Serum interleukin-33 and soluble suppression of tumorigenicity 2 in pediatric leukemia with febrile neutropenia

The purpose of this study was to evaluate the association between interleukin-33 (IL-33) and its receptor Soluble Suppression of Tumorigenicity-2 (sST2) levels and bacterial infections during febrile neutropenia (FN) in pediatric patients with acute lymphoblastic leukemia (ALL). In this prospective, case-control study, participants were divided into 3 groups: ALL patients with FN (Group A), ALL patients without neutropenia and fever (Group B), and healthy children without infection and chronic disease (Group C). There were 30 cases in each group. Blood samples for IL-33 and sST2 have been drawn from patients in Group A before the initiation of treatment and on days 1 and 5 of treatment, and from patients in Groups B and C at initiation. At admission, mean IL-33 level (39.02 ± 26.40 ng/L) in Group B and mean sST2 level (185.3 ± 371.49 ng/ml) in Group A were significantly higher than the other groups (p = 0.038, p < 0.001, respectively). No difference was observed in the mean IL-33 and sST2 levels in the 5-day follow-up of patients in Group A (p = 0.82, p = 0.86, respectively). IL-33 and sST2 levels were not associated with fever duration, neutropenia duration or length of hospitalization. While C-reactive protein (CRP) was significantly higher in patients with positive blood culture (p = 0.021), IL-33 (p = 0.49) and sST2 (p = 0.21) levels were not associated with culture positivity.  Conclusion: IL-33 and sST2 levels were not found valuable as diagnostic and prognostic markers to predict bacterial sepsis in patients with FN. What is Known: • Neutropenic patients are at high risk of serious bacterial and viral infections, but the admission symptom is often only fever. • Febrile neutropenia has a high mortality rate if not treated effectively. What is New: • Febrile neutropenia is not only caused by bacterial infections. Therefore, new biomarkers should be identified to prevent overuse of antibiotics. • Specific biomarkers are needed to diagnose bacterial sepsis in the early phase of febrile neutropenia.

Associations of MEFV gene variants, IL-33, and sST2 with the risk of Henoch-Schönlein purpura in children

Objective

Henoch-Schönlein purpura (HSP) is the most common systemic vasculitis in children. HSP is a multifactorial inflammatory disease, but its pathogenesis is still unclear. The pathogenicity of familial Mediterranean fever gene (MEFV) variants in HSP remains controversial. The objective of this study was to evaluate relationships between MEFV variants and susceptibility to HSP and their associations with clinical outcomes. We also investigated levels of IL-33 and soluble suppression of tumorigenicity 2 (sST2) in children with HSP and their clinical significance.

Methods

We selected 100 children with HSP as the case group. The control group consisted of 50 children who visited the hospital for physical health examinations. All subjects were screened for MEFV gene exon mutations, and levels of IL-33 and sST2 were measured.

Results

The frequency of MEFV variants was significantly greater in HSP patients than in healthy controls. The variant with the highest frequency was E148Q. The frequency of the C allele of the MEFV variant E148Q was 32 % in HSP patients and 18 % in controls (P-adjust = 0.04). Patients with the MEFV E148Q variant had more frequent joint involvement and recurrent purpura and higher levels of IL-33 and C-reactive protein (CRP). Levels of IL-33 and sST2 in children with HSP were significantly higher than those in the control group, and the sST2/IL-33 ratio in children with HSP was unbalanced (P-adjust <0.05). Logistic regression analysis revealed the presence of E148Q and an unbalanced sST2/IL-33 ratio to be independent risk factors for HSP.

Conclusion

The results of this study suggest that the MEFV variant E148Q is associated with HSP susceptibility in Chinese children and that carriers of the variant may have more severe clinical manifestations and greater inflammatory responses. E148Q and the sST2/IL-33 ratio may play important roles in the pathogenesis of HSP.

IL-33 regulates adipogenesis via Wnt/β-catenin/PPAR-γ signaling pathway in preadipocytes

Interleukin-33 (IL-33), an emerging cytokine within the IL-1 family, assumes a pivotal function in the control of obesity. However, the specific mechanism of its regulation of obesity formation remains unclear. In this study, we found that the expression level of IL-33 increased in visceral adipose tissue in mice fed with a high-fat diet (HFD) compared with that in mice fed with a normal diet (ND). In vitro, we also found the expression level of IL-33 was upregulated during the adipogenesis of 3T3-L1 cells. Functional test results showed that knockdown of IL-33 in 3T3-L1 cells differentiation could promote the accumulation of lipid droplets, the content of triglyceride and the expression of adipogenic-related genes (i.e. PPAR-γ, C/EBPα, FABP4, LPL, Adipoq and CD36). In contrast, overexpression of IL-33 inhibits adipogenic differentiation. Meanwhile, the above tests were repeated after over-differentiation of 3T3-L1 cells induced by oleic acid, and the results showed that IL-33 played a more significant role in the regulation of adipogenesis. To explore the mechanism, transcriptome sequencing was performed and results showed that IL-33 regulated the PPAR signaling pathway in 3T3-L1 cells. Further, Western blot and confocal microscopy showed that the inhibition of IL-33 could promote PPAR-γ expression by inhibiting the Wnt/β-catenin signal in 3T3-L1 cells. This study demonstrated that IL-33 was an important regulator of preadipocyte differentiation and inhibited adipogenesis by regulating the Wnt/β-catenin/PPAR-γ signaling pathway, which provided a new insight for further research on IL-33 as a new intervention target for metabolic disorders.

Interleukin-33/serum stimulation-2 pathway: Regulatory mechanisms and emerging implications in immune and inflammatory diseases

Interleukin (IL)- 33, a nuclear factor and pleiotropic cytokine of the IL-1 family, is gaining attention owing to its important role in chronic inflammatory and autoimmune diseases. This review extends our knowledge of the effects exerted by IL-33 on target cells by binding to its specific receptor serum stimulation-2 (ST2). Depending on the tissue context, IL-33 performs multiple functions encompassing host defence, immune response, initiation and amplification of inflammation, tissue repair, and homeostasis. The levels and activity of IL-33 in the body are controlled by complex IL-33-targeting regulatory pathways. The unique temporal and spatial expression patterns of IL-33 are associated with host homeostasis and the development of immune and inflammatory disorders. Therefore, understanding the origin, function, and processes of IL-33 under various conditions is crucial. This review summarises the regulatory mechanisms underlying the IL-33/ST2 signalling axis and its potential role and clinical significance in immune and inflammatory diseases, and discusses the current complex and conflicting findings related to IL-33 in host responses.

Activated Leukocyte Cell Adhesion Molecule Regulates the Expression of Interleukin-33 in RSV Induced Airway Inflammation by Regulating MAPK Signaling Pathways

PURPOSE

The respiratory syncytial virus (RSV) is a common respiratory virus that causes acute lower respiratory tract infectious diseases, particularly in young children and older individuals. Activated leukocyte cell adhesion molecule (ALCAM) is a membrane glycoprotein expressed in various cell types, including epithelial cells, and is associated with inflammatory responses and various cancers. However, the precise role of ALCAM in RSV-induced airway inflammation remains unclear, and our study aimed to explore this gap in the literature.

METHODS

C57BL/6 wild-type, ALCAM knockout mice and airway epithelial cells were infected with RSV and the expression of ALCAM and inflammatory cytokines were measured. We also conducted further experiments using Anti-ALCAM antibody and recombinant ALCAM in airway epithelial cells.

RESULTS

The expression levels of ALCAM and inflammatory cytokines increased in both RSV-infected mice and airway epithelial cells. Interestingly, IL-33 expression was significantly reduced in ALCAM-knockdown cells compared to control cells following RSV infection. Anti-ALCAM antibody treatment also reduced IL-33 expression following RSV infection. Furthermore, the phosphorylation of ERK1/2, p38, and JNK was diminished in ALCAM-knockdown cells compared to control cells following RSV infection. Notably, in the control cells, inhibition of these pathways significantly decreased the expression of IL-33. In vivo study also confirmed a reduction in inflammation induced by RSV infection in ALCAM deficient mice compared to wild-type mice.

CONCLUSION

These findings demonstrate that ALCAM contributes to RSV-induced airway inflammation at least partly by influencing IL-33 expression through mitogen-activated protein kinase signaling pathways. These results suggest that targeting ALCAM could be a potential therapeutic strategy for alleviating IL-33-associated lung diseases.

Combination of IL-33 with PD-1 blockade augment mILC2s-mediated anti-tumor immunity

BACKGROUND

Group 2 innate lymphoid cells (ILC2s) represent one of the main tissue-specific innate lymphoid cell populations, which are key drivers of cytokine secretion in their occupational niche. However, the precise involvement of ILC2s in cancer immunity and their potential impact on immunotherapeutic approaches remain poorly understood.

METHODS

The proportion of ILC2s originating from various tissue sources were quantified through flow cytometry, along with the determination of CD4+ T cell and CD8+ T cell percentages. Flow cytometry was also employed to assess IFN-γ production and programmed cell death protein-1 (PD-1) expression in T cells. Immunohistochemistry was utilized to detect IL-33 expression in tumor tissues, while immunofluorescence was employed to confirm the infiltration of ILC2s in both murine and human tumor tissues.

RESULTS

In this study, we provide evidence that intra-tumoral ILC2s in lung adenocarcinoma (LUAD) exist in a quiescent state. However, the activation of intra-tumoral ILC2s is induced by IL-33 specifically in a natural ILC2s (nILC2, ST2+KLRG1-) phenotype. Considering the pivotal role of PD-1 in cancer immunotherapy and its immunoregulatory functions, we investigated the synergistic effects of IL-33 and anti-PD-1 and found that their combination enhances anti-tumor immunity and improves the efficacy of immunotherapy. Moreover, this combination leads to the upregulation of activated mature ILC2s (mILC2, ST2+KLRG1+) phenotype, thereby highlighting the activated ILC2s as a novel enhancer of the immunoregulatory properties of anti-PD-1.

