Atherosclerosis: role of chemokines and macrophages

Hyaluronic Acid Nanoparticles as Nanomedicine for Treatment of Inflammatory Diseases

Owing to their unique biological functions, hyaluronic acid (HA) and its derivatives have been explored extensively for biomedical applications such as tissue engineering, drug delivery, and molecular imaging. In particular, self-assembled HA nanoparticles (HA-NPs) have been used widely as target-specific and long-acting nanocarriers for the delivery of a wide range of therapeutic or diagnostic agents. Recently, it has been demonstrated that empty HA-NPs without bearing any therapeutic agent can be used therapeutically for the treatment of inflammatory diseases via modulating inflammatory responses. In this review, we aim to provide an overview of the significant achievements in this field and highlight the potential of HA-NPs for the treatment of inflammatory diseases.

The important role of histone deacetylases in modulating vascular physiology and arteriosclerosis

Cardiovascular diseases are the leading cause of deaths in the world. Endothelial dysfunction followed by inflammation of the vessel wall leads to atherosclerotic lesion formation that causes ischemic heart and myocardial hypertrophy, which ultimately progress into cardiac dysfunction and failure. Histone deacetylases (HDACs) have been recognized to play crucial roles in cardiovascular disease, particularly in the epigenetic regulation of gene transcription in response to a variety of stresses. The unique nature of HDAC regulation includes that HDACs form a complex co-regulatory network with other transcription factors, deacetylate histones and non-histone proteins to facilitate the regulatory mechanism of the vascular system. The selective HDAC inhibitors are considered as the most promising target in cardiovascular disease, especially for preventing cardiac hypertrophy. In this review, we discuss our present knowledge of the cellular and molecular basis of HDACs in mediating the biological function of vascular cells and related pharmacologic interventions in vascular disease.

Atherosclerosis Treatment with Stimuli-Responsive Nanoagents: Recent Advances and Future Perspectives

Atherosclerosis is the root of approximately one-third of global mortalities. Nanotechnology exhibits splendid prospects to combat atherosclerosis at the molecular level by engineering smart nanoagents with versatile functionalizations. Significant advances in nanoengineering enable nanoagents to autonomously navigate in the bloodstream, escape from biological barriers, and assemble with their nanocohort at the targeted lesion. The assembly of nanoagents with endogenous and exogenous stimuli breaks down their shells, facilitates intracellular delivery, releases their cargo to kill the corrupt cells, and gives imaging reports. All these improvements pave the way toward personalized medicine for atherosclerosis. This review systematically summarizes the recent advances in stimuli-responsive nanoagents for atherosclerosis management and its progress in clinical trials.

Functional macrophages and gastrointestinal disorders

Macrophages (MΦ) differentiate from blood monocytes and participate in innate and adaptive immunity. Because of their abilities to recognize pathogens and activate bactericidal activities, MΦ are always discovered at the site of immune defense. MΦ in the intestine are unique, such that in the healthy intestine, they possess complex mechanisms to protect the gut from inflammation. In these complex mechanisms, they produce anti-inflammatory cytokines, such as interleukin-10 and transforming growth factor-β, and inhibit the inflammatory pathways mediated by Toll-like receptors. It has been demonstrated that resident MΦ play a crucial role in maintaining intestinal homeostasis, and they can be recognized by their unique markers. Nonetheless, in the inflamed intestine, the function of MΦ will change because of environmental variation, which may be one of the mechanisms of inflammatory bowel disease (IBD). We provide further explanation about these mechanisms in our review. In addition, we review recent discoveries that MΦ may be involved in the development of gastrointestinal tumors. We will highlight the possible therapeutic targets for the management of IBD and gastrointestinal tumors, and we also discuss why more details are needed to fully understand all other effects of intestinal MΦ.

Rhizoma Coptidis: A Potential Cardiovascular Protective Agent

Cardiovascular diseases (CVDs) are among the leading causes of morbidity and mortality in both the developed and developing world. Rhizoma coptidis (RC), known as Huang Lian in China, is the dried rhizome of medicinal plants from the family Ranunculaceae, such as Coptis chinensis Franch, C. deltoidea C.Y. Cheng et Hsiao, and C. teeta Wall which has been used by Chinese medicinal physicians for more than 2000 years. In China, RC is a common component in traditional medicines used to treat CVD associated problems including obesity, diabetes mellitus, hyperlipidemia, hyperglycemia and disorders of lipid metabolism. In recent years, numerous scientific studies have sought to investigate the biological properties of RC to provide scientific evidence for its traditional medical uses. RC has been found to exert significant beneficial effects on major risk factors for CVDs including anti-atherosclerotic effect, lipid-lowering effect, anti-obesity effect and anti-hepatic steatosis effect. It also has myocardioprotective effect as it provides protection from myocardial ischemia-reperfusion injury. These properties have been attributed to the presence of bioactive compounds contained in RC such as berberine, coptisine, palmatine, epiberberine, jatrorrhizine, and magnoflorine; all of which have been demonstrated to have cardioprotective effects on the various parameters contributing to the occurrence of CVD through a variety of pathways. The evidence available in the published literature indicates that RC is a herb with tremendous potential to reduce the risks of CVDs, and this review aims to summarize the cardioprotective properties of RC with reference to the published literature which overall indicates that RC is a herb with remarkable potential to reduce the risks and damage caused by CVDs.

