Cloning of the human eosinophil chemoattractant, eotaxin. Expression, receptor binding, and functional properties suggest a mechanism for the selective recruitment of eosinophils

Moving targets: cell migration inhibitors as new anti-inflammatory therapies

The pharmaceutical industry has targeted various types of molecules to subdue inflammatory diseases. Drugs that disrupt cell migration appear particularly promising in clinical trials and in many animal models of inflammatory disease. Cell migration inhibitors not only interfere with migration of cells to a tissue, but also can affect other necessary processes such as mediator release and angiogenesis. However, the question is whether drugs that target adhesion molecules or chemoattractant receptors will prove superior to drugs that target other molecular types. This review proclaims the virtues of targeting cell migration-related molecules for development of new anti-inflammatory and anti-tumor based drugs. It is likely that cell migration inhibitors will transform the way in which many human inflammatory diseases and cancers are treated.

Using guinea pigs in studies relevant to asthma and COPD

The guinea pig has been the most commonly used small animal species in preclinical studies related to asthma and COPD. The primary advantages of the guinea pig are the similar potencies and efficacies of agonists and antagonists in human and guinea pig airways and the many similarities in physiological processes, especially airway autonomic control and the response to allergen. The primary disadvantages to using guinea pigs are the lack of transgenic methods, limited numbers of guinea pig strains for comparative studies and a prominent axon reflex that is unlikely to be present in human airways. These attributes and various models developed in guinea pigs are discussed.

Role of gastrointestinal eosinophils in inflammatory bowel disease and intestinal tumours

Eosinophils have been implicated in the pathogenesis of inflammatory bowel disease (IBD). Immunohistopathological studies have revealed accumulation and activation of eosinophils in actively inflamed intestinal mucosa of Crohn's disease and ulcerative colitis patients. Elevated levels of chemokines relevant for eosinophil chemotaxis and mediator release from eosinophils can be detected in serum and faeces of patients with active IBD. Animal studies have revealed that abrogation of chemokines (such as eotaxin) promoting eosinophil chemotaxis and circulation results in decreased severity of murine experimental colitis, suggesting a pro-inflammatory role for eosinophils in IBD. Furthermore, selective deletion of certain eosinophil-specific granule products results in attenuation of experimental intestinal inflammation. Shortly after their initial discovery by Ehrlich, eosinophils have been associated with intestinal tumours. However, as only very few studies have addressed the role of eosinophils in intestinal cancerogenesis, their impact on intestinal tumour development remains obscure; in particular, functional data are missing.

Granulocyte-macrophage colony-stimulating factor is required for bronchial eosinophilia in a murine model of allergic airway inflammation

GM-CSF plays an important role in inflammation by promoting the production, activation, and survival of granulocytes and macrophages. In this study, GM-CSF knockout (GM-CSF(-/-)) mice were used to investigate the role of GM-CSF in a model of allergic airway inflammation. In allergic GM-CSF(-/-) mice, eosinophil recruitment to the airways showed a striking pattern, with eosinophils present in perivascular areas, but almost completely absent in peribronchial areas, whereas in wild-type mice, eosinophil infiltration appeared in both areas. In the GM-CSF(-/-) mice, mucus production in the airways was also reduced, and eosinophil numbers were markedly reduced in the bronchoalveolar lavage (BAL)(3) fluid. IL-5 production was reduced in the lung tissue and BAL fluid of GM-CSF(-/-) mice, but IL-4 and IL-13 production, airway hyperresponsiveness, and serum IgE levels were not affected. The presence of eosinophils in perivascular but not peribronchial regions was suggestive of a cell migration defect in the airways of GM-CSF(-/-) mice. The CCR3 agonists CCL5 (RANTES) and CCL11 (eotaxin-1) were expressed at similar levels in GM-CSF(-/-) and wild-type mice. However, IFN-gamma mRNA and protein were increased in the lung tissue and BAL fluid in GM-CSF(-/-) mice, as were mRNA levels of the IFN-gamma-inducible chemokines CXCL9 (Mig), CXCL10 (IP-10), and CXCL11 (I-Tac). Interestingly, these IFN-gamma-inducible chemokines are natural antagonists of CCR3, suggesting that their overproduction in GM-CSF(-/-) mice contributes to the lack of airway eosinophils. These findings demonstrate distinctive abnormalities to a model of allergic asthma in the absence of GM-CSF.

Genetic susceptibility to atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disorder with an increasing prevalence in industrialized countries. AD belongs to the group of allergic disorders that includes food allergy, allergic rhinitis, and asthma. A multifactorial background for AD has been suggested, with genetic as well as environmental factors influencing disease development. Recent breakthroughs in genetic methodology have greatly augmented our understanding of the contribution of genetics to susceptibility to AD. A candidate gene association study is a general approach to identify susceptibility genes. Fifty three candidate gene studies (50 genes) have identified 19 genes associated with AD risk in at least one study. Significant associations between single nucleotide polymorphisms (SNPs) in chemokines (chymase 1-1903A > G), cytokines (interleukin13 Arg144Gln), cytokine receptors (interleukin 4 receptor 1727G > A) and SPINK 1258G > A have been replicated in more than one studies. These SNPs may be promising for identifying at-risk individuals. SNPs, even those not strongly associated with AD, should be considered potentially important because AD is a common disease. Even a small increase in risk can translate to a large number of AD cases. Consortia and international collaborative studies, which may maximize study efficacy and overcome the limitations of individual studies, are needed to help further illuminate the complex landscape of AD risk and genetic variations.

Human eosinophils show chemotaxis to lymphoid chemokines and exhibit antigen-presenting-cell-like properties upon stimulation with IFN-gamma, IL-3 and GM-CSF

BACKGROUND

Eosinophils are multifunctional leukocytes. Under physiological conditions, they circulate in the blood and through the tissues to serve their functions. In certain inflammatory states, they enter the T-cell areas of lymph nodes (LNs) that drain the inflamed tissue and communicate with T cells in LNs, but the underlying mechanism that regulates their trafficking to LNs is not yet fully explored. Here, we report that a human eosinophilic leukemia cell line, EoL-1, and human peripheral blood (PB) eosinophils become reactive to the lymphoid chemokines CCL21 and CCL25 upon stimulation.

METHODS

EoL-1 cells were differentiated with dibutyryl cyclic AMP (dEoL-1) and subsequently pulsed with IFN-gamma, IL-3 and GM-CSF. The eosinophil fraction was purified from normal human adult PB and incubated for 1 day with the same cytokine combination.

RESULTS

Upon cytokine stimulation, dEoL-1 cells expressed chemokine receptors CCR7, CCR9 and CCR3 and developed chemotactic responsiveness to CCL21, CCL25 and CCL11, which bind to the respective receptors. Human PB eosinophils also showed chemotactic responsiveness to CCL21 and CCL25 upon stimulation with IFN-gamma, IL-3 and GM-CSF. In addition, the cytokine-stimulated dEoL-1 cells expressed costimulatory molecules, including CD40, CD80, CD86 and HLA-DR, and also expressed a tolerogenic and Th2-polarizing enzyme, indoleamine 2,3-dioxygenase.

CONCLUSIONS

These in vitro observations raise the possibility that eosinophils may utilize lymphoid chemokines to enter LNs and serve antigen-presenting functions in the LN under certain inflammatory conditions.

Immunology

The concept of forbidden foods that should not be eaten goes back to the Garden of Eden and apart from its religious meanings it may also have foreshadowed the concept of foods that can provoke adverse reactions. Thus we could say that allergic diseases have plagued mankind since the beginning of life on earth. The prophet Job was affected by a condition that following the rare symptoms described by the Holy Bible might be identified as a severe form of atopic dermatitis (AD). The earliest record of an apparently allergic reaction is 2621 B.C., when death from stinging insects was first described by hieroglyphics carved into the walls of the tomb of Pharaoh Menes depicting his death following the sting of a wasp. In 79 A.D., the death of the Roman admiral Pliny the Elder was ascribed to the SO₂-rich gases emanating from the eruption of Mount Vesuvius. Hippocrates (460–377 B.C.) was probably the first to describe how cow’s milk (CM) could cause gastric upset and hives, proposing dietetic measures including both treatment and prevention for CM allergy.

Chemokines in tumor angiogenesis and metastasis

Chemokines are a large group of low molecular weight cytokines that are known to selectively attract and activate different cell types. Although the primary function of chemokines is well recognized as leukocyte attractants, recent evidences indicate that they also play a role in number of tumor-related processes, such as growth, angiogenesis and metastasis. Chemokines activate cells through cell surface seven trans-membranes, G-protein-coupled receptors (GPCR). The role played by chemokines and their receptors in tumor pathophysiology is complex as some chemokines favor tumor growth and metastasis, while others may enhance anti-tumor immunity. These diverse functions of chemokines establish them as key mediators between the tumor cells and their microenvironment and play critical role in tumor progression and metastasis. In this review, we present some of the recent advances in chemokine research with special emphasis on its role in tumor angiogenesis and metastasis.