CONCLUSIONS

Collectively, these findings underscore the significance of ILC2s and their contribution to the anti-tumor response in the context of cancer immunotherapy. Consequently, the simultaneous targeting of ILC2s and T cells represents a potentially promising and widely applicable strategy for immunotherapeutic interventions.

The effect of interleukin-33 expression on prognosis in patients with nasopharyngeal carcinoma

INTRODUCTION

Interleukin-33 (IL-33) is a newly defined inflammatory cytokine that is a member of the interleukin-1 (IL-1) gene family. This cytokine is expressed in structural cells, such as the vascular endothelium, bronchial epithelial cells, keratinocytes, epithelial cells of the stomach, and fibroblastic reticular cells of lymphoid tissues. Several studies suggest that IL-33 plays a role in head-and-neck cancer. The aim of this study was to retrospectively examine IL-33 expression in nasopharyngeal carcinoma (NPC) and to evaluate its relationship between clinicopathological characteristics and prognosis.

METHODS

In this monocentric, retrospective analysis, the data of 43 cases diagnosed with primary NPC and 20 cases with normal nasopharyngeal tissue (diagnosed between 2014 and 2020) were evaluated regarding the relationship between the immunohistochemically analyzed IL-33 expression status and corresponding clinicopathological parameters.

RESULTS

The mean age was 56.9 years. The majority (67.4%) of the patients had an early tumor stage (T1-T2). IL-33 expression was positive in 56% of the cases. The five-year overall survival rate was 77% for all patients, 90% for the patients with positive IL-33 expression, and 55% for those without IL-33 expression (p = 0.008, univariate analysis). In multivariate analysis, IL-33 expression was shown to be the only independent prognostic marker for nasopharyngeal carcinoma (p = 0.014).

CONCLUSION

This retrospective study showed that IL-33 expression could be considered an independent factor affecting positively prognosis in NPC.

Different Gene Expression Patterns of IL-1 Family Members in Parkinson's Disease: Results from Bayesian Regression Model

Parkinson's disease, the second most prevalent neurodegenerative disorder lacking a recognized etiology, is influenced by oxidative stress and alterations in inflammatory cytokine levels. This study aimed to investigate the expression levels of Interleukin(IL)1 receptor accessory protein (IL-1RAcP), IL1β, IL1α, IL33, and IL36 genes in blood cells and serum IL-1β levels in Parkinson's disease patients compared to healthy controls (HCs).I n this case-control study, 44 Parkinson's disease patients and 44 age- and sex-matched HCs were included. Gene expression levels were assessed using Quantitative Real-time PCR, and serum IL-1β levels were measured via enzyme-linked immunosorbent assay. Advanced statistical analyses using the Bayesian regression model in R software were employed. Parkinson's disease patients exhibited elevated expression levels of IL-1RAcP and IL1β genes  but decreased levels of IL1α, IL33, and IL36 compared to HCs. Age-based differences were not significant. Regarding gender, IL33 transcript levels were significantly higher in males, and serum IL-1β levels were increased in patients. Subgroup analysis by gender indicated alterations in IL1β and IL-1RAcP expression in both genders, while IL1α, IL33, and IL36 showed reduced expression only in males. Remarkably, only female patients displayed significantly higher serum IL-1β levels than female HCs. These findings suggest that dysregulation of immune-related factors plays a crucial role in Parkinson's disease.

Interplay of IL-33 and IL-35 Modulates Th2/Th17 Responses in Cigarette Smoke Exposure HDM-Induced Asthma

Cigarette smoke (CS) facilitates adverse effects on the airway inflammation and treatment of asthma. Here, we investigated the mechanisms by which CS exacerbates asthma. The roles of IL-33 and IL-35 in asthma development were examined by treatment with IL-33 knockout (IL-33 KO) or transfection of adenovirus encoding IL-35 (Ad-IL-35) in a murine model of cigarette smoke-exposure asthma. Furthermore, the involvement of IL-33 and IL-35 in regulating DCs and Th2/Th17 cells was examined in a coculture system of DCs with CD4+ T cells. Additionally, we observed the effect of CpG-ODNs on the balance of IL-33 and IL-35. We show that CS and house dust mite (HDM) exposure induced IL-33 and suppressed IL-35 levels in cigarette smoke-exposure asthma in vivo and in vitro. Treatment with IL-33 KO or Ad-IL-35 significantly attenuated airway hyperreactivity, goblet hyperplasia, airway remodelling, and eosinophil and neutrophil infiltration in the lung tissues from asthmatic mice. Furthermore, we demonstrated reciprocal regulation between CS and HDM-modulated IL-33 and IL-35. Mechanistically, IL-33 KO (or anti-ST2) and Ad-IL-35 attenuated Th2- and Th17-associated inflammation by downregulating TSLP-DC signalling. Finally, administration of CpG-ODNs suppressed the expression of IL-33/ST2 and elevated the levels of IL-35, which is mainly derived from CD4+Foxp+ Tregs, to alleviate Th2- and Th17-associated inflammation by inhibiting the activation of BMDCs. Taken together, the IL-33/ST2 pathway drives the DC-Th2 and Th17 responses of cigarette smoke-exposure asthma, while IL-35 has the opposite effect. CpG-ODNs represent a potential therapeutic strategy for modulating the balance of IL-33 and IL-35 to suppress allergic airway inflammation.

Innate Type-2 Cytokines: From Immune Regulation to Therapeutic Targets

The intricate role of innate type-2 cytokines in immune responses is increasingly acknowledged for its dual nature, encompassing both protective and pathogenic dimensions. Ranging from defense against parasitic infections to contributing to inflammatory diseases like asthma, fibrosis, and obesity, these cytokines intricately engage with various innate immune cells. This review meticulously explores the cellular origins of innate type-2 cytokines and their intricate interactions, shedding light on factors that amplify the innate type-2 response, including TSLP, IL-25, and IL-33. Recent advancements in therapeutic strategies, specifically the utilization of biologics targeting pivotal cytokines (IL-4, IL-5, and IL-13), are discussed, offering insights into both challenges and opportunities. Acknowledging the pivotal role of innate type-2 cytokines in orchestrating immune responses positions them as promising therapeutic targets. The evolving landscape of research and development in this field not only propels immunological knowledge forward but also holds the promise of more effective treatments in the future.

Serum levels of interleukin-33 and mesencephalic astrocyte derived neurotrophic factors in patients with major depressive disorder: a cross-sectional comparative design

BACKGROUND

Major depressive disorder (MDD) is a debilitating health condition that has significant morbidity and mortality rates. Depression can be caused due to social, biological, environmental, psychological, and genetic factors. A few biological processes have been proposed as the pathophysiological pathways of depression. Neurotrophic factors and inflammatory cytokines have been linked to depression. Thus, we aimed to investigate the serum interleukin-33 (IL-33) and mesencephalic astrocyte-derived neurotrophic factor (MANF) in MDD patients and corresponding healthy controls (HCs).

METHOD

This study involved the inclusion of 129 MDD patients and 125 HCs matched by sex and age. A psychiatrist evaluated the study participants following DSM-5 criteria. The severity of the illness was assessed utilizing the Hamilton Depression Rating Scale (Ham-D). The serum concentrations of IL-33 and MANF were measured using enzyme-linked immunosorbent assay (ELISA) kits.

RESULTS

The mean serum levels of IL-33 were decreased (159.12 ± 6.07 pg/ml vs. 180.60 ± 8.64 pg/ml, p = 0.042), and the MANF levels were increased (5.40 ± 0.19 ng/ml vs. 4.46 ± 0.21 ng/ml, p = 0.001) in MDD patients when compared to HCs.

CONCLUSIONS

The current study proposes that lower IL-33 and higher MANF serum levels are associated with MDD progression and depression severity. These biomarkers could be used as risk assessment tools for MDD. We recommend more investigation, including a significant population, to determine the precise function of IL-33 and MANF in depression.

Interleukin-33 has the protective effect on oligodendrocytes against impairment induced by cuprizone intoxication

Our prior investigations have demonstrated the pivotal role of IL-33 in facilitating the maturation of oligodendrocytes (OLs), prompting our interest in exploring its potential therapeutic effects. In this study, our focus was directed towards deciphering the functions of interleukin-33 (IL-33) in established demyelinating mouse model induced by the feeding of cuprizone (CPZ)-containing diet. We observed the reduction in corpus callosal adenomatous polyposis coli (APC)+ OLs with IL-33 expression in mice subjected to CPZ feeding for durations of 6 and 8 weeks. In parallel, the levels of IL-33 in the corpus callosum declined after CPZ-containing diet. Furthermore, we conducted experiments utilizing primary oligodendrocyte precursor cells (OPCs) and mature OLs, which were exposed to CPZ. A decrease in the expression of myelin basic protein (MBP) was evident in the cultures of mature OLs after treatment with CPZ. Additionally, both IL-33 mRNA and protein levels exhibited downregulation. To counteract the diminished IL-33 levels induced by CPZ, we employed a lentiviral vector to overexpress IL-33 in OLs. Intriguingly, the overexpression of IL-33 (IL33OE) in OLs resulted in a more distinct membranous morphology following CPZ treatment when compared to that observed in OL Mock cultures. Moreover, MBP protein levels in the presence of CPZ were higher in IL33OE OLs than that detected in OL Mock cultures. These findings collectively indicate that IL-33 possesses the capability to mitigate CPZ-induced damage and bolster OL homeostasis. In summary, our study underscores the importance of IL-33 in the context of demyelinating diseases, shedding light on its potential therapeutic implications for fostering remyelination and preserving OL function.

Dexamethasone Suppresses IL-33-exacerbated Malignant Phenotype of U87MG Glioblastoma Cells via NF-κB and MAPK Signaling Pathways

BACKGROUND

Interleukin (IL)-33 is highly expressed in glioblastoma (GBM) and promotes tumor progression. Targeting IL-33 may be an effective strategy for the treatment of GBM. Dexamethasone (DEX) is a controversial drug routinely used clinically in GBM therapy. Whether DEX has an effect on IL-33 is unknown. This study aimed to investigate the effect of DEX on IL-33 and the molecular mechanisms involved.

