Interleukin-13 in asthma pathogenesis

Therapeutic effects of rosmarinic acid on airway responses in a murine model of asthma

Rosmarinic acid (RA) is an active component of a traditional Chinese herbal medicine. Previously, we reported that RA exerted a strong anti-inflammatory effect in a mouse acute lung injury model. Therefore, we hypothesized that RA might also have potential therapeutic effects in a murine model of asthma. In this study, we aimed to evaluate the anti-asthmatic activity of RA and explored its possible molecular mechanisms of action. Female BALB/c mice that had been sensitized to and challenged with ovalbumin (Ova) were treated with RA (20mg/kg) 1h after challenge. The results showed that RA greatly diminished the number of inflammatory cells and the production of Th2 cytokines in the bronchoalveolar lavage fluid (BALF); significantly reduced the secretion of total IgE, Ova-specific IgE, and eotaxin; and markedly ameliorated airway hyperresponsiveness (AHR) compared with Ova-induced mice. Histological studies further revealed that RA substantially decreased inflammatory cells infiltration and mucus hypersecretion compared with Ova-induced mice. Moreover, our results suggested that the protective effects of RA were mediated by the inhibition of JNK and p38 MAPK phosphorylation and nuclear factor-κB (NF-κB) activation. Furthermore, RA treatment resulted in a significant reduction in the mRNA expression of AMCase, CCL11, CCR3, Ym2 and E-selectin in lung tissue. These findings suggest that RA may effectively delay the development of airway inflammation and could thus be used as a therapy for allergic asthma.

Conformational flexibility of an anti-IL-13 DARPin†

Designed ankyrin repeat proteins (DARPin^®) are artificial non-immunoglobulin binding proteins with potential applications as therapeutic molecules. DARPin 6G9 binds interleukin-13 with high affinity and blocks the signaling pathway and as such is promising for the treatment of asthma and other atopic diseases. The crystal structures of DARPin 6G9 in the unbound form and in complex with IL-13 were determined at high resolution. The DARPin competes for the same epitope as the IL-13 receptor chain 13Rα1 but does not interfere with the binding of the other receptor chain, IL-4Rα. Analysis of multiple copies of the DARPin molecule in the crystal indicates the conformational instability in the N-terminal cap that was predicted from molecular dynamics simulations. Comparison of the DARPin structures in the free state and in complex with IL-13 reveals a concerted movement of the ankyrin repeats upon binding resulted in the opening of the binding site. The induced-fit mode of binding employed by DARPin 6G9 is very unusual for DARPins since they were designed as particularly stable and rigid molecules. This finding shows that DARPins can operate by various binding mechanisms and suggests that some flexibility in the scaffold may be an advantage.

Allergies - A T cells perspective in the era beyond the TH1/TH2 paradigm

Allergic diseases have emerged as a major health care burden, especially in the western hemisphere. They are defined by overshooting reactions of an aberrant immune system to harmless exogenous stimuli. The T_H1/T_H2 paradigm assumes that a dominance of T_H2 cell activation and an inadequate T_H1 cell response are responsible for the development of allergies. However, the characterization of additional T helper cell subpopulations such as T_H9, T_H17, T_H22, T_HGM-CSF and their interplay with regulatory T cells suggest further layers of complexity. This review summarizes state-of-the-art knowledge on T cell diversity and their induction, while revisiting the T_H1/T_H2 paradigm. With respect to these numerous contributors, it offers a new perspective on the pathogenesis of asthma, allergic rhinitis (AR) and atopic dermatitis (AD) incorporating recent discoveries in the field of T cell plasticity.

The role of IL-29 in immunity and cancer

Interleukin-29 (IL-29) is a new member of the recently discovered interferon λ (IFNλ) family. It is produced predominantly by maturing dendritic cells and macrophages. It has been implicated in numerous immunological responses and has shown antiviral activity similar to the Type I interferons, although its target cell population is more limited than the Type I interferons. In recent years, the role of IL-29 in the pathogenesis of various cancers has also been extensively studied. In this review, we will discuss the recent advances of IL-29 in immunological processes and the pathogenesis of various cancer.

IL-13 Augments Compressive Stress-Induced Tissue Factor Expression in Human Airway Epithelial Cells

Tissue factor (TF) is best known as a cellular initiator of coagulation, but it is also a multifunctional protein that has been implicated in multiple pathophysiologic conditions, including asthma. In the lung, airway epithelial cells express TF, but it is unknown how TF expression is regulated by asthma-associated mediators. We investigated the role of IL-13, a type 2 cytokine, alone and in combination with compressive stress, which mimics asthmatic bronchoconstriction, on TF expression and release of TF-positive extracellular vesicles from primary normal human bronchial epithelial cells. Well-differentiated normal human bronchial epithelial cells were treated with IL-13 and compressive stress, alone and in combination. TF mRNA, protein and activity were measured in the cells and conditioned media. TF was also measured in the bronchoalveolar lavage (BAL) fluid of allergen-challenged mice and patients with asthma. IL-13 and compressive stress increased TF expression, but only compressive stress induced TF-positive extracellular vesicle release. Pretreatment with IL-13 augmented compressive stress-induced TF expression and release. TF protein and activity in BAL fluid were increased in allergen-sensitized and -challenged mice. TF was elevated in the BAL fluid of patients with mild asthma after an allergen challenge. Our in vitro and in vivo data indicate close cooperation between mechanical and inflammatory stimuli on TF expression and release of TF-positive extracellular vesicles in the lungs, which may contribute to pathophysiology of asthma.

Matrix Metalloproteinase-Targeted Imaging of Lung Inflammation and Remodeling

Imaging techniques for detection of molecular and cellular processes that precede or accompany lung diseases are needed. Matrix metalloproteinases (MMPs) play key roles in the development of pulmonary pathology. The objective of this study was to investigate the feasibility of in vivo MMP-targeted molecular imaging for detection of lung inflammation and remodeling.

METHODS

Lung-specific IL-13 transgenic (Club cell 10-kDa protein [CC10]-IL-13 Tg) mice and wild-type littermates were used in this study. Lung structure, gene expression, and MMP activity were assessed by histology, real-time reverse transcription polymerase chain reaction, Western blotting, and zymography. MMP activation was imaged by in vivo small-animal SPECT/CT followed by ex vivo planar imaging. Signal specificity was addressed using a control tracer. The correlation between in vivo MMP signal and gene expression was addressed.

RESULTS

CC10-IL-13 Tg mice developed considerable pulmonary tissue remodeling and inflammation. CD68, MMP-12, and MMP-13 were significantly higher in CC10-IL-13 Tg lungs. On in vivo small-animal SPECT/CT and ex vivo planar images, the MMP signal was significantly higher in the lungs of CC10-IL-13 Tg mice than wild-type animals. Furthermore, a nonbinding analog tracer showed significantly lower accumulation in CC10-IL-13 Tg lungs relative to the specific tracer. There was a significant correlation between small-animal SPECT/CT-derived MMP signal and CD68 expression in the lungs (r = 0.70, P < 0.01).

CONCLUSION

Small-animal SPECT/CT-based MMP-targeted imaging of the lungs is feasible and reflects pulmonary inflammation. If validated in humans, molecular imaging of inflammation and remodeling can potentially help early diagnosis and monitoring of the effects of therapeutic interventions in pulmonary diseases.

Air pollution-related metals induce differential cytokine responses in bronchial epithelial cells

Different transition metals have been shown to induce inflammatory responses in lung. We have compared eight different metal ions with regard to cytokine responses, cytotoxicity and signalling mechanisms in a human lung epithelial cell model (BEAS-2B). Among the metal ions tested, there were large differences with respect to pro-inflammatory potential. Exposure to Cd(2+), Zn(2+) and As(3+) induced CXCL8 and IL-6 release at concentrations below 100μM, and Mn(2+) and Ni(2+) at concentrations above 200μM. In contrast, VO4(3-), Cu(2+) and Fe(2+) did not induce any significant increase of these cytokines. An expression array of 20 inflammatory relevant genes also showed a marked up-regulation of CXCL10, IL-10, IL-13 and CSF2 by one or more of the metal ions. The most potent metals, Cd(2+), Zn(2+) and As(3+) induced highest levels of oxidative activity, and ROS appeared to be central in their CXCL8 and IL-6 responses. Activation of the MAPK p38 seemed to be a critical mediator. However, the NF-κB pathway appeared predominately to be involved only in Zn(2+)- and As(3+)-induced CXCL8 and IL-6 responses. Thus, the most potent metals Cd(2+), Zn(2+) and As(3+) seemed to induce a similar pattern for the cytokine responses, and with some exceptions, via similar signalling mechanisms.

