Enhanced levels of CD154 (CD40 ligand) on platelets in patients with chronic heart failure

Immune checkpoints in cardiac physiology and pathology: therapeutic targets for heart failure

Immune checkpoint molecules are physiological regulators of the adaptive immune response. Immune checkpoint inhibitors (ICIs), such as monoclonal antibodies targeting programmed cell death protein 1 or cytotoxic T lymphocyte-associated protein 4, have revolutionized cancer treatment and their clinical use is increasing. However, ICIs can cause various immune-related adverse events, including acute and chronic cardiotoxicity. Of these cardiovascular complications, ICI-induced acute fulminant myocarditis is the most studied, although emerging clinical and preclinical data are uncovering the importance of other ICI-related chronic cardiovascular complications, such as accelerated atherosclerosis and non-myocarditis-related heart failure. These complications could be more difficult to diagnose, given that they might only be present alongside other comorbidities. The occurrence of these complications suggests a potential role of immune checkpoint molecules in maintaining cardiovascular homeostasis, and disruption of physiological immune checkpoint signalling might thus lead to cardiac pathologies, including heart failure. Although inflammation is a long-known contributor to the development of heart failure, the therapeutic targeting of pro-inflammatory pathways has not been successful thus far. The increasingly recognized role of immune checkpoint molecules in the failing heart highlights their potential use as immunotherapeutic targets for heart failure. In this Review, we summarize the available data on ICI-induced cardiac dysfunction and heart failure, and discuss how immune checkpoint signalling is altered in the failing heart. Furthermore, we describe how pharmacological targeting of immune checkpoints could be used to treat heart failure.

PEAL Score to Predict the Mortality Risk of Cardiogenic Shock in the Emergency Department: An Observational Study

BACKGROUND

The in-hospital mortality of cardiogenic shock (CS) remains high (28% to 45%). As a result, several studies developed prediction models to assess the mortality risk and provide guidance on treatment, including CardShock and IABP-SHOCK II scores, which performed modestly in external validation studies, reflecting the heterogeneity of the CS populations. Few articles established predictive scores of CS based on Asian people with a higher burden of comorbidities than Caucasians. We aimed to describe the clinical characteristics of a contemporary Asian population with CS, identify risk factors, and develop a predictive scoring model.

METHODS

A retrospective observational study was conducted between 2014 and 2019 to collect the patients who presented with all-cause CS in the emergency department of a single medical center in Taiwan. We divided patients into subgroups of CS related to acute myocardial infarction (AMI-CS) or heart failure (HF-CS). The outcome was all-cause 30-day mortality. We built the prediction model based on the hazard ratio of significant variables, and the cutoff point of each predictor was determined using the Youden index. We also assessed the discrimination ability of the risk score using the area under a receiver operating characteristic curve.

RESULTS

We enrolled 225 patients with CS. One hundred and seven patients (47.6%) were due to AMI-CS, and ninety-eight patients among them received reperfusion therapy. Forty-nine patients (21.8%) eventually died within 30 days. Fifty-three patients (23.55%) presented with platelet counts < 155 × 103/μL, which were negatively associated with a 30-day mortality of CS in the restrictive cubic spline plot, even within the normal range of platelet counts. We identified four predictors: platelet counts < 200 × 103/μL (HR 2.574, 95% CI 1.379-4.805, p = 0.003), left ventricular ejection fraction (LVEF) < 40% (HR 2.613, 95% CI 1.020-6.692, p = 0.045), age > 71 years (HR 2.452, 95% CI 1.327-4.531, p = 0.004), and lactate > 2.7 mmol/L (HR 1.967, 95% CI 1.069-3.620, p = 0.030). The risk score ended with a maximum of 5 points and showed an AUC (95% CI) of 0.774 (0.705-0.843) for all patients, 0.781 (0.678-0.883), and 0.759 (0.662-0.855) for AMI-CS and HF-CS sub-groups, respectively, all p < 0.001.

CONCLUSIONS

Based on four parameters, platelet counts, LVEF, age, and lactate (PEAL), this model showed a good predictive performance for all-cause mortality at 30 days in the all patients, AMI-CS, and HF-CS subgroups. The restrictive cubic spline plot showed a significantly negative correlation between initial platelet counts and 30-day mortality risk in the AMI-CS and HF-CS subgroups.

Protective Role of Platelets in Myocardial Infarction and Ischemia/Reperfusion Injury

Thrombotic occlusion of the coronary artery is a key component in the pathogenesis of myocardial ischemia and myocardial infarction (MI). The standard therapy for ischemia is revascularization and restoration of blood flow to previously ischemic myocardium. Paradoxically, reperfusion may result in further tissue damage called ischemia/reperfusion injury (IRI). Platelets play a major role in the pathogenesis of MI and IRI, since they contribute to the thrombus and microthrombi formation, inflammation, release of immunomodulatory mediators, and vasoconstrictive molecules. Antiplatelet therapies have proven efficacy in the prevention of thrombosis and play a protective role in cardiac IRI. Beyond the deterioration effect of platelets in MI and IRI, in the 90s the first reports on a protective effect of molecules released from platelets during MI appeared. However, the role of platelets in cardioprotection is still poorly understood. This review describes the involvement of platelets in MI, IRI, and inflammation. It mainly focuses on the protective role of platelets in MI and IRI. Platelets are involved in cardioprotection based on platelet-releasing molecules and antiplatelet therapy, apart from antiaggregatory effects. Additionally, the use of platelet-derived microparticles as possible markers of MI, with and without comorbidities, and their role in cardioprotection are discussed. This review is aimed at illustrating the present knowledge on the role of platelets in MI and IRI, especially in a context of cardioprotection.

Platelet Activity and Its Correlation with Inflammation and Cell Count Readings in Chronic Heart Failure Patients with Reduced Ejection Fraction

Background and objectives: There has been an increasing interest in the role of inflammation in thrombosis complications in chronic heart failure (HF) patients. The incidence of thrombosis in HF has been shown to be the highest in patients classified as NYHA IV (New York Heart association). It is stated that inflammation is regulated by platelet-induced activation of blood leukocytes. We aimed to compare the platelet and cell count readings in chronic HF with reduced ejection fraction (HFrEF) patients according to NYHA functional class and to evaluate the correlation between those readings. Materials and methods: A total of 185 patients were examined. The results of heart echoscopy (TEE) testing; fibrinogen, N-terminal pro b-type natriuretic peptide (NT-proBNP), C reactive protein (CRP), and cortisol concentrations; complete blood counts; and a 6 min walking test were assessed and platelet aggregation was determined. Results: Mean platelet volume (MPV) increased with deterioration of a patient’s state (p < 0.005). Lymphocyte count and percentage were the lowest in the NYHA IV group (p < 0.005). Neutrophil and monocyte percentage and count were the highest (p < 0.045) in the NYHA IV group. Adenosine diphosphate (ADP)- and ADR-induced platelet aggregation was higher in the NYHA III group compared to NYHA II and I groups (p < 0.023). NYHA functional class correlated with mean platelet volume (MPV) (r = 0.311, p = 0.0001), lymphocyte count (r = −0.186, p = 0.026), monocyte count (p = 0.172, p = 0.041), and percentage (r = 0.212, p = 0.011). CRP concentration correlated with NT-proBNP (r = 0.203, p = 0.005). MPV correlated with fibrinogen concentration (r = 0.244, p = 0.004). Conclusions: (1) MPV could be considered as an additional reading reflecting a patient’s condition, however the use of MPV to identify patients at risk of hypercoagulable state should be evaluated in more extensive studies; (2) increased neutrophil and monocyte counts could indicate a higher inflammatory state in chronic HFrEF.