METHODS

U87MG cells were induced by tumor necrosis factor (TNF)-α to express IL-33 and then treated with DEX. The mRNA levels of IL-33, NF-κB p65, ERK1/2, and p38 were determined by real-time quantitative PCR. The expression of IL-33, IkBα (a specific inhibitor of NF-κB) and MKP-1 (a negative regulator of MAPK), as well as the phosphorylation of NF-κB, ERK1/2 and p38 MAPK, were detected by Western blotting. The secretion of IL-33 was measured by ELISA. The proliferation, migration and invasion of U87MG cells were detected by CCK8 and transwell assays, respectively.

RESULTS

DEX significantly reduced TNF-α-induced production of IL-33 in U87MG cells, which was dependent on inhibiting the activation of the NF-κB, ERK1/2 and p38 MAPK signaling pathways, and was accompanied by the increased expression of IkBα but not MKP-1. Furthermore, the proliferation, migration and invasion of U87MG cells exacerbated by IL-33 were suppressed by DEX.

CONCLUSION

DEX inhibited the production and tumor-promoting function of IL-33. Whether DEX can benefit GBM patients remains controversial. Our results suggest that GBM patients with high IL-33 expression may benefit from DEX treatment and deserve further investigation.

Inhibition of IL-33 signaling ameliorate hepatic fibrosis with decreasing MCP-1 in a mouse model of diabetes and non-alcoholic steatohepatitis; comparison for luseogliflozin, an SGLT2 inhibitor

Non-alcoholic fatty liver disease (NAFLD) is increasing globally, and seeking therapeutic molecule targets is urgent. Several studies have demonstrated that IL-33 plays an important role in the progression of Non-alcoholic steatohepatitis (NASH) with fibrosis and the proliferation of hepatocellular carcinoma (HCC). However, whether the inhibition of IL-33 signaling prevents NAFLD from progressing to NASH and HCC has not been clarified. We investigated the effects of a novel antibody, IL-33RAb, and luseogliflozin, a SGLT2 inhibitor, when administered to a model mouse for NASH and HCC, and their effects were compared to investigate the mechanisms of how IL-33 is involved in the pathogenesis of NASH progression. Compared with the positive control of luseogliflozin, inhibition of IL-33 signaling ameliorated decreasing hepatic fibrosis via decreasingαSMA and MCP-1, and also partially suppressed the progression of the HCC cell line in in vitro experiments. These findings suggest that inhibition of IL-33 possibly prevents progression from NASH to HCC, and their effect may be a newly arrived therapeutic agent.

Serum interleukin-33 combined with FEF75% z-score and FeNO improves the diagnostic accuracy of asthma in children

OBJECTIVE

To investigate the diagnostic efficacy of serum IL-33 single indicator and combined indicators for asthma in children.

METHODS

132 children were initially diagnosed with asthma during acute exacerbation and 100 healthy children were included. Serum IL-33 concentration differences were compared between asthmatic and normal children. Correlations between IL-33 with pulmonary function parameters, FeNO, peripheral blood EOS counts and serum total IgE were analyzed in asthmatic children. ROC curves were used to assess IL-33 diagnostic efficacy and its combined indicators. To prevent overfitting of the predictive model, the hold-out cross-validation method was used.

RESULTS

(1) Serum IL-33 concentrations were significantly higher in children with asthma than in normal children (p < 0.001). (2) IL-33 concentration was negatively correlated with FVC z-score, FEV1 z-score and FEF75% z-score in asthmatic children (p < 0.05). (3) The area under the ROC curve of IL-33 was 0.821, which was higher than those of FeNO, FVC z-score, and FEV1 z-score. (4) Cross-validation of the combined indicators showed that IL-33 significantly improved asthma diagnostic efficacy. The combination of IL-33, FEF75% z-score, and FeNO showed the highest diagnostic efficacy, with the AUC, sensitivity, and specificity of the combined indicator being 0.954, 90.1%, and 89. 0%, respectively, and good extrapolation of the predictive model.

CONCLUSION

Serum IL-33 is higher in children with asthma and increases with the severity of pulmonary ventilation obstruction. A single indicator of serum IL-33 demonstrates moderate diagnostic accuracy, and its combination with FEF75% z-score and FeNO significantly improves the diagnostic accuracy in childhood asthma.

Potential mechanistic roles of Interleukin-33 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that occurs mainly in synovial joints, causing synovial inflammation and joint injury. If diagnosed and treated in time, the disease can be well controlled. However, in clinical practice, patients often fail to get timely and effective treatment due to misdiagnosis, missed diagnosis, and other reasons, resulting in deterioration of the condition and poor prognosis, seriously affecting the patient's quality of life. So far, the pathogenesis of RA is still unclear. In recent years, it has been found that the imbalance of cytokines plays a vital role in the occurrence and development of RA. Most RA-related cytokines are produced by immune cells, which bind to the specific receptors of effector cells through paracrine and autocrine pathways. The effect of cytokines on inflammation can be divided into pro-inflammatory and anti-inflammatory factors. When the impact of pro-inflammatory factors is more significant than anti-inflammatory factors, the condition of RA will be aggravated, resulting in more inflammatory severe reactions and immune disorders. Interleukin-33 (IL-33) is a new member of the interleukin-1(IL-1) family, and its receptor is suppression of tumorigenicity 2 (ST2). IL-33 plays a vital role in immune diseases such as RA by promoting a series of biochemical reactions in macrophages, mast cells, granulocytes, and other cells. This article aims to summarize the research progress of IL-33 in the pathogenesis of RA in recent years, discuss its role in the pathogenesis of RA, and provide new ideas for the prevention and treatment of RA in the future.

Decoding the IL-33/ST2 Axis: Its Impact on the Immune Landscape of Breast Cancer

Interleukin-33 (IL-33) has emerged as a critical cytokine in the regulation of the immune system, showing a pivotal role in the pathogenesis of various diseases including cancer. This review emphasizes the role of the IL-33/ST2 axis in breast cancer biology, its contribution to cancer progression and metastasis, its influence on the tumor microenvironment and cancer metabolism, and its potential as a therapeutic target. The IL-33/ST2 axis has been shown to have extensive pro-tumorigenic features in breast cancer, starting from tumor tissue proliferation and differentiation to modulating both cancer cells and anti-tumor immune response. It has also been linked to the resistance of cancer cells to conventional therapeutics. However, the role of IL-33 in cancer therapy remains controversial due to the conflicting effects of IL-33 in tumorigenesis and anti-tumor response. The possibility of targeting the IL-33/ST2 axis in tumor immunotherapy, or as an adjuvant in immune checkpoint blockade therapy, is discussed.

Plasma IL-33 levels and immune activation in HIV-TB coinfection: a cross-sectional study in Yaoundé, Cameroon

Introduction

HIV-1 and Mtb are characterized by immune activation and unbalances production of cytokines, but the expression of IL33 in HIV/TB coinfection remain understudied. This study aimed to evaluate the level of IL-33 in plasma of HIV and M. tuberculosis (HIV/TB) coinfected patients compared to patients with respective mono infections in Yaoundé.

Methods

a cross-sectional study was conducted among patients attending the pneumology service and HIV treatment center of the Yaoundé Jamot Hospital. Plasma samples of 157 HIV/TB coinfected patients (n =26, 50% males and 50% females, mean age 39), HIV-1 monoinfected patients (n = 41, 41% males and 59% females, mean age 35), TB monoinfected patients (n = 48, 56% males and 44% females, mean age 37) and healthy controls (n = 42, 29% males and 71% females, mean age 32) were examined by enzyme-linked immunoassay (ELISA) to detect the levels of IL-33 cytokine.

Results

plasma level of IL-33 were higher in HIV/TB coinfected (33.1±30.9 pg/ml) and TB monoinfected individuals (15.1±2.9 pg/ml) compared to healthy controls (14.0±3.4 pg/ml) and could not be detected in most of the HIV-1 monoinfected individuals (12.6±8.7 pg/ml). Interestingly, the increased plasma level of IL-33 in HIV/TB coinfected patients showed a statistically significant difference between healthy controls (33.1±30.9 pg/ml vs 14.0±3.4 pg/ml, P<0.0001) and HIV-1 monoinfected patients (33.1±30.9 pg/ml vs 12.6±8.7 pg/ml, P=0.0002). We further found that IL-33 was higher in patients with high viral load group (40.6±59.7 pg/ml vs 12.6±1.8 pg/ml), P= 0.47) whereas patients under highly active antiretroviral therapy (HAART) showed decreased level of IL-33 concentration as the number of years under ART increased. Our data showed a positive association between plasma IL-33 and viral load in the context of HIV/TB coinfection in our study population with a positive Pearson coefficient of r=0.21.

Conclusion

this study indicates that plasma level of IL-33 differs among HIV/TB coinfected patients and respective monoinfections patients. The increased level of plasma IL-33 reveals that IL-33 measurement in HIV-1 monoinfected patients may represent an early predictor of development of tuberculosis.

IL-33 regulates Müller cell-mediated retinal inflammation and neurodegeneration in diabetic retinopathy

Diabetic retinopathy (DR) is characterised by dysfunction of the retinal neurovascular unit, leading to visual impairment and blindness. Müller cells are key components of the retinal neurovascular unit and diabetes has a detrimental impact on these glial cells, triggering progressive neurovascular pathology of DR. Amongst many factors expressed by Müller cells, interleukin-33 (IL-33) has an established immunomodulatory role, and we investigated the role of endogenous IL-33 in DR. The expression of IL-33 in Müller cells increased during diabetes. Wild-type and Il33-/- mice developed equivalent levels of hyperglycaemia and weight loss following streptozotocin-induced diabetes. Electroretinogram a- and b-wave amplitudes, neuroretina thickness, and the numbers of cone photoreceptors and ganglion cells were significantly reduced in Il33-/- diabetic mice compared with those in wild-type counterparts. The Il33-/- diabetic retina also exhibited microglial activation, sustained gliosis, and upregulation of pro-inflammatory cytokines and neurotrophins. Primary Müller cells from Il33-/- mice expressed significantly lower levels of neurotransmitter-related genes (Glul and Slc1a3) and neurotrophin genes (Cntf, Lif, Igf1 and Ngf) under high-glucose conditions. Our results suggest that deletion of IL-33 promotes inflammation and neurodegeneration in DR, and that this cytokine is critical for regulation of glutamate metabolism, neurotransmitter recycling and neurotrophin secretion by Müller cells.

