Temporal changes of soluble ST2 after cardiovascular interventions

The ST2/IL-33 Pathway in Adult and Paediatric Heart Disease and Transplantation

ST2 is a member of interleukin 1 receptor family with soluble sST2 and transmembrane ST2L isoforms. The ligand of ST2 is IL-33, which determines the activation of numerous intracytoplasmic mediators following the binding with ST2L and IL-1RAcP, leading to nuclear signal and cardiovascular effect. Differently, sST2 is released in the blood and works as a decoy receptor, binding IL-33 and blocking IL-33/ST2L interaction. sST2 is mainly involved in maintaining homeostasis and/or alterations of different tissues, as counterbalance/activation of IL-33/ST2L axis is typically involved in the development of fibrosis, tissue damage, inflammation and remodeling. sST2 has been described in different clinical reports as a fundamental prognostic marker in patients with cardiovascular disease, as well as marker for the treatment monitoring of patients with heart failure; however, further studies are needed to better elucidate its role. In this review we reported the current knowledge about its role in coronary artery disease, heart failure, heart transplantation, heart valve disease, pulmonary arterial hypertension, and cardiovascular interventions.

Soluble ST2 as a Biomarker for Early Complications in Patients with Chronic Thromboembolic Pulmonary Hypertension Treated with Balloon Pulmonary Angioplasty

Background: The aim of the study was to assess soluble ST2 (sST2) concentration and its dynamic changes in the periprocedural period in patients with chronic thromboembolic pulmonary hypertension (CTEPH) treated with balloon pulmonary angioplasty (BPA). Methods: We prospectively analyzed 57 procedures of BPA performed in 37 patients with CTEPH. Biomarkers, such as N-terminal pro B-type natriuretic peptide (NT-proBNP), troponin T (TnT), and sST2 were assessed at four time points: Before the BPA procedure, 24 h and 48 h after the procedure, and at the discharge from hospital. Each postprocedural period was assessed for complications. Results: Before the BPA procedure, median sST2 concentration was 26.56 ng/mL (IQR: 16.66–40.83 ng/mL). sST2 concentration was significantly higher 24 h and 48 h after the BPA compared to the baseline measurements (33.31 ng/mL (IQR: 20.81–62.56), p = 0.000 and 27.45 ng/mL (IQR: 17.66–54.45), p = 0.028, respectively). sST2 level 24 h after the BPA procedure was significantly higher in the group with complications compared to the group without complications in the postprocedural period (97.66 ng/mL (IQR: 53.07–126.18) vs. 26.86 ng/mL (IQR: 19.10–40.12), p = 0.000). Conclusions: sST2 concentration in patients with CTEPH treated with BPA changes significantly in the postprocedural period and is significantly higher in the group with complications in postprocedural period.

An impedimetric biosensor system based on disposable graphite paper electrodes: Detection of ST2 as a potential biomarker for cardiovascular disease in human serum

In present study, we developed a highly sensitive, electrochemical immunosensor based on fullerene C₆₀-modified disposable graphite paper (GP) electrode for determination of Suppression of Tumorigenicity 2 (ST2) in human serum. The synthesis of the ST2 immunosensor was monitored with electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) techniques and single frequency impedance (SFI) technique which is utilized for the specific interaction between anti-ST2 and ST2 antigen. Moreover, the morphological alteration of each GP surface was examined by scanning electron microscopy (SEM), SEM-energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). All parameters such as fullerene C₆₀ concentration, antibody concentration and antibody incubation time were optimized. Analytical characteristics such as linear determination range, repeatability, reproducibility, regeneration and surface coverage were determined for the immunosensor. The ST2 electrochemical immunosensor had excellent repeatability, reproducibility and a wide detection range (from 0.1 fg mL^-1 to 100 fg mL^-1). The proposed immunosensor also had low limit of detection (LOD) and limit of quantification (LOQ) values of 0.124 fg mL^-1 and 0.414 fg mL^-1, respectively. The proposed immunosensor was applied to real samples to test applicability in clinical practice.

Galectin-3, GDF-15, and sST2 for the assessment of disease severity and therapy response in patients suffering from inoperable chronic thromboembolic pulmonary hypertension

PURPOSE

This study examined sST2, GDF-15, and galectin-3 as indicators of disease severity and therapy response in chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

This study included 57 inoperable CTEPH patients who underwent balloon pulmonary angioplasty and 25 controls without cardiovascular disease. Biomarker levels were examined in relation to advanced hemodynamic impairment [tertile with worst right atrial pressure (RAP) and cardiac index], hemodynamic therapy response [normalized hemodynamics (meanPAP ≤25 mmHg, PVR ≤3 WU and RAP ≤6 mmHg) or a reduction of meanPAP ≥25%; PVR ≥ 35%, RAP ≥25%].

