Pathogen-sensing plasmacytoid dendritic cells stimulate cytotoxic T-cell function in the atherosclerotic plaque through interferon-alpha

Dendritic cells in atherosclerosis

Atherosclerosis is a chronic inflammatory disease with activation of both the innate and adaptive arms of the immune system. Dendritic cells (DCs) are potent activators of adaptive immunity and have been identified in the normal arterial wall and within atherosclerotic lesions. Recent evidence points to a functional role for DCs in all stages of atherosclerosis because of their myriad functions including lipid uptake, antigen presentation, efferocytosis, and inflammation resolution. Moreover, DC-based vaccination strategies are currently being developed for the treatment of atherosclerosis. This review will focus on the current evidence as well as the proposed roles for DCs in the pathogenesis of atherosclerosis and discuss future therapeutic strategies.

Inflammation and immune system interactions in atherosclerosis

Cardiovascular disease (CVD) is the leading cause of mortality worldwide, accounting for 16.7 million deaths each year. The underlying cause of the majority of CVD is atherosclerosis. In the past, atherosclerosis was considered to be the result of passive lipid accumulation in the vessel wall. Today's picture is far more complex. Atherosclerosis is considered a chronic inflammatory disease that results in the formation of plaques in large and mid-sized arteries. Both cells of the innate and the adaptive immune system play a crucial role in its pathogenesis. By transforming immune cells into pro- and anti-inflammatory chemokine- and cytokine-producing units, and by guiding the interactions between the different immune cells, the immune system decisively influences the propensity of a given plaque to rupture and cause clinical symptoms like myocardial infarction and stroke. In this review, we give an overview on the newest insights in the role of different immune cells and subtypes in atherosclerosis.

Inflammation and coagulation in atherosclerosis

Cardiovascular diseases remain to be the leading cause of death in Western societies. Despite major findings in vascular biology that lead to a better understanding of the pathomechanisms involved in atherosclerosis, treatment of the disease has only changed slightly within the last years. A big body of evidence suggests that atherosclerosis is a chronic inflammatory disease of the vessel wall. Accumulation and peroxidation of LDL-particles within the vessel wall trigger a strong inflammatory response, causing macrophage and T-cell accumulation within the vessel wall. Additionally, B-cells and specific antibodies against LDL-particles, as well as the complement system are implicated in atherogenesis. Besides data from clinical trials and autopsy studies it was the implementation of mouse models of atherosclerosis and the emerging field of direct gen-modification that lead to a thorough description of the pathophysiological mechanisms involved in the disease and created overwhelming evidence for a participation of the immune system. Recently, the cross-talk between coagulation and inflammation in atherogenesis has gained attention. Serious limitations and disparities in the pathophysiology of atherosclerosis in mice and men complicated the translation of experimental data into clinical practice. Despite these limitations, new anti-inflammatory medical therapies in cardiovascular disease are currently being tested in clinical trials.

Does Oral Hygiene Trigger Carotid Artery Intima-Media Thickness?

<p><b>Background and Purpose:</b> The aim of this study was to evaluate whether poor oral hygiene is associated with the intima-media thickness of the carotid arteries, which is one of the predictors of future progression of subclinical atherosclerosis.</p><p><b>Methods:</b> We selected 108 patients during periodontal examinations according to their oral hygiene. The patients had no history of atherosclerotic disease. The results of carotid artery B-mode ultrasonography examinations were analyzed at baseline and after a mean of 7.8 months. Patients were scored on the DMFT index for the number of decayed (D), missing (M), and filled (F) teeth (T). We also used the Silness-Loe plaque index (SLI) to evaluate oral hygiene and dental plaque. The patients were divided into 2 groups according to DMFT and SLI criteria. Group I had a DMFT index of 0 to 3 and an SLI score of 0 or 1; group II had a DMFT index of 4 to 28 and an SLI score of 2 or 3.</p><p><b>Results:</b> Dental status and oral hygiene were significantly associated with carotid artery intima-media thickness. Patients with increasing DMFT and SLI indices were correlated with intima-media thickness of the carotid artery.</p><p><b>Conclusions:</b> Chronic poor oral hygiene and tooth loss are related to subclinical atherosclerotic changes in the carotid arteries and might be indicative of future progression of atherosclerosis.</p>

Coronary heart disease in systemic lupus erythematosus is associated with interferon regulatory factor-8 gene variants

BACKGROUND

Patients with systemic lupus erythematosus have increased morbidity and mortality in coronary heart disease (CHD). We asked whether there was a genetic influence on CHD in systemic lupus erythematosus.

METHODS AND RESULTS

The association between single-nucleotide polymorphisms (SNPs) and CHD in 2 populations of patients with systemic lupus erythematosus was assessed. Patients were genotyped on a custom 12k Illumina Array. The allele frequencies were compared between patients with (n=66) and without (n=509) CHD. We found 61 SNPs with an association (P<0.01) to CHD, with the strongest association for 3 SNPs located in the interferon regulatory factor-8 (IRF8) gene. Comparison of the allele frequencies of these 61 SNPs in patients with (n=27) and without (n=212) CHD in the second study population revealed that 2 SNPs, rs925994 and rs10514610 in IRF8 (linkage disequilibrium, r²=0.84), were associated with CHD in both study populations. Meta-analysis of the SNP rs925994 gave an odds ratio of 3.6 (2.1-6.3), P value 1.9×10⁻⁶. The identified IRF8 allele remained as a risk factor for CHD after adjustment for traditional CHD risk factors. The IRF8 risk allele was associated with the presence of carotid plaques (P<0.001) and increased intima-media thickness (P=0.01). By electrophoretic mobility shift assays, we show weaker binding of protein to the risk allele of the highly linked SNP rs11117415, and by flow cytometry, a reduced frequency of circulating B cells was detected in patients with the IRF8 risk allele.

CONCLUSIONS

There is a considerable genetic component for CHD in systemic lupus erythematosus, with IRF8 as a strong susceptibility locus.

The role of the vascular dendritic cell network in atherosclerosis

A complex role has been described for dendritic cells (DCs) in the potentiation and control of vascular inflammation and atherosclerosis. Resident vascular DCs are found in the intima of atherosclerosis-prone vascular regions exposed to disturbed blood flow patterns. Several phenotypically and functionally distinct vascular DC subsets have been described. The functional heterogeneity of these cells and their contributions to vascular homeostasis, inflammation, and atherosclerosis are only recently beginning to emerge. Here, we review the available literature, characterizing the origin and function of known vascular DC subsets and their important role contributing to the balance of immune activation and immune tolerance governing vascular homeostasis under healthy conditions. We then discuss how homeostatic DC functions are disrupted during atherogenesis, leading to atherosclerosis. The effectiveness of DC-based "atherosclerosis vaccine" therapies in the treatment of atherosclerosis is also reviewed. We further provide suggestions for distinguishing DCs from macrophages and discuss important future directions for the field.

