Antagonism of RANTES Receptors Reduces Atherosclerotic Plaque Formation in Mice

Interleukin-27 enhances TNF-α-mediated activation of human coronary artery endothelial cells

Immune cells and inflammatory mediators play important roles in the development of atherosclerotic vascular inflammation. IL-27 is a member of the IL-6/IL-12 family that can promote Th1 responses and augment the release of inflammatory mediators from human mast cells and monocytes. However, the direct effect of IL-27 on human coronary artery endothelial cells was unclear. In this study, the effects of IL-27 and TNF-α on the cell surface expression of adhesion molecules, inflammatory cytokines, and chemokines were investigated. Results showed that IL-27 alone could significantly promote the release of chemokine CXCL10. However, IL-27 could further significantly enhance the TNF-α-mediated upregulation of adhesion molecules ICAM-1 and VCAM-1, inflammatory cytokine IL-6, as well as chemokines CCL5 and CXCL10 from human coronary artery endothelial cells. The release of IL-6, CCL5, and CXCL10 were significantly suppressed by specific signaling molecule inhibitors, implying that the induction of these mediators from the human coronary artery endothelial cells could be differentially regulated by the c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, and nuclear factor-κB pathways. These results provided new insights into the effect of IL-27 on the TNF-α mediated activation of human coronary artery endothelial cells in atherosclerotic vascular inflammation.

Elevated RANTES level is associated with metabolic syndrome and correlated with activated platelets associated markers in healthy younger men

The objective of this study was to clarify the relationship of regulated on activation normal T cell expressed and secreted (RANTES) levels with metabolic syndrome (MS) and activated platelets-associated markers. We conducted a cross-sectional study of 210 healthy Japanese male volunteers (mean age 41 years old) who did not take any medications and were free of cardiovascular or cerebrovascular disease. The RANTES is correlated with age, diastolic blood pressure, and fast glucose by multivariate analysis using the cardiovascular risk factors (R (2) = .396, P < .001). The plasma RANTES level is significantly associated with MS after adjusting for age (P = .040). Once plasma interleukin 6, an activator of platelets, and plasma platelet-derived microparticles, a marker for activated platelets, are put into the equation, plasma RANTES level is significantly correlated with the activated platelet-associated markers (R (2) = .396, P < .001). These suggest the possible role of elevated RANTES in the forerunner of atherosclerosis in healthy younger men.

No Association between the CCR5Δ32 Polymorphism and Sporadic Esophageal Cancer in Punjab, North-West India

BACKGROUND

Chemokines and their receptors influence carcinogenesis and cysteine-cysteine chemokine receptor 5 (CCR5) directs spread of cancer to other tissues. A 32 base pair deletion in the coding region of CCR5 that might alter the expression or function of the protein has been implicated in a variety of immune-mediated diseases. The action of antiviral drugs being proposed as adjuvant therapy in cancer is dependent on CCR5 wild type status. In the present study, distribution of CCR5Δ32 polymorphism was assessed in North Indian esophageal cancer patients to explore the potential of using chemokine receptors antagonists as adjuvant therapy.

MATERIALS AND METHODS

DNA samples of 175 sporadic esophageal cancer patients (69 males and 106 females) and 175 unrelated healthy control individuals (69 males and 106 females) were screened for the CCR5Δ32 polymorphism by direct polymerase chain reaction (PCR).

RESULTS

The frequencies of wild type homozygous (CCR5/CCR5), heterozygous (CCR5/Δ32) and homozygous mutant (Δ32/Δ32) genotypes were 96.0 vs 97.72%, 4.0 vs 1.71% and 0 vs 0.57% in patients and controls respectively. There was no difference in the genotype and allele frequencies of CCR5Δ32 polymorphism in esophageal cancer patients and control group.

CONCLUSIONS

The CCR5Δ32 polymorphism is not associated with esophageal cancer in North Indians. As the majority of patients express the wild type allele, there is potential of using antiviral drug therapy as adjuvant therapy.

Chemokines Control Mobilization, Recruitment, and Fate of Monocytes in Atherosclerosis

Atherosclerosis is a chronic inflammatory disease of large arteries and, among others, characterized by continuous influx of monocytes into the subendothelial space, subsequent macrophage accumulation, and foam cell formation. Chemokines and their receptors tightly orchestrate monocyte trafficking and fate from birth to death. This brief review summarizes our current understanding of the interplay between monocytes and chemokines entertaining crucial processes in atherosclerosis development, progression, and regression.

Valproic acid attenuates intercellular adhesion molecule-1 and E-selectin through a chemokine ligand 5 dependent mechanism and subarachnoid hemorrhage induced vasospasm in a rat model

BACKGROUND

Up-regulation of regulated upon activation, normal T-cell expressed and secreted (RANTES/CCL5) and adhesion molecules is observed in the serum of animals following experimental subarachnoid hemorrhage (SAH). The present study was to examine the effect of valproic acid (VPA) on RANTES and alternation of adhesion molecules in this model.

METHODS

A rodent SAH model was employed. Animals were randomly assigned into six groups. Basilar artery (BA) was harvested for intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin evaluation (western blotting) and RANTES (rt-PCR). 1 ng CCL5 recombinant protein intrathecal injection was performed in the VPA + SAH groups. (N = 5).

RESULTS

Convoluted internal elastic lamina, distorted endothelial wall, and smooth muscle micro-necrosis was prominently observed in the SAH groups, which is absent in the VPA treatment and the healthy controls. Treatment with VPA dose-dependently reduced the ICAM-1, E-selectin and RANTES level, compared with the SAH group (p <0.01). The administration of CCL5 significantly increased CD45(+) glia and ICAM-1 level in the VPA treatment groups.

CONCLUSION

VPA exerts its anti-vasospastic effect through the dual effect of inhibiting RANTES expression and reduced adhesion molecules. Besides, VPA also decreased CD45(+) cells transmigrated to the vascular wall. The administration of CCL5 significantly reversed the inhibitory effect of this compound on CD45(+) monocytes, E-selectin, and ICAM-1 level. This study also lends credence to support this compound could attenuate SAH induced adhesion molecules and neuro-inflammation in a CCL5 dependent mechanism.

RGS1 regulates myeloid cell accumulation in atherosclerosis and aortic aneurysm rupture through altered chemokine signalling

Chemokine signalling drives monocyte recruitment in atherosclerosis and aortic aneurysms. The mechanisms that lead to retention and accumulation of macrophages in the vascular wall remain unclear. Regulator of G-Protein Signalling-1 (RGS1) deactivates G-protein signalling, reducing the response to sustained chemokine stimulation. Here we show that Rgs1 is upregulated in atherosclerotic plaque and aortic aneurysms. Rgs1 reduces macrophage chemotaxis and desensitizes chemokine receptor signalling. In early atherosclerotic lesions, Rgs1 regulates macrophage accumulation and is required for the formation and rupture of Angiotensin II-induced aortic aneurysms, through effects on leukocyte retention. Collectively, these data reveal a role for Rgs1 in leukocyte trafficking and vascular inflammation and identify Rgs1, and inhibition of chemokine receptor signalling as potential therapeutic targets in vascular disease.

Deficiency in lymphotoxin β receptor protects from atherosclerosis in apoE-deficient mice

RATIONALE

Lymphotoxin β receptor (LTbR) regulates immune cell trafficking and communication in inflammatory diseases. However, the role of LTbR in atherosclerosis is still unclear.