A novel anti-IL-33 antibody recognizes an epitope FVLHN of IL-33 and has a therapeutic effect on inflammatory diseases

As a crucial member of the Interleukin-1 (IL-1) family, IL-33 plays an indispensable role in modulating inflammatory responses. Here, we developed an effective anti-human IL-33 monoclonal antibody (mAb) named 5H8. Importantly, we have identified an epitope (FVLHN) of IL-33 protein as a recognition sequence for 5H8, which plays an important role in mediating the biological activity of IL-33. We observed that 5H8 significantly suppressed IL-33-induced IL-6 expression in bone marrow cells and mast cells in a dose-dependent manner in vitro. Furthermore, 5H8 effectively relievedHDM-induced asthma and PR8-induced acute lung injury in vivo. These findings indicate that targeting the FVLHN epitope is critical for inhibiting IL-33 function. In addition, wedetected that the Tm value of 5H8 was 66.47℃ and the KD value was 173.0 pM, which reflected that 5H8 had good thermal stability and high affinity. Taken together, our data suggest that our newly developed 5H8 antibody has potential as a therapeutic antibody for treating inflammatory diseases.

Anti-interleukin 33 treatment alleviates psoriatic dermatitis in mice induced imiquimod

Interleukin-33（IL-33), is constitutively expressed in the epithelial cells of the skin. It has been reported that IL-33 contributed to the severity of the disease in psoriasis-like mouse models. In the current study, we evaluated the effect of anti-IL-33 antibody (Ab) in imiquimod-induced psoriatic dermatitis in mice. Our observations showed that anti-IL-33 Ab ameliorated the erythema, scaling, epidermal thickness and spleen index. Additionally, we found anti-IL-33 Ab significantly decreased the expression of psoriasis-related cytokines. Moreover, anti-IL-33 Ab significantly reduced Ki-67 positive cells, CD3⁺CD4⁺T cells, and CD3⁺CD8⁺T cells in the skin lesions. Furthermore, anti-IL-33 Ab treatment down-regulated the expression of phosphorylation of STAT3 and IL-33 in model mouse. These results indicated that the anti-IL-33 Ab alleviated the seriousness of skin lesions, inhibited the activation of the STAT3, lymphocyte infiltration and the secretion of pro-inflammatory cytokines in imiquimod-induced psoriatic dermatitis in mice, suggesting IL-33 may be a therapeutic target for the treatment of psoriasis.

In acromegalic patients the serum levels of interleukin-33 and Resolvin D1 influence skin perfusion of hands: A pilot study

AIM

Acromegaly is a rare chronic disease, caused by the over-secretion of growth hormone (GH), that creates a pro-inflammatory state, but the exact mechanisms by which GH or insulin-like growth factor 1 (IGF-I) act on inflammatory cells are not fully understood. Aim of the study was to evaluate Interleukin-33 (IL33) and D-series resolvins 1 (RvD1) and the skin perfusion of hands in patients with acromegaly (AP) and healthy controls (HC).

METHODS

IL33 and RvD1 have been assessed in 20 AP and 20 HC. Nailfold videocapillaroscopy (NVC) was performed and skin perfusion of hands was assessed by laser speckle contrast analysis (LASCA) in both populations.

RESULTS

IL33 was significantly higher in AP compared to HC [73.08 pg/ml (IQR 47.11-100.80 pg/ml) vs 41.5 4 pg/ml (IQR 20.16-55.49 pg/ml), p < 0.05] and RvD1 was significantly lower in AP than HC [36.1 pg/ml (IQR 27.88-66.21 pg/ml) vs 60.01 pg/ml (IQR 46.88-74.69 pg/ml), p < 0.05]. At LASCA, peripheral blood perfusion (PBP) was significantly lower in AP compared to HC [56.66 pU (IQR 46.29-65.44 pU) vs 87 pU (IQR 80-98 pU), p < 0.001]. The median values of ROI1 and ROI3 were significantly lower in AP compared to HC [112.81 pU (IQR 83.36-121.69 pU) vs 131 pU (IQR 108-135 pU), p < 0.05] and [59.78 pU (IQR 46.84-79.75 pU) vs 85 pU (IQR 78-98 pU), p < 0.05], respectively. The proximal-distal gradient (PDG) was observed in 8 of 20 (40 %) AP.

CONCLUSION

Serum IL33 is higher in AP compared to HC; conversely, RvD1 is lower in AP compared to HC. Reduction of PBP of hands was present in AP compared to HC, probably due to endothelial dysfunction.

Modulation of IL-33/ST2 signaling as a potential new therapeutic target for cardiovascular diseases

IL-33 belongs to the IL-1 family of cytokines, which function as inducers of Th2 cytokine production by binding with ST2L and IL-1RAcP. This, in turn, activates various signaling pathways, including the mitogen-activated protein kinase (MAPK), the inhibitor of Kappa-B kinase (IKK) pathway, and the phospholipase D-sphingosine kinase pathway. IL-33 has demonstrated protective effects against various cardiovascular diseases (CVDs) by inducing Th2 cytokines and promoting alternative activating M2 polarization. However, the soluble decoy form of ST2 (sST2) mitigates the biological effects of IL-33, exacerbating CVDs. Furthermore, IL-33 also plays a significant role in the development of asthma, arthritis, atopic dermatitis, and anaphylaxis through the activation of Th2 cells and mast cells. In this review, we aim to demonstrate the protective role of IL-33 against CVDs from 2005 to the present and explore the potential of serum soluble ST2 (sST2) as a diagnostic biomarker for CVDs. Therefore, IL-33 holds promise as a potential therapeutic target for the treatment of CVDs.

Extended characterization of IL-33/ST2 as a predictor for wound age determination in skin wound tissue samples of humans and mice

Interleukin (IL)-33, an important inflammatory cytokine, is highly expressed in skin wound tissue and serum of humans and mice, and plays an essential role in the process of skin wound healing (SWH) dependent on the IL-33/suppression of tumorigenicity 2 (ST2) pathway. However, whether IL-33 and ST2 themselves, as well as their interaction, can be applied for skin wound age determination in forensic practice remains incompletely characterized. Human skin samples with injured intervals of a few minutes to 24 hours (hs) and mouse skin samples with injured intervals of 1 h to 14 days (ds) were collected. Herein, the results demonstrated that IL-33 and ST2 are increased in the human skin wounds, and that in mice skin wounds, there is an increase over time, with IL-33 expression peaking at 24 hs and 10 ds, and ST2 expression peaking at 12 hs and 7 ds. Notably, the relative quantity of IL-33 and ST2 proteins < 0.35 suggested a wound age of 3 hs; their relative quantity > 1.0 suggested a wound age of 24 hs post-mouse skin wounds. In addition, immunofluorescent staining results showed that IL-33 and ST2 were consistently expressed in the cytoplasm of F4/80-positive macrophages and CD31-positive vascular endothelial cells with or without skin wounds, whereas nuclear localization of IL-33 was absent in α-SMA-positive myofibroblasts with skin wounds. Interestingly, IL-33 administration facilitated the wound area closure by increasing the proliferation of cytokeratin (K) 14 -positive keratinocytes and vimentin-positive fibroblasts. In contrast, treating with its antagonist (i.e., anti-IL-33) or receptor antagonist (e.g., anti-ST2) exacerbated the aforementioned pathological changes. Moreover, treatment with IL-33 combined with anti-IL-33 or anti-ST2 reversed the effect of IL-33 on facilitating skin wound closure, suggesting that IL-33 administration facilitated skin wound closure through the IL-33/ST2 signaling pathway. Collectively, these findings indicate that the detection of IL-33/ST2 might be a reliable biomarker for the determination of skin wound age in forensic practice.

Symbiotic microbiome Staphylococcus epidermidis restricts IL-33 production in allergic nasal epithelium via limiting the cellular necroptosis

BACKGROUND

Allergic rhinitis (AR) is characterized by airway inflammation in nasal mucosa from inhaled allergens and interleukin (IL)-33 is the potent inducer of Th2 inflammation in allergic nasal epithelium. Staphylococcus epidermidis is one of the most abundant colonizers of the healthy human nasal mucosa and might impact the allergen-induced inflammatory responses in the nasal epithelium. Thus, we sought to characterize the mechanism of S. epidermidis regulating Th2 inflammation and IL-33 production in AR nasal mucosa.

RESULTS

The AR symptoms were alleviated and eosinophilic infiltration, serum IgE levels, and Th2 cytokines were significantly decreased in OVA-sensitized AR mice in response to human nasal commensal S. epidermidis. The inoculation of S. epidermidis to normal human nasal epithelial cells reduced IL-33 and GATA3 transcriptions and also reduced IL-33 and GATA3 expression in AR nasal epithelial (ARNE) cells and the nasal mucosa of AR mice. Our data exhibited that the cellular necroptosis of ARNE cells might be involved in IL-33 production and inoculation of S. epidermidis decreased the phosphorylation of necroptosis enzymes in ARNE cells, which was related to the reduction of IL-33 production.

CONCLUSIONS

We present that human nasal commensal S. epidermidis reduces allergic inflammation by suppressing IL-33 production in nasal epithelium. Our findings indicate that S. epidermidis serves a role in blocking allergen-induced cellular necroptosis in allergic nasal epithelium which might be a key mechanism of reduction of IL-33 and Th2 inflammation.

