Blood cell activation, coagulation, and inflammation in men and women with coronary artery disease

Sex dimorphisms in coagulation: Implications in trauma-induced coagulopathy and trauma resuscitation

Trauma-induced coagulopathy (TIC) is one of the leading causes of preventable death in injured patients. Consequently, it is imperative to understand the mechanisms underlying TIC and how to mitigate this mortality. An opportunity for advancement stems from the awareness that coagulation demonstrates a strong sex-dependent effect. Females exhibit a relative hypercoagulability compared to males, which persists after injury and confers improved outcomes. The mechanisms underlying sex dimorphisms in coagulation and its protective effect after injury have yet to be elucidated. This review explores sex dimorphisms in enzymatic hemostasis, fibrinogen, platelets, and fibrinolysis, with implications for resuscitation of patients with TIC.

Evaluation of four commercial ELISAs to measure tissue factor in human plasma

Background

Under pathological conditions, tissue factor (TF)-positive extracellular vesicles (EVs) are released into the circulation and activate coagulation. Therefore, it is important to identify methods that accurately quantitate levels of TF in plasma. Enzyme-linked immunosorbent assays (ELISAs) are a fast and simple method to quantitate levels of proteins. However, there are several specific challenges with measuring TF antigen in plasma including its low concentration and the complexity of plasma.

Objectives

We aimed to evaluate the ability of 4 commercial ELISAs to measure TF in human plasma.

Methods

We determined the ability of 4 commercial ELISAs (Imubind, Quantikine, Human SimpleStep, and CD142 Human) to detect recombinant human TF (Innovin) (12.5-100 pg/mL), TF-positive EVs isolated from the culture supernatant from a human pancreatic cancer cell line (57 pg/mL), TF in plasma containing low levels of EV TF activity (1.2-2.6 pg/mL) from lipopolysaccharide-stimulated whole blood, and plasma containing high levels of EV TF activity (151-696 pg/mL) from patients with acute leukemia.

Results

The CD142 Human ELISA could not detect recombinant TF. Imubind and Quantikine but not Human SimpleStep detected recombinant TF spiked into plasma and TF-positive EVs isolated from the culture supernatant of a human pancreatic cancer cell line. Quantikine and Imubind could not detect low levels of TF in plasma from lipopolysaccharide-stimulated whole blood. However, Quantikine but not Imubind detected TF in plasma from acute leukemia patients with high levels of EV TF activity.

Conclusion

Our results indicate that commercial ELISAs have different abilities to detect TF. Quantikine and Imubind could not detect low levels of TF in plasma, but Quantikine detected TF in plasma with high levels of TF.

Polymorphonuclear phenotypical expression of CD18, at baseline and after in vitro activation, in several clinical disorders: Revision of our case series

BACKGROUND

In relation to the different and important roles of the beta2 integrins, we have revisited the expression of polymorphonuclear leukocyte CD18 in several clinical disorders, at baseline and after in vitro activation.

SUBJECTS

we have examined subjects with type 1 diabetes mellitus, vascular atherosclerotic disease, type 2 diabetes mellitus without and with macrovascular complications, chronic renal failure on conservative treatment, essential hypertension, deep venous thrombosis, acute ischemic stroke and subjects with venous leg ulcers.

METHODS

unfractioned leukocyte suspension was prepared according to the Mikita's method, while the leukocyte were separated into mononuclear and polymorphonuclear cells with a Ficoll-Hypaque medium. Using specific monoclonal antibody, the CD18 expression was evaluated with cytofluorimetric analysis, using FACScan (Becton Dickinson) be Cellquest software; the activation in vitro with PMA was effected according to modified Yasui and Masuda methods.

RESULTS

in type 1 diabetes mellitus, at baseline CD18 is under expressed in comparison with normal control, and not changes after PMA activation were observed; in subjects with vascular atherosclerotic disease, in type 2 diabetes mellitus CD18 is over expressed at baseline but does not vary after activation; in subjects with chronic renal failure, essential hypertension and in subjects with acute ischemic stroke the CD18 up-regulate at baseline compared to normal control, and it increases further after activation; in subjects with deep venous thrombosis the CD18 expression is not different from control group at baseline, but it increases after activation; finally, in subjects with venous leg ulcers the CD18 is normally expressed at baseline, and it does not change after PMA activation.

CONCLUSIONS

in the different clinical disorders, the trend of this integrin subunit provides some specific information, useful to select the best therapeutic strategy in clinical practice.

Relationship Between Immunoinflammation and Coronary Physiology Evaluated by Quantitative Flow Ratio in Patients With Coronary Artery Disease

Background: The association between coronary physiology and immunoinflammation has not been investigated. We performed a retrospective study using quantitative flow ratio (QFR) to evaluate the interaction between immunoinflammatory biomarkers and coronary physiology.

