Expression of the C-C chemokine receptor CCR3 in human airway epithelial 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.

Epitope Mapping of Anti-Mouse CCR3 Monoclonal Antibodies Using Flow Cytometry

The CC chemokine receptor 3 (CCR3) is a receptor for CC chemokines, including CCL5/RANTES, CCL7/MCP-3, and CCL11/eotaxin. CCR3 is expressed on the surface of eosinophils, basophils, a subset of Th2 lymphocytes, mast cells, and airway epithelial cells. CCR3 and its ligands are involved in airway hyperresponsiveness in allergic asthma, ocular allergies, and cancers. Therefore, CCR3 is an attractive target for those therapies. Previously, anti-mouse CCR3 (mCCR3) monoclonal antibodies (mAbs), C₃Mab-3 (rat IgG_2a, kappa), and C₃Mab-4 (rat IgG_2a, kappa) were developed using the Cell-Based Immunization and Screening (CBIS) method. In this study, the binding epitope of these mAbs was investigated using flow cytometry. A CCR3 extracellular domain-substituted mutant analysis showed that C₃Mab-3, C₃Mab-4, and a commercially available mAb (J073E5) recognized the N-terminal region (amino acids 1-38) of mCCR3. Next, alanine scanning was conducted in the N-terminal region. The results revealed that the Ala2, Phe3, Asn4, and Thr5 of mCCR3 are involved in C₃Mab-3 binding, whereas Ala2, Phe3, and Thr5 are essential to C₃Mab-4 binding, and Ala2 and Phe3 are crucial to J073E5 binding. These results reveal the involvement of the N-terminus of mCCR3 in the recognition of C₃Mab-3, C₃Mab-4, and J073E5.

Establishment of Novel Anti-Mouse CCR3 Monoclonal Antibodies (C3Mab-6 and C3Mab-7) by N-terminal Peptide Immunization

The CC chemokine receptor 3 (CCR3) is a member of the G protein-coupled receptor family that is highly expressed in eosinophils and basophils. CCR3 has been proposed as a therapeutic target for human immunodeficiency virus and allergy diagnosis. Therefore, in this study, we developed specific and sensitive monoclonal antibodies (mAbs) for mouse CCR3 (mCCR3), which are useful for flow cytometry by peptide immunization. The established anti-mCCR3 mAbs, C₃Mab-6 (rat IgG₁, kappa) and C₃Mab-7 (rat IgG₁, kappa), reacted with mCCR3-overexpressed Chinese hamster ovary-K1 (CHO/mCCR3), in addition to mCCR3-endogenously expressed cell lines, such as P388 (mouse lymphoid neoplasma) and J774-1 (mouse macrophage-like) through flow cytometry. Kinetic analyses using flow cytometry indicated that the dissociation constants (K_Ds) of C₃Mab-6 for CHO/mCCR3, P388, and J774-1 cells were 8.7 × 10^-9 M, 1.4 × 10^-7 M, and 1.7 × 10^-7 M, respectively, whereas the K_Ds of C₃Mab-7 for these cell lines were 3.7 × 10^-9 M, 5.1 × 10^-7 M, and 3.1 × 10^-7 M, respectively. Results also indicated that C₃Mab-6 and C₃Mab-7 are useful for detecting cells expressing CCR3 through flow cytometry, thereby making them potentially beneficial for treating CCR3-expressing cells.

C3Mab-3: A Monoclonal Antibody for Mouse CC Chemokine Receptor 3 for Flow Cytometry

CC chemokine receptor 3 (CCR3) belongs to the G protein-coupled receptor family and is highly expressed in eosinophils and basophils. CCR3 is essential for recruiting eosinophils into the lung. Moreover, CCR3 was found in the serum of colorectal cancer patients higher than in the control group. Therefore, CCR3 will be a useful target for asthma and colorectal cancer diagnosis. This study developed a specific and sensitive monoclonal antibody (mAb) for mouse CCR3 (mCCR3), which is useful for flow cytometry using the Cell-Based Immunization and Screening method. The established anti-mCCR3 mAb, C₃Mab-3 (rat IgG_2a, kappa), reacted with mCCR3-overexpressed Chinese hamster ovary-K1 (CHO/mCCR3) cells through flow cytometry. C₃Mab-3 also reacted with P388 (mouse lymphoid neoplasma) and J774-1 (mouse macrophage-like) cells, which express mCCR3 endogenously. Kinetic analyses using flow cytometry indicated that K_Ds of C₃Mab-3 for CHO/mCCR3, P388, and J774-1 cells were 4.3 × 10^-8 M, 2.6 × 10^-7 M, and 2.4 × 10^-7 M, respectively. C₃Mab-3 could be a valuable tool for elucidating mCCR3-related biological response using flow cytometry.

Role of CCR3 in respiratory syncytial virus infection of airway epithelial cells

Respiratory syncytial virus (RSV) infection is the principal cause of severe lower respiratory tract disease and accounts for a significant risk for developing asthma later in life. Clinical studies have shown an increase in airway responsiveness and a concomitant Th₂ response in the lungs of RSV-infected patients. These indications suggest that RSV may modulate aspects of the immune response to promote virus replication. Here, we show that CCR3 facilitates RSV infection of airway epithelial cells, an effect that was inhibited by eotaxin-1/CCL11 or upon CCR3 gene silencing. Mechanistically, cellular entry of RSV is mediated by binding of the viral G protein to CCR3 and selective chemotaxis of Th₂ cells and eosinophils. In vivo, mice lacking CCR3 display a significant reduction in RSV infection, airway inflammation, and mucus production. Overall, RSV G protein-CCR3 interaction may participate in pulmonary infection and inflammation by enhancing eosinophils' recruitment and less potent antiviral Th₂ cells.

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CCR3 mediates RSV infection of human airway epithelial cells

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Eotaxin-1 blocks RSV-G binding to CCR3 and significantly decreases RSV infection

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RSV-G secreted protein (sG) attracts human eosinophils and Th₂ cells through CCR3

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RSV infection of mice lacking CCR3 exhibited reduced inflammation and mucus secretion

Development of Anti-Mouse CC Chemokine Receptor 3 Monoclonal Antibodies for Flow Cytometry

CC chemokine receptor 3 (CCR3), also known as CD193, belongs to class A of G protein-coupled receptors and is present in high levels in eosinophils, basophils, and airway epithelial cells. CCR3 is considered the therapeutic target for human immunodeficiency virus (HIV) infections and allergic diseases; therefore, the development of sensitive monoclonal antibodies (mAbs) for CCR3 has been desired. This study aimed to establish a specific and sensitive mAb against mouse CCR3 (mCCR3) useful for flow cytometry analysis by employing the Cell-Based Immunization and Screening (CBIS) method. The generated anti-mCCR3 mAb, C₃Mab-2 (rat IgG_2b, kappa), was found to react with mCCR3-overexpressed Chinese hamster ovary-K1 (CHO/mCCR3) cells, according to flow cytometric analysis. Also, it reacted with P388 (mouse lymphoid neoplasm) or J774-1 (mouse macrophage-like) cells, which express endogenous mCCR3. Taken together, C₃Mab-2, generated by the CBIS method, can be a valuable tool for detecting mCCR3 on the surface of mouse cells.

