Involvement of growth differentiation factor-15/macrophage inhibitory cytokine-1 (GDF-15/MIC-1) in oxLDL-induced apoptosis of human macrophages in vitro and in arteriosclerotic lesions

GDF-15 as a Target and Biomarker for Diabetes and Cardiovascular Diseases: A Translational Prospective

Growth differentiation factor-15 (GDF-15) is a stress responsive cytokine. It is highly expressed in cardiomyocytes, adipocytes, macrophages, endothelial cells, and vascular smooth muscle cells in normal and pathological condition. GDF-15 increases during tissue injury and inflammatory states and is associated with cardiometabolic risk. Increased GDF-15 levels are associated with cardiovascular diseases such as hypertrophy, heart failure, atherosclerosis, endothelial dysfunction, obesity, insulin resistance, diabetes, and chronic kidney diseases in diabetes. Increased GDF-15 level is linked with the progression and prognosis of the disease condition. Age, smoking, and environmental factors are other risk factors that may increase GDF-15 level. Most of the scientific studies reported that GDF-15 plays a protective role in different tissues. However, few reports show that the deficiency of GDF-15 is beneficial against vascular injury and inflammation. GDF-15 protects heart, adipose tissue, and endothelial cells by inhibiting JNK (c-Jun N-terminal kinase), Bad (Bcl-2-associated death promoter), and EGFR (epidermal growth factor receptor) and activating Smad, eNOS, PI3K, and AKT signaling pathways. The present review describes the different animal and clinical studies and patent updates of GDF-15 in diabetes and cardiovascular diseases. It is a challenge for the scientific community to use GDF-15 information for patient monitoring, clinical decision-making, and replacement of current treatment strategies for diabetic and cardiovascular diseases.

Growth differentiation factor 15, a marker of oxidative stress and inflammation, for risk assessment in patients with atrial fibrillation: insights from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial

BACKGROUND

Growth differentiation factor 15 (GDF-15), high-sensitivity troponin, and N-terminal pro-brain natriuretic peptide levels are predictive of death and cardiovascular events in healthy elderly subjects, patients with acute coronary syndrome, and patients with heart failure. High-sensitivity troponin I and N-terminal pro-brain natriuretic peptide are also prognostic in patients with atrial fibrillation. We evaluated the prognostic value of GDF-15 alone and in addition to clinical characteristics and other biomarkers in patients with atrial fibrillation.

METHODS AND RESULTS

The Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial randomized 18 201 patients with atrial fibrillation to apixaban or warfarin. Biomarkers were measured at randomization in 14 798 patients. Efficacy and safety outcomes during 1.9 years of follow-up were compared across quartiles of GDF-15 by use of Cox analyses adjusted for clinical characteristics, randomized treatment, and other biomarkers. The GDF-15 level showed a median of 1383 ng/L (interquartile range, 977-2052 ng/L). Annual rates of stroke or systemic embolism ranged from 0.9% to 2.03% (P<0.001); of major bleeding, from 1.22% to 4.53% (P<0.001); and of mortality, from 1.34% to 7.19% (P<0.001) in the lowest compared with the highest GDF-15 quartile. The prognostic information provided by GDF-15 was independent of clinical characteristics and clinical risk scores. Adjustment for the other cardiac biomarkers attenuated the prognostic value for stroke, whereas the prognostic value for mortality and major bleeding remained. Apixaban consistently reduced stroke, mortality, and bleeding, regardless of GDF-15 levels.

CONCLUSIONS

GDF-15 is a risk factor for major bleeding, mortality, and stroke in atrial fibrillation. The prognostic value for major bleeding and death remained even in the presence of N-terminal pro-brain natriuretic peptide and high-sensitivity troponin I.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00412984.

Incidence, risk factors, treatment and prognosis of popliteal artery embolization in the superficial femoral artery interventions

Objective

Percutaneous transluminal angioplasty and stenting (PTA + stent) has gained acceptance as a primary treatment modality for the superficial femoral artery (SFA) diseases. Popliteal artery embolization (PAE) is a severe complication in SFA interventions. The purpose of this study was to evaluate the incidence, risk factors, treatment and prognosis of PAE in primary SFA PTA + stent.

Methods

Chronic SFA arteriosclerosis cases that underwent primary PTA + stent were reviewed from a retrospectively maintained database. Runoff vessels were evaluated in all cases before and after the interventions for PAE detection. The primary patency, secondary patency and limb salvage rates were calculated using Kaplan-Meier analysis and compared using log-rank analysis. Cox multivariate regression was performed to evaluate predictors of patency and limb salvage rates.

Results

There were 436 lesions treated in 388 patients with 10 PAE events (2.3%) in total. PAE rate was significantly higher in Transatlantic Inter-Society Consensus (TASC) C/D group compared with TASC A/B group (OR = 8.91, P = .002), in chronic total occlusion (CTO) lesions compared with stenotic lesions (P<.0001), and in group with history of cerebral ischemic stroke (OR = 6.11, P = .007). PAE rates were not significantly affected by age, sex, smoking, hypertension, diabetes, hyperlipidemia and runoff status. The binary logistic regression showed that only the TASC C/D was an independent predictor of PAE (P = .031). The 12-month and 24-month primary patency, secondary patency and limb salvage rates in PAE group showed no significant differences comparing with non-PAE group.

Conclusions

PAE is a rare event in primary SFA PTA + stent. TASC C/D lesion, CTO and cerebral ischemic stroke history are risk factors for PAE. PAE is typically reversible by comprehensive techniques. If the popliteal flow is restored in time, PAE has no significant effect on long-term patency and limb salvage rates.

Biomarkers of cardiovascular stress and subclinical atherosclerosis in the community

BACKGROUND

Biomarkers of cardiovascular stress have been associated with incident cardiovascular outcomes. Their relations with measures of subclinical atherosclerosis, as assessed by carotid intima-media thickness, have not been well described.

METHODS

We measured plasma growth differentiation factor-15 (GDF-15), soluble ST2 (sST2), and high-sensitivity troponin I (hsTnI) in 3111 Framingham Offspring participants who also underwent carotid ultrasonography during the sixth examination (1995-1998, mean age 58 years, 54% women). Carotid measurements included maximal internal carotid artery (ICA) intima-media thickness (IMT), plaque presence (defined as ICA IMT >1.5 mm), and mean common carotid artery IMT. We carried out multivariable regressions for carotid measurements vs biomarkers using linear and logistic models; P < 0.0056 was deemed statistically significant.