Methods: A total of 172 patients with CAD who underwent coronary arteriography (CAG) and QFR were continuously enrolled from May 2020 to February 2021. As a quantitative indicator of coronary physiology, QFR can reflect the functional severity of coronary artery stenosis. The target vessel measured by QFR was defined as that with the most severe lesions. Significant coronary anatomical stenosis was defined as 70% stenosis in the target vessel.

Results: Compared with the QFR > 0.8 group, interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ were increased and CD3⁺ and CD4⁺ T lymphocyte counts were decreased in the QFR ≤ 0.8 group. In addition, patients with DS ≤ 70% had higher IL-6, IL-10, and TNF-α levels and decreased CD3⁺ and CD4⁺ T lymphocyte counts than those with DS > 70%. Logistic regression analysis indicated IL-6 to be an independent predictor of significant coronary functional and anatomic stenosis (odds ratio, 1.125; 95% CI, 1.059–1.196; P < 0.001). Receiver operating characteristic (ROC) analyses showed that IL-6 > 6.36 was predictive of QFR ≤ 0.8 of the target vessel. The combination of IL-6, IL-10 and CD4 improved the value for predicting QFR ≤ 0.8 of the target vessel (AUC, 0.737; 95% CI, 0.661–0.810).

Conclusion: Among immunoinflammatory biomarkers, IL-6 was independently associated with a higher risk of QFR ≤ 0.8 of the target vessel. The combination of immunoinflammatory biomarkers was highly predictive of significant coronary functional and anatomic stenosis.

Soluble Platelet Release Factors as Biomarkers for Cardiovascular Disease

Platelets are the main players in thrombotic diseases, where activated platelets not only mediate thrombus formation but also are involved in multiple interactions with vascular cells, inflammatory components, and the coagulation system. Although in vitro reactivity of platelets provides information on the function of circulating platelets, it is not a full reflection of the in vivo activation state, which may be relevant for thrombotic risk assessment in various disease conditions. Therefore, studying release markers of activated platelets in plasma is of interest. While this type of study has been done for decades, there are several new discoveries that highlight the need for a critical assessment of the available tests and indications for platelet release products. First, new insights have shown that platelets are not only prominent players in arterial vascular disease, but also in venous thromboembolism and atrial fibrillation. Second, knowledge of the platelet proteome has dramatically expanded over the past years, which contributed to an increasing array of tests for proteins released and shed from platelets upon activation. Identification of changes in the level of plasma biomarkers associated with upcoming thromboembolic events allows timely and individualized adjustment of the treatment strategy to prevent disease aggravation. Therefore, biomarkers of platelet activation may become a valuable instrument for acute event prognosis. In this narrative review based on a systematic search of the literature, we summarize the process of platelet activation and release products, discuss the clinical context in which platelet release products have been measured as well as the potential clinical relevance.

Trans-vessel gradient of myeloperoxidase in coronary artery disease

BACKGROUND

Coronary artery disease (CAD) may reflect generalized inflammation. We evaluated leucocyte activation in subjects with and without CAD in different vascular compartments.

MATERIALS AND METHODS

Patients were divided in two groups; subjects without CAD (controls; n = 25) and with stable CAD (n = 52) based on coronary angiography. After blood sampling from vessels, cardiovascular risk factors and leucocyte activation markers CD11b, CD66b and cytoplasmatic myeloperoxidase (MPO) were determined by flow cytometry.

RESULTS

Myeloperoxidase (MPO) was higher in patients with CAD at all sites compared with controls (188 ± 7 vs. 210 ± 12 au for venous (P < 0.05), 178 ± 7 vs. 212 ± 12 au for femoral artery (P = 0.08), 166 ± 7 vs. 195 ± 12 au for abdominal artery (P < 0.05), 166 ± 6 vs. 189 ± 14 au for left coronary (P = 0.08) and 163 ± 6 vs. 193 ± 12 au for the right coronary artery (P < 0.05)). Other markers did not differ between the groups. A gradient of inflammation from peripheral vessels to the coronaries was found by differences in MPO in both groups; from 210 ± 12 au in the venous compartments towards 189 ± 14 and 193 ± 12 au, in the left and right coronaries, respectively, for the controls (P = 0.001), and from 188 ± 7 au in the venous compartment towards 166 ± 6 and 163 ± 6 au in the left and right coronaries, respectively, for the patients (P = 0.007). Other leucocyte activation markers did not show such a gradient.

CONCLUSIONS

There is a generalized inflammatory neutrophil gradient for MPO from peripheral vessels towards the coronaries in both patients with CAD and controls. However, patients with CAD show a higher degree of inflammation, mostly in the coronaries. These data strengthen the role of activated neutrophils in CAD.

