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Separate reports have identified differences in plasma levels of the endothelial markers soluble E-selectin, von Willebrand factor (vWf) and soluble thrombomodulin in each of the major modifiable risk factors for atherosclerosis (smoking, hypertension and hypercholesterolaemia), and abnormal levels of some plasma markers predict various adverse cardiovascular events. However, it is unclear whether there is an increasing effect on the endothelium with a worsening risk-factor profile. We measured the three endothelial cell markers by enzyme-linked immunosorbent assay in the plasma of 200 subjects (mean age, 54 years; 58% men) free of the symptoms and clinical signs of atherosclerosis. Levels of the markers were then correlated with the Framingham coronary heart disease (CHD) and cerebrovascular disease (CVD) scores to help determine which (if any) may be useful as good laboratory predictors of future cardiovascular events in prospective epidemiological studies. vWf correlated with CHD (r(s) = 0.269, < 0.001) and CVD risk (r(s) = 0.331, P < 0.001), but soluble E-selectin correlated only with CHD risk (r(s) = 0.163, P = 0.021). We conclude that, of the three specific endothelial markers, vWf correlates most closely with the Framingham risk-factor prediction scores and therefore may be the better plasma endothelial marker of the future development of an atherothrombotic event.

Increased levels of the endothelial markers von Willebrand factor and soluble thrombomodulin have been identified as predictors of the development of adverse cardiovascular events. The purpose of this study was to determine which of these markers is the best predictor of such events. Both markers were measured using enzyme-linked immunosorbent assays in 111 subjects at high risk of cardiovascular disease (50 with peripheral atherosclerosis and 66 who had suffered myocardial infarction). After a mean of 46 months, a follow-up investigation was performed and cardiovascular end-points (myocardial infarction, stroke, measured progression of peripheral atherosclerosis, arterial surgery, etc.) were noted. Multivariate analysis revealed that both markers were independent predictors among the 54 subjects who suffered any one of the cardiovascular end-points (P < 0.01). However, only an increased level of von Willebrand factor predicted the outcome among the 39 subjects who suffered a myocardial infarction, stroke or arterial surgery (P < 0.05). We conclude that von Willebrand factor is a marginally better predictor of cardiovascular events than soluble thrombomodulin.

Development of an abdominal aortic aneurysm (AAA) may be a product of generalised atherosclerosis. If that is indeed the case, we would expect similarities in various risk factors and other markers in common with occlusive peripheral arterial disease (peripheral arterial disease), and less congruity with healthy controls. To test this hypothesis, we recorded the major risk factors for atherosclerosis, two markers of endothelial dysfunction, and soluble adhesion molecules in 21 patients with an uncomplicated AAA free of symptomatic peripheral arterial disease, 42 patients with peripheral arterial disease, and 42 healthy controls who were matched, as a group, for age and sex. After adjusting for smoking, there were no significant differences in blood pressure, fibrinogen, soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1 or lipoproteins between the groups. However, markers of endothelial integrity von Willebrand factor and soluble thrombomodulin were both higher (P < 0.05) only in peripheral arterial disease patients. Relative to the controls, platelet marker soluble P-selectin was increased in AAA (P < 0.01) and in the peripheral arterial disease patients (P < 0.05). Levels were higher in AAA patients than in peripheral arterial disease patients (P < 0.05). Our laboratory data suggest that the pathophysiology AAA and peripheral arterial disease are not identical.

von Willebrand factor antigen II (vWFAgII) is the 100 kDa propolypeptide of endothelial cell marker von Willebrand factor (vWF). Our aim was to determine the relationship between vWFAgII and mature vWF and an additional endothelial cell marker, soluble thrombomodulin, in atherosclerosis. To do this, we measured levels of all three by enzyme-linked immunosorbent assay in plasma obtained from 24 patients with peripheral vascular disease (PVD), from 25 patients who survived a myocardial infarction [i.e. had ischaemic heart disease (IHD)], and from 47 age- and sex-matched controls. We found raised levels of vWFAgII in PVD (57.3 +/- 15.3 microg/dl; mean +/- standard deviation) and in IHD (53.4 +/- 19.2 microg/dl) compared with the controls (35.7 +/- 12.0 microg/dl; analysis of variance P < 0.001). Raised levels of vWf were found in both groups of patients but raised soluble thrombomodulin was found only in patients with PVD. Levels of vWFAgII correlated with those of vWf (r = 0.45, P < 0.001) but not with soluble thrombomodulin (r = 0.14, P = 0.17), nor any of the major risk factors for atherosclerosis. Our brief study reports raised levels of vWFAgII in atherosclerosis. This may, like that of vWf, be related to endothelial cell damage, although the incomplete correlation between the two implies different metabolic and/or release mechanisms.

