Antigen-induced Airway Inflammation Research Articles

Role of CD4+ T Cells in Allergic Airway Diseases: Learning from Murine Models.

The essential contribution of CD4+ T cells in allergic airway diseases has been demonstrated, especially by using various murine models of antigen-induced airway inflammation. In addition to antigen-immunized mouse models employing mast cell-deficient mice and CD4+ T cell-depleting procedure, antigen-specific CD4+ T cell transfer models have revealed the possible development of allergic inflammation solely dependent on CD4+ T cells. Regardless of the classical Th1/Th2 theory, various helper T cell subsets have the potential to induce different types of allergic inflammation. T cell receptor (TCR)-transgenic (Tg) mice have been used for investigating T cell-mediated immune responses. Besides, we have recently generated cloned mice from antigen-specific CD4+ T cells through somatic cell nuclear transfer. In contrast to TCR-Tg mice that express artificially introduced TCR, the cloned mice express endogenously regulated antigen-specific TCR. Upon antigen exposure, the mite antigen-reactive T cell-cloned mice displayed strong airway inflammation accompanied by bronchial hyperresponsiveness in a short time period. Antigen-specific CD4+ T cell-cloned mice are expected to be useful for investigating the detailed role of CD4+ T cells in various allergic diseases and for evaluating novel anti-allergic drugs.

Critical Role of IRAK-M in Regulating Antigen-Induced Airway Inflammation.

Asthma is an airway epithelium disorder involving allergic lung inflammation. IL-1 receptor-associated kinase M (IRAK-M) is a negative regulator of Toll-like receptor (TLR) signaling on airway epithelial cells and macrophages, and it is known to limit the overproduction of cytokines during the inflammatory process. However, the direct role of IRAK-M in asthma pathogenesis is unclear. In the present study, we found a significant elevation of IRAK-M expression in mouse lungs after ovalbumin (OVA) exposure. Compared with wild-type mice, IRAK-M knockout (KO) mice responded to OVA challenge with significantly worse infiltration of airway inflammatory cells, greater airway responsiveness, higher proinflammatory cytokine levels in lung homogenates, and more prominent T-helper cell type 2 (Th2) and Th17 deviation. OVA exposure also induced higher activities of dendritic cells (DCs) and macrophages from IRAK-M KO mouse lungs. Furthermore, adoptive transfer of either IRAK-M KO bone-marrow-derived DCs or macrophages into wild-type mice aggravated OVA-induced airway inflammation. In vitro experiments showed that IRAK-M KO naive CD4+ T cells were more prone to differentiate into Th17 cells, but not regulatory T cells. Consistently, activation of IκBζ was significantly increased in the absence of IRAK-M, facilitating Th17 polarization. These findings suggest that IRAK-M plays a crucial role in the regulation of allergic airway inflammation by modifying the function of airway epithelia, DCs, and macrophages, and the differentiation of naive CD4+ T cells. Modulation of IRAK-M may provide a novel target for the control of asthma.

Th9 cells induce steroid-resistant bronchial hyperresponsiveness in mice

BackgroundReduced responsiveness to corticosteroid therapy is a major problem for patients with severe asthma. Although Th9 cells, along with Th2 cells, facilitate antigen-induced airway eosinophilia and bronchial hyperresponsiveness (BHR), the sensitivity of Th9 cell-mediated responses to steroid therapy remains unknown. In this study, we investigated the effect of dexamethasone (Dex) on antigen-induced airway inflammation in Th9 cell-transferred mice. MethodsOvalbumin (OVA)-specific Th2 and Th9 cells were polarized from the CD4+ T cells of DO11.10/RAG-2−/− mice. BALB/c mice were adoptively transferred with Th2 or Th9 cells and challenged with OVA. Dex treatment was performed twice, at 1 h before and at 24 h after the OVA challenge. Following treatment, the number of inflammatory cells in the bronchoalveolar lavage fluid and the bronchial responsiveness to inhaled methacholine were determined. ResultsIn both the Th2 and Th9 cell-transferred mice, substantial accumulation of eosinophils in the lungs and BHR were induced by challenge with the specific antigen. In the Th2 cell-transferred mice, these responses were significantly diminished by Dex treatment. In contrast, neither cellular infiltration nor BHR was affected by Dex treatment in the Th9 cell-transferred mice, although the Th9 cells substantially expressed glucocorticoid receptor α. Accordingly, antigen-induced interleukin-9 expression in the Th9 cells was attenuated by Dex treatment at least in vitro. Antigen-induced lung infiltration of infused Th2 cells but not Th9 cells was significantly suppressed by Dex. ConclusionsIn contrast to Th2-mediated responses, Th9-mediated airway inflammation was not affected by Dex. Th9 cells might be involved in the developmental mechanisms of steroid-resistant asthma.

