The Presage(®) ST2 Assay: analytical considerations and clinical applications for a high-sensitivity assay for measurement of soluble ST2

Fluorescence Aptasensor for sST2 Detection Using In Vitro Selected Aptamers

Soluble suppression of tumorigenicity 2 (sST2) is a critical biomarker for heart failure (HF) diagnosis and prognosis, yet conventional antibody-based detection methods suffer from time-consuming protocols and high costs and involve complex detection procedures. To address these challenges, we first screened high-affinity aptamers under clinically relevant conditions and then coupled with the CRISPR/Cas12a system to develop a fluorescence aptasensor for rapid and sensitive sST2 detection. A serum matrix was introduced during aptamer selection to enhance specificity and anti-interference performance in real biological environments. Three sST2-specific aptamers (Apt-1, Apt-2, and Apt-3) were identified with dissociation constants (KD) of 8.42, 46.08, and 25.02 nM, respectively. Among these, Apt-1 demonstrated superior performance, which was utilized to construct a fluorescence biosensor combining aptamer recognition with CRISPR/Cas12a trans-cleavage signal amplification. The sensor achieved a broad linear detection range (5-120 ng/mL) and an ultralow limit of detection (LOD, 0.816 ng/mL) when applied in detecting sST2 in both the buffer and human serum. Notably, the platform exhibited exceptional resistance to interference from HF-related proteins and maintained high accuracy in clinical serum samples, showing a strong correlation (R2 = 0.9794) with enzyme-linked immunosorbent assay (ELISA) results. By integration of serum-matrix screening and CRISPR-based signal enhancement, this work establishes a robust, cost-effective, and rapid diagnostic tool for sST2 detection.

Association of fibrotic markers with diastolic function after STEMI

Galectin-3 and Suppression of tumorigenicity-2 (ST2) are known markers of cardiac fibrosis. We investigated the prognostic value of fibrotic markers for the development of diastolic dysfunction and long-term outcome in patients suffering an ST-elevated myocardial infarction (STEMI). We analyzed 236 patients from the GIPS-III cohort with available echocardiographic studies and plasma measurements at hospitalization and after 4 months follow-up. Adjusted logistic mixed effects modelling revealed no association between the occurrence of diastolic dysfunction over time with abnormal plasma levels of galectin-3 and ST2. We observed no differences regarding survival outcome at follow-up of 5 years between patients with normal versus abnormal values in both galectin-3 (P = 0.75), and ST2 (P = 0.85). In conclusion, galectin-3 and sST2 were not associated with the development of diastolic dysfunction in non-diabetic patients that presented with a STEMI.

Soluble ST2: A Novel Biomarker for Diagnosis and Prognosis of Cardiovascular Disease

The increasing incidence of cardiovascular disease (CVD) is a significant global health concern, affecting millions of individuals each year. Accurate diagnosis of acute CVD poses a formidable challenge, as misdiagnosis can significantly decrease patient survival rates. Traditional biomarkers have played a vital role in the diagnosis and prognosis of CVDs, but they can be influenced by various factors, such as age, sex, and renal function. Soluble ST2 (sST2) is a novel biomarker that is closely associated with different CVDs. Its low reference change value makes it suitable for continuous measurement, unaffected by age, kidney function, and other confounding factors, facilitating risk stratification of CVDs. Furthermore, the combination of sST2 with other biomarkers can enhance diagnostic accuracy and prognostic value. This review aims to provide a comprehensive overview of sST2, focusing on its diagnostic and prognostic value as a myocardial marker for different types of CVDs and discussing the current limitations of sST2.

Soluble ST2 predicts continuous renal replacement therapy in patients receiving venoarterial extracorporeal membrane oxygenation

OBJECTIVE

This study aimed to evaluate the relationship between plasma soluble ST2 (sST2) levels 24 h after extracorporeal membrane oxygenation (ECMO) initiation and continuous renal replacement therapy (CRRT) in patients receiving venoarterial ECMO (V-A ECMO) support.

METHODS AND RESULTS

Data of patients who received ECMO support for postcardiotomy cardiogenic shock between January 2017 and July 2019 were retrospectively collected from Beijing Anzhen Hospital, Capital Medical University. Ultimately, 116 patients were included in the present study for analysis. The concentration of sST2 was determined by enzyme-linked immunosorbent assay (ELISA). The log10 sST2 levels were higher in patients undergoing CRRT than those who did not (6.06 vs. 6.22, p = 0.019). Patients undergoing CRRT had a lower survival rate than those who did not (32.8% vs. 67.3%, p < 0.001). In the univariate logistic regression analysis, sST2, HCO3-, lactate, and creatinine levels 24 h after ECMO initiation were related to CRRT (p < 0.05). In the multivariate logistic regression analysis, HCO3- and sST2 were identified as independent risk factors for CRRT use in patients undergoing ECMO (p < 0.05). The area under receiver operator characteristic curve (AUC) for sST2 and HCO3- together was 0.72 (95% confidence interval (CI), 0.79-0.91), which was better than those of sST2 or HCO3- alone (0.63 vs. 0.67).

CONCLUSIONS

sST2 and HCO3-levels at 24 h after ECMO initiation were associated with CRRT and could predict CRRT use in postcardiotomy cardiogenic shock patients undergoing ECMO.

Highly sensitive and specific graphene oxide-based FRET aptasensor for quantitative detection of human soluble growth stimulating gene protein 2

Soluble growth stimulation expressed gene 2 (sST2) is a new generation biomarker in the diagnosis and prognosis of heart failure (HF). Here, the sST2-specific aptamers were selected from a random ssDNA library with the full length of 88 nucleotides (nt) via target-immobilized magnetic beads (MB)-based systematic evolution of ligands by exponential enrichment (SELEX) technology. After eight rounds of selection, six aptamers with the most enrichment were selected. Among, the aptamer L1 showed the high-affinity binding to sST2 with the lowest Kd value (77.3 ± 0.05 nM), which was chosen as the optimal aptamer for further molecular docking. Then, the aptamer L1 was used to construct a graphene oxide (GO) - based fluorescence resonance energy transfer (FRET) biosensor for sST2, which exhibits a linear detection range of 0.1-100 μg/ml and a detection limit of 3.7 ng/ml. The aptasensor was applied to detect sST2 in real samples, with a good correlation and agreement with the traditional enzyme-linked immunosorbent assay (ELISA) when quantitative analyzing the sST2 concentration in serum samples from HF patients. The results show that not only an efficient strategy for screening the practicable aptamer, but also a rapid and sensitive detection platform for sST2 were established.

Association of soluble ST2 Level with 6-month Mortality and/or Recurrent Cardiovascular-Related Hospitalization in Pulmonary Embolism

BACKGROUND

The association of soluble suppression of tumorigenesis-2 (sST2) levels with prognosis in pulmonary embolism (PE) is unknown.

OBJECTIVE

This study aimed to investigate the relationship between sST2 levels in patients with acute PE and 6-month mortality and recurrent hospitalizations.

METHODS

This prospective study included 100 patients with acute PE. Patients were classified into two groups according to 6-month mortality and the presence of recurrent Cardiovascular-Related hospitalizations. Two groups were compared. A p-value of 0.05 was considered statistically significant.

RESULTS

Soluble ST2 levels were significantly higher in the group with mortality and recurrent hospitalizations. (138.6 ng/mL (56.7-236.8) vs. 38 ng/mL (26.3-75.4); p<0.001) The best cut-off threshold for sST2 levels in the prediction of a composite outcome of 6-month mortality and/or recurrent Cardiovascular-Related hospitalization was found to be >89.9 with a specificity of 90.6% and a sensitivity of 65.2%, according to the receiver operating characteristic curve (area under the curve = 0.798; 95% CI, 0.705-0.891; p <0.0001). After adjusting for confounding factors that were either statistically significant in the univariate analysis or for the variables correlated with the sST2 levels, sST2 level (OR = 1.019, 95% CI: 1.009-1.028, p 0.001) and C-reactive protein (CRP ) (OR = 1.010, 95% CI: 1.001-1.021, p = 0.046) continued to be significant predictors of 6-month mortality and/or recurrent Cardiovascular-Related hospitalization in the multiple logistic regression model via backward stepwise method.

CONCLUSION

Soluble ST2 level seems to be a biomarker to predict 6-month mortality and/or recurrent Cardiovascular-Related hospitalization in patients with acute PE.

Evaluation of soluble suppression of tumorigenicity 2 (sST2) as serum marker for liver fibrosis

BACKGROUND & AIMS

With the increase in patients at risk of advanced liver disease due to the obesity epidemic, there will be a need for simple screening tools for advanced liver fibrosis. Soluble suppression of tumorigenicity 2 (sST2) is a serum biomarker for fibrotic processes. The aim of this study was to evaluate sST2 as marker for liver fibrosis in patients successfully treated for chronic hepatitis C.

