Inflammation in high-grade carotid stenosis: a possible role for macrophages and T cells in plaque destabilization

Molecular Pathways of Vulnerable Carotid Plaques at Risk of Ischemic Stroke: A Narrative Review

The concept of vulnerable carotid plaques is pivotal in understanding the pathophysiology of ischemic stroke secondary to large-artery atherosclerosis. In macroscopic evaluation, vulnerable plaques are characterized by one or more of the following features: microcalcification; neovascularization; lipid-rich necrotic cores (LRNCs); intraplaque hemorrhage (IPH); thin fibrous caps; plaque surface ulceration; huge dimensions, suggesting stenosis; and plaque rupture. Recognizing these macroscopic characteristics is crucial for estimating the risk of cerebrovascular events, also in the case of non-significant (less than 50%) stenosis. Inflammatory biomarkers, such as cytokines and adhesion molecules, lipid-related markers like oxidized low-density lipoprotein (LDL), and proteolytic enzymes capable of degrading extracellular matrix components are among the key molecules that are scrutinized for their associative roles in plaque instability. Through their quantification and evaluation, these biomarkers reveal intricate molecular cross-talk governing plaque inflammation, rupture potential, and thrombogenicity. The current evidence demonstrates that plaque vulnerability phenotypes are multiple and heterogeneous and are associated with many highly complex molecular pathways that determine the activation of an immune-mediated cascade that culminates in thromboinflammation. This narrative review provides a comprehensive analysis of the current knowledge on molecular biomarkers expressed by symptomatic carotid plaques. It explores the association of these biomarkers with the structural and compositional attributes that characterize vulnerable plaques.

Vascular Imaging Techniques to Diagnose and Monitor Patients with Takayasu Arteritis: A Review of the Literature

Takayasu arteritis (TA) is a large vessel vasculitis that causes stenosis, occlusion, and sometimes the aneurysm of the aorta and its major branches. TA often occurs in young women, and because the symptoms are not obvious in the early stages of the disease, diagnosis is difficult and often delayed. In approximately 10% to 20% of patients, TA is reportedly complicated by ischemic stroke or transient ischemic attack. It is important to diagnose TA early and provide appropriate treatment to prevent complications from stroke. Diagnostic imaging techniques to visualize arterial stenosis are widely used in clinical practice. Even if no signs of cerebrovascular events are present at the time of the most recent evaluation of patients with TA, follow-up vascular imaging is important to monitor disease progression and changes in the cerebrovascular risk. However, the optimal imaging technique for monitoring of TA has not been established. Therefore, the purpose of this review is to describe newly available evidence on the usefulness of conventional imaging modalities (digital subtraction angiography, computed tomography angiography, magnetic resonance imaging/angiography, duplex ultrasound, and positron emission tomography) and novel imaging modalities (optical coherence tomography, infrared thermography, contrast-enhanced ultrasonography, and superb microvascular imaging) in the diagnosis and monitoring of TA.

Plasma nesfatin-1 and DDP-4 levels in patients with coronary artery disease: Kozani study

Background

Nesfatin-1, a novel adipokine and dipeptidyl peptidase-4 (DPP4), a mam malian serine protease, are potent factors of atherosclerosis. In the present cross-sectional study, we investigated whether the plasma nesfatin-1 and DPP4 is associated with the prevalence and severity of coronary artery disease (CAD) with and without diabetes mellitus (DM).

Methods

We consecutively enrolled a total of 240 patients with significant CAD (previous revascularization or angiographically-proven coronary artery stenosis > 50%) presented with either unstable angina (UA, N = 76) or stable chronic CAD (SCAD, N = 165). 85 patients with at least 2 classical cardiovascular risk factors but without significant CAD served as controls. The severity of CAD was assessed using coronary angiography by the Gensini score. Clinical parameters, glycemic and lipid profile, high-sensitivity CRP (hsCRP), nesfatin-1 and DPP4 levels were assayed.

Results

No differences were found for age, sex, hypertension and diabetes distribution between groups. Low nesfatin-1 levels were found in both CAD groups (UA & SCAD) with respect to controls. The difference between UA and SCAD groups was marginally non-significant. There was a significant increase of DPP4 along UA to SCAD and control groups. Differences between groups remained unchanged in non-diabetic participants. Nesfatin-1 significantly correlated to hsCRP (r = − 0.287, p = 0.036), HOMA-IR (r = − 0.587, p = 0.007) and hyperlipidemia (r = − 0.331, p = 0.034). DPP4 was significantly associated with hs-CRP (r = 0.353 p < 0.001) and FPG (r = 0.202, p = 0.020) in univariate analysis, but those correlations were lost in multiple regression analysis. There was a negative correlation between nesfatin-1 and the severity of CAD, quantified by the Gensini score (r = − 0.511, p < 0.001), but no association was found for DPP4.

Conclusions

Serum DPP4 levels are increased in patients with CAD, while serum nesfatin-1 levels have a negative association with both the incidence and the severity of CAD. These results are independent of the presence of diabetes mellitus. In addition, both peptides have a strong association with hsCRP.

Trial registration ClinicalTrials.gov Identifier: NCT00306176

Detection of Carotid Artery Stenosis with Intraplaque Hemorrhage and Neovascularization Using a Scanning Interferometer

Carotid artery stenosis (CAS) is a major cause of stroke or transient ischemic attack (TIA, mini-stroke) in the United States. Carotid endarterectomy (CEA), a surgical procedure, is used to treat CAS. According to the American Heart Association, 1 out of 5 patients underwent CEA inappropriately, which was most commonly due to apparent overestimation of stenosis severity, and half had uncertain indicators. The current imaging modalities are limited in providing critical information on carotid arterial plaque content, extent, and biology. To circumvent these limitations, we developed a sensing interferometer (SI) imaging system to assess vulnerable carotid plaques noninvasively to detect stenosis, neovascularization, and intraplaque hemorrhage (IPH). We have custom-built a SI prototype and its peripheral systems with back-mode-projection capability. We detected stenosis, neo-vessels, and IPH through SI imaging system in in vivo mice carotid atherosclerotic plaques and further verified the same plaques ex vivo through a histology scope, CRi Maestro, and histological analysis.

Macrophage-Hypoxia-Inducible Factor-1α Signaling in Carotid Artery Stenosis

Macrophages play crucial and diverse roles in the pathogenesis of inflammatory vascular diseases. Macrophages are the principal innate immune cells recruited to arterial walls to govern vascular homeostasis by modulating the proliferation of vascular smooth muscle cells, the reorganization of extracellular matrix components, the elimination of dead cells, and the restoration of normal blood flow. However, chronic sterile inflammation within the arterial walls draws inflammatory macrophages into intimal/neointimal regions that may contribute to disease pathogenesis. In this context, the accumulation and aberrant activation of macrophages in the neointimal regions govern the progression of inflammatory arterial wall diseases. Herein, we report that myeloid-hypoxia-inducible factor-1α (HIF1α) deficiency attenuates vascular smooth muscle cells and macrophage abundance in stenotic arteries and abrogates carotid neointima formation in vivo. The integrated transcriptomics, Gene Set Enrichment Analysis, metabolomics, and target gene evaluation showed that HIF1α represses oxidative phosphorylation, tricarboxylic acid cycle, fatty acid metabolism, and c-MYC signaling pathways while promoting inflammatory, glycolytic, hypoxia response gene expression in stenotic artery macrophages. At the molecular level, proinflammatory agents utilized STAT3 signaling pathways to elevate HIF1α expression in macrophages. Collectively, this study uncovers that macrophage-HIF1α deficiency restrains the pathogenesis of carotid artery stenosis by rewiring inflammatory and metabolic signaling pathways in macrophages.