Challenges to develop novel anti-inflammatory and analgesic drugs

Chronic inflammatory diseases and persistent pain of different origin represent common medical, social, and economic burden, and their pharmacotherapy is still an unresolved issue. Therefore, there is a great and urgent need to develop anti-inflammatory and analgesic agents with novel mechanisms of action, but it is a very challenging task. The main problem is the relatively large translational gap between the preclinical experimental data and the clinical results due to characteristics of the models, difficulties with the investigational techniques particularly for pain, as well as species differences in the mechanisms. We summarize here the current state-of-the-art medication and related ongoing strategies, and the novel targets with lead molecules under clinical development. The first members of the gold-standard categories, such as nonsteroidal anti-inflammatory drugs, glucocorticoids, and opioids, were introduced decades ago, and since then very few drugs with novel mechanisms of action have been successfully taken to the clinics despite considerable development efforts. Several biologics targeting different key molecules have provided breakthrough in some autoimmune/inflammatory diseases, but they are expensive, only parenterally available, their long-term side effects often limit their administration, and they do not effectively reduce pain. Some kinase inhibitors and phosphodiesterase-4 blockers have recently been introduced as new directions. There are in fact some promising novel approaches at different clinical stages of drug development focusing on transient receptor potential vanilloid 1/ankyrin 1 channel antagonism, inhibition of voltage-gated sodium/calcium channels, several enzymes (kinases, semicarbazide-sensitive amine oxidases, and matrix metalloproteinases), cytokines/chemokines, transcription factors, nerve growth factor, and modulation of several G protein-coupled receptors (cannabinoids, purinoceptors, and neuropeptides). WIREs Nanomed Nanobiotechnol 2017, 9:e1427. doi: 10.1002/wnan.1427 For further resources related to this article, please visit the WIREs website.

Higher macrophage superoxide anion production in coronary artery disease (CAD) patients with Type D personality

BACKGROUND

Type D personality (Type D) is an independent psychosocial risk factor for poor cardiac prognosis and increased mortality in patients with cardiovascular disease (CVD), but the involved mechanisms are poorly understood. Macrophages play a pivotal role in atherosclerosis, the process underlying coronary artery disease (CAD). We investigated macrophage superoxide anion production in production in CAD patients with and without Type D.

METHODS AND RESULTS

We studied 20 male CAD patients with Type D (M:66.7±9.9years) and 20 age-matched male CAD patients without Type D (M:67.7±8.5years). Type D was measured using the DS14 questionnaire with the two subscales 'negative affectivity' and 'social inhibition'. We assessed macrophage superoxide anion production using the WST-1 assay. All analyses were controlled for potential confounders. CAD patients with Type D showed higher superoxide anion production compared to CAD patients without Type D (F(1,38)=15.57, p<0.001). Complementary analyses using the Type D subscales 'negative affectivity' and 'social inhibition', and their interaction as continuous measures, showed that both Type D subscales (negative affectivity: (ß=0.48, p=0.002, R(2)=0.227); social inhibition: (ß=0.46, p=0.003, R(2)=0.208)) and their interaction (ß=0.36, p=0.022, R(2)=0.130) were associated with higher WST-1 reduction scores. Results remained significant when controlling for classical CVD risk factors (i.e. body mass index, mean arterial blood pressure), atherosclerosis severity (i.e. intima media thickness, presence of carotid plaques), and psychological factors (depressive symptom severity, chronic stress).

CONCLUSIONS

Our results indicate higher macrophage superoxide anion production in CAD patients with Type D compared to those without Type D. This may suggest a mechanism contributing to increased morbidity and mortality in CAD patients with Type D.

ABCA1 rs1883025 polymorphism and risk of age-related macular degeneration

PURPOSE

To evaluate the association of the ABCA1 rs1883025 polymorphism and susceptibility to age-related macular degeneration (AMD).

METHODS

A systematic search of the PubMed, EMBASE, and ISI web of science databases was performed to identify eligible published studies without language restrictions up to September 2015. Pooled odds ratios (ORs) with 95 % confidence intervals (CIs) were estimated under different genetic models using meta-analytic methods. Stratified analysis and sensitivity analysis were performed to explore potential sources of heterogeneity.

RESULTS

A total of 12 articles with 25,445 cases and 36,460 controls were eligible in this meta-analysis. The ABCA1 rs1883025 variant showed significant association with the lower risk of overall AMD under the allelic model (OR= 0.81, 95   %   CI=0.74-0.89). Stratified analysis based on ethnicity demonstrated a strong association between rs1883025 polymorphism and AMD in the Caucasian population, but not in Asian population. For late AMD, the ABCA1 rs1883025 variant was observed to have a significant association with the lower risk of this disease (OR = 0.81, 95 % CI, 0.72-0.91). In early-stage AMD, significant associations of the rs1883025 polymorphism with lower risk of early AMD were observed in different genetic models (OR ranging from 0.45 to 0.65, all P < 0.05).

