Aberrant Expression of Novel Cytokine IL-38 and Regulatory T Lymphocytes in Childhood Asthma

Evaluation of Salivary Il-38 Levels in Periodontitis: A Cross-Sectional Study

The goal of the current study was to assess levels of salivary interleukin (IL)-38, IL-1β, and IL-10 in various periodontal clinical conditions. In total, 60 (20 healthy, 20 gingivitis, and 20 stage II-III, grade A-B periodontitis) subjects were included in the study. Demographic and clinical periodontal parameters were recorded. Samples were examined for IL-38, IL-1β, and IL-10 levels by means of enzyme-linked immunosorbent assay. Results demonstrated that the periodontitis group had significantly lower salivary IL-38 levels (P < 0.05) than the healthy group. Salivary IL-10 levels did not differ significantly between the groups (P > 0.05). The salivary IL-1β levels of gingivitis (P < 0.001) and periodontitis groups (P < 0.01) were significantly higher than those of the healthy group. The present study indicated that IL-38 level is decreased in periodontal disease. The results suggested a possible role of IL-38 in the periodontal inflammation process. Clarifying the mechanisms of IL-38 in the inflammatory process may contribute to the development of novel treatment strategies in periodontal diseases.

Evaluation of IL-38, a Newly-introduced Cytokine, in Sera of Vitiligo Patients and Its Relation to Clinical Features

INTRODUCTION

Vitiligo is thought to be an autoimmune disorder caused by melanocytes dysfunction and depigmentation. Among different executors of the immune system in developing the disease, the role of various cytokines has been defined.

OBJECTIVES

We have focused on IL-38, the tenth member of IL-1 cytokine family with a proposed anti-inflammatory role, which has not hitherto been introduced as an anti-inflammatory factor in vitiligo.

METHODS

Sixty-nine generalized vitiligo patients and 72-year-old- and sex-matched healthy individuals were included in this study. IL-38 level was evaluated in sera of all participants using ELISA assay. The relation of IL-38 level to patients characteristics was evaluated.

RESULTS

IL-38 serum level in vitiligo patients (159.5±39.7 pg/ml) was lower than the healthy controls (166.7±34.8pg/ml) (P = 0.039). A weak negative correlation between the age of male patients and their IL-38 serum levels was identified (r = 0.38, P = 0.058). Evaluation of the IL-38 serum levels relationship with patients clinical characteristics showed no correlation with disease onset, stage of depigmentation, and disease activity status.

CONCLUSIONS

The lower levels of IL-38 as an anti-inflammatory cytokine support the inflammatory nature of vitiligo. It indicates the difference of IL-38 in sera of vitiligo patients and healthy controls, as the first report of the lower level of this cytokine in the context of vitiligo. The reason of this difference remains to be clarified; as there are not sufficient study reports revealing the role of gender, ethnicity and inflammation on the cytokine network in the context of vitiligo.

Regulatory T cells in lung disease and transplantation

Pulmonary disease can refer to the disease of the lung itself or the pulmonary manifestations of systemic diseases, which are often connected to the malfunction of the immune system. Regulatory T (Treg) cells have been shown to be important in maintaining immune homeostasis and preventing inflammatory damage, including lung diseases. Given the increasing amount of evidence linking Treg cells to various pulmonary conditions, Treg cells might serve as a therapeutic strategy for the treatment of lung diseases and potentially promote lung transplant tolerance. The most potent and well-defined Treg cells are Foxp3-expressing CD4+ Treg cells, which contribute to the prevention of autoimmune lung diseases and the promotion of lung transplant rejection. The protective mechanisms of Treg cells in lung disease and transplantation involve multiple immune suppression mechanisms. This review summarizes the development, phenotype and function of CD4+Foxp3+ Treg cells. Then, we focus on the therapeutic potential of Treg cells in preventing lung disease and limiting lung transplant rejection. Furthermore, we discussed the possibility of Treg cell utilization in clinical applications. This will provide an overview of current research advances in Treg cells and their relevant application in clinics.

Correlations between IL-36 family cytokines in peripheral blood and subjective and objective assessment results in patients with allergic rhinitis

BACKGROUND

Interleukin (IL)-36 family cytokines have received increasing attention, especially in the fields of inflammation and immunity research. However, whether IL-36 family cytokine levels are correlated with the results of the assessment of allergic rhinitis (AR) and affect the severity of AR remains unknown. Therefore, this study aimed to investigate the correlations between IL-36 family cytokine levels and subjective and objective assessment results and to further analyze the possible mechanisms of IL-36 family cytokines in the development of AR.

METHODS

An enzyme-linked immunosorbent assay (ELISA) was used to detect the concentrations of the IL-36 family cytokines IL-36α, IL-36β, IL-36γ, IL-36Ra, and IL-38 in the peripheral blood of patients with AR. The condition of patients with AR was assessed by 22-item sino-nasal outcome test (SNOT-22) score, visual analogue scale (VAS) scores for disease severity, and serum inhalant allergen immunoglobulin E (IgE) detection. Correlations between IL-36 family cytokine levels and subjective and objective assessment results in patients with AR were analyzed.

RESULTS

The concentration of IL-36α in the peripheral blood of patients with AR was the highest, and the concentration of IL-36β was the lowest. The concentration of IL-36α was higher in juvenile patients than in adult patients, and there was a difference in the IL-36Ra level between the perennial allergen group and the seasonal allergen group. There was a positive correlation between IL-36α level and IL-36γ level, IL-36γ level and IL-36Ra level, and IL-36Ra level and IL-38 level, and IL-36β level was positively correlated with IL-36Ra and IL-38 levels, respectively. IL-36α level was positively correlated with VAS score for nasal congestion symptom. IL-36β level was positively correlated with the total VAS score for ocular symptoms and VAS scores for ocular itching and eye pain symptoms. However, there was no correlation between the levels of all cytokines in IL-36 family and SNOT-22 score, the number of positive inhaled allergens, or the highest positive intensity of allergen specific immunoglobulin E (sIgE).

CONCLUSION

Peripheral blood IL-36 family cytokines play an important role in AR, and the concentrations of IL-36α and IL-36β were related to the severity of symptoms in patients with AR.

Serum interleukin-38 and -41 levels as candidate biomarkers in male infertility

BACKGROUND

Interleukin (IL)-38 and IL-41 are novel cytokines, but their role in male infertility (MI) is unknown. The purpose of this study was to measure the levels of serum IL-38 and IL-41 in patients with MI and correlate these levels with semen indexes.

METHODS

Eighty-two patients with MI and 45 healthy controls (HC) were recruited for this study. Semen parameters were detected using computer-aided sperm analysis, Papanicolaou staining, ELISA, flow cytometry, peroxidase staining and enzyme methods. Serum IL-38 and IL-41 levels were determined by ELISA.

RESULTS

Serum IL-38 levels were decreased (P < 0.01) in patients with MI compared with HC. Serum IL-41 levels were significantly higher in patients with MI than in HC (P < 0.0001). In patients with MI, serum IL-38 levels were positively correlated with semen white blood cell counts (r = 0.29, P = 0.009), and there was a positive correlation between semen white blood cell counts and sperm concentration (r = 0.28, P = 0.0100) and seminal plasma elastase (r = 0.67, P < 0.0001). Receiver operating characteristic curve analysis showed that the area under the curve of IL-38 for diagnosing MI was 0.5637 (P > 0.05), and the area under the curve of IL-41 for diagnosing MI was 0.7646 (P < 0.0001).