Sex and inflammation in respiratory diseases: a clinical viewpoint

This review discusses sex differences in the prognosis of acute or chronic inflammatory diseases. The consequences of severe inflammation vary in relation to sex, depending on illness duration. In the majority of acute diseases, males present higher mortality rates, whereas continuous chronic inflammation associated with tissue damage is more deleterious in females. The recruitment of cells, along with its clinical expression, is more significant in females, as reflected by higher inflammatory markers. Given that estrogens or androgens are known to modulate inflammation, their different levels in males and females cannot account for the sexual dimorphism observed in humans and animals from birth to death with regard to inflammation. Numerous studies evaluated receptors, cytokine production, and clinical outcomes in both animals and humans, revealing that estrogens clearly modulate the immune response, but the results are contradictory and difficult to link to hormone concentrations. Even in prepubescent children, the presentation of acute pneumonia or chronic diseases mimics the adult pattern. Several genes located on the X chromosome have been shown to encode molecules involved in inflammation. Moreover, 10% to 15% of the genes from silenced X chromosome may escape inhibition. Females are also a mosaic of cells with genes from either paternal or maternal X chromosome. Therefore, polymorphism of X-linked genes would result in the presence of two cell populations with distinct regulatory arsenals, providing females with greater diversity to fight against infectious challenges, in comparison with the uniform cell populations in hemizygous males. The similarities observed between males and Turner syndrome patients using an endotoxin stimulation model support the difference in gene expression between monosomy and disomy for the X chromosome. Considering the enhanced inflammation in females, cytokine production may be assumed to be higher in females than males. Even if all results are not clear-cut, nonetheless, many studies have reported higher cytokine levels in both male humans and animals than in females. High IL-6 levels in males correlated with poorer prognosis and shorter longevity. A sound understanding of the basic regulatory mechanisms responsible for these gender differences may lead to new therapeutic targets.

The effect of hormone therapy and tibolone on serum CD40L and ADAM-8 in healthy post-menopausal women

BACKGROUND/AIM

The role of neutrophils and platelets in atherothrombotic disease is well established. The aim of our study was to investigate the effect of HT and tibolone on the soluble markers of neutrophil and platelet activation, "a disentigrin and metalloproteinase domain" (ADAM-8) and CD40 ligand (CD40L) respectively, in healthy post-menopausal women.

SUBJECTS AND METHODS

One hundred and six healthy post-menopausal women were randomly allocated to: estradiol plus drospirenone (E₂/DSP), E₂ hemihydrate 1 mg plus norethisterone acetate (E₂/NETA) 0.5 mg, and tibolone 2.5 mg. Serum ADAM-8 and CD40L were measured at baseline and at 6 months.

RESULTS

Baseline values of ADAM-8 and CD40L were similar between groups. No significant correlation was revealed between ADAM-8 or CD40L and parameters related to cardiovascular risk factors in each group. No significant changes were observed between baseline values and values at 6 months (E₂/DSP group: ADAM-8: 267.4±71.3 pg/ml vs 270.7±42.8 pg/ml, p=0.86, CD40L: 6.43±3.13 vs 6.79±2.70 ng/ml, p=0.67), (E₂/NETA group: ADAM-8: 308.3±64.3 vs 294.7±57.7 pg/ml, p=0.40, CD40L: 9.68±2.81 vs 8.59±5.13 ng/ml, p=0.51), (tibolone group: ADAM-8: 307.5±87.5 vs 289±48.1 pg/ml, p=0.48, CD40L: 9.46±4.30 vs 9.26±4.60 ng/ml, p=0.99).

CONCLUSIONS

Our study has not revealed an association between estrogen plus progestin treatment or tibolone on serum ADAM-8 and CD40L levels in healthy post-menopausal women. Larger prospective studies are needed to further investigate the effect of low-dose HT or tibolone on serum markers of neutrophil and platelet activation.

The influence of direct thrombin inhibitors on the formation of platelet-leukocyte aggregates and tissue factor expression

INTRODUCTION

High concentrations of platelet-monocyte aggregates (PMAs) have been found in patients with myocardial infarction (MI). Oral direct thrombin inhibitors (DTIs) are under evaluation as long-term antithrombotic treatment. The aim was to evaluate whether DTIs affect the formation of platelet-leukocyte aggregates, TF expression and procoagulant microparticles (MPs).

MATERIAL AND METHODS

DTIs were added to an experimental whole blood model before platelet activation with thrombin or ADP. The concentrations of PMAs, platelet-granulocyte aggregates (PGAs), the amount of platelets bound per leukocyte and MPs were investigated by flow cytometry. TF mRNA and activity were recorded in all settings. TF activity was evaluated in a MI population treated with or without an oral DTI.

RESULTS

In vitro, thrombin and ADP increased the formation of PMAs and PGAs as well as TF mRNA expression. DTIs reduced the amount platelets bound to monocytes (p=0.02) and to granulocytes (p=0.001) upon thrombin stimulation together with a reduction of TF mRNA. In contrast, the ADP-induced formation of PMAs, PGAs and TF mRNA was not affected by the DTIs. Both thrombin and ADP stimulation increased the amount of TF-expressing MPs, which was effectively inhibited by the DTIs (p=0.02-0.002). In the MI population, the DTI reduced the TF activity (p<0.001).