Ontogeny of the eotaxins in human lung

The ontogeny of the C-C chemokines eotaxin-1, eotaxin-2, and eotaxin-3 has not been fully elucidated in human lung. We explored a possible role for eotaxin in developing lung by determining the ontogeny of eotaxin-1 (CCL11), eotaxin-2 (CCL24), eotaxin-3 (CCL26), and the eotaxin receptor, CCR3. We tested discarded surgical samples of developing human lung tissue using quantitative RT-PCR (QRT-PCR) and immunostaining for expression of CCL11, CCL24, CCL26, and CCR3. We assessed possible functionality of the eotaxin-CCR3 system by treating lung explant cultures with exogenous CCL11 and analyzing the cultures for evidence of changes in proliferation and activation of ERK1/2, a signaling pathway associated with CCR3. QRT-PCR analyses of 22 developing lung tissue samples with gestational ages 10-23 wk demonstrated that eotaxin-1 mRNA is most abundant in developing lung, whereas mRNAs for eotaxin-2 and eotaxin-3 are minimally detectable. CCL11 mRNA levels correlated with gestational age (P < 0.05), and immunoreactivity was localized predominantly to airway epithelial cells. QRT-PCR analysis detected CCR3 expression in 16 of 19 developing lung samples. Supporting functional capacity in the immature lung, CCL11 treatment of lung explant cultures resulted in significantly increased (P < 0.05) cell proliferation and activation of the ERK signaling pathway, which is downstream from CCR3, suggesting that proliferation was due to activation of CCR3 receptors by CCL11. We conclude that developing lung expresses the eotaxins and functional CCR3 receptor. CCL11 may promote airway epithelial proliferation in the developing lung.

Induction of TARC production by lipopolysaccharide and interleukin-4 in nasal fibroblasts

BACKGROUND

Th2 cell infiltration is a characteristic feature of allergic chronic sinusitis. However, the mechanisms that cause the predominance of Th2 cells in this disease have yet to be clarified. The airway is often exposed to not only Th2 cytokines but also bacterial products such as lipopolysaccharides (LPS). A CC chemokine, TARC, is a potent chemoattractant for Th2 cells. The objectives of this study were twofold. First, we examined whether nasal polyp fibroblasts were able to produce TARC when costimulated with LPS and IL-4. Second, we investigated whether there was any heterogeneity in TARC production among fibroblasts derived from different airway sites.

METHODS

Fibroblast lines were established from human biopsy tissue. The amount of TARC in the supernatants was measured by ELISA. The expression of TARC mRNA was quantitated by real-time PCR.

RESULTS

Combined stimulation with LPS and IL-4 significantly induced TARC production by nasal polyp fibroblasts in a dose- and time-dependent manner. This induction occurred in normal nasal fibroblasts, but not in normal lung fibroblasts.

CONCLUSIONS

Via TARC production, nasal fibroblasts may play an important role in the recruitment of Th2 cells into the sinus mucosa as well as nasal polyps. The heterogeneity in TARC production may reflect functional differences between upper and lower airway fibroblasts.

Inhibition effects of Moutan Cortex Radicis on secretion of eotaxin in A549 human epithelial cells and eosinophil migration

Eosinophils have been implicated in a broad range of diseases, most notably allergic conditions (e.g. asthma, rhinitis and atopic dermatitis) and inflammatory diseases. These diseases are characterized by an accumulation of eosinophils in the tissue. Defining the mechanisms that control eosinophil recruitment is fundamental to understanding how these diseases progress and may identify a novel target for drug therapy. Eotaxin is a potent eosinophil-specific chemokine that is released in the respiratory epithelium after allergic stimulation.

AIM OF THE STUDY

In this study, we determined whether Moutan Cortex Radicis (MCR), a plant extract, effects eotaxin secretion from A549 epithelial cells and eosinophil chemotaxis, and then examined the mechanism involved.

MATERIALS AND METHODS

Prior to assaying MCR's effects, A549 cells were stimulated with tumor necrosis factor-alpha (TNF-alpha), interleukin-4 (IL-4) and IL-1beta to induce expression of chemokines and adhesion molecules involved in eosinophil chemotaxis. In the presence of MCR, eotaxin, regulated on activation in normal T cells expressed and secreted (RANTES), IL-8, IL-16, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) transcripts were quantitated by real-time RT-PCR.

RESULTS

As a result, 0.01, 1, and 100 microg/ml of MCR treatments reduced eotaxin expression significantly and 0.01, 0.1, 1, 10, and 100 microg/ml of MCR reduced significantly eotaxin secretion. In addition, MCR treatment significantly inhibited eosinophil migration toward A549 medium. And 100 microg/ml of MCR suppressed the activated of nuclear factor (NF)-kappaB.

CONCLUSIONS

These findings indicate that suppressed eotaxin secretion by MCR treatment is due to the inhibition of NF-kappaB activation. Therefore, MCR might be of therapeutic value in treating asthma.

A comparison of inflammatory mediators released by basophils of asthmatic and control subjects in response to high-affinity IgE receptor aggregation

BACKGROUND

In human blood basophils, cross-linking the high-affinity IgE receptor Fc epsilonRI with multivalent antigen activates a signaling pathway leading to secretion of inflammatory mediators and cytokine production. Basophils are known to play an important role in the pathogenesis of asthma but there has been no comprehensive examination of the effectors these cells produce. Here a study of the transcription and release of a selection of chemokines and cytokines from basophils was undertaken.

METHODS

A Cartesian antibody array provided an effective method of assaying for multiple cytokines and chemokines simultaneously. Results were verified by RT-PCR and ELISA assays. This allowed the comparison of freshly prepared peripheral blood basophil responses to cross-linking of the high-affinity IgE receptor, with and without preincubation with IL-3.

RESULTS

Evidence that human blood basophils produce the chemokines MIP-5, eotaxin and GM-CSF was provided by antibody array and RT-PCR analyses. Preincubation with IL-3 enhanced the expression and release of IL-13, IL-8 and mRNA transcripts encoding MIP-5 and GATA2 in basophils from both asthmatic and control subjects. Leptin mRNA transcription, storage and release in basophils are described for the first time.

CONCLUSIONS

Surveying cytokine and chemokines stored and released by peripheral blood basophils shows that asthmatic and control subjects share similar profiles even when their degranulation responses are distinct. Evidence is provided for the production of leptin, GM-CSF, eotaxin and MIP-5 by peripheral blood basophils. IL-3 preincubation enhances the production and release of IL-8 upon IgE receptor cross-linking.

Increased expression of eotaxin-3 distinguishes between eosinophilic esophagitis and gastroesophageal reflux disease

Differentiating eosinophilic esophagitis from gastroesophageal reflux disease is important given their pathogenetic differences and responses to therapy. Eotaxins are a family of chemokines important for activation and recruitment of eosinophils mediated by their receptor, chemokine receptor-3 (CCR-3). Interleukin 5 (IL-5) is a key cytokine involved in many steps of eosinophil production and recruitment. The aim of this study was to compare the messenger RNA expression of the eotaxins, CCR-3, and IL-5 between well-characterized groups of patients with eosinophilic esophagitis, patients with gastroesophageal reflux disease, and healthy individuals. This was a retrospective study using esophageal biopsies from 33 patients with eosinophilic esophagitis, 20 patients with gastroesophageal reflux disease, and 17 healthy controls. Parameters studied included demographic features, presenting symptoms, endoscopic findings, histopathologic features, and messenger RNA levels of eotaxins 1, 2, and 3, CCR-3, and IL-5 by quantitative real-time polymerase chain reaction using formalin-fixed, paraffin-embedded tissue. Patients with eosinophilic esophagitis were predominantly males (M/F=3:1), with a mean age of 15.9 years and a mean eosinophil count of 55 per x400 high-power field. Patients with gastroesophageal reflux disease had a mean age of 31.5 years and a mean eosinophil count of 5.8 per high-power field. Total intraepithelial eosinophil and lymphocyte counts, the presence of superficial eosinophil clusters, microabscesses, and basal cell hyperplasia were all significantly associated with eosinophilic esophagitis as opposed to gastroesophageal reflux disease (P<.0001). The mean expression levels of eotaxin-3 were markedly elevated in patients with eosinophilic esophagitis as compared with the gastroesophageal reflux disease and healthy control groups (731+/-276, 31+/-12, and 1.5+/-0.4 pg/ng beta-actin, respectively; P<.001). Mean expression levels of eotaxins 1 and 2, IL-5, and CCR-3 were also significantly increased in the patients with eosinophilic esophagitis, albeit at lower levels than eotaxin-3. In conclusion, our results highlight the important contribution of eotaxin-3 in the pathogenesis of eosinophilic esophagitis. Determination of eotaxin-3 levels by real-time polymerase chain reaction on paraffinized, formalin-fixed tissue may be a useful test in the differentiation of eosinophilic esophagitis from gastroesophageal reflux disease.

