Adhesion molecule expression in symptomatic and asymptomatic carotid stenosis

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.

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.

Polymorphism rs5498 of the ICAM-1 gene affects the progression of carotid atherosclerosis in patients with type 2 diabetes mellitus

Background

Adhesion molecules are involved in the development of atherosclerosis. An increased level of the ICAM 1 molecule is associated with numerous inflammatory diseases including atherosclerosis of carotid arteries. The rs5498 (K469E) polymorphism of the ICAM-1 gene leads to an increase in the level of serum ICAM. We investigated the association between the rs5498 (K469E) polymorphism of the ICAM-1 gene and the progression of carotid atherosclerosis in subjects with type 2 diabetes mellitus (T2DM).

Methods

The study included 595 patients with T2DM and 200 subjects in the control group without T2DM. The control examination was made 3.8 years after the initial examination. Indicators of atherosclerosis (carotid intima-media thickness (CIMT), total plaque sum and sum of the plaques thickness) were detected by ultrasound examination. Genetic analyses of the polymorphism rs5498 of the ICAM-1 gene were made by RT-PCR.

Results

The distribution of genotypes and frequencies of rs5498 polymorphism was not significantly different between the group with type 2 diabetes ( T2DM) and the control group. Genotype EE K469E polymorphism is associated with a statistically significant annual plaques growth.

Conclusion

The EE genotype of the rs5498 of the ICAM-1 gene was associated with a more rapid progression of carotid atherosclerosis in patients with T2DM in comparison with other genotypes.

Life-Threatening Coronary Disease is Prevalent in Patients with Stenosing Carotid Artery Disease

Background

Atherosclerosis affects several vascular trees systemically and though surgical plaque removal diminishes the risk of stroke in patients with carotid stenosis, they still face a risk of other atherothrombotic complications like myocardial infarction and premature death.

Aims and/or hypothesis

This study was designed to reveal the long-term risk of death and atherothrombotic events following carotid endarterectomy.

Methods

Eighty-nine previously (1997–2000) endarterectomized carotid patients (56–92 years) were followed up to 15·2 years. Causes of death, cardiovascular events (stroke, transient ischemic attack, acute myocardial infarction), comorbidities, and medications were recorded and analyzed by Cox regression analysis. Four population controls and four controls with coronary disease ( n = 712) were selected for each case from a population cohort for age- and gender-matched analysis.

Results

At the end of follow-up, 41 (44·6%) patients had died and 48 were alive. Ten patients (24,4%) died due to acute myocardial infarction and one (2,4%) due to stroke. Nineteen (21%) patients had an acute myocardial infarction, 12 (13%) had a stroke, 13 (15%) had a transient ischemic attack, and 5 (6%) had other atherothrombotic events. The risk of death was 5·7-fold in diabetics ( P < 0·001) and 3·9-fold in smokers ( P < 0·001). Patients who did not use statins had 5·0-fold, and irregular users 3·3-fold risk of death compared with active users ( P = 0·005 and P = 0·001, respectively). The major factors associated with acute myocardial infarction were diabetes (6·0-fold risk, P = 0·004), bilateral carotid disease (3·5-fold risk, P = 0·014), and lack of statin use (4·4-fold risk, P = 0·038). Compared with population controls, carotid patients had a 4·4-fold risk of acute myocardial infarction ( P = 0·002).

Conclusions

Endarterectomized carotid patients have a high risk of acute myocardial infarction and death, and need an intensified cardiovascular disease-risk-lowering treatment. Although asymptomatic, the evaluation of prognostically significant myocardial ischemia should be considered in these high-risk patients. Eventually, a clinical trial is needed to address whether carotid patients would benefit from early intervention.

The impact of uric acid on long-term mortality in patients with asymptomatic carotid atherosclerotic disease

BACKGROUND

Serum uric acid (SUA) has been discussed to be related to cardiovascular (CV) disease and outcome. We investigated whether levels of SUA predict long-term mortality in neurologically asymptomatic patients with carotid atherosclerotic disease.

METHODS

We prospectively studied 959 consecutive patients with carotid atherosclerosis as evaluated by duplex Doppler sonography for all-cause and CV death, respectively.

