Molecular mechanisms of plaque instability

Prognostic value of non-obstructive coronary artery disease based on coronary computed tomography angiography in a long-term follow-up and multicenter study

This study investigates the long-term prognostic significance of non-obstructive coronary artery disease (CAD) in predicting the risk of all-cause death in a multicenter study. Three hospitals in Wuhan participated in this retrospective, observational, multicenter study of 7320 patients with suspected of having CAD and who underwent clinical coronary computed tomography angiography (CTA) from June 2011 to December 2015. According to coronary CTA, the extent of CAD was categorized as non-obstructive, obstructive, and no CAD. The primary outcome was all-cause mortality. A total of 611 patients experienced all-cause mortality with a median duration of 8.0 years (7.2-8.9). The annualized mortality rate was 0.50 (95% CI: 0.43-0.58), 1.31 (95% CI: 1.16-1.47), and 2.18 (95% CI: 1.93-2.46) for the no CAD, non-obstructive CAD, and obstructive CAD, respectively. There was a significant association between the classification and the increased cumulative events, as shown by the Kaplan-Meier survival curve (P < 0.001). The multivariate Cox model showed that the hazard ratios (HR) for predicting all-cause mortality from 1.42 (95% CI: 1.15-1.75, P = 0.001) in non-obstructive CAD to 1.87 (95% CI: 1.50-2.33, P < 0.001) in obstructive CAD compared with no CAD. At 8-year follow-up, patients with non-obstructive CAD detected by coronary CTA had a 1.42-fold increased risk of all-cause mortality compared to patients without evidence of CAD. Thus, these findings suggest that non-obstructive CAD is clinically significant and that further investigation of interventions to improve the prognosis of these patients is warranted.

Impact of Diabetes Duration on Major Adverse Cardiac Events in Patients with Non-Obstructive Coronary Artery Disease

Background/Objectives: Diabetes mellitus is a substantial risk factor for coronary artery disease (CAD). Diabetes duration is linked to clinical outcomes in CAD patients. This study aimed to investigate the impact of diabetes duration on major adverse cardiovascular and cerebrovascular outcomes, as well as all-cause mortality, in Korean patients diagnosed with non-obstructive CAD. Methods: This non-randomized, retrospective, single-center study was based on the medical records of 4287 patients who underwent coronary angiography from 1 January 2010 to 31 December 2015. Of these patients, 517 with non-obstructive CAD-defined as 20-49% coronary artery stenosis-were identified and categorized into three groups based on diabetes duration: those without diabetes, those with diabetes for <10 years, and those with diabetes for ≥10 years. Results: Over a median follow-up period of 60 months, the risk of major adverse cardiovascular and cerebrovascular events (MACCEs) increased nearly fourfold in patients who had non-obstructive CAD and diabetes for ≥10 years compared to those without diabetes, even after adjusting for covariates (adjusted hazard ratio [HR] 4.61, 95% confidence interval [CI] 2.04-10.40, p < 0.001). The risks of cardiovascular death and non-fatal stroke were also significantly higher in patients who had diabetes for ≥10 years compared to non-diabetic patients (adjusted HR 12.42, 95% CI 2.33-66.22, p = 0.003, adjusted HR 4.97, 95% CI 1.88-13.19, p = 0.001, respectively). Conclusions: Patients with non-obstructive CAD and a longer duration of diabetes exhibited a higher risk of MACCEs. Diabetes duration could be an important factor in predicting mortality in patients with non-obstructive CAD.

Cross-Sectional Analyses to Assess the Clinical Safety and Effectiveness of Bisoprolol in Patients With Non-obstructive Coronary Artery Disease Who Underwent Percutaneous Coronary Intervention: A Post-hoc Analysis

INTRODUCTION

Elevated central aortic pressure, cardiac output and peripheral vascular resistance contribute to high morbidity in relation to end organ dysfunction in obstructive and non-obstructive coronary artery disease (NOCAD) cases despite revascularization. Bisoprolol preempts further progression of left ventricular dysfunction in such cases due to anti-ischemic and anti-hypertensive effects, further extending its evaluation in local Indian settings.

METHODS

Post-hoc analyses of NOCAD patients with epicardial stenosis (N=378, 30 to 70% stenosis) from cross-sectional analyses conducted across eighty centers in India. Local ethics approval for study documents and endpoints for analyses was conducted in adherence to ICH-Good Clinical Practice (GCP) and Declaration of Helsinki guidelines. Descriptive and analytical statistics were performed using SPSS Version 29.0.1.0 (IBM Corp., Armonk, NY, USA).

RESULTS

Per-protocol analyses of NOCAD (N=378) showed (mean) age: 58.63 years (286 males and 92 females); mean weight: 75.49kg; mean BMI: 27.78kg/m2 and baseline left ventricular ejection fraction (LVEF): (46.85%). Prevalent risk factors include hypertension (100%), dyslipidemia (51.85%), smoking (24.07%), type 2 diabetes (59.52%), stroke (20.37%) and peripheral artery disease (4.76%). In overall population (n=800), bisoprolol (2.5 to 5mg/day) showed significant reduction in resting heart rate (RHR) (14bpm), and LVEF (5.08%). Similarly, in NOCAD cases significant changes in RHR (12.14bpm), and LVEF (4.68%) were noted at 24 weeks. Adverse events included chest congestion (6.61%), asthenia (5.03%), hypotension (4.76%), muscular weakness (3.70%), and bradycardia (1.85%) that were mild to moderate with none requiring treatment withdrawal.

CONCLUSION

Bisoprolol remains a clinically feasible option in Indian patients with NOCAD cases following percutaneous coronary intervention (PCI) as it reduces RHR and improves LVEF. Despite high rates of cardiovascular risk factors like age, type 2 diabetes and diffuse polyvascular disease, the drug was well-tolerated, with fewer adverse events. These results support the use of bisoprolol in managing NOCAD in Indian patients, highlighting its potential therapeutic uses to prevent further cardiac dysfunction.

Inflammatory crosstalk impairs phagocytic receptors and aggravates atherosclerosis in clonal hematopoiesis in mice

Clonal hematopoiesis (CH) increases inflammasome-linked atherosclerosis, but the mechanisms by which CH mutant cells transmit inflammatory signals to nonmutant cells are largely unknown. To address this question, we transplanted 1.5% Jak2V617F (Jak2VF) bone marrow (BM) cells with 98.5% WT BM cells into hyperlipidemic Ldlr-/- mice. Low-allele-burden (LAB) mice showed accelerated atherosclerosis with increased features of plaque instability, decreased levels of the macrophage phagocytic receptors c-Mer tyrosine kinase (MERTK) and triggering receptor expressed on myeloid cells 2 (TREM2), and increased neutrophil extracellular traps (NETs). These changes were reversed when Jak2VF BM was transplanted with Il1r1-/- BM. LAB mice with noncleavable MERTK in WT BM showed improvements in necrotic core and fibrous cap formation and reduced NETs. An agonistic TREM2 antibody (4D9) markedly increased fibrous caps in both control and LAB mice, eliminating the difference between the groups. Mechanistically, 4D9 increased TREM2+PDGFB+ macrophages and PDGF receptor-α+ fibroblast-like cells in the cap region. TREM2 and PDGFB mRNA levels were positively correlated in human carotid plaques and coexpressed in macrophages. In summary, low frequencies of Jak2VF mutations promoted atherosclerosis via IL-1 signaling from Jak2VF to WT macrophages and neutrophils, promoting cleavage of phagocytic receptors and features of plaque instability. Therapeutic approaches that stabilize MERTK or TREM2 could promote plaque stabilization, especially in CH- and inflammasome-driven atherosclerosis.

