Neovascular expression of E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 in human atherosclerosis and their relation to intimal leukocyte content

Monocyte Arrest and Transmigration on Inflamed Endothelium in Shear Flow Is Inhibited by Adenovirus-Mediated Gene Transfer of IκB-

Mobilization of nuclear factor-κB (NF-κB) activates transcription of genes encoding endothelial adhesion molecules and chemokines that contribute to monocyte infiltration critical in atherogenesis. Inhibition of NF-κB has been achieved by pharmacological and genetic approaches; however, monocyte interactions with activated endothelium in shear flow following gene transfer of the NF-κB inhibitor IκB- have not been studied. We found that overexpression of IκB- in endothelial cells using a recombinant adenovirus prevented tumor necrosis factor- (TNF-)–induced degradation of IκB- and suppressed the upregulation of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin mRNA and surface protein expression and the upregulation of transcripts for the chemokines monocyte chemoattractant protein 1 (MCP-1) and growth-related activity- (GRO-) by TNF-. This was associated with a reduction in endothelial MCP-1 secretion and GRO- immobilization. Adhesion assays under physiological shear flow conditions showed that firm arrest, spreading, and transmigration of monocytes on TNF-–activated endothelium was markedly inhibited by IκB- overexpression. Inhibition with monoclonal antibodies and peptide antagonists inferred that this was due to reduced expression of Ig integrin ligand as well as of chemokines specifically involved in these events. In contrast, rolling of monocytes was increased by IκB- transfer and was partly mediated by P-selectin; however, it appeared to be unaffected by the inhibition of E-selectin induction. Thus, our data provide novel evidence that selective modulation of NF-κB by adenoviral transfer of IκB- impairs the expression of multiple endothelial gene products required for subsequent monocyte arrest and emigration in shear flow and thus for monocyte infiltration in atherosclerotic plaques.

Monocyte Arrest and Transmigration on Inflamed Endothelium in Shear Flow Is Inhibited by Adenovirus-Mediated Gene Transfer of IκB-

Mobilization of nuclear factor-κB (NF-κB) activates transcription of genes encoding endothelial adhesion molecules and chemokines that contribute to monocyte infiltration critical in atherogenesis. Inhibition of NF-κB has been achieved by pharmacological and genetic approaches; however, monocyte interactions with activated endothelium in shear flow following gene transfer of the NF-κB inhibitor IκB- have not been studied. We found that overexpression of IκB- in endothelial cells using a recombinant adenovirus prevented tumor necrosis factor- (TNF-)–induced degradation of IκB- and suppressed the upregulation of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin mRNA and surface protein expression and the upregulation of transcripts for the chemokines monocyte chemoattractant protein 1 (MCP-1) and growth-related activity- (GRO-) by TNF-. This was associated with a reduction in endothelial MCP-1 secretion and GRO- immobilization. Adhesion assays under physiological shear flow conditions showed that firm arrest, spreading, and transmigration of monocytes on TNF-–activated endothelium was markedly inhibited by IκB- overexpression. Inhibition with monoclonal antibodies and peptide antagonists inferred that this was due to reduced expression of Ig integrin ligand as well as of chemokines specifically involved in these events. In contrast, rolling of monocytes was increased by IκB- transfer and was partly mediated by P-selectin; however, it appeared to be unaffected by the inhibition of E-selectin induction. Thus, our data provide novel evidence that selective modulation of NF-κB by adenoviral transfer of IκB- impairs the expression of multiple endothelial gene products required for subsequent monocyte arrest and emigration in shear flow and thus for monocyte infiltration in atherosclerotic plaques.

Cytokine secretion profiles of cloned T cells from human aortic atherosclerotic plaques

T cells take part in the chronic inflammatory reaction in atherosclerotic plaques, but their specific role in atherosclerosis has not yet been fully elucidated. Nevertheless, one may anticipate that activated T cells may secrete cytokines capable of modulating the morphology and hence the stability of plaques by regulating cell proliferation, lipid metabolism, and extracellular matrix (ECM) synthesis and/or degradation. This study has been designed to investigate the functional properties of T cells in atherosclerotic lesions. For this purpose, T-cell clones were generated from atherosclerotic plaques isolated from human aortas obtained at autopsy from six subjects. Cloned cells were activated with PMA and OKT-3 to initiate cytokine production and cytokine profiles of CD4-positive clones were measured by ELISA. The majority of the T-cell clones (125/155, 81 per cent) produced both interferon (IFN)-gamma and interleukin (IL)-4 (type 0 cytokine profile). Moreover, the production of IFN-gamma was dominant in the majority of these clones. A type 1 cytokine profile (high levels of IFN-gamma and low levels of IL-4) was found in 17 per cent of the clones (27/155). Only three clones (2 per cent) showed a type 2 cytokine secretion pattern (high levels of IL-4 and low levels of IFN-gamma). No cytolytic activity could be established in plaque-derived T cells. Our results show that the T-cell population in atherosclerotic lesions is heterogeneous, but the most dominant T cell by far is the one with a type 0 cytokine profile. The dominant secretion of IFN-gamma by T-cell clones suggest an important role for plaque T cells in modulating the growth and differentiation of other cells, such as macrophages and smooth muscle cells in atherosclerotic plaques.

