Growth-differentiation factor-15 for early risk stratification in patients with acute chest pain

Evaluation of Arterial Stiffness Parameters and the Growth Differentiation Factor-15 Level in Patients with Premature Myocardial Infarction

BACKGROUND

Myocardial infarction (MI) is increasing at a younger age. Growth differentiation factor-15 (GDF-15) has been implicated in several key mechanisms of atherogenesis. Arterial stiffness parameters, including pulse wave velocity (PWV) and the augmentation index (AIx), can indicate the presence or progression of atherosclerosis. The aim of this study is to evaluate the GDF-15 level and arterial stiffness parameters in patients with premature MI.

METHOD

Thirty patients aged ≤45 years (mean age: 39 ± 5 years, 23 male) who recovered from a MI and 15 age and sex-matched subjects were consecutively included. The serum GDF-15 concentration levels and arterial stiffness parameters of the patients and controls were measured.

RESULTS

GDF-15 levels were significantly higher in patients with premature MI, while there were no significant differences in PWV and AIx between the groups. The GDF-15 level was correlated negatively with high-density lipoprotein (HDL) cholesterol and positively with uric acid levels. Both GDF-15 (p = 0.046, odds ratio: 1.092, 95% confidence interval: 1.003-1.196) and HDL cholesterol (p = 0.037, odds ratio: 0.925, 95% confidence interval: 0.859-0.995) were found as independent factors associated with premature MI.

CONCLUSIONS

GDF-15 could be a risk factor for premature MI. Further studies are needed to elucidate the central role of GDF-15 in the pathophysiology of early atherosclerosis and MI in the young population.

Growth differentiation factor 15 and cardiovascular risk: individual patient meta-analysis

AIMS

Levels of growth differentiation factor 15 (GDF-15), a cytokine secreted in response to cellular stress and inflammation, have been associated with multiple types of cardiovascular (CV) events. However, its comparative prognostic performance across different presentations of atherosclerotic cardiovascular disease (ASCVD) remains unknown.

METHODS AND RESULTS

An individual patient meta-analysis was performed using data pooled from eight trials including 53 486 patients. Baseline GDF-15 concentration was analyzed as a continuous variable and using established cutpoints (<1200 ng/L, 1200-1800 ng/L, > 1800 ng/L) to evaluate its prognostic performance for CV death/hospitalization for heart failure (HHF), major adverse cardiovascular events (MACE), and their components using Cox models adjusted for clinical variables and established CV biomarkers. Analyses were further stratified on ASCVD status: acute coronary syndrome (ACS), stabilized after recent ACS, and stable ASCVD. Overall, higher GDF-15 concentration was significantly and independently associated with an increased rate of CV death/HHF and MACE (P < 0.001 for each). However, while GDF-15 showed a robust and consistent independent association with CV death and HHF across all presentations of ASCVD, its prognostic association with future myocardial infarction (MI) and stroke only remained significant in patients stabilized after recent ACS or with stable ASCVD [hazard ratio (HR): 1.24, 95% confidence interval (CI): 1.17-1.31 and HR: 1.16, 95% CI: 1.05-1.28 for MI and stroke, respectively] and not in ACS (HR: 0.98, 95% CI: 0.90-1.06 and HR: 0.87, 95% CI: 0.39-1.92, respectively).

CONCLUSION

Growth differentiation factor 15 consistently adds prognostic information for CV death and HHF across the spectrum of ASCVD. GDF-15 also adds prognostic information for MI and stroke beyond clinical risk factors and cardiac biomarkers but not in the setting of ACS.

Growth differentiation factor-15, a novel systemic biomarker of oxidative stress, inflammation, and cellular aging: Potential role in cardiovascular diseases

Growth differentiation factor-15 (GDF-15) is a cytokine upregulated in multiple pathological conditions where oxidative stress, endothelial dysfunction, tissue aging, and chronic inflammation are the hallmarks. GDF-15 has many sources of production, including cardiac and vascular myocytes, endothelial cells, adipocytes and macrophages in response to metabolic stress, oncogenic transformation and the burden of proinflammatory cytokines or reactive oxygen species. Although the main sources of GDF-15 are extracardiac tissues, it has been shown to be elevated in many cardiac disorders. In experimental models of heart disease, GDF-15 release is induced after an ischemic insult and in pressure overload scenarios. Likewise, in recent years, an increasing body of evidence has emerged linking GDF-15 to the risk of mortality in acute coronary syndromes, atrial fibrillation and heart failure. Additionally, GDF-15 has been shown to add prognostic information beyond other conventional biomarkers such as natriuretic peptides and cardiac troponins. Further studies are needed to assess whether the incorporation of GDF-15 into clinical practice can improve cardiovascular outcomes.

Growth differentiation factor-15 is a prognostic marker in patients with intermediate coronary artery disease

BACKGROUND

Growth differentiation factor-15 (GDF-15) is involved in multiple processes that are associated with coronary artery disease (CAD). However, little is known about the association between GDF-15 and the future ischemic events in patients with intermediate CAD. This study was conducted to investigate whether plasma GDF-15 constituted risk biomarkers for future cardiovascular events in patients with intermediate CAD.

METHODS

A prospective study was performed based on 541 patients with intermediate CAD (20%-70%). GDF-15 of each patient was determined in a blinded manner. The primary endpoint was major adverse cardiac event (MACE), which was defined as a composite of all-cause death, nonfatal myocardial infarction, revascularization and readmission due to angina pectoris.

RESULTS

After a median follow-up of 64 months, 504 patients (93.2%) completed the follow-up. Overall, the combined endpoint of MACE appeared in 134 patients (26.6%) in the overall population: 26 patients died, 11 patients suffered a nonfatal myocardial infarction, 51 patients underwent revascularization, and 46 patients were readmitted for angina pectoris. The plasma levels of GDF-15 (median: 1172.02 vs. 965.25 pg/mL, P = 0.014) were higher in patients with ischemic events than those without events. After adjusting for traditional risk factors, higher GDF-15 levels were significantly associated with higher incidence of the composite endpoint of MACE (HR = 1.244, 95% CI: 1.048-1.478, Quartile 4 vs. Quartile 1, P = 0.013).

CONCLUSIONS

The higher level of GDF-15 was an independent predictor of long-term adverse cardiovascular events in patients with intermediate CAD.

Growth Differentiation Factor-15 (GDF-15) Is Associated With Mortality in Ischemic Stroke Patients Treated With Acute Revascularization Therapy

Background and Aims: Growth differentiation factor-15 (GDF-15) has been identified as a robust marker of developing cardiovascular disease, however, little is currently known about its prognostic value in stroke patients. In a context of growing interest to discover new biomarkers in stroke, we aimed to assess the association between circulating GDF-15 levels and three-month mortality in ischemic stroke patients treated with acute revascularization therapy.

