Selective suppression of Th2-mediated airway eosinophil infiltration by low-molecular weight CCR3 antagonists

Studying allosteric regulation of chemokines and antagonists using a nanoscale hCCR3 receptor sensor

CC chemokine receptor-3 (hCCR3), a G protein-coupled receptor (GPCR) expressed predominantly on eosinophils, is an important drug target. However, it was unclear how chemokine ligands, activators and antagonists recognize hCCR3, and quantitative measurements of hCCR3 inhibition or activation were rare. This study constructed a nanogold receptor sensor using hCCR3 as the molecular recognition element and horseradish peroxidase as the signal amplifier. We quantified the kinetic antagonism between chemokines and hCCR3 before and after adding hCCR3 antagonists. A molecular docking study was carried out to investigate how hCCR3 and its ligands work. The study results indicate chemokines interact with hCCR3 at low concentrations, and reversible hCCR3 inhibitors solely inhibit hCCR3, not CCLs. Moreover, a quantitative evaluation of hCCR3 chemokine activators and their antagonists was carried out using a directed weighted network. This offers a novel approach to quantitatively evaluate chemokine-receptor activation and antagonism together. This research could potentially offer new insights into the mechanisms of action of chemokines and drug screening.

Generation of reporter mice for detecting the transcriptional activity of nuclear factor of activated T cells

Nuclear factor of activated T cells (NFAT) is a transcription factor essential for immunological and other biological responses. To develop analyzing system for NFAT activity in vitro and in vivo, we generated reporter mouse lines introduced with NFAT-driven enhanced green fluorescent protein (EGFP) expressing gene construct. Six tandem repeats of -286 to -265 of the human IL2 gene to which NFAT binds in association with its co-transcription factor, activator protein (AP)-1, was conjunct with thymidine kinase minimum promoter and following EGFP coding sequence. Upon introduction of the resulting reporter cassette into C57BL/6 fertilized eggs, the transgenic mice were obtained. Among 7 transgene-positive mice in 110 mice bone, 2 mice showed the designated reporter mouse character. Thus, the EGFP fluorescence of CD4+ and CD8+ T cells in these mice was enhanced by stimulation through CD3 and CD28. Each of phorbol 12-myristate 13-acetate (PMA) and ionomycin (IOM) stimulation weakly but their combined stimulation strongly enhanced EGFP expression. The stimulation-induced EGFP upregulation was also observed following T cell subset differentiation in a different manner. The EGFP induction by PMA + IOM stimulation was more potent than that by CD3/CD28 stimulation in helper T (Th)1, Th2, Th9, and regulatory T cells, while both stimulation conditions displayed the equivalent EGFP induction in Th17 cells. Our NFAT reporter mouse lines are useful for analyzing stimulation-induced transcriptional activation mediated by NFAT in cooperation with AP-1 in T cells.

CCR3 blockage elicits polyploidization associated with the signatures of epithelial-mesenchymal transition in carcinoma cell lines

Malignant features such as the acquisition of metastatic ability, stemness of cells, and therapeutic resistance of cancer cells are associated with epithelial-mesenchymal transition (EMT) accompanied by changes in motility and morphology. Recent reports implicated that the formation of polyploid giant cancer cells (PGCCs) in human malignancy correlated with the EMT processes. Chemokines are often involved in the regulation of cancer cell migration into tissues, and various types of human cancers exhibit enhanced expression of chemokine receptors, which could augment intrinsic potentials such as invasive activity, proliferating ability, and survival capacity in cancer cells. Nevertheless, the contribution of CCR3 in malignant cancer cells is controversial because it is a well-known primal receptor for the migration of eosinophils, one of the cells of the innate immune system. Here, we explored the blockage of chemokine receptor CCR3 in carcinoma cell lines and found that inhibition of CCR3 induced the formation of polyploid giant cells and stabilization of β-catenin via the PI3K/Akt/GSK-3β signaling pathway, which are processes associated with EMT. As a result of CCR3 inhibition, converted cells acquired enhanced mobile and proliferation abilities. In summary, these data indicate that modulation of the CCR3/PI3K/Akt/GSK-3β signaling pathway regulates polyploidization associated with the EMT processes.