The role of the complement anaphylatoxins in the recruitment of eosinophils

Eosinophils are blood and tissue immune cells that participate in a diverse range of activities normally beneficial for the host defense, but in circumstances of untoward inflammatory conditions these cells can be responsible for pathological responses. Accordingly the transit of eosinophils from the blood to tissues is a subject of considerable importance in immunology. In this article we review how the complement anaphylatoxins, C3a and C5a bring about eosinophil extravasation. These mediators do not merely provide a chemotactic or haptotactic gradient but are responsible for orchestrating innumerable responses by other cells types, including of endothelial cells, mast cells, and basophils in order to create an environment that is conducive for eosinophil infiltration. C5a has the capacity to prime the endothelium directly to present P-selectin, and C5a stimulated generation of eosinophil hydrogen peroxide and other oxidants can cause additional upregulation of endothelial P-selectin and ICAM-1. Moreover, the anaphylatoxins have the ability to recruit mast cells and basophils and can stimulate these cells to release IL-4 and IL-13, which by augmenting endothelial VCAM-1, convey some selectivity for eosinophils. The anaphylatoxins also have the capability to evoke the release and activation of eosinophil MMP-9, which is employed by this cell type to digest its way past the subendothelial matrix. Finally, because C3a and C5a can stimulate the generation of nitric oxide along with the secretion of histamine and LTC4 from several cell types, the anaphylatoxins can bring about an increase in vascular permeability that facilitates eosinophil accumulation at sites of allergic inflammation.

Minocycline delayed photoreceptor death in rds mice through iNOS-dependent mechanism

PURPOSE

To elucidate the role of activated microglia and nitric oxide (NO) in photoreceptor apoptosis in rds mice, and to investigate the effect of minocycline treatment on rds mice.

METHODS

Photoreceptor apoptosis in rds mice was detected by terminal dUTP transferase nick end labeling (TUNEL). Retinal microglial cells were identified by CD11b antibody. The mRNA expression of inducible nitric oxide synthase (iNOS) and chemokines were examined by reverse transcription polymerase chain reaction (RT-PCR) assay. The protein expression of iNOS was examined by immunohistochemistry and Western blotting analysis. The rds mice were treated intra-peritoneally from the second postnatal day (P2) with minocycline.

RESULTS

Accompanying photoreceptor degeneration in rds mice, microglia were activated and immigrated from inner retinal layer (IRL) to outer nuclear layer (ONL), and the expression of iNOS was up-regulated. Minocycline treatment reduced the iNOS expression and decreased the initial photoreceptor apoptosis, but did not provide long term ameliorative effect on the photoreceptor cell loss of rds mice.

CONCLUSIONS

NO played a major role in the initial photoreceptor apoptosis in rds mice. The migration of activated microglia to the ONL contributed to the subsequent photoreceptor cell death; minocycline treatment ameliorated the photoreceptor apoptosis in rds mice, and this protective effect was partly through iNOS-suppressive mechanism.

The effect of H1 antagonists carebastine and olopatadine on histamine induced expression of CC chemokines in cultured human nasal epithelial cells

BACKGROUND

CC chemokines have been shown to play an important role in inducing selective recruitment of inflammatory cells into local allergic inflammatory sites. CC chemokines are also known as histamine releasing factors. We previously showed that histamine enhances transcription of CC chemokines from nasal mucosa which leads to further induction of histamine release. This cyclic cascade may cause prolonged allergic inflammation. The aim of this study is to clarify the relationship between histamine and CC chemokine production by using human nasal epithelial cells (HNECs) and to examine the potential of H1 receptor (H1R) antagonists in new therapeutic approaches for the treatment of nasal allergy.

METHODS

HNECs were isolated from the nasal turbinates of patients diagnosed with nasal allergy. HNEC monolayers were cultured for 48 hours with or without histamine (10(-3) to 10(-5) mol/L). Furthermore, an H1R antagonist, either carebastine or olopatadine, was added to the supernatant (10(-3) to 10(-7) mol/L) 30 minutes before incubation with histamine. The expression of Regulated on Activation, Normal T-cell Expressed and Secreted (RANTES) and monocyte chemotactic protein-1 (MCP-1) in the culture media were measured by ELISA.

RESULTS

The release of RANTES and MCP-1 was significantly upregulated by histamine compared with the control group. Both carebastine and olopatadine inhibited the release of CC chemokine production to the control level in both groups.

CONCLUSIONS

This study suggests that the interaction between histamine and CC chemokines may prolong allergic inflammation in human nasal mucosa. We also demonstrate the potential use of H1R antagonists in new therapeutic approaches to the treatment of nasal allergy through inhibiting this histamine-CC chemokine interaction.

Pathophysiology of white-tailed deer vaccinated with porcine zona pellucida immunocontraceptive

White-tailed deer (n=14 treated, n=7 control) were examined postmortem to identify any possible pathophysiology resulting from PZP immunocontraception vaccination. Deer were treated twice in 1997; given a booster in 1998, with six being revaccinated in September 2000. Granulomas were found at injection sites of most deer, even 2 years post-treatment. Eosinophilic oophoritis occurred in 6 of 8 (75%) deer vaccinated in 1998, and 3 of 6 (50%) revaccinated in 2000. The 2000 revaccinates without oophoritis, had significantly fewer normal secondary follicles than control females (P=0.03), and deer in the 1998 treatment group (P=0.04). PZP immunocontraceptive vaccine elicited ovarian pathologies in deer similar to those observed in other species.

Cloning, expression and functional analysis of a novel-chemokine gene of Japanese flounder, Paralichthys olivaceus, containing two additional cysteines and an extra fourth exon

A CC chemokine gene (JFCCL3) was cloned and sequenced from Japanese flounder, Paralichthys olivaceus. The JFCCL3 cDNA contains an open reading frame of 288 nucleotides encoding 95 amino acid residues. The predicted amino acid sequence of JFCCL3 showed the conserved cysteine of the beta chemokine plus two additional cysteines. The genomic sequence consists of two isoforms: JFCCL3.1 and JFCCL3.2 with sizes of 1.8 and 1.2kb, respectively. Both isoforms contain three introns and four exons. RT-PCR showed that JFCCL3 is constitutively expressed in most tissues including lymphoid organs. Using quantitative real-time RT-PCR, the highest expression of JFCCL3 transcripts was observed in PBLs at 3h post-stimulation with Con A/PMA and at 1h post-stimulation with LPS. A phylogenetic analysis showed that JFCCL3 is more closely related to fractalkines than to other mammalian beta chemokines. A chemotaxis assay showed that recombinant JFCCL3 protein has bioactivity for Japanese flounder leukocyte attraction at concentrations from 0.01 to 10 microg/ml.

Eosinophils in the pathogenesis of allergic airways disease

Eosinophils are traditionally thought to form part of the innate immune response against parasitic helminths acting through the release of cytotoxic granule proteins. However, they are also a central feature in asthma. From their development in the bone marrow to their recruitment to the lung via chemokines and cytokines, they form an important component of the inflammatory milieu observed in the asthmatic lung following allergen challenge. A wealth of studies has been performed in both patients with asthma and in mouse models of allergic pulmonary inflammation to delineate the role of eosinophils in the allergic response. Although the long-standing association between eosinophils and the induction of airway hyper-responsiveness remains controversial, recent studies have shown that eosinophils may also promote airway remodelling. In addition, emerging evidence suggests that the eosinophil may also serve to modulate the immune response. Here we review the highly co-ordinated nature of eosinophil development and trafficking and the evolution of the eosinophil as a multi-factoral leukocyte with diverse functions in asthma.

Eosinophilic esophagitis: an allergist's approach

OBJECTIVE

To enhance the recognition of eosinophilic esophagitis by reviewing the presentation, diagnosis, and pathogenesis and then summarizing the epidemiology and treatment options.

DATA SOURCES

MEDLINE was searched for articles using the keywords esophagitis and either allergy or eosinophil. Additional sources include searches limited to therapy, including corticosteroids and leukotrienes, and those limited to review articles, including chemokines and cytokines, from January 1990 to April 2006. All searches were limited to the English language.