Superb Microvascular Imaging Ultrasound for Cervical Carotid Artery Stenosis for Prediction of the Development of Microembolic Signals on Transcranial Doppler during Carotid Exposure in Endarterectomy

Introduction

During exposure of the carotid arteries, embolism from the surgical site is recognized as a primary cause of neurological deficits or new cerebral ischemic lesions following carotid endarterectomy (CEA), and associations have been reported between histological neovascularization in the carotid plaque and both plaque vulnerability and the development of artery-to-artery embolism. Superb microvascular imaging (SMI) enables accurate visualization of neovessels in the carotid plaque without the use of intravenous contrast. This study aimed to determine whether preoperative SMI ultrasound for cervical carotid artery stenosis predicts the development of microembolic signals (MES) on transcranial Doppler (TCD) during exposure of the carotid arteries in CEA.

Methods

Preoperative cervical carotid artery SMI ultrasound followed by CEA under TCD monitoring of MES in the ipsilateral middle cerebral artery was conducted in 70 patients previously diagnosed with internal carotid artery stenosis (defined as ≥70%). First, observers visually identified intraplaque microvascular flow (IMVF) signals as moving enhancements located near the surface of the carotid plaque within the plaque on SMI ultrasonograms. Next, regions of interest (ROI) were manually placed at the identified IMVF signals (or at arbitrary places within the plaque when no IMVF signals were identified within the carotid plaque) and the carotid lumen, and time-intensity curves of the IMVF signal and lumen ROI were generated. Ten heartbeat cycles of both time-intensity curves were segmented into each heartbeat cycle based on gated electrocardiogram findings and averaged with respect to the IMVF signal and lumen ROI. The difference between the maximum and minimum intensities (ID) was calculated based on the averaged IMVF signal (ID_IMVF) and lumen (ID_l) curves. Finally, the ratio of ID_IMVF to ID_l was calculated.

Results

MES during exposure of the carotid arteries were detected in 17 patients (24%). The incidence of identification of IMVF signals was significantly greater in patients with MES (94%) than in those without (57%; p = 0.0067). The ID_IMVF/ID_l ratio was significantly greater in patients with MES (0.108 ± 0.120) than in those without (0.017 ± 0.042; p < 0.0001). The specificity and positive predictive value for the ID_IMVF/ID_l ratio for prediction of the development of MES were significantly higher than those for the identification of IMVF signals. Logistic regression analysis revealed that only the ID_IMVF/ID_l ratio was significantly associated with the development of MES (95% CI 101.1–3,628.9; p = 0.0048).

Conclusion

Preoperative cervical carotid artery SMI ultrasound predicts the development of MES on TCD during exposure of the carotid arteries in CEA.

Increased serum chemerin levels associated with carotid intima-media thickness

BACKGROUND

Elevated levels of chemerin can predict future ischemic cerebrovascular disease. Although chemerin is thought to play a role in atherosclerotic inflammation, whether circulating chemerin levels are associated with the severity of atherosclerosis remains to be determined.

OBJECTIVES

Through the use of carotid Doppler ultrasonography, our aim in this study was to investigate the relationships of serum chemerin levels with carotid intima-media thickness (CIMT) as an indicator of generalized atherosclerosis.

METHODS

This study compared 40 patients with ischemic stroke and 40 healthy subjects. Measurements were made at end-diastole using color Doppler ultrasonography (CDUS) after a 5-min rest interval in a quiet and dark room. CIMT was defined as the distance between the innermost edge of the luminal echo to the innermost edge of the media/adventitia echo. CIMT was measured in the posterior wall of both common carotid arteries within 1 cm proximally to the bulbus. Three measurements were made on both sides and the average measurement was taken as the CIMT. Serum chemerin levels were determined in all patients and healthy subjects.

RESULTS

Serum chemerin levels were significantly higher in the patient group than in the control group (p=0.004). Serum chemerin levels were positively correlated with CIMT (p<0.05). There was a significant difference between the groups with regard to CIMT (p<0.001).

CONCLUSION

Elevated serum chemerin levels appear to be associated with CIMT, thus suggesting that a link exists between chemerin and atherosclerotic ischemic cerebrovascular disease.

Inter-reader agreement of 18F-FDG PET/CT for the quantification of carotid artery plaque inflammation

Introduction

A significant proportion of ischemic strokes are caused by emboli from unstable atherosclerotic carotid artery plaques. Inflammation is a key feature of plaque instability. Positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-(¹⁸F)-fluoro-D-glucose (¹⁸F-FDG) is a promising technique to quantify plaque inflammation, but a consensus on the methodology has not been established. High inter-reader agreement is essential if ¹⁸F-FDG PET/CT is to be used as a clinical tool for the assessment of unstable plaques and stroke risk.

Methods

We assessed the inter-reader variability of different methods for quantification of ¹⁸F-FDG uptake in 43 patients with carotid artery stenosis ≥70%. Two independent readers delineated the plaque and collected maximum standardized uptake value (SUV_max) from all axial PET slices containing the atherosclerotic plaque.

Results

Uptake values with and without background correction were calculated and intraclass correlation coefficients were highest for uncorrected uptake values (0.97–0.98) followed by those background corrected by subtraction (0.89–0.94) and lowest for those background corrected by division (0.74–0.79).

Conclusion

Quantification methods without background correction have the highest inter-reader agreement for ¹⁸F-FDG PET of carotid artery plaque inflammation. The use of the single highest uptake value (max SUV_max) from the plaque will facilitate the method’s clinical utility in stroke prevention.

Serum uric acid in asymptomatic adults is weakly associated with carotid artery FDG uptake but not intima-media thickness

BACKGROUND

This study investigated the association of serum uric acid (UA) with carotid fluoro-2-deoxyglucose (FDG) uptake as a marker of inflammatory atherosclerosis.

METHODS AND RESULTS

In this cross-sectional retrospective study of 970 otherwise healthy adults, subjects in the greater serum UA quartiles had higher triglyceride (P < .001), lower high-density lipoprotein cholesterol (P < .05), and lower estimated GFR (P < .001). Mean and maximum Target-to-background ratios (TBRs) of carotid FDG uptake measured by positron emission tomography were significantly increased across greater serum UA quartiles (1.35 and 1.57 for Q1, 1.38 and 1.60 for Q2, 1.39 and 1.62 for Q3, and 1.39 and 1.61 for Q4; P = .001 and < .001). Carotid intima-media thickness was not different. Serum UA showed weak but significant correlations with estimated GFR (P < .001), and with mean (P < .001) and maximum carotid TBR (P = .004). Serum UA correlated with mean TBR in male (P = .008) and female subjects (P = .011), in high (≥ 70; P = .015) and low estimated GFR (< 70; P = .035), and in normotensive (P = .001) but not in hypertensive subjects.

CONCLUSIONS

Elevated serum UA in asymptomatic adults is associated with increased carotid FDG uptake, which suggests a potential role of UA in carotid inflammatory atherosclerosis.

Association of peripheral neutrophil count with intracranial atherosclerotic stenosis

BACKGROUND

Inflammation plays an important role in atherosclerosis but the contribution of neutrophils to this process is unclear. We sought to assess whether neutrophil count is associated with intracranial atherosclerotic stenosis (ICAS).

METHODS

A total of 2847 individuals were included in our study, including 1363 with acute ischemic stroke and 1484 normal controls without stroke. The presence of ICAS was confirmed by magnetic resonance angiography. The association between neutrophil count and ICAS was evaluated by multivariable logistic regression analysis.

RESULTS

Among 2847 individuals included in this study, individuals with ICAS had higher neutrophil counts than those without ICAS in groups with and without stroke (P <  0.0001 for stroke group, P = 0.0097 for group without stroke). The multivariable logistic regression analysis showed that the third and fourth quartiles were independent predictors of ICAS in all the subjects (Q3: OR 1.81, 95% CI 1.39-2.37, Q4: OR 2.29, 95% CI 1.70-3.10) and patients in the fourth quartile had a higher risk for the occurrence of ICAS in stroke group (Q4: OR 2.82, 95% CI 1.79-4.48). However, there was no significant association between neutrophil count and ICAS in the group without stroke.

CONCLUSIONS

The levels of circulating neutrophils were associated with the presence of ICAS. Our findings suggest that neutrophils may play a role in the pathogenesis of stroke related to ICAS and emphasize the need to develop proper strategies to control neutrophil response for the treatment of ICAS.

Should vascular wall 18F-FDG uptake be adjusted for the extent of atherosclerotic burden?