The role of fibromodulin in inflammatory responses and diseases associated with inflammation

Inflammation is an immune response that the host organism eliminates threats from foreign objects or endogenous signals. It plays a key role in the progression, prognosis as well as therapy of diseases. Chronic inflammatory diseases have been regarded as the main cause of death worldwide at present, which greatly affect a vast number of individuals, producing economic and social burdens. Thus, developing drugs targeting inflammation has become necessary and attractive in the world. Currently, accumulating evidence suggests that small leucine-rich proteoglycans (SLRPs) exhibit essential roles in various inflammatory responses by acting as an anti-inflammatory or pro-inflammatory role in different scenarios of diseases. Of particular interest was a well-studied member, termed fibromodulin (FMOD), which has been largely explored in the role of inflammatory responses in inflammatory-related diseases. In this review, particular focus is given to the role of FMOD in inflammatory response including the relationship of FMOD with the complement system and immune cells, as well as the role of FMOD in the diseases associated with inflammation, such as skin wounding healing, osteoarthritis (OA), tendinopathy, atherosclerosis, and heart failure (HF). By conducting this review, we intend to gain insight into the role of FMOD in inflammation, which may open the way for the development of new anti-inflammation drugs in the scenarios of different inflammatory-related diseases.

Assessment of indices of conjunctival microvascular function in patients with and without obstructive coronary artery disease

BACKGROUND

Atherosclerotic heart disease often remains asymptomatic until presentation with a major adverse cardiovascular event. Primary preventive therapies improve outcomes, but conventional screening often misattributes risk. Vascular imaging can be utilised to detect atherosclerosis, but often involves ionising radiation. The conjunctiva is a readily accessible vascular network allowing non-invasive hemodynamic evaluation.

AIM

To compare conjunctival microcirculatory function in patients with and without obstructive coronary artery disease.

METHODS

We compared the conjunctival microcirculation of myocardial infarction patients (MI-cohort) to controls with no obstructive coronary artery disease (NO-CAD cohort). Conjunctival imaging was performed using a smartphone and slit-lamp biomicroscope combination. Microvascular indices of axial (V_a) and cross-sectional (V_cs) velocity; blood flow rate (Q); and wall shear rate (WSR) were compared in all conjunctival vessels between 5 and 45 μm in diameter.

RESULTS

A total of 127 patients were recruited (66 MI vs 61 NO-CAD) and 3602 conjunctival vessels analysed (2414 MI vs 1188 NO-CAD). Mean V_a, V_cs and Q were significantly lower in the MI vs NO-CAD cohort (V_a 0.50 ± 0.17 mm/s vs 0.55 ± 0.15 mm/s, p < 0.001; V_cs 0.35 ± 0.12 mm/s vs 0.38 ± 0.10 mm/s, p < 0.001; Q 154 ± 116 pl/s vs 198 ± 130 pl/s, p < 0.001). To correct for differences in mean vessel diameter, WSR was compared in 10-36 μm vessels (3268/3602 vessels) and was lower in the MI-cohort (134 ± 64 s^-1 vs 140 ± 63 s^-1, p = 0.002).

CONCLUSIONS

Conjunctival microcirculatory alterations can be observed in patients with obstructive coronary artery disease. The conjunctival microvasculature merits further evaluation in cardiovascular risk screening.

Status of biomarkers for the identification of stable or vulnerable plaques in atherosclerosis

Atherosclerosis is a systemic inflammation of the arteries characterized by atherosclerotic plaque due to the accumulation of lipids, inflammatory cells, apoptotic cells, calcium and extracellular matrix (ECM) proteins. Stable plaques present a chronic inflammatory infiltration, whereas vulnerable plaques present an 'active' inflammation involved in the thinning of the fibrous cap that predisposes to plaque rupture. Several complex biological cellular processes lead plaques to evolve from stable to vulnerable predisposing them to rupture and thrombosis. In this review, we analyze some emerging circulating biomarkers related to inflammation, ECM and lipid infiltration, angiogenesis, metalloproteinases and microRNA (miRNA), as possible diagnostic and prognostic indicators of plaque vulnerability.

Treatment of Psoriasis With Biologic Therapy Is Associated With Improvement of Coronary Artery Plaque Lipid-Rich Necrotic Core: Results From a Prospective, Observational Study

BACKGROUND

Lipid-rich necrotic core (LRNC), a high-risk coronary plaque feature assessed by coronary computed tomography angiography, is associated with increased risk of future cardiovascular events in patients with subclinical, nonobstructive coronary artery disease. Psoriasis is a chronic inflammatory condition that is associated with increased prevalence of high-risk coronary plaque and risk of cardiovascular events. This study characterized LRNC in psoriasis and how LRNC modulates in response to biologic therapy.

METHODS

Consecutive biologic naïve psoriasis patients (n=209) underwent coronary computed tomography angiography at baseline and 1-year to assess changes in LRNC using a novel histopathologically validated software (vascuCAP Elucid Bioimaging, Boston, MA) before and after biologic therapy over 1 year.

RESULTS

Study participants were middle-aged, predominantly male with similar cardiometabolic and psoriasis status between treatment groups. In all participants at baseline, LRNC was associated with Framingham risk score (β [standardized β]=0.12 [95% CI, 0.00-0.15]; P=0.045), and psoriasis severity (β=0.13 [95% CI, 0.01-0.26]; P=0.029). At 1-year, participants receiving biologic therapy had a reduction in LRNC (mm²; 3.12 [1.99-4.66] versus 2.97 [1.84-4.35]; P=0.028), while those who did not receive biologic therapy over 1 year demonstrated no significant change with nominally higher LRNC (3.12 [1.82-4.60] versus 3.34 [2.04-4.74]; P=0.06). The change in LRNC was significant compared with that of the nonbiologic treated group (ΔLRNC, -0.22 mm² versus 0.14 mm², P=0.004) and remained significant after adjusting for cardiovascular risk factors and psoriasis severity (β=-0.09 [95% CI, -0.01 to -0.18]; P=0.033).

CONCLUSIONS

LRNC was associated with psoriasis severity and cardiovascular risk factors in psoriasis. Additionally, there was favorable modification of LRNC in those on biologic therapy. This study provides evidence of potential reduction in LRNC with treatment of systemic inflammation. Larger, longer follow-up prospective studies should be conducted to understand how changes in LRNC may translate into a reduction in future cardiovascular events in psoriasis.

