ST2L Transmembrane Receptor Expression: An Immunochemical Study on Endarterectomy Samples

Comparison of the effect of uric acid/albumin ratio on coronary colleteral circulation with other inflammation-based markers in stable coronary artery disease patients

BACKGROUND

The Uric acid/Albumin ratio (UAR) has recently been identified as a prominent marker in cardiovascular diseases. In this study, we aimed to reveal the effect of UAR on coronary collateral circulation (CCC) in patients with stable coronary artery disease (CAD) patients by comparing it with conventional inflammation-based markers.

METHODS

In this study, 415 consecutive patients who underwent coronary angiography for stable angina pectoris and were found to have chronic total occlusion in at least one coronary artery were retrospectively included. The study population was divided into two groups as good CCC (Rentrop 2-3) and poor CCC (Rentrop 0-1) according to the Rentrop classification, and the groups were compared in terms of UAR and other traditional inflammation-based markers.

RESULTS

In the poor CCC group, C-reactive protein/albumin ratio (CAR), monocyte/high-density lipoprotein cholesterol ratio (MHR), neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), systemic immune-inflammation index (SII) and UAR were found to be significantly high (p < .05, for all). UAR negatively correlated with rentrop classification (r = -0.383, p < .001). In multivariate regression analysis, MHR, NLR, SII and UAR were determined as independent predictors for poor CCC (p < .05, for all). The ability of UAR to predict poor CCC was superior to uric acid and albumin alone (p < .0001, for both). In addition, UAR was found to be superior to other inflammation-based markers in predicting poor CCC (p < .005, for all).

CONCLUSION

UAR was identified as a strong and independent predictor of CCC. In this context, UAR may be a useful biomarker in the risk prediction of patients with stable CAD.

Soluble ST2 in Patients with Carotid Artery Stenosis-Association with Plaque Morphology and Long-Term Outcome

Interleukin (IL-33) and the ST2 receptor are implicated in the pathogenesis of atherosclerosis. Soluble ST2 (sST2), which negatively regulates IL-33 signaling, is an established biomarker in coronary artery disease and heart failure. Here we aimed to investigate the association of sST2 with carotid atherosclerotic plaque morphology, symptom presentation, and the prognostic value of sST2 in patients undergoing carotid endarterectomy. A total of 170 consecutive patients with high-grade asymptomatic or symptomatic carotid artery stenosis undergoing carotid endarterectomy were included in the study. The patients were followed up for 10 years, and the primary endpoint was defined as a composite of adverse cardiovascular events and cardiovascular mortality, with all-cause mortality as the secondary endpoint. The baseline sST2 showed no association with carotid plaque morphology assessed using carotid duplex ultrasound (B 0.051, 95% CI -0.145-0.248, p = 0.609), nor with modified histological AHA classification based on morphological description following surgery (B -0.032, 95% CI -0.194-0.130, p = 0.698). Furthermore, sST2 was not associated with baseline clinical symptoms (B -0.105, 95% CI -0.432-0.214, p = 0.517). On the other hand, sST2 was an independent predictor for long-term adverse cardiovascular events after adjustment for age, sex, and coronary artery disease (HR 1.4, 95% CI 1.0-2.4, p = 0.048), but not for all-cause mortality (HR 1.2, 95% CI 0.8-1.7, p = 0.301). Patients with high baseline sST2 levels had a significantly higher adverse cardiovascular event rate as compared to patients with lower sST2 (log-rank p < 0.001). Although IL-33 and ST2 play a role in the pathogenesis of atherosclerosis, sST2 is not associated with carotid plaque morphology. However, sST2 is an excellent prognostic marker for long-term adverse cardiovascular outcomes in patients with high-grade carotid artery stenosis.

