Leukocyte-endothelium adhesion molecules in atherosclerosis

Revisiting the structural basis for biological activity of GMI-1070, a sialyl Lewisx mimetic

When it comes to the treatment of pathologies in which aberrant cell adhesion and extravasation from the bloodstream have been implicated, the selectins represent a central therapeutic target. In this context, the present work investigates the conformational landscape of two prototypes for the design of new antineoplasic and anti-inflammatory agents: the natural selectin ligand sialyl Lewis^x and its mimetic GMI-1070. Accordingly, a series of unbiased molecular dynamics simulations at the microsecond scale using GROMOS 53A6 (GLYC), CHARMM36m and GLYCAM06 force fields were employed, together with ConfID, an analytical method for the characterization of conformational populations of small molecules. Our results for sialyl Lewis^x are in agreement with and expand upon prior work. As for the mimetic, our results indicate that, in spite of its conformational restriction, GMI-1070's behavior in solution deviates from what had been proposed, highlighting thus some features that could be optimized, as the development of sialyl Lewis^x mimetics continues, and new candidates emerge.

The Effects of Sirolimus and Magnesium on Primary Human Coronary Endothelial Cells: An In Vitro Study

Drug eluting magnesium (Mg) bioresorbable scaffolds represent a novel paradigm in percutaneous coronary intervention because Mg-based alloys are biocompatible, have adequate mechanical properties and can be resorbed without adverse events. Importantly, Mg is fundamental in many biological processes, mitigates the inflammatory response and is beneficial for the endothelium. Sirolimus is widely used as an antiproliferative agent in drug eluting stents to inhibit the proliferation of smooth muscle cells, thus reducing the occurrence of stent restenosis. Little is known about the potential interplay between sirolimus and Mg in cultured human coronary artery endothelial cells (hCAEC). Therefore, the cells were treated with sirolimus in the presence of different concentrations of extracellular Mg. Cell viability, migration, barrier function, adhesivity and nitric oxide synthesis were assessed. Sirolimus impairs the viability of subconfluent, but not of confluent cells independently from the concentration of Mg in the culture medium. In confluent cells, sirolimus inhibits migration, while it cooperates with Mg in exerting an anti-inflammatory action that might have a role in preventing restenosis and thrombosis.

Molecular Imaging of Vulnerable Atherosclerotic Plaques in Animal Models

Atherosclerosis is characterized by intimal plaques of the arterial vessels that develop slowly and, in some cases, may undergo spontaneous rupture with subsequent heart attack or stroke. Currently, noninvasive diagnostic tools are inadequate to screen atherosclerotic lesions at high risk of acute complications. Therefore, the attention of the scientific community has been focused on the use of molecular imaging for identifying vulnerable plaques. Genetically engineered murine models such as ApoE^−/− and ApoE^−/−Fbn1C1039G^+/− mice have been shown to be useful for testing new probes targeting biomarkers of relevant molecular processes for the characterization of vulnerable plaques, such as vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2, intercellular adhesion molecule (ICAM)-1, P-selectin, and integrins, and for the potential development of translational tools to identify high-risk patients who could benefit from early therapeutic interventions. This review summarizes the main animal models of vulnerable plaques, with an emphasis on genetically altered mice, and the state-of-the-art preclinical molecular imaging strategies.

Expression of leukocyte adhesion-related glycosyltransferase genes in acute coronary syndrome patients

INTRODUCTION

Acute coronary syndrome (ACS) is caused by destabilization and rupture of atherosclerotic plaque in the coronary artery via mechanisms affecting leukocyte signaling, rolling, adhesion, extravasation and inflammation-promoting factors. The majority of cellular communication takes place on the membrane surface that is covered with glycoproteins and glycolipids synthesized by glycosyltransferases. The aim of this study was to determine the mRNA expression of leukocyte adhesion-related glycosyltransferases in patients during the onset and the chronic phase of ACS and to compare the expression with matching subjects without coronary disease.

SUBJECTS AND METHODS

The study included 26 ACS patients and 26 ACS-free matched-pair controls. Blood samples were collected at the time of hospital admittance and 8 days later. Expression analysis of six fucosyltransferases and six sialyltransferases was performed by a real-time polymerase chain reaction.

RESULTS

At the time of admittance ACS subjects had lower expression levels of FUT4, ST6GalNac4, ST6Gal1 and GM3 synthase (p < 0.05) than the control subjects, and moreover, after 8 days down-regulation of FUT7 and ST6GalNac3 was also observed (p < 0.05). When compared to the initial gene expression, after treatment and stabilization of ACS subjects, FUT7, ST6GalNac2 and ST6GalNac3 were down-regulated, whereas ST6GalNac1 was up-regulated. Expression levels of FUT7, ST6GalNac1, ST6GalNac2 and ST6GalNac3 were predicted by several drugs and medical history.

CONCLUSION

Expression of glycosyltransferase genes differs in ACS and control subjects. During the course of the ACS study we established further changes in gene expression levels. Medical history was predictive of gene expression levels while drugs were shown to modulate expression levels.

The immune system in stroke: clinical challenges and their translation to experimental research

Stroke represents an unresolved challenge for both developed and developing countries and has a huge socio-economic impact. Although considerable effort has been made to limit stroke incidence and improve outcome, strategies aimed at protecting injured neurons in the brain have all failed. This failure is likely to be due to both the incompleteness of modelling the disease and its causes in experimental research, and also the lack of understanding of how systemic mechanisms lead to an acute cerebrovascular event or contribute to outcome. Inflammation has been implicated in all forms of brain injury and it is now clear that immune mechanisms profoundly influence (and are responsible for the development of) risk and causation of stroke, and the outcome following the onset of cerebral ischemia. Until very recently, systemic inflammatory mechanisms, with respect to common comorbidities in stroke, have largely been ignored in experimental studies. The main aim is therefore to understand interactions between the immune system and brain injury in order to develop novel therapeutic approaches. Recent data from clinical and experimental research clearly show that systemic inflammatory diseases -such as atherosclerosis, obesity, diabetes or infection - similar to stress and advanced age, are associated with dysregulated immune responses which can profoundly contribute to cerebrovascular inflammation and injury in the central nervous system. In this review, we summarize recent advances in the field of inflammation and stroke, focusing on the challenges of translation between pre-clinical and clinical studies, and potential anti-inflammatory/immunomodulatory therapeutic approaches.