Signalling, Metabolic Pathways and Iron Homeostasis in Endothelial Cells in Health, Atherosclerosis and Alzheimer's Disease

Endothelial cells drive the formation of new blood vessels in physiological and pathological contexts such as embryonic development, wound healing, cancer and ocular diseases. Once formed, all vessels of the vasculature system present an endothelial monolayer (the endothelium), lining the luminal wall of the vessels, that regulates gas and nutrient exchange between the circulating blood and tissues, contributing to maintaining tissue and vascular homeostasis. To perform their functions, endothelial cells integrate signalling pathways promoted by growth factors, cytokines, extracellular matrix components and signals from mechanosensory complexes sensing the blood flow. New evidence shows that endothelial cells rely on specific metabolic pathways for distinct cellular functions and that the integration of signalling and metabolic pathways regulates endothelial-dependent processes such as angiogenesis and vascular homeostasis. In this review, we provide an overview of endothelial functions and the recent advances in understanding the role of endothelial signalling and metabolism in physiological processes such as angiogenesis and vascular homeostasis and vascular diseases. Also, we focus on the signalling pathways promoted by the transmembrane protein Neuropilin-1 (NRP1) in endothelial cells, its recently discovered role in regulating mitochondrial function and iron homeostasis and the role of mitochondrial dysfunction and iron in atherosclerosis and neurodegenerative diseases.

Parallel Murine and Human Plaque Proteomics Reveals Pathways of Plaque Rupture

RATIONALE

Plaque rupture is the proximate cause of most myocardial infarctions and many strokes. However, the molecular mechanisms that precipitate plaque rupture are unknown.

OBJECTIVE

By applying proteomic and bioinformatic approaches in mouse models of protease-induced plaque rupture and in ruptured human plaques, we aimed to illuminate biochemical pathways through which proteolysis causes plaque rupture and identify substrates that are cleaved in ruptured plaques.

METHODS AND RESULTS

We performed shotgun proteomics analyses of aortas of transgenic mice with macrophage-specific overexpression of urokinase (SR-uPA^+/0 mice) and of SR-uPA^+/0 bone marrow transplant recipients, and we used bioinformatic tools to evaluate protein abundance and functional category enrichment in these aortas. In parallel, we performed shotgun proteomics and bioinformatics studies on extracts of ruptured and stable areas of freshly harvested human carotid plaques. We also applied a separate protein-analysis method (protein topography and migration analysis platform) to attempt to identify substrates and proteolytic fragments in mouse and human plaque extracts. Approximately 10% of extracted aortic proteins were reproducibly altered in SR-uPA^+/0 aortas. Proteases, inflammatory signaling molecules, as well as proteins involved with cell adhesion, the cytoskeleton, and apoptosis, were increased. ECM (Extracellular matrix) proteins, including basement-membrane proteins, were decreased. Approximately 40% of proteins were altered in ruptured versus stable areas of human carotid plaques, including many of the same functional categories that were altered in SR-uPA^+/0 aortas. Collagens were minimally altered in SR-uPA^+/0 aortas and ruptured human plaques; however, several basement-membrane proteins were reduced in both SR-uPA^+/0 aortas and ruptured human plaques. Protein topography and migration analysis platform did not detect robust increases in proteolytic fragments of ECM proteins in either setting.

CONCLUSIONS

Parallel studies of SR-uPA^+/0 mouse aortas and human plaques identify mechanisms that connect proteolysis with plaque rupture, including inflammation, basement-membrane protein loss, and apoptosis. Basement-membrane protein loss is a prominent feature of ruptured human plaques, suggesting a major role for basement-membrane proteins in maintaining plaque stability.

Animal models of human atherosclerosis: current progress

Atherosclerosis retains the leading position among the causes of global morbidity and mortality worldwide, especially in the industrialized countries. Despite the continuing efforts to investigate disease pathogenesis and find the potential points of effective therapeutic intervention, our understanding of atherosclerosis mechanisms remains limited. This is partly due to the multifactorial nature of the disease pathogenesis, when several factors so different as altered lipid metabolism, increased oxidative stress, and chronic inflammation act together leading to the formation and progression of atherosclerotic plaques. Adequate animal models are currently indispensable for studying these processes and searching for novel therapies. Animal models based on rodents, such as mice and rats, and rabbits represent important tools for studying atherosclerosis. Currently, genetically modified animals allow for previously unknown possibilities in modelling the disease and its most relevant aspects. In this review, we describe the recent progress made in creating such models and discuss the most important findings obtained with them to date.

Exploring the role of extracellular matrix proteins to develop biomarkers of plaque vulnerability and outcome

Cardiovascular disease (CVD) is the most common cause of death in industrialized countries. One underlying cause is atherosclerosis, which is a systemic disease characterized by plaques of retained lipids, inflammatory cells, apoptotic cells, calcium and extracellular matrix (ECM) proteins in the arterial wall. The biologic composition of an atherosclerotic plaque determines whether the plaque is more or less vulnerable, that is prone to rupture or erosion. Here, the ECM and tissue repair play an important role in plaque stability, vulnerability and progression. This review will focus on ECM remodelling in atherosclerotic plaques, with focus on how ECM biomarkers might predict plaque vulnerability and outcome.

The Diabetes Mellitus-Atherosclerosis Connection: The Role of Lipid and Glucose Metabolism and Chronic Inflammation

Diabetes mellitus comprises a group of carbohydrate metabolism disorders that share a common main feature of chronic hyperglycemia that results from defects of insulin secretion, insulin action, or both. Insulin is an important anabolic hormone, and its deficiency leads to various metabolic abnormalities in proteins, lipids, and carbohydrates. Atherosclerosis develops as a result of a multistep process ultimately leading to cardiovascular disease associated with high morbidity and mortality. Alteration of lipid metabolism is a risk factor and characteristic feature of atherosclerosis. Possible links between the two chronic disorders depending on altered metabolic pathways have been investigated in numerous studies. It was shown that both types of diabetes mellitus can actually induce atherosclerosis development or further accelerate its progression. Elevated glucose level, dyslipidemia, and other metabolic alterations that accompany the disease development are tightly involved in the pathogenesis of atherosclerosis at almost every step of the atherogenic process. Chronic inflammation is currently considered as one of the key factors in atherosclerosis development and is present starting from the earliest stages of the pathology initiation. It may also be regarded as one of the possible links between atherosclerosis and diabetes mellitus. However, the data available so far do not allow for developing effective anti-inflammatory therapeutic strategies that would stop atherosclerotic lesion progression or induce lesion reduction. In this review, we summarize the main aspects of diabetes mellitus that possibly affect the atherogenic process and its relationship with chronic inflammation. We also discuss the established pathophysiological features that link atherosclerosis and diabetes mellitus, such as oxidative stress, altered protein kinase signaling, and the role of certain miRNA and epigenetic modifications.

Oxidative Stress and Inflammation, Key Targets of Atherosclerotic Plaque Progression and Vulnerability: Potential Impact of Physical Activity

Atherosclerosis, a complex cardiovascular disease, is a leading cause of mortality and morbidity worldwide. Oxidative stress and inflammation are both involved in the development of atherosclerotic plaque as they increase the biological processes associated with this pathology, such as endothelial dysfunction and macrophage recruitment and adhesion. Atherosclerotic plaque rupture leading to major ischemic events is the result of vulnerable plaque progression, which is a result of the detrimental effect of oxidative stress and inflammation on risk factors for atherosclerotic plaque rupture, such as intraplaque hemorrhage, neovascularization, and fibrous cap thickness. Thus, both are key targets for primary and secondary interventions. It is well recognized that chronic physical activity attenuates oxidative stress in healthy subjects via the improvement of antioxidant enzyme capacities and inflammation via the enhancement of anti-inflammatory molecules. Moreover, it was recently shown that chronic physical activity could decrease oxidative stress and inflammation in atherosclerotic patients. The aim of this review is to summarize the role of oxidative stress and inflammation in atherosclerosis and the results of therapeutic interventions targeting them in both preclinical and clinical studies. The effects of chronic physical activity on these two key processes are then reviewed in vulnerable atherosclerotic plaques in both coronary and carotid arteries.

