IL-21 administration into the nostril alleviates murine allergic rhinitis

The role of Interleukin-21 (IL-21) in allergic disorders: Biological insights and regulatory mechanisms

In recent decades, allergic diseases subsequent from an IgE-mediated response to specific allergens have become a progressively public chronic disease worldwide. They have shaped an important medical and socio-economic burden. A significant proportion of allergic disorders are branded via a form 2 immune response relating Th2 cells, type 2 natural lymphoid cells, mast cells and eosinophils. Interleukin-21 (IL-21) is a participant of the type-I cytokine family manufactured through numerous subsets of stimulated CD4+ T cells and uses controlling properties on a diversity of immune cells. Increasingly, experimental sign suggests a character for IL-21 in the pathogenesis of numerous allergic disorders. The purpose of this review is to discuss the biological properties of IL-21 and to summaries current developments in its role in the regulation of allergic disorders.

Effect of inactivated nature‐derived microbial composition on mouse immune system

Introduction

The hygiene hypothesis suggests that decrease in early life infections due to increased societal‐level hygiene standards subjects one to allergic and autoimmune diseases. In this report, we have studied the effect of sterilized forest soil and plant‐based material on mouse immune system and gut microbiome.

Methods

Inbred C57Bl/6 mice maintained in normal sterile environment were subjected to autoclaved forest soil‐derived powder in their bedding for 1 h a day for 3 weeks. Immune response was measured by immune cell flow cytometry, serum cytokine enzyme‐linked immunoassay (ELISA) and quantitative polymerase chain reaction (qPCR) analysis. Furthermore, the mouse gut microbiome was analyzed by sequencing.

Results

When compared to control mice, mice treated with soil‐derived powder had decreased level of pro‐inflammatory cytokines namely interleukin (IL)−17F and IL‐21 in the serum. Furthermore, splenocytes from mice treated with soil‐derived powder expressed less IL‐1b, IL‐5, IL‐6, IL‐13, and tumor necrosis factor (TNF) upon cell activation. Gut microbiome appeared to be stabilized by the treatment.

Conclusions

These results provide insights on the effect of biodiversity on murine immune system in sterile environment. Subjecting mice to soil‐based plant and microbe structures appears to elicit immune response that could be beneficial, for example, in type 2 inflammation‐related diseases, that is, allergic diseases.

A comprehensive gene expression profile of allergic rhinitis-derived nasal fibroblasts and the potential mechanism for its phenotype

BACKGROUND

Allergic rhinitis (AR) is a common immunoglobulin E-mediated immune response involved various cell types, while the role of nasal fibroblasts (NFs) in the pathogenesis of AR is less understood.

PURPOSE

The study aimed to uncover the gene expression profile of AR-derived NFs and the potential mechanism for the changed phenotype of AR-NFs.

RESEARCH DESIGN

The primary NFs were isolated from 3 AR patients (AR-NFs) and 3 controls (Ctrl-NFs), and the proliferation, migration and interleukins production abilities of NFs were detected respectively. RNA-sequence was used to identify differentially expressed genes (DEGs) in AR-NFs. Transcription factor (TF) regulatory network and bioinformatic analyses were both conducted to clarify the biological roles of DEGs including the TFs. The DEG with the highest validated |fold change (FC)| value, detected by qPCR, was selected for further confirmation.

RESULTS

AR-NFs showed a higher proliferation and migration abilities as well as released higher levels of IL-33 and IL-6, compared to Ctrl-NFs. A total of 729 DEGs were screened out in AR-NFs. TF regulatory network indicated that BARX homeobox 1 (BARX1) and forkhead box L1 were the major node TFs. Bioinformatic analyses showed that a large number of DEGs including several target genes of BARX1 were both enriched cytokine-related GO terms, and immune- or inflammation-related pathways. BARX1 had the highest |FC| value, and silencing BARX1 in AR-NFs resulted in the significant downregulation of proliferation and migration abilities, and the production of interleukins.

CONCLUSIONS

Our study for the first time provided the gene expression profile of AR-derived NFs, and BARX1 could be developed as a potent target to alleviate the pathogenesis of AR.

IL-21 Rescues the Defect of IL-10-Producing Regulatory B Cells and Improves Allergic Asthma in DOCK8 Deficient Mice

Mutations in human DOCK8 cause a combined immunodeficiency syndrome characterized by allergic diseases such as asthma and food allergy. However, the underlying mechanism is unclear. Regulatory B (Breg) cells that produce IL-10 exert potent immunosuppressive functions in patients with allergic and autoimmune disorders. DOCK8-deficient B cells show diminished responses to TLR9 signaling, suggesting a possible defect in IL-10-producing Breg cells in those with DOCK8 deficiency, which may contribute to allergies. Here, we isolated peripheral blood mononuclear cells from DOCK8-deficient patients and generated a Dock8 KO mouse model to study the effect of DOCK8 deficiency on Breg cells. DOCK8-deficient patients and Dock8 KO mice harbored quantitative and qualitative defects in IL-10-producing Breg cells; these defects were caused by abnormal Dock8^-/- CD4⁺ T cells. We found that recombinant murine (rm)IL-21 restored the function of Bregs both in vitro and in Dock8 KO mice, leading to reduced inflammatory cell infiltration of the lungs in a murine asthma model. Overall, the results provide new insight into the potential design of Breg-based or IL-21-based therapeutic strategies for allergic diseases, including asthma associated with DOCK8 deficiency.

Nuocytes from mesenteric lymph node promote allergic responses in a mouse model

INTRODUCTION

Nuocytes play an important role in Type 2 immunity. However, the contribution of ILC2s to allergic rhinitis remains to be clearly elucidated.

OBJECTIVE

To evaluate the role of nuocytes from mesenteric lymph node on allergic responses in mice.

METHODS

After intraperitoneal administration of interleukin IL-25 and IL-33 to wild-type and Il17br^-/-Il1rl1^-/- double-deficient mice, nuocytes were purified from the the nasal-associated lymphoid tissue and mesenteric lymph nodes. Then, we assessed productions of IL-5 and IL-13 in nuocytes' cultures. Finally, we adoptively transferred the mesenteric lymph node-derived nuocytes from wild-type and Il17br^-/-Il1rl1^-/- mice to the murine model of allergic rhinitis to evaluate their roles in nasal allergic responses.

RESULTS

We showed that nuocytes in the mesenteric lymph nodes of wild-type mice were upregulated after application of IL-25 and IL-33, and were induced to produce IL-5 and IL-13. Numbers of sneezing and nasal rubbing as well as eosinophils were all enhanced after the adoptive transfer of wild-type nuocytes. Concentrations of IL-5, IL-13, IL-25 and IL-33 in nasal lavage fluid of allergic mice were also increased. However, nuocytes fromIl17br^-/-Il1rl1^-/- mice did not increase sneezing and nasal rubbing and eosinophilia, and upregulate the above cytokines in the nasal lavage fluid.

CONCLUSION

The findings demonstrate that nuocytes from the mesenteric lymph nodes of wild-type mice promote allergic responses in a mouse model.

Knockdown of miR‑205‑5p alleviates the inflammatory response in allergic rhinitis by targeting B‑cell lymphoma 6

Allergic rhinitis (AR) is an IgE-mediated upper airway disease with a high worldwide prevalence. MicroRNA (miR)-205-5p upregulation has been observed in AR; however, its role is poorly understood. The aim of the present study was to investigate the effect of miR-205-5p on AR-associated inflammation. To establish an AR model, BALB/c mice were sensitized using an intraperitoneal injection of ovalbumin (OVA) on days 0, 7 and 14, followed by intranasal challenge with OVA on days 21–27. A lentiviral sponge for miR-205-5p was used to downregulate miR-205-5p in vivo via intranasal administration on days 20–26. Reverse transcription-quantitative PCR revealed that miR-205-5p was upregulated in AR mice. Notably, miR-205-5p knockdown reduced the frequency of nose-rubbing and sneezing, and attenuated pathological alterations in the nasal mucosa. The levels of total and OVA-specific IgE, cytokines IL-4, IL-5 and IL-13, and inflammatory cells, were decreased by miR-205-5p knockdown in AR mice. In addition, miR-205-5p knockdown inhibited nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation by reducing the expression levels of NLRP3, apoptosisassociated specklike protein containing a CARD, cleaved caspase-1 and IL-1β by western blot analysis. B-cell lymphoma 6 (BCL6) was confirmed as a target of miR-205-5p by luciferase reporter assay. In conclusion, the present findings suggested that miR-205-5p knockdown may attenuate the inflammatory response in AR by targeting BCL6, which may be a potential therapeutic target for AR.

