Mental-stress-induced platelet activation among patients with coronary artery disease.

OBJECTIVE: To study patients with coronary artery disease (CAD) scheduled for coronary angioplasty and to examine platelet activation in response to mental stress as a potential mechanism involved in the association between psychosocial factors and cardiac outcomes. Psychosocial factors have been identified as risk factors for CAD and adverse cardiac outcomes, although the underlying mechanisms are poorly understood. METHODS: Markers of platelet activation and platelet reactivity in response to experimentally induced mental stress (mental arithmetic and anger recall) were examined, using flow cytometry analysis and beta-thromboglobulin (BTG) assays among 249 CAD patients (age = 60.3 +/- 9.0 years, 15% women) who were scheduled to undergo elective percutaneous coronary intervention. RESULTS: Mental stress-induced increases in platelet activation (CD41 (GP IIb/IIIa), p = .002; percent of mononuclear cells positive for CD41, p = .01; CD62P (P-selectin) expression, p = .005; and percent platelets positive for CD62P, p < .001). The degree of platelet reactivity was not related to demographic, clinical, or psychological variables, or cardiovascular hemodynamic changes. CONCLUSIONS: Experimentally induced mental stress induced platelet activation in patients with CAD. This mechanism may partially explain the link between psychosocial variables and the development of adverse cardiac outcomes in patients with CAD.

C-reactive protein modulates vagal heart rate control in patients with coronary artery disease.

Systemic inflammation is associated with sympathetic cardiac activation and decreased HRV (heart rate variability) in subjects at high risk of CAD (coronary artery disease). In the present study, we examined the influence of systemic inflammation, measured by CRP (C-reactive protein), on vagal HR (heart rate) control during behavioural relaxation in patients with CAD. It was hypothesized that CRP would be associated with decreased vagal HR modulation. Consecutive patients were screened 2 weeks prior to elective PTCA (percutaneous transluminal coronary angioplasty). The study was comprised of 29 subjects who represented the first and fourth quartiles of the CRP distribution: Low (0.47+/-0.07 microg/ml)- and High (8.19+/-1.95 microg/ml)-CRP groups respectively. Vagal HR control was quantified as RR high-frequency spectral power (0.15 to 0.40 Hz), and was assessed in log-transformed absolute units (logHF power). Near-IR particle immunoassay was used to determine high-sensitivity CRP concentration. Assessment entailed 5 min of silent reading and self-guided behavioural relaxation. RR logHF power was decreased in the High-CRP group across both assessment procedures (P=0.032). Behavioural relaxation increased RR logHF power for both the Low- and High-CRP groups (P=0.033). Hierarchical linear regression determined that CRP accounted for 18.9% of the variance in RR logHF power during behavioural relaxation (P=0.03), independent of baseline RR interval, cardiac medication, respiratory logHF power and body mass index. In conclusion, patients with CAD had augmented vagal HR control with behavioural relaxation, but this effect was moderated by the severity of CRP. Therefore it may be advisable to assess systemic inflammation in interventions aimed at improving neurocardiac regulation in patients with CAD.

Relationship of a comprehensive panel of plasma oxidized low-density lipoprotein markers to angiographic restenosis in patients undergoing percutaneous coronary intervention for stable angina.

BACKGROUND: This study was performed to assess the relationship between oxidized low-density lipoprotein (OxLDL) and restenosis. OxLDL induces up-regulation of inflammatory genes and cytokines and recruits monocytes to the vessel wall. Elevated levels of monocytes post-percutaneous coronary intervention (PCI) are associated with in-stent restenosis. METHODS AND RESULTS: One hundred forty-one patients with stable angina pectoris had serial blood samples drawn before PCI (68% balloon only, 32% stent), immediately post-PCI and at 6 and 24 hours, 3 days, 1 week, and 1, 3, and 6 months. Plasma levels of OxLDL-E06, a measure of oxidized phospholipid (OxPL) content on apoB-100 detected by antibody E06 (OxPL/apoB), autoantibodies to malondialdehyde-LDL and copper-oxidized LDL, and apoB-immune complexes were measured in all samples. Quantitative and qualitative coronary angiography was performed with 94% angiographic follow-up. Restenosis was defined as >50% diameter stenosis (%DS). The overall angiographic restenosis rate was 32% (39% in balloon group, 16% in stent group). OxPL/apoB levels rose significantly and OxLDL autoantibody titers decreased immediately post-PCI in patients both with and without restenosis, but there were no significant differences among groups. There was also no relationship of any OxLDL marker to lesion length, %DS, or minimal lumen diameter. No differences were noted in stent versus balloon-treated patients. CONCLUSIONS: Serial measurement of a comprehensive panel of circulating OxLDL markers after uncomplicated PCI for stable angina does not predict restenosis.

