Markers of instability in high-risk carotid plaques are reduced by statins

NOX4 mRNA correlates with plaque stability in patients with carotid artery stenosis

Carotid artery stenosis (CAS) develops from atherosclerotic lesions and plaques. Plaque rupture or stenosis may result in occlusion of the carotid artery. Accordingly, the asymptomatic disease becomes symptomatic, characterized by ischemic stroke or transient ischemic attacks, indicating an urgent need for better understanding of the underlying molecular mechanisms and eventually prevent symptomatic CAS. NOX4, a member of the NADPH oxidase family, has anti-atherosclerotic and anti-inflammatory properties in animal models of early atherosclerosis. We hypothesized that NOX4 mRNA expression is linked to protective mechanisms in CAS patients with advanced atherosclerotic lesions as well. Indeed, NOX4 mRNA expression is lower in patients with symptomatic CAS. A low NOX4 mRNA expression is associated with an increased risk of the development of clinical symptoms. In fact, NOX4 appears to be linked to plaque stability, apoptosis and plaque hemorrhage. This is supported by cleaved caspase-3 and glycophorin C and correlates inversely with plaque NOX4 mRNA expression. Even healing of a ruptured plaque appears to be connected to NOX4, as NOX4 mRNA expression correlates to fibrous cap collagen and is reciprocally related to MMP9 activity. In conclusion, low intra-plaque NOX4 mRNA expression is associated with an increased risk for symptomatic outcome and with reduced plaque stabilizing mechanisms suggesting protective effects of NOX4 in human advanced atherosclerosis.

Synopsis of Biomarkers of Atheromatous Plaque Formation, Rupture and Thrombosis in the Diagnosis of Acute Coronary Syndromes

Acute coronary syndrome is the main cause of mortality and morbidity worldwide and early diagnosis is a challenge for clinicians. Though cardiac Troponin, the most commonly used biomarker, is the gold standard for myocardial necrosis, it is blind for ischemia without necrosis. Therefore, ideal biomarkers are essential in the care of patients presenting with symptoms suggestive of cardiac ischemia. The ideal biomarker or group of biomarkers of atheromatous plaque formation, rupture and thrombosis for timely and accurate diagnosis of acute coronary syndrome is a current need. Therefore, we discuss the existing understanding and future of biomarkers of atheromatous plaque formation, rupture and thrombosis of acute coronary syndrome in this review. Keywords were searched from Medline, ISI, IBSS and Google Scholar databases. Further, the authors conducted a manual search of other relevant journals and reference lists of primary articles. The development of high-sensitivity troponin assays facilitates earlier exclusion of acute coronary syndrome, contributing to a reduced length of stay at the emergency department, and earlier treatment resulting in better outcomes. Although researchers have investigated biomarkers of atheromatous plaque formation, rupture and thrombosis to help early diagnosis of cardiac ischemia, most of them necessitate validation from further analysis. Among these biomarkers, pregnancy-associated plasma protein-A, intercellular adhesion molecule-1, and endothelial cell-specific molecule- 1(endocan) have shown promising results in the early diagnosis of acute coronary syndrome but need further evaluation. However, the use of a combination of biomarkers representing varying pathophysiological mechanisms of cardiac ischemia will support risk assessment, diagnosis and prognosis in these patients and this is the way forward.

Biomarkers in unstable carotid plaque: Physiopathology and Prediction

AIMS

To study the role of cytokines and vascular inflammatory biomarkers in unstable carotid plaque.

BACKGROUND

Clinical studies showed that not only the degree of stenosis but also the type of carotid plaque can be responsible for ipsilateral ischemic stroke.

OBJECTIVE

The objective of this study is to suggest a role for vulnerable carotid atherosclerotic disease in the occurrence of ischemic stroke.

METHODS

PubMed, Embase, Cochrane library, and reference lists have been used to evaluate articles published until February 15, 2021.

RESULTS

Several factors may be involved in unstable plaque. Clinical studies support the involvement of brain inflammatory biomarkers as well as cytokines in the unstable carotid plaque.

CONCLUSIONS

Biomarkers could help to stratify patients with a vulnerable carotid plaque and to personalize the drug treatment. In this review, we briefly discuss the characteristics of vulnerable plaque and the role of biomarkers in the vulnerable carotid plaque.

Prestroke Statins Improve Prognosis of Atrial Fibrillation-Associated Stroke through Increasing Suppressor of Cytokine Signaling-3 Levels

BACKGROUND

Cerebral infarction associated with atrial fibrillation (AF) has relatively higher mortality and morbidity rates than other types of stroke. Statins are being commonly prescribed to patients with stoke. However, the use of statins in AF-related stroke, especially prestroke, has not been well studied. This study aimed to investigate whether the use of prestroke statins could improve clinical outcomes in patients with AF-related acute ischemic stroke (AIS) and its mechanism.

METHODS

This prospective study enrolled 453 AF-associated AIS patients from 4 medical centers and divided them into 2 groups based on the statin use before the stroke episode. All patients received comprehensive clinical examinations including 72-h Holter electrocardiogram monitoring and were followed up for 3 months. Plasma suppressor of cytokine signaling-3 (SOCS-3) and matrix metalloproteinase-9 (MMP-9) levels were measured by ELISA on admission and days 3 and 7 after enrollment. The endpoints were death, major disability (modified Rankin Scale score ≥3), and composite outcome (death/major disability) at 3 months after the AIS episode.

RESULTS

Plasma SOCS-3 levels were significantly increased and MMP-9 levels decreased in patients in the prestroke statin group on hospital admission and days 3 and 7 after enrollment (p < 0.001). Furthermore, our data suggested that baseline plasma SOCS-3 levels were associated with increased risk of 3-month mortality (adjusted odds ratio [OR], 1.012; 95% confidence interval [CI], 1.006-1.018; p < 0.001) and major disability (adjusted OR, 1.013; 95% CI, 1.007-1.02; p < 0.001). Similarly, baseline plasma MMP-9 levels were also associated with increased risk of 3-month mortality (adjusted OR, 1.037; 95% CI, 1.022-1.053; p < 0.001) and major disability (adjusted OR, 1.038; 95% CI, 1.022-1.55; p < 0.001).