Methods: 173 patients hospitalized for acute ischemic stroke and treated with either intravenous thrombolysis (n = 99, 57.2%), mechanical thrombectomy (n = 41, 23.4%) or combined therapy (n = 33, 19.1%) were prospectively included. Baseline clinical and biological characteristics were recorded. Plasma GDF-15 levels were measured at admission (D0), and at 24 h, 3 and 7 days. Clinical severity was assessed with the National Institutes of Health Stroke Scale (NIHSS) score, and vital status was obtained 3 months after the stroke.

Results: At 3 months post-stroke, 32 patients (18.5%) had died. The deceased patients had higher D0 plasma GDF-15 levels (median [IQR]: 2,777 [1,769–5,446] vs. 1,460 [965–2,079] pg/mL, P < 0.001). In multivariable logistic regression analysis, D0 GDF-15 levels in the third tertile of the distribution were independently associated with mortality at 3 months (OR = 3.71; 95% CI: 1.09–12.6, P = 0.036), even after adjustment for confounding variables including clinical severity.

Conclusions: Our data show for the first time that GDF-15 plasma concentration at admission is independently associated with 3-month mortality in ischemic stroke patients treated with acute revascularization therapy. The pathophysiological mechanisms that could explain this association warrant further study.

Growth-differentiation factor-15 predicts adverse cardiac events in patients with acute coronary syndrome: A meta-analysis

BACKGROUND

We aimed to analyse the association between high-level growth-differentiation factor-15 (GDF-15) and mortality, recurrent MI and heart failure compared to low-level GDF-15 in patients with acute coronary syndrome (ACS).

METHODS

PubMed and EMBASE were searched from their commencement to December 2017 for qualified studies that evaluated the associations between GDF-15 and ACS. Risk ratios were synthesized with random effect meta-analysis. Publication bias and sensitivity analyses were also conducted.

RESULTS

A total of thirteen studies and 43,547 participants were analyzed systematically in our meta-analysis. Our study showed a significant association between GDF-15 values and mortality (p = 0.000, RR = 6.75, 95% CI = 5.81-7.84) and recurrent MI (p = 0.000, RR = 1.95, 95% CI = 1.72-2.21) in the overall analyses. Subgroup analyses revealed similar results. However, there was evidence of heterogeneity in the study of heart failure, whose overall RR was 6.66, with an I² of 87.3%.

CONCLUSION

There was a significant association between high-level GDF-15 and mortality, recurrent MI in patients with ACS. We need more data to research the risk stratification of heart failure in ACS patients in the future.

Antibodies against MYC-Associated Zinc Finger Protein: An Independent Marker in Acute Coronary Syndrome?

Introduction

Atherosclerosis is considered the pathophysiology underlying cardiovascular (CVD), cerebrovascular, and peripheral vascular diseases. Evidence supporting an autoimmune component is emerging, with imaging studies correlating MYC-associated zinc finger protein antibody (MAZ-Ab) optical density (OD) with plaque activity. This study compares MAZ-Ab OD on ELISA testing among patients presenting with acute coronary syndromes (ACSs) to healthy controls and investigates the association of MAZ-Ab to traditional CVD risk factors.

Methods

Patients admitted with ACSs between August 2007 and July 2011 were included. Serum samples taken at presentation were retrospectively tested for MAZ-Ab and compared with serum from healthy volunteers with no CVD risk factors. Large-scale assessment of post-ACS prognostic relevance was performed using the established PLATO cohort.

Results

In total 174 ACS patients and 96 controls were included. Among ACS patients, median MAZ-Ab OD was higher compared with controls (0.46 vs. 0.27; p = 0.001). Although the majority of ACS patients (116/174; 67%) had suffered from a ST-elevation myocardial infarction, no significant differences in MAZ-Ab titers were evident between ACS subtypes (p = 0.682). No associations between MAZ-Ab OD and conventional CVD risk factors were identified. Large-scale testing revealed no prognostic stratification regarding reinfarction (OR 1.04 [95% CI: 0.94–1.16]; p = 0.436).

Conclusion

MAZ-Ab OD was higher or all ACS phenotypes compared with controls. Given current understanding of MAZ-Ab function, these findings support an autoimmune component to CVD independent of conventional risk factors and indeed the extent of end-organ damage.

GDF-15 predicts cardiovascular events in acute chest pain patients

Background

Treatment of patients presenting with possible acute myocardial infarction (AMI) is based on timely diagnosis and proper risk stratification aided by biomarkers. We aimed at evaluating the predictive value of GDF-15 in patients presenting with symptoms suggestive of AMI.

Methods

Consecutive patients presenting with suspected AMI were enrolled in three study centers. Cardiovascular events were assessed during a follow-up period of 6 months with a combined endpoint of death or MI.

Results

From the 1818 enrolled patients (m/f = 1208/610), 413 (22.7%) had an acute MI and 63 patients reached the combined endpoint. Patients with MI and patients with adverse outcome had higher GDF-15 levels compared with non-MI patients (967.1pg/mL vs. 692.2 pg/L, p<0.001) and with event-free patients (1660 pg/mL vs. 756.6 pg/L, p<0.001). GDF-15 levels were lower in patients with SYNTAX score ≤ 22 (797.3 pg/mL vs. 947.2 pg/L, p = 0.036). Increased GDF-15 levels on admission were associated with a hazard ratio of 2.1 for death or MI (95%CI: 1.67–2.65, p<0.001) in a model adjusted for age and sex and of 1.57 (1.13–2.19, p = 0.008) adjusted for the GRACE score variables. GDF-15 showed a relevant reclassification with regards to the GRACE score with an overall net reclassification index (NRI) of 12.5% and an integrated discrimination improvement (IDI) of 14.56% (p = 0.006).

Conclusion

GDF-15 is an independent predictor of future cardiovascular events in patients presenting with suspected MI. GDF-15 levels correlate with the severity of CAD and can identify and risk-stratify patients who need coronary revascularization.