Effects of the pan-selectin antagonist bimosiamose (TBC1269) in experimental human endotoxemia

Selectins mediate the adhesion of leukocytes to activated endothelial cells and activated platelets. In addition to these cell-to-cell interactions, they influence the fibrin content and size of venous thrombi in different animal models. However, the exact role of selectins in human endotoxemia still remains unclear. We aimed to investigate the effect of selectin inhibition in lipopolysaccharide (LPS)-induced tissue factor (TF)-dependent activation of coagulation in a well-standardized model of human endotoxemia. To explore whether selectin blockade attenuates LPS-induced coagulation in humans, we performed a randomized, double-bind placebo-controlled crossover trial in 16 healthy male volunteers. All subjects received 2 ng/kg of LPS and, 10 min thereafter, a 15-min infusion of either 30 mg/kg of the pan-selectin antagonist bimosiamose or equal volumes of placebo in random order, with a washout period of 6 weeks between both periods. Treatment with bimosiamose had no significant effect on LPS-induced TF expression, as quantified by TF mRNA levels, or on LPS-induced coagulation response, reflected by increases in plasma thrombin-antithrombin (TAT) complexes and prothrombin fragment (F1 + 2) levels. Furthermore, bimosiamose did not affect the LPS-dependent changes in leukocyte subpopulations or the increase in platelet-leukocyte aggregates, as determined in the level of CD41+ monocytes. Finally, neither the LPS-induced release of tumor necrosis factor, interleukin 6, leukocyte expression of CD11b, nor intercellular adhesion molecule 1 were affected by administration of bimosiamose. The pan-selectin antagonist bimosiamose does not attenuate TF-triggered coagulation or inflammation in human endotoxemia. This indicates a minor influence of this selectin antagonist in this model. In addition, infusion of bimosiamose was safe and well tolerated in human endotoxemia.

Polymeric particles conjugated with a ligand to VCAM-1 exhibit selective, avid, and focal adhesion to sites of atherosclerosis

The increased expression of VCAM-1 on endothelial segments within plaque regions could be used as a target to deliver polymeric drug carriers selectively to sites of atherosclerosis. We probed the hypothesis that polymeric particles conjugated with a ligand for VCAM-1 exhibit selective and avid adhesion to sites of atherosclerosis. Particles made from polystyrene or the biodegradable polymer poly(sebacic acid)-block-polyethylene glycol (PSA-PEG) were conjugated with an antibody to VCAM-1 (alpha-VCAM-1) or IgG (negative control). The particles were injected into the jugular vein of ApoE(-/-) (a murine model of atherosclerosis) or wild type mice and their adhesion to the aorta determined. alpha-VCAM-1 particles exhibited significantly greater adhesion to ApoE(-/-) mouse aorta [32 +/- 5 (mean +/- SEM) particles/mm(2) for polystyrene particles and 31 +/- 7 particles/mm(2) for PSA-PEG particles] compared to the level of adhesion to wild type mouse aorta (18 +/- 1 particles/mm(2) for polystyrene particles and 6 +/- 1 particles/mm(2) for PSA-PEG particles). Within ApoE(-/-) mice, the alpha-VCAM-1 particles exhibited significantly greater adhesion to the aorta (32 +/- 5 particles/mm(2) for polystyrene particles and 31 +/- 7 particles/mm(2) for PSA-PEG particles) compared to the adhesion of IgG particles (1 +/- 1 particles/mm(2) for polystyrene particles and 2 +/- 1 particles/mm(2) for PSA-PEG particles). Detailed analysis of the adhesion revealed that alpha-VCAM-1 particles exhibited focal adhesion to plaque regions, in particular the periphery of the plaques, within the ApoE(-/-) mouse aorta. Combined the data demonstrate that polymeric particles conjugated with a ligand to VCAM-1 exhibit selective, avid and focal adhesion to sites of atherosclerosis providing strong evidence that VCAM-1 ligand bearing polymeric particles could be used for targeting drugs selectively to atherosclerotic tissue.

Monocyte functional responsiveness after PSGL-1-mediated platelet adhesion is dependent on platelet activation status

OBJECTIVE

Acute coronary diseases are characterized by elevated levels of circulating platelet-leukocyte complexes, raising the possibility that proinflammatory processes might be initiated in leukocytes after platelet adhesion. Here we examined the mechanism of platelet binding to polymorphonuclear leukocytes, monocytes, and monocyte subsets and investigated the potential functional consequences of monocyte binding to minimally activated or thrombin-activated platelets.

METHODS AND RESULTS

In this article, we describe key differences in terms of stability of PSGL-1-mediated interaction of platelets with monocytes and polymorphonuclear leukocytes and a small but significant difference in platelet binding to monocyte subsets (CD14(high) and CD14(low)/HLA-DR(high)). We also report differential effects of platelet binding on monocyte functional responses between minimally and thrombin-activated platelets. In particular, monocyte CD11b expression and release of proinflammatory cytokines, like interleukin 1beta and tumor necrosis factor alpha, were significantly upregulated on adhesion of stimulated platelets, whereas unstimulated platelets had no effect. Moreover, binding of unstimulated, but not of thrombin-activated, platelets to monocytes had no impact on NF-kappaB activity, monocyte migration, and induction of apoptosis in the absence of survival factors.

CONCLUSIONS

Our data suggest that in the absence of overt activation, PSGL-1-P-selectin-dependent platelet binding to monocytes represents a normal physiological process with little impact on the potential of monocytes to cause vascular injury.

