Reviews of Interleukin-37: Functions, Receptors, and Roles in Diseases

A Narrative Review of the IL-18 and IL-37 Implications in the Pathogenesis of Atopic Dermatitis and Psoriasis: Prospective Treatment Targets

Atopic dermatitis and psoriasis are prevalent inflammatory skin conditions that significantly impact the quality of life of patients, with diverse treatment options available. Despite advances in understanding their underlying mechanisms, recent research highlights the significance of interleukins IL-18 and IL-37, in Th1, Th2, and Th17 inflammatory responses, closely associated with the pathogenesis of psoriasis and atopic dermatitis. Hence, IL-18 and IL-37 could potentially become therapeutic targets. This narrative review synthesizes knowledge on these interleukins, their roles in atopic dermatitis and psoriasis, and emerging treatment strategies. Findings of a literature search up to 30 May 2024, underscore a research gap in IL-37-targeted therapies. Conversely, IL-18-focused treatments have demonstrated promise in adult-onset Still's Disease, warranting further exploration for their potential efficacy in psoriasis and atopic dermatitis.

Anti-Inflammatory Effect of Atorvastatin and Rosuvastatin on Monosodium Urate-Induced Inflammation through IL-37/Smad3-Complex Activation in an In Vitro Study Using THP-1 Macrophages

Objective: The pleiotropic effect of hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) is responsible for potent defense against inflammatory response. This study evaluated the inhibitory effects of HMG-CoA reductase inhibitors on the monosodium urate (MSU)-induced inflammatory response through the regulation of interleukin-37 (IL-37) expression. Methods: Serum was collected from patients with gout (n = 40) and from healthy controls (n = 30). The mRNA and protein expression of the target molecules IL-1β, IL-37, caspase-1, and Smad3 were measured in THP-1 macrophages stimulated with MSU, atorvastatin, or rosuvastatin using a real-time quantitative polymerase chain reaction and Western blot assay. Transfection with IL-1β or Smad3 siRNA in THP-1 macrophages was used to verify the pharmaceutical effect of statins in uric-acid-induced inflammation. Results: Serum IL-37 levels in gout patients were significantly higher than in controls (p < 0.001) and was associated with the serum uric acid level (r = 0.382, p = 0.008). THP-1 cells stimulated with MSU markedly induced IL-37 mRNA expression and the transition of IL-37 from the cytoplasm to the nucleus. Recombinant IL-37 treatment dose-dependently inhibited activation of caspase-1 and IL-1β in MSU-induced inflammation. Atorvastatin and rosuvastatin attenuated caspase-1 activation and mature IL-1β expression but augmented translocation of IL-37 from the cytoplasm to the nucleus. Atorvastatin and rosuvastatin induced phosphorylation of Smad3 in THP-1 cells treated with MSU crystals. Statins potently attenuated translocation of IL-37 from the cytoplasm to the nucleus in THP-1 macrophages transfected with Smad3 siRNA compared to cells with negative control siRNA. Conclusions: This study revealed that statins inhibit the MSU-induced inflammatory response through phosphorylated Smad3-mediated IL-37 expression in THP-1 macrophages.

Neutrophil-derived nanovesicles deliver IL-37 to mitigate renal ischemia-reperfusion injury via endothelial cell targeting

Renal ischemia-reperfusion injury (IRI) is one of the most important causes of acute kidney injury (AKI). Interleukin (IL)-37 has been suggested as a novel anti-inflammatory factor for the treatment of IRI, but its application is still limited by its low stability and delivery efficiency. In this study, we reported a novel engineered method to efficiently and easily prepare neutrophil membrane-derived vesicles (N-MVs), which could be utilized as a promising vehicle to deliver IL-37 and avoid the potential side effects of neutrophil-derived natural extracellular vesicles. N-MVs could enhance the stability of IL-37 and targetedly deliver IL-37 to damaged endothelial cells of IRI kidneys via P-selectin glycoprotein ligand-1 (PSGL-1). In vitro and in vivo evidence revealed that N-MVs encapsulated with IL-37 (N-MV@IL-37) could inhibit endothelial cell apoptosis, promote endothelial cell proliferation and angiogenesis, and decrease inflammatory factor production and leukocyte infiltration, thereby ameliorating renal IRI. Our study establishes a promising delivery vehicle for the treatment of renal IRI and other endothelial damage-related diseases.

Important Roles of Interleukin-36, Interleukin-37, and Interleukin-38 Cytokines in the Pathogenesis of Rosacea

Background

Rosacea is a chronic inflammatory skin disease. Previous studies have determined that IL-36, IL-37, and IL-38 may play a role in the pathogenesis of various inflammatory diseases.

Aims and Objectives

The present study aims to evaluate the relationship of these cytokines with rosacea.

Materials and Methods

A total of 100 individuals, including 50 patients with rosacea and 50 healthy controls, were included in the study. IL-36, IL-37, and IL-38 levels were measured using the ELISA method by taking serum samples from all participants.

Results

The mean serum levels of IL-36, IL-37, and IL-38 in the patient group were 52.17 ± 24.07 pg/ml, 18.46 ± 8.18 pg/ml, and 25.74 ± 8.36 ng/l, respectively. The mean serum levels of IL-36, IL-37, and IL-38 in the control group were 32.99 ± 19.90 pg/ml, 44.61 ± 22.27 pg/ml, and 45.61 ± 17.32 ng/l, respectively. The difference between the serum levels of IL-36, IL-37, and IL-38 in the patient and control groups was statistically significant (P < 0.001).

Conclusion

Based on these findings, an increase in IL-36 and a decrease in IL-37 and IL-38 may contribute to the pathogenesis of rosacea. Future rosacea treatments could target and/or interact with these possible steps in the pathogenesis of rosacea.

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).

Agree to disagree: The contradiction between IL-18 and IL-37 reveals shared targets in cancer

IL-37 is a newly discovered member of the IL-1 cytokine family which plays an important role in regulating inflammation and maintaining physiological homeostasis. IL-37 showed a close relationship with IL-18, another key cytokine in inflammation regulation and cancer development. IL-37 affects the function of IL-18 either by binding to IL-18Rα, a key subunit of both IL-37 and IL-18 receptor, or by drastically neutralizing the IL-18 protein expression of IL-18 binding protein, an important natural inhibitory molecule of IL-18. Moreover, as another subunit receptor of IL-37, IL-1R8 can suppress IL-18Rα expression, functioning as a surveillance mechanism to prevent overactivation of both IL-18 and IL-37 signaling pathways. While IL-18 and IL-37 share the same receptor subunit, IL-18 would in turn interfere with IL-37 signal transduction by binding to IL-18Rα. It is also reported that IL-18 and IL-37 demonstrated opposing effects in a variety of cancers, such as glioblastoma, lung cancer, leukemia, and hepatocellular cancer. Although the mutual regulation of IL-18 and IL-37 and their diametrically opposed effects in cancers has been reported, IL-18 has not been taken into consideration when interpreting clinical findings and conducting mechanism investigations related to IL-37 in cancer. We aim to review the recent progress in IL-18 and IL-37 research in cancer and summarize the correlation between IL-18 and IL-37 in cancer based on their expression level and underlying mechanisms, which would provide new insights into elucidating the conflicting roles of IL-18 and IL-37 in cancer and bring new ideas for translational research related to IL-18 and IL-37.