Growth Differentiation Factor 15 May Predict Mortality of Peripheral and Coronary Artery Diseases and Correlate with Their Risk Factors

Plasma GDF15 concentrations were measured in 612 Taiwanese individuals without overt systemic disease. Clinical parameters, GDF15 genetic variants, and 22 biomarker levels were analyzed. We further enrolled 86 patients with PAD and 481 patients with CAD, who received endovascular intervention and coronary angiography, respectively, to examine the role of GDF15 level in predicting all-cause mortality. Significant associations were found between GDF15 genotypes/haplotypes and GDF15 levels. The circulating GDF15 level was positively associated with age, smoking, hypertension, and diabetes mellitus as well as circulating levels of lipocalin 2 and various biomarkers of inflammation and oxidative stress. Kaplan-Meier survival analysis showed that baseline GDF15 levels of above 3096 pg/mL and 1123 pg/mL were strong predictors of death for patients with PAD and CAD, respectively (P = 0.011 and P < 0.001). GDF15 more accurately reclassified 17.3% and 29.2% of patients with PAD and CAD, respectively (P = 0.0046 and P = 0.0197), compared to C-reactive protein. Both genetic and nongenetic factors, including cardiometabolic and inflammatory markers and adipokines, were significantly associated with GDF15 level. A high level of GDF15 was significantly associated with an increase of all-cause mortality in patients with high-risk PAD and in patients with angiographically documented CAD.

Temporal cardiac remodeling post-myocardial infarction: dynamics and prognostic implications in personalized medicine

Despite dramatic improvements in short-term mortality rates following myocardial infarction (MI), long-term survival for MI patients who progress to heart failure remains poor. MI occurs when the left ventricle (LV) is deprived of oxygen for a sufficient period of time to induce irreversible necrosis of the myocardium. The LV response to MI involves significant tissue, cellular, and molecular level modifications, as well as substantial hemodynamic changes that feedback negatively to amplify the response. Inflammation to remove necrotic myocytes and fibroblast activation to form a scar are key wound healing responses that are highly variable across individuals. Few biomarkers of early remodeling stages are currently clinically adopted. The discovery of underlying pathophysiological mechanisms and associated novel biomarkers has the potential of improving prognostic capability and therapeutic monitoring. Combining these biomarkers with other prominent ones could constitute a powerful diagnostic and prognostic tool that directly reflects the pathophysiological remodeling of the LV. Understanding temporal remodeling at the tissue, cellular, and molecular level and its link to a well-defined set of biomarkers at early stages post-MI is a prerequisite for improving personalized care and devising more successful therapeutic interventions. Here we summarize the integral mechanisms that occur during early cardiac remodeling in the post-MI setting and highlight the most prominent biomarkers for assessing disease progression.

No Added Value of Novel Biomarkers in the Diagnostic Assessment of Patients Suspected of Acute Coronary Syndrome

BACKGROUND

Despite the availability of high-sensitive troponin (hs-cTnT), there is still room for improvement in the diagnostic assessment of patients suspected of acute coronary syndrome (ACS). Apart from serial biomarker testing, which is time-consuming, novel biomarkers like copeptin have been proposed to expedite the early diagnosis of suspected ACS in addition to hs-cTnT. We determined whether placenta derived growth factor (PlGF), soluble Fms-like tyrosine kinase 1 (sFlt-1), myoglobin, N-terminal prohormone B-type Natriuretic Peptide (NT-proBNP), growth-differentiation factor 15 (GDF-15) and copeptin improved early assessment of chest pain patients.

METHODS

This prospective, single centre diagnostic FAME-ER study included patients presenting to the ED with symptoms suggestive of ACS. Blood was collected to measure biomarkers, notably, hs-cTnT was retrospectively assessed. Added value of markers was judged by increase in AUC using multivariable logistic regression.

RESULTS

Of 453 patients enrolled, 149 (33%) received a final diagnosis of ACS. Hs-cTnT had the highest diagnostic value in both univariable and multivariable analysis. PPVs of the biomarkers ranged from 23.5% (PlGF) to 77.9% (hs-cTnT), NPVs from 67.0% (PlGF) to 86.4% (hs-cTnT). Only myoglobin yielded diagnostic value in addition to clinical symptoms and electrocardiography (ECG) (AUC of clinical model 0.80) with AUC of 0.84 (p<0.001). However, addition of hs-cTnT was superior (AUC 0.89, p<0.001). Addition of the biomarkers to our clinical model and hs-cTnT did not or only marginally (GDF-15) improved diagnostic performance.

CONCLUSION

When assessing patients suspected of ACS, only myoglobin had added diagnostic value beyond clinical symptoms and ECG. However, when combined with hs-cTnT, it yields no additional diagnostic value. PlGF, sFlt-1, NT-proBNP, GDF-15 and copeptin had no added value to the clinical model or hs-cTnT.

Signal peptides: new markers in cardiovascular disease?

Proteins and peptides are well-documented as useful marker adjuncts to cardiovascular clinical decision-making. Most markers measured derive from a defined, stable proprotein region of their respective gene. However, a neglected portion of preproproteins known as the signal peptide (SP) is also present in the circulation and may also present as a measurable marker. SPs were assumed to be degraded intracellularly after directing secretion, but a small, growing body of evidence is identifying SPs as not being degraded within and without cells. In this article, evidence for the persistence of SPs after translation is presented and their role as potential cardiovascular biomarkers is discussed.

GDF-15 for prognostication of cardiovascular and cancer morbidity and mortality in men

The objective was to evaluate the hypothesis that growth-differentiation factor 15 (GDF-15) is an independent marker of the long-term risk for both cardiovascular disease and cancer morbidity beyond clinical and biochemical risk factors. Plasma obtained at age 71 was available from 940 subjects in the Uppsala Longitudinal Study of Adult Men (ULSAM) cohort. Complete mortality and morbidity data were obtained from public registries. At baseline there were independent associations between GDF-15 and current smoking, diabetes mellitus, biomarkers of cardiac (high-sensitivity troponin-T, NT-proBNP) and renal dysfunction (cystatin-C) and inflammatory activity (C-reactive protein), and previous cardiovascular disease (CVD). During 10 years follow-up there occurred 265 and 131 deaths, 115 and 46 cardiovascular deaths, and 185 and 86 events with coronary heart disease mortality or morbidity in the respective total cohort (n=940) and non-CVD (n=561) cohort. After adjustment for conventional cardiovascular risk factors, one SD increase in log GDF-15 were, in the respective total and non-CVD populations, associated with 48% (95%CI 26 to 73%, p<0.001) and 67% (95%CI 28 to 217%, p<0.001) incremental risk of cardiovascular mortality, 48% (95%CI 33 to 67%, p<0.001) and 61% (95%CI 38 to 89%, p<0.001) of total mortality and 36% (95%CI 19 to 56%, p<0.001) and 44% (95%CI 17 to 76%, p<0.001) of coronary heart disease morbidity and mortality. The corresponding incremental increase for cancer mortality in the respective total and non-cancer disease (n=882) population was 46% (95%CI 21 to 77%, p<0.001) and 38% (95%CI 12 to 70%, p<0.001) and for cancer morbidity and mortality in patients without previous cancer disease 30% (95%CI 12 to 51%, p<0.001). In conclusion, in elderly men, GDF-15 improves prognostication of both cardiovascular, cancer mortality and morbidity beyond established risk factors and biomarkers of cardiac, renal dysfunction and inflammation.

