induced neointimal formation where paracrine stimuli from adventitial infiltrating cells may lead to neointimal formation and mediolysis in ATGL-deficient conditions. Cuff injury might be a valuable model for understanding the mechanisms underlying the development of atherosclerotic lesions in patients with TGCV.

Galectin-3 Identifies a Subset of Macrophages With a Potential Beneficial Role in Atherosclerosis

OBJECTIVE

Galectin-3 (formerly known as Mac-2), encoded by the LGALS3 gene, is proposed to regulate macrophage adhesion, chemotaxis, and apoptosis. We investigated the role of galectin-3 in determining the inflammatory profile of macrophages and composition of atherosclerotic plaques. Approach and Results: We observed increased accumulation of galectin-3-negative macrophages within advanced human, rabbit, and mouse plaques compared with early lesions. Interestingly, statin treatment reduced galectin-3-negative macrophage accrual in advanced plaques within hypercholesterolemic (apolipoprotein E deficient) Apoe-/- mice. Accordingly, compared with Lgals3+/+:Apoe-/- mice, Lgals3-/-:Apoe-/- mice displayed altered plaque composition through increased macrophage:smooth muscle cell ratio, reduced collagen content, and increased necrotic core area, characteristics of advanced plaques in humans. Additionally, macrophages from Lgals3-/- mice exhibited increased invasive capacity in vitro and in vivo. Furthermore, loss of galectin-3 in vitro and in vivo was associated with increased expression of proinflammatory genes including MMP (matrix metalloproteinase)-12, CCL2 (chemokine [C-C motif] ligand 2), PTGS2 (prostaglandin-endoperoxide synthase 2), and IL (interleukin)-6, alongside reduced TGF (transforming growth factor)-β1 expression and consequent SMAD signaling. Moreover, we found that MMP12 cleaves macrophage cell-surface galectin-3 resulting in the appearance of a 22-kDa fragment, whereas plasma levels of galectin-3 were reduced in Mmp12-/-:Apoe-/- mice, highlighting a novel mechanism where MMP12-dependent cleavage of galectin-3 promotes proinflammatory macrophage polarization. Moreover, galectin-3-positive macrophages were more abundant within plaques of Mmp12-/-:Apoe-/- mice compared with Mmp12+/+:Apoe-/- animals.

CONCLUSIONS

This study reveals a prominent protective role for galectin-3 in regulating macrophage polarization and invasive capacity and, therefore, delaying plaque progression.

Discovery of novel biomarkers for atherosclerotic aortic aneurysm through proteomics-based assessment of disease progression

Since aortic aneurysms (AAs) are mostly asymptomatic, but they have a high mortality rate upon rupture, their detection and progression evaluation are clinically important issues. To discover diagnostic biomarkers for AA, we performed proteome analysis of aortic media from patients with thoracic atherosclerotic AA (TAAA), comparing protein levels between the aneurysm and normal tissue areas. After hierarchical clustering analysis of the proteome analysis data, tissue samples were classified into three groups, regardless of morphological features. This classification was shown to reflect disease progression stage identified by pathological examination. This proteomics-based staging system enabled us to identify more significantly altered proteins than the morphological classification system. In subsequent data analysis, Niemann-Pick disease type C2 protein (NPC2) and insulin-like growth factor-binding protein 7 (IGFBP7) were selected as novel biomarker candidates for AA and were compared with the previously reported biomarker, thrombospondin 1 (THBS1). Blood concentrations of NPC2 and IGFBP7 were significantly increased, while THBS1 levels were decreased in TAAA and abdominal atherosclerotic AA patients. Receiver operating characteristic analysis of AA patients and healthy controls showed that NPC2 and IGFBP7 have higher specificity and sensitivity than THBS1. Thus, NPC2 and IGFBP7 are promising biomarkers for the detection and progression evaluation of AA.

The plasma protein profile and cardiovascular risk differ between intima-media thickness of the common carotid artery and the bulb: A meta-analysis and a longitudinal evaluation

BACKGROUND AND AIMS

Genetic loci associated with CHD show different relationships with intima-media thickness in the common carotid artery (IMT-CCA) and in the bulb (IMT-bulb). We evaluated if IMT-CCA and IMT-bulb differ also with respect to circulating protein profiles and risk of incident atherosclerotic disease.

METHODS

In three Swedish cohorts (MDC, IMPROVE, PIVUS, total n > 7000), IMT-CCA and IMT-bulb were assessed by ultrasound at baseline, and 86 cardiovascular-related proteins were analyzed. In the PIVUS study only, IMT-CCA and IMT-bulb were investigated in relation to incident atherosclerotic disease over 10 years of follow-up.