Selenium inhibits 15-hydroperoxyoctadecadienoic acid-induced intracellular adhesion molecule expression in aortic endothelial cells

Increased intracellular adhesion molecule 1 (ICAM-1) expression and enhanced monocyte recruitment to the endothelium are critical steps in the early development of atherosclerosis. The 15-lipoxygenase 1 (15-LOX1) pathway can generate several proinflammatory eicosanoids that are known to enhance ICAM-1 expression within the vascular endothelium. Oxidative stress can exacerbate endothelial cell inflammatory responses by modifying arachidonic acid metabolism through the 15-LOX1 pathway. Because selenium (Se) influences the oxidant status of cells and can modify the expression of eicosanoids, we investigated the role of this micronutrient in modifying ICAM-1 expression as a consequence of enhanced 15-LOX1 activity. Se supplementation reduced ICAM-1 expression in bovine aortic endothelial cells, an effect that was reversed with 15-LOX1 overexpression or treatment with exogenous 15-hydroperoxyoctadecadienoic acid (15-HPETE). ICAM-1 expression increased proportionately when intracellular15-HPETE levels were allowed to accumulate. However, changes in intracellular 15-HETE levels did not seem to affect ICAM-1 expression regardless of Se status. Our results indicate that Se supplementation can reduce 15-HPETE-induced expression of ICAM-1 by controlling the intracellular accumulation of this fatty acid hydroperoxide in endothelial cells.

Vascular adhesion molecules in atherosclerosis

Numerous reports document the role of vascular adhesion molecules in the development and progression of atherosclerosis. Recent novel findings in the field of adhesion molecules require an updated summary of current research. In this review, we highlight the role of vascular adhesion molecules including selectins, vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule1 (ICAM-1), PECAM-1, JAMs, and connexins in atherosclerosis. The immune system is important in atherosclerosis, and significant efforts are under way to understand the vascular adhesion molecule-dependent mechanisms of immune cell trafficking into healthy and atherosclerosis-prone arterial walls. This review focuses on the role of vascular adhesion molecules in the regulation of immune cell homing during atherosclerosis and discusses future directions that will lead to better understanding of this disease.

Changes in inflammatory biomarkers following one-year of moderate resistance training in overweight women

BACKGROUND

Overweight individuals commonly demonstrate elevated levels of inflammatory and cell adhesion molecules. Elevated levels of inflammation and adhesion have been implicated in the pathogenesis of cardiovascular disease. Aerobic exercise has been shown to be effective in altering specific biomarkers of inflammation and cell adhesion; however, little is known regarding the effects of resistance training (RT) on these biomarkers. This study examined the effects of 1 year of moderate-intensity RT on biomarkers of inflammation and adhesion in healthy, overweight women.

METHODS AND RESULTS

Participants included 28 (12 control, 16 RT) overweight (body mass index>or=25 kg/m2) women, aged 25-44 years, studied before and after 1 year of RT. C-reactive protein (CRP), interleukin-6 (IL-6), adiponectin, intracellular adhesion molecule-1, vascular cell adhesion molecule-1 and E-selectin were measured by standard enzyme-linked immunosorbent assays. Body composition, blood pressure, fasting blood lipids, glucose and insulin also were assessed. There were no significant changes in blood pressure, fasting blood lipids, glucose or insulin levels in either group after 1 year. There was also no change in body mass or fat mass in either group; however, there was a significant increase in lean body mass (P<0.05) in the RT group. Both CRP (P<0.01) and adiponectin (P<0.01) demonstrated significant improvements in the RT group, with no change in IL-6. Conversely, there were no associated changes in the biomarkers of cell adhesion in either group.

CONCLUSIONS

This study demonstrates that moderate-intensity RT significantly results in modest improvements of inflammatory markers without affecting cell adhesion molecules in overweight women.

CD44 regulates vascular gene expression in a proatherogenic environment

OBJECTIVE

To identify early changes in vascular gene expression mediated by CD44 that promote atherosclerotic disease in apolipoprotein E (apoE)-deficient (apoE-/-) mice.

METHODS AND RESULTS

We demonstrate that CD44 is upregulated and functionally activated in aortic arch in the atherogenic environment of apoE-/- mice relative to wild-type (C57BL/6) controls. Moreover, CD44 activation even in apoE-/- mice is selective to lesion-prone regions because neither the thoracic aorta from apoE-/- mice nor the aortic arch of C57BL/6 mice exhibited upregulation of CD44 compared with thoracic aorta of CD57BL/6 mice. Consistent with these observations, gene expression profiling using cDNA microarrays and quantitative polymerase chain reaction revealed that approximately 155 of 19,200 genes analyzed were differentially regulated in the aortic arch, but not in the thoracic aorta, in apoE-/- CD44-/- mice compared with apoE-/- CD44+/+ mice. However, these genes were not regulated by CD44 in the context of a C57BL/6 background, illustrating the selective impact of CD44 on gene expression in a proatherogenic environment. The patterns of differential gene expression implicate CD44 in focal adhesion formation, extracellular matrix deposition, and angiogenesis, processes critical to atherosclerosis.

CONCLUSIONS

CD44 is an early mediator of atherogenesis by virtue of its ability to regulate vascular gene expression in response to a proatherogenic environment.

The A2B adenosine receptor protects against inflammation and excessive vascular adhesion

Adenosine has been described as playing a role in the control of inflammation, but it has not been certain which of its receptors mediate this effect. Here, we generated an A2B adenosine receptor-knockout/reporter gene-knock-in (A2BAR-knockout/reporter gene-knock-in) mouse model and showed receptor gene expression in the vasculature and macrophages, the ablation of which causes low-grade inflammation compared with age-, sex-, and strain-matched control mice. Augmentation of proinflammatory cytokines, such as TNF-alpha, and a consequent downregulation of IkappaB-alpha are the underlying mechanisms for an observed upregulation of adhesion molecules in the vasculature of these A2BAR-null mice. Intriguingly, leukocyte adhesion to the vasculature is significantly increased in the A2BAR-knockout mice. Exposure to an endotoxin results in augmented proinflammatory cytokine levels in A2BAR-null mice compared with control mice. Bone marrow transplantations indicated that bone marrow (and to a lesser extent vascular) A2BARs regulate these processes. Hence, we identify the A2BAR as a new critical regulator of inflammation and vascular adhesion primarily via signals from hematopoietic cells to the vasculature, focusing attention on the receptor as a therapeutic target.

