The role of IL-33 and its receptor ST2 in human nasal epithelium with allergic rhinitis

Cockroach protease allergen induces allergic airway inflammation via epithelial cell activation

Protease allergens are known to enhance allergic inflammation but their exact role in initiation of allergic reactions at mucosal surfaces still remains elusive. This study was aimed at deciphering the role of serine protease activity of Per a 10, a major cockroach allergen in initiation of allergic inflammation at mucosal surfaces. We demonstrate that Per a 10 increases epithelial permeability by disruption of tight junction proteins, ZO-1 and occludin, and enhances the migration of Monocyte derived dendritic cell precursors towards epithelial layer as exhibited by trans-well studies. Per a 10 exposure also leads to secretion of IL-33, TSLP and intracellular Ca²⁺ dependent increase in ATP levels. Further, in vivo experiments revealed that Per a 10 administration in mice elevated allergic inflammatory parameters along with high levels of IL-33, TSLP, IL-1α and uric acid in the mice lungs. We next demonstrated that Per a 10 cleaves CD23 (low affinity IgE receptor) from the surface of PBMCs and purified B cells and CD25 (IL-2 receptor) from the surface of PBMCs and purified T cells in an activity dependent manner, which might favour Th2 responses. In conclusion, protease activity of Per a 10 plays a significant role in initiation of allergic airway inflammation at the mucosal surfaces.

Interleukin-33 produced by M2 macrophages and other immune cells contributes to Th2 immune reaction of IgG4-related disease

IgG4-related disease (IgG4-RD) is characterized by elevated serum IgG4 and marked infiltration of IgG4-positive cells in multiple organs. Interleukin-33 (IL-33) is a recently described cytokine that is secreted by damaged epithelial cells, macrophages, and dendritic cells, and potently activates helper T type 2 (Th2) immune responses, which have been suggested to play a major role in IgG4 production of IgG4-RD. Here, we assessed the expression of IL-33 and related molecules in the salivary glands (SGs) of patients with IgG4-RD versus that in patients with Sjögren's syndrome (SS) and controls. Expression of IL-33 and its receptor (ST2) was strongly detected around ectopic germinal centers (GCs) in the SGs from patients with IgG4-RD, whereas IL-33 was expressed only in epithelial cells in patients with SS and controls. Moreover, IL-33 and CD68⁺/CD163⁺ macrophages were mainly distributed around ectopic GCs in patients with IgG4-RD. Double immunofluorescence staining showed that IL-33 expression co-localized with CD68⁺/CD163⁺ macrophages. Finally, mRNA expression levels of IL-33 showed a positive correlation to those of Th2 cytokines (IL-4 and IL-13) in patients with IgG4-RD. Our data suggest that IL-33 produced by M2 macrophages might contribute to the pathogenesis of IgG4-RD via aberrant activation of Th2 immune responses.

Epithelial-Derived Cytokines in Asthma

The interaction between the airway epithelium and the inhaled environment is crucial to understanding the pathobiology of asthma. Several studies have identified an important role of airway epithelial-derived cytokines, IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) in asthma pathogenesis. These cytokines have been described as epithelial-derived alarmins that activate and potentiate the innate and humoral arms of the immune system in the presence of actual or perceived damage. Each of the three epithelial-derived alarmins has been implicated in the pathobiology of inhaled allergen-induced airway responses. The best evidence to date exists for TSLP, in that a human monoclonal antibody, which binds TSLP and prevents its engagement with its receptor, resolves airway inflammation in patients with allergic asthma and attenuates allergen-induced airway responses. Better understanding the roles that the epithelial-derived alarmins play and how they influence airway immune response may allow the development of novel therapeutics for asthma treatment.

Pollen/TLR4 Innate Immunity Signaling Initiates IL-33/ST2/Th2 Pathways in Allergic Inflammation

Innate immunity has been extended to respond environmental pathogen other than microbial components. Here we explore a novel pollen/TLR4 innate immunity in allergic inflammation. In experimental allergic conjunctivitis induced by short ragweed (SRW) pollen, typical allergic signs, stimulated IL-33/ST2 signaling and overproduced Th2 cytokine were observed in ocular surface, cervical lymph nodes and isolated CD4⁺ T cells of BALB/c mice. These clinical, cellular and molecular changes were significantly reduced/eliminated in TLR4 deficient (Tlr4-d) or MyD88 knockout (MyD88^−/−) mice. Aqueous SRW extract (SRWe) directly stimulated IL-33 mRNA and protein expression by corneal epithelium and conjunctiva in wild type, but not in Tlr4-d or MyD88^−/− mice with topical challenge. Furthermore, SRWe-stimulated IL-33 production was blocked by TLR4 antibody and NF-kB inhibitor in mouse and human corneal epithelial cells. These findings for the first time uncovered a novel mechanism by which SRW pollen initiates TLR4-dependent IL-33/ST2 signaling that triggers Th2-dominant allergic inflammation.

Lipopolysaccharide Attenuates Induction of Proallergic Cytokines, Thymic Stromal Lymphopoietin, and Interleukin 33 in Respiratory Epithelial Cells Stimulated with PolyI:C and Human Parechovirus

Epidemiological studies based on the "hygiene hypothesis" declare that the level of childhood exposure to environmental microbial products is inversely related to the incidence of allergic diseases in later life. Multiple types of immune cell-mediated immune regulation networks support the hygiene hypothesis. Epithelial cells are the first line of response to microbial products in the environment and bridge the innate and adaptive immune systems; however, their role in the hygiene hypothesis is unknown. To demonstrate the hygiene hypothesis in airway epithelial cells, we examined the effect of lipopolysaccharide (LPS; toll-like receptor 4 ligand) on the expression of the proallergic cytokines thymic stromal lymphopoietin (TSLP) and interleukin 33 (IL33) in H292 cells (pulmonary mucoepidermoid carcinoma cells). Stimulation with the TLR ligand polyI:C and human parechovirus type 1 (HPeV1) but not LPS-induced TSLP and IL33 through interferon regulatory factor 3 (IRF3) and NF-κB activity, which was further validated by using inhibitors (dexamethasone and Bay 11-7082) and short hairpin RNA-mediated gene knockdown. Importantly, polyI:C and HPeV1-stimulated TSLP and IL33 induction was reduced by LPS treatment by attenuating TANK-binding kinase 1, IRF3, and NF-κB activation. Interestingly, the basal mRNA levels of TLR signaling proteins were downregulated with long-term LPS treatment of H292 cells, which suggests that such long-term exposure modulates the expression of innate immunity signaling molecules in airway epithelial cells to mitigate the allergic response. In contrast to the effects of LPS treatment, the alarmin high-mobility group protein B1 acts in synergy with polyI:C to promote TSLP and IL33 expression. Our data support part of the hygiene hypothesis in airway epithelia cells in vitro. In addition to therapeutic targeting of TSLP and IL33, local application of non-pathogenic LPS may be a rational strategy to prevent allergies.

IL-33 circulating serum levels are increased in patients with non-segmental generalized vitiligo

IL-33 is a recently identified cytokine, encoded by the IL-33 gene, which is a member of the IL-1 family that drives the production of T-helper-2 (Th-2)-associated cytokines. Serum levels of IL-33 have been reported to be up-regulated in various T-helper (Th)-1/Th-17-mediated diseases, such as psoriasis, rheumatoid arthritis, and inflammatory bowel. To investigate whether cytokine imbalance plays a role in the pathogenesis of vitiligo, we performed a case-control association study by enzyme-linked immunosorbent assay of IL-33 in our patients. IL-33 serum levels were measured by a quantitative enzyme immunoassay technique in patients with non-segmental generalized vitiligo and compared with those of healthy controls. IL-33 serum levels in patients with vitiligo were significantly increased than those in healthy controls. There was a positive correlation of IL-33 serum levels with extension of vitiligo and disease activity. This study suggests a possible systemic role of IL-33 in the pathogenesis of vitiligo. Inhibiting IL-33 activity might be a novel therapeutic strategy in the treatment of autoimmune inflammatory disease, like vitiligo.

