The vascular biology of atherosclerosis

Serum levels of Matrix Metalloproteinases (MMPs) in patients undergoing endovascular intervention for peripheral arterial disease

OBJECTIVES

Matrix metalloproteinases (MMPs) play a significant role in the development and progression of atherosclerotic vascular disease. The purpose of this study was to measure and document the profile of plasma circulating MMPs in patients with peripheral arterial disease (PAD) undergoing endovascular revascularization.

METHODS

This was a single centre prospective observational study with 80 patients with PAD enrolled. They underwent percutaneous balloon angioplasty and/or angioplasty with stent. Exclusion criteria were acute limb ischemia, active inflammation, wet gangrene, liver disease, end stage renal failure and cancer. Patients that underwent open or hybrid (open and endovascular) approach, were also excluded from the study. Venous blood samples were taken preoperatively, 24 hours and 6 months postoperatively. The values of MMP-2, MMP-3, MMP-7, MMP-9 and their inhibitors (Tissue Inhibitor of metalloproteinases, TIMP), TIMP-1 and TIMP-2 were measured.

RESULTS

The mean age was 67.1 years and 66 of them (82.5%) were male. During the clinical follow up (mean 35.8% months), 12 patients died (16.4%), 15 (20.5%) of them had a major adverse limb event (MALE) and 14 (19.2%) of them had a major adverse cardiovascular event (MACE). There was a statistically significant raise in the values of MMP-2. MMP-3 and MMP-7 at 6 months postoperatively, when compared to the preoperative and 24 hours postoperative values. There was no correlation of MMP and TIMP values with mortality, MALE and MACE events.

CONCLUSIONS

The present single-centre prospective study documented increased circulating levels of MMPs post-operatively in PAD patients undergoing endovascular treatment. Vascular trauma caused by angioplasty, could trigger expression of MMPs and TIMPs, but the absence of any association with clinical complications requires further investigation.

Oxidative Stress, Vascular Endothelium, and the Pathology of Neurodegeneration in Retina

Oxidative stress (OS) is an imbalance between free radicals/ROS and antioxidants, which evokes a biological response and is an important risk factor for diseases, in both the cardiovascular system and central nervous system (CNS). The underlying mechanisms driving pathophysiological complications that arise from OS remain largely unclear. The vascular endothelium is emerging as a primary target of excessive glucocorticoid and catecholamine action. Endothelial dysfunction (ED) has been implicated to play a crucial role in the development of neurodegeneration in the CNS. The retina is known as an extension of the CNS. Stress and endothelium dysfunction are suspected to be interlinked and associated with neurodegenerative diseases in the retina as well. In this narrative review, we explore the role of OS-led ED in the retina by focusing on mechanistic links between OS and ED, ED in the pathophysiology of different retinal neurodegenerative conditions, and how a better understanding of the role of endothelial function could lead to new therapeutic approaches for neurodegenerative diseases in the retina.

High Glucose Activates YAP Signaling to Promote Vascular Inflammation

Background and Aims

The YAP/TAZ signaling is known to regulate endothelial activation and vascular inflammation in response to shear stress. Moreover, YAP/TAZ signaling plays a role in the progression of cancers and renal damage associated with diabetes. However, whether YAP/TAZ signaling is also implicated in diabetes-associated vascular complications is not known.

Methods

The effect of high glucose on YAP/TAZ signaling was firstly evaluated in vitro on endothelial cells cultured under static conditions or subjected to shear stress (either laminar or oscillatory flow). The impact of diabetes on YAP/TAZ signaling was additionally assessed in vivo in db/db mice.

Results

In vitro, we found that YAP was dephosphorylated/activated by high glucose in endothelial cells, thus leading to increased endothelial inflammation and monocyte attachment. Moreover, YAP was further activated when high glucose was combined to laminar flow conditions. YAP was also activated by oscillatory flow conditions but, in contrast, high glucose did not exert any additional effect. Interestingly, inhibition of YAP reduced endothelial inflammation and monocyte attachment. Finally, we found that YAP is also activated in the vascular wall of diabetic mice, where inflammatory markers are also increased.

Conclusion

With the current study we demonstrated that YAP signaling is activated by high glucose in endothelial cells in vitro and in the vasculature of diabetic mice, and we pinpointed YAP as a regulator of high glucose-mediated endothelial inflammation and monocyte attachment. YAP inhibition may represent a potential therapeutic opportunity to improve diabetes-associated vascular complications.

Erythrocytes: Central Actors in Multiple Scenes of Atherosclerosis

The development and progression of atherosclerosis (ATH) involves lipid accumulation, oxidative stress and both vascular and blood cell dysfunction. Erythrocytes, the main circulating cells in the body, exert determinant roles in the gas transport between tissues. Erythrocytes have long been considered as simple bystanders in cardiovascular diseases, including ATH. This review highlights recent knowledge concerning the role of erythrocytes being more than just passive gas carriers, as potent contributors to atherosclerotic plaque progression. Erythrocyte physiology and ATH pathology is first described. Then, a specific chapter delineates the numerous links between erythrocytes and atherogenesis. In particular, we discuss the impact of extravasated erythrocytes in plaque iron homeostasis with potential pathological consequences. Hyperglycaemia is recognised as a significant aggravating contributor to the development of ATH. Then, a special focus is made on glycoxidative modifications of erythrocytes and their role in ATH. This chapter includes recent data proposing glycoxidised erythrocytes as putative contributors to enhanced atherothrombosis in diabetic patients.

Diagnostic and Prognostic Biomarkers for Myocardial Infarction

The incidence of myocardial infarction (MI) increases every year worldwide. Better diagnostic and prognostic biomarkers for clinical applications are the consistent pursuit of MI research. In addition to electrocardiogram, echocardiography, coronary angiography, etc., circulating biomarkers are essential for the diagnosis, prognosis, and treatment effect monitoring of MI patients. In this review, we assessed both strength and weakness of MI circulating biomarkers including: (1) originated from damaged myocardial tissues including current golden standard cardiac troponin, (2) released from non-myocardial tissues due to MI-induced systems reactions, and (3) preexisted in blood circulation before the occurrence of MI event. We also summarized newly reported MI biomarkers. We proposed that the biomarkers preexisting in blood circulation before MI incidents should be emphasized in research and development for MI prevention in near future.