RESULTS

During a median follow-up time of 6.3 years (interquartile range [IQR], 5.4-7.1 years), 246 deaths (25.7%), including 160 CV deaths (16.7%), were recorded. Median baseline SUA levels were 5.9 mg/dL (IQR, 5.0-7.0 mg/dL). SUA was significantly associated with all-cause death and CV death. Adjusted hazard ratios (HRs) for an increase of 1 mg/dL of SUA levels were 1.12 (95% confidence interval [CI], 1.04-1.21; P = .003) and 1.20 (95% CI, 1.11-1.30; P < .001) for all-cause and CV death, respectively. Quartiles of SUA levels showed a significant association with CV mortality (log-rank P = .002). For CV death, adjusted HRs for quartiles of increasing SUA levels were 1.45 (95% CI, .87-2.43), 1.44 (95% CI, .85-2.46), and 2.26 (95% CI, 1.36-3.76; P < .01), compared with the lowest quartile, respectively. Patients with baseline carotid stenosis of more than 50% and/or increased levels of SUA (≥median) had an approximately 2-fold increase in risk of (CV) death, compared with patients with carotid narrowing of less than 50% and/or SUA levels less than the median (P < .001).

CONCLUSIONS

Levels of SUA represent independent predictors for CV mortality in a cohort of patients with asymptomatic carotid atherosclerosis.

Low-expression variant of fatty acid-binding protein 4 favors reduced manifestations of atherosclerotic disease and increased plaque stability

BACKGROUND

Fatty acid-binding protein 4 (FABP4 or aP2 in mice) has been identified as a key regulator of core aspects of cardiometabolic disorders, including lipotoxic endoplasmic reticulum stress in macrophages. A functional promoter polymorphism (rs77878271) of human FABP4 gene has been described resulting in reduced FABP4 transcription.

METHODS AND RESULTS

We investigated the effects of this low-expression variant of FABP4 on cardiovascular morbidity and carotid atherosclerosis on a population level (n=7491) and in patient cohorts representing endarterectomized patients with advanced carotid atherosclerosis (n=92) and myocardial infarction (n=3432). We found that the low-expression variant was associated with decreased total cholesterol levels (P=0.006) with the largest reduction in variant allele homozygotes. Obese variant allele carriers also showed reduced carotid intima-media thickness (P=0.010) and lower prevalence of carotid plaques (P=0.060). Consistently, the variant allele homozygotes showed 8-fold lower odds for myocardial infarction (P=0.019; odds ratio, 0.12; 95% confidence interval, 0.003-0.801). Within the carotid plaques, the variant allele was associated with a 3.8-fold reduction in FABP4 transcription (P=0.049) and 2.7-fold reduction in apoptosis (activated caspase 3; P=0.043). Furthermore, the variant allele was enriched to patients with asymptomatic carotid stenosis (P=0.038). High FABP4 expression in the carotid plaques was associated with lipid accumulation, intraplaque hemorrhages, plaque ulcerations, and phosphoactivated endoplasmic reticulum stress markers.

CONCLUSIONS

Our results reveal FABP4 rs77878271 as a novel variant affecting serum total cholesterol levels and cardiovascular risk. A therapeutic regimen reducing FABP4 expression within the atherosclerotic plaque may promote lesion stability through modulation of endoplasmic reticulum stress signaling, and attenuation of apoptosis, lipid burden, and inflammation.

Coronary and carotid atherosclerosis: similarities and differences

Although a relationship is commonly accepted between coronary and carotid arterial disease, suggesting that atherosclerosis is a systemic condition, the extent of this association and correspondence has not been fully elucidated. This review discusses recent research in this field and highlights areas for future study. The prevalence of severe carotid stenosis increases with prevalence of coronary stenosis, with the latter being found in a significant number of stroke patients, while those with carotid stenosis may be at higher risk of myocardial infarction than stroke. There also appear to be common risk factors (age, diabetes, hypertension, smoking and dyslipidemia), although the effects in both vascular systems may not be identical. Furthermore, while the degree of stenosis in the coronary artery has little ability to predict acute coronary syndrome, which is caused by local thrombosis from a ruptured or eroded plaque, severe carotid stenosis causing hypoperfusion is highly predictive of stroke, although this effect may be time-limited. This apparent difference in event mechanism in the two arteries is interesting as is the difference in the rate of development of collaterals. Overall, the evidence shows that a clear relationship exists between disease in the coronary and carotid arteries, since conventional risk factors and the extent of stenosis and/or previous events emanating from one artery have a strong bearing on the prevalence of events in the other artery. Nevertheless, the exact correspondence between the two arteries is unclear, with sometimes contradictory study results. More research is needed to identify the full extent of risk factors for severe stenosis and cardio- or cerebral vascular events, among which, inflammatory biomarkers such as hs-CRP and prior vascular events are likely to play a key role.