RESULTS

In a meta-analysis of the analysis performed separately in the cohorts, three proteins, matrix metalloproteinase-12 (MMP-12), hepatocyte growth factor (HGF) and N-terminal pro-B-type natriuretic peptide (NT-proBNP), were associated with IMT-CCA when adjusted for traditional cardiovascular risk factors. Five proteins were associated with IMT-bulb (MMP-12, growth/differentiation factor 15 (GDF-15), osteoprotegerin, growth hormone and renin). Following adjustment for cardiovascular risk factors, IMT-bulb was significantly more closely related to incident stroke or myocardial infarction (total number of cases, 111) than IMT-CCA in the PIVUS study (HR 1.51 for 1 SD, 95%CI 1.21-1.87, p < 0.001 vs HR 1.17, 95%CI 0.93-1.47, p = 0.16). MMP-12 levels were related to this combined end-point (HR 1.30, 95%CI 1.08-1.56, p = 0.0061).

CONCLUSIONS

Elevated levels of MMP-12 were associated with both IMT-CCA and IMT-bulb, but other proteins were significantly related to IMT in only one of these locations. The finding that IMT-bulb was more closely related to incident atherosclerotic disease than IMT-CCA emphasizes a difference between these measurements of IMT.

Depletion of WNT10A Prevents Tumor Growth by Suppressing Microvessels and Collagen Expression

Background: We recently reported that WNT10A plays a pivotal role in wound healing by regulating collagen expression/synthesis, as the depletion of WNT10A dramatically delays skin ulcer formation. WNT signaling also has a close correlation with the cancer microenvironment and proliferation, since tumors are actually considered to be 'unhealing' or 'overhealing' wounds. To ascertain the in vivo regulatory functions of WNT10A in tumor growth, we examined the net effects of WNT10A depletion using Wnt10a-deficient mice (Wnt10a -/-). Methods and Results: We subjected C57BL/6J wild-type (WT) or Wnt10a -/- mice to murine melanoma B16-F10 cell transplantation. Wnt10a -/- mice showed a significantly smaller volume of transplanted melanoma as well as fewer microvessels and less collagen expression and more necrosis than WT mice. Conclusions: Taken together, our observations suggest that critical in vivo roles of Wnt10a-depleted anti-stromagenesis prevent tumor growth, in contrast with true wound healing/scarring.

Cardiovascular protection in females linked to estrogen-dependent inhibition of arterial stiffening and macrophage MMP12

Arterial stiffening is a consequence of aging and a cholesterol-independent risk factor for cardiovascular disease (CVD). Arterial stiffening and CVD show a sex bias, with men more susceptible than premenopausal women. How arterial stiffness and sex interact at a molecular level to confer risk of CVD is not well understood. Here, we used the sexual dimorphism in LDLR-null mice to show that the protective effect of female sex on atherosclerosis is linked to reduced aortic stiffness and reduced expression of matrix metalloproteinase-12 (MMP12) by lesional macrophages. Deletion of MMP12 in LDLR-null mice attenuated the male sex bias for both arterial stiffness and atherosclerosis, and these effects occurred despite high serum cholesterol. Mechanistically, we found that oxidized LDL stimulates secretion of MMP12 in human as well as mouse macrophages. Estrogen antagonizes this effect by downregulating MMP12 expression. Our data support cholesterol-independent causal relationships between estrogen, oxidized LDL-induced secretion of macrophage MMP12, and arterial stiffness that protect against atherosclerosis in females and emphasize that reduced MMP12 functionality can confer atheroprotection to males.

Predictive value of targeted proteomics for coronary plaque morphology in patients with suspected coronary artery disease

Background

Risk stratification is crucial to improve tailored therapy in patients with suspected coronary artery disease (CAD). This study investigated the ability of targeted proteomics to predict presence of high-risk plaque or absence of coronary atherosclerosis in patients with suspected CAD, defined by coronary computed tomography angiography (CCTA).

Methods

Patients with suspected CAD (n = 203) underwent CCTA. Plasma levels of 358 proteins were used to generate machine learning models for the presence of CCTA-defined high-risk plaques or complete absence of coronary atherosclerosis. Performance was tested against a clinical model containing generally available clinical characteristics and conventional biomarkers.

