The eosinophil as a therapeutic target in asthma: beginning of the end,or end of the beginning?

A major goal in asthma therapy is to reduce or prevent the inflammatory response associated with bronchial hyperresponsiveness, reversible airway obstruction and airway remodelling. However, because of the complex nature of the disease, a single target for such an ideal therapeutic approach remains elusive. To ensure a more rational design of anti-asthma drugs, recent investigations have attempted to elucidate the roles of inflammatory cellular components in asthma. Such studies have shown that eosinophilic infiltration is a prominent feature in the pathophysiology of asthma. Nonetheless, the role of the eosinophil in asthma has been questioned following recent human studies investigating the efficacy of a novel therapeutic strategy targeted at eosinophils.     

Antileukotriene drugs: clinical application, effectiveness and safety

Cysteinyl leukotrienes (Cys-LTs) are potent proinflammatory mediators derived from arachidonic acid through the 5-lypoxigenase (5-LO) pathway. They exert important pharmacological effects by interaction with at least two different receptors: Cys-LT(1) and Cys-LT(2). By competitive binding to the Cys-LT(1) receptor, leukotriene receptor antagonist drugs such as montelukast, zafirlukast, and pranlukast, block the effects of Cys-LTs and alleviate the symptoms of many chronic diseases, especially bronchial asthma and allergic rhinitis. Evidence obtained by randomized clinical trials as also by direct experience derived from patients suffering from asthma and allergic rhinitis justifies a broader role for leukotrienes receptor antagonists (LTRAs). Recently published studies and case reports have demonstrated beneficial effects of LTRAs on other diseases commonly associated with asthma (exercise induced asthma, rhinitis, chronic obstructive pulmonary disease, interstitial lung disease, chronic urticaria, atopic dermatitis, allergic fungal disease, nasal polyposis, and paranasal sinus disease) as well as other diseases not connected to asthma (migraine, respiratory syncytial virus postbronchiolitis, systemic mastocytosis, cystic fibrosis, pancreatitis, vulvovaginal candidiasis, cancer, atherosclerosis, eosinophils cystitis, otitis media, capsular contracture, and eosinophilic gastrointestinal disorders). The aim of this review is to show the most recent applications and effectiveness in clinical practice of the LTRAs.     

ADAM8 in allergy

ADAM (a disintegrin and metalloprotease) family members are membrane-anchored proteins with wide ranging functions, including proteolytic cleavage of cell surface molecules, cell fusion, cell adhesion and intracellular signaling. ADAM8, also known as CD156a, is expressed mainly in cells of the immune system, such as monocytes, neutrophils, eosinophils, dendritic cells, and B cells. It can cleave a variety of substrates and is a sheddase for CD23 and L-selectin. ADAM8 has an important role in allergic inflammation. ADAM8 mRNA expression is increased with disease progression in asthma. ADAM8 is strongly induced by allergens and Th2 cytokines in the lung in experimental asthma. Soluble ADAM8 is elevated in the bronchoalveolar lavage fluid of patients with eosinophilic pneumonia and has a physiologic role in protecting against allergic pulmonary disease in experimental murine asthma. Together, these findings support the view that ADAM8 might be a therapeutic target for allergic respiratory diseases. This review discusses novel strategies for immune intervention in allergic respiratory disease.     

Endothelium-platelet interactions in inflammatory lung disease

In addition to their established role in hemostasis, recent studies have identified platelets as key regulators of inflammatory reactions. Upon activation, platelets interact with both endothelial cells and circulating leukocytes. By receptor-mediated activation of interacting cell types and by release of mitogenic, pro-inflammatory and -coagulatory mediators, platelets contribute crucially to the initiation and propagation of pathological conditions and processes such as inflammatory bowel disease or atherosclerosis. In inflammatory lung disease, platelets play a critical role in the recruitment of neutrophils, eosinophils and lymphocytes as shown in experimental models of acute lung injury and allergic airway inflammation. Circulating platelet–leukocyte aggregates have been detected in patients with allergic asthma and cystic fibrosis, and in experimental lung injury. Here, we discuss the molecular mechanisms regulating the interaction of platelets with leukocytes, endothelial cells, and the subendothelial matrix with special regard to platelet kinetics in pulmonary microvessels and the putative role of platelets in inflammatory lung disorders. In light of the existing data from experimental and clinical studies it is conceivable that platelet adhesion molecules and platelet mediators provide promising targets for novel therapeutic strategies in inflammatory lung diseases.     