G9a Inhibition Promotes Neuroprotection through GMFB Regulation in Alzheimer's Disease

Epigenetic alterations are a fundamental pathological hallmark of Alzheimer's disease (AD). Herein, we show the upregulation of G9a and H3K9me2 in the brains of AD patients. Interestingly, treatment with a G9a inhibitor (G9ai) in SAMP8 mice reversed the high levels of H3K9me2 and rescued cognitive decline. A transcriptional profile analysis after G9ai treatment revealed increased gene expression of glia maturation factor β (GMFB) in SAMP8 mice. Besides, a H3K9me2 ChIP-seq analysis after G9a inhibition treatment showed the enrichment of gene promoters associated with neural functions. We observed the induction of neuronal plasticity and a reduction of neuroinflammation after G9ai treatment, and more strikingly, these neuroprotective effects were reverted by the pharmacological inhibition of GMFB in mice and cell cultures; this was also validated by the RNAi approach generating the knockdown of GMFB/Y507A.10 in Caenorhabditis elegans. Importantly, we present evidence that GMFB activity is controlled by G9a-mediated lysine methylation as well as we identified that G9a directly bound GMFB and catalyzed the methylation at lysine (K) 20 and K25 in vitro. Furthermore, we found that the neurodegenerative role of G9a as a GMFB suppressor would mainly rely on methylation of the K25 position of GMFB, and thus G9a pharmacological inhibition removes this methylation promoting neuroprotective effects. Then, our findings confirm an undescribed mechanism by which G9a inhibition acts at two levels, increasing GMFB and regulating its function to promote neuroprotective effects in age-related cognitive decline.

Potential Role of IL-37 in Atopic Dermatitis

Interleukin 37 (IL-37) is a recently discovered member of the IL-1 cytokine family that appears to have anti-inflammatory and immunosuppressive effects in various diseases. IL-37 acts as a dual-function cytokine, exerting its effect extracellularly by forming a complex with the receptors IL-18 α (IL-18Rα) and IL-1R8 and transmitting anti-inflammatory signals, as well as intracellularly by interacting with Smad3, entering the nucleus, and inhibiting the transcription of pro-inflammatory genes. Consequently, IL-37 is linked to IL-18, which plays a role in the pathogenesis of atopic dermatitis (AD), consistent with our studies. Some isoforms of IL-37 are expressed by keratinocytes, monocytes, and other skin immune cells. IL-37 has been found to modulate the skewed T helper 2 (Th2) inflammation that is fundamental to the pathogenesis of AD. This review provides an up-to-date summary of the function of IL-37 in modulating the immune system and analyses its potential role in the pathogenesis of AD. Moreover, it speculates on IL-37's hypothetical value as a therapeutic target in the treatment of AD.

Novel insights into IL-37: an anti-inflammatory cytokine with emerging roles in anti-cancer process

Interleukin-37 (IL-37) is a newly discovered member of IL-1 family. The cytokine was proved to have extensive protective effects in infectious diseases, allergic diseases, metabolic diseases, autoimmune diseases and tumors since its discovery. IL-37 was mainly produced by immune and some non-immune cells in response to inflammatory stimulus. The IL-37 precursors can convert into the mature forms after caspase-1 cleavage and activation intracellularly, and then bind to Smad-3 and transfer to the nucleus to inhibit the production and functions of proinflammatory cytokines; extracellularly, IL-37 binds to cell surface receptors to form IL-37/IL-18Rα/IL-1R8 complex to exert immunosuppressive function via inhibiting/activating multiple signal pathways. In addition, IL-37 can attenuate the pro-inflammatory effect of IL-18 through directly or forming an IL-37/IL-18BP/IL-18Rβ complex. Therefore, IL-37 has the ability to suppress innate and acquired immunity of the host, and effectively control inflammatory stimulation, which was considered as a new hallmark of cancer. Specifically, it is concluded that IL-37 can inhibit the growth and migration of tumor cells, prohibit angiogenesis and mediate the immunoregulation in tumor microenvironment, so as to exert effective anti-tumor effects. Importantly, latest studies also showed that IL-37 may be a novel therapeutic target for cancer monitoring. In this review, we summarize the immunoregulation roles and mechanisms of IL-37 in anti-tumor process, and discuss its progress so far and potential as tumor immunotherapy.

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.

Interleukin-37b Suppressed ILC2s in Children with Allergic Rhinitis

Background

Interleukin-37b is a fundamental inhibitor of innate and acquired immunity. Type 2 innate lymphoid cells (ILC2s) can secret type 2 cytokines and regulate allergic rhinitis (AR). However, the role of IL-37b in ILC2s in children with AR was not clear.

Methods

We recruited 15 AR children and controls. The serum IL-37b levels and its relation with the frequency and functional phenotype of ILC2s. The regulation of IL-37b on ILC2s proliferation and function was confirmed using flow cytometry and enzyme-linked immunosorbent assay (ELISA). The mRNA expression of IL-1R8, IL-18Rα, and ICOSL was examined using RCR. The change of IL-37b protein level in serum during subcutaneous allergen immunotherapy (SCIT) was determined by ELISA.

Results

We have demonstrated that both of the frequencies of blood ILC2s, IL-5+ILC2s, and IL-13+ILC2s in AR children were elevated compared with controls. The serum protein level of IL-37b was downregulated in AR, and it was negatively related to the frequency of ILC2s, IL-5+ILC2s, and IL-13+ILC2s. IL-37b increased the mRNA levels of IL-1R8, IL-18Rα, and ICOSL expressed by ILC2s. IL-37b suppressed the proliferation of ILC2s and the secretion of IL-5 and IL-13 from ILC2s. Finally, we found that IL-37b was increased in AR children after 3 years' SLIT, especially in the good response group.

Conclusion

Our findings highlight the role of IL-37b in the suppression of ILC2s and establish a new therapeutic target in AR.

Mast Cell Cytokines in Acute and Chronic Gingival Tissue Inflammation: Role of IL-33 and IL-37

Much evidence suggests autoimmunity in the etiopathogenesis of periodontal disease. In fact, in periodontitis, there is antibody production against collagen, DNA, and IgG, as well as increased IgA expression, T cell dysfunction, high expression of class II MHC molecules on the surface of gingival epithelial cells in inflamed tissues, activation of NK cells, and the generation of antibodies against the azurophil granules of polymorphonuclear leukocytes. In general, direct activation of autoreactive immune cells and production of TNF can activate neutrophils to release pro-inflammatory enzymes with tissue damage in the gingiva. Gingival inflammation and, in the most serious cases, periodontitis, are mainly due to the dysbiosis of the commensal oral microbiota that triggers the immune system. This inflammatory pathological state can affect the periodontal ligament, bone, and the entire gingival tissue. Oral tolerance can be abrogated by some cytokines produced by epithelial cells and activated immune cells, including mast cells (MCs). Periodontal cells and inflammatory-immune cells, including mast cells (MCs), produce cytokines and chemokines, mediating local inflammation of the gingival, along with destruction of the periodontal ligament and alveolar bone. Immune-cell activation and recruitment can be induced by inflammatory cytokines, such as IL-1, TNF, IL-33, and bacterial products, including lipopolysaccharide (LPS). IL-1 and IL-33 are pleiotropic cytokines from members of the IL-1 family, which mediate inflammation of MCs and contribute to many key features of periodontitis and other inflammatory disorders. IL-33 activates several immune cells, including lymphocytes, Th2 cells, and MCs in both innate and acquired immunological diseases. The classic therapies for periodontitis include non-surgical periodontal treatment, surgery, antibiotics, anti-inflammatory drugs, and surgery, which have been only partially effective. Recently, a natural cytokine, IL-37, a member of the IL-1 family and a suppressor of IL-1b, has received considerable attention for the treatment of inflammatory diseases. In this article, we report that IL-37 may be an important and effective therapeutic cytokine that may inhibit periodontal inflammation. The purpose of this paper is to study the relationship between MCs, IL-1, IL-33, and IL-37 inhibition in acute and chronic inflamed gingival tissue.

