Immunomodulation of atherosclerosis: myth and reality

Dyslipidemia Diagnosis and Treatment: Risk Stratification in Children and Adolescents

Dyslipidemias or dyslipoproteinemias are quantitative changes in total cholesterol concentration, respective fractions, or triglycerides in the plasma. Evidence supported that dyslipidemia in childhood is associated with atherosclerosis in adulthood, and early identification and treatment potentially reduce cardiovascular risk in adulthood, which is the principal cause of morbidity and mortality in developed countries. Dyslipidemias can result from primary lipoprotein metabolism changes due to different genetic causes (primary dyslipidemias) or as a consequence of exogenous factors or other pathologies (secondary dyslipidemias). Therefore, the combined dyslipidemias result from the association of important epigenetic and environmental influences with risk factors for cardiovascular disease. The criterion for lipid metabolism screening at young ages is not widely accepted and possibly follows a universal or directed screening strategy. Additionally, little is known about its long-term effects or possible risk-benefit despite the growing tendency to start pharmacological therapy. Therefore, this study aimed to review the available bibliography on dyslipidemia in pediatric age to present a practical and structured approach to dyslipidemia that focuses on screening, risk stratification for atherosclerotic disease, and therapeutic approach.

Rationale and design of a randomized controlled trial of pneumococcal polysaccharide vaccine for prevention of cardiovascular events: The Australian Study for the Prevention through Immunization of Cardiovascular Events (AUSPICE)

BACKGROUND

Research has shown that vaccination with Streptococcus pneumoniae reduced the extent of atherosclerosis in experimental animal models. It is thought that phosphorylcholine lipid antigens in the S. pneumoniae cell wall induce the production of antibodies that cross-react with oxidized low-density lipoprotein, a component of atherosclerotic plaques. These antibodies may bind to and facilitate the regression of the plaques. Available data provide evidence that similar mechanisms also occur in humans, leading to the possibility that pneumococcal vaccination protects against atherosclerosis. A systematic review and meta-analysis, including 8 observational human studies, of adult pneumococcal polysaccharide vaccination for preventing cardiovascular disease in people older than 65 years, showed a 17% reduction in the odds (odds ratio 0.83, 95% CI 0.71-0.97) of having an acute coronary syndrome event.

METHODS/DESIGN

The AUSPICE is a multicenter, randomized, placebo-controlled, double-blind, clinical trial to formally test whether vaccination with the pneumococcal polysaccharide vaccine protects against cardiovascular events (fatal and nonfatal acute coronary syndromes and ischemic strokes). Cardiovascular outcomes will be obtained during 4 to 5 years of follow-up, through health record linkage with state and national administrative data sets.

CONCLUSION

This is the first registered randomized controlled trial (on US, World Health Organization, Australia and New Zealand trial registries) to be conducted to test whether vaccination with the pneumococcal polysaccharide vaccine will reduce cardiovascular events. If successful, vaccination can be readily extended to at-risk groups to reduce the risk of cardiovascular diseases.

Atheroprotective effects of Cuphea carthagenensis (Jacq.) J. F. Macbr. in New Zealand rabbits fed with cholesterol-rich diet

ETHNOPHARMACOLOGICAL RELEVANCE

Although Cuphea carthagenensis (Jacq.) J. F. Macbr. is used in Brazilian folk medicine in the treatment of atherosclerosis and circulatory disorders, no study evaluating these effects has been conducted. The aim of this study was to evaluate the possible hypolipemiant and antiatherogenic activity of the ethanol soluble fraction obtained from C. carthagenensis (ES-CC) in an experimental atherosclerosis model using New Zealand (NZ) rabbits undergoing cholesterol-rich diet (CRD).