Potent CCR3 Receptor Antagonist, SB328437, Suppresses Colonic Eosinophil Chemotaxis and Inflammation in the Winnie Murine Model of Spontaneous Chronic Colitis

Eosinophils and their regulatory molecules have been associated with chronic intestinal inflammation and gastrointestinal dysfunctions; eosinophil accumulation in the gut is prominent in inflammatory bowel disease (IBD). The chemokine receptor CCR3 plays a pivotal role in local and systemic recruitment and activation of eosinophils. In this study, we targeted CCR3-ligand interactions with a potent CCR3 receptor antagonist, SB328437, to alleviate eosinophil-associated immunological responses in the Winnie model of spontaneous chronic colitis. Winnie and C57BL/6 mice were treated with SB328437 or vehicle. Clinical and histopathological parameters of chronic colitis were assessed. Flow cytometry was performed to discern changes in colonic, splenic, circulatory, and bone marrow-derived leukocytes. Changes to the serum levels of eosinophil-associated chemokines and cytokines were measured using BioPlex. Inhibition of CCR3 receptors with SB328437 attenuated disease activity and gross morphological damage to the inflamed intestines and reduced eosinophils and their regulatory molecules in the inflamed colon and circulation. SB328437 had no effect on eosinophils and their progenitor cells in the spleen and bone marrow. This study demonstrates that targeting eosinophils via the CCR3 axis has anti-inflammatory effects in the inflamed intestine, and also contributes to understanding the role of eosinophils as potential end-point targets for IBD treatment.

Critical Involvement of CD44 in T Helper Type 2 Cell-Mediated Eosinophilic Airway Inflammation in a Mouse Model of Acute Asthma

Interactions between CD44 and hyaluronan (HA) are crucial for recruiting leukocytes to inflamed tissues. This review summarizes findings from our studies of the roles of CD44-HA interactions in leukocyte trafficking, with a particular focus on airway T helper type 2 (Th2) cells in mouse models of acute asthma. In a mite allergen-induced model of acute asthma, intraperitoneal injection of anti-CD44 monoclonal antibodies blocked lymphocytes and eosinophils from accumulating in the lung, and suppressed both the antigen-induced increase in Th2 cytokines in the bronchoalveolar lavage fluid (BALF) and airway hyperresponsiveness (AHR). CD44 deficiency was associated with decreased mite allergen-induced Th2 cell-mediated airway inflammation and AHR in sensitized mice. Asthmatic responses to antigen-sensitized splenic CD4+ T cells transferred from CD44-deficient mice were weaker than in wild-type mice. Administration of anti-CD44 monoclonal antibodies preferentially suppressed the airway accumulation of antigen-specific Th2 cells induced by antigen challenge, without affecting Th1 and Th17 cells. Increased HA-binding ability of CD44 and expression of Neu1 sialidase were observed on antigen-specific Th2 cells compared with antigen-specific Th1 and Th17 cells. Finally, in a mouse model of acute asthma, neuraminidase 1-deficient SM/J mice exhibited a lower Th2 cytokine concentration and a lower absolute Th2 cell number in the BALF, as well as an attenuated AHR. Our findings indicate that CD44 critically contributes to the antigen challenge-induced airway accumulation of antigen-specific Th2 cells, without affecting Th1 and Th17 cells, in mice. Furthermore, neuraminidase 1 activity is necessary for the interaction between HA and CD44, and Th2 cell-mediated airway inflammation.

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.

Novel peptide nanoparticle-biased antagonist of CCR3 blocks eosinophil recruitment and airway hyperresponsiveness

BACKGROUND

Chemokine signaling through CCR3 is a key regulatory pathway for eosinophil recruitment into tissues associated with allergic inflammation and asthma. To date, none of the CCR3 antagonists have shown efficacy in clinical trials. One reason might be their unbiased mode of inhibition that prevents receptor internalization, leading to drug tolerance.

OBJECTIVE

We sought to develop a novel peptide nanoparticle CCR3 inhibitor (R321) with a biased mode of inhibition that would block G protein signaling but enable or promote receptor internalization.

METHODS

Self-assembly of R321 peptide into nanoparticles and peptide binding to CCR3 were analyzed by means of dynamic light scattering and nuclear magnetic resonance. Inhibitory activity on CCR3 signaling was assessed in vitro by using flow cytometry, confocal microscopy, and Western blot analysis in a CCR3+ eosinophil cell line and blood eosinophils. In vivo effects of R321 were assessed by using a triple-allergen mouse asthma model.

RESULTS

R321 self-assembles into nanoparticles and binds directly to CCR3, altering receptor function. Half-maximal inhibitory concentration values for eotaxin-induced chemotaxis of blood eosinophils are in the low nanomolar range. R321 inhibits only the early phase of extracellular signal-regulated kinase 1/2 activation and not the late phase generally associated with β-arrestin recruitment and receptor endocytosis, promoting CCR3 internalization and degradation. In vivo R321 effectively blocks eosinophil recruitment into the blood, lungs, and airways and prevents airway hyperresponsiveness in a mouse eosinophilic asthma model.

CONCLUSIONS

R321 is a potent and selective antagonist of the CCR3 signaling cascade. Inhibition through a biased mode of antagonism might hold significant therapeutic promise by eluding the formation of drug tolerance.