Vascular wall ¹⁸F-FDG uptake is often used as a surrogate marker of atherosclerotic plaque inflammation. A potential caveat is that vascular wall ¹⁸F-FDG uptake is higher simply because more atherosclerosis is present. To determine if the degree of inflammation is high or low relative to the extent of atherosclerosis, vascular wall ¹⁸F-FDG uptake may require statistical adjustment for a non-inflammatory marker reflecting the extent of atherosclerosis, e.g. calcification. Adjustments is probably needed if (1) vascular wall ¹⁸F-FDG uptake correlates sufficiently strongly with arterial calcification and (2) adjustment for extent of calcification affects determinants of vascular ¹⁸F-FDG uptake. This study addresses these questions. ¹⁸F-FDG PET/low-dose-CT scans of 99 patients were used. Cardiovascular risk factors were assessed and PET/CT scans were analysed for standardized ¹⁸F-FDG uptake values and calcification. ANOVA was used to establish the association between vascular ¹⁸F-FDG uptake and calcification. Multiple linear regression (with and without calcification as independent variable) was used to show whether determinants of vascular ¹⁸F-FDG uptake were affected by the degree of calcification. ¹⁸F-FDG uptake was related to increased calcification in the aortic arch, descending and abdominal aorta. However, ¹⁸F-FDG uptake showed considerable overlap between categories of calcification. Age and body mass index were main determinants of vascular ¹⁸F-FDG uptake. In multiple regression analyses, most standardized beta coefficients of these determinants were not affected by adjustment for the degree of calcification. Although vascular ¹⁸F-FDG uptake is related to total atherosclerotic burden, as reflected by vascular calcification, the association is weak and unlikely to affect the identification of determinants of atherosclerotic inflammation implicating no need for adjustment in future studies.

Cell-mediated immune response associated with Chlamydia pneumoniae infection in atherosclerotic patients

BACKGROUND

Chlamydia pneumoniae is an obligate intracellular bacterium that activates cell mediated immune responses; several investigations have demonstrated its strong implication in atherosclerosis.

OBJECTIVES

The main objective of our study was to explore the cell-mediated immune response to C. pneumoniae infection in patients with atherosclerosis by evaluating CD14, CD8 and CD4 expression.

METHODS

This investigation involved a total of 27 patients with atherosclerosis and 32 controls, among patients recruited to evaluate the association of C. pneumoniae with atherosclerosis. C. pneumoniae DNA was detected in PBMCs by nested PCR as described in our previous studies. CD4, CD8 and CD14 expression was measured by flow cytometry and data analysis was performed using FlowJo software.

RESULTS

The results revealed an increase in MFI expression of CD4, CD8 and CD14 in Cpn DNA+ subjects among both patients and healthy subject controls (CD4 Cpn DNA⁺ = 829.11 vs. CD4 Cpn DNA^- = 571.14; CD8 Cpn DNA⁺ = 1562 vs. CD8 Cpn DNA^- = 699; CD14 Cpn DNA⁺ = 1513.83 vs. CD14 Cpn DNA^- = 1170.70), with a statistically significant difference (p < 0.05). Furthermore, the comparison of CD4, CD8 and CD14 expression between Cpn DNA+ patients and Cpn DNA+ healthy subject controls showed a statistically significant increase in expression in the former group (p < 0.05).

CONCLUSION

These data provide incentive to further explore the role of C. pneumoniae in stimulating and changing mechanisms of the cell-mediated immune response induced by C. pneumoniae antigens. This may alter immune cell-mediated responses via increased expression of CD4, CD8 and CD14 during inflammation and the development of thrombosis, leading to fatal atherosclerosis.

18F-FDG PET/CT for the quantification of inflammation in large carotid artery plaques

BACKGROUND

There is currently no consensus on the methodology for quantification of 18F-FDG uptake in inflammation in atherosclerosis. In this study, we explore different methods for quantification of 18F-FDG uptake in carotid atherosclerotic plaques and correlate the uptake values to histological assessments of inflammation.

METHODS AND RESULTS

Forty-four patients with atherosclerotic stenosis ≥70% of the internal carotid artery underwent 18F-FDG PET/CT. Maximum standardized uptake values (SUVmax) from all plaque-containing slices were collected. SUVmax for the single highest and the mean of multiple slices with and without blood background correction (by subtraction (cSUV) or by division (target-to-background ratio (TBR)) were calculated. Following endarterectomy 30 plaques were assessed histologically. The length of the plaques at CT was 6-32 mm. The 18F-FDG uptake in the plaques was 1.15-2.66 for uncorrected SUVs, 1.16-3.19 for TBRs, and 0.20-1.79 for cSUVs. There were significant correlations between the different uptake values (r = 0.57-0.99, P < 0.001). Methods with and without blood background correction showed similar, moderate correlations to the amount of inflammation assessed at histology (r = 0.44-0.59, P < 0.02).

CONCLUSIONS

In large stenotic carotid plaques, 18F-FDG uptake reflects the inflammatory status as assessed at histology. Increasing number of PET slices or background correction did not change the correlation.

Nesfatin-1: A novel regulatory peptide associated with acute myocardial infarction and Mediterranean diet

We evaluated the relationship between nesfatin-1 and acute myocardial infarction (AMI) and Mediterranean diet scores. 67 patients with AMI and 33 patients with normal coronary arteries (control group) were included in the study. The patients with AMI were divided into 2 groups based on low (<32) (n = 33) and high values of the synergy between percutaneous coronary intervention with Taxus and cardiac surgery (SYNTAX) scores (≥34) (n = 35). Mediterranean diet score, serum nesfatin-1 concentrations and all other data were compared between the groups. Serum nesfatin-1 concentrations were significantly lower in 67 AMI patients (both the high and low SYNTAX groups) than in the control group (p < 0.001). Moreover, serum nesfatin-1 concentrations were lower in the high SYNTAX group than those in the low SYNTAX group (p < 0.001). There were positive correlations between the serum nesfatin-1 concentrations and Mediterranean diet scores in both the AMI patients and the control subjects, and there was a negative correlation between the serum nesfatin-1 concentrations and SYNTAX scores in the AMI patients. This study has shown that serum nesfatin-1 concentrations are closely related to the severity of AMI and Mediterranean diet scores.

Helicobacter pylori infection combined with non-alcoholic fatty liver disease increase the risk of atherosclerosis: Focus in carotid artery plaque

Atherosclerosis has severe consequences on human health. Carotid artery plaques are a condition typically caused by atherosclerosis. Previous studies showed that nonalcoholic fatty liver disease (NAFLD) and Helicobacter pylori (H pylori) are risks factors for carotid artery plaque formation. We hypothesize that the combination of NAFLD with H pylori infection increases the risk of carotid artery plaque formation.A total of 4669 subjects aged > 40 years who underwent routine health checkups between January 2006 and December 2015 were retrospectively reviewed. A serial examination, including abdominal ultrasound, carotid artery ultrasound and esophago-gastroduodenoscopy (EGD), and biopsy urease testing, was conducted.In total, 2402 subjects were enrolled. There were no differences in H pylori infection status among patients with or without NAFLD. There was a trend of more participants with both NAFLD and H pylori infection (number [N]=583) presenting carotid artery plaque (N = 187,32.08%) than participants without NAFLD and H pylori infection (N = 589) who presented plaque formation (N = 106, 18.00%). Participants who had both H pylori infection and NAFLD had the highest risk of any carotid artery plaque (odds ratio [OR], 1.93; 95% confidence interval [CI], 1.413-2.636) based on a multivariate logistic regression analysis. This analysis also showed that age >60 years, male sex, low-density lipoprotein (LDL) >130 mg/dL, and H pylori infection were independent risk factors for concomitant NAFLD and carotid artery plaque formation.The combination of H pylori infection and NAFLD increases carotid artery plaque formation. H pylori eradication and NAFLD control may be warranted to prevent carotid artery plaque formation.