Endothelium–platelet interactions in inflammatory lung disease

In addition to their established role in hemostasis, recent studies have identified platelets as key regulators of inflammatory reactions. Upon activation, platelets interact with both endothelial cells and circulating leukocytes. By receptor-mediated activation of interacting cell types and by release of mitogenic, pro-inflammatory and -coagulatory mediators, platelets contribute crucially to the initiation and propagation of pathological conditions and processes such as inflammatory bowel disease or atherosclerosis. In inflammatory lung disease, platelets play a critical role in the recruitment of neutrophils, eosinophils and lymphocytes as shown in experimental models of acute lung injury and allergic airway inflammation. Circulating platelet–leukocyte aggregates have been detected in patients with allergic asthma and cystic fibrosis, and in experimental lung injury. Here, we discuss the molecular mechanisms regulating the interaction of platelets with leukocytes, endothelial cells, and the subendothelial matrix with special regard to platelet kinetics in pulmonary microvessels and the putative role of platelets in inflammatory lung disorders. In light of the existing data from experimental and clinical studies it is conceivable that platelet adhesion molecules and platelet mediators provide promising targets for novel therapeutic strategies in inflammatory lung diseases.     

Role of eosinophils in allergic inflammation

Eosinophils are one of the cells that play a critical role in the pathogenesis of allergic diseases. The increase in the number of eosinophils in such diseases is regulated by interleukin-5 (IL-5). The author have prepared recombinant rat IL-5 using a baculovirus expression system and examined its biological activities in rat eosinophils. It was demonstrated that recombinant rat IL-5 prolongs the survival of mature eosinophils and differentiates immature eosinophils into mature eosinophils, suggesting that rat IL-5 is a factor for eosinophilia in rats. Recombinant rat eosinophil-associated ribonuclease (Ear)-1 and Ear-2 were also prepared. Eosinophil granule proteins are thought to cause tissue damage due to their cytotoxic activity, but using recombinant rat Ear-1 and Ear-2, it was found that rat Ear-1 and Ear-2 have strong RNase A activity and bactericidal activity, suggesting that these proteins play critical roles in host defense. Finally, the important role of acetylation of histones was clarified in the differentiation of HL-60 clone 15 cells into eosinophils using the histone deacetylase inhibitors sodium n-butyrate, apicidin, and trichostatin A. These findings would be useful for further investigations of the role of eosinophils in allergic inflammation.     

Pharmacological treatment of eosinophilic gastrointestinal disorders

Introduction: Eosinophilic gastrointestinal disorders (EGIDs) are increasingly prevalent chronic inflammatory diseases characterized by eosinophilic infiltration of the gastrointestinal (GI) tract, in the absence of other known causes of eosinophilia.

Areas covered: Clinical management of EGIDs is challenging, as there are currently limited therapeutic options available. The most common EGID is eosinophilic esophagitis (EoE), and rarer forms are eosinophilic gastritis, eosinophilic gastroenteritis, and eosinophilic colitis. Clinical presentation depends on the affected GI site. Recently duodenal eosinophilia has been recognized to commonly be present in patients with functional dyspepsia. This review will provide an overview of the pathogenesis and therapeutic management of EGIDs, with particular focus on the pharmacological strategies for these conditions.

Expert commentary: Despite the considerable progress made in understanding the pathogenesis of EGIDs, there is still an urgent need for the development of specific and effective therapeutic approaches. Therapeutic management protocols are required that are based on rigorous clinical investigation in large prospective controlled trials to better understand the risks, benefits and limitations of each therapy. More well-defined and consistent end-points are also required to assess treatment outcomes, as there has been variability between patient reported outcomes, clinical outcomes, and histological outcomes in the studies to date.     