CONCLUSION

DTIs modulate the formation of PMAs, PGAs and the TF production therein. Together with a reduction of procoagulant MPs, these results may contribute to the clinical benefit found of oral DTIs. Targeting different mechanisms in platelet and coagulation activation may be of importance due to the lack of effect of DTIs on ADP-induced platelet-leukocyte aggregates and TF production.

Enhanced neutrophil expression of annexin-1 in coronary artery disease

The systemic inflammatory activity in patients with stable coronary artery disease (CAD) is associated with a dysregulated cortisol response. Moreover, an aberrant activation status of neutrophils in CAD has been discussed; and the question of glucocorticoid resistance has been raised. The anti-inflammatory actions of glucocorticoids are mediated by annexin-1 (ANXA1). We investigated the expression of glucocorticoid receptors (GR) and ANXA1, as well as the exogenous effects of ANXA1 on neutrophils in CAD patients and related the data to diurnal salivary cortisol. Salivary cortisol levels were measured in the morning and evening during 3 consecutive days in 30 CAD patients and 30 healthy individuals. The neutrophil expression of GR and ANXA1 was determined by flow cytometry. The effect of exogenous ANXA1 was determined in a neutrophil stimulation assay. The patients showed a flattened diurnal cortisol pattern compared with healthy subjects, involving higher levels in the evening. The neutrophil expression of GR-total and GR-alpha was decreased, whereas the GR-beta expression did not differ compared with controls. The neutrophil expression of ANXA1 was significantly increased in patients. Ex vivo, ANXA1 impaired the leukotriene B(4)-induced neutrophil production of reactive oxygen species in patients but not in controls. Our findings indicate a persistent overactivation of the hypothalamic-pituitary-adrenal axis in CAD patients but do not give any evidence for glucocorticoid resistance, as assessed by the neutrophil expression of GR and ANXA1. The altered neutrophil phenotype in CAD may thus represent a long-term response to disease-related activation.

Tissue factor and IL8 production by P-selectin-dependent platelet-monocyte aggregates in whole blood involves phosphorylation of Lyn and is inhibited by IL10

BACKGROUND

P-selectin and CD40L expressed by activated platelets induce tissue factor (TF) and inflammatory cytokines in monocytes, but little is known of the cellular signaling pathways involved. The anti-inflammatory cytokine IL10 reduces atherosclerotic plaque formation.

OBJECTIVES

To evaluate the importance of P-selectin upon platelet-monocyte aggregate (PMA) formation in thrombin receptor activator peptide (TRAP) stimulated whole blood, the P-selectin-P-selectin glycoprotein ligand (PSGL)-1-induced cellular signaling pathway, and the effects of IL10 on these functions.

METHODS

TF, IL8, and monocyte chemotactic protein-1 (MCP-1) production, PMAs and phosphorylation of Lyn were analyzed in whole blood, purified monocytes, and vitamin D(3)-differentiated U-937 cells stimulated with TRAP or P-selectin with or without IL10. Anti-P-selectin or anti-CD40L antibodies (Abs), Src-kinases inhibitors, SU6656 or PP2, were added in some experiments.

RESULTS

TRAP and P-selectin increased TF, IL8, and MCP-1 mRNA in whole blood and purified monocytes. Anti-P-selectin Ab reduced TRAP-induced PMA formation by 80 +/- 2% (P = 0.001) and production of TF (P = 0.04) and IL8 (P = 0.01). IL10 and SU6656 had no effect on PMA formation, although both significantly reduced TF (P = 0.002 and P = 0.02) and IL8 (P = 0.009 and P = 0.001) mRNA upon TRAP and P-selectin stimulation. Induced Lyn phosphorylation in monocytes was diminished by SU6656 (P = 0.02), anti-P-selectin Ab (P = 0.02), and IL10 (P = 0.03) upon TRAP or P-selectin stimulation. These results were confirmed in the vitamin D(3)-differentiated U-937 cells.

CONCLUSIONS

The formation of PMAs in whole blood was P-selectin-dependent in the long term. P-selectin-PSGL-1-induced TF and IL8 expression through Lyn phosphorylation, and part of the inhibitory effect of IL10 depends on reduced phosphorylation.

Xa inhibition and coagulation activity--the influence of prolonged dalteparin treatment and gender in patients with acute coronary syndrome and healthy individuals

BACKGROUND

We evaluated coagulation activity in relation to gender in patients with acute coronary syndromes and in healthy individuals of similar age, and related coagulation activity to levels of Xa inhibition during dalteparin treatment.

METHODS

Serial blood samples were obtained from 555 (172 women) of 2267 patients in the Scandinavian FRISC II study, and a single sample in 457 (151 women) apparently healthy age- and sex-matched individuals. After randomization, all patients received dalteparin 120 IU/kg s.c. (maximum 10,000 IU) twice daily for 5 to 7 days inhospital and thereafter placebo (n = 285) or sex- and weight-adjusted doses of dalteparin (5000 or 7500 IU) twice daily (n = 270) for 3 months.