WITHDRAWN: Dendritic cells: A double-edge sword in atherosclerotic inflammation

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Neuroimmunology of the atherosclerotic plaque: a morphological approach

Atherosclerosis is a chronic inflammatory process, lasting for several decades until the onset of its clinical manifestations. The progression of the atherosclerotic lesion to a stable fibrotic plaque, narrowing the vascular lumen, or to a vulnerable plaque leading to main vascular complications, is associated to the involvement of several cell subpopulations of the innate as well as of the adaptive immunity, and to the release of chemokines and pro-inflammatory cytokines. Emerging evidence outlines that the cardiovascular risk is dependent on stress-mediators influencing cell migration and vascular remodeling. The view that atherosclerosis is initiated by monocytes and lymphocytes adhering to dysfunctional endothelial cells is substantiated by experimental and clinical observations. Macrophages, dendritic cells, T and B lymphocytes, granulocytes accumulating into the subendothelial space secrete and are stimulated by soluble factors, including peptides, proteases and cytokines acting synergistically. The final step of the disease, leading to plaque destabilization and rupture, is induced by the release, at the level of the fibrous cap, of metalloproteinases and elastases by the activated leukocytes which accumulate locally. Recruitment of specific cell subpopulations as well as the progression of atherosclerotic lesions towards a stable or an unstable phenotype, are related to the unbalance between pro-atherogenic and anti-atherogenic factors. In this connection stress hormones deserve particular attention, since their role in vascular remodeling, via vascular smooth cell proliferation, as well as in neoangiogenesis, via stimulation of endothelial cell proliferation and migration, has been already established.

Plasmacytoid Dendritic Cells Play a Key Role in Promoting Atherosclerosis in Apolipoprotein E–Deficient Mice

Objective—

Clinical studies have identified that reduced numbers of circulating plasmacytoid dendritic cells (pDCs) act as a predictor of cardiovascular events in coronary artery disease and that pDCs are detectable in the shoulder region of human atherosclerotic plaques, where rupture is most likely to occur. Results from animal models are controversial, with pDCs seen to inhibit or promote lesion development depending on the experimental settings. Here, we investigated the role of pDCs in atherosclerosis in apolipoprotein E−deficient mice.

Methods and Results—

We demonstrated that the aorta and spleen of both apolipoprotein E−deficient and C57BL/6 mice displayed similar numbers of pDCs, with similar activation status. In contrast, assessment of antigen uptake/presentation using the Eα/Y-Ae system revealed that aortic pDCs in apolipoprotein E−deficient - mice were capable of presenting in vivo systemically administered antigen. Continuous treatment of apolipoprotein E−deficient mice with anti−mouse plasmacytoid dendritic cell antigen 1 (mPDCA-1) antibody caused specific depletion of pDCs in the aorta and spleen and significantly reduced atherosclerosis formation in the aortic sinus (by 46%; P <0.001). Depletion of pDCs also reduced macrophages (by 34%; P <0.05) and increased collagen content (by 41%; P <0.05) in aortic plaques, implying a more stable plaque phenotype. Additionally, pDC depletion reduced splenic T-cell activation and inhibited interleukin-12, chemokine (C-X-C motif) ligand 1, monokine induced by interferon-γ, interferon γ−induced protein 10, and vascular endothelium growth factor serum levels.

Conclusion—

These results identify a critical role for pDCs in atherosclerosis and suggest a potential role for pDC targeting in the control of the pathology.

Phenotypic characterisation of pro-inflammatory monocytes and dendritic cells in peripheral arterial disease

Atherosclerosis is a chronic inflammatory process involving antigen-presenting cells like monocytes and dendritic cells (DC). The aim of this study was to perform a phenotypic characterisation of these cell types in patients with different degrees of peripheral arterial disease (PAD). Sixty patients with PAD [N= 30 intermittent claudication (IC), N= 30 critical limb ischemia (CLI)] and 30 controls were included. Peripheral blood leucocytes were analysed from peripheral blood by flow cytometry using different gating strategies to directly identify and analyse monocytes, myeloid DC, (mDC) and plasmacytoid DC (pDC). PAD patients showed a significantly higher proportion of proinflammatory CD14++CD16+ monocytes (p<0.0001) compared with healthy individuals. We found an increased number of mDC/ml and a reduced number of pDC/ml (both p<0.01) in PAD patients, leading to a shift in the mDC/pDC ratio (p<0.01). As compared to patients with intermittent claudication, CLI patients presented a reduced expression of HLA-DR (p<0.01), CD86 and CD40 on both mDCs and pDCs (p<0.01). Peripheral blood monocytes show a proinflammatory phenotype in PAD patients compared to controls. In contrast, CLI patients show a reduced expression of proinflammatory markers. We hypothesise that severe ischaemia and/or prolonged inflammation in CLI might lead to a paradoxical attenuation in the proinflammatory membrane pattern of circulating mononuclear cells, possibly hindering an adequate regulatory function of mDCs and pDCs and favouring the progression of disease.

Dendritic cell biology in human cytomegalovirus infection and the clinical consequences for host immunity and pathology

Human cytomegalovirus (HCMV), a member of the herpesvirus family, establishes life-long persistence and latency after primary infection and can be reactivated later in life. In immunosuppressed patients, it is an important pathogen that can cause severe disease. HCMV is also thought to play a causative role in inflammatory diseases and cancer. The virus can infect different immune cells, including dendritic cells (DCs) and can take advantage of host immune functions to avoid immune recognition. These characteristics have sparked major interest in understanding HCMV and its interaction with immune cells and their relevance to disease pathogenesis. In this review, we focus on the complex host-pathogen relationship between HCMV and DCs, including the persistence of the virus in these cells, their function in the immune response to HCMV infection and the potential clinical consequences of HCMV infection in DCs.

Plasmacytoid dendritic cells: biomarkers or potential therapeutic targets in atherosclerosis?

Plasmacytoid dendritic cells (pDCs) represent a unique subset of dendritic cells that play distinct and critical roles in the immune response. Importantly, pDCs play a pivotal role in several chronic autoimmune diseases strongly characterized by an increased risk of vascular pathology. Clinical studies have shown that pDCs are detectable in atherosclerotic plaques and others have suggested an association between reduced numbers of circulating pDCs and cardiovascular events. Although the causal relationship between pDCs and atherosclerosis is still uncertain, recent results from mouse models are starting to define the specific role(s) of pDCs in the disease process. In this review, we will discuss the role of pDCs in innate and adaptive immunity, the emerging evidence demonstrating the contribution of pDCs to vascular pathology and we will consider the possible impact of pDCs on the acceleration of atherosclerosis in chronic inflammatory autoimmune diseases. Finally, we will discuss how pDCs could be targeted for therapeutic utility.