Findings

A total of 196 patients with analyzable protein levels (n = 332) was included for analysis. A subset of 35 proteins was identified predicting the presence of high-risk plaques. The developed machine learning model had fair diagnostic performance with an area under the curve (AUC) of 0·79 ± 0·01, outperforming prediction with generally available clinical characteristics (AUC = 0·65 ± 0·04, p < 0·05). Conversely, a different subset of 34 proteins was predictive for the absence of CAD (AUC = 0·85 ± 0·05), again outperforming prediction with generally available characteristics (AUC = 0·70 ± 0·04, p < 0·05).

Interpretation

Using machine learning models, trained on targeted proteomics, we defined two complementary protein signatures: one for identification of patients with high-risk plaques and one for identification of patients with absence of CAD. Both biomarker subsets were superior to generally available clinical characteristics and conventional biomarkers in predicting presence of high-risk plaque or absence of coronary atherosclerosis. These promising findings warrant external validation of the value of targeted proteomics to identify cardiovascular risk in outcome studies.

Fund

This study was supported by an unrestricted research grant from HeartFlow Inc. and partly supported by a European Research Area Network on Cardiovascular Diseases (ERA-CVD) grant (ERA CVD JTC2017, OPERATION). Funders had no influence on trial design, data evaluation, and interpretation.

Hypertension Enhances Advanced Atherosclerosis and Induces Cardiac Death in Watanabe Heritable Hyperlipidemic Rabbits

Hypertension is a major risk factor for the development of atherosclerosis. Cardiovascular risk has been reported to be significantly increased in hyperlipidemic patients with hypertension. However, it is not clear whether hypertension can directly destabilize plaques, thereby enhancing cardiovascular events. To examine whether hypertension enhances the development of atherosclerosis and increases plaque vulnerability, we generated hypertensive Watanabe heritable hyperlipidemic (WHHL) rabbits by surgical removal of one kidney and partial ligation of the other renal artery and compared the nature of aortic and coronary atherosclerosis in hypertensive WHHL rabbits with normotensive WHHL rabbits. All hypertensive WHHL rabbits died from 34 to 56 weeks after surgery, whereas no normotensive WHHL rabbits died. Pathologic examinations revealed that hypertensive WHHL rabbits showed different degrees of myocardial infarction caused by severe coronary stenosis along with myocardial hypertrophy. Furthermore, aortic lesions in hypertensive WHHL rabbits exhibited a higher frequency of intraplaque hemorrhage and vulnerable plaques than those in normotensive WHHL rabbits. These results indicate that hypertension induced by the surgical removal of one kidney and partial ligation of the other renal artery method in WHHL rabbits may not only enhance the development of atherosclerosis but also destabilize the plaques, increasing cardiac death.

Critical in vivo roles of WNT10A in wound healing by regulating collagen expression/synthesis in WNT10A-deficient mice

BACKGROUND

We have reported that WNT10A plays a critical role in the growth of fibroblasts/myofibroblasts and microvascular endothelial cells, i.e.; wound healing/scarring. To ascertain the in vivo regulatory, central functions of WNT10A, we examined the net effects of WNT10A depletion using WNT10A-deficient mice (WNT10A-/-).

METHODS AND RESULTS

We generated WNT10A-/-mice, displaying a range of unique phenotypes of morpho/organogenetic failure, such as growth retardation, alopecia, kyphosis and infertility, and then focused on the functions of WNT10A in wound healing. We subjected C57BL/6J wild-type (WT) or WNT10A-/-mice to skin ulcer formation. The WNT10A-/-mice had significantly larger injured areas and delayed wound healing, which were associated with (a) a smaller number of fibroblasts/myofibroblasts and microvessels; and (b) more reduced expression and synthesis of collagen, compared with WT mice with intact WNT10A expression, especially in those with activated myofibroblasts.

CONCLUSIONS

These observations indicate that WNT10A signaling can play a pivotal in vivo role in wound healing by regulating the expression and synthesis of collagen, as one of fibrogenic factors, at least in part, and critical in vivo roles of WNT10A-mediated effective wound healing are extremely closely associated with collagen expression.