RESULTS

Maximal ICA IMT was significantly associated with plasma GDF-15 [β-estimate 0.04 per 1-U increase in log(GDF-15), SE 0.01, P < 0.0001]. Similarly, the odds of having carotid plaque increased 33% [odds ratio 1.33 per 1-U increase in log(GDF-15), 95% CI 1.20-1.48, P < 0.0001]. In contrast, there was no significant association of maximal ICA IMT or plaque presence with sST2 or hsTnI, and none of the 3 biomarkers was significantly associated with mean CCA IMT. GDF-15 was a stronger predictor of maximal ICA thickness and plaque presence compared with BNP and CRP when these conventional biomarkers were tested together.

CONCLUSIONS

Increased GDF-15 concentrations are associated with subclinical atherosclerosis, including maximal ICA IMT and carotid plaque presence. Future studies investigating the role of GDF-15 for screening and management of patients with subclinical atherosclerosis are warranted.

Increased serum levels of GDF-15 associated with mortality and subclinical atherosclerosis in patients on maintenance hemodialysis

BACKGROUND/AIMS

Increased carotid intima-media thickness (CIMT) was shown to be an independent predictor of cardiovascular (CV) mortality in dialysis patients and the general population. Growth differentiation factor 15 (GDF-15), a member of the transforming growth factor superfamily, is produced by cardiomyocytes and atherosclerotic lesions under stress conditions such as inflammation. We assessed associations between serum concentrations of GDF-15, mortality, and CIMT for subclinical atherosclerosis in hemodialysis (HD) patients.

METHODS

A total of 87 patients on maintenance hemodialysis and 45 sex- and age-matched healthy controls were included in this prospective study. Serum GDF-15 levels were measured by ELISA. CIMT was assessed by Doppler ultrasonography. The association between serum GDF-15 levels and mortality was assessed using Cox regression analysis with serum levels categorized into two groups according to the median value (328.18 pg/ml). Patients were followed for 2 years and cause-specific and all-cause mortality were determined.

RESULTS

The median level of serum GDF-15 was significantly higher in HD patients than controls [328 (198-522) vs. 176 (101-289) pg/ml, p < 0.01, respectively]. Serum GDF-15 levels were correlated to CIMT (r = 0.607, p < 0.001), C-reactive protein (CRP; r = 0.250, p = 0.010), HD duration (r = 0.376, p = 0.004), and serum albumin (r = - 0.156, p = 0.030). The multivariate analysis revealed that GDF-15 was found to be an independent variable of CIMT in HD patients. In the study, the serum GDF-15 level was an independent marker of all-cause of mortality when adjusted for age, CRP, and history of diabetes mellitus.

CONCLUSION

The relationship between serum GDF-15, mortality, and carotid artery thickening suggests that GDF-15 may be a novel marker of atherosclerosis, inflammation, and malnutrition in HD patients.

[Essential cardiac biomarkers in myocardial infarction and heart failure]

With the discovery of novel biomarkers in cardiovascular diseases, over the past decades considerable improvements in diagnosis, risk stratification and patient care could be achieved; however, despite extensive research, only few biomarkers have met the requirements of significantly improving diagnostic or prognostic approaches. Among the most established markers are cardiac troponins and natriuretic peptides, which are recommended in current guidelines for myocardial infarction or heart failure and are routinely used in clinical practice. Cardiac troponins T and I are the preferred biomarkers of choice for definition of myocardial infarction and proved to be prognostically relevant not only in acute coronary syndrome but also in non-cardiac diseases. The natriuretic peptides B-type natriuretic peptide (BNP) and amino-terminal pro-B-type natriuretic peptide (NT-proBNP) aid in diagnosis, risk stratification and monitoring of heart failure. In recent years several new promising markers have been proposed which might add incremental clinical information, most notably copeptin and growth differentiation factor (GDF) 15; however, larger studies are still required before recommendations for routine clinical use can be made.

Diagnostic performance of serum macrophage inhibitory cytokine-1 in pancreatic cancer: a meta-analysis and meta-regression analysis

Many existing studies have demonstrated that the macrophage inhibitory cytokine-1 (MIC-1) might be a powerful diagnostic biomarker in patients with pancreatic cancer; but individually published results are inconclusive. This meta-analysis aimed to derive a more precise estimation of the diagnostic performance of serum MIC-1 in pancreatic cancer. We searched CISCOM, CINAHL, Web of Science, PubMed, Google Scholar, EBSCO, Cochrane Library, China BioMedicine (CBM), and China National Knowledge Infrastructure (CNKI) databases from their inception through August 1st, 2013. Meta-analysis was performed using Meta-Disc version 1.4 and STATA version 12.0 software. Crude standardized mean difference (SMD) and their 95% confidence intervals (CI) were estimated. Data from selected studies were pooled to yield summary sensitivity, specificity, positive and negative likelihood ratio (LR), diagnostic odds ratio (DOR), and receiver operating characteristic (SROC) curve. Ten case-control studies were included in this meta-analysis with a total of 1235 pancreatic cancer patients and 730 healthy subjects. Our meta-analysis results revealed that serum MIC-1 levels in pancreatic patients were higher than those of healthy subjects (SMD=1.38, 95% CI=1.15-1.62, p<0.001). The area under the SROC curve was 0.92 (SE=0.020); the pooled sensitivity was 0.79 (95% CI=0.77-0.82); and the pooled specificity was 0.86 (95% CI=0.84-0.88). The pooled positive LR was 6.20 (95% CI=1.24-30.91); the pooled DOR was 35.73 (95% CI=18.52-68.93). In conclusion, the present meta-analysis suggests that serum MIC-1 may be a useful diagnostic biomarker with high sensitivity and specificity for identifying pancreatic cancer.

Cardiac biomarkers in heart failure

BACKGROUND

Heart failure is a syndrome characterized by the inability of the heart to meet the body's circulatory demands. Heart failure is a growing health issue worldwide and the prevalence of heart failure is expected to rise as populations age. Therapies and interventions for a variety of cardiac conditions continue to advance and biomarkers will play an increasing role in patient management.

METHODS

This is a review of the clinical research in blood based biomarkers for diagnosis, prognosis and therapeutic guidance of heart failure. The focus of this review is biomarkers that are currently available for clinical measurement, and their current and potential for applications for managing heart failure patients.

RESULTS

The various biologic pathways and physiologic processes of heart failure biomarkers represent a host of different including inflammation, remodeling, strain, neurohormonal activation, metabolism and cardiac myocyte injury. The clinical characteristics and applications of each heart failure biomarker are discussed.

CONCLUSION

As populations age and effective treatments and interventions for coronary artery disease improve, heart failure will increase in incidence and prevalence. Blood biomarkers will play an increasing role in the early diagnosis, therapeutic monitoring and management of heart failure patients in the future.