Interleukin-4 and interferon-γ orchestrate an epithelial polarization in the airways

Interferon-γ (IFN-γ) and interleukin-4 (IL-4) are key effector cytokines for the differentiation of T helper type 1 and 2 (Th1 and Th2) cells. Both cytokines induce fate-decisive transcription factors such as GATA3 and TBX21 that antagonize the polarized development of opposite phenotypes by direct regulation of each other's expression along with many other target genes. Although it is well established that mesenchymal cells directly respond to Th1 and Th2 cytokines, the nature of antagonistic differentiation programs in airway epithelial cells is only partially understood. In this study, primary normal human bronchial epithelial cells (NHBEs) were exposed to IL-4, IFN-γ, or both and genome-wide transcriptome analysis was performed. The study uncovers an antagonistic regulation pattern of IL-4 and IFN-γ in NHBEs, translating the Th1/Th2 antagonism directly in epithelial gene regulation. IL-4- and IFN-γ-induced transcription factor hubs form clusters, present in antagonistically and polarized gene regulation networks. Furthermore, the IL-4-dependent induction of IL-24 observed in rhinitis patients was downregulated by IFN-γ, and therefore IL-24 represents a potential biomarker of allergic inflammation and a Th2 polarized condition of the epithelium.

Overexpression of interleukin-33 is associated with poor prognosis of patients with glioma

Interleukin-33 (IL-33) has shown diagnostic and prognostic values in multiple human cancers. However, there is little knowledge on the role of IL-33 in human gliomas and its association with disease prognosis. This study aimed to evaluate the value of IL-33 in the prognosis of glioma patients. The expression of IL-33 was determined and compared in surgical specimens from 86 glioma patients and 16 normal brain tissues. The associations of IL-33 expression with the clinicopathological features and prognosis of glioma patients were assessed. qRT-PCR assay showed higher IL-33 mRNA expression in glioma tissues than in normal brain tissue ( p < 0.001), and significantly higher IL-33 mRNA expression was detected in both low- and high-grade glioma tissues relative to normal brain tissues ( p < 0.001). Western blotting revealed elevated IL-33 protein levels in glioma tissues compared to those in normal brain tissues, and immunohistochemical staining showed higher IL-33 protein expression in glioma tissues than in normal brain tissues. IL-33 expression correlated with the glioma grade ( p < 0.001) and Karnofsky performance status score ( p = 0.024), and the glioma patients with high IL-33 expression had a shorter progression-free survival ( p < 0.001) and overall survival ( p < 0.001) than those with low IL-33 expression. The univariate and multivariate analyses showed that IL-33 overexpression and the glioma grade were independent factors of a poor prognosis in glioma patients. Therefore, IL-33 may be a promising biomarker for the detection of gliomas, and IL-33 expression is useful for predicting the prognosis of the disease.

IL-33 promotes ICAM-1 expression via NF-kB in murine mast cells

BACKGROUND

IL-33, a member of the IL-1 cytokine family, binds to heterodimeric receptors ST2 and IL-1 receptor accessory protein, and activates Th2-type immune responses. The signals from the ST2 receptor are mediated by the two major pathways, including AP-1 and NF-κB molecules. The present study examined whether IL-33 induced ICAM-1 expression in bone marrow-derived mast cells (BMMCs).

METHODS

BMMCs from C57BL/6J mice, cultured in media containing IL-3 (20 ng/ml), were treated with IL-33 (50 ng/ml) for up to 72 h. ICAM-1 expression with mRNA and protein, degranulation of siRNA ICAM-1 transfected BMMCs, and cell adhesion were analyzed. In the in vivo part of the experiment rIL-33 (500 ng) was injected intradermally into the ear pinnae of mice and any resulting pathological changes were assessed.

RESULTS

ICAM-1 mRNA expression was increased one hour after IL-33 stimulation while ICAM-1 protein attained maximum expression levels 24 h after IL-33 stimulation. Moreover, IL-33-treated BMMCs showed increased cell adhesion to the LFA-1-coated plate. However, siRNA ICAM-1 transfected BMMCs did not affect Ag/IgE-mediated degranulation level compared to the wild control siRNA. Pre-treatment with a NF-κB inhibitor dramatically reduced ICAM-1 expression in IL-33-treated BMMCs, suggesting the involvement of NF-κB in the process. In vivo study, at 6 h after IL-33 treatment, MCs histologically showed up-regulated ICAM-1 expression though the number of tryptase-positive cells did not change.

CONCLUSIONS

These data suggest that MCs increase ICAM-1 expression and activate LFA-1 positive cells in the early phase of skin inflammation in response to IL-33.

Increased Levels of Interleukin-33 and Thymic Stromal Lymphopoietin in Exhaled Breath Condensate in Chronic Bronchial Asthma

BACKGROUND

Epithelium-derived cytokines such as thymic stromal lymphopoietin (TSLP), interleukin (IL)-25, and IL-33 are important contributors to inflammation in asthma. Exhaled breath condensate (EBC) is a noninvasive method used to assess the inflammation of airways. Our aim was to assess the levels of TSLP, IL-25, IL-33, and its receptor ST2l/IL-1 R4 in EBC in patients with asthma and to correlate these with serum levels and asthma control.

METHODS

EBC and serum levels of TSLP, IL-25, IL-33, and ST2l/IL-1 R4 were measured in 44 patients with chronic bronchial asthma (14 in the uncontrolled phase) and 19 healthy control participants.

RESULTS

EBC levels of IL-33 and TSLP and serum levels of IL-33 were statistically higher in patients with asthma than in controls. IL-25 and ST2l/IL-1 R4 were present in EBC at barely detectable levels and were not analyzed. The EBC and serum levels of all studied mediators did not differ between controlled and uncontrolled asthma patients, except for the serum level of ST2l/IL-1 R4, which was higher in uncontrolled asthma. There were no correlations between serum and EBC levels of TSLP and IL-33 or between either serum and EBC levels and the forced expiratory volume in 1 s or the total IgE level.

CONCLUSIONS

Higher levels of IL-33 and TSLP in EBC provide evidence supporting a role for these mediators in asthma. Their levels do not discriminate between controlled and uncontrolled asthma. The local reaction within the epithelium is independent of the systemic reaction.

IL-25/IL-33-responsive TH2 cells characterize nasal polyps with a default TH17 signature in nasal mucosa

BACKGROUND

Chronic rhinosinusitis with nasal polyposis (CRSwNP) in Western countries is characterized by eosinophilia, IgE production, and TH2 cytokine expression. Type 2 innate lymphoid cells from polyps produce IL-5 and IL-13 in response to IL-25 and IL-33, although the relevance of this axis to local mucosal T-cell responses is unknown.

OBJECTIVE

We sought to investigate the role of the IL-25/IL-33 axis in local mucosal T-cell responses in patients with CRSwNP.

METHODS

Polyp tissue and blood were obtained from patients undergoing nasal polypectomy. Control nasal biopsy specimens and blood were obtained from healthy volunteers. Tissue was cultured in a short-term explant model. T-cell surface phenotype/intracellular cytokines were assessed by means of flow cytometry. T-cell receptor variable β-chain analysis was performed with the immunoSEQ assay. Microarrays were performed for gene expression analysis.