Targeting eotaxin-1 and CCR3 receptor alleviates enteric neuropathy and colonic dysfunction in TNBS-induced colitis in guinea pigs

BACKGROUND

The accumulation of eosinophils is mediated by the chemokine receptor-3 (CCR3)-eotaxin axis. Increased expression of eotaxin and its receptor is associated with inflammatory bowel disease (IBD). Activation of eosinophils causes the release of cationic proteins that are neurotoxic such as eosinophil-derived neurotoxin (EDN). Damage to enteric neurons alters neurally controlled functions of the gut correlated with intestinal inflammation. We hypothesized that inhibition of the CCR3-eotaxin axis will prevent inflammation-induced functional changes to the gastrointestinal tract.

METHODS

Hartley guinea pigs were administered with trinitrobenzene sulfonate (TNBS; 30 mg/kg in 30% ethanol) intrarectally to induce colitis. A CCR3 receptor antagonist (SB 328437 [SB3]) was injected intraperitoneally 1 hour postinduction of colitis. Animals were euthanized 7 days post-treatment and colon tissues were collected for ex vivo studies. The EDN-positive eosinophils in the colon, indicating eosinophil activation, were quantified by immunohistochemistry. Effects of SB3 treatment on gross morphological damage, enteric neuropathy, and colonic dysmotility were determined by histology, immunohistochemistry, and organ bath experiments.

KEY RESULTS

The number of EDN-positive eosinophils was significantly increased in the lamina propria in close proximity to myenteric ganglia in inflamed colon. The TNBS-induced inflammation caused significant damage to colonic architecture and inhibition of colonic motility. Treatment with SB3 antagonist attenuated inflammation-associated morphological damage in the colon, reduced infiltration of EDN-positive eosinophils and restored colonic motility to levels comparable to control and sham-treated guinea pigs.

CONCLUSION & INFERENCES

This is the first study demonstrating that inhibition of CCR3-eotaxin axis alleviates enteric neuropathy and restores functional changes in the gut associated with TNBS-induced colitis.

Differential Contribution of Adhesion Molecules to Th1 and Th2 Cell-Mediated Lung and Bowel Inflammation

CD4⁺ T cells play a critical role in the development of allergic inflammation in several target organs. Various adhesion molecules are involved in the local recruitment of T cells and other inflammatory cells. We investigated the differential contribution of adhesion molecules to T helper 1 (Th1) and Th2 cell-mediated allergic lung and bowel inflammation by employing their neutralizing antibodies. BALB/c mice transferred with in vitro-differentiated antigen-specific Th1 and Th2 cells were intratracheally or intrarectally challenged with a relevant antigen. Infiltration of infused T cells occurred, along with the accumulation of neutrophils and eosinophils in the lungs of Th1 and Th2 cell-transferred recipients, respectively. Th1-mediated neutrophil and Th2-mediated eosinophil accumulation in the large intestine, which occurred after intrarectal challenge with the antigen, was indicated by the significant elevation of myeloperoxidase (MPO) and eosinophil peroxidase (EPO) activity. Blocking experiments with neutralizing antibodies indicated that intercellular cell adhesion molecule (ICAM)-1; vascular cell adhesion molecule (VCAM)-1; and αL, β2, and β7 integrins participate in the accumulation of Th2 cells and eosinophils in the lungs. In contrast, the migration of Th1 cells and neutrophils was diminished by blockage of αL/β2-integrin and ICAM-1, respectively. Mucosal addressin cell adhesion molecule (MadCAM)-1, vascular cell adhesion molecule (VCAM)-1, α4, β1, and β7 contributed to Th1-mediated neutrophilic inflammation in the bowel, though only MadCAM-1, α4, αL, and β2 were involved in Th2-mediated eosinophilic inflammation. We conclude that distinct sets of adhesion molecules are involved in Th1- and Th2-mediated allergic lung and bowel inflammation.

Neutrophilia, gelatinase release and microvascular leakage induced by human mast cell tryptase in a mouse model: Lack of a role of protease-activated receptor 2 (PAR2)

BACKGROUND

Tryptase, the most abundant protease of the human mast cell, has been implicated as a key mediator of allergic inflammation that acts through activation of PAR2.

OBJECTIVES

To investigate the contribution of PAR2 in the pro-inflammatory actions mediated by tryptase in a mice model.

METHODS

We have injected recombinant human βII-tryptase into the peritoneum of PAR2-deficient and wild-type C57BL/6 mice. After 6, 12 and 24 hours, mice were killed, peritoneal lavage performed and inflammatory changes investigated.

RESULTS

Tryptase stimulated an increase in neutrophil numbers in the peritoneum, but responses did not differ between PAR2-deficient and wild-type mice. Heat inactivation of tryptase or pre-incubation with a selective tryptase inhibitor reduced neutrophilia, but neutrophil accumulation was not elicited with a peptide agonist of PAR2 (SLIGRL-NH2 ). Zymography indicated that tryptase stimulated the release of matrix metalloproteinases (MMP) 2 and 9 in the peritoneum of both mouse strains. Studies involving immunomagnetic isolation of neutrophils suggested that neutrophils represent the major cellular source of tryptase-induced MMP2 and MMP9. At 24 hours after tryptase injection, there was increased microvascular leakage as indicated by high levels of albumin in peritoneal lavage fluid, and this appeared to be partially abolished by heat-inactivating tryptase or addition of a protease inhibitor. There was no corresponding increase in levels of histamine or total protein. The extent of tryptase-induced microvascular leakage or gelatinase release into the peritoneum did not differ between PAR2-deficient and wild-type mice.