CONCLUSION

Our data suggested that the prestroke use of statins improved the clinical outcomes in AIS patients with AF by upregulating the level of SOCS-3 and reducing the plasma MMP-9 level.

Matrix Metalloproteinases as Biomarkers of Atherosclerotic Plaque Instability

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases responsible for tissue remodeling and degradation of extracellular matrix (ECM) proteins. MMPs may modulate various cellular and signaling pathways in atherosclerosis responsible for progression and rupture of atherosclerotic plaques. The effect of MMPs polymorphisms and the expression of MMPs in both the atherosclerotic plaque and plasma was shown. They are independent predictors of atherosclerotic plaque instability in stable coronary heart disease (CHD) patients. Increased levels of MMPs in patients with advanced cardiovascular disease (CAD) and acute coronary syndrome (ACS) was associated with future risk of cardiovascular events. These data confirm that MMPs may be biomarkers in plaque instability as they target in potential drug therapies for atherosclerosis. They provide important prognostic information, independent of traditional risk factors, and may turn out to be useful in improving risk stratification.

Immune cells in carotid artery plaques: what can we learn from endarterectomy specimens?

INTRODUCTION

Endarterectomy specimens represent a unique opportunity to study atherosclerosis. This review aims to summarize the recent knowledge of atherogenesis from studies characterizing a cellular composition of carotid endarterectomy specimens.

EVIDENCE ACQUISITION

A non-systematic literature review was carried out to summarize recent knowledge regarding ex vivo analysis of carotid artery plaque composition. Upon evaluation of their relevance, and elaborate forward and backward search, 95 articles were included in the review.

EVIDENCE SYNTHESIS

Despite the significant advancement of in vivo imaging techniques, the stroke prediction based on carotid artery plaque morphology is not reliable. Besides analyses of plaque morphology, present studies focus on precise characterization of the different immune cell types and elucidation of their role in plaque development. Plaque content analyses revealed the presence of various immune cells in carotid artery plaques. Presence of different immune cells subpopulations can be connected to some undesirable changes in plaque stability.

CONCLUSIONS

Since the destabilization of the atherosclerotic plaque is a multifactorial process, a combination of various methods should be used to characterize the unstable plaques more accurately. In this context, studies characterizing plaque content from a cellular point of view could elucidate some processes underlying the plaque progression. Together with morphological evaluation, these analyses could enable more precise assessment of plaque stability.

Atherosclerotic plaque instability in carotid arteries: miR-200c as a promising biomarker

Early recognition of vulnerable carotid plaques could help in identifying patients at high stroke risk, who may benefit from earlier revascularisation. Nowadays, different biomarkers of plaque instability have been unravelled, among these miRNAs are promising tools for the diagnosis and treatment of atherosclerosis. Inflammation, reactive oxygen species (ROS) and endothelial dysfunction play a key role in unstable plaques genesis. We showed that miR-200c induces endothelial dysfunction, ROS production and a positive mechanism among miR-200c and miR-33a/b, two miRNAs involved in atherosclerosis progression. The goal of the present study was to determine whether miR-200c could be an atherosclerosis biomarker. Carotid plaques of patients that underwent carotid endarterectomy (CEA) were assayed for miR-200c expression. miR-200c was up-regulated in carotid plaques (n=22) and its expression was higher in unstable (n=12) compared with stable (n=10) plaques. miR-200c positively correlated with instability biomarkers (i.e. monocyte chemoattractant protein-1, cicloxigenase-2 (COX2), interleukin 6 (IL6), metalloproteinase (MMP) 1 (MMP1), 9 (MMP9)) and miR-33a/b. Moreover, miR-200c negatively correlated with stability biomarkers (i.e. zinc finger E-box binding homoeobox 1 (ZEB1), endothelial nitric oxide (NO) synthase (eNOS), forkhead boxO1 (FOXO1) and Sirtuin1 (SIRT1)) (stable plaques = 15, unstable plaques = 15). Circulating miR-200c was up-regulated before CEA in 24 patients, correlated with miR-33a/b and decreased 1 day after CEA. Interestingly, 1 month after CEA, circulating miR-200c is low in patients with stable plaques (n=11) and increased to control levels, in patients with unstable plaques (n=13). Further studies are needed to establish whether miR-200c represents a circulating biomarker of plaque instability. Our results show that miR-200c is an atherosclerotic plaque progression biomarker and suggest that it may be clinically useful to identify patients at high embolic risk.

Matrix metalloproteinase-8 and tissue inhibitor of matrix metalloproteinase-1 predict incident cardiovascular disease events and all-cause mortality in a population-based cohort

Background Extracellular matrix degrading proteases and their regulators play an important role in atherogenesis and subsequent plaque rupture leading to acute cardiovascular manifestations. Design and methods In this prospective cohort study, we investigated the prognostic value of circulating matrix metalloproteinase-8, tissue inhibitor of matrix metalloproteinase-1 concentrations, the ratio of matrix metalloproteinase-8/ tissue inhibitor of matrix metalloproteinase-1 and, for comparison, myeloperoxidase and C-reactive protein concentrations for incident cardiovascular disease endpoints. The population-based FINRISK97 cohort comprised 7928 persons without cardiovascular disease at baseline. The baseline survey included a clinical examination and blood sampling. During a 13-year follow-up the endpoints were ascertained through national healthcare registers. The associations of measured biomarkers with the endpoints, including cardiovascular disease event, coronary artery disease, acute myocardial infarction, stroke and all-cause death, were analysed using Cox regression models. Discrimination and reclassification models were used to evaluate the clinical implications of the biomarkers. Results Serum tissue inhibitor of matrix metalloproteinase-1 and C-reactive protein concentrations were associated significantly with increased risk for all studied endpoints. Additionally, matrix metalloproteinase-8 concentration was associated with the risk for a coronary artery disease event, myocardial infarction and death, and myeloperoxidase concentration with the risk for cardiovascular disease events, stroke and death. The only significant association for the matrix metalloproteinase-8/ tissue inhibitor of matrix metalloproteinase-1 ratio was observed with the risk for myocardial infarction. Adding tissue inhibitor of matrix metalloproteinase-1 to the established risk profile improved risk discrimination of myocardial infarction ( p=0.039) and death (0.001). Both matrix metalloproteinase-8 (5.2%, p < 0.001) and tissue inhibitor of matrix metalloproteinase-1 (12.9%, p < 0.001) provided significant clinical net reclassification improvement for death. Conclusions Serum matrix metalloproteinase-8 and tissue inhibitor of matrix metalloproteinase-1 can be considered as biomarkers of incident cardiovascular disease events and death.