Carotid Plaque Features and Inflammatory Biomarkers as Predictors of Restenosis and Mortality Following Carotid Endarterectomy

BACKGROUND

Carotid endarterectomy (CEA) is the first-line surgical intervention for cases of severe carotid stenoses. Unfortunately, the restenosis rate is high after CEA. This study aims to demonstrate the predictive role of carotid plaque features and inflammatory biomarkers (monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic inflammatory index (SII), Systemic Inflammation Response Index (SIRI), and Aggregate Index of Systemic Inflammation (AISI)) in carotid restenosis and mortality at 12 months following CEA.

METHODS

The present study was designed as an observational, analytical, retrospective cohort study and included all patients over 18 years of age with a minimum of 70% carotid stenosis and surgical indications for CEA admitted to the Vascular Surgery Clinic, Emergency County Hospital of Targu Mures, Romania between 2018 and 2021.

RESULTS

According to our results, the high pre-operative values of inflammatory biomarkers-MLR (OR: 10.37 and OR: 6.11; p < 0.001), NLR (OR: 34.22 and OR: 37.62; p < 0.001), PLR (OR: 12.02 and OR: 16.06; p < 0.001), SII (OR: 18.11 and OR: 31.70; p < 0.001), SIRI (OR: 16.64 and OR: 9.89; p < 0.001), and AISI (OR: 16.80 and OR: 8.24; p < 0.001)-are strong independent factors predicting the risk of 12-month restenosis and mortality following CEA. Moreover, unstable plaque (OR: 2.83, p < 0.001 and OR: 2.40, p = 0.04) and MI (OR: 3.16, p < 0.001 and OR: 2.83, p = 0.005) were independent predictors of all outcomes. Furthermore, AH (OR: 2.30; p = 0.006), AF (OR: 1.74; p = 0.02), tobacco (OR: 2.25; p < 0.001), obesity (OR: 1.90; p = 0.02), and thrombotic plaques (OR: 2.77; p < 0.001) were all independent predictors of restenosis, but not for mortality in all patients. In contrast, antiplatelet (OR: 0.46; p = 0.004), statin (OR: 0.59; p = 0.04), and ezetimibe (OR:0.45; p = 0.03) therapy were protective factors against restenosis, but not for mortality.

CONCLUSIONS

Our data revealed that higher preoperative inflammatory biomarker values highly predict 12-month restenosis and mortality following CEA. Furthermore, age above 70, unstable plaque, cardiovascular disease, and dyslipidemia were risk factors for all outcomes. Additionally, AH, AF, smoking, and obesity were all independent predictors of restenosis but not of mortality in all patients. Antiplatelet and statin medication, on the other hand, were protective against restenosis but not against mortality.

Association between circulating oxidized OxLDL/LDL-C ratio and the severity of coronary atherosclerosis, along with other emerging biomarkers of cardiovascular disease in patients with type 2 diabetes

AIMS

The aim of this study was to evaluate the association between circulating oxLDL/LDL-C ratio and the severity of coronary atherosclerosis, along with other emerging biomarkers of cardiovascular disease (CVD) in patients with type 2 diabetes.

METHODS

We recruited 152 patients with type 2 diabetes for our study. ELISA measured the plasma levels of oxLDL and other biomarkers. The severity of coronary lesions was evaluated using Gensini scores, which were calculated based on results of coronary computed tomographic angiography (CCTA). All patients were allocated into four groups according to CCTA findings and Gensini score: normal group (score = 0), mild coronary atherosclerosis group (0 < scores ≤ 3), moderate coronary atherosclerosis group (3.01 ≤ scores ≤ 32.67) and severe coronary atherosclerosis group (32.68 ≤ scores ≤ 180). Association between the oxLDL/LDL-C ratio and the severity of coronary atherosclerosis were evaluated using logistic regression models.

RESULTS

Multivariate logistic regression analysis showed that the oxLDL/LDL-C ratio was positively associated with severity of coronary atherosclerosis (OR 2.03, 95% CI 1.31-3.14, p < 0.01). Interleukin 33 (IL33) correlated positively with oxLDL/LDL-C ratio (r = 0.274, p < 0.01). However, vascular cell adhesion molecular-1 (VCAM-1) had similar trends with oxLDL/LDL-C ratio in these 4 groups.