Principles and Applications of Rabbit Models for Atherosclerosis Research

Rabbits are one of the most used experimental animals for biomedical research, particularly as a bioreactor for the production of antibodies. However, many unique features of the rabbit have also made it as an excellent species for examining a number of aspects of human diseases such as atherosclerosis. Rabbits are phylogenetically closer to humans than rodents, in addition to their relatively proper size, tame disposition, and ease of use and maintenance in the laboratory facility. Due to their short life spans, short gestation periods, high numbers of progeny, low cost (compared with other large animals) and availability of genomics and proteomics, rabbits usually serve to bridge the gap between smaller rodents (mice and rats) and larger animals, such as dogs, pigs and monkeys, and play an important role in many translational research activities such as pre-clinical testing of drugs and diagnostic methods for patients. The principle of using rabbits rather than other animals as an experimental model is very simple: rabbits should be used for research, such as translational research, that is difficult to accomplish with other species. Recently, rabbit genome sequencing and transcriptomic profiling of atherosclerosis have been successfully completed, which has paved a new way for researchers to use this model in the future. In this review, we provide an overview of the recent progress using rabbits with specific reference to their usefulness for studying human atherosclerosis.

Peroxiredoxin 4 (PRDX4): Its critical in vivo roles in animal models of metabolic syndrome ranging from atherosclerosis to nonalcoholic fatty liver disease

The peroxiredoxin (PRDX) family, a new family of proteins with a pivotal antioxidative function, is ubiquitously synthesized and abundantly identified in various organisms. In contrast to the intracellular localization of other family members (PRDX1/2/3/5/6), PRDX4 is the only known secretory form and protects against oxidative damage by scavenging reactive oxygen species in both the intracellular (especially the endoplasmic reticulum) compartments and the extracellular space. We generated unique human PRDX4 (hPRDX4) transgenic (Tg) mice on a C57BL/6J background and investigated the critical and diverse protective roles of PRDX4 against diabetes mellitus, atherosclerosis, insulin resistance, and nonalcoholic fatty liver disease (NAFLD) as well as evaluated its role in the intestinal function in various animal models. Our published data have shown that PRDX4 helps prevent the progression of metabolic syndrome by reducing local and systemic oxidative stress and synergistically suppressing steatosis, inflammatory reactions, and/or apoptotic activity. These observations suggest that Tg mice may be a useful animal model for studying the relevance of oxidative stress on inflammation and the dysregulation of lipid/bile acid/glucose metabolism upon the progression of human metabolic syndrome, and that specific accelerators of PRDX4 may be useful as therapeutic agents for ameliorating various chronic inflammatory diseases.

Pathological Quantification of Carotid Artery Plaque Instability in Patients Undergoing Carotid Endarterectomy

BACKGROUND

Unstable atherosclerotic carotid plaques cause cerebral thromboemboli and ischemic events. However, this instability has not been pathologically quantified, so we sought to quantify it in patients undergoing carotid endarterectomy (CEA).

METHODS AND RESULTS

Carotid plaques were collected during CEA from 67 symptomatic and 15 asymptomatic patients between May 2015 and August 2016. The specimens were stained with hematoxylin-eosin and elastica-Masson. Immunohistochemistry was performed using an endothelial-specific antibody to CD31, CD34 and PDGFRβ. The histopathological characteristics of the plaques were studied. By multiple-variable logistic regression analysis, plaque instability correlated with the presence of plaque rupture [odds ratio (OR), 9.75; P=0.013], minimum fibrous cap thickness (OR per 10 μm 0.70; P=0.025), presence of microcalcifications in the fibrous cap (OR 7.82; P=0.022) and intraplaque microvessels (OR 1.91; P=0.043). Receiver-operating characteristics analyses showed that these factors combined into a single score diagnosed symptomatic carotid plaques in patients with carotid artery stenosis with a high level of accuracy (area under the curve 0.92; 95% confidence interval 0.85-0.99 vs. asymptomatic).

CONCLUSIONS

This analysis of carotid plaque instability strongly suggested that the diagnostic scoring of carotid plaque instability improves the understanding and treatment of carotid artery disease in patients undergoing CEA.

Cholic Acid Enhances Visceral Adiposity, Atherosclerosis and Nonalcoholic Fatty Liver Disease in Microminipigs

AIM

We have recently established a novel swine model for studies of atherosclerosis using MicrominipigsTM (µMPs) fed a high-fat/high-cholesterol diet (HcD). Using this swine model, we re-evaluated the effects of dietary cholic acid (CA) on serum lipid profile, atherosclerosis and hepatic injuries.

METHODS

The µMPs were fed HcD supplemented with 0.7% CA (HcD＋CA) for eight weeks, and the effect of CA on serum lipoprotein levels, expression of oxidative stress markers, adiposity and lesion formation in the aorta, liver, and other organs was investigated.

