Increased levels of soluble ST2 protein and IgG1 production in patients with sepsis and trauma

Soluble ST2 as a possible biomarker for inflammation in patients with acute heart failure

AIM

The aim of this study was to explore the relationship between peripheral circulating serum soluble suppression of tumorigenicity-2 (sST2) levels and inflammatory biomarkers in patients with acute heart failure (AHF).

METHODS

One hundred and eleven consecutive AHF patients with NYHA class II-IV were enrolled, and peripheral blood was collected within 24 h of admission for the detection of NT-ProBNP, sST2, hypersensitive troponin I, cytokines, precalcitoninogen, C-reactive protein, in addition to routine standard of care blood tests.

RESULTS

The median sST2 of 111 patients was 47.50 ng/ml (24.25-86.15 IQR), of whom 43 patients (38.7%) had sST2 35 ng/ml or less; linear correlation analysis showed that serum sST2 correlated with NT-ProBNP ( r2  = 0.32), NEU% ( r2  = 0.41), NLR ( r2  = 0.36), CRP ( r2  = 0.50), IL-18 ( r2  = 0.43) ( P  < 0.001), and correlated with Hs-cTnI ( r2  = 0.19), NUE ( r2  = 0.25), LYM ( r2  = -0.23), IL-2RA ( r2  = 0.29) ( P  < 0.05). Multiple linear regression analysis depicted that CRP (β = 0.318), IL-18 (β = 0.368), NEU% (β = 0.346), NLR (β = -0.304), and NT-ProBNP (β = 0.324) significantly correlated with sST2 values, respectively ( P  < 0.05). ST2 levels have a linear association with length of hospitalization.

CONCLUSION

Peripheral blood inflammatory markers (CRP, IL-18, NEU%, NLR) in patients with AHF had a close relationship with sST2 levels, and the mechanism of action of sST2 may be related to the inflammatory response.

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.

Role of IL-33-ST2 pathway in regulating inflammation: current evidence and future perspectives

Interleukin (IL)-33 is an alarmin of the IL-1 superfamily localized to the nucleus of expressing cells, such as endothelial cells, epithelial cells, and fibroblasts. In response to cellular damage or stress, IL-33 is released and activates innate immune responses in some immune and structural cells via its receptor interleukin-1 receptor like-1 (IL-1RL1 or ST2). Recently, IL-33 has become a hot topic of research because of its role in pulmonary inflammation. The IL-33-ST2 signaling pathway plays a pro-inflammatory role by activating the type 2 inflammatory response, producing type 2 cytokines and chemokines. Elevated levels of IL-33 and ST2 have been observed in chronic pulmonary obstructive disease (COPD). Notably, IL-33 is present in COPD induced by cigarette smoke or acute inflammations. The role of IL-33 in sepsis is becoming increasingly prominent, and understanding its significance in the treatment of sepsis associated with high mortality is critical. In addition to its pro-inflammatory effects, the IL-33-ST2 axis appears to play a role in bacterial clearance and tissue repair. In this review, we focused on the role of the IL-33-ST2 axis in sepsis, asthma, and COPD and summarized the therapeutic targets associated with this axis, providing a basis for future treatment.

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.

Soluble suppression of tumorigenicity-2 in pregnancy with a small-for-gestational-age fetus and with preeclampsia

OBJECTIVE

Preeclampsia and fetal growth disorders are pregnancy-specific conditions that share common pathophysiological mechanisms. Yet, why some patients develop preeclampsia while others experience fetal growth restriction, or a combination of both clinical presentations, is unknown. We propose that the difference in severity of the maternal inflammatory response can contribute to the clinical phenotypes of preeclampsia vs. small for gestational age (SGA). To assess this hypothesis, we measured maternal plasma concentrations of the soluble isoform of suppression of tumorigenicity-2 (sST2), a member of the interleukin-1 receptor family that buffers proinflammatory responses. Previous reports showed that serum sST2 concentrations rise in the presence of intravascular inflammation and Th1-type immune responses and are significantly higher in patients with preeclampsia compared to those with normal pregnancy. The behavior of sST2 in pregnancies complicated by SGA has not been reported. This study was conducted to compare sST2 plasma concentrations in normal pregnancies, in those with preeclampsia, and in those with an SGA fetus.

METHODS

This retrospective cross-sectional study included women with an SGA fetus (n = 52), women with preeclampsia (n = 106), and those with normal pregnancy (n = 131). Maternal plasma concentrations of sST2 were determined by enzyme-linked immunosorbent assay. Doppler velocimetry of the uterine and umbilical arteries was available in a subset of patients with SGA (42 patients and 43 patients, respectively).

RESULTS

(1) Women with an SGA fetus had a significantly higher median plasma concentration of sST2 than normal pregnant women (p = .008); (2) women with preeclampsia had a significantly higher median plasma concentration of sST2 than those with normal pregnancy (p < .001) and those with an SGA fetus (p < .001); (3) patients with SGA and abnormal uterine artery Doppler velocimetry had a higher median plasma concentration of sST2 than controls (p < .01) and those with SGA and normal uterine artery Doppler velocimetry (p = .02); (4) there was no significant difference in the median plasma sST2 concentration between patients with SGA who had normal uterine artery Doppler velocimetry and controls (p = .4); (5) among patients with SGA, those with abnormal and those with normal umbilical artery Doppler velocimetry had higher median plasma sST2 concentrations than controls (p = .001 and p = .02, respectively); and (6) there was no significant difference in the median plasma sST2 concentrations between patients with SGA who did and those who did not have abnormal umbilical artery Doppler velocimetry (p = .06).

CONCLUSIONS

Preeclampsia and disorders of fetal growth are conditions characterized by intravascular inflammation, as reflected by maternal plasma concentrations of sST2. The severity of intravascular inflammation is highest in patients with preeclampsia.

The immune suppressive properties of damage associated molecular patterns in the setting of sterile traumatic injury

Associated with the development of hospital-acquired infections, major traumatic injury results in an immediate and persistent state of systemic immunosuppression, yet the underlying mechanisms are poorly understood. Detected in the circulation in the minutes, days and weeks following injury, damage associated molecular patterns (DAMPs) are a heterogeneous collection of proteins, lipids and DNA renowned for initiating the systemic inflammatory response syndrome. Suggesting additional immunomodulatory roles in the post-trauma immune response, data are emerging implicating DAMPs as potential mediators of post-trauma immune suppression. Discussing the results of in vitro, in vivo and ex vivo studies, the purpose of this review is to summarise the emerging immune tolerising properties of cytosolic, nuclear and mitochondrial-derived DAMPs. Direct inhibition of neutrophil antimicrobial activities, the induction of endotoxin tolerance in monocytes and macrophages, and the recruitment, activation and expansion of myeloid derived suppressor cells and regulatory T cells are examples of some of the immune suppressive properties assigned to DAMPs so far. Crucially, with studies identifying the molecular mechanisms by which DAMPs promote immune suppression, therapeutic strategies that prevent and/or reverse DAMP-induced immunosuppression have been proposed. Approaches currently under consideration include the use of synthetic polymers, or the delivery of plasma proteins, to scavenge circulating DAMPs, or to treat critically-injured patients with antagonists of DAMP receptors. However, as DAMPs share signalling pathways with pathogen associated molecular patterns, and pro-inflammatory responses are essential for tissue regeneration, these approaches need to be carefully considered in order to ensure that modulating DAMP levels and/or their interaction with immune cells does not negatively impact upon anti-microbial defence and the physiological responses of tissue repair and wound healing.

Evaluation of IL-33R and Galectin-3 as New Biomarkers of Cardiac Damage after Polytrauma-Association with Cardiac Comorbidities and Risk Factors

Polytrauma is one of the disorders with the greatest economic impact on healthcare in society and one predictor for poor outcome is cardiac damage. Interleukin 33 receptors (IL-33R) and galectin-3 are two new potential cardiac trauma biomarkers that are the subjects of this investigation. Additionally, this study assesses pre-existing cardiac damage or risk factors as predictors of cardiac damage after polytrauma. This retrospective study includes 107 polytraumatized patients with an ISS ≥16 admitted in a Level 1 Trauma Centre. Plasma samples were taken at admission. IL-33R and galectin-3 concentrations were detected in plasma samples by ELISA. Both did not correlate with the cardiac damage measured by troponin. Next to troponin, IL-33R was increased in patients with pre-existing cardiac comorbidities. In the subgroup of patients with cardiac comorbidities, the BMI and the initial blood sugar level were significantly increased compared to patients without cardiac comorbidities. Galectin-3 and IL-33R were shown to not correlate with cardiac damage. However, our data suggests that IL-33R protein should be revised in future studies as a marker of cardiac comorbidities. Further, our data indicate that patients with cardiac comorbidities represent a separate group of polytrauma patients characterized by higher concentrations of troponin, IL-33R, BMI and initial sugar level.