Thr325Ile polymorphism of the TAFI gene is related to TAFI antigen plasma levels and angiographic restenosis after percutaneous coronary interventions.

BACKGROUND: The fibrinolytic system is closely related to several processes that are involved in restenosis. We have previously shown that high pre-procedural plasma levels of thrombin-activatable fibrinolysis inhibitor (TAFI) antigen predicted angiographic restenosis. The aims of this study were to evaluate the relationship between Thr325Ile polymorphisms, plasma levels of TAFI antigen, and late angiographic restenosis after percutaneous coronary intervention (PCI). METHODS: We prospectively studied 159 patients with stable angina who underwent successful elective angioplasty or stenting of de novo native coronary artery lesions. Blood samples were drawn before the procedure. TAFI antigen levels were measured, as well as the presence of TAFI Ile325Thr genetic variation. Follow-up coronary angiography was performed in 90% of patients. RESULTS: The genotypes based on Ile325Thr substitution had significantly different TAFI antigen levels: genotype C/C>C/T>T/T (111+/-29%, 87+/-24%, and 59+/-22%, respectively, p<0.006). T/T genotype was associated with lower rates of restenosis compared to C/T and C/C genotypes (25% versus 37% and 33%, respectively, p<0.05). CONCLUSIONS: These data suggest that plasma TAFI antigen levels are genetically controlled. The T/T Thr325Ile polymorphism of the TAFI gene is associated with lower plasma levels of TAFI antigen and lower restenosis rates after PCI.

Pre-procedural plasma levels of C-reactive protein and interleukin-6 do not predict late coronary angiographic restenosis after elective stenting.

AIMS: Inflammatory markers may serve as an important prognostic predictor in patients with coronary heart diseases. In patients undergoing coronary interventions, it has been shown that baseline C-reactive protein (CRP) could predict late clinical restenosis. Only a few small studies have examined the possible relationship with angiographic restenosis. In patients with stable angina pectoris,we examined whether baseline CRP and IL-6 predict late coronary angiographic restenosis after stenting. METHODS AND RESULTS: Pre-procedural plasma levels of CRP and IL-6 were measured in 216 patients with stable angina pectoris undergoing elective coronary stenting. Angiographic follow-up was performed in all patients at 6 months. Baseline CRP levels were 6.15 +/- 0.78 mg/L versus 5.24 +/- 1.17 mg/L in the patent and restenosis groups, respectively (P=0.64). IL-6 levels were 0.46 +/- 0.03 ng/L versus 0.40 +/- 0.07 ng/L in the patent and restenosis groups, respectively (P=0.50). CRP levels were obtained again at the time of angiographic follow-up and were found to be similar in both groups (2.89 +/- 0.29 mg/L versus 2.61 +/- 0.63 mg/L, P=0.72). Moreover, in a sub-group of 43 patients, serial blood samples were obtained at several time points after the procedure up to 6 months. Both CRP and IL-6 plasma levels increased significantly in response to the procedure. CRP levels peaked at 3 days (11.27 +/- 1.53 mg/L versus 4.26 +/- 0.72 mg/L at baseline, P<0.0001). IL-6 levels reached maximum values after 24 h (1.08 +/- 0.14 ng/L versus 0.53 +/- 0.08 ng/L at baseline, P<0.0001). However, in this sub-group of patients, neither peak CRP nor IL-6 levels were found to predict late angiographic restenosis. CONCLUSIONS: Coronary stenting is associated with transient increases in both CRP and IL-6 levels. However, pre-procedural CRP and IL-6 levels do not predict late coronary angiographic restenosis.