Chemokine CCR3 antagonists

Because CC chemokine receptor 3 (CCR3) expression is confined to eosinophils, and such leukocytes play an important role in allergic disorders, identification of CCR3 antagonists represents a logical approach to identifying new treatments for eosinophil-associated inflammatory disorders such as asthma. CCR3 is also expressed on basophils, mast cells, airway epithelial cells and a subpopulation of T-helper 2 lymphocytes, which has increased interest in its possible role in allergy. Substantial research efforts by a number of drug companies have been directed at the development of small molecule CCR3 antagonists. This review encompasses patent applications pertaining to disclosures of CCR3 antagonists.     

Eotaxins and CCR3 receptor in inflammatory and allergic skin diseases: therapeutical implications

Cell migration is mediated by a group of chemotactic cytokines called chemokines: low molecular weight molecules that have been shown as important leukocyte chemical attractants to sites of inflammation and infection. Eotaxin-1, also called CCL11, was first described in 1994, as a highly specific eosinophils chemokine. Many cell types including lymphocytes, macrophages, bronchial smooth muscle cells, endothelial cells and eosinophils, are able to produce this chemokine, predominantly after cytokine stimulation, however little is known about its expression in human skin in vivo. Eotaxin-1 also regulates the chemiotaxis and, in some conditions, activation of basophils, mast cells and T lymphocytes. Chemokine receptors are named from their ligand families, thus the CC chemokine eotaxin-1 binds to the CCR3 receptor which is expressed on eosinophis, mast cells, Th2 type lymphocytes and even on keratinocytes. It seems that eotaxin-1 is one of the most important cytokines involved in tissue inflammation playing a central role in the pathogenesis of allergic airway diseases (asthma and rhinitis), in inflammatory bowel disease and gastrointestinal allergic hypersensitivity and recently it has been proposed as a therapeutical target for these conditions. Our group has studied the role of eotaxin-1 in the pathogenesis of two skin conditions: dermatitis herpetiformis and AIDS-associated eosinophilic folliculitis, demonstrating that this chemokine, together with Th2 type cytokines (IL-13 and IL-4) is important in cell recruitment, inflammation and tissue damage; moreover eotaxin has proven to paly an important role in other skin conditions such as, bullous pemphigoid, pemphigoid gestationis, atopic dermatitis and allergic drug reactions Recent advances in the understanding of eotaxin-1-mediated mechanisms of chemotaxis in allergic and inflammatory conditions may predict that therapeutic antagonism is achievable. This paper will focus on the role that eotaxin and its receptor play in the pathogenetical mechanism in a number of dermatologic diseases, some of which, like atopic dermatitis, may benefit from the introduction of novel and more selective therapeutic options.     

Pregnane X receptor as a target for treatment of inflammatory bowel disorders

Pregnane X receptor (PXR; NR1I2), a member of the nuclear receptor superfamily, has a major role in the induction of genes involved in drug transport and metabolism. Recent studies in mice have provided insight into a novel function for PXR in inflammatory bowel disease (IBD). The mechanism of the protective effect of PXR activation on IBD is not fully established, but is due in part to the attenuation of nuclear factor (NF)-κB signaling that results in lower expression of proinflammatory cytokines. Recent clinical trials with the antibiotic rifaximin, a PXR agonist in the gastrointestinal system, have revealed its potential therapeutic value in the treatment of intestinal inflammation in humans. Thus, PXR may be a novel target for IBD therapy.     