RESULTS

Before randomization, 96% of the patients had open-label anticoagulation with unfractionated heparin or dalteparin. Therapeutic anti-Xa levels (> 0.5 IU/mL) were found in 74%, 55%, 58%, and 33% of the dalteparin-treated patients at randomization, 2 days, 4 to 7 weeks, and 3 months, respectively, and were significantly related to lower levels of coagulation activity, ie, factor VIIa, prothrombin fragment 1+2, and D-dimer, during prolonged treatment. Female patients had higher anti-Xa levels than men at randomization (median 0.69 vs 0.60 IU/mL, P = .01) and at 2 days (0.65 vs 0.59 IU/mL, P < .001). Female patients had also significantly higher levels of all 3 coagulation markers at randomization, 2 days, 4 to 7 weeks, and 3 and 6 months. Similarly, healthy women had higher prothrombin fragment 1+2 levels (median 1.19 vs 0.94 nmol/L) and D-dimer levels than men (26 vs 21 microg/L) (both P < .001).

CONCLUSIONS

Despite weight-adjusted dosing, female patients reached higher anti-Xa levels, suggesting increased sensitivity to dalteparin treatment. Healthy women and female patients also had higher coagulation activity, which might increase the risk of thrombus formation. The large proportion of patients with subtherapeutic anti-Xa during prolonged dalteparin treatment may reflect poor compliance and could thus contribute to the gradual loss of clinical efficacy.

Soluble but not platelet P-selectin correlates with spontaneous platelet aggregation: a pilot study

BACKGROUND

P-selectin (PS) is a marker of platelet activation measured on the platelet surface as platelet PS (pPS) or in serum as soluble PS (sPS). Controversy remains over the exact relationship between sPS, pPS, and other markers such as spontaneous platelet aggregation (SPA).

OBJECTIVE

To investigate correlations between pPS, sPS, and SPA in patients with peripheral arterial disease.

METHODS

SPA, pPS, and sPS levels were measured in venous blood sampled from patients following intermittent claudication (n = 18) or an acute stroke (n = 18).

RESULTS

SPA and sPS correlated significantly in the claudicants (Pearson correlation coefficient, r = 0.661; P = .0020) and stroke patients (r = 0.514; P = .020). No significant correlation was identified between pPS and SPA, or sPS and pPS.

CONCLUSIONS

The 2 methods of assessing PS are not comparable. Although pPS is accepted as a platelet activation marker, sPS may be a better indicator of aggregation represented by SPA.

Neutrophil activation status in stable coronary artery disease

Background

During the last years, neutrophils have emerged as important players in atherogenesis. They are highly activated in peripheral blood of patients with unstable angina. Moreover, a primed state of circulating neutrophils has been proposed in patients with stable angina. Our aim was to investigate the neutrophil activation status in patients with stable coronary artery disease (CAD) at conventional drug treatment.

Methodology and Principal Findings

Thirty patients with stable CAD and 30 healthy controls were included using a paired design. The neutrophil expression of CD18 and high-affinity state of CD11b was analysed by flow cytometry before and after stimulation with chemoattractants. Also, the production of reactive oxygen species (ROS) was determined by chemiluminescence. During basal conditions, the neutrophil expression of CD18 or high-affinity state of CD11b did not differ between patients and controls. Chemoattractants (Interleukin-8 and Leukotriene B₄) did not increase either the expression or the amount of high-affinity CD11b/CD18-integrins in CAD patients compared to controls, and had no effect on the production of ROS. On the other hand, the ROS production in response to C3bi-opsonised yeast particles and the neutrophils' inherent capacity to produce ROS were both significantly decreased in patients.

Conclusion/Significance

We could not find any evidence that neutrophils in patients with stable CAD were primed, i.e. more prone to activation, compared to cells from healthy controls. According to our data, the circulating neutrophils in CAD patients rather showed an impaired activation status. It remains to be elucidated whether the neutrophil dysfunction in CAD is mainly a marker of chronic disease, an atherogenic factor or a consequence of the drug treatment.

Soluble CD40 ligand:interleukin-10 ratio predicts in-hospital adverse events in patients with ST-segment elevation myocardial infarction

INTRODUCTION

The balance between pro-inflammatory and anti-inflammatory molecules is likely to modulate the processes that lead to atherogenesis and rapid coronary artery disease progression. We sought to compare the positive predictive values of serum soluble CD40 ligand (sCD40L)/interleukin-10 (IL-10) ratio, versus individual sCD40L, and IL-10 measurements regarding in-hospital events in patients admitted into the hospital with ST-segment elevation myocardial infarction (STEMI).

METHODS

We recruited 96 patients with STEMI. sCD40L and IL-10 were measured at hospital admission in every patient. The composite of in-hospital death and heart failure represented the study end-point. Heart failure was defined as Killip class>1. Multivariable logistic regression analysis was performed to identify independent variables related to in-hospital events.