MATERIAL AND METHODS

Dyslipidemia and atherogenesis were induced by administration of standard commercial diet increased of 1% cholesterol (CRD) for 8 weeks. ES-CC was orally administered at doses of 10, 30 and 100mg/kg, once daily for four weeks, starting from the 4th week of CRD diet. Body weight measurements were weekly carried out from the beginning of experiments for 8 weeks. Serum levels of triglyceride (TG), total cholesterol (TC) and their fractions (LDL-C, VLDL-C and HDL-C) were measured at the beginning of experiments and at weeks four and eight. After euthanasia of rabbits, aorta segments (aortic arc, thoracic, abdominal and iliac segments) were macroscopically and microscopically evaluated and the intima and media layers of the arteries were measured. Additionally, the antioxidant activity of ES-CC and its influence on the functioning of hepatic antioxidant enzymes were also determined.

RESULTS

CRD induced dyslipidemia and major structural changes in the aortic wall. In addition, an increase in lipid peroxidation and a reduction of hepatic glutathione and serum nitrite levels were observed. Treatment with ES-CC was able to prevent the increase in TC, LDL-C, VLDL-C levels and triglycerides and promoted an increase in HDL-C levels in NZ rabbits. These effects were accompanied by a significant reduction in oxidative stress and modulation of the catalase and superoxide dismutase function. Moreover, the intima and media layers of the arterial segments were significantly reduced by ES-CC treatment.

CONCLUSIONS

This study demonstrated that ES-CC reduces serum lipids and hepatic oxidative stress when orally administered to NZ rabbits. In addition, it was able to prevent the development of CRD-induced atherosclerosis.

Reality of a Vaccine in the Prevention and Treatment of Atherosclerosis

Atherosclerosis together with multiple sclerosis, psoriasis and rheumatoid arthritis can be used as examples of chronic inflammatory diseases associated with multifactorial components that evolve over the years. Nevertheless, an important difference between these diseases relies on the fact that atherosclerosis develops from early ages where inflammation dominates the very beginning of the disease. This review highlights the inflammatory nature of atherosclerosis and the role the immune system plays in the process of atherogenesis. Although treatment of atherosclerosis has been for years based on lipid-lowering therapies reducing a series of risk factors, the degree of success has been only limited because cardiovascular complications related to the evolution of atherosclerotic lesions continue to appear in the population worldwide. In this sense, alternative treatments for atherosclerosis have come into play where both innate and adaptive immunity have been proposed to modulate atherosclerosis-associated inflammatory phenomena. When tested for their atheroprotective properties, several immunogens have been studied through passive and active immunization with good results and, therefore, the strategy through vaccination to control the disease has been made possible. Many experimental pre-clinical studies demonstrating proof of concept that vaccination using DNA and protein with an effective use of adjuvants and the optimal route of administration now provide a tangible new therapeutic approach that sets the stage for several of these vaccines to be tested in large, randomized, long-term clinical studies. A vaccine ready for human use will only be accomplished through the close association between academia, regulatory government organizations and private industry, allowing the reality of a simple and successful therapy to reduce atherosclerosis and its severe clinical complications.

Effect of flaxseed on choroid-sclera complex thickness and on LDL oxidation in the sclera, choroid and retina of diet-induced hypercholesterolaemic rabbits

The aim of the present study was to evaluate the effect of flaxseed on choroid-sclera complex thickness and on LDL oxidation in the sclera, choroid and retina of diet-induced hypercholesterolaemic rabbits. New Zealand male albino rabbits (n 21) were divided into two groups: group 1 (G1; n 11), fed a hypercholesterolaemic diet, and group 2 (G2; n 10), fed a hypercholesterolaemic diet enriched with flaxseed flour. The serum concentrations of total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol, TAG and fasting blood glucose were determined at the start of the experiment and on the day of killing (8th week). Choroid and sclera samples were subjected to haematoxylin-eosin (HE) staining and histomorphometric and immunohistochemical analyses with the anti-oxidised LDL antibody. Sensory retina samples were subjected to an immunohistochemical analysis with the primary monoclonal nitrotyrosine antibody. At the end of the experiment, a significant increase was observed in TC and LDL-C concentrations in G1 rabbits when compared with G2 rabbits (P= 0·008 and P= 0·02, respectively). HE staining revealed a significant increase in choroid-sclera complex thickness in G1 rabbits when compared with G2 rabbits (P< 0·001). Immunohistochemical analysis of choroid and sclera samples with the anti-oxidised LDL marker revealed a significant increase in immunoreactivity in G1 rabbits when compared with G2 rabbits (P< 0·001). Immunohistochemical analysis of sensory retina samples with the anti-nitrotyrosine marker revealed a significant increase in immunoreactivity in G1 rabbits when compared with G2 rabbits (P= 0·002). Flaxseed reduced the choroid-sclera complex thickness of diet-induced hypercholesterolaemic rabbits and the expression of oxidised LDL in the choroid-sclera complex as well as the expression of nitrotyrosine in the sensory retina.