RESULTS

The HcD＋CA-fed group exhibited more visceral adiposity, progression of atherosclerosis and higher serum levels of oxidative stress markers than the HcD-fed group, even though they showed similar serum lipid levels. The liver demonstrated increased lipid accumulation, higher expression of oxidative stress markers, accelerated activation of foamy Kupffer cells and stellate cells, and increased hepatocyte apoptosis, indicating non-alcoholic fatty liver disease (NAFLD). Intriguingly, foamy macrophage mobilization was observed in various organs, including the reticuloendothelial system, pulmonary capillary vessels and skin very often in HcD＋CA-fed µMPs.

CONCLUSION

To our knowledge, this is the first large animal model, in which visceral obesity, NAFLD and atherosclerosis are concomitantly induced by dietary manipulation. These data suggest the detrimental effects of CA, potentially through local and systemic activation of oxidative stress-induced signaling to macrophage mobilization, on the acceleration of visceral adiposity, atherosclerosis and NAFLD.

Regulatory T CD4 + CD25+ lymphocytes increase in symptomatic carotid artery stenosis

BACKGROUND

Atherosclerosis is a multifactorial disease characterized by an immune-inflammatory remodeling of the arterial wall. Treg and Th17 subpopulations are detectable inside atherosclerotic plaque; however, their behavior in symptomatic carotid artery stenosis (CAS) is not fully elucidated. The aim of this study was to evaluate Th17 and Treg subsets and their ratio in patients affected by symptomatic and asymptomatic CAS.

METHODS

14 patients with symptomatic CAS (CAS-S group), 41 patients with asymptomatic CAS (CAS-A group), 32 subjects with traditional cardiovascular risk factors (RF group), and 10 healthy subjects (HS group) were enrolled. Th17 and Treg frequency was determined by flow cytometry and by histology and immunohistochemistry. Interleukin (IL)-10, IL-17, and metalloproteinase (MMP)-12 levels were measured by ELISA.

RESULTS

Th17 were significantly increased in CAS-A versus RF and versus HS. Tregs were significantly increased in CAS-S versus CAS-A. Tregs/Th17 ratio was significantly reduced in CAS-A versus RF and versus HS, whereas it was significantly increased in CAS-S versus CAS-A.

CONCLUSIONS

The results of this study suggest that Th17 are related to the late stages of CAS but not to plaque instability. Moreover, Treg expansion seems to represent a specific cellular pattern displayed by patients with symptomatic CAS and associated with brain injury. KEY MESSAGES Tregs expansion seems to represent a specific cellular pattern displayed by patients with symptomatic CAS and associated with CD4+ effector depletion and brain ischemic injury. Th17 lymphocytes are related to the late stages of CAS but not to plaque instability.

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.

MMP-12, a Promising Therapeutic Target for Neurological Diseases

The role of matrix metalloproteinase-12 (MMP-12) in the pathogenesis of several inflammatory diseases such as chronic obstructive pulmonary disease, emphysema, and asthma is well established. Several new studies and recent reports from our laboratory and others highlighted the detrimental role of MMP-12 in the pathogenesis of several neurological diseases. In this review, we discuss in detail the pathological role of MMP-12 and the possible underlying molecular mechanisms that contribute to disease pathogenesis in the context of central nervous system diseases such as stroke, spinal cord injury, and multiple sclerosis. The available information on the specific MMP-12 inhibitors used in several preclinical and clinical studies is also reviewed. Based on the reported studies to date, MMP-12 suppression could emerge as a promising therapeutic target for several CNS diseases that were discussed in this review.

MMP-12 and TIMP Behavior in Symptomatic and Asymptomatic Critical Carotid Artery Stenosis

OBJECTIVE

The aim of this study was to evaluate the levels of matrix metalloproteinase-12 (MMP-12) and tissue inhibitors of metalloproteinases (TIMP)-1, TIMP-2, TIMP-3, and TIMP-4 in patients with symptomatic and asymptomatic critical carotid artery stenosis (CAS).

METHODS

We enrolled 10 patients affected by symptomatic CAS within 12 hours from onset of stroke (S group) and 30 patients with asymptomatic CAS (CAS group); 31 patients matched for age, sex, and traditional cardiovascular risk factors were used as controls (RF group). Serum levels of MMP-12, TIMP-1, TIMP-2, TIMP-3, and TIMP-4 were assessed by Luminex.

RESULTS

MMP-12 levels were significantly higher both in the S and CAS groups than in the RF group (P < .001). We found a significant decrease of all TIMPs in the CAS group compared with the RF group, whereas a significant increase was observed in the S group compared with the CAS group. A significant increase of TIMP-3 and TIMP-4 levels was observed in the S group compared with all other groups.