Dendritic cells and regulatory T cells in atherosclerosis

Although macrophages and other immune system cells, especially T cells, have been shown to play disease-promoting roles in atherosclerosis, less is known about the role of antigen presenting cells. Functional, immune stimulating dendritic cells (DCs) have recently been detected in aortic intima, the site of origin of atherosclerosis. We had compared DCs with macrophages in mice with experimental atherosclerosis, to clearly define cell types by developmental and functional criteria. This review summarizes recent advances in studies of DCs in humans and in mouse models of atherosclerosis, as well as providing a simple strategy to measure regulatory T (Treg) cells in the mouse aorta.

Mechanisms of premature atherosclerosis in rheumatoid arthritis and lupus

Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), the two most common systemic autoimmune disorders, have both unique and overlapping manifestations. One feature they share is a significantly enhanced risk of atherosclerotic cardiovascular (CV) disease that significantly contributes to morbidity and mortality. The primary mechanisms that drive CV damage in these diseases remain to be fully characterized, but recent discoveries indicate that distinct inflammatory pathways and immune dysregulation characteristic of RA and SLE likely play prominent roles. This review focuses on analyzing the major mechanisms and pathways potentially implicated in the acceleration of atherothrombosis and CV risk in SLE and RA, as well as in the identification of putative preventive strategies that may mitigate vascular complications in systemic autoimmunity.

Dendritic cells in atherogenesis: possible novel targets for prevention of atherosclerosis

Atherosclerosis has been recognized as an inflammatory disease of the arterial wall, involving innate and adaptive immunity. Effector T cells are differentiated from naïve T cells stimulated by antigen-presenting cells such as macrophages and dendritic cells (DCs) and play critical roles in atherogenesis. Accumulating evidence revealed that several subsets of regulatory T cells (Tregs) inhibit atherosclerotic lesion formation via inhibiting the inflammatory response of effector T cells. In addition, the contribution of DCs to atherogenesis has been demonstrated. DCs have different functions for either stimulating or inhibiting T cell function depending on their origin and maturation stage. In particular, immature DCs, which have potential for inducing Tregs and inhibiting effector T cells, are sometimes called 'tolerogenic DCs' and suppress immune responses. Epidemiological studies have highlighted the increasing prevalence of vitamin D(3) deficiency and its association with increased risks of cardiovascular diseases. Some studies have raised interest in the immunomodulatory properties of vitamin D(3) beyond its well-established role in bone and calcium metabolism. The active form of vitamin D(3) (calcitriol) induces Tregs and tolerogenic DCs, which are both involved in maintaining immunologic tolerance to self and harmless antigens. Interestingly, recent evidence suggested that DCs in the intestinal immune system are involved in inducing Tregs; modulating the function of DCs and Tregs in the intestinal immune system might have beneficial effects on atherosclerosis. In this review, we focus on the function of DCs in vascular diseases and discuss vitamin D(3) therapy for the prevention of atherosclerosis.

Do we know enough about the immune pathogenesis of acute coronary syndromes to improve clinical practice?

Morbidities related to atherosclerosis, such as acute coronary syndromes (ACS) including unstable angina and myocardial infarction, remain leading causes of mortality. Unstable plaques are inflamed and infiltrated with macrophages and T lymphocytes. Activated dendritic cells interact with T cells, yielding predominantly Th1 responses involving interferon-gamma (IFN-γ) and tumour necrosis factor-alpha (TNF-α), while the role of interleukin 17 (IL-17) is questionable. The expansion of CD28nullCD4 or CD8 T cells as well as pattern recognition receptors activation (especially Toll-like receptors; TLR2 and TLR4) is characteristic for unstable plaque. Inflammation modifies platelet and fibrin clot characteristics, which are critical for ACS. Understanding of the inflammatory mechanisms of atherothrombosis, bridging inflammation, oxidative stress and immune regulation, will allow for the detection of subjects at risk, through the use of novel biomarkers and imaging techniques including intravascular ultrasound, molecular targeting, magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET). Moreover, understanding the specific inflammatory pathways of plaque rupture and atherothrombosis may allow for immunomodulation of ACS. Statins and anti-platelet drugs are anti-inflammatory, but importance of immune events in ACS warrants the introduction of novel, specific treatments directed either on cytokines, TLRs or inflammasomes. While the prime time for the introduction of immunologically inspired diagnostic tests and treatments for atherosclerosis have not come yet, we are closer than ever before to finally being able to benefit from this vast body of experimental and clinical evidence. This paper provides a comprehensive review of the role of the immune system and inflammation in ACS.

Control of dichotomic innate and adaptive immune responses by artery tertiary lymphoid organs in atherosclerosis

Tertiary lymphoid organs (TLOs) emerge in tissues in response to non-resolving inflammation such as chronic infection, graft rejection, and autoimmune disease. We identified artery TLOs (ATLOs) in the adventitia adjacent to atherosclerotic plaques of aged hyperlipidemic ApoE^−/− mice. ATLOs are structured into T cell areas harboring conventional dendritic cells and monocyte-derived DCs; B cell follicles containing follicular dendritic cells within activated germinal centers; and peripheral niches of plasma cells. ATLOs also show extensive neoangiogenesis, aberrant lymphangiogenesis, and high endothelial venule (HEV) neogenesis. Newly formed conduit networks connect the external lamina of the artery with HEVs in T cell areas. ATLOs recruit and generate lymphocyte subsets with opposing activities including activated CD4⁺ and CD8⁺ effector T cells, natural and induced CD4⁺ T regulatory (nTregs; iTregs) cells as well as B-1 and B-2 cells at different stages of differentiation. These data indicate that ATLOs organize dichotomic innate and adaptive immune responses in atherosclerosis. In this review we discuss the novel concept that dichotomic immune responses toward atherosclerosis-specific antigens are carried out by ATLOs in the adventitia of the arterial wall and that malfunction of the tolerogenic arm of ATLO immunity triggers transition from silent autoimmune reactivity to clinically overt disease.

Plasmacytoid dendritic cells in atherosclerosis

Atherosclerosis, a chronic inflammatory disease of the vessel wall and the underlying cause of cardiovascular disease, is initiated and maintained by innate and adaptive immunity. Accumulating evidence suggests an important contribution of autoimmune responses to this disease. Plasmacytoid dendritic cells (pDCs), a specialized cell type known to produce large amounts of type I interferons (IFNs) in response to bacterial and viral infections, have recently been revealed to play important roles in atherosclerosis. For example, the development of autoimmune complexes consisting of self-DNA and antimicrobial peptides, which trigger chronic type I IFN production by pDCs, promote early atherosclerotic lesion formation. pDCs and pDC-derived type I IFNs can also induce the maturation of conventional DCs and macrophages, and the development of autoreactive B cells and antibody production. These mechanisms, known to play a role in the pathogenesis of other autoimmune diseases such as systemic lupus erythematosus and psoriasis, may also affect the development and progression of atherosclerotic lesion formation. This review discusses emerging evidence showing a contribution of pDCs in the onset and progression of atherosclerosis.