Increased expression of IL1-RL1 is associated with type 2 and type 1 immune pathways in asthma

Background

Asthma is a common chronic airway disease in the world. The purpose of this study was to explore the expression of IL1-RL1 in sputum and its correlation with Th1 and Th2 cytokines in asthma.

Methods

We recruited 132 subjects, detected IL1-RL1 protein level in sputum supernatant by ELISA, and analyzed the correlation between the expression level of IL1-RL1 and fraction of exhaled nitric oxide (FeNO), IgE, peripheral blood eosinophil count (EOS#), and Th2 cytokines (IL-4, IL-5, IL-10, IL-13, IL-33 and TSLP) and Th1 cytokines (IFN-γ, IL-2, IL-8). The diagnostic value of IL1-RL1 was evaluated by ROC curve. The expression of IL1-RL1 was further confirmed by BEAS-2B cell in vitro.

Results

Compared with the healthy control group, the expression of IL1-RL1 in sputum supernatant, sputum cells and serum of patients with asthma increased. The AUC of ROC curve of IL1-RL1 in sputum supernatant and serum were 0.6840 (p = 0.0034), and 0.7009 (p = 0.0233), respectively. IL1-RL1 was positively correlated with FeNO, IgE, EOS#, Th2 cytokines (IL-4, IL-5, IL-10, IL-13, IL-33 and TSLP) and Th1 cytokines (IFN-γ, IL-2, IL-8) in induced sputum supernatant. Four weeks after inhaled glucocorticoids (ICS) treatment, the expression of IL1-RL1 in sputum supernatant and serum was increased. In vitro, the expression of IL1-RL1 in BEAS-2B was increased after stimulated by IL-4 or IL-13 for 24 h.

Conclusion

The expression of IL1-RL1 in sputum supernatant, sputum cells and serum of patients with asthma was increased, and was positively correlated with some inflammatory markers in patients with asthma. IL1-RL1 may be used as a potential biomarker for the diagnosis and treatment of asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00499-z.

Non-Invasive Assessment of Congestion by Cardiovascular and Pulmonary Ultrasound and Biomarkers in Heart Failure

Worsening chronic heart failure (HF) is responsible for recurrent hospitalization and increased mortality risk after discharge, irrespective to the ejection fraction. Symptoms and signs of pulmonary and systemic congestion are the most common cause for hospitalization of acute decompensated HF, as a consequence of increased cardiac filling pressures. The elevated cardiac filling pressures, also called hemodynamic congestion, may precede the occurrence of clinical congestion by days or weeks. Since HF patients often have comorbidities, dyspnoea, the main symptom of HF, may be also caused by respiratory or other illnesses. Recent studies underline the importance of the diagnosis and treatment of hemodynamic congestion before HF symptoms worsen, reducing hospitalization and improving prognosis. In this paper we review the role of integrated evaluation of biomarkers and imaging technics, i.e., echocardiography and pulmonary ultrasound, for the diagnosis, prognosis and treatment of congestion in HF patients.

Suppression of tumorigenicity-2 (ST2) is a promising biomarker in heart transplantation

BACKGROUND

To evaluate the association between donors' and recipients' serum levels of soluble ST2 (sST2) and recipients' outcome after heart transplantation (HT).

METHODS

Blood samples were collected in 50 heart donors before organ procurement and in 50 recipients before HT (D0), a week after HT (D7) and at every first year's endomyocardial biopsy (EMB); sST2 levels were evaluated by ELISA.

RESULTS

Donors who sustained a cardiac arrest, had significantly higher sST2 levels. Recipients on national high emergency waiting list had significantly higher preoperative sST2 levels compared to recipients who did not. Recipients with postoperative sepsis or continuous renal replacement therapy had significantly higher sST2 levels at D7. Recipients who needed a postoperative ECMO for allograft dysfunction had significantly higher sST2 levels in their corresponding donors. Recipients who died during the hospitalization after the transplantation had significantly higher sST2 levels at D7 compared to recipients who did not. No difference was observed in sST2 levels in recipients who had mild allograft rejection and recipient who did not.

CONCLUSIONS

Higher sST2 levels in donors are associated to allograft dysfunction requiring ECMO in recipients; higher postoperative sST2 levels in recipients are associated with in-hospital mortality.

Severity of thermal burn injury is associated with systemic neutrophil activation

Burn injuries elicit a unique and dynamic stress response which can lead to burn injury progression. Though neutrophils represent crucial players in the burn-induced immunological events, the dynamic secretion pattern and systemic levels of neutrophil-derived factors have not been investigated in detail so far. Serum levels of neutrophil elastase (NE), myeloperoxidase (MPO), citrullinated histone H3 (CitH3), and complement factor C3a were quantified in burn victims over 4 weeks post injury. Furthermore, the potential association with mortality, degree of burn injury, and inhalation trauma was evaluated. In addition, leukocyte, platelet, neutrophil, and lymphocyte counts were assessed. Lastly, we analyzed the association of neutrophil-derived factors with clinical severity scoring systems. Serum levels of NE, MPO, CitH3, and C3a were remarkably elevated in burn victims compared to healthy controls. Leukocyte and neutrophil counts were significantly increased on admission day and day 1, while relative lymphocytes were decreased in the first 7 days post burn trauma. Though neutrophil-derived factors did not predict mortality, patients suffering from 3rd degree burn injuries displayed increased CitH3 and NE levels. Accordingly, CitH3 and NE were elevated in cases with higher abbreviated burn severity indices (ABSI). Taken together, our data suggest a role for neutrophil activation and NETosis in burn injuries and burn injury progression. Targeting exacerbated neutrophil activation might represent a new therapeutic option for severe cases of burn injury.

Emerging Functions of IL-33 in Homeostasis and Immunity

Our understanding of the functions of the IL-1 superfamily cytokine and damage-associated molecular pattern IL-33 continues to evolve with our understanding of homeostasis and immunity. The early findings that IL-33 is a potent driver of type 2 immune responses promoting parasite expulsion, but also inflammatory diseases like allergy and asthma, have been further supported. Yet, as the importance of a type 2 response in tissue repair and homeostasis has emerged, so has the fundamental importance of IL-33 to these processes. In this review, we outline an evolving understanding of IL-33 immunobiology, paying particular attention to how IL-33 directs a network of ST2+ regulatory T cells, reparative and regulatory macrophages, and type 2 innate lymphoid cells that are fundamental to tissue development, homeostasis, and repair.

Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Clinical Relevance of Elevated Soluble ST2, HSP27 and 20S Proteasome at Hospital Admission in Patients with COVID-19

Although, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents one of the biggest challenges in the world today, the exact immunopathogenic mechanism that leads to severe or critical Coronavirus Disease 2019 (COVID-19) has remained incompletely understood. Several studies have indicated that high systemic plasma levels of inflammatory cytokines result in the so-called "cytokine storm", with subsequent development of microthrombosis, disseminated intravascular coagulation, and multiorgan-failure. Therefore, we reasoned those elevated inflammatory molecules might act as prognostic factors. Here, we analyzed 245 serum samples of patients with COVID-19, collected at hospital admission. We assessed the levels of heat shock protein 27 (HSP27), soluble suppressor of tumorigenicity-2 (sST2) and 20S proteasome at hospital admission and explored their associations with overall-, 30-, 60-, 90-day- and in-hospital mortality. Moreover, we investigated their association with the risk of ventilation. We demonstrated that increased serum sST2 was uni- and multivariably associated with all endpoints. Furthermore, we also identified 20S proteasome as independent prognostic factor for in-hospital mortality (sST2, AUC = 0.73; HSP27, AUC = 0.59; 20S proteasome = 0.67). Elevated sST2, HSP27, and 20S proteasome levels at hospital admission were univariably associated with higher risk of invasive ventilation (OR = 1.8; p < 0.001; OR = 1.1; p = 0.04; OR = 1.03, p = 0.03, respectively). These findings could help to identify high-risk patients early in the course of COVID-19.