Structure-based rationale for interleukin 5 receptor antagonism

Human interleukin 5 (IL5) is the major hematopoietin that stimulates the proliferation, migration and activation of eosinophils and is implicated in the pathogenesis of inflammatory and other myeloproliferative diseases. IL5 functions through the signaling of a common receptor subunit beta (beta c), in a receptor activation process that requires initial recruitment of an IL5 specific receptor subunit alpha (IL5Ralpha), for cytokine presentation to beta c. Important advances have been made to understand molecular mechanisms of cytokine recognition and receptor antagonism. Mutational studies indicate that a pair of charge complementary regions play an essential role in specific interaction between IL5Ralpha and IL5. Moreover, peptide studies with the IL5 system have identified a cyclic peptide inhibitor, AF17121, which binds specifically to IL5Ralpha by mimicking the cytokine. A key receptor-recognition pharmacophore has been identified in this peptide inhibitor, and sites of inhibitor recognition can be proposed in the homology-deduced structural model of IL5Ralpha. These results provide an experimental platform to derive enhanced-potency peptidomimetic inhibitors. Such inhibitors have potential use as tools to evaluate the role of eosinophilia in disease and as potential leads to antagonists to treat hyper-eosinophilic diseases such as eosinophilic esophagitis, asthma and chronic myeloproliferative leukemias.     

儿童嗜酸粒细胞性膀胱炎1例报告并文献复习

目的:探讨儿童嗜酸粒细胞性膀胱炎临床特征及诊治要点。方法:回顾分析1 例嗜酸粒细胞性膀胱炎患儿的临床资料,并进行诊断性治疗,随访患儿病情转归情况。并复习嗜酸粒细胞性膀胱炎相关文献。结果:患儿,女,7 岁,临床表现为尿频、尿急、尿痛及夜尿增多,血常规提示嗜酸粒细胞明显升高,给予糖皮质激素及抗过敏治疗后,患儿临床症状缓解,复查血常规提示嗜酸粒细胞降低。结论:对于临床以尿路刺激症状为主要表现结合嗜酸粒细胞升高患儿需警惕儿童嗜酸粒细胞性膀胱炎。     

Mepolizumab: 240563, anti-IL-5 monoclonal antibody - GlaxoSmithKline, anti-interleukin-5 monoclonal antibody - GlaxoSmithKline, SB 240563

Mepolizumab is an anti-interleukin-5 monoclonal antibody that is in clinical trials with GlaxoSmithKline (GSK) for the treatment of severe asthma, nasal polyposis and hypereosinophilic syndrome and eosinophilic oesophagitis (the latter two indications are classed as eosinophilia in the phase table). Interleukin-5 stimulates the production, activation and maturation of eosinophils. Since mepolizumab inhibits interleukin-5 and has a long terminal half-life, treatment with mepolizumab causes a sustained reduction in the numbers of circulating eosinophils. Thus, mepolizumab may be a useful therapeutic agent for the treatment of conditions characterized by increased levels of eosinophils. Hypereosinophilic syndrome is a rare idiopathic disease with broad clinical signs and symptoms that is diagnosed based on a persistent blood eosinophil count of >1500 cells, various end-organ damages (including skin, heart, lung, nervous system and digestive system), and with exclusion of known secondary causes of hypereosinophilia. Mepolizumab is in clinical trials for the treatment of hypereosinophilic syndrome, eosinophilc oesophagitis, severe asthma (in patients with airway eosinophilia) and nasal polyposis. GlaxoSmithKline (GSK) has completed enrolment in a phase II study of mepolizumab in 20 patients with symptomatic eosinophilic bronchitis with or without asthma in Canada. The randomized, double-blind, placebo-controlled study is evaluating the effects of intravenous mepolizumab on asthma control, airway eosinophilia and the degree to which concomitant corticosteroid treatment can be reduced (NCT00292877). In previous clinical studies, including trials in the EU and US, mepolizumab has shown a lack of effect on allergen-induced airway responses and inflammation despite a significant reduction in blood and sputum eosinophil levels.A randomized, double-blind, placebo-controlled, multicentre, phase III study of mepolizumab over 9 months in 85 patients with hypereosinophilic syndrome was completed in 2006. All patients have been offered, and continued in, a phase III, open-label, long-term extension study of mepolizumab. Enrolment in this study was completed in September 2006.A phase III, compassionate use trial of mepalizumab (NCT00244686) in patients with hypereosinophilic syndrome was ongoing in October 2007 in the US. Patients who have significant clinical disease but are unresponsive to traditional treatment and those who have demonstrated clinical benefit from previous anti-IL-5 treatment are eligible to take part in the trial. Mepolizumab received orphan drug status for first-line treatment in patients with hypereosinophilic syndrome in the US and the EU in 2004. Mepolizumab is also in phase I/II clinical development for the treatment of eosinophilic oesophagitis. A phase I/II trial (NCT00358449) began in August 2006 in the US, Australia, the UK and Canada, and will enrol approximately 72 paediatric patients with eosinophilic oesophagitis. The randomized, parallel-group clinical trial will evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of intravenous mepolizumab for 12 weeks. In September 2006, GSK completed enrolment in a phase I/II study of mepolizumab for the treatment of eosinophilic oesophagitis in ten adult patients in Switzerland (NCT00274703). The randomized, double-blind, placebo-controlled study will evaluate the pharmacokinetics, pharmacodynamics, safety and tolerability of IV mepolizumab.A phase I/II trial of mepolizumab in four patients with eosinophilic oesophagitis conducted by Cincinnati Children's hospital found the monoclonal antibody was safe and effective. Brigham and Women's Hospital in association with GSK is conducting a phase I/II trial of mepolizumab in patients with Churg-Strauss Syndrome (CSS) in the US. The trial, which started in September 2007, will evaluate the potential of mepolizumab to reduce the need for corticosteroid therapy in patients with CSS (NCT00527566). CSS, otherwise known as allergic granulomatosis, is defined by patients with asthma, eosinophilia and vasculitis.     

