Towards understanding acute destabilization of vulnerable atherosclerotic plaques

Association between Mycoplasma pneumoniae infection, high‑density lipoprotein metabolism and cardiovascular health (Review)

The association between Mycoplasma pneumoniae (M. pneumoniae) infection, high-density lipoprotein metabolism and cardiovascular disease is an emerging research area. The present review summarizes the basic characteristics of M. pneumoniae infection and its association with high-density lipoprotein and cardiovascular health. M. pneumoniae primarily invades the respiratory tract and damages the cardiovascular system through various mechanisms including adhesion, invasion, secretion of metabolites, production of autoantibodies and stimulation of cytokine production. Additionally, the present review highlights the potential role of high-density lipoprotein for the development of prevention and intervention of M. pneumoniae infection and cardiovascular disease, and provides suggestions for future research directions and clinical practice. It is urgent to explore the specific mechanisms underlying the association between M. pneumoniae infection, high-density lipoprotein metabolism, and cardiovascular disease and analyze the roles of the immune system and inflammatory response.

Vascular imaging of atherosclerosis: Strengths and weaknesses

Atherosclerosis is an inflammatory disease that can lead to several complications such as ischemic heart disease, stroke, and peripheral vascular disease. Therefore, researchers and clinicians rely heavily on the use of imaging modalities to identify, and more recently, quantify the burden of atherosclerosis in the aorta, carotid arteries, coronary arteries, and peripheral vasculature. These imaging techniques vary in invasiveness, cost, resolution, radiation exposure, and presence of artifacts. Consequently, a detailed understanding of the risks and benefits of each technique is crucial prior to their introduction into routine cardiovascular screening. Additionally, recent research in the field of microvascular imaging has proven to be important in the field of atherosclerosis. Using techniques such as contrast-enhanced ultrasound and superb microvascular imaging, researchers have been able to detect blood vessels within a plaque lesion that may contribute to vulnerability and rupture. This paper will review the strengths and weaknesses of the various imaging techniques used to measure atherosclerotic burden. Furthermore, it will discuss the future of advanced imaging modalities as potential biomarkers for atherosclerosis.

Tanshinone IIA inhibits lipopolysaccharide‑induced inflammatory responses through the TLR4/TAK1/NF‑κB signaling pathway in vascular smooth muscle cells

To aim of the present study was to determine whether Tanshinone IIA (Tan IIA) inhibits lipopolysaccharide (LPS)‑induced inflammation in vascular smooth muscle cells (VSMCs) from rats and elucidate the underlying molecular mechanism. VSMCs were primarily cultured and then treated with LPS (1 µg/l) and Tan IIA (25, 50 and 100 µmol/l) for 24 h. Monocyte chemoattractant protein (MCP)‑1, interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α levels were detected by ELISA and reverse transcription‑quantitative polymerase chain reaction. Nitric oxide (NO) production was measured using the Griess reaction. The expression of Toll‑like receptor 4 (TLR4), nuclear factor (NF)‑κB (p65), and inducible NO synthase (iNOS), and the phosphorylation of transforming growth factor‑β‑activated kinase 1 (TAK1) were detected by western blot analysis. Tan IIA inhibited the LPS‑induced expression of MCP‑1, IL‑6, and TNF‑α in a concentration‑dependent manner and inhibited iNOS‑mediated NO production. In addition, Tan IIA suppressed the expression of TLR4, the phosphorylation of TAK1, and the nuclear translocation of NF‑κB (p65). The anti‑TLR4 antibody and TAK1 inhibitor 5Z‑7‑oxozeaenol partially attenuated the LPS‑induced expression of proinflammatory cytokines. In conclusion, Tan IIA inhibits LPS‑induced inflammatory responses in VSMCs in vitro through the partial suppression of the TLR4/TAK1/NF‑κB signaling pathway.

Hepatic lipase inactivation decreases atherosclerosis in insulin resistance by reducing LIGHT/Lymphotoxin β-Receptor pathway