Clinical and genetic correlates of growth differentiation factor 15 in the community

BACKGROUND

Growth differentiation factor 15 (GDF15), a stress-responsive cytokine produced in cardiovascular cells under conditions of inflammation and oxidative stress, is emerging as an important prognostic marker in individuals with and without existing cardiovascular disease (CVD). We therefore examined the clinical and genetic correlates of circulating GDF15 concentrations, which have not been investigated collectively.

METHODS

Plasma GDF15 concentrations were measured in 2991 participants in the Framingham Offspring Study who were free of clinically overt CVD (mean age, 59 years; 56% women). Clinical correlates of GDF15 were examined in multivariable analyses. We then conducted a genomewide association study of the GDF15 concentration that included participants in the Framingham Offspring Study and participants in the PIVUS (Prospective Investigation of the Vasculature in Uppsala Seniors) study.

RESULTS

GDF15 was positively associated with age, smoking, antihypertensive treatment, diabetes, worse kidney function, and use of nonsteroidal antiinflammatory drugs (NSAIDs), but it was negatively associated with total cholesterol and HDL cholesterol. Clinical correlates accounted for 38% of interindividual variation in the circulating GDF15 concentration, whereas genetic factors accounted for up to 38% of the residual variability (h(2) = 0.38; P = 2.5 × 10(-11)). We identified 1 locus of genomewide significance. This locus, which is on chromosome 19p13.11 and includes the GDF15 gene, is associated with GDF15 concentration (smallest P = 2.74 × 10(-32) for rs888663). Conditional analyses revealed 2 independent association signals at this locus (rs888663 and rs1054564), which were associated with altered cis gene expression in blood cell lines.

CONCLUSIONS

In ambulatory individuals, both cardiometabolic risk factors and genetic factors play important roles in determining circulating GDF15 concentrations and contribute similarly to the overall variation.

Growth differentiation factor-15, a novel biomarker related with disease severity in patients with hypertrophic cardiomyopathy

BACKGROUND

The growth differentiation factor 15 (GDF-15) has been shown up-regulated in stress conditions and to have regulatory actions in myocyte hypertrophy. We hypothesized that GDF-15 could be related to disease severity and functional status in patients with hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

We performed a study which includes 102 consecutive outpatient HCM subjects, 73% males, aged 47.1±14.6 years. A complete history and clinical examination was performed, including 12-lead electrocardiogram, echocardiography, symptom-limited treadmill exercise, 24-hour ECG-Holter monitoring, and magnetic resonance with Gadolinium. Several biomarkers, associated with myocardial remodeling and damage, were compared to GDF-15 levels. The assays were performed with commercial ELISAs or standardized methods when available. There was a significant association between GDF-15 levels and comorbidities, being higher in hypertension (p=0.001), diabetes (p=0.030), atrial fibrillation (p=0.012), dyspnea (p=0.020) and NYHA≥II functional class (p=0.037). GDF-15 levels were positively correlated with clinical variables (age, worse exercise capacity and mild renal dysfunction) and biomarkers of interstitial remodeling, such as metalloproteinase-2 (r: 0.40; p=0.009), N-terminal pro-B-type natriuretic peptide (r: 0.28; p=0.049), high-sensitivity troponin T (r: 0.30; p=0.003) and von Willebrand factor (r: 0.33; p=0.001). Multivariate analysis was assessed to estimate the involvement of these different factors in the GDF-15 levels, confirming the independent implication of severe dyspnea and functional status.

CONCLUSIONS

The present results show that higher levels of GDF-15 are associated to conditions of severe disease in HCM. Hence, GDF-15 is suggested as a novel marker related to the severity and could represent a further useful tool in monitoring functional capacity of HCM patients.

Increasing serum troponin I and early prognosis in patients with chest pain or angina equivalent symptoms in the emergency department

BACKGROUND

The purpose of this research was to determine the relation between negative or positive qualitative troponin I test and the short term prognosis of patients presenting to emergency department with chest pain or angina equivalent symptoms.

METHODS

we assessed the qualitative rapid troponin I in patients with chest pain or angina equivalent symptoms after at least 4 hours and then we followed the patients in 72 hours after presentation for adverse events such as death, CCU admission, fatal arrhythmias and heart failure.

RESULTS

After comparing qualitative troponin I test results and adverse events, we concluded that the troponin I was significantly more positive in patients with adverse events (i.e. CCU admission, fatal arrhythmias and heart failure) (P=0.031).

CONCLUSION

A single measurement of rapid qualitative troponin I test can be used as a prognostic factor in patients with chest pain or angina equivalent symptoms and also as a device for risk stratification of moderate and high risk patients.

Cardiac biomarkers in acute myocardial infarction

Each year, a large number of patients are seen in the Emergency Department with presentations necessitating investigation for possible acute myocardial infarction. Patients can be stratified by symptoms, risk factors and electrocardiogram results but cardiac biomarkers also have a prime role both diagnostically and prognostically. This review summarizes both the history of cardiac biomarkers as well as currently available (established and novel) assays. Cardiac troponin, our current "gold standard" biomarker criterion for the diagnosis of myocardial infarction has high sensitivity and specificity for this diagnosis and therapies instituted in patients with elevated troponin have been shown to influence outcomes. Other markers of myocardial necrosis, inflammation and neurohormonal activity have also been shown to have either diagnostic or prognostic utility, but none have been shown to be superior to troponin. The measurement of multiple biomarkers and the use of point of care markers may accelerate current diagnostic protocols for the assessment of such patients.

Growth Differentiation Factor-15 in the Early Diagnosis and Risk Stratification of Patients with Acute Chest Pain

BACKGROUND

Growth differentiation factor-15 (GDF-15) is a stress-responsive marker that might aid in the early diagnosis and risk stratification of patients with suspected acute myocardial infarction (AMI).

METHODS

In a prospective, international multicenter study, GDF-15, high-sensitivity cardiac troponin T (hs-cTnT), and B-type natriuretic peptide (BNP) were measured in 646 unselected patients presenting to the emergency department with acute chest pain. The final diagnosis was adjudicated by 2 independent cardiologists. The primary prognostic end point was all-cause mortality during a median follow-up of 26 months.