Marine-Derived Piericidin Diglycoside S18 Alleviates Inflammatory Responses in the Aortic Valve via Interaction with Interleukin 37

Calcific aortic valve disease (CAVD) is a valvular disease frequently in the elderly individuals that can lead to the valve dysfunction. Osteoblastic differentiation of human aortic valve interstitial cells (HAVICs) induced by inflammation play a crucial role in CAVD pathophysiological processes. To date, no effective drugs for CAVD have been established, and new agents are urgently needed. Piericidin glycosides, obtained from a marine-derived Streptomyces strain, were revealed to have regulatory effects on mitochondria in previous studies. Here, we discovered that 13-hydroxypiericidin A 10-O-α-D-glucose (1→6)-β-D-glucoside (S18), a specific piericidin diglycoside, suppresses lipopolysaccharide- (LPS) induced inflammatory responses of HAVICs by alleviating mitochondrial stress in an interleukin (IL)-37-dependent manner. Knockdown of IL-37 by siRNA not only exaggerated LPS-induced HAVIC inflammation and mitochondrial stress but also abrogated the anti-inflammatory effect of S18 on HAVICs. Moreover, S18 alleviated aortic valve lesions in IL-37 transgenic mice of CAVD model. Microscale thermophoresis (MST) and docking analysis of five piericidin analogues suggested that diglycosides, but not monoglycosides, exert obvious IL-37-binding activity. These results indicate that S18 directly binds to IL-37 to alleviate inflammatory responses in HAVICs and aortic valve lesions in mice. Piericidin diglycoside S18 is a potential therapeutic agent to prevent the development of CAVD.

MiR-300 promotes the proliferation, migration and invasion of fibroblast-like synoviocytes in rheumatoid arthritis by targeting IL-37

BACKGROUND

Fibroblast-like synoviocytes (FLS) are crucial regulators in the pathogenesis of rheumatoid arthritis (RA). Reportedly, microRNA (miR) participates in regulating the pathogenesis of RA. In this study, we explored the regulatory effects of miR-300 on the proliferation, migration and invasion of FLS, which were obtained from RA patients.

METHODS

qPCR was utilized to detect miR-300 expression and interleukin-37 (IL-37) mRNA expression in the synovial tissue of RA patients and healthy controls. Cell counting kit-8 (CCK-8) assay and Transwell assay were performed to investigate the regulatory function of miR-300 on the proliferation, migration and invasion of FLS. ELISA was employed to detect TNF-α, IL-6 and IL-8 levels, to evaluate the inflammatory response. Bioinformatics analysis and luciferase reporter assay were applied to validate the targeting relationship between miR-300 and IL-37. Western blot assay was executed to detect IL-37 protein expression in FLS.

RESULTS

MiR-300 was revealed to be markedly down-modulated in the synovial tissue and FLS of RA patients; meanwhile, IL-37 expression was up-modulated. The transfection of miR-300 mimics enhanced RA-FLS growth, migration, invasion and inflammatory response; transfection of miR-300 inhibitors repressed the growth, migration, invasion and inflammatory response of RA-FLS. IL-37 was identified as a downstream target of miR-300, and IL-37 partially counteracted the enhanced growth, migration, invasion and inflammatory response of RA-FLS induced by miR-300.

CONCLUSION

MiR-300 facilitates growth, migration, invasion and inflammatory response of FLS by targeting IL-37, suggesting it was a crucial regulator in the pathogenesis of RA.

Interleukin-37 gene polymorphism and susceptibility to pulmonary tuberculosis among Iraqi patients

BACKGROUND

Control of tuberculosis (TB) depends on a balance between host's immune factors and bacterial evasion strategies. Interleukin-37 (IL-37) is among the immunomodulatory factors that have been proposed to influence susceptibility to tuberculosis.

METHODS

A case-control study was conducted on 105 patients with pulmonary TB (37 active, 41 multi-drug resistant and 27 relapse) and 79 healthy controls to determine serum levels and single nucleotide polymorphisms (SNPs) of IL-37. The IL-37 level was assessed with an enzyme-linked immunosorbent kit, while DNA-sequencing was used to detect SNPs in the promoter region of IL37 gene.

RESULTS

Median level of IL-37 was markedly increased in serum of TB patients compared to controls (325.0 vs. 169.1 pg/mL; p < 0.001). This increase was universally determined in subgroups of patients distributed according to gender, age groups, and clinical type of disease, while no significant differences were found between the subgroups in patients or controls. Analysis of receiver operating characteristic curve confirmed these findings and IL-37 occupied a very good area under the curve, which was 0.816 (95% CI = 0.744-0.888; p < 0.001). At a cut-off value of 185.6 pg/mL, the sensitivity and specificity of IL-37 were 81.0 and 82.3%, respectively. Of the nine detected SNPs (rs2466449 G/A, rs2466450 A/G, rs2723168 G/A, rs3811042 G/A, rs3811045 T/C, rs3811046 G/T, rs3811047 A/G, rs3811048 G/A and rs200782323 G/A), only rs3811048 showed a significant association with TB; the G allele showed a significantly decreased frequency in TB patients compared to controls (25.2 vs. 44.9%; OR = 0.41; p < 0.001). It was possible to assign five haplotypes, and three showed significant differences between patients and controls. Frequency of haplotype A-A-G-A-C-T-G-A-G (0.331 vs. 0.213; OR = 2.10; p = 0.015) was significantly increased in TB patients compared to controls. On the contrary, frequencies of haplotypes A-A-G-A-C-T-G-G-G (0.029 vs. 0.116; OR = 0.24; p = 0.01) and A-A-G-G-T-G-A-G-G (0.140 vs. 0.275; OR = 0.45; p = 0.015) were significantly decreased in patients.

CONCLUSIONS

IL-37 was up-regulated in the serum of TB patients irrespective of their gender, age or clinical type of disease. SNPs in the promoter region of IL37 gene were proposed to be associated with susceptibility to TB.

CYTOKINES AS POTENTIAL MARKERS OF COVID-19 SEVERITY AND OUTCOMES

The continual propagation of SARS-CoV-2 has changed health care systems globally. Ranging degrees of clinical severity in COVID-19 patients have been noted in numerous literature sources. Cytokines play a crucial role in the development of key immunological processes in COVID-19. SARS-CoV-2 causes imbalance of the immune system and might culminate in cytokine storm and multiple organ involvement. The prevailing role of some special cytokines might serve as indicators of disease severity. Further stratification of patients in the context of specific cytokines can be beneficial for diagnosing disease stages. It can prevent critical states owing to timely diagnosis and targeted therapy. Targeting peculiar cytokines can markedly reduce complications. The aim of this article is to comprehensively overview the role of the main cytokines in COVID-19 pathogenesis and distinguish prognostic factors. Insights into specific cytokine involvement in COVID-19 pathogenesis may open new avenues for diagnosing hyperinflammatory COVID-19, predicting its outcomes and providing individualized cytokine-targeted therapeutic approaches.

Anti-inflammatory cytokines in sickle cell disease

Sickle cell disease (SCD) is a well-studied monogenetic disease with an established chronic inflammatory component. The paradigm shift towards inflammation has made the pathophysiology of SCD even more complex. Studies have shown that an imbalance between the pro-inflammatory and anti-inflammatory cytokines in SCD exists; however, the reports are skewed toward the pro-inflammatory mediators. We enumerate recent in vitro and in vivo studies on anti-inflammatory cytokines in SCD patients, and discuss the biology of anti-inflammatory cytokines including the already reported IL-2, TGF-β, and IL-10 as well as the recently discovered IL-27, IL-35 and IL-37. This review will improve the understanding of the pathophysiology of SCD and aid in the search of new therapeutic options for patients with SCD.