CONCLUSIONS

The present meta-analysis indicated that the T allelic in rs1883025 variant was significantly associated with the risk of developing AMD, particularly at the early stage. The associations of the ABCA1 locus with AMD risk in various populations need further exploration.

Lipid crystallization: from self-assembly to hierarchical and biological ordering

Lipid crystallization is ubiquitous in nature, observed in biological structures as well as in commercial products and applications. In a dehydrated state most of the lipids form well ordered crystals, whereas in an aqueous environment they self-assemble into various crystalline, liquid crystalline or sometimes macroscopically disordered phases. Lipid self-organization extends further to hierarchical levels including structured emulsions and nanostructured particles. Many consumer products including cosmetics, foods and medicines account for such lipid architectures. Cell membranes primarily consist of planar lipid bilayers; however sub-cellular biomembranes are more of a convoluted type. Some of the biological entities have lipids in truly crystalline form; yet liquid crystalline lipid phases are prevalent, in general. Crystallization of fats - triglyceride lipids - has been relatively well documented and reviewed more often, but this review features other areas where lipid organization is crucial and diverse. Some recent advances along with a few explicit examples of model lipid phases and biological evidences are also reported.

The effect of A(2A) adenosine receptor activation on C-C chemokine receptor 7 expression in human THP1 macrophages during inflammation

C-C chemokine receptor 7 (CCR7) and its chemoattractant agonist CCL21 promote cell migration and expression of pro-inflammatory proteins in an atherogenic environment. Since A(2A) adenosine receptor activation reduces migration and inflammatory effects, we examined its effect on CCR7 expression and migration. CCR7 protein expression decreased by about a third in macrophages treated with A(2A) receptor agonist CGS 21680 (p = 0.028, n = 7) and was reversed with antagonist, although mRNA levels increased twofold (p = 0.001, n = 3). Furthermore, macrophages treated with CGS 21680 showed a significant decrease in migration (p = 0.0311, n = 7). These results suggest that A(2A) adenosine receptor activation not only modulates CCR7 expression in both normal and inflammatory environments but also regulates macrophage migration to CCR7-specific chemoattractants.

Control of growth and inflammatory response of macrophages and foam cells with nanotopography

Macrophages play an important role in modulating the immune function of the human body, while foam cells differentiated from macrophages with subsequent fatty streak formation play a key role in atherosclerosis. We hypothesized that nanotopography modulates the behavior and function of macrophages and foam cells without bioactive agent. In the present study, nanodot arrays ranging from 10- to 200-nm were used to evaluate the growth and function of macrophages and foam cells. In the quantitative analysis, the cell adhesion area in macrophages increased with 10- to 50-nm nanodot arrays compared to the flat surface, while it decreased with 100- and 200-nm nanodot arrays. A similar trend of adhesion was observed in foam cells. Immunostaining, specific to vinculin and actin filaments, indicated that a 50-nm surface promoted cell adhesion and cytoskeleton organization. On the contrary, 200-nm surfaces hindered cell adhesion and cytoskeleton organization. Further, based on quantitative real-time polymerase chain reaction data, expression of inflammatory genes was upregulated for the 100- and 200-nm surfaces in macrophages and foam cells. This suggests that nanodots of 100- and 200-nm triggered immune inflammatory stress response. In summary, nanotopography controls cell morphology, adhesions, and proliferation. By adjusting the nanodot diameter, we could modulate the growth and expression of function-related genes in the macrophages and foam cell system. The nanotopography-mediated control of cell growth and morphology provides potential insight for designing cardiovascular implants.

CCR5Δ32 variant and cardiovascular disease in patients with rheumatoid arthritis: a cohort study

Introduction

The aim of our study was to analyze the influence of the CCR5Δ32 polymorphism in the risk of cardiovascular (CV) events and subclinical atherosclerosis among patients with rheumatoid arthritis (RA).

Methods

A total of 645 patients fulfilling the American Rheumatism Association 1987 revised classification criteria for RA were studied. Patients were genotyped for the CCR5 rs333 polymorphism using predesigned TaqMan assays. Also, HLA DRB1 genotyping was performed using molecular-based methods. Carotid intima-media thickness, flow-mediated endothelium-dependent dilatation (FMD) and endothelium-independent vasodilatation, which were used as surrogate markers of subclinical atherosclerosis, were measured in a subgroup of patients with no clinical CV disease.