CONCLUSIONS

OxLDL/LDL-C ratio is considered as a potential biomarker in patients with diabetes for early recognition and intervention of severe coronary atherosclerosis, and will be more effective if tested IL33 and VCAM-1 at the same time.

Biomarkers for Non-Invasive Stratification of Coronary Artery Disease and Prognostic Impact on Long-Term Survival in Patients with Stable Coronary Heart Disease

Knowledge about cardiac and inflammatory biomarkers in patients with stable coronary artery disease (CAD) is limited. To address this, we analyzed 3072 patients (36% female) with a median follow-up of 10 years in the Leipzig LIFE Heart Study with suspected CAD with coronary angiography. Selected biomarkers included troponin T (hsTNT), N-terminal pro B-type natriuretic peptide (NT-proBNP), copeptin, C-reactive protein (hsCRP), and interleukin-6 (IL-6). Patients were stratified by CAD severity: CAD0 (no sclerosis), CAD1 (non-obstructive, i.e., stenosis < 50%), and CAD2 (≥one stenosis ≥ 50%). Group comparison (GC) included GC1: CAD0 + 1 vs. CAD2; GC2: CAD0 vs. CAD1 + 2. CAD0, CAD1, and CAD2 were apparent in 1271, 631, and 1170 patients, respectively. Adjusted for classical risk factors, hs-cTnT, NT-proBNP, and IL-6 differed significantly in both GC and hsCRP only in GC2. After multivariate analysis, hs-cTnT, NT-proBNP, and IL-6 remained significant in GC1. In GC2, hs-cTnT (p < 0.001) and copeptin (p = 0.014) reached significance. Ten-year survival in groups CAD0, CAD1, and CAD2 was 88.3%, 77.3%, and 72.4%. Incorporation of hs-cTnT, NT-proBNP, copeptin, and IL-6 improved risk prediction (p < 0.001). The studied cardiac and inflammatory biomarkers enable fast and precise non-invasive identification of mortality risk in CAD patients, allowing the tailoring of primary and secondary CAD prevention.

The Prognostic Role of ST2L and sST2 in Patients Who Underwent Carotid Plaque Endarterectomy: A Five-Year Follow-Up Study

Soluble suppressor of tumorigenicity (sST)-2 plasma concentration is related to atherosclerosis. The aim of this study was to assess the prognostic impact of sST2 and its membrane-associated form (ST2L) in patients with carotid atherosclerotic plaque who underwent endarterectomy (CEA). Eighty-two consecutive patients (age range: 48−86 years) who underwent CEA were enrolled. Anthropometric, clinical, instrumental, and laboratory evaluations were gathered. Thirty-seven (45%) patients were symptomatic of cerebrovascular diseases. Patients underwent a five-year follow-up. Phone calls and the analysis of national and regional databases were performed in order to evaluate the occurrence of the primary outcome (all-cause mortality). The population was divided according to survival status. Statins were administered in 81% and 87.5% of survivors and non-survivors, respectively. sST2 levels were higher in non-survivors than in survivors (117.0 ± 103.9 vs. 38.0 ± 30.0 ng/mL, p < 0.001) and in symptomatic individuals, compared with asymptomatic (80.3 ± 92.1 ng/mL vs. 45.4 ± 41.4 ng/mL, p = 0.02). ROC curve analysis identified sST2 cut-off: >98.44 ng/mL as the best predictor for mortality. At the one-year follow-up, the survival rate decreased up to 20% in patients with sST2 higher than the cut-off value. A multivariate regression analysis revealed that only sST2 (HR: 1.012, 95% CI: 1.008−1.016, p < 0.0001) and triglycerides plasma levels (HR: 1.008, 95% CI: 1.002−1.015, p = 0.0135) remained significantly associated with all-cause mortality. ST2L was not associated with all-cause mortality risk. sST2 may act as an independent prognostic determinant of all-cause mortality and symptomatic cerebrovascular diseases in patients with carotid atherosclerotic plaque who underwent CEA.