OBJECTIVE

The aim of this study was to elucidate the role of LTbR in atherosclerosis.

METHODS AND RESULTS

After 15 weeks of feeding a Western-type diet, mice double-deficient in apolipoprotein E and LTbR (apoE(-/-)/LTbR(-/-)) exhibited lower aortic plaque burden than did apoE(-/-) littermates. Macrophage content at the aortic root and in the aorta was reduced, as determined by immunohistochemistry and flow cytometry. In line with a decrease in plaque inflammation, chemokine (C-C motif) ligand 5 (Ccl5) and other chemokines were transcriptionally downregulated in aortic tissue from apoE(-/-)/LTbR(-/-) mice. Moreover, bone marrow chimeras demonstrated that LTbR deficiency in hematopoietic cells mediated the atheroprotection. Furthermore, during atheroprogression, apoE(-/-) mice exhibited increased concentrations of cytokines, for example, Ccl5, whereas apoE(-/-)/LTbR(-/-) mice did not. Despite this decreased plaque macrophage content, flow cytometric analysis showed that the numbers of circulating lymphocyte antigen 6C (Ly6C)(low) monocytes were markedly elevated in apoE(-/-)/LTbR(-/-) mice. The influx of these cells into atherosclerotic lesions was significantly reduced, whereas apoptosis and macrophage proliferation in atherosclerotic lesions were unaffected. Gene array analysis pointed to chemokine (C-C motif) receptor 5 as the most regulated pathway in isolated CD115(+) cells in apoE(-/-)/LTbR(-/-) mice. Furthermore, stimulating monocytes from apoE(-/-) mice with agonistic anti-LTbR antibody or the natural ligand lymphotoxin-α1β2, increased Ccl5 mRNA expression.

CONCLUSIONS

These findings suggest that LTbR plays a role in macrophage-driven inflammation in atherosclerotic lesions, probably by augmenting the Ccl5-mediated recruitment of monocytes.

Chemokine and chemokine receptor structure and interactions: implications for therapeutic strategies

The control of cell migration by chemokines involves interactions with two types of receptors: seven transmembrane chemokine-type G protein-coupled receptors and cell surface or extracellular matrix-associated glycosaminoglycans. Coordinated interaction of chemokines with both types of receptors is required for directional migration of cells in numerous physiological and pathological processes. Accumulated structural information, culminating most recently in the structure of a chemokine receptor in complex with a chemokine, has led to a view where chemokine oligomers bind to glycosaminoglycans through epitopes formed when chemokine subunits come together, while chemokine monomers bind to receptors in a pseudo two-step mechanism of receptor activation. Exploitation of this structural knowledge has and will continue to provide important information for therapeutic strategies, as described in this review.

Protection of vascular endothelial cells from high glucose-induced cytotoxicity by emodin

Induction of endothelial cytotoxicity by hyperglycemia in diabetes has been widely accepted. Emodin is a natural anthraquinone in rhubarb used for treatment of diabetes, but its mechanism of action is not fully understood. This study aimed to examine the potential beneficial effects of emodin on endothelial cytotoxicity caused by high glucose milieu. Culture of human umbilical vein endothelial cells (HUVECs) with high concentrations of glucose resulted in damage to the cells, leading to decreased formazan products by 14-27%, reduced DNA contents by 12-19%, and increased hypodiploid apoptosis by 40-109%. These adverse effects of high glucose could be prevented to a large extent by co-culture with 3 μM of emodin which per se did not affect HUVECs viability. In addition, CCL5 expression of HUVECs cultured in high glucose medium was significantly elevated at both mRNA and protein levels, an effect abolished after treatment with emodin. Moreover, the enhanced adhesion of monocytes to HUVECs (2.1-2.2 fold over control) and elevated chemotaxis activities (2.3-2.4 fold over control) in HUVECs cultured in high glucose medium were completely reversed by emodin. Emodin also suppressed activation of p38 MAPK and ERK1/2 due to high glucose. Our data demonstrated that endothelial cytotoxicity occurred clearly when HUVECs were exposed to high glucose milieu and emodin was able to alleviate the impairments. The protective effects of emodin might be related to the inhibition of CCL5 expression and subsequent cell stress/inflammatory events possibly mediated by activation of MAPK signaling pathways.

Cytokines and Immune Responses in Murine Atherosclerosis

Atherosclerosis is an inflammatory disease of the vessel wall characterized by activation of the innate immune system, with macrophages as the main players, as well as the adaptive immune system, characterized by a Th1-dominant immune response. Cytokines play a major role in the initiation and regulation of inflammation. In recent years, many studies have investigated the role of these molecules in experimental models of atherosclerosis. While some cytokines such as TNF or IFNγ clearly had atherogenic effects, others such as IL-10 were found to be atheroprotective. However, studies investigating the different cytokines in experimental atherosclerosis revealed that the cytokine system is complex with both disease stage-dependent and site-specific effects. In this review, we strive to provide an overview of the main cytokines involved in atherosclerosis and to shed light on their individual role during atherogenesis.

Activation of an innate immune receptor, Nod1, accelerates atherogenesis in Apoe-/- mice

Atherosclerosis is essentially a vascular inflammatory process in the presence of an excess amount of lipid. We have recently reported that oral administration of a nucleotide-binding oligomerization domain (Nod)-1 ligand, FK565, induced vascular inflammation in vivo. No studies, however, have proven the association between Nod1 and atherosclerosis in vivo. To investigate a potential role of NOD1 in atherogenesis, we orally administered FK565 to apolipoprotein E knockout (Apoe(-/-)) mice for 4 wk intermittently and performed quantification of atherosclerotic lesions in aortic roots and aortas, immunohistochemical analyses, and microarray-based gene expression profiling of aortic roots. FK565 administration accelerated the development of atherosclerosis in Apoe(-/-) mice, and the effect was dependent on Nod1 in non-bone marrow origin cells by bone marrow transplantation experiments. Immunohistochemical studies revealed the increases in the accumulation of macrophages and CD3 T cells within the plaques in aortic roots. Gene expression analyses of aortic roots demonstrated a marked upregulation of the Ccl5 gene during early stage of atherogenesis, and the treatment with Ccl5 antagonist significantly inhibited the acceleration of atherosclerosis in FK565-administered Apoe(-/-) mice. Additionally, as compared with Apoe(-/-) mice, Apoe and Nod1 double-knockout mice showed reduced development of atherosclerotic lesions from the early stage as well as their delayed progression and a significant reduction in Ccl5 mRNA levels at 9 wk of age. Data in the present study show that the Nod1 signaling pathway in non-bone marrow-derived cells contributes to the development of atherosclerosis.

Monocyte subsets in atherosclerosis

Endothelial dysfunction and chronic inflammation of the arterial wall continuously drive the development of atherosclerotic lesions. Monocytes, as cells of the innate immunity, are particularly involved in this process. In the last decade, heterogeneity of circulating monocytes has widely been acknowledged, and a recent consensus nomenclature subdivides classical, intermediate and nonclassical monocytes. Accumulating experimental and clinical data suggest a differential, subset-specific contribution of monocytes to the pathology of atherosclerosis. This review summarizes recent key findings on human and mouse monocyte subpopulations, specifically highlighting their phenotype, functional characteristics and mechanisms of recruitment at homeostatic conditions, in atherosclerotic vascular disease, and after acute myocardial infarction.