CONCLUSIONS

Serum IL-38 levels were significantly lower, and serum IL-41 levels were higher in patients with MI. These results suggest that IL-38 and IL-41 may be novel biomarkers for the diagnosis of MI.

Association between IL-38 and inflammatory indicators in patients with bacterial pneumonia

BACKGROUND

IL-38, a recently discovered cytokine of IL-1 family, exerts immunoregulatory activities in multi-type inflammatory diseases. However, its expression level and underlying clinical importance for IL-38 in respiratory bacterial infections remain unknown.

METHODS

Thirty-five patients with bacterial pneumonia and twenty age- and gender- matched healthy individuals were enrolled in the study to determine serum IL-38 concentrations by ELISA. Then, the correlation between serum IL-38 levels and clinical features were analyzed and ROC curve was used to evaluate the potential diagnostic value for bacterial infections. In vitro, LPS-stimulated human respiratory epithelial cell model was employed to explore immunomodulatory mechanism of IL-38 in pulmonary infections.

RESULTS

Elevated serum levels of IL-38 were determined in patients with bacterial pneumonia when compared with healthy controls. In addition, serum IL-38 levels were negatively correlated with clinical inflammation parameters, including WBC count, CRP, PCT and proinflammatory IL-6 and IL-8. In vitro, we demonstrated that recombinant IL-38 was able to remarkably inhibit expression of proinflammatory IL-6, IL-8, IL-1β and TNF-α as well as adhesion molecule ICAM-1, which were partially mediated by attenuated activation of STAT3 and NF-κB signal cascades in BEAS-2B cells. Furthermore, we identified the diagnostic efficiency of IL-38 in discriminating patients with bacterial pneumonia from healthy individuals.

CONCLUSIONS

Our study indicates higher serum IL-38 levels in patients with bacterial pneumonia are involved in anti-inflammatory activities in respiratory infections revealing a critical role of IL-38 in attenuating excessive pulmonary inflammation against exogenous pathogens. More importantly, IL-38 exhibited a potential novel biomarker for bacterial pneumonia. Thus, our data may provide useful insights for both clinical and basic research for bacterial pneumonia diagnosis.

Serum interleukin 38 (IL-38) as a new potential biomarker of pediatric asthma

Background

Bronchial asthma is considered the most prevalent chronic respiratory disease worldwide and is one of the main causes of hospitalization in the pediatric population. Serum interleukin 38 (IL-38) levels are elevated in several inflammatory and autoimmune diseases. However, its exact role in the pathogenesis of these diseases is unclear.

Objectives

To investigate the role of IL-38 as a potential biomarker in pediatric patients with bronchial asthma.

Methods

Serum IL-38 levels were measured in 73 pediatric patients with bronchial asthma (34 atopic and 39 non-atopic) and 30 age- and sex-matched healthy control subjects using enzyme-linked immunosorbent assay.

Results

Serum IL-38 levels were significantly higher in patients with bronchial asthma compared to the control group (p < 0.001). A significant negative correlation was found between serum IL-38 levels and both relative and absolute eosinophilic counts in the atopic group (R = −0.575, p < 0.001 and R = −0.474, p = 0.005, respectively).

Conclusion

IL-38 could be a useful prognostic and therapeutic biomarker of atopic asthma in pediatric patients.

Interleukin-38 in atherosclerosis

Chronic inflammation caused by immune cells and their mediators is a characteristic of atherosclerosis. Interleukin-38 (IL-38), a member of the IL-1 family, exerts multiple anti-inflammatory effects via specific ligand-receptor interactions. Upon recognizing a specific receptor, IL-38 restrains mitogen-activated protein kinase (MAPK), nuclear factor kappa B (NK-κB), or other inflammation-related signaling pathways in inflammatory disease. Further research has shown that IL-38 also displays anti-atherosclerotic effects and reduces the occurrence and risk of cardiovascular events. On the one hand, IL-38 can regulate innate and adaptive immunity to inhibit inflammation, reduce pathological neovascularization, and inhibit apoptosis. On the other hand, it can curb obesity, reduce hyperlipidemia, and restrain insulin resistance to reduce cardiovascular disease risk. Therefore, this article expounds on the vital function of IL-38 in the development of atherosclerosis to provide a theoretical basis for further in-depth studies of IL-38 and insights on the prophylaxis and treatment of atherosclerosis.

IL-38, a potential therapeutic agent for lupus, inhibits lupus progression

BACKGROUND

Previous studies reported that IL-38 was abnormally expressed in patients with systemic lupus erythematosus (SLE). However, the involvement of IL-38 in the pathophysiology of SLE remains unknown.

METHODS

The therapeutic potential of IL-38 was tested in pristane-treated wild-type (WT) and IL-38^-/- mice. Thus, SLE was induced via pristane in WT and IL-38^-/- mice. Afterwards, the liver, spleen, and kidney of each mouse were obtained. The flow cytometric analysis of the immune cells, serologic expression of inflammatory cytokines and autoantibodies, renal histopathology, and inflammatory signaling were evaluated.

RESULTS

WT mice with pristane-induced lupus exhibited hepatomegaly, splenomegaly, severe kidney damages, increased lymphoproliferation, enhanced lymphoproliferation, and upregulated inflammatory cytokines, such as IL-6, IL-13, IL-17A, MIP-3α, IL-12p70, and IFNγ, and elevated levels of autoantibodies, such as ANA IgG, anti-dsDNA IgG, and total IgG. IL-38^-/- mice whose lupus progressed, had elevated cells of CD14⁺, CD19⁺, CD3⁺, and Th1, upregulated inflammatory cytokines and autoantibodies, and severe pathological changes in kidney. Administration of recombinant murine IL-38 to pristane-treated IL-38^-/- mice improved their renal histopathology, which depended on ERK1/2, JNK1/2, p38, NF-κB p65, and STAT5 signaling pathways.

CONCLUSION

IL-38 regulates SLE pathogenesis. Furthermore, targeting IL-38 is critical in the treatment of SLE.

Diverse Control Mechanisms of the Interleukin-1 Cytokine Family

The majority of interleukin-1 (IL-1) family cytokines lack amino terminal secretion signals or transmembrane domains for secretion along the conventional biosynthetic pathway. Yet, these factors must be translocated from the cytoplasm across the plasma membrane into the extracellular space in order to regulate inflammation. Recent work has identified an array of mechanisms by which IL-1 family cytokines can be released into the extracellular space, with supramolecular organizing centers known as inflammasomes serving as dominant drivers of this process. In this review, we discuss current knowledge of the mechanisms of IL-1 family cytokine synthesis, processing, and release from cells. Using this knowledge, we propose a model whereby host metabolic state dictates the route of IL-1β secretion, with implications for microbial infection and sterile inflammation.