Temporal Quantitative Phosphoproteomics Profiling of Interleukin-33 Signaling Network Reveals Unique Modulators of Monocyte Activation

Interleukin-33 (IL-33), a member of the IL-1 superfamily cytokines, is an endogenous danger signal and a nuclear-associated cytokine. It is one of the essential mediators of both innate and adaptive immune responses. Aberrant IL-33 signaling has been demonstrated to play a defensive role against various infectious and inflammatory diseases. Although the signaling responses mediated by IL-33 have been previously reported, the temporal signaling dynamics are yet to be explored. To this end, we applied quantitative temporal phosphoproteomics analysis to elucidate pathways and proteins induced by IL-33 in THP-1 monocytes. Employing a TMT labeling-based quantitation and titanium dioxide (TiO₂)-based phosphopeptide enrichment strategy followed by mass spectrometry analysis, we identified and quantified 9448 unique phosphopeptides corresponding to 3392 proteins that showed differential regulation. Of these, 171 protein kinases, 60 phosphatases and 178 transcription factors were regulated at different phases of IL-33 signaling. In addition to the confirmed activation of canonical signaling modules including MAPK, NFκB, PI3K/AKT modules, pathway analysis of the time-dependent phosphorylation dynamics revealed enrichment of several cellular processes, including leukocyte adhesion, response to reactive oxygen species, cell cycle checkpoints, DNA damage and repair pathways. The detailed quantitative phosphoproteomic map of IL-33 signaling will serve as a potentially useful resource to study its function in the context of inflammatory and pathological conditions.

The Paradigm Change of IL-33 in Vascular Biology

In this review, we focus on the actual understanding of the role of IL-33 in vascular biology in the context of the historical development since the description of IL-33 as a member of IL-1 superfamily and the ligand for ST2 receptor in 2005. We summarize recent data on the biology, structure and signaling of this dual-function factor with both nuclear and extracellular cytokine properties. We describe cellular sources of IL-33, particularly within vascular wall, changes in its expression in different cardio-vascular conditions and mechanisms of IL-33 release. Additionally, we summarize the regulators of IL-33 expression as well as the effects of IL-33 itself in cells of the vasculature and in monocytes/macrophages in vitro combined with the consequences of IL-33 modulation in models of vascular diseases in vivo. Described in murine atherosclerosis models as well as in macrophages as an atheroprotective cytokine, extracellular IL-33 induces proinflammatory, prothrombotic and proangiogenic activation of human endothelial cells, which are processes known to be involved in the development and progression of atherosclerosis. We, therefore, discuss that IL-33 can possess both protective and harmful effects in experimental models of vascular pathologies depending on experimental conditions, type and dose of administration or method of modulation.

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.

Angiotensin Converting Enzyme Inhibitors (ACEIs) Decrease the Progression of Cardiac Fibrosis in Rheumatic Heart Disease Through the Inhibition of IL-33/sST2

Rheumatic heart disease (RHD) is common in developing countries and poses a big medical challenge and burden. The pathogenesis of RHD is influenced by the triad of host, agent, and environment. Autoantigens generated from Group A Streptococcus (GAS) infection are captured by the resident dendritic cells (DCs) in the heart's valvular endothelium. DCs differentiate into antigen presenting cells (APC) in the valve interstices. APC induces activation of autoreactive T cells, which triggers inflammation and tissue fibrosis. Cardiac fibrosis is promoted through the activation of Mitogen activated protein kinases (MAPKs) and its downstream signaling, including its interaction with transforming growth factor-β (TGF-β) and Smad proteins. TGF-β-induced phosphorylation of Smad2 complexes with Smad3 and Smad4, and translocates into the nucleus. Angiotensin II enhances the migration, maturation, and presentation of DC. In RHD, Angiotensin II induces fibrosis via the stimulation of TGF-β, which further increases the binding of IL-33 to sST2 but not ST2L, resulting in the upregulation of Angiotensin II and progression of cardiac fibrosis. This cascade of inflammation and valvular fibrosis causes calcification and stiffening of the heart valves in RHD. Angiotensin converting enzyme inhibitors (ACEIs) inhibit Angiotensin II production, which in turn decreases TGF-β expression and the onset of overt inflammatory response. This condition leads to a reduction in the sST2 as the decoy receptor to "steal" IL-33, and IL-33 binds to ST2L and results in cardioprotection against cardiac fibrosis in the pathogenesis of RHD.