RESULTS

GDF-15 [820 (556-1315) pg/ml vs. 370 (314-516) pg/ml; p < 0.001] and sST2 [53.7 (45.3-74.1) ng/ml vs. 48.7 (35.5-57.0) ng/ml; p = 0.02] were higher in CTEPH patients than in controls. At baseline, a GDF-15 level ≥1443 pg/ml (AUC 0.88; OR 31.4) and a sST2 level ≥65 ng/ml (AUC 0.80; OR 10.9) were associated with advanced hemodynamic impairment. At follow-up GDF-15 ≤ 958 pg/ml (AUC = 0.74, OR 18) identified patients with optimal hemodynamic therapy response and ≤760 pg/ml (AUC = 0.79, OR 14).

CONCLUSION

GDF-15 and sST2 levels are higher in CTEPH and identified patients with advanced hemodynamic impairment. Further, decreased GDF-15 levels at follow-up were associated with hemodynamic therapy response. The diagnostic strength was not superior to NT-proBNP.

sST2 as a novel biomarker for the prediction of in-hospital mortality after coronary artery bypass grafting

Objectives: Soluble suppression of tumorigenicity 2 (sST2) biomarker is an emerging predictor of adverse clinical outcomes, but its prognostic value for in-hospital mortality after coronary artery bypass grafting (CABG) is not well understood. This study measured the association between operative sST2 levels and in-hospital mortality after CABG. Methods: A prospective cohort of 1560 CABG patients were analyzed from the Northern New England Cardiovascular Disease Study Group Biomarker Study. The primary outcome was in-hospital mortality after CABG surgery (n = 32). Results: After risk adjustment, patients in the third tercile of pre-, post- and pre-to-postoperative sST2 values experienced significantly greater odds of in-hospital death compared to patients in the first tercile of sST2 values. The addition of both postoperative and pre-to-postoperative sST2 biomarker significantly improved ability to predict in-hospital mortality status following CABG surgery, compared to using the EuroSCORE II mortality model alone, (c-statistic: 0.83 [95% CI: 0.75, 0.92], p value 0.0213) and (c-statistic: 0.83 [95% CI: 0.75, 0.92], p value 0.0215), respectively. Conclusion: sST2 values are associated with in-hospital mortality after CABG surgery and postoperative and pre-to-post operative sST2 values improve prediction. Our findings suggest that sST2 can be used as a biomarker to identify adult patients at greatest risk of in-hospital death after CABG surgery.

Different ST2 Serum Concentrations in Asymptomatic and Symptomatic Carotid Artery Stenosis

BACKGROUND

ST2 represents an interesting biomarker associated with the progression of atherosclerotic disease.

METHODS

This study aims to detect different ST2 serum concentrations, and intraplaque ST2 expression, in patients with symptomatic and asymptomatic carotid artery stenosis.

RESULTS

The analysis of ST2 expression in the atheromatous plaque did not show any significant difference between symptomatic and asymptomatic patients (39.61 ± 35.97 vs. 38.49 ± 35.26; P = ns). ST2 serum concentrations of asymptomatic and symptomatic patients were statistically different with a concentration of 11.04 ± 8.95 ng/mL and 13.91 ± 8.01 ng/mL, respectively (P = 0.037). We observed statistical difference in serum ST2 levels between asymptomatic and symptomatic patients for cerebrovascular acute disease. No differences have been obtained in intraplaque ST2 expression.

CONCLUSIONS

Soluble serum ST2 levels can be a useful biomarker to identify patients at risk for cerebrovascular events.

Predictive Ability of Novel Cardiac Biomarkers ST2, Galectin-3, and NT-ProBNP Before Cardiac Surgery

BACKGROUND

Current preoperative models use clinical risk factors alone in estimating risk of in-hospital mortality following cardiac surgery. However, novel biomarkers now exist to potentially improve preoperative prediction models. An assessment of Galectin-3, N-terminal pro b-type natriuretic peptide (NT-ProBNP), and soluble ST2 to improve the predictive ability of an existing prediction model of in-hospital mortality may improve our capacity to risk-stratify patients before surgery.