Coexistence of insulin resistance (IR) and metabolic syndrome (MetS) increases the risk of cardiovascular disease (CVD). Genetic studies in diabetes have linked Hepatic Lipase (HL) to an enhanced risk of CVD while others indicate a role of HL in inflammatory cells. Thus, we explored the role of HL on atherosclerosis and inflammation in a mouse model of MetS/IR, (apoE-/-Irs2+/- mice) and in patients with MetS and IR. HL-deficiency in apoE-/-Irs2+/- mice reduced atheroma size, plaque vulnerability, leukocyte infiltration and macrophage proliferation. Compared with apoE-/-Irs2+/-HL+/+ mice, MCP1, TNFa and IL6 plasma levels, pro-inflammatory Ly6Chi monocytes and activated(CD69+)-T lymphocytes were also decreased in apoE-/-Irs2+/-HL-/- mice. The LIGHT (Tumour necrosis factor ligand superfamily member 14, TNFSF14)/ Lymphotoxin β-Receptor(LTβ-R) pathway, which is involved in T-cell and macrophage activation, was diminished in plasma and in apoE-/-Irs2+/-HL-/- mouse atheromas. Treatment of apoE-/-Irs2+/-HL-/- mice with LIGHT increased the number of Ly6Chi-monocytes and lesion size. Acutely LIGHT-treated apoE-/- mice displayed enhanced proliferating Ly6Chi-monocytes and increased activation of the mitogen-activated protein kinase p38, suggesting that LIGHT/LTβ-R axis might promote atherogenesis by increasing proinflammatory monocytes and proliferation. Notably, MetS-IR subjects with increased atherosclerosis displayed up-regulation of the LIGHT/LTβ-R axis, enhanced inflammatory monocytes and augmented HL mRNA expression in circulating leukocytes. Thus, HL-deficiency decreases atherosclerosis in MetS/IR states by reducing inflammation and macrophage proliferation which are partly attributed to reduced LIGHT/LTβ-R pathway. These studies identify the LIGHT/LTβ-R axis as a main pathway in atherosclerosis and suggest that its inactivation might ameliorate inflammation and macrophage proliferation associated with atherosclerosis burden in MetS/IR.

Supplementary Material to this article is available at www.thrombosis-online.com.

Ultrasonographical Features Associated with Progression of Atherosclerosis in Patients with Moderate Internal Carotid Artery Stenosis

Carotid artery stenosis (CAS) is a leading cause of ischemic stroke. Plaque stabilization is a major management approach. Information about the ultrasonographical and clinical features associated with the progression of moderate internal carotid artery (ICA) stenosis (50-69%) could assist with prognostication and risk factor modifications. We evaluated 287 patients with moderate ICA stenosis (50-69%) and subsequently evaluated them at follow-up points at 12, 24, and 36 months. Patients were divided into three groups according to the degree of ICA stenosis: progression (70-99%, n = 48), stable (50-69%, n = 210), and regression (< 50%, n = 29). Responsible plaque thickness (RPT) across groups during follow-up was compared using a repeated measure ANOVA test. An ordinal regression was subsequently applied to identify risk factors for atherosclerosis progression. Male (P = 0.04), hypoechoic plaque (P < 0.01), smoking (P = 0.02), plaque ulceration (P = 0.05), and contralateral severe CAS or occlusions (P = 0.04) on ultrasound was more frequent in the progression group vs. other two groups. The ordinal regression revealed that only hypoechoic plaque (OR, 7.03; 95% CI, 3.34-14.81; P < 0.01) and contralateral ICA severe stenosis or occlusion (OR, 2.86; 95% CI, 1.41-5.80; P < 0.01) were independently associated with stenosis progression, while statin use was inversely associated with stenosis progression (OR, 0.26; 95% CI, 0.13-0.54; P < 0.01). Of note, symptomatic vs. asymptomatic moderate CAS at baseline was not associated with progression. For patients with moderate CAS, hypoechoic plaque, contralateral severe stenosis or occlusion on ultrasonography, and statin use are independently related to stenosis progression. Statin use may delay the progression of carotid stenosis.

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

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

Prelamin A Accumulation Attenuates Rac1 Activity and Increases the Intrinsic Migrational Persistence of Aged Vascular Smooth Muscle Cells

Vascular smooth muscle cell (VSMC) motility is essential during both physiological and pathological vessel remodeling. Although ageing has emerged as a major risk factor in the development of cardiovascular disease, our understanding of the impact of ageing on VSMC motility remains limited. Prelamin A accumulation is known to drive VSMC ageing and we show that presenescent VSMCs, that have accumulated prelamin A, display increased focal adhesion dynamics, augmented migrational velocity/persistence and attenuated Rac1 activity. Importantly, prelamin A accumulation in proliferative VSMCs, induced by depletion of the prelamin A processing enzyme FACE1, recapitulated the focal adhesion, migrational persistence and Rac1 phenotypes observed in presenescent VSMCs. Moreover, lamin A/C-depleted VSMCs also display reduced Rac1 activity, suggesting that prelamin A influences Rac1 activity by interfering with lamin A/C function at the nuclear envelope. Taken together, these data demonstrate that lamin A/C maintains Rac1 activity in VSMCs and prelamin A disrupts lamin A/C function to reduce Rac1 activity and induce migrational persistence during VSMC ageing.