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.

1,3-Dibromo-1,1-difluoro-2-propanone as a Useful Synthon for a Chemoselective Preparation of 4-Bromodifluoromethyl Thiazoles

We report herein a synthetic protocol for the preparation of 1,3-dibromo-1,1-difluoro-2-propanone, a new synthon used for the first time in a reaction with aromatic amines and sodium thiocyanate, leading to thiazoles which are useful candidates in drug discovery programs. The new synthon allows to introduce a bromodifluoromethyl group at the C4 of the thiazole, and it is amenable of further transformation such as the Br/F exchange useful in radiopharmaceutics. Application of the strategy to the preparation of a precursor of the biologically relevant DF2755Y is also reported.

P2X4R promotes airway remodeling by acting on the phenotype switching of bronchial smooth muscle cells in rats

The P2X4 receptor (P2X4R) contributes to airway inflammation and airway remodeling in mice with allergic asthma. However, the molecular mechanism by which P2X4R affects the airway remodeling in allergic asthma remains largely unknown. We established an allergic asthma model by ovalbumin (OVA) inhalation in BALB/c mice. Compared with the mice in the control group, the expression of proliferating cell nuclear antigen (PCNA) increased and that of alpha-smooth muscle actin (α-SMA) decreased in the OVA-challenged mice. 5-BDBD, a P2X4R antagonist, alleviated the OVA-induced changes. To clarify the role of P2X4R in the phenotype switching of the bronchial smooth muscle, bronchial smooth muscle contractility and p38MAPK expression were investigated. Platelet-derived growth factor-BB (PDGF-BB) was used to activate the proliferation of primary-cultured rat bronchial smooth muscle cells (BSMCs). P2X4R, p38MAPK, and phenotype markers were evaluated using Western blotting or immunofluorescence. PDGF-BB administration increased the P2X4R and phospho-p38MAPK expression in BSMCs, and the increased phospho-p38MAPK expression was downregulated by silencing of the P2X4R mRNA. PDGF-BB stimulated the proliferation and synthetic phenotype of BSMCs, which was aggravated by a P2X4R agonist and alleviated by a P2X4R antagonist or silencing the P2X4R mRNA. The decreased contractile phenotype induced by PDGF-BB was alleviated by a P2X4R antagonist or by silencing the P2X4R mRNA. SB203580, p38MAPK inhibitor, inhibited the PDGF-BB-induced increasing of synthetic phenotype and the proliferation of BSMCs. These findings indicate that P2X4R acts directly on the phenotype switching of BSMCs. Inhibiting P2X4R can promote the contractile differentiation of BSMCs via p38MAPK signaling. Thus, the effect of P2X4R on airway remodeling indicates that this receptor could be a target for future drug candidates.

Enhanced expression of Organic Cation Transporters in bronchial epithelial cell layers following insults associated with asthma - Impact on salbutamol transport

Increasing evidence suggests Organic Cation Transporters (OCT) might facilitate the absorption of inhaled bronchodilators, including salbutamol, across the lung epithelium. This is essentially scarred and inflamed in asthma. Accordingly, the impact of epithelial insults relevant to asthma on OCT expression and salbutamol transport was evaluated in air-liquid interfaced layers of the human broncho-epithelial cell line Calu-3. These were physically injured and allowed to recover for 48h or exposed to the pro-inflammatory stimulant lipopolysaccharide (LPS) for 48h and the aeroallergen house dust mite (HDM) for 8h twice over 48h. Increases in transporter expression were measured following each treatment, with the protein levels of the OCTN2 subtype consistently raised by at least 50%. Interestingly, OCT upregulation upon LPS and HDM challenges were dependent on an inflammatory event occurring in the cell layers. Salbutamol permeability was higher in LPS exposed layers than in their untreated counterparts and in both cases, was sensitive to the OCT inhibitor tetraethylammonium. This study is the first to show epithelial injury, inflammation and allergen abuse upregulate OCT in bronchial epithelial cells, which might have an impact on the absorption of their substrates in diseased lungs.

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).

Elements Involved In Promoting Eosinophilic Gastrointestinal Disorders

Eosinophilic gastrointestinal disorders (EGID) are food allergen-induced allergic gastrointestinal disorders, characterized by accumulation of highly induced eosinophils in different segments of gastrointestinal tract along with eosinophil microabssess and extracellular eosinophilic granules in the epithelial layer. EGID are both IgE- and cell-mediated group of diseases that include eosinophilic esophagitis (EoE), eosinophilic gastritis (EG), eosinophilic gastroenteritis (EGE) and eosinophilic colitis (EC). Despite the increased incidences and considerable progress made in understanding EGID pathogenesis. The mechanism is still not well understood. It has been shown that IL-4, IL-5, IL-13, IL-15, IL-18, eotaxin-1, eotaxin-2 and eotaxin-3 play a critical role in EGID pathogenesis. Currently, the only criterion for diagnosing EoE, EGE and EC are repetitive endoscopic and histopathological evaluation of biopsies along with other clinical characteristics/manifestations. Antigen elimination and corticosteroid therapies are the most effective therapies currently in practice for the treatment of EGID. The cytokines (anti-IL-5 and anti-IL-13) therapy trials were not very successful in case of EoE. Most recently, a clinical trial using anti-IL-13 reported only 60% reduced esophageal eosinophilia without achieving primary endpoint. This clinical finding is not surprising and is in accordance with our earlier report indicating that IL-13 is not critical in the initiation of EoE. Notably, EGID still has no reliable noninvasive diagnostic biomarkers. Hence, there is a great necessity to identify novel noninvasive diagnostic biomarkers that can easily diagnose EGID and provide an effective therapy. Now, the attention is required to target cell types like iNKT cells that produce eosinophil active cytokines and is found induced in the pathogenesis of both experimental and human EoE. iNKT cell neutralization is shown to protect allergen-induced EoE in experimental model. In this review, we have discussed the key elements that are critical in the disease initiation, progression, pathogenesis and important for future diagnostic and therapeutic interventions for EGID.