Soluble suppression of tumorigenicity 2 as outcome predictor after cardiopulmonary resuscitation: an observational prospective study

Prognostication after cardiopulmonary resuscitation (CPR) is complex. Novel biomarkers like soluble suppression of tumorigenicity 2 (sST2) may provide an objective approach. A total of 106 post-CPR patients were included in this single-center observational prospective study. Serum sST2 levels were obtained 24 h after admission. Individuals were assigned to two groups: patients below and above the overall cohort’s median sST2 concentration. Primary outcome was a combined endpoint at 6 months (death or Cerebral Performance Category > 2); secondary endpoint 30-day mortality. A uni- and multivariate logistic regression analysis were conducted. Elevated sST2-levels were associated with an increased risk for the primary outcome (OR 1.011, 95% CI 1.004–1.019, p = 0.004), yet no patients with poor neurological outcome were observed at 6 months. The optimal empirical cut-off for sST2 was 46.15 ng/ml (sensitivity 81%, specificity 53%, AUC 0.69). Levels above the median (> 53.42 ng/ml) were associated with higher odds for both endpoints (death or CPC > 2 after 6 months: 21% vs. 49%, OR 3.59, 95% CI 1.53–8.45, p = 0.003; death after 30 days: 17% vs. 43.3%, OR 3.75, 95% CI 1.52–9.21, p = 0.003). A positive correlation of serum sST2 after CPR with mortality at 30 days and 6 months after cardiac arrest could be demonstrated.

Randomised controlled trial into the role of ramipril in fibrosis reduction in rheumatic heart disease: the RamiRHeD trial protocol

INTRODUCTION

Rheumatic heart disease (RHD) is a major burden in developing countries and accounts for 80% of all people living with the disease, where it causes most cardiovascular morbidity and mortality in children and young adults. Chronic inflammation and fibrosis of heart valve tissue due to chronic inflammation in RHD will cause calcification and thickening of the impacted heart valves, especially the mitral valve. This fibrogenesis is enhanced by the production of angiotensin II by increased transforming growth factor β expression and later by the binding of interleukin-33, which is known to have antihypertrophic and antifibrotic effects, to soluble sST2. sST2 binding to this non-natural ligand worsens fibrosis. Therefore, we hypothesise that ACE inhibitors (ACEIs) would improve rheumatic mitral valve stenosis.

METHODS AND ANALYSIS

This is a single-centre, double-blind, placebo-controlled, randomised clinical trial with a pre-post test design. Patients with rheumatic mitral stenosis and valve dysfunction will be planned for cardiac valve replacement operation and will be given ramipril 5 mg or placebo for a minimum of 12 weeks before the surgery. The expression of ST2 in the mitral valve is considered to be representative of cardiac fibrosis. Mitral valve tissue will be stained by immunohistochemistry to ST2. Plasma ST2 will be measured by ELISA. This study is conducted in the Department of Cardiology and Vascular Medicine, Universitas Indonesia, National Cardiac Center Harapan Kita Hospital, Jakarta, Indonesia, starting on 27 June 2019.

ETHICS AND DISSEMINATION

The performance and dissemination of this study were approved by the ethics committee of National Cardiovascular Center Harapan Kita with ethical code LB.02.01/VII/286/KEP.009/2018.

TRIAL REGISTRATION NUMBER

NCT03991910.

Heart failure risk estimation based on novel biomarkers

Introduction: Despite advances in medical care, heart failure (HF)-associated morbidity and mortality remains high. Consequently, there is increased effort to find better ways for predicting, screening, and prognosticating HF in order to facilitate effective primary and secondary prevention.Areas covered: In this review, we describe the various biomarkers associated with different etiologic pathways implicated in HF, and discuss their roles in screening, diagnosing, prognosticating and predicting HF. We explore the emerging role of multi-omic approaches. We performed electronic searches in databases (PubMed and Google Scholar) through December 2020, using the following key terms: biomarker, novel, heart failure, risk, prediction, and estimation.Circulating BNP and troponin concentrations have been established in clinical care as key biomarkers for diagnosing and prognosticating HF. Emerging biomarkers (such as galectin-3 and ST-2) have gained further recognition for use in evaluating prognosis of HF patients. Promising biomarkers that are yet to be part of clinical recommendations include biomarkers of cardiorenal disease.Expert opinion: Increasing recognition of the complex and interdependent nature of pathophysiological pathways of HF has led to the application of multi-marker approaches including multi-omic high throughput assays. These newer approaches have the potential for new therapeutic discoveries and improving precision medicine in HF.

Inflammatory immune response in recipients of transcatheter aortic valves

Objective

Transcatheter aortic valve implantation (TAVI) is rapidly replacing cardiac surgery due to its minimal invasiveness and practicality. Midterm immunological studies on the biocompatibility of galactose-alpha-1,3-galactose (α-Gal)–carrying bioprosthetic heart valves for TAVI are not available. In this study we investigated whether bioprosthetic heart valves employed for TAVI augment an α-Gal–specific antibody-dependent and antibody-independent immune response 3 months after TAVI implantation.

Methods

This prospective observational study included 27 patients with severe aortic valve stenosis undergoing TAVI and 10 patients with severe mitral valve regurgitation treated with a transcatheter MitraClip (Abbott Laboratories, Abbott Park, Ill) procedure. Blood samples were drawn before and 90 days after treatment at a routine checkup. Serum samples were analyzed using enzyme-linked immunosorbent assay. Serum concentrations of α-Gal–specific immunoglobulin (Ig) G, IgG subclasses and IgE, complement factor 3a, NETosis-specific citrullinated H3, and the systemic inflammation markers soluble suppression of tumorigenicity and interleukin 33 were evaluated.

Results

Three months after TAVI, we found significantly increased serum concentrations of α-Gal–specific IgG3, complement factor complement factor 3a, citrullinated H3 levels, and soluble suppression of tumorigenicity (P = .002, P = .001, P = .025, and P = .039, respectively). Sensitization of α-Gal–specific IgE antibodies occurred in 55% of all patients after TAVI.

Conclusions

Our results indicate that TAVI elicits a midterm, specific humoral immune response against α-Gal and causes an unspecific humoral inflammation compared with patients undergoing MitraClip implantation. This observation will lead to a better understanding of postintervention morbidity and the long-term durability of bioprostheses and indicates that caution is appropriate when designing implantation strategies for younger patients.

Rapid systemic surge of IL-33 after severe human trauma: a prospective observational study

Background

Alarmins are considered proximal mediators of the immune response after tissue injury. Understanding their biology could pave the way for development of new therapeutic targets and biomarkers in human disease, including multiple trauma. In this study we explored high-resolution concentration kinetics of the alarmin interleukin-33 (IL-33) early after human trauma.

Methods

Plasma samples were serially collected from 136 trauma patients immediately after hospital admission, 2, 4, 6, and 8 h thereafter, and every morning in the ICU. Levels of IL-33 and its decoy receptor sST2 were measured by immunoassays.

Results

We observed a rapid and transient surge of IL-33 in a subset of critically injured patients. These patients had more widespread tissue injuries and a greater degree of early coagulopathy. IL-33 half-life (t_1/2) was 1.4 h (95% CI 1.2–1.6). sST2 displayed a distinctly different pattern with low initial levels but massive increase at later time points.

Conclusions

We describe for the first time early high-resolution IL-33 concentration kinetics in individual patients after trauma and correlate systemic IL-33 release to clinical data. These findings provide insight into a potentially important axis of danger signaling in humans.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00288-1.

Early sST2 Liberation after Implantation of a Left Ventricular Assist Device in Patients with Advanced Heart Failure

Background

The use of left ventricular assist device (LVAD) has increased considerably over the past decade; however, there is limited literature to assist in patient selection and monitoring. The frequency of adverse events remains high. We examined the early expression of circulating soluble ST2 (sST2), a biomarker with immunosuppressive and profibrotic activity, and assessed the risk of death at 1 year in patients receiving LVAD implant.