Marked acceleration of atherosclerosis after Lactobacillus casei-induced coronary arteritis in a mouse model of Kawasaki disease

OBJECTIVE

The purpose of this study was to investigate whether Lactobacillus casei cell wall extract-induced Kawasaki disease (KD) accelerates atherosclerosis in hypercholesterolemic mice. Method and Results- Apolipoprotein E knockout or low-density lipoprotein receptor knockout mice were injected with Lactobacillus casei cell wall extract (KD mice) or PBS, fed high-fat diet for 8 weeks, and atherosclerotic lesions in aortic sinuses, arch (AC), and whole aorta were assessed. KD mice had larger, more complex aortic lesions with abundant collagen, and both extracellular and intracellular lipid and foam cells, compared with lesions in control mice despite similar cholesterol levels. Both apolipoprotein E knockout KD and low-density lipoprotein receptor knockout KD mice showed dramatic acceleration in atherosclerosis versus controls, with increases in en face aortic atherosclerosis and plaque size in both the aortic sinuses and AC plaques. Accelerated atherosclerosis was associated with increased circulating interleukin-12p40, interferon-γ, tumor necrosis factor-α, and increased macrophage, dendritic cell, and T-cell recruitment in lesions. Furthermore, daily injections of the interleukin-1Ra, which inhibits Lactobacillus casei cell wall extract-induced KD vasculitis, prevented the acceleration of atherosclerosis.

CONCLUSIONS

Our results suggest an important pathophysiologic link between coronary arteritis/vasculitis in the KD mouse model and subsequent atherosclerotic acceleration, supporting the concept that a similar relation may also be present in KD patients. These results also suggest that KD in childhood may predispose to accelerated and early atherosclerosis as adults.

Blocking toll-like receptors 7 and 9 reduces postinterventional remodeling via reduced macrophage activation, foam cell formation, and migration

OBJECTIVE

The role of toll-like receptors (TLRs) in vascular remodeling is well established. However, the involvement of the endosomal TLRs is unknown. Here, we study the effect of combined blocking of TLR7 and TLR9 on postinterventional remodeling and accelerated atherosclerosis.

METHODS AND RESULTS

In hypercholesterolemic apolipoprotein E*3-Leiden mice, femoral artery cuff placement led to strong increase of TLR7 and TLR9 presence demonstrated by immunohistochemistry. Blocking TLR7/9 with a dual antagonist in vivo reduced neointimal thickening and foam cell accumulation 14 days after surgery by 65.6% (P=0.0079). Intima/media ratio was reduced by 64.5% and luminal stenosis by 62.8%. The TLR7/9 antagonist reduced the arterial wall inflammation, with reduced macrophage infiltration, decreased cytoplasmic high-mobility group box 1 expression, and altered serum interleukin-10 levels. Stimulation of cultured macrophages with TLR7 and TLR9 ligands enhanced tumor necrosis factor-α expression, which is decreased by TLR7/9 antagonist coadministration. Additionally, the antagonist abolished the TLR7/9-enhanced low-density lipoprotein uptake. The antagonist also reduced oxidized low-density lipoprotein-induced foam cell formation, most likely not via decreased influx but via increased efflux, because CD36 expression was unchanged whereas interleukin-10 levels were higher (36.1 ± 22.3 pg/mL versus 128.9 ± 6.6 pg/mL; P=0.008).

CONCLUSIONS

Blocking TLR7 and TLR9 reduced postinterventional vascular remodeling and foam cell accumulation indicating TLR7 and TLR9 as novel therapeutic targets.

Type I interferons are associated with subclinical markers of cardiovascular disease in a cohort of systemic lupus erythematosus patients

BACKGROUND

Systemic lupus erythematosus (SLE) patients have a striking increase in cardiovascular (CV) comorbidity not fully explained by the Framingham risk score. Recent evidence from in vitro studies suggests that type I interferons (IFN) could promote premature CV disease (CVD) in SLE. We assessed the association of type I IFN signatures with functional and anatomical evidence of vascular damage, and with biomarkers of CV risk in a cohort of lupus patients without overt CVD.

METHODOLOGY/PRINCIPAL FINDINGS

Serum type I IFN activity (induction of five IFN-inducible genes; IFIGs) from 95 SLE patient and 38 controls was quantified by real-time PCR. Flow mediated dilatation (FMD) of the brachial artery and carotid intima media thickness (CIMT) were quantified by ultrasound, and coronary calcification by computed tomography. Serum vascular biomarkers were measured by ELISA. We evaluated the effect of type I IFNs on FMD, CIMT and coronary calcification by first applying principal components analysis to combine data from five IFIGs into summary components that could be simultaneously modeled. Three components were derived explaining 97.1% of the total IFIG variation. Multivariable linear regression was utilized to investigate the association between the three components and other covariates, with the outcomes of FMD and CIMT; zero-inflated Poisson regression was used for modeling of coronary calcification. After controlling for traditional CV risk factors, enhanced serum IFN activity was significantly associated with decreased endothelial function in SLE patients and controls (p<0.05 for component 3), increased CIMT among SLE patients (p<0.01 for components 1 and 2), and severity of coronary calcification among SLE patients (p<0.001 for component 3).

CONCLUSIONS

Type I IFNs are independently associated with atherosclerosis development in lupus patients without history of overt CVD and after controlling for Framingham risk factors. This study further supports the hypothesis that type I IFNs promote premature vascular damage in SLE.

Phenotypic and functional heterogeneity of macrophages and dendritic cell subsets in the healthy and atherosclerosis-prone aorta

Atherosclerosis continues to be the leading cause of cardiovascular disease. Development of atherosclerosis depends on chronic inflammation in the aorta and multiple immune cells are involved in this process. Importantly, resident macrophages and dendritic cells (DCs) are present within the healthy aorta, but the functions of these cells remain poorly characterized. Local inflammation within the aortic wall promotes the recruitment of monocytes and DC precursors to the aorta and micro-environmental factors direct the differentiation of these emigrated cells into multiple subsets of macrophages and DCs. Recent data suggest that several populations of macrophages and DCs can co-exist within the aorta. Although the functions of M1, M2, Mox, and M4 macrophages are well characterized in vitro, there is a limited set of data on the role of these populations in atherogenesis in vivo. Recent studies on the origin and the potential role of aortic DCs provide novel insights into the biology of aortic DC subsets and prospective mechanisms of the immune response in atherosclerosis. This review integrates the results of experiments analyzing heterogeneity of DCs and macrophage subsets in healthy and diseased vessels and briefly discusses the known and potential functions of these cells in atherogenesis.