CD8+ Tregs ameliorate inflammatory reactions in a murine model of allergic rhinitis

BACKGROUND

CD8⁺CD25⁺fork-head box transcription factor (Foxp3)⁺ regulatory T cells (CD8⁺ Tregs) play a role in immune tolerance. However, the role of these cells in allergic rhinitis (AR) has not been elucidated. The study aimed to evaluate influences of CD8⁺ Tregs on inflammatory conditions in a murine model of AR.

METHODS

A murine model of AR was established. CD8⁺ Tregs were isolated from mice nasal mucosa and cultured in vitro. We examined interleukin (IL)-10 and transforming growth factor (TGF)-β in cell cultures. Then, we administered CD8⁺ Tregs into mice nasal mucosal cultures, and examined eosinophil cation protein (ECP), IL-4, IL-5 and IL-13 in these cultures. Finally, we adoptively transferred CD8⁺ Tregs into mice models, and evaluated percentages of CD8⁺ Tregs, numbers of sneezing and nasal rubbing, and counts of eosinophils and contents of ECP, IL-4, IL-5, IL-13, IL-10 and TGF-β in nasal lavage fluid (NLF) in mice.

RESULTS

The percentage of CD8⁺ Tregs from AR mice was reduced. IL-10 and TGF-β were increased in cell cultures from AR mice. ECP, IL-4, IL-5 and IL-13 were decreased after the AR mice CD8⁺ Tregs administration in mucosal cultures. However, their contents were not changed after normal CD8⁺ Tregs treatment. Additionally, the adoptive transfer of AR CD8⁺ Tregs enhanced the percentage of CD8⁺ Tregs and levels of IL-10 and TGF-β in NLF, reduced numbers of sneezing and nasal rubbing, and counts of eosinophils and concentrations of ECP, IL-4, IL-5 and IL-13 in NLF. However, normal CD8⁺ Tregs could not change above parameters.

CONCLUSION

These findings show that CD8⁺ Tregs may inhibit inflammatory responses in the AR condition.

Therapeutic Effect of C-C Chemokine Receptor Type 1 (CCR1) Antagonist BX471 on Allergic Rhinitis

Objective and Design

Allergic rhinitis (AR) is an immunoglobulin E (IgE)-mediated inflammatory respiratory hypersensitivity characterized by elevated Th2 cytokines and infiltration of inflammatory cells to nasal tissues. BX471 is a small-molecule C-C chemokine receptor type 1 (CCR1) antagonist involved in suppression of inflammation via blocking of primary ligands. In this study, we examined the anti-inflammatory effect of BX471 on ovalbumin (OVA)-induced AR mice model.

Materials and Methods

Levels of OVA-specific IgE and Th1 cytokines were determined by enzyme-linked immunosorbent assay (ELISA). Nasal expression of proinflammatory mediators was assessed by real-time polymerase chain reaction (RT-qPCR). Nasal-cavity sections were stained with hematoxylin and eosin (HE) and periodic acid-Schiff (PAS) to study eosinophil infiltration and goblet cell metaplasia. Relative protein levels of Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-kB), Toll-like Receptor 4 (TLR4) and Toll-like-receptor 2 (TLR2) were assessed by Western Blot. Percentage of CD4⁺CD25⁺Foxp3⁺ T regulatory cells (Treg) was measured by flow cytometry.

Results

Mice treated with BX471 showed significantly relieved sneezing and nasal-rubbing behaviors. The expression of nasal proinflammatory factors was significantly downregulated by BX471, and protein levels of tumor necrosis factor alpha (TNF- α) and NF-kB were suppressed. Blockade of CCR1 ligands inhibited eosinophil recruitment in nasal cavity. In addition, Treg cells population were upregulated in BX471-treated mice.

Conclusion

BX471 exerts anti-inflammatory effects in a mouse model of AR by inhibiting CCR1-mediated TNF-α production, which subsequently suppresses NF-kB activation in inflammatory cells, leading to a decrease in Th2 cytokines, IL-1β, VCAM-1, GM-CSF, RANTES, and MIP-1α expression levels, thus inhibiting eosinophil recruitment to nasal mucosa. In addition, BX-471 exhibits anti-allergic effect by increasing Treg cell population. Overall, BX471 represents a promising therapeutic strategy against AR.

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Serum Ghrelin Levels in Saudi Obese Asthmatic School-Children-Correlation with Interleukin-4, Interleukin-5, and Interleukin-21

Ghrelin is a peptide hormone with direct or indirect effects on obesity and asthma. More data are required to understand the effect of ghrelin on the control and pathogenesis of these diseases. The aim of this study was to evaluate ghrelin levels in selected groups of children to identify the association between serum ghrelin, obesity, and the severity of asthma. The study included 401 school children selected from the Najran area and grouped into non-obese asthmatics, obese asthmatics, obese non-asthmatics and controls (non-obese non-asthmatics). Blood levels of ghrelin, interleukin (IL)-4, IL-5 and IL-21 were determined by ELISA. The mean ghrelin values were insignificantly increased in obese children compared with non-obese children. The highest blood ghrelin values were in the non-obese asthmatic group. Serum ghrelin, IL-4 and IL-21 levels were significantly increased in asthmatic children compared with non-asthmatic children (p < 0.05), and there were significant positive correlations between ghrelin and IL-4, IL-5, and IL-21 in asthmatic children. Furthermore, ghrelin, IL-4, and IL-21 levels were significantly higher in uncontrolled asthmatics compared with controlled-asthmatic children (p < 0.05). Asthma was the only significant risk factor for high ghrelin values. This study provides evidence supporting the anti-inflammatory role of ghrelin in the pathogenesis of asthma. Asthma might be considered as an important determinant of high ghrelin values in children.

T Follicular Helper Cell Subsets and the Associated Cytokine IL-21 in the Pathogenesis and Therapy of Asthma

For many decades, T helper 2 (T_H2) cells have been considered to predominantly regulate the pathogenic manifestations of allergic asthma, such as IgE-mediated sensitization, airway hyperresponsiveness, and eosinophil infiltration. However, recent discoveries have significantly shifted our understanding of asthma from a simple T_H2 cell-dependent disease to a heterogeneous disease regulated by multiple T cell subsets, including T follicular helper (T_FH) cells. T_FH cells, which are a specialized cell population that provides help to B cells, have attracted intensive attention in the past decade because of their crucial role in regulating antibody response in a broad range of diseases. In particular, T_FH cells are essential for IgE antibody class-switching. In this review, we summarize the recent progress regarding the role of T_FH cells and their signature cytokine interleukin (IL)-21 in asthma from mouse studies and clinical reports. We further discuss future therapeutic strategies to treat asthma by targeting T_FH cells and IL-21.

Intervention of Orai1 Influences the Response of Nuocytes From Allergic Rhinitis Mice to IL-33

OBJECTIVE

Nuocytes are essential in innate type-2 immunity and contribute to the exacerbation of allergic rhinitis (AR). This study aimed to evaluate the intervention of Orai1 on the response of nuocytes from AR mice to interleukin (IL)-33.