Effect of olmesartan on leukocyte recruitment in choroid-sclera complex in hypercholesterolemia model

PURPOSE

Demonstrate that the blockade of angiotensin II AT-1 receptors, through the systemic administration of olmesartan, can reduce the MCP-1 expression and the resulting macrophage accumulation in the choroid and sclera of hypercholesterolemic rabbits.

METHODS

Thirty-two New Zealand rabbits were divided into 3 groups: group I (GI) was fed a standard rabbit diet; group II (GII) was fed a hypercholesterolemic diet; and group III (GIII) was fed a hypercholesterolemic diet plus olmesartan. Serum levels of total cholesterol, triglyceride, HDL cholesterol, and blood glucose were determined in fasting rabbits at the beginning of the experiment and on the day of euthanasia. The choroid and sclera were submitted to morphometric analysis as well as immunohistochemical analysis with MCP-1 and RAM-11 (macrophage marker) antibodies.

RESULTS

No abnormality was detected in GI. Group II and III had significant increases in choroid-sclera complex thicknesses when compared with group I (P<0.001). GII showed a significant increase in immunoreactivity for MCP-1 in relation to GI (P=0.001) and GIII (P=0.004). GII showed a significant increase in immunoreactivity for RAM-11 of the choroid-sclera complex in relation to GI (P<0.001) and GIII (P=0.034). A significant increase in immunoreactivity for RAM-11 was observed in GIII in relation to GI (P=0.008).

CONCLUSION

Olmesartan reduced the MCP-1 expression and the resultant macrophage accumulation in the choroid-sclera complex of hypercholesterolemic rabbits.

Role of apolipoprotein E in renal damage protection

It is well-known that nephrotic syndrome and chronic renal failure are associated with lipid and lipoprotein abnormalities. For a long time, it has been thought that hyperlipidemia is a secondary and insignificant condition of these renal injuries. Recently, it has been shown that dyslipidaemia may contribute to the development and progression of chronic kidney disease. Apolipoprotein E (apoE) null mice are a very popular model for studying spontaneous hypercholesterolemia, but only limited data are available for the role of apolipoprotein E in kidney disease. The purpose of this study is to evaluate kidney disease in apolipoprotein E deficient mice. For this study, apoE null mice and control mice at different ages (6 weeks and 15 months) were used. Kidney morphological damage and proteins involved in oxidative stress and aging (TNF-α and NF-kB) were analyzed. ApoE deficient mice have morphological alterations that are the hallmark of kidney pathogenesis, which increase with the age of the animals. In apoE null mice kidneys, there is also increased oxidative stress as compared to control mice at the same age and fewer antioxidant enzymes. Our findings add to the growing list of protective effects that apoE possesses.