Correlation of plasma soluble suppression of tumorigenicity-2 level with the severity and stability of coronary atherosclerosis

BACKGROUND

Soluble growth stimulation expressed gene 2 (sST2) is the receptor of interleukin (IL)-33. We hypothesized the IL-33/ST2 pathway may be closely related to the progression of coronary atherosclerotic lesions.

METHODS

We analyzed 262 patients, including 63 with stable angina pectoris (SAP), 97 with acute coronary syndrome (ACS), and 102 control subjects. Plasma sST2 levels were determined using ELISA. Gensini scores were calculated. Patients with ACS and SAP were further divided according to the complexity of atherosclerotic lesions (simple/complex). Statistical analysis was performed on all data.

RESULTS

The plasma sST2 levels were significantly higher in patients with coronary artery disease (CAD) than in the control group, and were significantly higher in ACS patients with complex lesions than in those with simple lesions. There were no correlations between plasma sST2 level and both the number of culprit vessels and Gensini score. Multivariate stepwise regression analysis revealed that angiographically detected complex lesions were independently correlated with plasma sST2 level. Logistic regression analyses showed that sST2 was an independent factor of both CAD and the lesion type (simple/complex) of ACS. For the diagnosis of ACS and complex lesions, the area under the receiver operating characteristic curve of sST2 was 0.651.

CONCLUSIONS

The plasma sST2 level was not correlated with the stenosis severity of coronary atherosclerosis. A relationship between the plasma sST2 level and the morphology of complex lesions was found for the first time, especially in ACS patients. It may be a new marker for assessing the stability and complexity of atherosclerotic plaques.

ST2 and the ST2/IL-33 signalling pathway-biochemistry and pathophysiology in animal models and humans

ST2 is an interleukin (IL)-1 receptor family member with transmembrane (ST2L) and soluble (sST2) isoforms. Structurally, the ST2 gene products are very similar in mice and humans. In humans and in mice, alternative promoter activation and splicing produce ST2L and sST2. ST2L represents the longest transcript, whereas sST2 is the truncated, soluble isoform. ST2L is the biological receptor for IL-33, a member of the IL-1 family. IL-33 is the functional ligand of ST2L and signals the presence of tissue damage to local immune cells. IL-33/ST2L signalling leads to the production of inflammatory cytokines/chemokines and to the induction of the immune response. Conversely, sST2 functions as a decoy receptor for IL-33, inhibiting the effects of IL-33/ST2L signalling. Animal studies have allowed the investigation of ST2 and the IL-33/ST2L signalling pathway at multiple levels. However, clinical studies have mainly focused on the determination of sST2 in the circulation. In humans, plasma concentrations of sST2 increase in several diseases, such as heart disease, pulmonary disease, burn injury and graft-versus-host disease. Consequently, increased plasma concentrations of sST2 are not specific for a single disorder in humans and are thus of limited value for diagnostic purposes. However, increased plasma concentrations of sST2 have been linked to a worse prognosis in numerous diseases. Nevertheless, the major source of circulating sST2 in healthy and diseased humans is currently not fully established. In addition, whether the downregulation of sST2 can improve the outcome of patients in the clinical setting has not been elucidated. The aim of the present review was to provide an update on the findings regarding the biochemistry and pathophysiology of ST2 and the sST2 signalling pathway in humans and experimental models.

