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Background: Natural anti-cytokine autoantibodies can regulate homeostasis of infectious and inflammatory diseases. The anti-cytokine autoantibody profile and relevance to the pathogenesis of asthma are unknown. We aim to identify key anti-cytokine autoantibodies in asthma patients, and reveal their immunological function and clinical significance., Methods: A Luciferase Immunoprecipitation System was used to screen serum autoantibodies against 11 key cytokines in patients with allergic asthma and healthy donors. The antigen-specificity, immunomodulatory functions and clinical significance of anti-cytokine autoantibodies were determined by ELISA, qPCR, neutralization assays and statistical analysis, respectively. Potential conditions for autoantibody induction were revealed by in vitro immunization., Results: Of 11 cytokines tested, only anti-IL-33 autoantibody was significantly increased in asthma, compare to healthy controls, and the proportion positive was higher in patients with mild-to-moderate than severe allergic asthma. In allergic asthma patients, the anti-IL-33 autoantibody level correlated negatively with serum concentration of pathogenic cytokines (e.g., IL-4, IL-13, IL-25 and IL-33), IgE, and blood eosinophil count, but positively with mid-expiratory flow FEF 25 - 75 %. The autoantibodies were predominantly IgG isotype, polyclonal and could neutralize IL-33-induced pathogenic responses in vitro and in vivo. The induction of the anti-IL-33 autoantibody in blood B-cells in vitro required peptide IL-33 antigen along with a stimulation cocktail of TLR9 agonist and cytokines IL-2, IL-4 or IL-21., Conclusions: Serum natural anti-IL-33 autoantibodies are selectively induced in some asthma patients. They ameliorate key asthma inflammatory responses, and may improve lung function of allergic asthma., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Ambient fine particulate matter (PM 2.5 ) is considered a plausible contributor to the onset of chronic obstructive pulmonary disease (COPD). Mechanistic studies are needed to augment the causality of epidemiologic findings. In this study, we aimed to test the hypothesis that repeated exposure to diesel exhaust particles (DEP), a model PM 2.5 , causes COPD-like pathophysiologic alterations, consequently leading to the development of specific disease phenotypes. Sprague Dawley rats, representing healthy lungs, were randomly assigned to inhale filtered clean air or DEP at a steady-state concentration of 1.03 mg/m 3 (mass concentration), 4 h per day, consecutively for 2, 4, and 8 weeks, respectively. Pulmonary inflammation, morphologies and function were examined., Results: Black carbon (a component of DEP) loading in bronchoalveolar lavage macrophages demonstrated a dose-dependent increase in rats following DEP exposures of different durations, indicating that DEP deposited and accumulated in the peripheral lung. Total wall areas (WAt) of small airways, but not of large airways, were significantly increased following DEP exposures, compared to those following filtered air exposures. Consistently, the expression of α-smooth muscle actin (α-SMA) in peripheral lung was elevated following DEP exposures. Fibrosis areas surrounding the small airways and content of hydroxyproline in lung tissue increased significantly following 4-week and 8-week DEP exposure as compared to the filtered air controls. In addition, goblet cell hyperplasia and mucus hypersecretions were evident in small airways following 4-week and 8-week DEP exposures. Lung resistance and total lung capacity were significantly increased following DEP exposures. Serum levels of two oxidative stress biomarkers (MDA and 8-OHdG) were significantly increased. A dramatical recruitment of eosinophils (14.0-fold increase over the control) and macrophages (3.2-fold increase) to the submucosa area of small airways was observed following DEP exposures., Conclusions: DEP exposures over the courses of 2 to 8 weeks induced COPD-like pathophysiology in rats, with characteristic small airway remodeling, mucus hypersecretion, and eosinophilic inflammation. The results provide insights on the pathophysiologic mechanisms by which PM 2.5 exposures cause COPD especially the eosinophilic phenotype., (© 2023. The Author(s).)

Cytokine storms are crucial in the development of various inflammatory diseases, including sepsis and autoimmune disorders. The immunosuppressive cytokine INTERLEUKIN (IL)-37 consists of five isoforms (IL-37a-e). We identified IL-37a as a nuclear cytokine for the first time. Compared to IL-37b, IL-37a demonstrated greater efficacy in protecting against Toll-like receptor-induced cytokine hypersecretion and lethal endotoxic shock. The full-length (FL) form of IL-37a and the N-terminal fragment, which is processed by elastase, could translocate into cell nuclei through a distinctive nuclear localization sequence (NLS)/importin nuclear transport pathway. These forms exerted their regulatory effects independent of the IL-1R8 receptor by transcriptionally upregulating the nuclear receptor peroxisome proliferator-activated receptor (PPARγ). This process involved the recruitment of the H3K4 methyltransferase complex WDR5/MLL4/C/EBPβ and H3K4me1/2 to the enhancer/promoter of Pparg. The receptor-independent regulatory pathway of the nuclear IL-37a-PPARγ axis and receptor-dependent signaling by secreted IL-37a maintain homeostasis and are potential therapeutic targets for various inflammatory diseases, including sepsis., (© 2023. The Author(s), under exclusive licence to CSI and USTC.)

Background: Asthma is a common chronic respiratory disease characterized by airways inflammation, hyperresponsiveness and remodeling. IL-37, an anti-inflammatory cytokine, consists of five splice isoforms, that is, a-e. Although it has been previously shown that recombinant human IL-37b is able to inhibit airway inflammation and hyperresponsiveness in animal models of asthma, the effects and difference of other IL-37 isoforms, such as IL-37a on features of asthma are unknown., Methods: Animal models of chronic asthma were established using IL-37a and IL-37b transgenic mice with C57BL/6J background and wild-type (WT) mice sensitized and nasally challenged with ovalbumin (OVA). Airway hyperresponsiveness was measured using FlexiVent apparatus, while histological and immunohistological stainings were employed to measure airways inflammation and remodeling indexes, including goblet cell metaplasia, mucus production, deposition of collagen, hypertrophy of airway smooth muscles and pulmonary angiogenesis., Results: Compared to WT mice, both IL-37a and IL-37b transgenic mice had significant reduced airway hyperresponsiveness and the declined total numbers of inflammatory cells, predominant eosinophils into airways and lung tissues. Furthermore, all features of airways remodeling, including degrees of mucus expression, collagen deposition, hypertrophy of smooth muscles, thickness of airways and neovascularization markedly decreased in IL-37 transgenic mice compared with OVA-treated WT mice., Conclusion: Our data suggest that both IL-37a and IL-37b isoforms are able to not only ameliorate airways inflammation and airways hyperresponsiveness, but also greatly reduce airways structural changes of animal models of chronic asthma., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Adherent-invasive Escherichia coli (AIEC) have been implicated in the aetiology of Crohn's disease (CD). They are characterized by an ability to adhere to and invade intestinal epithelial cells, and to replicate intracellularly in macrophages resulting in inflammation. Proline-rich tyrosine kinase 2 (PYK2) has previously been identified as a risk locus for inflammatory bowel disease and a regulator of intestinal inflammation. It is overexpressed in patients with colorectal cancer, a major long-term complication of CD. Here we show that Pyk2 levels are significantly increased during AIEC infection of murine macrophages while the inhibitor PF-431396 hydrate, which blocks Pyk2 activation, significantly decreased intramacrophage AIEC numbers. Imaging flow cytometry indicated that Pyk2 inhibition blocked intramacrophage replication of AIEC with no change in the overall number of infected cells, but a significant reduction in bacterial burden per cell. This reduction in intracellular bacteria resulted in a 20-fold decrease in tumour necrosis factor α secretion by cells post-AIEC infection. These data demonstrate a key role for Pyk2 in modulating AIEC intracellular replication and associated inflammation and may provide a new avenue for future therapeutic intervention in CD.