Targeting AMCase reduces esophageal eosinophilic inflammation and remodeling in a mouse model of egg induced eosinophilic esophagitis

Studies of AMCase inhibition in mouse models of lung eosinophilic inflammation have produced conflicting results with some studies demonstrating inhibition of eosinophilic inflammation and others not. No studies have investigated the role of AMCase inhibition in eosinophilic esophagitis (EoE). We have used a mouse model of egg (OVA) induced EoE to determine whether pharmacologic inhibition of AMCase with allosamidin reduced eosinophilic inflammation and remodeling in the esophagus in EoE. Administration of intra-esophageal OVA for 6 weeks to BALB/c mice induced increased levels of esophageal eosinophils, mast cells, and features of esophageal remodeling (fibrosis, basal zone hyperplasia, deposition of the extracellular matrix protein fibronectin). Administration of intraperitoneal (ip) allosamidin to BALB/c mice significantly inhibited AMCase enzymatic activity in the esophagus. Pharmacologic inhibition of AMCase with ip allosamidin inhibited both OVA induced increases in esophageal eosinophilic inflammation and OVA induced esophageal remodeling (fibrosis, epithelial basal zone hyperplasia, extracellular matrix deposition of fibronectin). This inhibition of eosinophilic inflammation in the esophagus by ip allosamidin was associated with reduced eotaxin-1 expression in the esophagus. Oral allosamidin inhibited eosinophilic inflammation in the epithelium but did not inhibit esophageal remodeling. These studies suggest that pharmacologic inhibition of AMCase results in inhibition of eosinophilic inflammation and remodeling in the esophagus in a mouse model of egg induced EoE partially through effects in the esophagus on reducing chemokines (i.e. eotaxin-1) implicated in the pathogenesis of EoE.     

Gastrointestinal endocannabinoid system: multifaceted roles in the healthy and inflamed intestine

1. The endogenous cannabinoid (endocannabinoid) system is emerging as a key modulator of intestinal physiology, influencing motility, secretion, epithelial integrity and immune function in the gut, in addition to influencing satiety and emesis. 2. Accumulating evidence suggests that the endocannabinoid system may play a pivotal role in the pathophysiology of gastrointestinal disease, particularly in the light of recent studies demonstrating an effect of endocannabinoids on the development of experimental inflammation and linkages with functional clinical disorders characterized by altered motility. 3. The predominant endocannabinoids, anandamide and 2-arachidonoylglycerol, not only mediate their effects via two recognized cannabinoid receptor subtypes, namely CB(1) and CB(2), but emerging evidence now shows they are also substrates for cyclo-oxygenase (COX)-2, generating a distinct and novel class of prostaglandin ethanolamides (prostamides) and prostaglandin glycerol esters. These compounds are bioactive and may mediate an array of biological effects distinct to those of conventional prostanoids. 4. The effects of prostamides on gastrointestinal motility, secretion, sensation and immune function have not been characterized extensively. Prostamides may play an important role in gastrointestinal inflammation, particularly given the enhanced expression of both COX-2 and endocannabinoids that occurs in the inflamed gut. 5. Further preclinical studies are needed to determine the therapeutic potential of drugs targeting the endocannabinoid system in functional and inflammatory gut disorders, to assist with the determination of feasibility for clinical translation.     