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.

Genetic deletion of growth differentiation factor 15 augments renal damage in both type 1 and type 2 models of diabetes

Growth differentiation factor 15 (GDF15) is emerging as valuable biomarker in cardiovascular disease and diabetic kidney disease. Also, GDF15 represents an early response gene induced after tissue injury and studies performed in GDF15 knockout (KO) mice suggest that GDF15 plays a protective role after injury. In the current study, we investigated the role of GDF15 in the development of diabetic kidney damage in type 1 and type 2 models of diabetes. Renal damage was assessed in GDF15 KO mice and wild-type (WT) mice in streptozotocin type 1 and db/db type 2 diabetic models. Genetic deletion of GDF15 augmented tubular and interstitial damage in both models of diabetes, despite similar diabetic states in KO and WT mice. Increased tubular damage in KO animals was associated with increased glucosuria and polyuria in both type 1 and type 2 models of diabetes. In both models of diabetes, KO mice showed increased interstitial damage as indicated by increased α-smooth muscle actin staining and collagen type 1 expression. In contrast, glomerular damage was similarly elevated in diabetic KO and WT mice. In type 1 diabetes, GDF15 KO mice demonstrated increased expression of inflammatory markers. In type 2 diabetes, elevated levels of plasma creatinine indicated impaired kidney function in KO mice. GDF15 protects the renal interstitium and tubular compartment in experimental type 1 and 2 diabetes without affecting glomerular damage.

Effects of acute exercise and xanthine oxidase inhibition on novel cardiovascular biomarkers

Several sports have been associated with a postexercise increase of cardiac, liver, and skeletal muscle biomarkers of injury. Exhaustive or acute physical exercise causes an increased generation of reactive oxygen species, resulting in cellular injury. Thus, exercise and training may trigger pathophysiological changes in serum concentrations of a variety of biomarkers. In this study, we aimed to evaluate the variation of novel biomarkers of stress and cardiovascular disease such as copeptin, midregional part of proadrenomedullin (MR-proADM), growth differentiation factor 15 (GDF15), soluble vascular endothelial growth factor receptor, and placental growth factor along with uric acid before and after acute high-intensity exercise and allopurinol administration. We also assessed whether allopurinol administration may affect the circulating levels of these biomarkers by inhibition of XO activity. This is a double-blind, placebo-controlled study in which 12 professional football players were divided into 2 experimental groups. An oral dose of 300 mg of allopurinol was administered to one group of six participants 4 hours before a match of the Spanish Football League, whereas the other 6 participants received placebo (cellulose). Venous blood samples were obtained before the match (baseline) and twelve hours afterwards (post-match). Serum MR-proADM levels increased significantly in the placebo group, whereas serum GDF15 levels increased significantly in both the placebo and allopurinol group after the match. No differences in the other parameters tested were found after the match in any experimental group. The trend toward postexercise increase of serum MR-proADM and GDF15 levels shows that the metabolism of these proteins is clearly imbalanced after exercise, which thereby represents a potential source of biological variability in their clinical assessment.

GDF-15 protects from macrophage accumulation in a mousemodel of advanced atherosclerosis

Background

The cytokine growth differentiation factor-15 (GDF-15), a member of the TGF beta superfamily, has recently been discovered to play an important role in cardiovascular diseases. It is mostly expressed in macrophages of atherosclerotic lesions, but its impact on advanced atherosclerosis is still unknown. This study was performed to evaluate the effects of GDF-15 in an established mouse model of advanced atherosclerosis.

Methods

Thirty-eight LDL receptor deficient mice received a lethal body radiation. Half of the group was transplanted with bone marrow of GDF-15 deficient mice. Nineteen mice were transplanted with bone marrow from wild-type controls. After 24 weeks on an atherogenic diet, animals were euthanized and sections of the aortic sinus were prepared. Lesion size and lesion composition, as well as macrophage content,were evaluated.

Results

While demonstrating no difference in lesion size, LDL-receptor knockout mice transplanted with bone marrow from GDF-15 deficient mice showed enhanced macrophage accumulation and features of atherosclerotic plaque destabilization, such as thinning of fibrous caps. Immunostaining against intercellular adhesion molecule-1 further revealed an increased expression in mice receiving GDF-15-deficient bone marrow.

Conclusions

This is the first study that demonstrates a protective role of GDF-15 in advanced atherosclerosis and macrophage accumulation, possibly due to the reduced expression of adhesion molecules.

Growth differentiation factor-15 deficiency inhibits atherosclerosis progression by regulating interleukin-6-dependent inflammatory response to vascular injury

BACKGROUND

Growth differentiation factor (GDF)-15 is a distant and divergent member of the transforming growth factor-β superfamily (TGF-β) . There is growing evidence indicating the involvement of GDF-15 in various pathologies. Expression of GDF-15 is induced under conditions of inflammation and increased GDF-15 serum levels are suggested as a risk factor for cardiovascular diseases.

METHODS AND RESULTS

We show here that GDF-15 and proinflammatory cytokine interleukin (IL)-6 levels are highly increased (5-fold) in cultured oxidized low-density lipoproteins-stimulated peritoneal macrophages derived from GDF-15(+/+)/apolipoprotein (apo) E(-/-), mice. Notably, IL-6 induction on oxidized low-density lipoproteins stimulation is completely abolished in the absence of GDF-15. Consistent with our in vitro data GDF-15 mRNA expression and protein levels are upregulated (2.5- to 6-fold) in the atherosclerotic vessel wall of GDF-15(+/+)/apoE(-/-) mice after a cholesterol-enriched diet. GDF-15 deficiency inhibits lumen stenosis (52%) and (18)FDG uptake (34%) in the aortic arch despite increased serum triglyceride/cholesterol levels and elevated body weight. Immunohistomorphometric investigations of atherosclerotic lesions reveal a decreased percentage of inflammatory CD11b(+) (57%) or IL-6(+), leukocytes, and apoptotic cells (74%) after 20 weeks. However, the total number of macrophages and cell density in atherosclerotic lesions of the innominate artery are increased in GDF-15(-/-)/apoE(-/-) mice.

CONCLUSIONS

Our data suggest that GDF-15 is involved in orchestrating atherosclerotic lesion progression by regulating apoptotic cell death and IL-6-dependent inflammatory responses to vascular injury.

