Ethnic/racial differences in circulating markers of angiogenesis and their association with cardiovascular risk factors and cardiovascular disease.

OBJECTIVE: To determine (a) whether ethnic/racial differences exist in circulating markers of angiogenesis (Angiopoietin-1 (Ang-1), Angiopoietin-2 (Ang-2), soluble Tie-2 receptor (sTie-2) and Angiogenin) between South Asian (SA; from India, Pakistan and Bangladesh); Black African-Caribbean and White (W) ethnic groups, and (b) associations between these markers in stable cardiovascular disease (CVD) and its risk factors. PATIENTS AND METHODS: We recruited 243 subjects (82 SA, 84 Black and 77 W) with symptomatic and clinically confirmed CVD (n=108), risk factor controls (with ≥ 1 cardiovascular risk factor, e.g. smoking, diabetes mellitus, dyslipidaemia, hypertension) and with ankle brachial pressure index >1) (n=64) and healthy controls free of CVD and risk factors (n=56). Angiogenic markers were measured by enzyme linked immunoassay. RESULTS: In healthy controls, angiogenin was higher in SA and Black subjects, compared to Whites (p<0.05). sTie-2 correlated inversely with angiogenin (p=0.001), was higher in women (p=0.029) and was lower in smokers (p=0.007). Overall, age (p=0.001) was the only independent factor associated with angiopoietin-1. Angiogenin (p=0.01) and SBP (p=0.014) were both independently higher in the Black group compared to the White group. CONCLUSIONS: Ethnic, racial, and demographic differences are evident in certain circulating markers of angiogenesis. With the exception of an effect of smoking on sTie-2, these differences are not influenced by the presence of other risk factors, nor the presence of stable cardiovascular disease.

No effect of clopidogrel activity or cessation on vascular function or markers of inflammation.

The platelet adenosine diphosphate (ADP)-receptor blocker clopidogrel is effective in reducing the rate of thrombosis in cardiovascular disease, but may also have nonplatelet activity. However, there is variability in the suppression of platelet function in individuals, leading to the concept of clopidogrel resistance, that is, reduced platelet-suppressing activity. We tested the hypothesis that some of the beneficial effect of clopidogrel may be due to the variable activity of this drug on the vascular system (assessed by plasma markers von Willebrand factor and soluble E-selectin, and functional arterial pulse wave velocity) and inflammation (C-reactive protein and interleukin-6) while 32 patients with coronary artery disease taking 75 mg clopidogrel daily, and again 2 weeks after cessation of clopidogrel therapy. Platelet responsiveness to clopidogrel was assessed by the phosphorylation of intracellular regulatory protein-vasodilator-stimulated phosphoprotein method and aggregometry to ADP. Response to aspirin was assessed using arachidonic acid (AA), and soluble P-selectin and PAC-1 were also measured. While on clopidogrel, there were no relationships between any vascular or inflammatory index and the response to clopidogrel. After stopping clopidogrel, there were no differences in platelet aggregation to AA, or the expression of P-selectin or PAC-1 at rest, or after stimulation by AA, but platelet responses to ADP all increased (p < 0.01). Although soluble P-selectin increased when clopidogrel was stopped (p = 0.006), there were no changes in plasma markers or vascular function. We conclude that 75 mg/day clopidogrel has no effect of markers of vascular function or inflammation.

Endothelial progenitor cells and circulating endothelial cells in early prostate cancer: a comparison with plasma vascular markers.

BACKGROUND: Separate studies indicate that endothelial perturbation, as demonstrated by abnormal endothelial progenitor cells (EPCs), circulating endothelial cells (CECs), and plasma markers such as von Willebrand factor (vWf) and soluble E selectin (sEsel) are present in cancer. However, there are no reports where these indices are compared. Accordingly, we hypothesized altered EPCs and CECs in prostate cancer that would correlate with vWf, sEsel, and prostate specific antigen (PSA). METHODS: We recruited 29 men with biopsy proven prostate cancer, with 25 with benign prostate disease and 27 free of prostate disease. CECs were defined on flow cytometry as being CD34+, CD146+, CD45-, and CD309-, EPCs were similarly defined as being CD34+, CD309+,CD45-, and CD146-. vWf, sEsel, and PSA were measured by immunoassay. RESULTS: Despite higher PSA, sE-sel, and vWf in prostate cancer (all P < 0.02), neither EPCs, CECs, nor their ratio, were significantly different. EPCs and CECs correlated significantly with each other in each group (r > 0.48, P < 0.01) but failed to correlate with any plasma marker. CONCLUSION: Unlike plasma endothelial markers, CECs and EPCs may play little part in the pathophysiology of early prostate cancer.

