Plasma IL-37 Elevated in Patients with Chronic Heart Failure and Predicted Major Adverse Cardiac Events: A 1-Year Follow-Up Study

IL-37 Modulates Myocardial Calcium Handling via the p-STAT3/SERCA2a Axis in HF-Related Engineered Human Heart Tissue

Interleukin-37 (IL-37) is a potent anti-inflammatory cytokine belonging to the IL-1 family. This study investigates the regulatory mechanism and reparative effects of IL-37 on HF-related human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs) and engineered human heart tissue subjected to hypoxia and H2O2 treatment. The contractile force and Ca2+ conduction capacity of the tissue are assessed using a stretching platform and high-resolution fluorescence imaging system. This investigation reveals that IL-37 treatment significantly enhances cell viability, calcium transient levels, contractile force, and Ca2+ conduction capacity in HF-related hiPSC-CMs and engineered human heart tissue. Notably, IL-37 facilitates the upregulation of sarcoplasmic reticulum calcium ATPase 2a (SERCA2a) through enhancing nuclear p-STAT3 levels. This effect is mediated by the binding of p-STAT3 to the SERCA2a promoter, providing a novel insight on the reparative potential of IL-37 in HF. IL-37 demonstrates its ability to enhance systolic function by modulating myocardial calcium handling via the p-STAT3/SERCA2a axis in HF-related engineered human heart tissue (as shown in schematic diagram).

Serum IL-38 Level Was Associated with Incidence of MACE in the STEMI Patients

Background

The relationship between serum IL-38 and major adverse cardiovascular events (MACE) in patients with ST elevation myocardial infarction (STEMI) remains unclear.

Methods

In the present study, 589 STEMI patients were included, the serum level of IL-38 was measured. The median follow-up time was 720 days, the STEMI patients were divided into high IL-38 (IL-38>6.49ng/mL) and low IL-38 groups (IL-38≤6.49ng/mL) to compare the probability of MACE.

Results

Plasma IL-38 levels were significantly lower in STEMI patients than in SAP patients (4.0±2.2 vs 6.9±3.2 ng/mL, P < 0.001). Ninety-three STEMI patients met the defined MACE study endpoint. The incidence of MACE was significantly lower in patients with high IL-38 group than in patients with low IL-38 group (7.8% vs 23.7%, P < 0.001). Low plasma IL-38 levels were independently associated with the occurrence of MACE (OR = 0.90, P < 0.001).

Conclusion

We get a conclusion that low plasma levels of IL-38 are independently associated with the occurrence of MACE.

A Critical Appraisal of the Diagnostic and Prognostic Utility of the Anti-Inflammatory Marker IL-37 in a Clinical Setting: A Case Study of Patients with Diabetes Type 2

BACKGROUND

The role of the cytokine interleukin-37 (IL-37) has been recognized in reversing inflammation-mediated metabolic costs. The aim was to evaluate the clinical utility of this cytokine as a diagnostic and prognostic marker in patients with type 2 diabetes (T2D).

METHODS

We included 170 older (median: 66 years) individuals with T2D (females: 95) and classified as primary care attenders to assess the association of factors that describe patients with plasma IL-37 levels (expressed as quartiles) using multinomial regression models. We determined the diagnostic ability of IL-37 cut-offs to identify diabetes-related complications or patient subgroups by using Receiver Operating Characteristic analysis (c-statistics).

RESULTS

Frailty status was shown to have a suppressive effect on IL-37 circulating levels and a major modifying effect on associations of metabolic and inflammatory factors with IL-37, including the effects of treatments. Situations in which IL-37 reached a clinically significant discriminating ability included the model of IL-37 and C-Reactive Protein in differentiating among diabetic patients with low-normal/high BMI ((<25/≥25 kg/m2), and the model of IL-37 and Thyroid Stimulating Hormone in discriminating between women with/without metabolic syndrome.

CONCLUSIONS

The study has revealed limitations in using classical approaches in determining the diagnostic and prognostic utility of the cytokine IL-37 in patients with T2D and lain a foundation for new methodology approaches.