Semi-Automated Curation Allows Causal Network Model Building for the Quantification of Age-Dependent Plaque Progression in ApoE-/- Mouse

The cellular and molecular mechanisms behind the process of atherosclerotic plaque destabilization are complex, and molecular data from aortic plaques are difficult to interpret. Biological network models may overcome these difficulties and precisely quantify the molecular mechanisms impacted during disease progression. The atherosclerosis plaque destabilization biological network model was constructed with the semiautomated curation pipeline, BELIEF. Cellular and molecular mechanisms promoting plaque destabilization or rupture were captured in the network model. Public transcriptomic data sets were used to demonstrate the specificity of the network model and to capture the different mechanisms that were impacted in ApoE^-/- mouse aorta at 6 and 32 weeks. We concluded that network models combined with the network perturbation amplitude algorithm provide a sensitive, quantitative method to follow disease progression at the molecular level. This approach can be used to investigate and quantify molecular mechanisms during plaque progression.

Multimodal optoacoustic and multiphoton microscopy of human carotid atheroma

Carotid artery atherosclerosis is a main cause of stroke. Understanding atherosclerosis biology is critical in the development of targeted prevention and treatment strategies. Consequently, there is demand for advanced tools investigating atheroma pathology. We consider hybrid optoacoustic and multiphoton microscopy for the integrated and complementary interrogation of plaque tissue constituents and their mutual interactions. Herein, we visualize human carotid plaque using a hybrid multimodal imaging system that combines optical resolution optoacoustic (photoacoustic) microscopy, second and third harmonic generation microscopy, and two-photon excitation fluorescence microscopy. Our data suggest more comprehensive insights in the pathophysiology of atheroma formation and destabilization, by enabling congruent visualization of structural and biological features critical for the atherosclerotic process and its acute complications, such as red blood cells and collagen.

Associations between Carotid Artery Plaque Score, Carotid Hemodynamics and Coronary Heart Disease

Background: The carotid artery plaque score (PS) is an independent predictor of Coronary Heart Disease (CHD). This study aims to evaluate the combination of PS and carotid hemodynamics to predict CHD. Methods: A total of 476 patients who underwent carotid ultrasonography and coronary angiography were divided into two groups depending on the presence of CHD. PS, carotid intima-media thickness, and carotid blood flow were measured. Receiver operating characteristic curve analysis was performed to establish the best prediction model for CHD presence. Results: Age, sex, carotid intima-media thickness of internal carotid artery and carotid bifurcation, PS, peak systolic velocity (PSA) of right internal carotid artery (RICA), and most resistance index data were significantly related with the presence of CHD. The area under the curve for a collective model, which included factors of the PS, carotid hemodynamics and age, was significantly higher than the other model. Age, PS, and PSA of RICA were significant contributors for predicting CHD presence. Conclusions: The model of PS and PSA of RICA has greater predictive value for CHD than PS alone. Adding age to PS and PSA of RICA further improves predictive value over PS alone.

Strokes and TIAs during and after carotid artery Doppler: cause or coincidence?

The aim of the present study was to explore the prevalence of acute cerebrovascular symptoms temporally related to carotid Doppler examination (DEx), in order to increase the awareness and recording of such events and to discuss possible mechanisms. All adult patients who complained of acute onset neurologic symptoms during or shortly after a carotid DEx, between 01/2003 and 12/2011 in the University Hospital of Lausanne were prospectively collected. We identified four consecutive patients with acute onset neurologic symptoms during or shortly after a carotid DEx among approximately 13,500 patients who underwent carotid DEx in our facility during the nine-year period (0.015% of all examined carotids). Clinical data, imaging reports and CTA (CT angiography) or/and ultrasound images are presented for each patient. Ischemic cerebrovascular events during or immediately after cervical Doppler could be due to chance or to several physical factors. They should be promptly recognized by Doppler personnel and properly treated, but do not put into question the overwhelming benefits of Doppler in cerebrovascular patients.

Endovascular shear strain elastography for the detection and characterization of the severity of atherosclerotic plaques: in vitro validation and in vivo evaluation

This work explores the potential of shear strain elastograms to identify vulnerable atherosclerotic plaques. The Lagrangian speckle model estimator (LSME) elasticity imaging method was further developed to estimate shear strain elasticity (SSE). Three polyvinyl alcohol cryogel vessel phantoms were imaged with an intravascular ultrasound (IVUS) scanner. The estimated SSE maps were validated against finite-element results. Atherosclerosis was induced in carotid arteries of eight Sinclair mini-pigs using a combination of surgical techniques, diabetes and a high-fat diet. IVUS images were acquired in vivo in 14 plaques before euthanasia and histology. All plaques were characterized by high magnitudes in SSE maps that correlated with American Heart Association atherosclerosis stage classifications (r = 0.97, p < 0.001): the worse the plaque condition the higher was the absolute value of SSE, i.e. |SSE| (e.g., mean |SSE| was 3.70 ± 0.40% in Type V plaques, whereas it was reduced to 0.11 ± 0.01% in normal walls). This study indicates the feasibility of using SSE to highlight atherosclerotic plaque vulnerability characteristics.

Framingham cardiovascular risk in patients with obesity and periodontitis

BACKGROUND

Obesity is a chronic inflammatory condition that has been associated to a risk factor for the development of periodontitis and cardiovascular disease; however, the relationship still needs to be clarified. The objective of this study was to evaluate the cardiovascular risk in obese patients with chronic periodontitis.