Circulating markers of endothelial function in cardiovascular disease

Endothelial dysfunction is a key event in cardiovascular disease. Measurement of endothelial dysfunction in vivo presents a major challenge, but has important implications since it may identify the clinical need for therapeutic intervention, specifically in primary prevention. Several biological markers have been used as indicators of endothelial dysfunction. The soluble adhesion molecules sICAM-1 and sVCAM-1 lack specificity and are increased in inflammatory processes. Both markers are increased in coronary artery disease. sICAM-1 level predicts the risk for cardiovascular disease or diabetes mellitus in healthy individuals. sE-selectin is specific for the endothelium and is increased in coronary artery disease and diabetes mellitus. sE-selectin is also associated with diabetic risk. The endothelium-specific marker, soluble thrombomodulin, is associated with severity of coronary artery disease, stroke or peripheral occlusive arterial disease and is not increased in healthy or asymptomatic subjects. Interestingly, thrombomodulin decreases during treatment of hypercholesterolemia or hyperhomocysteinemia. In contrast, von Willebrand factor is the best endothelial biomarker and predicts risk for ischemic heart disease or stroke.

Immunoglobulin treatment reduces atherosclerosis in apolipoprotein E-/- low-density lipoprotein receptor-/- mice via the complement system

Atherosclerosis is associated with activation of the immune system. Intravenously applied normal polyclonal immunoglobulins (IVIg) have broad therapeutic applications in the treatment of autoimmune and systemic inflammatory diseases. Recently, IVIg have been shown to inhibit atherogenesis in experimental animal models. To investigate the role of the complement system in this process, we used third complement component-deficient (C3(-/-)) and control atherosclerosis-prone apolipoprotein E (ApoE) and low-density lipoprotein receptor (LDLR) double knock-out mice fed a normal diet. IVIg treatment reduced lesion fraction area in the aortic root of complement-sufficient mice whereas the lesion fraction area of C3(-/-) mice was not affected. Thus, complement activation plays a role in the anti-atherosclerotic effects of IVIg, possibly by C3-derived fragments generated through Fc-dependent complement activation.

Age and sex modulate metabolic and cardiovascular risk markers of patients after 1 year of highly active antiretroviral therapy (HAART)

OBJECTIVE

Primary aim: To evaluate the modulating effects of age and sex on changes in plasma lipid levels in the response to highly active antiretroviral therapy (HAART). Secondary aim: To study insulin, leptin, adiponectin, E-selectin and P-selectin levels and their relation to demographics.

DESIGN

Comparative, longitudinal, open cohort-study.

SETTING

Tertiary care center at a University Hospital.

METHODS

Eighty-two consecutive HIV-seropositive patients of either sex were enrolled in the study. Subjects were between 19 and 60 years of age and naive to HAART. Patients were treated with nucleoside reverse transcriptase inhibitors (NRTIs) and protease inhibitor(s) (PIs) or reverse transcriptase inhibitors (RTIs) only. Subjects were evaluated at baseline and after 3, 6 and 12 months.

RESULTS

Total cholesterol levels increased in all patients. The greatest increase was seen in patients of older age treated with PI. Male gender was another risk factor for higher cholesterol but also for higher triglyceride levels. Therapy with protease inhibitors and/or stavudine had a negative influence on plasma triglyceride levels. Selectins, adipokines and insulin were less influenced by HAART.

CONCLUSION

Based on the results of this study selection of therapy regimen according to the demographic risk factors sex and age can offer an easy strategy to help to minimize lipid elevations.

The inhibitory effect of alacepril, an angiotensin-converting enzyme inhibitor, on endothelial inflammatory response induced by oxysterol and TNF-alpha

The objectives were to determine the effects of alacepril, an angiotensin-converting enzyme inhibitor, on the expression of adhesion molecules and monocyte adherence to endothelial cells induced by 7-ketocholesterol (7-KC) and tumor necrosis factor (TNF)-alpha. We used human aortic endothelial cells (HAECs) and U937 monocytic cells. Surface expression and mRNA levels of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were determined by EIA and RT-PCR. Adherence of U937 to HAECs was assessed by adhesion assay. Incubation of HAEC with 7-KC increased the surface expression of protein and mRNA levels of ICAM-1 and VCAM-1 on HAECs and the production of reactive oxygen species (ROS) in HAECs. Pretreatment with alacepril reduced the enhanced expression of these molecules in a dose-dependent manner. The inhibitory effect of alacepril against 7-KC or TNF-alpha-induced CAMs expression was stronger than that of captopril or enalapril. Alacepril inhibited the production of ROS in HAECs stimulated by 7-KC or TNF-alpha. These results suggest that alacepril works as anti-atherogenic agent through inhibiting endothelial-dependent adhesive interactions with monocytes induced by 7-KC and TNF-alpha.

New links between inflammation and thrombosis

This article is a summary of the Sol Sherry Lecture of the Council on Arteriosclerosis, Thrombosis, and Vascular Biology, which was presented at the Scientific Sessions of the American Heart Association in November 2004. It highlights work from our laboratory, focusing mainly on new aspects of P-selectin and CD40L (CD154) biology and on the interplay of platelets and leukocytes in thrombosis and inflammation.

The single nucleotide polymorphism Ser128Arg in the E-selectin gene is associated with enhanced coagulation during human endotoxemia

The single nucleotide polymorphism (SNP) Ser128Arg in the E-selectin gene is overrepresented in certain patient groups with atherosclerosis or restenosis. We hypothesized and tested whether it may affect cytokine-induced levels of soluble (s) E-selectin, or be associated with proinflammatory or procoagulant properties in a well-standardized inflammation model. Healthy male volunteers (n = 157) received a lipopolysaccharide (LPS) infusion and were genotyped for the S128R SNP, and outcome parameters were measured by enzyme immunoassays and real-time polymerase chain reaction (RT-PCR, Taqman). The S128R SNP had no pronounced effects on basal or inducible sE-selectin levels, or levels of tumor necrosis factor or interleukin-6. However, carriers of the S128R SNP had 20% higher monocyte counts at 24 hours after LPS infusion. Importantly, the S128R allele enhanced thrombin generation by 50% to 80%, as measured by prothrombin fragment F1+2 (P &lt; .01), and hence fibrin formation (D-dimer) 2-fold (P = .01 to P = .002). However, tissue factor (TF) mRNA levels were not affected. The S128R E-selectin genotype is associated with procoagulant effects in a human model of endotoxin-induced, TF-triggered coagulation. This could contribute to its linkage with various thrombotic cardiovascular disorders.