RESULTS

IL-25 receptor (IL-17RB)-expressing TH2 effector cells were identified in nasal polyp tissue but not the healthy nasal mucosa or periphery. IL-17RB(+)CD4(+) polyp-derived TH2 cells coexpressed ST2 (IL-33 receptor) and responded to IL-25 and IL-33 with enhanced IL-5 and IL-13 production. Within IL-17RB(+)CD4(+) T cells, several identical T-cell receptor variable β-chain complementarity-determining region 3 sequences were identified in different subjects, suggesting clonal expansion driven by a common antigen. Abundant IL-17-producing T cells were observed in both healthy nasal mucosal and polyp populations, with TH17-related genes the most overexpressed compared with peripheral blood T cells.

CONCLUSION

IL-25 and IL-33 can interact locally with IL-17RB(+)ST2(+) polyp T cells to augment TH2 responses in patients with CRSwNP. A local TH17 response might be important in healthy nasal mucosal immune homeostasis.

The Complex Type 2 Endotype in Allergy and Asthma: From Laboratory to Bedside

Better management of allergic diseases needs a sharpened understanding of disease heterogeneity and mechanisms in relation to clinically significant outcomes. Phenotypes describing observable clinical and morphologic characteristics and unique responses to treatment have been developed; however, they do not relate to disease mechanisms. Recently, extended heterogeneous and disease-related metabolic, inflammatory, immunological, and remodeling pathways have been described, and reproducible patterns are defined as disease endotypes. An endotype might consist of several intricated mechanisms that cannot be clearly separated into "pure single molecular mechanism" thus being a "complex endotype." The description of an endotype may rely on biomarkers, which can be the signature of a complex underlying pathway or a key molecule associated with or directly playing a role in a particular disease endotype. The Th2 type inflammation can be defined as a complex endotype in asthma and linked to mechanisms of disease development and response to treatment and to disease outcomes such as exacerbations and remodeling. The type 2 complex endotype in allergies and asthma includes innate lymphoid cells, T helper 2 cells, tissue eosinophilia, and IgE production. Currently, emerging endotype-driven strategies in asthma, particularly the development of biologicals that target a single molecular pathway, are being focused for solving individualized clinical problems on disease outcomes. Progress is also being made for endotyping rhinitis, chronic rhinosinusitis, and atopic dermatitis.

Alternative Method for Primary Nasal Epithelial Cell Culture Using Intranasal Brushing and Feasibility for the Study of Epithelial Functions in Allergic Rhinitis

Purpose

Although differentiated normal human nasal epithelial (NHNE) cells can be used to study the role of human nasal epithelium, there is a need for effective culture models of nasal epithelium in sinonasal disease status, including allergic rhinitis (AR). We aimed to examine the feasibility of intranasal brushing for culture of nasal epithelial cells in AR patients and to verify the hypothesis that allergic nasal epithelial (ARNE) cells differ in histologic and physiologic characteristics.

Methods

We established a system for isolating (via intranasal brushing) and culturing (with air-liquid interface, ALI) nasal epithelial cells from healthy volunteers (n=8) and AR patients (n=8). We used this system to compare the histologic findings and physiologic characteristics of NHNE and ARNE.

Results

The histology results showed that fully differentiated ALI culture was obtained at least 14 days after confluence and that both ciliated and secretory cells were well differentiated in ALI culture using nasal brushing. The histology results of ARNE culture were significantly different from NHNE. The number of ciliated cells was lower, and secretory cells were more dominant in ARNE cell culture compared to NHNE cells. We also observed, by electron microscopy, loose tight junctions and short cilia in cultured ARNE cells. In addition, the mRNA level of TSLP which was one of the epithelial-derived allergic cytokines was significantly higher, and the expressions of genes involved in ciliogenesis were lower in cultured ARNE cells without allergen stimulation.

Conclusions

Our findings suggest that ALI culture of ARNE cells using intranasal brushing may be an alternative method for epithelial cell culture in AR patients and that cultured ARNE cells will be useful for in vitro studies of the mechanisms at play during AR because they maintain unique allergic characteristics.

The messenger between worlds: the regulation of innate and adaptive type-2 immunity by innate lymphoid cells

Although type-2 immune responses evolved primarily to defend against extracellular helminths, in part through the co-opting of tissue repair and remodeling mechanisms, they are often inappropriately directed towards relatively innocuous allergens resulting in conditions including asthma, allergic rhinitis, food allergy, and atopic dermatitis. The recent discovery of group 2 innate lymphoid cells (ILC2) has increased our understanding of the initiation of these responses and the roles played by CD4(+) T helper (Th) 2 cells in their modulation. This review focuses on the important messenger role of ILC2 in translating epithelial-derived alarmins into downstream adaptive type-2 responses via dendritic cells and T cells, with special emphasis on their roles in allergic disease.

The paradigm of cytokine networks in allergic airway inflammation

PURPOSE OF REVIEW

Cytokines are immunomodulatory proteins important in cell signaling. Complex interactions of innate and adaptive immune cells, as well as structural cells and their cytokines, play crucial roles in regulating allergic airway inflammation. Here, we summarize current knowledge about the potential roles of known and newly identified helper T cells and epithelial cell-derived cytokines [interleukin (IL)-9, IL-17, IL-22, IL-25, and IL-33] in allergic rhinitis and asthma.

RECENT FINDINGS

Although T-helper (Th)2 cells were considered to be the main orchestrators of allergic airway inflammation, recent studies have revealed the potential interaction of other helper T cells and their cytokines in this process. Th17 cells may have a role in allergic rhinitis and asthma, and chronic rhinosinusitis with nasal polyps. An IL-9-producing subset called Th9 cells, Th22 cells which primarily secrete IL-22, IL-13, tumor necrosis factor-α, Th25 cells via producing IL-25 and epithelial cell-derived thymic stromal lymphopoietin, IL-33, IL-31, and IL-25 are believed to be important for the initiation of allergic reactions and inducing airway inflammation.

SUMMARY

A new paradigm of an interplay of cytokines is important in allergic rhinitis and asthma in orchestrating the allergic inflammatory response. Potential therapeutic applications emerging from the roles of these cytokines are promising, but need further research.

Interaction of thymic stromal lymphopoietin, IL-33, and their receptors in epithelial cells in eosinophilic chronic rhinosinusitis with nasal polyps

BACKGROUND

Thymic stromal lymphopoietin (TSLP), IL-25, and IL-33 system contribute to the initiation and development of Th2 responses. This study aimed to explore the involvement of TSLP, IL-25, IL-33, and their receptors in type 2 T-helper (Th) responses in chronic rhinosinusitis with nasal polyps (CRSwNPs) and their cross-regulation in human nasal epithelial cells (HNECs).

METHODS

Immunohistochemistry, quantitative RT-PCR, ELISA, Bio-Plex assay, and flow cytometry were used to detect the expression of TSLP/common γ-like TSLP receptor (TSLPR)/IL-7 receptor α (IL-7Rα), IL-25/IL-17B receptor (IL-17RB), and IL-33/membrane-bound ST2 (ST2L)/soluble ST2 (sST2) in sinonasal mucosa and HNECs. HNECs cultured at an air-liquid interface were used to explore the expression in regulation of these cytokine systems.

RESULTS

Compared with controls and noneosinophilic CRSwNP, the expression of TSLP/TSLPR/IL-7Rα and ST2L/sST2 was significantly increased in eosinophilic CRSwNP, predominantly in epithelial cells. In contrast, the expression of IL-33 and IL-25/IL-17RB was enhanced in epithelial cells in both eosinophilic and noneosinophilic CRSwNP compared to controls. The expression of TSLP, TSLPR, and ST2L was positively correlated with symptom and computer tomography scan scores in eosinophilic CRSwNP and with Th2 cytokine expression in sinonasal mucosa. The expression of ST2L was correlated with TSLP and its receptor expression. TSLP could induce ST2L expression that promoted IL-33-induced TSLP expression in HNECs. In addition, TSLP/TSLPR/IL-7Rα and ST2L could be induced by Th2 cytokines, while IL-25/IL-17RB and IL-33 could be upregulated by Th1/Th17 cytokines, in HNECs.

