The potential of interleukin-37 as an effective therapeutic agent in asthma

Molecular Markers of Blood Cell Populations Can Help Estimate Aging of the Immune System

Aging of the immune system involves functional changes in individual cell populations, in hematopoietic tissues and at the systemic level. They are mediated by factors produced by circulating cells, niche cells, and at the systemic level. Age-related alterations in the microenvironment of the bone marrow and thymus cause a decrease in the production of naive immune cells and functional immunodeficiencies. Another result of aging and reduced tissue immune surveillance is the accumulation of senescent cells. Some viral infections deplete adaptive immune cells, increasing the risk of autoimmune and immunodeficiency conditions, leading to a general degradation in the specificity and effectiveness of the immune system in old age. During the COVID-19 pandemic, the state-of-the-art application of mass spectrometry, multichannel flow cytometry, and single-cell genetic analysis have provided vast data on the mechanisms of aging of the immune system. These data require systematic analysis and functional verification. In addition, the prediction of age-related complications is a priority task of modern medicine in the context of the increase in the aged population and the risk of premature death during epidemics. In this review, based on the latest data, we discuss the mechanisms of immune aging and highlight some cellular markers as indicators of age-related immune disbalance that increase the risk of senile diseases and infectious complications.

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.

Type 2 cytokine genes as allergic asthma risk factors after viral bronchiolitis in early childhood

Background

Genome-wide association studies of asthma have identified associations with variants in type-2 related genes. Also, specific interactions between genetic variants and viral bronchiolitis in the development of asthma has been suggested.

Objective

To conduct a gene-based analysis of genetic variants in type 2 cytokine related genes as risk factors for allergic asthma at school age, and further, to study their interaction with specific viral infections in early childhood.

Methods

A prospectively investigated cohort of children with previous bronchiolitis and controls came for follow-up at school age. The research visit, blinded to viral exposure, included detailed lung function tests, laboratory investigation, and questionnaires. Allergic asthma was defined as typical symptoms plus objective variable airway obstruction, in addition to laboratory verified atopy (elevated eosinophil count or sensitization to an allergen). Targeted and complete sequencing was performed for nine type 2 cytokine candidate genes: IL4, 5, 13, 25, 33 and 37, IL17RB, CRLF2 and TSLP.

Results

At follow-up, there were 109 children with genetic data, 91 with a history of bronchiolitis (46% respiratory syncytial virus, 24% human rhinovirus, 15% human metapneumovirus and 14% mixed viral etiology) and 18 without. The median age was 9.4 years (range 6-13) and 41 (38%) had laboratory verified atopy. Twenty-one children (19%) met the definition of allergic asthma. After adjusting for age, sex and five viral categories, IL33 achieved nominal significance (p = 0.017) for a positive association with allergic asthma development. In the gene-virus interaction analysis, the variant set in IL17RB demonstrated a nominally significant positive interaction with human metapneumovirus infection (p=0.05).

Conclusion

The results highlight the multifactorial nature of allergic asthma risk, with both viral infection and inherited genetic variants contributing to increasing risk. Results for IL33 and IL17RB were nominally significant and are potential candidate targets for designing therapeutics and early screening, but these results must be replicated in an independent study.

HLA-G in asthma and its potential as an effective therapeutic agent

OBJECTIVE

Asthma is a heterogeneous disease. Severity of asthma and sensitivity to medications vary across asthma subtypes. Human leukocyte antigen (HLA)-G has a wide range of functions in normal and pathological physiology. Due to its powerful immune function, HLA-G participates in the pathogenesis of different asthma phenotypes by regulating the activity and function of various immune cells. The mechanism of HLA-G in asthma is not fully clear, and there is no consensus on its mechanism in asthma. Further studies are needed to explore the role of HLA-G in different phenotypes of human asthma.

METHODS

Observational study.

RESULTS

HLA-G is an important immunomodulatory factor in asthma. Studies have found different levels of HLA-G in patients with different asthma subtypes and healthy controls, but other studies have come to the opposite conclusion.

CONCLUSION

We speculate that further study on the mechanism of HLA-G in asthma pheno-types may explain some of the contradictions in current studies. Findings should provide information regarding the potential of HLA-G as a novel target for asthma diagnosis and treatment.