Study effect of probiotics and prebiotics on treatment of OVA-LPS-induced of allergic asthma inflammation and pneumonia by regulating the TLR4/NF-kB signaling pathway

Asthma is a common respiratory disease, and immune system dysregulation has direct relevance to asthma pathogenesis. Probiotics and prebiotics have immunomodulatory effects and can regulate immune responses and may attenuate allergic reactions. Therefore, in this study, we explored the role of probiotics and prebiotics in regulating acute airway inflammation and the TLR4/NF-kB pathway. Allergic asthma model of BALB/c mice was produced and treated with probiotics (LA-5, GG, and BB-12) and prebiotics (FOS and GOS). Then AHR, BALF cells count, EPO activity, IL-4, 5, 13, 17, 25, 33, as well as IFN-γ, total and OVA-specific IgE, IgG1, Cys-LT, LTB4, LTC4, and TSLP levels were measured. Also, the GTP/GOT assay was performed and gene expression of Akt, NLR3, NF-kB, PI3K, MyD88, TLR4, CCL11, CCL24, MUC5a, Eotaxin, IL-38, and IL-8 were determined. Finally, lung histopathological features were evaluated. Treatment with probiotics could control AHR, eosinophil infiltration to the BALF and reduce the levels of immunoglobulins, IL-17, GTP and also decrease mucus secretion, goblet cell hyperplasia, peribronchial and perivascular inflammation and also, EPO activity. It could reduce gene expression of TLR4 and CCL11. On the other hand, IL-38 gene expression was increased by both probiotic and prebiotic treatment. Treatment with probiotics and prebiotics could control levels of IL-4, 5, 13, 25, 33, leukotrienes, the gene expression of AKT, NLR3, NF-κB, MyD88, MUC5a. The prebiotic treatment could control peribronchial inflammation and PI3K gene expression. Both of the treatments had no significant effect on the GOT, TSLP and IL-8, eotaxin and CCL24 gene expression. Probiotics and prebiotics could induce tolerance in allegro-inflammatory reactions and alter immune responses in allergic conditions. Probiotics could also modulate cellular and humoral immune responses and prevent allergic disorders.

An overview of the biological and multifunctional roles of IL-38 in different infectious diseases and COVID-19

Undoubtfully, the normal immune system can make a potential response to variable pathogens and neutralize or kill them depending on the type of infection through innate and acquired immunity. Cytokines have poly-peptide nature and are considered as signaling molecules that could amplify or alleviate immune responses besides their other biological functions. Interleukin 38 (IL-38) is a member of the IL-1 family cytokine that, however, its anti-inflammatory role has been observed in different autoimmune diseases like systemic lupus erythematosus (SLE), psoriasis, and Sjogren’s syndrome; there is a controversy about the cytokine pro-inflammatory function. In the current review, we skimmed IL-38 structure, signaling mechanism, and its immunological functions, IL-38-producing immune cells. Also, we argued about the role of this cytokine in viral infections including hepatitis B (HBV), hepatitis C (HCV), influenza (Flu), and COVID-19. Also, it illustrated the IL-38 protective effects on sepsis. Moreover, we explained the modulatory role of IL-38 in the COVID-19 cytokine storm.

Serum levels of novel anti-inflammatory cytokine Interleukin-38 in diabetes patients infected with latent tuberculosis (DM-LTB-3)

IL-38 is a recently discovered, novel anti-inflammatory cytokine, which belongs to the IL-1β family. The role played by this cytokine in diabetes-tuberculosis nexus is not known. Serum levels of IL-38, TNF-α, IL-6, and IL-1β in Normal Glucose Tolerance (NGT) and chronic Diabetes (DM) subjects, both with and without latent tuberculosis (LTB) (n = 256) were quantified by ELISA. While, serum levels of IL-38 were significantly reduced, the levels of TNF-α, IL-6, and IL-1β were not altered, in LTB infected diabetes patients. While no significant secretion of IL-38 was detected in the quantiferon supernatant, secretion of TNF-α, IL-6, and IL-1β was significantly reduced in LTB infected diabetes patients. The decreased systemic levels of IL-38 and reduced in vitro secretion of other pro-inflammatory cytokines might represent a crucial pathway associated with diabetes-tuberculosis nexus.

Immunobiological Properties and Clinical Applications of Interleukin-38 for Immune-Mediated Disorders: A Systematic Review Study

Exponential growth in the usage of "cytokines" (as seroimmunobiomarkers) has facilitated more accurate prognosis, early diagnosis, novel, and efficient immunotherapeutics. Numerous studies have reported immunopathophysiological and immunopathological processes of interleukin-38 (IL-38). Therefore, in this systematic review article, the authors aimed to present an updated comprehensive overview on the immunobiological mechanisms, diagnostic, and immune gene-based therapeutic potentials of IL-38. According to our inclusion and exclusion criteria, a total of 216 articles were collected from several search engines and databases from the January 2012 to July 2021 time interval by using six main keywords. Physiologic or pathologic microenvironments, optimal dosage, and involved receptors affect the functionalities of IL-38. Alterations in serum levels of IL-38 play a major role in the immunopathogenesis of a wide array of immune-mediated disorders. IL-38 shows anti-inflammatory activities by reduction or inhibition of pro-inflammatory cytokines, supporting the therapeutic aspects of IL-38 in inflammatory autoimmune diseases. According to the importance of pre-clinical studies, it seems that manipulation of the immune system by immunomodulatory properties of IL-38 can increase the accuracy of diagnosis, and decipher optimal clinical outcomes. To promote our knowledge, more collaboration is highly recommended among laboratory scientists, internal/infectious diseases specialists, oncologists, immunologists, diseases-specific biomarkers scientists, and basic medical researchers.

The interleukin-1 cytokine family members: Role in cancer pathogenesis and potential therapeutic applications in cancer immunotherapy

The interleukin-1 (IL-1) family is one of the first described cytokine families and consists of eight cytokines (IL-1β, IL-1α, IL-18, IL-33, IL-36α, IL-36β, IL-36γ and IL-37) and three receptor antagonists (IL-1Ra, IL-36Ra and IL-38). The family members are known to play an essential role in inflammation. The importance of inflammation in cancer has been well established in the past decades. This review sets out to give an overview of the role of each IL-1 family member in cancer pathogenesis and show their potential as potential anticancer drug candidates. First, the molecular structure is described. Next, both the pro- and anti-tumoral properties are highlighted. Additionally, a critical interpretation of current literature is given. To conclude, the IL-1 family is a toolbox with a collection of powerful tools that can be considered as potential drugs or drug targets.

IL-36 cytokines in inflammatory and malignant diseases: not the new kid on the block anymore

The IL-36 family of cytokines were first identified in 2000 based on their sequence homology to IL-1 cytokines. Over subsequent years, the ability of these cytokines to either agonise or antagonise an IL-1R homologue, now known as the IL-36 Receptor (IL-36R), was identified and these cytokines went through several cycles of renaming with the current nomenclature being proposed in 2010. Despite being identified over 20 years ago, it is only during the last decade that the function of these cytokines in health and disease has really begun to be appreciated, with both homeostatic functions in wound healing and response to infection, as well as pathological functions now ascribed. In the disease context, over activation of IL-36 has now been associated with many inflammatory diseases including Psoriasis and inflammatory bowel diseases, with roles in cancer also now being investigated. This review summarises the current knowledge of IL-36 biology, its role in inflammatory diseases and focuses on an emerging role for IL-36 in cancer.