Results

A lower frequency of carriers of the CCR5Δ32 allele among patients with CV events (3.4% versus 11.3%, P = 0.025, odds ratio 0.28, 95% confidence interval (95% CI) 0.06 to 0.89) was observed. However, after adjusting for gender, age at time of RA diagnosis, and the presence of shared epitope, rheumatoid factor and classic CV risk factors in the Cox regression analysis, this reduction of CV events in CCR5Δ32 allele carriers was slightly outside the range of significance (P = 0.097; hazard ratio 0.37 (95% CI 0.12 to 1.19)). Carriers of the CCR5Δ32 deletion also showed higher FMD values than the remaining patients (CCR5/CCR5Δ32 patients: 7.03% ± 6.61% versus CCR5/CCR5 patients: 5.51% ± 4.66%). This difference was statistically significant when analysis of covariance was performed (P = 0.024).

Conclusions

Our results show a potential influence of the CCR5Δ32 deletion on the risk of CV disease among patients with RA. This may be due to a protective effect of this allelic variant against the development of vascular endothelial dysfunction.

Association of variants in the LIPC and ABCA1 genes with intermediate and large drusen and advanced age-related macular degeneration

PURPOSE

Intermediate and large drusen usually precede advanced age-related macular degeneration (AMD). There is little information about which genes influence drusen accumulation. Discovery of genetic variants associated with drusen may lead to prevention and treatments of AMD in its early stages.

METHODS

A total of 3066 subjects were evaluated on the basis of ocular examinations and fundus photography and categorized as control (n = 221), intermediate drusen (n = 814), large drusen (n = 949), or advanced AMD (n = 1082). SNPs in the previously identified CFH, C2, C3, CFB, CFI, APOE, and ARMS2/HTRA1 genes/regions and the novel genes LIPC, CETP, and ABCA1 in the high-density lipoprotein (HDL) cholesterol pathway were genotyped. Associations between stage of AMD and SNPs were assessed using logistic regression.

RESULTS

Controlling for age, sex, education, smoking, body mass index, and antioxidant treatment, the number of minor (T) alleles of the genes LIPC and ABCA1 were significantly associated with a reduced risk of intermediate drusen (LIPC [P trend = 0.045], ABCA1 [P = 4.4 × 10(-3)]), large drusen (LIPC [P = 0.041], ABCA1 [P = 7.7 × 10(-4)]), and advanced AMD (LIPC [P = 1.8 × 10(-3)], ABCA1 [P = 3 × 10(-4)]). After further adjustment for known genetic factors, the protective effect of the TT genotype was significant for intermediate drusen (LIPC [odds ratio (OR), 0.56; 95% confidence interval (CI), 0.33-0.94], ABCA1 [OR, 0.48; 95% CI, 0.27-0.85]), large drusen (LIPC [OR, 0.58; 95% CI, 0.34-0.98)], ABCA1 [OR, 0.41; 95% CI, 0.23-0.74)]), and advanced AMD (LIPC [OR, 0.39; 95% CI, 0.21-0.74)], ABCA1 [OR, 0.35; 95% CI, 0.17-0.71)]). CFH, C3, C2, and ARMS2/HTRA1 were associated with large drusen and advanced AMD.

CONCLUSIONS

LIPC and ABCA1 are related to intermediate and large drusen, as well as advanced AMD. CFH, C3, C2, and ARMS2/HTRA1 are associated with large drusen and advanced AMD. Genes may have varying effects on different stages of AMD.

Hyaluronic acid immobilized magnetic nanoparticles for active targeting and imaging of macrophages

Imaging and targeted delivery to macrophages are promising new approaches to study and treat a variety of inflammatory diseases such as atherosclerosis. In this manuscript, we have designed and synthesized iron oxide based magnetic nanoparticles bearing hyaluronic acid (HA) on the surface to target activated macrophages. The HA-coated nanoparticles were prepared through a co-precipitation procedure followed by postsynthetic functionalization with HA and fluorescein. The nanoparticles were characterized by transmission electron microscopy, thermogravimetric analysis, elemental analysis, dynamic light scattering, and high-resolution magic angle spinning NMR and were biocompatible with cells and colloidally stable in the presence of serum. The HA immobilized on the nanoparticles retained their specific biological recognition with the HA receptor CD44, which is present on activated macrophages in high-affinity forms. Cell uptake studies demonstrated significant uptake of HA nanoparticles by activated macrophage cell line THP-1, which enabled magnetic resonance imaging of THP-1 cells. The uptake of nanoparticles was found to be both HA and CD44 dependent. Interestingly, Prussian blue staining showed that the magnetite cores of the HA-coated nanoparticles were only transiently present inside the cells, thus reducing the potential concerns of nanotoxicity. Furthermore, fluorescein on the nanoparticle was found to be delivered to the cell nucleus. Therefore, with further development, these HA functionalized magnetic nanoparticles can potentially become a useful carrier system for molecular imaging and targeted drug delivery to activated macrophages.