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.

Improved identification of endothelial erosion by simultaneous detection of endothelial cells (CD31/CD34) and platelets (CD42b)

Loss of endothelial cells (ECs) with ensuing exposure of thrombogenic subendothelial surface is a common cause of thromboembolic complications in atherosclerotic arteries. Thus, endothelial denudation has emerged as a major contributor to the pathogenesis of atherosclerosis and its complications. Despite ongoing efforts in elucidating the pathogenesis of endothelial erosions in human atherosclerotic arteries, the mechanisms of erosion have remained enigmatic, partly due to lack of well-established methods for its identification. Here the authors point out plausible pitfalls in the current methodology and provide an improved immunohistochemical method for identifying endothelial erosion; i.e., immunofluorescence double staining with antibodies against CD42b and CD31/CD34. This method enables reliable detection of ECs and platelets in the same staining by allowing detection of "pseudoendothelium" caused by CD31 staining of a thin platelet layer covering sites of endothelial erosion. As erosion with a luminal platelet thrombus is likely to represent an in vivo erosion, and erosion without platelets an ex vivo artefact, the method makes it possible to exclude artefactual erosions resulting from sample processing. The novel immunostaining protocol presented here allows more reliable detection of endothelial erosions and so may facilitate studies on the mechanisms involved in the pathogenesis of plaque erosion and acute coronary syndromes.

Distinctive expression of chemokines and transforming growth factor-beta signaling in human arterial endothelium during atherosclerosis

Knowledge about the in vivo role of endothelium in chronic human atherosclerosis has mostly been derived by insights from mouse models. Therefore, we set out to establish by microarray analyses the gene expression profiles of endothelium from human large arteries, as isolated by laser microbeam microdissection, having focal atherosclerosis of the early or the advanced stage. Within individual arteries, the endothelial transcriptomes of the lesional and unaffected sides were compared pairwise, thus limiting genetic and environmental confounders. Specific endothelial signature gene sets were identified with changed expression levels in either early (n = 718) or advanced atherosclerosis (n = 403), relative to their paired plaque-free controls. Gene set enrichment analysis identified distinct sets of chemokines and differential enrichments of nuclear factor-kappaB-, p53-, and transforming growth factor-beta-related genes in advanced plaques. Immunohistochemistry validated the discriminative value of corresponding endothelial protein expression between early (fractalkine/CX3CL1, IP10/CCL10, TBX18) or advanced (BAX, NFKB2) stages of atherosclerosis and versus their plaque-free controls. The functional involvement of transforming growth factor-beta signaling in directing its downstream gene repertoire was substantiated by a consistent detection of activated SMAD2 in advanced lesions. Thus, we identified truly common, local molecular denominators of pathological changes to vascular endothelium, with a marked distinction of endothelial phenotype between early and advanced plaques.

Adipophilin expression is increased in symptomatic carotid atherosclerosis: correlation with red blood cells and cholesterol crystals

BACKGROUND AND PURPOSE

Adipophilin is an adipose differentiation-related protein expressed in lipid-containing cells. Using DNA microarray analysis, we previously found the adipophilin gene (ADFP) to be overexpressed in symptomatic carotid plaques (CP). This led us to further examine the role of adipophilin in carotid atherosclerosis relative to symptom status.

METHODS

Ninety-eight high-grade (>70%) CPs were obtained in carotid endarterectomy. The relative expression of ADFP mRNA was measured by quantitative real-time RT-PCR, and the relative amount of adipophilin protein was quantified with Western blotting. Detailed topographical correlations with extravasated red blood cells and extracellular cholesterol crystals were obtained by means of immunohistochemistry.

RESULTS

The relative expression of ADFP mRNA was increased in symptomatic compared with asymptomatic CPs at both the mRNA level (1.82+/-0.19[SE] versus 1.25+/-0.15, P=0.012) and the protein level (1.04+/-0.23 versus 0.46+/-0.14, P=0.043). Adipophilin colocalized with macrophage foam cells, extravasated red blood cells (P<0.0001), and cholesterol crystals (P<0.0001), and its expression associated with macroscopic ulceration of CP (P<0.0001).