Impact of age-dependent adventitia inflammation on structural alteration of abdominal aorta in hyperlipidemic mice

Background

The adventitia is suggested to contribute to vascular remodeling; however, the site-selective inflammatory responses in association with the development of atherosclerosis remain to be elucidated.

Methods and Results

Wild-type or apolipoprotein E knockout male C57BL/6J background mice were fed standard chow for 16, 32, and 52 weeks, and the morphology of the aortic arch, descending aorta, and abdominal aorta was compared. Atheromatous plaque formation progressed with age, particularly in the aortic arch and abdominal aorta but not in the descending aorta. In addition, we found that the numbers of macrophages, T-lymphocytes, and microvessels, assessed by anti-F4/80, CD3, and CD31 antibodies, were higher in the adventitia of the abdominal aorta at 52 weeks. These numbers were positively correlated with plaque formation, but negatively correlated with elastin content, resulting in the enlargement of the total vessel area. In aortic tissues, interleukin-6 levels increased in the atheromatous plaque with age, whereas the level of regulated on activation, normal T cell expressed and secreted (RANTES) increased with age, and compared with other sites, it was particularly distributed in inflammatory cells in the adventitia of the abdominal aorta.

Conclusion

This study suggests that adventitial inflammation contributes to the age-dependent structural alterations, and that the activation/inactivation of cytokines/chemokines is involved in the process.

Platelets and their chemokines in atherosclerosis-clinical applications

The concept of platelets as important players in the process of atherogenesis has become increasingly accepted due to accumulating experimental and clinical evidence. Despite the progress in understanding the molecular details of atherosclerosis, particularly by using animal models, the inflammatory and thrombotic roles of activated platelet s especially in the human system remain difficult to dissect, as often only the complications of atherosclerosis, i.e., stroke and myocardial infarction are definable but not the plaque burden. Platelet indices including platelet count and mean platelet volume (MPV) and soluble mediators released by activated platelets are associated with atherosclerosis. The chemokine CXCL4 has multiple atherogenic activities, e.g., altering the differentiation of T cells and macrophages by inhibiting neutrophil and monocyte apoptosis and by increasing the uptake of oxLDL and synergizing with CCL5. CCL5 is released and deposited on endothelium by activated platelets thereby triggering atherogenic monocyte recruitment, which can be attenuated by blocking the corresponding chemokine receptor CCR5. Atheroprotective and plaque stabilizing properties are attributed to CXCL12, which plays an important role in regenerative processes by attracting progenitor cells. Its release from luminal attached platelets accelerates endothelial healing after injury. Platelet surface molecules GPIIb/IIIa, GP1bα, P-selectin, JAM-A and the CD40/CD40L dyade are crucially involved in the interaction with endothelial cells, leukocytes and matrix molecules affecting atherogenesis. Beyond the effects on the arterial inflammatory infiltrate, platelets affect cholesterol metabolism by binding, modifying and endocytosing LDL particles via their scavenger receptors and contribute to the formation of lipid laden macrophages. Current medical therapies for the prevention of atherosclerotic therapies enable the elucidation of mechanisms linking platelets to inflammation and atherosclerosis.

Update on selective treatments targeting neutrophilic inflammation in atherogenesis and atherothrombosis

Atherosclerosis is the most common pathological process underlying cardiovascular diseases. Current therapies are largely focused on alleviating hyperlipidaemia and preventing thrombotic complications, but do not completely eliminate risk of suffering recurrent acute ischaemic events. Specifically targeting the inflammatory processes may help to reduce this residual risk of major adverse cardiovascular events in atherosclerotic patients. The involvement of neutrophils in the pathophysiology of atherosclerosis is an emerging field, where evidence for their causal contribution during various stages of atherosclerosis is accumulating. Therefore, the identification of neutrophils as a potential therapeutic target may offer new therapeutic perspective to reduce the current atherosclerotic burden. This narrative review highlights the expanding role of neutrophils in atherogenesis and discusses on the potential treatment targeting neutrophil-related inflammation and associated atherosclerotic plaque vulnerability.

Roles of the chemokine system in development of obesity, insulin resistance, and cardiovascular disease

The escalating epidemic of obesity has increased the incidence of obesity-induced complications to historically high levels. Adipose tissue is a dynamic energy depot, which stores energy and mobilizes it during nutrient deficiency. Excess nutrient intake resulting in adipose tissue expansion triggers lipid release and aberrant adipokine, cytokine and chemokine production, and signaling that ultimately lead to adipose tissue inflammation, a hallmark of obesity. This low-grade chronic inflammation is thought to link obesity to insulin resistance and the associated comorbidities of metabolic syndrome such as dyslipidemia and hypertension, which increase risk of type 2 diabetes and cardiovascular disease. In this review, we focus on and discuss members of the chemokine system for which there is clear evidence of participation in the development of obesity and obesity-induced pathologies.

Increased proatherogenic monocyte-platelet cross-talk in monocyte subpopulations of patients with stable coronary artery disease

BACKGROUND

Monocytes and platelets are important cellular mediators of atherosclerosis. Human monocytes can be divided into CD14(++) CD16(-) , CD14(++) CD16(+) and CD14(+) CD16(++) cells, which differ in their functional properties. The aim of this study was to examine monocyte subset distribution, monocyte-platelet aggregate (MPA) formation and expression of CCR5, the receptor of the platelet-derived chemokine CCL5, and to determine whether these parameters are altered in individuals with coronary atherosclerosis.

METHODS

Peripheral blood cells from 64 healthy blood donors (HBDs) and 60 patients with stable coronary artery disease (CAD) were stained with antibodies against CD14, CD16, CD42b and CCR5 and analysed by flow cytometry. Circulating CCL5 levels were determined using an enzyme-linked immunosorbent assay.

RESULTS

In patients with CAD, the relative proportion of the CD14(++) CD16(-) monocyte subset was elevated (P < 0.05) and of the CD14(+) CD16(++) subset was reduced (P < 0.001) compared with the HBD group. Furthermore, MPA formation significantly increased in patients with CAD in all three monocyte subsets. In both study groups, the majority of CCR5(+) cells was detected in CD14(++) CD16(+) monocytes (P < 0.001 versus CD14(++) CD16(-) and CD14(+) CD16(++) ), although the CCR5(+) monocyte number was reduced in patients with CAD (CD14(++) CD16(-) /CD14(+) CD16(++) , P < 0.001; CD14(++) CD16(+) , P < 0.05) compared with the HBD group, particularly in those who were not taking statins. Ex vivo incubation of monocytes from HBDs with plasma from patients with CAD also decreased CCR5(+) expression (P < 0.05 versus plasma from HBDs). Serum CCL5 levels were similar in both groups.

CONCLUSIONS

The increased monocyte-platelet cross-talk in patients with CAD might have contributed to atherosclerosis progression. The decreased CCR5(+) monocyte numbers in patients with CAD could have resulted from CCR5(+) cell recruitment into atherosclerotic lesions or CCR5 downregulation in response to circulating factors.