CONCLUSIONS

The positive feedback loop between TSLP, IL-33 and their receptors, and Th2 cytokines may facilitate Th2-skewed inflammation in eosinophilic CRSwNP.

Proallergic cytokines and group 2 innate lymphoid cells in allergic nasal diseases

Recent advances in our understanding of proallergic cytokines and group 2 innate lymphoid cells (ILC2s) indicate their critical roles in type 2 immunity-mediated disorders. Proallergic cytokines, interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin, are released from epithelial cells in inflamed tissues and drive type 2 inflammation by acting on innate and acquired immune systems. ILC2s are an innate immune population that responds to proallergic cytokines by producing type 2 cytokines. In line with allergic disorders in the lung, skin, and intestine, emerging evidence suggests the involvement of proallergic cytokines and ILC2s in allergic nasal diseases such as chronic rhinosinusitis with polyps (CRSwNP), allergic fungal rhinosinusitis, and allergic rhinitis (AR). In CRSwNP patients, both proallergic cytokine levels and ILC2s frequency are increased in the nasal mucosa. Increased proallergic cytokine levels correlate with poorer disease outcomes in CRSwNP. Levels of nasal proallergic cytokines are also elevated in AR patients. In addition, animal studies demonstrate that cytokines are essential for the development of AR. It is becoming clear that the proallergic cytokine/ILC2s axis participates in allergic diseases by multiple mechanisms dependent upon the inflammatory context. Thus, a thorough understanding of these cytokines and ILC2s including their tissue- and disease-specific roles is essential for targeting the pathways to achieve therapeutic applications.

IL-33 promotes MHC class II expression in murine mast cells

Mast cells (MCs), recognized as tissue-resident cells of hematopoietic origin, are involved in cellular and pathological manifestations of allergic disorders including atopic dermatitis. IL-33, a member of the IL-1 cytokine family, activates Th2-type immune responses, and promotes the degranulation and maturation of MCs. However, it is uncertain whether IL-33 treatment induces mature mast cells to acquire the characteristics of the monocyte-dendritic cell lineage.We investigated the effect of IL-33 on the MHC class II expression and function of murine mast cells. IL-33-treated mature murine bone marrow-derived mast cells (BMMCs) were analyzed by FACS, real-time PCR, chromatin immunoprecipitation (ChIP) assay, and Western blotting. The morphology and degranulation activity of BMMCs and T-cell activation by BMMCs were also examined. BMMCs treated with IL-33 for 10 days induced cell surface expression of the MHC class II protein, whereas the expression of FcεRI and c-kit was not affected by IL-33. The expression of CIITA, driven from pIII and pIV, was up-regulated in IL-33-treated BMMCs. The amount of PU.1 mRNA and protein significantly increased in IL-33-treated BMMCs. The ChIP assay showed PU.1 binding to CIITA pIII, and enhanced histone acetylation due to IL-33 treatment. Syngeneic T cells were activated by co-culture with IL-33-treated BMMCs, although the expression of the co-stimulatory molecules, CD40, CD80, CD86, and PDL-1, was not detected. Mast cells express MHC class II after prolonged exposure to IL-33, probably due to enhanced recruitment of PU.1 to CIITA pIII, resulting in transactivation of CIITA and MHC class II. IL-33 is an important cytokine in allergic disorders. Mast cells have the ability to express MHC class II after prolonged exposure to IL-33 in a murine model. IL-33 holds a key to understanding the etiology of atopic dermatitis.

ST2 in Pulmonary Disease

In recent years, numerous studies have focused on the use of soluble ST2 (sST2) as a clinical biomarker for cardiovascular disease. However, much preclinical data points to involvement of the ST2 pathway in inflammation, and specifically in pulmonary inflammation. This report summarizes the current body of clinical data suggesting the potential role of the ST2 pathway in clinical disease, including evidence that sST2 could be a useful biomarker in both allergic and nonallergic pulmonary disease.

Alteration of circulating type 2 follicular helper T cells and regulatory B cells underlies the comorbid association of allergic rhinitis with bronchial asthma

Allergic rhinitis (AR), the most common allergic disorder of the airway, is often accompanied by bronchial asthma. However, little is known about the mechanism by which AR advances to AR comorbid with bronchial asthma (AR+Asthma). To determine the pathophysiologic features of AR and AR+Asthma, we examined subsets of follicular helper T (Tfh) cells and regulatory B (Breg) cells in peripheral blood from AR and AR+Asthma patients. The results showed polarization of Tfh2 cells within Tfh cell subsets in both AR and AR+Asthma cases. Interestingly, the %Breg cells in total B cells were decreased in AR cases and, more extensively, in AR+Asthma cases. Moreover, we found significant correlations of fractional exhaled nitric oxide and blood eosinophil levels with the index %Tfh2 cells per %Breg cells. Our findings indicate that relative decrease in Breg cells under the condition of Tfh2 cell skewing is a putative exaggerating factor of AR to bronchial asthma.

IL-33/ST2 axis controls Th2/IL-31 and Th17 immune response in allergic airway diseases

IL-33 targeting ST2 receptor (T1/ST2), expressed on Th2 cell surface, regulates the production of cytokines like IL-17A and IL-31. We studied the role of IL-33/ST2 axis in IL-31 and IL-17A production in patients with allergic rhinitis (AR) and with concomitant allergic asthma and rhinitis (AAR). 20 healthy control subjects (HC), 14 AR and 17 AAR subjects were recruited and blood samples collected. IL-33, soluble ST2 (sST2), IL-17A and IL-31 plasma concentrations were measured by ELISA method. T1/ST2, IL-31 and IL-17A cellular expression were studied in peripheral blood mononuclear cells (PBMC) from HC, AR and AAR (n=6 for each group) by flow-cytometry. In vitro, we also evaluated the effect of beclomethasone dipropionate (BDP) on T1/ST2, IL-31 and IL-17A expression in CD3(+)T-cells from PBMC of AAR (n=6). Plasma levels of IL-33, IL-31 and IL-17A were significantly higher and sST2 was lower in patients with AR and AAR than in HC. IL-31 and IL-17A intracellular levels significantly increased, whereas T1/ST2 expression was significantly lower, in CD3(+)T-cells from AR and AAR compared to HC. Positive correlations were observed between plasmatic components of IL-33/ST2 axis and IL-31 in both AR and AAR and IL-17A in AAR. In vitro IL-31 and IL-17A intracellular levels decreased after BDP treatment, whereas T1/ST2 expression increased in cultured CD3(+)T-cells obtained from AAR. IL-33/ST2 axis is involved in Th2/IL-31 and Th17 immune response during the progression of allergic airway disease. In vitro BDP is able to control Th2/IL-31 and Th17 immune response in PBMC from allergic patients.

Thymic stromal lymphopoietin: a central regulator of allergic asthma

INTRODUCTION

Epithelial cell-derived mediators have emerged as key players for instigating local remodeling and the associated cellular inflammation in asthmatic airways. In particular, the epithelial-derived cytokine, thymic stromal lymphopoietin (TSLP), has been identified as a master switch for allergic inflammation.

