Chemokine receptors in airway disease: which receptors to target?

Optimization of CCR4 antagonists: side-chain exploration

The design, synthesis, and activity of novel and selective small molecule antagonists of the CC chemokine receptor-4 (CCR4) are presented. Compound 8c was efficacious in a murine allergic inflammation model (ED(50) 30 mg/kg).

Identification of chemokine receptor CCR4 antagonist

The present study reports the identification and hits to leads optimization of chemokine receptor CCR4 antagonists. Compound 12 is a high affinity, non-cytotoxic antagonist of CCR4 that blocks the functional activity mediated by the receptor.

Concentration of CCL11, CXCL8 and TNF-alpha in sputum and plasma of patients undergoing asthma or chronic obstructive pulmonary disease exacerbation

Asthma and chronic obstructive pulmonary disease (COPD) are common respiratory illnesses characterized by chronic inflammation of the airways. The characterization of induced or spontaneously produced sputum is a useful technique to assess airway inflammation. In the present study, we compared the concentrations of CCL2, CCL11, CXCL8, and tumor necrosis factor-alpha (TNF-alpha) in plasma and induced sputum of patients with severe asthma or COPD and correlated the levels of these mediators with inflammatory cells in sputum. Asthmatic patients had elevated levels of eosinophils (40.1 +/- 6.24%) in sputum whereas neutrophils (63.3 +/- 4.66%) predominated in COPD patients. The levels of the chemokine CCL11 were markedly increased in sputum (708.7 +/- 330.7 pg/ml) and plasma (716.6 +/- 162.2 pg/ml) of asthmatic patients and correlated with the percentage of eosinophils in induced sputum. The concentrations of CXCL8 (817.0 +/- 105.2 pg/ml) and TNF-alpha (308.8 +/- 96.1 pg/ml) were higher in sputum of COPD patients and correlated with the percentage of neutrophils in induced sputum. There was also an increase in the concentrations of CXCL8 (43.2 +/- 6.8 pg/ml) in sputum of asthmatic patients. These results validate that sputum is a suitable method to assess chemokines and cytokines associated with asthma and COPD. Moreover, the mechanisms involved in the synthesis of CCL11 and CXCL8/TNF-alpha would be helpful to better understand the inflammatory profile associated with asthma and COPD, respectively.

Therapeutic targeting of CCR1 attenuates established chronic fungal asthma in mice

CC chemokine receptor 1 (CCR1) represents a promising target in chronic airway inflammation and remodeling due to fungus-associated allergic asthma. The present study addressed the therapeutic effect of a nonpeptide CCR1 antagonist, BX-471, in a model of chronic fungal asthma induced by Aspergillus fumigatus conidia. BX-471 treatment of isolated macrophages inhibited CCL22 and TNF-alpha and promoted IL-10 release. BX-471 also increased toll like receptor-9 (TLR9) and decreased TLR2 and TLR6 expression in these cells. When administered daily by intraperitoneal injection, from days 15 to 30 after the initiation of chronic fungal asthma, BX-471 (3, 10, or 30 mg kg(-1)) dose-dependently reduced airway inflammation, hyper-responsiveness, and remodeling at day 30 after conidia challenge. The maximal therapeutic effect was observed at the 10 mg kg(-1) dose. In summary, the therapeutic administration of BX-471 significantly attenuated experimental fungal asthma via its effects on both innate and adaptive immune processes.

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

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

Bleomycin-induced pulmonary toxicity in chemotherapy for testicular cancer

Bleomycin is an antibiotic agent with antitumour activity, discovered in 1966 by Umezawa et al. Today, bleomycin is commonly used in chemotherapy for various tumour types. In testicular cancer especially, bleomycin is one of the key drugs in induction chemotherapy. It has the advantage of less myelotoxicity; however, its severe and potentially fatal pulmonary toxicity has limited its dose intensity. Several clinical trials have focused on eliminating bleomycin from the regimen or reducing the bleomycin dose for testicular cancer patients with good prognosis. However, the results indicate that bleomycin is still an essential component of induction chemotherapy when only three courses are administered. This review will focus on bleomycin-induced pulmonary toxicity in chemotherapy for testicular cancer, followed by a brief review of recent basic understanding of the pathogenesis of lung fibrosis.

The molecular basis of lymphocyte recruitment to the skin: clues for pathogenesis and selective therapies of inflammatory disorders

Spatial compartmentalization and tissue-selective localization of T lymphocytes to the skin are crucial for immune surveillance and the pathogenesis of various disorders including common inflammatory diseases such as atopic dermatitis or psoriasis, but also malignancies such as cutaneous T cell lymphomas. Cutaneous recruitment of lymphocytes is a highly complex process that involves extravasation, migration through the dermal connective tissue, and eventually, localization to the epidermis. An intertwined network of cytokines and chemokines provides the road signs for leukocyte migration, while various adhesion receptors orchestrate the dynamic events of cell-cell and cell-substrate interactions resulting in cutaneous localization of T cells. Selectively targeting the functions of molecules involved in this interplay promises exciting new therapeutic options for treating inflammatory skin disorders.

Pharmacology of airway inflammation in asthma and COPD

The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term treatment. Although inhaled glucocorticoids are highly effective in controlling airway inflammation in asthma, they are ineffective in the small group of patients with glucocorticoid-dependent and -resistant asthma. With very few exceptions, COPD is caused by tobacco smoking, and smoking cessation is the only truly effective treatment of COPD available. Current pharmacological treatment of COPD is unsatisfactory, as it does not significantly influence the severity of the disease or its natural course. Glucocorticoids are scarcely effective in COPD patients without concomitant asthma. Bronchodilators improves symptoms and quality of life, in COPD patients, but, with the exception of tiotropium, they do not significantly influence the natural course of the disease. Theophylline is the only drug which has been demonstrated to have a significant effect on airway inflammation in patients with COPD. Here we review the pharmacology of currently used antiinflammatory therapies for asthma and COPD and their proposed mechanisms of action. Recent understanding of disease mechanisms in severe steroid-dependent and -resistant asthma and in COPD, has lead to the development of novel compounds, which are in various stages of clinical development. We review the current status of some of these new potential drugs.