[Regulating the immune response to carbon tetrachloride-induced liver fibrosis in mice by blocking inducible co-stimulatory molecules and interleukin-33]

Objective: To investigate the effects of combined blockade of interleukin-33 (IL-33) and inducible co-stimulatory molecule (ICOS) on carbon tetrachloride-induced chronic liver fibrosis and imbalance of T helper lymphocyte subsets in mice. Methods: There were 40 BALB/c mice in each model and control group. Flow cytometry was used to determine the proportion of Th1/Th2/Th17 cells in the splenic lymphocyte suspension of mice, the expression levels of interferon γ, IL-4, and IL-17 in the splenic lymphocyte suspension of liver fibrosis mice after combined blockade of IL-33 and ICOS, and the pathological changes of liver histopathology in mice with liver fibrosis. Two independent sample t-test was used to compare data between groups. Results: Compared with the non-blocking group, the proportion of Th2 and Th17 cells in the IL-33/ICOS blocking group was significantly down-regulated (Th2: 65.96% ± 6.04% vs. 49.09% ± 7.03%; Th17: 19.17% ± 4.03% vs. 9.56% ± 2.03%), while the proportion of Th1 cells and Th1/Th2 ratio were up-regulated (Th1: 17.14% ± 3.02% vs. 31.93% ± 5.02%; Th1/Th2: 0.28 ± 0.06 vs. 0.62 ± 0.23), and the difference was statistically significant (t = 5.15, 6.03, 7.14, 4.28, respectively, with P < 0.05). After entering the chronic inflammation stage of liver fibrosis in mice (10 weeks), compared with the non-blocking group, the expression levels of IL-4 and IL-17 in the blockade group were significantly down-regulated [IL-4: (84.75 ± 14.35) pg/ ml vs. (77.88 ± 19.61) pg/ml; IL-17: (72.38 ± 15.13) pg/ml vs. (36.38 ± 8.65) pg/ml], while the expression of interferon γ was up-regulated [(37.25 ± 11.51) pg/ml vs. (77.88 ± 19.61) pg/ml], and the difference was statistically significant (t: IL-4: 4.71; IL-17: 5.84; interferon γ: 5.05, respectively, with P < 0.05). Liver histopathological results showed that hepatic necrosis, hepatic lobular structural disorder, and fibrous tissue hyperplasia were significantly lower in the blockade group than those in the non-blocking group at 13 weeks of liver fibrosis. Conclusion: Combined blockade of the ICOS signaling pathway and IL-33 can regulate Th2 and Th17 polarization, down-regulate the inflammatory response, and inhibit or prevent the occurrence and progression of fibrosis.

Comparison of Interleukin-33 Serum Levels in Patients with Breast Cancer and Idiopathic Granulomatous Mastitis

BACKGROUND

Breast cancer (BC) is the main cause of cancer death in women. Idiopathic granulomatous mastitis (IGM), a rare chronic disease that clinically mimics breast carcinoma, and is associated with high mortality and morbidity, but an immediate and accurate diagnosis can substantially decrease these rates. Expressed by numerous human tissues, interleukin-33 (IL-33) has an inductive role in the network of pro-inflammatory cytokines. The aim of this study was to investigate the serum levels of IL-33 in BC and IGM patients in comparison with healthy women.

MATERIALS AND METHODS

This descriptive-analytical study was carried out on 28 patients with BC and 25 patients with IGM as the patient groups and 25 healthy volunteers with normal screening reports as the control group. Histopathological pattern of BC and IGM were confirmed by specialized pathologists. The serum concentration of IL-33 was measured using enzyme-linked immunosorbent assay (ELISA) kit according to the manufacturer's instructions.

RESULTS

The mean age of the patients with BC and IGM and the control group was 49.1, 37.1, and 36.8 years, respectively. There was no significant difference in IL-33 expression among the participants with regard to age, marital status, body mass index (BMI), and menopausal status. IL-33 assay indicated a significant difference between the BC (P=0.011) and IGM (P=0.031) groups compared to the controls, although no substantial differences were observed between the IGM and BC groups.

CONCLUSION

IL-33 can be considered a significant factor distinguishing IGM and BC patients from controls, although it cannot be applied to diagnose and differentiate BC from IGM patients.
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Interleukin-33 as a Biomarker Affecting Intrathecal Synthesis of Immunoglobulin in Neuromyelitis Optica Spectrum Disorder and Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

INTRODUCTION

The purpose of this study was to analyze IL-33 maybe as a biomarker especially with respect to intrathecal immunoglobulin G (IgG) synthesis which was involved in the immune-mediated process in the demyelinating disease of the central nervous system.

METHODS

We aimed to determine the risk association of the serum and CSF levels of IL-33 in aquaporin-4 (AQP4)+neuromyelitis optica spectrum disorder (NMOSD) patients and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) patients compared with the control group. Levels of inflammatory (IL-2, IL-4, IL-6, and IL-10) markers and QAlb, the IgG index, and 24-h IgG synthesis rate were assessed in 28 AQP4+NMOSD patients and 11 MOGAD patients. Disease severity was assessed using the Expanded Disability Status Scale (EDSS).

RESULTS

The level of IL-33 in serum decreased first but then increased gradually in AQP4+NMOSD and MOGAD. The serum level of IL-2, IL-4, and IL-10 increased more significantly and decreased more rapidly after methylprednisolone treatment. The level of IL-33 in CSF increased progressively in AQP4+NMOSD and MOGAD, especially in MOGAD. The QAlb levels were increased significantly in the CSF of MOGAD patients and AQP4+NMOSD patients on the acute stage of the disease. The IgG index and 24-h IgG synthesis rate were also increased significantly in the CSF of two groups similarly.

CONCLUSIONS

Thus, we concluded that IL-33 may induce dysfunction of the blood-brain barrier and lead to intrathecal synthesis of immunoglobulin in the AQP4+NMOSD and MOGAD, especially in MOGAD. It maybe as a biomarker, at least in part, was involved in the demyelinating diseases of the central nervous system.

[Effect of acupuncture pretreatment of "Quchi"(LI11) and "Xuehai" (SP10) on mast cells and IL-33/ST2 in rats with urticaria]

OBJECTIVE

To observe the effect of electroacupuncture (EA) pretreatment at "Quchi "(LI11) and "Xuehai "(SP10) on expression of interleukin (IL)-33, suppression of tumorigenicity 2 (ST2) and mast cell degranulation in sensitive area of skin tissue in rats with urticaria, so as to explore its mechanisms underlying prevention of urticaria.

METHODS

A total of 32 male SD rats were randomly divided into blank control, model, EA preconditioning and medication groups, with 8 rats in each group. The urticaria model was established by topical injection of the prepared anti-ovalbumin serum (foreign serum, 0.1 mL/spot) along the bilateral sides of the spinal column on the back, followed by injection of mixture solution of ovalbumin, 0.5% evans blue and normal saline via the tail vein 48 h later. EA intervention (2 Hz/15 Hz, 1 mA) was applied to bilateral LI11 and SP10 for 20 min, once daily for 7 d before modeling.Back sensitization was started from the 5th day on. Rats of the medication group received gavage of loratadine, and those of the model group received gavage of the same volume of normal saline. The diameter of evans blue spots at the back skin tissue was measured; the histopathological changes of the blue spot tissues were observed by light microscope after H.E. staining. The state of degranulation of mast cells in the subcutaneous loose connective tissue was observed by using toluidine blue staining. Serum IgE and histamine contents were detected by ELISA, and the immunoactivity of IL-33 and ST2 in the skin and subcutaneous tissues of the sensitized spots (evans blue exudation spots) was observed by immunohistochemistry.

RESULTS

Compared with the blank control group, the diameter of evans blue spot, degranulation rate of mast cells, serum IgE and histamine contents, and the immunoactivity of IL-33 and ST2 in the evans blue exudation spot tissues were significantly increased in the model group (P<0.01). In comparison with the model group, the increase of the above-mentioned indexes was reversed in both EA and medication groups (P<0.01，P<0.05). No significant differences were found between the EA and medication groups in down-regulating the levels of the 6 indexes. H.E. staining of the blue spot tissues of rats in the model group showed incomplete structure of the epidermal layer of the skin, unclear interface of tissues, incomplete keratinization, chaotic epidermal cells, disorderly arrangement of fibers in the dermis, and infiltration of inflammatory cells and edema, which was relatively milder in the EA and medication groups.

CONCLUSION

EA preconditioning can prevent urticaria (reduce size and sensitive reactions) in rats, which may be associated with its functions in lowering the level of IgE through inhibiting IL-33 and ST2.

Melatonin ameliorates neurological deficits through MT2/IL-33/ferritin H signaling-mediated inhibition of neuroinflammation and ferroptosis after traumatic brain injury

Although traumatic brain injury (TBI) is a common cause of death and disability worldwide, there is currently a lack of effective therapeutic drugs and targets. To reveal the complex pathophysiologic mechanisms of TBI, we performed transcriptome analysis of the mouse cerebral cortex and immunohistochemical analysis of human cerebral tissues. The genes Mt1, Mt2, Il33, and Fth1 were upregulated post-TBI and enriched in pathways associated with the inflammatory response, oxidative phosphorylation, and ferroptosis. As an agonist of MT1/2, melatonin (MLT) confers anti-oxidant, anti-inflammatory, and anti-ferroptosis effects after TBI. However, whether these upregulated genes and their corresponding pathways are involved in the neuroprotective effect of MLT remains unclear. In this study, interventions to inhibit MT1/2, IL-33, and ferroptosis (i.e., ferritin H (Fth)-KO) were applied post-TBI. The results showed that MLT attenuated TBI-induced cerebral edema and neurological outcomes by inhibiting inflammation and ferroptosis. Mechanistically, MLT mainly suppressed inflammatory responses and ferroptosis via the activation of MT2 and IL-33 pathways. Building on the previous finding that Fth deletion increases susceptibility to ferroptosis post-TBI, we demonstrated that Fth depletion remarkably exacerbated the post-TBI inflammatory response, and abolished the anti-inflammatory effects of MLT both in vivo and in vitro. Furthermore, the post-TBI anti-inflammatory effect of MLT, which occurs by promoting the polarization of CD206⁺ macrophages, was dependent on Fth. Taken together, these results clarified that MLT alleviates inflammation- and ferroptosis-mediated brain edema and neurological deficits by activating the MT2/IL-33/Fth pathway, which provides a novel target and theoretical basis for MLT to treat TBI patients.