Chemokines in atherosclerosis: proceedings resumed

Chemokines play important roles in atherosclerotic vascular disease. Expressed by not only cells of the vessel wall but also emigrated leukocytes, chemokines were initially discovered to direct leukocytes to sites of inflammation. However, chemokines can also exert multiple functions beyond cell recruitment. Here, we discuss novel and recently emerging aspects of chemokines and their involvement in atherosclerosis. While reviewing newly identified roles of chemokines and their receptors in monocyte and neutrophil recruitment during atherogenesis and atheroregression, we also revisit homeostatic functions of chemokines, including their roles in cell homeostasis and foam cell formation. The functional diversity of chemokines in atherosclerosis warrants a clear-cut mechanistic dissection and stage-specific assessment to better appreciate the full scope of their actions in vascular inflammation and to identify pathways that harbor the potential for a therapeutic targeting of chemokines in atherosclerosis.

Immunological aspects of atherosclerosis

Atherosclerosis is a complex chronic inflammatory and metabolic disease that involves the collaboration of several cellular components of the immune system and results in thickening of the arterial wall. Atherosclerosis is also the primary cause of coronary artery and cerebrovascular diseases. A multitude of immune cell subsets, soluble molecules such as chemokines and cytokines, and circulating lipids play pivotal roles in atherosclerosis development. In this review, we highlight the role of the immune system in the course of atherosclerotic disease development and discuss the mechanisms involved.

Role of NADPH oxidase isoforms NOX1, NOX2 and NOX4 in myocardial ischemia/reperfusion injury

Myocardial reperfusion injury is mediated by several processes including increase of reactive oxygen species (ROS). The aim of the study is to identify potential sources of ROS contributing to myocardial ischemia-reperfusion injury. For this purpose, we investigated myocardial ischemia/reperfusion pathology in mice deficient in various NADPH oxidase isoforms (Nox1, Nox2, Nox4, as well as Nox1/2 double knockout). Following 30min of ischemia and 24h of reperfusion, a significant decrease in the size of myocardial infarct was observed in Nox1-, Nox2- and Nox1/Nox2-, but not in Nox4-deficient mice. However, no protection was observed in a model of chronic ischemia, suggesting that NOX1 and NOX2-mediated oxidative damage occurs during reperfusion. Cardioprotective effect of Nox1 and Nox2 deficiencies was associated with decrease of neutrophil invasion, but, on the other hand an improved reperfusion injury was also observed in isolated perfused hearts (Langendorff model) suggesting that inflammatory cells were not the major source of oxidative damage. A decrease in global post-reperfusion oxidative stress was clearly detected in Nox2-, but not in Nox1-deficient hearts. Analysis of key signaling pathways during reperfusion suggests distinct cardioprotective patterns: increased phosphorylation was seen for Akt and Erk in Nox1-deficient mice and for Stat3 and Erk in Nox2-deficient mice. Consequently, NOX1 and NOX2 represent interesting drug targets for controlling reperfusion damage associated with revascularization in coronary disease.

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.

Reconstituted high-density lipoprotein modulates activation of human leukocytes

An anti-inflammatory effect of reconstituted High Density Lipoprotein (rHDL) has been demonstrated in atherosclerosis and in sepsis models. An increase of adhesion molecules as well as tissue factor expression on endothelial cells in response to inflammatory or danger signals are attenuated by the treatment with rHDL. Here we show the inhibitory effect of rHDL on the activation of human leukocytes in a whole blood assay as well as on monocyte-derived human dendritic cells (DC). Multiplex analysis of human whole blood showed that phytohaemagglutinin (PHA)-induced secretion of the cytokines IL-1β, IL-1RA, IL-2R, IL-6, IL-7, IL-12(p40), IL-15 and IFN-α was inhibited. Furthermore, an inhibitory effect on the production of the chemokines CCL-2, CCL-4, CCL-5, CXCL-9 and CXCL-10 was observed. Activation of granulocytes and CD14+ monocytes by PHA is inhibited dose-dependently by rHDL shown as decreased up-regulation of ICAM-1 surface expression. In addition, we found a strong inhibitory effect of rHDL on toll-like receptor 2 (TLR2)- and TLR4-mediated maturation of DC. Treatment of DC with rHDL prevented the up-regulation of cell surface molecules CD80, CD83 and CD86 and it inhibited the TLR-driven activation of inflammatory transcription factor NF-κB. These findings suggest that rHDL prevents activation of crucial cellular players of cellular immunity and could therefore be a useful reagent to impede inflammation as well as the link between innate and adaptive immunity.

Pharmacological inhibition of the chemokine receptor, CX3CR1, reduces atherosclerosis in mice

OBJECTIVE

Alterations of the chemokine receptor CX3CR1 gene were associated with a reduced risk of myocardial infarction in human and limited atherosclerosis in mice. In this study, we addressed whether CX3CR1 antagonists are potential therapeutic tools to limit acute and chronic inflammatory processes in atherosclerosis.

APPROACH AND RESULTS

Treatment with F1, an amino terminus-modified CX3CR1 ligand endowed with CX3CR1 antagonist activity, reduced the extent of atherosclerotic lesions in both Apoe(-/-) and Ldlr(-/-) proatherogenic mouse models. Macrophage accumulation in the aortic sinus was reduced in F1-treated Apoe(-/-) mice but the macrophage density of the lesions was similar in F1-treated and control mice. Both in vitro and in vivo F1 treatment reduced CX3CR1-dependent inflammatory monocyte adhesion, potentially limiting their recruitment. In addition, F1-treated Apoe(-/-) mice displayed reduced numbers of blood inflammatory monocytes, whereas resident monocyte numbers remained unchanged. Both in vitro and in vivo F1 treatment reduced CX3CR1-dependent inflammatory monocyte survival. Finally, F1 treatment of Apoe(-/-) mice with advanced atherosclerosis led to smaller lesions than untreated mice but without reverting to the initial phenotype.

CONCLUSIONS

The CX3CR1 antagonist F1 is a potent inhibitor of the progression of atherosclerotic lesions by means of its selective impact on inflammatory monocyte functions. Controlling monocyte trafficking and survival may be an alternative or complementary therapy to lipid-lowering drugs classically used in the treatment of atherosclerosis.

Shear Stress Enhances Chemokine Secretion from Chlamydia pneumoniae-infected Monocytes

Chlamydia pneumoniae is a common respiratory pathogen that is considered a highly likely risk factor for atherosclerosis. C. pneumoniae is disseminated from the lung into systemic circulation via infected monocytes and lodges at the atherosclerotic sites. During transit, C. pneumoniae-infected monocytes in circulation are subjected to shear stress due to blood flow. The effect of mechanical stimuli on infected monocytes is largely understudied in the context of C. pneumoniae infection and inflammation. We hypothesized that fluid shear stress alters the inflammatory response of C. pneumoniae-infected monocytes and contributes to immune cell recruitment to the site of tissue damage. Using an in vitro model of blood flow, we determined that a physiological shear stress of 7.5 dyn/cm² for 1 h on C. pneumoniae-infected monocytes enhances the production of several chemokines, which in turn is correlated with the recruitment of significantly large number of monocytes. Taken together, these results suggest synergistic interaction between mechanical and chemical factors in C. pneumoniae infection and associated inflammation.

Supra-additive expression of interleukin-6, interleukin-8 and basic fibroblast growth factor in vascular smooth muscle cells following coinfection with Chlamydia pneumoniae and cytomegalovirus as a novel link between infection and atherosclerosis

BACKGROUND

Chlamydia pneumoniae and human cytomegalovirus (HCMV) may be involved in the pathogenesis of atherosclerosis. Prospective studies indicate an increased risk for cardiovascular events in patients with evidence of multiple infections.

OBJECTIVE

To determine whether there is a synergistic effect of coinfection with C pneumoniae and HCMV on expression of selected growth factors and cytokines.