CONCLUSIONS

Our findings indicate that tryptase is a potent stimulus for neutrophil accumulation, MMP release and microvascular leakage. Although these actions required an intact catalytic site, the primary mechanism of tryptase in vivo would appear to involve processes independent of PAR2.

Th9 cells induce steroid-resistant bronchial hyperresponsiveness in mice

BACKGROUND

Reduced 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.

METHODS

Ovalbumin (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.

RESULTS

In 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.

CONCLUSIONS

In 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.

Th9 cells elicit eosinophil-independent bronchial hyperresponsiveness in mice

BACKGROUND

Airway accumulation of eosinophils and bronchial hyperresponsiveness (BHR) are prominent features of bronchial asthma, though the contribution of eosinophils to the development of BHR is controversial. Similar to Th2 cell-mediated pathology, Th9 cells, characterized by IL-9-producing activity, have been demonstrated to induce airway eosinophilia and BHR. In this study, we investigated the role of eosinophils in Th9-mediated BHR by employing Th9 cell-transferred murine airway inflammation model.

METHODS

Ovalbumin (OVA)-specific Th2 and Th9 cells were differentiated from CD4(+) T cells of DO11.10/RAG-2(-/-) mice in vitro and cytokine-producing activity of those cells was examined. BALB/c mice were adoptively transferred with Th2 or Th9 cells and challenged with OVA. Then, the number of inflammatory cells in bronchoalveolar lavage fluid and bronchial responsiveness to inhaled methacholine were determined.

RESULTS

Both in Th2 and Th9 cell-transferred mice, substantial accumulation of eosinophils in the lungs and BHR were induced by challenge with specific antigen. Nevertheless, an essential and dispensable role of eosinophils in Th2- and Th9-mediated BHR, respectively, was demonstrated by employing eosinophil-deficient mice. The neutralization of IL-9 as well as deficiency of IL-10 in the donor cells did not affect Th9-mediated BHR.

CONCLUSIONS

In contrast to Th2-mediated and eosinophil-dependent BHR, Th9 could induce BHR independently from eosinophils and its characteristic cytokines, IL-9 and IL-10.

Neolignans from the Arils of Myristica fragrans as Potent Antagonists of CC Chemokine Receptor 3

CC chemokine receptor 3 (CCR3) is expressed selectively in eosinophils, basophils, and some Th2 cells and plays a major role in allergic diseases. A methanol extract from the arils of Myristica fragrans inhibited CC chemokine ligand 11-induced chemotaxis in CCR3-expressing L1.2 cells at 100 μg/mL. From this extract, eight new neolignans, maceneolignans A-H (1-8), were isolated, and their stereostructures were elucidated from their spectroscopic values and chemical properties. Of those constituents, compounds 1, 4, 6, and 8 and (+)-erythro-(7S,8R)-Δ(8')-7-hydroxy-3,4-methylenedioxy-3',5'-dimethoxy-8-O-4'-neolignan (11), (-)-(8R)-Δ(8')-3,4-methylenedioxy-3',5'-dimethoxy-8-O-4'-neolignan (17), (+)-licarin A (20), nectandrin B (25), verrucosin (26), and myristicin (27) inhibited CCR3-mediated chemotaxis at a concentration of 1 μM. Among them, 1 (EC50 1.6 μM), 6 (1.5 μM), and 8 (1.4 μM) showed relatively strong activities, which were comparable to that of a synthetic CCR3 selective antagonist, SB328437 (0.78 μM).

Essential Contribution of CD4+ T Cells to Antigen-Induced Nasal Hyperresponsiveness in Experimental Allergic Rhinitis

Nasal hyperresponsiveness (NHR) is a characteristic feature of allergic rhinitis (AR); however, the pathogenesis of NHR is not fully understood. In this study, during the establishment of an experimental AR model using ovalbumin-immunized and -challenged mice, augmentation of the sneezing reaction in response to nonspecific proteins as well as a chemical stimulant was detected. Whether NHR is independent of mast cells and eosinophils was determined by using mast cell- and eosinophil-deficient mice. NHR was suppressed by treatment with anti-CD4 antibody, suggesting the pivotal contribution of CD4+ T cells. Furthermore, antigen challenge to mice to which in vitro-differentiated Th1, Th2, and Th17 cells but not naïve CD4+ T cells had been adoptively transferred led to the development of equivalent NHR. Since antigen-specific IgE and IgG were not produced in these mice and since antigen-specific IgE-transgenic mice did not develop NHR even upon antigen challenge, humoral immunity would be dispensable for NHR. CD4+ T cells play a crucial role in the pathogenesis of AR via induction of NHR, independent of IgE-, mast cell-, and eosinophil-mediated responses.