Allergen-Experienced Group 2 Innate Lymphoid Cells Acquire Memory-like Properties and Enhance Allergic Lung Inflammation

Group 2 innate lymphoid cells (ILC2s) in the lung are stimulated by inhaled allergens. ILC2s do not directly recognize allergens but they are stimulated by cytokines including interleukin (IL)-33 released by damaged epithelium. In response to allergens, lung ILC2s produce T helper 2 cell type cytokines inducing T cell-independent allergic lung inflammation. Here we examined the fate of lung ILC2s upon allergen challenges. ILC2s proliferated and secreted cytokines upon initial stimulation with allergen or IL-33, and this phase was followed by a contraction phase as cytokine production ceased. Some ILC2s persisted long after the resolution of the inflammation as allergen-experienced ILC2s and responded to unrelated allergens more potently than naive ILC2s, mediating severe allergic inflammation. The allergen-experienced ILC2s exhibited a gene expression profile similar to that of memory T cells. The memory-like properties of allergen-experienced ILC2s may explain why asthma patients are often sensitized to multiple allergens.

The IL-33 receptor (ST2) regulates early IL-13 production in fungus-induced allergic airway inflammation

Allergic airway inflammation (AAI) in response to environmental antigens is an increasing medical problem, especially in the Western world. Type 2 interleukins (IL) are central in the pathological response but their importance and cellular source(s) often rely on the particular allergen. Here, we highlight the cellular sources and regulation of the prototypic type 2 cytokine, IL-13, during the establishment of AAI in a fungal infection model using Cryptococcus neoformans. IL-13 reporter mice revealed a rapid onset of IL-13 competence within innate lymphoid cells type 2 (ILC2) and IL-33R(+) T helper (Th) cells. ILC2 showed IL-33-dependent proliferation upon infection and significant IL-13 production. Th cells essentially required IL-33 to become either GATA3(+) or GATA3(+)/Foxp3(+) hybrids. GATA3(+) Th cells almost exclusively contributed to IL-13 production but hybrid GATA3(+)/Foxp3(+) Th cells did not. In addition, alveolar macrophages upregulated the IL-33R and subsequently acquired a phenotype of alternative activation (Ym1(+), FIZZ1(+), and arginase-1(+)) linked to type 2 immunity. Absence of adaptive immunity in rag2(-/-) mice resulted in attenuated AAI, revealing the need for Th2 cells for full AAI development. Taken together, in pulmonary cryptococcosis ILC2 and GATA3(+) Th2 cells produce early IL-13 largely IL-33R-dependent, thereby promoting goblet cell metaplasia, pulmonary eosinophilia, and alternative activation of alveolar macrophages.

Neuroimmunology of the Interleukins 13 and 4

The cytokines interleukin 13 and 4 share a common heterodimeric receptor and are important modulators of peripheral allergic reactions. Produced primarily by T-helper type 2 lymphocytes, they are typically considered as anti-inflammatory cytokines because they can downregulate the synthesis of T-helper type 1 pro-inflammatory cytokines. Their presence and role in the brain is only beginning to be investigated and the data collected so far shows that these molecules can be produced by microglial cells and possibly by neurons. Attention has so far been given to the possible role of these molecules in neurodegeneration. Both neuroprotective or neurotoxic effects have been proposed based on evidence that interleukin 13 and 4 can reduce inflammation by promoting the M2 microglia phenotype and contributing to the death of microglia M1 phenotype, or by potentiating the effects of oxidative stress on neurons during neuro-inflammation. Remarkably, the heterodimeric subunit IL-13Rα1 of their common receptor was recently demonstrated in dopaminergic neurons of the ventral tegmental area and the substantia nigra pars compacta, suggesting the possibility that both cytokines may affect the activity of these neurons regulating reward, mood, and motor coordination. In mice and man, the gene encoding for IL-13Rα1 is expressed on the X chromosome within the PARK12 region of susceptibility to Parkinson’s disease (PD). This, together with finding that IL-13Rα1 contributes to loss of dopaminergic neurons during inflammation, indicates the possibility that these cytokines may contribute to the etiology or the progression of PD.

Phytochemical profiles and inhibitory effects of Tiger Milk mushroom (Lignosus rhinocerus) extract on ovalbumin-induced airway inflammation in a rodent model of asthma

Background

Lignosus rhinocerus (L. rhinocerus), which is known locally as Tiger Milk mushroom, is traditionally used in the treatment of asthma by indigenous communities in Malaysia. However, to date, its efficacy on asthma has not been confirmed by scientific studies and there is also sparse information available on its active constituents. In this study, the volatile constituent of L. rhinocerus hot water extract was investigated using gas chromatography mass spectrometry (GC-MS). The potential effects of L. rhinocerus extract for anti-asthmatic activity was further investigated on ovalbumin (OVA)-sensitized asthmatic Sprague Dawley rats.

Methods

Sequential extraction using five solvents (petroleum ether, diethyl ether, hexane, ethyl acetate and methanol) was conducted prior to GC-MS analysis. Male Sprague Dawley rats were divided into the following four groups of five animals each: 1) normal rats, 2) sensitization plus OVA-challenged rats 3) sensitization plus OVA-challenged with L. rhinocerus treatment and 4) sensitization plus OVA-challenged with dexamethasone treatment. The levels of immunoglobulin E (IgE) in the serum and T-helper 2 cytokines, including interleukin (IL)-4, IL-5 and IL-13, in bronchoalveolar lavage fluid (BALF), as well as eosinophil infiltration in the lungs, were investigated.

Results

GC-MS analysis revealed the presence of five main groups (alkane, fatty acids, benzene, phenol and dicarboxylic acid) with a total of 18 constituents. Linoleic acid (21.35 %), octadecane (11.82 %) and 2,3-dihydroxypropyl elaidate (10.47 %) were present in high amounts. The extract significantly ameliorated the increase in total IgE in serum and IL-4, IL-5 and IL-13 levels in BALF and also effectively suppressed eosinophils numbers in BALF while attenuating eosinophil infiltrations in the lungs.

Conclusion

L. rhinocerus hot water extract has the potential to be used as an alternative for the treatment of acute asthma.

Increased mitochondrial arginine metabolism supports bioenergetics in asthma

High levels of arginine metabolizing enzymes, including inducible nitric oxide synthase (iNOS) and arginase (ARG), are typical in asthmatic airway epithelium; however, little is known about the metabolic effects of enhanced arginine flux in asthma. Here, we demonstrated that increased metabolism sustains arginine availability in asthmatic airway epithelium with consequences for bioenergetics and inflammation. Expression of iNOS, ARG2, arginine synthetic enzymes, and mitochondrial respiratory complexes III and IV was elevated in asthmatic lung samples compared with healthy controls. ARG2 overexpression in a human bronchial epithelial cell line accelerated oxidative bioenergetic pathways and suppressed hypoxia-inducible factors (HIFs) and phosphorylation of the signal transducer for atopic Th2 inflammation STAT6 (pSTAT6), both of which are implicated in asthma etiology. Arg2-deficient mice had lower mitochondrial membrane potential and greater HIF-2α than WT animals. In an allergen-induced asthma model, mice lacking Arg2 had greater Th2 inflammation than WT mice, as indicated by higher levels of pSTAT6, IL-13, IL-17, eotaxin, and eosinophils and more mucus metaplasia. Bone marrow transplants from Arg2-deficient mice did not affect airway inflammation in recipient mice, supporting resident lung cells as the drivers of elevated Th2 inflammation. These data demonstrate that arginine flux preserves cellular respiration and suppresses pathological signaling events that promote inflammation in asthma.

Gene Expression Analysis in Sinonasal Polyposis before and after Oral Corticosteroids: A Preliminary Investigation

OBJECTIVE: To characterize gene expression in sinonasal polyps and to gain insight into change in expression after oral corticosteroid treatment.

STUDY DESIGN AND METHODS: Nasal polyps were obtained before and after oral corticosteroid treatment and gene expression was analyzed with a focused gene array technique.

RESULTS: Pretreated sinonasal polyps demonstrated high gene expression for chemokine and leukotriene receptor genes (CCR2, CCR5, CX3CL1, and LTB4R) in all patients. After treatment, the global effects of corticosteroids were evident on gene expression.

CONCLUSIONS: Gene array techniques hold promise as a research method in sinonasal polyposis. The potential benefits, as well as the potential challenges, in using these research methods will be discussed.

Distal airways are protected from goblet cell metaplasia by diminished expression of IL-13 signalling components

BACKGROUND

Increased mucus production is a critical factor impairing lung function in patients suffering from bronchial asthma, the most common chronic inflammatory lung disease worldwide.

