Emerging Role of Interleukin-38 (IL-38) in the Development of Rheumatoid Arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is an incurable autoimmune disease. The role of interleukin-38 (IL-38), an anti-inflammatory cytokine, in RA is not fully understood, and its clinical relevance in RA remains unclear. This study aims to investigate the correlation of IL-38 with disease activity and the clinical manifestation of RA.

METHODS

In this cross-sectional study, patients with treatment-naïve RA (n = 63) and healthy controls (HC) (n = 60) were consecutively enrolled over a 15-month period. Patients with RA were categorized into three subgroups-low disease activity (LDA), moderate disease activity (MDA) and high disease activity (HDA)-using the Disease Activity Score in 28 joints based on C-reactive protein (DAS28-CRP). Circulating levels of IL-38, tumour necrosis factor (TNF), IL-6, IL-17, IL-1β, and 25(OH)D were assessed using enzyme-linked immunosorbent assay (ELISA). Clinical data, including duration, tender joints count (TJC), swollen joints count (SJC), patient global assessment (PGA), evaluator global assessment (EGA), bone mineral density (BMD), clinical disease activity index (CDAI), simplified disease activity index (SDAI), DAS28-CRP, joint musculoskeletal ultrasound (MSUS), and serological indicators were recorded. We determined the correlation between IL-38 and disease activity, as well as clinical manifestation in RA.

RESULTS

At the macroscopic level, musculoskeletal ultrasonography of joints in different stages of disease activity in RA suggests that, as the disease progresses, arthritis in the hand becomes more severe, accompanied by synovial thickening and pronounced blood flow signals in the joint area. The expression of IL-38, TNF, IL-6, IL-17 and IL-1β significantly increased in patients with RA compared to HC. Noteworthy differences were observed in the blood flow signal score, synovial signal score, IL-38, TNF, IL-6, IL-17 and IL-1β among the three subgroups (LDA, MDA and HDA). As disease activity increased in patients with RA, the blood flow signal score, synovial signal score and expression of TNF, IL-6, IL-17 and IL-1β exhibited a gradual increase, while the expression of IL-38 showed the opposite pattern. Inverse correlations were identified between IL-38 and pro-inflammatory cytokines (IL-6, IL-17), as well as key clinical parameters, including disease duration, SJC, TJC and DAS28-CRP score.

CONCLUSION

IL-38, intricately linked to the pathogenesis of RA, emerges as a promising therapeutic target for the management of this debilitating disease.

Serum Interleukin-38 and Tumor-Infiltrating Lymphocytes in Primary Brain Tumors

Background

Tumor-infiltrating lymphocytes (TILs) and brain stromal cells produce immunosuppressive cytokines, contributing to an immunosuppressive tumor microenvironment (TME). Interleukin-38 (IL-38) is a novel anti-inflammatory cytokine and a natural modulator of the innate and adaptive immune system. However, its biological roles in brain tumors are not well defined.

Objective

To assess the serum levels of IL-38 and the percentages of TILs in the tumor tissues of patients with primary brain tumors and to determine their associations with the pathological features of the disease.

Methods

IL-38 was evaluated in sera using the enzyme-linked immunosorbent assay (ELISA). Hematoxylin and eosin (H&E)-stained sections were scored to determine the percentages of TILs in four different areas: the invasive margin, central tumor, perivascular and perinecrotic areas.

Results

IL-38 serum levels were significantly higher in low- and high-grade tumors than in healthy individuals, meanwhile, its levels remained consistent between these two grades. Although no significant difference was found in IL-38 serum levels between different histological subtypes of brain tumors, its levels were significantly higher in intra-axial brain tumors than in extra-axial ones. Additionally, a significant positive correlation was observed between serum levels of IL-38 and tumor size in patients with low-grade tumors. TILs were detected in at least one of the four examined areas; however, no statistically significant correlation was found between IL-38 levels and TILs.

Conclusion

Our data may suggest a connection between IL-38 and immune suppression and tumor progression in primary brain tumors. Further investigation is needed to uncover the role of IL-38 in the brain tumor microenvironment.