Integrated analysis of gene expression changes associated with coronary artery disease

BACKGROUND

This study investigated the pathways and genes involved in coronary artery disease (CAD) and the associated mechanisms.

METHODS

Two array data sets of GSE19339 and GSE56885 were downloaded. The limma package was used to analyze the differentially expressed genes (DEGs) in normal and CAD specimens. Examination of DEGs through Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and Gene Ontology annotation was achieved by Database for Annotation, Visualization and Integrated Discovery (DAVID). The Cytoscape software facilitated the establishment of the protein-protein interaction (PPI) network and Molecular Complex Detection (MCODE) was performed for the significant modules.

RESULTS

We identified 413 DEGs (291 up-regulated and 122 down-regulated). Approximately 256 biological processes, only 1 cellular component, and 21 molecular functions were identified by GO analysis and 10 pathways were enriched by KEGG. Moreover, 264 protein pairs and 64 nodes were visualized by the PPI network. After the MCODE analysis, the top 4 high degree genes, including interleukin 1 beta (IL1B, degree = 29), intercellular adhesion molecule 1 (ICAM1, degree = 25), Jun proto-oncogene (JUN, degree = 23) and C-C motif chemokine ligand 2 (CCL2, degree = 20) had been identified to validate in RT-PCR and Cox proportional hazards regression between CAD and normals.

CONCLUSIONS

The relative expression of IL1B, ICAM1 and CCL2 was higher in CAD than in normal controls (P < 0.05-0.001), but only IL1B and CCL2 genes were confirmed after testing the gene expression in blood and/or analyzing in Cox proportional hazards regression (P < 0.05-0.001), and the proper mechanism may involve in the AGE-RAGE signaling pathway, fluid shear stress, the tumor necrosis factor (TNF) and cytokine-cytokine receptor interaction.

Expression Density of Receptors as a Potent Regulator of Cell Function and Property in Health and Pathology

The expression of cytokine receptors has a crucial role in many cellular processes. Recent studies reported that changes of receptor expression could control the action of mediators on target cells. The initiation of different signaling pathways and, therefore, specific effects on cells, depends on certain components forming the cytokine-receptor complex. These mechanisms control the immune response and affect both the course of diseases (oncological, autoimmune, inflammatory) and the effectiveness of therapy. This review describes the potential of immune mediator receptors to regulate the efficiency of cytokine activity during pathologic processes and ensure the variability of their biological effects. Our aim was to investigate the spectrum of potential roles of changes in mediator receptor expression for main classes of pathologies. For all major types of immune mediators (cytokines, interleukins, chemokines, growth factors, and tumor necrosis factors), it has been shown that changes in their receptor expression are associated with impaired functioning of the organism in chronic diseases.

Conflicting vascular and metabolic impact of the IL-33/sST2 axis

Interleukin 33 (IL-33), which is expressed by several immune cell types, endothelial and epithelial cells, and fibroblasts, is a cytokine of the IL-1 family that acts both intra- and extracellularly to either enhance or resolve the inflammatory response. Intracellular IL-33 acts in the nucleus as a regulator of transcription. Once released from cells by mechanical stress, inflammatory cytokines, or necrosis, extracellular IL-33 is proteolytically processed to act in an autocrine/paracrine manner as an 'alarmin' on neighbouring or various immune cells expressing the ST2 receptor. Thus, IL-33 may serve an important role in tissue preservation and repair in response to injury; however, the actions of IL-33 are dampened by a soluble form of ST2 (sST2) that acts as a decoy receptor and is produced by endothelial and certain immune cells. Accumulating evidence supports the conclusion that sST2 is a biomarker of vascular health with diagnostic and/or prognostic value in various cardiovascular diseases, including coronary artery disease, myocardial infarction, atherosclerosis, giant-cell arteritis, acute aortic dissection, and ischaemic stroke, as well as obesity and diabetes. Although sST2 levels are positively associated with cardiovascular disease severity, the assumption that IL-33 is always beneficial is naïve. It is increasingly appreciated that the pathophysiological importance of IL-33 is highly dependent on cellular and temporal expression. Although IL-33 is atheroprotective and may prevent obesity and type 2 diabetes by regulating lipid metabolism, IL-33 appears to drive endothelial inflammation. Here, we review the current knowledge of the IL-33/ST2/sST2 signalling network and discuss its pathophysiological and translational implications in cardiovascular diseases.