Growth-differentiation factor 15 predicts worsening of albuminuria in patients with type 2 diabetes

OBJECTIVE

Development of micro- or macroalbuminuria is associated with increased risk of cardiorenal complications, particularly in diabetes. For prevention of transition to micro- or macroalbuminuria, more accurate prediction markers on top of classical risk markers are needed. We studied a promising new marker, growth-differentiation factor (GDF)-15, to predict transition to increasing stage of albuminuria in type 2 diabetes mellitus (T2DM). In addition, we looked at the GDF-15 potential in nondiabetic subjects with hypertension (HT).

RESEARCH DESIGN AND METHODS

Case and control subjects were selected from the PREVEND cohort, a large (n = 8,592), prospective general population study on the natural course of albuminuria, with >10 years of follow-up and repeated albuminuria measurements. We found 24 T2DM and 50 HT case subjects transitioning from normo- to macroalbuminuria and 9 T2DM and 25 HT case subjects transitioning from micro- to macroalbuminuria (average follow-up 2.8 years). Control subjects with stable albuminuria were pair matched for age, sex, albuminuria status, and diabetes duration. GDF-15 was measured in samples prior to albuminuria transition.

RESULTS

Prior to transition, GDF-15 was significantly higher in case subjects with T2DM than in control subjects (median [IQR] 1,288 pg/mL [885-1,546] vs. 948 pg/mL [660-1,016], P < 0.001). The odds ratio for transition in albuminuria increased significantly per SD of GDF-15 (2.9 [95% CI 1.1-7.5], P = 0.03). GDF-15 also improved prediction of albuminuria transition, with significant increases in C statistic (from 0.87 to 0.92, P = 0.03) and integrated discrimination improvement (0.148, P = 0.001). In HT, GDF-15 was also independently associated with transition in albuminuria stage (2.0 [1.1-3.5], P = 0.02) and improved prediction significantly.

CONCLUSIONS

We identified GDF-15 as a clinically valuable marker for predicting transition in albuminuria stage in T2DM beyond conventional risk markers. These findings were confirmed in nondiabetic HT subjects.

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.

Prognostic utility of novel biomarkers of cardiovascular stress: the Framingham Heart Study

BACKGROUND

Biomarkers for predicting cardiovascular events in community-based populations have not consistently added information to standard risk factors. A limitation of many previously studied biomarkers is their lack of cardiovascular specificity.

METHODS AND RESULTS

To determine the prognostic value of 3 novel biomarkers induced by cardiovascular stress, we measured soluble ST2, growth differentiation factor-15, and high-sensitivity troponin I in 3428 participants (mean age, 59 years; 53% women) in the Framingham Heart Study. We performed multivariable-adjusted proportional hazards models to assess the individual and combined ability of the biomarkers to predict adverse outcomes. We also constructed a "multimarker" score composed of the 3 biomarkers in addition to B-type natriuretic peptide and high-sensitivity C-reactive protein. During a mean follow-up of 11.3 years, there were 488 deaths, 336 major cardiovascular events, 162 heart failure events, and 142 coronary events. In multivariable-adjusted models, the 3 new biomarkers were associated with each end point (P<0.001) except coronary events. Individuals with multimarker scores in the highest quartile had a 3-fold risk of death (adjusted hazard ratio, 3.2; 95% confidence interval, 2.2-4.7; P<0.001), 6-fold risk of heart failure (6.2; 95% confidence interval, 2.6-14.8; P<0.001), and 2-fold risk of cardiovascular events (1.9; 95% confidence interval, 1.3-2.7; P=0.001). Addition of the multimarker score to clinical variables led to significant increases in the c statistic (P=0.005 or lower) and net reclassification improvement (P=0.001 or lower).

CONCLUSION

Multiple biomarkers of cardiovascular stress are detectable in ambulatory individuals and add prognostic value to standard risk factors for predicting death, overall cardiovascular events, and heart failure.

Identification of follistatin-like 1 by expression cloning as an activator of the growth differentiation factor 15 gene and a prognostic biomarker in acute coronary syndrome

BACKGROUND

Growth differentiation factor 15 (GDF15) is a stress-responsive cytokine and biomarker that is produced after myocardial infarction and that is related to prognosis in acute coronary syndrome (ACS). We hypothesized that secreted proteins that activate GDF15 production may represent new ACS biomarkers.

METHODS

We expressed clones from an infarcted mouse heart cDNA library in COS1 cells and assayed for activation of a luciferase reporter gene controlled by a 642-bp fragment of the mouse growth differentiation factor 15 (GDF15) gene promoter. We measured the circulating concentrations of follistatin-like 1 (FSTL1) and GDF15 in 1369 patients with ACS.

RESULTS

One cDNA clone that activated the GDF15 promoter-luciferase reporter encoded the secreted protein FSTL1. Treatment with FSTL1 activated GDF15 production in cultured cardiomyocytes. Transgenic production of FSTL1 stimulated GDF15 production in the murine heart, whereas cardiomyocyte-selective deletion of FSTL1 decreased production of GDF15 in cardiomyocytes, indicating that FSTL1 is sufficient and required for GDF15 production. In ACS, FSTL1 emerged as the strongest independent correlate of GDF15 (partial R(2) = 0.26). A total of 106 patients died of a cardiovascular cause during a median follow-up of 252 days. Patients with an FSTL1 concentration in the top quartile had a 3.7-fold higher risk of cardiovascular death compared with patients in the first 3 quartiles (P < 0.001). FSTL1 remained associated with cardiovascular death after adjustment for clinical, angiographic, and biochemical variables.

CONCLUSIONS

Our study is the first to use expression cloning for biomarker discovery upstream of a gene of interest and to identify FSTL1 as an independent prognostic biomarker in ACS.

Biomarkers in acute myocardial injury

Acute coronary syndrome (ACS) is a significant cause of morbidity and mortality worldwide. The proper diagnosis of ACS requires reliable and accurate biomarker assays to detect evidence of myocardial necrosis. Currently, troponin is the gold standard biomarker for myocardial injury and is used commonly in conjunction with creatine kinase-MB (CK-MB) and myoglobin to enable a more rapid diagnosis of ACS. A new generation of highly sensitive troponin assays with improved accuracy in the early detection of ACS is now available, but the correct interpretation of assay results will require a careful consideration of assay characteristics and the clinical setting prior to incorporation into routine practice. B-type natriuretic peptides, copeptin, ischemia-modified albumin, heart-type fatty-acid-binding protein, myeloperoxidase, C-reactive protein, choline, placental growth factor, and growth-differentiation factor-15 make up a promising group of other biomarkers that have shown the ability to improve prognosis and diagnosis of ACS compared with traditional markers.