The elevated expression of IL-38 serves as an anti-inflammatory factor in osteoarthritis and its protective effect in osteoarthritic chondrocytes

The objective of this study is to investigate the role of IL-38 in osteoarthritis (OA). IL-38 levels in serum and synovial fluid (SF) of patients with OA were examined to identify the correlation between IL-38 expression and OA activity and to determine its anti-inflammatory effects in IL-1β-induced chondrocytes. A total of 75 patients with OA who underwent joint replacement surgery and 25 age- and sex-matched healthy volunteers were recruited. The levels of IL-38 in serum and SF are shown to be significant elevated in OA patients compared with that of healthy controls. Serum and SF IL-38 levels of OA patients are positively correlated with Kellgren-Lawrence (K-L) grades 2 to 3, as well as with pro-inflammatory cytokines IL-6, IL-23, and TNF-α, but are negatively correlated with the anti-inflammatory cytokine IL-10 in K-L grades 3 to 4. Furthermore, overexpression of IL-38 in vitro is shown to attenuate the expression of pro-inflammatory cytokines such as COX-2, IL-6, IL-8, IL-36Ra, IL-36α/β/γ, iNOS, and TNF-α, as well as matrix degrading enzymes such as MMP3, MMP13, and ADAMTS5, and apoptosis-related indicators Bax/Bcl-2, cleaved caspase 3/pro-caspase 3, and cleaved caspase 9/pro-caspase 9. IL-38 overexpression also reduces expression of the signaling proteins p-p38, p-p65, p-JNK, and RhoA significantly. Taken together, our results show that expression of IL-38 is increased in OA tissues and OA rat chondrocytes, and is positively correlated with early disease activity. This increased IL-38 expression lead to the inactivation of MAPK, NF-κB, JNK, and RhoA signaling pathways, which might have impletion on OA chondrocytes apoptosis, degradation and inflammatory effect. Thus, IL-38 probably serves as a novel therapeutic target for the treatment of OA.

Biology of interleukin-38 and its role in chronic inflammatory diseases

Interleukin (IL)-38 is the tenth member of the IL-1 cytokine family. IL-38 shares high similarity with IL-36Ra and IL-1Ra and can bind to their receptors, thus exerting an anti-inflammatory effect. Despite the lack of a signal peptide, IL-38 can be released from several cell types, but its maturation process remains obscure. The role of IL-38 in numerous inflammatory diseases, especially in autoimmune diseases, has been extensively studied. In this review, we discuss the characteristics, biological functions and pathways of IL-38, as well as its role in several chronic inflammatory diseases. Better understanding the role of IL-38 will pave the way for clinical treatments in the near future.

Interleukin-38 ameliorates poly(I:C) induced lung inflammation: therapeutic implications in respiratory viral infections

Interleukin-38 has recently been shown to have anti-inflammatory properties in lung inflammatory diseases. However, the effects of IL-38 in viral pneumonia remains unknown. In the present study, we demonstrate that circulating IL-38 concentrations together with IL-36α increased significantly in influenza and COVID-19 patients, and the level of IL-38 and IL-36α correlated negatively and positively with disease severity and inflammation, respectively. In the co-cultured human respiratory epithelial cells with macrophages to mimic lung microenvironment in vitro, IL-38 was able to alleviate inflammatory responses by inhibiting poly(I:C)-induced overproduction of pro-inflammatory cytokines and chemokines through intracellular STAT1, STAT3, p38 MAPK, ERK1/2, MEK, and NF-κB signaling pathways. Intriguingly, transcriptomic profiling revealed that IL-38 targeted genes were associated with the host innate immune response to virus. We also found that IL-38 counteracts the biological processes induced by IL-36α in the co-culture. Furthermore, the administration of recombinant IL-38 could mitigate poly I:C-induced lung injury, with reduced early accumulation of neutrophils and macrophages in bronchoalveolar lavage fluid, activation of lymphocytes, production of pro-inflammatory cytokines and chemokines and permeability of the alveolar-epithelial barrier. Taken together, our study indicates that IL-38 plays a crucial role in protection from exaggerated pulmonary inflammation during poly(I:C)-induced pneumonia, thereby providing the basis of a novel therapeutic target for respiratory viral infections.

Human recombinant interleukin-38 suppresses inflammation in mouse models of local and systemic disease

Interleukin (IL)-38 belongs to the IL-1 family and is part of the IL-36 subfamily due to its binding to the IL-36 Receptor (IL-1R6). In the current study, we assessed the anti-inflammatory properties of IL-38 in murine models of arthritis and systemic inflammation. First, the anti-inflammatory properties of mouse and human IL-38 precursors were compared to forms with a truncated N-terminus. In mouse bone marrow derived dendritic cells (BMDC), human and mouse IL-38 precursors with a truncation of the two N-terminal amino acids (3-152) suppressed LPS-induced IL-6. Recombinant human IL-38 (3-152) was further investigated for its immunomodulatory potential using four murine models of inflammatory disease: streptococcal cell wall (SCW)-induced arthritis, monosodium urate (MSU) crystal-induced arthritis, MSU crystal-induced peritonitis, and systemic endotoxemia. In each of these models IL-38 significantly reduced inflammation. In SCW and MSU crystal-induced arthritis, joint swelling, inflammatory cell influx, and synovial levels of IL-1β, IL-6, and KC were reduced by 50% or greater. These suppressive properties of IL-38 in SCW-induced arthritis were independent of the anti-inflammatory co-receptor IL-1R8, as IL-38 reduced arthritis equally in IL-1R8 deficient and WT mice. In MSU crystal-induced peritonitis, IL-38 reduced hypothermia, while plasma IL-6 and KC and peritoneal KC levels were reduced by 65-70%. In the LPS endotoxemia model, IL-38 pretreatment reduced systemic IL-6, TNFα and KC. Furthermore, in ex vivo cultured bone marrow, LPS-induced IL-6, TNFα and KC were reduced by 75-90%. Overall, IL-38 exhibits broad anti-inflammatory properties in models of systemic and local inflammation and therefore may be an effective cytokine therapy.

Reduced concentrations of the B cell cytokine interleukin 38 are associated with cardiovascular disease risk in overweight subjects

The IL‐1 family member IL‐38 (IL1F10) suppresses inflammatory and autoimmune conditions. Here, we report that plasma concentrations of IL‐38 in 288 healthy Europeans correlate positively with circulating memory B cells and plasmablasts. IL‐38 correlated negatively with age (p = 0.02) and was stable in 48 subjects for 1 year. In comparison with primary keratinocytes, IL1F10 expression in CD19⁺ B cells from PBMC was lower, whereas cell‐associated IL‐38 expression was comparable. In vitro, IL‐38 is released from CD19⁺ B cells after stimulation with rituximab. Intravenous LPS in humans failed to induce circulating IL‐38, compared to 100‐fold induction of IL‐6 and IL‐1 receptor antagonist. In a cohort of 296 subjects with body mass index > 27 at high risk for cardiovascular disease, IL‐38 plasma concentrations were significantly lower than in healthy subjects (p < 0.0001), and lowest in those with metabolic syndrome (p < 0.05). IL‐38 also correlated inversely with high sensitivity C‐reactive protein (p < 0.01), IL‐6, IL‐1Ra, and leptin (p < 0.05). We conclude that a relative deficiency of the B cell product IL‐38 is associated with increased systemic inflammation in aging, cardiovascular and metabolic disease, and is consistent with IL‐38 as an anti‐inflammatory cytokine.