High neutrophil to lymphocyte ratios predict intracranial atherosclerosis in a healthy population

BACKGROUND AND AIMS

Although atherosclerosis has been shown to be an inflammatory disease, intracranial atherosclerosis (ICAS) has not been well addressed. The purpose of this study was to evaluate the relationship between the neutrophil to lymphocyte ratio (NLR) and the presence of ICAS lesions in a generally healthy population.

METHODS

A consecutive series of subjects, who voluntarily visited for health check-ups between January 2006 and December 2013, were selected. Brain magnetic resonance imaging, brain magnetic angiography (MRA), and blood cell count data were assessed. ICAS was defined as an occlusion or more than 50% stenosis of intracranial vessels, as observed on brain MRA images. NLR was calculated based on absolute neutrophil and lymphocyte counts.

RESULTS

A total of 2842 subjects were evaluated, and 76 ICAS cases were found. The median NLR was 1.52 [1.17-2.01]. In multivariate analysis, NLR remained an independent predictor of ICAS [adjusted OR (aOR) = 1.72, 95% confidence interval (CI) = 1.01-2.95, p = 0.048]. Age (aOR = 1.08, 95% CI = 1.05-1.11, p < 0.001) and hypertension (aOR = 1.81, 95% CI = 1.11-2.94, p = 0.017) were also significant factors for ICAS independent of NLR. Regarding ICAS burdens, NLR was significantly higher when the number of ICAS lesions (p = 0.017) or occlusive ICAS lesions (p = 0.005) was increased in a dose-response manner.

CONCLUSIONS

A high NLR was associated with both prevalence and burdens of ICAS in a healthy population.

Thresholds for Arterial Wall Inflammation Quantified by 18F-FDG PET Imaging: Implications for Vascular Interventional Studies

Objectives

This study assessed 5 frequently applied arterial ¹⁸fluorodeoxyglucose (¹⁸F-FDG) uptake metrics in healthy control subjects, those with risk factors and patients with cardiovascular disease (CVD), to derive uptake thresholds in each subject group. Additionally, we tested the reproducibility of these measures and produced recommended sample sizes for interventional drug studies.

Background

¹⁸F-FDG positron emission tomography (PET) can identify plaque inflammation as a surrogate endpoint for vascular interventional drug trials. However, an overview of ¹⁸F-FDG uptake metrics, threshold values, and reproducibility in healthy compared with diseased subjects is not available.

Methods

¹⁸F-FDG PET/CT of the carotid arteries and ascending aorta was performed in 83 subjects (61 ± 8 years) comprising 3 groups: 25 healthy controls, 23 patients at increased CVD risk, and 35 patients with known CVD. We quantified ¹⁸F-FDG uptake across the whole artery, the most-diseased segment, and within all active segments over several pre-defined cutoffs. We report these data with and without background corrections. Finally, we determined measurement reproducibility and recommended sample sizes for future drug studies based on these results.

Results

All ¹⁸F-FDG uptake metrics were significantly different between healthy and diseased subjects for both the carotids and aorta. Thresholds of physiological ¹⁸F-FDG uptake were derived from healthy controls using the 90th percentile of their target to background ratio (TBR) value (TBR_max); whole artery TBR_max is 1.84 for the carotids and 2.68 in the aorta. These were exceeded by >52% of risk factor patients and >67% of CVD patients. Reproducibility was excellent in all study groups (intraclass correlation coefficient >0.95). Using carotid TBR_max as a primary endpoint resulted in sample size estimates approximately 20% lower than aorta.

Conclusions

We report thresholds for physiological ¹⁸F-FDG uptake in the arterial wall in healthy subjects, which are exceeded by the majority of CVD patients. This remains true, independent of readout vessel, signal quantification method, or the use of background correction. We also confirm the high reproducibility of ¹⁸F-FDG PET measures of inflammation. Nevertheless, because of overlap between subject categories and the relatively small population studied, these data have limited generalizability until substantiated in larger, prospective event-driven studies. (Vascular Inflammation in Patients at Risk for Atherosclerotic Disease; NTR5006)

The Protective Role of PAC1-Receptor Agonist Maxadilan in BCCAO-Induced Retinal Degeneration

A number of studies have proven that pituitary adenylate cyclase activating polypeptide (PACAP) is protective in neurodegenerative diseases. Permanent bilateral common carotid artery occlusion (BCCAO) causes severe degeneration in the rat retina. In our previous studies, protective effects were observed with PACAP1-38, PACAP1-27, and VIP but not with their related peptides, glucagon, or secretin in BCCAO. All three PACAP receptors (PAC1, VPAC1, VPAC2) appear in the retina. Molecular and immunohistochemical analysis demonstrated that the retinoprotective effects are most probably mainly mediated by the PAC1 receptor. The aim of the present study was to investigate the retinoprotective effects of a selective PAC1-receptor agonist maxadilan in BCCAO-induced retinopathy. Wistar rats were used in the experiment. After performing BCCAO, the right eye was treated with intravitreal maxadilan (0.1 or 1 μM), while the left eye was injected with vehicle. Sham-operated rats received the same treatment. Two weeks after the operation, retinas were processed for standard morphometric and molecular analysis. Intravitreal injection of 0.1 or 1 μM maxadilan caused significant protection in the thickness of most retinal layers and the number of cells in the GCL compared to the BCCAO-operated eyes. In addition, 1 μM maxadilan application was more effective than 0.1 μM maxadilan treatment in the ONL, INL, IPL, and the entire retina (OLM-ILM). Maxadilan treatment significantly decreased cytokine expression (CINC-1, IL-1α, and L-selectin) in ischemia. In summary, our histological and molecular analysis showed that maxadilan, a selective PAC1 receptor agonist, has a protective role in BCCAO-induced retinal degeneration, further supporting the role of PAC1 receptor conveying the retinoprotective effects of PACAP.

Hypothermia-induced platelet aggregation and cognitive decline in coronary artery bypass surgery: a pilot study

Hypothermia-induced platelet aggregation (HIPA) was previously reported in whole blood exposed to synthetic surfaces at 24°-32°C in one-third of normal subjects tested. Cardiopulmonary bypass, conducted with hypothermia, may lead to such aggregation, resulting in microvascular occlusion contributing to cognitive impairment. This pilot study was conducted to explore the relationship between HIPA and cognitive outcome at hospital discharge in patients undergoing coronary artery bypass graft (CABG) surgery as a first step toward a longer-term study.

Patients (n=45) undergoing mild to moderate hypothermia (32°-28°8C) during CABG surgery underwent cognitive testing preoperatively and prior to hospital discharge. Tests included: visual and verbal memory, mental processing speed, executive function, language, and intellectual function. HIPA was identified using an in vitro assay in which blood flowing in polyvinychloride tubing was subjected to hypothermia, and platelet aggregates were detected using microscopy and passing the exiting blood through a 20-μm pore filter.

Forty-four percent of patients exhibited HIPA. The entire cohort exhibited significant postoperative cognitive decline in verbal memory, mental processing speed and executive function. There was greater cognitive decline in the group with HIPA compared with the group not exhibiting this phenomenon. The patients with HIPA showed significant decline in four of five cognitive measures whereas patients not exhibiting this phenomenon declined in only two of five cognitive measures.

HIPA appears to be associated with an added risk of cognitive decline immediately following CABG surgery employing mild to moderate hypothermia. The findings of our study suggest the long-term cognitive effects of hypothermia-induced platelet aggregation need to be explored.

NLRP3 Inflammasome Expression and Activation in Human Atherosclerosis

Background

The NLR family, pyrin domain containing 3 (NLRP3) inflammasome is an interleukin (IL)‐1β and IL‐18 cytokine processing complex that is activated in inflammatory conditions. The role of the NLRP3 inflammasome in the pathogenesis of atherosclerosis and myocardial infarction is not fully understood.