METHODS

424 patients from the Swiss Hepatitis C Cohort Study were screened for inclusion in this post-hoc cohort study. Inclusion criteria were sustained virological response (SVR), available elastography (VCTE) and serum samples for biomarker analysis before and after treatment. For the validation of sST2, values were compared to VCTE, FIB-4 and APRI using Spearman's correlation and AUROC analyses.

RESULTS

Data of 164 subjects were finally analyzed. Median sST2 values slightly increased with VCTE-derived fibrosis stages and remained stable after reaching SVR within the respective fibrosis stage, suggesting that sST2 is not influenced by liver inflammation. However, correlation of sST2 pre- and post-treatment with VCTE was fair (Spearman's rho = 0.39 and rho = 0.36). The area under the curve (AUROC) for sST2 in detecting VCTE-defined F4 fibrosis (vs. F0-F3) before therapy was 0.74 (95%CI 0.65-0.83), and 0.67(95%CI 0.56-0.78) for the discrimination of F3/F4 fibrosis vs. F0-F2. Adding sST2 to either APRI or FIB-4, respectively, increased diagnostic performance of both tests.

CONCLUSIONS

sST2 can potentially identify patients with advanced fibrosis as a single serum marker and in combination with APRI and FIB-4.

Plasma soluble suppression of tumorigenesis 2 measured in the emergency department for diagnosis and outcome prediction of sepsis: A single-center prospective study

BACKGROUND AND AIMS

The diagnostic and prognostic performance of soluble Suppression of Tumorigenicity 2 (sST2) in suspected septic patients presenting to the Emergency Department (ED) is largely unknown.

MATERIALS AND METHODS

Patients were included in this prospective study if there was high suspicion of sepsis. The plasma level of sST2 was measured during initial ED evaluation. Outcomes were the evaluation of (1) sST2 diagnostic performance (alone and in combination with procalcitonin [PCT]), and (2) sST2 ability to predict 30-day and 90-day all-cause mortality.

RESULTS

Among 569 patients included, 481 (84.5 %) had sepsis or septic shock. Plasma sST2 levels were more elevated in septic patients (159 [71-331] vs 50 [31-103] ng/mL, P < 0.001). The AUC of sST2 for sepsis diagnosis was lower than the AUC of PCT (0.76 vs 0.85, P = 0.03). The best cut-off for sST2 was 61.7 ng/mL, with a sensitivity of 79.9 % and a specificity of 70.6 %. sST2 was able to correctly reclassify septic patients with PCT <0.5 (NRI 28.9 % [P = 0.02]). sST2 level was an independent predictor of 30-day mortality in a model including clinical variables (aHR 2.03 [1.24-3.33], C-index 0.69).

CONCLUSION

sST2 could be a useful adjunct in diagnosing sepsis and in all-cause mortality prediction.

A DNA aptamer-based assay for the detection of soluble ST2, a prognostic biomarker for monitoring heart failure

Heart failure (HF) is emerging as a leading cause of death worldwide. Estimation of BNP levels is a routine diagnosis in these patients. However, in patients having high body-mass index (BMI), renal disease or in geriatric patients, BNP level is reported to be noisy and leads to incongruous conclusion. Thus, for better risk stratification among heart failure patients, it is imperative to look for a superior biomarker. In recent times, sST2 has shown promise as a biomarker. Identifying such biomarkers in peripheral blood of HF patients, need an affine and selective molecular recognition element. Thus, in the current study an aptamer (sS9_P) against sST2 was identified from an aptamer library. Systematic Evolution of Ligands through Exponential enrichment (SELEX) derived aptamer evinced role of its primer binding domains in maintaining its selectivity. This aptamer candidate demonstrated dissociation constant (Kd) in low nanomolar range, and the Limit of Detection (LOD) was ~4 ng. Circular dichroism confirms the formation of complex stem-loop like structure. The well characterized sS9_P aptamer was used in an Aptamer Linked Immobilized Sorbent Assay (ALISA) to detect sST2 level in patients' serum (n = 99). Aptamer sS9_P has shown significant discrimination to differentiate HF patients and healthy volunteers with a reasonable specificity (~83 %) with a modest sensitivity of ~64 %. While sST-2 antibody has shown poor specificity of ~44% but good sensitivity (~87%). The insight obtained from this study indicates that a combination of aptamer and antibody-based assay can be used to design a point-of-care assay for the rapid detection of HF patients in emergency settings.

A biomarker for bacteremia in pregnant women with acute pyelonephritis: soluble suppressor of tumorigenicity 2 or sST2

Objective: Sepsis is a leading cause of maternal death, and its diagnosis during the golden hour is critical to improve survival. Acute pyelonephritis in pregnancy is a risk factor for obstetrical and medical complications, and it is a major cause of sepsis, as bacteremia complicates 15-20% of pyelonephritis episodes in pregnancy. The diagnosis of bacteremia currently relies on blood cultures, whereas a rapid test could allow timely management and improved outcomes. Soluble suppression of tumorigenicity 2 (sST2) was previously proposed as a biomarker for sepsis in non-pregnant adults and children. This study was designed to determine whether maternal plasma concentrations of sST2 in pregnant patients with pyelonephritis can help to identify those at risk for bacteremia.Study design: This cross-sectional study included women with normal pregnancy (n = 131) and pregnant women with acute pyelonephritis (n = 36). Acute pyelonephritis was diagnosed based on a combination of clinical findings and a positive urine culture. Patients were further classified according to the results of blood cultures into those with and without bacteremia. Plasma concentrations of sST2 were determined by a sensitive immunoassay. Non-parametric statistics were used for analysis.Results: The maternal plasma sST2 concentration increased with gestational age in normal pregnancies. Pregnant patients with acute pyelonephritis had a higher median (interquartile range) plasma sST2 concentration than those with a normal pregnancy [85 (47-239) ng/mL vs. 31 (14-52) ng/mL, p < .001]. Among patients with pyelonephritis, those with a positive blood culture had a median plasma concentration of sST2 higher than that of patients with a negative blood culture [258 (IQR: 75-305) ng/mL vs. 83 (IQR: 46-153) ng/mL; p = .03]. An elevated plasma concentration of sST2 ≥ 215 ng/mL had a sensitivity of 73% and a specificity of 95% (area under the receiver operating characteristic curve, 0.74; p = .003) with a positive likelihood ratio of 13.8 and a negative likelihood ratio of 0.3 for the identification of patients who had a positive blood culture.Conclusion: sST2 is a candidate biomarker to identify bacteremia in pregnant women with pyelonephritis. Rapid identification of these patients may optimize patient care.

Analytical performances of a new rapid assay of soluble ST2 for cardiac and inflammatory diseases and establishment of the reference intervals for children and adolescence in China

Background

sST2 has emerged as a potential disease biomarker of cardiac and inflammatory diseases in pediatrics. This study aimed to evaluate the performance of the new Pylon sST2 assay and establish the reference intervals of sST2 in children and adolescence in China.

Methods

The experiments on precision, linearity, effects of interferents and sample stability were carried out to evaluate the analytical performances. A total of 240 healthy participants, aged from 2 to 17 years were enrolled. The nonparametric method was used to calculate the age- and sex-specified reference intervals. sST2 levels were measured in children with different diseases to evaluate the assay's diagnostic performance.

Results

The repeatability and within-laboratory imprecision CVs of the assay were 6.0% and 7.6% at 19.5 ng/ml, and 3.1% and 5.9% at 289.8 ng/ml, respectively. The method showed linearity between 2.5 and 918.5 ng/ml. It was also noteworthy that the sST2 level was not affected in the presence of hemoglobin (2 mg/ml), triglyceride (30 mg/ml), bilirubin (0.3 mg/ml) and cholesterol (5 mg/ml). sST2 was found stable for 5 days at 4 °C in serum sample. The reference interval was determined as 2.1-21.0 ng/ml in general. No significant variation was observed by sex. However, sST2 increased constantly with age, especially in male. Increased sST2 was found in patients of systemic lupus erythematosus, sepsis, Crohn's diseases, respiratory failure and post cardiac surgery.

Conclusions

The Pylon sST2 assay showed good analytical performances. The reference intervals were established in children and adolescence and sST2 showed potential clinical values in several diseases in pediatrics.

Relationship Between Soluble ST2 Level and Chronic Thromboembolic Pulmonary Hypertension (CTEPH) in Acute Pulmonary Embolism (PE) Patients

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) is a disease characterized by right heart failure following recurrent pulmonary embolism (PE). It is important to know the predictors of the development of CTEPH after PE as it is a treatable cause of pulmonary arterial hypertension. Soluble ST2 is a biomarker closely associated with heart failure and the inflammatory process. The aim of this study was to investigate the relationship between sST2 level and the development of CTEPH in patients with PE.