CONCLUSIONS

Intraplaque hemorrhages may contribute to intracellular lipid accumulation and consequent adipophilin expression. Because adipophilin blocks cholesterol efflux from lipid-laden cells, they may die and develop a necrotic lipid core, thereby destabilizing the plaque.

Relationships between free radical levels during carotid endarterectomy and markers of arteriosclerotic disease

BACKGROUND

Free radical production is elevated in jugular venous blood emerging from the brain in conjunction with carotid endarterectomy. This study explores the relationships between markers for lesion progression in arteriosclerosis, production of radicals and clinical characteristics.

METHODS

The radical production during carotid endarterectomy was studied in 13 patients with an ex vivo spin trap method using OXANOH as a spin trap. MCP-1, ICAM-1, MMP-9 and oxLDL were determined in venous blood samples before, during and after clamping of the carotid artery. Principal component analysis (PCA) as well as partial least square regression analysis (PLS) was applied to interpret the data.

RESULTS

PCA and PLS analysis revealed that high values of MMP-9 and low values of ICAM-1 were associated with high radical production whereas MCP-1 and oxLDL were not correlated to radical production. MMP-9 was elevated at diabetes, high haemoglobin, high leucocyte counts and thrombocyte counts as well as at contralateral stenosis, whereas ICAM-1 showed reversed relationships to these clinical variables. MCP-1 increased during surgery.

CONCLUSIONS

The main finding in our study is that MMP-9 in plasma is asscociated with radical production during carotid endarterectomy, suggesting that this enzyme might be involved in the pathogenesis of brain damage in conjunction with ischaemia-reperfusion.

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.

Endothelial Apoptosis Does Not Determine Symptom Status in Carotid Artery Disease

BACKGROUND

We examined the hypothesis that endothelial denudation in advanced carotid plaques (CPs) occurs by increased apoptosis of endothelial cells (ECs) using scanning electron microscopy (SEM) as well as markers of cellular proliferation and apoptosis in advanced symptomatic CPs (SCPs) and asymptomatic CPs (ACPs).

METHODS

93 consecutive patients underwent carotid endarterectomy. Five additional specimens were studied by SEM. We performed TUNEL assays, and immunostaining against Fas receptor (FasR), Fas ligand (FasL), activated caspase 3 (ACA3) and Ki-67.

RESULTS

SEM revealed morphological changes consistent with EC detachment. Surprisingly, ACA3 positivity was more pronounced on the endothelium of ACPs (4.6 +/- 0.7% of total EC count) than on SCPs (3.3 +/- 0.7%, p = 0.049), and was found to correlate positively with nuclear Ki-67 expression (r(s) = 0.275, p = 0.040). FasL expression was significantly increased on the endothelium of SCPs compared with ACPs (66.4 +/- 4.4 vs. 53.9 +/- 4.5%, p = 0.047).

CONCLUSIONS

Absence of increased positivity of apoptotic markers dismisses apoptosis as a dominant mechanism underlying endothelial detachment of SCPs. Rather, increased ACA3 with co-expression of Ki-67 in ACPs might suggest that renewal of endothelium by active cell turnover may contribute to clinically silent evolution of plaques with preserved EC integrity. These observations may assist in designing novel therapies to prevent endothelial decay and symptom generation in advanced carotid artery disease.

Evidence, education and practice

Stroke causes greater loss of quality-adjusted life years than any other disease and is also one of the most expensive disorders. The burden of stroke will increase in the future due to change in the age structure of populations. We have a vast body of evidence on how to prevent stroke and how to treat stroke patients. Good examples are treatment of hypertension, antithrombotic agents and carotid surgery in stroke prevention, thrombolysis in ischaemic stroke and stroke unit care for all stroke patients. We only have to translate scientific evidence into daily practice. If some pieces are missing, it is our duty to generate them through research. While taking part in randomized clinical trials (RCTs), the discipline, an essential part of RCTs, will improve the daily care of all stroke patients. Besides RCTs there are many other sources of scientific evidence for stroke management, one of which is the European Stroke Initiative (EUSI). The mission of the EUSI is to improve and optimize stroke management in Europe through education and by offering best practice guidelines. Also national and international societies and organizations play an important role in providing education. The human factor is one obstacle to more successful stroke management because to be more effective we must change our own clinical routine. We can make a difference by applying available evidence to our daily practice.