Circulating interleukin-37 declines with aging in healthy humans: relations to healthspan indicators and IL37 gene SNPs

Aging is characterized by declines in physiological function that increase risk of age-associated diseases and limit healthspan, mediated in part by chronic low-grade inflammation. Interleukin (IL)-37 suppresses inflammation in pathophysiological states but has not been studied in the context of aging in otherwise healthy humans. Thus, we investigated associations between IL-37 and markers of healthspan in 271 young (18-39 years; n = 41), middle-aged (40-64 years; n = 162), and older (65 + years; n = 68) adults free of overt clinical disease. After conducting a thorough validation of AdipoGen's IL-37 ELISA, we found that plasma IL-37 is lower in older adults (young: 339 ± 240, middle-aged: 345 ± 234; older: 258 ± 175 pg/mL; P = 0.048), despite elevations in pro-inflammatory markers. As such, the ratios of circulating IL-37 to pro-inflammatory markers were considerably lower in older adults (e.g., IL-37 to C-reactive protein: young, 888 ± 918 vs. older, 337 ± 293; P = 0.02), indicating impaired IL-37 responsiveness to a pro-inflammatory state with aging and consistent with the notion of immunosenescence. These ratios were related to multiple indicators of healthspan, including positively to cardiorespiratory fitness (P < 0.01) and negatively to markers of adiposity, blood pressure, and blood glucose (all P < 0.05). Lastly, we correlated single-nucleotide polymorphisms (SNPs) in the IL37 and ILR8 (the co-receptor for IL-37) genes and found that variants in IL37 SNPs tended to be associated with blood pressure and adiposity (P = 0.08-0.09) but did not explain inter-individual variability in circulating IL-37 concentrations across age (P ≥ 0.23). Overall, our findings provide novel insights into a possible role of IL-37 in biological aging in humans.

IL-37-a putative therapeutic agent in cardiovascular diseases

Although it is a member of the Interleukin (IL)-1 family, IL-37 is unique in that it has wide-ranging anti-inflammatory characteristics. It was originally thought to prevent IL-18-mediated inflammation by binding to the IL-18-binding protein. However, upon discovery that it binds to the orphan receptor, IL-1R8, further studies have revealed an expanded role of IL-37 to include several intracellular and extracellular pathways that affect various aspects of inflammation. Its potential role specifically in cardiovascular diseases (CVD) stemmed initially from the discovery of elevated plasma IL-37 levels in human patients with acute coronary syndrome and atrial fibrillation. Other studies using mouse models of ischemia/reperfusion injury, vascular calcification and myocardial infarction have revealed that IL-37 can have a beneficial role in these conditions. This review will explore recent research on the effects of IL-37 on the pathogenesis of CVD.

The intellectual base and research fronts of IL-37: A bibliometric review of the literature from WoSCC

Background

IL-37 is a recently identified cytokine with potent immunosuppressive functions. The research fronts of IL-37 are worth investigating, and there is no bibliometric analysis in this field. The purpose of this study is to construct the intellectual base and predict research hotspots of IL-37 research both quantitatively and qualitatively according to bibliometric analysis.

Methods

The articles were downloaded from the Web of Science Core Collection (WoSCC) database from the inception of the database to 1 April 2022. CiteSpace 5.8.R3 (64-bit, Drexel University, Philadelphia, PA, USA) and Online Analysis Platform of Literature Metrology (https://bibliometric.com/) were used to perform bibliometric and knowledge-map analyses.

Results

A total of 534 papers were included in 200 academic journals by 2,783 authors in 279 institutions from 50 countries/regions. The journal Cytokine published the most papers on IL-37, while Nature Immunology was the most co-cited journal. The publications belonged mainly to two categories of Immunology and Cell Biology. USA and China were the most productive countries. Meanwhile, the University of Colorado Denver in USA produced the highest number of publications followed by Radboud University Nijmegen in the Netherlands and Monash University in Australia. Charles A. Dinarello published the most papers, while Marcel F. Nold had the most co-citations. Top 10 co-citations on reviews, mechanisms, and diseases were regarded as the knowledge base. The keyword co-occurrence and co-citations of references revealed that the mechanisms and immune-related disorders were the main aspects of IL-37 research. Notably, the involvement of IL-37 in various disorders and the additional immunomodulatory mechanisms were two emerging hotspots in IL-37 research.