Percutaneous coronary intervention results in acute increases in oxidized phospholipids and lipoprotein(a): short-term and long-term immunologic responses to oxidized low-density lipoprotein.

BACKGROUND: This study was performed to assess whether oxidized low-density lipoprotein (OxLDL) levels are elevated after percutaneous coronary intervention (PCI). METHODS AND RESULTS: Patients (n=141) with stable angina pectoris undergoing PCI had serial venous blood samples drawn before PCI, after PCI, and at 6 and 24 hours, 3 days, 1 week, and 1, 3, and 6 months. Plasma levels of OxLDL-E06, a measure of oxidized phospholipid (OxPL) content on apolipoprotein B-100 detected by antibody E06, lipoprotein(a) [Lp(a)], autoantibodies to malondialdehyde (MDA)-LDL and copper-oxidized LDL (Cu-OxLDL), and apolipoprotein B-100-immune complexes (apoB-IC) were measured. OxLDL-E06 and Lp(a) levels significantly increased immediately after PCI by 36% (P<0.0001) and 64% (P<0.0001), respectively, and returned to baseline by 6 hours. In vitro immunoprecipitation of Lp(a) from selected plasma samples showed that almost all of the OxPL detected by E06 was bound to Lp(a) at all time points, except in the post-PCI sample, suggesting independent release and subsequent reassociation of OxPL with Lp(a) by 6 hours. Strong correlations were noted between OxLDL-E06 and Lp(a) (r=0.68, P<0.0001). MDA-LDL and Cu-OxLDL autoantibodies decreased, whereas apoB-IC levels increased after PCI, but both returned to baseline by 6 hours. Subsequently, IgM autoantibodies increased and peaked at 1 month and then returned to baseline, whereas IgG autoantibodies increased steadily over 6 months. CONCLUSIONS: PCI results in acute plasma increases of Lp(a) and OxPL and results in short-term and long-term immunologic responses to OxLDL. OxPL that are released or generated during PCI are transferred to Lp(a), suggesting that Lp(a) may contribute acutely to a protective innate immune response. In settings of enhanced oxidative stress and chronically elevated Lp(a) levels, the atherogenicity of Lp(a) may stem from its capacity as a carrier of proinflammatory oxidation byproducts.

Thrombin-activatable fibrinolysis inhibitor (TAFI): a novel predictor of angiographic coronary restenosis.

The fibrinolytic system is closely related to several processes that are involved in restenosis. We previously showed that low PAI-1 plasma levels predicted restenosis. Recently, a different fibrinolytic inhibitor, TAFI, has been described. The aims of this study were to evaluate the relationship between pre-procedural plasma levels of TAFI and late angiographic restenosis and the interaction between TAFI and PAI-1.We prospectively studied 159 patients with stable angina who underwent successful elective angioplasty or stenting of de novo native coronary artery lesions. TAFI and PAI-1 antigen levels were measured in plasma samples drawn before the procedure. Follow-up coronary angiography was performed in 92% of patients. There was a significant correlation between pre-procedural TAFI levels and 6-month % diameter stenosis (DS) (r = 0.21; p = 0.013). The overall angiographic restenosis rate (DS>50%) was 31%. Pre-procedural TAFI levels were significantly higher in patients with restenosis (108 +/- 33% versus 94+/-30%, p = 0.011). Restenosis rates for patients in the upper tertile of TAFI levels were 2-fold higher than for those in the lowest tertile (45% versus 22%; p = 0.016). A combination of high TAFI and low PAI-1 levels identified patients at the highest risk of restenosis (53%) compared to 14% in patients with low TAFI and high PAI-1 levels; p = 0.027. In conclusion, pre-procedural plasma TAFI antigen levels identify patients at increased risk for restenosis after PCI.

The interaction between platelets and factor VII/VIIa.