Increased expression of the TGF-b superfamily cytokine MIC-1/GDF15 protects ApoE(-/-) mice from the development of atherosclerosis

AIM

MIC-1/GDF15 is a member of the TGF-b superfamily, which is thought to have pleiotropic roles in stress responses, inflammation, tissue injury and repair, energy homeostasis, and malignancy. MIC-1/GDF15 was recently identified as a new biomarker for the development of cardiovascular events and the outcome of atherosclerotic disease therapy. The aim of our study was to determine if MIC-1 also directly exerts pro- or antiatherogenic properties during the development of atherosclerosis.

METHODS AND RESULTS

We investigated the effect of transgenic overexpression of MIC-1 in macrophages in the ApoE(-/-) mouse model of atherosclerosis. After 6 months of high-fat diet, MIC-1/GDF15 transgenic ApoE(-/-) mice had smaller atherosclerotic lesions; however, no differences in lesion composition, pro- or anti-inflammatory cytokine production, or serum levels of lipids or cytokines were detected.

CONCLUSIONS

Our results suggest that MIC-1 has an overall protective effect on the disease process, but further studies will be required to define its mechanism of action.

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.

Growth/differentiation factor-15: prostate cancer suppressor or promoter?

Deregulation of expression and function of cytokines belonging to the transforming growth factor-β (TGF-β) family is often associated with various pathologies. For example, this cytokine family has been considered a promising target for cancer therapy. However, the detailed functions of several cytokines from the TGF-β family that could have a role in cancer progression and therapy remain unclear. One of these molecules is growth/differentiation factor-15 (GDF-15), a divergent member of the TGF-β family. This stress-induced cytokine has been proposed to possess immunomodulatory functions and its high expression is often associated with cancer progression, including prostate cancer (PCa). However, studies clearly demonstrating the mechanisms for signal transduction and functions in cell interaction, cancer progression and therapy are still lacking. New GDF-15 roles have recently been identified for modulating osteoclast differentiation and for therapy for PCa bone metastases. Moreover, GDF-15 is as an abundant cytokine in seminal plasma with immunosuppressive properties. We discuss studies that focus on the regulation of GDF-15 expression and its role in tissue homeostasis, repair and the immune response with an emphasis on the role in PCa development.

Adjustment of the GRACE score by growth differentiation factor 15 enables a more accurate appreciation of risk in non-ST-elevation acute coronary syndrome

AIMS

The aim of the study was to evaluate whether knowledge of the circulating concentration of growth differentiation factor 15 (GDF-15) adds predictive information to the Global Registry of Acute Coronary Events (GRACE) score, a validated scoring system for risk assessment in non-ST-elevation acute coronary syndrome (NSTE-ACS). We also evaluated whether GDF-15 adds predictive information to a model containing the GRACE score and N-terminal pro-B-type natriuretic peptide (NT-proBNP), a prognostic biomarker already in clinical use.

METHODS AND RESULTS

The GRACE score, GDF-15, and NT-proBNP levels were determined on admission in 1122 contemporary patients with NSTE-ACS. Six-month all-cause mortality or non-fatal myocardial infarction (MI) was the primary endpoint of the study. To obtain GDF-15- and NT-proBNP-adjusted 6-month estimated probabilities of death or non-fatal MI, statistical algorithms were developed in a derivation cohort (n = 754; n = 66 reached the primary endpoint) and applied to a validation cohort (n = 368; n = 33). Adjustment of the GRACE risk estimate by GDF-15 increased the area under the receiver-operating characteristic curve (AUC) from 0.79 to 0.85 (P < 0.001) in the validation cohort. Discrimination improvement was confirmed by an integrated discrimination improvement (IDI) of 0.055 (P = 0.005). A net 31% of the patients without events were reclassified into lower risk, and a net 27% of the patients with events were reclassified into higher risk, resulting in a total continuous net reclassification improvement [NRI(>0)] of 0.58 (P = 0.002). Addition of NT-proBNP to the GRACE score led to a similar improvement in discrimination and reclassification. Addition of GDF-15 to a model containing GRACE and NT-proBNP led to a further improvement in model performance [increase in AUC from 0.84 for GRACE plus NT-proBNP to 0.86 for GRACE plus NT-proBNP plus GDF-15, P = 0.010; IDI = 0.024, P = 0.063; NRI(>0) = 0.42, P = 0.022].

CONCLUSION

We show that a single measurement of GDF-15 on admission markedly enhances the predictive value of the GRACE score and provides moderate incremental information to a model including the GRACE score and NT-proBNP. Our study is the first to provide simple algorithms that can be used by the practicing clinician to more precisely estimate risk in individual patients based on the GRACE score and a single biomarker measurement on admission. The rigorous statistical approach taken in the present study may serve as a blueprint for future studies exploring the added value of biomarkers beyond clinical risk scores.

Clinical significance of serum growth differentiation factor-15 levels in systemic sclerosis: association with disease severity

OBJECTIVE

To determine serum growth differentiation factor-15 (GDF-15) levels and their clinical associations in patients with systemic sclerosis (SSc).

METHODS

Serum GDF-15 levels were examined by enzyme-linked immunosorbent assay in 61 patients with SSc and 24 healthy individuals. In a retrospective longitudinal study, sera from 14 patients with SSc were analyzed (duration of follow-up 1.2-7.2 years).

RESULTS

Serum GDF-15 levels were significantly elevated in SSc patients (1340 ± 910 pg/ml) compared with healthy individuals (213 ± 79 pg/ml; P < 0.001). Among SSc patients, patients with diffuse cutaneous SSc (n = 31) had higher levels of serum GDF-15 (1609 ± 1069 pg/ml) than those with limited cutaneous SSc (n = 30; 1142 ± 646 pg/ml; P < 0.05). SSc patients with high GDF-15 levels (≥1000 pg/ml) had pulmonary fibrosis, decreased vital capacity, and decreased diffusion capacity for carbon monoxide more often than those with low GDF-15 levels (<1000 pg/ml). GDF-15 levels correlated positively with the extent of skin sclerosis and inversely with percentage vital capacity and diffusion capacity for carbon monoxide in patients with SSc. In a longitudinal study, serum GDF-15 levels were generally decreased during the follow-up.

CONCLUSION

Serum GDF-15 levels were increased in patients with SSc and associated with the extent of skin sclerosis and the severity of pulmonary fibrosis. These results suggest that GDF-15 may play a role in the development of cutaneous and pulmonary fibrosis in SSc. Measurement of serum GDF-15 may be useful for risk stratification in early disease stage.