Identification of neovascularization by contrast-enhanced ultrasound to detect unstable carotid stenosis

Background

Plaque neovascularization accompanies local inflammation and critically contributes to plaque instability. Correct identification of intraplaque neovascularization by contrast–enhanced ultrasound (CEUS) may provide an additional risk marker in carotid stenosis. This pilot study investigates the correlation between histological evaluation of carotid plaque specimens and pre-surgery CEUS to identify neovascularization.

Methods

17 patients with high-grade internal carotid artery (ICA) stenosis were studied. CEUS was performed in all patients shortly before carotid endarterectomy. Neovascularization, infiltration of T cells and macrophages along with intraplaque hemorrhage were studied in excised plaques by immunohistochemistry. Ultrasound-based four-level and two-level classification systems for neovascularization were used. CEUS findings were compared with histological findings.

Results

Scores on the CEUS-based four-level and two-level classifications were robustly correlated with the density of intraplaque vessels (r = 0.635, p = 0.006 and r = 0.578, p = 0.015, respectively). Histological evaluation of regions with strong and prolonged intraplaque enhancement typically showed strong intraplaque neovascularization in conjunction with acute intraplaque hemorrhage. Moreover, higher grades of intraplaque neovascularization as determined by ultrasound were associated with a higher percentage of macrophage-rich areas.

Conclusion

CEUS is a technique well suited to gauge the degree of neovascularization of carotid plaques. Future research will have to define the reliability and validity of CEUS in everyday clinical practice. Further, our study suggests that CEUS may also be useful to pick up features of vulnerable plaques such as acute intraplaque hemorrhages.

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

Purpose

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

Procedures

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

Results

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

Conclusion

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

Gene expression signatures, pathways and networks in carotid atherosclerosis

BACKGROUND

Embolism from unstable atheromas in the carotid bifurcation is a major cause of stroke. Here, we analysed gene expression in endarterectomies from patients with symptomatic (S) and asymptomatic (AS) carotid stenosis to identify pathways linked to plaque instability.

METHODS

Microarrays were prepared from plaques (n = 127) and peripheral blood samples (n = 96) of S and AS patients. Gene set enrichment, pathway mapping and network analyses of differentially expressed genes were performed.

RESULTS

These studies revealed upregulation of haemoglobin metabolism (P = 2.20E-05) and bone resorption (P = 9.63E-04) in S patients. Analysis of subgroups of patients indicated enrichment of calcification and osteoblast differentiation in S patients on statins, as well as inflammation and apoptosis in plaques removed >1 month compared to <2 weeks after symptom. By prediction profiling, a panel of 30 genes, mostly transcription factors, discriminated between plaques from S versus AS patients with 78% accuracy. By meta-analysis, common gene networks associated with atherosclerosis mapped to hypoxia, chemokines, calcification, actin cytoskeleton and extracellular matrix. A set of dysregulated genes (LMOD1, SYNPO2, PLIN2 and PPBP) previously not described in atherosclerosis were identified from microarrays and validated by quantitative PCR and immunohistochemistry.

CONCLUSIONS

Our findings confirmed a central role for inflammation and proteases in plaque instability, and highlighted haemoglobin metabolism and bone resorption as important pathways. Subgroup analysis suggested prolonged inflammation following the symptoms of plaque instability and calcification as a possible stabilizing mechanism by statins. In addition, transcriptional regulation may play an important role in the determination of plaque phenotype. The results from this study will serve as a basis for further exploration of molecular signatures in carotid atherosclerosis.

Statin Therapy and the Development of Cerebral Amyloid Angiopathy--A Rodent in Vivo Approach

Background: Cerebral amyloid angiopathy (CAA) is characterized by vascular deposition of amyloid β (Aβ) with a higher incidence of cerebral microbleeds (cMBs) and spontaneous hemorrhage. Since statins are known for their benefit in vascular disease we tested for the effect on CAA. Methods: APP23-transgenic mice received atorvastatin-supplemented food starting at the age of eight months (n = 13), 12 months (n = 7), and 16 months (n = 6), respectively. Controls (n = 16) received standard food only. At 24 months of age cMBs were determined with T2*-weighted 9.4T magnetic resonance imaging and graded by size. Results: Control mice displayed an average of 35 ± 18.5 cMBs (mean ± standard deviation), compared to 29.3 ± 9.8 in mice with eight months (p = 0.49), 24.9 ± 21.3 with 12 months (p = 0.26), and 27.8 ± 15.4 with 16 months of atorvastatin treatment (p = 0.27). In combined analysis treated mice showed lower absolute numbers (27.4 ± 15.6, p = 0.16) compared to controls and also after adjustment for cMB size (p = 0.13). Conclusion: Despite to a non-significant trend towards fewer cMBs our results failed to provide evidence for beneficial effects of long-term atorvastatin treatment in the APP23-transgenic mouse model of CAA. A higher risk for bleeding complications was not observed.