Induced sputum in asthma: from bench to bedside

During recent years there has been a growing interest in using non-invasive biomarkers to understand and monitor the airway inflammation in subjects with respiratory tract disorders and mainly asthma and chronic obstructive pulmonary disease (COPD). Sputum induction is generally a well-tolerated and safe procedure and a European Respiratory Society Task Force has published a comprehensive review on sputum methodology. Induced sputum cell count and, to a lesser extent, mediator measurements have been particularly well validated. In asthma, the sputum and the cell culture supernatant can be used for the measurement of a variety of soluble mediators, including eosinophil-derived proteins, nitric oxide (NO) derivatives, cytokines and remodelling-associated proteins. Sputum eosinophilia (> 3%) is a classic feature of asthma although half of the patients seems to be non eosinophilic. Measuring the percentage of sputum eosinophils has proved to be useful in the clinical arena in helping to predict short term response to inhaled corticosteroids (ICS) and tailor the dose of ICS in the severe patients but there is scope for the application of other induced sputum markers potentially useful in clinical practice. The widespread application of induced sputum in asthma across the spectrum of disease severity has given insight into the relationship between airway function and airway inflammation, proposed new disease phenotypes and defined which of these phenotypes respond to current therapy, and perhaps most importantly provided an additional tool to guide the clinical management of asthmatic patients. To date sputum induction is the only non-invasive measure of airway inflammation that has a clearly proven role in asthma management.     

The pharyngeal mucosa is not involved in eosinophilic oesophagitis

Background  Eosinophilic oesophagitis is thought to be an isolated oesophageal disease associated with biopsy-verified eosinophilia of the squamous cell epithelium of the oesophagus. Food- or aeroallergens have been suggested to be the cause of eosinophilic oesophagitis; however, as these allergens pass through the pharynx sharing the same squamous cell epithelium, eosinophilic infiltration could be expected also here. Whether this is true or not has hitherto not been clarified.
Aim  To find out whether eosinophilia is present also within the pharyngeal epithelium in patients with eosinophilic oesophagitis.
Methods  In all, 10 patients (median age 34, range 15–70) with biopsy-verified eosinophilic oesophagitis [peak count >20 eosinophils per high power field (hpf)] were biopsied also in the pharynx. The biopsies underwent histopathological examination and at each level, the peak number of eosinophils per hpf was counted.
Results  None of the patients examined was found to have eosinophilia within the squamous cell epithelium of the pharynx (median peak count 0, range 0–1).
Conclusions  The pronounced eosinophilic infiltration in eosinophilic oesophagitis appears to be an isolated oesophageal phenomenon not shared by the adjoining organ sites and in particular, not by the pharynx. This may have implications for future research.     