AREAS COVERED

TSLP is expressed by structural and immune cells at the site of allergen entry in the airways. Stimuli for release of TSLP include common triggers of asthma symptoms, and TSLP levels correlate with disease severity. TSLP regulates helper T cell 2 (Th2) humoral immunity through upregulating OX40L on dendritic cells (DCs), which drives Th2 lymphocytes; however, activation of several other cells by TSLP also supports the development of Th2 inflammation. Animal models of asthma demonstrate that increased levels of TSLP can induce many of the characteristics of asthma.

EXPERT OPINION

The work conducted to date supports a critical role of TSLP in the pathogenesis of allergic asthma. The first clinical trial to block the downstream effects of OX40L has shown reduced levels of circulating IgE and airway eosinophils, confirming the importance of TSLP-induced OX40L levels on DCs. Clinical trials with TSLP blockade are underway and will unequivocally confirm whether TSLP is indeed a key driver of allergic inflammation in asthma.

Innate responses to pollen allergens

PURPOSE OF REVIEW

The aim of the present review was to discuss the effects of pollen components on innate immune responses.

RECENT FINDINGS

Pollens contain numerous factors that can stimulate an innate immune response. These include intrinsic factors in pollens such as nicotinamide adenine dinucleotide phosphate oxidases, proteases, aqueous pollen proteins, lipids, and antigens. Each component stimulates innate immune response in a different manner. Pollen nicotinamide adenine dinucleotide phosphate oxidases induce reactive oxygen species generation and recruit neutrophils that stimulate subsequent allergic inflammation. Pollen proteases damage epithelial barrier function and increase antigen uptake. Aqueous pollen extract proteins and pollen lipids modulate dendritic cell function and induce Th2 polarization. Clinical studies have shown that modulation of innate immune response to pollens with toll-like receptor 9- and toll-like receptor 4-stimulating conjugates is well tolerated and induces clear immunological effects, but is not very effective in suppressing primary clinical endpoints of allergic inflammation.

SUMMARY

Additional research on innate immune pathways induced by pollen components is required to develop novel strategies that will mitigate the development of allergic inflammation.

Innate immunity in the lung regulates the development of asthma

The lung, while functioning as a gas exchange organ, encounters a large array of environmental factors, including particulate matter, toxins, reactive oxygen species, chemicals, allergens, and infectious microbes. To rapidly respond to and counteract these elements, a number of innate immune mechanisms have evolved that can lead to lung inflammation and asthma, which is the focus of this review. These innate mechanisms include a role for two incompletely understood cell types, invariant natural killer T (iNKT) cells and innate lymphoid cells (ILCs), which together produce a wide range of cytokines, including interleukin-4 (IL-4), IL-5, IL-13, interferon-γ, IL-17, and IL-22, independently of adaptive immunity and conventional antigens. The specific roles of iNKT cells and ILCs in immunity are still being defined, but both cell types appear to play important roles in the lungs, particularly in asthma. As we gain a better understanding of these innate cell types, we will acquire great insight into the mechanisms by which allergic and non-allergic asthma phenotypes develop.

miR-143 inhibits interleukin-13-induced inflammatory cytokine and mucus production in nasal epithelial cells from allergic rhinitis patients by targeting IL13Rα1

Allergic rhinitis (AR) is a common chronic inflammatory condition of the nasal mucosal tissue. The interleukin-13 (IL-13) signaling pathway is of great importance in the pathogenesis of AR. However, how the signaling molecules in this pathway are regulated, particularly through microRNAs (miRNAs), remains unclear. In the present study, we investigated the regulatory role and mechanism of miRNA-143 (miR-143) in IL-13-induced inflammatory cytokine and mucus production in nasal epithelial cells (NECs) from AR patients. Our results showed that forced expression of miR-143 significantly decreased the mRNA and protein expression levels of granulocyte-macrophage colony-stimulating factor (GM-CSF), eotaxin and mucin 5AC (MUC5AC) in IL-13-stimulated NECs. Moreover, we confirmed that miR-143 directly targeted and significantly suppressed IL-13 receptor α1 chain (IL13Rα1) gene expression. This study thus suggests that miR-143 regulation of IL-13-induced inflammatory cytokine and mucus production in NECs from AR patients probably partly depends on inhibition of IL13Rα1. Therefore, the IL13Rα1 signaling pathway may be a potential target for the prevention and treatment of AR by miR-143.

Therapeutic potential of combined anti-IL-1β IgY and anti-TNF-α IgY in guinea pigs with allergic rhinitis induced by ovalbumin

We have previously demonstrated that anti-IL-1β immunoglobulin yolk(IgY) inhibits pathological responses in allergic asthma guinea pigs induced by ovalbumin(OVA). This study aims to determine whether the combined blockade of IL-1β and TNF-α can more effectively inhibit allergic inflammation in allergic rhinitis(AR) guinea pigs induced by OVA. Healthy guinea pigs treated with saline were used as the healthy control. The AR guinea pigs induced by OVA were randomly divided into (1) the AR model group containing negative control animals treated with intranasal saline; (2) the 0.1% non-specific IgY treatment group treated with non-specific IgY; (3) the 0.1% anti-TNF-α IgY treatment group treated with 0.1% anti-TNF-α IgY; (4) the 0.1% anti-IL-1β IgY treatment group treated with 0.1% anti-IL-1β IgY; (5) the 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY treatment group treated with 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY; and (6) the fluticasone propionate treatment group treated with fluticasone propionate. Cytokines were measured using an enzyme-linked immunosorbent assay. The results showed that IL-1β, IL-5, IL-9, IL-13, IL-18, IL-22, IL-33, TNF-α, TGF-β1 and OVA-specific IgE levels in the peripheral blood (PB) and nasal lavage fluid (NLF) significantly decreased at 2h, 4h or 8h in the 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY treatment group compared to the AR model group and the 0.1% non-specific IgY treatment group (P<0.05). The data suggest that blockade of IL-1β and TNF-α by intranasal instillation of combined anti-IL-1β IgY and anti-TNF-α IgY could be a potential alternative strategy for preventing and treating allergic rhinitis.

IL-33 stimulates CXCL8/IL-8 secretion in goblet cells but not normally differentiated airway cells

BACKGROUND

IL-13, a helper T cell type 2 (Th2) cytokine, transforms cultured airway epithelial cells to goblet cells, and this is not inhibited by corticosteroids. IL-33 stimulates Th2 cytokines and is highly expressed in airways of persons with asthma. The effect of IL-33 on goblet cell differentiation and cytokine secretion has not been described.

OBJECTIVE

We examined the effect of IL-33 on CXCL8/IL-8 secretion from goblet or normally differentiated human bronchial epithelial (NHBE) cells and signalling pathways associated with IL-33 activation in these cells.

METHODS

Normal human bronchial epithelial cells were grown to goblet or normally differentiated ciliated cell phenotype at air-liquid interface in the presence or absence of IL-13. After 14 days, differentiated cells were exposed to IL-33 for 24 h.

RESULTS

CXCL8/IL-8 secretion into the apical (air) side of the goblet cells was greater than from normally differentiated cells (P < 0.01), and IL-33 stimulated apical CXCL8/IL-8 release from goblet cells, but not from normally differentiated cells (P < 0.01). IL-33 increased ERK 1/2 phosphorylation in goblet cells (P < 0.05), and PD98059, a MAPK/ERK kinase inhibitor, attenuated IL-33-stimulated CXCL8/IL-8 secretion from goblet cells (P < 0.001). IL-13 induced ST2 mRNA (P < 0.02) and membrane-bound ST2 protein expression on the apical side surface of goblet cells compared with normally differentiated cells, and neutralization with anti-ST2R antibody attenuated IL-33-induced apical CXCL8/IL-8 secretion from goblet cells (P < 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

Goblet cells secrete CXCL8/IL-8, and this is increased by IL-33 through ST2R-ERK pathway, suggesting a mechanism for enhanced airway inflammation in the asthmatic airway with goblet cell metaplasia.