Biological Role, Mechanism of Action and the Importance of Interleukins in Kidney Diseases

Each year, the number of patients who are diagnosed with kidney disease too late is increasing, which leads to permanent renal failure. This growing problem affects people of every age, sex and origin, and its full etiopathogenesis is not fully understood, although the involvement of genetic susceptibility, infections, immune disorders or high blood pressure is suggested. Difficulties in making a correct and quick diagnosis are caused by the lack of research on early molecular markers, as well as educational and preventive activities among the public, which leads to the late detection of kidney diseases. An important role in the homeostasis and disease progression, including kidney diseases, is attributed to interleukins, which perform several biological functions and interact with other cells and tissues of the body. The aim of this article was to systematize the knowledge about the biological functions performed by interleukins in humans and their involvement in kidney diseases development. In our work, we took into account the role of interleukins in acute and chronic kidney disease and kidney transplantation.

The Role of Interleukins in the Pathogenesis of Dermatological Immune-Mediated Diseases

Autoimmune inflammatory diseases are primarily characterized by deregulated expression of cytokines, which drive pathogenesis of these diseases. A number of approved and experimental therapies utilize monoclonal antibodies against cytokine proteins. Cytokines can be classified into different families including the interleukins, which are secreted and act on leukocytes, the tumor necrosis factor (TNF) family, as well as chemokine proteins. In this review article, we focus on the interleukin family of cytokines, of which 39 members have been identified to this date. We outline the role of each of these interleukins in the immune system, and various dermatological inflammatory diseases with a focused discussion on the pathogenesis of psoriasis and atopic dermatitis. In addition, we describe the roles of various interleukins in psychiatric, cardiovascular, and gastrointestinal comorbidities. Finally, we review clinical efficacy and safety data from emerging late-phase anti-interleukin therapies under development for psoriasis and atopic dermatitis. Collectively, additional fundamental and clinical research remains necessary to fully elucidate the roles of various interleukin proteins in the pathogenesis of inflammatory dermatologic diseases, and treatment outcomes in patients.

Interleukin-37 inhibits inflammation activation and disease severity of PM2.5-induced airway hyperresponsiveness

We have shown in the past studies that fine particulate matter (PM2.5) exposure increases airway hyperresponsiveness and leads to lung inflammation damage. Interleukin (IL)-37 plays a inhibitory role in inflammation activation and maintenance. However, the function of IL-37 in the above processes keep unclear. We aim to explore the role of IL-37 in PM2.5-induced airway hyperresponsiveness in this study. A nose-only PM2.5 online concentration, enrichment and exposure instrument was also applied to generate mice model of airway hyperresponsiveness. A transgenic mice strain using a CMV promoter to express human IL-37b (hIL-37tg) was obtained. PM2.5 exposure was shown to increase airway resistance, followed by lung inflammation and IL-1β, TNFα, and IL-6 release, which was inhibited by IL-37tg mice and mice administrated recombinant human IL-37 intranasally (i.n). Moreover, expression of the proliferation-related protein PCNA and migration-related proteins MMP-2, MMP-9, and Vimentin was reduced in lung tissues of IL-37tg mice and mice given recombinant human IL-37 i.n. Abnormal cell contraction, proliferation, and migration of human airway smooth muscle cells (hASMCs) incubated with PM2.5 were also decreased by IL-37 treatment. In addition, IL-37 intervention of hASMCs before PM2.5 incubation decreased cytoplasmic calcium level and expression of PCNA, MMP-2, MMP-9 and Vimentin. Finally, knockdown of the IL-37 receptor IL-1R8 gene eliminated the protective effects of IL-37 in the above responses. We conclude that IL-37 inhibits inflammation activation and disease severity of airway hyperreactivity by PM2.5 induction.

Interleukin-37 gene polymorphism and susceptibility to coronavirus disease 19 among Iraqi patients

Coronavirus disease 19 (COVID-19) is a highly contagious respiratory viral infection. Dysregulated immune response is an important feature of disease, and cytokines are among the most important mediators of dysregulated immunity. Interleukin-37 (IL-37) is one such cytokine and studies have indicated its role in pathogenesis of COVID-19. However, IL37 gene polymorphisms have not been identified in patients with COVID-19. Therefore, this case-control study (100 patients and 100 controls) was performed to understand the role six single nucleotide polymorphisms of IL37 gene (SNPs: rs3811042, rs3811043, rs2466449, rs3811045, rs3811046 and rs3811047) in susceptibility to COVID-19 among cases with severe disease. These polymorphisms were identified by Sanger DNA sequencing. Results revealed that TG genotype of rs3811046 showed a significantly increased frequency in patients compared to controls (61.0 vs. 38.0%; odds ratio [OR] = 2.55; 95% confidence interval [CI] = 1.45–4.50; probability [p] = 0.002; corrected p [pc] = 0.01). GA genotype of rs3811047 also showed an increased frequency in patients but the pc-value was not significant (39.0 vs. 24.0%; OR = 2.02; 95% CI = 1.10–3.71; p = 0.033; pc = 0.165). Haplotype analysis revealed a significantly increased frequency of the haplotype G-C-A-T-T-A (in the order: rs3811042, rs3811043, rs2466449, rs3811045, rs3811046 and rs3811047) in COVID-19 patients compared to controls (0.055 vs. 0.006; OR = 10.23; 95% CI = 1.53–68.14; p = 0.003; pc = 0.03). In conclusion, the study indicated that two variants of IL37 gene (rs3811046 and rs3811047) may be associated with susceptibility to COVID-19 among Iraqi population.

The Activating Receptors of Natural Killer Cells and Their Inter-Switching Potentials

The global incidence of cancer is on the increase and researchers are prospecting for specific and non-selective therapies derived from the immune system. The killer activating receptors of NK cells are known to be involved in immunosurveillance against tumor and virally-infected cells. These receptors belong to two main categories, namely the immunoglobulin like and C-lectin like families. Though they have different signal pathways, all the killer activating receptors have similar effector functions which include direct cytotoxicity and the release of inflammatory cytokines such as IFN-gamma and TNF-alpha. To transduce signals that exceed the activation threshold for cytotoxicity, most of these receptors require synergistic effort. This review profiles 21 receptors: 13 immunoglobulin-like, 5 lectin-like, and 3 others. It critically explores their structural uniqueness, role in disease, respective transduction signal pathways and their status as current and prospective targets for cancer immunotherapy. While the native ligands of most of these receptors are known, much work is required to prospect for specific antibodies, peptides and multi-target small molecules with high binding affinities.

Interleukin-37 is down-regulated in serum of patients with severe coronavirus disease 2019 (COVID-19)

Pro-inflammatory and anti-inflammatory cytokines are indicated to play a prominent role in mediating the immunopathogenesis of coronavirus disease 19 (COVID-19). Interleukin (IL-37) is one of the anti-inflammatory cytokines that has been proposed to be involved in disease progression but the data are not overwhelming. Therefore, a case-control study was performed to analyze IL-37 levels in serum of 100 patients with severe COVID-19 and 100 blood donors (control group). Median age was significantly higher in COVID-19 cases than in controls. Stratification by gender, body mass index and ABO and Rh blood group systems showed no significant differences between patients and controls. Chronic diseases (cardiovascular and diabetes) were observed in 57.0% of patients. Serum levels of IL-37 and vitamin D were significantly decreased in patients compared to controls. The low level of IL-37 was more pronounced in males, overweight/obese cases, blood group B or AB cases, Rh-positive cases, and cases with no chronic disease. Low producers of IL-37 were more likely to develop COVID-19 (odds ratio = 2.66; 95% confidence interval = 1.51–4.70; corrected probability = 0.015). Receiver operating characteristic curve analysis demonstrated that a low serum level of IL-37 was a good predictor of COVID-19. Spearman's rank correlation analysis showed that IL-37 and vitamin D were significantly correlated. In conclusion, IL-37 was down-regulated in serum of patients with severe COVID-19 compared to controls. This down-regulation may be associated with an increased risk of disease. Gender, body mass index, blood groups and chronic disease status may also affect IL-37 levels.