Conclusions

The research on IL-37 was thoroughly reviewed using bibliometrics and knowledge-map analyses. The present study is a benefit for academics to master the dynamic evolution of IL-37 and point out the direction for future research.

Circulating Interleukin-37 Levels in Healthy Adult Humans - Establishing a Reference Range

Interleukin (IL)-37 has an important function in limiting excessive inflammation. Its expression is increased in numerous inflammatory and autoimmune conditions and correlates with disease activity, suggesting it could have potential as a disease biomarker. Nevertheless, a reference range has yet to be determined. Our aim was to establish the first reference range of circulating IL-37 levels in healthy adult humans. PubMed was searched for studies reporting blood IL-37 concentrations in healthy adult subjects as measured by enzyme-linked immunosorbent assay. Nineteen studies were included in the analysis. Mean IL-37 levels were weighted by sample sizes, and weighted mean lower and upper levels ( ± 2SD of means) were calculated to provide a weighted mean and reference range. IL-37 levels were quantified in either serum or plasma from a total of 1035 (647 serum; 388 plasma) healthy subjects. The serum, plasma and combined matrix weighted means (reference ranges) were 72.9 (41.5 – 104.4) pg/mL, 83.9 (41.1 – 126.8) pg/mL, and 77.1 (41.4 – 112.8) pg/mL, respectively. There were no significant differences between serum and plasma means and upper and lower limits. Study means and upper IL-37 levels were significantly higher in Chinese population studies. From our analysis, a preliminary reference range for circulating IL-37 levels in healthy human adults has been established. In order to determine a reliable reference range for clinical application, large, prospective, multi-ethnic, healthy population studies are necessary. In addition, demographics, sample matrix, collection, processing and storage methods potentially affecting IL-37 detection levels should be thoroughly investigated.

Circulating IL-37 levels are elevated in patients with hypertension

Interleukin-37 (IL-37) has been reported to be closely linked to vascular diseases, including atherosclerosis and aortic calcification. The present study aimed to assess the expression levels of IL-37 in patients with hypertension. Blood samples were collected from control subjects (n=20) and patients with hypertension (n=45). Subsequently, macrophages, lymphocytes and dendritic cells were individually isolated and the mRNA expression of IL-37 was measured. In addition, the circulating IL-37 levels in control subjects (n=30) and patients with hypertension (n=334) were assessed. Furthermore, all patients who were subjected to detection of circulating IL-37 underwent ambulatory blood pressure monitoring. The results suggested that the mRNA levels of IL-37 in macrophages, but not in lymphocytes and dendritic cells, isolated from patients with hypertension were markedly elevated compared with those in cells isolated from control subjects. Circulating IL-37 levels were increased in patients with hypertension compared with those in control subjects and positively correlated with systolic and diastolic blood pressure in patients with hypertension. No differences were observed between patients with dipper hypertension and patients with non-dipper hypertension. In addition, patients with hypertension with a smoking habit, type 2 diabetes mellitus and carotid atherosclerotic plaque (CAP) exhibited higher IL-37 levels. IL-37 levels were positively correlated with creatinine, C-reactive protein and homocysteine levels. Furthermore, the results of a linear regression analysis suggested that IL-37 levels were independently associated with the presence of CAP. In conclusion, IL-37 levels are increased in patients with hypertension and may be associated with the onset of CAP.

Plasma Interleukin-37 is Elevated in Acute Ischemic Stroke Patients and Probably Associated With 3-month Functional Prognosis

Background

Interleukin-37 is a novel cytokine emerging as a natural suppressor of inflammatory responses. Inflammation and the immune response play important roles in acute ischemic stroke. This study aimed at evaluating the plasma levels and the association with 3-month outcomes of interleukin-37 in acute ischemic stroke patients.

Patients and Methods

In total, 152 consecutive patients with acute ischemic stroke and 45 healthy controls were included. Plasma interleukin-37 levels were determined in the first morning after admission using an enzyme-linked immunesorbent assay. The primary outcome was the 3-month functional outcome (modified Rankin Scale score >2). Logistic regression was used to evaluate the risk and 3-month outcome of stroke according to plasma interleukin-37 level.