Aging and glycation promote erythrocyte phagocytosis by human endothelial cells: Potential impact in atherothrombosis under diabetic conditions

BACKGROUND AND AIMS

Atherothrombotic plaques of type 2 diabetic (T2D) patients are characterized by an increased neovascularization and intraplaque hemorrhage. The clearance of erythrocytes may be carried out by vascular cells. We explored the potential of human endothelial cells to bind and phagocyte in vitro aged and/or glycated erythrocytes as well as erythrocytes obtained from diabetic patients.

METHODS

Fresh, aged and glycated-aged erythrocytes from healthy volunteers and T2D patients were tested for their binding and phagocytosis capacity as well as the potential functional consequences on endothelial cells (viability, proliferation and wound healing capacity). Immunohistochemistry was also performed in human carotid atherothrombotic samples (from patients with or without T2D).

RESULTS

Aging and glycation of erythrocytes induced phosphatidylserine (PS) exposure and oxidative stress leading to enhanced endothelial cell binding and engulfment. Phagocytosis by endothelial cells was more pronounced with aged and glycated erythrocytes than with fresh ones. Phagocytosis was enhanced with T2D versus healthy erythrocytes. Furthermore, endothelial wound healing potential was significantly blunted after exposure to glycated-aged versus fresh erythrocytes. Finally, we show that interactions between erythrocytes and endothelial cells and their potential phagocytosis may occur in vivo, in atherothrombotic conditions, in neovessels and in the luminal endothelial lining.

CONCLUSIONS

Endothelial cells may play an important role in erythrocyte clearance in an atherothrombotic environment. Under diabetic conditions, erythrocyte glycation favors their engulfment by endothelial cells and may participate in endothelial dysfunction, thereby promoting vulnerable atherothrombotic plaques to rupture.

Lipid-lowering and antiatherogenic effects of Vitex megapotamica (Spreng.) Moldenke in a mice experimental model

ETHNOPHARMACOLOGICAL RELEVANCE

Vitex megapotamica (Spreng.) Moldenke is a deciduous tree, native of South America. Its leaves are traditionally used to treat cardiovascular diseases. This activity is related to the presence of flavonoids, the major compounds of the crude extract.

AIM OF THE STUDY

This study investigated the effects of the oral administration of crude extract and standardized fractions from V. megapotamica leaves on lipid profile and on the formation of atherosclerotic plaque in C57BL/6 LDLr-KO mice treated with high-fat diet (HFD).

MATERIALS AND METHODS

Male C57BL/6 LDLr-KO mice were fed with HFD (cholesterol, 1.25%) for 30 days. They were treated with hydroethanolic extract (500 or 1000mg/kg/day) or fractions (125 or 250mg/kg/day). After 30 days of treatment, it was evaluated the serum lipid profile, atherogenic index, and atherosclerotic plaque.

RESULTS

All doses of the hydroethanolic extract reduced significantly the levels of total cholesterol, triglycerides, LDL-c and the atherogenic index. The n-butanolic fraction also reduced significantly the levels of total cholesterol, triglycerides, LDL-c and the atherogenic index, at all doses, with exception for the triglycerides, which only the lower dose was effective. The residual fraction reduced significantly the levels of total cholesterol, LDL-c and the atherogenic index, at all doses, with exception for the atherogenic index, which only the higher dose was effective. The atherosclerotic plaque formation was impaired only by the lower dose of the hydroethanolic extract.

CONCLUSIONS

Overall, our data suggest that V. megapotamica has potential for the treatment of dyslipidemias.

The Profile of Circulating Matrix Metalloproteinases in Patients Undergoing Lower Limb Endovascular Interventions for Peripheral Arterial Disease

BACKGROUND

Matrix metalloproteinases (MMPs) play a significant role in the development and progression of atherosclerotic vascular disease. We aimed to document the profile of circulating MMPs in peripheral arterial disease (PAD) patients undergoing lower limb endovascular revascularization.

METHODS

A total of 46 patients (37 male; mean age 66 ± 11 years) undergoing elective lower limb percutaneous revascularization (angioplasty/stent) for symptomatic PAD were recruited from 2 vascular centers. Exclusion criteria were: acute limb ischemia, active infection and/or wet gangrene, liver disease, end-stage renal disease, and cancer. Patients having open revascularization or hybrid (open combined with endovascular) procedures were also excluded. Peripheral venous blood samples were taken on admission and 24 hrs after the procedure. Levels of MMP-2, MMP-3, MMP-7, and MMP-9 were measured along with tissue inhibitors of MMPs (TIMPs) 1 and 2.

RESULTS

Compared to baseline values, there was a significant elevation in serum MMP-3 (P = 0.014) and MMP-7 (P = 0.008) levels, whereas serum MMP-9 showed a nonsignificant trend to increase (P = 0.169). On the other hand, no significant alterations were found 24 hrs after angioplasty/stenting with regard to the MMP-2 level and TIMP-1 and 2 levels.

CONCLUSIONS

This study documented the periprocedural profile of circulating MMPs in patients undergoing angioplasty/stenting for PAD. The implications of increased MMP-3 and MMP-7 activity after peripheral endovascular interventions and their potential clinical relevance require further investigation.

Increased levels of legumain in plasma and plaques from patients with carotid atherosclerosis

BACKGROUND AND AIMS

The cysteine protease legumain has been shown to be up-regulated in unstable atherosclerotic plaques. This study aims to further elucidate legumain in atherosclerosis, by examining legumain in plasma and carotid plaques from patients with carotid stenosis. Furthermore, legumain secretion from monocyte-derived macrophages treated with atherogenic lipids during macrophage polarization was studied.

METHODS

Plasma levels of legumain from patients with carotid stenosis (n = 254), healthy controls (n = 91), and secreted from monocyte-derived macrophages were assessed by enzyme-linked-immunosorbent assay. Quantitative PCR and immunoblotting of legumain were performed on isolated plaques and legumain localization was visualized by immunohistochemistry and fluorescence microscopy. Monocyte-derived macrophages polarized to M1 or M2 macrophages were treated with VLDL, oxLDL or cholesterol crystals (CC) and the level of legumain analysed.