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.

The effect of Apis dorsata honey as complementary therapy on IL-37 levels and fatigue in breast cancer patients undergoing chemotherapy

OBJECTIVE

The purpose of this study is to determine the effect of Apis dorsata Honey as a complementary therapy on IL-37 levels and fatigue in breast cancer patients undergoing chemotherapy.

METHOD

The study used a quasi-experimental pretest-posttest design with a control group. A total of 30 subjects were recruited using a concurrent sampling technique. The intervention group consisted of 15 subjects who received oral honey at a dose of 13 ml (1 tablespoon × 3) for 15 days, and the control group consisted of 15 subjects. The groups' samples were chosen at random. The Fatigue Symptom Inventory (FSI) was used to assess the side effects of chemotherapy.

RESULTS

Although the effect of Apis dorsata Honey on IL-37 levels was not statistically significant (p > 0.05), the group given honey experienced a clinically significant increase in IL-37 levels, with a mean before (632.37514.93) and post (632.37514.93). (1,003.021,248.88). Fatigue decreased statistically significantly in the group given mean honey values prior to 13.205.59 and after 11.805.07 (p = 0.004).

CONCLUSION

Honey administration increases IL-37 levels clinically, though the increase is not statistically significant. Giving honey to patients with breast cancer can help alleviate fatigue caused by chemotherapy.

IL-37bΔ1-45 suppresses the migration and invasion of endometrial cancer cells by targeting the Rac1/NF-κB/MMP2 signal pathway

Endometrial carcinoma is one of the most common malignancies in the female reproductive system. Interleukin-37 (IL-37) is a newly discovered anti-inflammatory factor belonging to the IL-1 family. IL-37 has five different isoforms, and IL-37b is the most biologically functional subtype. In recent years, the protective roles of IL-37 in different cancers, including lung and liver cancers, have been successively reported. IL-37 also plays an important role in some gynecological diseases such as endometriosis, adenomyosis, and cervical cancer. However, the role and mechanism of IL-37b, especially the mature form of IL-37b, in endometrial carcinoma have not been elucidated. The present study demonstrated that IL-37 protein was downregulated in endometrial carcinoma cells compared with the control endometrium. IL-37b did not affect the proliferation and colony-forming ability of endometrial cancer cells. A mature form of IL-37b (IL-37bΔ1-45) effectively suppressed the migration and invasion of endometrial cancer cells by decreasing the expression of matrix metalloproteinase 2 (MMP2) via Rac1/NF-κB signal pathway. However, it did not affect epithelial-mesenchymal transition (EMT) or filamentous actin (F-actin) depolymerization of endometrial cancer cells. IL-37bΔ1-45 attenuated tumor metastasis in a peritoneal metastatic xenograft model of endometrial cancer. To sum up, these results suggested IL-37b could be involved in the pathogenesis of endometrial carcinoma and provide a novel target for the diagnosis and treatment of endometrial carcinoma.

Correlation Between Level of Interleukin-37 and Rheumatoid Arthritis Progression

Background

Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disease that primarily affects joints. Interleukin-37 (IL-37) is an anti-inflammatory cytokine that is known to suppress immune response and inflammation. The objective of this study is to evaluate the correlation between level of IL-37 and RA progression using the disease activity score in 28 joints (DAS-28).

Methods

A total of 87 RA patients were separated into 4 groups based on the DAS28, referred to as the remission, mild, moderate and severe groups. 18 healthy volunteers were also included. Serum level of IL-37 and IL-37 mRNA expression level in peripheral blood mononuclear cells (PBMCs) in each individual participant as well as IL-37 mRNA expression level in synovial cells were assessed to explore their correlation with RA progression.

Results

Serum level of IL-37 and IL-37 mRNA expression levels in both PBMCs and synovial cells were all positively correlated with the severity of RA as reflected by the DAS28. Receiver operating characteristic (ROC) analysis revealed area under curve (AUC) values of 1, 0.5262 and 0.7789 for the three parameters.

Conclusion

Our results suggest that serum IL-37 level and mRNA expression levels of IL-37 in PBMCs and synovial cells are correlated with the severity of RA in a Chinese population.

IL-37 Was Involved in Progress of Acute Myeloid Leukemia Through Regulating IL-6 Expression

Background

Interleukin-37, which was discovered in 2000, is a natural suppressor of immune and inflammatory responses. Recent studies reported that IL-37 was abnormally expressed in several tumor patients, including those with hepatocellular carcinoma, gastric cancer, lung cancer, colon cancer, epithelial ovarian cancer, and multiple myeloma. However, the expression and potential function of IL-37 in leukemia remain unknown.

Objective

The aim of this study was to evaluate IL-37 as a prognostic factor and its possible mechanism of action.

Methods

Polymerase chain reaction products were analyzed by agarose gel electrophoresis and were purified and subsequently sequenced by a genetic testing laboratory. Human PBMC was purified from whole blood samples by using Ficoll-Paque PLUS. The concentrations of human IL-37 and human IL-6 were measured using enzyme-linked immunosorbent assay (ELISA) kits.

Results

IL-37, especially isoform b and d, was expressed in the bone marrow of AML, CML, ALL, and CLL. Importantly, IL-37 expression was downregulated in newly diagnosed AML patients and restored in patients in complete remission. Moreover, a significant association was found between IL-37 expression and NPM1 mutation or possible prognosis evaluated by karyotype and gene mutation. Further analysis revealed that IL-37 expression was negatively correlated with IL-6 expression. With regard to the mechanism, recombinant human IL-37 could suppress IL-6 expression stimulated by LPS in PBMC of AML patients.

Conclusion

Our study suggested that IL-37 may be an important prognostic factor in AML and is involved in AML via the IL-6 signaling pathway, indicating that IL-37 is an innovative research strategy for AML pathogenesis and therapy.

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.

Different Features of Interleukin-37 and Interleukin-18 as Disase Activity Markers of Adult-Onset Still's Disease

The aim of this study was to evaluate the usefulness of serum interleukin (IL)-37 and IL-18 as disease activity markers of adult-onset Still’s disease (AOSD) and to compare their related clinical features. Forty-five patients with a set of high and subsequent low disease activity status of AOSD were enrolled. Modified Pouchot (mPouchot) score and serologic disease activity markers including levels of IL-37 and IL-18 were compared between high and low disease activity status. The relationships between disease activity parameters and differences in levels of cytokines according to each disease manifestation were evaluated in high disease activity status. mPouchot score and all disease activity markers including IL-37 and IL-18 significantly declined after treatment. Though both cytokines positively correlated with mPouchot score, the two did not correlate with each other in high disease activity status. IL-18 positively correlated with ferritin, AST, and LDH while IL-37 correlated better with CRP. The expression level of IL-37 was related to leukocytosis while IL-18 was related to pleuritis, pneumonitis, abnormal LFT, and hyperferritinemia. In addition, patients in the IL-18 dominant group presented with higher LDH levels and required a higher mean corticosteroid dose. In conclusion, IL-37 and IL-18 are disease activity markers reflecting different aspects of AOSD that can complement each other.