Methods

We prospectively enrolled 20 heart failure patients and measured sST2, IL-33, and IL-6 serum concentrations over three weeks after LVAD implantation. We compared the kinetics of IL-6, sST2, and IL-33 release in survivors with those of nonsurvivors using mixed model two-way analysis of variance for repeated measures. We also collected data on hemodynamic parameters (i.e., cardiac output) and frequency of infections during the hospital stay.

Results

LVAD therapy led to an immediate and significant improvement of the hemodynamic parameters in 1-year survivors and nonsurvivors alike. The 1-year survival rate was 65%. IL-6 concentrations showed a significant (p = 0.03) peak at admission to the intensive care unit following LVAD implantation, whereas sST2 levels were massively increased (p < 0.0003) on day 1. While 1-year survivors had persistently lower sST2 values compared to nonsurvivors during the first 3 weeks after LVAD implantation (p = 0.012), no differences were observed in the temporal pattern of IL-6 or IL-33. The odds of detecting Candida species in the bronchoalveolar lavage fluid were 14 times higher in nonsurvivors than in survivors (OR 13.7, CI 1.4-127, p = 0.02).

Conclusion

In patients implanted with LVAD, circulating sST2 levels and frequency of Candida colonisation were associated with higher mortality. Awareness of this early immune response can guide physicians in risk-benefit analysis.

Metal-induced bacterial interactions promote diversity in river-sediment microbiomes

Anthropogenic metal contamination results in long-term environmental selective pressure with unclear impacts on bacterial communities, which comprise key players in ecosystem functioning. Since metal contamination poses serious toxicity and bioaccumulation issues, assessing their impact on environmental microbiomes is important to respond to current environmental and health issues. Despite elevated metal concentrations, the river sedimentary microbiome near the MetalEurop foundry (France) shows unexpected higher diversity compared with the upstream control site. In this work, a follow-up of the microbial community assembly during a metal contamination event was performed in microcosms with periodic renewal of the supernatant river water. Sediments of the control site were gradually exposed to a mixture of metals (Cd, Cu, Pb and Zn) in order to reach similar concentrations to MetalEurop sediments. Illumina sequencing of 16S rRNA gene amplicons was performed. Metal-resistant genes, czcA and pbrA, as well as IncP plasmid content, were assessed by quantitative PCR. The outcomes of this study support previous in situ observations showing that metals act as community assembly managers, increasing diversity. This work revealed progressive adaptation of the sediment microbiome through the selection of different metal-resistant mechanisms and cross-species interactions involving public good-providing bacteria co-occurring with the rest of the community.

Soluble suppression of tumorigenicity-2 predicts pneumonia in patients with inhalation injury: Results of a pilot study

INTRODUCTION

Several mechanisms play a role in the development of pneumonia after inhalation injury. Our aim was to analyze whether higher concentrations of inflammatory markers or of biomarkers of epithelial injury are associated with a higher incidence of pneumonia in patients with inhalation injury.

MATERIAL AND METHODS

Secondary analysis of a single-center prospective observational cohort pilot study, performed over a two-year period (2015-2017) at the Burns Unit of the Plastic and Reconstructive Surgery Department of Vall d'Hebron University Hospital. All patients aged 18 with suspected inhalation injury undergoing admission to the Burns Unit were included. Plasma biomarkers of the lung epithelium (RAGE and SP-D), inflammation markers (IL6, IL8), and IL33, as well as soluble suppression of tumorigenicity-2 (sST2) levels, were measured within the first 24 h of admission.

RESULTS

Twenty-four patients with inhalation injury were included. Eight (33.3%) developed pneumonia after a median of 7 (4-8) days of hospital stay. Patients with pneumonia presented higher plasma concentrations of sST2 (2853 [2356-3351] ng/mL vs 1352 [865-1839] ng/mL; p < 0.001), IL33 (1.95 [1.31-2.59] pg/mL vs 1.26 [1.07-1.45] pg/mL; p = 0.002) and IL8 (325.7 [221.6-430.0] pg/mL vs 174.1 [95.2-253.0] pg/mL; p = 0.017) on day 1 of inclusion. Plasma sST2 concentration in the first 24 h demonstrated excellent diagnostic accuracy for predicting the occurrence of pneumonia in patients with smoke inhalation (AUROC 0.929 [95%CI 0.818-1.000]). A cutoff point of ≥2825 ng/mL for sST2 had a sensitivity of 75% and a specificity of 100%. The risk ratio of pneumonia in patients with sST2 ≥ 2825 ng/mL was 7.14 ([95% CI 1.56-32.61]; p = 0.016).

CONCLUSIONS

Plasma sST2 in the first 24 h of admission predicts the occurrence of pneumonia in patients with inhalation injury.

Antibody Production in Murine Polymicrobial Sepsis-Kinetics and Key Players

Although antigen-specific priming of antibody responses is impaired during sepsis, there is nevertheless a strong increase in IgM and IgG serum concentrations. Using colon ascendens stent peritonitis (CASP), a mouse model of polymicrobial abdominal sepsis, we observed substantial increases in IgM as well as IgG of all subclasses, starting at day 3 and peaking 2 weeks after sepsis induction. The dominant source of antibody-secreting cells was by far the spleen, with a minor contribution of the mesenteric lymph nodes. Remarkably, sepsis induction in splenectomized mice did not change the dynamics of the serum IgM/IgG reaction, indicating that the marginal zone B cells, which almost exclusively reside in the spleen, are dispensable in such a setting. Hence, in systemic bacterial infection, the function of the spleen as dominant niche of antibody-producing cells can be compensated by extra-splenic B cell populations as well as other lymphoid organs. Depletion of CD4+ T cells did not affect the IgM response, while it impaired IgG generation of all subclasses with the exception of IgG3. Taken together, our data demonstrate that the robust class-switched antibody response in sepsis encompasses both T cell-dependent and -independent components.

Soluble ST2: A complex and diverse role in several diseases

The Suppression of Tumorigenicity 2 protein (ST2) is a member of the interleukin (IL) 1 receptor family with transmembrane (ST2L) and soluble (sST2) isoforms that are (over)expressed in several cells in different conditions and following various triggers (e.g. inflammation, stress). The ligand of ST2 is IL-33, which on binding to ST2L results in nuclear signalling and immunomodulatory action in various cells (tumour, immune, heart). sST2, that is released in the circulation, functions as a »decoy« receptor of IL-33 and inhibits IL-33/ST2L signalling and beneficial effects. The importance and role of the ST2/IL-33 axis and sST2 have been evaluated and confirmed in several inflammatory, cancer and cardiac diseases. sST2 is involved in homeostasis/pathogenesis of these diseases, as the counterbalance/response on IL-33/ST2L axis activation, which is triggered and expressed during developing fibrosis, tissue damage/inflammation and remodelling. In clinical studies, sST2 has been recognised as an important prognostic marker in patients with cardiac disease, including patients with chronic kidney disease where specific characteristics of sST2 enable better assessment of the risk of End-Stage Renal Disease patients on dialysis. sST2 is also recognised as an important marker for monitoring treatment in heart failure patients. However, accurate measurement and interpretation of ST2 concentration in serum/plasma samples for routine and research applications require the use of appropriate methods and recognition of essential characteristics of both the methods and the analyte that may influence the result. sST2, as one of the most promising disease biomarkers, is deserving of further study and wider application in clinical practice.

Suppression of Tumourigenicity 2 in Heart Failure With Preserved Ejection Fraction

Heart failure (HF), with steadily increasing incidence rates and mortality in an ageing population, represents a major challenge. Evidence suggests that more than half of all patients with a diagnosis of HF suffer from HF with preserved ejection fraction (HFpEF). Emerging novel biomarkers to improve and potentially guide the treatment of HFpEF are the subject of discussion. One of these biomarkers is suppression of tumourigenicity 2 (ST2), a member of the interleukin (IL)-1 receptor family, binding to IL-33. Its two main isoforms – soluble ST2 (sST2) and transmembrane ST2 (ST2L) – show opposite effects in cardiovascular diseases. While the ST2L/IL-33 interaction is considered as being cardioprotective, sST2 antagonises this beneficial effect by competing for binding to IL-33. Recent studies show that elevated levels of sST2 are associated with increased mortality in HF with reduced ejection fraction. Nevertheless, the significance of sST2 in HFpEF remains uncertain. This article aims to give an overview of the current evidence on sST2 in HFpEF with an emphasis on prognostic value, clinical association and interaction with HF treatment. The authors conclude that sST2 is a promising biomarker in HFpEF. However, further research is needed to fully understand underlying mechanisms and ultimately assess its full value.