The relationship between brachial ankle pulse wave velocity and complement 1 inhibitor

Complement 1 (C1) inhibitor is an acute phase protein with anti-inflammatory properties. The aim of the present study was to elucidate the relationship between brachial ankle pulse wave velocity (baPWV), the parameter of arterial stiffness, and C1 inhibitor. One hundred subjects were randomly enrolled in this study. Data about baPWV, age, gender, hypertension, smoking, and body mass index (BMI) were measured. Blood tests for total cholesterol, low density lipoprotein, high density lipoprotein, triglycerides, hemoglobin A1c, erythrocyte sedimentation rate, C-reactive protein, complement 3, and C1 inhibitor were performed. Based on the Pearson correlation, the C1 inhibitor showed a positive relation to the baPWV (P<0.001). Multiple regression analysis revealed the significant predictors of baPWV were not only the conventional risk factors of arteriosclerosis and/or atherosclerosis, such as age (P<0.001), gender (P<0.001), hypertension (P<0.001), and BMI (P=0.006), but also the acute phase protein, C1 inhibitor (P=0.025). In conclusion, C1 inhibitor is associated with arterial stiffness through its association with increased inflammation.

Vascular oxidative stress increases dendritic cell adhesion and transmigration induced by homocysteine

Atherosclerosis is a long-term chronic inflammatory and immunological disease. Endothelial dysfunction and the dendritic cell (DC) immune response are pivotal early events in atherogenesis. This study investigated the effects and possible mechanisms of action of homocysteine (Hcy) on DC adhesion to and transmigration between endothelial cells (ECs), and indicated a novel immunoregulatory mechanism by which Hcy induces atherogenesis. When ECs were stimulated with increasing concentrations of Hcy, immunofluorescence showed that endothelial reactive oxygen species (ROS) generation strikingly increased, while nitrite assay showed that nitric oxide (NO) release markedly decreased. Furthermore, DC adhesion and transmigration were significantly increased when ECs were activated by Hcy. However, pretreatment of ECs with antioxidant before Hcy markedly attenuated the induction of DC adhesion and transmigration, dependent on the intracellular ROS decrease and endothelial NO increase. In conclusion, DC adhesion and transmigration are significantly increased by vascular oxidative stress under conditions of elevated Hcy levels. These findings provide insight into the inflammatory processes and immune responses occurring in atherosclerosis induced by Hcy.

Secreted phospholipase A2 type IIA as a mediator connecting innate and adaptive immunity: new role in atherosclerosis

AIMS

Human atherosclerotic plaques express markers of macrophage/dendritic cells as well as high levels of inflammatory proteins such as secreted phospholipase A(2) type IIA (sPLA(2)-IIA). To understand the cellular changes associated with the progress of atherosclerosis, we evaluated the role of sPLA(2)-IIA in mediating monocyte recruitment and differentiation into antigen-presenting cells.

METHODS AND RESULTS

The effect of sPLA(2)-IIA on monocyte differentiation was evaluated in human THP-1 cells, a cellular line widely used as a model for monocyte-macrophage differentiation. Changes in functional processes, morphology and expression of antigens, characteristic of differentiated cells, were monitored over a 1-3 day period. sPLA(2)-IIA inhibited CD14 expression in a time- and concentration-dependent manner and upregulated dendritic cell-specific ICAM-3 grabbing non-integrin levels at the cell surface, findings that were the same for human monocytes. In addition, sPLA(2)-IIA-differentiated cells showed a dendritic cell phenotype characterized by the generation of fine dendritic protrusions and an increase in surface markers such as CD40, CD83, CD54, CD61, and CD62L. Furthermore, cell adhesion, migration, endocytic activity, and allogeneic T cell proliferation capacity were markedly increased after sPLA(2)-IIA treatment.

CONCLUSION

sPLA(2)-IIA induces the differentiation of mononuclear cells and increases their adhesive and migratory capabilities, which suggests a novel function for sPLA(2)-IIA as a mediator connecting innate and adaptive immunity. These findings may provide insight into the immuno-inflammatory processes occurring in atherosclerosis, helping us to understand the cellular changes associated with the development of atherosclerosis.