METHODS

We established a murine model of AR. Nuocytes were obtained from the mouse nasal-associated lymphoid tissue. Then, we assessed expressions of Orai1, Ca²⁺ mean fluorescence intensity (MFI) in nuocytes, and their cellular response to mouse recombinant (rm) IL-33. After that, we administered rmlentivirus vectors (lenti) that encoded small hairpin RNA (shRNA) against ORAI1 (lenti-ORAI1) into nuocytes cultures and again evaluated Orai1 and Ca²⁺ MFI in nuocytes and their response to rmIL-33. Finally, we adoptively transferred nuocytes alone or nuocytes transfected by lenti or lenti-ORAI1 to AR models to investigate their roles during allergic inflammation.

RESULTS

We showed that Orai1 and Ca²⁺ MFI were upregulated in AR mice nuocytes. These cells were induced to produce more IL-5 and IL-13 by rmIL-33. However, the intervention of Orai1 by lenti-ORAI1 in nuocytes decreased Orai1 and Ca²⁺ MFI and reduced productions of aforementioned cytokines even after the administration of rmIL-33. Numbers of sneezing, nasal rubbing, and counts of eosinophils were all enhanced after the adoptive transfer of nuocytes. Concentrations of IL-5, IL-13, and IL-33 in the nasal lavage fluid (NLF) of allergic mice were also increased. However, the adoptive transfer of nuocytes transfected by lenti-ORAI1 decreased aforementioned parameters.

CONCLUSION

These findings show that the intervention of Orai1 in nuocytes influences the response of nuocytes to rmIL-33.

CD4+ T cells induce productions of IL-5 and IL-13 through MHCII on ILC2s in a murine model of allergic rhinitis

OBJECTIVE

CD4⁺ T cells play an important role not only in the induction of allergy but also in allergic inflammation. Group 2 innate lymphoid cells (ILC2s) also mediate type 2 immune responses in allergic rhinitis (AR). However, the relationships between CD4⁺ T cells and ILC2s in allergic condition are currently not well defined. The study aimed to evaluate the potential influences of CD4⁺ T cells on ILC2s in the murine model of AR.

METHODS

A murine model of AR was established using ovalbumin (OVA), and OVA-induced ILC2s were sorted and purified from the mouse nasal-associated lymphoid tissue (NALT), and cultured in vitro. Then, the expression of major histocompatibility complex class II (MHCII) on ILC2s was examined. CD4⁺ T cells were separated from AR mice peripheral blood mononuclear cells (PBMCs). After that, productions of IL-5 and IL-13 on ILC2s cultures were assessed when CD4⁺ T cells or plus anti-MHCII antibody or anti-CD4 antibody were administered into the cultures. Finally, we adoptively transferred ILC2s alone or ILC2s plus anti-MHCII antibody to the murine model of AR to investigate their roles in the nasal allergic inflammation.

RESULTS

We showed that ILC2s could be induced by OVA in the mouse NALT. The number and percentage of ILC2s in AR mice were increased. MHCII was expressed on ILC2s, and its protein and mRNA were all enhanced in allergic condition. IL-5 and IL-13 proteins and mRNAs were elevated after CD4⁺ T cells administration, and were reduced after these cells plus anti-MHCII antibody or anti-CD4 antibody application. Numbers of sneezing and nasal rubbing as well as counts of eosinophils in nasal lavage fluid (NLF) were all enhanced after the adoptive transfer of ILC2s when compared to AR mice. IL-5 and IL-13 in the NLF of allergic mice were also increased in comparison with AR group. However, above parameters were all decreased after the transfer of ILC2s plus anti-MHCII antibody versus AR mice or ILC2s-treated ones.

CONCLUSION

These findings show that CD4⁺ T cells induce productions of IL-5 and IL-13 through MHCII on ILC2s in AR mice models.

Synergy of Interleukin (IL)-5 and IL-18 in eosinophil mediated pathogenesis of allergic diseases

Eosinophils are circulating granulocytes that have pleiotropic effects in response to inflammatory signals in the body. In response to allergens or pathogens, exposure eosinophils are recruited in various organs that execute pathological immune responses. IL-5 plays a key role in the differentiation, development, and survival of eosinophils. Eosinophils are involved in a variety of allergic diseases including asthma, dermatitis and various gastrointestinal disorders (EGID). IL-5 signal transduction involves JAK-STAT-p38MAPK-NFκB activation and executes extracellular matrix remodeling, EMT transition and immune responses in allergic diseases. IL-18 is a classical cytokine also involved in immune responses and has a critical role in inflammasome pathway. We recently identified the IL-18 role in the generation, transformation, and maturation of (CD101+CD274+) pathogenic eosinophils. In, addition, several other cytokines like IL-2, IL-4, IL-13, IL-21, and IL-33 also contribute in advancing eosinophils associated immune responses in innate and adaptive immunity. This review discusses with a major focus (1) Eosinophils and its constituents, (2) Role of IL-5 and IL-18 in eosinophils development, transformation, maturation, signal transduction of IL-5 and IL-18, (3) The role of eosinophils in allergic disorders and (4) The role of several other associated cytokines in promoting eosinophils mediated allergic diseases.

Enhanced Anti-Allergic Activity of Milk Casein Phosphopeptide by Additional Phosphorylation in Ovalbumin-Sensitized Mice

The proteolytic digest of milk casein, known as casein phosphopeptide (CPP-III), exhibits diverse biological activities, including calcium absorption and antioxidant activities. We hypothesized that the additional phosphorylation of this peptide can enhance its immunomodulatory activity such as suppression of allergy-associated cytokine and antigen-specific immune response. This study was conducted to assess whether oral intake of additionally phosphorylated CPP-III (P-CPP) attenuates ovalbumin (OVA)-induced IgE-mediated allergic reactions because of the additional phosphate groups. Female BALB/c mice were intraperitoneally sensitized with OVA twice at intervals of 14 days and then orally fed native CPP-III (N-CPP), P-CPP, and dephosphorylated CPP-III (D-CPP) for 6 weeks. Next, the mice were orally challenged with 50 mg of OVA. Oral administration of P-CPP suppressed total and specific IgE levels in the serum. Mice fed P-CPP exhibited low levels of OVA-specific IgG1 and increased OVA-specific IgG2a. P-CPP also suppressed IL-4 production, while D-CPP showed similar a level compared to that of the control. Further, P-CPP increased the population of the T follicular helper (Tfh) cell in the spleen. These results suggest that additional phosphorylation of CPP can enhance the attenuation of allergen-specific IgE-modulated allergic reactions in a murine food allergy model.

IL-21 alleviates allergic asthma in DOCK8-knockout mice

Patients with DOCK8 deficiency are at increased susceptibility to develop allergic diseases such as food allergy and asthma. Here, we aimed to analyze the pathogenesis of asthma in DOCK8-deficient patients. In our mouse model, DOCK8-knockout (KO) mice sensitized with low-dose OVA were challenged with 1.5% OVA to induce allergic asthma. As compared to that in WT mice, remarkable airway hyperresponsiveness was observed in KO mice. Increased inflammatory cells and eosinophils infiltrated in airway lumen in KO mice especially around bronchi. KO mice showed higher levels of serum IgE and OVA-specific IgE and significantly elevated IgE-producing B cells in blood and in spleen. Surprisingly, nasal administration with rmIL-21 significantly reduced the airway hyperresponsiveness, inflammatory infiltration, as well as the serum IgE and IgE-producing B cells. DOCK8-knockout mice are susceptible to low-dose OVA induced allergic airway inflammation and airway hyperresponsiveness. Supplementary nasal administration of rmIL-21 alleviates allergic asthma in this mouse model.