An in vitro perfusion system to examine the responses of endothelial cells to simulated flow and inflammatory stimulation

Atherosclerosis is a disease process which develops at the arterial branches and curvatures of medium to large arteries. Local haemodynamic flow patterns in these vessels play an essential role in the formation of atherosclerotic lesions. To simulate pro-atherogenic blood flow patterns, we have developed a perfusion system with the ability to simulate in vivo patterns of blood flow in vitro. In this system, human umbilical vein endothelial cells were seeded in y-shaped microslides, in which they were exposed to a variety of flow patterns. Besides being able to reproduce the disturbed flow involved in the development of pro-atherogenic events within the arterial wall, the system also permitted the assessment of the pre-conditioning/priming effect of oscillatory flow on endothelial cells. The system was further capable of integrating multi-endpoint assays relevant to cardiovascular disease. We show that oscillatory flow primed endothelial cells, making them more sensitive to subsequent treatments. The treatment of oscillatory flow primed cells with TNFalpha resulted in the detection of enhanced levels of pro-inflammatory and chemoattractant factors such as IL-8 and MCP-1. These measurements were facilitated by the small volumes of medium circulating within the perfusion system. Oscillatory flow also altered the characteristics of monocyte adhesion to the endothelial layer. In summary, this system allows the monitoring of multiple endpoints and biomarkers, and provides an alternative to the use of in vivo and ex vivo models of cardiovascular disease.

Angiopoietin-1/Tie2 signaling pathway inhibits lipopolysaccharide-induced activation of RAW264.7 macrophage cells

Angiopoietin-1 (Ang1) is a ligand for the endothelial-specific tyrosine kinase receptor Tie2 and has been shown to play an essential role in embryonic vasculature development. There have been many studies about the anti-inflammatory effects of Ang1, most of which focus on endothelium cells. In the present study, we explore the role of Ang1-Tie2 signaling in the activation of macrophages upon lipopolysaccharide (LPS) stimulation. We found that Tie2 receptor is expressed on macrophages and Ang1 could inhibit LPS-induced activation of macrophages, as evidenced by cell migration and TNF-alpha production, specifically through Tie2 receptor. We further investigated the mechanism and found that Ang1-Tie2 could block LPS-induced activation of NF-kappaB which has been shown to be necessary for macrophage activation with LPS treatment. Thus, we described, for the first time, the role of Ang1-Tie2 signaling in macrophage activation and the possible mechanisms in response to immune stimulation.

Interleukin-6 aborts lymphopoiesis and elevates production of myeloid cells in systemic lupus erythematosus-prone B6.Sle1.Yaa animals

We previously reported the inhibitory action of interleukin-6 (IL-6) on B lymphopoiesis with SHIP(-/-) mice and showed that IL-6 biases lineage commitment toward myeloid cell fates in vitro and in vivo. Because elevated IL-6 is a feature of chronic inflammatory diseases, we applied an animal model of systemic lupus erythematosus (SLE) to determine whether IL-6 has similar effects on hematopoiesis. We found that IL-6 levels were elevated in the B6.Sle1.Yaa mice, and the increase was accompanied by losses of CD19(+) B cells and more primitive B-lymphoid progenitors in bone marrow. Both the CD19(+) B-cell population and their progenitors recovered in an IL-6(-/-) background. The uncommitted progenitors, containing precursors for both lymphoid and myeloid fates, expressed IL-6 receptor-alpha chain and responded to IL-6 by phosphorylation of STAT3. IL-6 stimulation caused uncommitted progenitors to express the Id1 transcription factor, which is known to inhibit lymphopoiesis and elevate myelopoiesis, and its expression was MAPK dependent. We conclude that chronic inflammatory conditions accompanied by increased IL-6 production bias uncommitted progenitors to a myeloid fate by inducing Id1 expression.

Cholesterol accumulation by macrophages impairs phagosome maturation

Macrophages are key to the pathogenesis of atherosclerosis. They take up and store excessive amounts of cholesterol associated with modified low density lipoprotein, eventually becoming foam cells that display altered immune responsiveness. We studied the effects of cholesterol accumulation on phagosome formation and maturation, using lipid transport antagonists and cholesterol transport-deficient mutants. In macrophages treated with U18666A, a transport antagonist that prevents cholesterol exit from late endosomes/lysosomes, the early stages of maturation proceeded normally; phagosomes acquired Rab5, phosphatidylinositol 3-phosphate, and EEA1 and merged with LAMP-containing vesicles. However, fusion with lysosomes was impaired. Rab7, which is required for phagolysosome formation, was acquired by phagosomes but remained inactive. Maturation was also studied in fibroblasts from Niemann-Pick type C individuals that have defective cholesterol transport. Transfection of FcgammaIIA receptors was used to confer phagocytic capability to these fibroblasts. Niemann-Pick type C phagosomes failed to fuse with lysosomes, whereas wild type fibroblasts formed normal phagolysosomes. These findings indicate that cholesterol accumulation can have a detrimental effect on phagosome maturation by impairing the activation of Rab7, sequestering it and its effectors in cholesterol-enriched multilamellar compartments.