Mechanisms of crystalline silica-induced pulmonary toxicity revealed by global gene expression profiling

A proper understanding of the mechanisms underlying crystalline silica-induced pulmonary toxicity has implications in the management and potential prevention of the adverse health effects associated with silica exposure including silicosis, cancer and several auto-immune diseases. Human lung type II epithelial cells and rat lungs exposed to crystalline silica were employed as experimental models to determine global gene expression changes in order to understand the molecular mechanisms underlying silica-induced pulmonary toxicity. The differential gene expression profile induced by silica correlated with its toxicity in the A549 cells. The biological processes perturbed by silica exposure in the A549 cells and rat lungs, as identified by the bioinformatics analysis of the differentially expressed genes, demonstrated significant similarity. Functional categorization of the differentially expressed genes identified cancer, cellular movement, cellular growth and proliferation, cell death, inflammatory response, cell cycle, cellular development, and genetic disorder as top ranking biological functions perturbed by silica exposure in A549 cells and rat lungs. Results of our study, in addition to confirming several previously identified molecular targets and mechanisms involved in silica toxicity, identified novel molecular targets and mechanisms potentially involved in silica-induced pulmonary toxicity. Further investigations, including those focused on the novel molecular targets and mechanisms identified in the current study may result in better management and, possibly, reduction and/or prevention of the potential adverse health effects associated with crystalline silica exposure.

Emerging biomarkers in heart failure

BACKGROUND

Until recently, biomarker testing in heart failure (HF) syndromes has been viewed as an elective supplement to diagnostic evaluation of patients suspected to suffer from this condition. This approach to the use of biomarker testing contrasts with other cardiovascular diagnoses such as acute myocardial infarction, for which biomarkers are integral to disease process definition, risk stratification, and in some cases treatment decision making.

CONTENT

In this review we consider various perspectives on the evaluation of biomarkers in HF. In addition, we examine recent advances in the understanding of established biomarkers in HF (such as the natriuretic peptides), the elucidation of novel biomarkers potentially useful for the evaluation and management of patients with HF, and the growing understanding of important and relevant comorbidities in HF. We also review candidate biomarkers from a number of classes: (a) myocyte stretch, (b) myocyte necrosis, (c) systemic inflammation, (d) oxidative stress, (e) extracellular matrix turnover, (f) neurohormones, and (g) biomarkers of extracardiac processes, such as renal function.

SUMMARY

Novel applications of established biomarkers of HF as well as elucidation and validation of emerging assays for HF syndromes have collectively led to a growing interest in the more widespread use of such testing in patients affected by the diagnosis.

Association of growth differentiation factor-15 with coronary atherosclerosis and mortality in a young, multiethnic population: observations from the Dallas Heart Study

BACKGROUND

Growth differentiation factor 15 (GDF-15) is produced by cardiomyocytes and atherosclerotic lesions under stress conditions. Although higher circulating GDF-15 concentrations are associated with mortality across a spectrum of cardiovascular conditions, the relationship of GDF-15 with atherosclerosis and mortality in the general population remains undefined.

METHODS

We measured plasma GDF-15 in 3219 participants of the Dallas Heart Study, a population sample of adults ages 30-65 years (55% women, 49% black). GDF-15 was analyzed in prespecified categories (<1200; 1200-1799; and ≥1800 ng/L) and continuously. End points included prevalent coronary artery calcium (CAC>10 Agatston units), increased CAC (CAC≥100 Agatston units) by electron beam computed tomography, and mortality through a median 7.3 years of follow-up (120 deaths, 48 cardiovascular deaths).

RESULTS

Increasing GDF-15 associated with older age, black race, hypertension, diabetes, smoking, left ventricular (LV) mass/body surface area, and worse renal function (P<0.0001 for each). In multivariable models adjusted for traditional risk factors, renal function, and LV mass/body surface area, GDF-15≥1800 ng/L was associated with CAC>10 (odds ratio 2.1; 95% CI 1.2-3.7; P=0.01), CAC≥100 (odds ratio 2.6; 95% CI 1.4-4.9; P=0.002), all-cause mortality (hazard ratio 3.5; 95% CI 2.1-5.9, P<0.0001), and cardiovascular mortality (hazard ratio 2.5; 95% CI 1.1-5.8, P=0.03). Adding log GDF-15 to fully adjusted models modestly improved the c statistic (P=0.025), the integrated discrimination index (0.028; P<0.0001) and the category-less net reclassification index (0.42; P=0.002). These findings remained significant with further adjustment for high-sensitivity C-reactive protein, N-terminal pro-B-type natriuretic peptide, and cardiac troponin T.

CONCLUSIONS

GDF-15 is independently associated with subclinical coronary atherosclerosis and mortality, and its potential role for risk stratification in the general population merits further evaluation.

GDF-15 is abundantly expressed in plexiform lesions in patients with pulmonary arterial hypertension and affects proliferation and apoptosis of pulmonary endothelial cells

BACKGROUND

Growth-differentiation factor-15 (GDF-15) is a stress-responsive, transforming growth factor-β-related cytokine, which has recently been reported to be elevated in serum of patients with idiopathic pulmonary arterial hypertension (IPAH). The aim of the study was to examine the expression and biological roles of GDF-15 in the lung of patients with pulmonary arterial hypertension (PAH).

METHODS

GDF-15 expression in normal lungs and lung specimens of PAH patients were studied by real-time RT-PCR and immunohistochemistry. Using laser-assisted micro-dissection, GDF-15 expression was further analyzed within vascular compartments of PAH lungs. To elucidate the role of GDF-15 on endothelial cells, human pulmonary microvascular endothelial cells (HPMEC) were exposed to hypoxia and laminar shear stress. The effects of GDF-15 on the proliferation and cell death of HPMEC were studied using recombinant GDF-15 protein.

RESULTS

GDF-15 expression was found to be increased in lung specimens from PAH patients, compared to normal lungs. GDF-15 was abundantly expressed in pulmonary vascular endothelial cells with a strong signal in the core of plexiform lesions. HPMEC responded with marked upregulation of GDF-15 to hypoxia and laminar shear stress. Apoptotic cell death of HPMEC was diminished, whereas HPMEC proliferation was either increased or decreased depending of the concentration of recombinant GDF-15 protein.

CONCLUSIONS

GDF-15 expression is increased in PAH lungs and appears predominantly located in vascular endothelial cells. The expression pattern as well as the observed effects on proliferation and apoptosis of pulmonary endothelial cells suggest a role of GDF-15 in the homeostasis of endothelial cells in PAH patients.

Growth-differentiation factor-15 is a robust, independent predictor of 11-year mortality risk in community-dwelling older adults: the Rancho Bernardo Study

BACKGROUND

Growth-differentiation factor-15 (GDF-15) is emerging as a prognostic marker in patients with cardiovascular disease (CVD), but its prognostic value in community-dwelling adults has not been reported. We hypothesized that GDF-15 would add incremental power for prediction of mortality in a population of community-dwelling older adults without known heart disease.