MATERIALS AND METHODS

A total of 87 obese patients were evaluated for anthropometric data (body mass index [BMI], waist circumference, body fat), systolic blood pressure (SBP) and diastolic blood pressure (DBP), cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL), triglycerides, glycemia and periodontal parameters (visible plaque index (VPI), gingival bleeding index (GBI), bleeding on probing (BOP), periodontal probing depth (PPD) and clinical attachment level (CAL)).

RESULTS

PATIENTS WERE DIVIDED INTO TWO GROUPS ACCORDING TO THE PERIODONTAL CHARACTERISTICS FOUND: Group O-PD: Obese patients with chronic periodontitis (n = 45), 22 men and 23 women; and Group O-sPD: Obese patients without chronic periodontitis (n = 42), 17 men and 25 women. Patients had a BMI mean of 35.2 (±5.1) kg/m(2) . Group O-PD showed a similarity between the genders regarding age, SBP, DBP, cholesterol, HDL, GBI, VPI, PPD ≥4 mm and CAL ≥4 mm. O-PD women showed greater glycemia level and smoking occurrence, but O-PD men presented a 13% - risk over of developing coronary artery disease in 10 years than O-PD women, 9% - risk over than O-sPD men and 15% - risk over than O-sPD women, by the Framingham Score.

CONCLUSIONS

It was concluded that obesity and periodontal disease are cardiovascular risk factors and that the two associated inflammatory conditions potentially increases the risk for heart diseases.

Nuclear receptor mediated mechanisms of macrophage cholesterol metabolism

Macrophages comprise a family of multi-faceted phagocytic effector cells that differentiate "in situ" from circulating monocytes to exert various functions including clearance of foreign pathogens as well as debris derived from host cells. Macrophages also possess the ability to engulf and metabolize lipids and this way connect lipid metabolism and inflammation. The molecular link between these processes is provided by certain members of the nuclear receptor family. For instance, peroxisome proliferator activated receptors (PPAR) and liver X receptors (LXR) are able to sense the dynamically changing lipid environment and translate it to gene expression changes in order to modulate the cellular phenotype. Atherosclerosis embodies both sides of this coin: it is a disease in which macrophages with altered cholesterol metabolism keep the arteries in a chronically inflamed state. A large body of publications has accumulated during the past few decades describing the role of nuclear receptors in the regulation of macrophage cholesterol homeostasis, their contribution to the formation of atherosclerotic plaques and their crosstalk with inflammatory pathways. This review will summarize the most recent findings from this field narrowly focusing on the contribution of various nuclear receptors to macrophage cholesterol metabolism.

Intrinsic directionality of migrating vascular smooth muscle cells is regulated by NAD(+) biosynthesis

Cell migration is central to tissue repair and regeneration but must proceed with precise directionality to be productive. Directional migration requires external cues but also depends on the extent to which cells can inherently maintain their direction of crawling. We report that the NAD(+) biosynthetic enzyme, nicotinamide phosphoribosyltransferase (Nampt/PBEF/visfatin), mediates directionally persistent migration of vascular smooth muscle cells (SMCs). Time-lapse microscopy of human SMCs subjected to Nampt inhibition revealed chaotic motility whereas SMCs transduced with the Nampt gene displayed highly linear migration paths. Ordered motility conferred by Nampt was associated with downsizing of the lamellipodium, reduced lamellipodium wandering around the cell perimeter, and increased lamellipodial protrusion rates. These protrusive and polarity-stabilizing effects also enabled spreading SMCs to undergo bipolar elongation to an extent not typically observed in vitro. Nampt was found to localize to lamellipodia and fluorescence recovery of Nampt-eGFP after photobleaching revealed microtubule-dependent transport of Nampt to the leading edge. In addition, Nampt was found to associate with, and activate, Cdc42, and Nampt-driven directional persistence and lamellipodium anchoring required Cdc42. We conclude that high-fidelity SMC motility is coordinated by a Nampt-Cdc42 axis that yields protrusive but small and anchored lamellipodia. This novel, NAD(+)-synthesis-dependent control over motility may be crucial for efficient repair and regeneration of the vasculature, and possibly other tissues.

Symptomatic and asymptomatic carotid artery plaque

Carotid atherosclerotic plaques represent both stable and unstable atheromatous lesions. Atherosclerotic plaques that are prone to rupture owing to their intrinsic composition such as a large lipid core, thin fibrous cap and intraplaque hemorrhage are associated with subsequent thromboembolic ischemic events. At least 15-20% of all ischemic strokes are attributable to carotid artery atherosclerosis. Characterization of plaques may enhance the understanding of natural history and ultimately the treatment of atherosclerotic disease. MRI of carotid plaque and embolic signals during transcranial Doppler have identified features beyond luminal stenosis that are predictive of future transient ischemic attacks and stroke. The value of specific therapies to prevent stroke in symptomatic and asymptomatic patients with severe carotid artery stenosis are the subject of current research and analysis of recently published clinical trials that are discussed in this article.

