Intervention of thymus and activation-regulated chemokine attenuates the development of allergic airway inflammation and hyperresponsiveness in mice

Proteomic signatures of eosinophilic and neutrophilic asthma from serum and sputum

BACKGROUND

Eosinophilic and neutrophilic asthma defined by high levels of blood and sputum eosinophils and neutrophils exemplifies the inflammatory heterogeneity of asthma, particularly severe asthma. We analysed the serum and sputum proteome to identify biomarkers jointly associated with these different phenotypes.

METHODS

Proteomic profiles (N = 1129 proteins) were assayed in sputum (n = 182) and serum (n = 574) from two cohorts (U-BIOPRED and ADEPT) of mild-moderate and severe asthma by SOMAscan. Using least absolute shrinkage and selection operator (LASSO)-penalised logistic regression in a stability selection framework, we sought sparse sets of proteins associated with either eosinophilic or neutrophilic asthma with and without adjustment for established clinical factors including oral corticosteroid use and forced expiratory volume.

FINDINGS

We identified 13 serum proteins associated with eosinophilic asthma, including 7 (PAPP-A, TARC/CCL17, ALT/GPT, IgE, CCL28, CO8A1, and IL5-Rα) that were stably selected while adjusting for clinical factors yielding an AUC of 0.84 (95% CI: 0.83-0.84) compared to 0.62 (95% CI: 0.61-0.63) for clinical factors only. Sputum protein analysis selected only PAPP-A (AUC = 0.81 [95% CI: 0.80-0.81]). 12 serum proteins were associated with neutrophilic asthma, of which 5 (MMP-9, EDAR, GIIE/PLA2G2E, IL-1-R4/IL1RL1, and Elafin) complemented clinical factors increasing the AUC from 0.63 (95% CI: 0.58-0.67) for the model with clinical factors only to 0.89 (95% CI: 0.89-0.90). Our model did not select any sputum proteins associated with neutrophilic status.

INTERPRETATION

Targeted serum proteomic profiles are a non-invasive and scalable approach for subtyping of neutrophilic and eosinophilic asthma and for future functional understanding of these phenotypes.

FUNDING

U-BIOPRED has received funding from the Innovative Medicines Initiative (IMI) Joint Undertaking under grant agreement no. 115010, resources of which are composed of financial contributions from the European Union's Seventh Framework Programme (FP7/2007-2013), and European Federation of Pharmaceutical Industries and Associations (EFPIA) companies' in-kind contributions (www.imi.europa.eu). ADEPT was funded by Johnson & Johnson/Janssen pharmaceutical Company.

Invariant natural killer T cells in lung diseases

Invariant natural killer T (iNKT) cells are a subset of T cells that are characterized by a restricted T-cell receptor (TCR) repertoire and a unique ability to recognize glycolipid antigens. These cells are found in all tissues, and evidence to date suggests that they play many immunological roles in both homeostasis and inflammatory conditions. The latter include lung inflammatory diseases such as asthma and infections: the roles of lung-resident iNKT cells in these diseases have been extensively researched. Here, we provide insights into the biology of iNKT cells in health and disease, with a particular focus on the role of pulmonary iNKT cells in airway inflammation and other lung diseases.

Role of Thymus and Activation-Regulated Chemokine in Allergic Asthma

Background

Objective

Methods

Results

Conclusion

Platelets Independently Recruit into Asthmatic Lungs and Models of Allergic Inflammation via CCR3

Platelet activation and pulmonary recruitment occur in patients with asthma and in animal models of allergic asthma, in which leukocyte infiltration, airway remodeling, and hyperresponsiveness are suppressed by experimental platelet depletion. These observations suggest the importance of platelets to various characteristics of allergic disease, but the mechanisms of platelet migration and location are not understood. The aim of this study was to assess the mechanism of platelet recruitment to extravascular compartments of lungs from patients with asthma and after allergen challenge in mice sensitized to house dust mite (HDM) extract (contains the DerP1 [Dermatophagoides pteronyssinus extract peptidase 1] allergen); in addition, we assessed the role of chemokines in this process. Lung sections were immunohistochemically stained for CD42b⁺ platelets. Intravital microscopy in allergic mice was used to visualize platelets tagged with an anti-mouse CD49b-PE (phycoerythrin) antibody. Platelet-endothelial interactions were measured in response to HDM (DerP1) exposure in the presence of antagonists to CCR3, CCR4, and CXCR4. Extravascular CD42b⁺ platelets were detected in the epithelium and submucosa in bronchial biopsy specimens taken from subjects with steroid-naive mild asthma. Platelets were significantly raised in the lung parenchyma from patients with fatal asthma compared with postmortem control-lung tissue. Furthermore, in DerP1-sensitized mice, subsequent HDM exposure induced endothelial rolling, endothelial adhesion, and recruitment of platelets into airway walls, compared with sham-sensitized mice, via a CCR3-dependent mechanism in the absence of aggregation or interactions with leukocytes. Localization of singular, nonaggregated platelets occurs in lungs of patients with asthma. In allergic mice, platelet recruitment occurs via recognized vascular adhesive and migratory events, independently of leukocytes via a CCR3-dependent mechanism.

What does elevated TARC/CCL17 expression tell us about eosinophilic disorders?

Eosinophilic disorders encompass a large spectrum of heterogeneous diseases sharing the presence of elevated numbers of eosinophils in blood and/or tissues. Among these disorders, the role of eosinophils can vary widely, ranging from a modest participation in the disease process to the predominant perpetrator of tissue damage. In many cases, eosinophilic expansion is polyclonal, driven by enhanced production of interleukin-5, mainly by type 2 helper cells (Th2 cells) with a possible contribution of type 2 innate lymphoid cells (ILC2s). Among the key steps implicated in the establishment of type 2 immune responses, leukocyte recruitment toward inflamed tissues is particularly relevant. Herein, the contribution of the chemo-attractant molecule thymus and activation-regulated chemokine (TARC/CCL17) to type 2 immunity will be reviewed. The clinical relevance of this chemokine and its target, C-C chemokine receptor 4 (CCR4), will be illustrated in the setting of various eosinophilic disorders. Special emphasis will be put on the potential diagnostic, prognostic, and therapeutic implications related to activation of the TARC/CCL17-CCR4 axis.

Rhinovirus-induced CCL17 and CCL22 in Asthma Exacerbations and Differential Regulation by STAT6

The interplay of type-2 inflammation and antiviral immunity underpins asthma exacerbation pathogenesis. Virus infection induces type-2 inflammation-promoting chemokines CCL17 and CCL22 in asthma; however, mechanisms regulating induction are poorly understood. By using a human rhinovirus (RV) challenge model in human airway epithelial cells in vitro and mice in vivo, we assessed mechanisms regulating CCL17 and CCL22 expression. Subjects with mild to moderate asthma and healthy volunteers were experimentally infected with RV and airway CCL17 and CCL22 protein quantified. In vitro airway epithelial cell- and mouse-RV infection models were then used to define STAT6- and NF-κB-mediated regulation of CCL17 and CCL22 expression. Following RV infection, CCL17 and CCL22 expression was higher in asthma, which differentially correlated with clinical and immunological parameters. Air-liquid interface-differentiated primary epithelial cells from donors with asthma also expressed higher levels of RV-induced CCL22. RV infection boosted type-2 cytokine-induced STAT6 activation. In epithelial cells, type-2 cytokines and STAT6 activation had differential effects on chemokine expression, increasing CCL17 and suppressing CCL22, whereas NF-κB promoted expression of both chemokines. In mice, RV infection activated pulmonary STAT6, which was required for CCL17 but not CCL22 expression. STAT6-knockout mice infected with RV expressed increased levels of NF-κB-regulated chemokines, which was associated with rapid viral clearance. Therefore, RV-induced upregulation of CCL17 and CCL22 was mediated by NF-κB activation, whereas expression was differentially regulated by STAT6. Together, these findings suggest that therapeutic targeting of type-2 STAT6 activation alone will not block all inflammatory pathways during RV infection in asthma.