Anti-inflammatory Mechanisms of IL-38 in Chinese Patients with Allergic Rhinitis

Background: T-helper 17 (Th17) cell response is engaged in the onset of allergic rhinitis (AR). Moreover, interleukin (IL)-38 is thought to be involved in inhibiting cytokine secretion in the Th17 pathway. Objective: To evaluate the regulatory function of IL-38 on abnormal Th17 responses in Chinese patients with AR. Methods: Forty-five participants, divided into an AR group (n=25) and a control group (n=20), were recruited for the study. In addition, the expression of IL-38 and Th17-related cytokines was measured as well as the Th17 cell count in participants. By implementing recombinant IL-38 (rIL-38), the intervention of human peripheral blood mononuclear cells (PBMCs) was performed. Then, flow cytometry, polymerase chain reaction (PCR), and enzyme-linked immunosorbent assay (ELISA) were used to detect theTh17 milieu. Results: The expression of IL-38 in the AR group notably reduced compared with that in the control, whereas Th17 cell frequency and the expression levels of its transcription factor (RORC) and cytokines (IL-17A and IL-23) increased. The differentiation and immune function of Th17 cells in PBMCs were inhibited by rIL-38. Conclusion: Th17 responses are inhibited by IL-38 in patients with AR. Therefore, the obtained findings indicate that IL-38 is a potential therapeutic target for Chinese 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.

Interleukin-38 suppresses abdominal aortic aneurysm formation in mice by regulating macrophages in an IL1RL2-p38 pathway-dependent manner

Macrophages play crucial roles in abdominal aortic aneurysm (AAA) formation through the inflammatory response and extracellular matrix degradation; therefore, regulating macrophages may suppress AAA formation. Interleukin-38 (IL-38) is a member of the IL-1 family, which binds to IL-36 receptor (IL1RL2) and has an anti-inflammation effect. Because macrophages express IL1RL2, we hypothesized that IL-38 suppresses AAA formation by controlling macrophages. We assessed a C57BL6/J mouse angiotensin II-induced AAA model with or without IL-38 treatment. RAW 264.7 cells were cultured with tumor necrosis factor-α and treated with or without IL-38. Because p38 has important roles in inflammation, we assessed p38 phosphorylation in vitro and in vivo. To clarify whether the IL-38 effect depends on the p38 pathway, we used SB203580 to inhibit p38 phosphorylation. IL1RL2+ macrophage accumulation along with matrix metalloproteinase (MMP)-2 and -9 expression was observed in mouse AAA. IL-38 reduced the incidence of AAA formation along with reduced M1 macrophage accumulation and MMP-2 and -9 expression in the AAA wall. Macrophage activities including inducible nitric oxide, MMP-2, and MMP-9 production and spindle-shaped changes were significantly suppressed by IL-38. Furthermore, we revealed that inhibition of p38 phosphorylation diminished the effects of IL-38 on regulating macrophages to reduce AAA incidence, indicating the protective effects of IL-38 depend on the p38 pathway. IL-38 plays protective roles against AAA formation through regulation of macrophage accumulation in the aortic wall and modulating the inflammatory phenotype. Using IL-38 may be a novel therapy for AAA patients.

Long noncoding RNA H19 alleviates inflammation in osteoarthritis through interactions between TP53, IL-38, and IL-36 receptor

Aims

Osteoarthritis (OA) is a common degenerative joint disease characterized by chronic inflammatory articular cartilage degradation. Long noncoding RNAs (lncRNAs) have been previously indicated to play an important role in inflammation-related diseases. Herein, the current study set out to explore the involvement of lncRNA H19 in OA.

Methods

Firstly, OA mouse models and interleukin (IL)-1β-induced mouse chondrocytes were established. Expression patterns of IL-38 were determined in the synovial fluid and cartilage tissues from OA patients. Furthermore, the targeting relationship between lncRNA H19, tumour protein p53 (TP53), and IL-38 was determined by means of dual-luciferase reporter gene, chromatin immunoprecipitation, and RNA immunoprecipitation assays. Subsequent to gain- and loss-of-function assays, the levels of cartilage damage and proinflammatory factors were further detected using safranin O-fast green staining and enzyme-linked immunosorbent assay (ELISA) in vivo, respectively, while chondrocyte apoptosis was measured using Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) in vitro.

Results

IL-38 was highly expressed in lentivirus vector-mediated OA mice. Meanwhile, injection of exogenous IL-38 to OA mice alleviated the cartilage damage, and reduced the levels of proinflammatory factors and chondrocyte apoptosis. TP53 was responsible for lncRNA H19-mediated upregulation of IL-38. Furthermore, it was found that the anti-inflammatory effects of IL-38 were achieved by its binding with the IL-36 receptor (IL-36R). Overexpression of H19 reduced the expression of inflammatory factors and chondrocyte apoptosis, which was abrogated by knockdown of IL-38 or TP53.