Antigen-induced immunomodulation in the pathogenesis of atherosclerosis

Atherosclerosis is a chronic inflammatory disorder characterised by the accumulation of monocytes/macrophages, smooth muscle cells, and lymphocytes within the arterial wall in response to the release of proinflammatory molecules. Such accumulation results in the formation of the atherosclerotic plaque, which would eventually evolve to complications such as total artery occlusion, rupture, calcification, or aneurysm. Although the molecular mechanism responsible for the development of atherosclerosis is not completely understood, it is clear that the immune system plays a key role in the development of the atherosclerotic plaque and in its complications. There are multiple antigenic stimuli that have been associated with the pathogenesis of atherosclerosis. Most of these stimuli come from modified self-molecules such as oxidised low-density lipoproteins (oxLDLs), beta2glycoprotein1 (β2GP1), lipoprotein a (LP(a)), heat shock proteins (HSPs), and protein components of the extracellular matrix such as collagen and fibrinogen in the form of advanced glycation-end (AGE) products. In addition, several foreign antigens including bacteria such as Porphyromonas gingivalis and Chlamydia pneumoniae and viruses such as enterovirus and cytomegalovirus have been associated with atherosclerosis as potentially causative or bystander participants, adding another level of complexity to the analysis of the pathophysiology of atherosclerosis. The present review summarises the most important scientific findings published within the last two decades on the importance of antigens, antigen stimulation, and adaptive immune responses in the development of atherosclerotic plaques.

Two-photon microscopy on vital carotid arteries: imaging the relationship between collagen and inflammatory cells in atherosclerotic plaques

We used two-photon laser scanning microscopy (TPLSM) to demonstrate for the first time its potential in studying relational details at the cellular level of atherogenesis in intact, viable mouse carotid arteries. Isolated and mounted arteries of ApoE-/-mice, aged 15 or 21 weeks (7 and 13 weeks on western diet), were imaged after labeling with specific fluorescent markers for cell nuclei, inflammatory cells, collagen, and lipids. Data were compared with C57BL6/J mice fed a chow diet. Control vessels had intact endothelium without adhering blood cells or significant intimal collagen labeling. In ApoE-/-mice already at 15 weeks, inflammatory cells adhered to the endothelium and increased labeling of collagen was observed in tunica intima at both lesion-prone and non-lesion-prone sites, indicating endothelium activation. In plaques, internalized inflammatory cell density increased with age and plaque progression in tunicae adventitia and intima, but not media. In the whole plaque, aging or plaque progression did not alter the direct relationship between inflammatory cells and collagen. However, within the fibrous caps specifically, direct contact between inflammatory cells and collagen increased with age. This study demonstrates the potential of TPLSM in determining detailed information regarding the complex relationship between inflammatory cells and collagen during atherogenesis.

Expression and function of ephrin-B1 and its cognate receptor EphB2 in human atherosclerosis: from an aspect of chemotaxis

Although several cytokines and chemokines have been demonstrated to play pivotal roles in the pathophysiological conditions of atherosclerosis, few findings exist regarding the expression and function of cytokine-modulating molecules such as ephrin-Bs and their cognate receptors, EphBs, in human atherosclerosis. Therefore, in the present study, we screened novel genes modulating atherogenesis by cDNA array and quantitatively determined them by real-time RT (reverse transcription)-PCR in human carotid atherosclerotic plaques. Ephrin-B1 and EphB2, key regulators of embryogenesis, were significantly up-regulated in plaques compared with those in adjacent control tissues [ephrin-B1, 0.638+/-0.106 compared with 0.831+/-0.152, or 130% (P<0.05); EphB2, 1.296+/-0.281 compared with 2.233+/-0.506, or 172% (P<0.05)]. Immunohistological analysis demonstrated that both ephrin-B1 and EphB2 were expressed in macrophages and T-lymphocytes in plaques as well as in monocytes, T-lymphocytes and arterial endothelial cells isolated from healthy adults. Interestingly, the extracellular domains of ephrin-B1 and EphB2, the expression of which were both enhanced in stimulated THP-1 cells, significantly inhibited spontaneous (22.5 and 27.6% respectively; P<0.01) and MCP-1 (monocyte chemoattractant protein-1)-dependent (29.7 and 22.6% respectively; P<0.01) migration of monocytes. In conclusion, these results demonstrate that ephrin-B1 and EphB2 are overexpressed in atherosclerotic tissue and might locally regulate cell migration, possibly through modulating cytokine-related chemotaxic activity; however, the functional role of these molecules in atherogenesis should be investigated further.

Alzheimer's, atherosclerosis, and aggregates: a role for bacterial degradation

Several of the most prevalent and severe age-related diseases, notably Alzheimer's disease and atherosclerosis, feature the accumulation of non-degradable aggregates within the lysosomes of disease-affected cells. At an early point in disease progression, the breakdown of lysosomal contents by the resident catabolic enzymes stops working properly. A return of lysosomal enzymatic activity to pre-disease levels may restore aggregate elimination. In this review, a method of bioremediation-derived lysosomal enzyme enhancement is proposed, featuring the cellular introduction of microbial-isolated enzymes, or xenoenzymes. The benefits and challenges of using xenoenzymes to break down aggregates are discussed. As the size of our elderly population grows, the incidence of age-related diseases will increase, necessitating the exploration of radical, but potentially powerful, therapeutic strategies.