Chemokine receptors and their therapeutic opportunities in diseased lung: far beyond leukocyte trafficking

Chemokine receptors and their chemokine ligands, key mediators of inflammatory and immune cell trafficking, are involved in the regulation of both physiological and pathological processes in the lung. The discovery that chemokine receptors/chemokines, typically expressed by inflammatory and immune cells, are also expressed in structural lung tissue cells suggests their role in mediating the restoration of lung tissue structure and functions. Thus, chemokine receptors/chemokines contribute not only to inflammatory and immune responses in the lung but also play a critical role in the regulation of lung tissue repair, regeneration, and remodeling. This review aims to summarize current state-of-the-art on chemokine receptors and their ligands in lung diseases such as chronic obstructive pulmonary disease, asthma/allergy, pulmonary fibrosis, acute lung injury, and lung infection. Furthermore, the therapeutic opportunities of chemokine receptors in aforementioned lung diseases are discussed. The review also aims to delineate the potential contribution of chemokine receptors to the processes leading to repair/regeneration of the lung tissue.

Hematopoietic stem and progenitor cells in inflammation and allergy

Hematopoietic stem and progenitor cells contribute to allergic inflammation. Pro-inflammatory cytokines that are generated following allergen challenge can impact the differentiation of hematopoietic progenitor cells leading to increased production of effector cells such as eosinophils and basophils, which are key cells involved in the pathogenesis of allergic airway inflammation. Homing of stem cells to the lungs is associated with inflammatory and remodeling changes in asthmatics. Factors that modulate the differentiation and increased migration of stem cells to the site of inflammation in asthma remain to be defined. Stem cells can mature at the site of inflammation in response to inflammatory mediators and other components in the milieu. While the available data suggest that hematopoietic cells traffic to target tissues, the molecular factors underlying in situ differentiation have yet to be specified. Here, we critically evaluate the potential role of hematopoietic progenitors in contributing to the increased immune cell infiltrate in allergic asthma and the factors that drive their differentiation.

Fumaric acid attenuates the eotaxin-1 expression in TNF-α-stimulated fibroblasts by suppressing p38 MAPK-dependent NF-κB signaling

Eotaxin-1 is a potent chemoattractant for eosinophils and a critical mediator during the development of eosinophilic inflammation. Fumaric acid is an intermediate product of the citric acid cycle, which is source of intracellular energy. Although fumaric acid ameliorates psoriasis and multiple sclerosis, its involvement in eotaxin-1-mediated effects has not been assessed. In this study, we investigated the effects of fumaric acid on eotaxin-1 expression in a mouse fibroblast cell line. We found that fumaric acid significantly inhibited tumor necrosis factor-α (TNF-α-induced eotaxin-1 expression. This fumaric acid effect was mediated through the inhibition of p38 mitogen-activated protein kinase (MAPK)-dependent nuclear factor (NF)-κB signaling. We also found that fumaric acid operates downstream of MEKK3 during TNF-α-induced NF-κB signaling, which upregulated eotaxin-1 expression. In addition, fumaric acid attenuated expression of CC-chemokine receptor 3 (CCR3), an eotaxin-1 receptor, and adhesion molecules that play important roles in eosinophil binding to induce allergic inflammation. Taken together, these findings indicate that inhibiting TNF-α-induced eotaxin-1 expression by fumaric acid occurs primarily through suppression of NF-κB signaling, which is mediated by inhibiting p38 MAPK and suggest that fumaric acid may be used as a complementary treatment option for eotaxin-1-mediated diseases.

Different GATA factors dictate CCR3 transcription in allergic inflammatory cells in a cell type-specific manner

The chemokine receptor CCR3 is expressed in prominent allergic inflammatory cells, including eosinophils, mast cells, and Th2 cells. We previously identified a functional GATA element within exon 1 of the CCR3 gene that is responsible for GATA-1-mediated CCR3 transcription. Because allergic inflammatory cells exhibit distinct expression patterns of different GATA factors, we investigated whether different GATA factors dictate CCR3 transcription in a cell type-specific manner. GATA-2 was expressed in EoL-1 eosinophilic cells, GATA-1 and GATA-2 were expressed in HMC-1 mast cells, and GATA-3 was preferentially expressed in Jurkat cells. Unlike a wild-type CCR3 reporter, reporters lacking the functional GATA element were not active in any of the three cell types, implying the involvement of different GATA factors in CCR3 transcription. RNA interference assays showed that small interfering RNAs specific for different GATA factors reduced CCR3 reporter activity in a cell type-specific fashion. Consistent with these findings, chromatin immunoprecipitation and EMSA analyses demonstrated cell type-specific binding of GATA factors to the functional GATA site. More importantly, specific inhibition of the CCR3 reporter activity by different GATA small interfering RNAs was well preserved in respective cell types differentiated from cord blood; in particular, GATA-3 was entirely responsible for reporter activity in Th2 cells and replaced the role predominantly played by GATA-1 and GATA-2. These results highlight a mechanistic role of GATA factors in which cell type-specific expression is the primary determinant of transcription of the CCR3 gene in major allergic inflammatory cells.

CpG methylation at GATA elements in the regulatory region of CCR3 positively correlates with CCR3 transcription

DNA methylation may regulate gene expression by restricting the access of transcription factors. We have previously demonstrated that GATA-1 regulates the transcription of the CCR3 gene by dynamically interacting with both positively and negatively acting GATA elements of high affinity binding in the proximal promoter region including exon 1. Exon 1 has three CpG sites, two of which are positioned at the negatively acting GATA elements. We hypothesized that the methylation of these two CpGs sites might preclude GATA-1 binding to the negatively acting GATA elements and, as a result, increase the availability of GATA-1 to the positively acting GATA element, thereby contributing to an increase in GATA-1-mediated transcription of the gene. To this end, we determined the methylation of the three CpG sites by bisulfate pyrosequencing in peripheral blood eosinophils, cord blood (CB)-derived eosinophils, PBMCs, and cell lines that vary in CCR3 mRNA expression. Our results demonstrated that methylation of CpG sites at the negatively acting GATA elements severely reduced GATA-1 binding and augmented transcription activity in vitro. In agreement, methylation of these CpG sites positively correlated with CCR3 mRNA expression in the primary cells and cell lines examined. Interestingly, methylation patterns of these three CpG sites in CB-derived eosinophils mostly resembled those in peripheral blood eosinophils. These results suggest that methylation of CpG sites at the GATA elements in the regulatory regions fine-tunes CCR3 transcription.

Eosinophilic gastrointestinal diseases: review and update

Eosinophilic gastrointestinal disorders (EGIDs) are a progressively more frequent diverse group of intestinal diseases. The intention of this paper is to present the newest developments in the care of patients with EGIDs and to sum up a rising literature defining the clinical features and mechanistic elements of eosinophils and their intricate associations with the gastrointestinal tract. Clinicians ought to stay sensitive to EGIDs as a diagnostic likelihood for patients with general gastrointestinal symptoms. Further research is warranted to establish various methods leading to dysfunction coupled with eosinophilic gastrointestinal inflammation.