Indications for distinct pathogenic mechanisms of asbestos and silica through gene expression profiling of the response of lung epithelial cells

Occupational and environmental exposures to airborne asbestos and silica are associated with the development of lung fibrosis in the forms of asbestosis and silicosis, respectively. However, both diseases display distinct pathologic presentations, likely associated with differences in gene expression induced by different mineral structures, composition and bio-persistent properties. We hypothesized that effects of mineral exposure in the airway epithelium may dictate deviating molecular events that may explain the different pathologies of asbestosis versus silicosis. Using robust gene expression-profiling in conjunction with in-depth pathway analysis, we assessed early (24 h) alterations in gene expression associated with crocidolite asbestos or cristobalite silica exposures in primary human bronchial epithelial cells (NHBEs). Observations were confirmed in an immortalized line (BEAS-2B) by QRT-PCR and protein assays. Utilization of overall gene expression, unsupervised hierarchical cluster analysis and integrated pathway analysis revealed gene alterations that were common to both minerals or unique to either mineral. Our findings reveal that both minerals had potent effects on genes governing cell adhesion/migration, inflammation, and cellular stress, key features of fibrosis. Asbestos exposure was most specifically associated with aberrant cell proliferation and carcinogenesis, whereas silica exposure was highly associated with additional inflammatory responses, as well as pattern recognition, and fibrogenesis. These findings illustrate the use of gene-profiling as a means to determine early molecular events that may dictate pathological processes induced by exogenous cellular insults. In addition, it is a useful approach for predicting the pathogenicity of potentially harmful materials.

Damage-associated molecular patterns stimulate interleukin-33 expression in nasal polyp epithelial cells

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a disorder characterized by eosinophilic inflammation and local T-helper 2 (Th2) cytokine production. Innate lymphoid cells that elaborate Th2 cytokines have recently been characterized within nasal polyps. These cells can be activated by the epithelial cell-derived cytokine interleukin-33 (IL-33). The objective of this study is to determine whether 2 molecules associated with tissue damage (high mobility group box-1 [HMGB-1] and adenosine triphosphate [ATP]) elicit expression of IL-33 in sinonasal epithelial cells (SNECs) derived from recalcitrant CRSwNP patients.

METHODS

Ethmoid tissue was obtained from 8 recalcitrant CRSwNP and 9 control subjects during endoscopic sinus surgery (ESS). Tissue was prepared for immunohistochemistry and for SNEC air-liquid interface culture. After exposure to either HMGB1 or ATP in vitro, SNECs were processed for messenger RNA (mRNA) extraction and immunocytochemistry. IL-33 levels were determined by real-time polymerase chain reaction (PCR) and by immunochemical staining with anti-IL-33 antibody.

RESULTS

Intranuclear IL-33 is normally expressed in basal epithelial cells, but is present in more apical cells and outside the nucleus in CRSwNP. Exposure of SNECs to HMGB-1 or ATP resulted in a statistically significant increase in IL-33 mRNA expression in SNECs derived from recalcitrant CRSwNP patients. This increase was reflected at the protein level by immunochemical staining of IL-33.

CONCLUSION

Tissue damage is a nonspecific trigger of epithelial IL-33 production in treatment-recalcitrant polyps, which may be responsible for perpetuating eosinophilic inflammation in CRSwNP. This common pathway may help explain why multiple environmental and infectious agents have been implicated in CRSwNP exacerbation.

Expression of interleukin-33 is correlated with poor prognosis of patients with squamous cell carcinoma of the tongue

OBJECTIVE

The aim of this study was to clarify the role of IL-33 in tumor progression.

METHODS

Surgical specimens from 81 patients with squamous cell carcinoma of the tongue were studied using immunohistochemistry. Primary tumor sections were analyzed for IL-33 and ST2 expression. To examine the influence of IL-33 on the microenvironment of the tumor, we determined the mast cell density (MCD) and microvessel density of the stroma.

RESULTS

Patients with high IL-33 expression had a significantly worse prognosis (p=0.004). IL-33 expression was significantly elevated in patients with local and nodal recurrence (p=0.014 and p=0.019). ST2 expression was also associated with a worse prognosis (p=0.024) and was significantly elevated in patients with nodal recurrence (p=0.004). MCD was associated with worse prognosis (p=0.038) and correlated significantly with IL-33 expression (r=0.626, p<0.001). Micovessels in the stroma were significantly increased in the high IL-33 group (p<0.001).

CONCLUSION

These data suggest that the IL-33/ST2 axis contributes to tumor aggressiveness and affects the tumor microenvironment. Immunohistochemical evaluation of IL-33 and ST2 is useful for identifying patients at a high risk for poor prognosis.

The roles of innate lymphoid cells in the development of asthma

Asthma is a common pulmonary disease with several different forms. The most studied form of asthma is the allergic form, which is mainly related to the function of Th2 cells and their production of cytokines (IL-4, IL-5, and IL-13) in association with allergen sensitization and adaptive immunity. Recently, there have been many advances in understanding non-allergic asthma, which seems to be related to environmental factors such as air pollution, infection, or even obesity. Cells of the innate immune system, including macrophages, neutrophils, and natural killer T cells as well as the newly described innate lymphoid cells, are effective producers of a variety of cytokines and seem to play important roles in the development of non-allergic asthma. In this review, we focus on recent findings regarding innate lymphoid cells and their roles in asthma.

Developments in the field of allergy in 2012 through the eyes of Clinical & Experimental Allergy

In 2012, we received 683 submissions and published 20 editorials, 38 reviews, 11 letters and 128 original articles. This represents an acceptance rate for original papers in the range of 20%. About 30% of original papers were triaged not to go out to review, either because the editors did not feel they had sufficient priority for publication or because the topic did not feel right for the readers of the journal. We place great emphasis on obtaining sufficient high-quality reviews to make our decisions on publication fair and consistent. Inevitably, however, there is a degree of luck about what gets published and which papers miss out, and we are always happy to receive an appeal on our decisions either at the triage stage or after review. This gives us the opportunity to revisit the decision and revise it or explain in more detail to the authors the basis for the decision. Once again in 2012, we were delighted by the quality of the papers submitted and the breadth and depth of research into allergic disease that it revealed. The pattern of papers submitted was similar in previous years with considerable emphasis on all aspects of asthma and rhinitis. We were particularly pleased with our special issue on severe asthma. Elucidating mechanisms using either animal models or patients has always been a major theme of the journal, and the excellent work in these areas has been summarized by Harissios Vliagoftis with a particularly interesting section on early-life events guiding the development of allergic disease, which understandably continue to be a major theme of research. Magnus Wickman summarized the papers looking at the epidemiology of allergic disease including work from birth cohorts, which are an increasingly rich source of data on risk factors for allergic disease, and two papers on the epidemiology of anaphylaxis. Giovanni Passalacqua discussed the papers in the clinical allergy section of the journal, and Adriano Mari who runs the excellent Allergome website discussed the papers looking at allergens including characterization and the relative usefulness of allergen arrays versus single extracts in diagnosis and management.

Transport of Pru p 3 across gastrointestinal epithelium - an essential step towards the induction of food allergy?

BACKGROUND

Since intestinal absorption of food protein can trigger an allergic reaction, the effect of plant food allergen on intestinal epithelial cell permeability and its ability to cross the epithelial monolayer was evaluated.

OBJECTIVE

To study the interaction of Pru p 3 with intestinal epithelium, its natural entrance, analyzing transport kinetics and cellular responses that trigger.