Auto-antigenic protein-DNA complexes stimulate plasmacytoid dendritic cells to promote atherosclerosis

BACKGROUND

Inflammation has been closely linked to auto-immunogenic processes in atherosclerosis. Plasmacytoid dendritic cells (pDCs) are specialized to produce type-I interferons in response to pathogenic single-stranded nucleic acids, but can also sense self-DNA released from dying cells or in neutrophil extracellular traps complexed to the antimicrobial peptide Cramp/LL37 in autoimmune disease. However, the exact role of pDCs in atherosclerosis remains elusive.

METHODS AND RESULTS

Here we demonstrate that pDCs can be detected in murine and human atherosclerotic lesions. Exposure to oxidatively modified low-density lipoprotein enhanced the capacity of pDCs to phagocytose and prime antigen-specific T cell responses. Plasmacytoid DCs can be stimulated to produce interferon-α by Cramp/DNA complexes, and we further identified increased expression of Cramp and formation of neutrophil extracellular traps in atherosclerotic arteries. Whereas Cramp/DNA complexes aggravated atherosclerotic lesion formation in apolipoprotein E-deficient mice, pDC depletion and Cramp-deficiency in bone marrow reduced atherosclerosis and anti-double-stranded DNA antibody titers. Moreover, the specific activation of pDCs and interferon-α treatment promoted plaque growth, associated with enhanced anti-double-stranded-DNA antibody titers. Accordingly, anti-double-stranded DNA antibodies were elevated in patients with symptomatic versus asymptomatic carotid artery stenosis.

CONCLUSIONS

Self-DNA (eg, released from dying cells or in neutrophil extracellular traps) and an increased expression of the antimicrobial peptide Cramp/LL37 in atherosclerotic lesions may thus stimulate a pDC-driven pathway of autoimmune activation and the generation of anti-double-stranded-DNA antibodies, critically aggravating atherosclerosis lesion formation. These key factors may thus represent novel therapeutic targets.

A decrease in the percentage of circulating mDC precursors in patients with coronary heart disease: a relation to the severity and extent of coronary artery lesions?

Inflammation plays a pivotal role in coronary heart disease. Dendritic cells (DCs) are principal players in inflammation and atherosclerosis. Although the percentage of circulating DC precursors in coronary heart disease have been investigated, circulating myeloid DC (mDC) and plasmacytoid DC (pDC) precursors have not been extensively studied, particularly in relation to the severity of coronary artery lesions in patients with coronary heart disease. In this study, we recruited controls (n = 29), patients with stable angina pectoris (SAP, n = 30), patients with unstable angina pectoris (UAP, n = 56), and patients with acute myocardial infarction (AMI, n = 50). The severity and extent of coronary artery lesions was evaluated by Gensini score, following coronary angiograms. The percentage of circulating mDC and pDC precursors was determined by fluorescence-activated cell sorting (FACS). Plasma levels of MCP-1 and MMP-9, which correlate with atherosclerosis and DC migration, were also measured. The percentage of circulating mDC precursors was reduced in patients with AMI and UAP compared with control and SAP patients, respectively (p < 0.01 for AMI vs. SAP and Control, p < 0.05 for UAP vs. SAP and Control). The percentage of circulating pDC precursors was not significant changed. The levels of plasma MMP-9 and MCP-1 and Genisi score were all increased in patients with AMI and UAP, compared to control and SAP patients, respectively (p < 0.01 for AMI vs. SAP and control, p < 0.05 for UAP vs. SAP and control). Overall, the percentage of circulating mDC precursors was negatively correlated with MCP-1 (p < 0.001), MMP-9 (p < 0.001) and Genisi scores (p < 0.001). Genisi scores were positively correlated with the levels of MCP-1 (p < 0.001) and MMP-9 (p < 0.001). Our study suggested that the percentage of circulating mDC precursors is negatively correlated with the severity and extent of coronary artery lesions in patients with coronary heart disease.

PSGL-1-expressing CD4 T cells induce endothelial cell apoptosis in perimenopausal women

AIM

Menopause and subsequent estrogen deficiency correlate with the development of atherosclerosis and cardiovascular diseases in women. However, the relationship between estrogen deficiency and development of atherosclerosis with inflammatory infiltrates is not fully understood. We sought to determine whether perimenopausal women (PMW) exhibited T cell dysfunction related to the expression of adhesion molecules and accelerated endothelial cell (EC) apoptosis.

METHODS

Fresh CD4 T cells were isolated from 48 PMW and 54 healthy control women with regular menstrual cycles (CW), and investigated cytotoxicity to ECs by apoptosis assay. The adhesion molecules on CD4 T cells were examined by flow cytometry. CD4 T cell rolling and adhesion on ECs were analyzed by adhesion assay under laminar flow.

RESULTS

CD4 T cells from PMW with low estradiol levels induced significant EC apoptosis (P = 0.0152). Furthermore, cytotoxic CD4 T cells from PMW strongly expressed P-selectin glycoprotein ligand-1 (PSGL-1) and integrin β2 (P < 0.0001 and P = 0.0285, respectively) but not L-selectin or integrin αM when compared to CD4 T cells from CW. Estradiol levels negatively correlated with only PSGL-1 expression (R = -0.781, P = 0.0002), and estradiol treatments inhibited both PSGL-1 expression (P = 0.0133) and T cell-induced EC apoptosis (P = 0.018). An estrogen receptor antagonist inhibited these effects of estradiol (P = 0.0355 and P = 0.0097, respectively). Moreover, PSGL-1 expression correlated with T cell adhesion to ECs under laminar flow conditions (R = 0.636, P = 0.0355) and with EC apoptosis (R = 0.614, P = 0.0196). PSGL-1 specific antibodies effectively suppressed T cell adhesion (P = 0.0057) and EC apoptosis (P = 0.001) indicating that CD4 T cell-mediated EC apoptosis depended on PSGL-1 adhesion in PMW.

CONCLUSIONS

PSGL-1-expressing cytotoxic CD4 T cells are abundant in PMW with low estradiol levels may contribute to T cell-mediated atherosclerotic development.

Atherosclerosis: current pathogenesis and therapeutic options

Coronary artery disease (CAD) arising from atherosclerosis is a leading cause of death and morbidity worldwide. The underlying pathogenesis involves an imbalanced lipid metabolism and a maladaptive immune response entailing a chronic inflammation of the arterial wall. The disturbed equilibrium of lipid accumulation, immune responses and their clearance is shaped by leukocyte trafficking and homeostasis governed by chemokines and their receptors. New pro- and anti-inflammatory pathways linking lipid and inflammation biology have been discovered, and genetic profiling studies have unveiled variations involved in human CAD. The growing understanding of the inflammatory processes and mediators has uncovered an intriguing diversity of targetable mechanisms that can be exploited to complement lipid-lowering therapies. Here we aim to systematically survey recently identified molecular mechanisms, translational developments and clinical strategies for targeting lipid-related inflammation in atherosclerosis and CAD.