Cellular and molecular immune components play a crucial role in the development and perpetuation of human malignancies, shaping anti-tumor responses. A novel immune regulator is interleukin-37 (IL-37), already shown to be involved in the inflammation associated with the pathophysiology of many human disorders, including cancer. The interplay between tumor and immune cells is of great importance, especially for highly immunogenic tumors such as bladder urothelial carcinoma (BLCA). This study aimed to investigate the potential of IL-37 and its receptor SIGIRR (single immunoglobulin IL-1-related receptor) to serve as prognostic and/or diagnostic markers in patients with BLCA. To this end, a series of bioinformatics tools processing -omics datasets and specifically designed qPCR assays on human BLCA tumors and cancer cell lines were utilized. Bioinformatics analysis revealed that IL-37 levels correlate with BLCA tumor development and are higher in patients with longer overall survival. Furthermore, mutations on SIGIRR are associated with enhanced infiltration of the tumor by regulatory T cells and dendritic cells. Based on the qPCR validation experiments, BLCA epithelial cells express the IL-37c and IL-37e isoforms, while the latter is the predominant variant detected in tumor biopsies, also associated with higher grade and the non-muscle-invasive type. This is the first time, to the best of our knowledge, that IL-37 and SIGIRR levels have been assessed in BLCA tumor lesions, and associations with pathological and survival parameters are described, while a transcript variant-specific signature is indicated to have a diagnostic potential. These data strongly indicate the need for further investigation of the involvement of this cytokine and interconnected molecules in the pathophysiology of the disease and its prospective as a therapeutic target and biomarker for BLCA.

Kinesin family member 20A (KIF20A) is a member of the kinesin family. It transports chromosomes during mitosis, plays a key role in cell division. Recently, studies proved that KIF20A was highly expressed in cancer. High expression of KIF20A was correlated with poor overall survival (OS). In this review, we summarized all the cancer that highly expressed KIF20A, described the role of KIF20A in cancer. We also organized phase I and phase II clinical trials of KIF20A peptides vaccine. All results indicated that KIF20A was a promising therapeutic target for multiple cancer., Competing Interests: The authors declare no competing interests., (© 2023 The Authors.)

Background: Metal components of environmental PM2.5 are associated with the exacerbation of allergic diseases like asthma. In our recent hospital-based population study, exposure to vanadium is shown to pose a significant risk for current asthma, but the causal relationship and its underlying molecular mechanisms remain unclear., Objective: We sought to determine whether vanadium co-exposure can aggravate house dust mite (HDM)-induced allergic airway inflammation and remodeling, as well as investigate its related mechanisms., Methods: Asthma mouse model was generated by using either vanadium pentoxide (V 2 O 5 ) or HDM alone or in combination, in which the airway inflammation and remodeling was investigated. The effect of V 2 O 5 co-exposure on HDM-induced epithelial-derived cytokine release and oxidative stress (ROS) generation was also examined by in vitro analyses. The role of ROS in V 2 O 5 co-exposure-induced cytokine release and airway inflammation and remodeling was examined by using inhibitors or antioxidant., Results: Compared to HDM alone, V 2 O 5 co-exposure exacerbated HDM-induced airway inflammation with increased infiltration of inflammatory cells and elevated levels of Th1/Th2/Th17 and epithelial-derived (IL-25, TSLP) cytokines in the bronchoalveolar lavage fluids (BALFs). Intriguingly, V 2 O 5 co-exposure also potentiated HDM-induced airway remodeling. Increased cytokine release was further supported by in vitro analysis in human bronchial epithelial cells (HBECs). Mechanistically, ROS, particularly mitochondrial-derived ROS, was significantly enhanced in HBECs after V 2 O 5 co-exposure as compared to HDM challenge alone. Inhibition of ROS with its inhibitor N-acetyl-L-cysteine (NAC) and mitochondrial-targeted antioxidant MitoTEMPO blocked the increased epithelial release caused by V 2 O 5 co-exposure. Furthermore, vitamin D 3 as an antioxidant was found to inhibit V 2 O 5 co-exposure-induced increased airway epithelial cytokine release and airway remodeling., Conclusions: Our findings suggest that vanadium co-exposure exacerbates epithelial ROS generation that contribute to increased allergic airway inflammation and remodeling., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Tu, Xiao, Lu, Liu, Wang, Yuan, Wan, Shen, Xu, Yang, Gong, Gao and Huang.)

Interleukin-37 (IL-37) is a relatively new IL-1 family cytokine that, due to its immunoregulatory properties, has lately gained increasing attention in basic and translational biomedical research. Emerging evidence supports the implication of this protein in any human disorder in which immune homeostasis is compromised, including cancer. The aim of this study was to explore the prognostic and/or diagnostic potential of IL-37 and its receptor SIGIRR (single immunoglobulin IL-1-related receptor) in human tumors. We utilized a series of bioinformatics tools and -omics datasets to unravel possible associations of IL-37 and SIGIRR expression levels and genetic aberrations with tumor development, histopathological parameters, distribution of tumor-infiltrating immune cells, and survival rates of patients. Our data revealed that amongst the 17 human malignancies investigated, IL-37 exhibits higher expression levels in tumors of lung adenocarcinoma (LUAD). Moreover, the expression profiles of IL-37 and SIGIRR are associated with LUAD development and tumor stage, whereas their high mRNA levels are favorable prognostic factors for the overall survival of patients. What is more, IL-37 correlates positively with a LUAD-associated transcriptomic signature, and its nucleotide changes and expression levels are linked with distinct infiltration patterns of certain cell subsets known to control LUAD anti-tumor immune responses. Our data indicate the potential value of IL-37 and its receptor SIGIRR to serve as biomarkers and/or immune-checkpoint therapeutic targets for LUAD patients. Further, the data highlight the urgent need for further exploration of this cytokine and the underlying pathogenetic mechanisms to fully elucidate its implication in LUAD development and progression.

Adult fibrosarcoma is an aggressive subtype of soft tissue sarcoma (STS), in which high expression of KIF20A indicates a poor prognosis. However, the precise role of KIF20A in fibrosarcoma progression remains unknown. In this study, we initially examined KIF20A expression and function in the human fibrosarcoma cell line HT-1080. The results showed that KIF20A was highly expressed in HT-1080, knockdown of KIF20A impaired cell proliferation, migration, invasion and induced G2/M arrest and cell apoptosis. Transcriptome study suggested that PI3K-Akt signal pathway was involved in these biological changes. We confirmed that PI3K-Akt and NF-κB signaling pathways were impaired after the down-regulation of KIF20A, which can be reversed by the Akt activator SC79 in HT-1080 in vitro. In a xenograft mouse model, knockdown of KIF20A inhibited tumor growth, Ki67 expression and liver metastasis. Taken together, our results suggested that KIF20A promoted fibrosarcoma progression via PI3K-Akt signaling pathway and might be a potential therapeutic target for fibrosarcoma., Competing Interests: Declaration of interest statement The authors declare that they have no conflict of interest., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: The emergence of the novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to millions of infections and is exerting an unprecedented impact on society and economies worldwide. The evidence showed that heart failure (HF) is a clinical syndrome that could be encountered at different stages during the progression of COVID-19. Shenfu injection (SFI), a traditional Chinese medicine (TCM) formula has been widely used for heart failure therapy in China and was suggested to treat critical COVID-19 cases based on the guideline for diagnosis and treatment of COVID-19 (the 7th version) issued by National Health Commission of the People's Republic of China. However, the active components, potential targets, related pathways, and underlying pharmacology mechanism of SFI against COVID-19 combined with HF remain vague., Objective: To investigate the effectiveness and possible pharmacological mechanism of SFI for the prevention and treatment of COVID-19 combined with HF., Methods: In the current study, a network analysis approach integrating active compound screening (drug-likeness, lipophilicity, and aqueous solubility models), target fishing (Traditional Chinese Medicine Systems Pharmacology, fingerprint-based Similarity Ensemble Approach, and PharmMapper databases), compound-target-disease network construction (Cytoscape software), protein-protein interaction network construction (STRING and Cytoscape software), biological process analysis (STRING and Cytoscape plug-in Clue GO) and pathway analysis (Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis) was developed to decipher the active ingredients, potential targets, relevant pathways, and the therapeutic mechanisms of SFI for preventing and treating COVID-19 combined with HF., Results: Finally, 20 active compounds (DL ≥ 0.18, 1≤Alog P ≤ 5, and -5≤LogS ≤ -1) and 164 relevant targets of SFI were identified related to the development of COVID-19 combined with HF, which were mainly involved in three biological processes including metabolic, hemostasis, and cytokine signaling in immune system. The C-T-D network and reactome pathway analysis indicated that SFI probably regulated the pathological processes of heart failure, respiratory failure, lung injury, and inflammatory response in patients with COVID-19 combined with HF through acting on several targets and pathways. Moreover, the venn diagram was used to identify 54 overlapped targets of SFI, COVID-19, and HF. KEGG pathway enrichment analysis showed that 54 overlapped targets were highly enriched to several COVID-19 and HF related pathways, such as IL-17 signaling pathway, Th17 cell differentiation, and NF-kappa B signaling pathway., Conclusions: A comprehensive network analysis approach framework was developed to systematically elucidate the potential pharmacological mechanism of SFI for the prevention and treatment of SFI against COVID-19 combined with HF. The current study may not only provide in-depth understanding of the pharmacological mechanisms of SFI, but also a scientific basis for the application of SFI against COVID-19 combined with HF., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