T lymphocytes induce endothelial cell matrix metalloproteinase expression by a CD40L-dependent mechanism: implications for tubule formation

Neovascularization frequently accompanies chronic immune responses characterized by T cell infiltration and activation. Angiogenesis requires endothelial cells (ECs) to penetrate extracellular matrix, a process that involves matrix metalloproteinases (MMPs). We report here that activated human T cells mediate contact-dependent expression of MMPs in ECs through CD40/CD40 ligand signaling. Ligation of CD40 on ECs induced de novo expression of gelatinase B (MMP-9), increased interstitial collagenase (MMP-1) and stromelysin (MMP-3), and activated gelatinase A (MMP-2). Recombinant human CD40L induced expression of MMPs by human vascular ECs to a greater extent than did maximally effective concentrations of interleukin-1beta or tumor necrosis factor-alpha. Moreover, activation of human vascular ECs through CD40 induced tube formation in a three-dimensional fibrin matrix gel assay, an effect antagonized by a MMP inhibitor. These results demonstrated that activation of ECs by interaction with T cells induced synthesis and release of MMPs and promoted an angiogenic function of ECs via CD40L-CD40 signaling. As vascular cells at the sites of chronic inflammation, such as atherosclerotic plaques, express CD40 and its ligand, our findings suggest that ligation of CD40 on ECs can mediate aspects of vascular remodeling and neovessel formation during atherogenesis and other chronic immune reactions.

Levels of soluble cell adhesion molecules in patients with angiographically defined coronary atherosclerosis

Adhesion molecules on the endothelial cell membrane play an important role in the pathogenesis of atherosclerosis. Levels of soluble forms of cell adhesion molecules are reportedly elevated in patients with peripheral artery vessel disease and in patients with an atherosclerotic aorta. The present study investigated the association of serum levels of soluble vascular cell adhesion molecule 1 (sVCAM-1), soluble intercellular adhesion molecule 1 (sICAM-1), and soluble P-selectin (sP-selectin) with coronary heart disease (CHD) and the extent of coronary atherosclerosis, and examined the influence of serum levels of lipids, lipoproteins and apolipoproteins (apo) in subjects with (n=52, M/F:43/9) and without (controls, n=40, M/F:25/15) angiographically proven coronary atherosclerosis. After controlling for age and gender, levels of sVCAM-1 (least squares mean +/- std error: 565+/-36 ng/ml vs 540+/-41 ng/ml, ns), sICAM-1 (261+/-17ng/ml vs 247+/-19ng/ml, ns), and sP-selectin (142+/-8ng/ml vs 149+/-10 ng/ml, ns) in patients with coronary atherosclerosis were not different from those in controls, as assessed by an analysis of covariance. After also adjusting for body mass index, hypertension, diabetes mellitus, and smoking by a multiple logistic function analysis, the association of sVCAM-1, sICAM-1, and sP-selectin with CHD was still not significant. Levels of sVCAM-1, sICAM-1, and sP-selectin were also not related to the extent of coronary atherosclerosis as judged by the number of stenosed vessels. However, inverse (p<0.05) relationships were observed between sVCAMs and serum levels of HDL3-cholesterol, apo A-II, and lipoprotein containing apo A-I and A-II, between sICAMs and levels of apo A-II and Lp A-I/A-II (Lp A-I/A-II), and between sP-selectin and lipoprotein containing only apo A-I. In conclusion, serum levels of soluble VCAM-1, ICAM-1, and P-selectin were not related to CHD or the extent of coronary atherosclerosis, but were inversely related to serum levels of high-density lipoprotein-related lipoproteins.

Chimeric 7E3 Fab (ReoPro) decreases detectable CD11b on neutrophils from patients undergoing coronary angioplasty

OBJECTIVES

The purpose of this study was to monitor the effects of chimeric 7E3 Fab (ReoPro) on leukocyte and platelet activation and interaction during coronary angioplasty.