METHODS AND RESULTS

We measured preoperative biomarkers in the NNECDSG (Northern New England Cardiovascular Disease Study Group), a prospective cohort of 1554 patients undergoing coronary artery bypass graft surgery. Exposures of interest were preoperative levels of galectin-3, NT-ProBNP, and ST2. In-hospital mortality and adverse events occurring after coronary artery bypass graft were the outcomes. After adjustment, NT-ProBNP and ST2 showed a statistically significant association with both their median and third tercile categories with NT-ProBNP odds ratios of 2.89 (95% confidence interval [CI]: 1.04-8.05) and 5.43 (95% CI: 1.21-24.44) and ST2 odds ratios of 3.96 (95% CI: 1.60-9.82) and 3.21 (95% CI: 1.17-8.80), respectively. The model receiver operating characteristic score of the base prediction model (0.80 [95% CI: 0.72-0.89]) varied significantly from the new multi-marker model (0.85 [95% CI: 0.79-0.91]). Compared with the Northern New England (NNE) model alone, the full prediction model with biomarkers NT-proBNP and ST2 shows significant improvement in model classification of in-hospital mortality.

CONCLUSIONS

This study demonstrates a significant improvement of preoperative prediction of in-hospital mortality in patients undergoing coronary artery bypass graft and suggests that biomarkers can be used to identify patients at higher risk.

Undiagnosed airflow limitation is common in patients with coronary artery disease and associated with cardiac stress

BACKGROUND AND OBJECTIVE

Smoking is a common risk factor for coronary artery disease (CAD) and chronic obstructive pulmonary disease (COPD). We evaluated the prevalence of undiagnosed COPD in patients with CAD and assessed the relationship between airflow obstruction and markers of cardiac stress.

METHODS

We recruited prospectively consecutive patients aged >40 years without known history of chronic lung disease (e.g. asthma, COPD, bronchiectasis) who had undergone percutaneous coronary intervention (PCI) for obstructive CAD between August 2009 and October 2010. Spirometry was performed and serum ST2, a novel biomarker of cardiomyocyte stress and fibrosis, was measured by enzyme-linked immunosorbent assay.

RESULTS

Among 475 subjects (mean age 64 ± 9.7, range 42-85 years, 87.2% males, 58.5% current or ex-smokers) who underwent spirometry, 51 (10.7%) had undiagnosed airflow obstruction with FEV1 /FVC ratio <70%. Of these 51 subjects, 14 (2.9%), 23 (4.8%) and 14 (2.9%) had FEV1 ≥80, 50-80 and 30-50% predicted normal, respectively. ST2 level was measured in all the subjects with undiagnosed airflow obstruction and in 290 subjects with normal lung function. There was no significant difference in left ventricular ejection fraction on echocardiogram between subjects with and without airflow obstruction. Patients with severe airflow obstruction had a higher level of cardiac stress marker ST2 than those with mild and moderate airflow obstruction (rho = -0.214, P ≤ 0.001).

CONCLUSION

Undiagnosed airflow obstruction is common among patients with CAD who have undergone PCI. Severity of airflow limitation is associated with increasing cardiac stress.

Soluble ST2--analytical considerations

Suppression of tumorigenicity 2 (ST2, also known as interleukin [IL]-1 receptor-like-1) is an IL-1 receptor family member with transmembrane (ST2L) and soluble isoforms (sST2). ST2L is a membrane-bound receptor, and IL-33 is the functional ligand for ST2L. sST2, a soluble truncated form of ST2L, is secreted into the circulation and functions as a "decoy" receptor for IL-33, inhibiting IL-33/ST2L signaling. Blood concentrations of sST2 are increased in inflammatory diseases and heart disease and are considered a valuable prognostic marker in both conditions. In multiple clinical trials, sST2 has emerged as a clinically useful prognostic biomarker in patients with cardiac diseases. Interestingly, sST2 even provides prognostic information in low-risk community-based populations. In this review, we will discuss analytical considerations of measuring circulating sST2 including pre-analytical issues, such as in vitro stability of sST2, biological variation of sST2, and postanalytical issues, such as reference ranges and comparisons to diseased cohorts.