Immunoglobulin G; structure and functional implications of different subclass modifications in initiation and resolution of allergy

IgE and not IgG is usually associated with allergy. IgE lodged on mast cells in skin or gut and basophils in the blood allows for the prolonged duration of allergy through the persistent expression of high affinity IgE receptors. However, many allergic reactions are not dependent on IgE and are generated in the absence of allergen specific and even total IgE. Instead, IgG plasma cells are involved in induction of, and for much of the pathogenesis of, allergic diseases. The pattern of IgG producing plasma cells in atopic children and the tendency for direct or further class switching to IgE are the principle factors responsible for long-lasting sensitization of mast cells in allergic children. Indirect class switching from IgG producing plasma cells has been shown to be the predominant pathway for production of IgE while a Th2 microenvironment, genetic predisposition, and the concentration and nature of allergens together act on IgG plasma cells in the atopic tendency to undergo further immunoglobulin gene recombination. The seminal involvement of IgG in allergy is further indicated by the principal role of IgG4 in the natural resolution of allergy and as the favourable immunological response to immunotherapy. This paper will look at allergy through the role of different antibodies than IgE and give current knowledge of the nature and role of IgG antibodies in the start, maintenance and resolution of allergy.

Pathogenic mechanisms of IgE-mediated inflammation in self-destructive autoimmune responses

Autoantibodies of the IgG subclass are pathogenic in a number of autoimmune disorders such as systemic lupus erythomatosus. The presence of circulating IgE autoantibodies in autoimmune patients has also been known for almost 40 years. Despite their role in allergies, IgE autoantibodies are not associated with a higher rate of atopy in these patients. However, recently they have been recognized as active drivers of autoimmunity through mechanisms involving the secretion of Type I interferons by plasmacytoid dendritic cells (pDC), the recruitment of basophils to lymph nodes, and the activation of adaptive immune responses through B and T cells. Here, we will review the formation, prevalence, affinity, and roles of the IgE autoantibodies that have been described in autoimmunity. We also present novel evidence supporting that triggering of IgE receptors in pDC induces LC3-associated phagocytosis, a cellular process also known as LAP that is associated with interferon responses. The activation of pDC with immune complexes formed by DNA-specific IgE antibodies also induce potent B-cell differentiation and plasma cell formation, which further define IgE's role in autoimmune humoral responses.

Chronic Rhinosinusitis with Polyps Is Characterized by Increased Mucosal and Blood Th17 Effector Cytokine Producing Cells

Background: Recent studies have implied a role for Th17 cells in CRS with nasal polyps (CRSwNP) patients. However, the capacity of these cells to produce Th17 cytokines is still unknown. Here we sought to quantify IL-17A, IL-17F, IL-21, and IL-22 cytokines produced by Th17 cells in mucosal tissue and peripheral blood of CRSwNP, CRS without nasal polyps (CRSsNP) and control patients.

Methods: Samples were prospectively collected from CRS patients and non-CRS controls. We used flow cytometry to characterize the Th17 cells and their cytokines in sinonasal tissue and peripheral blood.

Results: A total of 36 patients were recruited to the study. CRSwNP patients had significantly more tissue IL-17A (9.53 ± 2.71 vs. 1.11 ± 0.43 vs. 0.77 ± 0.07), IL-17F (4.96 ± 1.48 vs. 0.88 ± 0.31 vs. 0.56 ± 0.04), IL-21 (5.55 ± 2.01 vs. 1.60 ± 0.71 vs. 1.53 ± 0.55) and IL-22 (4.73 ± 1.58 vs. 0.70 ± 0.28 vs. 0.88 ± 0.26) producing Th17 cells compared to CRSsNP and control mucosa per mg of tissue, respectively. Allergic CRSwNP patients had decreased numbers of IL-21 producing Th17 cells compared to non-Allergic CRSwNP. (1.69 ± 0.57 vs. 9.41 ± 3.23) per mg of tissue, respectively (Kruskal-Wallis p < 0.05).

Conclusion: In summary our study identified increased numbers of IL-17A, IL-17F, IL-21 and IL-22 positive Th17 cells in CRSwNP patient polyps and peripheral blood suggesting an altered activation state of those cells both locally and systemically. Atopic CRSwNP had decreased amounts of tissue Th17 cell derived IL-21 implying a potential protective role for IL-21 in CRSwNP allergic inflammation.

Serum IL-21 levels are elevated in atopic dermatitis patients with acute skin lesions

BACKGROUND

Interleukin (IL)-21 is a member of the type I cytokine family and plays a role in the pathogenesis of T helper type 2 allergic diseases. It has been reported that IL-21 expression is upregulated in acute skin lesions in atopic dermatitis (AD) patients; however, little is known about the serum IL-21 levels of AD patients. The aim of this study was to quantify the serum IL-21 levels of AD patients and to evaluate the relationships between the serum IL-21 level and disease severity, laboratory markers, and eruption type in AD patients.

METHODS

We measured the serum IL-21 levels of adult AD patients and healthy control subjects using an enzyme-linked immunosorbent assay.

RESULTS

The adult AD patients exhibited significantly higher serum IL-21 levels than the healthy control subjects. A comparison of the patients' serum IL-21 levels based on the clinical severity of their AD revealed that the patients with severe AD demonstrated significantly higher serum IL-21 levels than those with mild AD and the healthy control subjects. The serum IL-21 levels were significantly correlated with the skin severity score, and especially with the degree of acute lesions such as erythema and edema/papules. The serum IL-21 level was not associated with laboratory markers, such as the serum IgE level, the serum thymus and activation-related chemokine level, blood eosinophilia, and the serum lactate dehydrogenase level.

CONCLUSIONS

These results suggest that IL-21 might be involved in the pathogenesis of AD, especially the development of acute skin lesions.

Protective effects of astragaloside IV against ovalbumin-induced allergic rhinitis are mediated by T-box protein expressed in T cells/GATA-3 and forkhead box protein 3/retinoic acid-related orphan nuclear receptor γt

3-O-β-D-xylopyranosyl-6-O-β-D-glucopyranosyl-cycloastragenol, or Astragaloside IV (AST), is one of the major active ingredients isolated from Astragalus membranaceous with distinct pharmacological effects, and possesses anti-inflammatory, immunoregulatory and antifibrotic properties. However, the effects of AST on allergic rhinitis remain to be elucidated. The present study aimed to examine the effects of AST on immunoglobulin (Ig) E‑mediated allergic reactions in vivo, by using a mouse model of allergic rhinitis established via repetitive sensitization and intranasal challenge with ovalbumin (OVA). Intragastric administration of AST (25 mg/kg or 50 mg/kg) or dexamethasone (DEX; 3 mg/kg) significantly alleviated the inflammatory response, nasal symptoms and mucosa remodeling, and decreased the serum levels of OVA‑specific IgE in allergic mice. Furthermore, treatment with AST or DEX significantly suppressed the mRNA and protein expression levels of the transcription factor GATA‑3 and retinoic acid receptor‑related orphan nuclear receptor (ROR)γt in tissue samples isolated from the spleen and nasal mucosa of mice with allergic rhinitis. Conversely, mRNA and protein expression levels of T‑box protein expressed in T cells (T‑bet) and forkhead box protein 3 (Foxp3) were upregulated in the spleen and nasal mucosa of mice with allergic rhinitis following treatment with AST or DEX, and spleen protein levels of signal transducer and activator of transcription 3 followed a similar trend. In addition, treatment with AST was associated with fewer adverse events compared with treatment with DEX. The present results suggested that treatment with AST may attenuate OVA‑induced allergic rhinitis via regulating the expression of the transcription factors GATA‑3, RORγt, T‑bet and Foxp3, which commit T helper cells to the Th1 phenotype. Therefore, AST may represent an alternative therapeutic approach for the treatment of patients with allergic rhinitis.

T follicular helper (Tfh ) cells in normal immune responses and in allergic disorders

Follicular helper T cells (Tfh ) are located within germinal centers of lymph nodes. Cognate interaction between Tfh , B cells, and IL-21 drives B cells to proliferate and differentiate into plasma cells thereby leading to antibody production. Tfh cells and IL-21 are involved in infectious and autoimmune diseases, immunodeficiencies, vaccination, and cancer. Human peripheral blood CXCR5(+) CD4(+) T cells comprise different subsets of Tfh -like cells. Despite the importance of the IgE response in the pathogenesis of allergic disorders, little is known about the role of follicular and blood Tfh cells and IL-21 in human and experimental allergic disease. Here, we review recent advances regarding the phenotypic and functional characteristics of both follicular and blood Tfh cells and of the IL-21/IL-21R system in the context of allergic disorders.