Airway epithelial integrin β4 suppresses allergic inflammation by decreasing CCL17 production

Airway epithelial cells (AECs) play a key role in asthma susceptibility and severity. Integrin β4 (ITGB4) is a structural adhesion molecule that is down-regulated in the airway epithelium of asthma patients. Although a few studies hint toward the role of ITGB4 in asthmatic inflammation pathogenesis, their specific resultant effects remain unexplored. In the present study, we determined the role of ITGB4 of AECs in the regulation of Th2 response and identified the underpinning molecular mechanisms. We found that ITGB4 deficiency led to exaggerated lung inflammation and AHR with higher production of CCL17 in house dust mite (HDM)-treated mice. ITGB4 regulated CCL17 production in AECs through EGFR, ERK and NF-κB pathways. EFGR-antagonist treatment or the neutralization of CCL17 both inhibited exaggerated pathological marks in HDM-challenged ITGB4-deficient mice. Together, these results demonstrated the involvement of ITGB4 deficiency in the development of Th2 responses of allergic asthma by down-regulation of EGFR and CCL17 pathway in AECs.

Sex differences in M2 polarization, chemokine and IL-4 receptors in monocytes and macrophages from asthmatics

Allergic asthma affects more women than men. It is mediated partially by IL-4/IL-13-driven polarization of monocyte-derived macrophages in the lung. We tested whether sex differences in asthma are due to differential IL-4 responsiveness and/or chemokine receptor expression in monocytes and monocyte-derived macrophages from healthy and allergic asthmatic men and women. We found female cells expressed M2 genes more robustly following IL-4 stimulation than male cells, as did cells from asthmatics than those from healthy controls. This likely resulted from increased expression ofγC, part of the type I IL-4 receptor, and reduced IL-4-induced SOCS1, a negative regulator of IL-4 signaling, in asthmatic compared to healthy macrophages. Monocytes from asthmatic women expressed more CX3CR1, which enhances macrophage survival. Our findings highlight how sex differences in IL-4 responsiveness and chemokine receptor expression may affect monocyte recruitment and macrophage polarization in asthma, potentially leading to new sex-specific therapies to manage the disease.

A multi-objective optimization method for identification of module biomarkers for disease diagnosis

Biomarker identification aims at finding a set of biological indicators that best discriminate biological samples of different phenotypes. In this paper, we take the module containing the significant disease-related genes and their interactions from biological networks as a module biomarker, and propose an evolutionary multi-objective optimization method to identify module biomarkers for disease diagnosis. To be specific, we take the classification accuracy on control and disease samples, the association with disease and the intra-link density in the module as the optimization objectives. To achieve the best performance, a novel population initiation strategy is tailored to generate dense-connected initial solutions, and a specific population update strategy is employed to direct the evolution towards the global optimums with abundant diversity. Experimental results show that our method outperforms the previous state-of-the-art disease diagnosis methods. Meantime, the detected biomarker module can reflect the basic and significant biological functions and has a great correlation with a disease phenotype.

CCL1 blockade alleviates human mesenchymal stem cell (hMSC)-induced pulmonary fibrosis in a murine sclerodermatous graft-versus-host disease (Scl-GVHD) model

Background

Human chronic graft-versus-host disease (CGVHD) shares clinical characteristics with a murine sclerodermatous GVHD (Scl-GVHD, B10.D2 → BALB/c) model that is characterized by skin and lung fibrosis. In this study, bone marrow- or adipose tissue-derived human mesenchymal stem cells (hMSCs) were injected into the Scl-GVHD mice to address their therapeutic effect on CGVHD.

Methods

Lethally irradiated BALB/c mice were transplanted with B10.D2 T cell-depleted bone marrow with or without spleen cells to generate Scl-GVHD. hMSCs were intravenously treated on days 3, 5, and 7 post-transplantation, and the control antibody or CCL1 blocking antibody was subcutaneously injected according to the same schedule as the hMSCs. Fourteen days after transplantation, the recipient mice were sacrificed, and their skin and lungs were analyzed.

Results

After the early injection of hMSCs after transplantation, the clinical and pathological severity of Scl-GVHD in the skin was significantly attenuated, whereas the pathological score was exacerbated in the lungs. hMSCs had migrated into the lungs, but not into the skin. CD11b monocyte/macrophages and CD4 T cells were markedly decreased in skin tissues, whereas there was an early recruitment of CD11b cells, and subsequently increased infiltration of CD4 T cells, in the lungs. Importantly, hMSCs persistently upregulated the expression of CCL1 in the lungs, but not in the skin. Concurrent treatment of hMSCs with a CCL1-blocking antibody alleviated the severity of the lung histopathology score and fibrosis with the preservation of the cutaneous protective effect against CGVHD. Infiltration of CD3 T cells and CD68 macrophages and upregulation of chemokines were also decreased in lung tissues, along with the recruitment of eosinophils and tissue IgE expression. In the skin, chemokine expression was further reduced after CCL1 blockade.

Conclusions

These data demonstrate that despite a protective effect against Scl-GVHD in the skin, administration of hMSCs exacerbated lung fibrosis associated with eosinophilia and airway inflammation through persistent CCL1 upregulation. CCL1 blockade offers a potential treatment of pulmonary complications induced after treatment with hMSCs.

Suppressive effect of environmental tobacco smoke on murine Th2 cell-mediated nasal eosinophilic inflammation

Background

Environmental tobacco smoke (ETS) exposure is recognized as a risk factor for the development of various respiratory diseases.

Objective

In this study, the effect of ETS on allergen-immunized and allergen-specific Th2 cell-transferred murine eosinophilic inflammation models and that of cigarette smoke extract (CSE) and nicotine on allergen-induced Th2 cell proliferation and interleukin (IL)-4 production were investigated.

Methods

Ovalbumin (OVA)-immunized and OVA-specific Th2 cell-transferred BALB/c mice were exposed to ETS and were challenged with OVA. Then, the number of inflammatory cells in the nasal mucosa and nasal hyperresponsiveness (NHR) were assessed. The effects of CSE and nicotine on the allergen-induced proliferative response of and IL-4 production by Th2 cells were determined in vitro.

Results

In OVA-immunized and Th2 cell-transferred mice, allergen-induced NHR and nasal eosinophil infiltration were significantly suppressed by ETS exposure, whereas the accumulation of neutrophils was rather enhanced. Allergen-specific Th2 cell proliferation and IL-4 production were inhibited by coculture with CSE. The same effects were induced by nicotine, though the effect on proliferation was relatively weak.

Conclusion

Regardless of its harmful effect, ETS suppresses NHR, probably through the inhibition of Th2 cell responses.

Thymus and Activation-regulated Chemokine as a Biomarker for IgG4-related Disease

High serum concentrations of thymus and activation-regulated chemokine (TARC) are observed in allergic diseases such as atopic dermatitis and bronchial asthma. Frequent allergic symptoms have been reported in patients with IgG4-related disease (IgG4-RD). We investigated the pathogenic role of TARC as a biomarker in IgG4-RD patients. We evaluated the serum concentrations of TARC from 29 IgG4-RD patients, 28 primary Sjögren syndrome (pSS) patients, and 23 healthy controls (HCs) by enzyme-linked immunosorbent assay (ELISA). We analyzed the correlations between the TARC concentrations and the subjects’ clinical parameters. To investigate the biological effect of TARC on the pathogenesis of IgG4-RD, we evaluated the in vitro induction of plasmablasts from IgG4-RD patients by TARC. The serum concentrations of TARC in the IgG4-RD patients were significantly higher than those of the pSS patients and HCs. The serum TARC concentration of the IgG4-RD group was positively correlated with the IgG4-RD responder index (IgG4-RD RI) score and with the number of organs involved, but it was not correlated with the serum IgG4 level or eosinophil number in the IgG4-RD patients’ peripheral blood. The patients who had lung involvement had higher serum TARC concentrations. In vitro, TARC clearly induced the formation of plasmablasts from the IgG4-RD patients’ peripheral blood mononuclear cells. Collectively, our data suggest that a systemic increment of TARC may contribute to the development of IgG4-RD through an aberrant induction of plasmablasts.