Soluble Suppression of Tumorigenicity 2 is Directly Correlated with Glycated Hemoglobin in Individuals with an Average glycemia in the Normal/Prediabetes Range

PURPOSE

Cardiovascular disease can be detected in individuals with prediabetes. The purpose of this study was to determine whether soluble suppression of tumorigenicity 2 (sST2), which is elevated in cardiovascular disease and/or type 2 diabetes, is correlated with glycated haemoglobin in individuals with glycemia in the normal/prediabetes range.

PATIENTS AND METHODS

The anthropometric, biochemical and metabolic parameters were measured in 30 adults, and the plasma levels of sST2 were quantified.

RESULTS

sST2 was directly correlated with glycated hemoglobin in individuals with glycemia in the normal/prediabetes range. Participants who were at the higher end of glycated hemoglobin (5.8-6.4%) had significantly higher sST2 compared to those at the lower end (≤5.5%). Moreover, sST2 was directly correlated with homeostatic model assessment of insulin resistance (HOMA-IR), alkaline phosphatase, and waist circumference. However, the correlation between sST2 and HOMA-IR or waist circumference was lost after adjusting for age, gender or body mass index.

CONCLUSION

Circulating sST2 may be used to establish a cut-off value for cardiometabolic risk/disease in individuals with glycemia in the normal/prediabetes range.

[Soluble ST2 - as a biomarker, a tool for risk stratification and therapeutic target in patients with chronic heart failure]

This review focuses on possibilities of using soluble ST2 as a HF marker for diagnostics, stratification of risk of adverse events, and for evaluation of prognosis and treatment effectiveness in patients with CHF. Circulating biomarkers are an essential element of algorithms for diagnostics, stratification of risk, and evaluation of prognosis in patients with HF. The recognized "gold standard", natriuretic peptides, has several well-known limitations, and multiple new candidate biomarkers have appeared in recent years. Soluble ST2, a marker of "mechanical myocardial stress", is considered as one of the most promising new biomarkers. This review discusses possibilities of using it in clinical practice in CHF patients.

[Soluble ST2 - biomarker for prognosis and monitoring in decompensated heart failure]

The review aims to appraise the value of determining the concentrations of the new biomarker sST2 for assessing prognosis and monitoring treatment effectiveness of patients with decompensated heart failure during an episode of decompensation and during long-term follow-up after discharge from the hospital. The article analyses in detail the expedience of sST2 measurement in a patient with ADHF on admission and discharge from the hospital and the changes in the biomarker level during the period of active treatment for risk-stratification in patients, presents the optimal threshold values of sST2, which should be oriented when selecting patients with high and very high risk. The importance of subsequent monitoring of the marker concentration during long-term observation in emphasized to predict the risk of death, HF re-decompensation / HF rehospitalization. The potential benefits of choosing sST2 as the optimal marker for serial measurement during long-term follow-up, as well as evaluating the treatment effectiveness in patients with HF, compared to the "classical" variant - natriuretic peptides are shown.

Biomarkers and Donor Selection in Heart Transplantation

BACKGROUND

Previously, we showed that B-type natriuretic peptide (BNP) measured in the donor was related to cardiac performance after cardiac transplantation. The present study assesses the value of 3 biomarkers in the selection of donor hearts in a larger cohort.

METHODS

Blood samples were prospectively obtained in 105 brain-dead patients scheduled for heart donation. BNP, soluble suppressor of tumorigenicity 2 (ST2), and troponin of heart donors were correlated with hemodynamic parameters early after transplantation as well as with the mortality of the recipients.

RESULTS

A significant inverse relationship was found between donor BNP measured at the time of donation and recipient cardiac index and cardiac output at day 13 post-transplantation (r = -0.31, P = .005, and r = -0.34, P = .0016, respectively). Logistic regression analysis-including BNP, ST2, and troponin-showed that donor BNP was a predictor of a poor cardiac index (< 2.2 L/min/m²) in the recipient (P = .04). A donor BNP > 132 pg/mL has a sensitivity of 56% (95% confidence interval 21-86) and a specificity of 86% (95% confidence interval 77-93) to predict poor cardiac performance in the recipient. When the donor BNP is ≤ 132 pg/mL, the risk of a poor cardiac function in the recipient is very low (negative predictive value 94%). Mortality at 30 days was also correlated to donor BNP (r = 0.29, P = .0029). Long-term survival of the recipient was not correlated to the biomarkers measured in the donor.

CONCLUSION

Donor BNP, but not donor ST2 or high-sensitivity troponin, provides information on the donor heart and early post-transplant performance, including 1-month mortality.

Elevations in Circulating sST2 Levels Are Associated With In-Hospital Mortality and Adverse Clinical Outcomes After Blunt Trauma

BACKGROUND

Soluble suppression of tumorigenicity 2 (sST2), a decoy receptor for interleukin (IL)-33, has emerged as a novel biomarker in various disease processes. Recent studies have elucidated the role of the sST2/IL-33 complex in modulating the balance of Th1/Th2 immune responses after tissue stress. However, the role of sST2 as a biomarker after traumatic injury remains unclear. To address this, we evaluated serum sST2 correlations with mortality and in-hospital adverse outcomes as endpoints in blunt trauma patients.

METHODS

We retrospectively analyzed clinical and biobank data of 493 blunt trauma victims 472 survivors (mean age: 48.4 ± 0.87; injury severity score [ISS]: 19.6 ± 0.48) and 19 nonsurvivors (mean age: 58.8 ± 4.5; ISS: 23.3 ± 2.1) admitted to the intensive care unit. Given the confounding impact of age on the inflammatory response, we derived a propensity-matched survivor subgroup (n = 19; mean age: 59 ± 3; ISS: 23.4 ± 2) using an IBM SPSS case-control matching algorithm. Serial blood samples were obtained from all patients (3 samples within the first 24 h and then once daily from day [D] 1 to D5 after injury). sST2 and twenty-nine inflammatory biomarkers were assayed using enzyme-linked immunosorbent assay and Luminex, respectively. Two-way analysis of variance on ranks was used to compare groups (P < 0.05). Spearman rank correlation was performed to determine the association of circulating sST2 levels with biomarker levels and in-hospital clinical outcomes.

RESULTS

Circulating sST2 levels of the nonsurvivor cohort were statistically significantly elevated at 12 h after injury and remained elevated up to D5 when compared either to the overall 472 survivor cohort or a matched 19 survivor subcohort. Admission sST2 levels obtained from the first blood draw after injury in the survivor cohort correlated positively with admission base deficit (correlation coefficient [CC] = 0.1; P = 0.02), international normalized ratio (CC = 0.1, P = 0.03), ISS (CC = 0.1, P = 0.008), and the average Marshall multiple organ dysfunction score between D2 and D5 (CC = 0.1, P = 0.04). Correlations with ISS revealed a positive correlation of ISS with plasma sST2 levels across the mild ISS (CC = 0.47, P < 0.001), moderate ISS (CC = 0.58, P < 0.001), and severe ISS groups (CC = 0.63, P < 0.001). Analysis of biomarker correlations in the matched survivor group over the initial 24 h after injury showed that sST2 correlates strongly and positively with IL-4 (CC = 0.65, P = 0.002), IL-5 (CC = 0.57, P = 0.01), IL-21 (CC = 0.52, P = 0.02), IL-2 (CC = 0.51, P = 0.02), soluble IL-2 receptor-α (CC = 0.5, P = 0.02), IL-13 (CC = 0.49, P = 0.02), and IL-17A (CC = 0.48, P = 0.03). This was not seen in the matched nonsurvivor group. sST2/IL-33 ratios were significantly elevated in nonsurvivors and patients with severe injury based on ISS ≥ 25.