METHODS

The production of interleukin (IL)-6, IL-8, basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), and 'regulated on activation normal T-cell expressed and secreted' (RANTES) was measured in coinfected aortic smooth muscle cells (AoSMC).

RESULTS

Using reverse transcription polymerase chain reaction and immunoassays, it was demonstrated that the expression of IL-6, IL-8, RANTES and bFGF was stimulated in a dose- and time-dependent fashion in C pneumoniae and also in HCMV-infected cultures. In contrast, the expression of PDGF-AA was only stimulated following HCMV infection. Coinfection with C pneumoniae and HCMV resulted in a supra-additive stimulation of IL-6 (30% increased expression, P≤0.05) at 48 h, IL-8 (137% increased expression, P≤0.001) at 24 h and bFGF (209% increased expression, P≤0.01) at 48 h following infection.

CONCLUSIONS

The findings of the present study show that C pneumoniae and HCMV are able to act in synergy in coinfected AoSMC. The supra-additive induction of AoSMC growth factors and cytokines indicates a novel molecular link between infection and vascular disease development.

Role of CC-chemokine receptor 5 on myocardial ischemia-reperfusion injury in rats

The expression level of CC-chemokine receptor 5 (CCR5) is enhanced post inflammatory stimulations and might play a crucial role on inflammatory cells infiltration post myocardial ischemia. The purpose of this study was to evaluate the role of CCR5 on myocardial ischemia-reperfusion (I/R) injury in rats. Adult male rats were randomized to sham group, I/R group (I/R, 30 min coronary artery occlusion followed by 2-h reperfusion), ischemic preconditioning (I/R + Pre), CCR5 antibody group [I/R + CCR5Ab (0.2 mg/kg)], and CCR5 agonist group [I/R + CCR5Ago, RNATES (0.1 mg/kg)], n = 12 each group. The serum level of creatine kinase (CK) and tumor necrosis factor α (TNF-α) were measured by ELISA. Myocardial infarction size and myeloperoxidase (MPO) activity were determined. Myocardial protein expression of CCR5 and intercellular adhesion molecule-1 (ICAM-1) were evaluated by Western blotting and immunohistochemistry staining, respectively. Myocardial nuclear factor-kappa B (NF-κB) activity was assayed by electrophoretic mobility shift assay. Myocardial CCR5 protein expression was significantly reduced in I/R + Pre group (P < 0.05 vs. I/R) and further reduced in I/R + CCR5Ab group (P < 0.05 vs. I/R + Pre). LVSP and ±dP/dt(max) were significantly lower while serum CK and TNF-α as well as myocardial MPO activity, ICAM-1 expression, and NF-κB activity were significantly higher in I/R group than in sham group (all P < 0.05), which were significantly reversed by I/R + Pre (all P < 0.05 vs. I/R) and I/R + CCR5Ab (all P < 0.05 vs. I/R + Pre) while aggravated by I/R + CCR5Ago (all P < 0.05 vs. I/R). Our results suggest that blocking CCR5 attenuates while enhancing CCR5 aggravates myocardial I/R injury through modulating inflammatory responses in rat heart.

Expression and relationship of proinflammatory chemokine RANTES/CCL5 and cytokine IL-1β in painful human intervertebral discs

STUDY DESIGN

Laboratory study.

OBJECTIVE

To evaluate expression of chemokine regulated and normal T cell expressed and secreted (RANTES)/C-C motif ligand 5 (CCL5) and interleukins in intervertebral discs (IVDs) specimens from patients with discogram-proven painful degeneration.

SUMMARY OF BACKGROUND DATA

Discogenic back pain results in tremendous costs related to treatment and lost productivity. The relationship between inflammation, degeneration (IVD), and cytokine upregulation is well established, but other mediators of the inflammatory cascade are not well characterized.

METHODS

Painful IVDs were taken from 18 patients undergoing surgery for discogenic pain with positive preoperative discogram. Painless control tissue was taken at autopsy from patients without back pain/spinal pathology or spinal levels with negative discograms resected for deformity.Quantitative real time polymerase chain reaction (qRT-PCR) was performed to evaluate RANTES, IL-1β, IL-6, and IL-8 expression in painful and control discs. RANTES and interleukin expression were analyzed on the basis of Pfirrmann grade.Disc cells were cultured in alginate beads using 2 groups: an untreated group and a group treated with 10 ng/mL IL-1β, 10 ng/mL TNF-α, and 1% fetal bovine serum to induce a degenerative phenotype.

RESULTS

Nine painless IVD specimens and 7 painful IVD specimens were collected. RANTES expression demonstrated a 3.60-fold increase in painful discs versus painless discs, a significant difference (P = 0.049). IL-1β expression demonstrated significantly higher expression in painful discs (P = 0.03). RANTES expression data demonstrated significant upregulation with increasing Pfirrmann grade (P = 0.045). RANTES expression correlated significantly with IL-1β expression (ρ = 0.67, P < 0.0001). RANTES expression increased more than 200-fold in the alginate culture model in cells treated with IL-1β/TNF-α, 1% fetal bovine serum (P < 0.001).

CONCLUSION

RANTES and IL-1β expression was significantly elevated in painful IVDs after careful selection of painless versus painful IVD tissue. RANTES expression was found to correlate significantly with expression of IL-1β. RANTES was upregulated by IL-1β/TNF-α/1% fetal bovine serum an in vitro treatment to induce a degenerative phenotype.

Efficacy of the CCR5 antagonist maraviroc in reducing early, ritonavir-induced atherogenesis and advanced plaque progression in mice

BACKGROUND

CCR5 plays an important role in atherosclerosis and ischemic cardiovascular diseases, as well as in HIV replication and diffusion. HIV infection is characterized by a high burden of cardiovascular diseases, particularly in subjects exposed to ritonavir-boosted protease inhibitors. Maraviroc, a CCR5 antagonist antiretroviral drug, might provide benefit for patients with M-tropic HIV infections at high risk for cardiovascular diseases.

METHODS AND RESULTS

Exposure to maraviroc limits the evolution and associated systemic inflammation of ritonavir-induced atherosclerotic in ApoE(-/-) mice and inhibits plaques development in a late model of atherosclerosis in which dyslipidemia plays the main pathogenic role. In ritonavir-treated mice, maraviroc reduced plaque areas and macrophage infiltration; downregulated the local expression of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, monocyte chemoattractant protein-1, and interleukin-17A; and reduced tumor necrosis factor-α and RANTES (regulated on activation, normal T cell expressed, and secreted). Moreover, maraviroc counterregulated ritonavir-induced lipoatrophy and interlelukin-6 gene expression in epididymal fat, along with the splenic proinflammatory profile and expression of CD36 on blood monocytes. In the late model, maraviroc inhibited atherosclerotic progression by reducing macrophage infiltration and lowering the expression of adhesion molecules and RANTES inside the plaques. However, limited systemic inflammation was observed.

CONCLUSIONS

In a mouse model of genetic dyslipidemia, maraviroc reduced the atherosclerotic progression by interfering with inflammatory cell recruitment into plaques. Moreover, in mice characterized by a general ritonavir-induced inflammation, maraviroc reversed the proinflammatory profile. Therefore, maraviroc could benefit HIV-positive patients with residual chronic inflammation who are at a high risk of acute coronary disease despite a suppressive antiretroviral therapy. To determine these benefits, large clinical studies are needed.