METHODOLOGY

Baseline characteristics, electrocardiographic findings, laboratory findings, transthoracic echocardiography (TTE) findings, location, and extent of involvement in CT pulmonary angiography were recorded in 100 patients with acute PE included in our prospective study. Treatment modalities and treatment durations were followed. Ventilation-perfusion scintigraphy was performed in patients with a systolic pulmonary artery pressure (sPAP) of 35 mmHg or more on TTE and residual thrombus on CT pulmonary angiography after at least three months of anticoagulant use. In the case of findings compatible with CTEPH in these examinations, patients were diagnosed with CTEPH by right heart catheterization. The sST2 levels obtained from all patients at admission were evaluated between the groups of patients with and without CTEPH.

RESULTS

CTEPH was observed in 11 of the 100 patients who participated in the trial, with a median follow-up of 284 ± 60 days. The mean age of the 11 patients with CTEPH was 67 ± 10 years; five were males and six were females. The mean age of 89 patients without CTEPH was 65 ± 18 years, 36 were males and 53 were females. The sST2 values of the group with CTEPH were found to be statistically significantly higher than those of patients without CTEPH [193.7 (184.3-244.7) vs 58.6 (29.5-122.9) p=0.020]. This receiver operating characteristic (ROC) curve shows that the optimal cutoff point of sST2 levels in the prediction of CTEPH was > 157.4 with specificity of 83.7% and sensitivity of 81.8% (area under the curve = 0.783; 95% CI, 1.005-1.027; p < 0.001).

CONCLUSION

In acute PE patients, sST2 levels may be a useful biomarker to predict the development of CTEPH.

Biomarker sST2 in Adults with Transposition of the Great Arteries Palliated by Mustard Procedure: A Five-Year Follow-up

The Mustard procedure was an early cardiac surgery for transposition of the great arteries (TGA). Despite being successful, it has been associated with long-term arrhythmias and heart failure. A key factor complicating management in adults with congenital heart disease (CHD) is the deficiency of biomarkers predicting outcome. Soluble suppression of tumorogenicity-2 (sST2) is secreted by cardiomyocytes in response to mechanical strain and fibrosis. We hypothesized that adults with a Mustard procedure would have higher levels of sST2 than healthy individuals, and this would correlate with clinical outcome. We performed a single-center study in patients managed during childhood with a Mustard procedure versus age-matched controls. Clinical and demographic data were collected and biomarkers (sST2, cTnI, BNP, lipid panel, insulin, and glucose) were obtained. There were 18 patients (12 male) in the Mustard cohort and 18 patients (6 male) in the control group (22-49 years, mean of 35.8 vs. mean 32.6 years, respectively, p = ns). Nine Mustard subjects were NYHA class II, and 9 subjects were class III. The control group was asymptomatic. sST2 in the Mustard group was elevated in 56% vs. 17% in controls (p = 0.035). Of the Mustard subjects with elevated sST2, 60% had elevated cTnI and BNP, and 90% had low HDL. Over five years, the Mustard patients with elevated sST2 values had greater medication use, arrhythmias, hospitalizations, and ablation/pacer implantations than Mustard subjects with normal sST2. Mustard subjects with elevated sST2 had other biomarker abnormalities and clinically worse outcomes. Thus, sST2 may add a predictive value to cardiac-related morbidity and mortality.

Inflammageing and Cardiovascular System: Focus on Cardiokines and Cardiac-Specific Biomarkers

The term "inflammageing" was introduced in 2000, with the aim of describing the chronic inflammatory state typical of elderly individuals, which is characterized by a combination of elevated levels of inflammatory biomarkers, a high burden of comorbidities, an elevated risk of disability, frailty, and premature death. Inflammageing is a hallmark of various cardiovascular diseases, including atherosclerosis, hypertension, and rapid progression to heart failure. The great experimental and clinical evidence accumulated in recent years has clearly demonstrated that early detection and counteraction of inflammageing is a promising strategy not only to prevent cardiovascular disease, but also to slow down the progressive decline of health that occurs with ageing. It is conceivable that beneficial effects of counteracting inflammageing should be most effective if implemented in the early stages, when the compensatory capacity of the organism is not completely exhausted. Early interventions and treatments require early diagnosis using reliable and cost-effective biomarkers. Indeed, recent clinical studies have demonstrated that cardiac-specific biomarkers (i.e., cardiac natriuretic peptides and cardiac troponins) are able to identify, even in the general population, the individuals at highest risk of progression to heart failure. However, further clinical studies are needed to better understand the usefulness and cost/benefit ratio of cardiac-specific biomarkers as potential targets in preventive and therapeutic strategies for early detection and counteraction of inflammageing mechanisms and in this way slowing the progressive decline of health that occurs with ageing.

Growth stimulation expressed gene 2 (ST2): Clinical research and application in the cardiovascular related diseases

As an interleukin (IL)-1 receptor family member, scientists found that when circulating soluble growth stimulation expressed gene 2 (sST2) is low, its ligand, IL-33, will bind to ST2L to exert protective effects on various types of cells. On the other hand, competitive binding of IL-33 occurs when sST2 concentrations are increased, followed by a reduction in the amount available for cell protection. Based on this mechanism, the usage of sST2 is to identify the population of high-risk patients with cardiovascular disease. In recent years, the role of serum sST2 in the occurrence, diagnosis, prognosis, and treatment of cardiovascular diseases has been gradually accepted by doctors. This manuscript systemically reviews the biological functions and applications of sST2 in disease diagnosis and treatment, especially for cardiovascular diseases. In clinical testing, since IL-33 can negatively impact sST2 measurement accuracy, the properties of current assay kits have been summarized and discussed to provide a clear view of the clinical chemistry results. Although sST2 is a promising biomarker, there are few quantitative approaches available for clinical testing. In this context, a mass spectrometry (MS)-based approach might be an option, as this is a powerful analytical tool to distinguish structurally related molecules in the matrix and decrease false-positive results in clinical testing. Moreover, approaches developed based on MS would be an ideal way to further study sST2 standardization.

Soluble Isoform of Suppression of Tumorigenicity 2 (ST2) Biomarker in a Large Cohort of Healthy Pediatric Population: Determination of Reference Intervals

Introduction: Only little data exists on ST2 reference intervals in healthy pediatric populations despite the high importance of this biomarker in adults with heart failure. The aim of the study was to assess the reference intervals of ST2 in a wide healthy pediatric cohort. Methods: We evaluated the serum concentrations of ST2 biomarker in 415 healthy pediatric subjects referred to our analysis laboratory. Subjects were categorized according to age (i.e., 0−6 (n = 79), 7−11 (n = 142) and 12−18 years (n = 191)) and sex. They were not suffering from any cardiac disorders, metabolic disorders, lung diseases, autoimmune disorders or malignancies. A written consent was obtained for each individual. No duplicate patients were included in the analysis and the presence of outliers was investigated. Reference intervals (Mean and central 95% confidence intervals) were determined. Results: Three outliers have been identified and removed from the analysis (60.0, 64.0 and 150.2 ng/mL). A total of 412 subjects were therefore included. The mean value for the whole population was 15.8 ng/mL (2.4−36.4 ng/mL). Males present a significantly higher mean concentration compared to females (17.2 versus 14.4 ng/mL, p = 0.001). A significant trend toward higher ST2 values with age was also observed, but for males only (r = 0.43, p < 0.0001). If considering age partitions, only males of 12−18 years (mean = 21.7 ng/mL) had significantly higher ST2 values compared to the other groups (ranging from 11.9 for males 0−6 years to 15.2 for females 12−18 years; p < 0.0001). Conclusions: We described age and sex-specific reference intervals for ST2 in a large healthy pediatric population. We found that ST2 values differ between sexes if considering all participants. A significant increase in ST2 with age was also observed, but only for males of 12−18 years.

The Translation and Commercialisation of Biomarkers for Cardiovascular Disease—A Review

As a leading cause of mortality and morbidity worldwide, cardiovascular disease and its diagnosis, quantification, and stratification remain significant health issues. Increasingly, patients present with cardiovascular disease in the absence of known risk factors, suggesting the presence of yet unrecognized pathological processes and disease predispositions. Fortunately, a host of emerging cardiovascular biomarkers characterizing and quantifying ischaemic heart disease have shown great promise in both laboratory settings and clinical trials. These have demonstrated improved predictive value additional to widely accepted biomarkers as well as providing insight into molecular phenotypes beneath the broad umbrella of cardiovascular disease that may allow for further personalized treatment regimens. However, the process of translation into clinical practice – particularly navigating the legal and commercial landscape – poses a number of challenges. Practical and legal barriers to the biomarker translational pipeline must be further considered to develop strategies to bring novel biomarkers into the clinical sphere and apply these advances at the patient bedside. Here we review the progress of emerging biomarkers in the cardiovascular space, with particular focus on those relevant to the unmet needs in ischaemic heart disease.

Cardiac biomarkers retain prognostic significance in patients with heart failure and chronic obstructive pulmonary disease

AIMS

Chronic obstructive pulmonary disease (COPD) is a frequent comorbidity in patients with heart failure (HF). We assessed the influence of COPD on circulating levels and prognostic value of three HF biomarkers: N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity troponin T (hs-TnT), and soluble suppression of tumorigenesis-2 (sST2).