B lymphocyte-mediated humoral immune response is essential for protection against infectious diseases. Deeper research in B cell biology, particularly metabolism is required for the better understanding of its properties in homeostasis and in diseases. Emerging immunometabolism, including anabolism and catabolism, has tremendously impacts on immune cells from development to function and markedly advances our view on immunoregulation. Growing evidence suggests that the ultimate effect of intracellular metabolism on immune cell functions is not only influenced by the external stimuli but also by the balance of the different metabolic pathways. However, B cell immunometabolism is not deeply investigated like T cells. The complex development and differentiation processes of B cell subsets have left many untouched, but fundamental aspects in B cell metabolism. Available evidence demonstrated that the intracellular metabolism has the ubiquitous impact on B cell fate and function decisions at the transcriptional regulation and signal transduction processes. In this review, we update the recent development in the immunometabolism of B cells with the latest findings including the immune-metabolic steering on B cell development, differentiation, and function skewing, and emphasis on how immunometabolism landscape may shape B cell functions in metabolic, autoimmune, and inflammatory disorders. The metabolic interaction of B cells with other immune cells in disease context will also be discussed., (© 2022 John Wiley & Sons Ltd.)

IL-10-producing B cells (B10) are involved in the prevention of autoimmune and allergic responses but its mechanisms remain poorly understood. We took advantage of the ovalbumin-induced asthma mouse model to demonstrate that the activity of FoxO1 is upregulated in lung B cells and correlates inversely with B10 cells, while showing decreased activity in ex vivo and in vitro induced B10 cells. We further observed that FoxO1 deficiency leads to increased frequency of B10 cells. These observations have in vivo clinical evidence, as B cell specific FoxO1 deficiency leads to reduced lung eosinophils and asthma remission in mice, and there are reduced regulatory B cells and increased FoxO1 activity in B cells of asthma patients. Single cell RNA-sequencing data demonstrated a negative correlation between the expression of Foxo1 and Il10 in B cells from the mouse spleen and lung and the human lung. For a biological mechanism, FoxO1 inhibits the expression of Prdm1, which encodes Blimp-1, a transcription factor of B10 cells. Our experimental evidence in both murine and human asthma demonstrates that FoxO1 is a negative regulator of B10 cell differentiation via negatively regulating Prdm1 and its expression in B cells contributes to allergic asthma disease., (© 2022. The Author(s), under exclusive licence to Society for Mucosal Immunology.)

Background: The monophosphoryl lipid A (MPLA) is a detoxified LPS derivative and an emerging safe immune adjuvant in human vaccine development. The adjuvant MPLA promotes antigen-presenting cell (APC) function and preferentially induces a Th1 response following vaccination. However, the mechanism by which the MPLA detoxicates and exerts its adjuvants effect on T-cell, particualrly the Th1 response is unknown., Aims: We assessed the direct effects of MPLA on murine and human CD4 + T-cell proliferation and the profile of cytokine production ex vivo., Results: We report that CD4 + T-cells only express functional TLR2 and TLR4 when activated by TCR stimulation, in particularly in the presence of IFNα. The activated T cells thereafter can respond directly to MPLA. MPLA does not affect T-cell proliferation in human T cells, but can induce a balanced Th1 cytokine profile in CD4 + T-cells by reducing the production of Th1 cytokines and enhancing the production of the regulatory cytokine IL-10. The MPLA-mediated regulatory effect on activated CD4 + T-cells is TLR2 and TLR4 dependent and can be abolished by the lipid A blocker polymyxin B., Conclusion: These data provide evidence, at least in part, for the safe induction of an appropriate level of Th1 response by adjuvant MPLA in human vaccine development., (Copyright © 2021 Elsevier GmbH. All rights reserved.)

The Coronavirus Disease 2019 (COVID-19) pandemic has become a global crisis and is more devastating than any other previous infectious disease. It has affected a significant proportion of the global population both physically and mentally, and destroyed businesses and societies. Current evidence suggested that immunopathology may be responsible for COVID-19 pathogenesis, including lymphopenia, neutrophilia, dysregulation of monocytes and macrophages, reduced or delayed type I interferon (IFN-I) response, antibody-dependent enhancement, and especially, cytokine storm (CS). The CS is characterized by hyperproduction of an array of pro-inflammatory cytokines and is closely associated with poor prognosis. These excessively secreted pro-inflammatory cytokines initiate different inflammatory signaling pathways via their receptors on immune and tissue cells, resulting in complicated medical symptoms including fever, capillary leak syndrome, disseminated intravascular coagulation, acute respiratory distress syndrome, and multiorgan failure, ultimately leading to death in the most severe cases. Therefore, it is clinically important to understand the initiation and signaling pathways of CS to develop more effective treatment strategies for COVID-19. Herein, we discuss the latest developments in the immunopathological characteristics of COVID-19 and focus on CS including the current research status of the different cytokines involved. We also discuss the induction, function, downstream signaling, and existing and potential interventions for targeting these cytokines or related signal pathways. We believe that a comprehensive understanding of CS in COVID-19 will help to develop better strategies to effectively control immunopathology in this disease and other infectious and inflammatory diseases.

We have previously demonstrated that benzo(a)pyrene (BaP) co-exposure with dermatophagoides group 1 allergen (Der f 1) can potentiate Der f 1-induced airway inflammation. The underlying mechanism, however, remains undetermined. Here we investigated the molecular mechanisms underlying the potentiation of BaP exposure on Der f 1-induced airway inflammation in asthma. We found that BaP co-exposure potentiated Der f 1-induced TGFβ1 secretion and signaling activation in human bronchial epithelial cells (HBECs) and the airways of asthma mouse model. Moreover, BaP exposure alone or co-exposure with Der f 1-induced aryl hydrocarbon receptor (AhR) activity was determined by using an AhR-dioxin-responsive element reporter plasmid. The BaP and Der f 1 co-exposure-induced TGFβ1 expression and signaling activation were attenuated by either AhR antagonist CH223191 or AhR knockdown in HBECs. Furthermore, AhR knockdown led to the reduction of BaP and Der f 1 co-exposure-induced active RhoA. Inhibition of RhoA signaling with fasudil, a RhoA/ROCK inhibitor, suppressed BaP and Der f 1 co-exposure-induced TGFβ1 expression and signaling activation. This was further confirmed in HBECs expressing constitutively active RhoA (RhoA-L63) or dominant-negative RhoA (RhoA-N19). Luciferase reporter assays showed prominently increased promoter activities for the AhR binding sites in the promoter region of RhoA. Inhibition of RhoA suppressed BaP and Der f 1 co-exposure-induced airway hyper-responsiveness, Th2-associated airway inflammation, and TGFβ1 signaling activation in asthma. Our studies reveal a previously unidentified functional axis of AhR-RhoA in regulating TGFβ1 expression and signaling activation, representing a potential therapeutic target for allergic asthma., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Wang, Tu, Do, Xiao, Bhatti, Yang, Sun, Xu, Yang, Huang, Gao and Liu.)

