Association of the fibrinolytic system and hemorheology with symptoms in patients with carotid occlusive disease

Selected Factors of Vascular Changes: The Potential Pathological Processes Underlying Primary Headaches in Children

Background: The prevalence, social consequences and complicated pathogenesis make headaches in children a significant clinical issue. Studies in adults suggest that primary headaches could be the first sign of atherosclerosis and platelet aggregation. Aim: To analyze the blood levels of selected biomarkers of vascular changes potentially associated with a higher risk of atherosclerosis in children with primary headaches. Methods: The medical family history, brain-derived neurotrophic factor (BDNF), soluble CD40 ligands (sCD40L), endothelial plasminogen activator inhibitor (PAI I), vascular endothelial growth factor (VEGF) and intima-media thickness (IMT) measurements were performed in the 83 children (52 with primary headaches, 31 controls). Selected factors were compared with basic laboratory parameters that are potentially related to atherosclerosis: C-reactive protein (CRP) and lipid concentration. Results: There were no significant differences in biomarkers of vascular changes in the study group and controls in general. In the study group, boys had a higher BDNF level than girls (p = 0.046). Normal-weight migraine patients had significantly higher PAI-I levels than controls (p = 0.034). A positive correlation between PAI-1 and triglycerides (TG) was observed. IMT did not differ between children with primary headaches and controls; however, IMT showed a positive correlation with BMI z-score and TG. Children with headaches had, more often, a positive family history of cardiovascular disease (p = 0.049). Conclusions: There were no clear clinical changes indicative of atherosclerosis in the study population. However, some trends are visible. Primary headaches are more often related to a family history of cardiovascular diseases. IMT is associated with TG levels and BMI z-score. The measured biomarkers of vascular changes show mutual relations.

Headache in Children: Selected Factors of Vascular Changes Involved in Underlying Processes of Idiopathic Headaches

Headaches are common complaints in children. The International Classification of Headache Disorders, 3^rd edition (beta version), defines more than 280 types of headaches. Primary headaches refer to independent conditions that cause pain and include migraine, tension-type headaches (TTH), and trigeminal autonomic cephalalgias (TACs). Several agents are involved in the pathogenesis of headaches. The factors associated with predisposition to atherosclerosis seem to be particularly important from the clinical point of view. The influence of obesity on the incidence of headaches has been well established. Moreover, idiopathic headaches, especially migraine, are thought to be one of the first signs of disorders in lipid metabolism and atherosclerosis. The risk of migraine increases with increasing obesity in children. Another factor that seems to be involved in both obesity and headaches is the adiponectin level. Recent data also suggest new potential risk factors for atherosclerosis and platelet aggregation such as brain-derived neurotrophic factor (BDNF), sCD40L (soluble CD40 ligand), serpin E1/PAI I (endothelial plasminogen activator inhibitor), and vascular endothelial growth factor (VEGF). However, their role is controversial because the results of clinical studies are often inconsistent. This review presents the current knowledge on the potential markers of atherosclerosis and platelet aggregation, which may be associated with primary headaches.

Lipid levels and selected biomarkers of vascular changes in children with idiopathic headaches - a preliminary report

INTRODUCTION

Elevated lipid concentrations were observed in adults with headaches. However, studies in children are scarce. Recent data suggest new potential risk factors for atherosclerosis, which may be associated with headaches. The aim of the study was to analyse the blood levels of lipids and new markers of atherosclerosis in children with idiopathic headaches.

MATERIAL AND METHODS

The study population comprised 65 children (39 with idiopathic headaches and 26 healthy children). Total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL) cholesterol and triacylglycerol (TG) levels were measured in every patient. Brain-derived neurotrophic factor (BDNF), soluble CD40 ligand (sCD40L), endothelial plasminogen activator inhibitor (serpin E1/PAI I) and vascular endothelial growth factor (VEGF) blood level measurements were performed in 34 children.

RESULTS

Children with headaches had higher BMI z-scores (0.2 vs. -1.14; p = 0.006). TC level was lower in patients with headaches (121.04 mg/dl vs. 146.87 mg/dl, p = 0.019). No differences in concentrations of TG, HDL or LDL were found. BDNF was significantly higher in the studied group (171.57 pg/ml vs. 64.04 pg/ml, p = 0.012). The VEGF was higher in boys with headaches than in girls (368.27 pg/ml vs. 142.86 pg/ml, p = 0.011). There were no differences in levels of VEGF, sCD40L or PAI-1 between groups.