Blood coagulation normally occurs when factor VII interacts with its specific cellular receptor, tissue factor, which is exposed when a blood vessel is severed. The factor VII/tissue factor complex then initiates a cascade of proteolytic reactions involving factors IX, X, prothrombin and fibrinogen, culminating in the formation of a fibrin clot. The role of platelets in the initiation phase of blood coagulation is still unclear. It has been postulated that platelets bind activated factor VIIa independently of tissue factor, and that this interaction forms the basis of the usefulness of high-dose recombinant factor VIIa in treating hemophiliacs with inhibitory antibodies, and other thrombocytopenia-like syndromes. In this review, we will examine the evidence for and against such an hypothesis, as well as discuss an alternative mechanism for the efficacy of high-dose factor VIIa in treating hemophilic patients with inhibitors.

Cytotoxicity of nitric oxide donors in smooth muscle cells is dependent on phenotype, and mainly due to apoptosis.

Two phenotypes of rat carotid arterial smooth muscle cells (SMC) have been isolated in our laboratory, and their proteolytic and anti-proteolytic activities have been investigated in the presence or absence of various stimulating agents. We report here a comparative study of the cytotoxic effects of nitric oxide (NO) donors, sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP), towards the swirling-type and the epithelioid-type SMCs. The concentration- and time-dependence of NO donors' capacity to induce cell deaths was measured by an intracellular acid phosphatase activity assay and cell counting. The typical morphological features of apoptosis, such as cell blebbing and cytoplasm condensation, were observed by phase contrast microscopy and with a fluorescent DNA-binding dye. Apoptotic cell deaths were confirmed using DNA fragmentation and terminal deoxyribonucelotidyl transferase-mediated dUTP nick end labelling (TUNEL) methods. Western blots were used to investigate the protein expression of several known mediators of apoptosis. It was found that both NO donors induced cell deaths in the SMC phenotypes. Compared to the swirling SMCs, the epithelioid SMCs were much more sensitive to these agents. A time- and dose-dependent decrease of cell viability was observed at NO donor concentrations higher than 0.2 mmol/l. Microscopic methods revealed cell morphology of apoptotic cell deaths. The 180-bp DNA multimers typical of apoptosis were shown by DNA fragmentation. TUNEL technique confirmed that apoptosis occurred most readily in the epithelioid SMCs than the swirling SMCs. When epithelioid SMCs were treated with SNP, changes in p53, p21(WAF1), Bcl-2, caspase 3 and PARP protein expression were found. These protein levels were unchanged when swirling SMCs were similarly treated.

Regulation of plasminogen activator inhibitor-1 secretion by urokinase and tissue plasminogen activator in rat epithelioid-type smooth muscle cells.

Tissue plasminogen activator (tPA) and urokinase (uPA) are targets of plasminogen activator inhibitor-1 (PAI-1) inhibition. We have previously shown that both proteases can also induce PAI-1 secretion in rat smooth muscle cells (SMCs). We now report that both proteases appear to use very similar cellular mechanisms for signal transduction. They induced PAI-1 secretion using a pathway(s) involving protein kinase C (PKC). They also activated the Raf/Mek/mitogen-activated protein kinase (MAPK) pathway, which lies downstream of PKC activation. Activation of protein kinase A (PKA), however, lowered PAI-1 secretion induced by uPA and tPA, as a result of an inhibition of the PKC pathway and inhibition of Raf, Mek and MAPK phosphorylations. Src and syk family non-receptor tyrosine kinases (TK) were also involved in PAI-1 induction. The mechanisms of interaction of these tyrosine kinases with other pathways appeared to be quite different: src appeared to act within the PKC and PKA pathways, while syk operated independently of these pathways. Furthermore, whereas src inhibition resulted in inhibition of Raf/Mek/Erk phosphorylations, syk inhibition could only inhibit Mek and Erk phosphorylations but not the phosphorylation of Raf. These multiple pathways utilized by uPA and tPA to modulate PAI-1 secretion might be involved in determining the proteolytic or antiproteolytic potential of the SMCs under different pathophysiological conditions.