Roles of novel IL-1 family (IL-36, IL-37, and IL-38) members in chronic brucellosis

The secretion of interleukin (IL)-1 family cytokines is one of the most potent and earliest pro-inflammatory responses triggered by brucellosis. However, the roles of the most recently discovered IL-1 family members, IL-36, IL-37, and IL-38, in the transition into the chronic form of brucellos is remain largely unknown. Therefore, in this study, the roles of IL-36, IL-37, and IL-38 in brucella infections and their effects on the transition from the acute to chronic form of the disease were investigated. Using peripheral blood samples from 40 patients with acute brucellosis, 40 patients with chronic brucellosis, and 40 healthy control subjects, we analysed the serum concentrations of secreted IL-36, IL-37, and IL-38 using ELISA. The findings were confirmed by using RT-qPCR to analyse the mRNA levels of the genes encoding IL-36, IL-37, and IL-38 in peripheral blood mononuclear cells (PBMCs) from 10 randomly selected patients from each of the three groups. Our results showed that serum IL-37 (p < 0.001) and IL-38 (p < 0.001) concentrations were lower in patients with brucellosis than in the healthy controls. In addition, serum IL-37 and IL-38 concentrations were higher in the chronic patient group than in the acute patient group. The mRNA expression levels of IL-37 and IL1F10, genes that encode IL-38, did not affect serum cytokine secretion levels. This result suggests that the high secretion levels of IL-37 and IL-38 may be related to the progression into the chronic form of brucellosis. Our findings will aid in clarifying the mechanism of the transition of brucellosis from the acute to the chronic form of the disease.

Interleukin-38 promotes tumor growth through regulation of CD8+ tumor-infiltrating lymphocytes in lung cancer tumor microenvironment

BACKGROUND

Interleukin (IL)-38 was discovered in 2001 and is a member of the IL-1 family of cytokines. IL-38 shows anti-inflammatory activity in several inflammatory diseases. In lung adenocarcinoma, we previously demonstrated that high IL-38 expression in tumor cells was associated with poor prognosis. However, the role of IL-38 in the tumor microenvironment has not been clarified.

METHODS

IL-38-plasmid-transfected Lewis lung carcinoma cells (LLC-IL38) and empty vector-transfected LLC cells (LLC-vector) were established. Cell proliferation in vitro and tumor growth in vivo were examined, and immunohistochemical staining was used to assess tumor-infiltrating lymphocytes (TILs). A CD8⁺ lymphocyte depletion model was established to show the association between IL-38 and CD8⁺ lymphocytes. Moreover, we examined the association between IL-38 expression and CD8⁺ TILs in human samples, analyzing immunohistochemical staining in 226 patients with radically resected lung adenocarcinoma.

RESULTS

Tumor growth of LLC-IL38 in vivo was significantly increased compared with that of LLC-vector, although cell proliferation of LLC-IL38 in vitro was lower than that of LLC-vector. CD8⁺ TILs were significantly decreased in LLC-IL38 tumor compared with LLC-vector tumor. The difference in tumor growth between LLC-IL38 and LLC-vector became insignificant after depletion of CD8⁺ lymphocytes. In immunohistochemical staining in tissues from patients with lung adenocarcinoma, multivariate analysis showed high IL-38 expression was an independent negative predicter of high density of CD8⁺ TILs.

CONCLUSION

We demonstrated that high IL-38 expression in tumor cells was significantly associated with reduction of CD8⁺ TILs and tumor progression. These results suggest that IL-38 could be a therapeutic target for lung cancer.

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.

Anti-inflammatory mechanisms of the novel cytokine interleukin-38 in allergic asthma

We elucidated the anti-inflammatory mechanisms of IL-38 in allergic asthma. Human bronchial epithelial cells and eosinophils were cocultured upon stimulation with the viral RLR ligand poly (I:C)/LyoVec or infection-related cytokine TNF-α to induce expression of cytokines/chemokines/adhesion molecules. House dust mite (HDM)-induced allergic asthma and humanized allergic asthma NOD/SCID murine models were established to assess anti-inflammatory mechanisms in vivo. IL-38 significantly inhibited induced proinflammatory IL-6, IL-1β, CCL5, and CXCL10 production, and antiviral interferon-β and intercellular adhesion molecule-1 expression in the coculture system. Mass cytometry and RNA-sequencing analysis revealed that IL-38 could antagonize the activation of the intracellular STAT1, STAT3, p38 MAPK, ERK1/2, and NF-κB pathways, and upregulate the expression of the host defense-related gene POU2AF1 and anti-allergic response gene RGS13. Intraperitoneal injection of IL-38 into HDM-induced allergic asthma mice could ameliorate airway hyperreactivity by decreasing the accumulation of eosinophils in the lungs and inhibiting the expression of the Th2-related cytokines IL-4, IL-5, and IL-13 in the bronchoalveolar lavage fluid (BALF) and lung homogenates. Histological examination indicated lung inflammation was alleviated by reductions in cell infiltration and goblet cell hyperplasia, together with reduced Th2, Th17, and innate lymphoid type 2 cell numbers but increased proportions of regulatory T cells in the lungs, spleen, and lymph nodes. IL-38 administration suppressed airway hyperreactivity and asthma-related IL-4 and IL-5 expression in humanized mice, together with significantly decreased CCR3+ eosinophil numbers in the BALF and lungs, and a reduced percentage of human CD4+CRTH2+ Th2 cells in the lungs and mediastinal lymph nodes. Together, our results demonstrated the anti-inflammatory mechanisms of IL-38 and provided a basis for the development of a regulatory cytokine-based treatment for allergic asthma.

Interleukin-38 is elevated in inflammatory bowel diseases and suppresses intestinal inflammation

There has been no report investigating the role of IL-38 in inflammatory bowel diseases (IBD). Therefore, we investigated the expression of IL-38 in IBD patients and its role in regulating intestinal inflammation. The levels of IL-38 were significantly elevated in the intestine of IBD patients and DSS-induced colitis mice. Immunofluorescence analysis revealed that B cell, not macrophage or T cell, was the source of IL-38 in the intestine. We found that rIL-38 treatment significantly attenuated DSS-induced colitis, including alleviation of weight loss, disease activity index, macroscopic changes and histological damage of colon, along with lower levels of IL-1β and TNF-α. In vitro, rIL-38 significantly decreased the expression of proinflammatory cytokines in LPS-stimulated RAW 264.7 cells and BMDM. This is the first study suggesting that IL-38 may have a protective effect in IBD, which inhibits the production of proinflammatory cytokines from macrophages. IL-38 may represent a promising therapeutic strategy in IBD.

Interleukin-38 protects against sepsis by augmenting immunosuppressive activity of CD4+ CD25+ regulatory T cells

Naturally occurring CD4⁺ CD25⁺ regulatory T cells (Tregs) are required to limit immune-induced pathology and to maintain homeostasis during the early-phase of sepsis. This study aimed to investigate the role of interleukin (IL)-38, a newly described member of the IL-1 cytokine family, in mediated immune response of CD4⁺ CD25⁺ Tregs in sepsis. Here, we provide evidence that expressions of IL-38 and its receptor were detected in murine CD4⁺ CD25⁺ Tregs. Stimulation of CD4⁺ CD25⁺ Tregs with LPS markedly up-regulated the expression of IL-38. Treatment with rmIL-38 dramatically enhanced the immunosuppressive activity of CD4⁺ CD25⁺ Tregs after LPS stimulation and in septic mice induced by CLP, resulting in amplification of helper T cell (Th) 2 response and reduction in the proliferation of effector T cells. These effects were robustly abrogated when anti-IL-38 antibody was administered. Administration of rmIL-38 improved the survival rate of CLP mice. In addition, CD4⁺ CD25⁺ Tregs depletion before the onset of sepsis obviously abolished IL-38-mediated protective response. These findings suggest that IL-38 enhances the immunosuppressive activity of CD4⁺ CD25⁺ Tregs, which might contribute to the improvement of host immune function and prognosis in the setting of sepsis.