OBJECTIVE

This study aimed at investigating whether goblet cell (GC) metaplasia and mucus production are differentially regulated in proximal and distal airways.

METHODS

Female Balb/c mice were sensitized to ovalbumin (OVA) and challenged with an OVA-aerosol on two consecutive days for 1 week (acute) or 12 weeks (chronic). Real-time RT-PCR analysis was applied on microdissected airways.

RESULTS

In acutely and chronically OVA-challenged mice, GC metaplasia and mucus production were observed in proximal but not in distal airways. In contrast, inflammation reflected by the infiltration of eosinophils and expression of the TH2-type cytokines IL-4 and IL-13 was increased in both proximal and distal airways. Abundance of IL-13Rα1 was lower in distal airways of healthy control mice. Under acute and chronic OVA-exposure, activation of IL-13Rα1-dependent signalling cascade, reflected by Spdef and Foxo3A transcription factors, was attenuated in distal compared to proximal airways.

CONCLUSION AND CLINICAL RELEVANCE

These data indicate that distal airways might be less sensitive to IL-13-induced GC metaplasia and mucus production through lower expression of IL-13Rα1 and attenuated activation of downstream signalling. This might represent a protective strategy to prevent mucus plugging of distal airways and thus impaired ventilation of attached alveoli.

A semisynthetic diterpenoid lactone inhibits NF-κB signalling to ameliorate inflammation and airway hyperresponsiveness in a mouse asthma model

Andrographolide (AGP) and 14-deoxy-11,12-didehydroandrographolide (DDAG), two main diterpenoid constituents of Andrographis paniculata were previously shown to ameliorate asthmatic symptoms in a mouse model. However, due to inadequacies of both compounds in terms of drug-likeness, DDAG analogues were semisynthesised for assessment of their anti-asthma activity. A selected analogue, 3,19-diacetyl-14-deoxy-11,12-didehydroandrographolide (SRS27), was tested for inhibitory activity of NF-κB activation in TNF-α-induced A549 cells and was subsequently evaluated in a mouse model of ovalbumin (OVA)-induced asthma. Female BALB/c mice, 6-8weeks old were sensitized on days 0 and 14, and challenged on days 22, 23 and 24 with OVA. Compound or vehicle (3% dimethyl sulfoxide) was administered intraperitoneally 1h before and 11h after each OVA aerosol challenge. On day 25, pulmonary eosinophilia, airway hyperresponsiveness, mucus hypersecretion, inflammatory cytokines such as IL-4, -5 and -13 in BAL fluid, gene expression of inflammatory mediators such as 5-LOX, E-selectin, VCAM-1, CCL5, TNF-α, AMCase, Ym2, YKL-40, Muc5ac, CCL2 and iNOS in animal lung tissues, and serum IgE were determined. SRS27 at 30μM was found to suppress NF-κB nuclear translocation in A549 cells. In the ovalbumin-induced mouse asthma model, SRS27 at 3mg/kg displayed a substantial decrease in pulmonary eosinophilia, BAL fluid inflammatory cytokines level, serum IgE production, mucus hypersecretion and gene expression of inflammatory mediators in lung tissues. SRS27 is the first known DDAG analogue effective in ameliorating inflammation and airway hyperresponsiveness in the ovalbumin-induced mouse asthma model.

Role of mast cells in fibrosis of classical Hodgkin lymphoma

The underlying mechanism of fibrosis in classical Hodgkin lymphoma (CHL) remains uncertain. This study aimed to investigate the association of fibrosis in the lymph nodes of patients with CHL through histological examination of the expression of cytokines associated with fibrosis and mast cell proliferation. Additionally, we sought to determine the degree of mast cell infiltration in a nodular sclerosis subtype of CHL (NSCHL) compared with that in non-NSCHL. We analyzed lymph nodes from 22 patients with CHL, of which eight were of the NSCHL and 14 of the non-NSCHL subtype, using immunohistochemical staining of forkhead box P3 (FOXP3), transforming growth factor (TGF)-β, interleukin (IL)-3, IL-13, and stem cell factor (SCF). Mast cells were positive for TGF-β and IL-13, and FOXP3-positive cells were negative for TGF-β. Only the expression of IL-13 in Hodgkin and Reed-Sternberg (HRS) cells was significantly more frequently observed in NSCHL than that in non-NSCHL (P = 0.0028) and was associated with a higher rate of fibrosis (P = 0.0097). The number of mast cells was significantly higher in NSCHL than that in non-NSCHL (P = 0.0001). A significantly positive correlation was observed between the rate of fibrosis and the number of mast cells (correlation coefficient, 0.8524; 95% CI, 0.6725-0.9372) (P <0.0001). The number of mast cells was significantly higher in the group with IL-13-positive HRS cells than that in the group with IL-13-negative HRS cells (P = 0.0157). Based on these findings, we hypothesize that IL-13 production by HRS cells may lead to fibrosis, and furthermore, promote mast cell proliferation and infiltration. This in turn might further produce the fibrotic cytokines IL-13 and TGF-β, resulting in fibrosis typical of NSCHL.

NFATc1 deletion in T lymphocytes inhibits the allergic trait in a murine model of asthma

BACKGROUND

NFATc1 isoforms are highly regulated in peripheral T cells where they contribute to the effector function and cell homeostasis.

OBJECTIVE

Here, we investigated the role of NFATc1 in asthma and in T cells.

METHODS

In a murine model of allergic asthma, we analysed differences in T-cell development in this allergic disease model, between wild-type and NFATc1 conditional knockout mice. Thus, we performed quantitative real-time PCR to investigate the mRNA expression of Th2-associated genes as well as genes that are involved in IgE immunoglobulin class-switch. Additionally, we used ELISA, Western blot and flow cytometry (FACS) to analyse protein concentrations of Th1-, Th2- and Th17-specific transcription factors and cytokines and the Th2 chemokine, thymus and activation-regulated chemokine/chemokine ligand 17 (TARC/CCL17) by ELISA.

RESULTS

Mice lacking NFATc1 in CD4(+) T cells display a significant reduction in lung Th2 and Th17 as well as an increase of Th1 cells in an experimental asthma model. Additionally, Batf gene, a recently described transcription factor of the Th2 and Th17 cell differentiation as well as a key T and B transcription factor involved in the IgE immunoglobulin class-switch, was found decreased in the lungs of these mice. As a consequence, serum OVA-specific IgE and IgG1 levels were found significantly decreased after allergen exposure and in the absence of NFATc1 in T cells in experimental allergic asthma.

CONCLUSIONS AND CLINICAL RELEVANCE

Targeting NFATc1 in T lymphocytes ameliorated the allergic trait in the airways of NFATc1(fl/fl) xCD4Cre mice. NFATc1 emerges as a novel target for anti-allergy intervention.

Does epigenetics play a role in human asthma?

Asthma and other allergic diseases are among the most prevalent chronic non-communicable diseases of childhood. According to the World Health Organization, asthma affects >7.0 million children under 18 in the United States, with an economic burden that is estimated to exceed that of tuberculosis and HIV/AIDS combined. Despite much research, the natural history of asthma and its pathogenesis are still in many ways elusive. This review discusses our current understanding of the role epigenetic processes play in asthma pathogenesis, focusing on genome-wide, population-based studies.

CD4+ T-cell subsets in inflammatory diseases: beyond the Th1/Th2 paradigm

CD4(+)T cells are crucial for directing appropriate immune responses during host defense and for the pathogenesis of inflammatory diseases. In addition to the classical biphasic model of differentiation of T-helper 1 (Th1) and Th2 cells, unexpected increases in the numbers of CD4(+)T-cell subsets, including Th17, Th9, T follicular-helper (Tfh) and T-regulatory (Treg) cells, have been recognized. In the present review, we focus on how these various T-helper cell subsets contribute to the pathogenesis of immune-mediated inflammatory diseases. In particular, we focus on multiple sclerosis, psoriasis and asthma as typical model diseases in which multiple T-helper cell subsets have recently been suggested to play a role. We will also discuss various unique sub-populations of T-helper cells that have been identified. First, we will introduce the heterogeneous T-helper cell subsets, which are classified by their simultaneous expression of multiple key transcription factors. We will also introduce different kinds of memory-type Th2 cells, which are involved in the pathogenesis of chronic type-2 immune-related diseases. Finally, we will discuss the molecular mechanisms underlying the generation of the plasticity and heterogeneity of T-helper cell subsets. The latest progress in the study of T-helper cell subsets has forced us to reconsider the etiology of immune-mediated inflammatory diseases beyond the model based on the Th1/Th2 balance. To this end, we propose another model--the pathogenic T-helper population disease-induction model--as a possible mechanism for the induction and/or persistence of immune-mediated inflammatory diseases.

