Delay of neutrophil apoptosis in acute coronary syndromes.

Apoptosis of polymorphonuclear neutrophils (PMN) is currently discussed as a key event in the control of inflammation. This study determined PMN apoptosis and its underlying mechanisms in controls (C), patients with stable (SAP) or unstable angina (UAP), and with acute myocardial infarction (AMI). Blood was drawn from 15 subjects of each C, SAP, UAP, and AMI. Apoptosis was measured by flow cytometry in isolated PMN (propidium iodide staining) and PMN from whole blood (CD16, FcgammaRIII). Serum cytokines were determined by enzyme-linked immunosorbent assay. Apoptosis of isolated PMN was delayed significantly in acute coronary syndromes (ACS) as compared with SAP or C (C, 51.2+/-12.6%; SAP, 44.9+/-13.6%; UAP, 28.4+/-10.1%; AMI, 20.3+/-8.5%; AMI or UAP vs. SAP or C, P<0.001). These results were confirmed by measurement of PMN apoptosis in cultured whole blood from patients and controls. Moreover, serum of patients with ACS markedly reduced apoptosis of PMN from healthy donors. Analysis of patients' sera revealed significantly elevated concentrations of tumor necrosis factor alpha, interferon-gamma (IFN-gamma), granulocyte macrophage-colony stimulating factor (GM-CSF), and interleukin (IL)-1beta in ACS (vs. C and SAP). IFN-gamma, GM-CSF, and IL-1beta significantly delayed PMN apoptosis in vitro. Furthermore, coincubation of PMN with adenosine 5'-diphosphate-activated platelets significantly inhibited PMN apoptosis as compared with coculture with unstimulated platelets. This study demonstrates a pronounced delay of PMN apoptosis in UAP and AMI, which may result from increased serum levels of IFN-gamma, GM-CSF, and IL-1beta and from enhanced platelet activation. Therapeutical modulation of these determinants of PMN lifespan may provide a new concept for the control of inflammation in ACS.

Upregulation of CD40-CD40 ligand (CD154) in patients with acute cerebral ischemia.

BACKGROUND AND PURPOSE: Inflammation and hypercoagulability contribute to the development of acute cerebral ischemia. Both can be mediated by the CD40 system. This study investigated whether the CD40 system and related mediators are upregulated in patients with transient ischemic attack (TIA) or stroke. METHODS: Seventeen patients with TIA, 60 patients with complete stroke, and 15 control subjects were investigated. CD154 and P-selectin were analyzed on platelets and CD40 on monocytes during and 3 months after acute cerebral ischemia by double-label flow cytometry. Blood concentrations of soluble CD154 and monocyte chemoattractant protein-1 (MCP-1) were evaluated. RESULTS: Our main findings are as follows: (1) patients with acute cerebral ischemia showed a significant increase of CD154 on platelets and CD40 on monocytes compared with controls; (2) plasma levels of soluble CD154 were significantly higher in these patients; (3) these patients had significantly higher numbers of prothrombotic platelet-monocyte aggregates; (4) the chemoattractant MCP-1 was significantly elevated in cerebral ischemia; and (5) at 3 months' follow-up, upregulation of CD154 still persisted in patients with previous acute cerebral ischemia. CONCLUSIONS: Patients with acute cerebral ischemia show upregulation of the CD40 system, which might contribute to the known proinflammatory, proatherogenic, and prothrombotic milieu found in these patients.

Upregulation of CD40 and CD40 ligand (CD154) in patients with moderate hypercholesterolemia.