RESULTS

Patients with carotid stenosis had significantly higher levels of plasma legumain compared with healthy controls (median 2.0 versus 1.5 ng/ml, respectively; p = 0.003), although there was no correlation between the level of legumain and the degree of stenosis, and legumain was not an independent factor to identify patients with carotid plaques. Moreover, patients with symptoms the last 2 months had higher expressions of mature legumain, cystatin C and E/M, and the macrophage markers CD80 (M1) and CD163 (M2). Legumain co-localized with both M1 and M2 macrophages within plaques, whereas legumain mRNA expression was significantly higher (p < 0.0001) in plaques compared to non-atherosclerotic arteries (controls). Furthermore, in vitro studies showed significantly increased secretion of legumain from pro-inflammatory M1 compared to pro-resolving M2 macrophages (p = 0.014), and particularly in M1 treated with CC. In plaques, legumain was localized to structures resembling foam cells.

CONCLUSIONS

Legumain is increased in both plasma and plaques of patients with carotid stenosis and might be a new and early biomarker of atherosclerosis.

Matrix metalloproteinases and risk stratification in patients undergoing surgical revascularisation for critical limb ischaemia

Critical limb ischaemia (CLI) is the most advanced form of peripheral artery disease (PAD) and it is often associated with foot gangrene, which may lead to major amputation of lower limbs, and also with a higher risk of death due to fatal cardiovascular events. Matrix metalloproteinases (MMPs) seem to be involved in atherosclerosis, PAD and CLI. Aim of this study was to evaluate variations in MMP serum levels in patients affected by CLI, before and after lower limb surgical revascularisation through prosthetic or venous bypass. A total of 29 patients (7 females and 22 males, mean age 73·4 years, range 65-83 years) suffering from CLI and submitted to lower extremity bypass (LEB) in our Institution were recruited. Seven patients (group I) underwent LEB using synthetic polytetrafluoroethylene (PTFE) graft material and 22 patients (group II) underwent LEB using autogenous veins. Moreover, 30 healthy age-sex-matched subjects were also enrolled as controls (group III). We documented significantly higher serum MMPs levels (P < 0·01) in patients with CLI (groups I and II) with respect to control group (group III). Finally, five patients with CLI (17·2%) showed poor outcomes (major amputations or death), and enzyme-linked immunosorbent assay (ELISA) test showed very high levels of MMP-1 and MMP-8. MMP serum levels seem to be able to predict the clinical outcomes of patients with CLI.

[Endothelial function: role, assessment and limits]

For several years, detecting and preventing cardiovascular diseases have become a major issue. Different methods have been developed to evaluate endothelial function. Endothelial dysfunction is one of the first steps leading to atherosclerosis. This review presents an insight into endothelial function, the interests of its assessment and methods for studying endothelial function. To date, the vascular endothelium must be considered as a specific organ with its own functions that contribute to the homeostasis of the cardiovascular system. Endothelial dysfunction typically corresponds to a decrease of nitric oxide NO bioavailability. Biological or physico-chemical methods may be used to assess dysfunction. Biological methods allow measuring NO metabolites and pro-inflammatory and vasoconstrictor mediators released by the endothelium. The physico-chemical methods include intra-coronary injections, plethysmography, flow-mediated dilation (FMD), digital plethysmography and optical techniques using laser (laser Doppler single-point, laser Doppler imager, laser speckle contrast imaging) that can be coupled with provocation tests (iontophoresis, microdialysis, post-ischemic hyperemia, local heating). The principle of each technique and its use in clinical practice are discussed. Studying endothelial dysfunction is a particularly promising field because of new drugs being developed. Nevertheless, assessment methodology still needs further development to enable reliable, non-invasive, reproducible, and inexpensive ways to analyze endothelial dysfunction.

Antioxidative effect and active components from leaves of Lotus ( Nelumbo nucifera )

The DPPH scavenging effect, the inhibition of human low-density lipoprotein oxidation, and antioxidative contents were employed for the activity-guided purification to identify the antioxidant components of lotus leaves (leaves of Nelumbo nucifera Gaertn.). The methanolic extract of lotus leaves (LLM) was separated into ethyl acetate (LLME), n-butanol (LLMB), and water (LLMW) fractions. LLME and LLMB exhibited greater capacity to scavenge DPPH radical, delayed LDL oxidation, and had higher antioxidative contents than LLMW. Seven flavonoids were isolated from both fractions by column chromatography. On the basis of 1D- and 2D-NMR experiments and MS data analyses, these compounds were identified as catechin (1), quercetin (2), quercetin-3-O-glucopyranoside (3), quercetin-3-O-glucuronide (4), quercetin-3-O-galactopyranoside (5), kaempferol-3-O-glucopyranoside (6), and myricetin-3-O-glucopyranoside (7). Quercetin and its glycosides (compounds 2-5) exerted potent inhibition of LDL oxidation, whereas myricetin-3-O-glucopyranoside (7) showed stronger DPPH scavenging activity. These results indicate that the antioxidant capacity of lotus leaves is partially relevant to its flavonoids.

High molecular weight adiponectin correlates positively with myeloperoxidase in patients with type 2 diabetes mellitus

Adiponectin (APN) is present in human plasma as a low molecular weight (LMW), a middle molecular weight (MMW) and a high molecular weight form (HMW). As a support to determine properties such as anti-atherogenic or atherogenic effects, recent clinical studies suppose to determine the ratio of each APN multimer to total APN but not the absolute plasma concentration of APN. In the present study, the correlation of APN and its multimers with myeloperoxidase (MPO), an enzyme with pro-inflammatory properties, was examined in patients with type 2 diabetes mellitus. MPO and APN serum levels were assessed in 49 patients with type 2 diabetes mellitus at the beginning and at the end of an anti-diabetic treatment. After treatment a significant increase in the ratio of HMW to total APN (from 0.43+/-0.16 to 0.59+/-0.14, p<0.05) was found. Before treatment, HMW-APN was correlated positively with MPO (r=0.314, p<0.05). Moreover, a positive correlation was observed between the increased HMW ratio and MPO during treatment (r=0.304, p<0.05). HMW-APN correlates positively with MPO in patients with type 2 diabetes. Therefore, HMW-APN may exert possible pro-inflammatory effects in type 2 diabetes.