Chemical sensitization and allergotoxicology

Chemical sensitization remains an important environmental and occupational health issue. A wide range of substances have been shown to possess the ability to induce skin sensitization or respiratory sensitization. As a consequence, there is a need to have appropriate methods to identify sensitizing agents. Although a considerable investment has been made in exploring opportunities to develop methods for hazard identification and characterization, there are, as yet, no validated nonanimal methods available. A state of the art of the different in vitro approaches to identify contact and respiratory capacity of chemicals is covered in this chapter.

CCL26-targeted siRNA treatment of alveolar type II cells decreases expression of CCR3-binding chemokines and reduces eosinophil migration: implications in asthma therapy

The underlying inflammation present in chronic airway diseases is orchestrated by increased expression of CC chemokines that selectively recruit leukocyte populations into the pulmonary system. Human CCL26 signals through CC chemokine receptor 3 (CCR3), is dramatically upregulated in challenged asthmatics, and stimulates recruitment of eosinophils (EOSs) and other leukocytes. CCL26 participates in regulation of its receptor CCR3 and modulates expression of a variety of chemokines in alveolar type II cells. Utilizing the A549 alveolar type II epithelial cell culture model, we carried out studies to test the hypothesis that CCL26-siRNA treatment of these cells would ameliorate Th2-driven release of the eotaxins and other CCR3 ligands that would, in turn, decrease recruitment and activation of EOSs. Results demonstrate that CCL26-siRNA treatments decreased interleukin-4-induced CCL26 and CCL24 expression by >70%. CCL26-directed small-interfering RNA (siRNA) treatments significantly decreased release of CCL5 (RANTES), CCL15 (MIP-1δ), CCL8 (MCP-2), and CCL13 (MCP-4). In bioactivity assays it was shown that EOS migration and activation were reduced up to 80% and 90%, respectively, when exposed to supernatants of CCL26-siRNA-treated cells. These results provide evidence that CCL26 may be an appropriate target for development of new therapeutic agents designed to alleviate the underlying inflammation associated with chronic diseases of the airways.

Pulmonary epithelial CCR3 promotes LPS-induced lung inflammation by mediating release of IL-8

Interleukin (IL)-8 from pulmonary epithelial cells has been suggested to play an important role in the airway inflammation, although the mechanism remains unclear. We envisioned a possibility that pulmonary epithelial CCR3 could be involved in secretion and regulation of IL-8 and promote lipopolysaccharide (LPS)-induced lung inflammation. Human bronchial epithelial cell line NCI-H292 and alveolar type II epithelial cell line A549 were used to test role of CCR3 in production of IL-8 at cellular level. In vivo studies were performed on C57/BL6 mice instilled intratracheally with LPS in a model of acute lung injury (ALI). The activity of a CCR3-specific inhibitor (SB-328437) was measured in both in vitro and in vivo systems. We found that expression of CCR3 in NCI-H292 and A549 cells were increased by 23% and 16%, respectively, 24 h after the challenge with LPS. LPS increased the expression of CCR3 in NCI-H292 and A549 cells in a time-dependent manner, which was inhibited significantly by SB-328437. SB-328437 also diminished neutrophil recruitment in alveolar airspaces and improved LPS-induced ALI and production of IL-8 in bronchoalveolar lavage fluid. These results suggest that pulmonary epithelial CCR3 be involved in progression of LPS-induced lung inflammation by mediating release of IL-8. CCR3 in pulmonary epithelia may be an attractive target for development of therapies for ALI.

A novel CC-chemokine receptor 3 antagonist, Ki19003, inhibits airway eosinophilia and subepithelial/peribronchial fibrosis induced by repeated antigen challenge in mice

CC-chemokine receptor 3 (CCR3) is a chemokine receptor for which major ligands, CC-chemokine ligand (CCL) 11, CCL24, and CCL26, are known to be involved in chemotaxis for eosinophils. In the present study, we evaluated the effect of a low molecular weight CCR3-receptor antagonist, Ki19003 (4-[[5-(2,4-dichlorobenzylureido)pentyl][1-(4-chlorophenyl)ethyl]amino]butanoic acid), on airway remodeling in a mouse model of allergic asthma. BALB/c mice were sensitized twice by intraperitoneal injection of ovalbumin (OA) and exposed daily to 1% OA for 3 weeks. Twenty-four hours after the final antigen challenge, bronchoalveolar lavage and histological examinations were carried out. Ki19003 clearly inhibited antigen-induced increase in the number of eosinophils in bronchoalveolar lavage fluid (BALF), but did not affect the number of other cell types examined in this study. Ki19003 also inhibited the increased production of transforming growth factor-beta1 in BALF and the amount of hydroxyproline in the lungs in a dose-dependent manner. Furthermore, Ki19003 significantly attenuated allergen-induced subepithelial and peribronchial fibrosis. These findings indicate that CCR3 antagonism prevents not only the infiltration of eosinophils into the airways but also the development of allergen-induced subepithelial and peribronchial fibrosis. Therefore, a CCR3 antagonist may be useful in the treatment of airway remodeling, especially subepithelial and peribronchial fibrosis, in allergic asthma.

Association of the CCR3 gene polymorphism with aspirin exacerbated respiratory disease

INTRODUCTION

Aspirin hypersensitivity represents two distinct clinical syndromes, such as aspirin exacerbated respiratory disease (AERD) and aspirin-intolerant chronic urticaria/angioedema (AICU) which have different clinical phenotypes resulting from different genetic backgrounds in a Korean population. Persistent eosinophilic inflammation in airway is a characteristic feature of AERD and chemokine CC motif receptor 3 (CCR3) plays an important role in eosinophilic infiltration into the asthmatic airway.

OBJECTIVES

The main objective of this study is to investigate the association between CCR3 gene polymorphisms and aspirin hypersensitivity, including AERD and AICU.

METHODS

CCR3 mRNA expression was measured after an aspirin provocation test by real-time PCR. In total, 330 patients with aspirin hypersensitivity (191 AERD and 139 AICU) and 217 normal healthy controls (NC) were genotyped for two CCR3 promoter polymorphisms (-520T/G and -174C/T), and the functional effects of the polymorphisms were analyzed applying a luciferase reporter assay and an electrophoretic mobility shift assay.

RESULTS

CCR3 mRNA expression was significantly increased after aspirin provocation in AERD patients (P=0.002) but not in AICU patients. An in vitro functional study showed that the reporter construct having a -520G allele exhibited significantly higher promoter activity compared with the construct having a -520T allele in human myeloid (U937), lymphoid (Jurkat), and mast (HMC-1) cell lines (P<0.001). We found -520G and -174T specific bands on EMSA.