Dexamethasone alleviate allergic airway inflammation in mice by inhibiting the activation of NLRP3 inflammasome

Dexamethasone (DEX) is the mainstay treatment for asthma, which is a common chronic airway inflammation disease. However, the mechanism of DEX resolute symptoms of asthma is not completely clear. Here, we aimed to analyze the effect of DEX on airway inflammation in OVA-induced mice and whether this effect is related to the inhibition of the activation of NLRP3 inflammasome. Female (C57BL/6) mice were used to establish the allergic airway inflammation model by inhalation OVA. The number of inflammatory cells in the bronchi alveolar lavage fluid (BALF) was counted by Swiss-Giemsa staining, and the contents of IL-1β, IL-18, IL-5 and IL-17 were detected by ELISA. The degree of inflammatory cells infiltration and mucous cells proliferation in lung tissue were separately observed by H&E and PAS staining. The proteins expression of NLRP3, pro-caspase-1, caspase-1, IL-1β, IL-6 and IL-17 in lung tissue were detected by Western blotting. We found that DEX significantly inhibited OVA-induced inflammatory cells infiltration, airway mucus secretion and goblet cell proliferation in mice. The total and classified numbers of inflammatory cells and the levels of IL-1β, IL-18, IL-5 and IL-17 in the BALF of the experimental group were significantly lower than those of the model group after DEX treatment. DEX also significantly inhibited the activity of NLRP3 inflammasome and reduced the protein contents of Pro-Caspase-1, Caspase-1, Capase-1/Pro-Caspase-1, IL-1β, IL-6 and IL-17 in lung tissues. Our study suggested that DEX alleviates allergic airway inflammation by inhibiting the activity of NLRP3 inflammasome and the levels of IL-1β and IL-18.

Melatonin biosynthesis restored by CpG oligodeoxynucleotides attenuates allergic airway inflammation via regulating NLRP3 inflammasome

AIMS

Both CpG oligodeoxynucleotide (CpG-ODN) and melatonin have been reported to induce Th1 response and contribute to allergic asthma resistance. Here, we aimed to reveal how they confer such effect as well as whether they crosstalk with each other.

MAIN METHODS

Six-week-old Female C57BL/6 mice were challenged by OVA to induce allergic airway inflammation, and were treated with CpG-ODN, CpG-ODN plus Luzindole or melatonin respectively. Bronchoalveolar lavage fluid (BALF) cellularity was classified and counted by Wright's-Giemsa staining. HE and PAS staining were used to analyze airway inflammation. The levels of IL-4, IL-5, IL-13,GM-CSF and IFN-γ, as well as IL-1β and IL-18 were analyzed by ELISA. Protein expressions of ASMT, AANAT, NLRP3, IL-1β and caspase-1 in lung tissue were detected by Western blotting, expression of ASMT and AANAT were further observed by immunohistochemistry.

KEY FINDINGS

We found that CpG-ODN considerably suppressed OVA-induced airway leukocytes infiltration, goblet cell hyperplasia and Th2 cytokines production. Furthermore, the resolution effect of CpG-ODN on OVA-induced allergic airway inflammation occurred in parallel with decreased-activation of NLRP3 inflammasome and increased biosynthesis of melatonin. Blocking the effect of endogenous melatonin by Luzindole abolished the suppressive effect of CpG-ODN on OVA-induced airway inflammation and activation of NLRP3 inflammasome, suggesting such effect was mediated by endogenous melatonin. Moreover, exogenous melatonin pronouncedly ameliorated airway inflammation and decreased the activation of NLRP3 inflammasome.

SIGNIFICANCE

These results proven that CpG-ODN protects against allergic airway inflammation via suppressing the activation of NLRP3 inflammasome, and such effect may be resulted from the restored-production of melatonin.

Interleukin 30 to Interleukin 40

Cytokines are important molecules that regulate the ontogeny and function of the immune system. They are small secreted proteins usually produced upon activation of cells of the immune system, including lymphocytes and myeloid cells. Many cytokines have been described, and several have been recognized as pivotal players in immune responses and in human disease. In fact, several anticytokine antibodies have proven effective therapeutics, especially in various autoimmune diseases. In the last 15 years, new cytokines have been described, and many remain poorly understood. Among the most recent cytokines discovered are interleukins-30 (IL-30) to IL-40. Several of these are members of other cytokine superfamilies, including several IL-1 superfamily members (IL-33, IL-36, IL-37, and IL-38) as well as several new members of the IL-12 family (IL-30, IL-35, and IL-39). The rest (IL-31, IL-32, IL-34, and IL-40) are encoded by genes that do not belong to any cytokine superfamily. Our aim of this review was to present a concise version of the information available on these novel cytokines to facilitate their understanding by members of the immunological community.

Targeting NLRP3 Inflammasome Activation in Severe Asthma

Severe asthma (SA) is a chronic lung disease characterized by recurring symptoms of reversible airflow obstruction, airway hyper-responsiveness (AHR), and inflammation that is resistant to currently employed treatments. The nucleotide-binding oligomerization domain-like Receptor Family Pyrin Domain Containing 3 (NLRP3) inflammasome is an intracellular sensor that detects microbial motifs and endogenous danger signals and represents a key component of innate immune responses in the airways. Assembly of the NLRP3 inflammasome leads to caspase 1-dependent release of the pro-inflammatory cytokines IL-1β and IL-18 as well as pyroptosis. Accumulating evidence proposes that NLRP3 activation is critically involved in asthma pathogenesis. In fact, although NLRP3 facilitates the clearance of pathogens in the airways, persistent NLRP3 activation by inhaled irritants and/or innocuous environmental allergens can lead to overt pulmonary inflammation and exacerbation of asthma manifestations. Notably, administration of NLRP3 inhibitors in asthma models restrains AHR and pulmonary inflammation. Here, we provide an overview of the pathophysiology of SA, present molecular mechanisms underlying aberrant inflammatory responses in the airways, summarize recent studies pertinent to the biology and functions of NLRP3, and discuss the role of NLRP3 in the pathogenesis of asthma. Finally, we contemplate the potential of targeting NLRP3 as a novel therapeutic approach for the management of SA.

Interleukin 38 Protects Against Lethal Sepsis

Background

Interleukin 38 (IL-38) is the most recently characterized cytokine of the interleukin 1 family. However, its role in sepsis remains unknown.

Methods

Circulating IL-38 levels were measured in 2 cohorts of adult and pediatric patients with sepsis. Using 2 murine models of lipopolysaccharide (LPS)-induced endotoxemia and cecal ligation and puncture (CLP)-induced sepsis, the effects of IL-38 on survival, inflammation, tissue injury, and bacterial clearance were assessed.

Results

Serum IL-38 concentrations were significantly elevated in adult and pediatric patients with sepsis relative to corresponding healthy adult and pediatric controls, respectively. An increased IL-38 level negatively correlated with the number of blood leukocytes and with the level of inflammatory cytokines, including interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) in clinical sepsis. Anti-IL-38 antibody impaired survival and while recombinant IL-38 improved survival in the 2 murine models of LPS-induced endotoxemia and CLP-induced sepsis. IL-38 administration decreased the inflammatory response, as reflected by lower levels of cytokines and chemokines (including IL-6, TNF-α, interleukin 10, interleukin 17, interleukin 27, CXCL1, and CCL2), and less damage to tissues (including lung, liver, and kidney) in CLP-induced sepsis. Furthermore, IL-38 augmented bacterial clearance in CLP-induced polymicrobial sepsis.