In utero programming of adult vascular function in transgenic mice lacking low-density lipoprotein receptor

OBJECTIVE

The objective of this study was to examine the role of maternal hypercholesterolemia in fetal programming of adult vascular function using transgenic mice lacking the low-density lipoprotein receptor (LDLR).

STUDY DESIGN

Homozygous LDLR knockout mice (B6.129S7-Ldlr(tm1Her)/J, LDLR(-/-KO)) and their wild-type controls (C57BL/6J, LDLR(+/+WT)) were cross-bred to produce 4 litter groups: LDLR(-/-KO), maternally derived heterozygous (LDLR(+/-Mat)), paternally derived heterozygous (LDLR(+/-Pat)) and LDLR(+/+WT). Female and male offspring were killed at 10-12 weeks of age, and carotid arteries were used for in vitro experiments.

RESULTS

The dose responses to phenylephrine were significantly higher in LDLR(-/-KO) and LDLR(+/-Mat) male offspring. The contractile responses to phenylephrine in female mice were significantly increased only in the LDLR(-/-KO) offspring. Maximal Ca(2+) contraction was higher in LDLR(-/-KO) male and female offspring.

CONCLUSION

Despite being genomically similar, heterozygous offspring that developed in a hypercholesterolemic maternal environment had abnormal vascular responses later in life compared with those that developed in a normal environment.

PKC isozymes in chronic cardiac disease: possible therapeutic targets?

Cardiovascular disease is the leading cause of death in the United States. Therefore, identifying therapeutic targets is a major focus of current research. Protein kinase C (PKC), a family of serine/threonine kinases, has been identified as playing a role in many of the pathologies of heart disease. However, the lack of specific PKC regulators and the ubiquitous expression and normal physiological functions of the 11 PKC isozymes has made drug development a challenge. Here we discuss the validity of therapeutically targeting PKC, an intracellular signaling enzyme. We describe PKC structure, function, and distribution in the healthy and diseased heart, as well as the development of rationally designed isozyme-selective regulators of PKC functions. The review focuses on the roles of specific PKC isozymes in atherosclerosis, fibrosis, and cardiac hypertrophy, and examines principles of pharmacology as they pertain to regulators of signaling cascades associated with these diseases.

Fine-tuning of the prediction of mortality in hemodialysis patients by use of cytokine proteomic determination

BACKGROUND AND OBJECTIVES

Inflammation-induced atherosclerosis and enhanced susceptibility to infection are linked to immune dysfunction and account for an important part of mortality in hemodialysis patients. This 4-yr prospective study aimed to use cytokine proteomic determination for predicting cardiovascular and noncardiovascular mortality in hemodialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Levels of 12 cytokines were measured using a proteomic biochip system in 134 patients who were on stable hemodialysis and compared with a control group of 150 healthy volunteers. Cox proportional hazards regression analysis was used to determine the relationship between cytokine and clinical outcome.

RESULTS

A proinflammatory state characterized by decreased anti-/proinflammatory cytokine ratio was evidenced in hemodialysis patients compared with control subjects. After adjustment for age, gender, smoking, and high-sensitivity C-reactive protein levels, IL-6 and (IL-4+IL-10)/IL-6 ratio were associated with a significant and specific enhanced hazard ratio of cardiovascular mortality (hazard ratio 11.32 [95% confidence interval 2.52 to 50.90; P < 0.01] and hazard ratio 3.14 [95% confidence interval 1.20 to 8.22; P < 0.05], respectively, when comparing the third and first tertiles). It is interesting that (IL-4+IL-6+IL-10)/(IL-2+IFN-gamma) ratio, used as a marker of lymphocytes T helper subsets cytokine secretion, was associated only with noncardiovascular mortality (hazard ratio 4.93; 95% confidence interval 1.03 to 23.65; P < 0.05).

CONCLUSION

Beyond the strong prediction of cardiovascular mortality by IL-6, determination of cytokine ratios can be useful to identify hemodialysis patients with increased noncardiovascular mortality risk.

Prostacyclin synthase gene transfer inhibits neointimal formation by suppressing PPARδ expression

OBJECTIVE

Prostacyclin (PGI(2)) is a potent ligand of peroxisome proliferator-activated receptor delta (PPAR delta) that regulates cell growth and differentiation. The aim of this study was to elucidate how endogenous PGI(2) overexpression affects the expressions of PPAR delta and mitogen-activated protein kinases (MAPKs) in the development of neointimal formation in experimental angioplasty with adenovirus-mediated PGI(2) synthase (Ad-PGIS) gene transfer.

METHODS AND RESULTS

In human aortic smooth muscle cells, protein blotting analysis showed that PGI(2) overproduction decreased the levels of phosphorylated p38 MAPK (P-p38 MAPK) (2.0-fold versus 0.83-fold relative to control). Immunohistochemical analysis in balloon-injured arteries revealed diffuse expression of PPAR delta in the neointima of control vessels, with no expression in uninjured vessels. The level of PPAR delta expression was lower in Ad-PGIS-treated arteries than in control vessels, with the PPAR delta localized in the neointima adjacent to endothelium. Staining of P-p38 MAPK showed a similar pattern to PPAR delta among the three groups. Morphometric analysis at day 14 revealed that Ad-PGIS reduced the intima-to-media ratio by up to 59%.

CONCLUSIONS

Ad-PGIS gene transfer reduced PPAR delta expression and inhibited neointimal formation after balloon injury in accordance with the reduction in the phosphorylation of p38 MAPK.

Interactions between microvascular and macrovascular disease in diabetes: pathophysiology and therapeutic implications

Convention partitions the complications of diabetes into two main subtypes. First are the diabetes-specific microvascular complications of retinopathy, nephropathy and neuropathy; second are the atherothrombotic macrovascular complications that account for the majority of premature deaths. Pathological interactions between microvascular and macrovascular complications, for example, nephropathy and macrovascular disease, are common. Similar mechanisms and shared risk factors drive the development and progression of both small and large vessel disease. This concept has therapeutic implications. Mounting evidence points to the need for multifactorial strategies to prevent vascular complications in subjects with diabetes and/or the metabolic syndrome. We advocate a combined therapeutic approach that addresses small and large vessel disease. Preferential use should be made of drug regimens that (i) maximize vascular protection, (ii) reduce the risk of iatrogenic vascular damage and (iii) minimize the increasing problem of polypharmacy.