Plasma haemoxygenase-1 in coronary artery disease. A comparison with angiogenin, matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1 and vascular endothelial growth factor.

It was the aim of this study to determine plasma haemoxygenase-1 (HO-1) across the spectrum of health, angina but normal coronary arteries (NCA), stable coronary artery disease (CAD), and acute coronary syndromes (ACS), and relationships with angiogenin, matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-1, and vascular endothelial growth factor. Plasma markers were measured (ELISA) in peripheral venous citrated plasma from 50 healthy subjects, 30 with NCA, 70 with stable CAD and 24 with an ACS, and from patient's aortic root, coronary ostium, coronary sinus and femoral artery. Human umbilical vein endothelial cells (HUVECs) were cultured with or without tumour necrosis factor (TNF), and platelets were probed. HO-1 was raised in stable CAD (p<0.05) and increased further in ACS (p<0.01) compared to healthy controls and NCA. HO-1 correlated only with MMP-9, and then only in the healthy controls. There were no major differences from cardiac or peripheral sites. HO-1 was present in HUVECs and 24-hour HUVEC supernatants but release was abolished by TNF. Platelets had no HO-1. In conclusion, HO-1 is raised in stable CAD and ACS and may arise from the endothelium but not the platelet. This may have implications for our understanding of the pathophysiology of CAD and its acute presentation as ACS.

Characterisation and validity of inflammatory biomarkers in the prediction of post-operative atrial fibrillation in coronary artery disease patients.

Atrial fibrillation (AF) is a common complication of coronary artery bypass grafting (CABG). We sought to determine the diagnostic validity of plasma biomarkers of i) inflammation (marked by interleukin-6 [IL-6] and high-sensitivity C-reactive protein [hs-CRP]), ii) extracellular matrix remodelling (matrix metalloproteinase [MMP-9], tissue inhibitor of matrix metalloproteinase [TIMP-1]) and iii) the prothrombotic state (tissue factor and von Willebrand factor [vWF]) in the risk prediction of post-operative AF. Samples were obtained preoperatively from peripheral/femoral vein and from intracardiac chambers (right atrium [RA], the right atrial appendage [RAA], the left atrium [LA] and the left atrial appendage [LAA]) amongst 100 consecutive patients free of AF and inflammatory disease undergoing elective CABG. Biomarker concentrations were related to incident AF (30 days). At 30 days post CABG, 30 patients were proven to have had AF. Concentrations of tissue factor (TF) and vWF were unrelated to postoperative AF. Peripheral (p=0.018), and intracardiac levels (RAA (p=0.029) and LA (p=0.026)) of hs-CRP were associated with the presence of AF after CABG. Intracardiac levels of IL-6 in samples from the RAA (p=0.031), LA (p=0.042) and LAA (p=0.006), and MMP-9 in the LAA sample were also associated with AF (p=0.007). Our data suggest that an intra-cardiac inflammatory environment that is manifest peri-operatively may predispose to the development of post-operative AF. This intracardiac inflammatory state was reflected by increased peripheral hs-CRP levels. These differences may indicate local substrate abnormalities contributing to the development of AF post-operatively.

The effects of coronary artery disease severity on time-dependent changes in platelet activation indices in stored whole blood.

BACKGROUND: Platelets play a pivotal role in the pathogenesis of the thrombotic complications in cardiovascular disease (CVD). Abnormal platelet activation indices are evolving as potentially useful markers in CVD risk stratification. Whilst there has been some investigation into the effects of storage time on several of these indices, the effects of underlying disease severity on these temporal changes have not been previously studied. METHODS: Using the ADVIA 120 haematology analyser, we assessed the effects of time-dependent storage of whole blood in EDTA, on a number of platelet activation indices: mean platelet volume (MPV), mean platelet component (MPC, measure of platelet density) and platelet component distribution width (PCDW, a marker of platelet shape change. We studied three age- and sex-matched patient groups: (i) healthy controls (n = 10), (ii) stable patients with coronary artery disease (CAD, n = 9); and (iii) patients with acute myocardial infarction (n = 8). Whole blood samples were processed at exactly 5 min following venesection and at 15, 30, 60 and 120 min later in storage in EDTA tubes at room temperature. RESULTS: There was a significant and stepwise increase in MPV (P = 0.01) and decrease in PCDW (P = 0.03), with a non-significant trend to increasing MPM and decreasing MPC with increasing underlying disease (that is healthy, 'stable' and 'acute' artery disease). There was a significant time-dependent increase in MPV and decrease in MPC and PCDW (all P < 0.05), which were all significant on 'post-hoc' analyses by 30 min. There were no significant changes in platelet count or MPM with time. There was no interaction of underlying disease with whole-blood storage time for any of the platelet indices reported (P = NS). CONCLUSION: There is a temporal increase in MPV and decrease in MPC and PCDW in venous blood stored over 2 h in EDTA. These changes are not influenced by the underlying CVD disease severity.