Role of Histamine-releasing Factor in Allergic Inflammatory Reactions.

Mast cells are effector cells in immunoglobulin E (IgE)-mediated immediate hypersensitivity and allergic diseases such as asthma and food allergy. Mast cells are activated by the aggregation of the IgE-bound high-affinity IgE receptor FcεRI with multivalent antigen. Activated mast cells secrete proinflammatory mediators such as histamine, serotonin, and proteases and produce cytokines and chemokines. However, it has been reported that mast cells are activated by crosslinking of FcεRI with monomeric IgE in the absence of antigen. We have recently demonstrated that histamine-releasing factor (HRF) is involved in IgE-mediated mast cell activation both in vitro and in vivo. HRF binds to a subset of IgE and IgG molecules [HRF-reactive antibodies (Abs)]. The Fab, but not Fc, portions of the IgE and IgG molecules are HRF-binding sites, and the N-terminal 19-residue (N19) and H3 portions of HRF are HRF-reactive Ab-binding sites. We observed that both N19 and H3 tagged with glutathione S transferase (GST) (GST-N19 and GST-H3) can inhibit the interaction between HRF and HRF-reactive Abs. Using acute- and late-phase passive cutaneous anaphylaxis mouse models, it was shown that HRF initiates mast cell activation through HRF-reactive, but not HRF-nonreactive, IgE in vivo. Antigen-induced passive cutaneous anaphylaxis was inhibited by pretreatment with GST-N19 and GST-H3. We demonstrated that pretreatment with GST-N19 before antigen challenge inhibited antigen-induced mast cell-dependent airway inflammation. In addition, GST-N19 partially inhibited Aspergillus fumigatus extract-induced IgE-dependent airway inflammation. However, GST-N19 did not inhibit T cell-dependent airway inflammation. These results suggest that mast cells are target cells for HRF to initiate IgE- and mast cell-dependent airway inflammation.

Rapid development of antigen-induced airway inflammation in cloned mice generated by nuclear transfer of antige-specific CD4+ T cells.

Rapid development of antigen-induced airway inflammation in cloned mice generated by nuclear transfer of antige-specific CD4+ T cells.

Effects of Asian Dust Particles on the Early-Stage Antigen-Induced Immune Response of Asthma in NC/Nga Mice.

Asian dust (AD) can aggravate airway inflammation in asthma, but the association between AD and the development of asthma remains unclear. This study aimed to investigate the effects of AD on the early stage of antigen sensitization using a mouse model of asthma, as well as the role of leukotrienes (LTs) in antigen-induced airway inflammation potentiated by AD particles. NC/Nga mice were co-sensitized by intranasal instillation of AD particles and/or Dermatophagoides farinae (Df) for five consecutive days. Df-sensitized mice were stimulated with an intranasal Df challenge at seven days. Mice were treated with the type 1 cysteinyl LT (CysLT1) receptor antagonist orally 4 h before and 1 h after the allergen challenge. At 24 h post-challenge, the differential leukocyte count, inflammatory cytokines, and LTs in bronchoalveolar lavage fluid were assessed, and airway inflammation was evaluated histopathologically. AD augmented neutrophilic and eosinophilic airway inflammation with increased CysLTs and dihydroxy-LT in a mouse model of asthma. The CysLT1 receptor antagonist was shown to attenuate both neutrophilic and eosinophilic airway inflammation augmented by AD. Therefore, exposure to AD may be associated with the development of asthma and LTs may play important roles in airway inflammation augmented by AD.