CONCLUSION

MMP-12 is related to critical CAS both symptomatic and asymptomatic, being mainly released in the late stage of plaque development. Moreover, we suggest that a specific pattern of matrix degrading enzyme inhibitors arises during the early phases of stroke.

Critical in vivo roles of histamine and histamine receptor signaling in animal models of metabolic syndrome

Histamine, a classic low-molecular-weight amine, is synthesized from L-histidine by histidine decarboxylase (HDC), and histamine-specific receptors (HRs) are essential for its actions. Our serial in vivo studies have uniquely reported that expression of histamine/HRs is variably identified in atherosclerotic lesions, and that HDC-gene knockout mice without histamine/HRs signaling show a marked reduction of atherosclerotic progression. These data have convinced us that histamine plays a pivotal role in the pathogenesis of atherosclerosis. Among four subclasses of HRs, the expression profile of the main receptors (H1/2R) has been shown to be switched from H2R to H1R during monocyte to macrophage differentiation, and H1R is also predominant in smooth muscle and endothelial cells of atheromatous plaque. Using various animal models of H1/2R-gene knockout mice, H1R and H2R were found to reciprocally but critically regulate not only hypercholesterolemia-induced atherosclerosis and injury-induced arteriosclerosis, but also hyperlipidemia-induced nonalcoholic fatty liver disease (NAFLD). Metabolic syndrome manifests obesity, dyslipidemia, insulin resistance, atherosclerosis, and/or NAFLD, i.e. the dysregulation of lipid/bile acid/glucose metabolism. Therefore, although its etiology is complicated and multifactorial, histamine/HRs signaling has a close relationship with the development of metabolic syndrome. We herein review diverse, key in vivo roles of histamine/HR signaling in the pathogenesis of metabolic syndrome.

Novel function of histamine signaling via histamine receptors in cholesterol and bile acid metabolism: Histamine H2 receptor protects against nonalcoholic fatty liver disease

We have reported that the function of histamine and its receptors (HRs) has a close relationship with the development of nonalcoholic fatty liver disease (NAFLD). However, much less is known regarding its pathogenic and molecular mechanism(s), including the early stage of hepatic and intestinal function for lipid and bile acid (BA) metabolism. We used H1R and H2R knockout mice (H1/2R-KO) to clarify those pivotal roles in cholesterol/BA metabolism, in which H1/2R-KO mice were separately fed a short-term 1% cholesterol or cholic acid (CA) diet. [(3) H]Cholesterol absorption study revealed that significantly enhanced accumulation occurred in the jejunum, blood and liver, but not in the feces, of H2R-KO mice, compared to wild-type and H1R-KO mice. Furthermore, four weeks after the high-cholesterol diet, the H2R-KO jejunum but not liver exhibited increased expressions of cholesterol transporters, consistent with higher plasma lipoprotein levels. Five days after CA diet, the H2R-KO mice showed significantly higher expressions of ileal BA-reabsorption and hepatic BA-efflux factors, corresponding to higher serum but lower fecal BA levels. The following long-term CA diets resulted in severe injury to the H2R-KO liver. Histamine/H2R signaling might have a protective role in the initial phase during NAFLD progression, correlated with cholesterol and BA metabolism in the liver/intestine.

Identification of matrix metalloproteinase-12 as a candidate molecule for prevention and treatment of cardiometabolic disease

Obesity is strongly associated with metabolic syndrome, a combination of risk factors that predispose to the development of the cardiometabolic diseases: atherosclerotic cardiovascular disease and type 2 diabetes mellitus. Prevention of metabolic syndrome requires novel interventions to address this health challenge. The objective of this study was the identification of candidate molecules for the prevention and treatment of insulin resistance and atherosclerosis, conditions that underlie type 2 diabetes mellitus and cardiovascular disease, respectively. We used an unbiased bioinformatics approach to identify molecules that are upregulated in both conditions by combining murine and human data from a microarray experiment and meta-analyses. We obtained a pool of eight genes that were upregulated in all the databases analysed. This included well known and novel molecules involved in the pathophysiology of type 2 diabetes mellitus and cardiovascular disease. Notably, matrix metalloproteinase 12 (MMP12) was highly ranked in all analyses and was therefore chosen for further investigation. Analyses of visceral and subcutaneous white adipose tissue from obese compared to lean mice and humans convincingly confirmed the up-regulation of MMP12 in obesity at mRNA, protein and activity levels. In conclusion, using this unbiased approach an interesting pool of candidate molecules was identified, all of which have potential as targets in the treatment and prevention of cardiometabolic diseases.