METHODS

Individual data from patients with chronic HF, known COPD status, NT-proBNP and hs-TnT values (n = 8088) were analysed. A subgroup (n = 3414) had also sST2 values.

RESULTS

Patients had a median age of 66 years (interquartile interval 57-74), 77% were men and 82% had HF with reduced ejection fraction. NT-proBNP, hs-TnT and sST2 were 1207 ng/l (487-2725), 17 ng/l (9-31) and 30 ng/ml (22-44), respectively. Patients with COPD (n = 1249, 15%) had higher NT-proBNP (P = 0.042) and hs-TnT (P < 0.001), but not sST2 (P = 0.165). Over a median 2.0-year follow-up (1.5-2.5), 1717 patients (21%) died, and 1298 (16%) died from cardiovascular causes; 2255 patients (28%) were hospitalized for HF over 1.8 years (0.9-2.1). NT-proBNP, hs-TnT and sST2 predicted the three end points regardless of COPD status. The best cut-offs from receiver-operating characteristics analysis were higher in patients with COPD than in those without. Patients with all three biomarkers higher than or equal to end-point- and COPD-status-specific cut-offs were also those with the worst prognosis.

CONCLUSIONS

Among patients with HF, those with COPD have higher NT-proBNP and hs-TnT, but not sST2. All these biomarkers yield prognostic significance regardless of the COPD status.

Cardiac biomarkers as indicators of right ventricular dysfunction and recovery in chronic thromboembolic pulmonary hypertension patients after balloon pulmonary angioplasty therapy - a cardiac magnetic resonance imaging cohort study

Background

In chronic thromboembolic pulmonary hypertension, right heart failure determines outcome. Balloon pulmonary angioplasty therapy allows right heart recovery, which can be monitored by cardiac magnetic resonance imaging. This study evaluates whether cardiac biomarkers (NT-proBNP, MR-proANP, sST2, and PAPP-A) are associated with cardiac magnetic resonance imaging findings prior to and after balloon pulmonary angioplasty therapy.

Methods

This observational cohort study enrolled 22 chronic thromboembolic pulmonary hypertension patients who underwent balloon pulmonary angioplasty therapy and completed a six-month follow-up including cardiac magnetic resonance imaging. Biomarker levels were compared with findings for right heart morphology and function derived from cardiac magnetic resonance imaging.

Results

Pulmonary hemodynamics improved after balloon pulmonary angioplasty therapy [pulmonary vascular resistance: 7.7 (6.0–9.0) vs. 4.7 (3.5–5.5) wood units, p < 0.001; mean pulmonary artery pressure 41 (38–47) vs. 32 (28–37) mmHg, p < 0.001]. Cardiac magnetic resonance imaging findings indicated right heart maladaptation at baseline and recovery after therapy [right ventricular end-diastolic volume 192 (141–229) ml vs. 143 (128–172) ml, p = 0.002; right ventricular end-systolic volume 131 (73–157) ml vs. 77 (61–99) ml (p < 0.001); right ventricular ejection fraction (RVEF) 34 (28–41) % vs. 52 (41–54) %; p < 0.001]. Biomarker level cut-offs [NT-proBNP 347 ng/L (area under the curve (AUC) 0.91), MR-proANP 230 pg/L (AUC 0.78), PAPP-A 14.5 mU/L (AUC 0.81), and sST2 48.0 ng/ml (AUC 0.88)] indicated a RVEF ≤ 35% at baseline. The dynamics of NT-proBNP (rs = −0.79; p < 0.001), MR-proANP (rs = –0.80; p < 0.001), and sST2 (rs = –0.49; p = 0.02) correlated inversely with the improvement in RVEF after therapy. A relative decrease of NT-proBNP < 53% (AUC 0.86) and MR-proANP < 24% (AUC 0.82) indicated a limited RVEF response.

Conclusions

In chronic thromboembolic pulmonary hypertension patients, cardiac magnetic resonance imaging findings illustrate right heart failure and recovery after balloon pulmonary angioplasty therapy. Cardiac biomarker levels correlate with right heart parameters at baseline and their dynamics after therapy.

Soluble suppression of tumorigenicity 2 (sST2) for predicting disease severity or mortality outcomes in cardiovascular diseases: A systematic review and meta-analysis

OBJECTIVES

Soluble suppression of tumorigenicity 2 (sST2) is a member of the interleukin-1 receptor family. It is raised in various cardiovascular diseases, but its value in predicting disease severity or mortality outcomes has been controversial. Therefore, we conducted a systematic review and meta-analysis to determine whether sST2 levels differed between survivors and non-survivors of patients with cardiovascular diseases, and whether elevated sST2 levels correlated with adverse outcomes.

METHODS

PubMed and Embase were searched until 23rd June 2021 for studies that evaluated the relationship between sST2 levels and cardiovascular disease severity or mortality.

RESULTS

A total of 707 entries were retrieved from both databases, of which 14 studies were included in the final meta-analysis. In acute heart failure, sST2 levels did not differ between survivors and non-survivors (mean difference [MD]: 24.2 ± 13.0 ng/ml; P = 0.06; I 2: 95%). Elevated sST2 levels tend to be associated with increased mortality risk (hazard ratio [HR]: 1.12, 95 %CI: 0.99-1.27, P = 0.07; I 2: 88%). In chronic heart failure, sST2 levels were higher in non-survivors than in survivors (MD: 0.19 ± 0.04 ng/ml; P = 0.001; I 2: 0%) and elevated levels were associated with increased mortality risk (HR: 1.64, 95% CI: 1.27-2.12, P < 0.001; I 2: 82%). sST2 levels were significantly higher in severe disease compared to less severe disease (MD: 1.56 ± 0.46 ng/ml; P = 0.001; I 2: 98%). Finally, in stable coronary artery disease, sST2 levels were higher in non-survivors than survivors (MD: 3.0 ± 1.1 ng/ml; P = 0.005; I 2: 80%) and elevated levels were significantly associated with increased mortality risk (HR: 1.32, 95% CI: 1.04-1.68, P < 0.05; I 2: 57%).

CONCLUSIONS

sST2 significantly predicts disease severity and mortality in cardiovascular disease and is a good predictor of mortality in patients with stable coronary artery disease and chronic heart failure.

Amyloid Deposits and Fibrosis on Left Ventricular Endomyocardial Biopsy Correlate With Extracellular Volume in Cardiac Amyloidosis

Background The relative contribution of amyloid and fibrosis to extracellular volume expansion in cardiac amyloidosis (CA) has never been defined. Methods and Results We included all patients diagnosed with amyloid light-chain (AL) or transthyretin cardiac amyloidosis at a tertiary referral center between 2014 to 2020 and undergoing a left ventricular endomyocardial biopsy. Patients (n=37) were more often men (92%), with a median age of 72 years (interquartile range, 68-81). Lambda-positive AL was found in 14 of 19 AL cases (38%) and kappa-positive AL in 5 of 19 (14%), while transthyretin was detected in the other 18 cases (48%). Amyloid deposits accounted for 15% of tissue sample area (10%-30%), without significant differences between AL and transthyretin amyloidosis. All patients displayed myocardial fibrosis, with a median extent of 15% of tissue samples (10%-23%; range, 5%-60%), in the absence of spatial overlap with amyloid deposits. Interstitial fibrosis was often associated with mild and focal subendocardial fibrosis. The extent of fibrosis or the combination of amyloidosis and fibrosis did not differ significantly between transthyretin amyloidosis and AL subgroups. In 20 patients with myocardial T1 mapping at cardiac magnetic resonance, the combined amyloid and fibrosis extent displayed a modest correlation with extracellular volume (r=0.661, P=0.001). The combined amyloid and fibrosis extent correlated with high-sensitivity troponin T (P=0.035) and N-terminal pro-B-type natriuretic peptide (P=0.002) serum levels. Conclusions Extracellular spaces in cardiac amyloidosis are enlarged to a similar extent by amyloid deposits and fibrotic tissue. Their combination can better explain the increased extracellular volume at cardiac magnetic resonance and circulating biomarkers than amyloid extent alone.

Integration of imaging and circulating biomarkers in heart failure: a consensus document by the Biomarkers and Imaging Study Groups of the Heart Failure Association of the European Society of Cardiology

Circulating biomarkers and imaging techniques provide independent and complementary information to guide management of heart failure (HF). This consensus document by the Heart Failure Association (HFA) of the European Society of Cardiology (ESC) presents current evidence-based indications relevant to integration of imaging techniques and biomarkers in HF. The document first focuses on application of circulating biomarkers together with imaging findings, in the broad domains of screening, diagnosis, risk stratification, guidance of treatment and monitoring, and then discusses specific challenging settings. In each section we crystallize clinically relevant recommendations and identify directions for future research. The target readership of this document includes cardiologists, internal medicine specialists and other clinicians dealing with HF patients.