Sodium nitrite attenuates MMP-9 production by endothelial cells and may explain similar effects of atorvastatin

Imbalanced matrix metalloproteinase (MMP) activity promotes cardiovascular alterations that are attenuated by statins. These drugs exert pleiotropic effects independent of cholesterol concentrations, including upregulation of nitric oxide (NO) formation and MMP downregulation. However, statins also increase tissue concentrations of nitrites, which activate new signaling pathways independent of NO. We examined whether atorvastatin attenuates MMP-9 production by human umbilical vein endothelial cells (HUVEC) stimulated with phorbol 12-myristate 13-acetate (PMA) by mechanisms possibly involving increased nitrite, and whether this effect results of NO formation. We also examined whether such an effect is improved by sildenafil, an inhibitor of phosphodiesterase-5 which potentiates NO-induced increases in cyclic GMP. MMP activity and nitrite concentrations were measured by gelatin zymography and ozone-based reductive chemiluminescence, respectively, in the conditioned medium of HUVECs incubated for 24 h with these drugs. Phospho-NFκB p65 concentrations were measured in cell lysate to assess NFκB activation. Atorvastatin attenuated PMA-induced MMP-9 gelatinolytic activity by mechanisms not involving NO, although it increased nitrite concentrations, whereas sildenafil had no effects. Combining both drugs showed no improved responses compared to atorvastatin alone. While sodium nitrite attenuated MMP-9 production by HUVECs, adding hemoglobin (NO scavenger) did not affect the responses to nitrite. Neither atorvastatin nor nitrite inhibited PMA-induced increases in phospho-NFκB p65 concentrations. These findings show that sodium nitrite attenuates MMP-9 production by endothelial cells and may explain similar effects exerted by atorvastatin. With both drugs, the inhibitory effects on MMP-9 production are not dependent on NO formation or on inhibition of NFκB activation. Our findings may help to elucidate important new nitrite-mediated mechanisms by which statins affect imbalanced MMP activity in a variety of cardiovascular disease.

Blockade of Ets-1 attenuates epidermal growth factor-dependent collagen loss in human carotid plaque smooth muscle cells

Although degradation of extracellular matrix by matrix metalloproteinases (MMPs) is thought to be involved in symptomatic (S) carotid plaques in atherosclerosis, the mechanisms of MMP expression are poorly understood. Here, we demonstrate that collagen loss in vascular smooth vessel cells (VSMCs) isolated from S plaques was induced by epidermal growth factor (EGF) through the activation of p38-MAPK and JNK-MAPK pathways. Inhibitors of p38-MAPK and JNK-MAPK signaling pathways downregulated the expression of MMP-1 and MMP-9. In addition, we examined whether v-ets erythroblastosis virus E26 oncogene homologue 1 (Ets-1), an important regulator of different genes, is involved in destabilizing S plaques in patients with carotid stenosis. We demonstrate that EGF induces Ets-1 expression and decreases interstitial and basement membrane collagen in vascular smooth muscle cells (VSMCs) from patients with carotid stenosis. Increased expression of MMP-1 and -9 and decreased collagen mRNA transcripts were also found in Ets-1-overexpressed VSMCs. Transfection with both dominant-negative form of Ets-1 and small interfering RNA blocked EGF-induced MMP-1 and -9 expressions and increased the mRNA transcripts for collagen I (α1) and collagen III (α1) in S compared with asymptomatic (AS) carotid plaques. Inhibitors of p38-MAPK (SB202190) and JNK-MAPK (SP600125) signaling pathways decreased the expression of Ets-1, MMP-1, and MMP-9 and increased collagen type I and III expression in EGF-treated VSMCs. This study provides a mechanistic insight into the role of Ets-1 in the plaque destabilization in patients with carotid stenosis involving p38-MAPK and JNK signaling pathways.

Impact of Cognitive Dysfunction on Survival in Patients With and Without Statin Use Following Carotid Endarterectomy

BACKGROUND:

Early cognitive dysfunction (eCD) is a subtle form of neurological injury observed in ∼25% of carotid endarterectomy (CEA) patients. Statin use is associated with a lower incidence of eCD in asymptomatic patients having CEA.

OBJECTIVE:

To determine whether eCD status is associated with worse long-term survival in patients taking and not taking statins.

METHODS:

This is a post hoc analysis of a prospective observational study of 585 CEA patients. Patients were evaluated with a battery of neuropsychometric tests before and after surgery. Survival was compared for patients with and without eCD stratifying by statin use. At enrollment, 366 patients were on statins and 219 were not. Survival was assessed by using Kaplan-Meier methods and multivariable Cox proportional hazards models.

RESULTS:

Age ≥75 years (P = .003), diabetes mellitus (P &lt; .001), cardiac disease (P = .02), and statin use (P = .014) are significantly associated with survival univariately (P &lt; .05) by use of the log-rank test. By Cox proportional hazards model, eCD status and survival adjusting for univariate factors within statin and nonstatin use groups suggested a significant effect by association of eCD on survival within patients not taking statin (hazard ratio, 1.61; 95% confidence interval, 1.09–2.40; P = .018), and no significant effect of eCD on survival within patients taking statin (hazard ratio, 0.98; 95% confidence interval, 0.59–1.66; P = .95).

CONCLUSION:

eCD is associated with shorter survival in patients not taking statins. This finding validates eCD as an important neurological outcome and suggests that eCD is a surrogate measure for overall health, comorbidity, and vulnerability to neurological insult.

Symptomatic carotid atherosclerotic disease: correlations between plaque composition and ipsilateral stroke risk

BACKGROUND AND PURPOSE

For symptomatic patients with carotid artery stenosis, the risk benefit for surgical intervention may vary among patient groups. Various modalities of plaque imaging have been promoted as potential tools for additional risk stratification, particularly in patients with moderate stenosis. However, it remains uncertain to what extent carotid plaque components predict risk of future ipsilateral ischemic stroke.

METHODS

In 2 large atherosclerotic carotid plaque biobank studies, we related histological characteristics of 1640 carotid plaques with a validated risk model for the prediction of individual 1- and 5-year stroke risk.

