Christian Widera

Diagnostic and prognostic impact of six circulating microRNAs in acute coronary syndrome

Circulating microRNAs may have diagnostic potential in acute coronary syndrome (ACS). Previous studies, however, were based on low patient numbers and could not assess the relation of microRNAs to clinical characteristics and their potential prognostic value. We thus assessed the diagnostic and prognostic value of cardiomyocyte-enriched microRNAs in the context of clinical variables and a sensitive myonecrosis biomarker in a larger ACS cohort. MiR-1, miR-133a, miR-133b, miR-208a, miR-208b, and miR-499 concentrations were measured by quantitative reverse transcription PCR in plasma samples obtained on admission from 444 patients with ACS. High-sensitivity troponin T (hsTnT) was measured by immunoassay. Patients were followed for 6 months regarding all-cause mortality. In a multiple linear regression analysis that included clinical variables and hsTnT, miR-1, miR-133a, miR-133b, and miR-208b were independently associated with hsTnT levels (all P<0.001). Patients with myocardial infarction presented with higher levels of miR-1, miR-133a, and miR-208b compared with patients with unstable angina. However, all six investigated microRNAs showed a large overlap between patients with unstable angina or myocardial infarction. MiR-133a and miR-208b levels were significantly associated with the risk of death in univariate and age- and gender-adjusted analyses. Both microRNAs lost their independent association with outcome upon further adjustment for hsTnT. The present study tempers speculations about the potential usefulness of cardiomyocyte-enriched microRNAs as diagnostic or prognostic markers in ACS.

GDF-15 is an inhibitor of leukocyte integrin activation required for survival after myocardial infarction in mice

Inflammatory cell recruitment after myocardial infarction needs to be tightly controlled to permit infarct healing while avoiding fatal complications such as cardiac rupture. Growth differentiation factor-15 (GDF-15), a transforming growth factor-β (TGF-β)–related cytokine, is induced in the infarcted heart of mice and humans. We show that coronary artery ligation in Gdf15-deficient mice led to enhanced recruitment of polymorphonuclear leukocytes (PMNs) into the infarcted myocardium and an increased incidence of cardiac rupture. Conversely, infusion of recombinant GDF-15 repressed PMN recruitment after myocardial infarction. In vitro, GDF-15 inhibited PMN adhesion, arrest under flow and transendothelial migration. Mechanistically, GDF-15 counteracted chemokine-triggered conformational activation and clustering of β2 integrins on PMNs by activating the small GTPase Cdc42 and inhibiting activation of the small GTPase Rap1. Intravital microscopy in vivo in Gdf15-deficient mice showed that Gdf-15 is required to prevent excessive chemokine-activated leukocyte arrest on the endothelium. Genetic ablation of β2 integrins in myeloid cells rescued the mortality of Gdf15-deficient mice after myocardial infarction. To our knowledge, GDF-15 is the first cytokine identified as an inhibitor of PMN recruitment by direct interference with chemokine signaling and integrin activation. Loss of this anti-inflammatory mechanism leads to fatal cardiac rupture after myocardial infarction.

A signature of circulating microRNAs differentiates takotsubo cardiomyopathy from acute myocardial infarction

Aims Takotsubo cardiomyopathy (TTC) remains a potentially life-threatening disease, which is clinically indistinguishable from acute myocardial infarction (MI). Today, no established biomarkers are available for the early diagnosis of TTC and differentiation from MI. MicroRNAs (miRNAs/miRs) emerge as promising sensitive and specific biomarkers for cardiovascular disease. Thus, we sought to identify circulating miRNAs suitable for diagnosis of acute TTC and for distinguishing TTC from acute MI. Methods and results After miRNA profiling, eight miRNAs were selected for verification by real-time quantitative reverse transcription polymerase chain reaction in patients with TTC (n = 36), ST-segment elevation acute myocardial infarction (STEMI, n = 27), and healthy controls (n = 28). We quantitatively confirmed up-regulation of miR-16 and miR-26a in patients with TTC compared with healthy subjects (both, P < 0.001), and up-regulation of miR-16, miR-26a, and let-7f compared with STEMI patients (P < 0.0001, P < 0.05, and P < 0.05, respectively). Consistent with previous publications, cardiac specific miR-1 and miR-133a were up-regulated in STEMI patients compared with healthy controls (both, P < 0.0001). Moreover, miR-133a was substantially increased in patients with STEMI compared with TTC (P < 0.05). A unique signature comprising miR-1, miR-16, miR-26a, and miR-133a differentiated TTC from healthy subjects [area under the curve (AUC) 0.835, 95% CI 0.733–0.937, P < 0.0001] and from STEMI patients (AUC 0.881, 95% CI 0.793–0.968, P < 0.0001). This signature yielded a sensitivity of 74.19% and a specificity of 78.57% for TTC vs. healthy subjects, and a sensitivity of 96.77% and a specificity of 70.37% for TTC vs. STEMI patients. Additionally, we noticed a decrease of the endothelin-1 (ET-1)-regulating miRNA-125a-5p in parallel with a robust increase of ET-1 plasma levels in TTC compared with healthy subjects (P < 0.05). Conclusion The present study for the first time describes a signature of four circulating miRNAs as a robust biomarker to distinguish TTC from STEMI patients. The significant up-regulation of these stress- and depression-related miRNAs suggests a close connection of TTC with neuropsychiatric disorders. Moreover, decreased levels of miRNA125a-5p as well as increased plasma levels of its target ET-1 are in line with the microvascular spasm hypothesis of the TTC pathomechanism.