Therapeutic Effect of Histone Deacetylase Inhibitor, Sodium Butyrate, on Allergic Rhinitis In Vivo

Despite the well-documented therapeutic effects of histone deacetylase inhibitor (HDACi) on various diseases, including arthritis and asthma, the therapeutic effect of HDACi on allergic rhinitis remains unmentioned in the literature. This study investigated the therapeutic effect of sodium butyrate (SoB), a form of HDACi, on mice with allergic rhinitis. The results showed that the expression levels of histone deacetylase 1 (HDAC1), histone deacetylase 3 (HDAC3), and thymic stromal lymphopoietin (TSLP) were significantly upregulated in mice with allergic rhinitis, whereas H3 acetylation at lysine 9 (H3AcK9) was decreased. The intranasal application of SoB inhibited the expression levels of TSLP levels and upregulated the expression of H3AcK9 in a mouse model of allergic rhinitis. Furthermore, SoB treatment significantly decreased the increased levels of ovalbumin-specific IgE and improved clinical symptoms and nasal mucosa epithelial morphology in the mouse model of allergic rhinitis. In addition, we further demonstrated that SoB treatment significantly increased the serum levels of IL-2 and IFN-γ and decreased the serum levels of IL-4 and IL-10, correcting the Th1/Th2 imbalance in the mouse model of allergic rhinitis. Taken together, our study suggests that SoB has the potential to treat allergic rhinitis.

Human IL-21+IFN-γ+CD4+ T cells in nasal polyps are regulated by IL-12

In the previous study, we found that the levels of IL-21 in nasal polyps (NPs) were significantly increased and associated with polyp size and recurrence. However, it is unclear that the cell source of IL-21 and the regulation of IL-21 in NP tissues. In the present study, we isolated the lymphocytes from NP tissues, uncinate tissues and peripheral blood of patients with NPs. The cells were analyzed for cell surface markers, cytokines and transcriptional factors by flow cytometry. The results indicated that CD4⁺ T cells were the major IL-21-exprssing cells in NP tissues and the majority of IL-21 producing CD4⁺ T cells co-expressed IFN-γ or IL-17A. IL-21⁺IFN-γ⁺CD4⁺ T cells in NP tissues exhibited the features of both Tfh and Th1 cells which co-expressed significantly higher amount of CXCR5, ICOS, PD-1, Bcl-6 and T-bet than did IL-21⁺IFN-γ⁻CD4⁺ T cells (p < 0.05). Treatment of the lymphocytes from NP tissues with IL-12 enhanced the production of IL-21 and IFN-γ, especially the frequency of IL-21⁺IFN⁻γ⁺CD4⁺ T cells (p < 0.05). The blockade of IL-12 inhibited the production of IL-21 and IFN-γ (p < 0.05). These findings indicated that IL-12 positively enhanced the generation of IL-21⁺IFN-γ⁺CD4⁺ T cells having the features of both Tfh and Th1 cells in NP tissues.

Interleukin-21 suppresses the differentiation and functions of T helper 2 cells

T helper type 2 (Th2) cells, which produce interleukin-4 (IL-4), IL-5 and IL-13, control immunity to all forms of allergic inflammatory responses. Interleukin-21 (IL-21) reduces allergic symptoms in murine models and inhibits IL-4-induced IgE secretion by B cells. However, whether or not IL-21 directly affects Th2 cells, which leads to reduced allergic symptoms, is unclear. In this study, we investigated the effects of IL-21 on the differentiation and effector functions of Th2 cells. We found that IL-21 reduced the number of differentiated Th2 cells and these Th2 cells showed a diminished Th2 cytokine production. Interleukin-21 suppressed Th2 cytokine production of already polarized Th2 cells by down-regulation of transcription factor GATA-3. It also induced apoptosis of Th2 cells with decreased anti-apoptotic factor Bcl-2. Intranasal administration of IL-21 at the beginning of ovalbumin (OVA) sensitization or before OVA challenge decreased Th2 cytokines in the bronchoalveolar lavage fluid of OVA/alum-immunized allergic mice. In addition, the inhibitory effects of IL-21 on Th2 effector functions can also be found in allergic patients. Our results demonstrate that IL-21 suppresses the development of Th2 cells and functions of polarized Th2 cells. Hence, the administration of IL-21 may be considered for use as a preventive and therapeutic approach when dealing with Th2-mediated allergic diseases.

Defective PTEN regulation contributes to B cell hyperresponsiveness in systemic lupus erythematosus

PTEN regulates normal signaling through the B cell receptor (BCR). In systemic lupus erythematosus (SLE), enhanced BCR signaling contributes to increased B cell activity, but the role of PTEN in human SLE has remained unclear. We performed fluorescence-activated cell sorting analysis in B cells from SLE patients and found that all SLE B cell subsets, except for memory B cells, showed decreased expression of PTEN compared with B cells from healthy controls. Moreover, the level of PTEN expression was inversely correlated with disease activity. We then explored the mechanisms governing PTEN regulation in SLE B cells. Notably, in normal but not SLE B cells, interleukin-21 (IL-21) induced PTEN expression and suppressed Akt phosphorylation induced by anti-immunoglobulin M and CD40L stimulation. However, this deficit was not primarily at the signaling or the transcriptional level, because IL-21-induced STAT3 (signal transducer and activator of transcription 3) phosphorylation was intact and IL-21 up-regulated PTEN mRNA in SLE B cells. Therefore, we examined the expression of candidate microRNAs (miRs) that could regulate PTEN: SLE B cells were found to express increased levels of miR-7, miR-21, and miR-22. These miRs down-regulated the expression of PTEN, and IL-21 stimulation increased the expression of miR-7 and miR-22 in both normal and SLE B cells. Indeed, a miR-7 antagomir corrected PTEN-related abnormalities in SLE B cells in a manner dependent on PTEN. Therefore, defective miR-7 regulation of PTEN contributes to B cell hyperresponsiveness in SLE and could be a new target of therapeutic intervention.

IL-21 receptor signalling partially mediates Th2-mediated allergic airway responses

BACKGROUND

Interleukin-21 (IL-21) has been implicated in the development of Th2-mediated immune responses; however, the exact role it plays in allergic diseases is not well understood.

OBJECTIVE

To elucidate the contribution of IL-21 receptor signalling to Th2-dependent immune responses in the lung.

METHODS

We compared allergic airway responses in wild-type BALB/c and Il21r-deficient mice exposed to local airway challenge with house dust mite (HDM).

RESULTS

We demonstrate that IL-21R-deficiency reduces HDM-driven airway hyperresponsiveness (AHR) with only partial effects on airway inflammation. Concomitant with the reduction in AHR in Il21r-deficient mice, significant suppression was observed in protein levels of the Th2 cytokines IL-4, and IL-13. In contrast, IL-21R-deficiency was associated with an increase in PBS- and allergen-driven IgE levels, while IgG1 and IgG2a levels were decreased. Moreover, our results suggest that IL-21 may contribute to AHR through its ability to both directly induce Th2 cell survival and to impair regulatory T-cell suppression of Th2 cytokine production. Importantly, we show that IL-21-positive cells are increased in the bronchial mucosa of asthmatics compared with non-asthmatics.

CONCLUSION

These results suggest that IL-21 plays an important role in the allergic diathesis by enhancing Th2 cytokine production through multiple mechanisms including the suppression of Treg inhibitory effects on Th2 cell cytokine production.