Short-term intratracheal use of PEG-modified IL-2 and glucocorticoid persistently alleviates asthma in a mouse model.

Regulatory T (Treg) cells play an important role in allergic airway diseases, and upregulation of Treg cells is a potential therapeutic strategy for asthma. In this study, we show that short-term intratracheal use of IL-2 combined with glucocorticoid alleviates antigen-induced airway inflammation and reduces airway hyperresponsiveness by expanding antigen-nonspecific Treg cells, with a decrease in T helper 2 (Th2) cells and Th2-associated cytokines. We also designed a long-acting polyethylene glycol (PEG)-modified IL-2 and demonstrated that the optimal dosage form is IL-2(PEG) plus budesonide, which can upregulate Treg cells and ameliorate asthma at a lower dose. The therapeutic effect was faster than treatment with dexamethasone and was effective at a low dose suitable for humans that could last for at least 6 weeks. This study unveils a new therapeutic regimen and suggests that such endogenous Treg therapy could be a useful tool to persistently alleviate asthma.

Boysenberry ingestion supports fibrolytic macrophages with the capacity to ameliorate chronic lung remodeling.

Lung fibrosis negatively impacts on lung function in chronic asthma and is linked to the development of profibrotic macrophage phenotypes. Epidemiological studies have found that lung function benefits from increased consumption of fruit high in polyphenols. We investigated the effect of boysenberry consumption, in both therapeutic and prophylactic treatment strategies in a mouse model of chronic antigen-induced airway inflammation. Boysenberry consumption reduced collagen deposition and ameliorated tissue remodeling alongside an increase in the presence of CD68+CD206+arginase+ alternatively activated macrophages in the lung tissue. The decrease in tissue remodeling was associated with increased expression of profibrolytic matrix metalloproteinase-9 protein in total lung tissue. We identified alternatively activated macrophages in the mice that consumed boysenberry as a source of the matrix metalloproteinase-9. Oral boysenberry treatment may moderate chronic tissue remodeling by supporting the development of profibrolytic alternatively activated macrophages expressing matrix metalloproteinase-9. Regular boysenberry consumption therefore has the potential to moderate chronic lung remodeling and fibrosis in asthma and other chronic pulmonary diseases.

Peripheral Airway Smooth Muscle, but Not the Trachealis, Is Hypercontractile in an Equine Model of Asthma.

Heaves is a naturally occurring equine disease that shares many similarities with human asthma, including reversible antigen-induced bronchoconstriction, airway inflammation, and remodeling. The purpose of this study was to determine whether the trachealis muscle is mechanically representative of the peripheral airway smooth muscle (ASM) in an equine model of asthma. Tracheal and peripheral ASM of heaves-affected horses under exacerbation, or under clinical remission of the disease, and control horses were dissected and freed of epithelium to measure unloaded shortening velocity (Vmax), stress (force/cross-sectional area), methacholine effective concentration at which 50% of the maximum response is obtained, and stiffness. Myofibrillar Mg(2+)-ATPase activity, actomyosin in vitro motility, and contractile protein expression were also measured. Horses with heaves had significantly greater Vmax and Mg(2+)-ATPase activity in peripheral airway but not in tracheal smooth muscle. In addition, a significant correlation was found between Vmax and the time elapsed since the end of the corticosteroid treatment for the peripheral airways in horses with heaves. Maximal stress and stiffness were greater in the peripheral airways of the horses under remission compared with controls and the horses under exacerbation, potentially due to remodeling. Actomyosin in vitro motility was not different between controls and horses with heaves. These data demonstrate that peripheral ASM is mechanically and biochemically altered in heaves, whereas the trachealis behaves as in control horses. It is therefore conceivable that the trachealis muscle may not be representative of the peripheral ASM in human asthma either, but this will require further investigation.