METHODS AND RESULTS

We measured plasma GDF-15, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and C-reactive protein levels in 1391 Rancho Bernardo Study participants, mean age 70 years, with no history of CVD and followed them for a mean of 11 years. In models adjusted for traditional CVD risk factors, GDF-15 was a robust predictor of all-cause, cardiovascular, and noncardiovascular mortality. GDF-15 was a stronger predictor of all-cause mortality than either NT-proBNP or C-reactive protein (hazard ratio [95% confidence interval] per SD log(10) units 1.5 [1.3 to 1.8], P<0.0001 for GDF-15 versus 1.3 [1.2 to 1.5], P<0.0001 for NT-proBNP; C-reactive protein was not a significant predictor). Among biomarkers considered, only GDF-15 predicted noncardiovascular death (hazard ratio 1.6 [1.4 to 2.0], P<0.0001). Growth differentiation factor-15 improved discrimination and modestly but significantly improved reclassification for all-cause and noncardiovascular mortality with borderline improvement for cardiovascular mortality; NT-proBNP significantly improved reclassification for all-cause and for cardiovascular mortality; C-reactive protein did not improve reclassification for any end point tested. Participants in the highest quartile of both GDF-15 and NT-proBNP had an increased risk of death compared with participants with only NT-proBNP elevated (hazard ratio 1.5 [1.1 to 2.0], P=0.01).

CONCLUSIONS

Growth differentiation factor-15 is a strong predictor of all-cause, cardiovascular, and noncardiovascular mortality in community-dwelling older individuals, adding incremental value to traditional risk factors and to NT-proBNP and C-reactive protein levels.

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.

Regulation of GDF-15, a distant TGF-β superfamily member, in a mouse model of cerebral ischemia

GDF-15 is a novel distant member of the TGF-β superfamily and is widely distributed in the brain and peripheral nervous system. We have previously reported that GDF-15 is a potent neurotrophic factor for lesioned dopaminergic neurons in the substantia nigra, and that GDF-15-deficient mice show progressive postnatal losses of motor and sensory neurons. We have now investigated the regulation of GDF-15 mRNA and immunoreactivity in the murine hippocampal formation and selected cortical areas following an ischemic lesion by occlusion of the middle cerebral artery (MCAO). MCAO prominently upregulates GDF-15 mRNA in the hippocampus and parietal cortex at 3 h and 24 h after lesion. GDF-15 immunoreactivity, which is hardly detectable in the unlesioned brain, is drastically upregulated in neurons identified by double-staining with NeuN. NeuN staining reveals that most, if not all, neurons in the granular layer of the dentate gyrus and pyramidal layers of the cornu ammonis become GDF-15-immunoreactive. Moderate induction of GDF-15 immunoreactivity has been observed in a small number of microglial cells identified by labeling with tomato lectin, whereas astroglial cells remain GDF-15-negative after MCAO. Comparative analysis of the size of the infarcted area after MCAO in GDF-15 wild-type and knockout mice has failed to reveal significant differences. Together, our data substantiate the notion that GDF-15 is prominently upregulated in the lesioned brain and might be involved in orchestrating post-lesional responses other than the trophic support of neurons.

The TGF-beta superfamily cytokine MIC-1/GDF15: secretory mechanisms facilitate creation of latent stromal stores

Macrophage inhibitory cytokine-1/growth differentiation factor 15 (MIC-1/GDF15), a divergent member of the TGF-beta superfamily is induced by a range of proinflammatory cytokines and oxidized low-density lipoprotein (oxLDL) and is highly expressed in macrophages in atherosclerotic and tumor lesions. MIC-1/GDF15, a major p53 target gene, is largely described to have anti-tumorigenic activity and more recently high MIC-1/GDF15 serum levels in late stage cancer were shown to be the major cause of cancer-associated weight loss. MIC-1/GDF15 serum levels independently predict both atherosclerotic events and severity of rheumatoid arthritis (RA), suggesting serum levels are important in modifying disease expression. Controlling serum levels is the ratio of latent unprocessed MIC-1/GDF15 stromal stores to soluble mature MIC-1/GDF15 generated by the cell. Here, we investigate MIC-1/GDF15 secretion from U937 monocytoid cells and identify novel mechanisms designed to ensure secretion of unprocessed cytokine and creation of latent stromal stores. We find that endogenous MIC-1/GDF15 is secreted as both processed and unprocessed forms. Pulse chase analysis of MIC-1/GDF15 secretion reveals that unprocessed MIC-1/GDF15 precursor is rapidly secreted, while mature MIC-1/GDF15 generated within the cell by intracellular processing is secreted much slower, possibly via an alternate secretory route. The COOH-T 47 amino acids of the propeptide are responsible for rapid secretion of MIC-1/GDF15 precursor and this effect occurs in the trans-Golgi network (TGN)/post TGN compartment. Thus, variations in MIC-1/GDF15 intracellular processing, regulating the presence or absence of propeptide, are a powerful mechanism modulating rate of MIC-1/GDF15 secretion and proMIC-1/GDF15 stromal storage, with major impact on circulating levels of mature MIC-1/GDF15.

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.

Serial measurement of growth-differentiation factor-15 in heart failure: relation to disease severity and prognosis in the Valsartan Heart Failure Trial

BACKGROUND

Growth-differentiation factor-15 (GDF-15) is emerging as a prognostic biomarker in patients with coronary artery disease. Little is known about GDF-15 as a biomarker in patients with heart failure.

METHODS AND RESULTS

The circulating concentration of GDF-15 was measured at baseline (n=1734) and at 12 months (n=1517) in patients randomized in the Valsartan Heart Failure Trial (Val-HeFT). GDF-15 levels at baseline ranged from 259 to 25 637 ng/L and were abnormally high (>1200 ng/L) in 85% of patients. Higher levels were associated with features of worse heart failure and biomarkers of neurohormonal activation, inflammation, myocyte injury, and renal dysfunction. Baseline GDF-15 levels (per 100 ng/L) were associated with the risks of mortality (hazard ratio, 1.017; 95% confidence interval, 1.014 to 1.019; P<0.001) and first morbid event (hazard ratio, 1.020; 95% confidence interval, 1.017 to 1.023; P<0.001). In a comprehensive multiple-variable Cox regression model that included clinical prognostic variables, B-type natriuretic peptide, high-sensitivity C-reactive protein, and high-sensitivity troponin T, GDF-15 remained independently associated with mortality (hazard ratio, 1.007; 95% confidence interval, 1.001 to 1.014; P=0.02) but not first morbid event. At 12 months, the GDF-15 levels had increased by a similar amount in the placebo and valsartan groups (P=0.94). Increases in GDF-15 over 12 months were independently associated with the risks of future mortality and first morbid event also after adjustment for clinical prognostic variables, B-type natriuretic peptide, high-sensitivity C-reactive protein, and high-sensitivity troponin T and their changes.