Interleukin-33 has been demonstrated to be associated with liver damage. However, its potential value in hepatitis B virus (HBV) infection remains unknown. This study was designed to investigate the role of IL-33 in hydrodynamic HBV mouse model. Different doses of IL-33 were used to treat HBV wild-type, ST2 knockout, CD8+ T depletion, NK depletion C57BL/6 mice and C.B-17 SCID and nod SCID mouse, respectively. The concentrations of HBV DNA, HBsAg, HBeAg, and molecules related to liver function were detected in the collected serum at different time points from model mice. Intrahepatic HBcAg was visualized by immunohistochemical staining of liver tissues. In vitro , hepG2 cells were transfected with pAAV-HBV 1.2, then treated with IL-33. The results showed that IL-33 significantly reduced HBV DNA and HBsAg in a dose-dependent manner in HBV wild-type mice. However, in the IL-33 specific receptor ST2 knockout mice, their antiviral effects could not be exerted. Through immunodeficient animal models and in vivo immune cell depletion mouse model, we found that IL-33 could not play antiviral effects without NK cells. Moreover, IL-33 could reduce the levels of HBsAg and HBeAg in the supernatant of HBV-transfected hepG2 cells in vitro . Our study revealed that IL-33 could inhibit HBV through ST2 receptor in the HBV mouse model, and this effect can be impaired without NK cell. Additionally, IL-33 had the direct anti-HBV effect in vitro , indicating that IL-33 could be a potent inducer of HBV clearance and a promising drug candidate., Competing Interests: There is no conflict of interest., (Copyright © 2020 Xiuzhu Gao et al.)

Increasing evidence suggests that IL-33 plays an important role in regulating tumor development. However, conflicting results, obtained from numerous studies, have highlighted the divergent functions of IL-33. The detailed mechanisms by which IL-33 modulates tumor development merit further investigation. Here, we report that IL-33 administration can effectively inhibit the development of pulmonary metastasis of breast cancer in a mouse. In our model, IL-33 promotes the production of TNF-α by macrophages, which increases IL-33 specific receptor (ST2) expression on natural killer (NK) cells and is pivotal in IL-33-induced NK cell activation. IL-33 treatment also facilitates the production of CCL5 in the lung by eosinophils and CD8 + T cells, which mediates the recruitment of NK cells to the tumor microenvironment. The systemic activation and local recruitment of NK cells result in potent tumor rejection in the lung. Our study reports a novel mechanism for the IL-33-meditated suppression of metastatic cancer and provides potential therapeutic strategies for targeting metastatic tumor., (© 2019 UICC.)

Background: Environmental pollutants, which coexist with allergens, have been associated with the exacerbation of asthma. However, the underlying molecular mechanisms remain elusive. We sought to determine whether benzo(a)pyrene (BaP) co-exposure with dermatophagoides group 1 allergen (Der f 1) can potentiate Der f 1-induced asthma and its underlying mechanisms., Methods: The effect of BaP was investigated in Der f 1-induced mouse model of asthma, including airway hyper-responsiveness, allergic inflammation, and epithelial-derived cytokines. The impact of BaP on Der f 1-induced airway epithelial cell oxidative stress (ROS) and cytokine release was further analyzed. The role of aryl hydrocarbon receptor (AhR) signaling in BaP-promoted Der f 1-induced ROS, cytokine production, and allergic inflammation was also investigated., Results: Compared with Der f 1, BaP co-exposure with Der f 1 led to airway hyper-responsiveness and increased lung inflammation in mouse model of asthma. Increased expression of TSLP, IL-33, and IL-25 was also found in the airways of these mice. Moreover, BaP co-exposure with Der f 1 activated AhR signaling with increased expression of AhR and CYP1A1 and promoted airway epithelial ROS generation and TSLP and IL-33, but not IL-25, expression. Interestingly, AhR antagonist CH223191 or cells with AhR knockdown abrogated the increased expression of ROS, TSLP, and IL-33. Furthermore, ROS inhibitor N-acetyl-L-cysteine (NAC) also suppressed BaP co-exposure-induced expression of epithelial TSLP, IL-33, and IL-25. Finally, AhR antagonist CH223191 and NAC inhibited BaP co-exposure with Der f 1-induced lung inflammation., Conclusions: Our findings suggest that BaP facilitates Der f 1-induced epithelial cytokine release through the AhR-ROS axis., (© 2019 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.)

The pro-Th2 cytokine IL-33 is now emerging as an important Th1 cytokine-IFN-γ inducer in murine CD4(+) T cells that is essential for protective cell-mediated immunity against viral infection in mice. However, whether IL-33 can promote human Th1 cell differentiation and how IL-33 polarizes Th1 cells is less understood. We assessed the ability of IL-33 to induce Th1 cell differentiation and IFN-γ production in vitro and in vivo. We report here that IL-33 alone had no ability in Th1 cell polarization. However it potentiated IL-12-mediated Th1 cell differentiation and IFN-γ production in TCR-stimulated murine and human CD4(+) T cells in vitro and in vivo. IL-33 promoted Th1 cell development via MyD88 and synergized with IL-12 to enhance St2 and IL-12R expression in CD4(+) T cells. These data therefore provide a novel mechanism for Th1 cell differentiation and optimal induction of a Type 1 response. Thus, IL-33 is capable of inducing IL-12-dependent Th1 cell differentiation in human and mouse CD4(+) T cells., (Copyright © 2015 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Neuropathic pain from injury to the peripheral and CNS represents a major health care issue. We have investigated the role of IL-33/IL-33 receptor (ST2) signaling in experimental models of neuropathic pain in mice. Chronic constriction injury (CCI) of the sciatic nerve induced IL-33 production in the spinal cord. IL-33/citrine reporter mice revealed that oligodendrocytes are the main cells expressing IL-33 within the spinal cord together with a minor expression by neurons, microglia. and astrocytes. CCI-induced mechanical hyperalgesia was reduced in IL-33R (ST2)(-/ -) mice compared with wild-type (WT) mice. Intrathecal treatment of WT mice with soluble IL-33 receptor (IL-33 decoy receptor) markedly reduced CCI-induced hyperalgesia. Consistent with these observations, intrathecal injection of IL-33 enhanced CCI hyperalgesia and induced hyperalgesia in naive mice. IL-33-mediated hyperalgesia during CCI was dependent on a reciprocal relationship with TNF-α and IL-1β. IL-33-induced hyperalgesia was markedly attenuated by inhibitors of PI3K, mammalian target of rapamycin, MAPKs (p38, ERK, and JNK), NF-κB, and also by the inhibitors of glial cells (microglia and astrocytes). Furthermore, targeting these signaling pathways and cells inhibited IL-33-induced TNF-α and IL-1β production in the spinal cord. Our study, therefore, reveals an important role of oligodendrocyte-derived IL-33 in neuropathic pain., (© FASEB.)