RESULTS

AMI was the adjudicated final diagnosis in 115 patients (18%). GDF-15 concentrations at presentation were significantly higher in AMI patients compared to patients with other diagnoses. The diagnostic accuracy of GDF-15 at presentation for the diagnosis of AMI as quantified by the area under the ROC curve (AUC) was lower (AUC 0.69, 95% CI 0.64–0.74) compared to hs-cTnT (AUC 0.96, 95% CI 0.94–0.98, P &lt; 0.001) and BNP (AUC 0.74, 95% CI 0.69–0.80, P = 0.02). A total of 55 deaths occurred during follow-up. GDF-15 predicted all-cause mortality independently of and more accurately than hs-cTnT [AUC 0.85 (95% CI 0.81–0.90) vs 0.77 (95% CI 0.72–0.83), P = 0.002] and BNP (AUC 0.75, 95% CI 0.68–0.82, P = 0.007). Net reclassification improvement was 0.15 (P = 0.01), and the absolute integrated discrimination improvement was 0.07, yielding a relative integrated discrimination improvement of 0.36 (P = 0.07).

CONCLUSIONS

GDF-15 predicts all-cause mortality in unselected patients with acute chest pain independently of and more accurately than hs-cTnT and BNP. However, GDF-15 does not seem to help in the early diagnosis of AMI.

The TGF-β superfamily cytokine, MIC-1/GDF15: a pleotrophic cytokine with roles in inflammation, cancer and metabolism

Macrophage inhibitory cytokine-1 (MIC-1/GDF15) is associated with cardiovascular disease, inflammation, body weight regulation and cancer. Its serum levels facilitate the diagnosis and prognosis of cancer and vascular disease. Furthermore, its serum levels are a powerful predictor of all-cause mortality, suggesting a fundamental role in biological processes associated with ageing. In cancer, the data available suggest that MIC-1/GDF15 is antitumorigenic, but this may not always be the case as disease progresses. Cancer promoting effects of MIC-1/GDF15 may be due, in part, to effects on antitumour immunity. This is suggested by the anti-inflammatory and immunosuppressive properties of MIC-1/GDF15 in animal models of atherosclerosis and rheumatoid arthritis. Furthermore, in late-stage cancer, large amounts of MIC-1/GDF15 in the circulation suppress appetite and mediate cancer anorexia/cachexia, which can be reversed by monoclonal antibodies in animals. Available data suggest MIC-1/GDF15 may be an important molecule mediating the interplay between cancer, obesity and chronic inflammation.

Relation of growth-differentiation factor 15 to left ventricular remodeling in ST-segment elevation myocardial infarction

The development of left ventricular remodeling (LVR) after myocardial infarction is associated with a high risk of heart failure and death. LVR is difficult to predict, and limited information is available on the association of cardiac biomarkers and LVR. Growth-differentiation factor-15 (GDF-15) is induced during heart failure development and, in animals models, might influence the different processes involved in cardiac remodeling. The aim of the present investigation was to assess the association between the serum levels of GDF-15 within the first 24 hours of ST-segment elevation myocardial infarction and the development of subsequent LVR at 12 months of follow-up. This prospective study included 97 patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention. Echocardiography was performed in all patients within the first 96 hours of admission and at 12 months of follow-up. LVR was defined as a >20% increase in the left ventricular end-diastolic volume at 12 months of follow-up compared to baseline. Blood samples for the determination of GDF-15 and brain natriuretic peptide were obtained within the first 24 hours after symptom onset. According to the pre-established criteria, 21 patients (22%) had LVR. Patients with LVR had greater levels of GDF-15 at study entry (median 3,439 pg/ml, interquartile range 2,391 to 6,168 vs median 1998 pg/ml, interquartile range 1,204 to 3,067, respectively; p <0.001). Multivariate analysis showed that GDF-15 (odds ratio 10.1, 95% confidence interval 2.5 to 40.1, p <0.001) and treatment with angiotensin-converting enzyme inhibitors (odds ratio 3.9, 95% confidence interval 1.2 to 12.3, p <0.01) were independents predictors of LVR. Receiving operating characteristics analysis showed an area under the curve of 0.77 for GDF-15 (95% confidence interval 0.67 to 0.84, p <0.001). In conclusion, the results of the present study have identified GDF-15 as an independent marker of LVR in patients with ST-segment elevation myocardial infarction.

Successful in vitro expansion and differentiation of cord blood derived CD34+ cells into early endothelial progenitor cells reveals highly differential gene expression

Endothelial progenitor cells (EPCs) can be purified from peripheral blood, bone marrow or cord blood and are typically defined by a limited number of cell surface markers and a few functional tests. A detailed in vitro characterization is often restricted by the low cell numbers of circulating EPCs. Therefore in vitro culturing and expansion methods are applied, which allow at least distinguishing two different types of EPCs, early and late EPCs. Herein, we describe an in vitro culture technique with the aim to generate high numbers of phenotypically, functionally and genetically defined early EPCs from human cord blood. Characterization of EPCs was done by flow cytometry, immunofluorescence microscopy, colony forming unit (CFU) assay and endothelial tube formation assay. There was an average 48-fold increase in EPC numbers. EPCs expressed VEGFR-2, CD144, CD18, and CD61, and were positive for acetylated LDL uptake and ulex lectin binding. The cells stimulated endothelial tube formation only in co-cultures with mature endothelial cells and formed CFUs. Microarray analysis revealed highly up-regulated genes, including LL-37 (CAMP), PDK4, and alpha-2-macroglobulin. In addition, genes known to be associated with cardioprotective (GDF15) or pro-angiogenic (galectin-3) properties were also significantly up-regulated after a 72 h differentiation period on fibronectin. We present a novel method that allows to generate high numbers of phenotypically, functionally and genetically characterized early EPCs. Furthermore, we identified several genes newly linked to EPC differentiation, among them LL-37 (CAMP) was the most up-regulated gene.

Inflammation and cardiac outcome

PURPOSE OF REVIEW

Inflammation is a key component in cardiovascular disease. Controlling inflammatory events and their subsequent processes holds the potential for novel therapeutic treatment options. Cytokines are the propagators of inflammation. In this review we will discuss important cytokines including IL-6, TNF-α, MCP-1, fractalkine, M-CSF and GDF-15, and their effect on cardiac outcome.

RECENT FINDINGS

Recent studies have shed light on the role of IL-6 in cardiovascular disease. Long-term IL-6 levels are highly associated with coronary heart disease. Molecular studies indicate that a permanent prolongation of STAT signaling in cardiac myocytes might be a potential reason for the detrimental effects of IL-6. TNF-α was long considered to have detrimental effects on myocardial function but recent studies show cardioprotective mechanisms for TNF-α. Macrophage modulating cytokines emerge as interesting molecular targets to treat cardiovascular disease. Especially, the two different subtypes of monocytes, a pro-inflammatory and a reparative subset, and their different chemotactic properties might be possible drug targets. Finally, we discuss GDF-15, which emerges as a novel biomarker in cardiovascular disease reflecting information from several pathological pathways.