CONCLUSION

This result suggests that the CCR3 genetic polymorphisms may contribute to the development of the AERD phenotype and may be used as a genetic marker for differentiating between the two major aspirin hypersensitivity phenotypes.

Nuclear autoantigen CENP-B transactivation of the epidermal growth factor receptor via chemokine receptor 3 in vascular smooth muscle cells

OBJECTIVE

We have previously found that the CENP-B nuclear autoantigen, which is specifically targeted by autoantibodies in the limited cutaneous form of systemic sclerosis, behaved as a potent migratory factor for human pulmonary artery smooth muscle cells (PASMCs). Other recent studies have shown that several disease-associated autoantigens induced cell migration by interacting with various chemokine receptors. Prompted by this hypothesis, we undertook this study to determine whether CENP-B interacts with chemokine receptors on the surface of human PASMCs, to explore the relevant signaling pathways, and to characterize the effects of anti-CENP-B binding on SMC stimulation.

METHODS

To demonstrate the expression of specific chemokine receptors by human PASMCs at both the messenger RNA and protein levels, reverse transcription-polymerase chain reaction, immunoblotting, and flow cytometry analyses were performed. Desensitization studies and specific inhibitors were used to further identify the CENP-B target on the surface of human PASMCs.

RESULTS

Our data strongly suggested that CENP-B used chemokine receptor 3 (CCR3) to mediate human PASMCs signaling. Moreover, several lines of evidence indicated that CENP-B binding subsequently stimulated the cross-talk between CCR3 and epidermal growth factor receptor (EGFR) via a matrix metalloprotease-dependent mechanism that involved the processing of heparin-binding EGF-like growth factor. Transactivation of the EGFR through CCR3 was found to be a critical pathway that elicits MAP kinase activation and secretion of cytokines such as interleukin-8. Finally, anti-CENP-B autoantibodies were found to abolish this signaling pathway, thus preventing CENP-B from transactivating EGFR and exerting its cytokine-like activities toward vascular smooth muscle cells.

CONCLUSION

The identification of CENP-B as a CCR3 ligand opens up new perspectives for the study of the pathogenic role of anti-CENP-B autoantibodies.

Th2 cells as targets for therapeutic intervention in allergic bronchial asthma

Th2 cells play a central role in the pathogenesis of allergic bronchial asthma, since each of their characteristic cytokines such as IL-4, IL-5, IL-9 and IL-13 contributes to hallmarks of this disease, including airway eosinophilia, increased mucus production, production of allergen-specific IgE and development of airway hyper-responsiveness. Therefore, these cells are predisposed as target cells for therapeutic intervention. Experimental approaches targeted Th2-type effector cytokines, Th2-cell recruitment and Th2-cell development. Another strategy uses the immunomodulatory potential of tolerance-inducing cytokines such as IL-10 or of cytokines such as IL-12, IL-18 and IFN-gamma that are able to induce a counterbalancing Th1 immune response.

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.

The airway smooth muscle CCR3/CCL11 axis is inhibited by mast cells

BACKGROUND

Airway smooth muscle hyperplasia is a feature of asthma, and increases with disease severity. CCR3-mediated recruitment of airway smooth muscle progenitors towards the airway smooth muscle bundle has been proposed as one possible mechanism involved in airway smooth muscle hyperplasia. Mast cells are microlocalized to the airway smooth muscle bundle and whether mast cells influence CCR3-mediated migration is uncertain.

METHODS

We examined the expression of CCR3 by primary cultures of airway smooth muscle cells from asthmatics and nonasthmatics. CCR3 function was examined using intracellular calcium measurements, chemotaxis, wound healing, cell proliferation and survival assays. We investigated the recovery and function of both recombinant and airway smooth muscle-derived CCL11 (eotaxin) after co-culture with beta-tryptase and human lung mast cells.

RESULTS

Airway smooth muscle expressed CCR3. Airway smooth muscle CCR3 activation by CCL11 mediated intracellular calcium elevation, concentration-dependent migration and wound healing, but had no effect on proliferation or survival. Co-culture with beta-tryptase or mast cells degraded recombinant and airway smooth muscle-derived CCL11, and beta-tryptase inhibited CCL11-mediated airway smooth muscle migration.

CONCLUSIONS

CCL11 mediates airway smooth muscle migration. However co-culture with beta-tryptase or mast cells degraded recombinant and airway smooth muscle-derived CCL11 and inhibited CCL11-mediated airway smooth muscle migration. Therefore these findings cast doubt on the importance of the CCL11/CCR3 axis in the development of airway smooth muscle hyperplasia in asthma.

Cell types involved in allergic asthma and their use in in vitro models to assess respiratory sensitization

This review first describes the mechanism and cell types involved in allergic asthma, which is a complex clinical disease characterized by airway obstruction, airway inflammation and airway hyperresponsiveness to a variety of stimuli. The development of allergic asthma exists of three phases, namely the induction phase, the early-phase asthmatic reaction (EAR) and the late-phase asthmatic reaction (LAR). In the induction phase, antigen-presenting cells play a major role. Most important cells in the EAR are mast cells, and during the LAR, various cell types, such as eosinophils, neutrophils, T cells, macrophages, dendritic cells (DCs), and cells that endow structure are involved. In occupational asthma, this immunological mechanism is involved in 90% of the cases. The second part of this review gives an overview of in vitro models to assess the hazardous potential of high- and low-molecular weight chemicals on the respiratory system. In order to develop a good in vitro model for respiratory allergy, the choice of appropriate cell types is important. Epithelial cells, macrophages and DCs are currently the most used models in this field of research.

Transcriptome of hypoxic immature dendritic cells: modulation of chemokine/receptor expression

Hypoxia is a condition of low oxygen tension occurring in inflammatory tissues. Dendritic cells (DC) are professional antigen-presenting cells whose differentiation, migration, and activities are intrinsically linked to the microenvironment. DCs will home and migrate through pathologic tissues before reaching their final destination in the lymph node. We studied the differentiation of human monocytes into immature DCs (iDCs) in a hypoxic microenvironment. We generated iDC in vitro under normoxic (iDCs) or hypoxic (Hi-DCs) conditions and examined the hypoxia-responsive element in the promoter, gene expression, and biochemical KEGG pathways. Hi-DCs had an interesting phenotype represented by up-regulation of genes associated with cell movement/migration. In addition, the Hi-DC cytokine/receptor pathway showed a dichotomy between down-regulated chemokines and up-regulated chemokine receptor mRNA expression. We showed that CCR3, CX3CR1, and CCR2 are hypoxia-inducible genes and that CCL18, CCL23, CCL26, CCL24, and CCL14 are inhibited by hypoxia. A strong chemotactic response to CCR2 and CXCR4 agonists distinguished Hi-DCs from iDCs at a functional level. The hypoxic microenvironment promotes the differentiation of Hi-DCs, which differs from iDCs for gene expression profile and function. The most prominent characteristic of Hi-DCs is the expression of a mobility/migratory rather than inflammatory phenotype. We speculate that Hi-DCs have the tendency to leave the hypoxic tissue and follow the chemokine gradient toward normoxic areas where they can mature and contribute to the inflammatory process.