Distinct functions of chemokine receptor axes in the atherogenic mobilization and recruitment of classical monocytes

We used a novel approach of cytostatically induced leucocyte depletion and subsequent reconstitution with leucocytes deprived of classical (inflammatory/Gr1^hi) or non-classical (resident/Gr1^lo) monocytes to dissect their differential role in atheroprogression under high-fat diet (HFD). Apolipoprotein E-deficient (Apoe^−/−) mice lacking classical but not non-classical monocytes displayed reduced lesion size and macrophage and apoptotic cell content. Conversely, HFD induced a selective expansion of classical monocytes in blood and bone marrow. Increased CXCL1 levels accompanied by higher expression of its receptor CXCR2 on classical monocytes and inhibition of monocytosis by CXCL1-neutralization indicated a preferential role for the CXCL1/CXCR2 axis in mobilizing classical monocytes during hypercholesterolemia. Studies correlating circulating and lesional classical monocytes in gene-deficient Apoe^−/− mice, adoptive transfer of gene-deficient cells and pharmacological modulation during intravital microscopy of the carotid artery revealed a crucial function of CCR1 and CCR5 but not CCR2 or CX₃CR1 in classical monocyte recruitment to atherosclerotic vessels. Collectively, these data establish the impact of classical monocytes on atheroprogression, identify a sequential role of CXCL1 in their mobilization and CCR1/CCR5 in their recruitment.

Leukocyte-specific CCL3 deficiency inhibits atherosclerotic lesion development by affecting neutrophil accumulation

OBJECTIVE

Despite common disbelief that neutrophils are involved in atherosclerosis, evidence is accumulating for a causal role of neutrophils in atherosclerosis. CC chemokine ligand (CCL)3 is an inflammatory chemokine and its expression is significantly increased during atherosclerotic lesion formation in mice. It has recently been shown that under conditions of inflammation neutrophils can migrate along a CCL3 gradient. In this study, we aimed to elucidate the role of leukocyte-derived CCL3 in atherogenesis.

METHODS AND RESULTS

Irradiated low density lipoprotein receptor(-/-) mice, reconstituted with CCL3(-/-) or littermate bone marrow showed markedly reduced CCL3 response to lipopolysaccharide treatment, establishing the critical relevance of leukocytes as source of CCL3. Hematopoietic deficiency of CCL3 significantly reduced aortic sinus lesion formation by 31% after 12 weeks of western-type diet. Interestingly, whereas plaque macrophage, collagen, and vascular smooth muscle cell content were unchanged, neutrophil adhesion to and presence in plaques was significantly attenuated in CCL3(-/-) chimeras. These mice had reduced circulating neutrophil numbers, which could be ascribed to an increased neutrophil turnover and CCL3(-/-) neutrophils were shown to be less responsive toward the neutrophil chemoattractant CXC chemokine ligand 1.

CONCLUSIONS

Our data indicate that under conditions of acute inflammation leukocyte-derived CCL3 can induce neutrophil chemotaxis toward the atherosclerotic plaque, thereby accelerating lesion formation.

CC chemokine receptors and chronic inflammation--therapeutic opportunities and pharmacological challenges

Chemokines are a family of low molecular weight proteins with an essential role in leukocyte trafficking during both homeostasis and inflammation. The CC class of chemokines consists of at least 28 members (CCL1-28) that signal through 10 known chemokine receptors (CCR1-10). CC chemokine receptors are expressed predominantly by T cells and monocyte-macrophages, cell types associated predominantly with chronic inflammation occurring over weeks or years. Chronic inflammatory diseases including rheumatoid arthritis, atherosclerosis, and metabolic syndrome are characterized by continued leukocyte infiltration into the inflammatory site, driven in large part by excessive chemokine production. Over years or decades, persistent inflammation may lead to loss of tissue architecture and function, causing severe disability or, in the case of atherosclerosis, fatal outcomes such as myocardial infarction or stroke. Despite the existence of several clinical strategies for targeting chronic inflammation, these diseases remain significant causes of morbidity and mortality globally, with a concomitant economic impact. Thus, the development of novel therapeutic agents for the treatment of chronic inflammatory disease continues to be a priority. In this review we introduce CC chemokine receptors as critical mediators of chronic inflammatory responses and explore their potential role as pharmacological targets. We discuss functions of individual CC chemokine receptors based on in vitro pharmacological data as well as transgenic animal studies. Focusing on three key forms of chronic inflammation--rheumatoid arthritis, atherosclerosis, and metabolic syndrome--we describe the pathologic function of CC chemokine receptors and their possible relevance as therapeutic targets.

The combination of an oxygen-dependent degradation domain-regulated adenovirus expressing the chemokine RANTES/CCL5 and NK-92 cells exerts enhanced antitumor activity in hepatocellular carcinoma

Oncolytic adenoviruses are modified based on adenovirus serotype 5 (Ad5), which belongs to subgroup C and depends on Coxsackie-adenovirus receptor (CAR) to recognize target cells. However, expression of CAR is generally low or lost in certain tumors including hepatocellular carcinoma (HCC). By contrast, CD46 is highly expressed in various types of malignant tumor cells. Therefore, we constructed an adenovirus vector expressing the human RANTES/CCL5 gene regulated by oxygen-dependent degradation domain (ODD) and analyzed its antitumor effects in vitro and in vivo. The human RANTES/CCL5 gene was fused with ODD by PCR and the recombinant oncolytic adenovirus containing RANTES-ODD, SG511-CCL5-ODD, was constructed by the Gateway system, which infected cells by binding CD46. Viral replication experiments were performed to evaluate the selective replication ability of SG511-CCL5-ODD. RANTES expression was determined by ELISA. The chemotactic test was used to analyze the ability of the expressed RANTES to recruit NK92 cells. The antitumor effects of SG511-CCL5-ODD were examined in HCC xenografts in nude mice. A chimeric oncolytic adenovirus, SG511-CCL5-ODD, was constructed successfully. Cells infected with the recombinant virus were able to express RANTES selectively in different environments controlled by ODD and the expressed RANTES was able to recruit NK92 cells by its chemotactic effect in vitro and improve the anticancer immune response in HCC xenografts in nude mice. The chimeric adenovirus SG511-CCL5-ODD highly expressed the RANTES-ODD fusion gene in the hypoxia of HCC under the control of the ODD and effectively attracted NK92 cells and a high number of immunocytes. These factors had complementary advantages and, in combination, exerted enhanced antitumor efficacy.

Regulation of atherogenesis by chemokines and chemokine receptors

Atherosclerosis is a chronic inflammatory and metabolic disorder affecting large- and medium-sized arteries, and the leading cause of mortality worldwide. The pathogenesis of atherosclerosis involves accumulation of lipids and leukocytes in the intima of blood vessel walls creating plaque. How leukocytes accumulate in plaque remains poorly understood; however, chemokines acting at specific G protein-coupled receptors appear to be important. Studies using knockout mice suggest that chemokine receptor signaling may either promote or inhibit atherogenesis, depending on the receptor. These proof of concept studies have spurred efforts to develop drugs targeting the chemokine system in atherosclerosis, and several have shown beneficial effects in animal models. This study will review key discoveries in basic and translational research in this area.

Platelets: key players in vascular inflammation

Review on platelet function in inflammation and atherosclerosis.