BACKGROUND

Increased expression of CD11b on monocytes and neutrophils promotes their adhesion to endothelial cells, extracellular matrix and smooth muscle cells. Thrombin-activated platelets adhere via P-selectin to monocytes and neutrophils. These cell interactions may affect the outcome of coronary angioplasty.

METHODS

During coronary angioplasty, venous blood was obtained for flow cytometric detection of leukocyte CD11b; platelet CD41a, CD61a and CD62P; the percentage of leukocytes with adherent platelets and the intensity of bound platelet fluorescence.

RESULTS

Leukocyte CD11b expression increased after angioplasty in control patients (neutrophils 171+/-25 to 255+/-31 mean fluorescence intensity [MFI, mean+/-SEM], n=25, p < 0.0001; monocytes 200+/-40 to 248+/-36 MFI, n=17, p < 0.05) and decreased in the patients selected to receive chimeric 7E3 Fab (neutrophils 146+/-30 to 82+/-22 MFI, n=25, p < 0.0001; monocytes 256+/- 53 to 160+/-38 MFI, n= 17, p < 0.05). Neutrophil CD11b decreased after in vitro incubation of whole blood with chimeric 7E3 Fab (n=5, p=0.01), but fMLP-induced increases in CD11b were not prevented. The CD11b expression was unchanged and increased with fMLP stimulation after in vitro incubation of isolated neutrophils with chimeric 7E3 Fab. Direct-labeled chimeric 7E3 Fab was not detected bound to neutrophils in whole blood or isolated cells using flow cytometric techniques. Adhesion of isolated neutrophils to protein-coated glass was not prevented by in vitro incubation with chimeric 7E3 Fab. Platelet activation increased after angioplasty in control patients (CD62P 8.9+/-0.8 to 12.3+/-1.2 MFI, n=25, p < 0.05; CD41a 382+/-25 to 454+/-26 MFI, n=25, p < 0.05, CD61a 436+/-52 to 529+/-58 MFI, n=11, p < 0.05); it did not increase in the patients selected to receive chimeric 7E3 Fab (CD62P 13.2+/-1.0 to 9.0+/-0.9 MFI, n=25, p < 0.05; CD61a 398+/-32 to 410+/-38 MFI, n=7, p=NS). Leukocytes with adherent platelets tended to increase in the control group of patients and decrease after the procedure in patients selected to receive chimeric 7E3 Fab; individual and procedure-related variability were marked.

CONCLUSIONS

Despite standard aspirin and heparin therapy, leukocyte and platelet activation with platelet adherence to leukocytes occurs after coronary angioplasty. Although chimeric 7E3 Fab does not bind to leukocytes directly, it influences CD11b expression in whole blood. Modulation of platelet and leukocyte activation and interaction by chimeric 7E3 Fab may contribute to an improved outcome after coronary angioplasty.

The role of adhesion molecules in atherosclerosis

The progression of atherosclerosis is currently believed to involve the interaction of monocytes with the vascular endothelium. Within the last decade, the cell-surface proteins thought to control these interactions have been investigated. This review seeks to describe the nature of these interactions through what are known as adhesion molecules and their role in atherogenesis. It begins with the stages of atherogenesis from the movement of the monocyte to the endothelium, followed by the migration of smooth muscle cells from the media to the intima, and subsequently to the later stages of fibrofatty plaque formation and potential complications due to thrombosis and/or plaque fissure and embolism. The different structural classifications of the adhesion molecules, such as integrins, cadherins, selectins, and members of the immunoglobulin gene superfamily, are outlined, and interaction of binding domains are highlighted. The vascular endothelium and the basic role of adhesion molecules in dysfunction are considered. Discussion of the role of adhesion molecules in atherogenesis focuses on interactions of the endothelium, monocytes, and leukocytes, as well as the influences of cytokines, oxidized low-density lipoproteins, and genetic determinants. Finally, epidemiological risk factors associated with atherosclerosis such as hypertension and dyslipidemia are considered in light of their effects on adhesion molecule expression.