RESULTS

No significant heterogeneity between the studies was found. Predicted 5-year stroke risk (top versus bottom quartile) was related to plaque thrombus (odds ratio, 1.42; 95% confidence interval, 1.11-1.89; P=0.02), fibrous content (0.65; 0.49-0.87; P=0.004), macrophage infiltration (1.41; 1.05-1.90; P=0.02), high microvessel density (1.49; 1.05-2.11; P=0.03), and overall plaque instability (1.40; 1.05-1.87; P=0.02). This association was not observed for cap thickness, calcification, intraplaque hemorrhage, or lymphocyte infiltration. Plaques removed within 30 days of most recent symptomatic event were most strongly correlated with predicted stroke risk.

CONCLUSIONS

Features of the vulnerable carotid plaque, including plaque thrombus, low fibrous content, macrophage infiltration, and microvessel density, correlate with predicted stroke risk. This study provides a basis for plaque imaging studies focused on stroke risk stratification.

Effect of simvastatin on MMPs and TIMPs in human brain endothelial cells and experimental stroke

Clinical studies demonstrated favorable effects of statins in stroke beyond lipid-lowering effects. In acute stroke, the disruption of the blood-brain barrier (BBB) is mediated by matrix metalloproteinases (MMPs). A modified MMP metabolism may account for the beneficial effects of statins. Cultured human brain microvascular endothelial cells (BMECs) were pretreated with simvastatin and subjected to oxygen glucose deprivation (OGD). Gene expression and protein secretion of MMP-2 and MMP-9 and the tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 were measured by quantitative real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Simvastatin significantly dampened the expression but not secretion of MMP-2 under OGD. MMP-9 synthesis rate was low and unaffected by simvastatin treatment, while the gene expression and protein secretion of TIMP-1 and TIMP-2 were both strongly induced. Our results provide evidence for a positive effect of simvastatin on the MMP metabolism in human BMECs and experimental stroke mainly by means of the increased expression and secretion of TIMP-1 and TIMP-2.

Statin treatment in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

We aimed to investigate the association of statin treatment with outcomes in patients with acute ischemic stroke.

METHODS

Over a 4.5-year period (starting November 2007), 12 781 patients (mean age, 72·8 ± 12·6 years; 48·6% women) with acute ischemic stroke from 15 hospitals in Schleswig-Holstein, Germany, were enrolled in a population-based study and prospectively evaluated. The primary outcomes were the mortality during hospitalization and the disability (modified Rankin Scale score ≥2) at discharge from hospital. The secondary outcomes were the mortality and disability at three-months after discharge.

RESULTS

A total of 7535 patients (59%) with acute ischemic stroke were treated with statins. During hospitalization (mean, nine-days), the in-hospital mortality rate (4·7%; 95% confidence interval, 4·3-5·1%) was lower in patients treated with statins than in those without statins (2·3% vs. 7·9%, respectively; P < 0·001). At three-months after discharge, the mortality rate (6·9%; 95% confidence interval, 6·4-7·5%) was lower in patients treated with statins than in those without statins (5·0% vs. 10·6%, respectively; P < 0·001). Adjusted logistic regression analysis showed that statin treatment was associated with reduced rates of in-hospital mortality (odds ratio, 0·39; 95% confidence interval, 0·31-0·48; P < 0·001) and three-month mortality (odds ratio, 0.47; 95% confidence interval, 0·34-0·63; P < 0·001). A comparison of the patient groups revealed that patients on statins were likely to have lower disability rates at discharge (59% vs. 67%, respectively; P < 0·001) and after three-months (33% vs. 42%, respectively; P < 0·001) in patients who had survived the stroke.

CONCLUSION

Statin treatment may improve the outcomes in patients with acute ischemic stroke. Further studies are necessary to confirm this finding.

MMP-1 and MMP-9 regulate epidermal growth factor-dependent collagen loss in human carotid plaque smooth muscle cells

Mechanisms underlying the rupture of atherosclerotic plaque, a crucial factor in the development of myocardial infarction and stroke, are not well defined. Here, we examined the role of epidermal growth factor (EGF)‐mediated matrix metalloproteinases (MMP) on the stability of interstitial collagens in vascular smooth muscle cells (VSMCs) isolated from carotid endarterectomy tissues of symptomatic and asymptomatic patients with carotid stenosis. VSMCs isolated from the carotid plaques of both asymptomatic and symptomatic patients were treated with EGF. The MMP‐9 activity was quantified by gelatin zymography and the analysis of mRNA transcripts and protein for MMP‐9, MMP‐1, EGFR and collagen types I, Col I(α1) and collagen type III, Col III(α1) were analyzed by qPCR and immunofluorescence, respectively. The effect of EGF treatment to increase MMP‐9 activity and mRNA transcripts for MMP‐9, MMP‐1, and EGFR and to decrease mRNA transcripts for Col I(α1) and Col III(α1) was threefold to fourfold greater in VSMCs isolated from the carotid plaques of symptomatic than asymptomatic patients. Inhibitors of EGFR (AG1478) and a small molecule inhibitor of MMP‐9 decreased the MMP9 expression and upregulated Col I(α1) and Col III(α1) in EGF‐treated VSMCs of both groups. Additionally, the magnitude in decreased MMP‐9 mRNA and increased Col I(α1) and Col III(α1) due to knockdown of MMP‐9 gene with siRNA in EGF‐treated VSMCs was significantly greater in the symptomatic group than the asymptomatic group. Thus, a selective blockade of both EGFR and MMP‐9 may be a novel strategy and a promising target for stabilizing vulnerable plaques in patients with carotid stenosis.

This report described the underlying mechanisms by which MMP‐1 and MMP‐9 induced by EFGR activation decreases the interstitial collagens and this could result in plaque instability in patients with carotid stenosis. Thus, selective blockade of EGFR and/or MMP‐9 may be a novel strategy and a promising target to stabilize atherosclerotic plaques and thus decreases morbidity and mortality.