Plasmacytoid dendritic cells protect against atherosclerosis by tuning T-cell proliferation and activity

RATIONALE

Unlike conventional dendritic cells, plasmacytoid DCs (PDC) are poor in antigen presentation and critical for type I interferon response. Though proposed to be present in human atherosclerotic lesions, their role in atherosclerosis remains elusive.

OBJECTIVE

To investigate the role of PDC in atherosclerosis.

METHODS AND RESULTS

We show that PDC are scarcely present in human atherosclerotic lesions and almost absent in mouse plaques. Surprisingly, PDC depletion by 120G8 mAb administration was seen to promote plaque T-cell accumulation and exacerbate lesion development and progression in LDLr⁻/⁻ mice. PDC depletion was accompanied by increased CD4⁺ T-cell proliferation, interferon-γ expression by splenic T cells, and plasma interferon-γ levels. Lymphoid tissue PDC from atherosclerotic mice showed increased indoleamine 2,3-dioxygenase (IDO) expression and IDO blockage abrogated the PDC suppressive effect on T-cell proliferation.

CONCLUSIONS

Our data reveal a protective role for PDC in atherosclerosis, possibly by dampening T-cell proliferation and activity in peripheral lymphoid tissue, rendering PDC an interesting target for future therapeutic interventions.

Dendritic cells in human atherosclerosis: from circulation to atherosclerotic plaques

Background. Atherosclerosis is a chronic inflammatory disease with atherosclerotic plaques containing inflammatory infiltrates predominantly consisting of monocytes/macrophages and activated T cells. More recent is the implication of dendritic cells (DCs) in the disease. Since DCs were demonstrated in human arteries in 1995, numerous studies in humans suggest a role for these professional antigen-presenting cells in atherosclerosis. Aim. This paper focuses on the observations made in blood and arteries of patients with atherosclerosis. In principal, flow cytometric analyses show that circulating myeloid (m) and plasmacytoid (p) DCs are diminished in coronary artery disease, while immunohistochemical studies describe increased intimal DC counts with evolving plaque stages. Moreover, mDCs and pDCs appear to behave differently in atherosclerosis. Yet, the origin of plaque DCs and their relationship with blood DCs are unknown. Therefore, several explanations for the observed changes are postulated. In addition, the technical challenges and discrepancies in the research field are discussed. Future. Future studies in humans, in combination with experimental animal studies will unravel mechanisms leading to altered blood and plaque DCs in atherosclerosis. As DCs are crucial for inducing but also dampening immune responses, understanding their life cycle, trafficking and function in atherosclerosis will determine potential use of DCs in antiatherogenic therapies.

Expression of circulatory dendritic cells and regulatory T-cells in patients with different subsets of coronary artery disease

BACKGROUND

Dendritic cells (DCs), regulators of innate and adaptive immunity, may play an important role in atherosclerosis. DC invasion was found in early atherosclerotic lesions. We aimed to characterize circulating DC gene expression in patients with different subsets of coronary artery disease (CAD).

METHODS

Peripheral blood mononuclear cells were quantified using real-time polymerase chain reaction and fluorescence activated cell sorting in patients with acute coronary syndrome (ST-elevation myocardial infarction [STEMI], n = 35; non-ST-elevation myocardial infarction [NSTEMI], n = 30) and stable CAD (6 months after stent implantation without progression, n = 15) compared with control subjects (n = 15). DCs and T-cells (TCs) were characterized using specific primers for CD1a (immature), CD86 (mature), CD123 (plasmacytoid), BDCA1 (myeloid), CD178 (activated TCs), and FOXP3 (regulatory TCs). To evaluate whether serum of patients with STEMI induces DC differentiation, incubation of patient serum was performed.

RESULTS

CD86 was upregulated and CD1a downregulated in all patients with CAD (P < 0.05). Patients with STEMI and NSTEMI showed a downregulation of CD1a compared with patients with stable CAD (P ≤ 0.01). In contrast, stable patients with CAD had elevated CD178 levels compared with patients with STEMI and NSTEMI (P ≤ 0.04). In patients with STEMI, FOXP3 was downregulated compared with control subjects (P < 0.0001). Incubation of STEMI serum induced an upregulation of CD1a and CD86 in a human DC cell line. Coincubation with a blocking antibody for heat shock protein 60 inhibited this upregulation.

CONCLUSIONS

DCs are differentially regulated in patients with different subsets of CAD. Mature DCs are upregulated and immature DCs are downregulated in patients with CAD. Patients with STEMI show a significant downregulation of regulatory TCs. Circulating shock protein 60 induces DC differentiation in patients with STEMI.

Giant cell arteritis: immune and vascular aging as disease risk factors

Susceptibility for giant cell arteritis increases with chronological age, in parallel with age-related restructuring of the immune system and age-induced remodeling of the vascular wall. Immunosenescence results in shrinkage of the naïve T-cell pool, contraction of T-cell diversity, and impairment of innate immunity. Aging of immunocompetent cells forces the host to take alternative routes for protective immunity and confers risk for pathogenic immunity that causes chronic inflammatory tissue damage. Dwindling immunocompetence is particularly relevant as the aging host is forced to cope with an ever growing infectious load. Immunosenescence coincides with vascular aging during which the arterial wall undergoes dramatic structural changes and medium and large arteries lose their pliability and elasticity. On the molecular level, elastic fibers deteriorate and matrix proteins accumulate biochemical modifications. Thus, the aging process impacts the two major biologic systems that liaise to promote giant cell arteritis; the immune system and the vessel wall niche.

Infection of peripheral blood mononuclear cells with neuropathogenic equine herpesvirus type-1 strain Ab4 reveals intact interferon-α induction and induces suppression of anti-inflammatory interleukin-10 responses in comparison to other viral strains

The recent increase in incidence, morbidity, and mortality of neurological disease induced by equine herpesvirus type 1 (EHV-1) has suggested a change of virulence of the virus. The exact mechanisms by which EHV-1 induces neurologic disease are not known. Environmental, viral, and host risk factors might contribute to neurological manifestation. Here, we investigated innate interferon-α (IFN-α), interleukin-10 (IL-10) and IL-4 responses after infection of equine peripheral blood mononuclear cells (PBMC) with EHV-1 using an available cytokine multiplex assay. Three viral strains representing an older isolate (RacL11), a recent abortigenic (NY03) and a neuropathogenic isolate (Ab4) were compared to identify differences in cytokine induction that might explain the increased pathogenicity of Ab4. Cytokine concentrations were also compared between foals, mares after birth, pregnant and non-pregnant mares to investigate whether immune responses to EHV-1 infection are influenced by age or pregnancy status. PBMC from all groups secreted high concentrations of anti-viral IFN-α in response to EHV-1. A reduced response was observed in foals compared to non-pregnant mares. EHV-1 infection induced moderate IL-10 and overall low IL-4 secretion. Ab4 infection resulted in a significant reduction of IL-10 responses in adult horses. IL-10 and IL-4 responses were lower in foals than in most mare groups. These data suggested that EHV-1 induces robust IFN-α secretion without major differences between viral strains. However, anti-inflammatory IL-10 production was significantly reduced after infection with neuropathogenic Ab4. The ability of this EHV-1 isolate to down-regulate IL-10 production might contribute to increased local inflammation and a higher risk for neurological manifestation of the disease after infection with Ab4.