Conclusions

These findings suggest that IL-38 attenuates sepsis by decreasing inflammation and increasing bacterial clearance, thus providing a novel tool for antisepsis therapy.

IL-38: A New Player in Inflammatory Autoimmune Disorders

Interleukin (IL)-38, a newly discovered IL-1 family cytokine, is expressed in several tissues and secreted by various cells. IL-38 has recently been reported to exert an anti-inflammatory function by binding to several receptors, including interleukin-36 receptor (IL-36R), interleukin-1 receptor accessory protein-like 1 (IL-1RAPL1), and interleukin-1 receptor 1 (IL-1R1) to block binding with other pro-inflammatory cytokines and inhibit subsequent signaling pathways; thereby regulating the differentiation and function of T cells, peripheral blood mononuclear cells, macrophages, and dendritic cells. Inflammatory autoimmune diseases, which are common immune-mediated inflammatory syndromes, are characterized by an imbalance between T helper cells (Ths), especially Th1s and Th17s, and regulatory T cells (Tregs). Recent findings have shown that abnormal expression of IL-38 in inflammatory autoimmune diseases, such as rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus, primary Sjogren's syndrome, psoriasis, inflammatory bowel disease, hidradenitis suppurativa, ankylosing spondylitis, and glaucoma, involves Th1s, Th17s, and Tregs. In this review, the expression, regulation, and biological function of IL-38 are discussed, as are the roles of IL-38 in various inflammatory autoimmune disorders. Current data support that the IL-38/IL-36R and/or IL-38/IL-1RAPL1 axis primarily play an anti-inflammatory role in the development and resolution of inflammatory autoimmune diseases and indicate a possible therapeutic benefit of IL-38 in these diseases.

Different intensity of autophagy regulate interleukin-33 to control the uncontrolled inflammation of acute lung injury

OBJECTIVES

Cytokines participate in the progression of acute respiratory distress syndrome (ARDS), and uncontrolled inflammation is a central issue of acute lung injury (ALI). Interleukin (IL)-33 is a nuclear protein that has been reported to have a proinflammatory role in ARDS. Studies have shown that excessive autophagy may lead to the increased mortality of patients with ARDS, while several investigations indicated that IL-33 and autophagy interact with one another. The present study sought to clarify the relation between autophagy and IL-33's proinflammatory role in ARDS.

METHODS

We built a lipopolysaccharide (LPS)-induced lung injury mouse model. To study the relationship between IL-33 and autophagy, mice were pretreated with rapamycin (RAPA; a promoter of autophagy) and 3-methyladenine (3-MA; an inhibitor of autophagy) prior to LPS administration. The expression of IL-33 in serum and bronchoalveolar lavage fluid (BALF) was measured. Immunohistochemistry of IL-33 in lung tissue was examined. Th1,Th2 cytokines/chemokine levels in serum and BALF were tested. Further, the severity of lung injury was evaluated. And the nuclear factor-kappa B (NF-κB)'s nuclear translocation in lung tissue was detected.

RESULTS

In comparison with the control group, the levels of IL-33 in serum and BALF were increased after LPS injection. Th1 cytokines/chemokine levels were significantly increased in serum and BALF, while Th2 cytokine levels changed only a little. The levels of IL-33 in serum and BALF of the RAPA group was significantly increased after LPS was injected as compared with the LPS group; additionally, the levels of IL-33 in serum and BALF of the 3-MA group was significantly reduced after LPS was injected as compared with the LPS group, and that lung injury was ameliorated after 3-MA pretreatment. Th1 cytokines and chemokines in both serum and BALF were also decreased in the 3-MA group. Furthermore, we found that the nuclear translocation of NF-κB increased after LPS administration, and NF-κB's nuclear translocation was significantly increased in comparison with the LPS group after RAPA pretreatment. In contrast, NF-κB's nuclear translocation decreased after 3-MA pretreatment as compared with the LPS group.

CONCLUSIONS

These findings showed that autophagy might regulate IL-33 by activating or inhibiting NF-κB to control the uncontrolled inflammation of acute lung injury.

Attenuated Airway Eosinophilic Inflammations in IL-38 Knockout Mouse Model

BACKGROUND

The role of IL-38, a new member of the IL-1 family, in airway eosinophilic inflammatory conditions such as asthma is unclear. To investigate the role of IL-38 in airway eosinophilic inflammation, an IL-38-gene deficient (KO) murine asthma model was analyzed.

METHODS

The numbers of eosinophils and neutrophils, and levels of IL-5, IL-13 and IL-17A protein and mRNA in bronchoalveolar lavage fluid (BALF) and lung tissue were compared between wild-type (WT) and IL-38-KO mice after OVA sensitization and challenge. The effects of additional purified recombinant mouse (rm) IL-38 protein were investigated in the IL-38-KO murine asthma model.

RESULTS

The IL-38 and IL-5 mRNA in WT mice was significantly higher after OVA challenge than after saline challenge (p<0.05). The number of airway eosinophils in IL-38-KO mice was significantly lower than in WT mice after OVA challenge (p<0.01). BALF analysis confirmed the lower number of airway eosinophils in IL-38-KO mice and showed that this was significantly associated with lower IL-5 protein levels (r=0.92, p<0.0001). However, the additional rm IL-38 protein did not neutralize airway eosinophilia in IL-38-KO mice.

CONCLUSION

IL-38 may enhance airway eosinophilic inflammation in asthma through IL-5 induction.

NLRP3 inflammasome: A likely target for the treatment of allergic diseases

Allergic diseases, such as asthma, rhinitis, dermatitis, conjunctivitis, and anaphylaxis, have recently become a global public health concern. According to previous studies, the NLRP3 inflammasome is a multi-protein complex known to be associated with many inflammatory conditions. In response to allergens or allergen/damage-associated molecular signals, NLRP3 changes its conformation to allow the assembly of the NLRP3 inflammasome complex and activates caspase-1, which is an evolutionarily conserved enzyme that proteolytically cleaves other proteins, such as the precursors of the inflammatory cytokines IL-1β and IL-18. Subsequently, active caspase-1 cleaves pro-IL-1 and pro-IL-18. Recently, accumulating human and mouse experimental evidence has demonstrated that the NLRP3 inflammasome, IL-1β, and IL-18 are critically involved in the development of allergic diseases. Furthermore, the application of specific NLRP3 inflammasome inhibitors has been demonstrated in animal models. Therefore, these inhibitors may represent potential therapeutic methods for the management of clinical allergic disorders. This review summarizes findings related to the NLRP3 inflammasome and its related factors and concludes that specific NLRP3 inflammasome inhibitors may be potential therapeutic agents for allergic diseases.

[Serum levels of interleukin-38 and interleukin-1β in the acute phase of Kawasaki disease in children]

OBJECTIVE

To study the expression of serum cytokines, interleukin-38 (IL-38) and interleukin-1β (IL-1β) in the acute phase of Kawasaki disease (KD) in children and the association of IL-38 and IL-1β with inflammatory response in the acute phase and the development of coronary artery lesion (CAL).

METHODS

A total of 40 children with KD who were hospitalized in the hospital between July 2015 and June 2016 were enrolled, with 21 children in the CAL group and 19 in the non-CAL (NCAL) group. Thirty healthy children and 19 children with infection and pyrexia, who were matched for sex and age, were enrolled as healthy control group and pyrexia control group respectively. ELISA was used to measure the serum levels of IL-38 and IL-1β in the 40 children in the acute phase of KD. Spearman's rank correlation analysis was used to investigate the correlations of IL-1β and IL-38 with interleukin-6 (IL-6), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT), N-terminal pro-brain natriuretic peptide (NT-proBNP), triglyceride (TG), and total cholesterol (TC).