SUMMARY

Cytokines are the main proximal mediators of inflammation and hold the potential of being good molecular targets for novel treatment regimes. Cytokines might be valuable biomarkers, adding information about the pathologic pathways in cardiovascular disease.

Growth differentiation factor 15: an additional diagnostic tool for the risk stratification of developing heart failure in patients with operated congenital heart defects?

BACKGROUND

Many young adults who have congenital heart defects develop heart failure despite corrective surgeries. Growth differentiation factor 15 (GDF-15) has an established role as a marker for risk stratification and mortality both in patients after acute myocardial infarction and in patients with heart failure. Our aim was to establish a role for GDF-15 for monitoring heart failure in operated congenital heart defects (ACHD). This potential biomarker was validated through comparison with maximal oxygen uptake (VO(2max)) and to another biomarker, N-terminal pro-brain natriuretic peptide (NT-proBNP).

METHODS

A total of 317 ACHD patients (129 females) with an average age of 26.5 ± 8.5 years (mean ± SD) enrolled in the study. We studied the relation between GDF-15 and NT-proBNP and VO(2max%) (percent predicted for age and gender). The cutoffs for the groups were as follows: NT-proBNP <100, 100 to 300, and >300 pg/mL; VO(2max%) <65%, 65% to 85%, and >85% of predicted normal.

RESULTS

Significant differences in mean GDF-15 levels were found between the NT-proBNP <100 and NT-proBNP >300 groups, as well as between the 100 to 300 and the >300 groups. For VO(2max%), significant differences were found in GDF-15 levels between <65% and >85% and between <65% and 65% to 85%, respectively. The lowest mean GDF-15 was found in groups with NT-proBNP <100 pg/mL and VO(2max%) >85%. The highest mean GDF-15 was found in the groups with NT-proBNP >300 pg/mL and VO(2max%) <65%. A subgroup analysis, including 82 patients with operated tetralogy of Fallot, showed that patients in the New York Heart Association I class have significantly lower NT-proBNP and GDF-15 level and markedly higher VO(2max) compared with the patients in higher New York Heart Association class.

CONCLUSION

Growth differentiation factor 15 might be used as a surrogate marker for latent heart failure and could help to identify patients with ACHD who are at risk for developing heart failure, even if they are clinically asymptomatic.

B-type natriuretic peptide in the early diagnosis and risk stratification of acute chest pain

BACKGROUND

Myocardial ischemia is a strong trigger of B-type natriuretic peptide (BNP) release. As ischemia precedes necrosis in acute myocardial infarction, we hypothesized that BNP might be useful in the early diagnosis and risk stratification of patients with acute chest pain.

METHODS

In a prospective, international multicenter study, BNP was measured in 1075 unselected patients with acute chest pain. The final diagnosis was adjudicated by 2 independent cardiologists. Patients were followed long term regarding mortality.

RESULTS

Acute myocardial infarction was the adjudicated final diagnosis in 168 patients (16%). BNP levels at presentation were significantly higher in acute myocardial infarction as compared with patients with other diagnoses (median 224 pg/mL vs. 56 pg/mL, P <.001). The diagnostic accuracy of BNP for the diagnosis of acute myocardial infarction as quantified by the area under the receiver operating characteristic curve (AUC) (0.74; 95% confidence interval [CI], 0.70-0.78) was lower compared with cardiac troponin T at presentation (AUC 0.88; 95% CI, 0.84-0.92; P <.001). Cumulative 24-month mortality rates were 0.5% in the first, 2.1% in the second, 7.0% in the third, and 22.9% in the fourth quartile of BNP (P <.001). BNP predicted all-cause mortality independently of and more accurately than cardiac troponin T: AUC 0.81 (95% CI, 0.76-0.86) versus AUC 0.70 (95% CI, 0.62-0.77; P <.001). Net reclassification improvement for BNP was 0.10 (P=.04), and integrated discrimination improvement 0.068 (P=.01).

CONCLUSIONS

BNP accurately predicts mortality in unselected patients with acute chest pain independently of and more accurately than cardiac troponin T, but does not seem to help in the early diagnosis of acute myocardial infarction.

Growth differentiation factor 15 and coronary collateral formation

BACKGROUND

The coronary collateral circulation can reduce sudden cardiac death,myocardial cell loss,and infarct size.Growth differentiation factor 15(GDF-15),a member of the transforming growth factor-beta (TGF-beta) superfamily,has been reported to have a prognostic predicting value in coronary artery disease.

HYPOTHESIS

GDF-15 can be related with the extent of collateral formation.

OBJECTIVE

Growth differentiation factor 15 (GDF-15), a member of the transforming growth factor-beta (TGF-beta) superfamily, has been reported to have a prognostic predicting value in coronary artery disease. We sought to investigate whether GDF-15 is related to coronary collateral development in patients with coronary heart disease.

METHODS

A cross-sectional study was performed in 201 patients, who were admitted for selective coronary angiography. Patients were divided into 3 groups based on Rentrop's classification of coronary collaterals. Group 1: patients with coronary collateral presence, which was defined by Rentrop's grade 1-3 collateral development. Group 2: patients with grade 0 collateral development. Group 3: control group were patients with a normal coronary angiogram. The levels of plasma GDF-15, asymmetric dimethylarginine (ADMA), and soluble Fms-related tyrosine kinase-1 (sFLT-1) were compared among the 3 groups.

RESULTS

There were significant statistical differences in plasma sFLT-1, ADMA, and GDF-15 concentrations among the different collateral groups. The correlations between Rentrop's grade and the cytokines were significant. A positive correlation was found between Rentrop's grade and GDF-15 (r = 0.187, P < 0.05). The correlations between the levels of plasma sFLT-1, ADMA, and Rentrop's grade were significant, with the correlation coefficient of r = 0.181, P < 0.05 (sFLT-1) and r = - 0.646, P < 0.001 (ADMA), respectively.

CONCLUSIONS

Our findings suggest that GDF-15 levels increase with the extent of collateral formation. In that case, the patients with a higher level of GDF-15 may predict more severe coronary stenosis, which has a higher probability to develop collaterals.

Growth differentiation factor 15 deficiency protects against atherosclerosis by attenuating CCR2-mediated macrophage chemotaxis

The TGF-β family member GDF-15 promotes lesion formation and plaque instability in atherosclerosis-prone LDLr-deficient mice.