[Study of the intronic polymorphism of the angiotensin 1 converting enzyme among coronary Tunisians]

BACKGROUND

The acute coronary syndromes (ACS) are classified among the major causes of mortality in the industrialized countries. The increased angiotensin I converting enzyme (ACEI) activity related to a genetic polymorphism constitutes a hereditary predisposition to these syndromes.

AIM

Evaluate the ACEI activity in Tunisian patients with coronary heart disease, and investigate the association between this activity and an intronic deletion of 287 pb on the intron 16 of the ACEI gene.

PATIENTS AND METHODS

Seventy-two coronary patients and 34 control subjects are recruited for our study. ACEI activity was measured by kinetic method. The intronic deletion was identified by PCR technique.

RESULTS

An increased activity of ACEI was observed in patients compared with control subjects (84.38 ± 33.83 UI/L vs 59.06 ± 18.2 UI/L, P=10(-5)). The molecular study showed a raised relative frequency of D/D genotype (51.4%) among patients, whereas among the witnesses, I/I genotype prevailed (62%). D/D genotype is always associated with highest ACEI activity for the patients and the control subjects.

CONCLUSION

The molecular studies and the biochemical investigations of the various parameters of cardiovascular risk (including the ACEI) direct towards a better treatment.

Candidate biomarkers for the detection of coronary plaque destabilization and rupture

Identification of high-risk patients presenting with chest pain remains challenging. The use of a single biomarker or a panel of biomarkers to detect occult plaque destabilization or rupture without frank infarction would allow for appropriate triage of such patients. Current data suggest that plaque vulnerability is determined by the relationship between forces that increase the size of the lipid core and destabilize the overlying thin fibrous cap. A variety of interrelated pathways are imputed to play important roles in this process of plaque evolution, destabilization, and rupture. These mechanisms include increased systemic and local inflammation, increased oxidative stress, matrix metalloproteinase modulation, and hemodynamic variables related to altered shear stress. Select candidate biomarkers that either reflect or influence these underlying processes and may ultimately have clinical application are highlighted in this review, which focuses on emerging biomarkers to define and predict the risks associated with the complex nature of vulnerable plaque biology.

Hemorrhage and large lipid-rich necrotic cores are independently associated with thin or ruptured fibrous caps: an in vivo 3T MRI study

OBJECTIVE

Histological studies suggest associations between hemorrhage and large lipid-rich/necrotic cores with thin or ruptured fibrous caps in advanced atherosclerosis. We investigated these associations in carotid arteries with mild to severe stenosis by in vivo 3T MRI.

METHODS AND RESULTS

Seventy-seven patients with >or=50% carotid stenosis in at least one side by duplex ultrasound underwent bilateral multi-contrast carotid MRI scans. Measurements for wall and lipid-rich/necrotic core sizes, presence of hemorrhage, and fibrous cap status (classified as intact thick, intact thin or ruptured) were recorded. Arteries with poor image quality, occlusion, or no detectable lipid-rich/necrotic core were excluded. For the 798 MRI slices included, multivariate ordinal regression analysis demonstrated larger %lipid-rich/necrotic core (odds ratio for 10% increase, 1.49; P=0.02) and presence of hemorrhage (odds ratio, 5.91; P<0.001) were independently associated with a worse (intact thin or ruptured) stage of fibrous cap status. For artery-based multivariate analysis, a larger maximum %lipid-rich/necrotic core and presence of hemorrhage independently associated with worse fibrous cap status (P<0.001, for both). No hemorrhage was detected in arteries with thick fibrous caps.

CONCLUSIONS

Hemorrhage and larger %lipid-rich/necrotic core were independently associated with a thin or ruptured fibrous cap status at an early to advanced stage of carotid atherosclerosis.

CD4+ CD28 null T cells in coronary artery disease: when helpers become killers

The crucial role of T cells in atherosclerosis and coronary artery disease (CAD) has been highlighted by recent observations. Helper CD4(+) T cells can both aggravate or attenuate the atherogenic process and the development of CAD. CD4(+)CD28(null) T cells are an unusual subset of helper cells which expand and have deleterious effects in CAD. In this review, we discuss the current issues on the generation of CD4(+)CD28(null) T cells and focus on their phenotypic and functional characteristics relevant to the development of cardiovascular events. The possible effects of the present day therapies for CAD on the CD4(+)CD28(null) T cells are also explored. Targeting the CD4(+)CD28(null) T cell subset in CAD could provide novel therapeutic strategies to prevent acute life-threatening coronary events.