Methods and Results

Atherosclerotic plaques were analyzed for transcripts of the NLRP3 inflammasome, and for IL‐1β release. The Swedish First‐ever myocardial Infarction study in Ac‐county (FIA) cohort consisting of DNA from 555 myocardial infarction patients and 1016 healthy individuals was used to determine the frequency of 4 single nucleotide polymorphisms (SNPs) from the downstream regulatory region of NLRP3. Expression of NLRP3, Apoptosis‐associated speck‐like protein containing a CARD (ASC), caspase‐1 (CASP1), IL1B, and IL18 mRNA was significantly increased in atherosclerotic plaques compared to normal arteries. The expression of NLRP3 mRNA was significantly higher in plaques of symptomatic patients when compared to asymptomatic ones. CD68‐positive macrophages were observed in the same areas of atherosclerotic lesions as NLRP3 and ASC expression. Occasionally, expression of NLRP3 and ASC was also present in smooth muscle cells. Cholesterol crystals and ATP induced IL‐1β release from lipopolysaccharide‐primed human atherosclerotic lesion plaques. The minor alleles of the variants rs4266924, rs6672995, and rs10733113 were associated with NLRP3 mRNA levels in peripheral blood mononuclear cells but not with the risk of myocardial infarction.

Conclusions

Our results indicate a possible role of the NLRP3 inflammasome and its genetic variants in the pathogenesis of atherosclerosis.

High CD3+ Cells in Intracranial Thrombi Represent a Biomarker of Atherothrombotic Stroke

Background and Purpose

Approximately 30% of strokes are cryptogenic despite an exhaustive in-hospital work-up. Analysis of clot composition following endovascular treatment could provide insight into stroke etiology. T-cells already have been shown to be a major component of vulnerable atherosclerotic carotid lesions. We therefore hypothesize that T-cell content in intracranial thrombi may also be a biomarker of atherothrombotic origin.

Materials and Methods

We histopathologically investigated 54 consecutive thrombi retrieved after mechanical thrombectomy in acute stroke patients. First, thrombi were classified as fibrin-dominant, erythrocyte-dominant or mixed pattern. We then performed quantitative analysis of CD3+ cells on immunohistochemically-stained thrombi and compared T-cell content between “atherothrombotic”, “cardioembolism” and “other causes” stroke subtypes.

Results

Fourteen (26%) thrombi were defined as fibrin-dominant, 15 (28%) as erythrocyte-dominant, 25 (46%) as mixed. The stroke cause was defined as “atherothrombotic” in 10 (18.5%), “cardioembolism” in 25 (46.3%), and “other causes” in 19 (35.2%). Number of T-cells was significantly higher in thrombi from the “atherothrombotic” group (53.60 ± 28.78) than in the other causes (21.77 ± 18.31; p<0.0005) or the “cardioembolism” group (20.08 ± 15.66; p<0.0003).

Conclusions

The CD3+ T-cell count in intracranial thrombi was significantly higher in “atherothrombotic” origin strokes compared to all other causes. Thrombi with high content of CD3+ cells are more likely to originate from an atherosclerotic plaque.

Gentiana lutea exerts anti-atherosclerotic effects by preventing endothelial inflammation and smooth muscle cell migration

BACKGROUND AND AIMS

Studies suggest that Gentiana lutea (GL), and its component isovitexin, may exhibit anti-atherosclerotic properties. In this study we sought to investigate the protective mechanism of GL aqueous root extract and isovitexin on endothelial inflammation, smooth muscle cell migation, and on the onset and progression of atherosclerosis in streptozotocin (STZ)-induced diabetic rats.

METHODS AND RESULTS

Our results show that both GL extract and isovitexin, block leukocyte adhesion and generation of reactive oxygen species in human umbilical vein endothelial cells (HUVECs) and rat aortic smooth muscle cells (RASMCs), following TNF-alpha and platelet derived growth factor-BB (PDGF-BB) challenges respectively. Both the extract and isovitexin blocked TNF-α induced expression of ICAM-1 and VCAM-1 in HUVECs. PDGF-BB induced migration of RASMCs and phospholipase C-γ activation, were also abrogated by GL extract and isovitexin. Fura-2 based ratiometric measurements demonstrated that, both the extact, and isovitexin, inhibit PDGF-BB mediated intracellular calcium rise in RASMCs. Supplementation of regular diet with 2% GL root powder for STZ rats, reduced total cholesterol in blood. Oil Red O staining demonstrated decreased lipid accumulation in aortic wall of diabetic animals upon treatment with GL. Medial thickness and deposition of collagen in the aortic segment of diabetic rats were also reduced upon supplementation. Immunohistochemistry demonstrated reduced expression of vascular cell adhesion molecule-1 (VCAM-1), inducible nitric oxide synthase (iNOS), and vascular endothelial cadherin (VE-cadherin) in aortic segments of diabetic rats following GL treatment.

CONCLUSIONS

Thus, our results support that GL root extract/powder and isovitexin exhibit anti-atherosclerotic activities.

Relationship between thyroid function and carotid artery plaque ulceration

Carotid artery plaque ulceration (PU) is known to be associated with cerebrovascular events (CVE). Even within euthyroid ranges, thyroid function has been reported to be associated with carotid atherosclerosis. However, the relationship between thyroid function and carotid PU remains unclear. Our aim was to determine the relationship between thyroid function and PU in patients with internal carotid artery stenosis (ICS). Records of patients with CVE were retrospectively reviewed. A total of 250 consecutive patients with ICS who had computed tomography angiography (CTA) of the carotid arteries following hospitalization were included in the study. CTA was used for the evaluation of carotid artery plaque morphology and ulceration. Plaque morphology was classified as fatty, mixed or calcified. Patients were divided into two groups according to the presence or absence of PU. Subclinical hypothyroidism (SCH) and hypothyroidism were significantly more common in patients with PU (p < 0.001 and p = 0.003, respectively). Patients with PU had higher incidence of low-normal FT4 levels (p = 0.02). Compared with patients who had no PU, patients with PU had decreased FT4 levels and elevated TSH levels (p = 0.001 and p = 0.001, respectively). TSH level (OR 1.33, p = 0.001), SCH (OR 4.2, p = 0.001), hypothyroidism (OR 3.15, p = 0.037), fatty plaque (OR 2.16, p = 0.01) and calcified plaque (OR 0.19, p < 0.001) were independently associated with PU. Our results suggest that SCH and hypothyroidism could be a risk factor for PU and subsequent CVE. Thyroid functions may be useful for risk stratification of patients with ICS.

Analysis of Multicontrast Carotid Plaque MR Imaging

Plaque imaging by MR imaging provides a wealth of information on the characteristics of individual plaque that may reveal vulnerability to rupture, likelihood of progression, or optimal treatment strategy. T1-weighted and T2-weighted images among other options reveal plaque morphology and composition. Dynamic contrast-enhanced-MR imaging reveals plaque activity. To extract this information, image processing tools are needed. Numerous approaches for analyzing such images have been developed, validated against histologic gold standards, and used in clinical studies. These efforts are summarized in this article.

Propionibacterium acnes Recovered from Atherosclerotic Human Carotid Arteries Undergoes Biofilm Dispersion and Releases Lipolytic and Proteolytic Enzymes in Response to Norepinephrine Challenge In Vitro

In the present study, human atherosclerotic carotid arteries were examined following endarterectomy for the presence of the Gram-positive bacterium Propionibacterium acnes and its potential association with biofilm structures within the arterial wall. The P. acnes 16S rRNA gene was detectable in 4 of 15 carotid artery samples, and viable P. acnes was one among 10 different bacterial species recoverable in culture. Fluorescence in situ hybridization analysis of 5 additional atherosclerotic carotid arteries demonstrated biofilm bacteria within all samples, with P. acnes detectable in 4 samples. We also demonstrated that laboratory-grown cultures of P. acnes biofilms were susceptible to induction of a biofilm dispersion response when challenged with physiologically relevant levels of norepinephrine in the presence of iron-bound transferrin or with free iron. The production and release of lipolytic and proteolytic extracellular enzymes by P. acnes were shown to increase in iron-induced dispersed biofilms, and these dispersion-induced P. acnes VP1 biofilms showed increased expression of mRNAs for the triacylglycerol lipases PPA2105 and PPA1796 and the hyaluronate lyase PPA380 compared to that in untreated biofilms. These results demonstrate that P. acnes can infect the carotid arteries of humans with atherosclerosis as a component of multispecies biofilms and that dispersion is inducible for this organism, at least in vitro, with physiologically relevant levels of norepinephrine resulting in the production and release of degradative enzymes.