Interleukin-33 and Soluble ST2 Levels in Infants with Hypoxic-Ischemic Encephalopathy

INTRODUCTION

Interleukin (IL)-33 and its receptor ST2L play key roles in the IL-33/ST2 signaling pathway. Soluble ST2 (sST2) inhibits the proper function of IL-33. sST2 levels are increased in patients with several neurological diseases, but in infants with hypoxic-ischemic encephalopathy (HIE), IL-33 and sST2 levels have not been studied. This study aimed to investigate whether serum levels of IL-33 and sST2 are useful as biomarkers of HIE severity and prognostic factors for infants with HIE.

METHODS

Twenty-three infants with HIE and 16 controls (gestational age ≥36 weeks and ≥1,800 g birth weight) were enrolled in this study. Serum levels of IL-33 and sST2 were measured at <6 h, 1-2, 3, and 7 days of age. Hydrogen-1 magnetic resonance spectroscopy was performed, and ratios of peak integrals of lactate/N-acetylaspartate (Lac/NAA) were calculated as objective indicators of brain damage.

RESULTS

In the moderate and severe HIE, serum sST2 concentrations were increased and there was a good correlation between serum sST2 and HIE severity on days 1-2, whereas no variation was observed in serum IL-33. Serum sST2 levels were positively correlated with Lac/NAA ratios (Kendall's rank correlation coefficient = 0.527, p = 0.024), and both sST2 and Lac/NAA ratios were significantly higher in HIE infants with neurological impairment (p = 0.020 and <0.001, respectively).

CONCLUSIONS

sST2 may be a useful predictor of severity and later neurological outcomes in infants with HIE. Further investigation is required to elucidate the relationship between the IL-33/ST2 axis and HIE.

Gata3 is detrimental to regulatory T cell function in autoimmune diabetes

Regulatory T cells (Tregs) protect against autoimmunity. In type 1 diabetes (T1D), Tregs slow the progression of beta cell autoimmunity within pancreatic islets. Increasing the potency or frequency of Tregs can prevent diabetes, as evidenced by studies in the nonobese diabetic (NOD) mouse model for T1D. We report herein that a significant proportion of islets Tregs in NOD mice express Gata3. The expression of Gata3 was correlated with the presence of IL-33, a cytokine known to induce and expand Gata3+ Tregs. Despite significantly increasing the frequency of Tregs in the pancreas, exogenous IL-33 was not protective. Based on these data, we hypothesized that Gata3 is deleterious to Treg function in autoimmune diabetes. To test this notion, we generated NOD mice with a Treg-specific deletion of Gata3. We found that deleting Gata3 in Tregs strongly protected against diabetes. Disease protection was associated with a shift of islet Tregs toward a suppressive CXCR3+Foxp3+ population. Our results suggest that islet Gata3+ Tregs are maladaptive and that this Treg subpopulation compromises the regulation of islet autoimmunity, contributing to diabetes onset.

Pericytes modulate islet immune cells and insulin secretion through Interleukin-33 production in mice

Introduction

Immune cells were recently shown to support β-cells and insulin secretion. However, little is known about how islet immune cells are regulated to maintain glucose homeostasis. Administration of various cytokines, including Interleukin-33 (IL-33), was shown to influence β-cell function. However, the role of endogenous, locally produced IL-33 in pancreatic function remains unknown. Here, we show that IL-33, produced by pancreatic pericytes, is required for glucose homeostasis.

Methods

To characterize pancreatic IL-33 production, we employed gene expression, flow cytometry, and immunofluorescence analyses. To define the role of this cytokine, we employed transgenic mouse systems to delete the Il33 gene selectively in pancreatic pericytes, in combination with the administration of recombinant IL-33. Glucose response was measured in vivo and in vitro, and morphometric and molecular analyses were used to measure β-cell mass and gene expression. Immune cells were analyzed by flow cytometry.

Resuts

Our results show that pericytes are the primary source of IL-33 in the pancreas. Mice lacking pericytic IL-33 were glucose intolerant due to impaired insulin secretion. Selective loss of pericytic IL-33 was further associated with reduced T and dendritic cell numbers in the islets and lower retinoic acid production by islet macrophages.

Discussion

Our study demonstrates the importance of local, pericytic IL-33 production for glucose regulation. Additionally, it proposes that pericytes regulate islet immune cells to support β-cell function in an IL-33-dependent manner. Our study reveals an intricate cellular network within the islet niche.

Interleukin-33 Ameliorates Murine Systemic Lupus Erythematosus and Is Associated with Induction of M2 Macrophage Polarisation and Regulatory T Cells

The innate cytokine IL-33 is increasingly recognised to possess biological effects on various immune cells. We have previously demonstrated elevated serum level of soluble ST2 in patients with active systemic lupus erythematosus suggesting involvement of IL-33 and its receptor in the lupus pathogenesis. This study sought to examine the effect of exogenous IL-33 on disease activity of pre-disease lupus-prone mice and the underlying cellular mechanisms. Recombinant IL-33 was administered to MRL/lpr mice for 6 weeks, whereas control group received phosphate-buffered saline. IL-33-treated mice displayed less proteinuria, renal histological inflammatory changes, and had lower serum levels of pro-inflammatory cytokines including IL-6 and TNF-α. Renal tissue and splenic CD11b+ extracts showed features of M2 polarisation with elevated mRNA expression of Arg1, FIZZI, and reduced iNOS. These mice also had increased IL-13, ST2, Gata3, and Foxp3 mRNA expression in renal and splenic tissues. Kidneys of these mice displayed less CD11b+ infiltration, had downregulated MCP-1, and increased infiltration of Foxp3-expressing cells. Splenic CD4+ T cells showed increased ST2-expressing CD4+Foxp3+ population and reduced IFN-γ+ population. There were no differences in serum anti-dsDNA antibodies and renal C3 and IgG2a deposit in these mice. Exogenous IL-33 was found to ameliorate disease activity in lupus-prone mice with induction of M2 polarisation, Th2 response, and expansion of regulatory T cells. IL-33 likely orchestrated autoregulation of these cells through upregulation of ST2 expression.

A fluorescent nano vector for early diagnosis and enhanced Interleukin-33 therapy of thoracic aortic dissection

Thoracic aortic dissection (TAD) is the most devastating complication of vascular disease. The accuracy of the clinical diagnosis and treatment of TAD at the early stage is still limited. Herein, we report a nano-delivery strategy for early diagnosis and the first case of interleukin-33 (IL-33) based therapy for the effective intervention of TAD. A targeted fluorescent nano vector (FNV) is designed to co-assemble with IL-33, which protects IL-33 and prolongs its half-life. With specific targeting ability to the thoracic aorta, FNV can diagnose TAD at its early stage through fluorescent imaging. FNV@IL-33 nanocomplex presents better therapeutic effects on mice TAD progression compared with that of IL-33 alone by reducing smooth muscle apoptosis. Administration of FNV@IL-33 two weeks before onset, the development of TAD is greatly intervened. Our study provides a novel approach for early diagnosis and effective IL-33 therapy of TAD, which opens attractive opportunities for clinical prevention of cardiovascular diseases.

Statin prevents cancer development in chronic inflammation by blocking interleukin 33 expression

Chronic inflammation is a major cause of cancer worldwide. Interleukin 33 (IL-33) is a critical initiator of cancer-prone chronic inflammation; however, its induction mechanism by the environmental causes of chronic inflammation is unknown. Herein, we demonstrate that Toll-like receptor (TLR)3/4-TBK1-IRF3 pathway activation links environmental insults to IL-33 induction in the skin and pancreas. FDA-approved drug library screen identified pitavastatin as an effective IL-33 inhibitor by blocking TBK1 membrane recruitment/activation through the mevalonate pathway inhibition. Accordingly, pitavastatin prevented chronic pancreatitis and its cancer sequela in an IL-33-dependent manner. IRF3-IL-33 axis was highly active in chronic pancreatitis and its associated pancreatic cancer in humans. Interestingly, pitavastatin use correlated with a significantly reduced risk of chronic pancreatitis and pancreatic cancer in patients. Our findings demonstrate that blocking the TBK1-IRF3 signaling pathway suppresses IL-33 expression and cancer-prone chronic inflammation. Statins present a safe and effective therapeutic strategy to prevent chronic inflammation and its cancer sequela.

IL-33 promotes increased replication of Theiler's Murine Encephalomyelitis Virus in RAW264.7 macrophage cells with an IRF3-dependent response

Interleukin-33 (IL-33), which promotes M2 macrophage development, may influence the control of viruses, such as Theiler's Murine Encephalomyelitis Virus (TMEV) that infect macrophages. Because Interferon Regulatory Factor-3 (IRF3) is also critical to control of TMEV infection in macrophages, information on the relationship between IL-33 and IRF3 is important. Thus, RAW264.7 Lucia murine macrophage lineage cells with an endogenous IRF3-ISRE promoter driving secreted luciferase and IRF3KO RAW Lucia, a subline deficient in IRF3, were challenged with TMEV. After the challenge, considerable TMEV RNA detected at 18 and 24 h in RAW cells was significantly elevated in IRF3KO RAW cells. TMEV induction of ISRE-IRF3 promoter activity, IFN-β and IL-33 gene expression, and IL-6 and IL-10 protein production, which was strong in RAW cells, was less in IRF3KO RAW cells. In contrast, expression of CD206 and ARG1, classical M2 macrophage markers, was significantly elevated in IRF3KO RAW cells. Moreover, RAW and IRF3KO RAW cells produced extracellular IL-33 prior to and after infection with TMEV and antibody blockade of the IL-33 receptor, ST2, reduced CD206 and ARG1 expression, but increased IL-6 gene expression. Pre-treating both RAW and IRF3KO RAW cells with IL-33 prior to challenge significantly increased TMEV infection, but also increased IL-33, IL-10, IL-6 mRNA expression, and NO production without increasing IFN-β. Notably, IL-33 induction of IL-33, IRF3-ISRE promoter activity, and IL-10 by TMEV or poly I:C/IFN-γ was significantly dependent upon IRF3. The results show that the expression of IL-33 and the repression of M2 macrophage phenotypic markers are dependent on IRF3 and that IL-33 decreases the ability of macrophages to control infection with macrophage-tropic viruses.