Inflammation in atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease is a leading cause of death and morbidity globally. Over the past several years, arterial inflammation has been implicated in the pathophysiology of athero-thrombosis, substantially confirming what pathologist Rudolf Virchow had observed in the 19th century. Lipid lowering, lifestyle changes, and modification of other risk factors have reduced cardiovascular complications of athero-thrombosis, but a substantial residual risk remains. In view of the pathogenic role of inflammation in athero-thrombosis, directly targeting inflammation has emerged as an additional potential therapeutic option; and some early promising results have been suggested by the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS), in which canakinumab, a fully human monoclonal antibody targeting the pro-inflammatory and pro-atherogenic cytokine interleukin 1 beta, was shown to reduce cardiovascular events.

Toll-like receptors in the functional orientation of cardiac progenitor cells

Cardiac progenitor cells (CPCs) have the potential to differentiate into several cell lineages with the ability to restore in cardiac tissue. Multipotency and self-renewal activity are the crucial characteristics of CPCs. Also, CPCs have promising therapeutic roles in cardiac diseases such as valvular disease, thrombosis, atherosclerosis, congestive heart failure, and cardiac remodeling. Toll-like receptors (TLRs), as the main part of the innate immunity, have a key role in the development and differentiation of immune cells. Some reports are found regarding the effect of TLRs in the maturation of stem cells. This article tried to find the potential role of TLRs in the dynamics of CPCs. By showing possible crosstalk between the TLR signaling pathways and CPCs dynamics, we could achieve a better conception related to TLRs in the regeneration of cardiac tissue.

Inflammation, infection and atherosclerosis

Atherosclerotic cardiovascular disease is a leading cause of death in much of the world. Adoption of a healthy lifestyle and cholesterol lowering are the key measures used to prevent major complications of atherosclerosis. Recent data have identified a critical role for inflammation mediated through activation of both innate and adaptive immune pathways in the pathophysiology of atherosclerosis opening up opportunities for development of anti-inflammatory interventions that could supplement risk factor modification and lipid lowering as an approach to further reducing the burden of atherosclerotic cardiovascular disease.

The maturation of a 'neural-hematopoietic' inflammatory axis in cardiovascular disease

PURPOSE OF REVIEW

Atherogenesis is the result of a complex interplay between lipids and innate immune cells, which are descendants of upstream progenitors residing in hematopoietic organs. In this review, we will discuss recent advances in the connection between hematopoiesis and atherogenesis.

RECENT FINDINGS

The relevance of a neural-hematopoietic axis was recently supported by the demonstration of a correlation between metabolic activity in the amygdala and the bone marrow. During follow-up, both amygdalar and bone marrow activities also predicted cardiovascular risk in patients, lending further support to a connection between neural stress and cardiovascular events mediated via increased hematopoietic activity.In parallel, functional changes in hematopoietic stem cells may also convey cardiovascular risk. In experimental models, knock-out of the ten-eleven translocation 2 (TET2) gene leading to monocyte-macrophage hyperresponsiveness, was associated with accelerated atherogenesis in murine experiments. In humans, whole-exome sequencing reporting on the 'clonal hematopoiesis of indeterminate potential' gene substantiated a two-fold elevated risk for developing coronary heart disease compared with noncarriers.

SUMMARY

Recent studies support the relevance of a 'neural-hematopoietic' inflammatory axis and clonal hematopoiesis as drivers of atherogenesis in humans. These data warrant further studies addressing the role of novel 'hematopoietic' targets for the treatment of patients with increased cardiovascular risk.

A Whole Blood Molecular Signature for Acute Myocardial Infarction

Chest pain is a leading reason patients seek medical evaluation. While assays to detect myocyte death are used to diagnose a heart attack (acute myocardial infarction, AMI), there is no biomarker to indicate an impending cardiac event. Transcriptional patterns present in circulating endothelial cells (CEC) may provide a window into the plaque rupture process and identify a proximal biomarker for AMI. Thus, we aimed to identify a transcriptomic signature of AMI present in whole blood, but derived from CECs. Candidate genes indicative of AMI were nominated from microarray of enriched CEC samples, and then verified for detectability and predictive potential via qPCR in whole blood. This signature was validated in an independent cohort. Our findings suggest that a whole blood CEC-derived molecular signature identifies patients with AMI and sets the framework to potentially identify the earlier stages of an impending cardiac event when used in concert with clinical history and other diagnostics where conventional biomarkers indicative of myonecrosis remain undetected.

Relation between serum levels of chemotaxis-related factors and the presence of coronary artery calcification as expression of subclinical atherosclerosis

BACKGROUND

Atherosclerotic plaque formation is characterized by recruitment of monocytes/macrophages, which contributes to its calcification by releasing pro-osteogenic cytokines. Chemotaxis-related proteins, including netrin-1, gremlin-1 and macrophage inflammatory protein-1β (MIP-1β), regulate immune cell migration. However, their relation with the presence of subclinical atherosclerosis, assessed by measures of coronary artery calcifications (CAC) in patients without known coronary artery disease (CAD), remains unclear.

AIMS

To examine whether these chemoattractant-related proteins are associated with the presence of CAC in patients without known CAD.

METHODS

A retrospective case-control observational study was conducted in 120 outpatients without CAD, undergoing a CAC evaluation by computed tomography with the Agatston Calcium score, categorized as CAC^- (none) and CAC⁺ (≥1). Serum biomarkers were quantified by ELISA.

RESULTS

Lpa, dyslipidaemia and smoking were significantly higher (p=0.006, p≤0.0001 and p=0.001, respectively) in CAC⁺ patients. Serum netrin-1 levels were lower in CAC⁺ than in CAC^- patients (196.8±127.8pg/ml versus 748.3±103.2pg/ml, p≤0.0001), and a similar pattern was found for gremlin-1 (1.14±0.39ng/ml versus 4.33±1.20ng/ml, p≤0.0001). However, TNFα and MIP-1β were strongly upregulated in CAC⁺ patients (447.56±74pg/ml versus 1104±144pg/ml and 402.00±94pg/ml versus 905.0±101.6pg/ml, respectively, p≤0.001). Multivariate analyses revealed that low netrin-1 and gremlin-1 levels and high TNFα and MIP-1β amounts were associated with CAC presence, after adjustment for clinical and biochemical variables.

CONCLUSIONS

We found a netrin-1 and gremlin-1 deficiency and a TNFα and MIP-1β overproduction in CAC⁺ patients' serum. These proteins may be used to identify individuals with subclinical atherosclerosis. Further research is warranted in a larger cohort of patients to establish these chemotactic-related proteins as biomarkers that improve CAD risk stratification.