Carotid FDG Uptake Improves Prediction of Future Cardiovascular Events in Asymptomatic Individuals

OBJECTIVES

This study sought to investigate the role of carotid fluoro-2-deoxyglucose (FDG) uptake as an independent prognostic indicator and to determine whether its addition improves risk prediction beyond the Framingham risk score (FRS) and carotid intima-media thickness (CIMT).

BACKGROUND

The prognostic value of carotid FDG uptake independent of and incremental to traditional cardiovascular risk factors and CIMT in asymptomatic individuals has not been evaluated.

METHODS

We measured carotid FDG uptake and CIMT in 1,089 asymptomatic adults (51.8 ± 6.3 years of age, 94.3% males) who underwent positron emission tomography/computed tomography imaging and examined the prognostic value of carotid FDG uptake compared with traditional risk factors and CIMT.

RESULTS

Cardiocerebrovascular events occurred in 19 participants (1.74%) during an average follow-up of 4.2 years (range 1.0 to 5.5 years). Multivariable Cox proportional hazards analyses revealed that high carotid FDG uptake (hazard ratio: 2.98; 95% confidence interval: 1.17 to 7.62; p = 0.022) and high CIMT (hazard ratio: 2.82; 95% confidence interval: 1.13 to 7.03; p = 0.026) were independent predictors of events. Comparison of predictive power demonstrated that adding carotid FDG uptake, but not CIMT, to the FRS significantly increased the time-dependent area under the receiver-operating characteristic curve from 0.60 to 0.73 (p = 0.04). Furthermore, improvement approaching significance was achieved by adding carotid FDG uptake to the FRS plus CIMT, which increased the area under the receiver-operating characteristic curve from 0.65 to 0.75 (p = 0.07). Net reclassification for event prediction was similarly improved by addition of carotid FDG uptake to the FRS (net reclassification index, 40.1%; p = 0.06), as well as the FRS plus CIMT (net reclassification index, 32.9%; p = 0.07).

CONCLUSIONS

High carotid FDG uptake predicts cardiovascular events independent of traditional risk factors and CIMT in asymptomatic adults and may add to risk stratification beyond the FRS and CIMT.

Clinical significance of macrophage phenotypes in cardiovascular disease

The emerging understanding of macrophage subsets and their functions in the atherosclerotic plaque has led to the consensus that M1 macrophages are pro-atherogenic while M2 macrophages may promote plaque stability, primarily though their tissue repair and anti-inflammatory properties. As such, modulating macrophage function to promote plaque stability is an exciting therapeutic prospect. This review will outline the involvement of the different macrophage subsets throughout atherosclerosis progression and in models of regression. It is evident that much of our understanding of macrophage function comes from in vitro or small animal models and, while such knowledge is valuable, we have much to learn about the roles of the macrophage subsets in the clinical setting in order to identify the key pathways to target to possibly promote plaque stability.

Bacteria present in carotid arterial plaques are found as biofilm deposits which may contribute to enhanced risk of plaque rupture

Atherosclerosis, a disease condition resulting from the buildup of fatty plaque deposits within arterial walls, is the major underlying cause of ischemia (restriction of the blood), leading to obstruction of peripheral arteries, congestive heart failure, heart attack, and stroke in humans. Emerging research indicates that factors including inflammation and infection may play a key role in the progression of atherosclerosis. In the current work, atherosclerotic carotid artery explants from 15 patients were all shown to test positive for the presence of eubacterial 16S rRNA genes. Density gradient gel electrophoresis of 5 of these samples revealed that each contained 10 or more distinct 16S rRNA gene sequences. Direct microscopic observation of transverse sections from 5 diseased carotid arteries analyzed with a eubacterium-specific peptide nucleic acid probe revealed these to have formed biofilm deposits, with from 1 to 6 deposits per thin section of plaque analyzed. A majority, 93%, of deposits was located proximal to the internal elastic lamina and associated with fibrous tissue. In 6 of the 15 plaques analyzed, 16S rRNA genes from Pseudomonas spp. were detected. Pseudomonas aeruginosa biofilms have been shown in our lab to undergo a dispersion response when challenged with free iron in vitro. Iron is known to be released into the blood by transferrin following interaction with catecholamine hormones, such as norepinephrine. Experiments performed in vitro showed that addition of physiologically relevant levels of norepinephrine induced dispersion of P. aeruginosa biofilms when grown under low iron conditions in the presence but not in the absence of physiological levels of transferrin.

IMPORTANCE

The association of bacteria with atherosclerosis has been only superficially studied, with little attention focused on the potential of bacteria to form biofilms within arterial plaques. In the current work, we show that bacteria form biofilm deposits within carotid arterial plaques, and we demonstrate that one species we have identified in plaques can be stimulated in vitro to undergo a biofilm dispersion response when challenged with physiologically relevant levels of norepinephrine in the presence of transferrin. Biofilm dispersion is characterized by the release of bacterial enzymes into the surroundings of biofilm microcolonies, allowing bacteria to escape the biofilm matrix. We believe these enzymes may have the potential to damage surrounding tissues and facilitate plaque rupture if norepinephrine is able to stimulate biofilm dispersion in vivo. This research, therefore, suggests a potential mechanistic link between hormonal state and the potential for heart attack and stroke.

Relationship between lysophosphatidic acid and matrix metalloproteinase-9 plasma concentrations and carotid atheromatous plaque stability in patients with cerebral infarction

Objective:

To investigate the correlation between plasma lysophosphatidic acid (LPA), matrix metalloproteinase (MMP)-9 and carotid atheromatous plaque stability in patients with cerebral infarction.

Method:

Patients with cerebral infarction underwent carotid artery duplex ultrasonography and transcranial Doppler monitoring for detection of microemboli. Patients were stratified by plaque type (no plaque, intima thickening, unstable plaque, stable plaque) and presence or absence of micoremboli. Plasma LPA and MMP-9 were quantified.

Result:

LPA and MMP-9 concentrations were significantly higher and microemboli positivity was significantly more common in patients with unstable plaque ( n = 21) than the other three groups (intima thickening, n = 16; stable plaque n = 41; no plaque; n = 12). There was a significant positive correlation between LPA and MMP-9 concentrations.

Conclusion:

Plasma LPA and MMP-9 concentrations may be useful biomarkers in the clinical identification and prediction of unstable plaque, and in guiding treatment.

Comparison of fluorodeoxyglucose uptake in symptomatic carotid artery and stable femoral artery plaques

BACKGROUND

Fluorine-18-labelled fluoroxdeoxyglucose (FDG) positron emission tomography (PET) has been used to evaluate atherosclerotic plaque metabolic activity, and through its uptake by macrophages is believed to have the potential to identify vulnerable plaques. The aims were to compare FDG uptake in carotid plaques from patients who had sustained a recent thromboembolic cerebrovascular event with that in femoral artery plaques from patients with leg ischaemia, and to correlate FDG uptake with the proportion of M1 and M2 macrophages present.

METHODS

Consecutive patients who had carotid endarterectomy for symptomatic, significant carotid stenosis and patients with severe leg ischaemia and significant stenosis of the common femoral artery underwent FDG-PET and histological plaque analysis. The voxel with the greatest activity in the region of interest was calculated using the Patlak method over 60 min. Plaques were dual-stained for CD68, and M1 and M2 macrophage subsets.

RESULTS

There were 29 carotid and 25 femoral artery plaques for study. The maximum dynamic uptake was similar in carotid compared with femoral plaques: median (range) 9·7 (7·1-12·2) versus 10·0 (7·4-16·6) respectively (P = 0·281). CD68 macrophage counts were significantly increased in carotid compared with femoral plaques (39·5 (33·9-50·1) versus 11·5 (7·7-21·3) respectively; P < 0·001), as was the proportion of M1 proinflammatory macrophages. The degree of carotid stenosis correlated with the maximum dynamic FDG uptake (rs  = 0·48, P = 0·008).

CONCLUSION

FDG uptake was no greater in symptomatic carotid plaques than in the less inflammatory femoral plaques. In patients on statin therapy. FDG uptake occurred in areas of significant arterial stenosis, irrespective of the degree of inflammation.