Circulating Biomarkers of Cell Adhesion Predict Clinical Outcome in Patients with Chronic Heart Failure

Cardiovascular inflammation and vascular endothelial dysfunction are involved in chronic heart failure (CHF), and cellular adhesion molecules are considered to play a key role in these mechanisms. We evaluated temporal patterns of 12 blood biomarkers of cell adhesion in patients with CHF. In 263 ambulant patients, serial, tri-monthly blood samples were collected during a median follow-up of 2.2 (1.4-2.5) years. The primary endpoint (PE) was a composite of cardiovascular mortality, HF hospitalization, heart transplantation and implantation of a left ventricular assist device and was reached in 70 patients. We selected the baseline blood samples in all patients, the two samples closest to a PE, or, for event-free patients, the last sample available. In these 567 samples, associations between biomarkers and PE were investigated by joint modelling. The median age was 68 (59-76) years, with 72% men and 74% New York Heart Association class I-II. Repeatedly measured levels of Complement component C1q receptor (C1qR), Cadherin 5 (CDH5), Chitinase-3-like protein 1 (CHI3L1), Ephrin type-B receptor 4 (EPHB4), Intercellular adhesion molecule-2 (ICAM-2) and Junctional adhesion molecule A (JAM-A) were independently associated with the PE. Their rates of change also predicted clinical outcome. Level of CHI3L1 was numerically the strongest predictor with a hazard ratio (HR) (95% confidence interval) of 2.27 (1.66-3.16) per SD difference in level, followed by JAM-A (2.10, 1.42-3.23) and C1qR (1.90, 1.36-2.72), adjusted for clinical characteristics. In conclusion, temporal patterns of C1qR, CDH5, CHI3L1, EPHB4, ICAM2 and JAM-A are strongly and independently associated with clinical outcome in CHF patients.

The Role of Antithrombotic Therapy in Heart Failure

Heart failure is a major contributor to global morbidity and mortality burden affecting approximately 1-2% of adults in developed countries, mounting to over 10% in individuals aged >70 years old. Heart failure is characterized by a prothrombotic state and increased rates of stroke and thromboembolism have been reported in heart failure patients compared with the general population. However, the impact of antithrombotic therapy on heart failure remains controversial. Administration of antiplatelet or anticoagulant therapy is the obvious (and well-established) choice in heart failure patients with cardiovascular comorbidity that necessitates their use, such as coronary artery disease or atrial fibrillation. In contrast, antithrombotic therapy has not demonstrated any clear benefit when administered for heart failure per se, i.e. with heart failure being the sole indication. Randomized studies have reported decreased stroke rates with warfarin use in patients with heart failure with reduced left ventricular ejection fraction, but at the expense of excessive bleeding. Non-vitamin K oral anticoagulants have shown a better safety profile in heart failure patients with atrial fibrillation compared with warfarin, however, current evidence about their role in heart failure with sinus rhythm is inconclusive and further research is needed. In the present review, we discuss the role of antithrombotic therapy in heart failure (beyond coronary artery disease), aiming to summarize evidence regarding the thrombotic risk and the role of antiplatelet and anticoagulant agents in patients with heart failure.

Dose-dependent decrease of platelet activation and tissue factor by omega-3 polyunsaturated fatty acids in patients with advanced chronic heart failure

Chronic heart failure (CHF) is characterised by activation of neuroendocrine and inflammatory pathways, and both are linked to a prothrombotic state. Treatment with omega-3 polyunsaturated fatty acids (n3-PUFA) showed significant benefits including mortality reduction in CHF, but exact mechanisms of action are still unclear. We investigated the effects of n3-PUFA on markers of platelet activation and thrombogenesis in patients with severe CHF. Thirty-six patients with non-ischaemic CHF (LVEF<35%, NYHA class>2) under optimised therapy were randomised to supplementation with 1g/day or 4g/day n3-PUFA, or placebo for 12 weeks. Using whole-blood flow cytometry, monocyteplatelet aggregates characterised by CD14+/CD42b+ co-expression and monocytic tissue factor (TF) were determined. Plasma levels of P-selectin, sCD40L, fibrinogen, prothrombin fragment F1.2, TF and proinflammatory markers (high sensitive[hs] interleukin-6, hsCRP, hsTNFalpha, monocyte chemotactic protein-1) were measured by immunoassay. Supplementation with 1g/day and 4g/day n3-PUFA but not placebo significantly reduced monocyte-platelet aggregates in a dose-dependent manner (p for trend=0.02 across the groups). A dose of 4g/day but not 1g/day n3-PUFA significantly decreased P-selectin (p=0.03). Plasma TF decreased dose-dependently upon n3-PUFA supplementation (p for trend=0.02), paralleled by a significant decrease of TF+-monocytes (p for trend=0.01). The amount of 4g/day n3-PUFA exhibited modest anti-inflammatory effects with a significant reduction of hs interleukin-6 (p<0.01) and a trend-wise reduction of hsTNF-alpha (p=0.09). No changes were seen for sCD40L, fibrinogen, hsCRP and monocyte chemotactic protein-1, while F1.2 was decreased by 4g/day n3-PUFA (P=0.03). In patients with severe non-ischaemic CHF, treatment with n3-PUFA leads to a dose-dependent decrease of platelet activation and TF. Higher dosage exhibits also anti-inflammatory effects.

* ClinicalTrials.gov registration number: NCT00149409

CD40-mediated signalling influences trafficking, T-cell receptor expression, and T-cell pathogenesis, in the NOD model of type 1 diabetes

CD40 plays a critical role in the pathogenesis of type 1 diabetes (T1D). The mechanism of action, however, is undetermined, probably because CD40 expression has been grossly underestimated. CD40 is expressed on numerous cell types that now include T cells and pancreatic β cells. CD40⁺ CD4⁺ cells [T helper type 40 (TH40)] prove highly pathogenic in NOD mice and in translational human T1D studies. We generated BDC2.5.CD40^-/- and re-derived NOD.CD154^-/- mice to better understand the CD40 mechanism of action. Fully functional CD40 expression is required not only for T1D development but also for insulitis. In NOD mice, TH40 cell expansion in pancreatic lymph nodes occurs before insulitis and demonstrates an activated phenotype compared with conventional CD4⁺ cells, apparently regardless of antigen specificity. TH40 T-cell receptor (TCR) usage demonstrates increases in several Vα and Vβ species, particularly Vα3.2⁺ that arise early and are sustained throughout disease development. TH40 cells isolated from diabetic pancreas demonstrate a relatively broad TCR repertoire rather than restricted clonal expansions. The expansion of the Vα/Vβ species associated with diabetes depends upon CD40 signalling; NOD.CD154^-/- mice do not expand the same TCR species. Finally, CD40-mediated signals significantly increase pro-inflammatory Th1- and Th17-associated cytokines whereas CD28 co-stimulus alternatively promotes regulatory cytokines.

Overlooked Mechanisms in Type 1 Diabetes Etiology: How Unique Costimulatory Molecules Contribute to Diabetogenesis

Type 1 Diabetes (T1D) develops when immune cells invade the pancreatic islets resulting in loss of insulin production in beta cells. T cells have been proven to be central players in that process. What is surprising, however, is that classic mechanisms of tolerance cannot explain diabetogenesis; alternate mechanisms must now be considered. T cell receptor (TCR) revision is the process whereby T cells in the periphery alter TCR expression, outside the safety-net of thymic selection pressures. This process results in an expanded T cell repertoire, capable of responding to a universe of pathogens, but limitations are that increased risk for autoimmune disease development occurs. Classic T cell costimulators including the CD28 family have long been thought to be the major drivers for full T cell activation. In actuality, CD28 and its family member counterparts, ICOS and CTLA-4, all drive regulatory responses. Inflammation is driven by CD40, not CD28. CD40 as a costimulus has been largely overlooked. When naïve T cells interact with antigen presenting cell CD154, the major ligand for CD40, is induced. This creates a milieu for T cell (CD40)-T cell (CD154) interaction, leading to inflammation. Finally, defined pathogenic effector cells including TH40 (CD4⁺CD40⁺) cells can express FOXP3 but are not Tregs. The cells loose FOXP3 to become pathogenic effector cells. Each of these mechanisms creates novel options to better understand diabetogenesis and create new therapeutic targets for T1D.