STUDY SELECTION

The authors selected relevant and current sources for inclusion in this review.

RESULTS

Eosinophilic esophagitis is a diagnosis made by identifying 20 to 24 eosinophils per high-power field on examination of esophageal biopsy specimens. In recent years, a marked increase in incidence worldwide may have occurred. Although the pathogenesis is still unclear, therapy involves the use of corticosteroids and appropriate dietary elimination.

CONCLUSION

Patients with atopy, especially males, who present with dysphagia, reflux symptoms, vomiting, abdominal pain, or failure to thrive should be considered for endoscopy to establish the diagnosis of eosinophilic esophagitis.

Percutaneous application of peptidoglycan from Staphylococcus aureus induces eosinophil infiltration in mouse skin

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease with immunopathologic features that vary depending on the duration of the lesion. The lesioned skin of AD patients shows an increased number of inflammatory cells such as eosinophils, mast cells and mononuclear cells in the dermis and superficial Staphylococcus aureus colonization.

OBJECTIVE

The purpose of this study was to determine the effects of peptidoglycan (PEG) from S. aureus on eosinophil induction in murine skin.

METHODS

PEG was applied to the barrier-disrupted abdominal skin of mice every 5 days. Twenty days later, the number of eosinophils in the abdominal skin was counted. The cytokine response in the skin was investigated by RT-PCR and immunohistological analysis. The regulated-upon activation in normal T cells expressed and secreted (RANTES) production from cultured epidermal cells was measured by ELISA.

RESULTS

The skin of mice treated with PEG showed a significantly increased number of eosinophils compared with that of mice treated with vehicle alone. In addition, application of PEG to the abdominal skin of mice increased the expression of mRNA for RANTES, but not that of mRNA for eotaxin, eotaxin-2 and monocyte chemotactic protein-3 in the skin. Immunohistologic analysis demonstrated that the levels of RANTES transcripts corresponded with those of protein synthesis in the epidermis. In vitro experiments using epidermal Langerhans cells (LCs) and keratinocytes (KCs) showed that RANTES production was induced by LCs but not by KCs stimulated with PEG. Furthermore, an intraperitoneal injection of anti-RANTES antibody neutralized the induction of eosinophils in the skin.

CONCLUSION

These results suggest that PEG may have an ability to induce eosinophil infiltration in the skin through RANTES production by LCs, and would explain the role of S. aureus colonization in AD patients.

Eotaxin selectively binds heparin. An interaction that protects eotaxin from proteolysis and potentiates chemotactic activity in vivo

An important feature of chemokines is their ability to bind to the glycosaminoglycan (GAG) side chains of proteoglycans, predominately heparin and heparan sulfate. To date, all chemokines tested bind to immobilized heparin in vitro, as well as cell surface heparan sulfate in vitro and in vivo. These interactions play an important role in modulating the action of chemokines by facilitating the formation of stable chemokine gradients within the vascular endothelium and directing leukocyte migration, by protecting chemokines from proteolysis, by inducing chemokine oligomerization, and by facilitating transcytosis. Despite the importance of eotaxin in eosinophil differentiation and recruitment being well established, little is known about the interaction between eotaxin and GAGs and the functional consequences of such an interaction. Here we report that eotaxin binds selectively to immobilized heparin with high affinity (K(d) = 1.23 x 10(-8) M), but not to heparan sulfate or a range of other GAGs. The interaction of eotaxin with heparin does not promote eotaxin oligomerization but protects eotaxin from proteolysis directly by plasmin and indirectly by cathepsin G and elastase. In vivo, co-administration of eotaxin and heparin is able to significantly enhance eotaxin-mediated eosinophil recruitment in a mouse air-pouch model. Furthermore, when heparin is co-administered with eotaxin at a concentration that does not normally result in eosinophil infiltration, eosinophil recruitment occurs. In contrast, heparin does not enhance eotaxin-mediated eosinophil chemotaxis in vitro, suggesting protease protection or haptotactic gradient formation as the mechanism by which heparin enhances eotaxin action in vivo. These results suggest a role for mast cell-derived heparin in the recruitment of eosinophils, reinforcing Th2 polarization of inflammatory responses.

Surfactant protein D inhibits early airway response in Aspergillus fumigatus-sensitized mice

BACKGROUND

The surfactant protein SP-D has been reported to reduce bronchial hyper-responsiveness, blood eosinophilia, and T-helper type 2 cytokines in models of allergic asthma. However, little is known about the functional effect of SP-D on the early airway response upon allergen inhalation, which is an important feature of this disease.

OBJECTIVE

We investigated whether SP-D is able to reduce the immediate allergen-induced mediator release and the early bronchial obstruction in addition to its effects on airway inflammation and bronchial hyperresponsiveness in an Aspergillus fumigatus mouse asthma model.

METHODS

A. fumigatus-sensitized mice were treated with a recombinant fragment of human SP-D or placebo. Lung functions were measured in orotracheally intubated, spontaneously breathing animals using body plethysmography. In addition, passively sensitized precision-cut lung slices (PCLS) were used to determine the effect of SP-D on allergen-induced histamine release.

RESULTS

SP-D inhibited the allergen-induced early airway response and reduced airway hyperresponsiveness compared with placebo. Eosinophilia in bronchoalveolar lavage and lung tissue was reduced after SP-D treatment, possibly by reducing eotaxin levels in the lung. Furthermore, SP-D treatment reduced the allergen-induced histamine release from PCLS.

CONCLUSION

These data suggest that SP-D not only reduces allergen-induced eosinophilic inflammation and airway hyperresponsiveness but also provides protection against early airway obstruction by inhibition of early mediator release.

A dual antagonist for chemokine CCR3 receptor and histamine H1 receptor

Eosinophilic chemokines and histamine play distinct but important roles in allergic diseases. Inhibition of both eosinophilic chemokines and histamine, therefore, is an ideal strategy for the treatment of allergic inflammation, such as asthma, allergic rhinitis, and atopic dermatitis. YM-344484 was found to potently inhibit both the CCL11-induced Ca2+ influx in human CCR3-expressing cells (Kb=1.8 nM) and histamine-induced Ca2+ influx in histamine H1 receptor-expressing PC3 cells (Kb=47 nM). YM-344484 also inhibited the CCL11-induced chemotaxis of human CCR3-expressing cells (IC50=6.2 nM) and CCL11-induced eosinophil-derived neurotoxin release from human eosinophils (IC50=19 nM). Orally administered YM-344484 inhibited the increase in histamine-induced vascular permeability in mice (82% inhibition at a dose of 10 mg/kg) and the accumulation of eosinophils in a mouse asthma model (74% at a dose of 300 mg/kg). These results indicate that YM-344484, a novel and functional dual antagonist for chemokine CCR3 receptor and histamine H1 receptor, is an attractive candidate for development as a novel anti-allergic inflammation drug.

Eosinophil cationic protein and chemokines in nasopharyngeal secretions of infants with respiratory syncytial virus (RSV) bronchiolitis and non-RSV bronchiolitis

Bronchiolitis is a risk factor for the development of childhood asthma. Eosinophilic inflammation in airways plays an important role in the pathophysiology of both bronchiolitis and asthma. To investigate this inflammation, we measured the eosinophil cationic protein (ECP), regulated on activation normal T-cell expressed and secreted (RANTES) and eotaxin levels in nasopharyngeal secretions (NPS). Twenty-eight patients with RSV bronchiolitis (RSV group), 11 patients with non-RSV bronchiolitis (non-RSV group) and 7 controls were enrolled in this study. ECP, RANTES, and eotaxin levels were measured by enzyme immunoassays. The ECP level in the NPS of the RSV group was significantly higher than that in the NPS of the non-RSV group and controls. RANTES and eotaxin levels in infants with bronchiolitis were significantly higher than those in the controls, but there was no significant difference between the RSV and non-RSV groups. In conclusion, with regard to eosinophilic airway inflammation, as compared with non-RSV bronchiolitis, RSV bronchiolitis may be more similar to childhood asthma.