The Interleukin-33/ST2 Axis Enhances Lung-Resident CD14+ Monocyte Function in Patients with Non-Small Cell Lung Cancer

Interleukin-33 (IL-33) binds to its cognate receptor suppression of tumorigenicity 2 (ST2), leading to critical modulatory roles in immune responses during inflammation and cancers. The aim of this study was to investigate the role of IL-33/ST2 signaling in monocyte function in non-small cell lung cancer (NSCLC). Sixty-two NSCLC patients and nineteen controls were enrolled. IL-33 levels and ST2 expression were measured in peripheral blood and bronchoalveolar lavage fluid (BALF) by ELISA and flow cytometry. HLA-DR expression by CD14+ monocytes, granzyme B and proinflammatory cytokine secretion were also investigated in lipopolysaccharide-stimulated cells. CD14+ monocytes purified from BALF in the tumor site were stimulated with IL-33 in vitro, and co-cultured with a lung cancer cell line A549 cells. The cytotoxicity of monocytes with IL-33 stimulation was then assessed. IL-33 levels were lower in the peripheral blood and tumor microenvironment of NSCLC patients. There was no significant difference in peripheral ST2 expression between NSCLC patients and controls. Soluble ST2 levels were increased but membrane-bound ST2 expression in CD14+ monocytes was decreased in tumor microenvironment of NSCLC patients. There were no remarkable differences in either HLA-DR expression or proinflammatory cytokine secretion by circulating CD14+ monocytes between NSCLC patients and controls. CD14+ monocytes in the tumor microenvironment revealed a dysfunctional phenotype, which presented as lower HLA-DR expression and reduced granzyme B and proinflammatory cytokines. A higher concentration of IL-33 stimulation promoted tumor-resident CD14+ monocyte-induced target cell death. The present study indicates that IL-33/ST2 signaling pathway might enhance the activity of tumor-resident CD14+ monocytes in NSCLC.

Loss of SLC26A3 Results in Colonic Mucosal Immune Dysregulation via Epithelial-Immune Cell Crosstalk

BACKGROUND & AIMS

Down-regulation of chloride transporter SLC26A3 or down-regulated in adenoma (DRA) in colonocytes has recently been linked to the pathogenesis of ulcerative colitis (UC). Because exaggerated immune responses are one of the hallmarks of UC, these current studies were undertaken to define the mechanisms by which loss of DRA relays signals to immune cells to increase susceptibility to inflammation.

METHODS

NanoString Immunology Panel, fluorescence assisted cell sorting, immunoblotting, immunofluorescence, and quantitative real-time polymerase chain reaction assays were used in wild-type and DRA knockout (KO) mice. Interleukin (IL)-33 blocking was used to determine specific changes in immune cells and co-housing/broad spectrum antibiotics administration, and ex vivo studies in colonoids were conducted to rule out the involvement of microbiota. Colonoid-derived monolayers from healthy and UC patient biopsies were analyzed for translatability.

RESULTS

There was a marked induction of Th2 (>2-fold), CD4⁺ Th2 cells (∼8-fold), RORγt⁺ Th17, and FOXP3⁺ regulatory T cells (Tregs). DRA KO colons also exhibited a robust induction of IL-33 (>8-fold). In vivo studies using blocking of IL-33 established that T2 immune dysregulation (alterations in ILC2, Th2, and GATA3⁺ iTregs) in response to loss of DRA was due to altered epithelial-immune cell crosstalk via IL-33.

CONCLUSIONS

Loss of DRA in colonocytes triggers the release of IL-33 to drive a type 2 immune response. These observations emphasize the critical importance of DRA in mucosal immune homeostasis and its implications in the pathogenesis of UC.

Interleukin-33 Induces Neutrophil Extracellular Trap (NET) Formation and Macrophage Necroptosis via Enhancing Oxidative Stress and Secretion of Proatherogenic Factors in Advanced Atherosclerosis

Interleukin-33 (IL-33) acts as an 'alarmin', and its role has been demonstrated in driving immune regulation and inflammation in many human diseases. However, the precise mechanism of action of IL-33 in regulating neutrophil and macrophage functioning is not defined in advanced atherosclerosis (aAT) patients. Further, the role of IL-33 in neutrophil extracellular trap (NET) formation in aAT and its consequent effect on macrophage function is not known. In the present study, we recruited n = 52 aAT patients and n = 52 control subjects. The neutrophils were isolated from both groups via ficoll/percoll-based density gradient centrifugation. The effect of IL-33 on the NET formation ability of the neutrophils was determined in both groups. Monocytes, isolated via a positive selection method, were used to differentiate them into macrophages from each of the study subjects and were challenged by IL-33-primed NETs, followed by the measurement of oxidative stress by calorimetric assay and the expression of the proinflammatory molecules by quantitative PCR (qPCR). Transcript and protein expression was determined by qPCR and immunofluorescence/ELISA, respectively. The increased expression of IL-33R (ST-2) was observed in the neutrophils, along with an increased serum concentration of IL-33 in aAT compared to the controls. IL-33 exacerbates NET formation via specifically upregulating CD16 expression in aAT. IL-33-primed NETs/neutrophils increased the cellular oxidative stress levels in the macrophages, leading to enhanced macrophage necroptosis and the release of atherogenic factors and matrix metalloproteinases (MMPs) in aAT compared to the controls. These findings suggested a pathogenic effect of the IL-33/ST-2 pathway in aAT patients by exacerbating NET formation and macrophage necroptosis, thereby facilitating the release of inflammatory factors and the release of MMPs that may be critical for the destabilization/rupture of atherosclerotic plaques in aAT. Targeting the IL-33/ST-2-NETs axis may be a promising therapeutic target for preventing plaque instability/rupture and its adverse complications in aAT.

Clinical implications of interleukins-31, 32, and 33 in gastric cancer

BACKGROUND

Gastric cancer (GC) is one of the most common malignancies in China with a high morbidity and mortality.

AIM

To determine whether interleukin (IL)-31, IL-32, and IL-33 can be used as biomarkers for the detection of GC, via evaluating the correlations between their expression and clinicopathological parameters of GC patients.

METHODS

Tissue array (n = 180) gastric specimens were utilised. IL-31, IL-32, and IL-33 expression in GC and non-GC tissues was detected immunohistochemically. The correlations between IL-31, IL-32, and IL-33 expression in GC and severity of clinicopathological parameters were evaluated. Survival curves were plotted using the Kaplan-Meier method/Cox regression. Circulating IL-31, IL-32, and IL-33 were detected by ELISA.

RESULTS

We found that the expression levels of IL-31, IL-32, and IL-33 were all lower in GC than in adjacent non-GC gastric tissues (P < 0.05). IL-33 in peripheral blood of GC patients was significantly lower than that of healthy individuals (1.50 ± 1.11 vs 9.61 ± 8.00 ng/mL, P <0.05). Decreased IL-31, IL-32, and IL-33 in GC were observed in younger patients (< 60 years), and IL-32 and IL-33 were lower in female patients (P < 0.05). Higher IL-32 correlated with a longer survival in two GC subgroups: T4 invasion depth and TNM I-II stage. Univariate/multivariate analysis revealed that IL-32 was an independent prognostic factor for GC in the T4 stage subgroup. Circulating IL-33 was significantly lower in GC patients at TNM stage IV than in healthy people (P < 0.05).

CONCLUSION

Our findings may provide new insights into the roles of IL-31, IL-32, and IL-33 in the carcinogenesis of GC and demonstrate their relative usefulness as prognostic markers for GC. The underlying mechanism of IL-31, IL-32, and IL-33 actions in GC should be further explored.

Dual roles of interleukin-33 in cognitive function by regulating central nervous system inflammation

With the advent of an aging society, the incidence of dementia is increasing, resulting in a vast burden on society. It is increasingly acknowledged that neuroinflammation is implicated in various neurological diseases with cognitive dysfunction such as Alzheimer’s disease, multiple sclerosis, ischemic stroke, traumatic brain injury, and central nervous system infections. As an important neuroinflammatory factor, interleukin-33 (IL-33) is highly expressed in various tissues and cells in the mammalian brain, where it plays a role in the pathogenesis of a number of central nervous system conditions. Reams of previous studies have shown that IL-33 has both pro- and anti-inflammatory effects, playing dual roles in the progression of diseases linked to cognitive impairment by regulating the activation and polarization of immune cells, apoptosis, and synaptic plasticity. This article will summarize the current findings on the effects IL-33 exerts on cognitive function by regulating neuroinflammation, and attempt to explore possible therapeutic strategies for cognitive disorders based on the adverse and protective mechanisms of IL-33.

Inhibition of osteoclastogenesis by interleukin-33 administration in the periodontal ligament under mechanical loading

BACKGROUND AND OBJECTIVES

The molecular mechanisms mediating external root resorption are poorly understood. Interleukin-33 (IL-33) expression increased remarkably in the periodontal ligament (PDL) under orthodontic loading. The IL-33-driven responses are delicately cell type- and tissue context-dependent. It is unknown how IL-33 act on osteoclastogenesis in the context of root surface. This study aimed to investigate the effect of IL-33 on osteoclastogenesis in the PDL under mechanical loading.

MATERIALS AND METHODS

C57BL/6J mice were treated with injections of phosphate buffer saline (PBS) or recombinant mouse IL-33 (rmIL-33, 6 μl, 30 μg/ml), and subjected to models of orthodontic tooth movement. Tartrated resistant acid phosphates (TRAP)-positive cells and IL-33 expressions were examined in the PDL. IL-33 release from human PDL cells (hPDLCs) was detected by ELISA. Cementoblast-like (OCCM-30) cells were cultured in the presence of rmIL-33 to examine the release of osteoclast-regulatory proteins. The effects of rmIL-33 on osteoclastogenesis were examined in vitro in cultures of bone marrow macrophages (BMMs) and in BMMs-OCCM-30 cocultures. Expressions of osteoclast-specific or -related genes and proteins were investigated in BMMs-OCCM-30 cocultures treated with or without rmIL-33, in the presence or absence of granulocyte-macrophage colony-stimulating factor (GM-CSF) neutralizing antibody.