Inhibitory effect of Zanthoxylum bungeanum seed oil on ovalbumin‑induced lung inflammation in a murine model of asthma

The present study aimed to investigate the therapeutic efficacy of Zanthoxylum bungeanum seed oil (Z. seed oil) to alleviate airway inflammation in asthmatic mice. The asthmatic mice were treated with vehicle, ovalbumin (OVA), or OVA + Z. seed oil (2 g/kg) for between 24 h and 14 days. Following treatment, inflammatory cell infiltration and pulmonary tissue damage were assessed by hematoxylin and eosin staining, and immunohistochemistry. The expression levels of pro‑inflammatory cytokines, chemokines, adhesion molecules and mitogen activated protein kinase signaling proteins were measured by enzyme‑linked immunosorbent assays, reverse transcription quantitative‑polymerase chain reaction and western blot analysis. In asthmatic mice, administration of Z. seed oil attenuated lung tissue injury and airway remodeling, and inhibited the infiltration of leukocytes and eosinophils into the airway by reducing the expression levels of inflammatory cytokines and chemokines compared with OVA‑treated mice (P<0.05). Z. seed oil also reduced the levels of inflammatory chemokine and adhesion molecules via downregulation of extracellular signal‑regulated kinase and activation of c‑JUN N‑terminal kinase in the Z. seed‑treated mice compared with OVA‑treated mice (P<0.05). Thus, data from the present study indicates that Z. seed oil can suppress pulmonary inflammation and tissue injury during asthma, and suggests that it may be used to effectively treat allergen‑induced asthma.

An Interleukin 13 Polymorphism Is Associated with Symptom Severity in Adult Subjects with Ever Asthma

Different genes are associated with categorical classifications of asthma severity. However, continuous outcomes should be used to catch the heterogeneity of asthma phenotypes and to increase the power in association studies. Accordingly, the aim of this study was to evaluate the association between single nucleotide polymorphisms (SNPs) in candidate gene regions and continuous measures of asthma severity, in adult patients from the general population. In the Gene Environment Interactions in Respiratory Diseases (GEIRD) study (www.geird.org), 326 subjects (aged 20–64) with ever asthma were identified from the general population in Verona (Italy) between 2007 and 2010. A panel of 236 SNPs tagging 51 candidate gene regions (including one or more genes) was analysed. A symptom and treatment score (STS) and pre-bronchodilator FEV₁% predicted were used as continuous measures of asthma severity. The association of each SNP with STS and FEV₁% predicted was tested by fitting quasi-gamma and linear regression models, respectively, with gender, body mass index and smoking habits as potential confounders. The Simes multiple-test procedure was used for controlling the false discovery rate (FDR). SNP rs848 in the IL13 gene region (IL5/RAD50/IL13/IL4) was associated with STS (TG/GG vs TT genotype: uncorrected p-value = 0.00006, FDR-corrected p-value = 0.04), whereas rs20541 in the same gene region, in linkage disequilibrium with rs848 (r² = 0.94) in our sample, did not reach the statistical significance after adjusting for multiple testing (TC/CC vs TT: uncorrected p-value = 0.0003, FDR-corrected p-value = 0.09). Polymorphisms in other gene regions showed a non-significant moderate association with STS (IL12B, TNS1) or lung function (SERPINE2, GATA3, IL5, NPNT, FAM13A) only. After adjusting for multiple testing and potential confounders, SNP rs848 in the IL13 gene region is significantly associated with a continuous measure of symptom severity in adult subjects with ever asthma.

Intranasal Administration of Recombinant Mycobacterium smegmatis Inducing IL-17A Autoantibody Attenuates Airway Inflammation in a Murine Model of Allergic Asthma

Asthma is a chronic inflammatory disorder, previous studies have shown that IL-17A contributes to the development of asthma, and there is a positive correlation between the level of IL-17A and the severity of disease. Here, we constructed recombinant Mycobacterium smegmatis expressing fusion protein Ag85A-IL-17A (rMS-Ag85a-IL-17a) and evaluated whether it could attenuate allergic airway inflammation, and further investigated the underlying mechanism. In this work, the murine model of asthma was established with ovalbumin, and mice were intranasally vaccinated with rMS-Ag85a-IL-17a. Autoantibody of IL-17A in sera was detected, and the airway inflammatory cells infiltration, the local cytokines and chemokines production and the histopathological changes of lung tissue were investigated. We found that the administration of rMS-Ag85a-IL-17a induced the autoantibody of IL-17A in sera. The vaccination of rMS-Ag85a-IL-17a remarkably reduced the infiltration of inflammatory cells and the secretion of mucus in lung tissue and significantly decreased the numbers of the total cells, eosinophils and neutrophils in BALF. Th1 cells count in spleen, Th1 cytokine levels in BALF and supernatant of splenocytes and mediastinal lymph nodes, and T-bet mRNA in lung tissue were significantly increased with rMS-Ag85a-IL-17a administration. Meanwhile, rMS-Ag85a-IL-17a vaccination markedly decreased Th2 cells count, Th2 cytokine and Th17 cytokine levels in BALF and supernatant of splenocytes and mediastinal lymph nodes, and chemokines mRNA expression in lung tissue. These data confirmed that recombinant Mycobacterium smegmatis in vivo could induce autoantibody of IL-17A, which attenuated asthmatic airway inflammation.

Type 2 innate lymphoid cells: at the cross-roads in allergic asthma

Allergic asthma is a chronic inflammatory disease of the lower airways that affects millions of people worldwide. Allergic asthma is a T helper 2 cell (Th2)-mediated disease, in which Th2 cytokines interleukin (IL)-4, IL-5, and IL-13 are closely associated with the symptoms. IL-4 is needed by B cells to switch toward an IgE response, IL-5 recruits and activates eosinophils while IL-13 increases mucus production. The identification of type 2 innate lymphoid cells (ILC2), which are able to rapidly produce large amounts of IL-5 and IL-13 in response to epithelial derived cytokines, implicated a new key player besides Th2 cells. ILCs constitute a family of innate lymphocytes distinct from T and B cells. ILC2s are located in various epithelial compartments in mice and human, including the lung. The recent finding of increased numbers of ILC2s in the airways of severe asthma patients prompts further research to clarify their immunological function. Murine studies have shown that ILC2s are an early innate source of IL-5 and IL-13 after allergen exposure, which induce airway eosinophilic infiltration, mucus hyperproduction, and airway hyperresponsiveness but not allergen-specific IgE production. ILC2s contribute to the initiation as well as to the maintenance of the adaptive type 2 immune response. Here, we review the recent progress on our understanding of the role of ILC2s in the immunopathology of allergic asthma, in particular by studies using murine models which have elucidated fundamental mechanisms by which ILC2s act.

Differential gene network analysis for the identification of asthma-associated therapeutic targets in allergen-specific T-helper memory responses

BACKGROUND

Asthma is strongly associated with allergic sensitization, but the mechanisms that determine why only a subset of atopics develop asthma are not well understood. The aim of this study was to test the hypothesis that variations in allergen-driven CD4 T cell responses are associated with susceptibility to expression of asthma symptoms.

METHODS

The study population consisted of house dust mite (HDM) sensitized atopics with current asthma (n = 22), HDM-sensitized atopics without current asthma (n = 26), and HDM-nonsensitized controls (n = 24). Peripheral blood mononuclear cells from these groups were cultured in the presence or absence of HDM extract for 24 h. CD4 T cells were then isolated by immunomagnetic separation, and gene expression patterns were profiled on microarrays.

RESULTS

Differential network analysis of HDM-induced CD4 T cell responses in sensitized atopics with or without asthma unveiled a cohort of asthma-associated genes that escaped detection by more conventional data analysis techniques. These asthma-associated genes were enriched for targets of STAT6 signaling, and they were nested within a larger coexpression module comprising 406 genes. Upstream regulator analysis suggested that this module was driven primarily by IL-2, IL-4, and TNF signaling; reconstruction of the wiring diagram of the module revealed a series of hub genes involved in inflammation (IL-1B, NFkB, STAT1, STAT3), apoptosis (BCL2, MYC), and regulatory T cells (IL-2Ra, FoxP3). Finally, we identified several negative regulators of asthmatic CD4 T cell responses to allergens (e.g. IL-10, type I interferons, microRNAs, drugs, metabolites), and these represent logical candidates for therapeutic intervention.