Heme oxygenase-1 inhibits basophil maturation and activation but promotes its apoptosis in T helper type 2-mediated allergic airway inflammation.

The anti-inflammatory role of heme oxygenase-1 (HO-1) has been studied extensively in many disease models including asthma. Many cell types are anti-inflammatory targets of HO-1, such as dendritic cells and regulatory T cells. In contrast to previous reports that HO-1 had limited effects on basophils, which participate in T helper type 2 immune responses and antigen-induced allergic airway inflammation, we demonstrated in this study, for the first time, that the up-regulation of HO-1 significantly suppressed the maturation of mouse basophils, decreased the expression of CD40, CD80, MHC-II and activation marker CD200R on basophils, blocked DQ-ovalbumin uptake and promoted basophil apoptosis both invitro and invivo, leading to the inhibition of T helper type 2 polarization. These effects of HO-1 were mimicked by exogenous carbon monoxide, which is one of the catalytic products of HO-1. Furthermore, adoptive transfer of HO-1-modified basophils reduced ovalbumin-induced allergic airway inflammation. The above effects of HO-1 can be reversed by the HO-1 inhibitor Sn-protoporphyrin IX. Moreover, conditional depletion of basophils accompanying hemin treatment further attenuated airway inflammation compared with the hemin group, indicating that the protective role of HO-1 may involve multiple immune cells. Collectively, our findings demonstrated that HO-1 exerted its anti-inflammatory function through suppression of basophil maturation and activation, but promotion of basophil apoptosis, providing a possible novel therapeutic target in allergic asthma.

The effects of imiquimod on the level of BALF IL-12, IL-13 and sera IgE in asthmatic murine

Objective To observe the effects of aerosol imiquimod on the level of Interleukin-12(IL-12) and interleukin-13(IL-13) in bronchial alveolar lavage fluid(BALF) and serum immunoglobulin E( IgE ) level in mouse asthma models. Methods Thirty BALB/c mice were divided into 3 groups, control group, asthma group and imiquimod group, ten in each group.The asthma group and imiquimod group were established by sensitization and challenge with ovalbumin (OVA), imiquimod group was interfered with aerosol imiquimod 30 min before challenge.Serum in each group was collected by excising eyeball 24 h after the last challenge.The level of IgE in serum was measured by ELISA.Bronchoalveolar lavage fluid (BALF) was performed, and total cell counts, cell differential were examined.The level of IL-12 and IL-13 in BALF was measured by ELISA and total cell counts, cell differential were examined in BALF.The inflammation changes of lung was observed by HE staining. Results (1)By hematoxylin-eosin(HE) staining, the result of asthma mice were small airway wall thickening, secretion increased, epithelial cells fall off, arranging disorderly, and submucosal had plenty of inflammatory cells infiltration, mainly with lymphocytes.But imquimod group attenuated the airway inflammation of asthmatic mice.(2)Total cell counts and all kinds of inflammatory cells of asthma group were increased greatly compared with normal group; Eosinophil and lymphocyte cells were much lower in imquimod group than those in asthma group (P<0.05). (3) The level of IL-13 in BALF and the level of IgE in serum in imiquimod group was obviously higher than that in control group, IL-13 level were positively correlated with IgE level(r=0.774, P<0.05), but imiquimod group was greatly decreased compared with control group and increased in comparison with that in group A; The level of IL-12 in asthma group was reduced and the level of IgE was increased compared with normal group.IL-12 level in imiquimod group was evidently higher and IgE level was lower than that in asthma group.IL-12 level negatively correlated with IgE level(r=-0.802, P<0.05). Conclusion Imiquimod aerosol inhalation may up-regulate the level of Th1 chemokine IL-12, down-regulates the level of Th2 chemokine IL-13 and decrease the level of IgE in serum so that it may suppress antigen-induced airway inflammation. Key words: Asthma; IgE; Imiquimod