Oxidative mechanisms and atherothrombotic cardiovascular disease

Oxidant stress has been implicated in the etiology and pathogenesis of atherothrombotic vascular disease. Elevated levels of reactive oxygen species, resulting from increased production and/or decreased antioxidant capacity, modulate the vessel wall phenotype to create an environment that facilitates the progression of atherosclerosis. Herein, we review a number of biochemical mechanisms by which oxidant stress mediates atherosclerotic lesion formation and progression.

Calcium distribution in the vessel wall and intima-media thickness of the human carotid arteries

Increased common carotid artery (CCA) intima-media thickness (IMT) measured by B-mode ultrasound is an early marker of the atherosclerotic process. Arterial calcification is not clearly understood. Using the particle-induced X-ray emission (PIXE) method, we have looked for the location in the artery wall where calcium accumulated in the early phase of atherosclerosis. Twelve segments of CCAs of deceased stroke patients were investigated. In-vivo, carotid duplex ultrasound was performed with bilateral CCA IMT measurement at plaque-free sections. During autopsy, segments of carotid arteries were collected and filled under pressure with a stained histologic embedding material. The frozen arteries were cut into 60-microm-thick slices. Calcium distribution maps from the segments of arteries were determined by PIXE method. IMT measured by ultrasound and calcium distribution maps measured by PIXE were compared. In our cross-sectional study, using the PIXE analysis and ultrasound images, we could demonstrate early calcium accumulation in the media layer. Our results have also shown a significant relationship between calcium content of distributional maps measured by PIXE analysis and corresponding IMT on B-mode ultrasound images of human CCAs.

Homocysteine at pathophysiological concentrations enhances binding of dendritic cells to endothelial cells mediated by DC-SIGN

Elevated plasma homocysteine (Hcy) is an independent risk factor for atherosclerosis, which is recognized as inflammatory and immune responses. The purpose of this study was to investigate the effect of Hcy on the interaction between dendritic cells (DCs) and endothelial cells (ECs) by upregulating the expression of DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN) in cultured DCs. The immunophenotype of Hcy-treated DCs was monitored by flow cytometry. Then, they were coincubated with cultured human umbilical vein endothelial cells, and adhesion of DCs to ECs, and migration of DCs through an endothelial monolayer growing on the insert of a transwell plate, were assessed using a confocal microscope and a multi-detection microplate reader. The expression of DC-SIGN on Hcy-stimulated DCs was assessed by Western blot and immunofluorescence staining. The presence of Hcy did not change the phenotype of immature and mature DCs. Hcy promoted adhesion of DCs to ECs and migration in a concentration-dependent fashion. This effect was inhibited by an anti-DC-SIGN monoclonal antibody. The expression of DC-SIGN on DCs was significantly upregulated by Hcy in a concentration-dependent manner. Taken together, our results show for the first time that Hcy can potentiate the adhesion of DCs to ECs and migration by upregulating the expression of DC-SIGN on DCs, suggesting a novel role of Hcy in the pathogenesis of human vascular disease.

[Immunological aspects of atherosclerosis]

The pathogenesis of atherosclerosis remains incompletely understood. Accumulation of oxidized lipoproteins (oxLDL) within the vascular wall drives a related immune response very early during the disease course. Such an immune response is self-amplified and eventually escapes from physiologic control mechanisms. Certain lymphocytes may become pathogenic. B cells play a protective role by producing antibodies able to neutralize oxLDL. Elucidation of the immune control mechanisms in atherosclerosis will open the way to new therapeutic perspectives.

Screening of a HUAEC cDNA library identifies actin as a candidate autoantigen associated with carotid atherosclerosis