Generation and Characterization of Torudokimab (LY3375880): A Monoclonal Antibody That Neutralizes Interleukin-33

Background

Interleukin-33 (IL-33) is an alarmin that is released following cellular damage, mechanical injury, or necrosis. It is a member of the IL-1 family and binds to a heterodimer receptor consisting of ST2 and IL-1RAP to induce the production of a wide range of cellular mediators, including the type 2 cytokines IL-4, IL-5 and IL-13. This relationship has led to the hypothesis that the IL-33/ST2 pathway is a driver of allergic disease and inhibition of the IL-33 and ST2 association could have therapeutic benefit.

Methods

In this paper, we describe the selection of a phage antibody through the ability to bind human IL-33 and block IL-33/ST2 interaction. This hit antibody was then affinity matured by site-directed mutagenesis of the antibody complementarity-determining regions (CDRs). Further characterization of a fully human monoclonal antibody (mAb), torudokimab (LY3375880) included demonstration of human IL-33 neutralization activity in vitro with an NFκB reporter assay and IL-33 induced mast cell cytokine secretion assay, followed by an in vivo IL-33-induced pharmacodynamic inhibition assay in mice that used IL-5 production as the endpoint.

Results

Torudokimab is highly specific to IL-33 and does not bind any of the other IL-1 family members. Furthermore, torudokimab binds human and cynomolgus monkey IL-33 with higher affinity than the binding affinity of IL-33 to ST2, but does not bind mouse, rat, or rabbit IL-33. Torudokimab’s half-life in cynomolgous monkey projects monthly dosing in the clinic.

Conclusion

Due to torudokimab’s high affinity, its ability to completely neutralize IL-33 activity in vitro and in vivo, and the observed cynomolgus monkey pharmacokinetic properties, this molecule was selected for clinical development.

Pre-analytical considerations in biomarker research: focus on cardiovascular disease

Clinical biomarker research is growing at a fast pace, particularly in the cardiovascular field, due to the demanding requirement to provide personalized precision medicine. The lack of a distinct molecular signature for each cardiovascular derangement results in a one-size-fits-all diagnostic and therapeutic approach, which may partially explain suboptimal outcomes in heterogeneous cardiovascular diseases (e.g., heart failure with preserved ejection fraction). A multidimensional approach using different biomarkers is quickly evolving, but it is necessary to consider pre-analytical variables, those to which a biological sample is subject before being analyzed, namely sample collection, handling, processing, and storage. Pre-analytical errors can induce systematic bias and imprecision, which may compromise research results, and are easy to avoid with an adequate study design. Academic clinicians and investigators must be aware of the basic considerations for biospecimen management and essential pre-analytical recommendations as lynchpin for biological material to provide efficient and valid data.

Novel Biomarkers in Heart Failure: New Insight in Pathophysiology and Clinical Perspective

Heart failure (HF) is a complex clinical syndrome with a huge social burden in terms of cost, morbidity, and mortality. Brain natriuretic peptide (BNP) appears to be the gold standard in supporting the daily clinical management of patients with HF. Novel biomarkers may supplement BNP to improve the understanding of this complex disease process and, possibly, to personalize care for the different phenotypes, in order to ameliorate prognosis. In this review, we will examine some of the most promising novel biomarkers in HF. Inflammation plays a pivotal role in the genesis and progression of HF and, therefore, several candidate molecules have been investigated in recent years for diagnosis, prognosis, and therapy monitoring. Noncoding RNAs are attractive as biomarkers and their potential clinical applications may be feasible in the era of personalized medicine. Given the complex pathophysiology of HF, it is reasonable to expect that the future of biomarkers lies in the application of precision medicine, through wider testing panels and “omics” technologies, to further improve HF care delivery.

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.

Development of a Novel Homogeneous Nanoparticle-Based Assay for Rapid and High-Throughput Quantitation of the sST2 Protein in Human Serum

Purpose

The suppression of tumorigenicity 2 (ST2) protein is a member of the interleukin-1 receptor family with the transmembrane (ST2L) and soluble (sST2) subtypes and plays an important role in several diseases. Therefore, the present study aimed to establish and validate a novel amplified luminescent proximity homogeneous immunoassay (AlphaLISA) for the detection of sST2 in human serum.

Materials and Methods

Based on a sandwich-type immunoassay format, sST2 was captured using two different anti-sST2 antibodies. One of the antibodies was biotinylated while the other one was coated with AlphaLISA chemibeads. Thereafter, multiple tests were conducted to optimize the working conditions and validate analytical performance.

Results

The optimum concentration of the biotinylated antibodies was 1 μg/mL while the optimal dilution ratio for the anti-sST2 antibodies and conjugated chemibeads was 1:500. In addition, the optimal antigen-antibody reaction time was 15 minutes (min). Notably, the developed method showed a short turnaround time of about 25 min. Moreover, the assay exhibited high sensitivity with a limit of detection (LOD) of 0.176 ng/mL and a limit of quantification (LOQ) of 0.8 ng/mL. Furthermore, the intra-assay precision and inter-assay precision values were 5.29–7.10% and 9.41%–13.66%, respectively. It is also noteworthy that the test results deviated by less than ±10% when samples had ≤10.0 ng/mL of triglycerides, ≤0.5 mmol/L of bilirubin, ≤5.0 g/L of triglyceride, and ≤250 μg/L of biotin. Additionally, the developed assay was almost consistent with the commercially available PresageTM ST2 assay kit, with a Spearman correlation coefficient of 0.916 and an R² of 0.963 as well as a slope of 0.957 from linear regression analysis.

Conclusion

The present study showed that the sandwich AlphaLISA is a rapid, high-throughput, and reliable test for studying the levels of sST2 in a variety of diseases.

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.

Clinical and Prognostic Significance of sST2 in Heart Failure: JACC Review Topic of the Week

Soluble suppression of tumorigenesis-2 (sST2) is released in response to vascular congestion and inflammatory and pro-fibrotic stimuli, and is a strong, independent predictor of mortality and heart failure (HF) hospitalization in patients with acute or chronic HF. sST2 meets 2 fundamental criteria for clinically useful biomarkers: accurate, repeated measurements are available at a reasonable cost, and the biomarker provides information not already available from a careful clinical assessment. In particular, the prognostic value of sST2 is additive to natriuretic peptides and (in the case of chronic HF) to high-sensitivity troponin T. Nevertheless, the need for a multibiomarker approach to risk stratification and the role of sST2 as a guide to therapy decision-making remain to be established. Four years after a consensus document on sST2, and following major advances in the comprehension of the clinical value of this biomarker, the authors felt it worthwhile to reappraise current knowledge on sST2 in HF.

Serum soluble suppression of tumorigenicity-2 level associates with severity of pulmonary hypertension associated with uncorrected atrial septal defect

Uncorrected atrial septal defect undergoes right ventricle chronic volume overload which may lead to pulmonary hypertension and Eisenmenger Syndrome. The soluble suppression of tumorigenicity-2 is a left ventricle strain biomarker; however, its role in right ventricle strain is unclear. This study aimed to investigate the implication of serum soluble suppression of tumorigenicity-2 in adult uncorrected atrial septal defect. This was a cross-sectional study. We enrolled 81 adult uncorrected secundum atrial septal defect patients. Clinical and hemodynamic data were collected. Serum samples were withdrawn from the pulmonary artery during right heart catheterization. Serum soluble suppression of tumorigenicity-2 and NT-proBNP levels were measured. Subjects were divided into three groups based on clinical and hemodynamic severity. The correlation of soluble suppression of tumorigenicity-2 with patients' data and comparison among groups were analyzed. A p value <0.05 was considered statistically significant. Results showed that, there were significant correlations between serum soluble suppression of tumorigenicity-2 and mean pulmonary artery pressure (r = 0.203, p = 0.035) and right ventricle end-diastolic diameter (r = 0.203, p <0.05). Median serum soluble suppression of tumorigenicity-2 level was incrementally increased from group I (atrial septal defect and no-pulmonary hypertension), group II (left-to-right atrial septal defect and pulmonary hypertension), to group III (Eisenmenger Syndrome): (17.4 ng/mL, 21.8 ng/mL, and 29.4 ng/mL, respectively). A post-hoc analysis showed that serum soluble suppression of tumorigenicity-2 level was significantly different between groups I and III (p = 0.01). Serum N terminal pro brain natriuretic peptide (NT-proBNP) level was consistently associated with worse clinical and hemodynamic parameters. No correlation was found between serum soluble suppression of tumorigenicity-2 and NT-proBNP level. In conclusion, serum soluble suppression of tumorigenicity-2 level had significant positive correlation with mean pulmonary artery pressure and right ventricle end-diastolic diameter in uncorrected secundum atrial septal defect patients. Higher serum soluble suppression of tumorigenicity-2 level was associated with the presence of pulmonary hypertension and Eisenmenger Syndrome in uncorrected secundum atrial septal defect patients.