BACKGROUND: Hypercholesterolemia, a risk factor for cardiovascular disease, is associated with inflammation and hypercoagulability. Both can be mediated by the CD40 system. This study investigated whether the CD40 system is upregulated in patients with moderate hypercholesterolemia and whether it is influenced by therapy with a hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor. METHODS AND RESULTS: Fifteen patients with moderate hypercholesterolemia and 15 healthy control subjects were investigated. CD154 and P-selectin were analyzed on platelets and CD40 was analyzed on monocytes before and under therapy with the statin cerivastatin by double-label flow cytometry. Blood concentrations of soluble CD154 and monocyte chemoattractant protein-1 (MCP-1) were evaluated. Our main findings were as follows. Patients with moderate hypercholesterolemia showed a significant increase of CD154 and P-selectin on platelets and CD40 on monocytes compared with healthy subjects. Soluble CD154 showed a nonsignificant trend for higher plasma levels in patients. A positive correlation was found for total or LDL cholesterol and CD154, but not for CD40 on monocytes. The latter was upregulated in vitro by C-reactive protein, which was found to be significantly elevated in patients with moderate hypercholesterolemia. CD154 on platelets proved to be biologically active because it enhanced the release of MCP-1, which was markedly elevated in an in vitro platelet-endothelial cell coculture model and in the serum of patients. Short-term therapy with a HMG-CoA reductase inhibitor significantly downregulated CD40 on monocytes and serum levels of MCP-1. CONCLUSION: Patients with moderate hypercholesterolemia show upregulation of the CD40 system, which may contribute to the known proinflammatory, proatherogenic, and prothrombotic milieu found in these patients.

Patients with acute coronary syndromes express enhanced CD40 ligand/CD154 on platelets.

OBJECTIVE: To investigate whether CD40L/CD154 on platelets and soluble CD40L/CD154 may play a role in the inflammatory process of acute coronary syndromes. DESIGN AND SETTING: Observational study in a university hospital. PATIENTS: 15 patients with acute myocardial infarction, 25 patients with unstable angina, 15 patients with stable angina, and 12 controls. MAIN OUTCOME MEASURES: CD40L/CD154 on platelets, P-selectin/CD62P on platelets, soluble CD40L/CD154 serum concentrations. RESULTS: Mean (SD) CD40L/CD154 expression on platelets was 6.2 (2.8) MFI (mean fluorescence intensity) in the infarct group, 11 (3.3) MFI in the unstable angina group (p < 0.001 v infarction), 3.6 (0.9) MFI in the stable angina group (p < 0.01 v infarction; p < 0.001 v unstable angina), and 3.2 (1.0) MFI in the controls (p < 0.01 v infarction; p < 0.001 v unstable angina; NS v stable angina). Soluble CD40L/CD154 concentration was 5.2 (1.1) ng/ml in the infarct group, 4.2 (0.7) ng/ml in the unstable angina group (p < 0.001 v infarction), 2.9 (1.0) ng/ml in stable angina group (p < 0.001 v infarction and unstable angina), and 3.0 (0.5) ng/ml in the controls (p < 0.001 v infarction and unstable angina; NS v stable angina). At a six months follow up, there was lower expression of CD40L/CD154 on platelets in patients with unstable angina (12.3 (3.6) v 3.8 (1.2) MFI, p < 0.0001) and acute myocardial infarction (6.2 (2.8) v 3.5 (0.8) MFI, p < 0.01) compared with their admission values six months earlier. Patients with unstable angina who needed redo coronary angioplasty (PTCA) or who had recurrence of angina were characterised by increased CD40L/CD154 expression on platelets compared with the remainder of the study group (recurrence of angina: 12.7 (3.2) v 9.7 (1.6) MFI, p < 0.05; re-do PTCA: 14.3 (4.2) v 10.3 (2.1) MFI, p < 0.05). CONCLUSIONS: Both CD40L/CD154 on platelets and soluble CD40L/CD154 are raised in patients with unstable angina and myocardial infarction. These findings suggest that CD40-CD40L/CD154 interactions may play a pathogenic role in triggering and propagation of acute coronary syndromes.

Monocytes coexpress endothelial and macrophagocytic lineage markers and form cord-like structures in Matrigel under angiogenic conditions.