M1-like macrophages are potent producers of anti-viral interferons and M1-associated marker-positive lung macrophages are decreased during rhinovirus-induced asthma exacerbations

BACKGROUND

Macrophages (Mф) can be M1/M2 polarized by Th1/2 signals, respectively. M2-like Mф are thought to be important in asthma pathogenesis, and M1-like in anti-infective immunity, however their roles in virus-induced asthma exacerbations are unknown. Our objectives were (i) to assess polarised Mф phenotype responses to rhinovirus (RV) infection in vitro and (ii) to assess Mф phenotypes in healthy subjects and people with asthma before and during experimental RV infection in vivo.

METHODS

We investigated characteristics of polarized/unpolarized human monocyte-derived Mф (MDM, from 3-6 independent donors) in vitro and evaluated frequencies of M1/M2-like bronchoalveolar lavage (BAL) Mф in experimental RV-induced asthma exacerbation in 7 healthy controls and 17 (at baseline) and 18 (at day 4 post infection) people with asthma.

FINDINGS

We observed in vitro: M1-like but not M2-like or unpolarized MDM are potent producers of type I and III interferons in response to RV infection (P<0.0001), and M1-like are more resistant to RV infection (P<0.05); compared to M1-like, M2-like MDM constitutively produced higher levels of CCL22/MDC (P = 0.007) and CCL17/TARC (P<0.0001); RV-infected M1-like MDM were characterized as CD14+CD80+CD197+ (P = 0.002 vs M2-like, P<0.0001 vs unpolarized MDM). In vivo we found reduced percentages of M1-like CD14+CD80+CD197+ BAL Mф in asthma during experimental RV16 infection compared to baseline (P = 0.024).

INTERPRETATION

Human M1-like BAL Mф are likely important contributors to anti-viral immunity and their numbers are reduced in patients with allergic asthma during RV-induced asthma exacerbations. This mechanism may be one explanation why RV-triggered clinical and pathologic outcomes are more severe in allergic patients than in healthy subjects.

FUNDING

ERC FP7 Advanced grant 233015, MRC Centre Grant G1000758, Asthma UK grant 08-048, NIHR Biomedical Research Centre funding scheme, NIHR BRC Centre grant P26095, the Predicta FP7 Collaborative Project grant 260895, RSF grant 19-15-00272, Megagrant No 14.W03.31.0024.

Th2 cell differentiation from naive CD4+ T cells is enhanced by autocrine CC chemokines in atopic diseases

BACKGROUND

Chemokines are involved not only in regulating leucocyte recruitment, but also in other activities. However, functions other than cell recruitment remain poorly understood. We have already shown that the production of CC chemokine ligand (CCL)17 and CCL22 by antigen-stimulated naïve CD4⁺  T cells was higher in asthmatic patients than in healthy controls. However, the role of these chemokines in stimulated naïve CD4⁺ T cells remains unclear.

OBJECTIVE

To clarify the biological function of CCL17 and CCL22 on naïve CD4⁺ T, we examined effects of these two chemokines on naïve CD4⁺ T cells expressing CC chemokine receptor (CCR)4 (a receptor for CCL17 and CCL22) during differentiation of Th2 cells in asthmatic patients as allergic subjects.

METHODS

Naïve CD4⁺ T cells were prepared from healthy controls and patients with asthma. We analysed effect of CCL17 and CCL22, and blocking their receptor on differentiation of Th2 cells.

RESULTS

Production of CCL17 and CCL22 by activated naive CD4⁺ T cells under Th2 condition was much more in asthmatic patients than in healthy controls. Proliferation and survival of the Th2 differentiating cells and restimulation-induced IL-4 production were much greater in asthmatic patients than in healthy controls. These cell biological phenomena were inhibited by blockade of CCR4. The biological effects of exogenous CCL17 and CCL22 were apparently observed in both healthy controls and asthmatic patients. The effectiveness of these chemokines on naïve CD4⁺ T cells from healthy controls was stronger than those from asthmatic patients. We found that thymic stromal lymphopoietin (TSLP), a Th2 promoting chemokine, is involved in the activation of CD4⁺ naïve T cells via production of CCL17 and CCL22.

CONCLUSIONS AND CLINICAL RELEVANCE

These data suggest that CCL17 and CCL22 produced by TSLP-primed naïve CD4⁺ T cells in asthma might contribute to an increase in Th2 cells via autocrine loops.

Excision release of 5?hydroxycytosine oxidatively induced DNA base lesions from the lung genome by cat dander extract challenge stimulates allergic airway inflammation

BACKGROUND

Ragweed pollen extract (RWPE) induces TLR4-NFκB-CXCL-dependent recruitment of ROS-generating neutrophils to the airway and OGG1 DNA glycosylase-dependent excision of oxidatively induced 8-OH-Gua DNA base lesions from the airway epithelial cell genome. Administration of free 8-OH-Gua base stimulates RWPE-induced allergic lung inflammation. These studies suggest that stimulation of innate receptors and their adaptor by allergenic extracts initiates excision of a set of DNA base lesions that facilitate innate/allergic lung inflammation.

OBJECTIVE

To test the hypothesis that stimulation of a conserved innate receptor/adaptor pathway by allergenic extracts induces excision of a set of pro-inflammatory oxidatively induced DNA base lesions from the lung genome that stimulate allergic airway inflammation.

METHODS

Wild-type (WT), Tlr4KO, Tlr2KO, Myd88KO, and TrifKO mice were intranasally challenged once or repeatedly with cat dander extract (CDE), and innate or allergic inflammation and gene expression were quantified. We utilized GC-MS/MS to quantify a set of oxidatively induced DNA base lesions after challenge of naïve mice with CDE.

RESULTS

A single CDE challenge stimulated innate neutrophil recruitment that was partially dependent on TLR4 and TLR2, and completely on Myd88, but not TRIF. A single CDE challenge stimulated MyD88-dependent excision of DNA base lesions 5-OH-Cyt, FapyAde, and FapyGua from the lung genome. A single challenge of naïve WT mice with 5-OH-Cyt stimulated neutrophilic lung inflammation. Multiple CDE instillations stimulated MyD88-dependent allergic airway inflammation. Multiple administrations of 5-OH-Cyt with CDE stimulated allergic sensitization and allergic airway inflammation.

CONCLUSIONS AND CLINICAL RELEVANCE

We show for the first time that CDE challenge stimulates MyD88-dependent excision of DNA base lesions. Our data suggest that the resultant-free base(s) contribute to CDE-induced innate/allergic lung inflammation. We suggest that blocking the MyD88 pathway in the airways with specific inhibitors may be a novel targeted strategy of inhibiting amplification of innate and adaptive immune inflammation in allergic diseases by oxidatively induced DNA base lesions.

The Combination Therapy of Dietary Galacto-Oligosaccharides With Budesonide Reduces Pulmonary Th2 Driving Mediators and Mast Cell Degranulation in a Murine Model of House Dust Mite Induced Asthma

Background: Dietary non-digestible galacto-oligosaccharides (GOS) suppress allergic responses in mice sensitized and challenged with house dust mite (HDM). Budesonide is the standard therapy for allergic asthma in humans but is not always completely effective.

Aim: To compare the efficacy of budesonide or different doses of GOS alone or with a combination therapy of budesonide and GOS on HDM-allergic responses in mice.

Methods:BALB/c mice were sensitized and challenged with HDM, while fed a control diet or a diet supplemented with 1 or 2.5 w/w% GOS, and either or not oropharyngeally instilled with budesonide. Systemic and local inflammatory markers, such as mucosal mast cell protease-1 (mMCP-1) in serum, pulmonary CCL17, CCL22, and IL-33 concentrations and inflammatory cell influx in the bronchoalveolar lavage fluid (BALF) were determined.