Conclusion

Collectively, our findings evidenced that upregulation of lncRNA H19 attenuates inflammation and ameliorates cartilage damage and chondrocyte apoptosis in OA by upregulating TP53, IL-38, and by activating IL-36R.

Cite this article: Bone Joint Res 2022;11(8):594–607.

Evaluation of interleukin-38 levels in serum of patients with coronavirus disease 2019

Interleukin‐38 (IL‐38) has recently been considered as a cytokine with anti‐inflammatory properties in viral respiratory infections, particularly coronavirus disease 19 (COVID‐19), but the evidence has not been well elucidated. Therefore, a case‐control study was conducted to determine IL‐38 serum levels in 148 patients with COVID‐19 (45 moderate, 55 severe, and 48 critical) and 113 controls. Results demonstrated that IL‐38 levels did not show significant differences between patients and controls (68.7 [interquartile range: 62.7–75.6] vs. 67.7 [58.0–82.6] pg/ml; probability = 0.457). Similarly, patients stratified by disease severity, age group, gender, or chronic disease showed no significant differences between IL‐38 levels in each stratum. Whereas, overweight/obese patients had a significantly lower median of IL‐38 compared to normal‐weight patients. Further, IL‐38 showed significantly higher levels in the age group ≥50 years of patients with critical illness than in the age group <50 years. Female patients with severe disease also showed significantly elevated levels of IL‐38 compared to male patients. In conclusion, the study indicated that serum IL‐38 levels were not affected by COVID‐19 infection, but the distribution of patients according to disease severity, age, gender, and body mass index may better reveal the role of IL‐38 in disease pathogenesis.

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.

IL-1 family cytokines as drivers and inhibitors of trained immunity

Trained immunity is the long-term memory of innate immune cells, characterised by increased pro-inflammatory responses towards homo- and heterologous secondary stimuli. Interleukin (IL)-1 signalling plays an essential role in the induction of trained immunity, also called innate immune memory. As such, certain anti-inflammatory members of the IL-1 family of cytokines (IL-1F) which interfere with the inflammatory process have the potential to regulate the induction of a trained phenotype. The aim of this review is to provide an update on the role of IL-1F members in the context of trained immunity, emphasising the role of anti-inflammatory cytokines from the IL-1F to inhibit the induction of trained immunity, and touching upon their potential as therapeutics in IL-1-driven inflammatory disorders.

IL-38 as an early predictor of the ischemic stroke prognosis

BACKGROUND

Ischemic stroke is caused by a sudden neurological defect following a vascular occlusion and elicits a local and systemic inflammation in brain tissue. Interleukin-38 is an anti-inflammatory cytokine associated with ischemic and inflammatory diseases. This study was designed to analyze the effect of tPA therapy on interleukin-38 serum level changes and the serum level of IL-38 in the prognosis of ischemic stroke patients in the next three months.

METHODS

We enrolled 29 ischemic stroke patients confirmed by a neurologist based on radiologic and clinical manifestation between 2019 September to 2020 February. The patients who had NIHSS more than 6 with no underlying inflammatory diseases were selected for tPA therapy. On admission and 24 h after tPA therapy, the IL-38 serum level was measured by ELISA kit.

RESULTS

The results showed that serum levels of IL-38 were significantly increased after tPA therapy (P < 0.001). A remarkable relationship was observed between the modified Rankin Score (mRS) and IL-38 serum changes in response to tPA therapy (P < 0.001). Besides, IL-38 serum changes following tPA were dramatically related to NIHSS at hospitalization (P = 0.007). Also, our analysis posed a positive relation between NIHSS at hospitalization and mRs criteria (P = 0.023). No notable relation has been observed between IL-38 serum levels before and after tPA and mRs (P = 0.601 and P = 0.074, respectively). Furthermore, there was no evidence for the relation between NIHSS at hospitalization and IL-38 levels before and after tPA (P = 0.457 and P = 0.105, respectively).

CONCLUSION

The results indicate that tPA could meaningfully increase the IL-38 serum level. Also, a negative correlation has been found between IL-38 serum changes in response to tPA and mRS. Since the lower changes in IL-38 serum level result in a poorer prognosis, we conclude that IL-38 serum changes might be a novel early predictor factor for ischemic stroke prognosis.