CONCLUSION

Differential network analysis of allergen-induced CD4 T cell responses can unmask covert disease-associated genes and pin point novel therapeutic targets.

Genome-Wide Methylation Study Identifies an IL-13-induced Epigenetic Signature in Asthmatic Airways

RATIONALE

Epigenetic changes to airway cells have been proposed as important modulators of the effects of environmental exposures on airway diseases, yet no study to date has shown epigenetic responses to exposures in the airway that correlate with disease state. The type 2 cytokine IL-13 is a key mediator of allergic airway diseases, such as asthma, and is up-regulated in response to many asthma-promoting exposures.

OBJECTIVES

To directly study the epigenetic response of airway epithelial cells (AECs) to IL-13 and test whether IL-13-induced epigenetic changes differ between individuals with and without asthma.

METHODS

Genome-wide DNA methylation and gene expression patterns were studied in 58 IL-13-treated and untreated primary AEC cultures and validated in freshly isolated cells of subjects with and without asthma using the Illumina Human Methylation 450K and HumanHT-12 BeadChips. IL-13-mediated comethylation modules were identified and correlated with clinical phenotypes using weighted gene coexpression network analysis.

MEASUREMENTS AND MAIN RESULTS

IL-13 altered global DNA methylation patterns in cultured AECs and were significantly enriched near genes associated with asthma. Importantly, a significant proportion of this IL-13 epigenetic signature was validated in freshly isolated AECs from subjects with asthma and clustered into two distinct modules, with module 1 correlated with asthma severity and lung function and module 2 with eosinophilia.

CONCLUSIONS

These results suggest that a single exposure of IL-13 may selectively induce long-lasting DNA methylation changes in asthmatic airways that alter specific AEC pathways and contribute to asthma phenotypes.

Petatewalide B, a novel compound from Petasites japonicus with anti-allergic activity

ETHNOPHARMACOLOGICAL RELEVANCE

The giant butterbur Petasites japonicus is used to treat asthma and allergic diseases in traditional Korean, Japanese, and Chinese medicine.

AIM OF THE STUDY

To elucidate the anti-allergic effect of Petasites genus, we studied effects of several compounds from Petasites japonicus leaves and found a novel bakkenolide-type sesquiterpine. In the present study, anti-allergic and anti-inflammatory effects of the new compound was examined using in vivo and in vitro experiments.

MATERIALS AND METHODS

The novel compound was isolated from Petasites japonicus leaves and named petatewalide B. Antigen-induced degranulation and Ca(2+) mobilization were measured in RBL-2H3 mast cells by measuring β-hexosaminidase activity and fluorescence change of Ca(2+) probe, fura-2. Induction of inducible nitric oxide synthase and cyclooxygenase 2 was measured by Western blotting in peritoneal macrophages. In addition, ovalbumin-induced asthma model was used for in vivo efficacy test of petatewalide B. Membrane potential was estimated by measuring fluorescence change of DiBAC in C6 glioma cells.

RESULTS

Petatewalide B inhibited the antigen-induced degranulation of β-hexosaminidase in RBL-2H3 mast cells, but did not affect antigen-induced Ca(2+) increase in the cells. Petatewalide B also showed inhibition of the LPS-induced induction of iNOS, but not COX-2 in mouse peritoneal macrophages. Nitric oxide production was also inhibited by petatewalide B in macrophages. In the ovalbumin-induced asthma model, petatewalide B strongly inhibited accumulations of eosinophils, macrophages, and lymphocytes in bronchoalveolar lavage fluid. Petatewalide B increased the membrane potential of C6 glioma cells in a concentration-dependent manner.

CONCLUSION

Petatewalide B from Petasites genus not only has anti-allergic and anti-inflammatory effects but also induces a transient increase of membrane potential in C6 glioma cells.

Group 2 innate lymphoid cells license dendritic cells to potentiate memory TH2 cell responses

Rapid activation of memory CD4(+) T helper 2 (TH2) cells during allergic inflammation requires their recruitment into the affected tissue. Here we demonstrate that group 2 innate lymphoid (ILC2) cells have a crucial role in memory TH2 cell responses, with targeted depletion of ILC2 cells profoundly impairing TH2 cell localization to the lungs and skin of sensitized mice after allergen re-challenge. ILC2-derived interleukin 13 (IL-13) is critical for eliciting production of the TH2 cell-attracting chemokine CCL17 by IRF4(+)CD11b(+)CD103(-) dendritic cells (DCs). Consequently, the sentinel function of DCs is contingent on ILC2 cells for the generation of an efficient memory TH2 cell response. These results elucidate a key innate mechanism in the regulation of the immune memory response to allergens.

Targeted anti-inflammatory therapeutics in asthma and chronic obstructive lung disease

Asthma and chronic obstructive pulmonary disease (COPD) are chronic inflammatory diseases of the airway, although the drivers and site of the inflammation differ between diseases. Asthmatics with a neutrophilic airway inflammation are associated with a poor response to corticosteroids, whereas asthmatics with eosinophilic inflammation respond better to corticosteroids. Biologicals targeting the Th2-eosinophil nexus such as anti-interleukin (IL)-4, anti-IL-5, and anti-IL-13 are ineffective in asthma as a whole but are more effective if patients are selected using cellular (eg, eosinophils) or molecular (eg, periostin) biomarkers. This highlights the key role of individual inflammatory mediators in driving the inflammatory response and for accurate disease phenotyping to allow greater understanding of disease and development of patient-oriented antiasthma therapies. In contrast to asthmatic patients, corticosteroids are relatively ineffective in COPD patients. Despite stratification of COPD patients, the results of targeted therapy have proved disappointing with the exception of recent studies using CXC chemokine receptor (CXCR)2 antagonists. Currently, several other novel mediator-targeted drugs are undergoing clinical trials. As with asthma specifically targeted treatments may be of most benefit in specific COPD patient endotypes. The use of novel inflammatory mediator-targeted therapeutic agents in selected patients with asthma or COPD and the detection of markers of responsiveness or nonresponsiveness will allow a link between clinical phenotypes and pathophysiological mechanisms to be delineated reaching the goal of endotyping patients.

The control of tissue fibrosis by the inflammatory molecule LIGHT (TNF Superfamily member 14)

The TNF Superfamily member LIGHT (TNFSF14) has recently emerged as a potential target for therapeutic interventions aiming to halt tissue fibrosis. In this perspective, we discuss how LIGHT may influence the inflammatory and remodeling steps that characterize fibrosis, relevant for many human diseases presenting with scarring such as asthma, idiopathic pulmonary fibrosis, systemic sclerosis, and atopic dermatitis. LIGHT acts through two receptors in the TNF receptor superfamily, HVEM (TNFRSF14) and LTβR (TNFRSF3), which are broadly expressed on hematopoietic and non-hematopoietic cells. LIGHT can regulate infiltrating T cells, macrophages, and eosinophils, controlling their trafficking or retention in the inflamed tissue, their proliferation, and their ability to produce cytokines that amplify fibrotic processes. More interestingly, LIGHT can act on structural cells, namely epithelial cells, fibroblasts, smooth muscle cells, adipocytes, and endothelial cells. By signaling through either HVEM or LTβR expressed on these cells, LIGHT can contribute to their proliferation and expression of chemokines, growth factors, and metalloproteinases. This will lead to hyperplasia of epithelial cells, fibroblasts, and smooth muscle cells, deposition of extracellular matrix proteins, vascular damage, and further immune alterations that in concert constitute fibrosis. Because of its early expression by T cells, LIGHT may be an initiator of fibrotic diseases, but other sources in the immune system could also signify a role for LIGHT in maintaining or perpetuating fibrotic activity. LIGHT may then be an attractive prognostic marker as well as an appealing target for fibrosis therapies relevant to humans.

Biologics in asthma--the next step toward personalized treatment

Asthma is a multifaceted disease and is associated with significant impairment and risk, and a therapeutic response that is highly variable. Although current treatments are usually effective for patients with mild-to-moderate disease, patients with more severe asthma are often unresponsive to current efforts, and there remains a need for agents with properties that may achieve control in these individuals. There is ongoing research to identify bioactive molecules that contribute to the pathophysiology of asthma, and many of these have been identified as potential therapeutic targets to improve control of this disease. As a consequence of these efforts, monoclonal antibodies have been developed and tested as to their effectiveness in the treatment of asthma. The assessment of these new treatments has identified particular pathways that, in selected patients, have shown benefit. The following review will discuss the current and future use of biological agents for the treatment of asthma, their efficacy, and how certain patient phenotypes and endotypes may be associated with biomarkers that may be used to select treatments to achieve greatest effectiveness of their use. As knowledge of the effects of these biological agents in asthma emerges, as well as the patients in whom they are most beneficial, the movement toward personalized treatment will follow.