Effects of antisense oligodeoxynucleotides targeting CCR3 on the airway response to antigen in rats

Asthma is characterized by airway hyperresponsiveness (AHR) and inflammation, consisting predominantly of eosinophils within the airway lumen and walls. Eosinophil recruitment to the airways is mediated mainly by eotaxin and other chemokines that bind to the CC-chemokine receptor-3 (CCR3), which is highly expressed on eosinophils. This study assessed whether topical inhibition of CCR3 mRNA expression by phosphorothioate antisense oligodeoxynucleotides (AS-ODNs) modifies pulmonary eosinophilia and AHR in an antigen-induced allergic asthma model in Brown Norway (BN) rats. Results show that specific inhibition of CCR3 expression in the lungs by an AS-ODN (AS4) reduced total eosinophil infiltration and the percentage of eosinophils into the airways of ovalbumin challenged rats. Moreover, reduction in CCR3 mRNA levels was correlated with a decrease in CCR3 protein in lung tissue. In addition, AS4 treatment had no effect on circulating eosinophils or on eosinophils in the bone marrow. Finally, AHR was significantly decreased in AS4-treated rats when compared with rats treated with a mismatch AS-ODN. In conclusion, inhibition of the expression of CCR3 decreased pulmonary eosinophilia and reduced AHR after antigen challenge in rats. Topical inhibition of CCR3 expression, using an AS-ODN, could represent a novel approach for the treatment of asthma.

A potent human anti-eotaxin1 antibody, CAT-213: isolation by phage display and in vitro and in vivo efficacy

The CC chemokine, eotaxin1 (CCL11) is an important regulator of eosinophil function. A marked accumulation of eosinophils in tissues has been correlated with the up-regulation of eotaxin1 expression in several diseases. The potential therapeutic value of neutralizing the effects of eotaxin1 in inflammatory conditions (including asthma) is under investigation. A human single-chain fragment variable antibody that neutralizes human eotaxin1 (CAT-212) was produced using antibody phage display and converted to whole antibody IgG4 format (CAT-213). A novel approach to lead optimization in which the length of the variable heavy chain complementarity-determining region 3 was reduced by one amino acid resulted in an increase in potency of >1000-fold compared with the parent anti-eotaxin1 antibody. The optimized antibody binds eotaxin1 with high affinity (80.4 pM) and specificity. CAT-213 and CAT-212 do not bind or neutralize a range of other human proteins including human monocyte chemoattractant protein-1, a structurally similar chemokine. CAT-213 neutralizes the ability of eotaxin1 to cause an increase in intracellular calcium signaling (with an IC(50) value of 2.86 nM), migration of CCR3-expressing L1.2 cells (with an IC(50) value of 0.48 nM), and inhibition of the eotaxin1-evoked shape change of human eosinophils in vitro (with an IC(50) of 0.71 nM). Local administration of CAT-213 to mice (1-100 microg kg(-1)) attenuates dermal eosinophilia induced by human eotaxin1, achieving >90% inhibition of eosinophil influx. CAT-213 may therefore be of therapeutic value in inhibiting diseases in which eotaxin1 and eosinophils play a major role, for example, severe asthma.

Effects of inhaled eotaxin on airway function and inflammatory cell influx in sensitised and non-sensitised guinea pigs

Eotaxin is a chemokine that has high potency and selectivity as a chemoattractant agent for eosinophils, signalling exclusively through the CCR3 receptor. Eotaxin is upregulated in the lungs within 3 h of antigen challenge, levels peak at 6 h in lung tissue and bronchoalveolar (BAL) fluid, and fall within 12 h of exposure. This study aimed to look at the effect(s) of eotaxin inhalation on airway function in guinea pigs, to determine if the expected inflammatory cell (eosinophil) infiltration could induce airway hyperreactivity (AHR) and a bronchoconstrictor response equivalent to the late asthmatic response (LAR) seen after antigen challenge. Animals were sensitised with 100 microg/ml OA with a dose on days 1 and 5. Airway responses to inhaled eotaxin (10 or 20 microg/ml) were determined by whole body plethysmography as the change in specific airway conductance (sGaw). Inhaled histamine (1mM) was used to investigate AHR, and cell influx was determined by BAL. Senitised animals exposed to 10 microg/ml eotaxin did not reveal a bronchoconstrictor response or AHR and cellular infiltration to the lungs was not evident 24 h after exposure. Both sensitised and non-sensitised animals exposed to 20 microg/ml eotaxin however revealed a significant bronchoconstrictor response 6h post-challenge, with reductions in sGaw of -27.0+/-6.6% and -32.3+/-6.8%, respectively. Both groups also displayed a bronchoconstrictor response to inhaled histamine 24h after exposure, indicating AHR, and a significant increase in both total and differential cell counts. Sensitised animals, however, revealed a significant increase in cell influx compared to non-sensitised animals. Nebulised eotaxin can reveal a LAR, AHR to inhaled histamine, and cellular infiltration to the lungs, possibly via the mobilisation of eosinophils from the bone marrow, and their subsequent recruitment to the airways.

Evidence of a functional role for mast cells in the development of type 1 diabetes mellitus in the BioBreeding rat

Human type 1 diabetes mellitus (T1DM) arises through autoimmune destruction of pancreatic beta cells and is modeled in many respects by the lymphopenic and spontaneously diabetic BioBreeding (BB) DRlyp/lyp rat. Previously, preonset expression profiling of whole DRlyp/lyp pancreatic lymph nodes (PLN) revealed innate immune activity, specifically that of mast cells and eosinophils. Furthermore, we observed that pancreatic islets of DRlyp/lyp rats as well as those of diabetes-inducible BB DR(+/+) rats potentially recruit innate cells through eotaxin expression. Here we determine that lifelong eotaxin expression begins before 40 days of life and is localized specifically to beta cells. In this report, we find that PLN mast cells are more abundant in DRlyp/lyp compared with related BB DR(+/+) rats (2.1 +/- 0.9% vs 0.9 +/- 0.4% of total cells, p < 0.0001). DRlyp/lyp PLN mast cell gene expression profiling revealed an activated population and included significant overrepresentation of transcripts for mast cell protease 1, cationic trypsinogen, carboxypeptidase A, IL-5, and phospholipase Cgamma. In the DR(+/+) rat, which develops T1DM upon depletion of T regulator cells, mast cells displayed gene expression consistent with the negative regulation of degranulation, including significant overrepresentation of transcripts encoding tyrosine phosphatase SHP-1, lipid phosphatase SHIP, and E3 ubiquitin ligase c-Cbl. To recapitulate the negative mast cell regulation observed in the DR(+/+) rats, we treated DRlyp/lyp rats with the mast cell "stabilizer" cromolyn, which significantly (p < 0.05) delayed T1DM onset. These findings are consistent with a growing body of evidence in human and animal models, where a role for mast cells in the initiation and progression of autoimmune disease is emerging.

Allergens induce enhanced bronchoconstriction and leukotriene production in C5 deficient mice

BACKGROUND

Previous genetic analysis has shown that a deletion in the complement component 5 gene-coding region renders mice more susceptible to allergen-induced airway hyperresponsiveness (AHR) due to reduced IL-12 production. We investigated the role of complement in a murine model of asthma-like pulmonary inflammation.

METHODS

In order to evaluate the role of complement B10 mice either sufficient or deficient in C5 were studied. Both groups of mice immunized and challenged with a house dust extract (HDE) containing high levels of cockroach allergens. Airways hyper-reactivity was determined with whole-body plesthysmography. Bronchoalveolar lavage (BAL) was performed to determine pulmonary cellular recruitment and measure inflammatory mediators. Lung homogenates were assayed for mediators and plasma levels of IgE determined. Pulmonary histology was also evaluated.

RESULTS

C5-deficient mice showed enhanced AHR to methylcholine challenge, 474% and 91% increase above baseline Penh in C5-deficient and C5-sufficient mice respectively, p < 0.001. IL-12 levels in the lung homogenate (LH) were only slightly reduced and BAL IL-12 was comparable in C5-sufficient and C5-deficient mice. However, C5-deficient mice had significantly higher cysteinyl-leukotriene levels in the BAL fluid, 1913 +/- 246 pg/ml in C5d and 756 +/- 232 pg/ml in C5-sufficient, p = 0.003.

CONCLUSION

These data demonstrate that C5-deficient mice show enhanced AHR due to increased production of cysteinyl-leukotrienes.

The adipocyte fatty acid-binding protein aP2 is required in allergic airway inflammation

The adipocyte fatty acid-binding protein aP2 regulates systemic glucose and lipid metabolism. We report that aP2, in addition to being abundantly expressed by adipocytes, is also expressed by human airway epithelial cells and shows a striking upregulation following stimulation of epithelial cells with the Th2 cytokines IL-4 and IL-13. Regulation of aP2 mRNA expression by Th2 cytokines was highly dependent on STAT6, a transcription factor with a major regulatory role in allergic inflammation. We examined aP2-deficient mice in a model of allergic airway inflammation and found that infiltration of leukocytes, especially eosinophils, into the airways was highly dependent on aP2 function. T cell priming was unaffected by aP2 deficiency, suggesting that aP2 was acting locally within the lung, and analysis of bone marrow chimeras implicated non-hematopoietic cells, most likely bronchial epithelial cells, as the site of action of aP2 in allergic airway inflammation. Thus, aP2 regulates allergic airway inflammation and may provide a link between fatty acid metabolism and asthma.