Systems biology of macrophages

Cells and tissues function in context. Under a given growth or survival medium they perform tasks, replicate and die. Given a stimulus they respond by invoking myriad biomolecular networks that result in a specified cellular outcome. At any given instant it can be argued that the cell is in a "state" defined by its components--their concentrations and locations, the interactions between components--that are modulated in space and time, and the complex circuitry--that involves a large number of interacting networks and a snapshot of the dynamical processes--such as gene expression, cell cycle, transport of components, etc. At present, we can measure, using high and low throughput methods, several cellular components in a context-dependent manner and obtain a partial picture of cellular networks and dynamical processes. Are these measurements sufficient to answer important biological questions and help reconstruct a systems-level understanding of a mammalian cell? This chapter will address systems biology strategies developed to address this question and demonstrate the power of integration of diverse cellular data for answering interesting biological questions in macrophages. We will use this systems biology approach to address the following questions: (1) How good are macrophage cell lines in addressing phenotypic biology of primary macrophages? (2) How do signals associated with inflammatory molecules regulate gene transcription in macrophages? (3) How can we combine proteomic and other cellular measurements to characterize the repertoire of upstream signaling networks invoked by macrophages? (4) How do designed knockdowns of proteins influence cellular phenotypes?

Imaging and molecular biomarkers of vulnerable atheromatous plaques

Rupture of a vulnerable atherosclerotic plaque is the main cause of acute coronary syndromes, myocardial infarction and death. Identification of biomarkers that accurately predict the risk of plaque rupture may be a means to establish and monitor response to therapeutic intervention. This review focuses on recent advances for the use of circulating molecular biomarkers and imaging modalities to assess atherosclerotic vulnerable plaques in both preclinical models and clinical conditions.

Matrix metalloproteinases in peripheral vascular disease

Matrix metalloproteinases (MMPs) are extracellular matrix-modifying enzymes that are important in many physiologic and pathologic vascular processes. Dysregulation of MMP activity has been associated with common vascular diseases such as atherosclerotic plaque formation, abdominal aortic aneurysms, and critical limb ischemia. For this reason, MMPs have become an important focus for basic science studies and clinical investigations by vascular biology researchers. This article reviews the recent literature, summarizing our current understanding of the role of MMPs in the pathogenesis of various peripheral vascular disease states. In addition, the importance of MMPs in the future diagnosis and treatment of peripheral vascular disease is discussed.

Thiazolidinediones and vascular damage

PURPOSE OF REVIEW

Although the thiazolidinediones were introduced for the treatment of hyperglycemia in type 2 diabetes, it became quickly apparent that these agents modulated many pathways related to vascular physiology and pathophysiology. Given the fact that cardiovascular disease is the leading cause of death in diabetes, it has become important to know whether these agents have vasculoprotective effects and if so whether these are associated with the prevention of cardiovascular disease.

RECENT FINDINGS

The thiazolidinedione class improves endothelial vasomotion, inhibits inflammatory and procoagulant processes and has powerful antiproliferative and antioxidant effects. Experimentally these agents retard atherosclerosis development in predisposed animals. Clinical studies demonstrate that they increase HDL cholesterol and LDL size, and may lower triglyceride levels. They modestly lower blood pressure, reduce microalbuminuria, arterial stiffness and reduce carotid wall thickening. These effects are generally independent of glucose lowering and in many instances have been shown to occur in nondiabetic subjects. A single clinical endpoint intervention trial of add-on pioglitazone treatment in type 2 diabetic patients with cardiovascular disease suggested on secondary analyses that the agent reduced cardiovascular events.

SUMMARY

The weight of the experimental, subclinical and clinical assessments of the effects of these agents supports the contention that they are vasculoprotective. In the final analysis their use in clinical practice to prevent cardiovascular disease will mostly depend on whether clinical trials consistently demonstrate that they reduced cardiovascular events.

Whole grains and CVD risk

There is an increasing body of evidence, including that from prospective population studies and epidemiological observational studies, suggesting a strong inverse relationship between increased consumption of wholegrain foods and reduced risk of CVD. This evidence has translated into specific dietary recommendations in the USA to consume at least three servings of whole grain per d, and has informed the development of specific health claims for wholegrain foods both in the USA and in Europe. Wholegrain foods are rich sources of many nutrients and phytochemicals, including complex carbohydrates, dietary fibre, minerals, vitamins, antioxidants and phyto-oestrogens such as lignans. Many of these components are lost from the grain during processing and although some may be replaced (such as in the mandatory fortification of white flour), this practice ignores the possible synergistic effects of the ‘natural’ constituents. The notion that wholegrain foods are simply a source of dietary fibre has been dispelled, although the additional components that contribute to the health benefits have not been clearly identified. In addition, the mechanisms by which wholegrain foods may have their effect are poorly understood. At present there are few strictly-controlled intervention studies that have confirmed a beneficial effect of increased consumption of wholegrain foods, demonstrated the level of consumption required to elicit a beneficial effect or provided evidence of modes of action. Although wholegrain foods are considered amongst the healthiest food choices available, their consumption falls well below current recommendations, which have been based mainly on epidemiological evidence. Well-controlled intervention studies are needed to provide more detailed mechanistic evidence to support the health claims and findings which can be used to develop effective public health strategies to promote whole-grain consumption.