The humoral immune response to endothelium has a pivotal role in the development of atherosclerosis. Using a molecular method, we sought to identify endothelial autoantigens in carotid atherosclerosis. Immunoscreening of a HUAEC expression library with IgG from a pool of two sera from patients with carotid atherosclerosis identified a clone specific to actin. We evaluated actin-specific IgG reactivity in patients with carotid atherosclerosis and compared responses with those in patients with systemic lupus erythematosus and type 1 diabetes mellitus and in healthy subjects. Enzyme-linked immunoassay detected actin-specific IgG in a significantly higher percentage of sera from patients with atherosclerosis and systemic lupus erythematosus than from healthy subjects (16/61, 26% and 13/33, 39%versus 2/41, 5%, P = 0.012 and P < 10(-4), by chi2 test). Mean optical density values were significantly higher in patients than in healthy subjects (P < 10(-4) by Student's t-test). Patients with atherosclerosis and uncomplicated plaques had significantly higher serum anti-actin IgG reactivity than those with complicated plaques (P = 0.048 by Student's t-test). Our findings suggest that actin is an autoantigenic molecule of potential clinical interest in carotid atherosclerosis.

Oxidized LDL autoantibodies are related to apolipoprotein E phenotype, independently of postprandial change in plasma triglycerides and LDL size, among patients with angiographically verified coronary artery disease and healthy controls

OBJECTIVE

Oxidized low-density lipoprotein (LDL) autoantibodies (oxLDLab), apolipoprotein E (apoE) phenotype, postprandial triglyceride changes and LDL size are suggested to be risk factors for coronary artery disease (CAD). Our aim was to study the interaction between these new risk factors among patients with CAD and healthy controls.

METHODS

oxLDLab from 31 men with angiographically verified CAD and 31 healthy men were analyzed by enzyme-linked immunosorbent assay. Isoelectric focusing and immunoblotting were used for apoE phenotyping. Triglyceride level was measured after 12 h of fasting and 3, 5 and 7 h after a high-fat meal. Nondenaturing gradient gel electrophoresis was used to separate LDL particles according to size.

RESULTS

oxLD- Lab levels increased according to apoE phenotype in the following order: E2 < E3 < E4 (p = 0.004, ANOVA). The postprandial response of triglycerides, the size of LDL particles and the concentration of LDL and high-density lipoprotein (HDL) cholesterol did not differ between apoE phenotypes, and the use of these variables as covariates did not change the statistically significant difference in oxLDLab levels between apoE phenotypes (p = 0.01, ANCOVA). oxLDLab levels did not differ between the patient and control groups.

CONCLUSION

We found an association between apoE allele epsilon2 and decreased levels of oxLDLab, which was independent of the postprandial response of triglycerides, the size of LDL particles and plasma LDL and HDL cholesterol levels. The mechanism by which apoE affects oxidation of LDL remains unknown.

Endothelial determinants of dendritic cell adhesion and migration: new implications for vascular diseases

OBJECTIVE

Atherosclerosis is a chronic disease triggered by endothelial injury and sustained by inflammation. Dendritic cells (DCs) are critical for the cell-mediated arm of an immune response and are known to influence inflammatory immunity. A fundamental aspect of DC function is their capacity to adhere and migrate through vascular endothelial cells (ECs). We investigated the role of endothelial activation and dysregulation of the NO pathway on DC adhesion and migration.

METHODS AND RESULTS

We discovered that DC adhesion and migration are modulated by changes in endothelial function. DC adhesion and transmigration were markedly increased after exposing ECs to hypoxia, oxidized low density lipoprotein, or tumor necrosis factor-alpha. Specifically, inhibition of endothelial NO synthase increased DC binding and transmigration. L-Arginine or 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibition partially decreased DC-EC interaction.

CONCLUSIONS

The results of this study suggest that the adhesion and migration of DCs are increased by stimuli known to accelerate atherogenesis. Vice versa, augmentation of endothelial NO synthase activity prevents DC adhesion. These findings may provide insight into the inflammatory processes occurring in atherosclerosis. Because DCs control immunity, regulating DC-EC interaction may be relevant to inflammation and atherogenesis.