Alpha(1,3)fucosyltransferases FucT-IV and FucT-VII control susceptibility to atherosclerosis in apolipoprotein E-/- mice

OBJECTIVE

These studies examine the contributions of alpha(1,3)fucosyltransferases (FucT) IV and VII to the generation of selectin counter-receptors necessary for selectin-dependent atherogenesis. They also determine the functional contribution of FucT-IV and FucT-VII to shear-dependent tethering of monocytes to P-selectin, a process believed to be required for atherogenesis.

METHODS AND RESULTS

Atherosclerotic lesion size and histology were determined in apolipoprotein E-/- mice sufficient or deficient in FucT-IV or FucT-VII. Lesion size was subtly reduced in FucT-IV-deficient mice and significantly reduced in FucT-VII-deficient mice. FucT deficiency did not alter lesion histology, plasma total cholesterol, or the lipoprotein distribution profile. Atheroprotection in FucT-IV or FucT-VII deficiency aligned with subtle and profound reductions, respectively, of P-selectin counter-receptor activity on peripheral blood monocytes as determined by tethering to P-selectin-IgG in vitro under shear flow.

CONCLUSIONS

FucT-VII-mediated alpha(1,3)fucosylation of selectin ligands is a necessary concomitant to atherogenesis in apoE-/- mice and is required for P-selectin-dependent peripheral blood monocyte adhesion under shear stress. FucT-IV deficiency yields subtle deficits in monocyte P-selectin counter-receptor activity and is associated with a subtle decrement in atherosclerosis. These studies identify an important role for FucT-VII in atherogenesis, and a subsidiary role for FucT-IV, and implicate leukocyte selectin counter-receptors in the pathogenesis of atherosclerosis.

Inflammation meets oxidation: NF-kappaB as a mediator of initial lesion development in atherosclerosis

Transcription factor nuclear factor-kappaB (NF-kappaB) and its target genes are involved in the pathogenesis of atherosclerosis, in addition to many other diseases. Monocyte recruitment into subendothelial space is primarily mediated by NF-kappaB-dependent gene expression, and this event is a crucial milestone, because it is nearly impossible to reverse the progression of the lesion after this point. Recent advances in our understanding of atherosclerosis as a disease of childhood enforces the necessity of developing novel approaches for prevention and treatment. Here, the authors address NF-kappaB as a major therapeutic target, especially for preventive measures, in the light of two main hypotheses of atherosclerosis: oxidation and inflammation.

Platelet P-selectin facilitates atherosclerotic lesion development

P-selectin is an adhesion molecule expressed on activated platelets and endothelium. It is known to play an important role in atherosclerosis. P-selectin also circulates in plasma in a soluble form (sP-selectin), which induces procoagulant microparticle formation. We investigated the role of platelet versus endothelial P-selectin in generating sP-selectin and in the formation of atherosclerotic lesions in the apolipoprotein E (apoE)-deficient mouse model. For this we transplanted apoE(-/-)P-selectin(-/-) and apoE(-/-)P-selectin(+/+) lethally irradiated mice with bone marrow of either genotype. Seven months after transplantation, we determined from the chimeric animals that the majority of circulating sP-selectin was of endothelial origin. Thus, in atherosclerosis, the procoagulant sP-selectin reflects endothelial rather than platelet activation. We found that endothelial P-selectin was crucial for the promotion of atherosclerotic lesion growth because in its absence only relatively small lesions developed. However, platelet P-selectin also contributed to the lesion development because lesions in wild-type recipients receiving transplants with wild-type platelets were 30% larger than those receiving P-selectin-deficient platelets (P <.008) and were more frequently calcified (80% versus 44%). In comparison with P-selectin wild-type animals, absence of either endothelial or platelet P-selectin inhibited migration of smooth muscle cells into the lesion. Thus, in addition to endothelium, platelets and their P-selectin also actively promote advanced atherosclerotic lesion development.

Cigarette smoking as a significant risk factor for digital vascular disease in patients with systemic sclerosis

OBJECTIVE

Patients with systemic sclerosis (SSc) are at high risk for digital vascular complications, including amputation and gangrene. Cigarette smoking is an important risk factor for vascular disease in the general population. We investigated the influence of cigarette smoking on digital ischemia in patients with SSc.

METHODS

We studied 101 patients with SSc (87 women and 14 men, median age 53 years, median disease duration 13 years). Smoking history was defined in terms of current smoking status and total number of pack-years. Digital ischemic events were classified as debridement, hospital admission for intravenous (IV) administration of vasodilators, and digital amputation. The influence of smoking on digital ischemic events was examined using logistic regression, adjusting for age, sex, and disease duration. Results are expressed as the odds ratio (OR) and 95% confidence interval (95% CI).

RESULTS

Of the 101 patients, 21 (21%) were current smokers, 37 (37%) were ex-smokers, and 43 (43%) had never smoked. After adjusting for age, sex, and disease duration, current smokers were significantly more likely than never-smokers to have had debridement (OR 4.5, 95% CI 1.1-18.3) or admission for IV vasodilators (OR 3.8, 95% CI 1.1-12.9). Patients smoking at higher intensity were more likely to require admission for IV vasodilators.

CONCLUSION

Among patients with SSc, current smokers are 3-4 times more likely than never-smokers to incur digital vascular complications. Resources should be directed to supporting smoking cessation in patients with SSc.