Review article: oesophageal dilation in adults with eosinophilic oesophagitis

Aliment Pharmacol Ther 2011; 33: 748–757

Summary

Background Eosinophilic oesophagitis is a chronic inflammatory disorder of the oesophagus, characterised by the proton pump inhibitor‐refractory accumulation of eosinophils in the oesophageal epithelium (>15 intraepithelial eosinophils/high powered field). Adults present with solid food dysphagia and recurrent food impactions. Oesophageal remodelling produces the characteristic endoscopic feature of adult eosinophilic oesophagitis including strictures, rings and a narrow calibre oesophagus. Aim To evaluate the safety and efficacy of oesophageal dilation as the initial therapy for adults with eosinophilic oesophagitis. Methods Medline search from 1975 to November 2010 for all reports of the treatment of patients with eosinophilic oesophagitis using search words: eosinophilic oesophagitis treatment, dilation and eosinophilic oesophagitis, steroids and eosinophilic oesophagitis. Results Our systematic review found that 92% of patients treated with oesophageal dilation had improvement in their dysphagia symptoms for up to 1–2 years. Three case series clearly showed clinical resolution of dysphagia symptoms, independent of the degree of eosinophil infiltration, which was unchanged after dilation. Postprocedure pain for several days is common, due to some degree of mucosal tear, but true perforation very rare (<0.1%). Conclusions Oesophageal dilation is an acceptable option for healthy adult eosinophilic oesophagitis patients with anatomic narrowing, possibly followed by a course of topical steroids to reduce inflammation and retard remodelling. Future studies should include a head‐to‐head comparison of topical steroids and oesophageal dilation, bougie vs through‐the‐scope balloon dilation and maintenance topical steroids compared with on‐demand treatment.     

Recent advances in neurokinin-3 receptor antagonists

This review addresses the recent highlights and progress made in the neurokinin-3 (NK-3) receptor area since the last update, provided in this journal in 1997. Whereas in the neurokinin-1 (NK-1) and neurokinin-2 (NK-2) biological areas literature information based on clinical data account for a high therapeutic potential (in emesis and depression for NK-1 and asthma for NK-2 receptor antagonists), there is a total deficiency of information from NK-3 receptor antagonists in clinical development. No other chemical classes in addition to dichlorophenylalkylpiperidines, represented by SR 142,801 and quinolines, represented by SB-222200 and SB-223412, have been identified by pharmaceutical companies and scientists involved in the specific field. Biological evidence indicates pain/inflammation as a suitable CNS-related therapeutic target, this conclusion is based on localisation studies and efficacy of selected NK-3 receptor antagonists in rat disease models of inflammatory pain. In the periphery, the most likely therapeutic indications might be pulmonary and gastrointestinal tract diseases. It is clearly still premature to anticipate any therapeutic potential in man.     

2B4 (CD244) is involved in eosinophil adhesion and chemotaxis, and its surface expression is increased in allergic rhinitis after challenge

A role for the subtypes of CD2 Ig superfamily receptors has been recently demonstrated in eosinophilic inflammation in experimental asthma and atopic asthmatics. We investigated the functions of 2B4 (CD244) molecules in eosinophil adhesion and chemotaxis, and correlated the results to the pathophysiology of allergic rhinitis (AR). Herein, we show that agonistic stimulation of 2B4 by C1.7, the anti-human 2B4 functional grade purified antibody, resulted in significant increase of eosinophils and eosinophil cell line (Eol-1 cells) adhesion to collagen type IV, and random migration. These functions were associated with tyrosine kinase phosphorylation of several protein residues of low molecular weight. Flow cytometry (FACS) experiments demonstrated that Eol-1 cells, normal peripheral blood eosinophils and eosinophils from AR patients, express surface 2B4 molecules. In vitro AR model demonstrated that the CC-chemokine receptor CCR3 stimulation by eotaxin induced significant increase in the expression of surface 2B4 in eosinophils and Eol-1 cells. Immunofluorescence confocal microscopy images showed that eotaxin induces also redistribution of 2B4 molecules towards the pseudopods in eosinophils and Eol-1 cells, changing their shape. Blocking of 2B4 molecules by the corresponding neutralizing antibody inhibited eotaxin induced Eol-1-adhesion, chemotaxis and the cytoskeleton changes. Pretreatment of Eol-1 cells with 1 microM genistein blocked eotaxin-induced Eol-1 adhesion, chemotaxis and 2B4 up-regulated expression. In vivo correlation demonstrated the expression of 2B4 molecules in eosinophils from AR patients to be significantly increased, after nasal provocation challenge. These results identify a novel role for 2B4 molecules in eosinophil functional migratory response and may point to a novel tyrosine kinase-mediated ligation between CCR3 receptor and 2B4 co-receptor in eosinophil chemotaxis. If so, then 2B4 molecules would be a novel target for therapeutic modalities in diseases characterized by eosinophilia such as AR.