Characterization of fractalkine (CX3CL1) and CX3CR1 in human coronary arteries with native atherosclerosis, diabetes mellitus, and transplant vascular disease

BACKGROUND

Fractalkine is a novel chemokine that mediates both firm adhesion of leukocytes to the endothelium via CX3CR1 and leukocyte transmigration out of the bloodstream. Fractalkine has recently been shown to play a role in the pathogenesis of acute organ rejection. Since its expression is regulated by inflammatory agents such as LPS, IL-1, and TNF-alpha, fractalkine involvement in atherosclerosis and transplant vascular disease (TVD) is of particular interest. In this study, we characterized the presence of fractalkine and its receptor CX3CR1 in human coronary arteries from normal, atherosclerotic, diabetic, and TVD settings.

METHOD

Polyclonal rabbit antibodies were used to immunostain human fractalkine and CX3CR1 to localize their presence in transverse sections of the proximal left anterior descending and/or right coronary arteries. Slides were scored in a blinded fashion for intensity of staining (0 to 4+) and for localization in vessel walls.

RESULTS

Normal coronary arteries showed no fractalkine staining. In atherosclerotic coronary arteries, staining was localized to the intima, media, and adventitia. Within the media, fractalkine expression was seen in macrophages, foam cells, and smooth muscle cells (SMCs). Diabetic vessels showed similar staining patterns to atherosclerotic coronaries, with much stronger staining in the deep intima. Transplanted coronaries showed staining in the endothelium, intima, and adventitia in early disease, and intimal, medial, and adventitial staining in late disease. CX3CR1 staining was seen in the coronary arteries of all cases, with specific localization to regions with fractalkine staining.

CONCLUSION

The distinctive staining patterns in native atherosclerosis, diabetes mellitus with atherosclerosis, and TVD indicate that the expression of fractalkine and CX3CR1 may be important in the pathogenesis of these diseases.

MCMV infection increases early T-lymphocyte influx in atherosclerotic lesions in apoE knockout mice

BACKGROUND

Multiple epidemiological studies have suggested that cytomegalovirus (CMV) infection is associated with atherosclerotic disease. However, conclusive proof that the virus is directly related to the progression of the disease is still lacking.

OBJECTIVES

The goal of this study was to investigate whether MCMV is able to exacerbate the atherosclerotic process in atherosclerosis-susceptible mice.

STUDY DESIGN

apoE knockout mice kept on a chow diet were sacrificed at both 2 and 20 weeks post infection (p.i.). C57Bl/6J mice fed an atherogenic diet were sacrificed at 2 weeks p.i. Lesion area, lesion composition (endothelial cells and smooth muscle cells) and inflammatory influx (T-lymphocytes and macrophages) in lesions were determined. The former one was determined by means of a microscope coupled to a computer-assisted morphometry system. The latter ones were scored after immunohistochemical staining.

RESULTS

In the chronic phase of the infection mean lesion size was significantly increased after MCMV infection in the apoE knockout mice. This increase could to a large extent be attributed to a significant increase in type V lesion area after MCMV infection. Also, a significant increase in T-lymphocyte influx was observed in the acute phase of the infection in lesions from apoE knockout mice after MCMV infection while this effect was absent in C57Bl/6J mice. After MCMV infection no increase was observed in macrophage, smooth muscle cell and endothelial cell number in lesions from both mice strains.

CONCLUSIONS

MCMV infection may exacerbate the atherosclerotic process in apoE knockout mice by means of an acute lymphocytic inflammatory response. In contrast to the MCMV induced effect in apoE knockout mice, MCMV infection did not increase the influx of T-lymphocytes in atherosclerotic lesions of C57Bl/6J mice.

Cross-reactivity of anti-CagA antibodies with vascular wall antigens: possible pathogenic link between Helicobacter pylori infection and atherosclerosis

BACKGROUND

Helicobacter pylori-CagA positive strains have been shown to be associated with atherosclerosis. However, the pathogenesis is still undetermined. The aim of this study was to determine whether anti-CagA antibodies cross-react with antigens of normal and atherosclerotic arteries.