Direct modulatory effect of C-reactive protein on primary human monocyte adhesion to human endothelial cells

C-reactive protein (CRP) is the prototypic acute phase serum protein in humans. The effects of CRP on primary human monocyte adhesion molecule expression and interaction with the endothelium have not been studied. Herein, we describe an investigation into the phenotypic and functional consequences of CRP binding to peripheral blood monocytes ex vivo. Peripheral whole blood was collected from healthy, non-smoking males. Mononuclear cells (MNC) and monocytes were isolated by differential centrifugation using lymphoprep and Dynal negative isolation kit, respectively. Cells were exposed to CRP from 0 to 250 micro g/ml for 0-60 min at 37 degrees C and analysed for (a) CD11b, PECAM-1 (CD31) and CD32 expression by flow cytometry and (b) adhesion to LPS (1 micro g/ml; 0-24 h) treated human umbilical vein endothelial cells (HUVEC). CD14+ monocyte expression of CD11b increased significantly up to twofold when exposed to CRP, compared to controls. There was no significant difference in CD32 expression, whereas CD31 expression decreased after exposure to CRP. CRP treatment of monocytes inhibited their adhesion to early LPS-activated HUVEC (0-5 h). However, the adhesion of CRP-treated monocytes to HUVEC was significantly greater to late activation antigens on HUVEC (24 h, LPS) compared to controls. We have shown that CRP can affect monocyte activation ex vivo and induce phenotypic changes that result in an altered recruitment to endothelial cells. This study provides the first evidence for a further role for C-reactive protein in both monocyte activation and adhesion, which may be of importance during an inflammatory event.

Endothelial cell expression of adhesion molecules is induced by fetal plasma from pregnancies with umbilical placental vascular disease

OBJECTIVE

To test the hypothesis that local production with spill into the fetal circulation of factor(s) injurious to endothelium is responsible for the vascular pathology present when the umbilical artery Doppler study is abnormal. Expression of adhesion molecules is a feature of endothelial cell activation.

DESIGN

Case-control study.

SETTING

University teaching hospital.

SAMPLES

Fetal plasma was collected from 27 normal pregnancies, 39 pregnancies with umbilical placental vascular disease defined by abnormal umbilical artery Doppler and 11 pregnancies with pre-eclampsia and normal umbilical artery Doppler.

METHODS

Isolated and cultured human umbilical vein endothelial cells from normal pregnancies were incubated with fetal plasma from three study groups. mRNA expression of intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) were assessed by reverse transcription-polymerase chain reaction. To confirm the occurrence of this in vivo, we measured the levels of soluble fractions of sICAM-1, sVCAM-1 and sPECAM-1 in the fetal circulation in the fetal plasma used for endothelial cell incubation.

RESULTS

The mRNA expression of ICAM-1 [median 1.1 (interquartile range 0.5-1.9) vs 0.7 (0.3-1.2), P < 0.05] and PECAM-1 [2.1 (1.2-3.0) vs 1.5 (0.7-2.1), P < 0.05] was significantly higher following incubation with fetal plasma from umbilical placental vascular disease compared with the normal group. There was no difference in the expression of VCAM-1 [1.2 (0.9-1.8) vs 1.1 (0.8-1.6), ns]. The group with maternal pre-eclampsia and normal umbilical artery Doppler did not differ from the normal group. In the umbilical placental vascular disease group, the results were similar in the presence or absence of pre-eclampsia. For soluble fractions of the adhesion molecules released into the fetal circulation, we found the levels (ng/mL) of sICAM- I [median 248.5 (interquartile range 197.3-315.7) vs 174.2 (144.5-212.9), P < 0.05] and sPECAM-1 [9.3 (6.2-11.1) vs 6.1 (5.4-7.7), P < 0.05] in fetal plasma to be significantly increased in the presence of umbilical placental vascular disease compared with the normal.

CONCLUSIONS

Vascular disease in the fetal umbilical placental circulation is associated with an elevation in mRNA expression by endothelial cells of ICAM-1 and PECAM-1. Our study provides evidence for endothelial cell activation and dysfunction in umbilical placental vascular disease. We speculate that the plasma factor(s) affecting the vessels of the umbilical villous tree is locally released by the trophoblast. The occurrence of the maternal syndrome of pre-eclampsia appears to be independent of this.

Reduced expression of endothelial cell markers after 1 year treatment with simvastatin and atorvastatin in patients with coronary heart disease

The study was aimed at investigating the effects, after treatment for 1 year, of two different statins on the levels of circulating biochemical markers of endothelial function in patients with established coronary heart disease, with the hypothesis that statins might reduce these levels. Twenty-eight patients were randomized to treatment with atorvastatin and 30 to simvastatin for 1 year. The starting dose in both groups was 20 mg/day. Soluble forms of P-selectin, E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were determined to assess inflammatory activity of the endothelium, and tissue plasminogen activator antigen (tPAag), von Willebrand factor and thrombomodulin for evaluation of the haemostatic function. In the total study population there were significantly reduced levels after 1 year treatment in ICAM-1 (P<0.001), E-selectin (P=0.022) and P-selectin (P<0.001), whereas a significant increase was observed in VCAM-1 (P=0.003). Almost the same pattern was seen within both groups although the increase in VCAM-1 was only seen in the simvastatin group (P=0.017). An overall reduction in tPAag was further observed (P=0.048). The reduction in proinflammatory and to some extent haemostatic markers of endothelial function after 1 year treatment with either simvastatin or atorvastatin may be indicative of a less activated state of the endothelium which possibly may contribute to modulation of the progression of atherosclerosis.

Serum levels of selected adhesion molecules in patients with coronary artery disease

BACKGROUND

Adhesion molecules have been suggested as mediators of atherosclerotic inflammatory process. They may contribute to the pathogenesis of stable and unstable angina.

METHODS

The study group consisted of 59 patients with coronary artery disease: 27 patients with stable exertional angina (group A), 32 patients with unstable angina (group B). 20 healthy persons acted as controls (group C). Serum levels of soluble Intercellular Adhesion Molecule 1 (sICAM-1), Vascular Cell Adhesion Molecule 1 (sVCAM-1), sE-selectin, sP-selectin were measured both before and after the treadmill ECG stress test in groups A and C. In group B the measurements were carried out at 6, 24, and 48 hours following an episode of chest pain.

RESULTS

There were no differences between the baseline serum levels of adhesion molecules as determined in groups A and C. In patients with stable angina, the post-exercise concentrations of sE-selectin were significantly higher (68.8+/-29 ng/ml) in comparison to both baseline- (38.7+/-15 ng/ml), and group C-values (pre-exercise: 35.1+/-16; post-exercise: 49.9+/-15 ng/ml). In unstable patients, serum sP-selectin (190.1+/-99 ng/ml) and sVCAM-1 levels (1359+/-299 ng/ml) were higher when compared to those found in groups A (142.3+/-24; 962+/-352 ng/ml, respectively) and C (136.4+/-33; 851+/-168 ng/ml, respectively).