Serum IL-37 Level Is Associated with Rheumatoid Arthritis and Disease Activity: A Meta-Analysis

Interleukin-37 (IL-37) inhibits the pathogenesis of rheumatoid arthritis (RA) via downregulating proinflammatory cytokines. Accordingly, we performed an analysis to accurately assess the relationship between serum IL-37 cytokine levels and disease activity of RA. Subgroup analysis and sensitivity analysis were applied to explore the sources of heterogeneity. Correlation coefficient (r) was utilized to evaluate the relationship between IL-37 and disease activity of RA patients. Ten studies were included into the research. Functional analysis revealed elevated serum IL-37 concentrations in RA patients (SMD = 1.61, P < 0.00001). The relationship between serum IL-37 levels and disease activity was statistically significant (C-reactive protein: r = 1.47, P = 0.0002; erythrocyte sedimentation rate: r = 1.55, P < 0.00001; rheumatoid factor: r = 1.40, P = 0.004; tumor necrosis factor⁃α: r = 1.64, P = 0.0003; Disease Activity Score for 28 joints: r = 1.63, P < 0.00001; tender joint count: r = 1.48, P < 0.00001; and swollen joint count: r = 1.52, P = 0.0003), but anti-CCP was not significant (anti-CCP: r = 0.98, P = 0.72). In summary, these data are suggesting that the elevated serum level of IL-37 in RA is positively correlated with the disease activity of RA, suggesting a role for IL-37in the pathogenesis of RA.

Entecavir downregulates interleukin-37 in patients with chronic active hepatitis B infection

Objectives

Interleukin-37 (IL-37) has been identified as a potent inhibitor of the immune response. This study aimed to examine IL-37 expression in patients with chronic active hepatitis B (CAHB), and explore its possible regulatory role during inflammation.

Methods

Peripheral blood mononuclear cells (PBMCs) were collected from control (n = 20) and CAHB patients (n = 30) before and after treatment with entecavir (EVT) for 24 weeks. The PBMCs were cultured with lipopolysaccharide and IL-37 expression was determined by real-time polymerase chain reaction and flow cytometry. The mRNA and protein concentrations of IL-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) in PBMCs were also measured.

Results

Levels of IL-37, IL-1β, IL-6, and TNF-α were significantly increased in the supernatant of PBMCs from patients with CAHB. IL-37 significantly reduced the expression of IL-1β, IL-6, and TNF-α. EVT resulted in regression of intraocular inflammation in patients with CAHB, associated with decreased production of IL-37.

Conclusion

These results suggest that increased expression of IL-37 was associated with the suppression of the inflammatory response in patients with CAHB. Furthermore, EVT treatment of CAHB was also correlated with downregulation of IL-37, indicating that EVT may partially alleviate the immune response by modulating IL-37 production.

Association between Serum IL-37 and Spinal Cord Injury: A Prospective Observational Study

Objective

Interleukin-37 (IL-37) is a new cytokine that naturally inhibits inflammation. Inflammation plays an important role in acute spinal cord injury (SCI). The purpose of this study is to check whether serum IL-37 can be used as a clinical predictor of SCI.

Methods

All subjects underwent venipuncture within 24 hours of enrollment to obtain peripheral blood and then centrifuged to obtain serum. The concentration of serum IL-37 was determined by enzyme-linked immunosorbent assay (ELISA). One month after the injury, the American Spinal Cord Injury Association (ASIA) impairment scale was used for neurological examination.

Results

A total of 148 people were included in the study, including 52 normal controls (NC) and 96 patients with acute SCI within 24 hours of onset. The comparison of clinical baseline data (age, gender, BMI: body mass index, smoking, alcohol drinking, CHD: coronary heart disease, HBP: high blood pressure, and DM: diabetes mellitus) between the two groups was not statistically significant (p > 0.05). However, the serum IL-37 concentration of SCI patients was significantly higher than that of the NC group, and the difference was statistically significant (p < 0.001). And with the aggravation of SCI grade, the level of IL-37 increased significantly (p < 0.05). Pearson correlation analysis further showed that serum IL-37 concentration is negatively correlated with AISA motor score (r = −0.327, p < 0.05).

Conclusion

The serum IL-37 concentration of SCI patients is significantly increased, and it is closely related to the recovery of motor function. We proved for the first time that serum IL-37 has prognostic value in patients with SCI. In addition, serum IL-37 may be used as a prognostic biomarker for SCI.

Levels of TNF-α, IL-6, IL-17, IL-37 cytokines in patients with active vitiligo

OBJECTIVES

Vitiligo is an autoimmune disease, and its pathogenesis involves changes in cytokine levels in the affected patients. Tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-17 from pro-inflammatory cytokines, IL-37 in a recently detected anti-inflammatory activity. The aim of our study was to determine serum TNF-α, IL-6, IL-17, IL-37 levels in patients with vitiligo to understand their possible roles in the disease etiology and to compare the results with the healthy controls.

METHODS

The study included 48 generalized vitiligo patients who were diagnosed with vitiligo, had an increase in the lesions within the last 3 months, and did not receive any systemic or topical treatment during this period; furthermore, 18 healthy controls were included.

RESULTS

Patient group: n = 48, mean age = 30.48 ± 9.86 years; control group: n = 18, mean age = 28.27 ± 9.66 years. Individuals in the patient group had significantly higher serum levels of IL-37(t = 3.90, p < .001), IL-6 (t = 3.39, p < .05), IL-17 (t = 2.08, p < .05), and TNF-α (t = 4.69 p < .001) than in the control group.

CONCLUSION

The high levels of (pro-anti) inflammatory cytokines in vitiligo patients draw attention to the importance of cytokines in the pathogenesis of the disease.

SARS-CoV-2 Infection and Cardioncology: From Cardiometabolic Risk Factors to Outcomes in Cancer Patients

The coronavirus disease-2019 (COVID-19) is a highly transmissible viral illness caused by SARS-CoV-2, which has been defined by the World Health Organization as a pandemic, considering its remarkable transmission speed worldwide. SARS-CoV-2 interacts with angiotensin-converting enzyme 2 and TMPRSS2, which is a serine protease both expressed in lungs, the gastro-intestinal tract, and cardiac myocytes. Patients with COVID-19 experienced adverse cardiac events (hypertension, venous thromboembolism, arrhythmia, myocardial injury, fulminant myocarditis), and patients with previous cardiovascular disease have a higher risk of death. Cancer patients are extremely vulnerable with a high risk of viral infection and more negative prognosis than healthy people, and the magnitude of effects depends on the type of cancer, recent chemotherapy, radiotherapy, or surgery and other concomitant comorbidities (diabetes, cardiovascular diseases, metabolic syndrome). Patients with active cancer or those treated with cardiotoxic therapies may have heart damages exacerbated by SARS-CoV-2 infection than non-cancer patients. We highlight the cardiovascular side effects of COVID-19 focusing on the main outcomes in cancer patients in updated perspective and retrospective studies. We focus on the main cardio-metabolic risk factors in non-cancer and cancer patients and provide recommendations aimed to reduce cardiovascular events, morbidity, and mortality.

Elevated serum levels of interleukin-37 correlate with poor prognosis in gastric cancer

BACKGROUND

interleukin-37 (IL-37) is as a natural suppressor of the innate inflammatory and immune responses. It has also been reported to be involved in carcinogenesis and metastasis. The present case-control study was designed to investigate the role of serum levels of IL-37 in patients with gastric cancer.