Results: Budesonide or GOS alone suppressed the number of eosinophils in the BALF of HDM allergic mice whereas budesonide either or not combined with GOS lowered both eosinophil and lymphocyte numbers in the BALF of HDM-allergic mice. Both 1 w/w% and 2.5 w/w% GOS and/or budesonide suppressed serum mMCP-1 concentrations. However, budesonide nor GOS alone was capable of reducing Th2 driving chemokines CCL17, CCL22 and IL-33 protein levels in supernatants of lung homogenates of HDM allergic mice, whereas the combination therapy did. Moreover, IL-13 concentrations were only significantly suppressed in mice treated with budesonide while fed GOS. A similar tendency was observed for the frequency of GATA3⁺CD4⁺ Th2 and CD4⁺RORγt⁺ Th17 cells in the lungs of the allergic mice.

Conclusion: Dietary intervention using GOS may be a novel way to further improve the efficacy of anti-inflammatory drug therapy in allergic asthma by lowering Th2 driving mediators and mast cell degranulation.

Effects of anti-allergic drugs on T cell-mediated nasal hyperresponsiveness in a murine model of allergic rhinitis

BACKGROUND

We have recently demonstrated that T cell-mediated nasal hyperresponsiveness (NHR) is a representative pathophysiological feature of allergic rhinitis (AR). Although several anti-allergic drugs are used for the treatment of AR, the efficacy of these drugs on T cell-mediated NHR have not been elucidated. In these studies we investigated the effects of dexamethasone (Dex), montelukast (Mk), and chlorpheniramine (Chl) on NHR in antigen-immunized and antigen-specific Th2 cell-transferred mice.

METHODS

OVA-immunized BALB/c mice were treated with Dex, Mk, or Chl and challenged intranasally with OVA. We then assessed NHR, the number of inflammatory cells in the nasal lavage fluid (NALF), mRNA expression of Th2 cytokines in the nasal tissue, the population of CD3⁺CD4⁺ cells in the nasal lymphoid tissue (NALT), and antigen-specific serum IgE and IgG levels. Antigen-induced NHR and changes in antigen-specific T cells in the NALT were investigated in OVA-specific Th2 cell-transferred mice.

RESULTS

Dex significantly suppressed antigen-induced NHR, inflammatory cell infiltration, and IL-4, IL-5, IL-6, and IL-13 expression in immunized mice. Chl was completely ineffective, and only IL-13 expression was suppressed by Mk. None of these drugs affected IgE and IgG production. Antigen-induced NHR and the increase in antigen-specific T cells in the NALT of Th2 cell-transferred mice were inhibited by Dex, but not by Mk or Chl.

CONCLUSIONS

Steroids are effective for the reduction of NHR in AR by suppressing the accumulation of inflammatory cells, especially antigen-specific T cells.

RelB-Deficient Dendritic Cells Promote the Development of Spontaneous Allergic Airway Inflammation

RelB is a member of the NF-κB family, which is essential for dendritic cell (DC) function and maturation. However, the contribution of RelB to the development of allergic airway inflammation (AAI) is unknown. Here, we identify a pivotal role for RelB in the development of spontaneous AAI that is independent of exogenous allergen exposure. We assessed AAI in two strains of RelB-deficient (RelB^-/-) mice: one with a targeted deletion and one expressing a major histocompatibility complex transgene. To determine the importance of RelB in DCs, RelB-sufficient DCs (RelB^+/+ or RelB^-/-) were adoptively transferred into RelB^-/- mice. Both strains had increased pulmonary inflammation compared with their respective wild-type (RelB^+/+) and heterozygous (RelB^+/-) controls. RelB^-/- mice also had increased inflammatory cell influx into the airways, levels of chemokines (CCL2/3/4/5/11/17 and CXCL9/10/13) and T-helper cell type 2-associated cytokines (IL-4/5) in lung tissues, serum IgE, and airway remodeling (mucus-secreting cell numbers, collagen deposition, and epithelial thickening). Transfer of RelB^+/- CD11c⁺ DCs into RelB^-/- mice decreased pulmonary inflammation, with reductions in lung chemokines, T-helper cell type 2-associated cytokines (IL-4/5/13/25/33 and thymic stromal lymphopoietin), serum IgE, type 2 innate lymphoid cells, myeloid DCs, γδ T cells, lung Vβ13⁺ T cells, mucus-secreting cells, airway collagen deposition, and epithelial thickening. These data indicate that RelB deficiency may be a key pathway underlying AAI, and that DC-encoded RelB is sufficient to restore control of this inflammation.

Clinical implications of CD4+ T cell subsets in adult atopic asthma patients

Background

T cells play a central role in chronic inflammation in asthma. However, the roles of individual subsets of T cells in the pathology of asthma in patients remain to be better understood.

Methods

We investigated the potential signatures of T cell subset phenotypes in asthma using fresh whole blood from adult atopic asthma patients (n = 43) and non-asthmatic control subjects (n = 22). We further assessed their potential clinical implications by correlating asthma severity.

Results

We report four major features of CD4⁺ T cells in the blood of atopic asthma patients. First, patients had a profound increase of CCR7⁺ memory CD4⁺ T cells, but not CCR7⁻ memory CD4⁺ T cells. Second, an increase in CCR4⁺ CD4⁺ T cells in patients was mainly attributed to the increase of CCR7⁺ memory CD4⁺ T cells. Accordingly, the frequency of CCR4⁺CCR7⁺ memory CD4⁺ T cells correlated with asthma severity. Current common asthma therapeutics (including corticosteroids) were not able to affect the frequency of CCR4⁺CCR7⁺ memory CD4⁺ T cell subsets. Third, patients had an increase of Tregs, as assessed by measuring CD25, Foxp3, IL-10 and CTLA-4 expression. However, asthma severity was inversely correlated only with the frequency of CTLA-4⁺ CD4⁺ T cells. Lastly, patients and control subjects have similar frequencies of CD4⁺ T cells that express CCR5, CCR6, CXCR3, CXCR5, CD11a, or α4 integrin. However, the frequency of α4⁺ CD4⁺ T cells in patients correlated with asthma severity.

Conclusions

CCR4⁺CCR7⁺ memory, but not CCR4⁺CCR7⁻ memory, α4⁺, and CTLA4⁺ CD4⁺ T cells in patients show significant clinical implications in atopic asthma. Current common therapeutics cannot alter the frequency of such CD4⁺ T cell subsets in adult atopic asthma patients.

Electronic supplementary material

The online version of this article (10.1186/s13223-018-0231-3) contains supplementary material, which is available to authorized users.

Structural insights into chemokine CCL17 recognition by antibody M116

The homeostatic chemokine CCL17, also known as thymus and activation regulated chemokine (TARC), has been associated with various diseases such as asthma, idiopathic pulmonary fibrosis, atopic dermatitis and ulcerative colitis. Neutralization of CCL17 by antibody treatment ameliorates the impact of disease by blocking influx of T cells. Monoclonal antibody M116 derived from a combinatorial library shows potency in neutralizing CCL17-induced signaling. To gain insight into the structural determinants of antigen recognition, the crystal structure of M116 Fab was determined in complex with CCL17 and in the unbound form. Comparison of the structures revealed an unusual induced-fit mechanism of antigen recognition that involves cis-trans isomerization in two CDRs. The structure of the CCL17-M116 complex revealed the antibody binding epitope, which does not overlap with the putative receptor epitope, suggesting that the current model of chemokine-receptor interactions, as observed in the CXCR4-vMIP-II system, may not be universal.