Activation of invariant natural killer T cells in regional lymph nodes as new antigen-specific immunotherapy via induction of interleukin-21 and interferon-γ

Invariant natural killer T (iNKT) cells play important immunoregulatory functions in allergen-induced airway hyperresponsiveness and inflammation. To clarify the role of iNKT cells in allergic rhinitis (AR), we generated bone marrow-derived dendritic cells (BMDCs), which were pulsed by ovalbumin (OVA) and α-galactosylceramide (OVA/α-GalCer-BMDCs) and administered into the oral submucosa of OVA-sensitized mice before nasal challenge. Nasal symptoms, level of OVA-specific immunoglobulin (IgE), and T helper type 2 (Th2) cytokine production in cervical lymph nodes (CLNs) were significantly ameliorated in wild-type (WT) mice treated with OVA/α-GalCer-BMDCs, but not in WT mice treated with OVA-BMDCs. These anti-allergic effects were not observed in Jα18(-/-) recipients that lack iNKT cells, even after similar treatment with OVA/α-GalCer-BMDCs in an adoptive transfer study with CD4(+) T cells and B cells from OVA-sensitized WT mice. In WT recipients of OVA/α-GalCer-BMDCs, the number of interleukin (IL)-21-producing iNKT cells increased significantly and the Th1/Th2 balance shifted towards the Th1 dominant state. Treatment with anti-IL-21 and anti-interferon (IFN)-γ antibodies abrogated these anti-allergic effects in mice treated with α-GalCer/OVA-BMDCs. These results suggest that activation of iNKT cells in regional lymph nodes induces anti-allergic effects through production of IL-21 or IFN-γ, and that these effects are enhanced by simultaneous stimulation with antigen. Thus, iNKT cells might be a useful target in development of new treatment strategies for AR.

T helper 17 cells and related cytokines after allergen inhalation challenge in allergic asthmatics

BACKGROUND

T helper (Th)17 cells may play a role in allergic asthma. This study assessed the effect of allergen inhalation challenge on circulating Th17 cells and related cytokines in allergic asthmatics.

METHODS

Peripheral blood mononuclear cells were collected from 16 atopic asthmatics before and 24 h after allergen challenge, as well as from 10 atopic nonasthmatics and 10 normal controls. Cells were stained for Th17 cytokines and their receptors (IL-17A, IL-17F, IL-21, IL-22, IL-17R, and IL-23R) using flow cytometry. Cytokine concentrations from cell culture supernatants were quantified using a multiplex assay for IL-17A, IL-17F, IL-21, IL-22, and IL-23.

RESULTS

At baseline, asthmatics had a higher percentage of circulating Th17 cells (1.2 ± 0.5%) compared to normal controls (0.9 ± 0.66%, p < 0.001) but not compared to atopic nonasthmatics (1.13 ± 0.5%). There was a significant increase in Th17 cells in asthmatics after allergen challenge to 1.55 ± 0.4% (p < 0.05) and a trend toward significance in IL-17R expression from 3.4 ± 4.3 to 6.86 ± 6.84% after allergen challenge (p = 0.06). There was also a significant reduction in IL-21-positive cells following allergen challenge from 3.46 ± 1.85 to 2.33 ± 1.37% (p < 0.001). There were no significant differences in IL-17F, IL-22 and IL-23R expression. The concentration of IL-17A in culture supernatant was significantly higher in asthmatics compared to normal controls and IL-17A significantly increased 24 h after allergen challenge.

CONCLUSIONS

The increase of Th17 cells and IL-17A in atopic asthma after allergen inhalation challenge suggests a possible role for Th17 in allergen-induced airway responses.

Role of Tyk-2 in Th9 and Th17 cells in allergic asthma

In a murine model of allergic asthma, we found that Tyk-2^(−/−) asthmatic mice have induced peribronchial collagen deposition, mucosal type mast cells in the lung, IRF4 and hyperproliferative lung Th2 CD4⁺ effector T cells over-expressing IL-3, IL-4, IL-5, IL-10 and IL-13. We also observed increased Th9 cells expressing IL-9 and IL-10 as well as T helper cells expressing IL-6, IL-10 and IL-21 with a defect in IL-17A and IL-17F production. This T helper phenotype was accompanied by increased SOCS3 in the lung of Tyk-2 deficient asthmatic mice. Finally, in vivo treatment with rIL-17A inhibited local CD4⁺CD25⁺Foxp3⁺ T regulatory cells as well as Th2 cytokines without affecting IL-9 in the lung. These results suggest a role of Tyk-2 in different subsets of T helper cells mediated by SOCS3 regulation that is relevant for the treatment of asthma, cancer and autoimmune diseases.

Upregulated interleukin-21 receptor on B cells associated with the downregulation of IgE in patients with allergic rhinitis

Allergic diseases, such as allergic rhinitis, caused by an immunoglobulin E (IgE)-mediated reaction to specific allergens are a common chronic condition worldwide. Interleukin-21 (IL-21), a type I cytokine that is produced by T cells, exerts regulatory effects on a variety of immune cells. In our previous study, we found that serum levels of IL-21 were significantly decreased in patients with severe atopic dermatitis, suggesting that IL-21 might play a role in allergic reactions. In this study, we investigated the role of IL-21/IL-21 receptor (IL-21R) in patients with allergic rhinitis. Our results demonstrated that there was no difference in IL-21 serum levels between allergic rhinitis patients and controls. However, allergic patients had significantly increased expression of IL-21R on naive and memory B cells. IL-21R was upregulated through stimulation by the combination of CD40 ligand (CD40L) and IL-4. IL-21 alone neither induced nor inhibited IgE secretion from CD40L-stimulated B cells. However, IL-21 inhibited IgE secretion of B cells that were induced by the combination of CD40L and IL-4 in allergic patients. Moreover, a negative correlation between the expression of IL-21R and serum levels of IgE was found in patients with allergy. These results suggest that the role of IL-21 in an ongoing allergic reaction is to downregulate the IgE level by binding to IL-21R on B cells, which increases the expression in allergic patients.

Interleukin-21: a double-edged sword with therapeutic potential

Interleukin-21 is a cytokine with broad pleiotropic actions that affect the differentiation and function of lymphoid and myeloid cells. Since its discovery in 2000, a tremendous amount has been learned about its biological actions and the molecular mechanisms controlling IL-21-mediated cellular responses. IL-21 regulates both innate and adaptive immune responses, and it not only has key roles in antitumour and antiviral responses but also exerts major effects on inflammatory responses that promote the development of autoimmune diseases and inflammatory disorders. Numerous studies have shown that enhancing or inhibiting the action of IL-21 has therapeutic effects in animal models of a wide range of diseases, and various clinical trials are underway. The current challenge is to understand how to specifically modulate the actions of IL-21 in the context of each specific immune response or pathological situation. In this Review, we provide an overview of the basic biology of IL-21 and discuss how this information has been - and can be - exploited therapeutically.

The emerging role of interleukin-21 in allergic diseases (Review)

Interleukin (IL)-21 is a newly discovered member of the type I cytokine family. Since its discovery in 2000, IL-21 has been the focus of extensive investigation, due to its homology to IL-2, IL-4 and IL-15 and its pleiotropic effects on innate and adaptive immune responses. An increasing amount of experimental evidence supports a role for IL-21 in the pathogenesis of several allergic diseases, such as allergic rhinitis, atopic dermatitis (AD) and atopic asthma. In this review, we aimed to discuss the biological characteristics of IL-21 and summarize the current progress on the role of IL-21 in the regulation of allergic inflammation.

Targeting interleukins to treat severe asthma

Severe asthma is thought to be a heterogeneous disease with different phenotypes predicated primarily on the nature of the inflammatory cell infiltrate and response to corticosteroid therapy. This group of patients often has refractory disease with an associated increase in morbidity and mortality, and there remains a need for better therapies for severe asthmatics. Inflammatory changes in asthma are driven by immune mechanisms, within which interleukins play an integral role. Interleukins are cell-signaling cytokines that are produced by a variety of cells, predominantly T cells. Knowledge about their actions has improved the understanding of the pathogenesis of asthma and provided potential targets for novel therapies. To date, this has not translated into clinical use. However, there are ongoing clinical trials that use monoclonal antibodies for various interleukins, some of which have shown to be promising in Phase II studies.