Omics-based approaches to understand mechanosensitive endothelial biology and atherosclerosis

Atherosclerosis is a multifactorial disease that preferentially occurs in arterial regions exposed to d-flow can be used to indicate disturbed flow or disturbed blood flow. The mechanisms by which d-flow induces atherosclerosis involve changes in the transcriptome, methylome, proteome, and metabolome of multiple vascular cells, especially endothelial cells. Initially, we begin with the pathogenesis of atherosclerosis and the changes that occur at multiple levels owing to d-flow, especially in the endothelium. Also, there are a variety of strategies used for the global profiling of the genome, transcriptome, miRNA-ome, DNA methylome, and metabolome that are important to define the biological and pathophysiological mechanisms of endothelial dysfunction and atherosclerosis. Finally, systems biology can be used to integrate these 'omics' datasets, especially those that derive data based on a single animal model, in order to better understand the pathophysiology of atherosclerosis development in a holistic manner and how this integrative approach could be used to identify novel molecular diagnostics and therapeutic targets to prevent or treat atherosclerosis. WIREs Syst Biol Med 2016, 8:378-401. doi: 10.1002/wsbm.1344 For further resources related to this article, please visit the WIREs website.

The role of endothelial mechanosensitive genes in atherosclerosis and omics approaches

Atherosclerosis is the leading cause of morbidity and mortality in the U.S., and is a multifactorial disease that preferentially occurs in regions of the arterial tree exposed to disturbed blood flow. The detailed mechanisms by which d-flow induces atherosclerosis involve changes in the expression of genes, epigenetic patterns, and metabolites of multiple vascular cells, especially endothelial cells. This review presents an overview of endothelial mechanobiology and its relation to the pathogenesis of atherosclerosis with special reference to the anatomy of the artery and the underlying fluid mechanics, followed by a discussion of a variety of experimental models to study the role of fluid mechanics and atherosclerosis. Various in vitro and in vivo models to study the role of flow in endothelial biology and pathobiology are discussed in this review. Furthermore, strategies used for the global profiling of the genome, transcriptome, miR-nome, DNA methylome, and metabolome, as they are important to define the biological and pathophysiological mechanisms of atherosclerosis. These "omics" approaches, especially those which derive data based on a single animal model, provide unprecedented opportunities to not only better understand the pathophysiology of atherosclerosis development in a holistic and integrative manner, but also to identify novel molecular and diagnostic targets.

Matrix metalloproteinase-12 is an essential mediator of acute and chronic arterial stiffening

Arterial stiffening is a hallmark of aging and risk factor for cardiovascular disease, yet its regulation is poorly understood. Here we use mouse modeling to show that matrix metalloproteinase-12 (MMP12), a potent elastase, is essential for acute and chronic arterial stiffening. MMP12 was induced in arterial smooth muscle cells (SMCs) after acute vascular injury. As determined by genome-wide analysis, the magnitude of its gene induction exceeded that of all other MMPs as well as those of the fibrillar collagens and lysyl oxidases, other common regulators of tissue stiffness. A preferential induction of SMC MMP12, without comparable effect on collagen abundance or structure, was also seen during chronic arterial stiffening with age. In both settings, deletion of MMP12 reduced elastin degradation and blocked arterial stiffening as assessed by atomic force microscopy and immunostaining for stiffness-regulated molecular markers. Isolated MMP12-null SMCs sense extracellular stiffness normally, indicating that MMP12 causes arterial stiffening by remodeling the SMC microenvironment rather than affecting the mechanoresponsiveness of the cells themselves. In human aortic samples, MMP12 levels strongly correlate with markers of SMC stiffness. We conclude that MMP12 causes arterial stiffening in mice and suggest that it functions similarly in humans.

Elevated Plasma Levels of MMP-12 Are Associated With Atherosclerotic Burden and Symptomatic Cardiovascular Disease in Subjects With Type 2 Diabetes

OBJECTIVE

Matrix metalloproteinases (MMPs) degrade extracellular matrix proteins and play important roles in development and tissue repair. They have also been shown to have both protective and pathogenic effects in atherosclerosis, and experimental studies have suggested that MMP-12 contributes to plaque growth and destabilization. The objective of this study was to investigate the associations between circulating MMPs, atherosclerosis burden, and incidence of cardiovascular disease with a particular focus on type 2 diabetes mellitus.