The immune system in atherosclerosis

Cardiovascular disease, a leading cause of mortality worldwide, is caused mainly by atherosclerosis, a chronic inflammatory disease of blood vessels. Lesions of atherosclerosis contain macrophages, T cells and other cells of the immune response, together with cholesterol that infiltrates from the blood. Targeted deletion of genes encoding costimulatory factors and proinflammatory cytokines results in less disease in mouse models, whereas interference with regulatory immunity accelerates it. Innate as well as adaptive immune responses have been identified in atherosclerosis, with components of cholesterol-carrying low-density lipoprotein triggering inflammation, T cell activation and antibody production during the course of disease. Studies are now under way to develop new therapies based on these concepts of the involvement of the immune system in atherosclerosis.

Complement in atherosclerosis: friend or foe?

Atherosclerosis is a chronic inflammatory disease and the complement system plays a central role in innate immunity. Increasing evidence exists that the complement system is activated within atherosclerotic plaques. However, the role of complement in atherogenesis is not fully understood. Whereas complement activation by the classic and lectin pathway may be protective by removing apoptotic cells and cell debris from atherosclerotic plaques, activation of the complement cascade by the alternative pathway and beyond the C3 convertase with formation of anaphylatoxins and the terminal complement complex may be proatherogenic and may play a role in plaque destabilization leading to its rupture and the onset of acute cardiovascular events. In this review article we present evidence for complement activation within atherosclerotic plaques and we discuss recent data derived from experimental animal models that suggest a dual role of complement in the development of the disease. In addition, we summarize the role of complement components as biomarkers for cardiovascular disease.

DNA-dependent protein kinase catalytic subunit mediates T-cell loss in rheumatoid arthritis

In the autoimmune syndrome rheumatoid arthritis (RA), T cells and T-cell precursors have age-inappropriate shortening of telomeres and accumulate deoxyribonucleic acid (DNA) double strand breaks. Whether damaged DNA elicits DNA repair activity and how this affects T-cell function and survival is unknown. Here, we report that naïve and resting T cells from RA patients are susceptible to undergo apoptosis. In such T cells, unrepaired DNA stimulates a p53-ataxia telangiectasia mutated-independent pathway involving the non-homologous-end-joining protein DNA-protein kinase catalytic subunit (DNA-PKcs). Upregulation of DNA-PKcs transcription, protein expression and phosphorylation in RA T cells co-occurs with diminished expression of the Ku70/80 heterodimer, limiting DNA repair capacity. Inhibition of DNA-PKcs kinase activity or gene silencing of DNA-PKcs protects RA T cells from apoptosis. DNA-PKcs induces T-cell death by activating the JNK pathway and upregulating the apoptogenic BH3-only proteins Bim and Bmf. In essence, in RA, the DNA-PKcs-JNK-Bim/Bmf axis transmits genotoxic stress into shortened survival of naïve resting T cells, imposing chronic proliferative turnover of the immune system and premature immunosenescence. Therapeutic blockade of the DNA-PK-dependent cell-death machinery may rejuvenate the immune system in RA.

Unexpected protective role for Toll-like receptor 3 in the arterial wall

The critical role of Toll-like receptors (TLRs) in mammalian host defense has been extensively explored in recent years. The capacity of about 10 TLRs to recognize conserved patterns on many bacterial and viral pathogens is remarkable. With so few receptors, cross-reactivity with self-tissue components often occurs. Previous studies have frequently assigned detrimental roles to TLRs, in particular to TLR2 and TLR4, in immune and cardiovascular disease. Using human and murine systems, we have investigated the consequence of TLR3 signaling in vascular disease. We compared the responses of human atheroma-derived smooth muscle cells (AthSMC) and control aortic smooth muscle cells (AoSMC) to various TLR ligands. AthSMC exhibited a specific increase in TLR3 expression and TLR3-dependent functional responses. Intriguingly, exposure to dsRNA in vitro and in vivo induced increased expression of both pro- and anti-inflammatory genes in vascular cells and tissues. Therefore, we sought to assess the contribution of TLR3 signaling in vivo in mechanical and hypercholesterolemia-induced arterial injury. Surprisingly, neointima formation in a perivascular collar-induced injury model was reduced by the systemic administration of the dsRNA analog Poly(I:C) in a TLR3-dependent manner. Furthermore, genetic deletion of TLR3 dramatically enhanced the development of elastic lamina damage after collar-induced injury. Accordingly, deficiency of TLR3 accelerated the onset of atherosclerosis in hypercholesterolemic ApoE(-/-) mice. Collectively, our data describe a protective role for TLR signaling in the vessel wall.

Common infections and the risk of stroke

The occurrence of stroke in populations is incompletely explained by traditional vascular risk factors. Data from several case-control studies and one large study using case series methodology indicate that recent infection is a temporarily acting, independent trigger factor for ischemic stroke. Both bacterial and viral infections, particularly respiratory tract infections, contribute to this association. A causal role for infection in stroke is supported by a graded temporal relationship between these conditions, and by multiple pathophysiological pathways linking infection and inflammation, thrombosis, and stroke. Furthermore, observational studies suggest that influenza vaccination confers a preventive effect against stroke. Case-control and prospective studies indicate that chronic infections, such as periodontitis, chronic bronchitis and infection with Helicobacter pylori, Chlamydia pneumoniae or Cytomegalovirus, might increase stroke risk, although considerable variation exists in the results of these studies, and methodological issues regarding serological results remain unresolved. Increasing evidence indicates that the aggregate burden of chronic and/or past infections rather than any one single infectious disease is associated with the risk of stroke. Furthermore, genetic predispositions relating to infection susceptibility and the strength of the inflammatory response seem to co-determine this risk. Here, we summarize and analyze the evidence for common acute and chronic infectious diseases as stroke risk factors.