Platelets play a crucial role in the physiology of the primary hemostasis and in the pathophysiological activity of arterial thrombosis, provide rapid protection against bleeding, and catalyze the formation of stable blood clots via the coagulation cascade. Over the past years, it has become clear that platelets are important, not only in hemostasis and thrombosis but also in inflammation and in distinct aspects of atherosclerosis. Nowadays, platelets are known to have a large variety of functions. Platelets are able to interact with a large variety of cell types, such as leukocytes, endothelial cells, and SMCs, and these interactions have been implicated in the pathophysiology of vascular inflammation. In addition, platelets carry a highly inflammatory payload and are able to transport, synthesize, and deposit cytokines, chemokines, and lipid mediators, thereby initiating and propagating atherosclerotic disease. In this review, the current state of the art of the proinflammatory functions in the context of atherosclerotic cardiovascular disease will be outlined.

Therapeutic strategies to deplete macrophages in atherosclerotic plaques

Macrophages can be found in all stages of atherosclerosis and are major contributors of atherosclerotic plaque development, progression and destabilization. Continuous recruitment of monocytes drives this chronic inflammatory disease, which can be intervened by several strategies: reducing the inflammatory stimulus by lowering circulating lipids and promoting cholesterol efflux from plaque, direct and indirect targeting of adhesion molecules and chemokines involved in monocyte adhesion and transmigration and inducing macrophage death in atherosclerotic plaques in combination with anti-inflammatory drugs. This review discusses the outlined strategies to deplete macrophages from atherosclerotic plaques to promote plaque stabilization.

Role of maraviroc in a dyslipidemic murine model of atherosclerosis RTV-induced

Purpose

Chemokines and their receptors play a crucial role in the development of atherosclerosis. CCR5 is considered to be crucial to monocyte recruitment during development of atherosclerosis. CCR5, known as a co-receptor of HIV-1, is the target of the approved CCR5 antagonist maraviroc (MVC). Therefore we investigated whether MVC reduces inflammation and atherosclerosis in a rodent model of dyslipidemia (ApoE-/-mice) treated or not with Ritonavir (RTV).

Methods

Two-month-old mice (8 per group): wild type, ApoE-/- plus vehicle; ApoE-/- plus RTV; ApoE-/- plus RTV in combination with MVC. Nine-month-old mice (13 per group): wild type; Apo E-/- + vehicle; and Apo E-/- + MVC. Animals were sacrificed after 3 months treatments and plasma, aortas and epididymal fat were collected. Areas of aortas plaque were measured. Immunohistochemistry was performed to evaluate macrophages infiltration, and protein levels of cytokines/chemokines (i.e. ICAM, PAI, VCAM, IL-10, IL-17, MCP1, Rantes, TNFα, INFγ) were evaluated in aorta lysates.

Summary of results

RTV enhances the plaque areas percentage in two month old ApoE-/- mice and is significantly reduced by MVC. The ritonavir-enhanced Mac3 expression on plaques is also reduced by MVC. Treatment with MVC lowers aortic concentration of cytokines/chemokines and plasmatic level of CRP that are increased by RTV. Ritonavir, enhancing mRNA expression of IL-6, Rantes and Mip1α, induces lipoatrophy in epididymal fat; MVC revertes this lipoatrophy and reduces mRNA levels of these cytokines-chemokines. Moreover, in ApoE-/- mice 9 months old, MVC significantly reduces the percentage of plaque areas (from 16.6±3.35% to 7.13±1.44%) (en-face coloration), lowers aortic MAC3 staining and reduces the aortic concentration of cytokines/chemokines.

Conclusions

In a dyslipidemic rodent model the CCR5 inhibitor Maraviroc significantly reduces the percentage of aortic plaque areas, aortic inflammation and lipoatrophy of the epididymal fat. Therefore, the current use of CCR5 antagonists to treat HIV infection, a condition associated with an increased occurrence of cardiovascular disease, should also be exploited to determine any beneficial cardiovascular effects [1,2].

Adipocyte-released insulin-like growth factor-1 is regulated by glucose and fatty acids and controls breast cancer cell growth in vitro

AIMS/HYPOTHESIS

Type 2 diabetes and obesity are associated with increased risk of site-specific cancers. We have investigated whether metabolic alterations at the level of adipose-derived differentiating cells may affect specific phenotypes of breast cancer cells.

METHODS

Growth profiles of breast cancer cell lines were evaluated in co-cultures with differentiated adipocytes or their precursor cells and upon treatment with adipocyte conditioned media. Production and release of cytokines and growth factors were assessed by real-time RT-PCR and multiplex-based ELISA assays.

RESULTS

Co-cultures with either differentiated mouse 3T3-L1 or human mammary adipocytes increased viability of MCF-7 cells to a greater extent, when compared with their undifferentiated precursors. Adipocytes cultured in 25 mmol/l glucose were twofold more effective in promoting cell growth, compared with those grown in 5.5 mmol/l glucose, and activated mitogenic pathways in MCF-7 cells. Growth-promoting action was also enhanced when adipocytes were incubated in the presence of palmitate or oleate. Interestingly, 3T3-L1 and human adipocytes released higher amounts of keratinocyte-derived chemokine/IL-8, the protein 'regulated upon activation, normally T expressed, and secreted' (RANTES), and IGF-1, compared with their precursor cells. Their levels were reduced upon incubation with low glucose and enhanced by fatty acids. Moreover, both undifferentiated cells and differentiated adipocytes from obese individuals displayed about twofold higher IGF-1 release and MCF-7 cell growth induction than lean individuals. Finally, inhibition of the IGF-1 pathway almost completely prevented the growth-promoting effect of adipocytes on breast cancer cells.

CONCLUSIONS/INTERPRETATION

IGF-1 release by adipocytes is regulated by glucose and fatty acids and may contribute to the control of cancer cell growth in obese individuals.

Hydrogen sulfide inhibits the development of atherosclerosis with suppressing CX3CR1 and CX3CL1 expression

Hydrogen sulfide, as a novel gaseous mediator, has been suggested to play a key role in atherogenesis. However, the precise mechanisms by which H(2)S affects atherosclerosis remain unclear. Therefore, the present study aimed to investigate the potential role of H(2)S in atherosclerosis and the underlying mechanism with respect to chemokines (CCL2, CCL5 and CX3CL1) and chemokine receptors (CCR2, CCR5, and CX3CR1) in macrophages. Mouse macrophage cell line RAW 264.7 or mouse peritoneal macrophages were pre-incubated with saline or NaHS (50 µM, 100 µM, 200 µM), an H(2)S donor, and then stimulated with interferon-γ (IFN-γ) or lipopolysaccharide (LPS). It was found that NaHS dose-dependently inhibited IFN-γ or LPS-induced CX3CR1 and CX3CL1 expression, as well as CX3CR1-mediated chemotaxis in macrophages. Overexpression of cystathionine γ-lyase (CSE), an enzyme that catalyzes H(2)S biosynthesis resulted in a significant reduction in CX3CR1 and CX3CL1 expression as well as CX3CR1-mediated chemotaxis in stimulated macrophages. The inhibitory effect of H(2)S on CX3CR1 and CX3CL1 expression was mediated by modulation of proliferators-activated receptor-γ (PPAR-γ) and NF-κB pathway. Furthermore, male apoE(-/-) mice were fed a high-fat diet and then randomly given NaHS (1 mg/kg, i.p., daily) or DL-propargylglycine (PAG, 10 mg/kg, i.p., daily). NaHS significantly inhibited aortic CX3CR1 and CX3CL1 expression and impeded aortic plaque development. NaHS had a better anti-atherogenic benefit when it was applied at the early stage of atherosclerosis. However, inhibition of H(2)S formation by PAG increased aortic CX3CR1 and CX3CL1 expression and exacerbated the extent of atherosclerosis. In addition, H(2)S had minimal effect on the expression of CCL2, CCL5, CCR2 and CCR5 in vitro and in vivo. In conclusion, these data indicate that H(2)S hampers the progression of atherosclerosis in fat-fed apoE(-/-) mice and downregulates CX3CR1 and CX3CL1 expression on macrophages and in lesion plaques.