Results

Plasma interleukin-37 levels were significantly higher in the patients with acute ischaemic stroke than in the healthy controls (182.26 versus 97.89 pg/mL, p<0.001). Patients with large-artery atherosclerosis had significantly higher IL-37 levels than those with small-artery occlusion (202.12±35.82 versus 175.67±33.71pg/mL, p<0.001). Plasma interleukin-37 levels were positively correlated with National Institutes of Health Stroke Scale scores (r=0.521, p<0.0001) and lesion volume (r=0.442, p<0.0001). Ninety-four and 58 patients had favourable and unfavourable 3-month outcomes, respectively. Elevated plasma interleukin-37 levels were independently associated with unfavourable 3-month outcomes (adjusted odds ratio=1.033, p=0.001, 95% confidence interval: 1.015–1.056).

Conclusion

Admission plasma interleukin-37 levels were significantly increased after acute ischemic stroke. Elevated interleukin-37 levels were independently associated with unfavourable 3-month prognoses in acute ischemic stroke patients. Further studies with other populations are needed.

The role of serum interleukin-37 levels, inflammation and blood pressure in patients with preeclampsia

AIM

Preeclampsia is one of the major causes of perinatal, fetal, and maternal mortality and morbidity. The aim of this study was to investigate the association of serum interleukin 37 (IL 37) with preeclampsia.

METHODS

39 women with preeclampsia were included as the study group. 38 healthy, and normotensive pregnant women, at similar gestational week with similar gravidity volunteered as the control group. Clinical findings, biochemical parameters, maternal and perinatal outcomes, and the serum concentrations of IL37 were compared between the groups. The relationship of IL 37 concentrations with clinical findings and blood pressure outcomes were also investigated.

RESULTS

Maternal serum IL 37 concentrations were significantly higher in patients with preeclampsia compared to the healthy pregnant women in the control group (p = .005). IL 37 positively correlated systolic blood pressure (BP) (r = 0.344, p = .002), and diastolic BP (r = 0.332, p = .003). IL 37 was identified as an independent predictor of preeclampsia.

CONCLUSIONS

Serum IL 37 concentrations were higher in preeclamptic patients compared to healthy pregnant women. Furthermore, IL 37 concentrations achieved success in identifying preeclampsia with hypertension. Increased IL 37 activity may have a role in the pathophysiology of preeclampsia.

Cytokines in heart failure

The natural history of heart failure (HF) is not linear, because changes in the heart structure and function start long before the disease becomes clinically evident. Many different cytokines originating from intracardiac tissues (cardiomyocytes, cardiac endothelial cells, cardiac fibroblasts, and cardiac infiltrated immune cells) or extracardiac tissues (adipose tissue, gut, and lymphoid organs) have been identified in HF. Because the levels of circulating cytokines correlate with the development and severity of HF, these mediators may have both pathophysiological importance, through their ability to modulate inflammation, myocyte stress/stretch, myocyte injury and apoptosis, fibroblast activation and extracellular matrix remodeling, and utility as clinical predictive biomarkers. A greater understanding of the mechanisms mediated by the multifaceted network of cytokines, leading to distinct HF phenotypes (HF with reduced or preserved ejection fraction), is urgently needed for the development of new treatment strategies. In this chapter, all these issues were thoroughly discussed, pointing on the practical considerations concerning the clinical use of the cytokines as prognostic biomarkers and potential therapeutic targets in HF.

Role of IL-37 in Cardiovascular Disease Inflammation

Inflammation is closely related to the pathogenesis and prognosis of cardiovascular disease (CVD). Interleukin-37 (IL-37), an anti-inflammatory IL-1 family cytokine, shifts cytokine expression from pro- to anti-inflammation via regulation of macrophage polarization and lipid metabolism. In macrophages, IL-37 functions through both intracellular and extracellular pathways to regulate the activity of NF-kB and PTEN as well as the expression of cytokines, including IL-1β, IL-6, and IL-10. Moreover, IL-37 levels are increased in the serum of patients with heart failure, atherosclerosis, and acute coronary syndrome with no evidence of anti-inflammatory effects. However, transgenic overexpression of IL-37 improves cardiac infarct and attenuates atherosclerosis plaque expansion. Hence, it is worthwhile to investigate the precise mechanism and role of IL-37 in the pathogenesis of CVD, which may provide deeper understanding of the inflammatory response in this context. This review summarizes the regulatory role of IL-37 in systematic inflammation induced by CVD and highlights recent advancements in the clinical application of IL-37 as a therapeutic agent or biomarker for diagnosis of CVD.