Prevalence and Prognosis of Nonobstructive Coronary Artery Disease in Patients Undergoing Coronary Angiography or Coronary Computed Tomography Angiography: A Meta-Analysis

OBJECTIVE

To evaluate the prevalence, clinical characteristics, and risk of cardiac events in patients with nonobstructive coronary artery disease (CAD).

PATIENTS AND METHODS

We searched PubMed, EMBASE, and the Cochrane Library from January 1, 1990, to November 31, 2015. Studies were included if they reported prevalence or prognosis of patients with nonobstructive CAD (≤50% stenosis) among patients with known or suspected CAD. Patients with nonobstructive CAD were further grouped as those with no angiographic CAD (0% or ≤20%) and those with mild CAD (>0% or >20% to ≤50%). Data were pooled using random effects modeling, and annualized event rates were assessed.

RESULTS

Fifty-four studies with 1,395,190 participants were included. The prevalence of patients with nonobstructive CAD was 67% (95% CI, 63%-71%) among patients with stable angina and 13% (95% CI, 11%-16%) among patients with non-ST-segment elevation acute coronary syndrome. The prevalence varied depending on sex, clinical setting, and risk profile of the population investigated. The risk of hard cardiac events (cardiac death or myocardial infarction) in patients with mild CAD was lower than that in patients with obstructive CAD (risk ratio, 0.28; 95% CI, 0.20-0.38) but higher than that in those with no angiographic CAD (risk ratio, 1.85; 95% CI, 1.52-2.26). The annualized event rates of hard cardiac events in patients with no angiographic CAD, mild CAD, and obstructive CAD were 0.3% (95% CI, 0.1%-0.4%), 0.7% (95% CI, 0.5%-1.0%), and 2.7% (95% CI, 1.7%-3.7%), respectively, among patients with stable angina and 1.2% (95% CI, 0.02%-2.3%), 4.1% (95% CI, 3.3%-4.9%), and 17.0% (95% CI, 8.4%-25.7%) among patients with non-ST-segment elevation acute coronary syndrome. The correlation between CAD severity and prognosis is consistent regardless of clinical presentation of all-cause death, myocardial infarction, total cardiovascular events, and revascularization.

CONCLUSION

Nonobstructive CAD is associated with a favorable prognosis compared with obstructive CAD, but it is not benign. The high prevalence and impaired prognosis of this population warrants further efforts to improve the risk stratification and management of patients with nonobstructive CAD.

Atorvastatin attenuates atherosclerotic plaque destabilization by inhibiting endoplasmic reticulum stress in hyperhomocysteinemic mice

Endoplasmic reticulum (ER) stress has been suggested to play a role in the progression of plaque vulnerability and the occurrence of acute complications of coronary atherosclerosis. Atorvastatin is known to exert pleiotropic effects on the cardiovascular system. The present study aimed to examine the stabilizing effects of atorvastatin on vulnerable plaques within hyperhomocysteinemic apolipoprotein E‑deficient (ApoE‑/‑) mice, and to investigate the potential mechanisms underlying ER stress in ApoE‑/‑ mice and macrophages. In the present study, ApoE‑/‑ mice were administrated methionine or atorvastatin, and were sacrificed after 2 months. Necrotic core size, collagen content and inflammatory cytokine infiltration were subsequently measured in the aortic lesions, in order to investigate plaque stability. Treatment with atorvastatin decreased the number and size of necrotic cores, increased collagen content, and downregulated tumor necrosis factor (TNF)‑α and matrix metalloproteinase (MMP)‑9 mRNA expression, as compared with the methionine group. Immunohistochemical analysis indicated that atorvastatin administration prevented ER stress activation in aortic lesions of hyperhomocysteinemic mice. Furthermore, macrophages were challenged with homocysteine (Hcy) in the presence or absence of atorvastatin and thapsigargin (an ER stress inducer). Atorvastatin suppressed Hcy‑induced ER stress, and downregulated TNF‑α and MMP‑9 mRNA expression in the macrophages. Conversely, thapsigargin attenuated the inhibitory effects of atorvastatin against Hcy‑induced TNF‑α and MMP‑9 expression. These results indicated that hyperhomocysteinemia may promote atherosclerotic plaque development and instability. In addition, atorvastatin was able to improve atherosclerotic plaque stability in hyperhomocysteinemic mice by inhibiting ER stress.

Polymerase delta-interacting protein 2 regulates collagen accumulation via activation of the Akt/mTOR pathway in vascular smooth muscle cells

OBJECTIVES

Polymerase delta interacting protein 2 (Poldip2) has previously been implicated in migration, proliferation and extracellular matrix (ECM) production in vascular smooth muscle cells. To better understand the role of Poldip2 in ECM regulation, we investigated the mechanism responsible for collagen I accumulation in Poldip2(+/-) mouse aortic smooth muscle cells (MASMs).

APPROACH AND RESULTS

Protein degradation and protein synthesis pathways were investigated. Depletion of Poldip2 had no effect on proteasome activity, but caused a partial reduction in autophagic flux. However, the rate of collagen I degradation was increased in Poldip2(+/-) vs. Poldip2(+/+) MASMs. Conversely, activation of the PI3K/Akt/mTOR signaling pathway, involved in regulation of protein synthesis, was significantly elevated in Poldip2(+/-) MASMs as was β1-integrin expression. Suppressing mTOR signaling using Akt inhibitor or rapamycin and reducing β1-integrin expression using siRNA prevented the increase in collagen I production. While collagen I and fibronectin were increased in Poldip2(+/-) MASMs, overall protein synthesis was not different from that in Poldip2(+/)(+)MASMs, suggesting selectivity of Poldip2 for ECM proteins.

CONCLUSIONS

Poldip2(+/-) MASMs exhibit higher β1-integrin expression and activity of the PI3K/Akt/mTOR signaling pathway, leading to increased ECM protein synthesis. These findings have important implications for vascular diseases in which ECM accumulation plays a role.

Lymphocyte subpopulations in myocardial infarction: a comparison between peripheral and intracoronary blood

The frequency and profile of lymphocyte subsets within the culprit coronary artery were investigated in 33 patients with myocardial infarction and compared to their systemic circulating counterparts. T cell subsets including CD4⁺CD28null, activated and regulatory T-cells, TH1/TH2/TH17 phenotypes, NK and B-cells were studied in intracoronary (IC) and arterial peripheral blood (PB) samples. CD4⁺CD28null T-lymphocytes were significantly increased in IC compared to PB (3.7 vs. 2.9 %, p < 0.0001). Moreover, patients with more than 6 h of evolution of STEMI exhibited higher levels of CD4⁺CD28null T-cells suggesting that this subset may be associated with more intense myocardial damage. The rare NK subpopulation CD3⁻CD16⁺CD56⁻ was also increased in IC samples (5.6 vs. 3.9 %, p = 0.006). CD4⁺CD28null T-cells and CD3⁻CD16⁺CD56⁻ NK subpopulations were also associated with higher CK levels. Additionally, IFN-γ and IL10 were significantly higher in IC CD4⁺ lymphocytes. Particular immune cell populations with a pro-inflammatory profile at the site of onset were increased relative to their circulating counterparts suggesting a pathophysiological role of these cells in plaque instability, thrombi and myocardial damage.