Localization of lipids in the aortic wall with imaging TOF-SIMS

Time-of-flight secondary-ion-mass-spectrometry (TOF-SIMS) was utilized to address the issue of localization of lipids and inorganic ions in healthy rat aorta and human atherosclerotic plaque. Pieces of rat aorta were high pressure frozen, freeze-fractured and freeze dried. The samples were analyzed by imaging TOF-SIMS equipped with a Bi(1-7)(+)-source. Reference lipid samples were analyzed and compared to data obtained by analysis of the rat aorta samples. Fatty acids, cholesterol, oxysterol and diacylglycerols were detected and localized. A heterogeneous lipid distribution could be shown in the aorta, where the lamellae of the aorta, distinguished by imaging of CN(-), appeared enriched in cholesterol, oxysterol and diacylglycerols, while the smooth muscle tissue, identified by imaging of PO(3), appeared enriched in phosphocholine. Palmitic/palmitoleic acid and stearic/oleic acid appeared to be heterogeneously distributed over the aorta with high concentration areas located especially in the tunica media region of the aorta. Human atherosclerotic plaque showed an irregular cholesterol distribution mainly located in spots in the intima region with elongated diacylglycerol regions located mainly in the media region.

COX-2 and atherosclerosis

Inflammation plays a central role in the development of atherosclerotic disease, from the early phases of lesion formation to plaque disruption, the main underlying cause of acute ischemic syndromes. Arachidonic acid metabolism is implicated in the pathophysiology of ischemic syndromes affecting the coronary or cerebrovascular territory, as demonstrated by biochemical measurements of eicosanoid biosynthesis and the results of inhibitor trials in these settings. In particular, much attention has been focused on the pathway catalyzed by cyclooxygenase (COX), which leads to the generation of a variety of lipid mediators known as prostanoids. Two COX isozymes have been characterized, COX-1 and COX-2, that differ in terms of regulatory mechanisms of expression, tissue distribution, substrate specificity, and preferential coupling to upstream and downstream enzymes. Whereas the role of platelet COX-1 in acute ischemic diseases is established, the role of COX-2 in atherothrombosis remains unclear. In this article, we summarize the findings from our group suggesting a crucial role for COX-2 in modulating atherosclerotic plaque stability or instability, according to the variable expression of upstream and downstream enzymes in the prostanoid biosynthesis.

Are thiazolidinediones good or bad for the heart?

Type 2 diabetes is a global epidemic contributing to significant cardiovascular morbidity and mortality. The high prevalence of cardiovascular disease can largely be attributed to the metabolic syndrome with its multiple cardiovascular risk factors, including central obesity, hypertension, glucose intolerance, chronic inflammation, and dyslipidemia. The peroxisome proliferator-activated receptor-gamma agonists, the thiazolidinediones, may potentially correct the inflammatory disarray, endothelial dysfunction, dyslipidemia, and plaque vulnerability associated with diabetic cardiovascular disease through their effects on insulin resistance and fat metabolism, yet they can also exacerbate congestive heart failure. This review summarizes basic science, animal, and human data on the effects of thiazolidinediones on cardiovascular disease.

Dietary cholesterol and differential monocyte chemoattractant protein-1 gene expression in aorta and liver of apo E-deficient mice

In humans, hypercholesterolemia, steatohepatitis, and risk for arteriosclerosis are associated. Apolipoprotein E-deficient mice, a widely used animal model, show both arteriosclerosis and steatohepatitis in response to high-fat and cholesterol diets. We have found a relationship between these conditions and a higher mRNA aortic and hepatic monocyte chemoattractant protein-1 (mcp-1) gene expression. Both tissues respond in a similar way when dietary cholesterol is provided for a few weeks but differently if the conditions persist for a protracted period of time. After 8 months of treatment, the mcp-1 gene expression in the aorta continues increasing but in the liver decreases. This coincides with a significant increase in hepatic ppar-delta anti-inflammatory gene expression. Apparently, the arterial wall cannot prevent the deleterious effects of higher mcp-1 expression by increasing ppar-delta gene expression and the lesion progress. However, in the liver, the activation of anti-inflammatory genes may reduce the hepatic mcp-1 expression which significantly decreases the inflammatory response. This differential inflammatory gene expression in aorta and liver may support the idea that anti-inflammatory transcription factors are involved in the response to diet and inflammation. Therefore, the use of cholesterol-enriched diets should be carefully considered in the apolipoprotein E-deficient mice because they may trigger different stimuli and seriously hinder the interpretation of possible findings.

Thiazolidinediones

Our knowledge and understanding of the role played by peroxisome proliferator-activated gamma receptors in physiology and pathophysiology has expanded dramatically over the past 5 years. Originally described as having important functions in adipogenesis and glucose homeostasis, their pharmacologic agonists, the thiazolidinediones, were introduced as antihyperglycemic, insulin-sensitizing agents for the management of type 2 diabetes mellitus. However, it was to some degree inevitable that the thiazolidinediones would be rapidly recognized as having vasculoprotective properties beyond glycemic control that might also be beneficial. First, diabetic complications are vascular in nature, the earliest feature of these is endothelial dysfunction. Second, it is being increasingly appreciated that these complications develop through inflammatory and procoagulant pathways in which increased oxidative stress is considered a major etiologic mechanism, and which are closely linked to the presence of insulin resistance, visceral obesity, and hyperglycemia. Early appreciation that the thiazolidinediones have antioxidant, anti-inflammatory, anti-procoagulant, and antiproliferative properties in addition to their insulin-sensitizing, anti-lipotoxic properties created a marriage of investigative pathways that has not only led to a very large body of literature on the pleiotropic effects of thiazolidinediones, but also to the development of new understandings of the connections between insulin resistance, obesity, and hyperglycemia and the onset of vascular disease. Understandably, most of the focus has been directed at the macrovascular complications of diabetes, since these are the major causes of morbidity and mortality in this population. However, there is evidence that these agents may have benefits for the microvascular complications as well, and their potential role for cardiovascular disease prevention in non-diabetic patients with the metabolic syndrome is a logical extension of the work performed in diabetes. The recently reported results of the effects of pioglitazone versus placebo on cardiovascular events in patients with type 2 diabetes support the contention that these agents have vasculoprotective effects.

Aortic function is compromised in a rat model of polycystic ovary syndrome

BACKGROUND

Arterial mechanical parameters are modified in women with polycystic ovary syndrome (PCOS), before and during pregnancy. This study tested the hypothesis that aortic mechanics and endothelial function are modified in the mifepristone-treated rat model of PCOS.

METHODS

Female rats injected daily with mifepristone or vehicle for 7-9 days were assessed by ultrasound to allow estimation of aortic stiffness index and compliance. The influence of acetylcholine (ACh) and sodium nitroprusside (SNP) on dissected phenylephrine-contracted aortic rings was assessed.