Growth differentiation factor (GDF) 15 is a member of the transforming growth factor β (TGF-β) superfamily, which operates in acute phase responses through a currently unknown receptor. Elevated GDF-15 serum levels were recently identified as a risk factor for acute coronary syndromes. We show that GDF-15 expression is up-regulated as disease progresses in murine atherosclerosis and primarily colocalizes with plaque macrophages. Hematopoietic GDF-15 deficiency in low density lipoprotein receptor^−/− mice led to impaired initial lesion formation and increased collagen in later lesions. Although lesion burden in GDF-15^−/− chimeras was unaltered, plaques had reduced macrophage infiltrates and decreased necrotic core formation, all features of improved plaque stability. In vitro studies pointed to a TGFβRII-dependent regulatory role of GDF-15 in cell death regulation. Importantly, GDF-15^−/− macrophages displayed reduced CCR2 expression, whereas GDF-15 promoted macrophage chemotaxis in a strictly CCR2- and TGFβRII-dependent manner, a phenomenon which was not observed in G protein–coupled receptor kinase 2^+/− macrophages. In conclusion, GDF-15 deletion has a beneficial effect both in early and later atherosclerosis by inhibition of CCR2-mediated chemotaxis and by modulating cell death. Our study is the first to identify GDF-15 as an acute phase modifier of CCR2/TGFβRII-dependent inflammatory responses to vascular injury.

Growth differentiation factor-15 and risk of recurrent events in patients stabilized after acute coronary syndrome: observations from PROVE IT-TIMI 22

OBJECTIVE

To investigate growth differentiation factor (GDF)-15 at hospital discharge for assessment of the risk of death, recurrent myocardial infarction (MI), and congestive heart failure, and to determination of whether these risks can be modified by statins.

METHODS AND RESULTS

GDF-15 is a transforming growth factor-β-related cytokine induced in response to tissue injury. GDF-15 concentration is associated with all-cause mortality in patients with acute coronary syndrome (ACS). We measured GDF-15 in 3501 patients after ACS, treated with moderate or intensive statin therapy in PROVE IT-TIMI 22. By using established cutoff points, GDF-15 (<1200, 1200-1800, and >1800 ng/L) was associated with 2-year risk of death or MI (5.7%, 8.1%, and 15.1%, respectively; P<0.001), death (P<0.001), MI (P<0.001), and congestive heart failure (P<0.001). After adjustment for age, sex, body mass index, diabetes mellitus, hypertension, smoking, MI, qualifying event, renal function, B-type natriuretic peptide, and high-sensitivity C-reactive protein, GDF-15 was associated with the risk of death or MI (adjusted hazard ratio per ln increase GDF-15, 2.1 [95% CI, 1.6 to 2.9]; P<0.001), death (P<0.001), MI (P<0.001), and congestive heart failure (P<0.001). There was no significant interaction between GDF-15 and intensive statin therapy for the risk of death or MI (P=0.24 for the interaction).

CONCLUSIONS

GDF-15 is associated with recurrent events after ACS, independent of clinical predictors, B-type natriuretic peptide, and high-sensitivity C-reactive protein. This finding supports GDF-15 as a prognostic marker in ACS and investigation of other therapies that modify this risk.

Novel biomarkers in cardiovascular disease: update 2010

The rapid evaluation of patients presenting with symptoms suggestive of an acute coronary syndrome is of great clinical relevance. Biomarkers have become increasingly important in this setting to supplement electrocardiographic findings and patient history because one or both can be misleading. Today, cardiac troponin is still the only marker used routinely in this setting due to its myocardial tissue specificity and sensitivity, as well as its established usefulness for therapeutic decision making. However, even current generation troponin assays have certain limitations such as insufficient sensitivity for diagnosing unstable angina. Novel high-sensitivity assays for cardiac troponin have the potential to overcome these limitations. Further studies are needed to answer some critical questions regarding the best cutoffs for diagnosis and risk assessment and the optimal work-up for rule-out of acute myocardial infarction. Other nonmyocardial tissue-specific markers might help in this setting. Myeloperoxidase, copeptin, and growth differentiation factor 15 reflect different aspects of the development of atherosclerosis or acute ischemia. Each has demonstrated impact in risk stratification of acute coronary syndromes. Limited data also show that copeptin may, when used together with cardiac troponin, improve the sensitivity for diagnosing acute myocardial infarction, and growth differentiation factor 15 may help in selection of patients that benefit from invasive therapy. Further evaluation is needed before these markers can be adopted routinely in clinical practice.

The novel biomarker growth differentiation factor 15 in heart failure with normal ejection fraction

AIMS

Heart failure with normal ejection fraction (HFnEF) is an important clinical entity that remains incompletely understood. The novel biomarker growth differentiation factor 15 (GDF-15) is elevated in systolic heart failure (HFrEF) and is predictive of an adverse outcome. We investigated the clinical relevance of GDF-15 plasma levels in HFnEF.

METHODS AND RESULTS

A subgroup of patients from the ongoing DIAST-CHF observational trial, with a history of chronic heart failure (CHF) or positive Framingham criteria at presentation, was selected. Patients were classified as having either HFrEF (n=86) or HFnEF (n=142) and compared with healthy elderly controls (n=188) from the same cohort. Growth differentiation factor 15 levels in HFnEF were significantly higher than in controls and similar to those in HFrEF. In multivariate analysis, factors significantly associated with GDF-15 levels were age, sex, estimated glomerular filtration rate (eGFR), presence of HFrEF and HFnEF. Growth differentiation factor 15 correlated with multiple echocardiographic markers of diastolic function and was associated with 6 min walk test performance and SF-36 physical score on multivariate analysis in all patients. When using a classification for HFnEF that did not employ N-terminal pro brain natriuretic peptide (NT-proBNP) as a diagnostic criterion, the diagnostic properties of GDF-15 for detecting HFnEF tended to be superior to those of NT-proBNP, and a combination significantly improved diagnostic accuracy.

CONCLUSION

Growth differentiation factor 15 is elevated in HFnEF to a similar degree as in HFrEF. It is independently associated with impairment in exercise capacity and in physical components of quality of life. Diagnostic precision of GDF-15 is at least as good as that of NT-proBNP and combining both markers improves diagnostic accuracy.

Improving long-term risk prediction in patients with acute chest pain: the Global Registry of Acute Coronary Events (GRACE) risk score is enhanced by selected nonnecrosis biomarkers

BACKGROUND

The Global Registry of Acute Coronary Events (GRACE) risk score is widely recommended for risk assessment in patients with acute coronary syndrome. However, there is limited knowledge regarding the utility of this score for long-term risk prediction in unselected patients with acute chest pain and whether it might be improved by the integration of nonnecrosis biomarkers.