Touch of chemokines

Chemoattractant cytokines or chemokines constitute a family of structurally related proteins found in vertebrates, bacteria, or viruses. So far, 48 chemokine genes have been identified in humans, which bind to around 20 chemokine receptors. These receptors belong to the seven transmembrane G-protein-coupled receptor family. Chemokines and their receptors were originally studied for their role in cellular trafficking of leukocytes during inflammation and immune surveillance. It is now known that they exert different functions under physiological conditions such as homeostasis, development, tissue repair, and angiogenesis but also under pathological disorders including tumorigenesis, cancer metastasis, inflammatory, and autoimmune diseases. Physicochemical properties of chemokines and chemokine receptors confer the ability to homo- and hetero-oligomerize. Many efforts are currently performed in establishing new therapeutically compounds able to target the chemokine/chemokine receptor system. In this review, we are interested in the role of chemokines in inflammatory disease and leukocyte trafficking with a focus on vascular inflammatory diseases, the operating synergism, and the emerging therapeutic approaches of chemokines.

RANTES/CCL5-induced pro-angiogenic effects depend on CCR1, CCR5 and glycosaminoglycans

Atherosclerosis involves angiogenesis and inflammation with the ability of endothelial cells and monocytes to respond to chemokines. We addressed here by in vitro and in vivo approaches, the role of the chemokine Regulated on Activation, Normal T Cell Expressed and Secreted (RANTES)/CCL5 on angiogenesis through its receptors CCR1, CCR5, syndecan-1 (SDC-1), syndecan-4 (SDC-4) and CD-44. Our data demonstrate that RANTES/CCL5 is pro-angiogenic in a rat subcutaneous model. This RANTES/CCL5-activity may be related to the in vitro promotion of endothelial cell migration, spreading and neo-vessel formation. RANTES/CCL5-mediated angiogenesis depends at least partly on Vascular Endothelial Growth Factor (VEGF) secretion by endothelial cells, since this effect is decreased when endothelial cells are incubated with anti-VEGF receptor antibodies. RANTES/CCL5-induced chemotaxis is mediated by matrix metalloproteinase-9. We demonstrate that specific receptors of RANTES/CCL5 such as G protein-coupled receptors CCR1 and CCR5, and heparan sulfate proteoglycans, SDC-1, SDC-4 or CD-44, play a major role in RANTES/CCL5-induced angiogenic effects. By the use of two RANTES/CCL5 mutants, [E66A]-RANTES/CCL5 with impaired ability to oligomerize, and [44AANA47]-RANTES/CCL5 mutated in the main RANTES/CCL5-glycosaminoglycan (GAG) binding site, we demonstrate that chemokine oligomerization and binding to GAGs are essential in RANTES/CCL5-induced angiogenic effects. According to these results, new therapeutic strategies based on RANTES/CCL5 can be proposed for neo-angiogenesis after vascular injury. Mutants of RANTES/CCL5 may also represent an innovative approach to prevent the angiogenesis associated with the formation of atherosclerotic plaque.

Ginkgolide B reduces atherogenesis and vascular inflammation in ApoE(-/-) mice

Aims

To investigate whether ginkgolide B (a platelet-activating factor inhibitor) affects vascular inflammation in atherosclerosis-prone apolipoprotein E-deficient (ApoE^−/−) mice.

Methods and Results

Human platelets were used to evaluate the effects of ginkgolide B on platelet aggregation and signal transduction. Ginkgolide B attenuated platelet aggregation and inhibited phosphatidylinositol 3 kinase (PI3K) activation and Akt phosphorylation in thrombin- and collagen-activated platelets. ApoE^−/− mice were administered a high-cholesterol diet for 8 weeks. Plasma platelet factor 4 (PF4) and RANTES (regulated upon activation, normal T-cell expressed, and secreted protein) were then measured using an enzyme-linked immunosorbent assay. Scanning electron microscopy and immunohistochemistry were used to determine atherosclerotic lesions. Ginkgolide B decreased plasma PF4 and RANTES levels in ApoE^−/− mice. Scanning electron microscopic examination showed that ginkgolide B reduced aortic plaque in ApoE^−/− mice. Immunohistochemistry analysis demonstrated that ginkgolide B diminished P-selectin, PF4, RANTES, and CD40L expression in aortic plaque in ApoE^−/− mice. Moreover, ginkgolide B suppressed macrophage and vascular cell adhesion protein 1 (VCAM-1) expression in aorta lesions in ApoE^−/− mice. Similar effects were observed in aspirin-treated ApoE^−/− mice.

Conclusion

Ginkgolide B significantly reduced atherosclerotic lesions and P-selectin, PF4, RANTES, and CD40L expression in aortic plaque in ApoE−/− mice. The efficacy of ginkgolide B was similar to aspirin. These results provide direct evidence that ginkgolide B inhibits atherosclerosis, which may be associated with inhibition of the PI3K/Akt pathway in activated platelets.

CCR5Δ32 genotype leads to a Th2 type directed immune response in ESRD patients

Background

In patients with end stage renal disease (ESRD) we observed protection from inflammation-associated mortality in CCR5Δ32 carriers, leading to CCR5 deficiency, suggesting impact of CCR5Δ32 on inflammatory processes. Animal studies have shown that CCR5 deficiency is associated with a more pronounced Th2 type immune response, suggesting that in human CCR5Δ32 carriers the immune response may be more Th2 type directed. So, in the present study we determined the Th1-Th2 type directed immune response in ESRD patients carrying and not carrying the CCR5Δ32 genetic variant after stimulation.

Methodology/Principal Findings

We tested this hypothesis by determining the levels of IFN-γ and IL-4 and the distribution of Th1, Th2 and Th17 directed circulating CD4+ and CD8+ T cells and regulatory T cells (Tregs) after stimulation in ESRD patients with (n = 10) and without (n = 9) the CCR5Δ32 genotype. The extracellular levels of IFN-γ and IL-4 did not differ between CCR5Δ32 carriers and non carriers. However, based on their intracellular cytokine profile the percentages IL-4 secreting CD4+ and CD8+ T cells carrying the CCR5Δ32 genotype were significantly increased (p = 0.02, respectively p = 0.02) compared to non carriers, indicating a more Th2 type directed response. Based on their intracellular cytokine profile the percentages IFN-γ and IL-17 secreting T cells did not differ between carriers and non-carriers nor did the percentage Tregs, indicating that the Th1, Th17 and T regulatory response was not affected by the CCR5Δ32 genotype.

Conclusions/Significance

This first, functional human study shows a more pronounced Th2 type immune response in CCR5Δ32 carriers compared to non carriers. These differences may be involved in the previously observed protection from inflammation-associated mortality in ESRD patients carrying CCR5Δ32.