Soluble ST2 in heart failure

In addition to routine clinical laboratory tests (including natriuretic peptides and cardiac troponins), other biomarkers are gaining attention for their utility in heart failure (HF) management. Among them, soluble ST2 (sST2) a novel biomarker integrating inflammation, fibrosis, and cardiac stress has been included in the 2013 ACCF/AHA guideline for additive risk stratification of patients with acute and chronic HF. sST2 is an interleukin-1 (IL-1) receptor family member, is secreted into the circulation and functions as a "decoy" receptor for IL-33, inhibiting IL-33/ST2 signaling. Blood concentrations of sST2 are increased in various diseases such as inflammatory diseases and heart diseases and are considered a valuable prognostic marker in both conditions. sST2 lacks disease specificity and, therefore, is not a valuable marker for the diagnosis of HF. In acute and chronic HF, however, sST2 is strongly associated with measures of HF severity and poor outcome. Several studies in patients with HF indicate that serial measurement of sST2 has prognostic value and could have a potential role in future biomarker-directed therapy. In this review, the role of sST2 as a HF biomarker will be discussed, specifically addressing analytical considerations of measuring sST2 as well as the clinical applications of measurement of sST2 for the diagnosis, prognosis and monitoring of acute and chronic HF.

Soluble ST2 and N-terminal pro-brain natriuretic peptide combination. Useful biomarker for predicting outcome of childhoodpulmonary arterial hypertension

BACKGROUND

Some potential biomarkers have been reported recently in patients with pulmonary arterial hypertension (PAH), but the most clinically useful among these potential biomarkers, especially in childhood PAH, has not been identified. Therefore, this study investigated which biomarker is useful in assessing severity of and patient prognosis in childhood idiopathic PAH (IPAH)/heritable PAH (HPAH).

METHODS AND RESULTS

Fifty-nine patients who were younger than 16 years at onset of IPAH/HPAH were selected. The following 10 biomarker candidates were quantified: high-sensitivity troponin T, human heart fatty acid-binding protein, N-terminal pro-brain natriuretic peptide (NT-proBNP), pentraxin-3, soluble ST2 (sST2), angiopoietin-2 (Ang-2), matrix metalloproteinase 2, tenascin C, endostatin (ES), and thymidine kinase. Functional characteristics and clinical outcomes were analyzed retrospectively. NT-proBNP, sST2, Ang-2, and ES correlated well with New York Heart Association class. On area under the receiver operating characteristic curve analysis, sST2 had a significantly good relationship with prognosis. On Kaplan-Meier curve and univariate Cox regression analyses, elevated sST2 and NT-proBNP level predicted poor outcome of the present patients with childhood IPAH/HPAH. Furthermore, patients with elevated sST2 had significantly worse prognosis among those with high NT-proBNP.

CONCLUSIONS

The sST2 and NT-proBNP combination is a useful biomarker to predict clinical condition and outcome in patients with childhood IPAH/HPAH.  

Soluble ST2 levels are not associated with secondary cardiovascular events and vulnerable plaque phenotype in patients with carotid artery stenosis

OBJECTIVE

Soluble ST2 (sST2), a novel biomarker predictive for heart disease, has recently been shown associated with the progression of atherosclerotic disease in a mouse model. The present study was designed to assess sST2 plasma levels in patients scheduled for carotid endarterectomy and relate it with the occurrence of adverse cardiovascular events during follow-up. In addition, sST2 levels were associated to patient clinical data and atherosclerotic plaque characteristics.

METHODS AND RESULTS

Plasma sST2 levels were measured in 391 patients who underwent carotid endarterectomy and were subsequently followed for 3 years. Primary composite endpoint was the occurrence of an adverse cardiovascular event. At baseline, no differences were observed in sST2 levels between asymptomatic (n = 75) and symptomatic (n = 316) patients (85 [49-122] versus 90 [58-137] pg/ml, p = 0.263). Soluble ST2 plasma levels did not differ between patients who experienced a secondary manifestation of cardiovascular disease and patients who remained free of symptoms (90 [60-129] versus 88 [46-140] pg/ml, p = 0.519). There was no association between sST2 levels and any of the following plaque characteristics: size of a lipid core, degree of calcification, number of macrophages or smooth muscle cells, amount of collagen and number of microvessels.

CONCLUSIONS

Soluble ST2 plasma levels have no predictive value for future cardiovascular events in patients with significant carotid artery stenosis. In addition, we did not observe an association between plasma sST2 levels and the histopathological features of a rupture prone plaque. This study does not provide supportive evidence that sST2 reflects a progressive state of advanced atherosclerotic disease.