Activation of the liver X receptor protects against hepatic injury in endotoxemia by suppressing Kupffer cell activation

Recent reports have demonstrated that liver X receptors (LXRs) of the nuclear receptor family have anti-inflammatory effects on macrophages. Here we examine whether activation of LXR by the synthetic agonist GW3965 can ameliorate the liver injury/dysfunction caused by endotoxins in the rat. Male Wistar rats received GW3965 (0.3 mg/kg) or vehicle (50% dimethyl sulfoxide) 30 min before coadministration of lipopolysaccharide (LPS, 5 mg/kg i.v.) and peptidoglycan (1 mg/kg i.v.). Treatment with GW3965 attenuated the increase in the plasma levels of alanine aminotransferase and bilirubin (markers of liver injury/dysfunction) as well as the focal hepatocyte necrosis (histology) caused by coadministration of LPS and peptidoglycan. This protective effect of GW3965 treatment was associated with reduced infiltration of mast cells in the liver (histopathology) and reduced gene expression of the chemokines eotaxins 1 and 2, whereas MIP-2 mRNA levels were not affected. Plasma levels of tumor necrosis factor alpha and prostaglandin E2 were significantly attenuated by GW3965, whereas plasma interleukins 6 and 10 were not altered. High expression of LXRalpha mRNA was observed in Kupffer cell cultures, suggesting that Kupffer cells are targets of GW3965. Subsequent in vitro studies in Kupffer cells demonstrated that exposure to GW3965 attenuated the LPS-induced release of tumor necrosis factor alpha and prostaglandin E2 in a dose-dependent manner. In conclusion, this study demonstrates that activation of LXR by GW3965 protects against liver injury and dysfunction in a rat model of endotoxemia, in part by exerting an anti-inflammatory effect on Kupffer cells.

Selective inhibition of eosinophil influx into the lung by small molecule CC chemokine receptor 3 antagonists in mouse models of allergic inflammation

CC chemokine receptor (CCR) 3 is a chemokine receptor implicated in recruiting cells, particularly eosinophils (EPhi), to the lung in episodes of allergic asthma. To investigate the efficacy of selective, small molecule antagonists of CCR3, we developed a murine model of EPhi recruitment to the lung. Murine eotaxin was delivered intranasally to mice that had previously received i.p. injections of ovalbumin (OVA), and the effects were monitored by bronchoalveolar lavage. A selective eosinophilic influx was produced in animals receiving eotaxin but not saline. Furthermore, the number of EPhi was concentration- and time-dependent. Although anti-CCR3 antibody reduced the number of EPhi, the effect of eotaxin in OVA-sensitized mice was not a direct chemotactic stimulus because mast cell deficiency (in WBB6F1-Kitw/Kitw-v mice) significantly reduced the response. Two representative small molecule CCR3 antagonists from our program were characterized as being active at mouse CCR3. They were administered p.o. to wild-type mice and found to reduce eotaxin-elicited EPhi selectively in a dose-dependent manner. Pump infusion of one of the inhibitors to achieve steady-state levels showed that efficacy was not achieved at plasma concentrations equivalent to the in vitro chemotaxis IC90 but only at much higher concentrations. To extend the results from our recruitment model, we tested one of the inhibitors in an allergenic model of airway inflammation, generated by adoptive transfer of OVA-sensitive murine T helper 2 cells and aerosolized OVA challenge of recipient mice, and found that it inhibited EPhi recruitment. We conclude that small molecule CCR3 antagonists reduce pulmonary eosinophilic inflammation elicited by chemokine or allergenic challenge.

Rosmarinic acid as a downstream inhibitor of IKK-beta in TNF-alpha-induced upregulation of CCL11 and CCR3

1. Tumor necrosis factor (TNF)-alpha is known to induce the expression of CCL11 and CCR3 via the activation of NF-kappaB. CCL11 (eotaxin), the C-C chemokine, is a potent chemoattractant for eosinophils and Th2 lymphocytes, and CCR3 is the receptor for CCL11. 2. In order to determine the effects of rosmarinic acid on the TNF-alpha-induced upregulation of CCL11 and CCR3 in human dermal fibroblasts, we performed an enzyme-linked immunosorbent assay for CCL11 and a Western blot assay for CCR3. The TNF-alpha-induced expression of CCL11 and CCR3 genes was attenuated by rosmarinic acid. 3. In our NF-kappaB luciferase reporter system, TNF-alpha-induced NF-kappaB activation was observed to be reduced by rosmarinic acid. In accordance with this result, rosmarinic acid also inhibited TNF-alpha-induced phosphorylation and degradation of IkappaB-alpha, as well as nuclear translocation of NF-kappaB heterodimer induced by TNF-alpha. This suggests that rosmarinic acid downregulates the expression of CCL11 and CCR3 via the inhibition of NF-kappaB activation signaling. 4. Using the NF-kappaB luciferase reporter system, Western blot analysis, and IKK-beta activity assay, we determined that rosmarinic acid inhibits IKK-beta activity in NF-kappaB signaling, which upregulates the expression of CCL11 and CCR3. Additionally, TNF-alpha-induced secretion of soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1 molecules was found to be attenuated by rosmarinic acid. 5. Our results show that rosmarinic acid inhibits the expression of CCL11 and CCR3 by suppressing the IKK-beta activity in NF-kappaB activation signaling. Further, these results suggest that rosmarinic acid might inhibit the expression of NF-kappaB promoter-related genes.

Extracellular matrix regulates enhanced eotaxin expression in asthmatic airway smooth muscle cells

RATIONALE

Altered airway smooth muscle (ASM) function and enrichment of the extracellular matrix (ECM) with fibronectin and collagen are key features of asthma. Previously, we have reported these ECM proteins enhance ASM synthetic function.

OBJECTIVE

We compared ASM cultured from endobronchial biopsies from subjects with and without asthma to assess if asthmatic cells were hypersecretory and determined whether the underlying mechanism involved autocrine ECM production.

METHODS AND MEASUREMENTS

Cells from subjects with and without asthma were cultured on plastic or in plates precoated with ECM proteins. Cytokine production was evaluated by enzyme-linked immunosorbent assay and by reverse transcriptase-polymerase chain reaction. Function-blocking integrin antibodies were used to identify integrin involvement.

RESULTS

Baseline eotaxin and its production after stimulation with interleukin (IL)-13, IL-1beta, or tumor necrosis factor-alpha was increased (2.5- to 6.0-fold) in ASM cells cultured from subjects with asthma compared with healthy subjects. When seeded on ECM from asthmatic ASM, IL-13-dependent eotaxin release from healthy or asthmatic ASM was enhanced compared with culture on healthy ECM. The ECM substrates fibronectin and type I collagen each enhanced IL-13-dependent eotaxin release, and Western immunoblot indicated that fibronectin expression was higher in asthmatic ASM cells. Integrin-blocking antibodies revealed that alpha5beta1 was required for more than 50% of the enhanced IL-13-dependent eotaxin release by ASM cells from subjects with asthma, whereas alpha2beta1 or alphavbeta3 neutralization lacked effect.

CONCLUSION

The data indicate that ASM cells cultured from subjects with asthma are hypersecretory compared with cells from healthy donors and that autocrine fibronectin secretion acting via alpha5beta1 in part underlies this effect.

Endothelial and epithelial expression of eotaxin-2 (CCL24) in nasal polyps

BACKGROUND

Nasal polyposis is mostly associated with eosinophilia of mucosal tissue. This points to the implication of CC chemokines in nasal eosinophilia. Recently the CC chemokine eotaxin-2 (CCL24) was identified. This study was initiated to localize the cellular source, analyze expression of mRNA, and quantify protein synthesis of CCL24.

METHODS

Specimens of nasal inferior turbinates from controls and polypous tissue from patients suffering from chronic polypous sinusitis were collected. Furthermore, fibroblasts and epithelial cells were cultured. CCL24 protein was analyzed by immunohistochemistry and ELISA, expression of mRNA by SQ-RT-PCR.

RESULTS

CCL24 was observed in endothelial and epithelial cells. Specimens from patients expressed significantly (>2fold) more CCL24 mRNA than controls. Fibroblasts and unstimulated cells did not express CCL24 mRNA. Upon stimulation with TNF-alpha, INF-gamma, IL-4, or costimulation with TNF-alpha and INF-gamma CCL24 mRNA was significantly enhanced (3.2-19.6%). In controls, fibroblast, and unstimulated cells CCL24 protein was below detection limit. Most polyps comprised significant amounts of CCL24 (mean 0.24 ng/mg). TNF-alpha, INF-gamma or IL-4 induced CCL24 protein (0.1-0.3 ng/ml) in epithelial cells. Costimulation with TNF-alpha and IL-4 (0.1-30 and 1-30 ng/ml, respectively) synergistically induced synthesis of CCL24 protein (0.18-0.31 ng/ml).