CONCLUSIONS

Elevations in serum sST2 levels are associated with poor clinical trajectories and mortality after blunt trauma. High sST2 coupled with low IL-33 associates with severe injury, mortality, and worse clinical outcomes. These findings suggest that sST2 could serve as an early prognostic biomarker in trauma patients and that sustained elevations of sST2 could contribute to a detrimental suppression of IL-33 bioavailability in patients with high injury severity.

IL-33 drives group 2 innate lymphoid cell-mediated protection during Clostridium difficile infection

Clostridium difficile (C. difficile) incidence has tripled over the past 15 years and is attributed to the emergence of hypervirulent strains. While it is clear that C. difficile toxins cause damaging colonic inflammation, the immune mechanisms protecting from tissue damage require further investigation. Through a transcriptome analysis, we identify IL-33 as an immune target upregulated in response to hypervirulent C. difficile. We demonstrate that IL-33 prevents C. difficile-associated mortality and epithelial disruption independently of bacterial burden or toxin expression. IL-33 drives colonic group 2 innate lymphoid cell (ILC2) activation during infection and IL-33 activated ILC2s are sufficient to prevent disease. Furthermore, intestinal IL-33 expression is regulated by the microbiota as fecal microbiota transplantation (FMT) rescues antibiotic-associated depletion of IL-33. Lastly, dysregulated IL-33 signaling via the decoy receptor, sST2, predicts C. difficile-associated mortality in human patients. Thus, IL-33 signaling to ILC2s is an important mechanism of defense from C. difficile colitis.

Here, Frisbee et al. show that hypervirulent Clostridium difficile induces IL-33 expression in the gut and IL-33 reduces mortality and morbidity via group 2 innate lymphoid cells. Furthermore, serum levels of the soluble IL-33 decoy receptor, sST2, are associated with enhanced disease severity in human C. difficile patients.

Structural Basis of IL-1 Family Cytokine Signaling

Interleukin-1 (IL-1) family cytokines are key signaling molecules in both the innate and adaptive immune systems, mediating inflammation in response to a wide range of stimuli. The basic mechanism of signal initiation is a stepwise process in which an agonist cytokine binds its cognate receptor. Together, this cytokine-receptor complex recruits an often-common secondary receptor. Intracellularly, the Toll/IL-1 Receptor (TIR) domains of the two receptors are brought into close proximity, initiating an NF-κB signal transduction cascade. Due to the potent inflammatory response invoked by IL-1 family cytokines, several physiological mechanisms exist to inhibit IL-1 family signaling, including antagonist cytokines and decoy receptors. The numerous cytokines and receptors in the IL-1 superfamily are further classified into four subfamilies, dependent on their distinct cognate receptors—the IL-1, IL-33, and IL-36 subfamilies share IL-1RAcP as their secondary receptor, while IL-18 subfamily utilizes a distinct secondary receptor. Here, we describe how structural biology has informed our understanding of IL-1 family cytokine signaling, with a particular focus on molecular mechanisms of signaling complex formation and antagonism at the atomic level, as well as how these findings have advanced therapeutics to treat some chronic inflammatory diseases that are the result of dysregulated IL-1 signaling.

Recent advances in the biology of IL-1 family cytokines and their potential roles in development of sepsis

The IL-1 family comprises two anti-inflammatory cytokines (IL-37, IL-38), two receptor antagonists (IL-1ra, IL-36ra), and seven ligand agonists (IL-1α, IL-1β, IL-33, IL-36α, IL-36β, IL-36γ). The members of this family exert pleiotropic effects on intercellular signaling, leading to pro- or anti-inflammatory responses. They initiate potent inflammatory and immune responses by binding to specific receptors in the IL-1 receptor family, and their activities are repressed by naturally occurring inhibitors. Various immune cells produce and are regulated by these crucial molecules, which appear to be involved in the pathogenesis of diverse diseases including cancer as well as inflammatory and autoimmune disorders. Recent decades have seen substantial progress in understanding how the IL-1 family contributes to the development of sepsis. In this review, we will briefly introduce the IL-1 family and discuss its critical role in inflammatory and immune responses. The potential significance of IL-1 members in sepsis will also be explored, together with the clinical implications for treating this dangerous condition.

Prognostic role of soluble ST2 in acute coronary syndrome with diabetes

BACKGROUND

Acute coronary syndrome (ACS) patients are at an increased risk of major adverse cardiovascular events (MACE). The objective of our study was to assess whether cardiac biomarker like soluble ST2 (sST2) can predict MACE among ACS patients with diabetes.

MATERIALS AND METHODS

A total of 122 patients with ACS were included in the study. sST2 level in blood plasma samples was quantified using enzyme-linked immunosorbent assay (ELISA). Prognostic utility of sST2 for the primary outcome of MACE which included mortality, rehospitalization due to chest pain, unstable angina, recurrent myocardial infarction (MI) and stroke, was assessed during follow-up.

RESULTS

The median follow-up period was of 180 days. ROC (receiver operating characteristic) curve demonstrated that elevated levels of sST2 were able to predict mortality, and MACE in ACS patients, along with increased risk of occurrence of MACE and mortality in ACS patients having diabetes. Kaplan-Meier plots revealed a significant increase in the occurrence of MACE in diabetic ACS patients (P = 0.006; by log-rank test). Cox regression analysis revealed that sST2 is not an independent predictor of mortality and MACE in ACS patients having diabetes; however, high sST2 level was found to be a predictor of MACE in all ACS subjects in the fully adjusted model with a hazard ratio (HR) of 5.8 (P = 0.032).

CONCLUSION

The current study indicates that elevated levels of sST2 might be a suitable biomarker to evaluate the risk of future adverse cardiovascular events in ACS patients with diabetes.

IL-33 receptor (ST2) deficiency downregulates myeloid precursors, inflammatory NK and dendritic cells in early phase of sepsis

BACKGROUND

Sepsis is a life-threatening disease mediated by profound disturbances in systemic inflammatory response to infection. IL-33 is multifunctional regulator of numerous aspects of innate and adaptive immune response. The aim of this article was to further evaluate the role of IL-33 receptor (ST2) in different pathways of innate immunity during early polymicrobial sepsis.

METHODS

Polymicrobial sepsis was induced using cecal ligation and puncture (CLP) model in ST2 deficient (ST2-/-) and wild type BALB/c mice. Peritoneal and spleen cells were isolated for further phenotyping. Apoptosis was determined by immunohistochemistry and flow cytometry.

RESULTS

Deletion of ST2 leads to increased susceptibility to early manifestations of sepsis as evaluated by clinical signs and survival. These are accompanied by decrease in the total number of neutrophils, eosinophils and mast cells in peritoneal cavity 12 h after CLP. In early sepsis there was also low number of precursors of myeloid cells in particular CD11b+Ly6G+Ly6Clow cells in spleen of ST2-/- mice. Although the number of NK cells in the spleen was similar, there were significant differences in the presence of inflammatory IFN-γ and IL-17 producing NK cells. Further, ST2 deletion affects the phenotype and maturation of dendritic cell in sepsis. The total number of dendritic cells in the spleen was lower as well as IL-12 expressing dendritic cells. Finally, there was higher frequency of active caspase-3 positive and early apoptotic cells, in particular CD11c positive cells, in spleen of septic ST2-/- mice.

CONCLUSION

Taken together, our data provide the evidence that ST2 deficiency in early phase of sepsis downregulates myeloid precursors, inflammatory NK and dendritic cells.

Soluble ST2 in Heart Failure

Suppression of tumorigenicity 2 (ST2) is a member of the interleukin (IL)-1 receptor family, whose role was originally established in the context of inflammatory and autoimmune diseases. More recently, testing for ST2 has been used in the setting of cardiovascular disease. The soluble form of ST2 is a decoy receptor that inhibits beneficial cardioprotective effects of IL-33; such inhibition results in cardiac hypertrophy, myocardial fibrosis, and ventricular dysfunction. Measurement of soluble ST2 has utility for assessing heart failure severity and prognosis. In this review, we examine the role of soluble ST2 in both acute and chronic heart failure.