Platelet CD40 contributes to enhanced monocyte chemoattractant protein 1 levels in patients with resistant hypertension

BACKGROUND

Growing evidence shows that inflammation plays a pivotal role in the pathophysiology of essential hypertension (EH). Although it is acknowledged that target organ damage involves an inflammatory response, most work has focused on the role of macrophages. However, recently, platelets were identified as inducing inflammation partly by releasing cytokines. The goal of our study was to evaluate the role of platelets as inflammatory cells in the pathogenesis of EH.

METHODS

Thirty-nine patients with EH and 30 healthy normotensive controls have been examined. Expression of platelet CD40 was measured by flow cytometry. Serum levels of monocyte chemoattractant protein 1 (MCP-1) and sCD40L were measured via a multiplexing assay. In in vitro experiments, activated platelets were cocultured with human umbilical vein endothelial cells (HUVEC) in the presence and absence of anti-CD154 antibodies. MCP-1 in the supernatants was measured by EIA.

RESULTS

Essential hypertension patients showed significantly enhanced MCP-1 levels with highest levels in EH patients with microalbuminuria. EH patients showed increased expression of platelet CD40. In the cell coculture model, activated platelets were able to significantly induce MCP-1 release from HUVEC in a CD40L-dependent manner. EH patients showed elevated sCD40L levels with a positive correlation with MCP-1 levels.

CONCLUSIONS

Platelets can contribute to enhanced MCP-1 levels in EH. MCP-1 is markedly elevated in serum of EH patients with highest levels in patients with microalbuminuria, one early sign of renal target organ damage. Further studies are required to test whether MCP-1 blocking or antiplatelet strategies may represent new therapeutic options in preventing hypertensive target organ damage.

Combining patient proteomics and in vitro cardiomyocyte phenotype testing to identify potential mediators of heart failure with preserved ejection fraction

BACKGROUND

Heart failure with ejection fraction (HFpEF) is a syndrome resulting from several co-morbidities in which specific mediators are unknown. The platelet proteome responds to disease processes. We hypothesize that the platelet proteome will change composition in patients with HFpEF and may uncover mediators of the syndrome.

METHODS AND RESULTS

Proteomic changes were assessed in platelets from hospitalized subjects with symptoms of HFpEF (n = 9), the same subjects several weeks later without symptoms (n = 7) and control subjects (n = 8). Mass spectrometry identified 6102 proteins with five scans with peptide probabilities of ≥0.85. Of the 6102 proteins, 165 were present only in symptomatic subjects, 78 were only found in outpatient subjects and 157 proteins were unique to the control group. The S100A8 protein was identified consistently in HFpEF samples when compared with controls. We validated the fining that plasma S100A8 levels are increased in subjects with HFpEF (654 ± 391) compared to controls (352 ± 204) in an external cohort (p = 0.002). Recombinant S100A8 had direct effects on the electrophysiological and calcium handling profile in human induced pluripotent stem cell-derived cardiomyocytes.

CONCLUSIONS

Platelets may harbor proteins associated with HFpEF. S100A8 is present in the platelets of subjects with HFpEF and increased in the plasma of the same subjects. We further established a bedside-to-bench translational system that can be utilized as a secondary screen to ascertain whether the biomarkers may be an associated finding or causal to the disease process. S100A8 has been linked with other cardiovascular disease such as atherosclerosis and risk for myocardial infarction, stroke, or death. This is the first report on association of S100A8 with HFpEF.

Thrombocytopaenia as a Prognostic Indicator in Heart Failure with Reduced Ejection Fraction

BACKGROUND

Studies suggest that thrombocytopaenia is associated with a higher mortality in several diseases. Little is known about the effect of low platelet count on mortality in patients with heart failure with reduced ejection fraction (HFrEF). The aim of this study was to determine the prognostic value of thrombocytopaenia in these patients by assessing all-cause mortality.

METHODS

A total of 1,907 patients with HFrEF, defined by left ventricular ejection fraction <40% on echocardiography, were analysed in this multi-centre retrospective study. All patients were on medical therapy with a beta-blocker and an angiotensin-converting enzyme inhibitor. Patients were categorised into two groups based on platelet count measured within one month of the diagnosis of HFrEF: normal to mild thrombocytopaenia (platelet count 100,000-450,000 per uL); and moderate to severe thrombocytopaenia (platelet count <100,000 per uL). One-year all-cause mortality was compared between the two groups.

RESULTS

Mean age was 65±15 years and 62% of patients were male. Overall one-year mortality was 17.2% with higher mortality among patients with HFrEF and moderate/severe thrombocytopaenia compared to those with normal/mild thrombocytopaenia (33.0% vs. 15.4%, p <0.001). After adjusting for baseline characteristics, patients with HFrEF and moderate/severe thrombocytopaenia had a higher mortality compared to patients with normal/mild thrombocytopaenia (HR 1.84, 95% CI 1.33-2.56, p <0.001).

CONCLUSION

In patients with HFrEF, higher degree of thrombocytopaenia is associated with higher all-cause mortality. These findings may support the use of platelet counts as a prognostic marker in the assessment of the patient with HFrEF.

A Central Role for Monocyte-Platelet Interactions in Heart Failure

Heart failure (HF) is an increasingly prevalent and costly multifactorial syndrome with high morbidity and mortality rates. The exact pathophysiological mechanisms leading to the development of HF are not completely understood. Several emerging paradigms implicate cardiometabolic risk factors, inflammation, endothelial dysfunction, myocardial fibrosis, and myocyte dysfunction as key factors in the gradual progression from a healthy state to HF. Inflammation is now a recognized factor in disease progression in HF and a therapeutic target. Furthermore, the monocyte-platelet interaction has been highlighted as an important pathophysiological link between inflammation, thrombosis, endothelial activation, and myocardial malfunction. The contribution of monocytes and platelets to acute cardiovascular injury and acute HF is well established. However, their role and interaction in the pathogenesis of chronic HF are not well understood. In particular, the cross talk between monocytes and platelets in the peripheral circulation and in the vicinity of the vascular wall in the form of monocyte-platelet complexes (MPCs) may be a crucial element, which influences the pathophysiology and progression of chronic heart disease and HF. In this review, we discuss the role of monocytes and platelets as key mediators of cardiovascular inflammation in HF, the mechanisms of cell activation, and the importance of monocyte-platelet interaction and complexes in HF pathogenesis. Finally, we summarize recent information on pharmacological inhibition of inflammation and studies of antithrombotic strategies in the setting of HF that can inform opportunities for future work. We discuss recent data on monocyte-platelet interactions and the potential benefits of therapy directed at MPCs, particularly in the setting of HF with preserved ejection fraction.

Correlation between mean platelet volume and B-type natriuretic peptide concentration in emergency patients with heart failure

BACKGROUND

In heart failure patients, mean platelet volume (MPV) may reflect increased platelet activation or increased numbers of large, hyper-aggregable platelets. B-type natriuretic peptide (BNP) concentration in blood is a sensitive and specific marker of heart failure, correlating with the severity and prognosis of illness, in patients presenting with acute dyspnea to the emergency department. This study evaluated the correlation between BNP concentration and MPV.