METHODS

This was achieved using Pru p 3, the peach LTP, as a model. Enterocytic monolayers were established by culturing Caco 2 cells, as a model of enterocytes, on permeable supports that separate the apical and basal compartments. Pru p 3 was added to the apical compartment, the transepithelial resistance (TEER) was measured, and the transport was quantified.

RESULTS

The peach allergen that crossed the cell monolayer was detected in the cell fraction and in the basal medium by immunodetection with specific antibodies and the quantity was measured by ELISA assay. Pru p 3 was able to cross the monolayer without disturbing the integrity of the tight junctions. This transport was significantly higher than that of a non-allergenic peach LTP, LTP1, and occurred via lipid raft pathway. The incubation of Caco 2 cells with Pru p 3 and LTP1 produced the expression of epithelial-specific cytokines TSLP, IL33 and IL25.

CONCLUSION

These results suggest that Pru p 3 was able to cross the cell monolayer by the transcellular route and then induce the production of Th2 cytokines. The results of the present study represent a step towards clarifying the importance of Pru p 3 as a sensitizer.

CLINICAL RELEVANCE

The capacity of food allergens to cross the intestinal monolayer could explain their high allergenic capacity and its fast diffusion through the body associating to severe symptoms.

Innate lymphoid cells and asthma

Asthma is a complex and heterogeneous disease with several phenotypes, including an allergic asthma phenotype characterized by TH2 cytokine production and associated with allergen sensitization and adaptive immunity. Asthma also includes nonallergic asthma phenotypes, such as asthma associated with exposure to air pollution, infection, or obesity, that require innate rather than adaptive immunity. These innate pathways that lead to asthma involve macrophages, neutrophils, natural killer T cells, and innate lymphoid cells, newly described cell types that produce a variety of cytokines, including IL-5 and IL-13. We review the recent data regarding innate lymphoid cells and their role in asthma.

Cytokine profiles in allergic rhinitis

Allergic rhinitis, particularly seasonal allergic rhinitis, is considered a classic Th2-mediated disease, with important contributions to pathology by interleukins 4, 5 and 13. As such, allergic rhinitis is an excellent model for studying allergic inflammation, with findings potentially relevant to the mechanism of lower airways inflammation seen in allergic asthma. However, recent evidence has revealed roles for additional non-Th2 cytokines in asthma, including IL-17 family cytokines and epithelial-derived cytokines. Additionally, putative roles for epithelial-derived cytokines and innate lymphoid cells have been described in chronic rhinosinusitis with nasal polyps. Here, evidence for the involvement of different cytokines and cytokine groups in allergic rhinitis is considered.

Asthma and Mast Cell Biology

Asthma is a chronic inflammatory disease of the lung and its pathophysiology is initiated by mast cell activation in response to the antigen binding to IgE receptor as well as by TH2 cell activation. Mast cells are well established effector cells in asthma where they exacerbate the inflammatory response, playing a key role in early phase, degranulating and increasing histamine. Human mast cells possess high affinity IgE receptors and are ubiquitous but predominantly localized in mucosal and connective tissue and are distributed along blood vessels. There are two types of mast cells: connective tissue mast cells (TC) and mucosal mast cells (T mast cells). TC mast cells contain more heparin, whereas T mast cells contain more chondroitin sulfate. In asthma, mast cell activation can trigger degranulation, releasing secretory granule complex and preformed mediators, such as histamine and proteases, along with the synthesis of leukotrines and prostaglandins, and induction of cytokines and chemokines. Leukotrine inhibitors and omalizumab, which inhibits IgE, both relieve the asthma exacerbation when administered to humans and permit to reduce the use of other drugs. The release of cytokines by mast cells, such as TNF-alpha, IL-1, IL-6 and IL-33, participate in the pathogenesis of asthma. Stress worsens asthma, and this effect is also mediated by mast cell activation through the release of cytokines. Administration of IL-33 in experimental animals provokes pathological effects in the mucosal tissues and augments antibody IgE and IgA in blood vessels. Here, we report the impact of mast cell biology in asthma pathogenesis.

Isolation and culture of primary human nasal epithelial cells from anesthetized nasal epithelia

CONCLUSION

Using a local anesthetic agent before obtaining nasal biopsies by nasal brushing makes the sampling procedure smooth, avoids lacrimation, nasal itching/irritation, and/or sneezing and provides enough viable cells to establish primary cultures.

OBJECTIVES

To examine the use of local anesthesia to avoid the irritation experienced by the subject when nasal biopsies are obtained by nasal brushing in order to culture viable nasal epithelial cells.

METHODS

Nasal epithelial cells were collected from the mid-part of the inferior turbinate of healthy volunteers by brushing with interdental brushes, after spraying a topical anesthetic on the nasal mucosa. Immunocytochemistry was performed to assess the purity of epithelial cells.

RESULTS

Cell samples ranging from 1.16 × 10(5) to 3.06 × 10(5) cells/per sample were obtained. Of 11 samples, 7 formed confluent cultures, while the remaining 4 samples showed only patches of epithelial cells. Neither fungal nor bacterial contamination posed a problem. Immunocytochemistry of the cytospin slides confirmed the presence of epithelial cells in the cultures. No adverse effects were experienced by the volunteers.

The anti-atherogenic cytokine interleukin-33 inhibits the expression of a disintegrin and metalloproteinase with thrombospondin motifs-1, -4 and -5 in human macrophages: Requirement of extracellular signal-regulated kinase, c-Jun N-terminal kinase and phosphoinositide 3-kinase signaling pathways

Atherosclerosis is an inflammatory disorder of the vasculature regulated by cytokines. Amongst the cytokines, IL-33 attenuates the development of atherosclerosis in mouse model systems via several mechanisms, including inhibition of macrophage foam cell formation and promotion of a Th1 to Th2 shift. Proteases produced by macrophages, such as matrix metalloproteinases and members of ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, play potential roles in regulating atherosclerotic plaque stability. Despite such importance, the action of IL-33 on the expression of such proteases has not been analyzed. We have therefore investigated the effect of IL-33 on the expression of ADAMTS-1, -4 and -5 in human macrophages. Immunohistochemical analysis showed that these three proteases were expressed in human atherosclerotic lesions, particularly by macrophages and, to a lesser extent, by smooth muscle cells and endothelial cells. The expression of ADAMTS-1, -4 and -5 in human macrophages was specifically inhibited by IL-33. The action of IL-33 on the expression of these ADAMTS members was mediated through its receptor ST2. IL-33 activated ERK1/2, JNK1/2 and c-Jun, but not p38 MAPK or Akt, in human macrophages. RNA interference assays using a combination of adenoviral encoding small hairpin RNA and small interfering RNA showed a requirement of ERK1/2, JNK1/2, c-Jun, PI3Kγ and PI3Kδ, but not p38α, in the IL-33-inhibited expression of these ADAMTS isoforms. These studies provide novel insights into the expression of ADAMTS-1, -4 and -5 in human atherosclerotic lesions and the regulation of their expression in human macrophages by the key anti-atherogenic cytokine IL-33.

Expression of IL-33 and its receptor ST2 in chronic rhinosinusitis with nasal polyps

OBJECTIVES/HYPOTHESIS

Interleukin (IL)-33 is a novel member of the IL-1 cytokine family and a ligand for the orphan IL-1 family receptor ST2. IL-33 induces T helper 2-type inflammatory responses and is considered to play a crucial role in allergic inflammatory reactions such as asthma and atopic dermatitis. However, the role of IL-33 and its receptor ST2 in chronic rhinosinusitis remains unclear.

STUDY DESIGN

In vitro study.