CONCLUSIONS

Serum levels of soluble adhesion molecules in patients with stable angina are comparable to those of healthy persons. Stress test-induced increase of sE-selectin concentration may reflect endothelial response to exercise. Unstable angina is characterized by significant elevation of sP-selectin and sVCAM-1 serum levels which seems to be related to enhanced platelets and leukocytes activation.

Involvement of ICAM-1 in the progression of atherosclerosis in APOE-knockout mice

Recent clinical evidence has indicated that the level of soluble ICAM-1 (sICAM-1) is correlated with the severity of atherosclerosis and can predict future cardiovascular events. Here, using apolipoprotein E (APOE)-deficient mice, we investigated the level of sICAM-1 in parallel with endothelial ICAM-1 expression and aortic atherosclerosis. We also examined the effect of ICAM-1 deficiency during the progression of atherosclerosis using double knockout mice. The level of sICAM-1 increased significantly in parallel with the progression of atherosclerosis in APOE-deficient mice, while the sICAM-1 level remained constant in wild-type mice from 3 to 10 months of age. ICAM-1 staining was detected in virtually all endothelial cells, however, ICAM-1 was expressed strongly in the endothelium overlying atheromatous palque in APOE-deficient mice. Deficiency of ICAM-1 in APOE-deficient mice significantly reduced lesions after 5 and 10 months. The present study supported the notion that the level of sICAM-1 is closely related with the severity of atherosclerosis and cardiovascular events, and also suggested that inhibition of ICAM-1 can delay the progression of atherosclerosis.

Endogenous heparin activity deficiency: the 'missing link' in atherogenesis?

This paper reviews published studies since 1995 dealing with many atherogenic mechanisms where exogenous heparin was beneficial. In these areas endogenous heparin deficiency is likely to be harmful. Mechanisms included inflammatory factors, lower endogenous plasma heparin levels, lipoprotein lipase, chemokines, APOE e4, lipoprotein(a), among others. Demonstrated reduction of heparan sulfate proteoglycans (HSPG) and of endogenous plasma heparin was reviewed.

Therapeutic potential of dietary phase 2 enzyme inducers in ameliorating diseases that have an underlying inflammatory component

Many diseases associated with ageing have an underlying oxidative stress and accompanying inflammatory component, for example, Alzheimer's disease or atherosclerosis. Reviewed in this manuscript are: the role of oxidative stress in activating the transcription factor nuclear factor kappa B (NFκB), the role of NFκB in activating pro-inflammatory gene transcription, strong oxidants produced by cells, anti-oxidant defense systems, the central role of phase 2 enzymes in the anti-oxidant defense, dietary phase 2 enzyme inducers and evidence that dietary phase 2 enzymes decrease oxidative stress. It is likely that a diet containing phase 2 enzyme inducers may ameliorate or even prevent diseases that have a prominent inflammatory component to them. Research should be directed into the potential therapeutic effects of dietary phase 2 enzyme inducers in ameliorating diseases with an underlying oxidative stress and inflammatory component to them.Key words: Alzheimer's disease, atherosclerosis, diet, glutathione, inflammation, stroke.

Prominent role of P-selectin in the development of advanced atherosclerosis in ApoE-deficient mice

BACKGROUND

Adhesive interactions between leukocytes and endothelial cells are characteristic of the development of atherosclerotic lesions, but the receptors involved remain to be defined. P-selectin is an adhesion receptor expressed on activated endothelial cells or platelets and was shown to be involved in fatty streak formation in LDL receptor-deficient mice on an atherogenic diet. The main purpose of this study is to examine the role of P-selectin in the spontaneous development of advanced atherosclerosis in apoE-deficient mice. METHODDS AND RESULTS: We intercrossed P-selectin-deficient mice with mice lacking apoE and compared lesion development in apoE-deficient mice with P-selectin (apoE(-/-) P(+/+)) and without P-selectin (apoE(-/-) P(-/-)) that were fed normal mouse chow. At 4 months of age, apoE(-/-) P(-/-) mice had 3. 5-fold smaller aortic sinus lesions than apoE(-/-) P(+/+) mice. These were limited to fatty streaks in the apoE(-/-) P(-/-) mice, whereas 70% of apoE(-/-) P(+/+) lesions contained smooth muscle cells. Significantly more of the aortic sinus circumference was covered by lesions in the apoE(-/-) P(+/+) animals. The P-selectin genotype affected macrophage recruitment, because twice as many mononuclear cells were present in the P-selectin-positive lesions. At 15 months, the lesions progressed to the fibrous plaque stage in both genotypes and spread throughout the aorta, but this process was delayed in apoE(-/-) P(-/-) mice. In the aortic sinus, the lesions of the apoE(-/-) P(-/-) mice were 2.6-fold smaller and less calcified.

CONCLUSIONS

P-selectin appears to be a key adhesion receptor mediating leukocyte recruitment into lesions and promoting advanced atherosclerosis in apoE-deficient mice.

The mechanisms of coronary restenosis: insights from experimental models

Since its introduction into clinical practice, more than 20 years ago, percutaneous transluminal coronary angioplasty (PTCA) has proven to be an effective, minimally invasive alternative to coronary artery bypass grafting (CABG). During this time there have been great improvements in the design of balloon catheters, operative procedures and adjuvant drug therapy, and this has resulted in low rates of primary failure and short-term complications. However, the potential benefits of angioplasty are diminished by the high rate of recurrent disease. Up to 40% of patients undergoing angioplasty develop clinically significant restenosis within a year of the procedure. Although the deployment of endovascular stents at the time of angioplasty improves the short-term outcome, 'in-stent' stenosis remains an enduring problem. In order to gain an insight into the mechanisms of restenosis, several experimental models of angioplasty have been developed. These have been used together with the tools provided by recent advances in molecular biology and catheter design to investigate restenosis in detail. It is now possible to deliver highly specific molecular antagonists, such as antisense gene sequences, to the site of injury. The knowledge provided by these studies may ultimately lead to novel forms of intervention. The present review is a synopsis of our current understanding of the pathological mechanisms of restenosis.