Diabetes-Associated MicroRNAs in Pediatric Patients With Type 1 Diabetes Mellitus: A Cross-Sectional Cohort Study

CONTEXT Circulating microRNAs (miRNAs/miRs) are used as novel biomarkers for diseases. miR-21, miR-126, and miR-210 are known to be deregulated in vivo or in vitro under diabetic conditions. OBJECTIVE The aim of this study was to investigate the circulating miR-21, miR-126, and miR-210 in plasma and urine from pediatric patients with type 1 diabetes and to link our findings to cardiovascular and diabetic nephropathy risk factors in children with type 1 diabetes. DESIGN miR-21, miR-126, and miR-210 concentrations were measured with quantitative RT-PCR in plasma and urine samples from 68 pediatric patients with type 1 diabetes and 79 sex- and age-matched controls. SETTING The study consisted of clinical pediatric patients with type 1 diabetes. PATIENTS OR OTHER PARTICIPANTS Inclusion criterion for patients was diagnosed type 1 diabetes. Exclusion criteria were febrile illness during the last 3 months; chronic inflammatory or rheumatic disease; hepatitis; HIV; glucocorticoid treatment; liver, renal, or cardiac failure; or hereditary dyslipidemia. Patients were age and sex matched to controls. MAIN OUTCOME MEASURE(S) Main outcome parameters were changes in miR-21, miR-126, and miR-210 concentration in plasma and urine from type 1 diabetic patients compared with corresponding controls. RESULTS Circulating miRNA levels of miR-21 and miR-210 were significantly up-regulated in the plasma and urine of the type 1 diabetic patients. Urinary miR-126 levels in diabetic patients were significantly lower than in age- and gender-matched controls and negatively correlated between the patients glycated hemoglobin mean and miR-126 concentration value. In contrast, circulating miR-126 levels in plasma were comparable in both cohorts. For urinary miR-21, we found by an adjusted receiver-operating characteristic-curve analysis with an area under the curve of 0.78. CONCLUSIONS Type 1 diabetic pediatric patients revealed a significant deregulation of miR-21, miR-126, and miR-210 in plasma and urinary samples, which might indicate an early onset of diabetic-associated diseases.

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.

Circulating Concentrations of Follistatin-Like 1 in Healthy Individuals and Patients with Acute Coronary Syndrome as Assessed by an Immunoluminometric Sandwich Assay

BACKGROUND Follistatin-like 1 (FSTL1) is a 308-amino acid secreted glycoprotein. Tissue levels of FSTL1 are induced in animal models and patients with chronic inflammatory and cardiovascular disease. We hypothesized that FSTL1 can be measured in the human circulation and used as a biomarker in acute coronary syndrome (ACS). METHODS We developed an immunoluminometric assay (ILMA), assessed the preanalytic characteristics of FSTL1, and determined circulating FSTL1 concentrations in 120 apparently healthy individuals and 216 patients with ACS. RESULTS The assay had a limit of detection of 0.17 microg/L, limit of quantification of 1.02 microg/L, intraassay imprecision of < or =12.7%, and interassay imprecision of < or =15.4%. Selectivity was demonstrated with size-exclusion chromatography and lack of cross-reactivity with related proteins. The assay was not appreciably influenced by unrelated biological substances. FSTL1 in serum or whole blood was stable at room temperature for 48 h and was resistant to 4 freeze-thaw cycles. Measured FSTL1 concentrations in citrated plasma and heparin-treated plasma were 18% and 17% lower, respectively, than concentrations measured in serum. Apparently healthy individuals presented with a median FSTL1 serum concentration of 7.18 (range 1.06-18.49) microg/L. Serum FSTL1 concentrations were increased in ACS and related to the risk of all-cause mortality during follow-up. CONCLUSIONS The ILMA permits detection of FSTL1 in human serum and plasma. We expect that the favorable preanalytic characteristics of FSTL1 and the reference limits defined here for apparently healthy individuals will facilitate future studies of FSTL1 as a biomarker in various disease settings, including ACS.

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.