RESULTS

Thirty two patients (33%) achieved the study end-point and 64 (67%) had no adverse events during hospital admission. IL-10 levels (pg/ml) were lower (28.2+/-9.8 versus 33.24+/-11.3, p=0.03) and sCD40L levels (pg/ml) higher (156.8+/-54.2 versus 135.4+/-38.70, p=0.02) in patients with events compared to those without events. Significantly higher odd ratios were found for sCD40L/IL-10 ratio (OR=2.10, 95% CI: 1.90 to 2.80, p=0.01) compared to individual sCD40L (OR=1.40, 95% CI: 0.90 to 2.20, p=0.08) and IL-10 (OR=0.70, 95% CI: 0.50 to 0.93, p=0.02) measurements.

CONCLUSION

Our study showed that serum ratio of sCD40L/IL-10 is a better independent predictor of in-hospital adverse events than individual sCD40L and IL-10 measurements in patients with STEMI.

Acetylsalicylic acid is compounding to antiplatelet effect of C-reactive protein

The contribution of inflammatory process to the modulation of platelet response to acetylsalicylic acid (ASA) remains obscure. In our study, we examined the in vitro effect of C-reactive protein (CRP) on the ASA-mediated inhibition of collagen-stimulated platelet reactivity. Influence of CRP on platelet responsiveness to ASA was analysed using classical turbidimetric aggregation and flow cytometry. When acting alone, both C-reactive protein and ASA inhibited collagen-dependent platelet aggregation and reduced the expressions of two platelet surface membrane activation markers: P-selectin and activated GPIIbIIIa complex. Compared to the effects observed for ASA alone, the simultaneous action of both agents lead to further reductions in platelet aggregation (by 56.7+/-1.0% vs. 14.9+/-0.6%, p<0.0001) and lowered the expressions of platelet surface membrane P-selectin (by 72.1+/-5.3% vs. 65.0+/-6.0%, p<0.01) and activated GPIIbIIIa (by 67.0+/-5.6% vs. 47.7+/-8.3%, p<0.01). In general, our findings showed for the first time the augmenting effect of native C-reactive protein in the antiplatelet action of acetylsalicylic acid. Thus, we conclude that the effectiveness of aspirin therapy may strongly depend upon the presence of native CRP in circulation.

Relationship between electrocardiographic and biochemical variables in coronary artery disease

BACKGROUND

ECG (electrocardiogram) markers reflecting abnormal heart rate variability and abnormal repolarization as well as several biochemical markers reflecting inflammation, endothelial dysfunction, and procoagulation states were reported to show an association with increased cardiovascular mortality. ECG and biochemical markers could operate independently or they could interrelate in pathogenetic pathways of coronary disease. In this study, we aimed to explore the relationship between ECG and biochemical markers in a longitudinal study of coronary patients.

METHODS

A total of 499 observations from 52 patients with up to 12 repeated measurements were collected providing data on series of ECG (heart rate variability and repolarization) parameters and biochemical parameters. Generalized estimating equation models adjusting for repeated measurements were used for the analyses.

RESULTS

There was a significant association between ECG parameters reflecting abnormal repolarization (prolonged QT interval, lower T wave amplitude) and elevated levels of C-reactive protein and fibrinogen. Abnormal heart rate variability, increased sympathetic tone (low-frequency power) was associated with increased concentrations of soluble E-selectin, a marker of endothelial cell activation. There was no association between ECG markers and parameters reflecting increased procoagulation states.

CONCLUSION

These results indicate that there is an association between ECG parameters and blood markers reflecting endothelial function and inflammation in coronary artery disease patients. The pathophysiologic mechanisms of these associations remain to be elucidated.

Activation of peripheral and in vivo transmigrated neutrophils in patients with stable coronary artery disease

Accumulating evidence support a role of neutrophils in coronary artery disease (CAD). However little is known about the action of neutrophils at a local inflammatory site represented by an atherosclerotic plaque. To gain insight into these issues, we applied a skin blister model that permits analyses of in vivo transmigrated neutrophils. We hypothesised that the chronic inflammation in stable CAD mediates priming of neutrophils that impacts the out-come of neutrophil action at an inflammatory site. Thirteen patients with angiographically verified CAD were eligible for study entry together with 13 age and sex matched controls. Markers of inflammation (IL-6 and CRP), neutrophil activation (IL-8 and MMP-9/NGAL), and functional aspects (CD11b up-regulation and intracellular H(2)O(2) production) of peripheral and in vivo transmigrated neutrophils were studied. Systemic IL-8 and MMP-9/NGAL concentrations were significantly increased in patients indicating a primed state in circulating neutrophils. In vivo transmigrated neutrophils in stable CAD patients had an increased propensity to release MMP-9/NGAL and a reduced capacity to up-regulate CD11b and to produce hydrogen peroxide. These aberrations at the inflammatory site may be a consequence of a primed state of circulating neutrophils and point towards potential mechanisms whereby neutrophils at a local inflammatory site may contribute to the pathogenesis of CAD.