Fluorescence Lifetime Imaging Combined with Conventional Intravascular Ultrasound for Enhanced Assessment of Atherosclerotic Plaques: an Ex Vivo Study in Human Coronary Arteries

This study evaluates the ability of label-free fluorescence lifetime imaging (FLIm) to complement intravascular ultrasound (IVUS) for concurrent visualization of human coronary vessel composition, structure, and pathology. Co-registered FLIm and IVUS data from 16 coronary segments were correlated to eight distinct pathological features including thin-cap fibroatheroma (TCFA). The sensitivity, specificity, and positive predictive value for combined FLIm-IVUS (89, 99, 89 %) were better than FLIm (70, 98, 88 %) and IVUS (45, 94, 62 %) alone in distinguishing between pathologies. FLIm can assess compositional changes in luminal surface through variations in fluorescence lifetime values (<3.5 ns for lipid-rich areas; >4 ns for collagen-rich areas) enabling detection of macrophages in fibrous caps (sensitivity, 86 %) and distinguishing between relatively stable thick-cap fibroatheromas and rupture-prone TCFA (sensitivity, 80 %) amongst other features. Current results demonstrate the potential of FLIm-IVUS as a new intravascular method for improved evaluation of plaques that may subsequently aid in guiding coronary intervention.

Nonobstructive coronary artery disease and risk of myocardial infarction

IMPORTANCE

Little is known about cardiac adverse events among patients with nonobstructive coronary artery disease (CAD).

OBJECTIVE

To compare myocardial infarction (MI) and mortality rates between patients with nonobstructive CAD, obstructive CAD, and no apparent CAD in a national cohort.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of all US veterans undergoing elective coronary angiography for CAD between October 2007 and September 2012 in the Veterans Affairs health care system. Patients with prior CAD events were excluded.

EXPOSURES

Angiographic CAD extent, defined by degree (no apparent CAD: no stenosis >20%; nonobstructive CAD: ≥1 stenosis ≥20% but no stenosis ≥70%; obstructive CAD: any stenosis ≥70% or left main [LM] stenosis ≥50%) and distribution (1, 2, or 3 vessel).

MAIN OUTCOMES AND MEASURES

The primary outcome was 1-year hospitalization for nonfatal MI after the index angiography. Secondary outcomes included 1-year all-cause mortality and combined 1-year MI and mortality.

RESULTS

Among 37,674 patients, 8384 patients (22.3%) had nonobstructive CAD and 20,899 patients (55.4%) had obstructive CAD. Within 1 year, 845 patients died and 385 were rehospitalized for MI. Among patients with no apparent CAD, the 1-year MI rate was 0.11% (n = 8, 95% CI, 0.10%-0.20%) and increased progressively by 1-vessel nonobstructive CAD, 0.24% (n = 10, 95% CI, 0.10%-0.40%); 2-vessel nonobstructive CAD, 0.56% (n = 13, 95% CI, 0.30%-1.00%); 3-vessel nonobstructive CAD, 0.59% (n = 6, 95% CI, 0.30%-1.30%); 1-vessel obstructive CAD, 1.18% (n = 101, 95% CI, 1.00%-1.40%); 2-vessel obstructive CAD, 2.18% (n = 110, 95% CI, 1.80%-2.60%); and 3-vessel or LM obstructive CAD, 2.47% (n = 137, 95% CI, 2.10%-2.90%). After adjustment, 1-year MI rates increased with increasing CAD extent. Relative to patients with no apparent CAD, patients with 1-vessel nonobstructive CAD had a hazard ratio (HR) for 1-year MI of 2.0 (95% CI, 0.8-5.1); 2-vessel nonobstructive HR, 4.6 (95% CI, 2.0-10.5); 3-vessel nonobstructive HR, 4.5 (95% CI, 1.6-12.5); 1-vessel obstructive HR, 9.0 (95% CI, 4.2-19.0); 2-vessel obstructive HR, 16.5 (95% CI, 8.1-33.7); and 3-vessel or LM obstructive HR, 19.5 (95% CI, 9.9-38.2). One-year mortality rates were associated with increasing CAD extent, ranging from 1.38% among patients without apparent CAD to 4.30% with 3-vessel or LM obstructive CAD. After risk adjustment, there was no significant association between 1- or 2-vessel nonobstructive CAD and mortality, but there were significant associations with mortality for 3-vessel nonobstructive CAD (HR, 1.6; 95% CI, 1.1-2.5), 1-vessel obstructive CAD (HR, 1.9; 95% CI, 1.4-2.6), 2-vessel obstructive CAD (HR, 2.8; 95% CI, 2.1-3.7), and 3-vessel or LM obstructive CAD (HR, 3.4; 95% CI, 2.6-4.4). Similar associations were noted with the combined outcome.

CONCLUSIONS AND RELEVANCE

In this cohort of patients undergoing elective coronary angiography, nonobstructive CAD, compared with no apparent CAD, was associated with a significantly greater 1-year risk of MI and all-cause mortality. These findings suggest clinical importance of nonobstructive CAD and warrant further investigation of interventions to improve outcomes among these patients.

CXCR4 blockade induces atherosclerosis by affecting neutrophil function

AIMS

The SDF-1α/CXCR4 dyad was previously shown by us and others to be instrumental in intimal hyperplasia as well as early stage atherosclerosis. We here sought to investigate its impact on clinically relevant stages of atherosclerosis in mouse and man.

METHODS AND RESULTS

Immunohistochemical analysis of CXCR4 expression in human atherosclerotic lesions revealed a progressive accumulation of CXCR4(+) cells during plaque progression. To address causal involvement of CXCR4 in advanced stages of atherosclerosis we reconstituted LDLr(-/-) mice with autologous bone marrow infected with lentivirus encoding SDF-1α antagonist or CXCR4 degrakine, which effects proteasomal degradation of CXCR4. Functional CXCR4 blockade led to progressive plaque expansion with disease progression, while also promoting intraplaque haemorrhage. Moreover, CXCR4 knockdown was seen to augment endothelial adhesion of neutrophils. Concordant with this finding, inhibition of CXCR4 function increased adhesive capacity and reduced apoptosis of neutrophils and resulted in hyperactivation of circulating neutrophils. Compatible with a role of the neutrophil CXCR4 in end-stage atherosclerosis, CXCR4 expression by circulating neutrophils was lowered in patients with acute cardiovascular syndromes.

CONCLUSION

In conclusion, CXCR4 contributes to later stages of plaque progression by perturbing neutrophil function.

The prognostic significance of declining health-related quality of life scores at 6 months after coronary artery bypass surgery

PURPOSE

Health-related quality of life (HRQoL) measured on the EQ-5D (European quality of life-5 dimensions)-questionnaire has been shown to improve after coronary artery bypass grafting (CABG), this study investigated whether changes in HRQoL predict later morbidity.

METHODS

Included were 404 consecutive patients undergoing isolated CABG between 2008 and 2010 who filled the EQ-5D-questionnaire at baseline and 6 months postoperatively. Records were reviewed for later major adverse cardiac and cerebrovascular events (MACCE) after 6 months. Follow-up was 38.6 months (10-58).

RESULTS

Patients who suffered later MACCE more often had suffered an in-hospital postoperative stroke, had a longer in-hospital stay, had lower HRQoL scores at 6 months and deteriorated on several EQ-5D-subscales. Logistic regression showed 6 months visual analogue scale scores and declining function scores to be independent predictors of later MACCE.