OBJECTIVES: It has been shown that circulating human non-adherent CD34+ cells coexpressing vascular endothelial growth factor (VEGF)-R2 and AC133 have the capacity to differentiate into adherent mature endothelial cells. However, prior studies have demonstrated that a much bigger subset of primary adherent mononuclear cells can also form endothelial progenitor cells (EPC). To determine the origin of the latter cell population we tested the hypothesis: do monocytes as a firmly adherent and plastic cell type have the potential to differentiate into an endothelial phenotype. METHODS: CD34-/CD14+ monocytes were isolated from human peripheral blood by adherence separation and magnetic bead selection (purity >90%) and cultured on fibronectin-coated plastic dishes (medium containing VEGF 10 ng/ml, basic fibroblast growth factor (bFGF) 2 ng/ml, insulin like growth factor (IGF-1) 1 ng/ml, 20% fetal calf serum). RESULTS: After 2 weeks of culture, using fluorescence activated cell analysis we observed a new expression of the endothelial markers von Willebrand factor (vWf), VE-cadherin (VE) and ec-NOS in 45.2, 12.4 and 9.8% of the cells, respectively. The proportion of cells expressing these markers further increased after 4 weeks (94.2, 89.7 and 58.8% of these cells, respectively). The proportion of CD45 expressing cells remained unchanged during this period. However, after 14 days the specific macrophage antigen CD68 was newly expressed in 62% of the analysed cells with a further increase to 90% after 28 days of culture. In three-dimensional gel (Matrigel the formation of cord- and tubular-like structures was observed. CONCLUSION: The present data indicate that under angiogenic stimulation macrophages develop an endothelial phenotype with expression of specific surface markers and even form cord- and tubular-like structures in vitro suggesting that this cell population may be recruited for vasculogenesis.

Role of intracellular calcium in the regulation of phospholipase A2 in fMet-Leu-Phe-challenged human polymorph neutrophils.

In the present study, we have shown that the protein kinase C (PKC) inhibition by staurosporine augmented fMet-Leu-Phe-(FMLP)-induced arachidonic acid (AA) release in human polymorph neutrophils (PMN). This effect is in contradiction to a recently reported mechanism that besides Ca2+, the phosphorylation of cytosolic phospholipase A2 (cPLA2) is essential for the enzyme activation. In addition, we found that staurosporine elevated the basal concentration of intracellular Ca2+, although initial Ca2+ release was not affected. Since thapsigargin, a blocker of endogenous Ca2+ ATPase, also increased AA release dose-dependently, we believe that the elevation of intracellular Ca2+ is the most essential step and not the phosphorylation of enzyme for the activation of cPLA2.

Thromboxane A2 analogue U 46619 enhances tumour cell proliferation in HeLa cells via specific receptors which are apparently distinct from TXA2 receptors on human platelets.

In this study, we have demonstrated for the first time by using U 46619, a stable analogue of thromboxane A2 (TXA2), that TXA2 exerts a cell proliferative effect on HeLa cells which is mediated by specific TXA2 receptors, inasmuch as the cell proliferation could be dose-dependently suppressed by TXA2 receptor antagonist BM 13177. The investigation of the phospholipase C pathway by U 46619 and prostaglandin H2 (PGH2) in the presence and absence of BM 13177 in cells with or without pertussis toxin pretreatment, as well as radioligand receptor binding studies, revealed that, in contrast to TXA2 receptors on human platelets, where TXA2 and PGH2 share the same receptor binding sites, HeLa cells possess distinct receptors for TXA2 and PGH2.

Clinical significance of prostacyclin and thromboxane in cancer of the female breast and genital tract.

Studies investigating the role of thromboxane A2 and prostacyclin in cancer of the female breast and genital tract are reviewed. Whereas thromboxane A2 was found to promote the tumour growth and metastasis, prostacyclin exerted a protective effect in maintaining vascular and platelet homeostasis. Thus, monitoring of prostacyclin and thromboxane levels in plasma and urine of cancer patients may be essential for the evaluation of tumour growth and metastasis. Of all modulators of thromboxane and prostacyclin biosynthesis, nafazatrom was found to exhibit promising results for the treatment of advanced breast cancer, although its use in the routine therapy is questionable at this stage.