Eosinophils as a pharmacological target for the treatment of allergic diseases

Eosinophils are innate immune cells and active players in inflammatory responses. Their activation and increased levels in the blood and at specific sites are associated with parasitic infections and several inflammatory conditions, notably allergic diseases in which eosinophils are considered to be damaging cells. Intervention targeting eosinophils is thought to prevent and/or limit irreversible organ damage and other eosinophil-associated disorders like hypereosinophilic syndromes, some cancers and autoimmune diseases. Several eosinophil-targeted therapeutic agents which block specific steps in eosinophil differentiation, migration and activation have recently been developed, showing encouraging results and new insights into their specific role in allergy. Here, we review some potentially effective drug compounds, their drawbacks and future prospective focusing on allergic diseases.

Selective suppression of Th2 cell-mediated lung eosinophilic inflammation by anti-major facilitator super family domain containing 10 monoclonal antibody

BACKGROUND

The eosinophil is deeply associated with the pathogenesis of bronchial asthma and other allergic diseases. We recently identified a novel eosinophil-specific cell surface molecule, major facilitator super family domain containing 10 (Mfsd10). A monoclonal antibody (mAb) against Mfsd10 (M2) showed selective binding and neutralizing activities for eosinophils. However, the relative potency of the blockage of Mfsd10 and other eosinophil-specific molecules for the treatment of allergic diseases has not been evaluated. Therefore, in this study, the effects of M2 and an anti-Siglec-F mAb on antigen-immunized and antigen-specific Th2 cell-transferred murine eosinophilic inflammation models were comparatively investigated.

METHODS

Ovalbumin (OVA)-specific Th2 cells were differentiated from naïve CD4+ T cells of DO11.10/RAG-2-/- mice in vitro and cytokine producing activity of the Th2 cells was examined. OVA-immunized and Th2 cell-transferred BALB/c mice were treated with M2 or anti-Siglec-F and challenged with OVA. Then the number of inflammatory cells and the concentration of IL-5 in the bronchoalveolar lavage fluid (BALF) were determined.

RESULTS

Antigen-specific Th2 cells produced large amounts of IL-4, IL-5 and IL-13 but not IL-17A or IFN-γ. Administration of M2 significantly suppressed antigen-induced lung eosinophil infiltration both in OVA-immunized and Th2 cell-transferred mice. The potency as well as selectivity of M2 for down-regulating eosinophils was quite similar to that of anti-Siglec-F. Both mAbs did not affect antigen-induced IL-5 production in the lungs.

CONCLUSIONS

Mfsd10 as well as Siglec-F could be an effective target to treat eosinophil-related disorders including bronchial asthma.

Distinct chemokine receptor axes regulate Th9 cell trafficking to allergic and autoimmune inflammatory sites

Migration of Th cells to peripheral sites of inflammation is essential for execution of their effector function. The recently described Th9 subset characteristically produces IL-9 and has been implicated in both allergy and autoimmunity. Despite this, the migratory properties of Th9 cells remain enigmatic. In this study, we examined chemokine receptor usage by Th9 cells and demonstrate, in models of allergy and autoimmunity, that these cells express functional CCR3, CCR6, and CXCR3, chemokine receptors commonly associated with other, functionally opposed effector Th subsets. Most Th9 cells that express CCR3 also express CXCR3 and CCR6, and expression of these receptors appears to account for the recruitment of Th9 cells to disparate inflammatory sites. During allergic inflammation, Th9 cells use CCR3 and CCR6, but not CXCR3, to home to the peritoneal cavity, whereas Th9 homing to the CNS during experimental autoimmune encephalomyelitis involves CXCR3 and CCR6 but not CCR3. To our knowledge, these data provide the first insights into regulation of Th9 cell trafficking in allergy and autoimmunity.