The effects of exercise stress testing on soluble E-selectin, von Willebrand factor, and circulating endothelial cells as indices of endothelial damage/dysfunction.

BACKGROUND: The quantification of circulating endothelial cells (CECs) in whole blood is an increasingly recognized index of endothelial damage/dysfunction. Abnormal CECs have been linked to the severity of coronary artery disease (CAD). OBJECTIVE: We assessed the relationship of CECs to other markers of endothelial dysfunction (von Willebrand factor (vWF) and soluble E-selectin (sEsel)) during exercise stress testing (EST) in a cohort of patients with suspected CAD. METHODS: We studied a cohort of patients referred to our chest pain clinic with a history of exertional chest pain. Treadmill EST was performed, using a full Bruce exercise protocol. Blood for CECs (immunobead method), vWF and sEsel (both ELISA) were collected immediately before (pre-exercise), immediately following exercise, and at 30 minutes post-EST. RESULTS: We studied 31 patients (84% male; mean (SD) age 58.4 (9.8) years). Of the entire cohort, 14 patients (45.2%) had a positive EST. Exercise led to significant increases in levels of CECs, sEsel, vWF, white blood cells (WBC), heart rate, mean and systolic blood pressure compared with base-line (all P < 0.05). There was a significant correlation between the change (delta (immediate post-pre-exercise)) in CECs and delta vWF (r = 0.45; 95% CI 0.11-0.69: P = 0.01) and delta sEsel (r = 0.41; 0.05-0.7: P = 0.02), as well as between delta vWF and delta sEsel (r = 0.55; 0.25-0.76: P = 0.001). Neither absolute nor delta CEC counts were predictive of exercise work-load/functional capacity, nor the presence of positive EST results. CONCLUSION: EST led to a significant increase in endothelial markers (CECs, vWF, and sEsel) compared with base-line levels. The rise in CECs correlated with the increases in other endothelial markers, but was not related to the either exercise workload/capacity or to the presence of a positive EST.

Effects of percutaneous coronary intervention on peripheral venous blood circulating endothelial cells and plasma indices of endothelial damage/dysfunction.

BACKGROUND: The relationship between endothelial damage/dysfunction and coronary artery disease is well recognized. However, the effects of percutaneous coronary intervention (PCI) [stenting/angioplasty] on circulating markers of endothelial damage/dysfunction (eg, von Willebrand factor [vWF], soluble E-selectin [sEsel] levels, and more recently circulating endothelial cells [CECs]) has been less well defined. AIMS AND METHODS: We investigated the effects of both diagnostic coronary angiography (CA) [n = 15; blood sampling immediately before CA and 15 min after CA] and PCI (n = 38; blood sampling before PCI, 15 min after PCI, and 24 h after PCI) on levels of CECs, vWF, and sEsel across comparable patient groups. We also included a cohort of comparable healthy control subjects in order to compare baseline levels of three endothelial markers. RESULTS: There were no differences in baseline levels of CECs, vWF, or sEsel between the three study groups (healthy control subjects, CA, PCI; all p = not significant). Following CA (before to 15 min after), there were no significant changes in vWF and CECs (p = not significant). Following PCI, there were significant increases observed at 15 min after PCI and at 24 h after PCI (when compared with pre-PCI levels) in CECs (p = 0.0006), vWF (p = 0.007), and sEsel (p = 0.024). CONCLUSION: We observed significant increases in three endothelial markers (CECs, vWF, and sEsel) with elective PCI but not CA. This is in keeping with endothelial damage/dysfunction following PCI.