RESULTS

Interleukin-33 expressions were upregulated in the PDL under orthodontic loading. Static compressive force enhanced expression and release of IL-33 from hPDLCs. Administration of rmIL-33 resulted in reduced number of TRAP-positive cells in the PDL, and inhibited osteoclast differentiation from BMMs in vitro. OCCM-30 cells had varied osteoprotegerin (OPG) / receptor activator for nuclear factor-κB ligand (RANKL) secretion and increased release of GM-CSF under rmIL-33 stimulation. Treatment with rmIL-33 in BMMs-OCCM-30 cocultures resulted in inhibited differentiation and decreased activity of osteoclasts, and these effects were partially reversed by GM-CSF neutralizing antibody.

CONCLUSIONS

Interleukin-33 inhibits osteoclastogenesis in the PDL under orthodontic loading. The anti-osteoclastogenic effects were mediated partly by directly affecting osteoclast precursors and partly by cementoblast-mediated release of GM-CSF.

The role of IL-1 family of cytokines and receptors in pathogenesis of COVID-19

A global pandemic has erupted as a result of the new brand coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This pandemic has been consociated with widespread mortality worldwide. The antiviral immune response is an imperative factor in confronting the recent coronavirus disease 2019 (COVID-19) infections. Meantime, cytokines recognize as crucial components in guiding the appropriate immune pathways in the restraining and eradication of the virus. Moreover, SARS-CoV-2 can induce uncontrolled inflammatory responses characterized by hyper-inflammatory cytokine production, which causes cytokine storm and acute respiratory distress syndrome (ARDS). As excessive inflammatory responses are contributed to the severe stage of the COVID-19 disease, therefore, the pro-inflammatory cytokines are regarded as the Achilles heel during COVID-19 infection. Among these cytokines, interleukin (IL-) 1 family cytokines (IL-1, IL-18, IL-33, IL-36, IL-37, and IL-38) appear to have a strong inflammatory role in severe COVID-19. Hence, understanding the underlying inflammatory mechanism of these cytokines during infection is critical for reducing the symptoms and severity of the disease. Here, the possible mechanisms and pathways involved in inflammatory immune responses are discussed.

Counteractive Effects of IL-33 and IL-37 on Inflammation in Osteoarthritis

Osteoarthritis (OA) is a chronic inflammatory disease where pro-inflammatory cytokines, damage-associated molecular patterns (DAMPs), and macrophages play a crucial role. However, the interactive role of these mediators, the exact cause precipitating OA and definitive treatment for OA are not known yet. Moreover, the interactive role of interleukin (IL)-33 and IL-37 with other factors in the pathogenesis of OA has not been discussed elaborately. In this study, we analyzed the expression of IL-33 and IL-37 in human OA knee and hip joint cartilage tissues. The effect of increased DAMPs, IL-33, and IL-37 on IL-6, tumor necrosis factor (TNF)-α, toll-like receptors (TLRs), and matrix metalloproteinases (MMPs) expression was delineated using human normal and osteoarthritic chondrocytes. The effect of anti-inflammatory cytokine IL-37 on various mediators of inflammation in the presence of IL-33, rHMGB-1, and LPS was investigated to delineate the effects of IL-37. Further, the effects of blocking IL-33 downstream signaling and the effects of IL-33 and IL-37 on macrophage polarization were assessed along with examining the macrophage phenotypes in human OA cartilage tissues. The results of this study revealed increased expression of IL-33 in OA cartilage and that IL-33 increases IL-6, TNF-α, TLRs, and MMPs expression and favors phenotypic conversion towards the M1 phenotype, while IL-37 and blocking IL-33 receptor ST2 have opposite effects. Overall, the results suggest that blocking IL-33 and increasing IL-37 act synergistically to attenuate inflammation and might serve as potential therapeutics in OA.

Inhibition of Spinal Interleukin-33 Attenuates Peripheral Inflammation and Hyperalgesia in Experimental Arthritis

Accumulating evidence indicates that the continuous and intense nociceptive from inflamed tissue may increase the excitability of spinal dorsal horn neurons, which can signal back and modulate peripheral inflammation. Previous studies have demonstrated that spinal interleukin (IL)-33 contributes to the hyperexcitability of spinal dorsal horn neurons. This study was undertaken to investigate whether spinal IL-33 can also influence a peripheral inflammatory response in a rat model of arthritis. Lentivirus-delivered short hairpin RNA targeting IL-33 (LV-shIL-33) was constructed for gene silencing. Rats with adjuvant-induced arthritis (AIA) were injected intrathecally with LV-shIL-33 3 days before the complete Freund's adjuvant (CFA) injection. During an observation period of 21 days, pain-related behavior and inflammation were assessed. In addition, the expression of spinal proinflammatory cytokines and the activation of spinal extracellular signal-regulated kinase (ERK) and nuclear factor-κB (NF-κB) pathways were evaluated on 9 days after CFA treatment. The existence of tissue injury or inflammation in rats with AIA resulted in the upregulation of spinal IL-33, which is predominantly expressed in neurons, astrocytes, and oligodendrocytes. Intrathecal administration of LV-shIL-33 significantly alleviated hyperalgesia, paw swelling, and joint destruction, and attenuated the expression of proinflammatory cytokines [IL-6, IL-1β, and tumor necrosis factor-α (TNF-α)], as well as the activation of ERK and NF-κB/p65 in the spinal cord. Our data suggest that spinal IL-33 contributes to the development of both peripheral inflammation and hyperalgesia. Thus, interference with IL-33 at the spinal level might represent a novel therapeutic target for painful inflammatory disorders.

Discovery of small molecular inhibitors for interleukin-33/ST2 protein-protein interaction: a virtual screening, molecular dynamics simulations and binding free energy calculations

The interleukin-1 receptor like ST2 has emerged as a potential drug discovery target since it was identified as the receptor of the novel cytokine IL-33, which is involved in many inflammatory and autoimmune diseases. For the treatment of such IL-33-related disorders, efforts have been made to discover molecules that can inhibit the protein–protein interactions (PPIs) between IL-33 and ST2, but to date no drug has been approved. Although several anti-ST2 antibodies have entered clinical trials, the exploration of small molecular inhibitors is highly sought-after because of its advantages in terms of oral bioavailability and manufacturing cost. The aim of this study was to discover ST2 receptor inhibitors based on its PPIs with IL-33 in crystal structure (PDB ID: 4KC3) using virtual screening tools with pharmacophore modeling and molecular docking. From an enormous chemical space ZINC, a potential series of compounds has been discovered with stronger binding affinities than the control compound from a previous study. Among them, four compounds strongly interacted with the key residues of the receptor and had a binding free energy <  − 20 kcal/mol. By intensive calculations using data from molecular dynamics simulations, ZINC59514725 was identified as the most potential candidate for ST2 receptor inhibitor in this study.

Tryptase and IL-33 in Bronchoalveolar Lavage Fluid May Predict the Types of Eosinophilic Pneumonia and Disease Recurrence

INTRODUCTION

Eosinophilic pneumonia (EP) is characterized by a marked accumulation of eosinophils in the lungs and blood. Eosinophils and mast cells play an important role in the pathogenesis of EP via release of biomarkers such as tryptase and interleukin (IL)-33. However, the potential role of these biomarkers is not fully understood.

OBJECTIVES

We aimed to evaluate the differences among the levels of tryptase and IL-33 in bronchoalveolar lavage fluid (BALF) from several types of EP. We evaluated the differences between the levels of these biomarkers in the recurrent and nonrecurrent cases.

METHOD

We prospectively collected the clinical data of patients with EP, diagnosed between 2006 and 2015 in our institution. Bronchoscopy was performed before steroid treatment; BALF was collected. The clinical characteristics of EP patients and the levels of tryptase and IL-33 in BALF were evaluated.

RESULTS

We enrolled 15 patients with chronic EP (CEP), 5 with acute EP (AEP), 10 with drug-induced EP, and 6 with angiitis-related EP. Tryptase levels in the CEP group were significantly higher than that in the drug-induced EP group (p = 0.048), while the AEP group had the highest IL-33 levels. Recurrence of EP was noted in 67% of patients with CEP. The levels of tryptase and IL-33 were notably higher in the recurrent cases than that in the nonrecurrent CEP group (p = 0.004, p = 0.04, respectively). Furthermore, there was a positive correlation between the levels of tryptase and IL-33 in the BALF of patients with CEP (ρ = 0.69, p = 0.004).

CONCLUSIONS

Tryptase and IL-33 in BALF are useful biomarkers for the assessment of EP types. These biomarkers could be used to predict disease recurrence.

Breast cancer in schizophrenia could be interleukin-33-mediated

Recent epidemiological and genetic studies have revealed an interconnection between schizophrenia and breast cancer. The mutual underlying pathophysiological mechanisms may be immunologically driven. A new cluster of molecules called alarmins may be involved in sterile brain inflammation, and we have already reported the potential impact of interleukin-33 (IL-33) on positive symptoms onset and the role of its soluble trans-membranes full length receptor (sST2) on amelioration of negative symptoms in schizophrenia genesis. Furthermore, these molecules have already been shown to be involved in breast cancer etiopathogenesis. In this review article, we aim to describe the IL-33/suppressor of tumorigenicity 2 (ST2) axis as a crossroad in schizophrenia-breast cancer comorbidity. Considering that raloxifene could be tissue-specific and improve cognition and that tamoxifen resistance in breast carcinoma could be improved by strategies targeting IL-33, these selective estrogen receptor modulators could be useful in complementary treatment. These observations could guide further somatic, as well as psychiatric therapeutical protocols by incorporating what is known about immunity in schizophrenia.