The role of the T follicular helper cells in allergic disease

T follicular helper (Tfh) cells were discovered just over a decade ago as germinal centre T cells that help B cells make antibodies. Included in this role is affinity maturation and isotype switching. It is here that their functions become less clear. Tfh cells principally produce IL-21 which inhibits class switching to IgE. Recent studies have questioned whether the germinal centre is the main site of IgE class switching or IgE affinity maturation. In this review, I will examine the evidence that these cells are responsible for regulating IgE class switching and the relationship between Tfh cells and T helper 2 (Th2) effector cells.

Decrease in interleukin-21 in children suffering with severe atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a kind of eczema with an inflammatory, relapsing, non-contagious, and pruritic skin disorder. It is associated with the local infiltration of T helper type 2 (Th2) cells that secrete interleukin (IL)-4 and IL-5. IL-21 is a member of IL-2 family cytokine mainly expressed by activated CD4+ T lymphocytes. Until now, there is no clinical research in the expression of IL-21 in patients with AD.

METHODS

We analyzed serum levels of total immunoglobulin E (IgE), allergen-specific IgE, and cytokines IL-4, IL-5, IFN-γ, IL-17, and IL-21 in AD cases and controls. In addition, cytokine levels in the culture supernatants of peripheral blood mononuclear cells stimulated with anti-CD3 and anti-CD28 Abs, phytohemagglutin (PHA), or pokeweed mitogen (PWM) were measured. We also assessed clinical skin severity by Scoring of Atopic Dermatitis (SCORAD) index.

RESULTS

Our results showed that serum total IgE in the case group was significantly higher than that of control group (365.449 ± 52.945 and 39.243 ± 7.605 IU/ml, respectively). Logistic regression analysis system reveals serum levels of IL-21 and IFN-γ are significantly correlated. However, IL-21 and IL-4, IL-21 and IL-5, as well as IL-21 and IL-17 showed no correlation.

CONCLUSION

A significantly decreased level of IL-21 was observed in children suffering with severe AD compared with controls, suggesting that IL-21 may play a role in AD.

Alleviation of murine allergic rhinitis by C19, a C-terminal peptide of chemokine-like factor 1 (CKLF1)

Human chemokine-like factor (CKLF1) is a human cytokine that exhibits chemotactic activities on a wide spectrum of leukocytes. One of CKLF1's C-terminal peptides, C19, exerts inhibitory effects on chemotaxis mediated by mouse Ccr3 and Ccr4 and human CCR3 and CCR4. Mouse models of asthma show that C19 can also inhibit the Th2 response. CCR3 and CCR4 are chemokine receptors important to allergic rhinitis, a condition whose pathogenesis is similar to that of asthma. Here, we established a mouse model of allergic rhinitis by repetitive sensitization and intranasal challenge with OVA and assessed whether C19 has therapeutic effects on this model. In this study, both intranasal and intraperitoneal administration of C19 reduced allergic symptoms such as sneezing and rubbing and serum concentration of IgE. C19 showed a strong ability to suppress eosinophil accumulation in nasal mucosa and lung tissues. C19 was able to suppress the Th2 cytokine IL-4 without augmenting the Th1 cytokine IFN-γ in BAL and IL-4(+) cells in the local nasal tissue. In terms of symptom amelioration, IgE reduction, and eosinophilia suppression, C19 was found to be as effective against allergic rhinitis as Budesonide. Moreover, intranasal treatment has a stronger therapeutic effect than other types of administration, and it may be more convenient and safe. For these reasons, C19 may have potential in the treatment of allergic rhinitis.

Expressions of IL-17, IL-21 and IL-23 in the Serum of Allergic Rhinitis Patients

The present study aimed to investigate the expressions of interleukin-17 (IL-17), IL-21 and IL-23 in the serum of allergic rhinitis (AR) patients and to explore their relationship with special IgE (sFgE) in the serum. AR patients (n=24) and healthy subjects (n=12) were recruited and serum samples were collected. The serum level of IgE specific for inhalant allergens was determined using the automatic quantitative immunofluorescence analysis system, and the contents of IL-17, IL-21 and IL-23 in the serum were detected using ELISA. The level of serum IgE in the healthy individuals was categorized as grade 0 and that in the AR patients as grade 2-6. The mean contents of IL-17, IL-21 and IL-23 were 164.71 ±39.37 pg/mL, 199±97.86 pg/mL and 78.94±26.33 pg/mL, respectively, in the AR patients, and 67.75±18.24 pg/mL, 7.58±5.49 pg/mL and 13.58± 3.93 pg/mL, respectively, in the healthy subjects. Statistical analysis showed the serum levels of IL-17 and IL-23 in the AR patients were markedly higher than those in the healthy subjects, however, no significant difference was noted in the content of IL-21. Furthermore, the IL-17 level was positively related to the levels of IL-23 and IgE and the IL-23 level was positively related to the IgE level among AR patients, but no relations were observed between the IL-21 level and levels of IL-17, IL-23 and IgE. Our study indicates IL-17 and IL-23 may play an important role in the pathogenesis of AR and maybe IL-21 is not involved in the occurrence of AR.

The central role of CD30L/CD30 interactions in allergic rhinitis pathogenesis in mice

CD30 ligand (CD30L) plays an important role in the amplification and/or activation of effector CD4(+) T cells, irrespective of Th cell subset. To examine the role of CD30L in allergic rhinitis, we evaluated an OVA model of allergic rhinitis in CD30L knock out (KO) mice on a BALB/c background sensitized with OVA. Symptoms of allergic rhinitis such as eosinophil infiltration into the nasal mucosa were drastically diminished in OVA-sensitized CD30L KO mice following intranasal challenge with OVA. The levels of OVA-specific IgE in the sera and the Th2 response in nasopharynx-associated lymphoid tissues and cervical LNs of CD30L KO mice were significantly lower than those of WT mice following intranasal challenge with OVA. Intranasal administration of CD30-Ig during the effector phase with OVA significantly prevented the development of allergic rhinitis in WT mice. These results suggest that CD30L plays an important role in allergic rhinitis and that the inhibition of CD30L/CD30 signaling might be useful as a novel biological therapy for allergic rhinitis.

Regulation of effector and memory T-cell functions by type I interferon

Type I interferon (IFN-α/β) is comprised of a family of highly related molecules that exert potent antiviral activity by interfering with virus replication and spread. IFN-α/β secretion is tightly regulated through pathogen sensing pathways that are operative in most somatic cells. However, specialized antigen-presenting plasmacytoid dendritic cells are uniquely equipped with the capacity to secrete extremely high levels of IFN-α/β, suggesting a key role for this cytokine in priming adaptive T-cell responses. Recent studies in both mice and humans have demonstrated a role for IFN-α/β in directly influencing the fate of both CD4(+) and CD8(+) T cells during the initial phases of antigen recognition. As such, IFN-α/β, among other innate cytokines, is considered an important 'third signal' that shapes the effector and memory T-cell pool. Moreover, IFN-α/β also serves as a counter-regulator of T helper type 2 and type 17 responses, which may be important in the treatment of atopy and autoimmunity, and in the development of novel vaccine adjuvants.