The IL-33/ST2 pathway, inflammation and atherosclerosis: Trigger and target?

The "inflammatory hypothesis" of atherosclerosis postulates that inflammatory cell signalling drives the formation, growth and ultimately the instability of atherosclerotic plaques, setting up the substrate for the thrombotic response that causes myocardial damage or infarction. The recent Canakinumab Antiinflammatory Thrombosis Outcome Study (CANTOS) trial has been hailed as the first demonstration, ex iuvantibus, of the inflammatory hypothesis. Indeed, interleukin (IL)-1β inhibition was found to reduce cardiovascular events in patients with previous myocardial infarction and raised high-sensitivity C-reactive protein, despite no effects on the lipid profile. These results prompt a dissection of inflammatory mechanisms of atherosclerosis in order to search for specific biomarkers with prognostic value and/or therapeutic targets. Under this respect, the IL-33/suppression of tumorigenesis 2 (ST2) pathway deserves consideration. Indeed, its elements are particularly expressed in the endothelium of arterial vessels, and the interaction between IL-33 and the ST2 receptor blunts the immune response characteristic of atherosclerosis. By contrast, soluble ST2 (sST2) acts as a decoy receptor for IL-33, thus blocking its protective effects. Despite a solid theoretical framework, no definite demonstration of an involvement of the IL-33/ST2 pathway in atherosclerosis has been provided. Therefore, further studies are warranted to verify if elements of the IL-33/ST2 pathway may be proposed as markers of plaque burden and predictors of future cardiovascular events, and to explore the potential clinical benefit of enhanced IL-33/ST2 signalling in atherosclerosis.

miRNA-21 Expression in the Serum of Elderly Patients with Acute Myocardial Infarction

BACKGROUND The aims of this study were to examine the expression of miRNA-21 in the serum of elderly patients (>65 years) with acute myocardial infarction (AMI) and to investigate the potential role of serum miRNA-21 as a marker of early cardiac myocyte damage. MATERIAL AND METHODS Thirty-eight elderly patients with recent AMI, 27 elderly patients with unstable angina pectoris, and 25 healthy elderly individuals were included in the study. Serum miRNA-21 expression was determined following total RNA extraction and reverse-transcribed into cDNA, followed by reverse transcription-polymerase chain reaction (RT-PCR). Serum creatine kinase MB isoenzyme (CK-MB) and cardiac troponin I (cTnI) levels were analyzed by electrochemiluminescence. Apoptosis of human cardiac myocytes (HCM) was analyzed using fluorescence-activated cell sorting (FACS), and protein expression of caspase-3 was detected using Western blot. RESULTS Expression levels of miRNA-21 in the serum of elderly patients with AMI were positively correlated with serum levels of CK-MB (r=0.3683, P=0.0229) and cTnI (r=0.5128, P=0.009). Following tumor necrosis factor (TNF)-α induction, the apoptosis rates of HCM transfected with the miRNA-21 mimic short hairpin RNA (shRNA) were downregulated by 39.1% compared with control HCM cells, and protein expression of c-Jun N-terminal kinases (JNK) and p38 were unchanged (P>0.05); protein expression of p-JNK, p-p38 and caspase-3 were downregulated by 37.1%, 35.8%, and 36.0%, respectively. CONCLUSIONS Expression of miRNA-21 was upregulated in the serum of elderly patients with AMI, which inhibited TNF-a induced apoptosis in HCM by activating the JNK/p38/caspase-3 signaling pathway.