Differential display fingerprints: new approach to characterize smooth muscle cells and human coronary atherectomy tissues

AIM OF THE STUDY

Smooth muscle cells build up the normal media and stabilize atherosclerotic lesions whereas an inflammatory component is determinant for unstable angina. Smooth muscle cells, currently identified by alpha-actin, present a phenotypic heterogeneity and alpha-actin can be reduced in pathology. We tried to characterize vascular cell types, particularly smooth muscle cells, and coronary atherosclerotic tissues, by random genes expression fingerprints.

MATERIALS AND METHODS

Expression fingerprints (cDNA electrophoresis) were performed by differential display reverse transcriptase-polymerase chain reaction. Variability of fingerprints was studied for a panel of arterial muscle cell phenotypes and comparisons were made with fingerprints from other cell types (endothelial cells and macrophages). The technique was then applied to human coronary atherectomy samples compared to control human arterial (mammary) smooth muscle.

RESULTS

Arterial smooth muscle cells fingerprints were overall similar whatever the cell phenotype (native contractile, dedifferentiated in culture or epithelioid). Moreover, with two primer pairs, the muscular fingerprints markedly differed from the endothelial and the monocytic fingerprints. Application of differential display to coronary atherectomy samples was feasible. Interestingly, the pathological tissues exhibited either smooth muscle-like or smooth muscle-divergent fingerprints.

CONCLUSIONS

Smooth muscle cells and inflammatory cells exhibited distinct differential display fingerprint patterns. Thus, a simple expression profile of arbitrary genes provides a molecular bar code tool (pattern signature) useful to characterize vascular cell cultures or tissues. The present work proposes a method to analyze coronary atherectomy samples which estimates their whole quality, muscular versus non muscular (inflammatory), this is of interest for clinical research.

Shear stress-induced changes in atherosclerotic plaque composition are modulated by chemokines

We previously found that low shear stress (LSS) induces atherosclerotic plaques in mice with increased lipid and matrix metalloproteinase content and decreased vascular smooth muscle and collagen content. Here, we evaluated the role of chemokines in this process, using an extravascular device inducing regions of LSS, high shear stress, and oscillatory shear stress (OSS) in the carotid artery. One week of shear stress alterations induced expression of IFN-gamma-inducible protein-10 (IP-10) exclusively in the LSS region, whereas monocyte chemoattractant protein-1 (MCP-1) and the mouse homolog of growth-regulated oncogene alpha (GRO-alpha) were equally upregulated in both LSS and OSS regions. After 3 weeks, GRO-alpha and IP-10 were specifically upregulated in LSS regions. After 9 weeks, lesions with thinner fibrous caps and larger necrotic cores were found in the LSS region compared with the OSS region. Equal levels of MCP-1 expression were observed in both regions, while expression of fractalkine was found in the LSS region only. Blockage of fractalkine inhibited plaque growth and resulted in striking differences in plaque composition in the LSS region. We conclude that LSS or OSS triggers expression of chemokines involved in atherogenesis. Fractalkine upregulation is critically important for the composition of LSS-induced atherosclerotic lesions.

Computed tomography calcium quantification as a measure of atherosclerotic plaque morphology and stability

OBJECTIVES

We examined the relationship between computed tomography (CT)-quantified calcium and histopathologic atherosclerotic plaque morphology and rupture.

MATERIALS AND METHODS

Seven aortae were harvested from autopsy cases. All were scanned, ex vivo, on a 16-slice CT scanner and CT calcium scores (CTCS) were calculated using a Siemens Calcium Scoring package. The aorta segments were physically cross sectioned at 3-mm intervals corresponding to CT reconstructions. Two pathologists evaluated the cross sections for histology calcium score (HCS), plaque fibrous cap disruption, overlying thrombus, internal hemorrhage, size, lipid content, and inflammation. CT and histology data were subsequently paired using predetermined quadrant and slice conventions.

RESULTS

Three hundred forty-nine aorta cross sections yielded 41 atherosclerotic plaques. Eleven plaques demonstrated plaque disruption and thrombosis and all contained calcium. CTCS was not significantly different between atherosclerotic plaques with and without evidence of disruption/thrombosis (F[1,30] = 1.525, P = 0.227). CT was 100% sensitive for nodular calcification, but only 56% (5 of 9 plaques) sensitive for non-nodular calcification. There was no significant relationship between CTCS and intraplaque hemorrhage, lipid content, inflammation, and plaque size (P = 0.179, P = 0.230, P = 0.314, and P = 0.054). There was significant correlation between CTCS and HCS (Pearson coefficient = 0.535; P < 0.01).

CONCLUSIONS

Calcium quantity does not appear to predict plaque morphology or likelihood of rupture. CT has lower sensitivity for non-nodular compared with nodular calcification.

What are the most useful and trustworthy noninvasive anatomic markers of existing vascular disease?