A new antagonist for CCR4 attenuates allergic lung inflammation in a mouse model of asthma

CCR4 is highly expressed on Th2 cells. CCR4 ligands include CCL22 and CCL17. Chemokine-like factor 1 can also mediate chemotaxis via CCR4. We designed and synthetized novel CCR4 antagonists, which were piperazinyl pyridine derivatives, for disrupting the interaction between three ligands and CCR4. We also determined whether these novel CCR4 antagonists could alleviate allergic asthma in a mouse. For identifying the potent compounds in vitro, we used chemotaxis inhibition and competition binding assays induced by CCL22, CCL17 and one of CKLF1's C-terminal peptides, C27. We found compound 8a which showed excellent potency in blocking the interaction of CCR4 and its three ligands. For studying the specificity of compounds, we chose chemotaxis inhibition assays with different receptors and ligands. We found compound 8a had excellent receptor specificity and exerted few influence on the interaction of other receptors and their ligands. In the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, compound 8a had no obvious cytotoxicity till the higher concentration (16 μM). For determining the potency of compounds in blocking the interaction of CCR4 in vivo, we used the ovalbumin induced allergic asthma model in mice. Our study demonstrated that CCR4 blockaded by compound 8a effectively attenuated airway hyperresponsiveness, airway eosinophilia and Th2 cytokines.

Raw Cow's Milk Prevents the Development of Airway Inflammation in a Murine House Dust Mite-Induced Asthma Model

Epidemiological studies show an inverse relation between raw cow’s milk consumption and the development of asthma. This protective effect seems to be abolished by milk processing. However, evidence for a causal relationship is lacking, and direct comparisons between raw and processed milk are hardly studied. Therefore, this study investigated the preventive capacity of raw and heated raw milk on the development of house dust mite (HDM)-induced allergic asthma in mice. Six- to seven-week-old male BALB/c mice were intranasally (i.n.) sensitized with 1 µg HDM or PBS on day 0, followed by an i.n. challenge with 10 µg HDM or PBS on days 7–11. In addition, mice were fed 0.5 mL raw cow’s milk, heated raw cow’s milk, or PBS three times a week throughout the study, starting 1 day before sensitization. On day 14, airway hyperresponsiveness (AHR) in response to increasing doses of methacholine was measured to assess lung function. Bronchoalveolar lavage fluid (BALF) and lungs were furthermore collected to study the extent of airway inflammation. Raw milk prevented both HDM-induced AHR and pulmonary eosinophilic inflammation, whereas heated raw milk did not. Both milk types suppressed the Th2-polarizing chemokine CCL17 in lung homogenates and reduced lung Th2 and Th17 cell frequency. IL-4 and IL-13 production after ex vivo restimulation of lung T cells with HDM was also reduced by both milk types. However, local IL-5 and IL-13 concentrations were only suppressed by raw milk. These findings support the asthma-protective capacity of raw cow’s milk and show the importance of reduced local type 2 cytokine levels. Heated raw milk did not show an asthma-protective effect, which indicates the involvement of heat-sensitive components. Besides causal evidence, this study provides the basis for further mechanistic studies.

Increased sputum levels of thymus and activation-regulated chemokine in children with asthma not eosinophilic bronchitis

BACKGROUND

Thymus and activation-regulated chemokine (TARC), a member of the CC chemokine family, plays a crucial role in Th2-specific inflammation. We aimed to determine the concentration of sputum TARC in children with asthma and eosinophilic bronchitis (EB) and its relation with eosinophilic inflammation, pulmonary function, and bronchial hyper-responsiveness.

METHODS

In total, 90 children with asthma, 38 with EB, and 45 control subjects were enrolled. TARC levels were measured in sputum supernatants using an ELISA. We performed pulmonary function tests and measured exhaled fractional nitric oxide, eosinophil counts in blood, and sputum and serum levels of total IgE in all children.

RESULTS

Sputum TARC levels were significantly higher in children with asthma than in either children with EB (p=0.004) or the control subjects (p=0.014). Among patients with asthma, sputum TARC concentration was higher in children with sputum eosinophilia than in those without sputum eosinophilia (p=0.035). Sputum TARC levels positively correlated with eosinophil counts in sputum, serum total IgE levels, exhaled fractional nitric, and the bronchodilator response. Negative significant correlations were found between sputum TARC and FEV1/FVC (the ratio of forced expiratory volume in one second and forced expiratory vital capacity) or PC₂₀ (the provocative concentration of methacholine causing a 20% decrease in the FEV₁).

CONCLUSION

Elevated TARC levels in sputum were detected in children with asthma but not in children with EB. Sputum TARC could be a supportive marker for discrimination of asthma from EB in children showing characteristics of eosinophilic airway inflammation.

A multistrain probiotic formulation attenuates skin symptoms of atopic dermatitis in a mouse model through the generation of CD4+Foxp3+ T cells

BACKGROUND

Atopic dermatitis (AD) is characterized by chronic inflammation of the skin. AD develops mainly in infants and young children. It induces skin disorders and signals the initiation of the allergic march including allergic asthma and rhinitis. Probiotics modify intestinal microbial populations in a beneficial way for human and animal hosts by reducing inflammatory cytokines.

OBJECTIVE

As a result of their immunomodulatory properties, probiotics have been considered a promising therapeutic option for the prevention and treatment of AD.

DESIGN

In this study, we examined the effects of GI7, a potential probiotic mixture consisting of seven strains of bifidobacteria and lactic acid bacteria, on AD in a mouse model.

RESULTS

Administration of GI7 for 8 weeks reduced AD-like skin lesions and induced changes in the levels of serum markers such as immunoglobulin E and cytokines related to T helper (Th)1 and Th2 cells, and in skin barrier genes. Alleviation of AD seems to be associated with GI7-induced generation of CD4⁺Foxp3⁺ regulatory T cells.

CONCLUSIONS

The probiotic mixture may have potential to improve symptoms of AD.

Efficient Use of a Crude Drug/Herb Library Reveals Ephedra Herb As a Specific Antagonist for TH2-Specific Chemokine Receptors CCR3, CCR4, and CCR8

Chemokine receptors CCR3 and CCR4 are preferentially expressed by TH2 cells, mast cells, and/or eosinophils, all of which are involved in the pathogenesis of allergic diseases. Therefore, CCR3 and CCR4 have long been highlighted as potent therapeutic targets for allergic diseases. Japanese traditional herbal medicine Kampo consists of multiple crude drugs/herbs, which further consist of numerous chemical substances. Recent studies have demonstrated that such chemical substances appear to promising sources in the development of novel therapeutic agents. Based on these findings, we hypothesize that Kampo-related crude drugs/herbs would contain chemical substances that inhibit the cell migration mediated by CCR3 and/or CCR4. To test this hypothesis, we screened 80 crude drugs/herbs to identify candidate substances using chemotaxis assay. Among those tested, Ephedra Herb inhibited the chemotaxis mediated by both CCR3 and CCR4, Cornus Fruit inhibited that mediated by CCR3, and Rhubarb inhibited that mediated by CCR4. Furthermore, Ephedra Herb specifically inhibited the chemotaxis mediated by not only CCR3 and CCR4 but CCR8, all of which are selectively expressed by TH2 cells. This result led us to speculate that ephedrine, a major component of Ephedra Herb, would play a central role in the inhibitory effects on the chemotaxis mediated by CCR3, CCR4, and CCR8. However, ephedrine exhibited little effects on the chemotaxis. Therefore, we fractionated Ephedra Herb into four subfractions and examined the inhibitory effects of each subfraction. As the results, ethyl acetate-insoluble fraction exhibited the inhibitory effects on chemotaxis and calcium mobilization mediated by CCR3 and CCR4 most significantly. In contrast, chloroform-soluble fraction exhibited a weak inhibitory effect on the chemotaxis mediated by CCR8. Furthermore, maoto, one of the Kampo formulations containing Ephedra Herb, exhibited the inhibitory effects on the chemotaxis mediated by CCR3, CCR4, and CCR8. Taken together, our data suggest that these crude drugs/herbs might be useful sources to develop new drugs targeting TH2-mediated allergic diseases.