Expression and regulation of CCR1 by airway smooth muscle cells in asthma

C-C chemokines such as CCL11, CCL5, and CCL3 are central mediators in the pathogenesis of asthma. They are mainly associated with the recruitment and the activation of specific inflammatory cells, such as eosinophils, lymphocytes, and neutrophils. It has recently been shown that they can also activate structural cells, such as airway smooth muscle and epithelial cells. The aims of this study were to examine the expression of the CCL3 receptor, CCR1, on human airway smooth muscle cells (ASMC) and to document the regulation of this receptor by cytokines involved in asthma pathogenesis. We first demonstrated that CCR1 mRNA is increased in the airways of asthmatic vs control subjects and showed for the first time that ASMC express CCR1 mRNA and protein, both in vitro and in vivo. Calcium mobilization by CCR1 ligands confirmed its functionality on ASMC. Stimulation of ASMC with TNF-alpha and, to a lesser extent, IFN-gamma resulted in an up-regulation of CCR1 expression, which was totally suppressed by both dexamethasone or mithramycin. Taken together, our data suggest that CCR1 might be involved in the pathogenesis of asthma, through the activation of ASMC by its ligands.

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

The effects of selective CC chemokine receptor (CCR)-3 antagonists on antigen-induced leukocyte accumulation in the lungs of mice adoptively transferred with in vitro-differentiated T(h)1 and T(h)2 were investigated. Inhalation of antigen by mice injected with T(h)1 and T(h)2 initiated the migration of T cells themselves into the lungs. Subsequently, neutrophils massively accumulated in T(h)1-transferred mice, whereas eosinophil infiltration was specifically induced by T(h)2. CCR3 antagonists, SB-297006 and/or SB-328437, suppressed antigen-induced accumulation of T(h)2 as well as eosinophils in the lungs, whereas they failed to affect T(h)1-mediated airway inflammation. Not only T(h)2 and eosinophil infiltration but also cellular mobilization in T(h)1-transferred mice was attenuated by an anti-CC chemokine ligand-11 antibody. CCR3 antagonists reduced chemokine production in the lungs of mice transferred with T(h)2 but not T(h)1, suggesting that down-regulation of chemokine synthesis is involved in the selective inhibition of T(h)2-mediated eosinophil infiltration by CCR3 antagonists.

Effects of allergenic extracts on airway epithelium

When allergen is inhaled it comes into contact with the epithelium of the respiratory tract. This contact triggers multiple events that can ultimately stimulate development of allergic asthma. Some allergens, like house dust mite, contain active proteolytic enzymes that break down tight epithelial cell junctions. Others act to enhance inflammation by stimulating epithelial cells to make proinflammatory cytokines and chemokines. Alterations in airways include mucous cell metaplasia and eosinophil recruitment. In this review, cell culture experiments as well as several animal models and human patient data are utilized to examine the mechanisms by which allergens alter the normal epithelial homeostasis. Environmental pollutants, such as ozone and environmental tobacco smoke, enhance allergen-mediated effects on epithelium.

The polymorphisms of Eotaxin 1 and CCR3 genes influence on serum IgE, Eotaxin levels and mild asthmatic children in Taiwan

BACKGROUND

Asthma is a complex disorder, which is known to be affected by interactions between genetic and environmental factors. The human Eotaxin 1 and CCR3 attract eosinophils and Th2-lymphocytes to migrate to the inflammatory foci that could represent a key mechanism in allergy and asthma.

OBJECTIVE

We hypothesized that Eotaxin1 gene Ala23Thr and A-384 G, and CCR3 gene T51C polymorphisms are associated with plasma Eotaxin levels and predispose individuals to asthma pathogenesis.

METHODS

One hundred seventy-eight hospital-based asthmatic children and 277 community-based controls aged from 5 to 12 years were recruited in southern Taiwan. Whole blood samples and questionnaires were collected. In this study, we addressed genetic effects of Eotaxin 1 and CCR3 genes on asthma, plasma IgE and Eotaxin 1 levels.

RESULTS

In comparison with subjects with Ala23Ala genotype, Ala23Thr polymorphism of the Eotaxin 1 gene showed a significant protective effect on asthma (AOR = 0.58, 95% CI = 0.37-0.92). We demonstrated that the mean Eotaxin 1 concentration was significantly higher in subjects with Ala23Ala than in subjects with Thr23Thr (P = 0.005) or Ala23Thr (P = 0.07), which showed a gene-dose dependent relationship. But, we observed that the A-384G polymorphism of Eotaxin 1 gene and T51C polymorphism of CCR3 gene are not associated with asthma.

CONCLUSION

This study finding provide a strong evidence that Eotaxin 1 Thr23Thr homozygote has a protective effect on asthma and significantly decreases plasma Eotaxin 1 concentrations in asthmatics in Taiwan.

Design of Noncompetitive Interleukin-8 Inhibitors Acting on CXCR1 and CXCR2

Chemokines CXCL8 and CXCL1 play a key role in the recruitment of neutrophils at the site of inflammation. CXCL8 binds two membrane receptors, CXCR1 and CXCR2, whereas CXCL1 is a selective agonist for CXCR2. In the past decade, the physiopathological role of CXCL8 and CXCL1 has been investigated. A novel class of small molecular weight allosteric CXCR1 inhibitors was identified, and reparixin, the first drug candidate, is currently under clinical investigation in the prevention of ischemia/reperfusion injury in organ transplantation. Reparixin binding mode to CXCR1 has been studied and used for a computer-assisted design program of dual allosteric CXCR1 and CXCR2 inhibitors. In this paper, the results of modeling-driven SAR studies for the identification of potent dual inhibitors are discussed, and three new compounds (56, 67, and 79) sharing a common triflate moiety have been selected as potential leads with optimized pharmacokinetic characteristics.