CONCLUSIONS

Children with headaches have lower total cholesterol and higher BDNF levels than controls. No significant difference in levels of triacylglycerols, HDL cholesterol, LDL cholesterol, VEGF, sCD40L or PAI-1 was found between children with headaches and controls.

Morphology and histology of silent and symptom-causing atherosclerotic carotid plaques - Rationale and design of the Helsinki Carotid Endarterectomy Study 2 (the HeCES2)

INTRODUCTION

Every fifth ischemic stroke is caused by thromboembolism originating from an atherosclerotic carotid artery plaque. While prevention is the most cost-effective stroke therapy, antiplatelet and cholesterol-lowering drugs have a ceiling effect in their efficacy. Therefore, discovery of novel pathophysiologic targets are needed to improve the primary and secondary prevention of stroke. This article provides a detailed study design and protocol of HeCES2, an observational prospective cohort study with the objective to investigate the pathophysiology of carotid atherosclerosis.

MATERIALS AND METHODS

Recruitment and carotid endarterectomies of the study patients with carotid atherosclerosis were performed from October 2012 to September 2015. After brain and carotid artery imaging, endarterectomised carotid plaques (CPs) and blood samples were collected from 500 patients for detailed biochemical and molecular analyses. Findings to date: We developed a morphological grading for macroscopic characteristics within CPs. The dominant macroscopic CP characteristics were: smoothness 62%, ulceration 61%, intraplaque hemorrhage 60%, atheromatous gruel 59%, luminal coral-type calcification 34%, abundant (44%) and moderate (39%) intramural calcification, and symptom-causing "hot spot" area 53%. Future plans: By combining clinically oriented and basic biomedical research, this large-scale study attempts to untangle the pathophysiological perplexities of human carotid atherosclerosis. Key Messages This article is a rationale and design of the HeCES2 study that is an observational prospective cohort study with the objective to investigate the pathophysiology of carotid atherosclerosis. The HeCES2 study strives to develop diagnostic algorithms including radiologic imaging to identify carotid atherosclerosis patients who warrant surgical treatment. In addition, the study aims at finding out new tools for clinical risk stratification as well as novel molecular targets for drug development.

Research Progress on the Risk Factors and Outcomes of Human Carotid Atherosclerotic Plaques

Objective:

Atherosclerosis is an inflammatory process that results in complex lesions or plaques that protrude into the arterial lumen. Carotid atherosclerotic plaque rupture, with distal atheromatous debris embolization, causes cerebrovascular events. This review aimed to explore research progress on the risk factors and outcomes of human carotid atherosclerotic plaques, and the molecular and cellular mechanisms of human carotid atherosclerotic plaque vulnerability for therapeutic intervention.

Data Sources:

We searched the PubMed database for recently published research articles up to June 2016, with the key words of “risk factors”, “outcomes”, “blood components”, “molecular mechanisms”, “cellular mechanisms”, and “human carotid atherosclerotic plaques”.

Study Selection:

The articles, regarding the latest developments related to the risk factors and outcomes, atherosclerotic plaque composition, blood components, and consequences of human carotid atherosclerotic plaques, and the molecular and cellular mechanisms of human carotid atherosclerotic plaque vulnerability for therapeutic intervention, were selected.

Results:

This review described the latest researches regarding the interactive effects of both traditional and novel risk factors for human carotid atherosclerotic plaques, novel insights into human carotid atherosclerotic plaque composition and blood components, and consequences of human carotid atherosclerotic plaque.

Conclusion:

Carotid plaque biology and serologic biomarkers of vulnerability can be used to predict the risk of cerebrovascular events. Furthermore, plaque composition, rather than lesion burden, seems to most predict rupture and subsequent thrombosis.

Increased thrombin generation potential in symptomatic versus asymptomatic moderate or severe carotid stenosis and relationship with cerebral microemboli

INTRODUCTION

The importance of thrombin generation in the pathogenesis of TIA or stroke and its relationship with cerebral microembolic signals (MES) in asymptomatic and symptomatic carotid stenosis has not been comprehensively assessed.

METHODS

Plasma thrombin generation parameters from patients with moderate or severe (≥ 50%) asymptomatic carotid stenosis were compared with those from patients with symptomatic carotid stenosis in the early (≤ 4 weeks) and late phases (≥ 3 months) after TIA or stroke in this prospective, pilot observational study. Thrombin generation profile was longitudinally assessed in symptomatic patients with data at each time point. Bilateral transcranial Doppler ultrasound monitoring of the middle cerebral arteries was performed whenever possible to classify patients as MES-positive or MES-negative.