RESULTS

Aortic compliance was reduced by 67% in mifepristone-treated rats versus controls (P<0.05), while stiffness index was increased 2.3-fold (P<0.02). ACh-induced dilation was less in aortic rings from mifepristone-treated rats (P=0.022) and was less sensitive to the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) (P<0.001), while SNP-induced dilation was greater (P=0.001).

CONCLUSIONS

Aortic mechanics in vivo and endothelial function in vitro were consistently perturbed in mifepristone-treated rats. Aortic ring behaviour suggested that NO release was depressed or degradation elevated, with a compensatory increase in NO sensitivity and/or activation of a non-NO-mediated relaxation mechanism. The mifepristone-treated rat is a valid model for investigation of the vascular deficits seen in PCOS.

Expression and function of receptors for insulin-like growth factor-I and insulin in human coronary artery smooth muscle cells

AIMS/HYPOTHESIS

Hyperinsulinaemia and insulin resistance, as well as low IGF-I, have been implicated in the pathogenesis of cardiovascular disease. Little is known about direct effects of IGF-I and insulin on human coronary artery smooth muscle cells (HCASMCs). Our aim was to characterise the expression and function of IGF-I receptor (IGF-IR) and insulin receptor (IR) in HCASMCs.

MATERIALS AND METHODS

Cultured HCASMCs were used. mRNA expression was measured by quantitative real-time RT-PCR analysis. Receptor proteins, phosphorylation of beta-subunits and the presence of hybrid IR/IGF-IR were analysed by immunoprecipitation and western blotting. DNA synthesis and glucose metabolism were assessed using [3H]thymidine incorporation and D-[U-14C]glucose accumulation respectively.

RESULTS

The mRNA expression of IGF-IR was approximately eight-fold higher than that of IR in HCASMCs. The presence of IGF-IR and IR could be demonstrated by immunoprecipitation and western blot analysis. Phosphorylation of the IGF-IR beta-subunit was obtained by IGF-I at 10(-10)-10(-8) mol/l and insulin at 10(-8) mol/l. Insulin and IGF-I at 10(-10)-10(-9) mol/l phosphorylated the IR beta-subunit. When immunoprecipitated with monoclonal anti-IR alpha-subunit or IGF-IR alpha-subunit antibodies, we found bands in slightly different positions, suggesting the presence of hybrid IR/IGF-IR. IGF-I at 10(-9)-10(-8) mol/l significantly stimulated [3H]thymidine incorporation and at a concentration of 10(-9)-10(-7) mol/l also D-[U-14C]glucose accumulation in HCASMCs. Insulin at 10(-9)-10(-7) mol/l had no effect on DNA synthesis, but increased glucose accumulation at 10(-7) mol/l.

CONCLUSIONS/INTERPRETATION

Our study provides experimental evidence that IGF-IR and possibly hybrid IR/IGF-IR play a role in HCASMCs.

Coronary event rates in liver transplant recipients reflect the increased prevalence of cardiovascular risk-factors

Increased prevalence of cardiovascular risk-factors in liver transplant recipients compared with pretransplant and standard population data has been acknowledged. The impact of risk-profiles on cardiovascular event rates or death, however, has not yet been established. Here we evaluate the development of risk-factors during a prospective follow-up of 10 years in 302 patients and compare numbers of coronary events with data from the German Prospective Cardiovascular Münster (PROCAM)-Score population. Prevalence of overweight (17% vs. 27%), hypertension (70% vs. 80%), and diabetes (21% vs. 25%) increased from early to late after transplantation, while elevated serum cholesterol (64% vs. 37%) and triglycerides (40% vs. 21%) became less frequent. Cardiovascular risk-profiles favoring tacrolimus over ciclosporin A based immunosuppression early after transplantation converged over time. Increased risk-scores in liver transplant recipients matched with score standardized event rates in the PROCAM population (ratio: 1.11, 95% CI: 0.53-2.03), nine events were predicted for the transplant population and oppose 10 events observed. Thus, indicating a reflection of increased cardiovascular risk-profiles in corresponding numbers of cardiovascular events.

The PPAR-γ activator, Rosiglitazone, inhibits actin polymerisation in monocytes: Involvement of Akt and intracellular calcium

Monocyte hyperactivation as seen in diabetes results in increased cytoskeletal rigidity and reduced cell deformability leading to microchannel occlusions and microvascular complications. The thiazolidinediones (TZDs) are PPAR-gamma agonists that have been reported to exert beneficial non-metabolic effects on the vasculature. This study demonstrates that the TZD, Rosiglitazone, significantly reduces f-MLP-induced actin polymerisation in human monocytic cells (p < 0.05). Two of the key signalling processes known to be involved in the regulation of cytoskeletal remodelling were investigated: PI(3)K-dependent Akt phosphorylation and intracellular calcium concentration [Ca(2+)](i). The PI(3)K inhibitor, Wortmannin, ameliorated f-MLP-induced actin polymerisation (p < 0.05), while the Ca(2+) sequestration inhibitor, thapsigargin, induced actin depolymerisation (p < 0.05), confirming the involvement of both processes in cytoskeletal remodelling. Rosiglitazone significantly reduced f-MLP activation of Akt (p < 0.05), and significantly increased [Ca(2+)](i) in both resting and f-MLP-stimulated cells (p < 0.05). Therefore, Rosiglitazone interacts with signalling events downstream of occupancy of the f-MLP receptor, to modulate cytoskeletal remodelling in a PPAR-gamma-independent manner. To our knowledge, these results are the first to present evidence that a PPAR-gamma agonist can modulate actin remodelling in monocytes, and may therefore be protective against microvascular damage in diabetes.