CONCLUSION

Deteriorating function and HRQoL-scores at 6 months as compared to baseline postoperatively predict later adverse cardiovascular events after CABG.

Update on the efficacy of statin treatment in acute coronary syndromes

BACKGROUND

The natural history of atherosclerosis might involve coronary plaque rupture/erosion, thrombus formation and vessel lumen occlusion, clinically recognized as acute coronary syndrome (ACS). International guidelines strongly recommend early statin administration in patients admitted for ACS. In addition to lowering circulating levels of low-density lipoprotein cholesterol (LDL-c), statin treatment was shown to promote plaque stabilization or regression in several ways, including reduction in necrotic lipid core, anti-inflammatory effects and improvement in endothelial function. The aim of this review is to summarize clinical evidence on the role of statins in secondary prevention of ACS.

MATERIALS AND METHODS

This narrative review is based on the material found on medline and pubmed up to August 2013. We looked for the terms 'statin, acute coronary syndromes' in combination with 'atherosclerosis, acute myocardial infarction, pathophysiology'.

RESULTS

This review article emphasizes the relevance of the timing of statin administration to improve the outcomes after ACS. Early and continuous statin administration has emerged as key features to prevent adverse events, especially in patients admitted for ACS undergoing percutaneous coronary intervention. Clinical trials matching the improved clinical outcome with the imaging of atherosclerotic plaque stabilization/regression, further supporting the effectiveness of statin therapy. However, the achievement of these goals requires high dose of statins, thus increasing the risk of adverse events.

CONCLUSIONS

Although clinical trials and meta-analyses have provided conflicting results, it is likely that in clinical practice, the rate of adverse events is higher, so that many concerns still remain about a statin high-dose approach in ACS patients.

The vulnerable plaque: current concepts and future perspectives on coronary morphology, composition and wall stress imaging

Cardiovascular imaging plays an important role in the identification and characterization of the vulnerable plaque. A major goal is the ability to identify individuals at risk of plaque rupture and developing an acute coronary syndrome. Early recognition of rupture-prone atherosclerotic plaques may lead to the development of pharmacologic and interventional strategies to reduce acute coronary events. We review state-of-the-art cardiovascular imaging for identification of the vulnerable plaque. There is ample evidence of a close relationship between plaque morphology and patient outcome, but molecular imaging can add significant information on tissue characterization, inflammation and subclinical thrombosis. Additionally, identifying arterial wall exposed to high shear stress may further identify rupture-prone arterial segments. These new modalities may help reduce the individual, social and economic burden of cardiovascular disease.

Novel small leucine-rich repeat protein podocan is a negative regulator of migration and proliferation of smooth muscle cells, modulates neointima formation, and is expressed in human atheroma

BACKGROUND

Smooth muscle cell (SMC) migration and proliferation critically influence the clinical course of vascular disease. We tested the effect of the novel small leucine-rich repeat protein podocan on SMC migration and proliferation using a podocan-deficient mouse in combination with a model of arterial injury and aortic explant SMC culture. In addition, we examined the effect of overexpression of the human form of podocan on human SMCs and tested for podocan expression in human atherosclerosis. In all these conditions, we concomitantly evaluated the Wnt-TCF (T-cell factor) pathway.

METHODS AND RESULTS

Podocan was strongly and selectively expressed in arteries of wild-type mice after injury. Podocan-deficient mice showed increased arterial lesion formation compared with wild-type littermates in response to injury (P<0.05). Also, SMC proliferation was increased in arteries of podocan-deficient mice compared with wild-type (P<0.05). In vitro, migration and proliferation were increased in podocan-deficient SMCs and were normalized by transfection with the wild-type podocan gene (P<0.05). In addition, upregulation of the Wnt-TCF pathway was found in SMCs of podocan-deficient mice both in vitro and in vivo. On the other hand, podocan overexpression in human SMCs significantly reduced SMC migration and proliferation, inhibiting the Wnt-TCF pathway. Podocan and a Wnt-TCF pathway marker were differently expressed in human coronary restenotic versus primary lesions.

CONCLUSIONS

Podocan appears to be a potent negative regulator of the migration and proliferation of both murine and human SMCs. The lack of podocan results in excessive arterial repair and prolonged SMC proliferation, which likely is mediated by the Wnt-TCF pathway.

Pathophysiological role of neutrophils in acute myocardial infarction

The pathogenesis of acute myocardial infarction is known to be mediated by systemic, intraplaque and myocardial inflammatory processes. Among different immune cell subsets, compelling evidence now indicates a pivotal role for neutrophils in acute coronary syndromes. Neutrophils infiltrate coronary plaques and the infarcted myocardium and mediate tissue damage by releasing matrix-degrading enzymes and reactive oxygen species. In addition, neutrophils are also involved in post-infarction adverse cardiac remodelling and neointima formation after angioplasty. The promising results obtained in preclinical modelswith pharmacological approaches interfering with neutrophil recruitment or function have confirmed the pathophysiological relevance of these immune cells in acute coronary syndromes and prompted further studies of these therapeutic interventions. This narrative review will provide an update on the role of neutrophils in acute myocardial infarction and on the pharmacological means that were devised to prevent neutrophil-mediated tissue damage and to reduce post-ischaemic outcomes.

Blocking TLR2 activity diminishes and stabilizes advanced atherosclerotic lesions in apolipoprotein E-deficient mice

AIM

Toll-like receptor 2 (TLR2) signaling plays a critical role in the initiation of atherosclerosis. The aim of this study was to investigate whether blocking TLR2 activity could produce therapeutic effects on advanced atherosclerosis.

METHODS

Forty-week old apolipoprotein E-deficient (ApoE(-/-)) mice fed on a normal diet were intravenously injected with a TLR2-neutralizing antibody or with an isotype-matched IgG for 18 weeks. Double-knockout ApoE(-/-)Tlr2(-/-) mice were taken as a positive control. At the end of the treatments, the plasma lipid levels were measured, and the plaque morphology, pro-inflammatory cytokines expression and apoptosis in arteries were analyzed. In the second part of this study, 6-week old ApoE(-/-) and ApoE(-/-)Tlr2(-/-) mice fed on a high-cholesterol diet for 12 to 24 weeks, the expression levels of TLR2 and apoptotic markers in arteries were examined.

RESULTS

Blockade of TLR2 activity with TLR2-neutralizing antibody or knockout of Tlr2 gene did not alter the plasma lipid levels in ApoE(-/-) mice. However, the pharmacologic and genetic manipulations significantly reduced the plaque size and vessel stenosis, and increased plaque stability in the brachiocephalic arteries. The protective effects of TLR2 antagonism were associated with the suppressed expression of pro-inflammatory cytokines IL-6 and TNF-α and the inactivation of transcription factors NF-κB and Stat3. In addition, blocking TLR2 activity attenuated ER stress-induced macrophage apoptosis in the brachiocephalic arteries, which could promote the resolution of necrotic cores in advanced atherosclerosis. Moreover, high-cholesterol diet more prominently accelerated atherosclerotic formation and increased the expression of pro-apoptotic protein CHOP and apoptosis in ApoE(-/-) mice than in ApoE(-/-)Tlr2(-/-) mice.