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 overexpression prevents bleomycin-induced mouse pulmonary fibrosis

Pulmonary fibrosis is a kind of pulmonary disorder with chronic inflammation and excessive collagen deposition, and its etiology is not clear. Interleukin (IL)-38 is a new member of IL-1 family cytokines, but its role in pulmonary fibrosis has not been elucidated. In this study, a lentivirus expressing IL-38 was injected into the nasal cavity of mice with bleomycin-induced pulmonary fibrosis. We found that IL-38 overexpression reduced the body weight loss and improved the survival of mice induced by bleomycin. Furthermore, IL-38 expression attenuated the pulmonary inflammation and fibrosis damage induced by bleomycin, decreased the production of pro-inflammatory and pro-fibrotic cytokines such as IL-1β, IL-6, IL-17A, monocyte chemoattractant protein-1, and tumor necrosis factor-α, but increased the release of anti-inflammatory cytokine IL-1 receptor antagonist (IL-1Ra) in the lungs of bleomycin-challenged mice. Our data suggest that IL-38 may inhibit bleomycin-induced pulmonary inflammation and fibrosis through its anti-inflammatory effect and regulation of IL-1β/IL-1Ra balance, and IL-38 may be a new strategy for the treatment of pulmonary fibrosis.

Plasma levels of interleukin-38 in healthy aging and in type 2 diabetes

Plasma levels of interleukin (IL)-38 were evaluated in patients with type 2 diabetes (T2DM) and healthy controls. Plasma IL-38 was higher in T2DM patients and positively related to waist/hip ratio, HbA1c, uric acid, liver function tests, triglycerides and total proteins. Patients suffering from diabetic nephropathy had the highest IL-38 levels.

Elevated IL-38 Serum Levels in Newly Diagnosed Multiple Sclerosis and Systemic Sclerosis Patients

OBJECTIVE

Interleukin (IL)-38 is a newly discovered member of the IL-1 cytokine family with a proposed anti-inflammatory profile. We studied the probable role of this cytokine in the pathogenesis of two autoimmune diseases: multiple sclerosis (MS) and systemic sclerosis (SSc).

SUBJECTS AND METHODS

A total of 87 MS patients and 86 SSc patients (40 new and recently untreated cases and 46 treated cases) were selected for this study. Eighty-seven and 80 age- and sex-matched healthy subjects were included as controls for MS and SSc, respectively. Clinical and paraclinical features of the patients were recorded at the time of sampling. Serum IL-38 was measured by ELISA.

RESULTS

Levels of serum IL-38 did not significantly differ between the total MS or SSc patients compared to controls. However, levels of IL-38 were significantly higher in newly diagnosed patients of MS (206.43 ± 38.97 pg/mL, p < 0.0001) than in those previously treated (158.04 ± 39.45 pg/mL). Similarly, new/recently untreated cases of SSc patients showed increased IL-38 levels (185.19 ± 36.27 pg/mL, p = 0.001) compared to treated patients (166.82 ± 33.08 pg/mL). IL-38 levels in newly diagnosed MS patients (p = 0.007) and new/recently untreated SSc patients (p = 0.032) were significantly higher than those in healthy controls.

CONCLUSION

The higher serum levels of IL-38 in new or recently untreated cases of MS and SSc patients than in treated patients and healthy controls suggest the possible role of this cytokine in the development of these diseases or as part of a feedback loop to attenuate the inflammatory conditions in early stages of these diseases.

Blockade of Th17 response by IL-38 in primary Sjögren's syndrome

BACKGROUND

T helper 17 (Th17) cell responses were involved in the pathophysiology of primary Sjögren's syndrome (pSS). IL-38 has been reported to inhibit the secretion of chemokines involved in Th17 pathway. This study aimed to explore the regulation of Th17 response by IL-38 in pSS.

METHODS

Twenty-four pSS patients, 15 non-pSS control, and 13 health subjects were recruited. The expression of IL-38 and Th17 cytokines were detected and compared between pSS and controls. Human peripheral blood mononuclear cells (PBMCs) and minor salivary gland mononuclear cells (MSGMs) were purified and stimulated by IL-38. The differentiation and function of Th17 cells were evaluated by PCR and enzyme-linked immunosorbent assay (ELISA).

RESULTS

The pSS patients presented with significantly lower expression of IL-38 and higher Th17 cytokines (IL-17 and IL-23) compared with both non-pSS and healthy controls. The IL-38 inhibited the differentiation and function of Th17 responses from PBMCs and MSGMs. The IL-38 treatment could inhibit the Th17 response in mice model.