Imaging of the vulnerable carotid plaque: biological targeting of inflammation in atherosclerosis using iron oxide particles and MRI

OBJECTIVES

Identification of those patients with high-risk asymptomatic carotid plaques remains an elusive but essential step in stroke prevention. Inflammation is a key process in plaque destabilization and the propensity of atherosclerotic lesions to cause clinical sequelae. There is currently no clinical imaging technique available to assess the degree of inflammation associated with plaques. This study aims at visualizing and characterizing atherosclerosis using antibody-conjugated superparamagnetic iron oxide (SPIO) particles as an MRI probe to assess inflammation in human atherosclerotic plaques.

METHODS

Atherosclerotic plaques were collected from 20 consecutive patients (n=10 from symptomatic patients, n=10 from asymptomatic patients) undergoing carotid endarterectomy (CEA) for extracranial high-grade internal carotid artery (ICA) stenosis (>70% luminal narrowing). Inflammatory markers on human atherosclerotic plaques were detected and characterized by ex vivo magnetic resonance imaging (MRI) using anti-VCAM-1 antibody and anti-E-selectin antibody-conjugated SPIO with confirmatory immunohistochemistry.

RESULTS

Inflammation associated with human ex vivo atherosclerotic plaques could be imaged using dual antibody-conjugated SPIO by MRI. Symptomatic plaques could be distinguished from asymptomatic ones by the degree of inflammation, and the MR contrast effect was significantly correlated with the degree of plaque inflammation (r=.64, p<.001). The asymptomatic plaque population exhibited heterogeneity in terms of inflammation. The dual-targeted SPIO-induced MR signal not only tracked closely with endothelial activation (i.e. endothelial expression of VCAM-1 and E-selectin), but also reflected the macrophage burden within plaque lesions, offering a potential imaging tool for quantitative MRI of inflammatory activity in atherosclerosis.

CONCLUSIONS

These functional molecular MRI probes constitute a novel imaging tool for ex vivo characterization of atherosclerosis at a molecular level. Further development and translation into the clinical arena will facilitate more accurate risk stratification in carotid artery disease in the future.

Levels of circulating neopterin in patients with severe carotid artery stenosis undergoing carotid stenting

AIMS

The association between an elevated serum neopterin level and the development of coronary artery complex lesions has been extensively assessed; however, the correlation between the serum neopterin level and the development of carotid artery stenosis has seldom been reported. This study tested whether this biomarker is increased in patients with severe carotid artery stenosis(≥70%) undergoing carotid artery(CA) stenting and investigated independent predictors of an increased circulating neopterin level.

METHODS

Fifty patients with severe CA stenosis(CAS) undergoing CA stenting were consecutively enrolled in this study from January 2009 through December 2011. The serum neopterin levels of age- and gender-matched acute ischemic stroke(AIS) patients(n=120) and control subjects(CS)(n=33) were also measured. A blood sample was prospectively collected from each patient in the catheterization room.

RESULTS

The serum levels of neopterin were significantly higher in the CAS patients than in the AIS patients or CS and significantly higher in the AIS patients than in the CS(all p＜0.001). An analysis of the variables of 170 patients(CAS＋AIS) demonstrated that age, a previous history of stroke and severe CAS were significantly correlated with an increased serum level of neopterin(all p＜0.005). A multivariate binary logistic regression analysis of the severe CAS patients(n=50) demonstrated that age and the creatinine level were independent predictors of a high neopterin level(neopterin level ≥16.52 ng/dL, i.e., according to the median value of neopterin)(all p＜0.05).

CONCLUSIONS

The circulating neopterin levels are significantly higher in patients with severe CAS than in those with AIS. The presence of CAS, age and the creatinine level were significantly correlated with an increased serum neopterin level.

Carotid artery disease and stroke: assessing risk with vessel wall MRI

Although MRI is widely used to diagnose stenotic carotid arteries, it also detects characteristics of the atherosclerotic plaque itself, including its size, composition, and activity. These features are emerging as additional risk factors for stroke that can be feasibly acquired clinically. This paper summarizes the state of evidence for a clinical role for MRI of carotid atherosclerosis.

Therapeutic strategies to deplete macrophages in atherosclerotic plaques

Macrophages can be found in all stages of atherosclerosis and are major contributors of atherosclerotic plaque development, progression and destabilization. Continuous recruitment of monocytes drives this chronic inflammatory disease, which can be intervened by several strategies: reducing the inflammatory stimulus by lowering circulating lipids and promoting cholesterol efflux from plaque, direct and indirect targeting of adhesion molecules and chemokines involved in monocyte adhesion and transmigration and inducing macrophage death in atherosclerotic plaques in combination with anti-inflammatory drugs. This review discusses the outlined strategies to deplete macrophages from atherosclerotic plaques to promote plaque stabilization.

Macrophage subtypes in symptomatic carotid artery and femoral artery plaques

OBJECTIVE

To compare differences in macrophage heterogeneity and morphological composition between atherosclerotic plaques obtained from recently symptomatic patients with carotid artery disease and femoral plaques from patients with severe limb ischemia.

DESIGN

Experimental study.

METHODS

Plaques were obtained from 32 patients undergoing carotid endarterectomy and 25 patients undergoing common femoral endarterectomy or lower limb bypass. Macrophages and T cell numbers were detected in plaque sections by immunohistochemistry and anti CD68 and CD3 antibodies. Dual staining for CD68 and M1- and M2-macrophage markers and morphometric analysis of hematoxylin and eosin stained plaque sections was performed.

RESULTS

Carotid plaques had significantly increased percentage areas of confluent lipid and leukocytic infiltrates. In contrast, areas of fibroconnective tissue were significantly greater in femoral plaques and percentage areas of confluent calcification and collagen were elevated. Carotid artery plaques had greater numbers per plaque area of macrophages and T cells consistent with a more inflammatory phenotype. Proportions displaying M1-activation markers were significantly increased in the carotid compared to femoral plaques whereas femoral plaques displayed a greater proportion of M2-macrophages.

CONCLUSION

Plaques from patients with recently symptomatic carotid disease have a predominance of M1-macrophages and higher lipid content than femoral plaques, consistent with a more unstable plaque.

Fluorine-18-fluorodeoxyglucose positron emission tomography may predict the outcome in patients with asymptomatic mild stenosis of internal carotid artery--case report

A 47-year-old male presented with asymptomatic mild (45%) internal carotid artery (ICA) stenosis associated with familial hypercholesterolemia. Fluorine-18-fluorodeoxyglucose ([(18)F]FDG) positron emission tomography (PET) showed that the carotid plaque had high uptake of [(18)F]FDG on the initial scan. He was treated with antiplatelet agent, but subsequently developed retinal artery occlusion on the ipsilateral side. The patient safely underwent carotid endarterectomy (CEA). Histological examination revealed that the plaque was rich in lipids and activated macrophages. Previous large randomized clinical trials have clarified that CEA is an effective therapeutic option to reduce the risk for subsequent ischemic stroke in patients with severe (more than 70%) ICA stenosis. The case strongly suggests that [(18)F]FDG PET may be a useful modality to identify inflamed and/or vulnerable carotid plaque and may be useful to predict the risk for subsequent ischemic stroke even in patients with mild to moderate ICA stenosis (less than 70%).

Serum level and prognostic value of neopterin in patients after ischemic stroke

BACKGROUND

We hypothesized that serum level of neopterin is significantly predictive of prognostic outcome in patients after acute ischemic stroke (IS).

METHODS

Between November 2008 and May 2010, serum levels of neopterin were prospectively collected at 48 h after acute IS in 157 patients.

RESULTS

Serum neopterin levels were substantially higher in patients with severe neurological impairment [National institutes of Health Stroke Scale (NIHSS) score ≥12] than in those with NIHSS <12 (p<0.008). Furthermore, Spearman's test showed a strongly positive correlation between neopterin level and NIHSS (p=0.003). Multiple logistic regression analysis demonstrated that serum neopterin level was strongly and independently predictive of NIHSS ≥12 (p=0.002) at 48 h after acute IS and 90-day major adverse clinical outcome (defined as NIHSS≥12, recurrent stroke or death) (p=0.003).