The phenotype of infiltrating macrophages influences arteriosclerotic plaque vulnerability in the carotid artery

BACKGROUND

Proinflammatory (M1) macrophages and anti-inflammatory (M2) macrophages have been identified in atherosclerotic plaques. While these macrophages have been speculated to be related to plaque vulnerability, there are limited studies investigating this relationship. Therefore, we examined the association between macrophage phenotype (M1 versus M2) and plaque vulnerability and clinical events.

METHODS

Patients undergoing carotid endarterectomy received an ultrasound of the carotid artery before surgery. Plaques were processed for analysis by immunohistochemistry, Western blotting, and real-time polymerase chain reaction studies. Medical history and clinical data were obtained from medical records.

RESULTS

Patients were divided into 2 groups: those suffering from acute ischemic attack (symptomatic, n = 31) and those that did not present with symptoms (asymptomatic, n = 34). Ultrasound analysis revealed that plaque vulnerability was greater in the symptomatic group (P= .033; Chi-square test). Immunohistochemistry revealed that plaques from the symptomatic group had a greater concentration of M1 macrophages (CD68-, CD11c-positive) while plaques from the asymptomatic group had more M2 macrophages (CD163-positive). This observation was confirmed by Western blotting. Characterization by real-time polymerase chain reaction studies revealed that plaques from the symptomatic group had increased expression of the M1 markers CD68 and CD11c, as well as monocyte chemoattractive protein-1, interleukin-6, and matrix metalloproteinase-9. In addition, more M1 macrophages expressed in unstable plaques were defined by ultrasound analysis, while more M2 macrophages were expressed in stable plaques.

CONCLUSIONS

Our data show that M1 macrophage content of atherosclerotic plaques is associated with clinical incidence of ischemic stroke and increased inflammation or fibrinolysis. We also show the benefits of using ultrasound to evaluate vulnerability in the plaques.

Suppression of oxLDL-induced MMP-9 and EMMPRIN expression by berberine via inhibition of NF-κB activation in human THP-1 macrophages

Upregulation of matrix metalloproteinases (MMPs) and extracellular matrix metalloproteinase inducer (EMMPRIN) by macrophages leads to atherosclerotic plaque rupture by degradation of the extracellular matrix. NF-κB activation regulates many key inflammatory genes linked to atherosclerosis. In the present study, the function of berberine, a natural extract from Rhizoma coptidis, on MMP-9 and EMMPRIN expression, the role of NF-κB activation in oxLDL-stimulated macrophages, and the possible mechanism in which NF-κB activation is involved were investigated. Berberine inhibited the expression of MMP-9 and EMMPRIN at both mRNA and protein levels. The phosphorylation of IκB-α and nuclear translocation of p65 protein were reduced by berberine, suggesting that NF-κB activation was inhibited by berberine in oxLDL-stimulated macrophages. Overall, berberine suppressed the expression of MMP-9 and EMMPRIN by at least reducing partly the activity of NF-κB in oxLDL-induced macrophages.

Current role of biomarkers in carotid disease: a systematic review

BACKGROUND AND PURPOSE

Accumulating evidence suggests that carotid plaque vulnerability can be used as a determinant of ischemic stroke risk stratification and carotid intervention. Novel markers of high-risk carotid plaque in patients are needed.

SUMMARY OF REVIEW

Advances in cellular and molecular pathophysiology, the demand for accurately predicting carotid risk, and choosing the optimal prevention strategy are stimulating great interest in the development of novel surrogate markers. Biomarkers in cardiovascular disease are expected to predict the natural history, clinical outcomes, and the efficacy of disease-modifying interventions. We aimed to review the literature regarding clinical data on novel serum biomarkers related to ischemic cerebrovascular events associated with carotid artery disease. We provide background information on the biomarkers related to all aspects of carotid disease: natural history, carotid intervention strategies for symptomatic and asymptomatic patients, perioperative risk prediction, and their therapeutic implications.

CONCLUSION

At present, heterogeneous data support evidence that biological markers can help existing practices to more accurately assess patients at risk for stroke. Randomized-controlled trials for carotid artery disease and carotid intervention, incorporating biomarkers, are needed.

Plaque rupture is a determinant of vascular events in carotid artery atherosclerotic disease: involvement of matrix metalloproteinases 2 and 9

BACKGROUND AND PURPOSE

Unstable carotid atherosclerotic plaques are characterized by cap rupture, leading to thromboembolism and stroke. Matrix metalloproteinases (MMPs) have been implicated in the progression of atherosclerosis and plaque rupture. The aim of this study was to assess the relationship between the expressions of MMP-2 and MMP-9 and carotid plaque instability.

METHODS

Eighty atherosclerotic plaques were collected from 74 patients undergoing carotid endarterectomy. Clinical information was obtained from each patient, and plaque morphology was examined at the macroscopic and microscopic levels. The immunohistochemical expressions of MMPs were graded using semiquantitative scales.

RESULTS

Macroscopic ulceration (84.6% versus 63.4%, p=0.042) and microscopic cap rupture (79.5% versus 51.2%, p=0.010) were more common in symptomatic than in asymptomatic patients. Immunoreactivities of MMP-2 and MMP-9 were increased in 40 and 36 atheromatous plaques, respectively. Macroscopic ulceration was strongly correlated with the expressions of MMP-2 (p<0.001) and MMP-9 (p=0.001). There were significant correlations between increased MMP-2 expression and cap rupture (p=0.002), intraplaque hemorrhage (p=0.039), and a thin fibrous cap (p=0.002), and between increased MMP-9 expression and cap rupture (p=0.010) and a large lipid core (p=0.013).

CONCLUSIONS

Plaque rupture was significantly associated with the development of vascular events in carotid atherosclerotic disease. MMP-2 and MMP-9 are strongly correlated with plaque instability.