CONCLUSIONS

IL-38 inhibits T helper 17 type responses in pSS, suggesting that IL-38 may be used as potential treatment target in pSS.

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.

Interleukin-38 increases the insulin sensitivity in children with the type 2 diabetes

The prevalence of type 2 diabetes mellitus (DM) is increasing in the children population. It is well known that inflammation contributes to the type 2 DM pathogenesis. Interleukin 38 (IL-38) is one newly identified anti-inflammatory factor. Therefore, we investigated whether the expression level of IL-38 is associated with type 2 DM in the children and the underlying mechanism. Children with recently diagnosed type 2 diabetes mellitus were recruited and studied. The healthy subjects without glucose metabolism abnormalities were used as controls. The IL-38 expression level was determined by quantitative PCR and ELISA (Enzyme-linked immunoassay). Statistic analysis showed that the IL-38 level was significantly associated with type 2 DM and insulin resistance in the children. The patients were then divided into two groups, one group sensitive to insulin therapy while the other resistant to insulin therapy. Data showed that the IL-38 was highly expressed in the group sensitive to insulin therapy. In the mice model, overexpressing the IL-38 could suppress the expression of IL-36, a pro-inflammatory factor, and also the diabetes development. Thus our results showed that higher IL-38 was associated with the increased insulin sensitive in children with type 2 DM and inhibited T2DM development in the mouse model through suppressing the function of IL-36.

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 expression and clinical significance in serum of patients with chronic obstructive pulmonary disease]

Objective: To investigate the serum level of interleukin-38 (IL-38) and its clinical significance in patients with chronic obstructive pulmonary disease (COPD). Methods: Totally 72 patients with acute exacerbation of COPD (AECOPD group) and 65 patients with stable COPD (S-COPD group) were recruited from Tianjin Chest Hospital from June 2016 to August 2017. In the same period 40 elderly healthy subjects were selected as control group (C group). The general data and laboratory examination results of these subjects were recorded. Serum IL-38 was measured by double antibody enzyme-linked immunosorbent assays (ELISA). The inter-group differences of above parameters were analyzed. Pearson correlation or Spearman rank correlation analysis was used to analyze the correlation between IL-38 and each variable, and multivariate stepwise regression analysis was used to determine the influencing factors of serum IL-38 in COPD patients. Results: The serum level of IL-38 was higher in AECOPD group than in S-COPD group[(57.88±13.72) vs (51.75±14.06) ng/L, P<0.05], and was higher in either of the two COPD groups than in C group[(46.37±13.18) ng/L](both P<0.05). Correlation analysis of single factor showed that serum IL-38 levels were positively correlated with body mass index (r=0.190, P<0.05), and negatively correlated with C reactive protein (CRP), fibrinogen (FIB), forced expiratory volume in one second as a percentage of estimated value (FEV₁%pred) and the number of acute exacerbations in the past 1 year (r=-0.344, -0.176, -0.195, -0.229, all P<0.05). The CRP level and the number of acute exacerbations in the past 1 year were independent factors affecting the serum level of IL-38 (β=-0.204, -0.183, both P<0.05) in patients with COPD. Conclusion: IL-38 is compensatory increased in serum of patients with COPD and may be used as one of the serological markers for evaluation of COPD.

Plasma interleukin-38 in patients with rheumatoid arthritis

Previous studies have indicated that interleukin-38 (IL-38) is involved in rheumatoid arthritis (RA). The present study aims to assess plasma levels of IL-38 in RA and discuss the potential of IL-38 as a biomarker for RA. Protein concentrations of IL-38 were examined by enzyme-linked immunosorbent assay, and the mRNA level of IL-38 was tested by quantitative real-time polymerase chain reaction. Plasma IL-38 was first compared in a training cohort, including 130 RA patients and 53 healthy controls, given the optimal cutoff. Then, we validated the levels of IL-38 in a further cohort of 519 patients, including 250 with RA, 63 systemic lupus erythematosus, 62 primary Sjogren's syndrome, 51 gout, 63 osteoarthritis, and 30 psoriatic arthritis, as well as 60 healthy controls. To further discuss the changes in IL-38 after treatment and the relationship with disease activity, we tested IL-38 expression in RA patients from the training cohort under follow-up. In the training cohort, plasma levels of IL-38 were higher in RA patients compared with healthy controls (681.00 [234.45-826.47] versus 152.04 [70.06-246.80] pg/mL, P < 0.001). The IL-38 mRNA level was elevated in RA patients as compared with healthy controls (P < 0.001). Expression of IL-38 was significantly higher in RA patients compared with that in non-RA patients in the validation cohort (all P < 0.001). Treatment significantly reduced IL-38 expression. IL-38 expression was related to parameters of inflammation both at baseline and in the follow-up studies. The area under the curve (AUC) of the receiver-operating characteristic curve showed that IL-38 may be a potential biomarker for RA. At the optimal cutoff value of 341.90 pg/mL, the sensitivity, specificity, and AUC were 72.30%, 90.60%, and 0.840, respectively, in the training cohort. Similar results were noted in the validation cohort. In conclusion, IL-38 expression correlated with RA disease activity, and plasma IL-38 might be a promising diagnostic biomarker for RA.