Targeting TSLP With shRNA Alleviates Airway Inflammation and Decreases Epithelial CCL17 in a Murine Model of Asthma

Airway epithelium defends the invasion from microorganisms and regulates immune responses in allergic asthma. Thymic stromal lymphopoietin (TSLP) from inflamed epithelium promotes maturation of dendritic cells (DCs) to prime Th2 responses via CCL17, which induces chemotaxis of CD4⁺ T cells to mediate inflammation. However, few studies have investigated the regulation of epithelial CCL17. In this study, we used shRNA against TSLP to clarify the role of TSLP in the airway inflammation and whether TSLP affects the airway inflammation via epithelial CCL17. Specific shTSLP was delivered by lentivirus and selected by the knockdown efficiency. Allergic mice were intratracheally pretreated with the lentivirus and followed by intranasal ovalbumin (OVA) challenges. The sera antibody levels, airway inflammation, airway hyper-responsiveness (AHR), cytokine levels in bronchoalveolar lavage fluids, and CCL17 expressions in lungs were determined. In vivo, TSLP attenuation reduced the AHR, decreased the airway inflammation, inhibited the maturations of DCs, and suppressed the migration of T cells. Furthermore, the expression of CCL17 was particularly decreased in bronchial epithelium. In vitro, CCL17 induction was regulated by TSLP. In conclusion, TSLP might coordinate airway inflammation partially via CCL17-mediated responses and this study provides the vital utility of TSLP to develop the therapeutic approach in allergic airway inflammation.

Chemokine receptors : therapeutic potential in asthma

Leukocyte infiltration of the lung is a characteristic feature of allergic asthma and it is thought that these cells are selectively recruited by chemokines. Extensive research has confirmed that chemokine receptors are expressed on the main cell types involved in asthma, including eosinophils, T helper type 2 cells, mast cells and even neutrophils. Moreover, animal experiments have outlined a functional role for these receptors and their ligands. Chemokines signal via seven-transmembrane spanning G-protein coupled receptors, which are favored targets of the pharmaceutical industry due to the possibility of designing small-molecule inhibitors. In fact, this family represents the first group of cytokines where small-molecule inhibitors have been designed. However, the search for efficient antagonists of chemokine/chemokine receptors has not been easy; a particular feature of the chemokine system is the number of molecules with overlapping functions and binding specificities, as well as the difficulty in reconciling the in vivo biologic functional validation of chemokines in rodent models with the development of antagonists which bind the human receptor, because of the lack of species cross-reactivity. The chemokines and their receptors that are active during allergic reactions are reviewed. Possible points of interaction that may be a target for development of new therapies, as well as the progress to date in developing inhibitors of key chemokine receptors for asthma therapy, are also discussed.

A strategy to discover decoy chemokine ligands with an anti-inflammatory activity

Excessive signaling by chemokines has been associated with chronic inflammation or cancer, thus attracting substantial attention as promising therapeutic targets. Inspired by chemokine-clearing molecules shaped by pathogens to escape the immune system, we designed a generic screening assay to discover chemokine neutralizing molecules (neutraligands) and unambiguously distinguish them from molecules that block the receptor (receptor antagonists). This assay, called TRIC-r, combines time-resolved intracellular calcium recordings with pre-incubation of bioactive compounds either with the chemokine or the receptor-expressing cells. We describe here the identification of high affinity neutraligands of CCL17 and CCL22, two chemokines involved in the Th2-type of lung inflammation. The decoy molecules inhibit in vitro CCL17- or CCL22-induced intracellular calcium responses, CCR4 endocytosis and human T cell migration. In vivo, they inhibit inflammation in a murine model of asthma, in particular the recruitment of eosinophils, dendritic cells and CD4⁺T cells. Altogether, we developed a successful strategy to discover as new class of pharmacological tools to potently control cell chemotaxis in vitro and in vivo.

Targeting chemokine receptors in disease--a case study of CCR4

Since their early 1990s, the chemokine receptor family of G protein-coupled receptors (GPCRs) has been the source of much pharmacological endeavour. Best known for their key roles in recruiting leukocytes to sites of infection and inflammation, the receptors present themselves as plausible drug targets for therapeutic intervention. In this article, we will focus our attention upon CC Chemokine Receptor Four (CCR4) which has been implicated in diseases as diverse as allergic asthma and lymphoma. We will review the discovery of the receptors and their ligands, their perceived roles in disease and the successful targeting of CCR4 by both small molecule antagonists and monoclonal antibodies. We will also discuss future directions and strategies for drug discovery in this field.

Differential dermal expression of CCL17 and CCL18 in tuberculoid and lepromatous leprosy

BACKGROUND

Leprosy is characterized by polar clinical, histologic and immunological presentations. Previous immunologic studies of leprosy polarity were limited by the repertoire of cytokines known at the time.

METHODOLOGY

We used a candidate gene approach to measure mRNA levels in skin biopsies from leprosy lesions. mRNA from 24 chemokines and cytokines, and 6 immune cell type markers were measured from 85 Nepalese leprosy subjects. Selected findings were confirmed with immunohistochemistry.

PRINCIPAL RESULTS

Expression of three soluble mediators (CCL18, CCL17 and IL-10) and one macrophage cell type marker (CD14) was significantly elevated in lepromatous (CCL18, IL-10 and CD14) or tuberculoid (CCL17) lesions. Higher CCL18 protein expression by immunohistochemistry and a trend in increased serum CCL18 in lepromatous lesions was observed. No cytokines were associated with erythema nodosum leprosum or Type I reversal reaction following multiple comparison correction. Hierarchical clustering suggested that CCL18 was correlated with cell markers CD209 and CD14, while neither CCL17 nor CCL18 were highly correlated with classical TH1 and TH2 cytokines.

CONCLUSIONS

Our findings suggest that CCL17 and CCL18 dermal expression is associated with leprosy polarity.

Recent progress in the development of antagonists to the chemokine receptors CCR3 and CCR4

INTRODUCTION

The chemokine receptors CCR3 and CCR4 have been shown to be important therapeutic targets for the treatment of a variety of diseases. Although only two chemokine receptor inhibitors have been approved so far, there are numerous compounds that are in various stages of development.

AREAS COVERED

In this review article, the authors provide an update on the progress made in the identification of antagonists against the chemokine receptors CCR3 and CCR4 from 2009 to the present. The rationale of writing this review article is to cover the most important approaches to identifying antagonists to these two receptors, which could prove to be useful therapeutics in treating proinflammatory diseases.

EXPERT OPINION

Pharmaceutical companies have expended a considerable amount of money and effort to identify potent inhibitors of CCR3 and CCR4 for the treatment of asthma and atopic diseases. Although a variety of compounds have been described and several have progressed into the clinic, none have so far made it as approved drugs. There are, however, novel approaches such as mogamulizumab, a monoclonal antibody to CCR4 currently is in clinical trials for cancer and ASM8, an antisense nucleotide to CCR3, which is in Phase II clinical trials for asthma that might still prove to be successful new therapeutics.

Distinct conformations of the chemokine receptor CCR4 with implications for its targeting in allergy

CC chemokine receptor 4 (CCR4) is expressed by Th2 and regulatory T cells and directs their migration along gradients of the chemokines CCL17 and CCL22. Both chemokines and receptor are upregulated in allergic disease, making CCR4 a therapeutic target for the treatment of allergy. We set out to assess the mechanisms underlying a previous report that CCL22 is a dominant ligand of CCR4, which may have implications for its therapeutic targeting. Human T cells expressing endogenous CCR4 and transfectants engineered to express CCR4 were assessed for receptor function, using assays of calcium release, chemotaxis, receptor endocytosis, and ligand binding. Despite the two ligands having equal potency in calcium flux and chemotaxis assays, CCL22 showed dominance in both receptor endocytosis assays and heterologous competitive binding assays. Using two different CCR4-specific Abs, we showed that CCR4 exists in at least two distinct conformations, which are differentially activated by ligand. A major population is activated by both CCL17 and CCL22, whereas a minor population is activated only by CCL22. Mutation of a single C-terminal residue K310 within a putative CCR4 antagonist binding site ablated activation of CCR4 by CCL17, but not by CCL22, despite having no effect on the binding of either ligand. We conclude that CCL17 and CCL22 are conformationally selective ligands of CCR4 and interact with the receptor by substantially different mechanisms. This finding suggests that the selective blockade of CCR4 in allergy may be feasible when one CCR4 ligand dominates, allowing the inhibition of Th2 signaling via one ligand while sparing regulatory T cell recruitment via another.