Purpose: The role of IL28B gene variants and expression in hepatitis B virus (HBV) infections are not well understood. Here, we evaluated whether IL28B gene expression and rs12979860 variations are associated with HBV outcomes., Materials and Methods: IL28B genetic variations (rs12979860) were genotyped by pyrosequencing of DNA samples from 137 individuals with chronic HBV infection [50 inactive carriers (IC), 34 chronic hepatitis B (CHB), 27 cirrhosis, 26 hepatocellular carcinoma (HCC)], and 19 healthy controls. IL28A/B mRNA expression in peripheral blood mononuclear cells was determined by qRT-PCR, and serum IL28B protein was measured by ELISA., Results: Patients with IL28B C/C genotype had greater IL28A/B mRNA expression and higher IL28B protein levels than C/T patients. Within the various disease stages, compared to IC and healthy controls, IL28B expression was reduced in the CHB, cirrhosis, and HCC cohorts (CHB vs. IC, p=0.02; cirrhosis vs. IC, p=0.01; HCC vs. IC, p=0.001; CHB vs. controls, p<0.01; cirrhosis vs. controls, p<0.01; HCC vs. controls, p<0.01). When stratified with respect to serum HBV markers in the IC and CHB cohorts, IL28B mRNA and protein levels were higher in HBeAg-positive than negative individuals (p=0.01). Logistic regression analysis revealed that factors associated with high IL28B protein levels were C/C versus C/T genotype [p=0.016, odds ratio (OR)=0.25, 95% confidence interval (CI)=0.08-0.78], high alanine aminotransferase values (p<0.001, OR=8.02, 95% CI=2.64-24.4), and the IC stage of HBV infection (p<0.001)., Conclusion: Our data suggest that IL28B genetic variations may play an important role in long-term development of disease in chronic HBV infections.

Background: The initiation and regulation of pulmonary fibrosis are not well understood. IL-33, an important cytokine for respiratory diseases, is overexpressed in the lungs of patients with idiopathic pulmonary fibrosis., Objectives: We aimed to determine the effects and mechanism of IL-33 on the development and severity of pulmonary fibrosis in murine bleomycin-induced fibrosis., Methods: Lung fibrosis was induced by bleomycin in wild-type or Il33r (St2)(-/-) C57BL/6 mice treated with the recombinant mature form of IL-33 or anti-IL-33 antibody or transferred with type 2 innate lymphoid cells (ILC2s). The development and severity of fibrosis was evaluated based on lung histology, collagen levels, and lavage cytology. Cytokine and chemokine levels were quantified by using quantitative PCR, ELISA, and cytometry., Results: IL-33 is constitutively expressed in lung epithelial cells but is induced in macrophages by bleomycin. Bleomycin enhanced the production of the mature but reduced full-length form of IL-33 in lung tissue. ST2 deficiency, anti-IL-33 antibody treatment, or alveolar macrophage depletion attenuated and exogenous IL-33 or adoptive transfer of ILC2s enhanced bleomycin-induced lung inflammation and fibrosis. These pathologic changes were accompanied, respectively, by reduced or increased IL-33, IL-13, TGF-β1, and inflammatory chemokine production in the lung. Furthermore, IL-33 polarized M2 macrophages to produce IL-13 and TGF-β1 and induced the expansion of ILC2s to produce IL-13 in vitro and in vivo., Conclusions: IL-33 is a novel profibrogenic cytokine that signals through ST2 to promote the initiation and progression of pulmonary fibrosis by recruiting and directing inflammatory cell function and enhancing profibrogenic cytokine production in an ST2- and macrophage-dependent manner., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Toll-like receptors (TLRs) 2 and 4 recognize different endogenous and exogenous agonists and play a distinct role in infection and inflammation. However, their ultimate effect in a given infectious and inflammatory disease is less understood. We produced polyclonal anti-murine TLR2 and TLR4 antibodies and investigated their effect on cutaneous leishmaniasis and inflammatory arthritis. Administration of these antibodies to susceptible BALB/c mice, infected in the footpad with Leishmania major, reduced footpad swelling but not the parasite load compared with mice treated with control IgG. The antibodies synergistically reduced leishmanial-specific T-cell proliferation, T helper type 1 and type 2 cytokine production, specific IgG1 and IgG2a antibody synthesis, and T-cell receptor and co-stimulatory molecule expression on dendritic cells in infected mice. We then tested the effect of these antibodies on collagen-induced arthritis (CIA) in DBA/1 mice, a classic model of chronic inflammation. Both antibodies markedly suppressed the development of clinical parameters with concomitant reduction of pro-inflammatory cytokine production. These data therefore suggest that anti-TLR2 and 4 antibodies may have a synergistic therapeutic effect on inflammatory disease in vivo., (© 2014 John Wiley & Sons Ltd.)

Background: Asthma is thought to result from the generation of T helper type 2 (Th2) responses, leading to bronchial inflammation. IFN-λ1 (also known as IL-29) is a recently described member of the IFN-λ family and has been shown to decrease production of Th2 cytokines in vitro. However, the role and mechanism of IFN-λ1 in asthma remain unknown., Objectives: The aim of this study was to clarify the importance of IFN-λ1 in allergen-induced airway hyperresponsiveness (AHR) and inflammation., Methods: We used a murine model for ovalbumin (OVA)-induced asthma to examine the effect of intranasal delivery of recombinant adenovirus expressing human IFN-λ1 (Ad-hIFN-λ1) on AHR and allergic airway inflammation., Results: Intranasal instillation of Ad-hIFN-λ1 before airway antigen challenge in OVA-immunized mice significantly decreased the severity of AHR and numbers of eosinophils and levels of IL-4, IL-5, and IL-13, but not IL-10 and IFN-γ; both in vivo, in the bronchoalveolar lavage fluid and in vitro, following stimulation of lymphocytes from spleens with OVA, compared with administration of a control virus (Ad-mock). Furthermore, Ad-hIFN-λ1 treatment inhibited serum IgE secretion and increased numbers of splenic CD4(+)CD25(+)FOXP3(+) Treg cells. Histological studies showed that Ad-hIFN-λ1 attenuated OVA-induced lung tissue eosinophilia., Conclusions: These results demonstrate that delivery of the Ad-hIFN-λ1 can mitigate allergic airway inflammation in experimental asthma. The potent immunoregulatory action of IFN-λ1 may offer a novel therapeutic approach to treat allergic asthma., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Cigarette smoke (CS) is the principal cause of pulmonary inflammatory response. IL-28 (IFN-λ) is a novel group of class II cytokines targeting the epithelial cells and IL-28 responses prominent in lungs can exert important immunomodulatory effects. We tested the hypothesis that IL-28B may modulate the lung inflammation induced by CS. Groups of mice were exposed to CS two times per day for 11 consecutive days. CS exposure induced lymphocyte, neutrophil and macrophage infiltration and inflammatory cytokine (IL-1β, tumor necrosis factor-α (TNF)-α, IL-17, and IL-4) in the airways. More importantly, all these CS-induced pathogenic changes were significantly inhibited by hydrodynamic delivery of plasmid DNA encoding mouse IL-28B. Thus, our results suggest that IL-28 cytokines are beneficial for the suppression of CS-mediated airway inflammation and may be a therapeutic target in CS-related diseases., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Regulatory B cells (Breg) have attracted increasing attention for their roles in maintaining peripheral tolerance. Interleukin 33 (IL-33) is a recently identified IL-1 family member, which leads a double-life with both pro- and anti-inflammatory properties. We report here that peritoneal injection of IL-33 exacerbated inflammatory bowel disease in IL-10-deficient (IL-10(-/-)) mice, whereas IL-33-treated IL-10-sufficient (wild type) mice were protected from the disease induction. A phenotypically unconventional subset(s) (CD19(+)CD25(+)CD1d(hi)IgM(hi)CD5(-)CD23(-)Tim-1(-)) of IL-10 producing Breg-like cells (Breg(IL-33)) was identified responsible for the protection. We demonstrated further that Breg(IL-33) isolated from these mice could suppress immune effector cell expansion and functions and, upon adoptive transfer, effectively blocked the development of spontaneous colitis in IL-10(-/-) mice. Our findings indicate an essential protective role, hence therapeutic potential, of Breg(IL-33) against mucosal inflammatory disorders in the gut., (Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.)