Instructive roles for cytokine-receptor binding parameters in determining signaling and functional potency

Cytokines dimerize cell surface receptors to activate signaling and regulate many facets of the immune response. Many cytokines have pleiotropic effects, inducing a spectrum of redundant and distinct effects on different cell types. This pleiotropy has hampered cytokine-based therapies, and the high doses required for treatment often lead to off-target effects, highlighting the need for a more detailed understanding of the parameters controlling cytokine-induced signaling and bioactivities. Using the prototypical cytokine interleukin-13 (IL-13), we explored the interrelationships between receptor binding and a wide range of downstream cellular responses. We applied structure-based engineering to generate IL-13 variants that covered a spectrum of binding strengths for the receptor subunit IL-13Rα1. Engineered IL-13 variants representing a broad range of affinities for the receptor exhibited similar potencies in stimulating the phosphorylation of STAT6 (signal transducer and activator of transcription 6). Delays in the phosphorylation and nuclear translocation of STAT6 were only apparent for those IL-13 variants with markedly reduced affinities for the receptor. From these data, we developed a mechanistic model that quantitatively reproduced the kinetics of STAT6 phosphorylation for the entire spectrum of binding affinities. Receptor endocytosis played a key role in modulating STAT6 activation, whereas the lifetime of receptor-ligand complexes at the plasma membrane determined the potency of the variant for inducing more distal responses. This complex interrelationship between extracellular ligand binding and receptor function provides the foundation for new mechanism-based strategies that determine the optimal cytokine dose to enhance therapeutic efficacy.

Alterations in DNA methylation and airway hyperreactivity in response to in utero exposure to environmental tobacco smoke

Growing evidence indicates that prenatal exposure to maternal smoking is a risk factor for the development of asthma in children. However, the effects of prenatal environmental tobacco smoke (ETS) exposure on the genome and lung immune cells are unclear. This study aims to determine whether in utero ETS exposure alters DNA methylation patterns and increases airway hyperreactivity (AHR) and inflammation. Pregnant C57BL/6 mice were exposed daily to a concentration of 1.0 mg/m(3) ETS. AHR was determined in the 6-week-old offspring by measurement of airway resistance. Global and gene promoter methylation levels in lung DNA from offspring were analyzed by luminometric methylation and pyrosequencing assays, respectively. Offspring exposed to ETS showed a marked increase in the number of alveolar macrophages in the bronchoalveolar lavage fluid and level of IL-13 in the airways compared with offspring of filtered-air exposed dams (controls). ETS exposure significantly augmented AHR compared with controls. In the methylation analysis, ETS-exposed offspring had a significantly lower level of global DNA methylation than the controls. We observed a significant increase in IFN-γ, and significant decrease in IL-13 methylation levels in the ETS group compared with controls. Collectively, these data suggest that in utero ETS exposure increases the risk of pulmonary inflammation and AHR through altered DNA methylation, but additional studies are needed to fully determine the causal link between changes in methylation and cytokines levels, as well as AHR.

Critical role of actin-associated proteins in smooth muscle contraction, cell proliferation, airway hyperresponsiveness and airway remodeling

Asthma is characterized by airway hyperresponsiveness and airway remodeling, which are largely attributed to increased airway smooth muscle contractility and cell proliferation. It is known that both chemical and mechanical stimulation regulates smooth muscle contraction. Recent studies suggest that contractile activation and mechanical stretch induce actin cytoskeletal remodeling in smooth muscle. However, the mechanisms that control actin cytoskeletal reorganization are not completely elucidated. This review summarizes our current understanding regarding how actin-associated proteins may regulate remodeling of the actin cytoskeleton in airway smooth muscle. In particular, there is accumulating evidence to suggest that Abelson tyrosine kinase (Abl) plays a critical role in regulating airway smooth muscle contraction and cell proliferation in vitro, and airway hyperresponsiveness and remodeling in vivo. These studies indicate that Abl may be a novel target for the development of new therapy to treat asthma.

Anti-allergic effect of α-cubebenoate isolated from Schisandra chinensis using in vivo and in vitro experiments

AIM OF THE STUDY

In Oriental countries, the dried fruits of Schisandra chinensis are extensively used in traditional medicine to treat asthma, gonorrhea, and other diseases. Recently, α-cubebenoate was isolated as an anti-inflammatory component from Schisandra chinensis. In the present study, the authors examined the anti-allergic effect of α-cubebenoate using in vivo and in vitro experiments.

MATERIALS AND METHODS

α-Cubebenoate was isolated from an extract of Schisandra chinensis fruits. Antigen-induced degranulation and Ca(2+) mobilization were measured in RBL-2H3 mast cells. In addition, BALB/c mice were sensitized with ovalbumin and aluminum hydroxide, and then challenged with ovalbumin for three consecutive days. α-Cubebenoate (1mg/kg) was administered intraperitoneally 30min before each ovalbumin challenge.

RESULTS

In RBL-2H3 mast cells, α-cubebenoate inhibited antigen-induced degranulation and increase of intracellular Ca(2+) concentrations. In the ovalbumin-induced asthma model, α-cubebenoate suppressed bronchiolar structural changes induced by ovalbumin challenge. Furthermore, α-cubebenoate strongly inhibited accumulations of eosinophils, macrophages, and lymphocytes in bronchoalveolar lavage fluid. α-Cubebenoate also suppressed Th2 cytokines (IL-4 and IL-13) and TGF-β1 in lung tissues and in immune cells at the mRNA and protein levels.

CONCLUSION

α-Cubebenoate has an inhibitory effect on allergic inflammation and could be utilized as an agent for the treatment of asthma.

Dynamics of IL-4 and IL-13 expression in the airways of sheep following allergen challenge

Background

IL-4 and IL-13 play a critical yet poorly understood role in orchestrating the recruitment and activation of effector cells of the asthmatic response and driving the pathophysiology of allergic asthma. The house dust mite (HDM) sheep asthma model displays many features of the human condition and is an ideal model to further elucidate the involvement of these critical Th₂ cytokines. We hypothesized that airway exposure to HDM allergen would induce or elevate the expression profile of IL-4 and IL-13 during the allergic airway response in this large animal model of asthma.

Methods

Bronchoalveolar lavage (BAL) samples were collected from saline- and house dust mite (HDM)- challenged lung lobes of sensitized sheep from 0 to 48 h post-challenge. BAL cytokines (IL-4, IL-13, IL-6, IL-10, TNF-α) were each measured by ELISA. IL-4 and IL-13 expression was assessed in BAL leukocytes by flow cytometry and in airway tissue sections by immunohistology.

Results

IL-4 and IL-13 were increased in BAL samples following airway allergen challenge. HDM challenge resulted in a significant increase in BAL IL-4 levels at 4 h compared to saline-challenged airways, while BAL IL-13 levels were elevated at all time-points after allergen challenge. IL-6 levels were maintained following HDM challenge but declined after saline challenge, while HDM administration resulted in an acute elevation in IL-10 at 4 h but no change in TNF-α levels over time. Lymphocytes were the main early source of IL-4, with IL-4 release by alveolar macrophages (AMs) prominent from 24 h post-allergen challenge. IL-13 producing AMs were increased at 4 and 24 h following HDM compared to saline challenge, and tissue staining provided evidence of IL-13 expression in airway epithelium as well as immune cells in airway tissue.

Conclusion

In a sheep model of allergic asthma, airway inflammation is accompanied by the temporal release of key cytokines following allergen exposure that primarily reflects the Th₂-driven nature of the immune response in asthma. The present study demonstrates for the first time the involvement of IL-4 and IL-13 in a relevant large animal model of allergic airways disease.

The role of CRAC channel in asthma

Asthma is increasing globally and current treatments only manage a proportion of patients. There is an urgent need to develop new therapies. Lymphocytes are thought to play a central role in the pathophysiology of asthma through the production of inflammatory mediators. This is thought to be via the transcription factor NFAT which in turn can be activated through Ca(2+) release-activated Ca(2+) (CRAC) channels. The aim of this work was to investigate the role of CRAC in clinical and pre-clinical models of allergic asthma. Initial data demonstrated that the NFAT pathway is increased in stimulated lymphocytes from asthmatics. To confirm a role for the channel we showed that a selective inhibitor, Synta 66, blocked mediator production from lymphocytes. Synta 66 inhibited CD2/3/28 induced IL-2, IL-7, IL-13 & IFNΥ in a concentration-dependent manner in healthy and severe asthma donors, with over 60% inhibition observed for all cytokines. NFAT pathway was also increased in a pre-clinical asthma model. In this model we have demonstrated that CRAC played a central role in the airway inflammation and late asthmatic response (LAR). In conclusion, our data provides evidence that suggests targeting CRAC channels could be of therapeutic benefit for asthma sufferers.