Modulation of eotaxin-3 (CCL26) in alveolar type II epithelial cells

Airway epithelial inflammation associated with emphysema, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and asthma is regulated in part by alveolar type II cell chemokine signaling. Data suggest that resident lung cells use CCR3, CCR5 and CCR2 chemokine receptor/ligand systems to regulate the profile of leukocytes recruited in disease-associated inflammatory conditions. Thus studies were designed to test whether alveolar type II cells possess a Th1-activated CCR5-ligand system that modulates the Th2-activated CCR3/eotaxin-2 (CCL24), eotaxin-3 (CCL26) chemokine systems. The A549 alveolar type II epithelial-like cell culture model was used to demonstrate that alveolar type II cells constitutively express CCR5 which may be upregulated by MIP-1alpha (CCL3) whose expression was induced by the Th1 cytokines IL-1beta and IFN-gamma. Selective down-regulation of CCL26, but not CCL24, was observed in CCL3 and IL-4/CCL3 stimulated cells. Down-regulation was reversed by anti-CCR5 neutralizing antibody treatment. Thus, one mechanism through which Th1-activated CCCR5/ligand pathways modulate Th2-activated CCR3/ligand pathways is the differential down-regulation of CCL26 expression. Results suggest that the CCR3 and CCR5 receptor/ligand signaling pathways may be important targets for development of novel mechanism-based adjunctive therapies designed to abrogate the chronic inflammation associated with airway diseases.

A central regulatory role for eosinophils and the eotaxin/CCR3 axis in chronic experimental allergic airway inflammation

To clarify the role and regulation of eosinophils, we subjected several key eosinophil-related genetically engineered mice to a chronic model of allergic airway inflammation aiming to identify results that were independent of the genetic targeting strategy. In particular, mice with defects in eosinophil development (Deltadbl-GATA) and eosinophil recruitment [mice deficient in CCR3 (CCR3 knockout) and mice deficient in both eotaxin-1 and eotaxin-2 (eotaxin-1/2 double knockout)] were subjected to Aspergillus fumigatus-induced allergic airway inflammation. Allergen-induced eosinophil recruitment into the airway was abolished by 98%, 94%, and 99% in eotaxin-1/2 double knockout, CCR3 knockout, and Deltadbl-GATA mice, respectively. Importantly, allergen-induced type II T helper lymphocyte cytokine production was impaired in the lungs of eosinophil- and CCR3-deficient mice. The absence of eosinophils correlated with reduction in allergen-induced mucus production. Notably, by using global transcript expression profile analysis, a large subset (29%) of allergen-induced genes was eosinophil- and CCR3-dependent; pathways downstream from eosinophils were identified, including in situ activation of coagulation in the lung. In summary, we present multiple lines of independent evidence that eosinophils via CCR3 have a central role in chronic allergic airway disease.

Functional analysis of the chemokine receptor CCR3 on airway epithelial cells

The function of chemokine receptors on structural cells is only partially known. We previously reported the expression of a functional CCR3 receptor on airway epithelial cells (EC). We speculated that CCR3 might drive wound repair and expression of inflammatory genes in epithelium. The human airway EC lines BEAS-2B, 16-HBE, and primary bronchial EC were used to test the effect of in vitro challenge with the CCR3 ligands CCL11/eotaxin, CCL24/eotaxin-2, or CCL26/eotaxin-3 on 1) wound repair, using an established wound model; 2) cell proliferation and chemotaxis, using specific fluorometric assays; and 3) gene expression, using pathway-specific arrays for inflammatory and profibrotic cytokines, chemokines, and chemokine receptor genes. Agonist specificity was tested by cell pretreatment with an AstraZeneca CCR3 antagonist (10(-8) - 10(-6) M). CCL24 challenge significantly accelerated epithelial wound closure, with similar effects exerted by CCL11 and CCL26. This effect was time dependent, submaximal at 1 nM, and comparable in potency to epidermal growth factor. CCL24 induced a concentration-dependent increase in EC proliferation and chemotaxis, with significant effects observed at 10 nM. The AstraZeneca compound selectively inhibited these CCL24-mediated responses. CCL11 induced the up-regulation of several profibrogenic molecules such as fibroblast growth factor 1 and 5 and of several CC and CXC chemokines. Epithelial immunostaining for CCR3 was stronger in bronchial biopsies of asthmatics displaying marked inflammatory changes than in nondiseased samples. Epithelial CCR3 participates in key functions for wound repair, amplifies the expression of profibrogenic and chemokine transcripts, and appears up-regulated in inflamed asthmatic airways.

Membrane-bound eotaxin-3 mediates eosinophil transepithelial migration in IL-4-stimulated epithelial cells

Epithelial cells play an important role in orchestrating mucosal immune responses. In allergic-type inflammation, epithelial cells control the recruitment of eosinophils into the mucosa. Th2-type cytokine-driven release of eosinophil-active chemokines from epithelial cells directs eosinophil migration into the mucosal epithelium. CCR3, the main eosinophil chemokine receptor, regulates this process; however, the respective contribution of individual CCR3 ligands in eosinophil transepithelial migration is less well understood. Using an in vitro transepithelial chemotaxis system, we found that eotaxin-3 produced by IL-4-stimulated airway epithelial cells and CCR3 on eosinophils exclusively mediate eosinophil transepithelial migration. Eotaxin-3 protein levels were also increased in the nasal mucosal epithelium recovered from allergic patients as compared to non-allergic patients. Surprisingly, eotaxin-3 in IL-4-stimulated airway epithelial cells was predominantly cell surface bound, and the cell surface form was critical for eosinophil transepithelial migration. Eotaxin-3 cell surface association was partially glycosaminoglycan (GAG) dependent, but was completely protein dependent, suggesting that eotaxin-3 associates with both GAG and cell surface proteins. We thus provide evidence that cell surface-associated eotaxin-3 is the critical IL-4-dependent chemotactic signal mediating eosinophil transepithelial migration in the setting of allergic inflammation.

A closer look at chemokines and their role in asthmatic responses

Inflammatory cell recruitment is a hallmark phenomenon of all inflammatory diseases, including allergic asthma. In allergy and asthma, recruitment of inflammatory cells such as T cells, dendritic cells, mast cells, eosinophils and neutrophils, is mediated via a number of chemokines and their receptors. Not only are chemokines involved in recruitment of these cells, they also play a role in activation and differentiation of inflammatory cells, among others, by selectively activating Th1 or Th2 cells or by effects on epithelial or endothelial cells. Binding of chemokines with their receptors has been demonstrated to be highly promiscuous and the subsequent activation pattern on effector cells is very heterogeneous, which has lead to confusion and has complicated research in this field. Nonetheless, chemokines and their receptors are important potential therapeutical targets in allergy and asthma because of their central role in cell recruitment and activation during inflammation.