Engineering away lysosomal junk: medical bioremediation

Atherosclerosis, macular degeneration, and neurodegenerative diseases such as Alzheimer's disease, are associated with the intracellular accumulation of substances that impair cellular function and viability. Reversing this accumulation may be a valuable therapy, but the accumulating substances resist normal cellular catabolism. On the other hand, these substances are naturally degraded in the soil and water by microorganisms. Thus, we propose the concept of "medical bioremediation," which derives from the successful field of in situ environmental bioremediation of petroleum hydrocarbons. In environmental bioremediation, communities of microorganisms mineralize hydrophobic organics using a series of enzymes. In medical bioremediation, we hope to utilize one or several microbial enzymes to degrade the intracellular accumulators enough that they can be cleared from the affected cells. Here, we present preliminary, but promising results for the bacterial biodegradation of 7-ketocholesterol, the main accumulator of foam cells associated with atherosclerosis. In particular, we report on the isolation of several Nocardia strains able to biodegrade 7-ketocholesterol and as an ester of 7-ketocholoesterol. We also outline key intermediates in the biodegradation pathway, a key step towards identifying the key enzymes that may lead to a therapy.

Nuclear translocation of p65 NF-kappaB is sufficient for VCAM-1, but not ICAM-1, expression in TNF-stimulated smooth muscle cells: Differential requirement for PARP-1 expression and interaction

Although nuclear translocation of NF-kappaB and subsequent binding to promoters of ICAM-1 and VCAM-1 have been shown to be decisive for their expression, a number of discrepancies in the expression patterns of these adhesion molecules have been reported in both cell culture systems and disease settings, including atherosclerosis, asthma, and autoimmune diseases. Here we show that while p65 NF-kappaB nuclear translocation in TNF-treated smooth muscle cells (SMCs) was sufficient for the expression of VCAM-1, expression of ICAM-1 showed a critical requirement for PARP-1. I-kappaBalpha phosphorylation and subsequent degradation were virtually identical in both TNF-treated wild-type and PARP-1-/- SMCs. VCAM-1 expression in TNF-treated PARP-1-/- SMCs was completely inhibited by the NF-kappaB inhibitor, pyrrolidine dithiocarbamate, confirming that VCAM-1 expression was indeed NF-kappaB-dependent. The expression of both VCAM-1 and ICAM-1 was associated with a transient interaction between PARP-1 and p65 NF-kappaB when examined in the fibroblastic cell line, COS-7, and in the airway epithelial cell line, A549. Such interactions were confirmed using florescence resonance energy transfer analysis. Protein acetylation activity, mediated by p300/CBP, was required for both VCAM-1 and ICAM-1 expression in TNF-treated SMCs; however, the interaction of PARP-1 with p300/CBP was dispensable for VCAM-1 expression. These findings indicate that p65 NF-kappaB nuclear translocation may be sufficient for certain genes (e.g., VCAM-1) while insufficient for others (e.g., ICAM-1), thus providing a novel insight into the role of NF-kappaB in driving target gene expression. Furthermore, the data suggest a differential requirement for PARP-1 expression in inflammatory processes.

Systems biology of macrophages

Cells and tissues function in context. Under a given growth or survival medium they perform tasks, replicate and die. Given a stimulus they respond by invoking myriad biomolecular networks that result in a specified cellular outcome. At any given instant it can be argued that the cell is in a "state" defined by its components--their concentrations and locations, the interactions between components--that are modulated in space and time, and the complex circuitry--that involves a large number of interacting networks and a snapshot of the dynamical processes--such as gene expression, cell cycle, transport of components, etc. At present, we can measure, using high and low throughput methods, several cellular components in a context-dependent manner and obtain a partial picture of cellular networks and dynamical processes. Are these measurements sufficient to answer important biological questions and help reconstruct a systems-level understanding of a mammalian cell? This chapter will address systems biology strategies developed to address this question and demonstrate the power of integration of diverse cellular data for answering interesting biological questions in macrophages. We will use this systems biology approach to address the following questions: (1) How good are macrophage cell lines in addressing phenotypic biology of primary macrophages? (2) How do signals associated with inflammatory molecules regulate gene transcription in macrophages? (3) How can we combine proteomic and other cellular measurements to characterize the repertoire of upstream signaling networks invoked by macrophages? (4) How do designed knockdowns of proteins influence cellular phenotypes?

Oxidative stress and autophagy

Organisms respond to oxidative injury by orchestrating a stress response to prevent further damage. An increase in the intracellular levels of antioxidant agents, and at the same time the removal of already damaged components, are both part of the oxidative stress response. Lysosomes have been classically considered one of the main targets of the reactive oxygen species. In fact, the destabilization of the lysosomal membrane during oxidizing conditions promotes the leakage of the enzymes contained in these organelles and contributes to cellular damage. However, recent evidence supports a protective role of the lysosomal system, which can eliminate altered intracellular components through autophagy, at least in the first stages of oxidative injury. Consequently, activation of the main intracellular proteolytic systems, the ubiquitin/proteasome, and also the lysosomal/autophagic system occurs during the oxidative stress response. The opposing roles for the lysosomal system under oxidizing conditions are discussed in this review.