Increased expression of IL-37 correlates with TNF-α levels and disease stage in endometriosis patients

Background

IL-37 is an anti-inflammatory cytokine that increases in several inflammatory diseases with the main inducing signal for its production being pro-inflammatory cytokines like TNF-α. We aimed to assess the correlation between peritoneal fluid levels of IL-37 and TNF-α in endometriosis patients and investigate their association with disease stage. Levels of IL-37 and TNF-α were assessed in peritoneal fluid of 50 patients with endometriosis and 23 endometriosis-free females using enzyme-linked immunosorbent assay. We also assessed serum levels of IL-37 using enzyme-linked immunosorbent assay and expression of IL-37 mRNA in peritoneal fluid cells using polymerase chain reaction.

Results

Peritoneal fluid levels of IL-37 and TNF-α were higher in endometriosis patients than in control females. Also, levels were higher in patients with late endometriosis than patients with early endometriosis. In addition, serum levels of IL-37, as well as IL-37 mRNA expression in peritoneal fluid cells, were higher in patients than controls. In endometriosis patients, peritoneal fluid levels of IL-37 positively correlated with levels of TNF-α.

Conclusion

Collectively, our results show increased levels of the anti-inflammatory cytokine IL-37 in endometriosis patients that correlate with levels of the pro-inflammatory cytokine TNF-α, one of the main signals for IL-37 production.

Severe acute asthma at the pediatric intensive care unit: can we link the clinical phenotypes to immunological endotypes?

INTRODUCTION

The clinical phenotype of severe acute asthma at the pediatric intensive care unit (PICU) is highly heterogeneous. However, current treatment is still based on a 'one-size-fits-all approach'.

AREAS COVERED

We aim to give a comprehensive description of the clinical characteristics of pediatric patients with severe acute asthma admitted to the PICU and available immunological biomarkers, providing the first steps toward precision medicine for this patient population. A literature search was performed using PubMed for relevant studies on severe acute (pediatric) asthma.

EXPERT OPINION

Omics technologies should be used to investigate the relationship between cellular molecules and pathways, and their clinical phenotypes. Inflammatory phenotypes might guide bedside decisions regarding the use of corticosteroids, neutrophil modifiers and/or type of beta-agonist. A next step toward precision medicine should be inclusion of these patients in clinical trials on biologics.

The emerging role of Interleukin 37 in bone homeostasis and inflammatory bone diseases

Interleukin 37 (IL-37) is a newly identified cytokine that belongs to the IL-1 family. Unlike other members of the IL-1 family, it has been demonstrated that IL-37 possesses anti-inflammatory characteristics in both innate and acquired immune responses. Recently, significant progress has been made in understanding the role of IL-37 in inflammatory signaling pathways. Meanwhile, IL-37 has also attracted more and more attention in bone homeostasis and inflammatory bone diseases. The latest studies have revealed that IL-37 palys an essential role in the regulation of osteoclastogenesis and osteoblastogenesis. The levels of IL-37 are abnormal in patients with inflammatory bone diseases such as rheumatoid arthritis (RA), osteoarthritis (OA), ankylosing spondylitis (AS), and periodontitis. In addition, in vivo studies have further confirmed that recombinant IL-37 treatment displayed therapeutic potential in these diseases. The present review article aims to provide an overview describing the biological functions of IL-37 in bone homeostasis and inflammatory bone diseases, thus shedding new light on a novel therapeutic strategy in the future.

IL-37b alleviates endothelial cell apoptosis and inflammation in Kawasaki disease through IL-1R8 pathway

Kawasaki disease (KD) is an acute vasculitis of pediatric populations that may develop coronary artery aneurysms if untreated. It has been regarded as the principal cause of acquired heart disease in children of the developed countries. Interleukin (IL)-37, as one of the IL-1 family members, is a natural suppressor of inflammation that is caused by activation of innate and adaptive immunity. However, detailed roles of IL-37 in KD are largely unclear. Sera from patients with KD displayed that IL-37 level was significantly decreased compared with healthy controls (HCs). QRT-PCR and western blot analyses showed that the expression level of IL-37 variant, IL-37b, was remarkably downregulated in human umbilical vein endothelial cells (HUVECs) exposed to KD sera-treated THP1 cells. Therefore, we researched the role of IL-37b in the context of KD and hypothesized that IL-37b may have a powerful protective effect in KD patients. We first observed and substantiated the protective role of IL-37b in a mouse model of KD induced by Candida albicans cell wall extracts (CAWS). In vitro experiments demonstrated that IL-37b alleviated endothelial cell apoptosis and inflammation via IL-1R8 receptor by inhibiting ERK and NFκB activation, which were also recapitulated in the KD mouse model. Together, our findings suggest that IL-37b play an effective protective role in coronary endothelial damage in KD, providing new evidence that IL-37b is a potential candidate drug to treat KD.