CCR3 expression and function in asthmatic airway smooth muscle cells

Asthma is characterized by an increase in airway smooth muscle mass and a decreased distance between the smooth muscle layer and the epithelium. Furthermore, there is evidence to indicate that airway smooth muscle cells (ASMC) express a wide variety of receptors involved in the immune response. The aims of this study were to examine the expression of CCR3 on ASMC, to compare this expression between asthmatic and nonasthmatic subjects, and to determine the implications of CCR3 expression in the migration of ASMC. We first demonstrated that ASMC constitutively express CCR3 at both mRNA and protein levels. Interestingly, TNF-alpha increases ASMC surface expression of CCR3 from 33 to 74%. Furthermore, using FACS analysis, we found that ASMC CCR3 is expressed to a greater degree in asthmatic vs control subjects (95 vs 75%). Functionality of the receptor was demonstrated by calcium assay; the addition of CCR3 ligand eotaxin to ASMC resulted in an increase in intracellular calcium production. Interestingly, ASMC was seen to demonstrate a positive chemotactic response to eotaxin. Indeed, ASMC significantly migrated toward 100 ng/ml eotaxin (2.2-fold increase, compared with control). In conclusion, the expression of CCR3 by ASMC is increased in asthmatics, and our data show that a CCR3 ligand such as eotaxin induces migration of ASMC in vitro. These results may suggest that eotaxin could be involved in the increased smooth muscle mass observed in asthmatics through the activation of CCR3.

Chemokines: key players in innate and adaptive immunity

Healthy individuals initiate an immediate immune response to microbes by using a set of germline-encoded receptors that recognize common molecular patterns found on the surface of pathogens that are distinct from self-antigens. This innate immune response is the first line of defense against microorganisms in vertebrates, and constitutes the only immune response in plants and invertebrates. The innate immune system includes cellular components, as well as a host of soluble products (antimicrobial peptides, complement fragments, cytokines, and chemokines). The adaptive immune response, which provides long-lasting protection, takes days to develop and requires somatic mutations leading to the development of antigen-specific T cell receptors (cell-mediated immunity) and immunoglobulins (humoral immunity). Members of the chemokine superfamily are crucially involved in both innate and adaptive responses. We review the biological actions of the chemokine superfamily, focusing on several functions that are relevant for both immune responses, such as cell recruitment, microbicidal activity, cell activation, polarization of CD4+ T cells, and effects on structural cells. In particular, we will illustrate the central role that chemokines play in host defense, best demonstrated by the tremendous number of chemokine and chemokine receptor homologs found in microbial genomes, which deflect the immune response of the host.

Inflammation of the respiratory tract is associated with CCL28 and CCR10 expression in a murine model of allergic asthma

Mouse models and in vitro cell culture were used to examine airway expression of the mucosal chemokine CCL28. Low levels of constitutively expressed mRNA were observed in transformed murine epithelial cells, but high levels could be induced by stimulation. Cytokines that signal through NF-kappaB, including IL-1beta and TNF-alpha or via JAK-STAT pathway including oncostatin M induced CCL28 in airway epithelial cells in vitro. Immunohistochemistry of murine airway tissue revealed that constitutive expression of CCL28 protein in vivo was low and not ubiquitous. However, abundant expression was detected in epithelia and lymphoid aggregates following allergic sensitization and challenge with ovalbumin. This was accompanied by increased detection of cells expressing CCR10 protein and mRNA in inflamed airways. Taken together, these data support a role for CCL28 in contributing to allergen driven airway pathologies, show that proinflammatory cytokines can induce this signal and suggest a role for CCR10 expressing cells in airway inflammation.

Elevated expression of TARC (CCL17) and MDC (CCL22) in models of cigarette smoke-induced pulmonary inflammation

TARC (CCL17) and MDC (CCL22) are well-known chemoattractants for Th2 cells. Here, we evaluated the role of both chemokines for cigarette smoke-induced airway inflammation. The expression profiles of MDC, TARC, and their receptor CCR4 were analyzed in models of acute and chronic cigarette smoke-induced airway inflammation that is characterized by a Th1 immune response. The results were compared to the expression of both chemokines in models of idiopathic pulmonary fibrosis and acute asthma, which are associated with a Th2 immune response. The expression of MDC and TARC was found to be elevated in all lung inflammation models. In contrast to the findings in the asthma and lung fibrosis models, the increased expression of MDC and TARC in the cigarette-smoke model was not associated with an increased infiltration of Th2 cells into smoke-treated lungs. Our data indicate that instead of Th2 cells, airway epithelial cells expressing CCR4 might be the principal targets for MDC and TARC released from alveolar macrophages during cigarette smoke-induced airway inflammation.

Drosophila melanogaster as a complementary system for studying HIV-1-related genes and proteins

Human immunodeficiency virus type 1 (HIV-1) persists as a pandemic even though new information about the virus is being discovered on a daily basis. If the brain becomes infected, HIV-1 encephalitis or HIV-1-associated dementia may develop. There is much to be learned about the modes of action and mechanisms of genes and proteins, and their interactions that underlie HIV-1 infection. Drosophila melanogaster has been used successfully to study genes and proteins related to HIV-1 infection, including but not limited to the disturbance of antimicrobial responses by viral protein U and the identification of D. melanogaster analogs to the serine palmitoyltransferase 5 and 6 proteins that play a role in activation of transcription by the HIV-1 Tat protein in human cells. We believe that utilizing D. melanogaster as a complementary system for the study of genes and proteins related to HIV-1 infection will provide useful information that will lead to new studies designed to enhance our understanding of the mechanistic roles of these molecules. In the present study, we focus on the utilization of D. melanogaster as a complementary system for studying HIV-1 related genes and proteins, why this research should be extended, and why this complementary system is an important method for enhancing our understanding of the genetics involved in HIV-1 infection.

Chemokines provide the sustained inflammatory bridge between innate and acquired immunity

In this review we focus on the role of chemokines in discreet areas of innate immunity and demonstrate that chemokines are key participants to not only the early inflammatory response to a foreign agent, but important to the sustained immune reaction. Our studies support the concept that a concerted and interactive innate and acquired immune reaction is key for an automatic, dynamic, sustained, and regulated response toward clearing foreign stimuli. It is imperative that the in vivo concept of innate and acquired immunity be considered a continuum of a global assault on a foreign agent and not as modes, which are independent of one another.

2-Arylpropionic CXC Chemokine Receptor 1 (CXCR1) Ligands as Novel Noncompetitive CXCL8 Inhibitors

The CXC chemokine CXCL8/IL-8 plays a major role in the activation and recruitment of polymorphonuclear (PMN) cells at inflammatory sites. CXCL8 activates PMNs by binding the seven-transmembrane (7-TM) G-protein-coupled receptors CXC chemokine receptor 1 (CXCR1) and CXC chemokine receptor 2 (CXCR2). (R)-Ketoprofen (1) was previously reported to be a potent and specific noncompetitive inhibitor of CXCL8-induced human PMNs chemotaxis. We report here molecular modeling studies showing a putative interaction site of 1 in the TM region of CXCR1. The binding model was confirmed by alanine scanning mutagenesis and photoaffinity labeling experiments. The molecular model driven medicinal chemistry optimization of 1 led to a new class of potent and specific inhibitors of CXCL8 biological activity. Among these, repertaxin (13) was selected as a clinical candidate drug for prevention of post-ischemia reperfusion injury.