Disruption of peripheral blood B-cell homeostasis and variation of surface receptors occur with certain infections and autoimmune diseases. However, the impact of antiviral therapy on B-cell alteration during chronic hepatitis B (CHB) infection remains unclear. Our study aims to document the effects of B-cell alteration in CHB patients treated with tenofovir or adefovir. A total of 21 CHB patients and 10 healthy donors were recruited into the study. We identified B-cell subsets by flow cytometry and observed changes in the B-cell repertoire of CHB patients upon tenofovir or adefovir antiviral treatment. The total and percent of B cells and CD5 + B-cell subsets were significantly increased in CHB patients compared to healthy donors. Total and percent of CD5 + B cells gradually decreased following the diminution of the HBV DNA load after tenofovir and adefovir treatment. Upon tenofovir treatment, the percent of memory CD27 + B cells was increased but the absolute number declined, whereas naïve CD27- B cells declined in both percent and absolute number. In the adefovir treatment group, neither naïve nor memory B cells were altered by the treatment. Furthermore, CHB patients displayed higher levels of activation markers (CD69 and CD24) and trended towards restored B-cell homeostasis after antiviral treatment. In conclusion, disrupted B-cell homeostasis is an important feature of CHB patients and is partially restored after control of viral replication by antiviral treatment. B-cell antiviral immunity is improved by restoring B-cell homeostasis and activation.

Interleukin-33 (IL-33) and its receptor ST2 are over-expressed in clinical colitis tissue. However, the significance of these observations is at present unknown. Significantly, we demonstrate here that IL33 and ST2 are the primary early genes induced in the inflamed colon of BALB/c mice following dextran sulphate sodium (DSS)-induced experimental ulcerative colitis. Accordingly diarrhoea and DSS-induced colon inflammation were impaired in ST2(-/-) BALB/c mice and exacerbated in wild-type mice by treatment with exogenous recombinant IL-33, associated respectively with reduced and enhanced expression of chemokines (CXCL9 and CXCL10), and inflammatory (IL-4, IL-13, IL-1, IL-6, IL-17) and angiogenic (vascular endothelial growth factor) cytokines in vivo. The exacerbation effect of treatment with recombinant IL-33 on DSS-induced acute colitis was abolished in IL-4(-/-) BALB/c mice. Hence, IL-33 signalling via ST2, by inducing an IL-4-dependent immune response, may be a major pathogenic factor in the exacerbation of ulcerative colitis., (© 2013 John Wiley & Sons Ltd.)

Interleukin (IL)-33 is a recently identified pleiotropic cytokine, which can orchestrate complex innate and adaptive immune responses in immunity and disease. It has been characterized as a cytokine of the IL-1 family and affects a wide range of immune cells by signalling through its receptor ST2L. Accumulating evidence suggests a crucial role of IL-33/ST2 in inducing and modifying host immune responses against a variety of pathogens including parasites, bacteria, viruses and fungi as well as sterile insults of both endogenous and exogenous source. In this review, we endeavour to give a comprehensive overview of the current knowledge about the role of IL-33 and its receptor ST2 in host defence against infections.

The mechanism by which cigarette smoke (CS) causes chronic obstructive pulmonary disease (COPD) is poorly understood. Interleukin-33 (IL-33) is a pleiotropic cytokine predominantly expressed in lung tissue and can elicit airway inflammation in naive mice. We tested the hypothesis that IL-33 is induced by CS and contributes to CS-mediated airway inflammation in a mouse model of CS-induced COPD. Groups of mice were exposed to CS three times per day for 4 consecutive days. The expression levels of IL-33 and ST2 were markedly enhanced in the lung tissue of mice inhaling CS. Exposure to CS also induced neutrophil and macrophage infiltration and expression of inflammatory cytokines (IL-1β, tumour necrosis factor-α, IL-17), chemokines (monocyte chemoattractant protein-1) and mucin 5, subtypes A and C in the airways. More importantly, all of these CS-induced pathogenic changes were significantly inhibited by treatment with neutralizing anti-IL-33 antibody delivered intranasally. Hence, our results suggest that IL-33 plays a critical role in CS-mediated airway inflammation and may be a therapeutic target in CS-related diseases, including COPD., (© 2012 Blackwell Publishing Ltd.)

Interleukin (IL)-33, a member of the IL-1 cytokine family, is an important modulator of the immune system associated with several immune-mediated disorders. High levels of IL-33 are expressed by the central nervous system (CNS) suggesting a potential role of IL-33 in autoimmune CNS diseases. We have investigated the expression and function of IL-33 in the development of experimental autoimmune encephalomyelitis (EAE) in mice. We report here that IL-33 and its receptor ST2 (IL-33Rα) are highly expressed in spinal cord tissue, and ST2 expression is markedly increased in the spinal cords of mice with EAE. Furthermore, ST2-deficient (ST2(-/-) ) mice developed exacerbated EAE compared with wild-type (WT) mice while WT, but not ST2(-/-) EAE mice treated with IL-33 developed significantly attenuated disease. IL-33-treated mice had reduced levels of IL-17 and IFN-γ but produced increased amounts of IL-5 and IL-13. Lymph node and splenic macrophages of IL-33-treated mice showed polarization toward an alternatively activated macrophage (M2) phenotype with significantly increased frequency of MR(+) PD-L2(+) cells. Importantly, adoptive transfer of these IL-33-treated macrophages attenuated EAE development. Our data therefore demonstrate that IL-33 plays a therapeutic role in autoimmune CNS disease by switching a predominantly pathogenic Th17/Th1 response to Th2 activity, and by polarization of anti-inflammatory M2 macrophages., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Alcohol intake is inversely related to rheumatoid arthritis (RA) disease incidence and severity. Resveratrol, a safe, well-described plant-derived compound, possesses anti-inflammation and immune-regulatory properties and is present in red wine. As such, it could mediate anti-inflammatory properties of the latter and offer novel therapeutic utility in is own right., Objective: To evaluate the therapeutic effect of resveratrol on collagen-induced arthritis (CIA) and its putative immune modulation in mice., Methods: CIA was induced in DBA1 mice by immunisation with collagen II. Different doses of resveratrol were administered before or after the development of CIA. The levels of antibody and cytokines in serum or in draining lymph node (DLN) lymphocyte culture supernatants were measured by ELISA and Th17 cell development in DLN was monitored by flow cytometry., Results: Either prophylactic or therapeutic administration of resveratrol attenuated clinical parameters and bone erosion in CIA mice. The arthritis-protective effects were associated with markedly reduced serum levels of pro-inflammatory cytokines and collagen-specific, but not total, IgG, and with reduced numbers of Th17 cells and the production of IL-17 in DLN., Conclusion: Resveratrol modulates inflammatory arthritis in rodents by selectively suppressing key cellular and humoral responses necessary for disease development. This may partly explain the protective effects of red wine but importantly may offer a novel, effective and safe pathway whereby novel agents could be developed to treat RA.

Natural killer (NK) cells play a critical role in innate antiviral immunity, but little is known about the impact of antiviral therapy on the frequency of NK cell subsets. To this aim, we performed this longitudinal study to examine the dynamic changes of the frequency of different subsets of NK cells in CHB patients after initiation of tenofovir or adefovir therapy. We found that NK cell numbers and subset distribution differ between CHB patients and normal subjects; furthermore, the association was found between ALT level and CD158b(+) NK cell in HBV patients. In tenofovir group, the frequency of NK cells increased during the treatment accompanied by downregulated expression of NKG2A and KIR2DL3. In adefovir group, NK cell numbers did not differ during the treatment, but also accompanied by downregulated expression of NKG2A and KIR2DL3. Our results demonstrate that treatment with tenofovir leads to viral load reduction, and correlated with NK cell frequencies in peripheral blood of chronic hepatitis B virus infection. In addition, treatments with both tenofovir and adefovir in chronic HBV infected patients induce a decrease of the frequency of inhibitory receptor(+) NK cells, which may account for the partial restoration of the function of NK cells in peripheral blood following treatment.