CONCLUSION

Serum level of neopterin was notably increased after acute IS. This biomarker was strongly and independently predictive of 90-day unfavorable clinical outcome in patients after acute IS.

Toll-like receptor 7 stimulation by imiquimod induces macrophage autophagy and inflammation in atherosclerotic plaques

Atherosclerotic plaques tend to rupture as a consequence of a weakened fibrous cap, particularly in the shoulder regions where most macrophages reside. Macrophages express Toll-like receptors to recognize pathogens and eliminate intracellular pathogens by inducing autophagy. Because Toll-like receptor 7 (TLR7) is thought to be expressed in macrophages but not in smooth muscle cells (SMCs), we investigated whether induction of macrophage autophagic death by TLR7 ligand imiquimod can affect the composition of atherosclerotic plaques in favor of their stability. Immunohistochemical staining of human carotid plaques as well as Western blotting of cultured macrophages and SMCs confirmed that TLR7 was expressed in macrophages, but not in SMCs. In vitro experiments showed that only TLR7 expressing cells underwent imiquimod-induced cell death, which was characterized by autophagosome formation. Imiquimod-treated macrophages activated nuclear factor-κB (NF-κB) and released pro-inflammatory cytokines and chemokines. This effect was inhibited by the glucocorticoid dexamethasone. Imiquimod-induced cytokine release was significantly decreased in autophagy-deficient macrophages because these cells died by necrosis at an accelerated pace. Local in vivo administration of imiquimod to established atherosclerotic lesions in rabbit carotid arteries induced macrophage autophagy without induction of cell death, and triggered cytokine production, upregulation of vascular adhesion molecule-1, infiltration of T-lymphocytes, accumulation of macrophages and enlargement of plaque area. Treatment with dexamethasone suppressed these pro-inflammatory effects in vivo. SMCs and endothelial cells in imiquimod-treated plaques were not affected. In conclusion, imiquimod induces macrophage autophagy in atherosclerotic plaques, but stimulates plaque progression through cytokine release and enhanced infiltration of inflammatory cells.

Intravascular frequency-domain optical coherence tomography assessment of atherosclerosis and stent-vessel interactions in human carotid arteries

BACKGROUND AND PURPOSE

Carotid artery-related stroke is largely an embolic disease that has been correlated with inflammation, plaque rupture, and thrombus formation in "vulnerable" atherosclerotic plaque. Nevertheless, current guidelines for carotid revascularization in asymptomatic patients rely on the calculation of stenosis for risk assessment, a parameter that has been viewed with increasing skepticism. Intravascular OCT is an imaging technique that offers high axial resolution (10 μm), allowing an unprecedented micron-level assessment of human carotid plaque morphology. This observational article reports the first successful use of the newest iteration of this technology, FDOCT without balloon occlusion to assess human carotid artery disease and carotid stent-vessel interaction in vivo.

MATERIALS AND METHODS

Four patients with asymptomatic carotid artery disease and ambiguous noninvasive and/or angiographic data underwent carotid FDOCT to assess risk and to formulate a treatment strategy.

RESULTS

Findings include the unexpected demonstration of TCFAs, plaque rupture, thrombus, inflammation, and marked tissue prolapse through stent struts in patients without high-risk factors by conventional criteria, as well as low-risk features in a patient with a high-risk noninvasive study. The procedures were performed without safety issues or special accommodations for vessel occlusion.

CONCLUSIONS

The present study demonstrates the technical feasibility of FDOCT in cervical carotid arteries. As such, this technology holds the promise of not only clarifying ambiguous data in individual patients but of providing data that might call for a future paradigm shift in the assessment of asymptomatic carotid artery disease.

Prevalence and risk factors of carotid vessel wall inflammation in coronary artery disease patients: FDG-PET and CT imaging study

OBJECTIVES

We investigated the prevalence and clinical risk factors of carotid vessel wall inflammation by means of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in a population consisting of coronary artery disease (CAD) patients.

BACKGROUND

The atherosclerotic disease process is characterized by infiltration and retention of oxidized lipids in the artery wall, triggering a disproportionate inflammatory response. Efforts have been made to use noninvasive imaging to quantify this inflammatory response in the vessel wall. Recently, carotid FDG-PET has been shown to reflect the metabolic rate of glucose, a process known to be enhanced in inflamed tissue.

METHODS

Carotid inflammation was quantified in 82 CAD patients (age 62 ± 10 years) as the maximum target-to-background ratio ((wholevessel)TBR(max)). Furthermore, we assessed the maximal standardized uptake value values ((wholevessel)SUV(max)), the single hottest segment (SHS), and the percent active segments (PAS) of the FDG uptake in the artery wall, measured by FDG-PET.

RESULTS

Whole-vessel TBR(max) >1.8 was present in 67%, >2.0 in 39%, >2.2 in 23%, and >2.4 in 12% of the population. Multiple linear regression analysis with backward elimination revealed that body mass index (BMI) ≥30 kg/m2 (p < 0.0001), age >65 years (p = 0.01), smoking (p = 0.02), and hypertension (p = 0.01) were associated with (wholevessel)TBR(max). The number of components of the metabolic syndrome was also associated with (wholevessel)TBR(max) (p = 0.02). In similar analyses, (wholevessel)SUV(max) was associated with BMI ≥30 kg/m2 (p < 0.0001), age >65 years (p = 0.004), male gender (p = 0.02), and hypertension (p = 0.04); SHS with BMI ≥30 kg/m2 (p < 0.0001), age >65 years (p = 0.02), smoking (p = 0.04), and hypertension (p = 0.05); PAS with BMI ≥30 kg/m2 (p = 0.001), smoking (p = 0.03), and hypertension (p = 0.01).

CONCLUSIONS

Carotid inflammation as revealed by FDG-PET is highly prevalent in the CAD population and is associated with obesity, age over 65 years, history of hypertension, smoking, and male gender. Artery wall FDG uptake increased when components of the metabolic syndrome clustered.

Polymorphisms of interleukin-1 and interleukin-6 genes on the risk of ischemic stroke in a meta-analysis

Many epidemiological studies have investigated the associations between polymorphisms of interleukin-1 (IL1) and interleukin-6 (IL6) genes and risk of ischemic stroke (IS), but no conclusions are available because of conflicting results. The aim of this study was to assess the relationships by meta-analysis. The databases of Pubmed, Embase and Wangfang, updated to August 1st, 2011, were retrieved. Odds ratio (OR) and corresponding 95% confidence interval (95% CI) as effect size were calculated by a fixed- or random-effect model. In total, three case-control studies for IL1α-889C/T, eight studies for IL1β-511C/T, eight studies for IL1-Ra and seven studies for IL6-147G/C were included in this meta-analysis. Combined analysis indicated that IL1β-511C/T polymorphism was not overall associated with risk of IS [OR (95% CI)=1.22 (0.85-1.87) for TT vs. CC]. However, when subgroup analyses for countries were conducted, the results indicated that T allele was associated with increased risk of IS for Polish and associated with a trend of increased risk of IS for Chinese although it did not reach statistical significance [TT vs. CC: OR (95% CI)=1.97 (1.22-3.17) for Polish and 1.40 (0.99-1.99) for Chinese]. In addition, overall and subgroup analyses indicated that IL1α-889C/T, IL1-Ra and IL6-147G/C polymorphisms were also not associated with risk of IS [OR (95% CI)=1.21 (0.86-1.70) for TT vs. CC of IL1α-889C/T, 1.22 (0.85-1.75) for RN2/RN2 vs. RN1/RN1 for IL1-Ra and 1.09 (0.84-1.40) for G carriers vs. C carriers for IL6-147G/C]. This study inferred that IL1β-511C/T polymorphism might be moderately associated with increased risk of IS, but no sufficient evidence was available to support any associations between IL1-Ra and IL6-147G/C polymorphisms and IS. We could not draw a conclusion between IL1α-889C/T polymorphism and risk of IS based on the limited data, and further large sample-sized studies were required.