Prospective diagnostic accuracy study of plasma soluble ST2 for diagnosis of acute aortic syndromes

Acute aortic syndromes (AASs) are difficult to diagnose emergencies. Plasma soluble ST2 (sST2), a prognostic biomarker for heart failure, has been proposed as a diagnostic biomarker of AASs outperforming D-dimer, the current diagnostic standard. We performed a prospective diagnostic accuracy study of sST2 for AASs in the Emergency Department (ED). In 2017–2018, patients were enrolled if they had ≥1 red-flag symptoms (chest/abdominal/back pain, syncope, perfusion deficit) and a clinical suspicion of AAS. sST2 was detected with the Presage® assay. Adjudication was based on computed tomography angiography (CTA) or on diagnostic outcome inclusive of 30-day follow-up. 297 patients were enrolled, including 88 with AASs. The median age was 67 years. In 162 patients with CTA, the median sST2 level was 41.7 ng/mL (IQR 29.4–103.2) in AASs and 34.6 ng/mL (IQR 21.4–51.5) in alternative diagnoses (P = 0.005). In ROC analysis, the AUC of sST2 was 0.63, as compared to 0.82 of D-dimer (P < 0.001). Sensitivity and specificity values of sST2 associated with different cutoffs were: 95.5% and 10.8% (≥12 ng/mL), 84.1% and 29.7% (≥23.7 ng/mL), 35.2% and 85.1% (≥66.5 ng/mL). Results were similar in the full cohort. In conclusion, in patients from a European ED, plasma sST2 provided modest accuracy for diagnosis of AASs.

Soluble ST2 is a Useful Biomarker for Grading Cerebral-Cardiac Syndrome in Patients after Acute Ischemic Stroke

This study tested whether the soluble (s)ST2 is a superb biomarker predictive of moderate to severe cerebral-cardiac syndrome (CCS) (defined as coexisting National Institute of Health Stroke Scale (NIHSS) >8 and left-ventricular ejection fraction (LVEF) <60%) in patients after acute ischemic stroke (IS). Between November 2015 and October 2017, a total of 99 IS patients were prospectively enrolled and categorized into three groups based on NIHSS, i.e., group 1 (NIHSS ≤ 8, n = 66), group 2 (NIHSS = 9-15, n = 14) and group 3 (NIHSS ≥ 16, n = 19), respectively. Blood samples were collected immediately after hospitalization, followed by transthoracic echocardiographic examination. The results showed that the flow cytometric analysis for assessment of inflammatory biomarkers of TLR2+/CD14+cells, TLR4+/CD14+cells, Ly6g+/CD14+cells, and MPO+/CD14+cells, and ELISA assessment for circulatory level of sST2 were significantly higher in groups 2/3 than in group 1 (all p < 0.01). However, these parameters did not show significant differences between groups 2 and 3 (all p > 0.05). The LVEF was significantly lower in group 3 than in group 1 (p < 0.001), but it displayed no difference between groups 1/2 or between groups 2/3. These inflammatory biomarkers ((TLR2+/CD14+cells// TLR4+/CD14+cells// MPO+/CD14+cells) and sST2)) were significantly positively correlated to NIHSS and strongly negatively correlated to LVEF (all p < 0.05). Multivariate analysis demonstrated that both MPO/CD14+cells >20% (p = 0.027) and sST2 ≥ 17,600 (p = 0.004) were significantly and independently predictive of moderate-severe CCS after acute IS. Receiver operating characteristic curve analysis demonstrated that sST2 was the most powerful predictor of CCS with a sensitivity of 0.929 and a specificity of 0.731 (p < 0.001). In conclusion, sST2 is a useful biomarker for prediction of CCS severity in patients after acute IS.

Association of plasma-soluble ST2 and galectin-3 with cardiovascular events and mortality following cardiac surgery

BACKGROUND

Cardiac surgery induces hemodynamic stress on the myocardium, and this process can be associated with significant post-operative morbidity and mortality. Soluble suppression of tumorigenicity 2 (sST2) and galectin-3 (gal-3) are biomarkers of myocardial remodeling and fibrosis; however, their potential association with post-operative changes is unknown.

METHODS

We measured peri-operative plasma sST2 and gal-3 levels in two prospective cohorts (TRIBE-AKI and NNE) of over 1800 patients who underwent cardiac surgery. sST2 and gal-3 levels were evaluated for association with a composite primary outcome of cardiovascular event or mortality over median follow-up periods of 3.4 and 6.0 years, respectively, for the two cohorts. Meta-analysis of hazard ratio estimates from the cohorts was performed using random effects models.

RESULTS

Cohorts demonstrated event rates of 70.2 and 66.8 per 1000 person-years for the primary composite outcome. After adjustment for clinical covariates, higher post-operative sST2 and gal-3 levels were significantly associated with cardiovascular event or mortality [pooled estimate HRs: sST2 1.29 (95% CI 1.16, 1.44); gal-3 1.26 (95% CI 1.09, 1.46)]. These associations were not significantly modified by pre-operative congestive heart failure or AKI.

CONCLUSIONS

Higher post-operative sST2 and gal-3 values were associated with increased incidence of cardiovascular event or mortality. These two biomarkers should be further studied for potential clinical utility for patients undergoing cardiac surgery.

ST2 PLASMA LEVEL IN PATIENTS WITH ACUTE MYOCARDIAL INFARCTION WITHOUT ST ELEVATION AND DIFFERENT CLINICAL CHARACTERISTICS

The aim. Estimation of ST2 plasma level in patients with acute myocardial infarction without ST elevation (NSTEMI) and its relationship with different clinical characteristics. Materials and methods. 165 patients aged from 35 to 79 (average of 60.7±0.8 years) with various forms of coronary artery disease (CAD) with and without arterial hypertension were examined. The variability of plasma ST2 level in different forms of CAD and in NSTEMI group was analyzed depending on gender-age and clinical characteristics and features of the disease course. Results: The results of the present investigation were that the ST2 level in the main cohort was in range from 5.5 to 233.9 (in the middle – 49.8±3.5 ng / ml (median indicator – 34.7 and the interquartile range – 21.9 and 59.1 respectively). Significantly higher ST2 levels were found in patients with NSTEMI, unlike the comparison group, in the median analysis (35.9 vs. 27.7 ng/ml, p=0.047) and no statistical differences were observed in the mean values. In patients with NSTEMI, a certain association of ST2 level in plasma with the MI course was detected. A higher level of neurohormone is registered with anterior unlike posterior ECG localization of MI; at high unlike moderate risk on the GRACE scale; when complicated unlike the uncomplicated course of MI; in the case of acute HF and cardiac arrhythmias unlike patients with the absence of these manifestations in the acute period of MI. Conclusions. High variability of ST2 level in plasma was demonstrated in patients with NSTEMI on the first day after destabilization (minimum and maximum values – 12.7 and 233.9 respectively, median – 35.9 and interquartile range – 25.9 and 55.7 ng / ml). It is shown that significantly higher ST2 level in plasma is determined in patients with acute MI regardless of its variant among different clinical forms of CAD. It is found that significantly higher level of ST2 in patients with NSTEMI is recorded in the case of concomitant HTN and type 2 diabetes, with smoking and heavy cardiovascular heredity. Proved influence of the character of MI course on the level of ST2 in plasma, significantly higher level of neurohormone was determined with anterior localization of MI, high risk on the GRACE scale (≥ 140 points), complicated course of MI, development of cardiac arrhythmias and HF in the acute period of MI.

Heart failure biomarker levels correlate with invasive haemodynamics in pulmonary valve replacement

BACKGROUND

Although widely used in cardiology, relation of heart failure biomarkers to cardiac haemodynamics in patients with CHD (and in particular with pulmonary insufficiency undergoing pulmonary valve replacement) remains unclear. We hypothesised that the cardiac function biomarkers N-terminal pro-brain natriuretic peptide (NT-proBNP), soluble suppressor of tumorigenicity 2, and galectin-3 would have significant associations to right ventricular haemodynamic derangements.

METHODS

Consecutive patients ( n = 16) undergoing cardiac catheterisation for transcatheter pulmonary valve replacement were studied. NT-proBNP, soluble suppressor of tumorigenicity 2, and galectin-3 levels were measured using a multiplex enzyme-linked immunosorbent assay from a pre-intervention blood sample obtained after sheath placement. Spearman correlation was used to identify significant correlations (p ≤ 0.05) of biomarkers with baseline cardiac haemodynamics. Cardiac MRI data (indexed right ventricular and left ventricular end-diastolic volumes and ejection fraction) prior to device placement were also compared to biomarker levels.

RESULTS

NT-proBNP and soluble suppressor of tumorigenicity 2 were significantly correlated (p < 0.01) with baseline mean right atrial pressure and right ventricular end-diastolic pressure. Only NT-proBNP was significantly correlated with age. Galectin-3 did not have significant associations in this cohort. Cardiac MRI measures of right ventricular function and volume were not correlated to biomarker levels or right heart haemodynamics.