Attenuation of accumulation of neointimal lipid by pioglitazone in mice genetically deficient in insulin receptor substrate-2 and apolipoprotein E

Rupture of vulnerable atherosclerotic plaques that are characterized by extensive neointimal accumulation of lipid is a cause of acute coronary syndromes. To identify whether insulin resistance alters atherogenesis, we characterized the composition of atherosclerotic lesions in the proximal aortas in mice deficient in apolipoprotein E (ApoE(-/-)) and in ApoE(-/-) mice in which insulin resistance was intensified by a concomitant heterozygous deficiency in insulin receptor substrate type 2 (IRS2(+/-) ApoE(-/-) mice). In addition, we characterized the effect of an insulin sensitizer, pioglitazone, on the atherogenesis in IRS2(+/-) ApoE(-/-) mice. The extent of the aortic intima occupied by lesion was increased in the IRS2(+/-) ApoE(-/-) compared with ApoE(-/-) mice (79 +/- 3% compared with 68 +/- 8%, p<0.05). Treatment with pioglitazone decreased the neointimal content of lipid in 20-week-old mice from 50 +/- 6% to 30 +/- 7%, p=0.005 and decreased the cellularity reflected by the multisection cross-sectional areas of lesions comprising cells in atheroma from 24 +/- 1% to 19 +/- 3%, p=0.018. Accordingly, genetically induced intensification of insulin resistance increases atheroma formation. Furthermore, attenuation of insulin resistance by treatment with pioglitazone decreases accumulation of lipid in the neointima.

Hypoxia inducible factor pathways as targets for functional foods

The etiology of most chronic angiogenic diseases such as rheumatoid arthritis, atherosclerosis, diabetes complications, and cancer includes the presence of pockets of hypoxic cells growing behind aerobic cells and away from blood vessels. Hypoxic cells are the result of uncontrolled growth and insufficient vascularization and have undergone a shift from aerobic to anaerobic metabolism. Cells respond to hypoxia by stimulating the expression of hypoxia inducible factor (HIF), which is critical for survival under hypoxic conditions and in embryogenesis. HIF is a heterodimer consisting of the O2-regulated subunit, HIF-1alpha, and the constitutively expressed aryl hydrocarbon receptor nuclear translocator, HIF-1beta. Under hypoxic conditions, HIF-1alpha is stable, accumulates, and migrates to the nucleus where it binds to HIF-1beta to form the complex (HIF-1alpha + HIF-1beta). Transcription is initiated by the binding of the complex (HIF-1alpha + HIF-1beta) to hypoxia responsive elements (HREs). The complex [(HIF-1alpha + HIF-1beta) + HREs] stimulates the expression of genes involved in angiogenesis, anaerobic metabolism, vascular permeability, and inflammation. Experimental and clinical evidence show that these hypoxic cells are the most aggressive and difficult angiogenic disease cells to treat and are a major reason for antiangiogenic and conventional treatment failure. Hypoxia occurs in early stages of disease development (before metastasis), activates angiogenesis, and stimulates vascular remodeling. HIF-1alpha has also been identified under aerobic conditions in certain types of cancer. This review summarizes the role of hypoxia in some chronic degenerative angiogenic diseases and discusses potential functional foods to target the HIF-1alpha pathways under hypoxic and normoxic conditions. It is reported that dietary quinones, semiquinones, phenolics, vitamins, amino acids, isoprenoids, and vasoactive compounds can down-regulate the HIF-1 pathways and therefore the expression of several proangiogenic factors. Considering the lack of efficiency or the side effects of synthetic antiangiogenic drugs at clinical trials, down-regulation of hypoxia-induced angiogenesis by use of naturally occurring functional foods may provide an effective means of prevention.

Type 2 Diabetes and Chronic Systolic Heart Failure

Diabetes is a chronic progressive endocrinopathy associated with significant macrovascular and microvascular complications as well as cardiomyopathy and heart failure (HF). Diabetes and chronic systolic HF result in similar activation of pathologic neurohormonal pathways. When diabetes and HF coexist, morbidity and mortality significantly increase. This article reviews important clinical issues in the care of patients with diabetes and HF. A review of pertinent pathophysiologic principles is provided, followed by a discussion of the treatment issues related to this population. Treatment issues include vascular disease risk factor modification, HF pharmacotherapy, glycemic management, and control of other common comorbid conditions.

Adiponectin, obesity, and cardiovascular disease

Several adipocyte-secreted factors have been demonstrated to potentially link obesity, insulin resistance, and cardiovascular disease. Among those, adiponectin is an insulin-sensitizing and anti-inflammatory adipokine, concentrations of which are decreased in obesity-associated metabolic and vascular disorders. Recently, two adiponectin receptors (AdipoR) have been isolated and adenosine monophosphate kinase (AMPK), as well as acetyl coenzyme A carboxylase (ACC), appear to be critical downstream mediators for various effects of this adipokine. In addition to beneficial metabolic effects, adiponectin seems to be vasoprotective by interfering with various atherogenic processes. Of clinical interest, thiazolidinediones (TZDs) which are used in the treatment of type 2 diabetes stimulate adiponectin expression and secretion whereas several hormones dysregulated in insulin resistance and obesity downregulate this adipokine. The current knowledge on regulation and function of adiponectin in obesity, insulin resistance, and cardiovascular disease is summarized in this review and its clinical implications are discussed.

Clinical use of thiazolidinediones: recommendations

Type 2 diabetes mellitus is characterized by progressive beta-cell secretory dysfunction against a background of insulin resistance, which is present many years before the onset of hyperglycemia in most patients. Intensive treatment of diabetes reduces the risk of the onset and progression of microvascular complications and may impact the risk of development of macrovascular complications, notably coronary artery disease. Therefore, aggressive treatment with the goal of achieving serum glucose concentrations as close to normal as possible is warranted. Although medical nutritional therapy and exercise remain the cornerstones of therapy for type 2 diabetes, >90% of patients ultimately require pharmacologic therapy, and most need >1 agent to achieve therapeutic objectives. When considering which agent or agents to use to treat type 2 diabetes, one must consider the mechanism of action of the drug, its ability to lower serum glucose concentrations, the durability of effect, and potential adverse effects. In addition, some medications have potential benefits that extend beyond glucose lowering. These include beneficial effects on the adverse metabolic consequences of insulin resistance and possibly beta-cell preservation. Thiazolidinediones should be considered as early as possible in the natural history of type 2 diabetes because of their persistent glucose-lowering effect and their ability to reduce insulin resistance as well as because these agents may preserve beta-cell function and reverse some of the adverse metabolic consequences of insulin resistance.