CONCLUSION

In nasal polyps endothelial and epithelial cells are obviously the main source of CCL24, which was shown for transcription (mRNA) and production (protein) levels and was associated with diseases. Results gave evidence of CLL24- directed migration of cells from inside (the bloodstream) to the epithelial side (mucosa) in eosinophilic inflammatory diseases, e.g. nasal polyposis.

Association of plasma eotaxin levels with the presence and extent of angiographic coronary artery disease

Eotaxin (CCL11) is an eosinophil-specific chemoattractant which has been found to be highly expressed at sites of vascular pathology. In the present study, we aimed to evaluate the association of plasma eotaxin levels with the presence and extent of angiographic coronary artery disease (CAD). Three hundred and fifty six consecutive patients attending for elective coronary angiography were investigated. Compared with 111 patients without CAD, 245 with CAD showed higher eotaxin concentrations [median (interquartile range): 76.0 (56.3-103.0)pg/ml versus 116.0 (80.5-162.0)pg/ml, respectively; P<0.001]. Importantly, a significant Spearman correlation was found between eotaxin levels and the extent score of coronary artery stenosis (r=0.449, P<0.001). A stepwise increase in plasma levels of eotaxin was also found depending on the number of >50% coronary stenosis: median value 76.0 pg/ml in CAD(-) subjects, 96.0 pg/ml in 1-vessel disease, 128.0 pg/ml in 2-vessel disease, and 129.0 pg/ml in 3-vessel disease (P<0.001 for trend). After confounding variables were controlled for, multiple stepwise regression analysis demonstrated that plasma eotaxin was an independent predictor of angiographic extent of CAD (beta=0.426, P<0.001). Our data suggest that increased eotaxin levels are associated with the presence of CAD and that circulating levels of this chemokine may reflect the extent of coronary atherosclerosis.

Mast cell beta-tryptase selectively cleaves eotaxin and RANTES and abrogates their eosinophil chemotactic activities

Recent studies have shown that a lack of eosinophils in asthmatic airway smooth muscle (ASM) bundles in contrast to the large number of mast cells is a key feature of asthma. We hypothesized that this is caused by beta-tryptase, the predominant mast cell-specific protease, abrogating the eosinophil chemotactic activities of ASM cell-derived eosinophil chemoattractants such as eotaxin and RANTES. We studied the effect of beta-tryptase on the immunoreactivities of human ASM cell-derived and recombinant eotaxin and other recombinant chemokines that are known to be produced by human ASM cells. We report in this study that purified beta-tryptase markedly reduced the immunoreactivity of human ASM cell-derived and recombinant eotaxin, but had no effect on eotaxin mRNA expression. The effect was mimicked by recombinant human beta-tryptase in the presence of heparin and was reversed by heat inactivation and the protease inhibitor leupeptin, suggesting that the proteolytic activity of tryptase is required. beta-Tryptase also exerted similar effects on recombinant RANTES, but not on the other chemokines and cytokines that were screened. Furthermore, a chemotaxis assay revealed that recombinant eotaxin and RANTES induced eosinophil migration concentration-dependently, which was abrogated by pretreatment of these chemokines with beta-tryptase. Another mast cell protease chymase also markedly reduced the immunoreactivity of eotaxin, but had no effect on RANTES and other chemokines and did not affect the influence of beta-tryptase on RANTES. These findings suggest that mast cell beta-tryptase selectively cleaves ASM-derived eotaxin and RANTES and abrogates their chemotactic activities, thus providing an explanation for the eosinophil paucity in asthmatic ASM bundles.

Alanine scanning mutagenesis of the chemokine receptor CCR3 reveals distinct extracellular residues involved in recognition of the eotaxin family of chemokines

Despite considerable differences in primary structure, the chemokines eotaxin-1/CCL11, eotaxin-2/CCL24 and eotaxin-3/CCL26 signal via a single receptor, CCR3, but exhibit different potencies and efficacies. To examine receptor/ligand interactions in more detail, we performed alanine scanning mutagenesis of 21 charged residues within the extracellular loops (ECLs) of CCR3. Following transient expression in the L1.2 cell line, CCR3 mutants were assessed for their ability to be expressed at the cell surface, bind CCL11 and induce chemotactic responses to CCL11, CCL24 and CCL26. The majority of constructs were well expressed at the cell surface and bound CCL11 with low nanomolar affinity. Exceptions to this rule included the mutants E175A and E176A (ECL2) which were poorly expressed and responded weakly to all three ligands in chemotaxis assays. In contrast, the mutants K26 (amino-terminus) E179 and E180 (ECL2) responded in chemotaxis assays to CCL11 and CCL24, but not to CCL26. Mutation of residues in ECL3 was informative, with the D272A, K277A and D280A mutants exhibiting reduced chemotactic responses to two or more of the three ligands examined, despite being expressed on the cell surface at levels similar to WT CCR3. This suggests a major role for ECL3 in the recognition of all three eotaxins. In summary, distinct acidic and basic residues within CCR3 determine both receptor expression and activation by the eotaxins. Determining how these chemokines interact with their receptor at the molecular level should increase our understanding of the process of chemokine receptor activation.

Eotaxin polymorphisms and serum total IgE levels in children with asthma

BACKGROUND

Eotaxin (chemokine, CC motif, ligand; CCL11) is a potent eosinophil chemoattractant strongly implicated in the pathobiology of asthma. Genetic variation at the CCL11 locus has been correlated with serum total IgE, blood eosinophil counts, and circulating eotaxin protein levels in several case-control asthma studies. Family-based association studies of CCL11 genetic variants have not been reported to date.

OBJECTIVE

To evaluate 9 common CCL11 single nucleotide polymorphisms (SNPs) in nuclear families ascertained through patients with asthma participating in the Childhood Asthma Management Program study.

METHODS

Single nucleotide polymorphism genotyping was performed by using minisequencing and probe hybridization platforms. Family-based association analysis for asthma and 4 asthma-related intermediate quantitative phenotypes was performed by using FBAT.

RESULTS

One SNP, -384A>G, was associated with asthma among African American families (P = .01). CCL11 SNPs and haplotypes were not associated with asthma among white or Hispanic families. Two low-frequency alleles in strong pairwise linkage disequilibrium, -426C and IVS2+199A, were associated with lower serum total IgE levels (P = .0006 and P = .009, respectively) in white families, whereas 2 more common variants, -576C and g.4438C, were associated with higher IgE levels in African American families (P = .01-.04). Haplotype analysis in the white cohort provided additional evidence of association with serum total IgE, implicating 2 haplotypes. No single SNP or haplotype associations were observed with blood eosinophil levels, FEV(1), or airway responsiveness.

CONCLUSION

These findings provide further evidence that genetic variation at the CCL11 locus is an important determinant of serum total IgE levels among patients with asthma.

Expression of ecalectin, a novel eosinophil chemoattractant, in nasal polyps

CONCLUSION

Ecalectin, which is produced in the mucosa of nasal polyps, seems to play an important role in the accumulation and activation of eosinophils in nasal polyps, regardless of the presence or absence of atopic predisposition.

OBJECTIVE

Ecalectin is a recently discovered eosinophil chemoattractant which elongs to the galectin family. We investigated the expression of ecalectin in nasal polyp tissues associated with various nasal and paranasal diseases in order to clarify the pathogenesis of eosinophilia in nasal polyposis.

MATERIAL AND METHODS

Nasal polyps were taken from 56 patients diagnosed as having chronic sinusitis with nasal polyposis. The surgically resected polyps and nasal turbinates were immunohistochemically stained using antibodies against EG2, human mast cell tryptase, CD3 and ecalectin.

RESULTS

The number of EG2- and ecalectin-positive cells was significantly higher in nasal polyps than control turbinates. Ecalectin-positive cells were observed in the subepithelial layer, where many EG2-positive cells were present. The number of ecalectin-positive cells correlated significantly with the number of EG2-positive cells in nasal polyps. Many ecalectin mRNA-positive cells were also observed in nasal polyps with an accumulation of EG2-positive cells.