RESULTS

Data from 31 asymptomatic, 46 'early symptomatic' and 35 'late symptomatic' patients were analysed. Peak thrombin (344.2 nM vs 305.3 nM; p = 0.01) and endogenous thrombin potential (1772.4 vs 1589.7; p = 0.047) were higher in early symptomatic than asymptomatic patients. Peak thrombin production decreased in symptomatic patients followed up from the early to late phase after TIA or stroke (339.7 nM vs 308.6 nM; p = 0.02). Transcranial Doppler ultrasound data were available in 25 asymptomatic, 31 early symptomatic and 27 late symptomatic patients. Early symptomatic MES-positive patients had a shorter 'time-to-peak thrombin' than asymptomatic MES-positive patients (p=0.04), suggesting a more procoagulant state in this early symptomatic subgroup.

DISCUSSION

Thrombin generation potential is greater in patients with recently symptomatic than asymptomatic carotid stenosis, and decreases over time following TIA or stroke associated with carotid stenosis. These data improve our understanding of the haemostatic/thrombotic biomarker profile in moderate-severe carotid stenosis.

Role of red blood cell flow behavior in hemodynamics and hemostasis

The primary role of red blood cells (RBCs) is to transport oxygen to the tissues, which is performed predominantly in the blood capillaries. However, RBCs have unique flow-affecting properties that play a key role in blood flow in all blood vessel types and sizes. While RBCs as oxygen carriers have been studied extensively, their hemodynamic function has been examined less comprehensively. This review aims to bridge this gap, focusing on the role of RBC flow properties in hemodynamics, hemostasis and thrombosis.

Fibrinolytic therapy in acute stroke

Acute ischemic stroke is a major cause of morbidity and mortality in Europe, North America, and Asia. Its treatment has completely changed over the past decade with different interventional approaches, such as intravenous trials, intra-arterial trials, combined intravenous/intra-arterial trials, and newer devices to mechanically remove the clot from intracranial arteries. Intravenous thrombolysis with tissue plaminogen activator (tPA) within 4.5 hours of symptoms onset significantly improved clinical outcomes in patients with acute ischemic stroke. Pharmacological intra-arterial thrombolysis has been shown effective until 6 hours after middle cerebral artery occlusion and offers a higher rate of recanalization compared with intravenous thrombolysis, whereas combined intravenous/ intra-arterial thrombolysis seems to be as safe as isolated intravenous thrombolysis. The more recent advances in reperfusion therapies have been done in mechanical embolus disruption or removal. Merci Retriever and Penumbra System have been approved for clot removal in brain arteries, but not as a therapeutic modality for acute ischemic stroke since it is no clear whether mechanical thrombectomy improves clinical outcome in acute stroke. However, mechanical devices are being used in clinical practice for patients who are ineligible for tPA or who have failed to respond to intravenous tPA. We summarize the results of the major thrombolytic trials and the latest neurointerventional approaches to ischemic stroke.

Gene expression differences between stroke-associated and asymptomatic carotid plaques

Atherosclerotic carotid stenosis is an important risk factor for stroke. Carotid plaques (CPs) causing stroke may present a distinct type of molecular pathology compared with transient ischemic attack (TIA)-associated or asymptomatic plaques. We compared the gene expression profiles of CPs from stroke patients (n = 12) and asymptomatic patients (n = 9), both with similar risk factors and severity of carotid stenosis (>70%). Sixty probes showed over 1.5-fold expression difference at 5% false discovery rate. Functional clustering showed enrichment of genes in 51 GO categories and seven pathways, the most significant of which relate to extracellular-matrix interaction, PPAR gamma signaling, scavanger receptor activity, and lysosomal activity. Differential expression of ten genes was confirmed in an extended replication group (n = 43), where the most significant expression differences were found in CD36 (2.1-fold change, p = 0.005), CD163 (1.7-fold change, p = 0.007) and FABP4 (2.2-fold change, p = 0.015). These include four genes not previously linked to plaque destabilization: GLUL (2.2-fold change, p = 0.016), FUCA1 (2.2-fold change, p = 0.025), IL1RN (1.6-fold change, p = 0.034), and S100A8 (2.5-fold change, p = 0.047). Strong correlations were found to plaque ulceration, plaque hemorrhage, and markers of apoptosis and proliferation (activated caspase 3, TUNEL, and Ki67). Protein expression of these genes was confirmed by immunohistochemistry and was found in the atheromatous areas of CPs critical for plaque destabilization. This study presents a comprehensive transcriptional analysis of stroke-associated CPs and demonstrates a significant transcriptome difference between stroke-associated and asymptomatic CPs. Follow-up studies on the identified genes are needed to define whether they could be used as biomarkers of symptomatic CPs or have a role in plaque destabilization.