METHODS AND RESULTS

Eight umbilical cord sections, 14 atherosclerotic artery sections, and 10 gastrointestinal tract sections were examined by immunohistochemistry using polyclonal anti-CagA antibodies. Five atherosclerotic and 3 normal artery samples were also lysed in ice-cold lysis buffer containing protease inhibitors and were immunoprecipitated using the same antibodies. Anti-CagA antibodies reacted with cytoplasm and nuclei of smooth muscle cells in umbilical cord and atherosclerotic vessel sections, cytoplasm of fibroblasts-like cells in intimal atherosclerotic plaques, and the cell membranes of endothelial cells. Anti-CagA antibodies also specifically immunoprecipitated 2 high molecular weight antigens of 160 and 180 kDa from both normal and atherosclerotic artery lysates.

CONCLUSIONS

Anti-CagA antibodies cross-react with antigens of both normal and atherosclerotic blood vessels. We speculate that the binding of anti-CagA antibodies to those antigens in injured arteries could influence the progression of atherosclerosis in CagA-positive H pylori-infected patients.

Immunomodulation for treatment and prevention of atherosclerosis

In recent years, it has become clear that the immune system has a major role in atherosclerosis development and progression. More specifically, atherosclerosis fulfills all four criteria to define a condition as being an autoimmune in nature. This association also suggests that modification of the immune response in atherosclerosis could affect this process. In this review, we summarize different aspects of immunomodulation in atherosclerosis. These include immunosuppression, active immunization, induction of tolerance, administration of intravenous immunoglobulin, gene therapy, cytokine network manipulation and statins.

Expression of heat shock protein-70 by dendritic cells in the arterial intima and its potential significance in atherogenesis

OBJECTIVE

Overexpression of heat shock proteins (HSPs) is an important means of cell protection during physiologic stress such as occurs during atherogenesis. Immune responses are early events in atherosclerosis, with recent studies indicating that both humoral and cellular autoimmune processes in atherogenesis are directed toward HSPs. Dendritic cells are the key cells in the initiation and regulation of immune responses. This study examined whether HSP70 is overexpressed by dendritic cells in atherosclerotic lesions.

METHODS

Twenty-six carotid artery and 16 aortic specimens obtained at endarterectomy and aortic reconstruction were examined with immunohistochemical techniques. The nature of cells that overexpressed HSP70 was studied in consecutive sections that were double stained with antibodies to HSP70 and cell type-specific markers, including CD1a and fascin (to identify dendritic cells), CD14 (monocytes), CD68 (macrophages), CD3 (T cells), CD15 (mast cells), von Willibrand factor (endothelial cells), and alpha-smooth muscle actin (smooth muscle cells). Staining with HLA-DR and CD1d was used to identify cells involved in antigen presentation.

RESULTS

In advanced atherosclerotic lesions, several cell types, including monocytes, macrophages, dendritic cells, and smooth muscle cells, overexpressed HSP70. In contrast, in early atherosclerotic lesions, only dendritic cells overexpressed HSP70. Dendritic cells that overexpressed HSP70 frequently contacted T cells and also expressed HLA-DR. Furthermore, dendritic cells that clustered with T cells expressed CD1d, a unique molecule responsible for presenting lipid antigens.

CONCLUSION

The results suggest that direct contacts between activated dendritic cells that overexpress HSP70 and T cells might be responsible for T cell activation and might facilitate the presentation of lipid antigens to T cells directly within the arterial wall. In early intimal lesions, HSP70 is overexpressed exclusively by dendritic cells, which suggests that dendritic cells might be involved in the early phases of atherogenesis.

Dendritic cells and their involvement in atherosclerosis

Dendritic cells constitute a unique family of cells able to induce primary immune responses. Over the past decade, immunologists have been increasingly preoccupied with dendritic cells and dendritic cells are now seen as a panacea for vaccine development, tumour immunotherapy and a host of other immunological applications. The recent finding of dendritic cells accumulating in atherosclerotic lesions should stimulate investigation of their contributions to atherogenesis and their potential use in anti-atherosclerosis therapies.