APPROACH AND RESULTS

Plasma levels of MMP-1, -3, -7, -10, and -12 were analyzed by the Proximity Extension Assay technology in 1500 subjects participating in the SUMMIT (surrogate markers for micro- and macrovascular hard end points for innovative diabetes tools) study, 384 incident coronary cases, and 409 matched controls in the Malmö Diet and Cancer study and in 205 carotid endarterectomy patients. Plasma MMP-7 and -12 were higher in subjects with type 2 diabetes mellitus, increased with age and impaired renal function, and was independently associated with prevalent cardiovascular disease, atherosclerotic burden (as assessed by carotid intima-media thickness and ankle-brachial pressure index), arterial stiffness, and plaque inflammation. Baseline MMP-7 and -12 levels were increased in Malmö Diet and Cancer subjects who had a coronary event during follow-up.

CONCLUSIONS

The plasma level of MMP-7 and -12 are elevated in type 2 diabetes mellitus, associated with more severe atherosclerosis and an increased incidence of coronary events. These observations provide clinical support to previous experimental studies, demonstrating a role for these MMPs in plaque development, and suggest that they are potential biomarkers of atherosclerosis burden and cardiovascular disease risk.

Rabbit models for the study of human atherosclerosis: from pathophysiological mechanisms to translational medicine

Laboratory animal models play an important role in the study of human diseases. Using appropriate animals is critical not only for basic research but also for the development of therapeutics and diagnostic tools. Rabbits are widely used for the study of human atherosclerosis. Because rabbits have a unique feature of lipoprotein metabolism (like humans but unlike rodents) and are sensitive to a cholesterol diet, rabbit models have not only provided many insights into the pathogenesis and development of human atherosclerosis but also made a great contribution to translational research. In fact, rabbit was the first animal model used for studying human atherosclerosis, more than a century ago. Currently, three types of rabbit model are commonly used for the study of human atherosclerosis and lipid metabolism: (1) cholesterol-fed rabbits, (2) Watanabe heritable hyperlipidemic rabbits, analogous to human familial hypercholesterolemia due to genetic deficiency of LDL receptors, and (3) genetically modified (transgenic and knock-out) rabbits. Despite their importance, compared with the mouse, the most widely used laboratory animal model nowadays, the use of rabbit models is still limited. In this review, we focus on the features of rabbit lipoprotein metabolism and pathology of atherosclerotic lesions that make it the optimal model for human atherosclerotic disease, especially for the translational medicine. For the sake of clarity, the review is not an attempt to be completely inclusive, but instead attempts to summarize substantial information concisely and provide a guideline for experiments using rabbits.

Marine hydroquinone zonarol prevents inflammation and apoptosis in dextran sulfate sodium-induced mice ulcerative colitis

BACKGROUND AND AIM

We previously identified an anti-inflammatory compound, zonarol, a hydroquinone isolated from the brown algae Dictyopteris undulata as a marine natural product. To ascertain the in vivo functions of zonarol, we examined the pharmacological effects of zonarol administration on dextran sulfate sodium (DSS)-induced inflammation in a mouse model of ulcerative colitis (UC). Our goal is to establish a safe and effective cure for inflammatory bowel disease (IBD) using zonarol.

METHODS AND RESULTS

We subjected Slc:ICR mice to the administration of 2% DSS in drinking water for 14 days. At the same time, 5-aminosalicylic acid (5-ASA) at a dose of 50 mg/kg (positive control) and zonarol at doses of 10 and 20 mg/kg, were given orally once a day. DSS-treated animals developed symptoms similar to those of human UC, such as severe bloody diarrhea, which were evaluated by the disease activity index (DAI). Treatment with 20 mg/kg of zonarol, as well as 5-ASA, significantly suppressed the DAI score, and also led to a reduced colonic ulcer length and/or mucosal inflammatory infiltration by various immune cells, especially macrophages. Zonarol treatment significantly reduced the expression of pro-inflammatory signaling molecules, and prevented the apoptosis of intestinal epithelial cells. Finally, zonarol protected against in vitro lipopolysaccharide (LPS)-induced activation in the RAW264.7 mouse macrophage cell line.

CONCLUSIONS

This is the first report that a marine bioproduct protects against experimental UC via the inhibition of both inflammation and apoptosis, very similar to the standard-of-care sulfasalazine, a well-known prodrug that releases 5-ASA. We believe that the oral administration of zonarol might offer a better treatment for human IBDs than 5-ASA, or may be useful as an alternative/additive therapeutic strategy against UC, without any evidence of side effects.