Background: The interleukin-28B gene (IL28B) locus has been associated with host resistance to hepatitis C virus (HCV) infection and response to PEG-IFN/RBV treatment in western populations. This study was to determine whether this gene variant is also associated with spontaneous clearance of HCV infection, treatment response and IL-28B protein production in Chinese patients., Methods: We genotyped IL28B genetic variations (rs12980275, rs8103142, rs8099917 and rs12979860) by pyrosequencing DNA samples from cohorts consisting of 529 subjects with persistent HCV infection, 196 subjects who cleared the infection, 171 healthy individuals and 235 chronic HCV patients underwent IFN/RBV treatment. The expression of IL-28B were measured by ELISA and RT-PCR., Results: We found that the four IL28B variants were in complete linkage disequilibrium (r2 = 0.97-0.98). The rs12979860 CC genotype was strongly associated with spontaneously HCV clearance and successful IFN/RBV treatment compared to the CT/TT. IL-28B levels in persistent HCV patients were significantly lower than subjects who spontaneously resolved HCV and healthy controls and were also associated with high levels of ALT (alanine aminotransferase) and AST (aspartate aminotransferase). IL-28B levels were also significantly lower in individuals carrying T alleles than CC homozygous., Conclusions: Thus, the rs12979860-CC variant upstream of IL28B gene is associated with spontaneous clearance of HCV, susceptible to IFN/RBV treatment and increased IL-28B levels in this Chinese population.

B1 B cells produce natural IgM and play a critical role in the early defense against bacterial and viral infection. The polyreactive IgM also contributes to the clearance of apoptotic products and plays an important role in autoimmune pathogenesis. However, the mechanism of activation and proliferation of B1 cells remains obscure. In this study, we report that IL-33, a new member of IL-1 family, activates B1 cells, which express the IL-33 receptor α, ST2. IL-33 markedly activated B1 cell proliferation and enhanced IgM, IL-5, and IL-13 production in vitro and in vivo in a ST2-dependent manner. The IL-33-activated B1 cell functions could be largely abolished by IL-5 neutralization and partially reduced by T cell or mast cell deficiency in vivo. ST2-deficient mice developed less severe oxazolone-induced contact sensitivity (CS) than did wild-type (WT) mice. Furthermore, IL-33 treatment significantly exacerbated CS in WT mice with enhanced B1 cell proliferation and IgM and IL-5 production. Moreover, IL-33-activated B1 cells from WT mice could adoptively transfer enhanced CS in ST2(-/-) mice challenged with IL-33. Thus, we demonstrate, to the best of our knowledge, a hitherto unrecognized mechanism of B1 cell activation and IL-33 function, and suggest that IL-33 may play an important role in delayed-type hypersensitivity.

Using TLR agonists in cancer treatment can have either beneficial or detrimental effects. Therefore, it is important to determine their effect on the tumor growth and understand the underlying mechanisms in animal tumor models. In this study, we report a general immunotherapeutic activity of a synthetic bacterial lipoprotein (BLP), a TLR1/TLR2 agonist, on established lung carcinoma, leukemia, and melanoma in mice. Systemic treatment of 3LL tumor-bearing mice with BLP, but not LPS, led to a dose-dependent tumor regression and a long-lasting protective response against tumor rechallenge. The BLP-mediated tumor remission was neither mediated by a direct tumoricidal activity nor by innate immune cells, because it lacked therapeutic effect in immunodeficient SCID mice. Instead, BLP treatment reduced the suppressive function of Foxp3(+) regulatory T cells (Tregs) and enhanced the cytotoxicity of tumor-specific CTL in vitro and in vivo. Furthermore, adoptive cotransfer of BLP-pretreated but not untreated CTL and Tregs from wild-type but not from TLR2(-/-) mice was sufficient to restore antitumor immunity in SCID mice by reciprocally modulating Treg and CTL function. These results demonstrate that the TLR1/TLR2 agonist BLP may have a general tumor therapeutic property involving reciprocal downregulation of Treg and upregulation of CTL function. This property may play an important role in the development of novel antitumor strategies.

Chronicity of hepatitis B (CHB) infection is characterized by a weak immune response to the virus. Entecavir (ETV) and adefovir dipivoxil (ADV) are effective in suppressing hepatitis B virus (HBV) replication. However, the underlying immune mechanism in the antiviral response of patients treated with nucleoside or nucleotide analogs is not clearly understood. In this study, regulatory T cells (Tregs) and intracellular cytokines, including IL-2, interferon (IFN)-γ, tumor-necrosis factor (TNF)-α and IL-4, were measured prior to and at 12, 24, 36 and 48 weeks after treatment with ETV or ADV. The cytokines were increased from 24 to 48 weeks after treatment. Higher levels of Th1 cytokines were observed with ETV (n=29) versus ADV (n=28) treatment. By contrast, the numbers of Tregs in both groups were decreased. The altered cytokine profile and cellular component was accompanied by a decrease in HBV DNA levels in both groups, which may contribute to their therapeutic effect in CHB infection. Our findings suggest that the antiviral effect of the drugs may be attributed not only to their direct effect on virus suppression but also to their immunoregulatory capabilities.

IL-33 has emerged as an important mediator in the immunopathogenesis of allergy and asthma. However, the role of IL-33 in eosinophil-mediated inflammation has not been fully explored. In this article, we report that IL-33 directly stimulates eosinophil differentiation from CD117(+) progenitors in an IL-5-dependent manner. Although resting eosinophils expressed moderate levels of the IL-33R alpha-chain (ST2L), eosinophils that accumulated in the airways of mice with OVA-induced asthma expressed increased amounts of ST2L. In vitro, IL-33 and GM-CSF are potent inducers of ST2L expression on eosinophils, and IL-33 induced the production of IL-13, CCL17, and TGF-beta by eosinophils. In adoptive-transfer experiments, IL-33 exacerbated eosinophil-mediated airway inflammation by increasing the levels of eosinophils, macrophages, lymphocytes, IL-13, TGF-beta, CCL3, CCL17, and CCL24 in the lungs. IL-33 also enhanced the eosinophil-mediated differentiation of airway macrophages toward the alternatively activated macrophage phenotype in an IL-13-dependent manner. Taken together, this study demonstrates that the IL-33/ST2 signaling pathway activates airway eosinophils that exacerbate airway inflammation in an autocrine and paracrine manner.

Rationale: Chronic low-grade inflammation involving adipose tissue likely contributes to the metabolic consequences of obesity. The cytokine interleukin (IL)-33 and its receptor ST2 are expressed in adipose tissue, but their role in adipose tissue inflammation during obesity is unclear., Objective: To examine the functional role of IL-33 in adipose tissues and investigate the effects on adipose tissue inflammation and obesity in vivo., Methods and Results: We demonstrate that treatment of adipose tissue cultures in vitro with IL-33 induced production of Th2 cytokines (IL-5, IL-13, IL-10) and reduced expression of adipogenic and metabolic genes. Administration of recombinant IL-33 to genetically obese diabetic (ob/ob) mice led to reduced adiposity, reduced fasting glucose and improved glucose and insulin tolerance. IL-33 also induced accumulation of Th2 cells in adipose tissue and polarization of adipose tissue macrophages toward an M2 alternatively activated phenotype (CD206(+)), a lineage associated with protection against obesity-related metabolic events. Furthermore, mice lacking endogenous ST2 fed high-fat diet had increased body weight and fat mass and impaired insulin secretion and glucose regulation compared to WT controls fed high-fat diet., Conclusions: In conclusion, IL-33 may play a protective role in the development of adipose tissue inflammation during obesity.

Objectives: Interleukin 33 (IL-33) is a new member of the IL-1 family of cytokines which signals via its receptor, ST2 (IL-33R), and has an important role in Th2 and mast cell responses. This study shows that IL-33 orchestrates neutrophil migration in arthritis., Methods and Results: Methylated bovine serum albumin (mBSA) challenge in the knee joint of mBSA-immunised mice induced local neutrophil migration accompanied by increased IL-33R and IL-33 mRNA expression. Cell migration was inhibited by systemic and local treatments with soluble (s)IL-33R, an IL-33 decoy receptor, and was not evident in IL-33R-deficient mice. IL-33 injection also induced IL-33R-dependent neutrophil migration. Antigen- and IL-33-induced neutrophil migration in the joint was dependent on CXCL1, CCL3, tumour necrosis factor alpha (TNFalpha) and IL-1beta synthesis. Synovial tissue, macrophages and activated neutrophils expressed IL-33R. IL-33 induces neutrophil migration by activating macrophages to produce chemokines and cytokines and by directly acting on neutrophils. Importantly, neutrophils from patients with rheumatoid arthritis successfully treated with anti-TNFalpha antibody (infliximab) expressed significantly lower levels of IL-33R than patients treated with methotrexate alone. Only neutrophils from patients treated with methotrexate alone or from normal donors stimulated with TNFalpha responded to IL-33 in chemotaxis., Conclusions: These results suggest that suppression of IL-33R expression in neutrophils, preventing IL-33-induced neutrophil migration, may be an important mechanism of anti-TNFalpha therapy of inflammation.