Immunologic quantitation of tissue factors

The large number of conflicting reports on the presence and concentration of circulating tissue factor (TF) in blood generates uncertainties regarding its relevance to hemostasis and association with specific diseases. We believe that the source of these controversies lies in part in the assays used for TF quantitation. We have developed a highly sensitive and specific double monoclonal antibody fluorescence-based immunoassay and integrated it into the Luminex Multi-Analyte Platform. This assay, which uses physiologically relevant standard and appropriate specificity controls, measures TF antigen in recombinant products and natural sources including placenta, plasma, cell lysates and cell membranes. Comparisons of reactivity patterns of various full-length and truncated TFs on an equimolar basis revealed quantitative differences in the immune recognition of TFs by our antibodies in the order of TF 1-263 > 1-242 > 1-218 > placental TF. Despite this differential recognition, all TF species are quantifiable at concentrations < or = 2 pM. Using a calibration curve constructed with recombinant TF 1-263 and plasma from healthy individuals (n = 91), we observed the concentration of TF antigen in plasma to be substantially lower than that generally reported in the literature: TF antigen in plasma of 72 individuals (79%) was below 2 pM (quantitative limit of our assay); TF antigen levels between 2.0 and 5.0 pM could be detected in six individuals (7%); and in 14% (13 plasmas), the non-specific signal was higher than the specific signal, and thus TF levels could not be determined. These differential recognition patterns affect TF quantitation in plasma and should be considered when evaluating plasma TF-like antigen concentrations.

Platelet-endothelial cell adhesion molecule-1 gene polymorphism and its soluble level are associated with severe coronary artery stenosis in Chinese Singaporean

OBJECTIVES

Platelet-endothelial cell adhesion molecule-1 (PECAM-1) mediates the transendothelial migration of circulating leukocytes, a characteristic change in vascular inflammation leading to atherosclerotic plaque development. We hypothesized that genetic variation and soluble level of PECAM-1 could be associated with coronary artery disease (CAD).

DESIGN AND METHODS

We analyzed two single nucleotide polymorphisms (SNPs) of PECAM-1 gene C+373G (Leu125Val) at exon 3, which encodes the first extracellular (Ig)-like domain that mediates the homophilic binding of PECAM-1, and G+1688A (Ser563Asn) at exon 8 in 144 angiographically documented (> or =70% stenosis) patients with CAD and 150 age- and sex-matched controls in the Chinese population in Singapore, using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy. Level of plasma soluble PECAM-1 (sPECAM-1) was measured by ELISA.

RESULTS

The Leu125Val polymorphism was associated with CAD (P < 0.01). Also, the level of sPECAM-1 is was found to be elevated in CAD patients (P = 0.005). Moreover, subjects with the homozygous GG genotype of the Leu125Val polymorphism had higher sPECAM-1 levels (P = 0.005). The level of sPECAM-1 was further correlated to soluble platelet selectin (sP-selectin, also measured by ELISA), platelet count, and total white blood cell count (WBC), suggesting that platelets are a major source of sPECAM-1 and platelet activation and inflammation may contribute to PECAM-1 elevations in CAD patients.

CONCLUSION

The Leu125Val polymorphism of PECAM-1 and the level of sPECAM-1 are associated with CAD in Chinese in Singapore. The level of sPECAM-1 is also associated with platelet activation and inflammation and correlated to the Leu125Val polymorphism. Our data suggest that PECAM-1 plays an important role in the development of atherosclerosis.

Circulating levels of proinflammatory cytokines and neutrophil-platelet aggregates in patients with coronary artery disease

Several lines of evidence indicate that increased inflammatory activity in peripheral blood is associated with the acute coronary syndrome. Systemic inflammation in clinically stable conditions of coronary artery disease has been less studied. We examined cytokine profiles in 20 patients who had acute coronary syndrome, 45 who had angiographically verified coronary artery disease and stable angina pectoris, and 45 healthy controls. Circulating levels of C-reactive protein, interleukin-1 receptor antagonist, interleukin-2 receptor, interleukin-6, interleukin-10, and interleukin-18 were determined. Subpopulations of peripheral immune cells, including neutrophil-platelet aggregates, were analyzed by 3-color flow cytometry using a panel of monoclonal antibodies. Patients who had acute coronary syndrome and stable angina pectoris had significantly higher levels of C-reactive protein, interleukin-6, and interleukin-1 receptor antagonist than did controls, whereas levels of interleukin-2 receptor, interleukin-10, and interleukin-18 were similar across groups. Patients had significantly more neutrophils, and the numbers of neutrophil-platelet aggregates were particularly large in patients who had stable angina pectoris. High levels of C-reactive protein, interleukin-6, and interleukin-1 receptor antagonist in patients were significantly related to numbers of neutrophils and neutrophil-platelet aggregates but not to other immune cell subpopulations. The data suggest that the interaction between neutrophils and platelets is an important component of proinflammatory activity seen in peripheral blood of stable and unstable forms of coronary artery disease.