IL-33 and Its Receptor ST2 after Inhaled Allergen Challenge in Allergic Asthmatics

BACKGROUND

Previous murine models have demonstrated interleukin (IL)-33 to be an important mediator of type-2 inflammation and to promote airway hyperresponsiveness in allergic asthma. A number of inflammatory cells produce IL-33 and eosinophils express ST2 mRNA. The relationship between IL-33 and eosinophils in allergic asthma, however, remains unclear.

OBJECTIVE

The aim of this work was to evaluate in vitro the effect of allergen inhalation on IL-33 levels and expression of its receptor (ST2L) on eosinophils in allergic asthmatics, and the effect of IL-33 stimulation on eosinophil activity.

METHODS

Plasma and sputum IL-33, soluble ST2 (sST2) levels, and ST2L expression on eosinophils were measured in 10 healthy controls and 10 allergic asthmatics. Asthmatics underwent allergen and diluent inhalation challenges. Blood and sputum samples were collected to measure IL-33, sST2, and ST2L eosinophil expression before and 24 h after allergen inhalation. Purified blood eosinophils from allergic asthmatics were incubated overnight with IL-33 to assess ST2 and intracellular IL-5 expression.

RESULTS

Baseline levels of IL-33 in sputum and sST2 in plasma and sputum were similar in allergic asthmatics compared to healthy controls. In addition, there was no difference in blood or sputum eosinophil ST2L expression in healthy controls versus allergic asthmatics. Eosinophil ST2L expression was significantly increased 24 h postallergen inhalation in allergic asthmatics. In vitro stimulation of human eosinophils with IL-33 and LPS significantly increased eosinophil ST2L expression and IL-33 stimulation increased intracellular IL-5 expression, which was attenuated by treatment with sST2 and ST2 blockade.

CONCLUSION AND CLINICAL RELEVANCE

In mild asthmatics, there was a significant upregulation of ST2 surface expression on eosinophils from blood and sputum following allergen inhalation challenge. In vitro, IL-33 stimulation of eosinophils increases both ST2 membrane expression and IL-5 production. These results support a role for IL-33 in causing allergen-induced eosinophilia. Blockade of IL-33 and ST2 signaling may present a novel therapeutic avenue for asthma treatment.

Adenovirus-mediated overexpression of sST2 attenuates cardiac injury in the rat with severe acute pancreatitis

AIMS

Severe acute pancreatitis (SAP) is a serious disease associated with systematic inflammation and multiple organs dysfunction. Soluble ST2 (sST2), a member of the Toll interleukin (IL)-1 receptor (TIR) superfamily, has been demonstrated to exert immune-regulatory and anti-inflammatory properties in several inflammation-related diseases. In this study, we investigated whether transfer of sST2 gene by adenovirus vector could attenuate sodium taurocholate-induced SAP and associated cardiac injury.

MAIN METHODS

A rat model of SAP was induced by retrograde injection of 5% sodium taurocholate (1 ml/kg) into the biliopancreatic duct. Rats in the treatment groups were intravenously injected with adenovirus expressing sST2 (Ad-sST2, 1 × 10⁹ particles/rat) or green fluorescent protein (Ad-GFP) via the tail vein 48 h before SAP induction. Histological changes in the pancreatic and heart tissues, and parameters for evaluating SAP and associated cardiac injury were determined at 24 h after SAP.

KEY FINDINGS

Sodium taurocholate induced obvious pathological changes in pancreas and elevated serum levels of amylase and lipase. Furthermore, SAP animals exhibited significant cardiac impairment, evidenced by decreased cardiac function, increased myocardial apoptosis and cardiac-related enzymes including creatine kinase isoenzyme, lactate dehydrogenase, and Troponin T. Administration of Ad-sST2 markedly improved the structure of pancreas and heart tissues, and reversed the alterations in serum amylase, lipase and cardiac-related enzymes. In addition, Ad-sST2 treatment downregulated pro-inflammatory cytokines production, demonstrating the anti-inflammatory property of sST2.

SIGNIFICANCE

Our results suggest that administration of Ad-sST2 significantly attenuated the severity of SAP and associated cardiac damage, and the cardioprotective effect is associated with its anti-inflammatory action.

Polymicrobial sepsis and non-specific immunization induce adaptive immunosuppression to a similar degree

Sepsis is frequently complicated by a state of profound immunosuppression, in its extreme form known as immunoparalysis. We have studied the role of the adaptive immune system in the murine acute peritonitis model. To read out adaptive immunosuppression, we primed post-septic and control animals by immunization with the model antigen TNP-ovalbumin in alum, and measured the specific antibody-responses via ELISA and ELISpot assay as well as T-cell responses in a proliferation assay after restimulation. Specific antibody titers, antibody affinity and plasma cell counts in the bone marrow were reduced in post-septic animals. The antigen-induced splenic proliferation was also impaired. The adaptive immunosuppression was positively correlated with an overwhelming general antibody response to the septic insult. Remarkably, antigen “overload” by non-specific immunization induced a similar degree of adaptive immunosuppression in the absence of sepsis. In both settings, depletion of regulatory T cells before priming reversed some parameters of the immunosuppression. In conclusion, our data show that adaptive immunosuppression occurs independent of profound systemic inflammation and life-threatening illness.

Increased soluble ST2 and IL‑4 serum levels are associated with disease severity in patients with membranous nephropathy

The interleukin (IL)‑33/suppression of tumorigenicity 2 (ST2) axis regulates Th2 reactivity, and ST2 is the receptor for IL‑33. In this study, the roles of IL‑33 and soluble ST2 (sST2) in the pathogenesis of membranous nephropathy (MN), and their association with disease severity were evaluated. Serum levels of IL‑33 and sST2 in 93 patients, and 34 healthy controls (HCs) were measured by enzyme‑linked immunosorbent assays. Clinical characteristics were recorded and the estimated glomerular filtration rates (eGFRs) were computed. In addition, the association between serum IL‑33 and sST2 levels, and clinical measurements in patients with MN was analyzed. No difference in the serum levels of IL‑33 was identified between the patients with MN and HCs. However, the serum levels of sST2 were considerably higher in the MN patients compared with in the HCs at every stage. Higher concentrations of serum IL‑2, IL‑4, IL‑10, IL‑17A, and IFN‑γ were measured in the MN patients compared with in the HCs. Serum sST2 concentrations were negatively correlated with IL‑4 concentrations in the patients with MN. Furthermore, serum sST2 levels were negatively correlated with the eGFRs and serum calcium levels. Serum sST2 levels, but not IL‑33 levels, were positively correlated with the 24‑h urine protein and serum phosphorus levels. Following treatment, serum sST2 levels were considerably reduced, whereas serum IL‑4 and IL‑10 levels were significantly increased. These data suggest that sST2 and IL‑4, but not IL‑33, contribute to the pathogenesis of MN.

Leptospirosis in human: Biomarkers in host immune responses

Leptospirosis remains one of the most widespread zoonotic diseases caused by spirochetes of the genus Leptospira, which accounts for high morbidity and mortality globally. Leptospiral infections are often found in tropical and subtropical regions, with people exposed to contaminated environments or animal reservoirs are at high risk of getting the infection. Leptospirosis has a wide range of clinical manifestations with non-specific signs and symptoms and often misdiagnosed with other acute febrile illnesses at early stage of infection. Despite being one of the leading causes of zoonotic morbidity worldwide, there is still a gap between pathogenesis and human immune responses during leptospiral infection. It still remains obscure whether the severity of the infection is caused by the pathogenic properties of the Leptospira itself, or it is a consequence of imbalance host immune factors. Hence, in this review, we seek to summarize the past and present milestone findings on the biomarkers of host immune response aspects during human leptospiral infection, including cytokine and other immune mediators. A profound understanding of the interlink between virulence factors and host immune responses during human leptospirosis is imperative to identify potential biomarkers for diagnostic and prognostic applications as well as designing novel immunotherapeutic strategies in future.

Pentraxin-3 as a marker of sepsis severity and predictor of mortality outcomes: A systematic review and meta-analysis

OBJECTIVES

Pentraxin-3 (PTX-3) is a multi-functional pattern recognition molecule produced by various cell types of peripheral tissues in different infections. It is raised in sepsis, but its values in predicting disease severity or mortality outcomes have been controversial. Therefore, we conducted a systematic review and meta-analysis of these associations.