METHODS

We calculated the GRACE risk score in 453 chest pain patients and assessed its value for risk assessment together with the additive prognostic information obtained from N-terminal pro-B-type natriuretic peptide, C-reactive protein, growth differentiation factor-15 (GDF-15), and cystatin C.

RESULTS

After a median follow-up of 5.8 years, 92 patients (20.7%) had died. The GRACE risk score was significantly higher in patients who died (median 146 vs 93, P < .001) and provided a c-statistic regarding mortality of 0.78. A significant increase of the c-statistic was achieved only after addition of GDF-15 (c-statistic 0.81, P = .003) and, to a minor extent, after addition of cystatin C (c-statistic 0.81, P = .035). Assessment of the integrated discriminative improvement yielded similar results. N-terminal pro-B-type natriuretic peptide had only limited incremental prognostic value, and C-reactive protein was not predictive for outcome.

CONCLUSION

The GRACE risk score allows for the prediction of mortality in chest pain patients even after almost 6 years of follow-up. However, its predictive value could be further enhanced by the addition of selected nonnecrosis biomarkers, in particular GDF-15 or cystatin C.

Growth differentiation factor-15: a new biomarker in cardiovascular disease

Growth differentiation factor-(GDF-)15 is a stress-responsive cytokine that is emerging as a biomarker of cardiac and vascular dysfunction and disease. Elevated circulating levels of GDF-15 identify high-risk individuals across the cardiovascular continuum, from stable coronary artery disease to acute coronary syndrome and heart failure. The association of GDF-15 with outcome in these conditions is independent of clinical risk factors and established biomarkers, including NT-proBNP (N-terminal pro-B-type natriuretic peptide) and troponin. The prognostic information provided by GDF-15 in cardiovascular disease may inform patient management, e.g., by identifying patients with non-ST segment elevation acute coronary syndrome who benefit from an invasive strategy, or by monitoring treatment response in heart failure. Future studies need to evaluate prospectively whether GDF-15, alone or as part of a multimarker strategy, can improve contemporary risk prediction algorithms and support therapeutic management of patients with cardiovascular disease.

Gene expression profiling of dilated cardiomyopathy in older male EP4 knockout mice

Using a line of mice with cardiac-specific knockout (KO) of the EP4 receptor gene, experiments were designed to determine whether a cardiac phenotype developed with age. Cardiac function was assessed by echocardiography in 23- to 33-wk-old male and female KO and littermate controls (WT) mice. After echocardiography, hearts were removed to assess weight, and then some were further processed for histology [myocyte cross-sectional area (MCSA), interstitial collagen fraction (ICF), and macrophage infiltration] and some for extraction of total RNA and protein. Older male KO mice had reduced ejection fraction (EF) coupled with left ventricular dilatation. MCSA and infiltrating macrophages were not different between groups, but ICF increased by 39% in KO mice. In contrast to male KO mice, 30- to 32-wk-old female KO mice had only a slight reduction in EF. To understand gene expression differences between male WT and KO mice, we performed whole genome gene expression profiling (Illumina BeadChips) on hearts of 30-to 32-wk-old mice. Data indicated that 156 genes were overexpressed in the KO hearts more than twofold, including genes involved in remodeling, inflammation, and oxidative stress. Overexpressed chemokines/cytokines were further examined in hearts of 10- to 12-wk-old male KO mice, and we found that growth differentiation factor-15 (GDF-15) expression was higher in KO than in WT hearts. In conclusion, EP4 knockdown in cardiac myocytes in aged male KO mice is in part associated with increased fibrosis, reduced EF, and dilated cardiomyopathy. Early overexpression of GDF-15 in hearts of male KO mice may contribute to or be a marker of the disease phenotype. The absence of serious cardiac dysfunction in aged female mice suggests a sexual dimorphism in the phenotype.

Sensitive plasma protein analysis by microparticle-based proximity ligation assays

Detection of proteins released in the bloodstream from tissues damaged by disease can promote early detection of pathological conditions, differential diagnostics, and follow-up of therapy. Despite these prospects and a plethora of candidate biomarkers, efforts in recent years to establish new protein diagnostic assays have met with limited success. One important limiting factor has been the challenge of detecting proteins present at trace levels in complex bodily fluids. To achieve robust, sensitive, and specific detection, we have developed a microparticle-based solid-phase proximity ligation assay, dependent on simultaneous recognition of target proteins by three antibody molecules for added specificity. After capture on a microparticle, solid-phase pairs of proximity probes are added followed by washes, enabling detection and identification of rare protein molecules in blood while consuming small amounts of sample. We demonstrate that single polyclonal antibody preparations raised against target proteins of interest can be readily used to establish assays where detection depends on target recognition by three individual antibody molecules, recognizing separate epitopes. The assay was compared with state-of-the-art sandwich ELISAs for detection of vascular endothelial growth factor, interleukin-8 and interleukin-6, and it was found to be superior both with regard to dynamic range and minimal numbers of molecules detected. Furthermore, the assays exhibited excellent performance in undiluted plasma and serum as well as in whole blood, producing comparable results for nine different antigens. We thus show that solid-phase proximity ligation assay is suitable for validation of a variety of protein biomarkers over broad dynamic ranges in clinical samples.

Growth-differentiation factor-15 in heart failure

The stress-responsive transforming growth factor-beta-related cytokine, growth-differentiation factor-15 (GDF-15), is emerging as a new biomarker in patients with cardiovascular disease. The circulating levels of GDF-15 are elevated and independently related to an adverse prognosis in acute coronary syndrome and left- or right-sided heart failure. GDF-15 adds significant prognostic information to established clinical and biochemical risk markers in these conditions. Elevated levels of GDF-15 may identify patients who have non-ST-elevation acute coronary syndrome who derive the greatest benefit from an invasive treatment strategy. As with other heart failure biomarkers, including BNP, it is currently not known what specific therapies could be used to reduce the risk associated with elevated levels of GDF-15 in heart failure. Further elucidation of the pathobiology and upstream inducers of this new biomarker may lead to new therapeutic concepts that address the risk associated with elevated GDF-15 levels. A commercial assay for GDF-15 should be available in the near future.

The development of gene therapy for diseases of the lung

The development of a successful gene therapy has many stages, including preclinical testing in animal models and proof of principle clinical studies. A variety of diseases affect the lung, which are candidates for gene therapy; this review will mainly focus on the diseases that have attracted the most attention and have therefore yielded the most progress, namely lung cancer and the monogenic disorder cystic fibrosis. Knowledge gained from clinical studies could eventually be applied to more complex lung conditions such as acute respiratory distress syndrome and asthma. In addition, increased gene transfer efficiencies could be obtained by appropriate selection of the gene transfer vector and mode of delivery.