CONCLUSIONS

NT-proBNP and soluble suppressor of tumorigenicity 2, biomarkers of myocardial strain, significantly correlated to invasive pressure haemodynamics in transcatheter pulmonary valve replacement patients. Serial determination of soluble suppressor of tumorigenicity 2, as it was not associated with age, may be superior to serial measurement of NT-proBNP as an indicator for timing of pulmonary valve replacement.

sST2 Predicts Outcome in Chronic Heart Failure Beyond NT-proBNP and High-Sensitivity Troponin T

BACKGROUND

Soluble suppression of tumorigenesis-2 (sST2) is a biomarker related to inflammation and fibrosis.

OBJECTIVES

This study assessed the independent prognostic value of sST2 in chronic heart failure (HF).

METHODS

Individual patient data from studies that assessed sST2 for risk prediction in chronic HF, together with N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity troponin T (hs-TnT), were retrieved.

RESULTS

A total of 4,268 patients were evaluated (median age 68 years, 75% males, 65% with ischemic HF, 87% with left ventricular ejection fraction [LVEF] <40%). NT-proBNP, hs-TnT, and sST2 were 1,360 ng/l (interquartile interval: 513 to 3,222 ng/l), 18 ng/l (interquartile interval: 9 to 33 ng/l), and 27 ng/l (interquartile interval: 20 to 39 ng/l), respectively. During a 2.4-year median follow-up, 1,319 patients (31%) experienced all-cause death (n = 932 [22%] for cardiovascular causes). Among the 4,118 patients (96%) with available data, 1,029 (24%) were hospitalized at least once for worsening HF over 2.2 years. The best sST2 cutoff for the prediction of all-cause and cardiovascular death and HF hospitalization was 28 ng/ml, with good performance at Kaplan-Meier analysis (log-rank: 117.6, 61.0, and 88.6, respectively; all p < 0.001). In a model that included age, sex, body mass index, ischemic etiology, LVEF, New York Heart Association functional class, glomerular filtration rate, HF medical therapy, NT-proBNP, and hs-TnT, the risk of all-cause death, cardiovascular death, and HF hospitalization increased by 26%, 25%, and 30%, respectively, per each doubling of sST2. sST2 retained its independent prognostic value across most population subgroups.

CONCLUSIONS

sST2 yielded strong, independent predictive value for all-cause and cardiovascular mortality, and HF hospitalization in chronic HF, and deserves consideration to be part of a multimarker panel together with NT-proBNP and hs-TnT.

Short-term and long-term prognostic value of circulating soluble suppression of tumorigenicity-2 concentration in acute coronary syndrome: a meta-analysis

Background: Higher circulating soluble suppression of tumorigenicity-2 (sST2) concentration is suggested as a marker of prognosis in many cardiovascular diseases. However, the short-term and long-term prognostic value of sST2 concentration in acute coronary syndrome (ACS) remains to be summarized.Methods: A meta-analysis of follow-up studies was performed. Studies were identified via systematic search of databases including PubMed, Cochrane's Library, and Embase. A fixed- or random-effect model was applied according to the heterogeneity. We reported the prognostic value of sST2 concentration for all-cause mortality, heart failure (HF) events, and major adverse cardiovascular events (MACEs) within 1 month after hospitalization and during subsequent follow-up.Results: Twelve studies with 11690 ACS patients were included. Higher baseline sST2 concentration as continuous variables predicte the increased risk of all-cause mortality (risk ratio [RR]: 3.16, P=0.002), HF events (RR: 1.48, P<0.001), and MACEs (RR: 1.47, P<0.001) within 1 month after hospitalization, which is consistent with the results with sST2 concentration as categorized variables (RR = 2.14, 2.89, and 2.89 respectively, P all <0.001). Moreover, higher baseline sST2 concentration as continuous variables predict the increased risk of all-cause mortality (RR: 2.20, P<0.001), HF events (RR: 1.39, P<0.001), and MACEs (RR: 1.53, P=0.02) during subsequent follow-up. Meta-analysis with sST2 concentration as categorized variables retrieved similar results (RR = 2.65, 2.59, and 1.81 respectively, P all <0.001).Conclusions: Higher circulating sST2 concentration at baseline predicts poor clinical outcome in ACS patients.

Revisiting the obesity paradox in heart failure: Per cent body fat as predictor of biomarkers and outcome

Aims

Obesity defined by body mass index (BMI) is characterized by better prognosis and lower plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) in heart failure. We assessed whether another anthropometric measure, per cent body fat (PBF), reveals different associations with outcome and heart failure biomarkers (NT-proBNP, high-sensitivity troponin T (hs-TnT), soluble suppression of tumorigenesis-2 (sST2)).

Methods

In an individual patient dataset, BMI was calculated as weight (kg)/height (m) 2 , and PBF through the Jackson–Pollock and Gallagher equations.

Results

Out of 6468 patients (median 68 years, 78% men, 76% ischaemic heart failure, 90% reduced ejection fraction), 24% died over 2.2 years (1.5–2.9), 17% from cardiovascular death. Median PBF was 26.9% (22.4–33.0%) with the Jackson–Pollock equation, and 28.0% (23.8–33.5%) with the Gallagher equation, with an extremely strong correlation ( r = 0.996, p < 0.001). Patients in the first PBF tertile had the worst prognosis, while patients in the second and third tertile had similar survival. The risks of all-cause and cardiovascular death decreased by up to 36% and 27%, respectively, per each doubling of PBF. Furthermore, prognosis was better in the second or third PBF tertiles than in the first tertile regardless of model variables. Both BMI and PBF were inverse predictors of NT-proBNP, but not hs-TnT. In obese patients (BMI ≥ 30 kg/m2, third PBF tertile), hs-TnT and sST2, but not NT-proBNP, independently predicted outcome.

Conclusion

In parallel with increasing BMI or PBF there is an improvement in patient prognosis and a decrease in NT-proBNP, but not hs-TnT or sST2. hs-TnT or sST2 are stronger predictors of outcome than NT-proBNP among obese patients.

Increased serum concentrations of soluble ST2 predict mortality after burn injury

Background:

Large burn injuries induce a systemic response in affected patients. Soluble ST2 (sST2) acts as a decoy receptor for interleukin-33 (IL-33) and has immunosuppressive effects. sST2 has been described previously as a prognostic serum marker. Our aim was to evaluate serum concentrations of sST2 and IL-33 after thermal injury and elucidate whether sST2 is associated with mortality in these patients.

Methods:

We included 32 burn patients (total body surface area [TBSA] >10%) admitted to our burn intensive care unit and compared them to eight healthy probands. Serum concentrations of sST2 and IL-33 were measured serially using an enzyme-linked immunosorbent assay (ELISA) technique.

Results:

The mean TBSA was 32.5%±19.6%. Six patients (18.8%) died during the hospital stay. Serum analyses showed significantly increased concentrations of sST2 and reduced concentrations of IL-33 in burn patients compared to healthy controls. In our study cohort, higher serum concentrations of sST2 were a strong independent predictor of mortality.

Conclusions:

Burn injuries cause an increment of sST2 serum concentrations with a concomitant reduction of IL-33. Higher concentrations of sST2 are associated with increased in-hospital mortality in burn patients.

Interleukin-33 in Systemic Sclerosis: Expression and Pathogenesis

Interleukin-33 (IL-33), a member of the IL-1 superfamily, functions as a traditional cytokine and nuclear factor. It is proposed to have an “alarmin” role. IL-33 mediates biological effects by interacting with the ST2 receptor and IL-1 receptor accessory protein, particularly in innate immune cells and T helper 2 cells. Recent articles have described IL-33 as an emerging pro-fibrotic cytokine in the immune system as well as a novel potential target for systemic sclerosis. Here, we review the available information and focus on the pleiotropic expression and pathogenesis of IL-33 in systemic sclerosis, as well as the feasibility of using IL-33 in clinical applications.

Usefulness of Enhanced Liver Fibrosis, Glycosylation Isomer of Mac-2 Binding Protein, Galectin-3, and Soluble Suppression of Tumorigenicity 2 for Assessing Liver Fibrosis in Chronic Liver Diseases

BACKGROUND

Liver biopsies have been partially replaced by noninvasive methods for assessing liver fibrosis. We explored the usefulness of four novel biomarkers, enhanced liver fibrosis (ELF), glycosylation isomer of Mac-2 binding protein (M2BPGi), galectin-3, and soluble suppression of tumorigenicity 2 (sST2), in association with liver fibrosis.

METHODS

ELF, M2BPGi, galectin-3, and sST2 were assayed in 173 patients with chronic liver diseases. The results were analyzed according to fibrosis grade (F0/1, F2, and F3/4) by transient elastography (TE).

RESULTS

ELF, M2BPGi, galectin-3, and sST2 values differed significantly according to TE grade; ELF and M2BPGi values were higher in F2 and F3/4 than in F0/1 (P≤0.001, all), sST2 values were higher in F3/4 than in F0/1 and F2 (P<0.05), and galectin-3 values were higher in F3/4 than in F0/1 (P=0.0036). ELF and M2BPGi showed good TE fibrosis detection performance (area under the curves [AUC], 0.841 and 0.833 for ≥F2; and 0.837 and 0.808 for ≥F3). The sensitivity and specificity for predicting TE grade F≥2 were 84.1% and 76.7% for ELF and 63.6% and 91.5% for M2BPGi.