Internalization of the chemokine receptor CCR4 can be evoked by orthosteric and allosteric receptor antagonists

The chemokine receptor CCR4 has at least two natural agonist ligands, MDC (CCL22) and TARC (CCL17) which bind to the same orthosteric site with a similar affinity. Both ligands are known to evoke chemotaxis of CCR4-bearing T cells and also elicit CCR4 receptor internalization. A series of small molecule allosteric antagonists have been described which displace the agonist ligand, and inhibit chemotaxis. The aim of this study was to determine which cellular coupling pathways are involved in internalization, and if antagonists binding to the CCR4 receptor could themselves evoke receptor internalization. CCL22 binding coupled CCR4 efficiently to β-arrestin and stimulated GTPγS binding however CCL17 did not couple to β-arrestin and only partially stimulated GTPγS binding. CCL22 potently induced internalization of almost all cell surface CCR4, while CCL17 showed only weak effects. We describe four small molecule antagonists that were demonstrated to bind to two distinct allosteric sites on the CCR4 receptor, and while both classes inhibited agonist ligand binding and chemotaxis, one of the allosteric sites also evoked receptor internalization. Furthermore, we also characterize an N-terminally truncated version of CCL22 which acts as a competitive antagonist at the orthosteric site, and surprisingly also evokes receptor internalization without demonstrating any agonist activity. Collectively this study demonstrates that orthosteric and allosteric antagonists of the CCR4 receptor are capable of evoking receptor internalization, providing a novel strategy for drug discovery against this class of target.

Engagement of two distinct binding domains on CCL17 is required for signaling through CCR4 and establishment of localized inflammatory conditions in the lung

CCL17 (TARC) function can be completely abolished by mAbs that block either one of two distinct sites required for CCR4 signaling. This chemokine is elevated in sera of asthma patients and is responsible for establishing inflammatory sites through CCR4-mediated recruitment of immune cells. CCL17 shares the GPCR CCR4, with CCL22 (MDC) but these two chemokines differentially affect the immune response. To better understand chemokine mediated effects through CCR4, we have generated chimeric anti-mouse CCL17 surrogate antibodies that inhibit function of this ligand in vitro and in vivo. The affinities of the surrogate antibodies for CCL17 range from 685 pM for B225 to 4.9 nM for B202. One antibody, B202, also exhibits weak binding to CCL22 (KD∼2 µM) and no binding to CCL22 is detectable with the second antibody, B225. In vitro, both antibodies inhibit CCL17-mediated calcium mobilization, β-arrestin recruitment and chemotaxis; B202 can also partially inhibit CCL22-mediated β-arrestin recruitment. Both B202 and B225 antibodies neutralize CCL17 in vivo as demonstrated by reduction of methacholine-induced airway hyperreactivity in the A. fumigatus model of asthma. That both antibodies block CCL17 function but only B202 shows any inhibition of CCL22 function suggests that they bind CCL17 at different sites. Competition binding studies confirm that these two antibodies recognize unique epitopes that are non-overlapping despite the small size of CCL17. Taking into consideration the data from both the functional and binding studies, we propose that effective engagement of CCR4 by CCL17 involves two distinct binding domains and interaction with both is required for signaling.

International Union of Basic and Clinical Pharmacology. [corrected]. LXXXIX. Update on the extended family of chemokine receptors and introducing a new nomenclature for atypical chemokine receptors

Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145-176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human Genome Nomenclature Committee.

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 11.9 nM. 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.

Lung dendritic cells imprint T cell lung homing and promote lung immunity through the chemokine receptor CCR4

T cell trafficking into the lung is critical for lung immunity, but the mechanisms that mediate T cell lung homing are not well understood. Here, we show that lung dendritic cells (DCs) imprint T cell lung homing, as lung DC-activated T cells traffic more efficiently into the lung in response to inhaled antigen and at homeostasis compared with T cells activated by DCs from other tissues. Consequently, lung DC-imprinted T cells protect against influenza more effectively than do gut and skin DC-imprinted T cells. Lung DCs imprint the expression of CCR4 on T cells, and CCR4 contributes to T cell lung imprinting. Lung DC-activated, CCR4-deficient T cells fail to traffic into the lung as efficiently and to protect against influenza as effectively as lung DC-activated, CCR4-sufficient T cells. Thus, lung DCs imprint T cell lung homing and promote lung immunity in part through CCR4.

CCL17/thymus and activation-regulated chemokine induces calcitonin gene-related peptide in human airway epithelial cells through CCR4

BACKGROUND

Calcitonin gene-related peptide (CGRP) is a potent arterial and venous vasodilator. Increased airway epithelial cell expression of CGRP, together with increased CCL17 expression, was previously observed in a model of provoked asthma in atopic human subjects.

OBJECTIVE

We sought to determine whether CCL17 induces CCR4-dependent CGRP synthesis and secretion by human airway epithelial cells.

METHODS

Human airway epithelial cell lines (BEAS-2B and A549) and human primary airway cells were cultured with CCL17 or various other cytokines, and CGRP expression was measured by using RT-PCR, quantitative immunofluorescence, and enzyme immunoassay. CCR4 expression was determined in cultured cells by using flow cytometry and in bronchial biopsy specimens by using immunohistochemistry.

RESULTS

CCL17 induced a several thousand-fold increase in CGRP mRNA expression and released peptide product from BEAS-2B and A549 cells in a time- and concentration-dependent fashion. Concentration-dependent CCL17-induced release of CGRP by primary human airway epithelial cells was also observed. Under comparable conditions, CCL17 induced greater CGRP release from BEAS-2B cells than either IL-13, a cytokine mixture (TNF-α, GM-CSF, and IL-1), or CCL22. CCR4 was expressed by BEAS-2B and A549 cells and internalized after ligation with CCL17. CCL17-induced CGRP release was inhibited by a specific anti-CCR4 blocking antibody. Bronchial biopsy specimens obtained from healthy volunteers and asthmatic patients before and after provoked asthma all exhibited CCR4 staining of equivalent intensity, indicating that the receptor is constitutively expressed.

CONCLUSIONS

CCL17-induced, CCR4-dependent release of CGRP by human airway epithelial cells represents a novel inflammatory pathway and a possible target in patients with asthma and allergic disease.

Compartmentalized chemokine-dependent regulatory T-cell inhibition of allergic pulmonary inflammation

BACKGROUND

Induction of endogenous regulatory T (Treg) cells represents an exciting new potential modality for treating allergic diseases, such as asthma. Treg cells have been implicated in the regulation of asthma, but the anatomic location in which they exert their regulatory function and the mechanisms controlling the migration necessary for their suppressive function in asthma are not known. Understanding these aspects of Treg cell biology will be important for harnessing their power in the clinic.

OBJECTIVE

We sought to determine the anatomic location at which Treg cells exert their regulatory function in the sensitization and effector phases of allergic asthma and to determine the chemokine receptors that control the migration of Treg cells to these sites in vivo in both mice and human subjects.

METHODS

The clinical efficacy and anatomic location of adoptively transferred chemokine receptor-deficient CD4(+)CD25(+) forkhead box protein 3-positive Treg cells was determined in the sensitization and effector phases of allergic airway inflammation in mice. The chemokine receptor expression profile was determined on Treg cells recruited into the human airway after bronchoscopic segmental allergen challenge of asthmatic patients.