Production of interleukin (IL)-33 in the lungs during multiple antigen challenge-induced airway inflammation in mice, and its modulation by a glucocorticoid

Although interleukin (IL)-33 is a candidate aggravator of asthma, the cellular sources of IL-33 in the lungs during the progression of antigen-induced airway inflammation remain unclear. Furthermore, it has not been determined whether the antigen-induced production of IL-33 can be pharmacologically modulated in vivo. In this study, we examined the production of IL-33 in the lungs of sensitized mice during multiple intratracheal challenges with the antigen, ovalbumin. The 1st challenge clearly induced the IL-33 production in the lungs, and it was enhanced by the 2nd–4th challenges. IL-33 mRNA transcription was also induced after these challenges. An immunohistochemical analysis revealed that the cellular sources of IL-33 after the 1st challenge were mainly bronchial epithelial cells, while those after the 3rd challenge were not only the epithelial cells, but also inflammatory cells that infiltrated the lungs. Flow cytometric analyses indicated that approximately 20% and 10% of the IL-33-producing cells in the lungs were M2 macrophages and conventional dendritic cells, respectively. A systemic treatment with dexamethasone before the 1st challenge potently suppressed the IL-33 production. When dexamethasone was administered before the respective challenges, production of the IL-33 protein and the infiltration of IL-33-producing M2 macrophages and dendritic cells into the lungs in the 3rd challenge were also suppressed. In conclusion, the cellular sources of IL-33 in the lungs were dynamically altered during multiple challenges: not only bronchial epithelial cells, but also the M2 macrophages and dendritic cells that infiltrated the lungs produced IL-33. The production of IL-33 was susceptible to the glucocorticoid treatment.

Blockade of Notch Signalling by γ-Secretase Inhibitor in Lung T Cells of Asthmatic Mice Affects T Cell Differentiation and Pulmonary Inflammation.

Notch is a single-pass transmembrane receptor protein expressed by T cells, which contributes to the pathogenesis of asthma through regulation of the development and differentiation of T cells. γ-Secretase inhibitor (GSI) acts as an effective blocker of Notch signalling. The present study aimed to investigate the role of GSI MW167 in T cell differentiation and antigen-induced airway inflammation. An OVA-induced airway inflammation mouse model was established. Blockade of Notch signalling was achieved using MW167. The expression of IL-4, IL-5, IFN-γ, Notch1 signalling and pro-inflammatory transcription factors in activated lung T cells was evaluated. Finally, the therapeutic effect of MW167 was investigated by haematoxylin and eosin staining, real-time PCR and ELISA. The expression of IL-4 and IL-5 decreased and that of IFN-γ increased significantly, and the protein expression levels of pro-inflammatory transcription factors reduced in active lung T cells after administration of MW167, compared to the control group. MW167 treatment prevented OVA-induced airway inflammation and histological changes. The serum and bronchoalveolar lavage fluid (BALF) levels of IL-4 and IL-5 in MW167-treated mice decreased significantly, whereas those of IFN-γ increased, relative to the levels in OVA-challenged animals treated with PBS. Our findings indicate that Notch signalling plays an important role in the pathogenesis of asthma and that MW167 may be a potential therapeutic target for allergen-induced airway inflammation.

Influenza A infection enhances antigen-induced airway inflammation and hyperresponsiveness in young but not aged mice.