CONCLUSIONS

This is the first study to compare the liver fibrosis assessment of four novel biomarkers: ELF, M2BPGi, galectin-3, and sST2. The biomarkers varied significantly according to TE grade, and each biomarker showed a different trend. ELF and M2BPGi seem to have comparable good performance for detecting liver fibrosis.

ST2 elevation in heart failure, predictive of a high early mortality

Background

Soluble suppression of tumorigenicity-2 (sST2) is a novel biomarker shown to be useful for prognostic assessment in heart failure (HF). However, very limited data exists about its prognostic utility in patients with HF in India.

Methods

We studied 150 patients [mean age 67.7 ± 13.3, 93 (62%) males], hospitalized with clinical HF, irrespective of their left ventricular ejection fraction (LVEF). HF was confirmed by N-terminal probrain natriuretic peptide (NT-proBNP) value above 125 ng/L. Primary end point was death or cardiac transplant at 1-year follow-up, with additional telephonic follow-up performed at 2 years. The clinical outcomes were correlated with the sST2 values obtained at the time of initial hospitalization.

Results

HF was ischemic in origin in 82.0% patients. The primary outcome occurred in 9.3% patients at the end of 1-year follow-up and in 16.7% patients at the end of 2 years. The patients who had events had significantly higher NT-proBNP and sST2 values, but there was no difference in the clinical characteristics, cause of HF, baseline LVEF, or serum creatinine. The patients with elevated sST2 levels (>35 ng/mL) had substantially higher event rates than those with normal sST2 levels (13.7% vs 0.0% at 1-year, P = 0.005; 22.5% vs 4.2% at 2-years, P = 0.004). On multivariate analysis, sST2 was the strongest predictor of adverse outcomes at both 1-year and 2-year follow-ups.

Conclusion

In patients hospitalized for HF, elevated sST2 >35 ng/mL at the time of initial hospitalization was associated with significantly high mortality over a 2-year period. The prognostic value of sST2 was incremental to that of NT-proBNP. These findings suggest that a single elevated sST2 value at the time of hospitalization should alert the physicians about the high risk of adverse outcomes and should help facilitate timely intensification of HF treatment.

Prognostic Role of High-sensitivity Cardiac Troponin I and Soluble Suppression of Tumorigenicity-2 in Surgical Intensive Care Unit Patients Undergoing Non-cardiac Surgery

Background

The prognostic utility of cardiac biomarkers, high-sensitivity cardiac troponin I (hs-cTnI) and soluble suppression of tumorigenicity-2 (sST2), in non-cardiac surgery is not well-defined. We evaluated hs-cTnI and sST2 as predictors of 30-day major adverse cardiac events (MACE) in patients admitted to the surgical intensive care unit (SICU) following major non-cardiac surgery.

Methods

hs-cTnI and sST2 concentrations were measured in 175 SICU patients immediately following surgery and for three days postoperatively. The results were analyzed in relation to 30-day MACE and were compared with the revised Goldman cardiac risk index (RCRI) score.

Results

Overall, 30-day MACE was observed in 16 (9.1%) patients. hs-cTnI and sST2 concentrations differed significantly between the two groups with and without 30-day MACE (P<0.05). The maximum concentration of sST2 was an independent predictor of 30-day MACE (odds ratio=1.016, P=0.008). The optimal cut-off values of hs-cTnI and sST2 for predicting 30-day MACE were 53.0 ng/L and 182.5 ng/mL, respectively. A combination of hs-cTnI and sST2 predicted 30-day MACE better than the RCRI score. Moreover, 30-day MACE was observed more frequently with increasing numbers of above-optimal cut-off hs-cTnI and sST2 values (P<0.0001). Reclassification analyses indicated that the addition of biomarkers to RCRI scores improved the prediction of 30-day MACE.

Conclusions

This study demonstrates the utility of hs-cTnI and sST2 in predicting 30-day MACE following non-cardiac surgery. Cardiac biomarkers would provide enhanced risk stratification in addition to clinical RCRI scores for patients undergoing major non-cardiac surgery.

Soluble ST2 for Risk Stratification and the Prediction of Mortality in Patients Undergoing Transcatheter Aortic Valve Implantation

This study aimed to assess the prognostic value of soluble ST2 (sST2) for risk stratification in patients undergoing transcatheter aortic valve implantation (TAVI). In 461 patients undergoing TAVI, sST2 was determined at baseline and categorized into quartiles. An optimum cutoff of 29 ng/ml was calculated. Primary end point was 1-year all-cause mortality. Results were validated in an independent cohort. Patients with sST2 >29 ng/ml had an increased 30-day (9.7% vs 4.6%, p = 0.043) and 1-year mortality (38.1% vs 21.8%, p = 0.001). In accordance, patients with N-terminal pro-brain natriuretic peptide (NT-proBNP) >8145 pg/ml revealed a comparable 30-day mortality (7.9% vs 4.7%, p = 0.189) and 1-year mortality (39.5% vs 21.0%, p <0.001). In univariate regression analysis, sST2 and NT-proBNP were associated with increased mortality risk. In multivariate regression analysis, independent predictors of mortality were logistic EuroSCORE, chronic renal failure, left ventricular ejection fraction, and sST2. In receiver operating characteristic curve analysis, sST2 did not provide incremental prognostic information beyond that obtained from surgical risk scores such as the STS-PROM or NT-proBNP. Similar findings could be achieved in an independent validation cohort. In conclusion, sST2 is independently associated with adverse outcome after TAVI but was not superior to NT-proBNP or surgical risk scores for the prediction of postprocedural outcomes.

A Multiparametric Approach Based on NT-proBNP, ST2, and Galectin3 for Stratifying One Year Prognosis of Chronic Heart Failure Outpatients

Galectin-3 and ST2 are emerging biomarkers involved in myocardial fibrosis. We evaluate the relevance of a multiparametric biomarker approach based on increased serum levels of NT-proBNP, galectin-3, and ST2 in stratifying the prognosis of chronic heart failure (CHF) outpatients. In 315 CHF outpatients in stable clinical condition clinical and echocardiographic evaluations were performed. Routine chemistry and serum levels of NT-proBNP, galectin-3, and ST2 were also assessed. During a 12 month follow-up, cardiovascular death, and/or heart failure (HF) occurred in 64 patients. The presence of NT-proBNP, galectin-3, and ST2 were higher than the recommended cutoffs and were all associated with events at univariate Cox regression analysis, as well as in a multivariate analysis including the three biomarkers. When a score based on the number of biomarkers above the recommended cut-offs was used (in a range of 0-3), it was associated with events both with respect to the univariate (HR 2.96, 95% CI 2.21-3.95, p < 0.001, C-index 0.78) and the multivariate (HR 1.52, 95% CI 1.06-2.17, p: 0.023, C-index 0.87) analyses, after correction for the variables of a reference model. Our results suggest that an easy prognostic approach based on the combination of three biomarkers, although with partially-overlapping pathophysiological mechanisms, is able to identify patients with the highest risk of heart failure progression.

Diagnostic utility of biomarkers of left ventricular stress in patients with aortic stenosis and preserved left ventricular ejection fraction

INTRODUCTION

Aortic stenosis (AS) is the most common acquired valvular heart disease. The early identification of patients with severe AS is crucial. NT-proBNP is a well-known biomarker of pressure overload, and its role in patients with AS has been demonstrated in previous studies. Another, less well-known biomarker of pressure overload is sST2 protein, and its role in AS is unclear.

AIM

To evaluate the utility of sST2 protein, NT-proBNP and selected clinical parameters in the assessment of degenerative AS severity in a population with preserved left ventricular ejection fraction (LVEF).

MATERIAL AND METHODS

Sixty-nine consecutive patients (mean age: 68.42 ±12.58 years, 55.07% male) with symptomatic degenerative AS and preserved LVEF ≥ 45% were prospectively included. At enrollment complete transthoracic echocardiographic examination, ECG analysis, and standard laboratory tests including NT-proBNP were performed and blood samples for sST2 were obtained.

RESULTS

There were 43 (62.32%) patients with severe AS. The multivariate stepwise linear regression models revealed that only systolic blood pressure (SBP), Sokolow-Lyon index and left ventricular end-diastolic diameter (LVEDD) were independently associated with severe AS. Spearman correlation coefficients analysis showed no correlations between sST2 levels and a mild to moderate correlation between NT-proBNP concentration and parameters of AS severity. However, levels of NT-proBNP (p = 0.1857) and sST2 (p = 0.7851) did not differentiate patients according to severity of AS.

CONCLUSIONS

In the study population with degenerative AS and preserved LVEF neither the NT-proBNP nor sST2 concentrations can be used to differentiate patients according to the severity of AS.