Importance of endothelial function in mediating the benefits of lipid-lowering therapy

Trials of lipid lowering by various methods have clearly demonstrated the benefits, clinically and angiographically. Evidence of slowed arterial disease progression and even regression has been convincing but modest, at best. For example, among those treated intensively in the Familial Atherosclerosis Treatment Study (FATS), the mean improvement in proximal stenosis severity was <1% per patient, and only 12% of all lesions showed convincing regression. Despite these modest arterial benefits, the associated reductions in major cardiovascular events have been surprisingly great (24-35% in 3 recent large trials and > or =50% in angiographic trials using combination therapies). The process of plaque disruption helps explain this discrepancy. Disruption can be predicted by a large accumulation of core lipid in the plaque and a high density of lipid-laden macrophages in its thinned fibrous cap. Lesions with these characteristics comprise only 10-20% of the overall lesion population but account for 60-90% of the acute clinical events. Lipid-lowering therapy has beneficial effects on these "high-risk" features of plaque morphology. The composite of data presented here supports the hypothesis that lipid-lowering therapy selectively depletes lipids from this relatively small but dangerous subgroup of fatty lesions, effectively stabilizing them.

Effect of iodinated contrast media on neutrophil adhesion to cultured endothelial cells

PURPOSE

To investigate the influence of contrast media (CM) on endothelial cells (ECs) with respect to cytotoxicity and to neutrophil adhesion.

MATERIALS AND METHODS

Human umbilical vein ECs were incubated with chromium-51-labeled human neutrophils in the presence of CM (diatrizoate, ioxaglate, iopamidol, and iodixanol) in three concentrations: 2, 20, and 50 mg I/mL. CM was compared with glucose solutions prepared from plain, buffered glucose solutions, iso-osmolar to the corresponding CM solution. Neutrophil adhesion to the EC monolayer, EC morphology, and cytotoxicity were evaluated.

RESULTS

The effect of CM on neutrophil adhesion was dependent on dose, with increased adhesion at low CM concentrations (2 and 20 mg I/mL) and decreased adhesion at high CM concentration (50 mg I/mL). The response was observed only if ECs and neutrophils were exposed to CM simultaneously in a shared environment. Glucose solutions with the same osmolarity did not show similar effect. Both diatrizoate and ioxaglate had a greater cytotoxic effect on ECs and neutrophils than did iodixanol and iopamidol.

CONCLUSION

The altered neutrophil adhesion to ECs may be due to CM-induced cytotoxicity or CM-induced EC activation because the glucose solutions did not cause a similar change at equal osmolality. The lack of cell death, combined with altered neutrophil adhesion implies modulation of cell adhesion molecules by CM. The results could be pertinent to the pathogenesis of peripheral vascular lesions and the endothelial response in immunosuppressed or septic patients receiving CM during imaging studies.

Effects of omega-3 fatty acids and/or antioxidants on endothelial cell markers

BACKGROUND

Increased expression of cell adhesion molecules and increased procoagulant activity of the vascular endothelium have been postulated to characterize dysfunctional endothelium. The cellular effects of n-3 fatty acids (n-3 FAs) and antioxidants are still not clarified.

METHODS

In a randomized, factorial two-by-two design study, we have investigated 41 male smokers with hyperlipidaemia before and after 6 weeks of supplementation with either n-3 FAs (4.8 g daily) or placebo with the addition of antioxidants (150 mg of vitamin C, 75 mg of vitamin E and 15 mg of beta-carotene daily) or placebo with regard to the effects on some endothelial cell markers: thrombomodulin (sTM), von Willebrand factor (vWF), tissue plasminogen activator antigen (tPAag) and soluble forms of the cell adhesion molecules E-selectin, P-selectin and vascular cell adhesion molecule 1 (VCAM-1).

RESULTS

In the n-3 FA group, significant reductions in the plasma levels of vWF (P = 0.034) and sTM (P < 0.001) were demonstrated compared with placebo, whereas increased levels were found for E-selectin (P = 0.001) and VCAM-1 (P = 0.010). In the antioxidant group, no differences in changes were noted for any of the variables.

CONCLUSION

The reduction in the levels of sTM and vWF with n-3 FA supplementation could indicate an improvement with regard to the haemostatic markers of endothelial dysfunction, whereas the simultaneous increase in the soluble forms of E-selectin and VCAM-1 may suggest an adverse effect on the inflammatory system. The antioxidants seem to be neutral in their effect on these endothelial cell markers in our study population of smokers. The interpretation of the soluble forms of these molecules are, however, still debatable.