METHODS

serum IL-37 levels were determined using the enzyme-linked immunosorbent assay in 180 patients diagnosed with gastric cancer and 100 healthy controls. The association between IL-37 levels and clinical factors was assessed. Univariate and multivariate analyses were performed to investigate the prognostic significance of these parameters in gastric cancer.

RESULTS

serum IL-37 levels in gastric cancer patients (5.606 ± 0.837 pg/ml) were significantly higher than those in healthy controls (2.364 ± 0.210 pg/ml, p < 0.001). High serum IL-37 levels were related to a poorly differentiated histologic type (p = 0.046) and advanced T stage (p = 0.003). The Kaplan-Meier survival analysis indicated that the high-IL-37 group had a poorer overall survival and progression-free survival (overall survival [OS]: 39.0 months vs 13.0 months, p < 0.001, progression-free survival [PFS]: 25.0 months vs 10.0 months, p < 0.001). Multivariate analyses showed serum IL-37 to be an independent prognostic factor for gastric cancer patients (OS: hazard ratios [HR] = 1.842, 95% CI: 1.190-2.854, p = 0.006; PFS: HR = 1.547, 95% CI: 1.014-2.359, p = 0.043).

CONCLUSIONS

in conclusion, serum IL-37 levels were associated with poor overall survival and progression-free survival in gastric cancer patients. IL-37 may be a potential predictor of prognosis in gastric cancer.

Novel immune biomarkers in complex regional pain syndrome

We investigated serum levels of 29 cytokines and immune-activated kynurenine and tetrahydrobiopterin pathway metabolites in 15 complex regional pain syndrome (CRPS) subjects and 14 healthy controls. Significant reductions in interleukin-37 and tryptophan were found in CRPS subjects, along with positive correlations between kynurenine/tryptophan ratio and TNF-α levels with kinesiophobia, tetrahydrobiopterin levels with McGill pain score, sRAGE, and xanthurenic acid and neopterin levels with depression, anxiety and stress scores. Using machine learning, we identified a set of binary variables, including IL-37 and GM-CSF, capable of distinguishing controls from established CRPS subjects. These results suggest possible involvement of various inflammatory markers in CRPS pathogenesis.

IL-37 Exerts Anti-Inflammatory Effects in Fetal Membranes of Spontaneous Preterm Birth via the NF-κB and IL-6/STAT3 Signaling Pathway

Spontaneous preterm birth (sPTB), defined as delivery before 37 weeks of gestation, is thought to be a multifactorial syndrome. However, the inflammatory imbalance at the maternal-fetal interface promotes excessive secretion of inflammatory factors and induces apoptosis and degradation of the extracellular matrix (ECM), which can subsequently lead to preterm birth. As an anti-inflammatory molecule in the IL-1 family, interleukin-37 (IL-37) mainly plays an inhibiting role in a variety of inflammatory diseases. However, as a typical inflammatory disease, no previous studies have been carried out to explore the role of IL-37 in sPTB. In this study, a series of molecular biological experiments were performed in clinical samples and human amniotic epithelial cell line (Wistar Institute Susan Hayflick (WISH)) to investigate the deficiency role of IL-37 and the potential mechanism. Firstly, the results indicated that the expression of IL-37 in human peripheral plasma and fetal membranes was significantly decreased in the sPTB group. Afterward, it is proved that IL-37 could significantly suppress the production of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in WISH cells. Simultaneously, once silence IL-37, LPS-induced apoptosis and activity of matrix metalloproteinases (MMPs) 2 and 9 were significantly increased. In addition, the western blot data showed that IL-37 performed its biological effects by inhibiting the NF-κB and IL-6/STAT3 pathway. In conclusion, our results suggest that IL-37 limits excessive inflammation and subsequently inhibits ECM remodeling and apoptosis through the NF-κB and IL-6/STAT3 signaling pathway in the fetal membranes.

Integrated Transcriptome Analysis of Human Visceral Adipocytes Unravels Dysregulated microRNA-Long Non-coding RNA-mRNA Networks in Obesity and Colorectal Cancer

Obesity, and the obesity-associated inflammation, represents a major risk factor for the development of chronic diseases, including colorectal cancer (CRC). Dysfunctional visceral adipose tissue (AT) is now recognized as key player in obesity-associated morbidities, although the biological processes underpinning the increased CRC risk in obese subjects are still a matter of debate. Recent findings have pointed to specific alterations in the expression pattern of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), and long non-coding RNAs (lncRNAs), as mechanisms underlying dysfunctional adipocyte phenotype in obesity. Nevertheless, the regulatory networks and interrelated processes relevant for adipocyte functions, that may contribute to a tumor-promoting microenvironment, are poorly known yet. To this end, based on RNA sequencing data, we identified lncRNAs and miRNAs, which are aberrantly expressed in visceral adipocytes from obese and CRC subjects, as compared to healthy lean control, and validated a panel of modulated ncRNAs by real-time qPCR. Furthermore, by combining the differentially expressed lncRNA and miRNA profiles with the transcriptome analysis dataset of adipocytes from lean and obese subjects affected or not by CRC, lncRNA-miRNA-mRNA adipocyte networks were defined for obese and CRC subjects. This analysis highlighted several ncRNAs modulation that are common to both obesity and CRC or unique of each disorder. Functional enrichment analysis of network-related mRNA targets, revealed dysregulated pathways associated with metabolic processes, lipid and energy metabolism, inflammation, and cancer. Moreover, adipocytes from obese subjects affected by CRC exhibited a higher complexity, in terms of number of genes, lncRNAs, miRNAs, and biological processes found to be dysregulated, providing evidence that the transcriptional and post-transcriptional program of adipocytes from CRC patients is deeply affected by obesity. Overall, this study adds further evidence for a central role of visceral adipocyte dysfunctions in the obesity-cancer relationship.

Plasma levels of IL-1β and IL-37 in patients with severe haemophilia

Objective

Haemophilia A and B are disorders caused by the lack of clotting factors VIII and IX, respectively. Repeated bleeding into the same joint leads to haemophilic arthropathy (HA). Interleukin (IL)-1β is responsible for the pro-inflammatory response and IL-37 is induced by IL-1β stimuli to have an anti-inflammatory response and prevent uncontrolled inflammation and tissue damage. Our objective was to investigate plasma levels of IL-1β and IL-37 in patients with severe haemophilia with different severities of HA.

Methods

Peripheral blood samples were collected from 14 patients with severe haemophilia A and 6 with severe haemophilia B, and 18 healthy individuals. Plasma levels of IL-1β and IL-37 were detected by immunoassay, and severity of HA was evaluated using the Pettersson scoring system. Plasma levels of IL-1β and IL-37 were analysed in patients with severe haemophilia grouped by Pettersson score and in healthy individuals.

Results

Plasma levels of IL-1β and IL-37 were significantly higher in patients with severe haemophilia compared with healthy individuals and significantly lower in those with moderate to severe HA than in those with no or mild HA.

Conclusions

Plasma levels of IL-1β and IL-37 may be useful to track HA progression in patients with severe haemophilia.

Novel Analgesics with Peripheral Targets

A limited number of peripheral targets generate pain. Inflammatory mediators can sensitize these. The review addresses targets acting exclusively or predominantly on sensory neurons, mediators involved in inflammation targeting sensory neurons, and mediators involved in a more general inflammatory process, of which an analgesic effect secondary to an anti-inflammatory effect can be expected. Different approaches to address these systems are discussed, including scavenging proinflammatory mediators, applying anti-inflammatory mediators, and inhibiting proinflammatory or facilitating anti-inflammatory receptors. New approaches are contrasted to established ones; the current stage of progress is mentioned, in particular considering whether there is data from a molecular and cellular level, from animals, or from human trials, including an early stage after a market release. An overview of publication activity is presented, considering a IuPhar/BPS-curated list of targets with restriction to pain-related publications, which was also used to identify topics.