Predictive value of soluble intercellular adhesion molecule-1 for risk of ischemic events in individuals with cerebrovascular disease

BACKGROUND AND PURPOSE

Cellular adhesion molecules may play a critical role in the inflammatory process leading to atherosclerosis. The purpose of this study was to determine whether soluble intercellular adhesion molecule-1 (sICAM-1) is a predictor of future ischemic events in high-risk individuals and also whether it is associated with carotid artery stenosis.

METHODS

We conducted a prospective study of sICAM-1 concentration in 3 groups: (1) subjects with recent (< 7 days) ischemic stroke or TIA, (2) asymptomatic subjects with carotid stenosis > or = 50% and (3) asymptomatic individuals with vascular risk factors. Subjects were followed for a minimum of 3 years. sICAM-1 levels were compared between the groups and correlated with the risk of ischemic events and the degree of carotid artery stenosis.

RESULTS

We studied 275 subjects. Mean sICAM-1 levels were significantly higher in those with recent ischemic stroke or TIA compared to those with risk factors alone. During follow-up, ischemic events occurred almost nine times more frequently in subjects in group 1 compared to group 3. sICAM-1 concentration was not predictive of future ischemic events (OR 1.001, 95% CI 0.998-1.004). There was no significant association between sICAM-1 concentration and carotid artery stenosis (OR 1.001, 95% CI 0.999-1.004).

CONCLUSIONS

Mean sICAM-1 levels were higher in subjects with recent cerebral ischemia. No association between sICAM-1 and carotid artery stenosis was observed. Neither baseline nor subsequent sICAM-1 levels were predictive of the risk of future ischemic events.

Pleiotropic effects of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors on renal function

Pleiotropic, or non-lipid-dependent, effects mediated by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have important clinical implications for the cardiovascular (CV) system. Atherosclerosis is an inflammatory process accompanied by increases in levels of plasma inflammatory markers and accumulation of immune cells within atherosclerotic plaques. Statins not only decrease serum lipid levels, but also inhibit signaling molecules at several points in inflammatory pathways. The anti-inflammatory effects and improved endothelial function associated with statin therapy are thought to be partly responsible for the reduction in CV morbidity and mortality. In analogy, patients with chronic kidney disease administered statins for CV risk reduction show evidence of improved renal function. However, whether statins confer similar protective benefits on the kidney has not been established. Several lines of evidence suggest that similar etiologic and pathological processes may be involved in CV and chronic kidney diseases. If inflammation and functional changes in the renovascular endothelium contribute to the progression of kidney disease, statins are likely to be effective in the treatment of renal disease. In this review, we critically consider emerging data indicating that statins may modulate renal function by altering the inflammatory response of the kidney and renal vasculature to dyslipidemia. Whether the amelioration of renal function by statins is separable from the lipid-lowering effects of these drugs still remains to be delineated. Other questions that remain to be addressed and issues that should be investigated also are presented.

Heme Oxygenase-1 Is Expressed in Carotid Atherosclerotic Plaques Infected byHelicobacter pyloriand Is More Prevalent in Asymptomatic Subjects

BACKGROUND AND PURPOSE

It is not well established what are the features, if any, that distinguish symptomatic from asymptomatic carotid atherosclerotic plaques. Inducible heme oxygenase-1 (HO-1) is a component of cellular defense mechanisms against oxidative stress. We aimed to assess the presence of Helicobacter pylori (H pylori) and the expression of HO-1 in carotid atherosclerotic plaques of patients with and without prior neurologic symptoms attributable to the operated artery.

METHODS

We examined 25 symptomatic and 23 asymptomatic carotid atherosclerotic plaques removed during endarterectomy and 7 normal carotid arteries obtained at autopsy. We investigated the presence of H pylori DNA in the vessel wall and performed immunohistochemical detection of HO-1.