Incremental Prognostic Value of Biomarkers beyond the GRACE (Global Registry of Acute Coronary Events) Score and High-Sensitivity Cardiac Troponin T in Non-ST-Elevation Acute Coronary Syndrome

BACKGROUND Guidelines recommend the use of validated risk scores and a high-sensitivity cardiac troponin assay for risk assessment in non-ST-elevation acute coronary syndrome (NSTE-ACS). The incremental prognostic value of biomarkers in this context is unknown. METHODS We calculated the Global Registry of Acute Coronary Events (GRACE) score and measured the circulating concentrations of high-sensitivity cardiac troponin T (hs-cTnT) and 8 selected cardiac biomarkers on admission in 1146 patients with NSTE-ACS. We used an hs-cTnT threshold at the 99th percentile of a reference population to define increased cardiac marker in the score. The magnitude of the increase in model performance when individual biomarkers were added to GRACE was assessed by the change (Δ) in the area under the receiver-operating characteristic curve (AUC), integrated discrimination improvement (IDI), and category-free net reclassification improvement [NRI(>0)]. RESULTS Seventy-eight patients reached the combined end point of 6-month all-cause mortality or nonfatal myocardial infarction. The GRACE score alone had an AUC of 0.749. All biomarkers were associated with the risk of the combined end point and offered statistically significant improvement in model performance when added to GRACE (likelihood ratio test P ≤ 0.015). Growth differentiation factor 15 [ΔAUC 0.039, IDI 0.049, NRI(>0) 0.554] and N-terminal pro-B-type natriuretic peptide [ΔAUC 0.024, IDI 0.027, NRI(>0) 0.438] emerged as the 2 most promising biomarkers. Improvements in model performance upon addition of a second biomarker were small in magnitude. CONCLUSIONS Biomarkers can add prognostic information to the GRACE score even in the current era of high-sensitivity cardiac troponin assays. The incremental information offered by individual biomarkers varies considerably, however.

Growth Differentiation Factor 15 Plasma Levels and Outcome after Ischemic Stroke

Background: Growth differentiation factor 15 (GDF-15) is a stress-responsive cytokine that is induced after experimental brain injury. We hypothesized that the circulating levels of GDF-15 are increased and associated with neurological outcome in patients with ischemic stroke. Methods: Serial blood samples were obtained between 6 h and 7 days after symptom onset in 57 consecutive patients with acute ischemic stroke (n = 51) or transient ischemic attack (n = 6). GDF-15 was measured by immunoradiometric assay. Neurological outcome using the modified Rankin Scale (mRS) at 7 and 90 days was classified as favorable (mRS 0 or 1) or unfavorable (mRS >1). Results: Six hours after symptom onset, GDF-15 levels were abnormally high (>1,200 ng/l) in 68% of the patients. They declined by 8% over the course of 7 days (p < 0.001). GDF-15 levels were correlated with the circulating levels of the inflammatory marker interleukin-6 and the glial protein S100 calcium binding protein B, and with carotid intima-media thickness. Ischemic stroke patients with an mRS score >1 at 7 or 90 days had higher circulating levels of GDF-15 at all preceding sampling time points compared to patients with an mRS score of 0 or 1 (p ≤ 0.002). Similarly, in a logistic regression analysis, GDF-15 levels measured between 6 h and 7 days after symptom onset were associated with mRS at 7 and 90 days. Conclusions: These data show for the first time that the circulating levels of GDF-15 are elevated and associated with neurological outcome in patients with ischemic stroke.

Diagnostic performance of rising, falling, or rising and falling kinetic changes of high-sensitivity cardiac troponin T in an unselected emergency department population

Background: Current ESC guidelines for the diagnosis of myocardial infarction consider a rise and/or fall of cardiac biomarkers. However, whether rising or falling patterns of high-sensitivity cardiac troponin T (hs-cTnT) improve the discrimination of ST-elevation myocardial infarction (non-STEMI) from non-acute coronary syndromes (ACS) has not been evaluated yet. Methods: We compared protocols of rising and falling absolute and relative hs-cTnT changes in an unselected emergency department population. Results: A total of 635 patients with unstable angina pectoris (UAP), non-STEMI, or acute symptoms and increased hs-cTnT (>99th percentile) were enrolled. Of these, 572 patients met the inclusion criteria of consistently rising patterns (n=254, 44.4%), consistently falling patterns (n=224, 39.2%), or falling patterns after an initial rise (n=94, 16.4%). Final diagnoses included 66 (11.5%) patients with UAP, 141 (24.7%) patients with non-STEMI, and 365 (63.8%) patients with hs-cTnT elevations not due to ACS. Rising values were found more frequently in patients with non-STEMI, as compared to non-ACS (OR 3.69, 95% CI 2.46–5.53; p<0.0001), and falling patterns were observed more frequently in patients with non-ACS conditions (OR 3.56, 95% CI 2.24–5.63; p<0.001). Addition of rising but not falling changes increased diagnostic performance of hs-cTnT concentrations at presentation: positive: AUC 0.680 (95% CI 0.618–0.742) vs. 0.861 (95% CI 0.822–0.900; p<0.0001), negative: AUC 0.678 (95% CI 0.545–0.812) vs. 0.741 (95% CI 0.635–0.847). A 20% criterion as proposed by ESC guidelines performed equally for positive and negative changes only when admission hs-cTnT values were considered: AUC 0.785 (95% CI 0.726–0.845) vs. AUC 0.763 (95% CI 0.681–0.845); p=ns. Conclusions: Detection of rising but not falling hs-cTnT values improves discrimination of non-STEMI from non-ACS in an unselected emergency department population.