Although morbidity and mortality rates from asthma are highest in patients > 65 years of age, the effect of older age on airway inflammation in asthma is not well established. To investigate age-related differences in the promotion of allergic inflammation after influenza A viral respiratory infection on antigen-specific IgE production, antigen-induced airway inflammation and airway hyperresponsiveness in mice. To accomplish this objective, the following model system was used. Young (6 week) and aged (18 months) BALB/c mice were first infected with a non-lethal dose of influenza virus A (H/HKx31). Mice were then ovalbumin (OVA)-sensitized during the acute infection (3-days post inoculation) and then chronically underwent challenge to the airways with OVA. Forty-eight hours after the final OVA challenge, airway hyperresponsiveness (AHR), bronchoalveolar fluid (BALF) cellular and cytokine profile, antigen-specific IgE and IgG1, and lung tissue inflammation were measured. Age-specific differences were noted on the effect of a viral infection, allergic sensitization, airway inflammation and airway hyperresponsiveness. Serum OVA-specific IgE was significantly increased in only the aged mice infected with influenza virus. Despite greater morbidity (e.g. weight loss and sickness scores) during the acute infection in the 18-month old mice that were OVA-sensitized, there was little effect on the AHR and BALF cellular differential. In contrast, BALF neutrophils and AHR increased, but eosinophils decreased in 6-week mice that were OVA-sensitized during an acute influenza infection. With increased age in a mouse model, viral infection prior to antigen sensitization affects the airway and systemic allergic response differently. These differences may reflect distinct phenotypic features of allergic inflammation in older patients with asthma.

Mechanisms of pathogenesis in allergic asthma: role of interleukin-23.

Asthma is a chronic airway inflammatory disease characterized by intense leukocyte and eosinophilic infiltration accompanied by mucus hypersecretion and tissue hyperresponsiveness. Recent evidence suggests that T-helper (Th)2 cells and their cytokine products orchestrate the pathology of asthma. In addition, Th17 cells are implicated in the pathogenesis of antigen-induced airway inflammation. The Th17 related cytokine interleukin (IL)-23 plays important roles in many immunological diseases, such as experimental autoimmune encephalomyelitis, rheumatoid arthritis, psoriasis and inflammatory bowel disease. Several reports describe the role of IL-23 in the pathogenesis of allergic asthma in both human and mice. IL-23 leads to neutrophil infiltration in the airway of asthmatic mice, which is characteristic of severe asthma resulting from Th17 development and subsequently IL-17 secretion. IL-23 can also promote eosinophil infiltration in the airway, which is a hallmark of allergic asthma. These studies suggest that IL-23 could be a promoting factor in the development of allergic asthma and likewise would be a target for asthma therapy. In support of this view, trials of anti-IL-23 therapy have been attempted in human and mouse asthma models with encouraging outcomes. This review presents the role of IL-23 in asthma according to recent clinical trials and animal model studies. The proposed mechanisms of IL-23-induced airway inflammation and the agents currently being tested that target IL-23 related pathways are discussed.

Basophils as a primary inducer of the T helper type 2 immunity in ovalbumin‐induced allergic airway inflammation

Antigen-induced allergic airway inflammation is mediated by T helper type 2 (Th2) cells and their cytokines, but the mechanism that initiates the Th2 immunity is not fully understood. Recent studies show that basophils play important roles in initiating Th2 immunity in some inflammatory models. Here we explored the role of basophils in ovalbumin (OVA) -induced airway allergic inflammation in BALB/c mice. We found that OVA sensitization and challenge resulted in a significant increase in the amount of basophils in blood and lung, along with the up-regulation of activation marker of CD200R. However, depletion of basophils with MAR-1 or Ba103 antibody attenuated airway inflammation, represented by the significantly decreased amount of the Th2 subset in spleen and draining lymph nodes, interlukin-4 level in lung and OVA-special immunoglobulin E (sIgE) levels in serum. On the other hand, adoptive transfer of basophils from OVA-challenged lung tissue to naive BALB/c mice provoked the Th2 immune response. In addition, pulmonary basophils from OVA-challenged mice were able to uptake DQ-OVA and express MHC class II molecules and CD40 in vivo, as well as to release interleukin-4 following stimulation by IgE-antigen complexes and promote Th2 polarization in vitro. These findings demonstrate that basophils may participate in Th2 immune responses in antigen-induced allergic airway inflammation and that they do so through facilitating antigen presentation and providing interleukin-4.