RESULTS

The serum level of IL-38 in the children in the acute phase of KD was significantly lower than that in the healthy control group (P<0.05), but significantly higher than that in the pyrexia control group (P<0.05). There was no significant difference in the level of IL-38 between the CAL and NCAL groups (P>0.05). The children in the acute phase of KD had a significantly higher level of IL-1β than the healthy control group (P<0.05), while there was no significant difference between this group and the pyrexia control group (P>0.05). There was also no significant difference in the level of IL-1β between the CAL and NCAL groups (P>0.05). Serum IL-1β and IL-38 levels were not correlated with serum levels of CRP, ESR, PCT, IL-6, and NT-ProBNP or blood lipids (TG and TC) (P>0.05).

CONCLUSIONS

IL-38 is involved in an inflammatory response in the acute phase of KD and may exert an anti-inflammatory effect, which is opposite to the effect of IL-1β to promote inflammatory response. However, there is no significant correlation between these two cytokines and the development of CAL in KD.

Overview of the IL-1 family in innate inflammation and acquired immunity

The interleukin-1 (IL-1) family of cytokines and receptors is unique in immunology because the IL-1 family and Toll-like receptor (TLR) families share similar functions. More than any other cytokine family, the IL-1 family is primarily associated with innate immunity. More than 95% of living organisms use innate immune mechanisms for survival whereas less than 5% depend on T- and B-cell functions. Innate immunity is manifested by inflammation, which can function as a mechanism of host defense but when uncontrolled is detrimental to survival. Each member of the IL-1 receptor and TLR family contains the cytoplasmic Toll-IL-1-Receptor (TIR) domain. The 50 amino acid TIR domains are highly homologous with the Toll protein in Drosophila. The TIR domain is nearly the same and present in each TLR and each IL-1 receptor family. Whereas IL-1 family cytokine members trigger innate inflammation via IL-1 family of receptors, TLRs trigger inflammation via bacteria, microbial products, viruses, nucleic acids, and damage-associated molecular patterns (DAMPs). In fact, IL-1 family member IL-1a and IL-33 also function as DAMPs. Although the inflammatory properties of the IL-1 family dominate in innate immunity, IL-1 family member can play a role in acquired immunity. This overview is a condensed update of the IL-1 family of cytokines and receptors.

Clinical implications of the novel cytokine IL-38 expressed in lung adenocarcinoma: Possible association with PD-L1 expression

Interleukin (IL)-38, a novel member of the IL-1 cytokine family, is homologous to IL-1 receptor antagonist (IL-1Ra) and IL-36Ra, and has been reported to act as an antagonist. IL-38 expression is found in tonsil, placenta, and spleen, and recent studies suggest an association between IL-38 and autoimmune diseases. However, whether IL-38 plays a role in carcinogenesis or cancer growth is unclear. In the present study, we identified increases in IL-38 expression by immunohistochemistry in multiple types of cancer cells. In the examination of 417 surgically resected primary lung adenocarcinomas, Fisher's exact tests showed significant associations between high IL-38 expression and high tumor grades, an advanced T status, advanced N status, advanced stage, and the presence of pleural and vessel invasions. Survival analyses by the Kaplan-Meier method showed that patients with high expression of IL-38 had significantly shorter disease-free survival and shorter overall survival after surgery than patients with low expression of IL-38 (log-rank test: P = 0.0021 and P = 0.0035, respectively). Moreover, programmed cell death-ligand 1 (PD-L1)-positive cases showed higher expression of IL-38 than PD-L1-negative cases (Wilcoxon rank-sum test: P < 0.0001). In conclusion, IL-38 was expressed in tumor cells of various cancers, and IL-38 expression was associated with poor survival of lung adenocarcinoma patients. IL-38 may affect host immunity or the tumor microenvironment, and contribute to the progression of lung adenocarcinoma.

IL-38 overexpression induces anti-inflammatory effects in mice arthritis models and in human macrophages in vitro

OBJECTIVES

Interleukin (IL)-38 is a newly characterised cytokine that belongs to the IL-1 family. This cytokine is expressed in the rheumatoid arthritis (RA) synovial tissue and IL-38 deficient mice have exacerbated arthritis. Here, we analysed the effect of IL-38 overexpression in the joints of arthritic mice, in human macrophages and synovial fibroblasts in vitro.

METHODS

Articular injections of an adeno-associated virus (AAV) 2/8 encoding IL-38 were performed in collagen-induced arthritis (CIA), K/BxN serum transfer-induced arthritis (STIA) and antigen-induced arthritis (AIA) in mice. The effect of IL-38 overexpression was evaluated through clinical scores, immunohistochemistry, microCT, Luminex and RT-qPCR analysis. THP-1 macrophages were transduced with a lentiviral vector to overexpress IL-38.

RESULTS

Clinical inflammatory scores were significantly decreased after AAV IL-38 injection in joints of mice with CIA and STIA, but not AIA. This decrease was accompanied by reduced macrophage infiltration and a decreased expression of Th17 cytokines (IL-17, IL-23, IL-22) and TNFα. However, IL-38 overexpression had no effect on cartilage or bone destruction. In vitro, the THP-1 monocytic cell line expressed less IL-6, TNFα and IL-23 after IL-38 overexpression. Conditioned media from these cells, containing released IL-38, also exert an anti-inflammatory effect on human primary macrophages and synovial fibroblasts from patients with RA.

CONCLUSIONS

This study shows for the first time that IL-38 overexpression attenuates the severity of experimental arthritis. IL-38 may exert its anti-inflammatory effects by decreasing the production of proinflammatory cytokines by macrophages and synovial fibroblasts. This effect can lead to the development of novel treatment strategies in arthritis.

Delivery of adipose-derived mesenchymal stem cells attenuates airway responsiveness and inflammation in a mouse model of ovalbumin-induced asthma

Adipose-derived mesenchymal stem cells (ADMSCs) possess immunomodulation property, yet their therapeutic potential in asthma is unclear. This study aimed to explore the effects of ADMSCs on airway hyperresponsiveness and inflammation in ovalbumin (OVA)-induced asthma models. The underlying mechanism(s) was also examined. BALB/c mice were sensitized with OVA on days 0, 7, and 14, followed by 8-week OVA challenge from day 22. ADMSCs were injected via tail vein on day 21. Animals were measured for airway responsiveness, lung pathology, IgE and cytokine levels in serum, cell composition in bronchoalveolar lavage fluid (BALF), gene expression in the lung, and regulatory T cells (Tregs). We found that delivery of ADMSCs decreased airway responsiveness and eosinophil counts in BALF and reduced infiltration of inflammatory cells and number of mucus-expressing goblet cells in the lung in OVA-challenged mice. OVA-evoked elevation of serum IgE levels and alteration of cytokine production in serum and BALF was significantly prevented by ADMSCs. In addition, administration of ADMSCs impaired the regulation of lung IL-10, Foxp3, IL-17, and RORγ expression by OVA challenge and restored the percentage of CD4⁺CD25⁺Foxp3⁺ Tregs in the spleen. In conclusion, ADMSCs confer protection against OVA-induced airway hyperresponsiveness and inflammation, which is associated with induction of Tregs and restoration of immune homeostasis. These findings suggest that ADMSCs may have therapeutic implications for allergic asthma.