Cardiovascular disease is the leading cause of mortality and morbidity in developed countries. Evidence challenges the notion that the severity of lesions on angiography is a predictor of future cardiac events. With the recognition that subclinical coronary artery stenoses are responsible for myocardial infarcts and sudden death, it may be important to identify patients with plaque characteristics that may place them at increased risk. Intravascular ultrasound, though invasive, remains the current imaging gold standard. Computed tomography, cardiac magnetic resonance, and single-photon emission CT positron emission tomography are evolving and promising modalities. Functional studies reflecting plaque temperature and molecular imaging reflecting plaque constituents are being developed. We review the pathology of the vulnerable atherosclerotic plaque and recent innovations in imaging modalities to assess plaque complication risk.

Review article: The role of statins in reducing perioperative cardiac risk: physiologic and clinical perspectives

PURPOSE

To review the pathobiology and clinical implications of coronary vulnerable atherosclerotic plaques (VAPs), to discuss the role of statin therapy in VAP stabilization, and the potential benefits of perioperative statin therapy (PST) in reducing perioperative risk of acute coronary syndromes (ACSs).

SOURCE

MEDLINE search using "perioperative", "cardiac morbidity", "atherosclerosis", "vulnerable plaque", "statins" and combinations of these terms as keywords. The reference lists of relevant articles were further reviewed to identify additional citations.

PRINCIPAL FINDINGS

The nonstenotic, yet rupture-prone VAP causes most myocardial infarctions (MIs) and other ACSs, both in the nonsurgical and surgical patients. Large clinical trials in both primary and secondary prevention and in patients with ACSs have demonstrated that statin therapy will reduce cardiovascular morbidity and mortality across a broad spectrum of patient subgroups. These trials also suggest, and laboratory investigations establish, that statins possess favourable vascular effects independent of cholesterol reduction. Statins appear to interfere specifically with the pathophysiologic mechanisms implicated in atherothrombotic disease. Statins reduce vascular inflammation, improve endothelial function, stabilize VAPs, and reduce platelet aggregability and thrombus formation. Recent studies have shown that PST is associated with a reduced incidence of perioperative and long-term cardiovascular complications in high-risk patients. Combined therapy with statins and ss-blockers is a conceptually valid strategy targeting critical steps in the pathogenesis of an ACS.

CONCLUSION

Emerging evidence for the efficacy and safety of PST is promising, especially when combined with ss-blocker therapy in patients at highest risk. Confirmation of this early evidence awaits the results of ongoing and future prospective randomized controlled trials.

Lysophosphatidylcholine induces inflammatory activation of human coronary artery smooth muscle cells

Lysophosphatidylcholine (LPC) is the major bioactive lipid component of oxidized LDL, thought to be responsible for many of the inflammatory effects of oxidized LDL described in both inflammatory and endothelial cells. Inflammation-induced transformation of vascular smooth muscle cells from a contractile phenotype to a proliferative/secretory phenotype is a hallmark of the vascular remodeling that is characteristic of atherogenesis; however, the role of LPC in this process has not been fully described. The present study tested the hypothesis that LPC is an inflammatory stimulus in coronary artery smooth muscle cells (CASMCs). In cultured human CASMCs, LPC stimulated time- and concentration-dependent release of arachidonic acid that was sensitive to phospholipase A2 and C inhibition. LPC stimulated the release of arachidonic acid metabolites leukotriene-B4 and 6-keto-prostaglandin F1alpha, within the same time course. LPC was also found to stimulate basic fibroblast growth factor release as well as stimulating the release of the cytokines GM-CSF, IL-6, and IL-8. Optimal stimulation of these signals was obtained via palmitic acid-substituted LPC species. Stimulation of arachidonic acid, inflammatory cytokines and growth factor release, implies that LPC might play a multifactorial role in the progression of atherosclerosis, by affecting inflammatory processes.

MMP-9 Microsatellite Polymorphism and Susceptibility to Carotid Arteries Atherosclerosis

Objective— The aims of this study were to compare a microsatellite polymorphism (PM) of matrix metalloproteinase (MMP)-9 in patients with carotid atherosclerosis and control population, and to assess the relationship between this PM and plaque structure.

Methods and Results— One hundred fifty patients referring to vascular diagnostic centers for suspected carotid atherosclerosis (at ultrasound examination: 110 positive, 40 negative) and controls (n=110) have been genotyped for MMP-9 PM. After controlling for risk factors, allelic and genotype frequencies were significantly different among the groups, with significant prevalence of long microsatellites in patients with carotid atherosclerosis. Long microsatellites (settled as 22 to 27 repeats) were associated with carotid atherosclerosis (odds ratio [OR], 5.2; 95% confidence interval [CI], 2.9 to 9.2), compared with controls; an independent case control study on patients with coronary atherosclerosis confirmed such result. Binary logistic regression showed that hypertension, long microsatellites in MMP-9 PM and smoking habits were variables accounting for the difference between ultrasound-positive patients and controls. Long microsatellites were also associated to plaques with thin fibrous cap and echolucent core (OR, 13.1; 95% CI, 1.6 to 100). These alleles were slightly more represented in female patients (χ 2 test=0.019; OR, 2.7; 95% CI, 1.2 to 6) but not associated with other risk factors. Plasma MMP-9 levels were related neither to MMP-9 PM nor to plaque type, and were related to gender and extension of atherosclerosis in carotid arteries.