Cell surface adhesion molecule expression is likely to be important in inflammation, atherosclerosis and cancer, and soluble forms of many of these molecules are present in plasma. We measured levels of the soluble form of platelet endothelial cell adhesion molecule-1 (sPECAM) by ELISA in the serum of 77 patients with frank atherosclerosis, 69 patients with inflammatory connective tissue disease, and 39 patients with cancer. Each group of patients was controlled by an equal number of age- and sex-matched healthy subjects. There was no difference between sPECAM in patients with atherosclerosis and their matched controls or between patients with connective tissue disease and their controls. However, sPECAM levels were lower (16.6 +/- 5.0 ng/ml, mean +/- SD) in patients with cancer than in their controls (21.1 +/- 4.4 ng/ml, P < 0.001). No differences were found in sPECAM levels between the major subgroups of each type of disease, or as a result of factors such as age, sex or smoking in the controls. In contrast to levels of many other soluble adhesion molecules, levels of sPECAM are not altered in inflammatory or atherosclerotic vascular disease and therefore appear to have little relevance in these conditions. However, there may be significant differences in sPECAM levels in patients with low levels in cancer. Additional investigations are therefore justified.

Increased soluble P-selectin has been described in atherosclerosis, but the mechanisms for this and its clinical significance are unknown. In an attempt to clarify these points we measured soluble P-selectin and von Willebrand factor, an endothelial cell marker, by ELISA in 116 patients who had survived a myocardial infarction and in 116 matched controls. Raised levels of both soluble P-selectin (median 272 ng/ml, range 55-850 ng/ml vs 190 ng/ml, range 40-395 ng/ml) and von Willebrand factor (mean +/- SD 128 +/- 37 IU/dl vs 100 +/- 33 IU/dl; both P < 0.001) failed to correlate (r = 0.12), and soluble P-selectin failed to correlate with any of the major risk factors for atherosclerosis. A four-year follow-up of 68 of these patients revealed that soluble P-selectin was higher in the 33 (48%) who had suffered an additional cardiovascular event (e.g. subsequent myocardial infarction, arterial surgery; median 350 ng/ml, range 275-460 ng/ml) compared with those free of an end-point (270 ng/ml, range 140-400 ng/ml, P = 0.0012). We conclude that increased soluble P-selectin is unrelated to the risk factors for atherosclerosis but is a new marker of disease progression in patients who have survived a myocardial infarction.

Soluble P-selectin (CD62P) may arise from platelets, the endothelium, or both, and raised levels are found in those with thrombotic disease and atherosclerosis. To determine whether these increased levels in atherosclerosis are related to hypercholesterolaemia, blood samples were obtained from 86 patients (43 with symptomatic vascular disease) attending a hypercholesterolaemia clinic, and 86 age- and sex-matched controls. Parallel measurement of endothelial cell product von Willebrand factor helped define the origin of sP-selectin. Using ELISAs, soluble P-selectin was higher (median 290 ng/ml, range 80-735, P < 0.05) in patients with vascular disease than in both patients with uncomplicated hypercholesterolaemia (median 210 ng/ml, range 55-550), and controls (median 190 ng/ml, range 48-500). Von Willebrand factor was raised in both patients with uncomplicated hypercholesterolaemia (115 +/- 26 IU/dl, P < 0.05) and patients with hypercholesterolaemia and vascular disease (129 +/- 32 IU/dl, P < 0.02) compared with controls (102 +/- 30 IU/dl). Levels of soluble P-selectin did not correlate with von Willebrand factor, total low-density-lipoprotein (LDL) or high-density-lipoprotein (HDL) cholesterol or triglycerides levels, blood pressure or smoking, but von Willebrand factor correlated with LDL cholesterol (r = 0.42, P < 0.05). We conclude that plasma lipoproteins are not a major influence on levels of soluble P-selectin.

Circulating levels of the adhesion molecule P-selectin (CD62P) are increased in the plasma of patients with atherosclerosis, but its relationship to the anatomical location of symptomatic disease or extent of symptomatic disease is unknown. The influence of the risk factors for atherosclerosis on soluble P-selectin is also unclear. To clarify these questions we analysed plasma samples from 170 patients with symptomatic peripheral vascular disease and 119 asymptomatic controls who were, as a group, age- and sex-matched. Soluble P-selectin (ELISA) was increased in 83 patients with symptomatic disease of the iliac and/or femoral arteries alone (P < 0.05, ANOVA) but not in 37 patients with symptomatic carotid artery disease alone compared with controls. Soluble P-selectin was equally raised in 120 patients with disease at one arterial site and in 50 patients with disease at two or more arterial sites (both P < 0.05) compared with controls. Smoking and atherosclerosis were both independent predictors of raised soluble P-selectin. We conclude that increased soluble P-selectin may have value as a marker of peripheral vascular disease of the iliac and/or femoral arteries in group comparisons only, as the poor discrimination and wide variation of data make comparisons at the individual level difficult.