Graft-versus-host disease reduces regulatory T-cell migration into the tumour tissue

The therapeutic principle of allogeneic haematopoietic cell transplantation (allo-HCT) is based on an active donor immune system that eliminates host-derived tumour cells. We hypothesized that in addition to the alloantigen-driven anti-tumour response, disruption of the immunological microenvironment within the tumour is responsible for its elimination after allo-HCT. We observed that induction of graft-versus-host disease (GvHD) significantly reduced the abundance of luc(+)  FoxP3(+) regulatory T (Treg) cells in the tumour tissue, which is indicative of impaired or over-ridden tumour recruitment signals towards Treg cells. Analysis of the intestines and liver revealed chemokines and purine nucleotides as candidates for attracting Treg to these sites of inflammation. Despite its expression on tissue-residing Treg cells, the chemokine receptor CCR3 was not critical for Treg-cell function following allo-HCT. Extracellular ATP can attract immune cells via P2Y2. P2Y2 was found to be expressed on Treg cells, and we found a partial reduction of GvHD prevention when P2Y2(-/-) rather than P2Y2(+/+) Treg cells were given. Exogenous local inflammation reduced Treg-cell accumulation in the tumour, suggesting a potential clinical approach to prevent Treg-cell-mediated tumour escape. In conclusion, we demonstrate that GvHD-related inflammation reduced Treg-cell numbers at the tumour sites, which may in turn help to explain the observation that patients with GvHD have a lower risk of tumour relapse.

Establishment of monoclonal antibodies against a novel eosinophil-specific cell surface molecule, major facilitator super family domain containing 10

Eosinophilic inflammation is the prominent feature of bronchial asthma, though the importance of eosinophils in the pathogenesis of this disease is controversial. We here established monoclonal antibodies against a newly identified cell surface molecule specifically expressed on mouse eosinophils. Eosinophils were highly purified from small intestine lamina propria and thymus as CD11c(+)Gr1(low)F4/80(+)B220(-) cells. Upon comparative microarray analysis for mRNA expressed in eosinophils and other leukocytes, major facilitator super family domain containing 10 (Mfsd10) was identified as a novel eosinophil-specific cell surface molecule. Hybridomas were established from spleen cells of rats immunized with Mfsd10-introduced Ba/F3 cells. One of three monoclonal antibodies against Mfsd10 displayed selective binding activity against eosinophils recovered in bronchoalveolar lavage fluid of ovalbumin-immunized and -challenged mice. Administration of this antibody in vivo induced a significant reduction of eosinophils recruited in the allergic lungs. Anti-Mfsd10 antibody is useful for investigating the pathophysiological roles of eosinophils with its selective binding and neutralizing activity for mouse eosinophils.

Inhibitory effect of CCR3 signal on alkali-induced corneal neovascularization

AIM

To investigate the effect of CC chemokine receptor 3 (CCR3) signal on corneal neovascularization (CRNV) induced by alkali burn and to explore its mechanism.

METHODS

Specific pathogen-free male BALB/C mice (aged 6-8 weeks) were randomly divided into CCR3-antagonist treated group (experimental group) and control group. CRNV was induced by alkali burn in mice. The time kinetic CCR3 expression in injured corneas was examined by reverse transcription polymerase chain reaction (RT-PCR). CCR3-antagonist (SB-328437 at different concentration of 125µg/mL, 250µg/mL, and 500µg/mL) was locally administrated after alkali injury. The formation of CRNV was assessed by CD31 corneal whole mount staining at two weeks after injury. Monocyte chemotactic protein 1 (MCP-1), monocyte chemotactic protein 3 (MCP-3) expressions in the early phase after injury were quantified and compared by RT-PCR. Macrophage intracorneal accumulation in the early phase after injury was evaluated and compared by immunohistochemistry.

RESULTS

Alkali injury induced the time kinetic intracorneal CCR3 expression. 500µg/mL of CCR3-antagonist treatment in the early phase but not the late phase resulted in significant impaired CRNV as compared to control group (P<0.05). CCR3-antagonist treatment in the early phase significantly reduced the intracorneal MCP-1 and MCP-3 enhancement compare to control group at day 2 and day 4 (P<0.05). Moreover, the number of intracorneal macrophage infiltration in the experimental group was reduced than those in control group at day 4 (P<0.05).

CONCLUSION

CCR3 signal is involved in alkali-induced CRNV. CCR3-antagonist can inhibit alkali-induced CRNV by reducing the intracorneal MCP-1 and MCP-3 mRNA expression and the intracorneal macrophage infiltration.

CD44 is critical for airway accumulation of antigen-specific Th2, but not Th1, cells induced by antigen challenge in mice

CD44 is a cell adhesion molecule involved in lymphocyte infiltration of inflamed tissues. We previously demonstrated that CD44 plays an important role in the development of airway inflammation in a murine model of allergic asthma. In this study, we investigated the role of CD44 expressed on CD4(+) T cells in the accumulation of T-helper type 2 (Th2) cells in the airway using CD44-deficient mice and anti-CD44 monoclonal antibodies. Antigen-induced Th2-mediated airway inflammation and airway hyperresponsiveness (AHR) in sensitized mice were reduced by CD44-deficiency. These asthmatic responses induced by the transfer of antigen-sensitized splenic CD4(+) T cells from CD44-deficient mice were weaker than those from WT mice. Lack of CD44 failed to induce AHR by antigen challenge. Expression level and hyaluronic acid receptor activity of CD44, as well as Neu1 sialidase expression on antigen-specific Th2 cells, were higher than those on antigen-specific Th1 cells. Anti-CD44 antibody preferentially suppressed the accumulation of those Th2 cells in the airway induced by antigen challenge. Our findings indicate that CD44 expressed on CD4(+) T cells plays a critical role in the accumulation of antigen-specific Th2 cells, but not Th1 cells, in the airway and in the development of AHR induced by antigen challenge.