IL-21 reduces immediate hypersensitivity reactions in mouse skin by suppressing mast cell activation or IgE production

IL-21 regulates activation, proliferation, and differentiation of various immune cells. We have previously shown that exogenous IL-21 administration reduces allergic reactions in mouse models of anaphylaxis and allergic rhinitis. However, the effects of IL-21 in allergic cutaneous reactions remain unclear. In this study, we examined the effects of IL-21 in a mouse model of the IgE-mediated cutaneous immediate hypersensitivity reaction (IHR). We also investigated the mechanism of IL-21-induced regulation of allergic cutaneous reactions. Mice were sensitized by intraperitoneal ovalbumin (OVA) injection and challenged by injecting OVA intradermally into the ears, with intraperitoneal administration of recombinant murine (rm)IL-21 during the sensitization period or after completion of sensitization. After challenge, IL-21-untreated allergic mice developed biphasic responses characterized by early-phase and late-phase reactions. The biphasic reactions were significantly reduced by rmIL-21 treatment during sensitization or after completion of sensitization. Administration of rmIL-21 during sensitization reduced the cutaneous IHR by suppressing allergen-specific IgE production. In contrast, administration of rmIL-21 after completion of sensitization did not decrease serum levels of allergen-specific IgE, but significantly suppressed mast cell degranulation in skin. These results suggest that the regulatory effects of IL-21 on the cutaneous IHR involve suppression of allergen-specific IgE production or mast cell degranulation.

Role of IL-21 in inflammatory bowel disease

IL-21 was first described as a critical regulator of T- and B-cell functions. More recently, it has become apparent that IL-21 controls the activity of both immune and nonimmune cells and, depending on the timing and context analyzed, it can promote either inflammatory or counter-regulatory effects. IL-21 participates in the immune responses against tumor cells and chronic viral infections, but excessive production of IL-21 has been associated with the development of immune-inflammatory diseases in various organs. In this article, we focus on data supporting the pathogenic role of IL-21 in human inflammatory bowel diseases and discuss preclinical studies that suggest that neutralization of IL-21 in vivo could be a new strategy to counteract the inflammatory bowel disease-related, tissue damaging immune response.

Targeting interleukin-21 in rheumatoid arthritis

Interleukin-21 (IL-21) is a new member of the type I cytokine superfamily, which binds to a composite receptor that consists of a private receptor (IL-21R) and the common cytokine receptor γ chain. Recently, increasing evidence has shown that IL-21 contributes to the pathogenesis of chronic inflammatory and autoimmune diseases because of its pro-inflammatory and immune-mediated properties. IL-21 induced T-cell activation and pro-inflammatory cytokine secretion in rheumatoid arthritis (RA). IL-21R RNA transcripts were found in synovial tissue samples of patients with RA. In addition, blockade of the IL-21/IL-21R pathway ameliorated disease in animal models of RA and significantly inhibited inflammatory cytokine production in vitro. Moreover, IL-21R deficiency in the K/BxN mouse model of inflammatory arthritis was sufficient to block arthritis initiation completely. All theses findings suggest that IL-21 has important biological effects in autoimmunity that might be a promising therapeutic target for RA. In this review, we discuss the biological features of IL-21 and summarize recent advances in the role of IL-21 in the pathogenesis and treatment of RA.

Amelioration of experimental allergic rhinitis with suppression of topical immune responses by lack of IL-27/WSX-1 signaling

BACKGROUND

Allergic rhinitis is 1 of the most common atopic diseases with strong similarity to asthma. Interleukin (IL) 27 is an immunosuppressive cytokine, and lack of the IL-27 receptor (WSX-1) resulted in exacerbation of allergic airway hyperresponsiveness.

OBJECTIVE

To address the role of IL-27/WSX-1 in the rhinitis model compared with the asthma model.

METHODS

Wild-type or WSX-1(-l-) female mice were immunized intraperitoneally 4 times with ovalbumin adsorbed to aluminum potassium sulfate at a 1-week interval. The sensitized mice were then challenged for 14 days with ovalbumin intranasally from days 22 to 35. Clinical scores, serum antigen specific IgE levels, and cytokine production in the nasal lavage fluid were examined. Cytokine and chemokine expression in the cervical lymph nodes, nasopharynx-associated lymphoid tissues, and nasal mucosa was also examined.

RESULTS

WSX-1(-l-) mice developed augmented immune responses in the serum (IgE production), cervical lymph nodes (cytokine and chemokine expression), and nasopharynx-associated lymphoid tissues (cytokine and chemokine expression), whereas local responses, such as clinical scores and nasal lavage fluid cytokine production, were reduced in WSX-1(-l-) mice. Expression of some chemokines was also reduced in the nasal mucosal tissues of WSX-1(-l-) mice.

CONCLUSION

In contrast to the immunosuppressive role observed in the asthma model, IL-27/WSX-1 topically plays an exacerbating role in the pathogenesis of allergic rhinitis, presumably through differential expression of chemokines.

Inhibition of allergic responses by CD40 gene silencing

BACKGROUND

Gene silencing using small interfering RNA (siRNA) is a potent method of specifically knocking down molecular targets. Small interfering RNA is therapeutically promising, however, treatment of allergic diseases with siRNA has not been explored in vivo. The aim of this study was to evaluate therapeutic effects of CD40 siRNA on inhibition of allergic responses.

METHODS

Mice sensitized with ovalbumin (OVA) and alum were treated with CD40 siRNA, scrambled siRNA, or phosphate buffer saline (PBS) alone, and then challenged intranasally with OVA.

RESULTS

A significant reduction in nasal allergic symptoms was observed in the CD40 siRNA treated OVA-allergic mice compared to the controls of scrambled siRNA and PBS alone, which is correlated with the decrease of local eosinophil accumulation. CD40 siRNA treatment knocked down CD40 expression on dendritic cells (DCs) in vivo and impaired their antigen presenting function. Treatment with CD40 siRNA resulted in inhibition of OVA-specific T cell response and decrease of interleukin-4 (IL-4), IL-5, and interferon-gamma production from T cells stimulated with OVA. Administration of CD40 siRNA also suppressed CD40 expression on B cells, resulting in down-regulation of OVA-specific immunoglobulin E (IgE), IgG1, and IgG2a levels. Additionally, increased regulatory T cells were observed in the CD40 siRNA treated mice.

CONCLUSIONS

The present study demonstrates a novel therapeutic use for siRNA in allergy. CD40 siRNA attenuated allergy through inhibition of DC and B cell functions and generation of regulatory T (Treg) cells.

STAT3 is required for IL-21–induced secretion of IgE from human naive B cells

The production of immunoglobulin E (IgE) is tightly regulated. This is evidenced by the fact that it comprises less than 0.0001% of serum Ig, and aberrant production causes atopic conditions, including allergy, rhinitis, and anaphylaxis. Interleukin-4 (IL-4) is a well-characterized inducer of IgE by human and murine B cells, whereas interferon-γ can antagonize this effect. IL-21 has also been recognized for its ability to suppress IL-4–induced IgE production by murine B cells. Here, we identified IL-21 as an inducer of IgE production by CD40L-stimulated human naive B cells. Furthermore, there was a striking synergy between IL-4 and IL-21 on inducing IgE secretion by CD40L-stimulated human B cells, such that the levels detected under these conditions exceeded those induced by IL-4 or IL-21 alone by more than 10-fold. IL-21 induced activation of STAT3 and analysis of B cells from patients with loss-of-function STAT3 mutations revealed that the ability of IL-21 to induce IgE secretion, and augment that driven by IL-4, was STAT3-dependent. These findings highlight a fundamental difference between the regulation of IgE production by human and murine B cells and have implications for the dysregulated production of IgE in conditions characterized by extremely high levels of serum IgE.

The Yin and Yang of interleukin-21 in allergy, autoimmunity and cancer

IL-21 is a type I cytokine that like IL-2, IL-4, IL-7, IL-9, and IL-15 shares the common cytokine receptor gamma chain, gamma(c). IL-21 is produced by activated CD4(+) T cells, NKT cells, and Th17 cells and has pleiotropic actions on a range of lymphoid lineages. IL-21 regulates immunoglobulin production and drives B cell terminal differentiation into plasma cells, cooperatively expands CD8(+) T cells and drives Th17 differentiation, has inhibitory effects on antigen presentation by dendritic cells, and can be pro-apoptotic for B and NK cells. Moreover, IL-21 has potent anti-tumor effects and is implicated in the development of autoimmune diseases. Regulating IL-21 actions in vivo therefore has clinical potential for a range of diseases and is an area of active investigation.