Cytokine Storm and Mucus Hypersecretion in COVID-19: Review of Mechanisms

Mucus is an integral part of the respiratory physiology. It protects the respiratory tract by acting as a physical barrier against inhaled particles and microbes. Excessive inflammation in conditions such as COVID-19 can result in over-production of mucus which obstructs the airway. Build-up of mucus can also contribute to recurrent airway infection, causing further obstruction. This article summarizes the current understanding and knowledge of respiratory mucus production and proposes the role of cytokine storm in inducing sudden mucus hypersecretion in COVID-19. Based on these cascades, the active constituents that inhibit or activate several potential targets are outlined for further research. These may be explored for the discovery and design of drugs to combat cytokine storm and its ensuing complications.

The Role of New IL-1 Family Members (IL-36 and IL-38) in Atopic Dermatitis, Allergic Asthma, and Allergic Rhinitis

PURPOSE OF REVIEW

Since the discovery of its very first member in 1974, the IL-1 family has expanded into a group of 11 potent molecules which are essential in both innate and acquired immunity. Pro-inflammatory cytokines IL-36α, IL-36β, and IL-36γ and their receptor antagonists IL-36Ra and IL-38, which belong to the IL-36 subfamily, are some of the most recently identified members. Recent studies show that these members possess pro-inflammatory and anti-inflammatory activities and may take part in the pathogenesis of allergy. In this review, the involvement and importance of these newly described IL-1 family members in the most common allergic diseases, i.e., atopic dermatitis (AD), allergic asthma, and allergic rhinitis, will be discussed.

RECENT FINDINGS

Dysregulation of IL-36 and IL-38 was observed in the skin and respiratory tract of AD, allergic rhinitis, and allergic asthma individuals. Although the upregulation in IL-36α and IL-36γ observed in the lesional skin of AD patients was unexpectedly small, IL-36 may play an important role in AD pathogenesis especially upon Staphylococcus aureus colonization. While IL-36γ regulates eosinophils to induce an inflammatory response in allergic rhinitis, IL-36α was found to regulate Th17 immunity. IL-36 receptor antagonists, IL-36Ra and IL-38, however, both show promising anti-inflammatory activities against allergic asthma. Of note, IL-38 in allergic asthmatic children is significantly lower than their healthy counterparts, while the anti-inflammatory effects of IL-38 in allergic asthma exacerbation upon viral-like infection were demonstrated in in vitro, HDM-induced, and humanized mice models. Dysregulated expression of IL-36 and IL-38 observed in allergic patients and mice models revealed that they may have essential roles in the pathogenesis in AD, allergic rhinitis, and allergic asthma, especially during the host defense against pathogens at inflammatory sites. Their receptor antagonists, IL-36Ra and IL-38, could also be promising biologics in the control of allergy. Since allergic diseases are phenotypically complex, contradictory data obtained in different studies may be explained if further stratification of disease endotypes is explored. Genetically modified mice model and investigation in anti-IL-36 treatment may be useful to characterize the therapeutic potential of these cytokines in the regulation of allergy in the future.

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.

IL-37b alleviates inflammation in the temporomandibular joint cartilage via IL-1R8 pathway

Objectives

Interleukin (IL)‐37 is a natural suppressor of innate inflammation. This study was conducted to explore the anti‐inflammatory effects of IL‐37 in temporomandibular joint (TMJ) inflammation.

Materials and Methods

The expression of IL‐37 in the TMJ was measured using ELISA and IHC. Human TMJ chondrocytes were treated with IL‐37b and IL‐1β, and inflammation‐related factors were detected. siRNA‐IL‐1R8 was transfected into chondrocytes, and the affected pathways were detected. IL‐37b was used in disc‐perforation‐induced TMJ inflammation in SD rats. Micro‐CT, IHC, real‐time PCR and histological staining were used to quantify the therapeutic effect of IL‐37b.