RESULTS

H pylori DNA was present in 28 plaques and HO-1 was expressed in 30 plaques. HO-1 was found in 27 H pylori-positive specimens but in only 3 H pylori-negative specimens (P<0.001). All 7 normal carotid arteries were negative for both H pylori and HO-1. Although 82% of asymptomatic specimens were positive for H pylori and 87% for HO-1, only 36% of symptomatic specimens were positive for both H pylori and HO-1 (P<0.01).

CONCLUSIONS

This study suggests a strong association between H pylori infection and expression of HO-1 in carotid atherosclerotic plaques. There was a substantial prevalence of these features in specimens obtained from asymptomatic subjects.

Are 3-Hydroxy-3-Methylglutaryl-CoA Reductase Inhibitors Renoprotective?: Table 1

Statins reduce serum cholesterol and cardiovascular morbidity and mortality. The mechanisms for these beneficial effects are reviewed. Altered inflammatory responses and improved endothelial function mediated by statins are thought to be partly responsible for the reduction of morbidity and mortality as a result of cardiovascular events. In analogy, whether statins confer similar benefits on the kidney has not been established. This review critically considers the available data whereby dyslipidemia mediates renal dysfunction by modulating the inflammatory response to diverse cytokines. Also reviewed is the emerging database indicating that statins may modulate renal function by altering the response of the kidney to dyslipidemia.

Associations of soluble intercellular adhesion molecule-1 with carotid atherosclerosis progression

Our previous study demonstrated that plasma concentration of high-sensitivity C-reactive protein (hs-CRP) is a marker of carotid atherosclerosis activity. In this study, we investigated whether plasma levels of soluble cell adhesion molecules have potential value to predict atherosclerosis progression. The study included 192 outpatients 40-82 years of age who were treated for traditional risk factor for cardiovascular disease. Patients underwent repeated ultrasonographic evaluation for 53+/-11 months. Severity of atherosclerosis was evaluated by the maximal intimal-medial thickness (max-IMT), plaque number (PN) and plaque score (PS, the sum of all plaque thicknesses). Blood samples were collected for measurement of hs-CRP, soluble intercellular adhesion molecule (sICAM-1) and sP-selectin at the time of baseline examination. The development of atherosclerosis was estimated by the formula: Deltavalue/year=(last value-baseline value)/number of follow-up years. Multivariate linear regression analysis revealed that sICAM-1 was associated with DeltaIMT/year and DeltaPS/year, which was not the case for sP-selectin. sICAM-1 was closely associated with DeltaIMT/year especially in patients with apparent atheromatous plaque. Our results suggested that levels of sICAM-1 might have predictive value of progression of carotid atherosclerosis independently of traditional risk factors and hs-CRP.

Inflammation and infections as risk factors for ischemic stroke

BACKGROUND

Inflammatory processes have fundamental roles in stroke in both the etiology of ischemic cerebrovascular disease and the pathophysiology of cerebral ischemia. We summarize clinical data on infection and inflammation as risk or trigger factors for human stroke and investigate current evidence for the hypothesis of a functional interrelation between traditional risk factors, genetic predisposition, and infection/inflammation in stroke pathogenesis.

SUMMARY OF REVIEW

Several traditional vascular risk factors are associated with proinflammatory alterations, including leukocyte activation, and predispose cerebral vasculature to thrombogenesis on inflammatory stimulation. Furthermore, accumulation of inflammatory cells, mainly monocytes/macrophages, within the vascular wall starts early during atherogenesis. During later disease stages, their activation can lead to plaque rupture and thrombus formation, increasing stroke risk. Inflammatory markers (eg, leukocytes, fibrinogen, C-reactive protein) are independent predictors of ischemic stroke. Chronic infections (eg, infection with Chlamydia pneumoniae or Helicobacter pylori) were found to increase the risk of stroke; however, study results are at variance, residual confounding is not excluded, and causality is not established at present. In case-control studies, acute infection within the preceding week was a trigger factor for ischemic stroke. Acute and exacerbating chronic infection may act by activating coagulation and chronic infections and may contribute to atherogenesis. Genetic predisposition of the inflammatory host response may be an important codeterminant for atherogenesis and stroke risk.

CONCLUSIONS

Inflammation contributes to stroke risk via various interrelated mechanisms. Infectious diseases, traditional risk factors, and genetic susceptibility may cooperate in stimulating inflammatory pathways. Final proof of a causal role of infectious/inflammatory mechanisms in stroke pathogenesis is still lacking and will require interventional studies.