Artemisinin inhibits extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinase-9 expression via a protein kinase Cδ/p38/extracellular signal-regulated kinase pathway in phorbol myristate acetate-induced THP-1 macrophages

1. Overexpression of extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinases (MMPs) by monocytes/macrophages has been proposed to play a significant role in atherosclerotic plaque progression and rupture. The aim of the present study was to explore whether artemisinin, a natural extract from Artemisia annua, could decrease EMMPRIN and MMP-9 expression in phorbol myristate acetate (PMA)-induced macrophages by regulating the protein kinase (PK) Cδ/c-Jun N-terminal kinase (JNK)/p38/extracellular signal-regulated kinase (ERK) pathway. 2. Human monocytic THP-1 cells were pretreated with 20-80 μg/mL artemisinin for 4 h or 1-10 μmol/L rottlerin for 1 h prior to stimulation with PMA (100 nmol/L) for another 48 h. Cells were collected to analyse the induction of EMMPRIN and MMP-9. Upstream pathway analysis using the PKCδ inhibitor rottlerin detected activation of the PKCδ/JNK/p38/ERK pathway. 3. Artemisinin (20-80 μg/mL) significantly inhibited the induction of EMMPRIN and MMP-9 at both the transcriptional and translational levels in a dose-dependent manner in PMA-induced macrophages. In addition, artemisinin (20-80 μg/mL) strongly blocked PKCδ/JNK/p38/ERK MAPK phosphorylation. The PKCδ inhibitor rottlerin (1-10 μmol/L) also significantly inhibited JNK/p38/ERK phosphorylation and decreased EMMPRIN and MMP-9 mRNA and protein expression. 4. The results of the present study suggest that artemisinin inhibits EMMPRIN and MMP-9 expression and activity by suppressing the PKCδ/ERK/p38 cascade in PMA-induced macrophages.

Assessment of MMP-9, TIMP-1, and COX-2 in normal tissue and in advanced symptomatic and asymptomatic carotid plaques

Background

Mature carotid plaques are complex structures, and their histological classification is challenging. The carotid plaques of asymptomatic and symptomatic patients could exhibit identical histological components.

Objectives

To investigate whether matrix metalloproteinase 9 (MMP-9), tissue inhibitor of MMP (TIMP), and cyclooxygenase-2 (COX-2) have different expression levels in advanced symptomatic carotid plaques, asymptomatic carotid plaques, and normal tissue.

Methods

Thirty patients admitted for carotid endarterectomy were selected. Each patient was assigned preoperatively to one of two groups: group I consisted of symptomatic patients (n = 16, 12 males, mean age 66.7 ± 6.8 years), and group II consisted of asymptomatic patients (n = 14, 8 males, mean age 67.6 ± 6.81 years). Nine normal carotid arteries were used as control. Tissue specimens were analyzed for fibromuscular, lipid and calcium contents. The expressions of MMP-9, TIMP-1 and COX-2 in each plaque were quantified.

Results

Fifty-eight percent of all carotid plaques were classified as Type VI according to the American Heart Association Committee on Vascular Lesions. The control carotid arteries all were classified as Type III. The median percentage of fibromuscular tissue was significantly greater in group II compared to group I (p < 0.05). The median percentage of lipid tissue had a tendency to be greater in group I than in group II (p = 0.057). The percentages of calcification were similar among the two groups. MMP-9 protein expression levels were significantly higher in group II and in the control group when compared with group I (p < 0.001). TIMP-1 expression levels were significantly higher in the control group and in group II when compared to group I, with statistical difference between control group and group I (p = 0.010). COX-2 expression levels did not differ among groups. There was no statistical correlation between MMP-9, COX-2, and TIMP-1 levels and fibrous tissue.

Conclusions

MMP-9 and TIMP-1 are present in all stages of atherosclerotic plaque progression, from normal tissue to advanced lesions. When sections of a plaque are analyzed without preselection, MMP-9 concentration is higher in normal tissues and asymptomatic surgical specimens than in symptomatic specimens, and TIMP-1 concentration is higher in normal tissue than in symptomatic specimens.

Statins: multiple neuroprotective mechanisms in neurodegenerative diseases

Statins have been widely used for the treatment of a variety of conditions beyond their original role in lowering cholesterol. Since statins have relatively few side effects, they have been recognized as useful medicine to ameliorate neurodegenerative disorders. Current studies on the applications of statins have demonstrated their neuroprotective and clinical significance among neurodegenerative diseases like cerebral ischemic stroke, vascular dementia, Alzheimer's disease, and Parkinson's disease, though the neuroprotective mechanisms are not completely understood. This review will discuss recent development in the use of statins in slowing down the progression of these neurodegenerative diseases. It will summarize the potential mechanisms for statin-mediated neuroprotective effects in neurodegenerative diseases. In detail, this review discuss the roles of statins in lowering cholesterol, reducing reactive oxygen species, impairing β-amyloid production and serum apolipoprotein E levels, enhancing the levels of endothelial nitric oxide synthase and cerebral blood flow, and modulating cognitive related receptors and matrix metalloproteases. Finally, different alterations of various receptors in brain regions following statin treatment and their correlations with cognitive dysfunction in Parkinson's disease will also be reviewed, as well as the potential for therapy in ameliorating the progression of Parkinson's disease. This article is part of a Special Issue entitled "Interaction between repair, disease, & inflammation."

Celecoxib combined with atorvastatin prevents progression of atherosclerosis

BACKGROUND

Increased expression of cyclooxygenase (COX-2) contributes to atherosclerosis. Recent studies suggest that COX-2 inhibitors prevent early plaque development but their effects on established lesions are less clear, while the statins promote plaque stability. The purpose of this study is to investigate whether administering a combination of a COX-2 inhibitor with a statin drug alters plaque progression in apo E-/- mice.

MATERIALS AND METHODS

Apo E-/- mice were fed a Western diet from 6 to 26 wk of age. At 26 wk, the Western diets supplemented with atorvastatin, celecoxib, or atorvastatin plus celecoxib were given for an additional 12 wk.