IL-37 promotes cell apoptosis in cervical cancer involving Bim upregulation

Background: Growing evidence has indicated that interleukin-37 (IL-37) is a potential anticancer molecule that mainly plays an inhibiting role in different kinds of cancers, but data for the role of IL-37 on cell apoptosis in cancers remains rare. The present study aimed to explore the role of IL-37 in cell apoptosis in cervical cancer, and the involved apoptosis-related molecules.

Methods: IL-37 was overexpressed by transfecting the pIRES2-EGFP-IL-37 plasmid in HeLa and C33A cells. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to detect the mRNA expression of IL-37, Bcl-2, Bax and Bim. Western blotting was performed to detect the protein expression of IL-37 and Bim. Cell apoptosis was detected by flow cytometry.

Results: IL-37 upregulated the mRNA expression levels of Bim by 138.40% for HeLa (P<0.05) and 58.95% for C33A (P<0.05), and increased the protein expression levels of BimL by 69.10% (P<0.05) and 56.66% (P<0.05) in HeLa and C33A, respectively. Overexpression of IL-37 increased the apoptosis rates by 152.86% for HeLa (P<0.01) and 25.4% for C33A (P<0.05). Knockdown of Bim by specific siRNA interference fragments (SiBim) reduced the apoptosis rates by 36.00% for HeLa (P<0.05) and 14.66% for C33A (P<0.05). Compared with the IL-37 overexpression group, the apoptosis rate in cotransfecting the IL-37 overexpression plasmid and SiBim group decreased by approximately 31% (P<0.05) and 24.35% (P<0.05) in HeLa and C33A, respectively.

Conclusion: IL-37 upregulated Bim in cervical cancer cells. Furthermore, IL-37 can promote cervical cancer cell apoptosis, but Bim knockdown decreased this promotion through IL-37. Thus, IL-37 can promote cervical cancer cell apoptosis, which involve the upregulation of Bim.

Influencing factors of NT-proBNP level inheart failure patients with different cardiacfunctions and correlation with prognosis

Factors influencing N-terminal pro-brain natriuretic peptide (NT-proBNP) level in heart failure patients with different cardiac functions were identified to explore the correlations with prognosis. Eighty heart failure patients with different cardiac functions treated in Yixing People's Hospital from January 2016 to June 2017 were selected, and divided into two groups (group with cardiac function in class II and below and group with cardiac function in class III and above), according to the cardiac function classification established by New York Heart Association (NYHA). Blood biochemical test and outcome analysis were conducted to measure serum NT-proBNP and matrix metalloproteinase-9 (MMP-9) levels in patients with different cardiac functions, and correlations between levels of NT-proBNP and MMP-9 and left ventricular ejection fraction (LVEF) level were analyzed in patients with different cardiac functions at the same time. In addition, risk factors for heart failure in patients with different cardiac functions were analyzed. Compared with the group with cardiac function in class III and above, the group with cardiac function in class II and below had significantly lower serum NT-proBNP and MMP-9 levels (p<0.05). For echocardiogram indexes, left ventricular end-diastolic diameter (LVEDD) and left ventricular end-systolic diameter (LVESD) in the group with cardiac function in class II and below were obviously lower than those in the group with cardiac function in class III and above (p<0.05), while LVEF was higher in group with cardiac function in class II and below than that in group with cardiac function in class III and above (p<0.05). NT-proBNP and MMP-9 levels were negatively correlated with LVEF level [r=−0.8517 and −0.8517, respectively, p<0.001 (<0.05)]. Cardiac function in class III and above, increased NT-proBNP, increased MMP-9 and decreased LVEF were relevant risk factors and independent risk factors for heart failure in patients with different cardiac functions. NT-proBNP and MMP-9 levels are negatively correlated with LVEF in patients regardless of the cardiac function class. Therefore, attention should be paid to patients who have cardiac function in class III and above, increased NT-proBNP and MMP-9 levels and decreased LVEF in clinical practices, so as to actively prevent and treat heart failure.