CONCLUSION

The pharmacologic or genetic blockade of TLR2 activity diminishes and stabilizes advanced atherosclerotic lesions in ApoE(-/-) mice. Thus, targeting TLR2 signaling may be a promising therapeutic strategy against advanced atherosclerosis.

The prevention and regression of atherosclerotic plaques: emerging treatments

Occlusive vascular diseases, such as sudden coronary syndromes, stroke, and peripheral arterial disease, are a huge burden on the health care systems of developed and developing countries. Tremendous advances have been made over the last few decades in the diagnosis and treatment of atherosclerotic diseases. Intravascular ultrasound has been able to provide detailed information of plaque anatomy and has been used in several studies to assess outcomes. The presence of atherosclerosis disrupts the normal protective mechanism provided by the endothelium and this mechanism has been implicated in the pathophysiology of coronary artery disease and stroke. Efforts are being put into the prevention of atherosclerosis, which has been shown to begin in childhood. This paper reviews the pathophysiology of atherosclerosis and discusses the current options available for the prevention and reversal of plaque formation.

Dichotomy in Hedgehog signaling between human healthy vessel and atherosclerotic plaques

The major cause for plaque instability in atherosclerotic disease is neoangiogenic revascularization, but the factors controlling this process remain only partly understood. Hedgehog (HH) is a morphogen with important functions in revascularization, but its function in human healthy vessel biology as well as in atherosclerotic plaques has not been well investigated. Hence, we determined the status of HH pathway activity both in healthy vessels and atherosclerotic plaques. A series of 10 healthy organ donor-derived human vessels, 17 coronary atherosclerotic plaques and 24 atherosclerotic carotid plaques were investigated for HH pathway activity. We show that a healthy vessel is characterized by a high level of HH pathway activity but that atherosclerotic plaques are devoid of HH signaling despite the presence of HH ligand in these pathological structures. Thus, a dichotomy between healthy vessels and atherosclerotic plaques with respect to the activation status of the HH pathway exists, and it is tempting to suggest that downregulation of HH signaling contributes to long-term plaque stability.

The SHAPE guideline: ahead of its time or just in time?

In 2006, a grass roots movement called SHAPE (Screening for Heart Attack Prevention and Education) published a novel practice guideline for cardiovascular screening in the asymptomatic at-risk population. It suggested the use of noninvasive tests for subclinical atherosclerosis in cardiovascular risk assessment to target intensified preventive care to those at highest risk. The SHAPE guideline received much attention but not as much support from the "official" medical societies. However, subsequent studies published since 2006 have now provided strong supportive evidence for the strategy spearheaded by the SHAPE guideline. Indeed, the latest guidelines issued jointly by the American Heart Association and the American College of Cardiology have elevated recommendation levels for noninvasive imaging of subclinical atherosclerosis. This change is widely viewed as a significant step toward the SHAPE guidelines. The background for SHAPE and the evidence behind the recommendation to use coronary artery calcium score measured by computed tomography, carotid intima-media thickness and plaque measured by ultrasound, and ankle-brachial index in cardiovascular risk assessment is reviewed in this article.

Progress in HDL-based therapies for atherosclerosis

Atherosclerosis is a chronic inflammatory disease affecting medium and large arteries resulting from a complex interaction between genetic and environmental risk factors that include dyslipidemia, hypertension, diabetes mellitus, and smoking. The most serious manifestations of atherosclerotic vascular disease, such as unstable angina, myocardial infarction, ischemic stroke, and sudden death, largely result from thrombosis superimposed on a disrupted (ruptured or eroded) atherosclerotic plaque. Adoption and maintenance of a healthy lifestyle coupled with management of modifiable risk factors significantly reduce the adverse clinical consequences of athero-thrombosis. Reducing low-density lipoprotein cholesterol levels using statins and other agents serves as the primary pharmacologic approach to stabilize atherosclerotic vascular disease. However, a large residual risk remains, prompting the search for additional therapies for atherosclerosis management, such as raising atheroprotective high-density lipoprotein (HDL) and/or improving HDL function. This review focuses on new and emerging HDL-based therapeutic strategies targeting atherosclerosis.

Solid-phase immunoglobulins IgG and IgM activate macrophages with solid-phase IgM acting via a novel scavenger receptor a pathway

IgG may accelerate atherosclerosis via ligation of proinflammatory Fcγ receptors; however, IgM is unable to ligate FcγR and is often considered vasculoprotective. IgM aggravates ischemia-reperfusion injury, and solid-phase deposits of pure IgM, as seen with IgM-secreting neoplasms, are well known clinically to provoke vascular inflammation. We therefore examined the molecular mechanisms by which immunoglobulins can aggravate vascular inflammation, such as in atherosclerosis. We compared the ability of fluid- and solid-phase immunoglobulins to activate macrophages. Solid-phase immunoglobulins initiated prothrombotic and proinflammatory functions in human macrophages, including NF-κB p65 activation, H(2)O(2) secretion, macrophage-induced apoptosis, and tissue factor expression. Responses to solid-phase IgG (but not to IgM) were blocked by neutralizing antibodies to CD16 (FcγRIII), consistent with its known role. Macrophages from mice deficient in macrophage scavenger receptor A (SR-A; CD204) had absent IgM binding and no activation by solid-phase IgM. RNA interference-mediated knockdown of SR-A in human macrophages suppressed activation by solid-phase IgM. IgM binding to SR-A was demonstrated by both co-immunoprecipitation studies and the binding of fluorescently labeled IgM to SR-A-transfected cells. Immunoglobulins on solid-phase particles around macrophages were found in human plaques, increased in ruptured plaques compared with stable ones. These observations indicate that solid-phase IgM and IgG can activate macrophages and destabilize vulnerable plaques. Solid-phase IgM activates macrophages via a novel SR-A pathway.

Bypassing the Patient: Comparison of Biocompatible Models for the Future of Vascular Tissue Engineering

The objective of vascular tissue engineering is to develop tissue-engineered, biocompatible, small-diameter vessels suitable to withstand in vivo systolic pressures as well as be immunologically compatible with the patient, in order to minimize graft rejection. In this study, we present and compare two models of biocompatible, tissue-engineered vascular grafts (TEVG), using chitosan and acellularized rat aortas as options for scaffolds. Human aortic adventitial smooth muscle cells and fibroblasts were seeded onto a fibrin gel and subsequently wrapped around either of the two scaffolds. After several weeks of maturation in standard culturing conditions, the graft models were analyzed and compared by mechanical testing, cell viability, and histology. Histological and viability data showed that both models were viable and developed similarly, with a scaffold surrounded by two layers of cells, the fibroblasts lying on top of the smooth muscle cells. Both models responded to 200 mM potassium chloride (KCl) (tensions of 38 ± 3, 78 ± 13, and 52 ± 7 μN) and 25 mM 8-bromo-cyclic AMP (tensions of −23 ± 4, −39 ± 10, and −31 ± 12 μN) stimulation by vasoconstriction and vasorelaxation ( n = 3), respectively; however, the chitosan model was unable to maintain the contracted and relaxed tension. Because the acellularized aorta TEVGs were able to maintain stimulated tension better than chitosan TEVGs, we concluded that the acellularized aorta model was better suited for further development.