Selective down-regulation of Th2 cell-mediated airway inflammation in mice by pharmacological intervention of CCR4

BACKGROUND

The chemokine receptor CCR4 has been implicated in Th2 cell-mediated immune responses. However, other T cell subsets are also known to participate in allergic inflammation.

OBJECTIVE

The role of CCR4 in Th1, Th2, and Th17 cell-mediated allergic airway inflammation was investigated.

METHOD

We generated an allergic airway inflammation model by adoptive transfer of in vitro-polarized ovalbumin (OVA)-specific Th1, Th2, and Th17 cells. The effect of a low-molecular weight CCR4 antagonist, Compound 22, on this model was examined.

RESULTS

Upon in vitro polarization of DO11.10 naïve T cells, Th1- and Th2-polarized cells dominantly expressed CXCR3 and CCR4, respectively, while Th17-polarized cells expressed CCR6 and CCR4. Intranasal OVA-challenge of mice transferred with each T cell subset induced accumulation of T cells in the lungs. Eosinophils were also massively accumulated in Th2-transferred mice, whereas neutrophils were preferentially recruited in Th1- and Th17-transferred mice. Compound 22, as well as anti-CCL17 or anti-CCL22 antibody selectively suppressed accumulation of Th2 cells and eosinophils in the lungs of Th2-transferred and OVA-challenged mice. Compound 22 also inhibited bronchial hyperresponsiveness but had little effect on goblet cell hyperplasia in Th2-transferred and OVA-challenged mice.

CONCLUSIONS AND CLINICAL RELEVANCE

There were notable differences in allergic lung inflammation mediated by different T cell subsets. CCR4 blockage was selectively effective for suppression of Th2-mediated allergic inflammation by blocking infiltration of Th2 cells.

Treatment of allergic asthma: modulation of Th2 cells and their responses

Atopic asthma is a chronic inflammatory pulmonary disease characterised by recurrent episodes of wheezy, laboured breathing with an underlying Th2 cell-mediated inflammatory response in the airways. It is currently treated and, more or less, controlled depending on severity, with bronchodilators e.g. long-acting beta agonists and long-acting muscarinic antagonists or anti-inflammatory drugs such as corticosteroids (inhaled or oral), leukotriene modifiers, theophyline and anti-IgE therapy. Unfortunately, none of these treatments are curative and some asthmatic patients do not respond to intense anti-inflammatory therapies. Additionally, the use of long-term oral steroids has many undesired side effects. For this reason, novel and more effective drugs are needed. In this review, we focus on the CD4+ Th2 cells and their products as targets for the development of new drugs to add to the current armamentarium as adjuncts or as potential stand-alone treatments for allergic asthma. We argue that in early disease, the reduction or elimination of allergen-specific Th2 cells will reduce the consequences of repeated allergic inflammatory responses such as lung remodelling without causing generalised immunosuppression.

Understanding the genetic regulation of IgE production

Immunoglobulin E (IgE) is a key mediator of anti-parasitic and anti-tumour immunity. However it is also a critical component of atopic and autoimmune diseases, and elevated serum IgE levels are a common indicator of immune dysregulation. In this review we survey the literature on genetic associations of elevated IgE in humans and mice. We find that defects in a limited number of pathways explain the majority of gene associations with IgE. Commonly, elevated IgE is associated with defects in Th bias and B cell class switching, severe T cell tolerance defects and defects in immunity at the host-environment interface. These genetic data demonstrate the mechanisms of control over IgE production and the manner in which they can be circumvented.

Exacerbation of facial motoneuron loss after facial nerve axotomy in CCR3-deficient mice

We have previously demonstrated a neuroprotective mechanism of FMN (facial motoneuron) survival after facial nerve axotomy that is dependent on CD4⁺ Th2 cell interaction with peripheral antigen-presenting cells, as well as CNS (central nervous system)-resident microglia. PACAP (pituitary adenylate cyclase-activating polypeptide) is expressed by injured FMN and increases Th2-associated chemokine expression in cultured murine microglia. Collectively, these results suggest a model involving CD4⁺ Th2 cell migration to the facial motor nucleus after injury via microglial expression of Th2-associated chemokines. However, to respond to Th2-associated chemokines, Th2 cells must express the appropriate Th2-associated chemokine receptors. In the present study, we tested the hypothesis that Th2-associated chemokine receptors increase in the facial motor nucleus after facial nerve axotomy at timepoints consistent with significant T-cell infiltration. Microarray analysis of Th2-associated chemokine receptors was followed up with real-time PCR for CCR3, which indicated that facial nerve injury increases CCR3 mRNA levels in mouse facial motor nucleus. Unexpectedly, quantitative- and co-immunofluorescence revealed increased CCR3 expression localizing to FMN in the facial motor nucleus after facial nerve axotomy. Compared with WT (wild-type), a significant decrease in FMN survival 4 weeks after axotomy was observed in CCR3^−/− mice. Additionally, compared with WT, a significant decrease in FMN survival 4 weeks after axotomy was observed in Rag2^−/− (recombination activating gene-2-deficient) mice adoptively transferred CD4⁺ T-cells isolated from CCR3^−/− mice, but not in CCR3^−/− mice adoptively transferred CD4⁺ T-cells derived from WT mice. These results provide a basis for further investigation into the co-operation between CD4⁺ T-cell- and CCR3-mediated neuroprotection after FMN injury.