RESULTS

We show that CCR7, but not CCR4, is required on Treg cells to suppress allergic airway inflammation during the sensitization phase. In contrast, CCR4, but not CCR7, is required on Treg cells to suppress allergic airway inflammation during the effector phase. Consistent with our murine studies, human subjects with allergic asthma had an increase in CCR4-expressing functional Treg cells in the lungs after segmental allergen challenge.

CONCLUSION

The location of Treg cell function differs during allergic sensitization and allergen-induced recall responses in the lung, and this differential localization is critically dependent on differential chemokine function.

Nrf2 is a protective factor against oxidative stresses induced by diesel exhaust particle in allergic asthma

Epidemiological studies have shown that air pollutants, such as diesel exhaust particle (DEP), are implicated in the increased incidence of allergic airway disorders. In vitro studies of molecular mechanisms have focused on the role of reactive oxygen species generated directly and indirectly by the exposure to DEP. Antioxidants effectively reduce the allergic inflammatory effects induced by DEP both in vitro and in vivo. On the other hand, Nrf2 is a transcription factor essential for the inducible and/or constitutive expression of phase II and antioxidant enzymes. Disruption of Nrf2 enhances susceptibility to airway inflammatory responses and exacerbation of allergic inflammation induced by DEP in mice. Host responses to DEP are regulated by a balance between antioxidants and proinflammatory responses. Nrf2 may be an important protective factor against oxidative stresses induced by DEP in airway inflammation and allergic asthma and is expected to contribute to chemoprevention against DEP health effects in susceptible individuals.

Cultivated ginseng inhibits 2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions in NC/Nga mice and TNF-α/IFN-γ-induced TARC activation in HaCaT cells

Ginseng contains many bioactive constituents, including various ginsenosides that are believed to have anti-allergic, anti-oxidant, and immunostimulatory activities; however, its effects on atopic dermatitis (AD) remain unclear. In the current study, we hypothesized that cultivated ginseng (CG) would inhibit 2,4-dinitrochlorobenzene (DNCB)-induced AD-like skin lesions in NC/Nga mice by regulating the T helper (Th)1/Th2 balance. Also, CG inhibits TNF-α/IFN-γ-induced thymus- and activation-regulated chemokine (TARC) expression through nuclear factor-kappa B (NF-κB)-dependent signaling in HaCaT cells. CG ameliorated DNCB-induced dermatitis severity, serum levels of IgE and TARC, and mRNA expression of TARC, TNF-α, IFN-γ, IL-4, IL-5, and IL-13 in mice. Histopathological examination showed reduced thickness of the epidermis/dermis and dermal infiltration of inflammatory cells in the ears. Furthermore, CG suppressed the TNF-α/IFN-γ-induced mRNA expression of TARC in HaCaT cells. CG inhibited TNF-α/IFN-γ-induced NF-κB activation. These results suggest that CG inhibited the development of the AD-like skin symptoms by modulating Th1 and Th2 responses in the skin lesions in mice and TARC expression by suppressing TNF-α/IFN-γ-induced NF-κB activation in keratinocytes, and so may be a useful tool in the therapy of AD-like skin symptoms.

Regulatory T cells migrate to airways via CCR4 and attenuate the severity of airway allergic inflammation

We have previously shown that regulatory T (Treg) cells that accumulate in the airways of allergic mice upregulate CC-chemokine receptor 4 (CCR4) expression. These Treg cells suppressed in vitro Th2 cell proliferation but not type 2 cytokine production. In the current study, using a well-established murine model of allergic lung disease or oral tolerance, we evaluated the in vivo activity of Treg cells in allergic airway inflammation with special focus on CCR4 function. We found that allergic, but not tolerant, mice treated with anti-CD25 Ab showed increased airway eosinophilia and IL-5- or IL-4-producing Th2 cells when compared with untreated mice. Notably, mice with CCR4 deficiency displayed an augmented airway allergic inflammation compared with wild-type or CCR2 knockout (KO) mice. The allergic phenotype of CCR4KO mice was similar to that observed in anti-CD25-treated mice. The exacerbated allergic inflammation of CCR4KO mice was directly associated with an impaired migration of Treg cells to airways and augmented frequency of pulmonary Th2 cells. Adoptive transfer of CD25(+)CD4(+) T cells expressing high levels of CCR4, but not CCR4KO CD25(+)CD4(+) T cells, attenuated the severe airway Th2 response of CCR4KO mice. Our results show that CCR4 is critically involved in the migration of Treg cells to allergic lungs that, in turn, attenuate airway Th2 activation and allergic eosinophilic inflammation.

Experimental advances in understanding allergic airway inflammation

Asthma is largely an inflammatory disease, with the development of T cell mediated inflammation in the lung following exposure to allergen or other precipitating factors. Currently, the major therapies for this disease are directed either at relief of bronchoconstriction (ie beta-agonists) or are non-specific immunomodulators (ie, corticosteroids). While much attention has been paid to factors that regulate the initiation of an inflammatory response, chronic inflammation may also be due to defects in regulatory mechanisms that limit or terminate immune responses. In this review, we explore the elements controlling both the recruitment of T cells to the lung and their function. Possibilities for future therapeutic intervention are highlighted.

Dual Role of Th17 Cytokines, IL-17A,F, and IL-22 in Allergic Asthma

The proinflammatory role of T helper (Th) 17 cells and therefore of its cytokines, IL-17 (IL-17A), IL-17F, and IL-22, in autoimmune disorders has been favored, although there is evidence that not only IL-17A but also IL-17F and IL-22 have a dual role as negative regulators. Here we review the concept of the dual function of IL-17A, IL-17F, and IL-22 in the light of recent strategies to use neutralization of these cytokines as potential alternative to neutralizing TNF and IL-1 treatments in chronic inflammatory disorders. Expectedly, in allergic lung inflammation, neutralization of IL-17A inhibited neutrophil recruitment. However, this IL-17A antibody treatment concomitantly increased eosinophil recruitment by neutralizing IL-17A’s dual role as negative regulator. IL-17A negatively regulated dendritic cell function and activation of T helper cell (Th)2 cytokine production. Furthermore, IL-17A inhibited Th2-characteristic chemokine and adhesion molecule expression. On a mechanistic level, IL-17A acted on IκB-β by preventing degradation and in turn leading to reduced NF-κB activation or IL-17A inhibited transcription factor IRF-1. Therefore, anti-IL-17A therapy, although presenting a promising lead in chronic inflammatory disorders, bears a potential risk of exacerbating allergic asthma.

Effect of Alpinia katsumadai Hayata on House Dust Mite-Induced Atopic Dermatitis in NC/Nga Mice

We evaluated the effects of Alpinia katsumadai Hayata (AKH, Zingiberaceae) extract on the production of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) in RAW 264.7 cells, thymus- and-activation-regulated chemokine (TARC/CCL17) in HaCaT cells, and histamine level in HMC-1 cells. In an in vivo experiment, atopic dermatitis was induced by topical application of house dust mites for 4 weeks, and the protective effects of AKH was investigated by measuring the severity of the skin reaction on the back and ears, and plasma levels of immunoglobulin E (IgE) and histamine. AKH extract suppressed the production of NO and PGE(2) in RAW 264.7 cells, TARC in HaCaT cells, and histamine in HMC-1 cells in a dose-dependent manner. In in vivo experiments, the severity of dermatitis, including erythema/hemorrhage, edema, erosion and scaling, and plasma levels of IgE, and histamine were lower in NC/Nga mice with atopic dermatitis, treated with AKH extract than in untreated mice. AKH extract reduced the histological manifestations of atopic dermatitis-like skin lesions such as erosion, hyperplasia of the epidermis and dermis, and inflammatory cell infiltration on the skin of the back and ear. These results suggest that AKH inhibits the development of house dust mite-induced atopic dermatitis in NC/Nga mice.