Sepsis is a systemic inflammatory condition following bacterial infection with a high mortality rate and limited therapeutic options. Here we show that interleukin-33 (IL-33) reduces mortality in mice with experimental sepsis from cecal ligation and puncture (CLP). IL-33-treated mice developed increased neutrophil influx into the peritoneal cavity and more efficient bacterial clearance than untreated mice. IL-33 reduced the systemic but not the local proinflammatory response, and it did not induce a T helper type 1 (T(H)1) to T(H)2 shift. The chemokine receptor CXCR2 is crucial for recruitment of neutrophils from the circulation to the site of infection. Activation of Toll-like receptors (TLRs) in neutrophils downregulates CXCR2 expression and impairs neutrophil migration. We show here that IL-33 prevents the downregulation of CXCR2 and inhibition of chemotaxis induced by the activation of TLR4 in mouse and human neutrophils. Furthermore, we show that IL-33 reverses the TLR4-induced reduction of CXCR2 expression in neutrophils via the inhibition of expression of G protein-coupled receptor kinase-2 (GRK2), a serine-threonine protein kinase that induces internalization of chemokine receptors. Finally, we find that individuals who did not recover from sepsis had significantly more soluble ST2 (sST2, the decoy receptor of IL-33) than those who did recover. Together, our results indicate a previously undescribed mechanism of action of IL-33 and suggest a therapeutic potential of IL-33 in sepsis.

Objective: IL-33 has recently been found to be the specific ligand of ST2, an IL-1 receptor family member that is selectively expressed in Th2 cells and mediates Th2 response. This study aims to measure the serum levels of soluble ST2 (sST2) and IL-33 in patients with SLE and to examine their association with disease activity., Methods: Seventy SLE patients were evaluated for disease activity, determined by SLEDAI, levels of anti-dsDNA antibody, C3 and C4. Fifty-seven patients were evaluated longitudinally on a second occasion. IL-33 and sST2 were measured by sandwich ELISA in the 127 SLE serum samples and compared with 28 age- and sex-matched healthy controls., Results: Serum sST2 level was significantly higher in active SLE patients [0.51 (0.18) ng/ml] compared with inactive patients [0.42 (0.08) ng/ml] (P = 0.006) and normal controls [0.36 (0.13) ng/ml] (P < 0.001). sST2 level correlated significantly with SLEDAI, anti-dsDNA antibody and prednisolone dosage, and negatively with C3. Linear regression analysis showed that serum sST2 level was an independent predictive factor for modified SLEDAI, excluding anti-dsDNA and complement score after controlling for age, sex, glomerular filtration rate and prednisolone dosage (regression coefficient: 8.5; 95% CI 2.6, 14.3) (P = 0.005). Serum sST2 level was sensitive to change in disease activity longitudinally, with an effect size of 0.29. Elevated serum IL-33 was comparable in frequency (4.3 vs 7.1%; P = 0.62) and levels (P = 0.53) between SLE patients and controls., Conclusions: Elevated serum sST2 level in SLE patients was found to correlate with disease activity and was sensitive to change, suggesting a potential role as a surrogate marker of disease activity.

Rheumatoid arthritis pathogenesis comprises dysregulation in both innate and adaptive immunity. There is therefore intense interest in the factors that integrate these immunologic pathways in rheumatoid arthritis. In this paper, we report that IL-33, a novel member of the IL-1 family, can exacerbate anti-glucose-6-phosphate isomerase autoantibody-induced arthritis (AIA). Mice lacking ST2 (ST2(-/-)), the IL-33 receptor alpha-chain, developed attenuated AIA and reduced expression of articular proinflammatory cytokines. Conversely, treatment of wild-type mice with rIL-33 significantly exacerbated AIA and markedly enhanced proinflammatory cytokine production. However, IL-33 failed to increase the severity of the disease in mast cell-deficient or ST2(-/-) mice. Furthermore, mast cells from wild-type, but not ST2(-/-), mice restored the ability of ST2(-/-) recipients to mount an IL-33-mediated exacerbation of AIA. IL-33 also enhanced autoantibody-mediated mast cell degranulation in vitro and in synovial tissue in vivo. Together these results demonstrate that IL-33 can enhance autoantibody-mediated articular inflammation via promoting mast cell degranulation and proinflammatory cytokine production. Because IL-33 is derived predominantly from synovial fibroblasts, this finding provides a novel mechanism whereby a host tissue-derived cytokine can regulate effector adaptive immune response via enhancing innate cellular activation in inflammatory arthritis.

Alternatively activated macrophages (AAM) play a crucial role in type 2 immunity. Mice deficient in ST2, a receptor for the latest member of the IL-1 family, IL-33, have impaired type 2 immune responses. We therefore reasoned that IL-33/ST2 signaling may be involved in the differentiation and activation of AAM during airway inflammation. We report here that IL-33 changed the quiescent phenotype of alveolar macrophages toward an AAM phenotype that expressed mannose receptor, IL-4Ralpha, and produced high levels of CCL24 and CCL17 in an IL-13-dependent manner during IL-33-induced airway inflammation. Neutralization of AAM-derived CCL24 led to an amelioration of IL-33-induced eosinophilia in the lungs. Moreover, depletion of alveolar macrophages reduced IL-33-induced airway inflammation. Additionally, the attenuated OVA-induced airway inflammation in ST2(-/-) mice was associated with a decrease in AAM differentiation. In vitro, IL-33 amplified IL-13-induced polarization of alveolar- and bone marrow-derived macrophage toward an AAM phenotype by increasing the expression of arginase I, Ym1, as well as the production of CCL24 and CCL17. IL-13/IL-4Ralpha signaling was crucial for IL-33-driven AAM amplification by inducing the expression of ST2L. Finally, we showed that IL-33 was more abundantly expressed in the lung epithelial cells of asthma patients than those from healthy controls, suggesting that IL-33 may be involved in lung macrophage activation in clinical asthma. Taken together, we demonstrate here that IL-33/ST2 plays a significant role in the amplification of AAM polarization and chemokine production which contribute to innate and Ag-induced airway inflammation.

Anaphylactic shock is characterized by elevated immunoglobulin-E (IgE) antibodies that signal via the high affinity Fc epsilon receptor (Fc epsilonRI) to release inflammatory mediators. Here we report that the novel cytokine interleukin-33 (IL-33) potently induces anaphylactic shock in mice and is associated with the symptom in humans. IL-33 is a new member of the IL-1 family and the ligand for the orphan receptor ST2. In humans, the levels of IL-33 are substantially elevated in the blood of atopic patients during anaphylactic shock, and in inflamed skin tissue of atopic dermatitis patients. In murine experimental atopic models, IL-33 induced antigen-independent passive cutaneous and systemic anaphylaxis, in a T cell-independent, mast cell-dependent manner. In vitro, IL-33 directly induced degranulation, strong eicosanoid and cytokine production in IgE-sensitized mast cells. The molecular mechanisms triggering these responses include the activation of phospholipase D1 and sphingosine kinase1 to mediate calcium mobilization, Nuclear factor-kappaB activation, cytokine and eicosanoid secretion, and degranulation. This report therefore reveals a hitherto unrecognized pathophysiological role of IL-33 and suggests that IL-33 may be a potential therapeutic target for anaphylaxis, a disease of considerable unmet medical need.