The significance of human platelet-activating factor-acetylhydrolase in patients with chronic stable angina

BACKGROUND: Inflammatory reactions within coronary atherosclerotic plaques are increasingly thought to be crucial determinants of the clinical course in patients with coronary artery disease (CAD). Platelet-activating factor-acetylhydrolase (PAF-AH) is considered to reflect the ongoing inflammatory process in patients with CAD. Our objective was to determine the activity of PAF-AH in patients with stable angina and its correlations to lipoprotein levels and the inflammatory status of the patient. METHODS: Forty-five patients with documented CAD and stable angina and 20 controls were investigated for PAF-AH activity, lipoprotein levels, and peripheral neutrophil (PMN) activity. RESULTS: Patients were divided into two groups according to the values of PAF-AH activity (group 1: </=250 IU/l and group 2: >250 IU/l). A correlation was observed between PAF-AH activity and LDL-C and HDL-C in controls and in all patients. The percentage of granulocytes generating intracellular O(2)(-) in unstimulated PMN was higher in group 2 patients than in group 1 patients and controls. The phagocytic activity of PMNs had an inverse correlation with PAF-AH in group 2. High intracellular O(2)(-) generation was coupled with low extracellular release of the anion and phagocytosis impairment in group 2. During the follow-up period, some of the patients in group 2 displayed a worsening of the clinical state and/or resting ECG changes. CONCLUSIONS: PAF-AH activity in patients with stable angina is correlated with hyperlipemia and a high PMN activation state, and it may be considered a potential predictor of vascular risk.

Thrombin and tumor necrosis factor alpha synergistically stimulate tissue factor expression in human endothelial cells: regulation through c-Fos and c-Jun

Tissue factor is critically important for initiating the activation of coagulation zymogens leading to the generation of thrombin. Quiescent endothelial cells do not express tissue factor on their surface, but many stimuli including cytokines and coagulation proteases can elicit tissue factor synthesis. We challenged human endothelial cells simultaneously with tumor necrosis factor alpha (TNFalpha) and thrombin because many pathophysiological conditions, such as sepsis, diabetes, and coronary artery disease, result in the concurrent presence of circulating inflammatory mediators and activated thrombin. We observed a remarkable synergy in the expression of tissue factor by thrombin plus TNFalpha. This was due to altered regulation of the transcription factors c-Jun and c-Fos. The activation of c-Jun was greater and more sustained than that obtained with either thrombin or TNFalpha alone. Thrombin-stimulated expression of c-Fos was both enhanced and prolonged by the concurrent presence of TNFalpha. These changes support the increased availability of c-Jun/c-Fos AP-1 complexes for mediating transcription at the tissue factor promoter. Transcription factors downstream of the extracellular signal-regulated kinases as well as changes in NFkappaB regulation were not involved in the synergistic increase in tissue factor expression by thrombin and TNFalpha. Thus, concurrent exposure of vascular endothelial cells to cytokines and procoagulant proteases such as thrombin can result in greatly enhanced tissue factor expression on the endothelium, thereby perpetuating the prothrombotic phenotype of the endothelium.

Serum level of the antiinflammatory cytokine interleukin-10 is an important prognostic determinant in patients with acute coronary syndromes

BACKGROUND

Convincing evidence suggests that atherosclerosis is an inflammatory disease. The inflammatory response is an important determinant of atherosclerotic plaque instability. Therefore, we investigated the prognostic impact of key inflammatory players, namely the inflammatory marker C-reactive protein (CRP) and the antiinflammatory cytokine interleukin-10 (IL-10), in patients with acute coronary syndromes.

METHODS AND RESULTS

IL-10, CRP, and troponin T were measured at baseline and before discharge in 547 patients enrolled in the placebo group of the c7E3 Anti Platelet Therapy in Unstable Refractory angina (CAPTURE) trial. Death and nonfatal myocardial infarction were recorded during 6-month follow-up. IL-10 levels did not correlate with troponin T concentrations but were inversely correlated with CRP levels (P<0.001). Patients with elevated IL-10 levels (>3.5 pg/mL; n=276) were at significantly lower risk compared with patients with elevated IL-10 levels (hazard ratio, 0.33; 95% confidence interval [CI], 0.25 to 0.76; P=0.002). The predictive value of IL-10 was independent of myocardial necrosis but significantly interacted with CRP levels. CRP-positive patients with IL-10 serum levels above the calculated threshold value of 3.5 pg/mL were protected from the increased cardiac risk of CRP-positive patients with low IL-10 levels (adjusted hazard ratio, 0.25; 95% CI, 0.10 to 0.63; P=0.003). Moreover, discharge IL-10 levels >2.5 pg/mL were associated with lower cardiac risk during 6-month follow-up (hazard ratio, 0.38; 95% CI, 0.19 to 0.83; P=0.005).

CONCLUSIONS

Elevated IL-10 serum levels are associated with a more favorable prognosis in patients with acute coronary syndromes and elevated CRP levels. These data demonstrate the importance of the balance between proinflammatory and antiinflammatory markers as a major determinant of patients' outcome in acute coronary syndromes.