Effects of facial nerve axotomy on Th2- and Th1-associated chemokine expression in the facial motor nucleus of wild-type and presymptomatic mSOD1 mice

We have previously demonstrated a neuroprotective mechanism of facial motoneuron (FMN) survival after facial nerve axotomy that is dependent on CD4(+) Th2 cell interaction with peripheral antigen-presenting cells, as well as CNS resident microglia. To investigate this mechanism, we chose to study the Th2-associated chemokine, CCL11, and Th1-associated chemokine, CXCL11, in wild-type and presymptomatic mSOD1 mice after facial nerve axotomy. In this report, the results indicate that CCL11 is constitutively expressed in the uninjured facial motor nucleus, but CXCL11 is not expressed at all. Facial nerve axotomy induced a shift in CCL11 expression from FMN to astrocytes, whereas CXCL11 was induced in FMN. Differences in the number of CCL11- and CXCL11-expressing cells were observed between WT and mSOD1 mice after facial nerve axotomy.

A severe deficiency of coagulation factor VIIa results in attenuation of the asthmatic response in mice

Eosinophil counts in the bronchoalveolar lavage fluid of wild-type (WT) mice increased after ovalbumin (OVA) challenge, a response that was diminished in comparably challenged low-expressing coagulation factor VII (FVII(tTA/tTA)) mice. Levels of T helper type 2 (Th2) cytokines, IL-4, IL-5, and IL-13, and eosinophil-attracting chemokines, eotaxin and RANTES, were also lower in the OVA-challenged FVII(tTA/tTA) mice. Eosinophils purified from low-FVII mice underwent apoptosis at a faster rate compared with WT eosinophils, and eosinophil migration in response to eotaxin was reduced in eosinophils obtained from FVII(tTA/tTA) mice. Airway hyperresponsiveness and mucous layer thickness were reduced in OVA-treated FVII(tTA/tTA) mice, and addition of exogenous coagulation factor X (FX) enhanced mucin production in human epithelial NCI-H292 cells. Correspondingly, incubation of FX with NCI-H292 cells resulted in activated (a) FX production, suggesting that the components required for FX activation were present on NCI-H292 cells. These results demonstrate that FVIIa functions in the asthmatic response to an allergen by stimulating lung eosinophilia, airway hyperresponsiveness, and mucin production, this latter effect through its ability to activate FX in conjunction with tissue factor.

Post-transcriptional silencing of CCR3 downregulates IL-4 stimulated release of eotaxin-3 (CCL26) and other CCR3 ligands in alveolar type II cells

Trafficking and inflammation in airway diseases are, in part, modulated by members of the CC chemokine family, eotaxin-1 (CCL11), eotaxin-2 (CCL24), and eotaxin-3 (CCL26), which transduce signals through their CCR3 receptor. In this context, we hypothesized that transfecting alveolar type II epithelial cells with CCR3-targeted siRNA or antisense (AS-ODN) sequences will downregulate cellular synthesis and release of the primary CCR3 ligands CCL26 and CCL24 and will modulate other CCR3 ligands. The human A549 alveolar type II epithelium-like cell culture model was used for transfection and subsequent effects on CCR3 agonists. siRNAs were particularly effective. PCR showed a 60-80% decrease in mRNA and immunoblots showed up to 75-84% reduction of CCR3 in siRNA treated cells. CCR3-siRNA treatments reduced IL-4 stimulated CCL26 release and constitutive CCL24 release by 65% and 80%, respectively. Release of four additional CCR3 agonists RANTES, MCP-2, MCP-3 and MCP-4 was also significantly reduced by CCR3-siRNA treatments of the alveolar type II cells. Activation of eosinophils, assessed as superoxide anion generation, was reduced when eosinophils were treated with supernatants of A549 cells pretreated with CCR3-targeted siRNAs or AS-ODNs. Collectively, the data suggest that post-transcriptional regulation of CCR3 receptors may be a potential therapeutic approach for interrupting proinflammatory signaling.