MATERIAL AND METHODS

Data were collected from 319 patients admitted to the emergency department of a cardiology hospital from January-July 2014. EDTA blood samples drawn at admission were analyzed using automated hematology system, and BNP concentration was measured using a fluorescence immunoassay.

RESULTS

The study included 190 patients with and 129 without acute heart failure (AHF). These groups had BNP concentration of 200-5000 ng/L and 5-98 ng/L, respectively. MPV levels were significantly higher in the AHF group (P<0.001). BNP concentrations were positively correlated with MPV (r=0.41, P<0.001) and neutrophil/lymphocyte ratio (r=0.38, P<0.001).

CONCLUSION

Increased MPV values correlate with BNP concentration, an indicator of HF severity and clinical status, in patients with AHF admitted to the emergency department.

Role of platelets in NOX2 activation mediated by TNFα in heart failure

Tumor necrosis factor (TNF) α may contribute to the deterioration of cardiovascular function in heart failure (HF) through various mechanisms, including the generation of reactive oxygen species (ROS). NADPH oxidase is the major source of ROS in the vascular system, but the interplay between TNFα and NADPH oxidase activation is elusive. As platelets possess NADPH oxidase enzyme, they represent an important tool to investigate the interplay between NADPH oxidase and TNFα in patients with HF. Serum gp91phox (NOX2), the catalytic core of NADPH oxidase, and serum TNFα were measured in 120 HF patients and in 60 healthy subjects. Compared with healthy subjects, HF patients had higher blood levels of NOX2 and TNFα with a progressive increase from NYHA I to NYHA IV classes. NOX2 levels in blood were independently associated with TNFα in HF patients. An in vitro study, performed on platelets from a subgroup of HF patients, shows that TNFα, at concentrations commonly found in HF patients' peripheral circulation, activates platelet NOX2. Thus, TNFα increases ROS production and the extracellular levels of NOX2. These phenomena are inhibited by the NOX2-specific blocking peptide gp91ds-tat. The study provides evidence that circulating NOX2, as well as the activation of NOX2 on platelets, is increased in HF likely as a consequence of the underlying inflammatory process.

The tumor necrosis factor superfamily in heart failure

Numerous clinical studies have established that tumor necrosis factor (TNF)-alpha may play a pathogenic role in the development and progression of heart failure (HF). Recent reports suggest that other ligands in the TNF superfamily could also play a pathogenic role in chronic HF. TNF superfamily ligands are expressed predominantly by cells in the immune system, while the TNF receptor superfamily are expressed by a wide variety of cells, including myocardial cells. Several pathways are activated by ligand-receptor interactions, but of particular importance is the nuclear factor (NF)-kappaB pathway which is activated in the failing human heart. All ligands in the TNF superfamily have the potential to activate NF-kappaB, leading to transcription of genes involved in apoptosis, cell survival, proliferation, inflammation and hypertrophic signaling in cardiomyocytes. Among several TNF superfamily members that are activated in HF, the authors' have recentlyshown that CD40L-CD40 and OPG-RANK-RANKL interactions may be implicated in the pathogenesis of HF through different mechanisms, possibly representing new targets for therapy in this disorder.

Platelets of patients with chronic kidney disease demonstrate deficient platelet reactivity in vitro

Background

In patients with chronic kidney disease studies focusing on platelet function and properties often are non-conclusive whereas only few studies use functional platelet tests. In this study we evaluated a recently developed functional flow cytometry based assay for the analysis of platelet function in chronic kidney disease.

Methods

Platelet reactivity was measured using flow cytometric analysis. Platelets in whole blood were triggered with different concentrations of agonists (TRAP, ADP, CRP). Platelet activation was quantified with staining for P-selectin, measuring the mean fluorescence intensity. Area under the curve and the concentration of half-maximal response were determined.

Results

We studied 23 patients with chronic kidney disease (9 patients with cardiorenal failure and 14 patients with end stage renal disease) and 19 healthy controls. Expression of P-selectin on the platelet surface measured as mean fluorescence intensity was significantly less in chronic kidney disease patients compared to controls after maximal stimulation with TRAP (9.7 (7.9-10.8) vs. 11.4 (9.2-12.2), P = 0.032), ADP (1.6 (1.2-2.1) vs. 2.6 (1.9-3.5), P = 0.002) and CRP (9.2 (8.5-10.8) vs. 11.5 (9.5-12.9), P = 0.004). Also the area under the curve was significantly different. There was no significant difference in half-maximal response between both groups.

Conclusion

In this study we found that patients with chronic kidney disease show reduced platelet reactivity in response of ADP, TRAP and CRP compared to controls. These results contribute to our understanding of the aberrant platelet function observed in patients with chronic kidney disease and emphasize the significance of using functional whole blood platelet activation assays.

Ethylenecarbodiimide-fixed donor splenocyte infusions differentially target direct and indirect pathways of allorecognition for induction of transplant tolerance

Strategic exposure to donor Ags prior to transplantation can be an effective way for inducting donor-specific tolerance in allogeneic recipients. We have recently shown that pretransplant infusion of donor splenocytes treated with the chemical cross-linker ethylenecarbodiimide (ECDI-SPs) induces indefinite islet allograft survival in a full MHC-mismatched model without the need for any immunosuppression. Mechanisms of allograft protection by this strategy remain elusive. In this study, we show that the infused donor ECDI-SPs differentially target T cells with indirect versus direct allospecificities. To target indirect allospecific T cells, ECDI-SPs induce upregulation of negative, but not positive, costimulatory molecules on recipient splenic CD11c(+) dendritic cells phagocytosing the injected ECDI-SPs. Indirect allospecific T cells activated by such CD11c(+) dendritic cells undergo robust initial proliferation followed by rapid clonal depletion. The remaining T cells are sequestered in the spleen without homing to the graft site or the graft draining lymph node. In contrast, direct allospecific T cells interacting with intact donor ECDI-SPs not yet phagocytosed undergo limited proliferation and are subsequently anergized. Furthermore, CD4(+)CD25(+)Foxp3(+) T cells are induced in lymphoid organs and at the graft site by ECDI-SPs. We conclude that donor ECDI-SP infusions target host allogeneic responses via a multitude of mechanisms, including clonal depletion, anergy, and immunoregulation, which act in a synergistic fashion to induce robust transplant tolerance. This simple form of negative vaccination has significant potential for clinical translation in human transplantation.

The significance of immune-related molecule expression profiles in an animal model of Graves' disease

BACKGROUND

The thyrotropin receptor (TSHR) A-subunit has been reported to be a critical autoantigen in the generation of thyroid-stimulating antibodies, thereby causing Graves' disease (GD). However, immune mechanisms associated with GD animal models induced by TSHR A-subunit are poorly understood until now.

METHODS

Female BALB/c mice (n = 23) were randomly divided into two groups, and GD presentation was monitored following injection with either 50 μl phosphate-buffered saline containing 10(9) particles of adenovirus expressing the human TSHR A-subunit (Ad-TSHR289) or the Ad-LacZ control. Expressions of CD40, CD40L, CD80, CD86, CD28, CTLA-4, FOXP3 and IL-17A in various tissues were assessed by quantitative RT-PCR and immunohistochemical assays.

RESULTS

Compared with control group, mice of the hyperthyroid group showed significant elevation of expression in the thyroid of CD40 and CD86, expression in the heart of CD28, CD40 and CD40L and expression in the liver of CD28, CD40 and CD86. Conversely, there was significantly diminished expression of CTLA-4 in the thymus of mice in the hyperthyroid group. Expression of all genes examined was not significantly different in the spleens of mice from either of the groups and CD40L and FOXP3 expression was not detected in the thyroids of hyperthyroid mice.