Tobacco-related diseases. Is there a role for antioxidant micronutrient supplementation?

It is clear that smoking causes an increase in free radicals, reactive nitrogen and oxygen species (RNS and ROS, respectively), and that cigarette smoking is associated with increases in the incidence and severity of several diseases including atherosclerosis, cancer, and chronic obstructive lung disease. Although there is still no unequivocal evidence that oxidative stress is a contributor to these diseases or that an increased intake of antioxidant nutrients is beneficial, the observation that smokers have lower circulating levels of some of these nutrients, raises concern. This article discusses the possible links between the observed oxidant-induced damage related to tobacco smoking, effects on cellular mechanisms, and their potential involvement in the causation and enhancement of disease processes.

Dexamethasone lowers circulating E-selectin and ICAM-1 in healthy men

Plasma levels of circulating adhesion molecules (AMs) are increased in a number of inflammatory and cardiovascular disorders. Yet the mechanisms regulating the physiologic levels of soluble AMs are largely unknown. It has recently been postulated that glucocorticoids may exert their anti-inflammatory actions partially through the inhibition of cytokine-stimulated expression of E-selectin and intercellular adhesion molecule (ICAM-1). However, it remains controversial whether glucocorticoids affect the basal expression of AMs on resting cells. We have thus evaluated the effects of glucocorticoids by infusing therapeutic doses of dexamethasone (0.04 mg/kg and 1.0 mg/kg twice a day for 2 days) or placebo on plasma levels of circulating E-selectin (cE-selectin), soluble thrombomodulin (sTM), circulating ICAM-1 (cICAM-1), and circulating vascular cell adhesion molecule (cVCAM-1) in 9 healthy men. Plasma was obtained before infusion at 24 and 48 hours. Compared with baseline, levels of cE-selectin decreased by 16% and 22% with the lower and the higher doses, respectively, at 48 hours (P = .007), whereas sTM was unchanged. Both doses of dexamethasone reduced cICAM-1 by about 15% at 48 hours (P = .007), but there were no changes in cVCAM. Dexamethasone time-dependently decreases plasma levels of cE-selectin and cICAM-1 in healthy men. This demonstrates that a glucocorticoid-sensitive mechanism specifically down-regulates normal plasma levels of cE-selectin and cICAM-1 in healthy subjects, which could thus reflect minor baseline inflammation.

P-Selectin or intercellular adhesion molecule (ICAM)-1 deficiency substantially protects against atherosclerosis in apolipoprotein E-deficient mice

The expression of leukocyte and endothelial cell adhesion molecules (CAMs) is essential for the emigration of leukocytes during an inflammatory response. The importance of the inflammatory response in the development of atherosclerosis is indicated by the increased expression of adhesion molecules, proinflammatory cytokines, and growth factors in lesions and lesion-prone areas and by protection in mice deficient in various aspects of the inflammatory response. We have quantitated the effect of deficiency for intercellular adhesion molecule (ICAM)-1, P-selectin, or E-selectin on atherosclerotic lesion formation at 20 wk of age in apolipoprotein (apo) E(-/-) (deficient) mice fed a normal chow diet. All mice were apo E(-/-) and CAM(+/+) or CAM(-/-) littermates, and no differences were found in body weight or cholesterol levels among the various genotypes during the study. ICAM-1(-/-) mice had significantly less lesion area than their ICAM-1(+/+) littermates: 4.08 +/- 0.70 mm(2) for -/- males vs. 5.87 +/- 0.66 mm(2) for +/+ males, and 3.95 +/- 0. 65 mm(2) for -/- females vs. 5.59 +/- 1.131 mm(2) for +/+ females, combined P < 0.0001. An even greater reduction in lesion area was observed in P-selectin(-/-) mice: 3.06 +/- 1.04 mm(2) for -/- males vs. 5.09 +/- 1.22 mm(2) for +/+ males, and 2.85 +/- 1.26 mm(2) for -/- females compared with 5.60 +/- 1.19 mm(2) for +/+ females, combined P < 0.001. The reduction in lesion area for the E-selectin null mice, although less than that seen for ICAM-1 or P-selectin, was still significant (4.54 +/- 2.14 mm(2) for -/- males vs. 5.92 +/- 0.63 mm(2) for +/+ males, and 4.38 +/- 0.85 mm(2) for -/- females compared with 5.94 +/- 1.44 mm(2) for +/+ females, combined P < 0.01). These results, coupled with the closely controlled genetics of this study, indicate that reductions in the expression of P-selectin, ICAM-1, or E-selectin provide direct protection from atherosclerotic lesion formation in this model.

Functional characterization of atherosclerosis-associated Ser128Arg and Leu554Phe E-selectin mutations

The cellular adhesion molecule E-selectin is expressed on activated endothelial cells, and is involved in the process of adherence of blood cells to vessel endothelium in inflammatory events such as atherosclerosis. In a recent study we found a Ser128Arg mutation in the EGF domain as well as a Leu554Phe mutation in the membrane domain of E-selectin. We also established increased frequencies of both mutations among young patients with severe coronary atherosclerosis. In the present study we investigated the influence of these mutations on cell adhesion and on the release of soluble E-selectin. Mutants were created by site-directed mutagenesis and COS cells were transfected with E-selectin, either wild-type or mutant. Antibody-binding studies and cell-adhesion assays were performed on transfected COS cells and on interleukin-1 beta-stimulated HUVECs. Soluble E-selectin in supernatants of wild type and Leu554Phe mutant-transfected COS cells was measured by ELISA. We discovered significant differences in the strength of HL-60 cell adhesion for the Ser128Arg mutant: in comparison with the wild type, the strength of adhesion to the mutant was reduced on transfected COS cells (P < 0.01) as well as on stimulated HUVECs (P < 0.01). Significantly diminished release of soluble E-selectin was detected for the Leu554Phe membrane domain mutant, in comparison with the wild type. In summary, the mutations studied here influence the E-selectin function in vitro and may be considered as one of the risk factors involved in the complex pathogenesis of atherosclerosis.