Association of IL13R alpha 1 +1398A/G polymorphism in a North Indian population with asthma: A case-control study

Background:

Interleukin 13 (IL13) is directly involved in the secretion of total serum immunoglobulin E (IgE), which plays a major role in the asthma pathogenesis.

Objective:

One of the polymorphic receptor of IL13 is IL13Rα1, which after binding to IL13, initiates signal transduction that results in mucin secretion, airway hyperreactivity, fibrosis, and chitinase up-regulation, which increases asthma risk.

Methods:

In the present study, the role of IL13Rα1 +1398A/G gene polymorphisms in asthma was detected with a total of 964 individuals, including 483 healthy controls and 481 asthma patients from a North Indian population using polymerase chain reaction-restriction fragment length polymorphism method.

Results:

Statistical analysis revealed that the mutant allele (G) is predominant in asthma patients (42.7%) than the controls (38.2%), which shows an increased risk toward asthma with odds ratio = 1.21, 95% confidence interval (1.00–1.45), χ² = 4.10 and p = 0.043. Furthermore, the phenotypic characteristics also reveal a significant association with the disease (p < 0.05).

Conclusions:

This is the first study conducted in India and +1398A/G polymorphism in noncoding region of IL13Rα1 confer risk toward asthma in the studied population.

Group 2 innate lymphoid cells in disease

Group 2 innate lymphoid cells (ILC2) are now recognized as an important innate source of type-2 effector cytokines. Although initially associated with mucosal tissues, it is clear that ILC2 are present in diverse anatomical locations. The function of ILC2 at these sites is equally varied, and although ILC2 represent a relatively minor population, they are fundamentally important regulators of innate and adaptive immune processes. As such, there is much interest to understand the role of ILC2 in diseases with a type-2 inflammatory component. This review explores the known roles of ILC2 in disease, and the diseases that show associations or other strong evidence for the involvement of ILC2.

Deciphering Asthma Biomarkers with Protein Profiling Technology

Asthma is a chronic inflammatory disease of the airways, resulting in bronchial hyperresponsiveness with every allergen exposure. It is now clear that asthma is not a single disease, but rather a multifaceted syndrome that results from a variety of biologic mechanisms. Asthma is further problematic given that the disease consists of many variants, each with its own etiologic and pathophysiologic factors, including different cellular responses and inflammatory phenotypes. These facets make the rapid and accurate diagnosis (not to mention treatments) of asthma extremely difficult. Protein biomarkers can serve as powerful detection tools in both clinical and basic research applications. Recent endeavors from biomedical researchers have developed technical platforms, such as cytokine antibody arrays, that have been employed and used to further the global analysis of asthma biomarker studies. In this review, we discuss potential asthma biomarkers involved in the pathophysiologic process and eventual pathogenesis of asthma, how these biomarkers are being utilized, and how further testing methods might help improve the diagnosis and treatment strain that current asthma patients suffer.

Critical role of IL-6 in dendritic cell-induced allergic inflammation of asthma

Interleukin (IL)-6 plays important roles in autoimmunity and inflammation and is essential for T helper (Th) 2 and Th17 differentiation. However, whether it is involved in the development and function of dendritic cells (DCs) during allergen-induced airway inflammation and airway hyper-reactivity (AHR) remains undefined. In this study, Dermatophagoides pteronyssinus (Der p)-induced airway inflammation and AHR were studied in IL-6 knockout (KO) mice. Der p-loaded bone marrow-derived DCs (BMDCs) from IL-6 KO mice were used to assaying their ability to induce airway inflammation in naïve wild-type mice. Our results showed that IL-6 KO mice showed reduced AHR, significant decreases in inflammatory cell recruitment and Th2 and Th17 cytokine production in the airways, and lowered Der p-specific immunoglobulin G1 after Der p exposure. Further exploration of BMDCs from IL-6 KO mice revealed decreased activity of phagocytosis and reduced expression of MHC class II and CD86 after Der p stimulation. Adoptive transfer of Der p-loaded BMDCs from IL-6 KO mice also showed a functional defect in their inability to induce Th2 and Th17 immune responses and trigger airway inflammation and AHR in recipient mice. Finally, in allergic asthmatics, DCs that differentiated from monocytes treated with anti-IL-6 receptor antibody (tocilizumab) had poor capacity for eliciting Th2 polarization as compared to DCs generated from monocytes without antibody treatment. In conclusion, IL-6 signaling in DCs is essential for their uptake of allergens, maturation, and initiation of Th2/Th17-mediated airway inflammation and AHR in asthma, thus providing a new potential target for treating allergic asthma.

KEY MESSAGES

IL-6 signaling is important for DCs to take up allergens and to initiate Th2/Th17-mediated airway inflammation. DCs from allergic asthmatics treated with anti-IL-6 receptor antibody had poor capacity for eliciting Th2 polarization. Anti-IL-6 treatment may provide a new potential target for treating allergic asthma.

Interferon at the crossroads of allergy and viral infections

IFN-α/β was first described as a potent inhibitor of viral replication, but it is now appreciated that IFN signaling plays a pleiotropic role in regulating peripheral T cell functions. Recently, IFN-α/β was shown to block human Th2 development by suppressing the transcription factor GATA3. This effect is consistent with the role for IFN-α/β in suppressing allergic inflammatory processes by blocking granulocyte activation and IL-4-mediated B cell isotype switching to IgE. With the consideration of recent studies demonstrating a defect in IFN-α/β secretion in DCs and epithelial cells from individuals with severe atopic diseases, there is an apparent reciprocal negative regulatory loop in atopic individuals, whereby the lack of IFN-α/β secretion by innate cells contributes to the development of allergic Th2 cells. Is it possible to overcome these events by treating with IFN-α/β or by inducing its secretion in vivo? In support of this approach, case studies have documented the therapeutic potential of IFN-α/β in treating steroid-resistant allergic asthma and other atopic diseases. Additionally, individuals with asthma who are infected with HCV and respond to IFN therapy showed a reduction in symptoms and severity of asthma attacks. These findings support a model, whereby allergic and antiviral responses are able to cross-regulate each other, as IgER cross-linking of pDCs prevents IFN-α/β production in response to viral infection. The clinical importance of upper-respiratory viruses in the context of allergic asthma supports the need to understand how these pathways intersect and to identify potential therapeutic targets.

The effects of corticosteroids on cytokine production from asthma lung lymphocytes

BACKGROUND

Lymphocytes play a central role in the pathophysiology of asthma. Corticosteroids have a limited effect in severe asthma and we hypothesise that lymphocytes play a central role in corticosteroid insensitivity. We investigated the effects of corticosteroids on cytokine production from lung lymphocytes obtained from patients with moderate severe asthma (MSA) compared to mild asthma (MA) and healthy non-smokers (HNS).

METHODS

Bronchoalveolar lavage (BAL) cells obtained by bronchoscopy from patients with MSA and MA (n = 11 and n = 14 respectively) and HNS (n = 7) were stimulated with CD2/3/28 beads to activate the lymphocytes, in the presence or absence of dexamethasone (0.01-1 μM). Supernatants were assayed for IL-2, IFNγ, IL-17, IL-13 and IL-10 production.

RESULTS

Dexamethasone caused variable inhibition of cytokines; 1 μM inhibited IL-10 and IL-17 by 50% or lower, while inhibition > 50% was observed for IL-2, IL-13 and IFNγ. The effect of dexamethasone on IL-13 production was reduced in MSA.