CONCLUSIONS

The expression profile of multiple immune-related molecules differed in mice in the GD group following Ad-TSHR289 immunization, suggesting that these molecules played a potential role in GD pathogenesis.

The PPAR-Platelet Connection: Modulators of Inflammation and Potential Cardiovascular Effects

Historically, platelets were viewed as simple anucleate cells responsible for initiating thrombosis and maintaining hemostasis, but clearly they are also key mediators of inflammation and immune cell activation. An emerging body of evidence links platelet function and thrombosis to vascular inflammation. peroxisome proliferator-activated receptors (PPARs) play a major role in modulating inflammation and, interestingly, PPARs (PPARβ/δ and PPARγ) were recently identified in platelets. Additionally, PPAR agonists attenuate platelet activation; an important discovery for two reasons. First, activated platelets are formidable antagonists that initiate and prolong a cascade of events that contribute to cardiovascular disease (CVD) progression. Dampening platelet release of proinflammatory mediators, including CD40 ligand (CD40L, CD154), is essential to hinder this cascade. Second, understanding the biologic importance of platelet PPARs and the mechanism(s) by which PPARs regulate platelet activation will be imperative in designing therapeutic strategies lacking the deleterious or unwanted side effects of current treatment options.

Soluble CD40 ligand levels in acute pulmonary embolism: a prospective, randomized, controlled study

CD40 ligand is a thromboinflammatory molecule that predicts cardiovascular events. Platelets constitute the major source of soluble CD40 ligands (sCD40L), which has been shown to influence platelet activation. The main aim of this study was to evaluate sCD40L levels in patients with acute pulmonary embolism (PE). Sixty-five PE patients (32 males, mean age 58 ± 12 years) and 29 healthy controls (15 males, mean age 56 ± 14 years) were enrolled in the study. sCD40L levels were evaluated at the enrollment by ELISA method. Multislice detected pulmonary computed tomography was performed on all patients with a suspected diagnosis of PE. In addition, echocardiography was performed to evaluate right ventricular (RV) dysfunction. There was no statistically significant difference between the two groups regarding demographic features. sCD40L levels were significantly higher in acute PE group compared to healthy controls (5.3 ng/ml and 1.4 ng/ml, respectively; p < 0.001). sCD40L levels of patients with and without RV dysfunction were similar. Correlation analysis between echocardiographic findings and sCD40L levels did not show significant difference. The present study demonstrated a role of sCD40L in pathogenesis of PE for the first time. Further studies are needed to clarify a predictive and prognostic value of sCD40L levels in acute PE patients.

Activation of platelets and cellular coagulation in cerebral small-vessel disease

Platelets and monocytes play a pivotal role in the initiation and progression of large-vessel atherosclerosis. An up-regulation of various platelet and coagulation activation markers has been described in cardiovascular diseases and in patients with acute cerebral ischemia. In the present study the role of platelets and cellular coagulation activation in cerebral small-vessel disease (cSVD) was assessed. In 24 patients with cSVD but without established large-vessel disease, whole blood samples were obtained. Patients were divided into three subgroups (Fazekas 1, 2 and 3) according to extent of cSVD based on morphological magnetic resonance imaging criteria. Surface expression of CD40L and CD62P on platelets, tissue-factor exposition on monocytes and platelet-monocyte aggregates were measured with flow cytometry. Plasma levels of soluble CD40L, interleukin (IL)-6 and IL-7 were assessed by ELISA. Patients with cSVD show a significantly elevated expression of platelet CD40L (P < 0.001) and CD62P (P < 0.023), significantly elevated amounts of platelet-monocyte aggregates (P < 0.004), a significantly enhanced tissue-factor exposition on monocytes (P < 0.019) and significantly lower plasma levels of IL-7 compared to 10 healthy controls. However, this platelet and monocyte activation did not correlate with the severity of cSVD. Patients with cSVD show an up-regulation of the platelet CD40L and CD62P system and an activation of cellular coagulation which might contribute to the initiation and progression of cSVD.

Vascular effects of ultrafine particles in persons with type 2 diabetes

BACKGROUND

Diabetes confers an increased risk for cardiovascular effects of airborne particles.

OBJECTIVE

We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes.

METHODS

In a randomized, double-blind, crossover trial, 19 subjects with type 2 diabetes inhaled filtered air or 50 µg/m³ elemental carbon UFP (count median diameter, 32 nm) by mouthpiece for 2 hr at rest. We repeatedly measured markers of vascular activation, coagulation, and systemic inflammation before and after exposure.

RESULTS

Compared with air, particle exposure increased platelet expression of CD40 ligand (CD40L) and the number of platelet-leukocyte conjugates 3.5 hr after exposure. Soluble CD40L decreased with UFP exposure. Plasma von Willebrand factor increased immediately after exposure. There were no effects of particles on plasma tissue factor, coagulation factors VII or IX, or D-dimer.

CONCLUSIONS

Inhalation of elemental carbon UFP for 2-hr transiently activated platelets, and possibly the vascular endothelium, in people with type 2 diabetes.

Inhibition of progenitor dendritic cell maturation by plasma from patients with peripartum cardiomyopathy: role in pregnancy-associated heart disease

Dendritic cells (DCs) play dual roles in innate and adaptive immunity based on their functional maturity, and both innate and adaptive immune responses have been implicated in myocardial tissue remodeling associated with cardiomyopathies. Peripartum cardiomyopathy (PPCM) is a rare disorder which affects women within one month antepartum to five months postpartum. A high occurrence of PPCM in central Haiti (1 in 300 live births) provided the unique opportunity to study the relationship of immune activation and DC maturation to the etiology of this disorder. Plasma samples from two groups (n = 12) of age- and parity-matched Haitian women with or without evidence of PPCM were tested for levels of biomarkers of cardiac tissue remodeling and immune activation. Significantly elevated levels of GM-CSF, endothelin-1, proBNP and CRP and decreased levels of TGF-beta were measured in PPCM subjects relative to controls. Yet despite these findings, in vitro maturation of normal human cord blood derived progenitor dendritic cells (CBDCs) was significantly reduced (p < 0.001) in the presence of plasma from PPCM patients relative to plasma from post-partum control subjects as determined by expression of CD80, CD86, CD83, CCR7, MHC class II and the ability of these matured CBDCs to induce allo-responses in PBMCs. These results represent the first findings linking inhibition of DC maturation to the dysregulation of normal physiologic cardiac tissue remodeling during pregnancy and the pathogenesis of PPCM.

Inhibition of platelet activation in rats with severe congestive heart failure by a novel endothelial nitric oxide synthase transcription enhancer

AIMS

Increased risk of thrombo-embolic events in congestive heart failure (CHF) has been attributed to a hypercoagulable state including vascular endothelial dysfunction and reduced bioavailability of nitric oxide (NO) as well as platelet activation. We investigated whether treatment with a novel endothelial NO synthase (eNOS)-transcription enhancer positively modulates systemic NO bioavailability and reduces platelet activation in rats with CHF.

METHODS AND RESULTS

After experimental myocardial infarction, male Wistar rats were treated with either placebo or the eNOS-transcription enhancer, AVE9488 (25 ppm/day) for 10 weeks. In rats with severe CHF (left ventricular end-diastolic pressure >15 mmHg), platelet vasodilator-stimulated phosphoprotein (VASP)-phosphorylation reflecting the integrity of the NO/cGMP pathway was significantly reduced (mean immunofluorescence at Ser(157): Sham, 61.4 +/- 9.1; CHF-Placebo, 37.4 +/- 4.9; P < 0.05; Ser(239): Sham, 18.1 +/- 2.5; CHF-Placebo, 13.2 +/- 0.6; P < 0.05). Platelet surface expression of P-selectin and glycoprotein 53 were increased in CHF rats compared with sham-operated animals. Chronic treatment with AVE9488 significantly enhanced platelet VASP-phosphorylation in CHF rats (Ser(157): 70.4 +/- 16.2; Ser(239): 19.3 +/- 1.8). In parallel, platelet surface expression of P-selectin and glycoprotein 53 was reduced in the treatment group.