Elevated Interleukin-38 Level Associates with Clinical Response to Atorvastatin in Patients with Hyperlipidemia

BACKGROUND/AIMS

Hyperlipidemia is a risk factor for various cardiovascular and metabolic disorders. And it is tightly related to chronic inflammation. Interleukin-38 (IL-38) represents a new member of anti-inflammatory cytokines. Thus we studied the important role of IL-38 in hyperlipidemia development and treatment.

METHODS

The mRNA level of IL-38 in PBMCs (peripheral blood mononuclear cells) and serum IL-38 levels in hyperlipidemia patients and healthy controls were measured by real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunoassay (ELISA). The hyperlipidemia patients were further divided into two groups (Sensitive and Resistant Group) according to their clinical response to Atorvastatin therapy. Finally, the effects of IL-38 on hyperlipidemia was evaluated in the mice model.

RESULTS

Data showed that the IL-38 mRNA and serum protein levels were higher in patients with hyperlipidemia compared with healthy controls. And the IL-38 mRNA and serum protein levels were higher in patients sensitive to Atorvastatin therapy than the resistant group. In vitro, IL-38 inhibited the production of IL-6, IL-1β and CRP in PBMCs of patients with hyperlipidemia. In the mice model of hyperlipidemia, IL-38 was also elevated during the hyperlipidemia development. Furthermore, the IL-38 over-expressed by adeno-associated virus significantly inhibited the hyperlipidemia development, inflammatory factor secretion and also the atherosclerosis process.

CONCLUSION

Thus our data showed that IL-38 might present protective effects on hyperlipidemia treatment.

Elevated serum interleukin-38 level at baseline predicts virological response in telbivudine-treated patients with chronic hepatitis B

AIM: To investigate serum interleukin (IL)-38 level and its clinical role in predicting virological response (VR) to telbivudine (LdT) in patients with chronic hepatitis B (CHB).

METHODS: The study participants were divided into two groups; one group consisted of 43 healthy controls (HCs) and the other group consisted of 46 patients with hepatitis B e antigen-positive CHB. All patients were administered 600 mg of oral LdT daily for 52 wk, and they visited physicians every 12 wk for physical examination and laboratory tests. Serum IL-38 levels were determined using ELISA. The concentrations of serum Th1- and Th2-type cytokines were measured using the cytometric bead array (CBA) method.

RESULTS: Serum levels of IL-38 at baseline in all patients were higher than those in HCs [306.97 (123.26-492.79) pg/mL vs 184.50 (135.56-292.16) pg/mL, P = 0.019]; the levels returned to normal after the first 12 wk of treatment with LdT [175.51 (103.90-331.91) pg/mL vs 184.50 (135.56-292.16) pg/mL, P > 0.05]. Serum IL-38 levels at baseline were positively associated with serum aspartate aminotransferase levels in patients with CHB (r = 0.311, P = 0.036). Higher levels of serum IL-38 at baseline were associated with a greater probability of VR to LdT treatment at 24 wk (48.15% vs 15.79%, P = 0.023) and 52 wk (66.67% vs 36.84%, P = 0.044). The levels of serum IL-38 in patients with primary non-response at week 12 after treatment initiation were lower than those in patients with primary response [64.44 (49.85-172.08) pg/mL vs 190.54 (121.35-355.28) pg/mL, P = 0.036]. Serum IL-38 levels were correlated with serum IL-6 and IL-12 levels in patients with CHB during treatment with LdT.

CONCLUSION: Elevated serum IL-38 levels in untreated CHB patients reflect ongoing liver injury. Higher serum IL-38 levels before treatment indicate a greater probability of VR to LdT treatment.