Remodeling adipose tissue inflammasome for type 2 diabetes mellitus treatment: Current perspective and translational strategies

Obesity-associated type 2 diabetes mellitus (T2DM) is characterized by low-grade chronic systemic inflammation that arises primarily from the white adipose tissue. The interplay between various adipose tissue-derived chemokines drives insulin resistance in T2DM and has therefore become a subject of rigorous investigation. The adipocytokines strongly associated with glucose homeostasis include tumor necrosis factor-α, various interleukins, monocyte chemoattractant protein-1, adiponectin, and leptin, among others. Remodeling the adipose tissue inflammasome in obesity-associated T2DM is likely to treat the underlying cause of the disease and bring significant therapeutic benefit. Various strategies have been adopted or are being investigated to modulate the serum/tissue levels of pro- and anti-inflammatory adipocytokines to improve glucose homeostasis in T2DM. These include use of small molecule agonists/inhibitors, mimetics, antibodies, gene therapy, and other novel formulations. Here, we discuss adipocytokines that are strongly associated with insulin activity and therapies that are under investigation for modulation of their levels in the treatment of T2DM.

IL-37 is protective in allergic contact dermatitis through mast cell inhibition

Allergic contact dermatitis (ACD), characterized predominantly by erythema, vesiculation, and pruritus, is a T cell-mediated skin inflammatory condition. Among immune cells involved in ACD, mast cells (MCs) play an essential role in its pathogenesis. As an inhibitor of proinflammatory IL-1 family members, interleukin 37 (IL-37) has been shown to ameliorate inflammatory responses in various allergic diseases. In this study, we assessed the immunomodulatory effect of IL-37 on allergic inflammation using a 2,4-dinitrofluorobenzene (DNFB)-induced ACD rat model and isolated rat peritoneal mast cells (RPMCs). Systematic application of IL-37 significantly relieved ear swelling, reduced inflammatory cell infiltration, decreased inflammatory cytokine production (TNF-α, IL-1β, IFN-γ, and IL-13), inhibited MC recruitment, lowered IgE levels, and reduced IL-33 production in the local ear tissues with DNFB challenge. Additionally, RPMCs isolated from ACD rats with IL-37 intervention showed downregulation of IL-6, TNF-α, IL-13, and MCP-1 production following IL-33 stimulation, and reduction of β-hexosaminidase and histamine release under DNP-IgE/HSA treatment. Moreover, IL-37 treatment also significantly restrained NF-κB activation and P38 phosphorylation in ACD RPMCs. SIS3, a specific Smad3 inhibitor, abolished the suppressive effects of IL-37 on MC-mediated allergic inflammation, suggesting the participation of Smad3 in the anti-ACD effect of IL-37. These findings indicated that IL-37 protects against IL-33-regulated MC inflammatory responses via inhibition of NF-κB and P38 MAPK activation accompanying the regulation of Smad3 in rats with ACD.

Pyroptosis: The missing puzzle among innate and adaptive immunity crosstalk

Pyroptosis is a newly discovered programmed cell death with inflammasome formation. Pattern recognition receptors that identify repetitive motifs of prospective pathogens such as LPS of gram-negative bacteria are crucial to pyroptosis. Upon stimulation by pathogen-associated molecular patterns or damage-associated molecular patterns, proinflammatory cytokines, mainly IL-1 family members IL-1β and IL-18, are released through pyroptosis specific pore-forming protein, gasdermin D. Even though IL-1 family members are mainly involved in innate immunity, they can be factors in adaptive immunity. Given the importance of IL-1 family members in health and diseases, deciphering the role of pyroptosis in the regulation of innate and adaptive immunity is of great importance, especially with the recent progress in identifying the exact mechanism of such a pathway. In this review, we will focus on how the innate inflammatory mediators can regulate the adaptive immune system and vice versa via pyroptosis.

The role of IL-37 in skin and connective tissue diseases

IL-37 was discovered as an anti-inflammatory and immunosuppressive cytokine of the IL-1 family. Significant advancements in the understanding of signaling pathways associated with IL-37 have been made in recent years. IL-37 binds to IL-18R and recruits IL-1R8 to form the IL-37/IL-1R8/IL-18Rα complex. Capase-1 plays a key role in the nuclear transduction of IL-37 signal, processing precursor IL-37 into the mature isoform, and interacting with Smad3. IL-37 exerts its role by activating anti-inflammation pathways including AMPK, PTEN, Mer, STAT3 and p62, and promoting tolerogenic dendritic cells and Tregs. In addition, IL-37 inhibits pro-inflammatory cytokines such as IL-1, IL-6, IL-8, IL-17, IL-23, TNF-α, and IFN-γ, and suppresses Fyn, MAPK, TAK1, NFκB, and mTOR signaling. The final effects of IL-37 depend on the interaction among IL-18R, IL-1R8, IL-37 and IL-18BP. Previous studies have deciphered the role of IL-37 in the development and pathogenesis of autoimmune diseases, chronic infections and cancer. In this review, we discuss the role of IL-37 in psoriasis, atopic dermatitis, Behcet's diseases, systemic lupus erythematosus, and other skin and connective tissue diseases.

Circulating concentration of interleukin-37 in Helicobacter pylori-infected patients with peptic ulcer: Its association with IL-37 related gene polymorphisms and bacterial virulence factor CagA

The immunopathologic responses play a major role in the development of H. pylori (HP)-related gastrointestinal diseases. IL-37 is an anti-inflammatory cytokine with potent suppressive effects on innate and adaptive immune responses. Here, we investigated the IL-37 levels and two single nucleotide polymorphisms (SNPs) including rs3811047 and rs2723176 in IL-37 gene in HP-infected peptic ulcer (PU) patients to identify any relationship. Three groups, including 100 HP-infected PU patients, 100 HP-infected asymptomatic (AS) subjects and 100 non-infected healthy control (NHC) subjects were enrolled to study. Serum IL-37 levels and the genotyping at rs3811047 and rs2723176 were determined using ELISA and SSP-PCR methods, respectively. Significantly higher IL-37 levels were observed in PU patients compared with AS and NHC groups (P < 0.0001). In both PU and AS groups, the CagA⁺ HP-infected participants displayed higher IL-37 levels compared with those infected with CagA^- strains (P < 0.0001). There were significant differences between PU, AS and NHC groups regarding the distribution of genotypes and alleles at rs3811047 and rs2723176 SNPs. The genotype GG and allele G at IL-37 rs3811047 SNP, and the genotype CC and allele C at IL-37 rs2723176 SNP more frequently expressed in PU patients than total healthy subjects (AS + NHC groups) and were associated with an increased risk of PU development (genotype GG: RR = 3.08, P < 0.009; allele G: RR = 2.94, P < 0.01; genotype CC: RR = 5, P < 0.01; and allele C: RR = 5.0, P < 0.02, respectively). The PU patients with allele A at IL-37 rs2723176 SNP expressed higher amounts of IL-37 compared with patients carried allele C at the same position (P < 0.05). In AS carriers and NHC individuals, the IL-37 levels in subjects carried genotype AA or allele A at IL-37 rs2723176 SNP were higher than those carried genotype CC or allele C at the same location (P < 0.01 and P < 0.02 for AS group; P < 0.0001 and P < 0.001 for NHC subjects, respectively). The increased IL-37 levels may be considered as a valuable marker of PU development in HP-infected individuals. The SNPs rs3811047 and rs2723176 were associated with PU development. The CagA status of HP and IL-37 rs2723176 SNP may affect the IL-37 levels.