CONCLUSION

Platelet activation was evident in CHF rats. Therapy with the eNOS-transcription enhancer, AVE9488, reduced platelet activation in parallel to normalization of platelet NO bioavailability.

Soluble, platelet-bound, and total P-selectin as indices of platelet activation in congestive heart failure

BACKGROUND

Many complications associated with congestive heart failure (CHF) have a thrombosis-related aetiology. Platelets play an important role in thrombogenesis, but it is not clear whether circulating platelets actively participate in thrombosis-related complications associated with CHF.

OBJECTIVE

To determine whether soluble P-selectin, platelet surface P-selectin, and total platelet P-selectin as indices of platelet activation in CHF patients-compared to 'disease controls' and 'healthy controls'-and to assess their prognostic value in CHF.

METHODS

We measured soluble P-selectin (sP-sel, by enzyme-linked immunosorbent assay, ELISA), total platelet P-selectin (pP-sel, by a novel 'platelet lysate' assay), platelet surface P-selectin (CD62P%G) and platelet surface CD63 (CD63%G) expression by flow cytometry-in 108 patients with stable congestive heart failure (all with left ventricular ejection fraction (LVEF) <50%). Levels were compared with 50 healthy controls and 70 'disease controls' (patients with coronary artery disease with normal left ventricular systolic function).

RESULTS

CHF patients and disease controls had higher sP-sel, CD62P%G and CD63%G than healthy controls. There were no significant correlations between sP-sel, pP-sel, CD62P%G and CD63%G with ejection fraction (all P>0.05). There were no differences in these markers when ischaemic and non-ischaemic aetiologies of CHF were compared. After a median follow-up of 490 days (range 340-535), there were 7 deaths, 15 hospitalizations for worsening heart failure, 1 for cardiac resynchronization therapy, 4 for revascularizations, 4 for myocardial infarctions, and 1 stroke. None of the platelet markers were predictive of the composite end-point at follow-up.

CONCLUSIONS

Patients with stable CHF exhibit evidence of abnormal platelet activation, despite usage of antiplatelet agents. These abnormalities did not determine prognosis and were broadly similar to those seen in 'disease controls' indicating that platelet abnormalities in CHF may simply be related to associated comorbidities.

Clinical Use and Pathogenetic Basis of Laboratory Tests for the Evaluation of Primary Arterial Hypertension

This review focuses on the laboratory biochemical tests that are useful in the diagnostic approach to the hypertensive patient. A "minimal" diagnostic laboratory work-up, including a small number of tests that are simple and relatively inexpensive, is first described. Because these tests provide basic information on the presence of major cardiovascular (CV) risk factors and target organ damage, and might give some clues to the presence of a secondary form of hypertension (HT), they should be performed on all patients presenting with HT. Other tests that are aimed at assessing the overall CV risk, a major determinant of prognosis that dictates the therapeutic strategy in the individual HT patient, are then discussed. They allow identification of major CV risk factors and associated clinical conditions which, if present, lead to a substantial change of therapeutic strategy. The role of C-reactive protein as a marker of atherosclerosis and its predictive value for CV events are also discussed. Finally, a section is devoted to tests that are currently confined to research purposes, such as markers of endothelial function including endothelin-1, homocysteine and genetic analysis.

Bench-to-bedside review: the value of cardiac biomarkers in the intensive care patient

The use of cardiac biomarkers in the intensive care setting is gaining increasing popularity. There are several reasons for this increase: there is now the facility for point-of-care biomarker measurement providing a rapid diagnosis; biomarkers can be used as prognostic tools; biomarkers can be used to guide therapy; and, compared with other methods such as echocardiography, the assays are easier and much more affordable. Two important characteristics of the ideal biomarker are disease specificity and a linear relationship between the serum concentration and disease severity. These characteristics are not present, however, in the majority of biomarkers for cardiac dysfunction currently available. Those clinically useful cardiac biomarkers, which naturally received the most attention, such as troponins and B-type natriuretic peptide, are not as specific as was originally thought. In the intensive care setting, it is important for the user to understand the degree of specificity of these biomarkers and that the interpretation of the results should always be guided by other clinical information. The present review summarizes the available biomarkers for different cardiac conditions. Potential biomarkers under evaluation are also briefly discussed.

Soluble CD40 ligand and atrial fibrillation: Relationship to platelet activation, and endothelial damage/dysfunction

Increased plasma soluble CD40L (sCD40L) is present in many cardiovascular diseases and predicts poor outcome, but levels in atrial fibrillation (AF) are unknown. Although the platelet is frequently cited as the source of sCD40L, this view is not universal. We hypothesised (a) raised sCD40L in non-rheumatic AF, and (b) that sCD40L correlates with platelet, but not endothelial, markers, thus suggesting a platelet origin. Plasma sCD40L, platelet marker soluble P-selectin and endothelial markers von Willebrand factor (vWf) and soluble E-selectin were measured by ELISA in 54 AF patients free of diabetes or major cardiovascular disease, and in 28 age/sex matched controls. Median (inter-quartile range) sCD40L in AF was 0.82 (0-4.8) ng/mL compared to 0.21 (0-5.5 ng/mL) in controls (p=0.0397). vWf and soluble P-selectin (p<0.005), but not soluble E-selectin, were raised in AF, but none of the indices inter-correlated significantly. We find that sCD40L is marginally raised in AF but the stimulus for this is unclear. The lack of clear correlation with relevant plasma markers suggests that the source is unlikely to be the endothelium or platelet alone.

Disruption of the homeostatic balance between autoaggressive (CD4+CD40+) and regulatory (CD4+CD25+FoxP3+) T cells promotes diabetes

Although regulatory T cells (Tregs) are well described, identifying autoaggressive effector T cells has proven more difficult. However, we identified CD4loCD40+ (Th40) cells as being necessary and sufficient for diabetes in the NOD mouse model. Importantly, these cells are present in pancreata of prediabetic and diabetic NOD mice, and Th40 cells but not CD4+CD40(-) T cells transfer progressive insulitis and diabetes to NOD.scid recipients. Nonobese-resistant (NOR) mice have the identical T cell developmental background as NOD mice, yet they are diabetes-resistant. The seminal issue is how NOR mice remain tolerant to diabetogenic self-antigens. We show here that autoaggressive T cells develop in NOR mice and are confined to the Th40 subset. However, NOR mice maintain Treg numbers equivalent to their Th40 numbers. NOD mice have statistically equal numbers of CD4+CD25+forkhead box P3+intrinsic Tregs compared with NOR or nonautoimmune BALB/c mice, and NOD Tregs are equally as suppressive as NOR Tregs. A critical difference is that NOD mice develop expanded numbers of Th40 cells. We suggest that a determinant factor for autoimmunity includes the Th40:Treg ratio. Mechanistically, NOD Th40 cells have low susceptibility to Fas-induced cell death and unlike cells from NOR and BALB/c mice, have predominantly low Fas expression. CD40 engagement of Th40 cells induces Fas expression but further confers resistance to Fas-mediated cell death in NOD mice. A second fundamental difference is that NOD Th40 cells undergo much more rapid homeostatic expansion than Th40 cells from NOR mice.