Comparison of plasma eotaxin family level in aspirin-induced and aspirin-tolerant asthma patients

STUDY OBJECTIVE

Eosinophilic infiltration of airway tissue is a central feature of aspirin-induced asthma (AIA). Eotaxins belong to the family of CC chemokines, which coordinate the recruitment of inflammatory cells bearing chemokine (C-C motif) receptor-3 to sites of allergic inflammation. In the present study, the levels of eotaxin-1, eotaxin-2, and eotaxin-3 following an oral aspirin provocation test (APT) were measured, and the relationship between the eotaxin level and clinical parameters in patients with asthma was evaluated.

PATIENTS AND DESIGN

An APT was performed in patients with asthma. Twenty AIA patients and 23 aspirin-tolerant asthma (ATA) patients were identified. Plasma levels of eotaxin-1, eotaxin-2, and eotaxin-3 levels were measured by enzyme-linked immunosorbent assay in the 43 patients with asthma and in 39 control subjects.

RESULTS

The proportion of blood eosinophils was significantly higher in asthmatic patients than in control subjects. Nasal polyps were more common in AIA patients than in ATA patients (p < 0.05). In addition, the eotaxin-1 level was higher in AIA and ATA patients than in control subjects (p < 0.01 for each). The eotaxin-2 level was higher in ATA patients than in either the AIA patients (p < 0.05) or control subjects (p < 0.01). Similarly, the eotaxin-3 level was higher in ATA patients than in control subjects. A trend toward higher plasma levels of eotaxin-1 and eotaxin-3 at baseline and at 4 h after APT administration in the ATA group was noted but was not significant. Eotaxin-2 was also higher in ATA patients than in AIA patients at baseline and at 4 h after the APT.

CONCLUSION

This study shows that eotaxin-2 is differentially secreted in patients with asthma according to aspirin intolerance, and that secretion is not time-dependent in response to the APT in AIA and ATA patients. It therefore appears that eotaxin-2 may be up-regulated and may act differentially in patients with ATA.

In vitro and in vivo characterization of a novel CCR3 antagonist, YM-344031

Eosinophils play a prominent proinflammatory role in a broad range of diseases, including atopic dermatitis and asthma. Eotaxin-1 and its receptor CCR3 are implicated in the recruitment of eosinophils from blood into inflammatory tissues, therefore inhibition of Eotaxin-1/CCR3 interaction may have therapeutic potential for allergic inflammation with eosinophil infiltration. YM-344031, a novel and selective small molecule CCR3 antagonist, potently inhibited ligand binding (IC(50)=3.0nM), ligand-induced Ca(2+) flux (IC(50)=5.4nM), and the chemotaxis of human CCR3-expressing cells (IC(50)=19.9nM). YM-344031 (1-10mg/kg) orally administered to cynomolgus monkeys significantly inhibited Eotaxin-1-induced eosinophil shape change in whole blood. Additionally, orally administered YM-344031 (100mg/kg) prevented both immediate- and late-phase allergic skin reactions in a mouse allergy model. YM-344031 therefore has potential as a novel and orally available compound for the treatment of allergic inflammation, such as atopic dermatitis and asthma.

Differences in potency of CXC chemokine ligand 8-, CC chemokine ligand 11-, and C5a-induced modulation of integrin function on human eosinophils

The hypothesis was tested that different chemoattractants have different effects on the activity of integrins expressed by the human eosinophil. Three chemoattractants, CXCL8 (IL-8), CCL11 (eotaxin-1), and C5a were tested with respect to their ability to induce migration and the transition of eosinophils from a rolling interaction to a firm arrest on activated endothelial cells under flow conditions. CCL11 and C5a induced a firm arrest of eosinophils rolling on an endothelial surface, whereas CXCL8 induced only a transient arrest of the cells. The CXCL8- and CCL11-induced arrest was inhibited by simultaneously blocking alpha4 integrins (HP2/1) and beta2 integrins (IB4). In contrast, the C5a-induced arrest was only inhibited by 30% under these conditions. The potency differences of C5a>CCL11>CXCL8 to induce firm adhesion under flow condition was also observed in migration assays and for the activation of the small GTPase Rap-1, which is an important signaling molecule in the inside-out regulation of integrins. Interestingly, only C5a was able to induce the high activation epitope of alphaMbeta2 integrin recognized by MoAb CBRM1/5. The C5a-induced appearance of this epitope and Rap activation was controlled by phospholipase C (PLC), as was shown with the PLC inhibitor U73122. These data show that different chemoattractants are able to induce distinct activation states of integrins on eosinophils and that optimal chemotaxis is associated with the high activation epitope of the alphaMbeta2 integrin. Furthermore, PLC plays an important role in the inside-out signaling and, thus, the activation status of integrins on eosinophils.

Human airway smooth muscle cells express eotaxin in response to signaling following mast cell contact

BACKGROUND

Asthma is a chronic inflammatory disease of the airways. Mast-cell (MC)-derived cytokines may mediate both airway inflammation and remodeling. It has also been shown that airway smooth muscle cells (ASMC) can be a source of proinflammatory cytokines. In the human airways, MC-ASMC cell interactions may have pivotal effects on modulating inflammation.

OBJECTIVES

We wanted to know whether the production of eotaxin, an important proinflammatory cytokine, through a cell-to-cell contact mechanism of human ASMC activation by MC was mediated by p38 MAPK.

METHODS

We cocultured normal humanASMC with a human MC line (HMC-1) and assayed for the production of eotaxin.

RESULTS

When cultured together, human ASMC and HMC-1 contact induced eotaxin secretion. Separation of HMC-1 and human ASMC by a porous membrane inhibited this induction. Coculturing of human ASMC with HMC-1 induced increased expression of eotaxin gene mRNA. HMC-1-derived cellular membranes caused an increase in eotaxin production in human ASMC. Activation of p38 MAPK was also seen in cocultures by Western blot, whereas eotaxin production in cocultures was significantly inhibited by the p38 inhibitor SB203580.

CONCLUSION

These novel studies reveal the importance of cell-to-cell interactions in the complex milieu of airway inflammation.

Mouse adenovirus type 1 infection in SCID mice: an experimental model for antiviral therapy of systemic adenovirus infections

The importance of human adenovirus infections in immunocompromised patients urges for new and adequate antiadenovirus compounds. Since human adenoviruses are species specific, animal models for systemic adenovirus infections rely on a nonhuman adenovirus. We established mouse adenovirus type 1 (MAV-1) infection of BALB/c SCID mice as a model for the evaluation of antiadenovirus therapy. In vitro studies with mouse embryonic fibroblasts pointed to the acyclic nucleoside phosphonate cidofovir and the N-7-substituted acyclic derivative 2-amino-7-(1,3-dihydroxy-2-propoxymethyl)purine (S-2242) as markedly active compounds against MAV-1. SCID mice, infected intranasally with MAV-1, developed a fatal disseminated infection after approximately 19 days, characterized by hemorrhagic enteritis. Several techniques were optimized to monitor viral, immunological, and pathological aspects of MAV-1 infection. Real-time PCR quantification of viral DNA revealed that after replication in the lungs, virus disseminated to several organs, including the brain, liver, spleen, intestine, heart, and kidneys (resulting in viruria). Immunohistochemical staining showed that MAV-1 was localized in the endothelial cells of the affected organs. Using reverse transcription-PCR, tissue levels of proinflammatory cytokines (i.e., interleukin-1beta and tumor necrosis factor alpha) were found to be markedly increased. The MAV-1/SCID model appears to be an appropriate model for in vivo evaluation of antiadenovirus agents. Treatment with cidofovir or S-2242 at a dose of 100 mg per kg of body weight resulted in a significant delay in MAV-1-related death, although these antivirals were unable to completely suppress virus replication despite continued drug treatment. These findings suggest that complete virus clearance during antiviral therapy for disseminated adenovirus infection may require an efficient adaptive immune response from the host.

Localization of human T-cell lymphotropic virus-1 gag proviral sequences in dermato-immunological disorders with eosinophilia

The mechanisms leading to the development of eosinophilia were investigated in 65 patients with immunodermatological disorders, including the role of eosinophilotactic cytokines and the possible involvement of human T-cell leukemia virus, HTLV. HTLV-1 gag proviral sequences were revealed in two cases of lymphoproliferative disorders such as angiolymphoid hyperplasia with eosinophilia (ALHE) and CD4+ cutaneous lymphoma, respectively. Increased level of GM-CSF was detected in 33% of disorders studied. Elevated level of IL-5 and eotaxin was detected in 27% and 30%, respectively, of patients with bullous diseases. Elevated level of GM-CSF and eotaxin was found in 33% and 46%, respectively, of patients with inflammatory diseases. Neither of the four cytokines, however proved to be responsible alone or together for the induction of eosinophilia. The possible indirect role of human retroviruses through induction of eosinophilic chemotactic cytokines is hypothesized.