CONCLUSION

These findings suggest that the production of specific lymphocyte derived cytokines is poorly suppressed by corticosteroids in MSA, which may be responsible for persistent airway inflammation in these patients

Nuclear Receptor Nur77 Attenuates Airway Inflammation in Mice by Suppressing NF-κB Activity in Lung Epithelial Cells

Allergic asthma is characterized by persistent chronic airway inflammation, which leads to mucus hypersecretion and airway hyperresponsiveness. Nuclear receptor Nur77 plays a pivotal role in distinct immune and inflammatory cells and is expressed in eosinophils and lung epithelium. However, the role of Nur77 in allergic airway inflammation has not been studied so far. In the present study, we determined the role of Nur77 in airway inflammation using a murine model of OVA-induced allergic airway inflammation. We found that OVA-challenged Nur77 knockout (KO) mice show significantly enhanced infiltration of inflammatory cells, including eosinophils and lymphocytes, and aggravated mucus production. The infiltration of macrophages is limited in this model and was similar in wild-type and Nur77 KO mice. Higher levels of Th2 cytokines were found in bronchoalveolar lavage fluid and draining lymph node cells of Nur77-KO mice, as well as increased serum IgG1 and IgG2a levels. Knockdown of Nur77 in human lung epithelial cells resulted in a marked increase in IκBα phosphorylation, corresponding with elevated NF-κB activity, whereas Nur77 overexpression decreased NF-κB activity. Consistently, Nur77 significantly decreased mRNA levels of inflammatory cytokines and Muc5ac expression and also attenuated mucus production in lung epithelial cells. To further corroborate these findings, we searched for association of single nucleotide polymorphisms in Nur77 gene with asthma and with the severity of bronchial hyperresponsiveness. We identified three Nur77 single nucleotide polymorphisms showing association with severity of bronchial hyperresponsiveness in asthma patients. Collectively, these findings support a protective role of Nur77 in OVA-induced airway inflammation and identify Nur77 as a novel therapeutic target for airway inflammation.

CD300f associates with IL-4 receptor α and amplifies IL-4-induced immune cell responses

IL-4 receptor (R) α, the common receptor chain for IL-4 and IL-13, is a critical component in IL-4- and IL-13-mediated signaling and subsequent effector functions such as those observed in type 2 inflammatory responses. Nonetheless, the existence of intrinsic pathways capable of amplifying IL-4Rα-induced responses remains unknown. In this study, we identified the myeloid-associated Ig receptor CD300f as an IL-4-induced molecule in macrophages. Subsequent analyses demonstrated that CD300f was colocalized and physically associated with IL-4Rα. Using Cd300f(-/-) cells and receptor cross-linking experiments, we established that CD300f amplified IL-4Rα-induced responses by augmenting IL-4/IL-13-induced signaling, mediator release, and priming. Consistently, IL-4- and aeroallergen-treated Cd300f(-/-) mice displayed decreased IgE production, chemokine expression, and inflammatory cell recruitment. Impaired responses in Cd300f(-/-) mice were not due to the inability to generate a proper Th2 response, because IL-4/IL-13 levels were markedly increased in allergen-challenged Cd300f(-/-) mice, a finding that is consistent with decreased cytokine consumption. Finally, CD300f expression was increased in monocytes and eosinophils obtained from allergic rhinitis patients. Collectively, our data highlight a previously unidentified role for CD300f in IL-4Rα-induced immune cell responses. These data provide new insights into the molecular mechanisms governing IL-4Rα-induced responses, and may provide new therapeutic tools to target IL-4 in allergy and asthma.

IL-4 and IL-13 signaling in allergic airway disease

Aberrant production of the prototypical type 2 cytokines, interleukin (IL)-4 and IL-13 has long been associated with the pathogenesis of allergic disorders. Despite tremendous scientific inquiry, the similarities in their structure, and receptor usage have made it difficult to ascertain the distinct role that these two look-alike cytokines play in the onset and perpetuation of allergic inflammation. However, recent discoveries of differences in receptor distribution, utilization/assembly and affinity between IL-4 and IL-13, along with the discovery of unique innate lymphoid 2 cells (ILC2) which preferentially produce IL-13, not IL-4, are beginning to shed light on these mysteries. The purpose of this chapter is to review our current understanding of the distinct roles that IL-4 and IL-13 play in allergic inflammatory states and the utility of their modulation as potential therapeutic strategies for the treatment of allergic disorders.

The development of allergic inflammation in a murine house dust mite asthma model is suppressed by synbiotic mixtures of non-digestible oligosaccharides and Bifidobacterium breve M-16V

Purpose

The incidence and severity of allergic asthma is rising, and novel strategies to prevent or treat this disease are needed. This study investigated the effects of different mixtures of non-digestible oligosaccharides combined with Bifidobacterium breve M-16V (BB) on the development of allergic airway inflammation in an animal model for house dust mite (HDM)-induced allergic asthma.

Methods

BALB/c mice were sensitized intranasally (i.n.) with HDM and subsequently challenged (i.n.) with PBS or HDM while being fed diets containing different oligosaccharide mixtures in combination with BB or an isocaloric identical control diet. Bronchoalveolar lavage fluid (BALF) inflammatory cell influx, chemokine and cytokine concentrations in lung homogenates and supernatants of ex vivo HDM-restimulated lung cells were analyzed.

Results

The HDM-induced influx of eosinophils and lymphocytes was reduced by the diet containing the short-chain and long-chain fructo-oligosaccharides and BB (FFBB). In addition to the HDM-induced cell influx, concentrations of IL-33, CCL17, CCL22, IL-6, IL-13 and IL-5 were increased in supernatants of lung homogenates or BALF and IL-4, IFN-γ and IL-10 were increased in restimulated lung cell suspensions of HDM-allergic mice. The diet containing FFBB reduced IL-6, IFN-γ, IL-4 and IL-10 concentrations, whereas the combination of galacto-oligosaccharides and long-chain fructo-oligosaccharides with BB was less potent in this model.

Conclusion

These findings show that synbiotic dietary supplementation can affect respiratory allergic inflammation induced by HDM. The combination of FFBB was most effective in the prevention of HDM-induced airway inflammation in mice.

Correlation between CCL26 production by human bronchial epithelial cells and airway eosinophils: Involvement in patients with severe eosinophilic asthma

BACKGROUND

High pulmonary eosinophil counts are associated with asthma symptoms and severity. Bronchial epithelial cells (BECs) produce CC chemokines, notably CCL26 (eotaxin-3), which recruits and activates eosinophils from asthmatic patients. This suggests that CCL26 production by BECs might be involved in persistent eosinophilia in patients with severe asthma despite treatment with high corticosteroid doses.

OBJECTIVE

We sought to determine whether CCL26 levels correlate with eosinophilia and asthma severity.

METHODS

Human CC chemokine expression was assessed by means of quantitative PCR or a quantitative PCR array in vehicle- or IL-13-treated BECs. CCL26 was quantitated by means of ELISA. Immunohistochemistry analyses of CCL26 and major basic protein were done on bronchial biopsy specimens.

RESULTS

IL-13 selectively induced CCL26 expression by BECs. This increase was time-dependent and more prominent in BECs from patients with severe eosinophilic asthma. CCL26 levels measured in supernatants of IL-13-stimulated BECs also increased with asthma severity as follows: patients with severe eosinophilic asthma > patients with mild asthma ≈ healthy subjects. Immunohistochemistry analyses of bronchial biopsy specimens confirmed increased levels of CCL26 in the epithelium of patients with mild and those with severe eosinophilic asthma. Tissue eosinophil counts did not correlate with CCL26 staining. However, sputum CCL26 levels significantly correlated with sputum eosinophil counts (P < .0001), suggesting that CCL26 participates in the movement of eosinophils from the tissues to the airway lumen.

CONCLUSIONS

These results show a relation between CCL26 production by IL-13-stimulated BECs, sputum eosinophil counts, and asthma severity. They also suggest a role for CCL26 in the sustained inflammation observed in patients with severe eosinophilic asthma and reveal CCL26 as a potential target for treating patients with eosinophilic asthma that are refractory to classic therapies.

Serotonin 5-HT₂ receptor activation prevents allergic asthma in a mouse model

Asthma is an inflammatory disease of the lung characterized by airways hyper-responsiveness (AHR), inflammation, and mucus hyperproduction. Current mainstream therapies include bronchodilators that relieve bronchoconstriction and inhaled glucocorticoids to reduce inflammation. The small molecule hormone and neurotransmitter serotonin has long been known to be involved in inflammatory processes; however, its precise role in asthma is unknown. We have previously established that activation of serotonin 5-hydroxytryptamine (5-HT)(2A) receptors has potent anti-inflammatory activity in primary cultures of vascular tissues and in the whole animal in vasculature and gut tissues. The 5-HT(2A) receptor agonist, (R)-2,5-dimethoxy-4-iodoamphetamine [(R)-DOI] is especially potent. In this work, we have examined the effect of (R)-DOI in an established mouse model of allergic asthma. In the ovalbumin mouse model of allergic inflammation, we demonstrate that inhalation of (R)-DOI prevents the development of many key features of allergic asthma, including AHR, mucus hyperproduction, airways inflammation, and pulmonary eosinophil recruitment. Our results highlight a likely role of the 5-HT2 receptors in allergic airways disease and suggest that 5-HT2 receptor agonists may represent an effective and novel small molecule-based therapy for asthma.