Soluble CD40L, platelet surface CD40L and total platelet CD40L in congestive heart failure: relationship to platelet volume, mass and granularity

BACKGROUND

Many complications associated with congestive heart failure (CHF) have a thrombosis-related aetiology, which may involve platelets. The immune modulator pair CD40-CD40L has been proposed to be an important link between inflammation and thrombosis and may be important in the pathophysiology of CHF.

OBJECTIVE

To study soluble CD40L (sCD40L), platelet surface CD40L (%GCD40L) and total platelet CD40L (pCD40L) levels in CHF patients, their relationships to other platelet indices (platelet volume, mass and component) and to assess their prognostic value.

METHODS

We measured sCD40L (by ELISA); pCD40L (by a platelet lysate assay); platelet surface CD40L (%GCD40L) expression by flow cytometry; mean platelet volume (MPV), mean platelet mass (MPM) and mean platelet component (MPC); in 108 patients with stable CHF. Levels were compared with 37 'healthy controls' and 63 'disease controls'. After a median follow-up period of 490 days, clinical endpoints were determined.

RESULTS

pCD40L was significantly higher in CHF than disease controls, but not sCD40L or %GCD40L levels. CHF patients and disease controls had higher MPV (one-way anova, P < 0.0001), whilst MPC was significantly lower in CHF patients (P < 0.0001), compared to healthy controls. All indices related to CD40L (i.e. sCD40L, pCD40L and %GCD40L) were neither related to disease severity or left ventricular ejection function, nor to clinical endpoints at follow-ups.

CONCLUSION

Patients with stable CHF patients did not exhibit enhanced levels of CD40L and the latter did not predict clinical events at follow-up. The lack of difference in CD40L levels between CHF and disease controls suggests that CD40L may not have a major role in CHF per se, but in the comorbidities associated with CHF.

Relationship between CD40 ligand expression and B type natriuretic peptide levels in patients with chronic heart failure

BACKGROUND

Inflammation plays a pathogenic role in the development of chronic heart failure (CHF). Increasing evidence shows that CD40-CD40 ligand (CD40L) interaction plays a pathogenic role in inflammatory disorders. We assessed whether CD40 ligand expression was abnormal in patients with CHF.

METHODS

Twenty normal controls and 86 patients with CHF were investigated. The expression of CD40L on platelets was analyzed by indirect-immunofluorescence flow cytometry, and the soluble CD40L (sCD40L) level was determined by a commercially available enzyme-linked immunosorbent assay (ELISA). B type natriuretic peptide (BNP) was measured by radioimmunoassay.

RESULTS

All patients with CHF showed a significant increased expression of CD40L (32.3+/-13.9 MFI) on platelets and sCD40L levels (20.5+/-8.6 microg/l) compared with controls(p<0.0001). CD40L expression on platelets and sCD40L levels positively correlated with New York Heart Association (NYHA) functional class, left ventricular ejection fraction and BNP levels in CHF.

CONCLUSIONS

Patients with CHF showed increased expression of CD40L system, which may create a pathogenic role in the development and progression of CHF.

CD40/CD40L system and vascular disease

Several distinct lines of investigation in the context of atherosclerosis dealing with low-grade inflammation, oxidative stress and platelet activation are now emerging, with CD40/CD40L system as the missing link. CD40 ligand is a transmembrane glycoprotein structurally related to tumour necrosis factor-alpha and more than 95% of the circulating CD40L derives from platelets. CD40L appears as a multiplayer of several cell types in the inflammatory network. The peculiarity of CD40L as an inflammatory mediator derived from platelets expands the functional repertoire of platelets from players of haemostasis and thrombosis to powerful amplifiers of inflammation by promoting the release of cytokines and chemokines, cell activation and cell-cell interactions. The multifunctional role of CD40L, as a simultaneous activator of all these systems, further blurs the intricate relationship between such events both in the physiological systems and the pathological derangement occurring in atherothrombosis.

Statins in heart failure. Beyond the lipid lowering effect

Statins, the most widely prescribed medications in patients with hyperlipidemia and coronary heart disease, have a number of pleiotropic actions beyond cholesterol lowering. They improve endothelial function, they have antioxidant and anti-inflammatory effects, they regulate neovascularization and have immunomodulatory activities. Experimental evidence suggests that statins may be beneficial in heart failure as they can inhibit myocardial hypertrophy, reduce cardiomyocyte loss by apoptosis, reduce oxidative stress and restore neurohormonal imbalance. Furthermore small randomised clinical trials showed that short term statin administration may improve key pathophysiological aspects of this syndrome. Finally retrospective analyses of large statin trials imply a long term profit on clinical outcome in this group of patients. These results however need to be reviewed with caution as certain studies have demonstrated that low serum cholesterol is associated with worse prognosis in HF and that ubiquinone levels, a micronutrient with antioxidant actions, reduces significantly following statin administration. Large prospective randomised controlled trials are needed to confirm the beneficial effect of statins on cardiovascular outcome in HF patients and further elucidate the contributing mechanisms. Finally the statin dose and the interaction with co-administered drugs need to be studied.

Platelet activation in acute, decompensated congestive heart failure

BACKGROUND

Congestive heart failure (CHF) is associated with increased risk of venous thromboembolism, stroke and sudden death. This may be related to abnormalities of thrombogenesis and platelet activation. A comprehensive assessment of platelet (dys)function in acute decompensated heart failure (AHF) is lacking, and we hypothesised that such patients would show greater abnormalities in platelet indices, compared to stable CHF and healthy controls.

METHODS

We measured soluble P-selectin (sP-sel, by ELISA); platelet surface P-selectin (CD62P%G) and CD63%G expression by flow cytometry; and platelet structural indices [mean platelet volume (MPV), mean platelet mass (MPM) and mean platelet component (MPC)] in 22 patients with AHF (pre- and posttreatment), who were compared to 68 patients with stable congestive heart failure (CHF, all with left ventricular ejection fraction (LVEF) <50%) and 23 healthy controls.

RESULTS

There were significant differences between the 3 study groups in MPV (p<0.001), MPC (p=0.001), platelet surface P-selectin (CD62P%G, p<0.0001) and platelet surface CD63P%G (p=0.017). On post-hoc analyses, AHF patients had higher platelet surface P-selectin (CD62P%G) compared to stable CHF patients and healthy controls (Tukey's test, all p<0.05), whilst CD63%P was similarly high in both disease groups, compared to healthy controls. Platelet surface P-selectin (p=0.032), CD63 (p=0.024) and CD40L (p=0.024) were significantly reduced following treatment of AHF, though platelet morphology and sP-sel levels were not significantly changed.

CONCLUSION

AHF patients demonstrate some abnormalities of platelet activation compared to stable CHF patients and healthy controls. These platelet abnormalities are modified by treatment, raising the possibility that platelets may partly contribute to the pathophysiology of adverse complications associated with AHF.

Platelet membrane CD154 and sCD154 in progressive peripheral arterial disease: A pilot study

OBJECTIVE

The expression and potential role of platelet membrane CD154 and sCD154 in atherosclerosis was investigated in patients with peripheral arterial disease.

METHODS

This prospective observational study measured the expression of platelet-bound CD154 and soluble CD154 (sCD154) in 39 patients with critical limb ischaemia (CLI, n=15), stable intermittent claudication (SIC, n=12) and age-matched controls (AMC, n=12). Basal and agonist-stimulated CD154, P-selectin expression and fibrinogen binding was measured by whole blood flow cytometry, while sCD154 was measured in paired plasma samples by ELISA.