RESULTS

When the mice were 38 wk of age, the total area occupied by the atherosclerotic lesion was 53% less in the mice fed the combination of atorvastatin + celecoxib P ≤ 0.05) than that of the apo E-/- mice fed the Western diet alone, atorvastatin alone, or celecoxib alone. The decreased extent of atherosclerosis observed in the apo E-/- mice fed the combination of drugs was associated with reduced levels of prostaglandin (PG) E(2,) decreased protein expression of metalloproteinase (MMP)-9, macrophage chemotactic protein (MCP-1), and COX 2, and decreased staining for MMP-9, F4-80 (a marker for macrophages), and vascular cell adhesion molecule (VCAM).

CONCLUSION

This study indicates that using statins with a COX-2 inhibitor reduced the extent of atherosclerosis and inflammatory/cell adhesion molecule levels in the apo E-/- mouse model.

Differences in carotid plaque content of macrophages, T cells and MMP-9 between patients with embolic and hemodynamic cerebral ischemia due to symptomatic carotid stenosis

BACKGROUND

Cerebral ischemia in patients with carotid artery atherosclerosis is most often caused by thromboembolism, while hemodynamic stroke mechanism is rare. Differences in plaque inflammation according to stroke mechanism are an understudied issue. The purpose of this pilot study was to compare carotid plaque inflammation in patients with thromboembolic and hemodynamic cerebral ischemia.

METHODS

We included 6 patients with hemodynamic and 27 with embolic cerebral ischemia who had carotid endarterectomy (CEA). We compared plaque morphology markers (macrophages, T cells, MMP-9, plaque rupture, surface thrombus, intraplaque hemorrhage, lipid core) between patients with hemodynamic and embolic cerebral ischemia and assessed vascular events and deaths during the first year post CEA.

RESULTS

Compared to patients with hemodynamic mechanism, those with embolic mechanism showed a higher median (interquartile range) content of T cells/mm(2) [49.66 (21.26-71.39) vs. 10.28 (7.05-13.87); P=0.0005] and higher median total percentages of macrophage area [2.81% (1.69-4.09) vs. 0.99% (0.57-1.50); P=0.003] and MMP-9 area [0.63% (0.42-1.01) vs. 0.25% (0.05-0.45); P=0.007]. Signs of plaque instability such as plaque rupture, surface thrombus and intraplaque hemorrhage showed a tendency to be more pronounced in patients with thromboembolism. The incidences of vascular events and the survival rates in the first year after CEA were similar in the two groups.

CONCLUSIONS

Major differences in plaques related to stroke mechanism were found in patients with symptomatic carotid stenosis. However, further investigations are necessary to validate our results. Identification of stroke mechanism may improve risk stratification and could help to identify the most suitable secondary stroke prevention strategy.

The effect of statin therapy on the progression of carotid artery stenosis in relation to stenosis severity

OBJECTIVES

To examine the effect of early statin treatment on progression of arteriosclerosis in internal carotid arteries (ICA); to compare the progression of arteriosclerosis in ICA of patients treated with a statin to the progression seen in drug-naïve patients.

PATIENTS AND METHODS

We performed repetitive Doppler scans of 363 carotid arteries with ICA stenosis > or =40% in 254 patients over time. Information on statin therapy and other risk factors for stroke were correlated with the annual change in degree of ICA stenosis.

RESULTS

In statin-treated patients, 19% of ICA stenosis showed a progression while 74% showed a regression of stenosis. In statin-naïve patients, 63% of stenotic arteries showed a progression, while a reduction could be observed in 28%. Decrease of ICA stenosis was most accentuated in patients with a mild stenosis and was independent of serum cholesterol levels.

CONCLUSION

Treatment with statins already in early stages of ICA stenosis might delay the progression and even reverse the degree of stenosis.

Serum leptin levels in patients undergoing carotid endarterectomy: a pilot study

INTRODUCTION

Elevated serum leptin levels are associated with cardiovascular events. We investigated the role of serum leptin in patients undergoing carotid endarterectomy (CEA).

METHODS

A total of 74 patients (55 men; 38 symptomatic and 36 asymptomatic; mean age 66.9 +/- 8.2 years) undergoing CEA for >70% carotid artery stenosis were enrolled.

RESULTS

Serum leptin levels were lower in symptomatic compared with asymptomatic patients (7.1 +/- 1.3 vs 14.4 +/- 4.7 ng/dL; P < .001). Interleukin-6 (IL-6) levels were higher in symptomatic compared with asymptomatic patients (4.3 +/- 1.7 vs 3.3 +/- 1.1 pg/dL; P = .017). Symptomatic patients had more intense macrophage accumulation (0.7% +/- 0.1% vs 0.3% +/- 0.1%; P < .001). Serum leptin and serum IL-6 levels were independently associated with the presence of symptoms in multivariate analysis.

CONCLUSION

Serum leptin levels were decreased in symptomatic carotid artery disease. This finding requires further investigation in larger studies.

Atherosclerotic plaque stability--what determines the fate of a plaque?

Although the understanding of the underlying pathology of atherosclerosis has improved in recent years, the disease is still the main cause of death globally. Current evidence has implicated the role of inflammation in atherogenesis and plaque destabilization. Thus, inflammatory cytokines may attenuate interstitial collagen synthesis, increase matrix degradation, and promote apoptosis in several atheroma-associated cell types, and all these cellular events may enhance plaque vulnerability. Several cell types found within the lesion (ie, monocyte/macrophages, T cells, mast cells, platelets) contribute to this immune-mediated plaque destabilization, and a better understanding of these processes is a prerequisite for the development of new treatment strategies in these individuals. Such knowledge could also facilitate a better identification of high-risk individuals. In the present study, these issues will be discussed in more detail, particularly focusing on the interactions between matrix degradation, apoptotic, and inflammatory processes in plaque destabilization.