METHODS

The expression patterns of IL-33 and ST2 at both mRNA and protein levels in nasal polyps from eosinophilic chronic rhinosinusitis (ECRS) patients (n = 10) and non-ECRS patients (n = 13), as well as in seemingly normal mucosa of the uncinate processes in patients without sinusitis (control; n = 5), were compared using immunohistochemical staining, enzyme-linked immunosorbent assay, and real-time polymerase chain reactions.

RESULTS

ST2-positive cells in the inflammatory cells in the subepithelial layer were significantly higher in the ECRS group than other groups. The expression of ST2 mRNA in polyps of the ECRS group was significantly increased compared with controls. Many ST2-positive eosinophils were observed in the mucosa of ECRS but not in the mucosa of non-ECRS patients. The expression level of IL-33 mRNA was not significantly different among the three groups.

CONCLUSIONS

The current study suggests that IL-33 and its receptor ST2 may play important roles in the pathogenesis of chronic rhinosinusitis, especially in ECRS, through the increased expression of ST2 in eosinophils.

LEVEL OF EVIDENCE

N/A.

Potential autocrine regulation of interleukin-33/ST2 signaling of dendritic cells in allergic inflammation

This study identified a novel phenomenon that dendritic cells (DCs) produced interleukin (IL)-33 via Toll-like receptor (TLR)-mediated innate pathway. Mouse bone marrow-derived DCs were treated with or without microbial pathogens or recombinant murine IL-33. IL-33 mRNA and protein were found to be expressed by DCs and largely induced by several microbial pathogens, highly by lipopolysaccharide (LPS) and flagellin. Using two mouse models of topical challenge by LPS and flagellin and experimental allergic conjunctivitis, IL-33-producing DCs were observed in ocular mucosal surface and the draining cervical lymph nodes in vivo. The increased expression levels of myeloid differentiation primary-response protein 88 (MyD88), nuclear factor (NF)-κB1, NF-κB2, and RelA accompanied by NF-κB p65 nuclear translocation were observed in DCs exposed to flagellin. IL-33 induction by flagellin was significantly blocked by TLR5 antibody or NF-κB inhibitor quinazoline and diminished in DCs from MyD88 knockout mice. IL-33 stimulated the expression of DC maturation markers, CD40 and CD80, and proallergic cytokines and chemokines, OX40L, IL-4, IL-5, IL-13, CCL17 (C-C motif chemokine ligand 17), TNF-α (tumor necrosis factor-α), and IL-1β. This stimulatory effect of IL-33 in DCs was significantly blocked by ST2 antibody or soluble ST2. Our findings demonstrate that DCs produce IL-33 via TLR/NF-κB signaling pathways, suggesting a molecular mechanism by which local allergic inflammatory response may be amplified by DC-produced IL-33 through potential autocrine regulation.

Potential contribution of interleukin-33 to the development of interstitial lung disease in patients with primary Sjogren's Syndrome

OBJECTIVE

To determine whether interleukin (IL)-33 and soluble ST2 (sST2) are associated with primary Sjogren's Syndrome (pSS).

METHODS

Serum levels of IL-33 and sST2 in 110 pSS patients and 78 healthy controls were measured by enzyme-linked immunosorbent assay (ELISA). Immunoglobulins, rheumatoid factors (RF), antinuclear antibody (ANA), anti-SSA/RO-52 antibody, anti-SSB antibody and erythrocyte sedimentation rate (ESR) were measured by standard laboratory techniques. Interstitial lung disease (ILD) was identified on high-resolution computed tomography (HRCT). Disease activity in pSS was scored with the European League Against Rheumatism Sjogren's Syndrome Disease Activity Index (ESSDAI).

RESULTS

Serum levels of IL-33 and sST2 were significantly elevated in pSS patients, especially in patients with ILD. There was significant positive correlation between IL-33 and RF, anti-SSB antibody.

CONCLUSION

IL-33/sST2 may be involved in the pathogenesis of pSS and partly contribute to the ILD in pSS patients.

Cytokine and chemokine responses to helminth and protozoan parasites and to fungus and mite allergens in neonates, children, adults, and the elderly

Background

In rural sub-Saharan Africa, endemic populations are often infected concurrently with several intestinal and intravascular helminth and protozoan parasites. A specific, balanced and, to an extent, protective immunity will develop over time in response to repeated parasite encounters, with immune responses initially being poorly adapted and non-protective. The cellular production of pro-inflammatory and regulatory cytokines and chemokines in response to helminth, protozoan antigens and ubiquitous allergens were studied in neonates, children, adults and the elderly.

Results

In children schistosomiasis prevailed (33%) while hookworm and Entamoeba histolytica/E. dispar was found in up to half of adults and the elderly. Mansonella perstans filariasis was only present in adults (24%) and the elderly (25%). Two or more parasite infections were diagnosed in 41% of children, while such polyparasitism was present in 34% and 38% of adults and the elderly. Cytokine and chemokine production was distinctively inducible by parasite antigens; pro-inflammatory Th2-type cytokine IL-19 was activated by Entamoeba and Ascaris antigens, being low in neonates and children while IL-19 production enhanced “stepwise” in adults and elderly. In contrast, highest production of MIP-1delta/CCL15 was present in neonates and children and inducible by Entamoeba-specific antigens only. Adults and the elderly had enhanced regulatory IL-27 cytokine responses, with Th2-type chemokines (MCP-4/CCL13, Eotaxin-2/CCL24) and cytokines (IL-33) being notably inducible by helminth- and Entamoeba-specific antigens and fungus-derived allergens. The lower cellular responsiveness in neonates and children highlighted the development of a parasite-specific cellular response profile in response to repeated episodes of exposure and re-infection.

Conclusions

Following repeated exposure to parasites, and as a consequence of host inability to prevent or eliminate intestinal helminth or protozoa infections, a repertoire of immune responses will evolve with lessened pro-inflammatory and pronounced regulatory cytokines and chemokines; this is required for partial parasite control as well as for preventing inadequate and excessive host tissue and organ damage.

The role of type 2 innate lymphoid cells in asthma

Asthma is a complex and heterogeneous disease with several phenotypes, including an allergic asthma phenotype, characterized by Th2 cytokine production and associated with allergen sensitization and adaptive immunity. Asthma also includes nonallergic asthma phenotypes that require innate rather than adaptive immunity. These innate pathways to asthma involve macrophages, neutrophils, as well as ILCs, newly described cell types that produce a variety of cytokines, including IL-5 and IL-13. We review the recent data regarding ILCs and their role in asthma.

Allergic rhinitis, chronic rhinosinusitis and asthma: unravelling a complex relationship

PURPOSE OF REVIEW

Allergic rhinitis, chronic rhinosinusitis (CRS) and asthma have a high worldwide prevalence and confer a significant socioeconomic burden. This article reviews the recent advances in allergic rhinitis, CRS and asthma with view to understanding the upper and lower airway as one system.

RECENT FINDINGS

Allergic rhinitis, CRS and asthma demonstrate strong epidemiological coassociation, and early life risk factors for upper airway disease are now apparent. The absence of demonstrable peripheral IgE does not strictly classify airway disease as nonallergic. Excess mucosal inflammation with immune dysregulation is a common feature to all. An important role for innate immunity is now apparent and offers prospects of novel therapeutic approaches in the future. A role for bacterial superantigens is also emerging in all three diseases. Genetic studies highlight common associations between allergic rhinitis, CRS and asthma.

SUMMARY

Whether such overlapping pathological findings reflect a manifestation of the same disease but in relation to the different airway locations in individuals with genetic predisposition remains unknown, although likely. This continues under investigation and debate. The current research priorities are to understand what key events predispose to both upper and lower airway disease together and the critical immunological factors that establish and sustain airway inflammation.