Results

IL‐37 was expressed in the synovium and the disc of patients with osteoarthritis (OA) and in the articular cartilage of condylar fracture patients. IL‐37 was highly expressed in synovial fluid of patients with synovitis than in those with OA and disc displacement and was closely related to visual analogue scale (VAS) score. In vitro, IL‐37b suppressed the expression of pro‐inflammatory factors. In addition, IL‐37b exerted anti‐inflammatory effects via IL‐1R8 by inhibiting the p38, ERK, JNK and NF‐κB activation, while silencing IL‐1R8 led to inflammation and upregulation of these signals. In disc‐perforation‐induced TMJ inflammation in SD rats, IL‐37b suppressed inflammation and inhibited osteoclast formation to protect against TMJ.

Conclusions

IL‐37b may be a novel therapeutic agent for TMJ inflammation.

IL-37 increases in patients after ischemic stroke and protects from inflammatory brain injury, motor impairment and lung infection in mice

Post-stroke inflammation may contribute to secondary brain injury and systemic immunosuppression. Interleukin(IL)-37 is an immunosuppressive cytokine belonging to the IL-1 superfamily with no mouse homologue yet identified, the effects of which have not been studied in stroke. Here we report: (1) the effect of ischemic stroke on circulating IL-37 in humans; and (2) the effect of IL-37 on stroke outcome measures in mice transgenic for human IL-37 (IL-37tg). We found that in the first 3 days after ischemic stroke in 55 patients, the plasma abundance of IL-37 was ~2-fold higher than in 24 controls. In IL-37tg mice, cerebral ischemia-reperfusion resulted in marked increases in plasma IL-37 (~9-fold) and brain IL-37 mRNA (~7,000-fold) at 24 h compared with sham-operated IL-37tg mice. Further, compared with wild-type (WT) mice subjected to cerebral ischemia-reperfusion, IL-37tg mice exhibited less severe locomotor deficit, smaller cerebral infarcts and reduced bacterial lung infection. In the ischemic hemisphere, there were 60% fewer pro-inflammatory microglia-macrophages and up to 4-fold higher expression of anti-inflammatory markers in IL-37tg compared to WT mice. Our data show that IL-37 expression is increased following ischemic stroke in humans and IL-37tg mice, and may exert protective effects by modulating post-stroke inflammation in the brain and periphery.

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.

Distinct transcriptomic profiles of early-onset atopic dermatitis in blood and skin of pediatric patients

BACKGROUND

Atopic dermatitis (AD) predominantly affects young children, but our understanding of AD pathogenesis is based on skin and blood samples from long-standing adult AD. Genomic biopsy profiling from early pediatric AD showed significant Th2 and Th17/Th22-skewing, without the characteristic adult Th1 up-regulation. Because obtaining pediatric biopsies is difficult, blood gene expression profiling may provide a surrogate for the pediatric skin signature.

OBJECTIVE

To define the blood profile and associated biomarkers of early moderate-to-severe pediatric AD.

METHODS

We compared microarrays and reverse transcription polymerase chain reaction (RT-PCR) of blood cells from 28 AD children (<5 years and within 6 months of disease onset) to healthy control blood cells. Differentially expressed genes (DEGs) in blood (fold change [FCH] > 1.2 and false discovery rate [FDR] < 0.05) were then compared with skin DEGs.

RESULTS

Eosinophil and Th2 markers (IL5RA, IL1RL1/ST2, HRH4, CCR3, SIGLEC8, PRSS33, CLC from gene arrays; IL13/IL4/CCL22 from RT-PCR) were up-regulated in early pediatric AD blood, whereas IFNG/Th1 was decreased. Th1 markers were negatively correlated with clinical severity (EASI, pruritus, transepidermal water loss [TEWL]), whereas Th2/Th17-induced interleukin (IL)-19 was positively correlated with SCORAD. Although a few RT-PCR-defined immune markers (IL-13/CCL22) were increased in blood, as previously also reported for skin, minimal overlap based on gene array DEGs was seen.

CONCLUSION

The whole blood signature of early moderate-to-severe pediatric AD blood cells show predominantly a Th2/eosinophil profile; however, markers largely differ from the skin profile. Given their complementarity, pooling of biomarkers from blood and skin may improve profiling and predictions, providing insight regarding disease course, allergic comorbidity development, and response to systemic medications.