Pitavastatin-induced downregulation of CCR2 and CCR5 in monocytes is associated with the arrest of cell-cycle in S phase

The pleiotropic effects of statin, including its anti-inflammatory effects, via chemokines may be independent of statin-induced cholesterol reduction. Therefore, we examined the effect of pitavastatin on cell proliferation and the association between chemokine receptors (CCR2 and CCR5) and their ligands, RANTES (regulated upon activation, normal T cell-expressed and secreted) and monocyte chemotactic protein-1 (MCP-1), in monocytes. Pitavastatin but not pravastatin inhibited cell proliferation in a dose-dependent manner and showed S-phase arrest associated with the downregulation of CCR2 and CCR5 expression in human monocytic tumor cells (U937 cells). Although the anti-proliferative effects of pitavastatin were not inhibited by lower concentrations of RANTES and MCP-1, overexpression of CCR2/CCR5 significantly blocked the anti-proliferation with a low concentration of RANTES or MCP-1. Pitavastatin upregulated p21(waf1) but not p27(kip1), and did not change the expression levels of cyclin D1 or cdk4. In addition, RANTES and MCP-1 upregulated cyclin D1 in the presence of pitavastatin. In conclusion, the anti-proliferative effect of pitavastatin, but not pravastatin, through the downregulation of CCR2/CCR5 may be a pleiotropic effect. This effect may be anti-atherogenic in monocytes.

Monocyte recruitment and foam cell formation in atherosclerosis

Atherosclerosis is a chronic immune-inflammatory disease in which the interactions of monocytes with activated endothelium are crucial events leading to atherosclerotic alteration of the arterial intima. In early atherosclerosis, monocytes migrate into the subendothelial layer of the intima where they differentiate into macrophages or dendritic cells. In the subendothelial space enriched with atherogenic lipoproteins, most macrophages transform into foam cells. Foam cells aggregate to form the atheromatous core and as this process progresses, the atheromatous centres of plaques become necrotic, consisting of lipids, cholesterol crystals and cell debris. This review highlights some aspects of monocyte recruitment and foam cell formation in atherosclerosis.

Medical bioremediation: prospects for the application of microbial catabolic diversity to aging and several major age-related diseases

Several major diseases of old age, including atherosclerosis, macular degeneration and neurodegenerative diseases are associated with the intracellular accumulation of substances that impair cellular function and viability. Moreover, the accumulation of lipofuscin, a substance that may have similarly deleterious effects, is one of the most universal markers of aging in postmitotic cells. Reversing this accumulation may thus be valuable, but has proven challenging, doubtless because substances resistant to cellular catabolism are inherently hard to degrade. We suggest a radically new approach: augmenting humans' natural catabolic machinery with microbial enzymes. Many recalcitrant organic molecules are naturally degraded in the soil. Since the soil in certain environments - graveyards, for example - is enriched in human remains but does not accumulate these substances, it presumably harbours microbes that degrade them. The enzymes responsible could be identified and engineered to metabolise these substances in vivo. Here, we survey a range of such substances, their putative roles in age-related diseases and the possible benefits of their removal. We discuss how microbes capable of degrading them can be isolated, characterised and their relevant enzymes engineered for this purpose and ways to avoid potential side-effects.

Carotid atherosclerotic plaques from symptomatic stroke patients share the molecular fingerprints to develop in a neoplastic fashion: a microarray analysis study

Identification of genetic mechanisms that promote the onset of stroke and transient cerebral ischemic attack symptoms in carotid atherosclerotic patients would further our understanding of the pathophysiology of this disease and could lead to new pharmacological and molecular therapies. Using Affymetrix Human Genome 230 GeneChip set, the present study evaluated the gene expression differences in geometrically similar carotid artery plaque samples extricated from six symptomatic stroke patients and four asymptomatic patients. There was no significant difference in the degree of stenosis between the two groups. Of the 44,860 transcripts analyzed, 289 (approximately 0.6% of the total transcripts) were differentially expressed between the plaques from the symptomatic and asymptomatic groups (236 were expressed more abundantly and 53 were expressed less abundantly in the symptomatic group). Of the 236 transcripts expressed more abundantly in the symptomatic plaques, 71% (167 transcripts) indicate an active cell proliferation and neoplastic process. These include oncogenes, growth factors, tumor promoters, tumor markers, angiogenesis promoters, transcription factors, RNA splicing factors, RNA processing proteins, signal transduction mediators and those that control the metabolism. Real-time polymerase chain reaction confirmed the increased expression of 63 transcripts in the symptomatic plaques. The other groups of transcripts expressed more abundantly in the symptomatic plaques are those that control ionic homeostasis, those that participate in the progression of degenerative neurological diseases (Alzheimer's disease, amyotrophic lateral sclerosis and Huntington's disease) and epilepsy. This indicates that symptomatic plaques are molecularly and biochemically more active than the asymptomatic plaques, or active plaque growth precipitates stroke symptoms.