CONCLUSIONS

GDF-15 reflects information from several pathological pathways and provides independent prognostic information in heart failure. GDF-15 levels increase over time, suggesting that GDF-15 reflects a pathophysiological axis that is not completely addressed by the therapies prescribed in Val-HeFT.

Increased expression of growth differentiation factor-15 in systemic sclerosis-associated pulmonary arterial hypertension

BACKGROUND

Growth differentiation factor (GDF)-15 is a secreted member of the transforming growth factor-β cytokine superfamily. GDF-15 levels are elevated in the serum of patients with cardiovascular diseases. We hypothesized that GDF-15 levels would also be increased in the plasma and lung tissue of patients with systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH).

METHODS

GDF-15 levels were measured in plasma in subjects with SSc-PAH (n = 30) and compared with subjects with systemic sclerosis (SSc) without pulmonary arterial hypertension (PAH) (n = 24). Patients with idiopathic PAH (IPAH) (n = 44) and normal individuals (n = 13) served as control subjects. Immunohistochemistry and immunofluorescence assay identified GDF-15 protein in lung tissue from patients with SSc-PAH and IPAH.

RESULTS

Patients with SSc-PAH had significantly higher mean circulating levels of GDF-15 in plasma compared with patients with SSc without PAH (422.3 ± 369.5 pg/mL vs 108.1 ± 192.8 pg/mL, P = .004). GDF-15 levels correlated positively with estimated right ventricular systolic pressure on echocardiogram and plasma levels of the amino terminal propeptide form of brain natriuretic peptide. There was an inverse correlation between circulating GDF-15 and diffusing capacity of the lung for carbon monoxide (Dlco) and a positive correlation with the FVC to Dlco ratio on pulmonary function test. GDF-15 levels > 125 pg/mL were associated with reduced survival. GDF-15 protein expression was increased in lung tissue from patients with SSc-PAH.

CONCLUSIONS

GDF-15 may be a useful biomarker in PAH associated with SSc. Its presence in lung tissue may suggest a role in the pathology of the disease.

Plasma growth differentiation factor-15 independently predicts all-cause and cardiovascular mortality as well as deterioration of kidney function in type 1 diabetic patients with nephropathy

OBJECTIVE

Growth deferentiation factor-15 (GDF-15) is involved in inflammation and apoptosis. Expression is induced in the heart in response to ischemia and in atherosclerotic plaques. The aim of this study was to investigate GDF-15 levels in relation to all-cause mortality, cardiovascular mortality and morbidity, decline in glomerular filtration rate (GFR), and progression toward end-stage renal disease (ESRD).

RESEARCH DESIGN AND METHODS

The study was a prospective observational follow-up study including 451 type 1 diabetic patients with diabetic nephropathy (274 men, aged 42.1 +/- 0.5 years [means +/- SD], diabetes duration 28.3 +/- 8.9 years, GFR 76 +/- 33 ml/min/1.73 m(2)) and a control group of 440 patients with longstanding type 1 diabetes and persistent normoalbuminuria (232 men, aged 45.4 +/- 11.5 years, duration of diabetes 27.7 +/- 10.1 years). The patients were followed for 8.1 (0.0-12.9) years (median [range]).

RESULTS

Among normoalbuminuric patients, GDF-15 above the median predicted an adjusted (age, systolic blood pressure [sBP], and estimated GFR) increased risk of all-cause mortality (hazard ratio [HR] 3.6 [95% CI 1.3-10.3]; P = 0.014). Among patients with diabetic nephropathy, higher (fourth quartile) versus lower (first quartile) GDF-15 levels predict all-cause mortality (covariate-adjusted [sex, age, smoking, blood pressure, A1C, cholesterol, GFR, N-terminal prohormone B-type natriuretic peptide, antihypertensive treatment, and previous cardiovascular events]; HR 4.86 [95% CI 1.37-17.30]) as well as fatal and nonfatal cardiovascular events (adjusted HR 5.59 [1.23-25.43] and 3.55 [1.08-11.64], respectively). In addition, higher GDF-15 levels predict faster decline in GFR (P < 0.001) but not development of ESRD.

CONCLUSIONS

Higher levels of GDF-15 are a predictor of all-cause and cardiovascular mortality and morbidity in patients with diabetic nephropathy. Furthermore, higher levels of GDF-15 are associated with faster deterioration of kidney function.

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.

Growth-Differentiation Factor-15 for Long-Term Risk Prediction in Patients Stabilized After an Episode of Non–ST-Segment–Elevation Acute Coronary Syndrome

Background— Growth-differentiation factor-15 (GDF-15) has emerged as a prognostic biomarker in patients with non–ST-segment–elevation acute coronary syndrome. This study assessed the time course and the long-term prognostic relevance of GDF-15 levels measured repetitively in patients with non–ST-segment–elevation acute coronary syndrome during 6 months after the acute event.

Methods and Results— GDF-15 and other biomarkers were measured at randomization, after 6 weeks, and after 3 and 6 months in 950 patients with non–ST-segment–elevation acute coronary syndrome included in the FRagmin and Fast Revascularization during InStability in Coronary artery disease II study. Study end points were death, recurrent myocardial infarction, and their composite during 5-year follow-up. Median GDF-15 levels decreased slightly from 1357 ng/L at randomization to 1302 ng/L at 6 months ( P <0.001). GDF-15 was consistently related to cardiovascular risk factors and biochemical markers of hemodynamic stress, renal dysfunction, and inflammation. Moreover, GDF-15 was independently related to the 5-year risk of the composite end point when measured at both 3 months (adjusted hazard ratio, 1.8 [1.0 to 3.0]) and 6 months (adjusted hazard ratio, 2.3 [1.3 to 4.1]). Serial measurements of GDF-15 at randomization and 6 months helped to identify patient cohorts at different levels of risk, with patients with persistently elevated GDF-15 levels >1800 ng/L having the highest rate of the composite end point.

Conclusions— GDF-15 is independently related to adverse events in non–ST-segment–elevation acute coronary syndrome both in the acute setting and for at least 6 months after clinical stabilization. Therefore, continued research on GDF-15 should be focused on the usefulness of GDF-15 for support of clinical management in acute and chronic ischemic heart disease.

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.