Immune aging and rheumatoid arthritis

Immunologic models of rheumatoid arthritis (RA) have to take into account that the disease occurs at an age when immunocompetence is declining and in a host whose immune system shows evidence of accelerated immune aging. By several immune aging biomarkers, the immune system in patients with RA is prematurely aged by more than 20 years. One major pathogenetic mechanism is a defect in telomere maintenance and DNA repair that causes accelerated cell death. These findings in RA are reminiscent of murine autoimmunity models, in which lymphopenia was identified as a major risk factor for autoimmunity. Progress in the understanding of how accelerated immune aging is pathogenetically involved in RA may allow development of new therapeutic approaches that go beyond the use of anti-inflammatory agents and eventually could open new avenues for preventive intervention.

Myeloid type I interferon signaling promotes atherosclerosis by stimulating macrophage recruitment to lesions

Inflammatory cytokines are well-recognized mediators of atherosclerosis. Depending on the pathological context, type I interferons (IFNs; IFNalpha and IFNbeta) exert either pro- or anti-inflammatory immune functions, but their exact role in atherogenesis has not been clarified. Here, we demonstrate that IFNbeta enhances macrophage-endothelial cell adhesion and promotes leukocyte attraction to atherosclerosis-prone sites in mice in a chemokine-dependent manner. Moreover, IFNbeta treatment accelerates lesion formation in two different mouse models of atherosclerosis and increases macrophage accumulation in the plaques. Concomitantly, absence of endogenous type I IFN signaling in myeloid cells inhibits lesion development, protects against lesional accumulation of macrophages, and prevents necrotic core formation. Finally, we show that type I IFN signaling is upregulated in ruptured human atherosclerotic plaques. Hereby, we identify type I IFNs as proatherosclerotic cytokines that may serve as additional targets for prevention or treatment.

The expression and functions of toll-like receptors in atherosclerosis

Inflammation drives atherosclerosis. Both immune and resident vascular cell types are involved in the development of atherosclerotic lesions. The phenotype and function of these cells are key in determining the development of lesions. Toll-like receptors are the most characterised innate immune receptors and are responsible for the recognition of exogenous conserved motifs on pathogens, and, potentially, some endogenous molecules. Both endogenous and exogenous TLR agonists may be present in atherosclerotic plaques. Engagement of toll-like receptors on immune and resident vascular cells can affect atherogenesis as signalling downstream of these receptors can elicit proinflammatory cytokine release, lipid uptake, and foam cell formation and activate cells of the adaptive immune system. In this paper, we will describe the expression of TLRs on immune and resident vascular cells, highlight the TLR ligands that may act through TLRs on these cells, and discuss the consequences of TLR activation in atherosclerosis.

Changes in blood dendritic cell counts in relation to type of coronary artery disease and brachial endothelial cell function

BACKGROUND

Recently we reported a decline of circulating myeloid (m) and plasmacytoid (p) dendritic cells (DCs) in patients with coronary artery disease (CAD). This study also determined the total blood DC numbers and focused on effects of extent (one vs. three-vessel disease) and type (stable vs. unstable) of CAD, and on endothelial cell function.

METHODS

Patients undergoing diagnostic coronarography were enrolled in four groups: control patients (atypical chest pain, <50% narrowing, n=15), stable one-vessel (n=15), stable three-vessel (n=15), and unstable one-vessel CAD (n=16). Total blood DCs were identified as lineage (lin) and HLADR, and DC subtypes with blood DC antigen (BDCA)-1 for mDCs and BDCA-2 for pDCs. Flow-mediated dilatation (FMD) was measured in the brachial artery.

RESULTS

Numbers of total blood DCs, mDCs and pDCs declined in CAD patients compared with control patients, but without differences between the CAD groups. Interleukin-6 and high sensitivity C-reactive protein displayed inverse associations with mDCs. A FMD below the median of the study population, use of beta-blockers or of lipid-lowering drugs was associated with increased mDCs, whereas pDCs were similar. Interestingly, the effects of drugs and FMD were additive with that of CAD.

CONCLUSION

This study indicates that lower blood DCs do not result from medication intake or endothelial dysfunction, and are an overall systemic effect of atherosclerosis rather than CAD type (stable or unstable) or number of stenotic coronary arteries. In view of discrete associations with cytokines, FMD, beta-blockers and statins, mDCs and pDCs seem to behave differently and may influence inflammation during atherosclerosis in different ways.

Inflammatory and autoimmune reactions in atherosclerosis and vaccine design informatics

Atherosclerosis is the leading pathological contributor to cardiovascular morbidity and mortality worldwide. As its complex pathogenesis has been gradually unwoven, the regime of treatments and therapies has increased with still much ground to cover. Active research in the past decade has attempted to develop antiatherosclerosis vaccines with some positive results. Nevertheless, it remains to develop a vaccine against atherosclerosis with high affinity, specificity, efficiency, and minimal undesirable pathology. In this review, we explore vaccine development against atherosclerosis by interpolating a number of novel findings in the fields of vascular biology, immunology, and bioinformatics. With recent technological breakthroughs, vaccine development affords precision in specifying the nature of the desired immune response—useful when addressing a disease as complex as atherosclerosis with a manifold of inflammatory and autoimmune components. Moreover, our exploration of available bioinformatic tools for epitope-based vaccine design provides a method to avoid expenditure of excess time or resources.

Statins reduce endothelial cell apoptosis via inhibition of TRAIL expression on activated CD4 T cells in acute coronary syndrome

OBJECTIVE

Statins reduce cardiovascular-related morbidity and mortality, but their effects on inflammation in atherosclerosis are not fully understood. We investigated whether statins can modulate cytotoxic functions of CD4 T cells in acute coronary syndrome (ACS).

METHODS AND RESULTS

Fresh CD4 T cells were isolated from 55 patients with ACS without statin treatment on admission and from 34 age-matched controls. CD4 T cells collected from ACS patients induced endothelial cell apoptosis significantly more than control T cells. The TNF-related apoptosis-inducing ligand (TRAIL) receptor DR5 was strongly upregulated on endothelial cells, and TRAIL-specific antibodies effectively blocked CD4 T cell-mediated apoptosis, indicating that T cell-mediated endothelial death was dependent on the TRAIL pathway. Expression of both the activating antigen CD69 and TRAIL was enhanced on ACS T cells. In in-vitro assays rosuvastatin, fluvastatin, and pitavastatin directly blocked CD4 T cell-mediated endothelial cell apoptosis and reduced T cell-expression of CD69 and TRAIL through TCR-induced Extracellar signal-Regulated Kinases (ERK) activation.

CONCLUSIONS

Activated CD4 T cells expressing TRAIL are enriched in the blood of ACS patients and induce endothelial injury, which may contribute to the destabilization of the plaque. Early statin therapy may suppress T cell-mediated endothelial cell damage in atherosclerotic plaques and thus prevent cardiovascular events.