Conclusions— The number of repeats (≥22 CA) in the microsatellite of MMP-9 promoter, but not MMP-9 plasma levels, is associated to carotid atherosclerosis and particularly to plaques with a thin fibrous cap.

Macrophage retinoblastoma deficiency leads to enhanced atherosclerosis development in ApoE-deficient mice

The cellular composition of an atherosclerotic lesion is determined by cell infiltration, proliferation, and apoptosis. The tumor suppressor gene retinoblastoma (Rb) has been shown to regulate both cell proliferation and cell death in many cell types. To study the role of macrophage Rb in the development of atherosclerosis, we used apoE-deficient mice with a macrophage-restricted deletion of Rb (Rb(del) mice) and control littermates (Rb(fl) mice). After 12 wk feeding a cholesterol-rich diet, the Rb(del) mice showed a 51% increase in atherosclerotic lesion area with a 39% increase in the relative number of advanced lesions. Atherosclerotic lesions showed a 13% decrease in relative macrophage area and a 46% increase in relative smooth muscle cell area, reflecting the more advanced state of the lesions. The increase in atherosclerosis was independent of in vitro macrophage modified lipoprotein uptake or cytokine production. Whereas macrophage-restricted Rb deletion did not affect lesional macrophage apoptosis, a clear 2.6-fold increase in lesional macrophage proliferation was observed. These studies demonstrate that macrophage Rb is a suppressing factor in the progression of atherosclerosis by reducing macrophage proliferation.

Determinants of plaque instability in atherosclerotic vascular disease

BACKGROUND

Despite numerous advances in the understanding of the pathogenesis of atherosclerosis, the factors that determine atheromatous plaque instability remain unclear. The prediction of the vulnerability of a plaque to rupture and subsequent thrombosis would be useful in guiding development of diagnostic and therapeutic approaches.

METHODS

Aortas with areas of gross atherosclerosis were obtained from seven autopsy cases. These were then serially sectioned at 3-mm intervals, analyzed histologically, and scored as to plaque size, calcification, lipid content, intraplaque hemorrhage, inflammation, plaque disruption, and plaque thrombosis. Bivariate correlations and binary multivariate regression analyses were performed using SPSS software.

RESULTS

Plaque instability was highly correlated with intraplaque hemorrhage, lipid content, and plaque size. Weaker but statistically significant correlations were found with inflammation and calcification. However, in multivariate regression analyses, only plaque size, intraplaque hemorrhage, and lipid content, independent predictors of plaque instability, were significant.

CONCLUSIONS

Atheromatous plaques may be rendered unstable by increases in size, increased intra- and extracellular lipid accumulation, and intraplaque hemorrhage. Based on these results, diagnostic modalities that detect plaque size, plaque hemorrhage, and/or lipid content are most likely to be useful in predicting unstable plaques.

Participation of macrophages in atherosclerotic lesion morphology in LDLr-/- mice

Lystbeige (beige) mice crossed with LDL receptor-deficient (LDLr-/-) mice had a distinct atherosclerotic lesion morphology that was not observed in LDLr-/- mice. This morphology is often associated with a stable plaque phenotype. We hypothesized that macrophage expression of the beige mutation accounted for this distinct morphology. Cultured bone marrow-derived macrophages from LDLr-/- and beige,LDLr-/- mice were compared for their ability to accumulate cholesterol, efflux cholesterol, migrate in response to chemotactic stimuli through Matrigel-coated membranes, and express matrix metalloproteinase 9 (MMP9). No differences in cholesterol metabolism were identified. Beige,LDLr-/- macrophage invasion in vitro appeared to be less than LDLr-/- macrophage invasion but did not achieve significance. Nevertheless, tumor necrosis factor-alpha-induced MMP9 expression, secretion, and enzymatic activity of beige,LDLr-/- macrophages were all significantly decreased compared with those of LDLr-/- macrophages (P < 0.05). For in vivo analyses of macrophage function, bone marrow transplantation (BMT) studies were performed. LDLr-/- mice and beige,LDLr-/- mice were irradiated and reconstituted with wild-type or beige bone marrow from mice expressing green fluorescent protein (GFP). Identification of GFP cells provided for direct identification of donor-derived cells within lesions. Only expression of the beige mutation in the BMT recipients altered the macrophage location and collagen content of the lesions. These results suggested that impaired macrophage function by itself did not account for the stable lesion morphology of beige,LDLr-/- double-mutant mice.