Double filtration plasmapheresis maintains normal adhesion molecule levels

Levels of plasma soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), and von Willebrand factor (vWF) increase in patients with peripheral vascular or ischemic heart disease. These factors are related to the progression of atherosclerosis. Furthermore, these substances and thrombomodulin (TM) are indicators for assessing the degree of damage to the endothelium. To evaluate the effect of double filtration plasmapheresis (DFPP) on these molecules, the plasma levels of vWF, sICAM-1, sVCAM-1, and TM were measured in 4 familial hypercholesterolemia (FH) patients who underwent treatment with DFPP at 2 week intervals for more than 3 years. The levels of sVCAM-1 and sICAM-1 in hypercholesterolemia patients with ischemic heart disease as a control was 773 +/- 109 and 334 +/- 82 ng/ml. These values were higher than the normal value. In the FH patients who underwent DFPP treatment, the average sICAM-1 levels were 221 +/- 47 and 197 +/- 36 ng/ml before and after, respectively. The average sVCAM-1 levels were 601 +/- 87 and 486 +/- 60 ng/ml. There were no significant differences between the pre- and post-DFPP values. The activities of plasma vWF before and after DFPP treatment were 158 +/- 23 and 45 +/- 9%. The levels of plasma TM before and after treatment were 3.0 +/- 0.3 and 3.4 +/- 0.5 FU/ml. From these results, it is suggested that DFPP treatment does not damage the endothelium and may prevent the progression of atherosclerosis by removing the substances that induce the production of sICAM-1 and sVCAM-1 due to long-term treatment.

Plasma concentration of soluble intercellular adhesion molecule 1 and risks of future myocardial infarction in apparently healthy men

BACKGROUND

The intercellular adhesion molecule ICAM-1 mediates adhesion and transmigration of leucocytes to the vascular endothelial wall, a step proposed to be critical in the initiation and progression of atherosclerosis. Whether concentrations of soluble ICAM-1 (sICAM-1) are raised in apparently healthy individuals who later suffer acute myocardial infarction is unknown.

METHODS

We obtained baseline plasma samples from a prospective cohort of 14,916 healthy men enrolled in the Physicians' Health Study. With a nested case-control design, we measured sICAM-1 concentrations for 474 participants who developed a first myocardial infarction, and 474 controls (participants who remained healthy throughout the 9-year follow-up). Cases were matched to controls according to age and smoking status at the time of myocardial infarction.

FINDINGS

We found a significant association between increasing concentration of sICAM-1 and risk of future myocardial infarction (p = 0.003), especially among participants with baseline sICAM-1 concentrations in the highest quartile (> 260 ng/mL; relative risk 1.6 [95% Cl 1.1-2.4], p = 0.02). This association was present overall as well as among non-smokers, and persisted after control for lipid and non-lipid risk factors. In multivariate analyses, the risk of future myocardial infarction was 80% higher for participants with baseline sICAM-1 concentrations in the highest quartile (relative risk 1.8 [1.1-2.8], p = 0.02). Similar risk estimates were seen among non-smokers. We found slight but significant correlations between sICAM-1 and fibrinogen, high-density-lipoprotein cholesterol, homocysteine, triglycerides, tissue-type plasminogen-activator antigen, and C-relative protein, but adjustment for these altered the risk little. The risk of myocardial infarction associated with raised concentrations of sICAM-1 seemed to increase with length of follow-up.

INTERPRETATION

Our data support the hypothesis that cellular mediators of inflammation have a role in atherogenesis and provide a clinical basis to consider antiadhesion therapies as a novel means of cardiovascular disease prevention.

Neovascularization in atherectomy specimens from patients with unstable angina: implications for pathogenesis of unstable angina

Although neovascularization has been noted in atherosclerotic plaque, the presence of neovascularization has not been correlated with clinical syndromes. This study examined the relation between neovascularization in atherosclerotic plaque removed during directional coronary atherectomy and clinical status in 28 patients. Neovascularization was determined by immunohistochemistry with endothelial cell-specific monoclonal antibodies and was found in nine (50%) of 18 specimens from patients with unstable angina and in only one (10%) of 10 specimens from patients with stable angina (p < 0.05). There was no significant relation between neovascularization and other clinical factors (age, sex, race, hypertension, diabetes, tobacco use, hypercholesterolemia, positive family history of coronary artery disease, history of myocardial infarction, or stenosis severity). These results suggest that neovoscularization may play a role in the pathogenesis of unstable angina.

Effects of hormone therapy on inflammatory cell adhesion molecules in postmenopausal healthy women

To investigate the effect of estrogen with antioxidant potential on soluble markers of chronic vascular inflammation, we administered either transdermal 17beta-estradiol 0.1 mg/day (9 women) or 17beta-estradiol 0.1 mg and medroxyprogesterone acetate 2.5 mg/day (11 women) for 1-month treatment in a randomized design, with measurement of cell adhesion molecules. Hormone therapy significantly lowered intercellular adhesion molecules-1 levels by 8% (p = 0.009) and tended to lower E-selectin levels (by 6%, p = 0.096), and VCAM-1 levels (by 4%, p = 0.084).