METHODS

PubMed and Embase were searched until July 18, 2017 for studies that evaluated the relationship between PTX-3 levels and disease severity or mortality in sepsis.

RESULTS

A total of 23 and 10 entries were retrieved from both databases, respectively, of which 16 studies were included in the final meta-analysis. A total of 3001 patients (56% male, mean age 63 ± 15 years; mean follow-up duration of 207 days) were analysed. PTX-3 was significantly higher in patients with more severe sepsis compared to those with less severe sepsis (standard mean difference = 18.5 ng/mL, standard error: 4.5 ng/mL, P < 0.0001) and higher in non-survivors compared to survivors (standard mean difference = 40.3 ng/mL, standard error: 6.8 ng/mL, P < 0.0001). Elevated PTX-3 levels significantly increased the risk of all-cause mortality (hazard ratio: 1.91, 95% CI: 1.53 to 2.46, P < 0.0001).

CONCLUSIONS

PTX-3 significantly predicts disease severity and mortality in sepsis.

Predictive value of low interleukin-33 in critically ill patients

Patients admitted to a medical intensive care unit (ICU) are characterized by an activated immune system and exhibit a high mortality rate irrespective of the underlying cause of admission. Interleukin (IL)-33 has been shown to be protective in experimental sepsis models and it has been demonstrated that circulating levels of its "decoy" receptor soluble ST2 (sST2) are associated with outcome in critically ill patients. The aim of the present study was to investigate whether circulating IL-33 is associated with 30-day mortality in patients admitted to a medical ICU. In this prospective, observational study, both IL-33 and sST2 levels were assessed in 223 consecutive patients at ICU admission using specific enzyme-linked immunosorbent assays (ELISAs). During the 30-day follow-up, 58 patients (26%) died. Circulating IL-33 was detectable in 166 patients and in 57 patients, serum IL-33 was below the detection limit. Both detectable IL-33 and sST2 below the median were strong predictors of survival in critically ill patients independent of acute physiology and chronic health evaluation II (APACHE II) score. IL-33 and sST2 predicted risk independent from each other. Patients with both, non-detectable levels of IL-33 and sST2 levels above the median, showed a dramatically increased mortality risk (HR 6.9 95% CI 3.0-16.2; p<0.001). Low levels of IL-33 and increased levels of sST2 predict mortality risk in critically ill patients independent from each other and APACHE II score. Both together showed additive predictive value suggesting a pathogenic role of the IL-33/ST2 system in critically ill patients.

Association of interleukin 1 receptor-like 1 gene polymorphisms with eosinophilic phenotype in Japanese adults with asthma

BACKGROUND

IL1RL1 (ST2) is involved in Th2 inflammation including eosinophil activation. Single nucleotide polymorphisms (SNPs) of the IL1RL1 gene are associated with asthma development and increased peripheral blood eosinophil counts. However, the association between IL1RL1 SNPs and eosinophilic phenotype among adults with asthma remains unexplored.

METHODS

In a primary cohort of 110 adult Japanese patients with stable asthma, we examined the associations between IL1RL1 SNPs and clinical measurements including forced expiratory volume (FEV₁), airway reversibility of FEV₁, exhaled nitric oxide (FeNO), serum soluble-ST2 (sST2) levels, peripheral blood eosinophil differentials and serum total IgE level. The findings in the primary cohort were confirmed in a validation cohort of 126 adult Japanese patients with stable asthma.

RESULTS

Patients with minor alleles in 3 SNPs (rs17026974, rs1420101, and rs1921622) had high FeNO, blood eosinophil differentials, and reversibility of FEV₁, but low levels of serum sST2 and FEV₁. Minor alleles of rs1041973 were associated with low serum sST2 levels alone. In the validation cohort, minor alleles of rs1420101 were associated with high FeNO and blood eosinophil differentials, whereas minor alleles of rs17026974 and rs1921622 were associated with high blood eosinophil differentials and FeNO, respectively. Multivariate analyses revealed that the minor allele of rs1420101 additively contributed to the FeNO, blood eosinophil differentials, and reversibility of FEV₁.

CONCLUSIONS

The minor alleles of IL1RL1 SNPs were associated with high FeNO and peripheral blood eosinophilia among adult Japanese patients with stable asthma. IL1RL1 SNPs may characterize the eosinophilic phenotype with greater eosinophilic inflammation in the Japanese asthma cohort.

Emerging Roles of IL-33/ST2 Axis in Renal Diseases

Renal diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), have a great impact on health care systems worldwide. Similar to cardiovascular diseases, renal diseases are inflammatory diseases involving a variety of cytokines. Primary causes of renal injury include ischemia, uremic toxins, bacteremia, or nephrotoxicity. Inflammation represents an important component following kidney injury. Interleukin (IL)-33 is a member of the IL-1 cytokine family, which is widely expressed in epithelial barrier tissues and endothelial cells, and mediates both tissue inflammation and repair responses. IL-33 is released as a nuclear alarmin in response to tissue damage and triggers innate and adaptive immune responses by binding to its receptor, suppression of tumorigenicity 2 (ST2). Recent evidence from clinical and experimental animal studies indicates that the IL-33/ST2 axis is involved in the pathogenesis of CKD, renal graft injury, systemic lupus nephritis, and AKI. In this review, we discuss the pathological and tissue reparative roles of the IL-33/ST2 pathway in different types of renal diseases.

Maternal plasma-soluble ST2 concentrations are elevated prior to the development of early and late onset preeclampsia - a longitudinal study

OBJECTIVE

The objectives of this study were to determine (1) the longitudinal profile of plasma soluble ST2 (sST2) concentrations in patients with preeclampsia and those with uncomplicated pregnancies; (2) whether the changes in sST2 occur prior to the diagnosis of preeclampsia; and (3) the longitudinal sST2 profile of women with early or late preeclampsia.

MATERIALS AND METHODS

This longitudinal nested case-control study included singleton pregnancies in the following groups: (1) uncomplicated pregnancies (n = 160); and (2) those complicated by early (<34 weeks, n = 9) and late (≥34 weeks, n = 31) preeclampsia. sST2 concentrations were determined by enzyme-linked immunosorbent assays. Mixed-effects models were used for the longitudinal analysis.

RESULTS

(1) Plasma sST2 concentration profiles across gestation differed significantly among cases and controls (p < 0.0001); (2) women with early preeclampsia had higher mean sST2 concentrations than controls at >22 weeks of gestation; cases with late preeclampsia had higher mean concentrations at >33 weeks of gestation (both p < 0.05); and (3) these changes started approximately 6 weeks prior to clinical diagnosis.

CONCLUSIONS

Maternal plasma sST2 concentrations are elevated 6 weeks prior to the clinical diagnosis of preeclampsia. An increase in the maternal plasma concentration of sST2 may contribute to an exaggerated intravascular inflammatory response and/or the Th1/Th2 imbalance in some cases.

Soluble Suppression of Tumorigenicity 2 and Echocardiography in Sepsis

Soluble suppression of tumorigenicity 2 (sST2) has emerged as a biomarker of cardiac stretch or remodeling, and has demonstrated a role in acutely decompensated heart failure. However, its role in sepsis-induced cardiac dysfunction is still unknown. We explored whether sST2 serum concentration reflects either systolic or diastolic dysfunction as measured by Doppler echocardiography. In a total of 127 patients with sepsis, correlations between sST2 and blood pressure, left ventricular (LV) ejection fraction, LV diastolic filling (ratio of early transmitral flow velocity to early diastolic mitral annulus velocity), and resting pulmonary arterial pressure were evaluated. Correlations between sST2 and other sepsis biomarkers (high-sensitivity C-reactive protein [hs-CRP] and procalcitonin) were also examined. sST2 showed a moderate correlation with mean arterial pressure (r=-0.3499) but no correlation with LV ejection fraction, diastolic filling, or resting pulmonary hypertension. It showed moderate correlations with hs-CRP and procalcitonin (r=0.2608 and r=0.3829, respectively). sST2 might have a role as a biomarker of shock or inflammation, but it cannot reflect echocardiographic findings of LV ejection fraction or diastolic filling in sepsis.