RESULTS

Basal expression of CD154 on the platelet surface was enhanced in both groups of patients with peripheral arterial disease. However, the critical limb ischaemics showed the highest level of basal expression 0.7+/-0.3 [median+/-IQR] and was significantly increased compared to both stable intermittent claudicants and age-matched controls (P<0.001). On agonist stimulation with either ADP or thrombin critical limb ischaemics demonstrated greater platelet reactivity and propensity to express CD154 compared to age-matched controls (P<0.05). Confirmation of the cellular expression of CD154 results was obtained by measuring sCD154 concentrations in autologous plasma samples. Here plasma levels of sCD154 in critical limb ischaemics were significantly greater than both stable intermittent claudicants and age-matched controls (P<0.005).

CONCLUSIONS

Enhanced basal platelet expression and increased propensity to express CD154 and sCD154 in critical limb ischaemics compared to both controls and patients with stable intermittent claudication support evidence for the role of CD154 in atherogenesis and suggest a novel function in progressive and acute peripheral arterial disease.

Antithrombotic therapy in patients with chronic heart failure: rationale, clinical evidence and practical implications

Chronic heart failure (CHF) is traditionally associated with increased risk of thromboembolic complications. Key features of CHF pathophysiology, such as impairment of intracardiac hemodynamics, peripheral blood flow deceleration, neuroendocrine activation, chronic oxidative stress and proinflammatory changes, could explain the predisposition to thromboembolism. However, conclusive epidemiologic data on thromboembolic event incidence in CHF are lacking. Furthermore, the place of antithrombotic therapy in CHF management is still uncertain. Apart from established indications for warfarin (e.g. atrial fibrillation and previous embolic events), there is no robust evidence to support administration of vitamin K antagonists to other patients with CHF, particularly to patients in sinus rhythm. The role of aspirin in preventing thromboembolism in these patients is also controversial. Large randomized trial data on the effectiveness and risks of warfarin and aspirin use in CHF patients with sinus rhythm are forthcoming. This article provides a brief overview of the epidemiologic and pathobiological background of thromboembolism in CHF, and discusses the up-to-date clinical evidence on antithrombotic therapy in detail.

Cardiac function, inflammatory mediators and mortality in critical limb ischemia

Patients with critical limb ischemia (CLI) have a high frequency of concomitant coronary heart disease and congestive heart failure. The aim of the study was to evaluate cardiac function in relation to inflammatory markers and 1-year mortality rate among patients with CLI. The authors investigated 232 consecutive patients with CLI by means of electrocardiogram (ECG), and measurements of endothelin (ET)-1, tumor necrosis factor alpha (TNF)alpha, interleukin (IL)-6, neopterin, CD40 ligand, and 8-epi-prostaglandin (PG)F2alpha in plasma. Echocardiography (echo) was performed in 88 (38%) patients. One-year mortality rate was assessed after prospective follow-up. One hundred and eighty-six (80%) patients had sinus rhythm (SR), 36 (16%) had atrial fibrillation or flutter (AF), and 10 (4%) pacemaker rhythm. Ischemic ECG changes occurred in 143 (62%) patients. Patients with AF showed higher IL-6 (p = 0.0296) and neopterin (p = 0.0494) concentrations. Patients with ischemic ECG changes showed higher ET-1 (p = 0.0303), 8-epi-PGF2alpha (p = 0.0027), neopterin (p = 0.0004) concentrations and 1-year mortality rate (p = 0.0105). The difference in ET-1 remained in logistic regression (p = 0.0152). Internal diameter of the left ventricle on echo correlated with IL-6 (r = 0.345, p = 0.0017), TNFalpha (r = 0.240, p = 0.0273), and neopterin (r = 0.327, p = 0.0028). Internal diameter of the left atrium correlated with TNFalpha (r = 0.384, p = 0.0092) and neopterin (r = 0.526, p = 0.0004), and ejection fraction (EF) correlated inversely with IL-6 (r = -0.380, p = 0.0015) and neopterin (r = -0.346, p = 0.0038). Patients with EF <40% showed higher (p = 0.0462) 1-year mortality rate than patients with EF >40%. In conclusion, in critical limb ischemia, cardiac rhythm disturbances and ischemic ECG changes were related to inflammatory mediators and predicted 1-year mortality rate. The inflammatory mediators correlated with echocardiographic signs of congestive heart failure.

Antithrombotic therapy for congestive heart failure

Patients with congestive heart failure (CHF) are at increased risk of thromboembolic events. However, there is much debate and uncertainty over the use of antithrombotic therapy in these patients. The evidence for oral anticoagulation is limited, although large randomised trial data are forthcoming. Aspirin may be detrimental for heart failure due to a possible interaction with angiotensin-converting enzyme inhibitors, leading to increased hospitalisations from decompensated heart failure. The objective of this review article is to summarise the available evidence regarding the risk of stroke and thromboembolic events in CHF patients, as well as the effectiveness and risks of antithrombotic therapy in these patients.

Rosuvastatin Reduces Platelet Activation in Heart Failure

OBJECTIVES

Endothelial dysfunction and platelet activation are part of the cardiovascular phenotype in congestive heart failure (CHF). We investigated whether 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibition would beneficially modulate vascular NO bioavailability and platelet activation in experimental CHF.

METHODS AND RESULTS

Chronic myocardial infarction was induced by coronary ligation in male Wistar rats. Animals were either treated with placebo or the HMG-CoA reductase inhibitor rosuvastatin. After 10 weeks, hemodynamic assessment was performed and endothelial function was determined in organ bath studies. NO bioavailability was assessed by in vivo platelet vasodilator-stimulated phosphoprotein (VASP) phosphorylation. Markers of platelet degranulation (surface expression of P-selectin and glycoprotein 53) were determined as well as the amount of circulating platelet-leukocyte aggregates. Endothelium-dependent, acetylcholine-induced vasorelaxation was significantly impaired in aortic rings from CHF rats and improved by rosuvastatin. In parallel, in vivo VASP phosphorylation reflecting NO bioavailability was significantly attenuated in platelets from CHF rats and normalized by rosuvastatin. Platelet activation, which was increased in CHF, was reduced by treatment with rosuvastatin.

CONCLUSIONS

HMG-CoA reductase inhibition improved endothelial function, increased systemic NO bioavailability and inhibited exaggerated platelet activation in CHF rats. These mechanisms may contribute to the beneficial effects of statin treatment in CHF.

Novel markers for heart failure diagnosis and prognosis

PURPOSE OF REVIEW

This paper reviews recent advances in heart failure biomarkers for identification of disease precursors, subclinical disease, and onset or progression of overt disease.

RECENT FINDINGS

Heart failure biomarkers can be categorized empirically as neurohormonal mediators, markers of myocyte injury and remodeling, and indicators of systemic inflammation. Brain natriuretic peptide is the most widely studied, with a potentially important but evolving role for determining prognosis and as a surrogate endpoint in clinical trials. Strong evidence exists for use of brain natriuretic peptide in the diagnosis of acute heart failure and for improved clinical outcomes with a brain natriuretic peptide-guided approach to heart failure care. The use of brain natriuretic peptide as a screening tool for asymptomatic left ventricular systolic dysfunction, or to distinguish systolic from diastolic heart failure, is not supported by current data. Markers of myocyte injury, including troponins, heart-type fatty acid binding protein, and myosin light chain-1, may further improve heart failure prognostication in conjunction with plasma brain natriuretic peptide. Biomarkers of matrix remodeling and inflammation have emerged as potential preclinical indicators to identify individuals at risk of developing clinical heart failure. A role for cellular adhesion molecules may also emerge in identifying those at risk for cardiovascular thrombotic complications, such as stroke.

SUMMARY

The spectrum of heart failure biomarkers and their potential clinical applications continues to grow. Ongoing research on multimarker strategies will likely identify biomarker combinations that are optimal at various stages during the evolution of heart failure, ranging from their use for screening, diagnosis, determining prognosis, and guiding management.