Regulatory T cell Itch reins in Th2 inflammation

Regulatory T cell Itch reins in Th2 inflammation

Wogonin attenuates ovalbumin antigen-induced neutrophilic airway inflammation by inhibiting th17 differentiation.

Allergic airway inflammation is generally considered to be a Th2-type immune response. Recent studies, however, have demonstrated that Th17-type immune responses also play important roles in this process, particularly in the pathogenesis of neutrophilic airway inflammation, a hallmark of severe asthma. We scrutinized several Kampo extracts that reportedly exhibit anti-inflammatory activity by using in vitro differentiation system of human and mouse naïve T cells. We found that hange-shashin-to (HST) and oren-gedoku-to (OGT) possess inhibitory activity for Th17 responses in vitro. Indeed, wogonin and berberine, major components common to HST and OGT, exhibit Th17-inhibitory activities in both murine and human systems in vitro. We therefore evaluated whether wogonin suppresses OVA-induced neutrophilic airway inflammation in OVA TCR-transgenic DO11.10 mice. Consequently, oral administration of wogonin significantly improved OVA-induced neutrophilic airway inflammation. Wogonin suppressed the differentiation of naïve T cells to Th17 cells, while showing no effects on activated Th17 cells.

Itch expression by Treg cells controls Th2 inflammatory responses

Regulatory T (Treg) cells maintain immune homeostasis by limiting autoimmune and inflammatory responses. Treg differentiation, maintenance, and function are controlled by the transcription factor Foxp3. However, the exact molecular mechanisms underlying Treg cell regulation remain elusive. Here, we show that Treg cell-specific ablation of the E3 ubiquitin ligase Itch in mice caused massive multiorgan lymphocyte infiltration and skin lesions, chronic T cell activation, and the development of severe antigen-induced airway inflammation. Surprisingly, Foxp3 expression, homeostasis, and the in vitro and in vivo suppressive capability of Treg cells were not affected by Itch deficiency. We found that the expression of Th2 cytokines by Treg cells was increased in the absence of Itch. Fate mapping revealed that a fraction of Treg cells lost Foxp3 expression independently of Itch. However, Th2 cytokines were excessively augmented in Itch(-/-) Foxp3-negative "ex-Treg" cells without altering the percentage of conversion. Targeted knockdown of Th2 transcriptional regulators in Itch(-/-) Treg cells prevented Th2 cytokine production. The present study unveils a mechanism of Treg cell acquisition of Th2-like properties that is independent of Foxp3 function and Treg cell stability.

Suppressive effects of a novel CC chemokine receptor 4 antagonist on Th2 cell trafficking in ligand- and antigen-induced mouse models

CC chemokine receptor 4 (CCR4) has been implicated as a preferential marker for T helper type 2 (Th2) cells, and is believed to be involved in the pathology of allergic diseases by controlling Th2 cell trafficking into inflamed tissues. The objective of the study was to characterize the pharmacological properties of E0001-163, a novel CCR4 antagonist. E0001-163 was tested in both in vitro chemotaxis assays as well as in vivo mouse models of CCR4 ligand-induced air pouch and antigen-induced airway inflammation by utilizing in vitro-polarized Th2 cells. In vitro, E0001-163 inhibited migratory response of human Th2-polarized cells to CCL22, a CCR4 ligand, with an IC50 value of 11.9nM. E0001-163 significantly suppressed CCL22-induced Th2 cell trafficking into mouse air pouch in a dose-dependent manner at doses of 3 and 10mg/kg, suggesting that E0001-163 has an inhibitory effect on CCR4-mediated T cell trafficking in vivo. In addition, E0001-163 partially decreased Th2 cell trafficking and the level of IL-4 in the lungs in Th2-tansferred and ovalbumin (OVA)-challenged mice. T cell trafficking involves multiple chemokine receptors both in acute and chronic phases, and our findings suggest that CCR4, together with other chemokine receptors, may be involved in Th2 cell trafficking under disease conditions.