Microarray analysis reveals overexpression of CD163 and HO-1 in symptomatic carotid plaques

OBJECTIVE

We studied by microarray analysis whether symptomatic and asymptomatic carotid plaques from the same patient differ in gene expression and whether the same changes are present in an independent sample set.

METHODS AND RESULTS

Carotid plaques from four patients with bilateral high-grade stenosis, one being symptomatic and the other asymptomatic, were analyzed on Affymetrix U95Av2 arrays. 33 genes showed >1.5-fold change between symptomatic and asymptomatic plaques in an intraindividual comparison with FDR ranging from 0.28 to 0.40. Three genes involved in iron-heme homeostasis, CD163, HO-1, and transferrin receptor, were further analyzed in 40 independent plaques. HO-1 (fold-change 1.93, 95%CI 1.04 to 3.94, P=0.040) and CD163 (1.58, 1.11 to 2.40, P=0.013) mRNAs were again induced, and also HO-1 protein was overexpressed in symptomatic plaques (4.38, 1.54 to 12.20, P=0.024). The expression of HO-1 and CD163 correlated with tissue iron content but iron itself was not associated with the symptom status.

CONCLUSIONS

Symptomatic plaques show overexpression of CD163 and HO-1 both in intraindividual and interindividual comparison. Their expression correlates with iron deposits but asymptomatic and symptomatic plaques from isolated patients do not differ in macroscopic hemorrhages or iron deposits. We suggest that symptomatic plaques show a more pronounced induction of CD163 and HO-1 in response to plaque hemorrhages.

Carotid endarterectomy for asymptomatic plaque

Statistical correlations are linear noninteractive relationships, but the dynamics of causation are nonlinear and involve complex interactions where variables change through their effect on one another and interact with the context of the patient over time. The discovery and interpretation of plaque vulnerable features in the individual patient are not determined for the asymptomatic patient being considered for carotid endarterectomy. New technologies for identification of plaque chemical and morphologic composition are on the horizon and may be applicable to certain patients but change in their usefulness as the plaque and patient change over time.

D-dimer local expression is increased in symptomatic patients undergoing carotid endarterectomy

BACKGROUND

Although atherosclerosis is a silent widespread disease, the focal character of the lesions triggering the clinical manifestations is unquestionable. We hypothesized that symptomatic patients with advanced, unstable carotid plaques have increased local intraplaque and circulating levels of fibrin-fibrinogen related products.

METHODS

Plaque tissue and plasma samples were studied in 106 patients undergoing endarterectomy for symptomatic and asymptomatic carotid disease. Fibrin-fibrinogen related products were evaluated by ELISA, Western-blotting, and histology. All tested parameters were compared with patient carotid symptomatology, multiple vascular risk factors (VRF), bilateral carotid pathology, ultrasound examination, and previous therapies with statins and/or antiplatelet drugs.

RESULTS

In symptomatic patients, plasma D-dimer was elevated in patients with unstable carotid plaques (UNS) compared with stable (STA) ones (857+/-121 vs. 692+/-156 ng/ml, p=0. 026). Furthermore, plasma D-dimer was significantly increased in patients with a coexistence of carotid and coronary artery disease, compared to others (976+/-325 vs. 714+/-197 ng/ml; p<0.001). Intra-plaque D-dimer content was increased in ulcerated-complicated (UC) plaques compared with fibrous non-complicated (F) plaques in symptomatic patients (5.9+/-1 vs. 1.8+/-1, p<0.001), and in patients with hypercholesterolaemia, compared with those with normal cholesterol levels (6.1+/-1 vs. 2.9+/-0.7; p=0.027). However, there was no correlation between D-dimer content in the carotid plaque and plasma D-dimer levels.

CONCLUSIONS

Hypercholesterolemia and UC plaques appear to be associated with high fibrin intraplaque turnover as demonstrated by higher intraplaque D-dimer. Plasma markers of fibrin turnover were increased in UNS plaques, and in patients with coexisting carotid and coronary artery disease. Although, both plasma and plaque D-dimers were associated with unstable carotid disease, the usefulness of the measurement of plasma D-dimer in these patients should be confirmed by prospective studies.