Biopsy neutrophilia, neutrophil chemokine and receptor gene expression in severe exacerbations of chronic obstructive pulmonary disease

We have applied immunohistology and in situ hybridization to bronchial biopsies of patients with chronic obstructive pulmonary disease (COPD) to examine neutrophil recruitment and to determine neutrophil chemoattractant and CXC receptor (CXCR) 1 and CXCR2 gene expression associated with acute severe exacerbations. Cells were counted in endobronchial biopsies of (1) patients with COPD intubated for exacerbations (E-COPD; n = 15), (2) those with COPD in a stable phase of their disease (S-COPD; n = 7), and (3) nonsmoker surgical control subjects intubated for a nonrespiratory surgical procedure (n = 15). In comparison with the nonrespiratory surgical procedure and S-COPD groups, neutrophilia and gene expression for epithelial-derived neutrophil attractant-78 (CXCL5), interleukin-8 (CXCL8), CXCR1, and CXCR2 were each upregulated in the E-COPD group (p < 0.01); compared with the S-COPD group, by 97-, 6-, 6-, 3-, and 7-fold, respectively (p < 0.01). In E-COPD, there was a significant positive association between the number of neutrophils and CXCR2 mRNA-positive cells (r = 0.79; p < 0.01) but not between the number of neutrophils and CXCR1 mRNA-positive cells. At the time of sampling of the mucosa, there was no association between neutrophil number and either the length of intubation or viral infection. Thus, in COPD, in addition to CXCL8 and CXCR1, CXCL5 and CXCR2 appear to play important roles in the airway neutrophilia characteristic of severe exacerbations.

Chemokines in allergic airway disease

Expression of chemokine receptors on T helper 2 cells and eosinophils has been postulated to be the mechanism by which these cells are selectively recruited to the lung during allergic inflammatory reactions. Mouse models have provided evidence to show that blocking the ligands for these receptors is successful in abrogating the pathophysiological effects of allergen challenge. However, recent studies describing the effect of genetic deletions of these chemokine receptors have not confirmed the results obtained with ligand knockouts or neutralising antibodies. Coupled with the realisation that, because of a lack of species cross-reactivity, it is not possible to test small molecule antagonists against human receptors in the original in vivo animal models, the future of chemokine receptor therapeutics is in question. However, recent advances have been made regarding the therapeutic potential of blocking the chemokine receptors CCR3, CCR4 and CCR8 in allergic airway disease.

What's in the pipeline? Prospects for monoclonal antibodies (mAbs) as therapies for lung diseases

The striking clinical results from recent studies with Remicade (infliximab, a monoclonal anti-TNFalpha antibody) in rheumatoid arthritis, Crohn's disease and psoriasis demonstrate the disease-altering potential of monoclonal antibodies (mAbs) in chronic inflammation. Chronic obstructive pulmonary disease (COPD) and asthma represent two major chronic pulmonary inflammatory diseases with substantial unmet medical needs. Most of the cells and mediators implicated in the pathophysiology of COPD and asthma are excellent targets for mAb intervention. Indeed, clinical trials with mAbs directed against IL-5, IgE, and CD4 yielded results that are critical in dissecting the pathophysiology of asthma, and reinforce the potential for mAbs as therapeutic agents in treating pulmonary diseases. Furthermore, fundamental advances in the discovery, manufacture and safety of mAbs underscore the enormous therapeutic value of these agents for chronic pulmonary diseases. Indeed, a large number of mAbs are in pre-clinical and clinical development for treating these conditions. In this review, we discuss the scientific rationale for generating mAb therapies directed specifically toward COPD and asthma. We believe that as a therapeutic class, mAbs offer the opportunity to alter symptoms, progression and outcome of chronic pulmonary diseases.

1,536-Well Assay Development and Screening Using Whole Cell Displacement Binding and Laser Scanning Imaging

A screen of a GPCR against Pharmacopeia's combinatorial libraries was performed using 1,536-well plates in a 1.5-microl assay volume with an LSI that was specially modified to enable detection at these volumes. The screen encompassed approximately 4 x 10(6) compounds. The assay uses a CHO cell line that expresses human CXCR1. The plate format chosen was the Corning 1536 low-profile wafer plate. The performance of the screen is evaluated, and the necessity to obtain cytotoxicity data from the same well is described.

Novel therapies for the treatment of inflammatory airway disease

Asthma and chronic obstructive pulmonary disease (COPD) are diseases of the airways with an underlying inflammatory component. The prevalence and healthcare burden of asthma and COPD is still rising and is predicted to continue to rise in the current century. The beta-agonists and corticosteroids form the basis of the treatments available to alleviate the symptoms of asthma, whereas the treatments available for COPD have been shown to have a limited effect on slowing the progression of the disease. Asthma and COPD are both in need of novel, safe treatments to tackle the underlying inflammation that characterises their pathology. The inflammatory processes inherent in asthma and COPD provide the opportunity for innovative drug research. This review will outline the new approaches and targets being investigated, which may provide opportunities for novel therapeutic interventions in these debilitating diseases.

Phosphoinositide 3-kinase gamma is an essential amplifier of mast cell function

Mast cells are key regulators in allergy and inflammation, and release histamine upon clustering of their IgE receptors. Here we demonstrate that murine mast cell responses are exacerbated in vitro and in vivo by autocrine signals through G protein-coupled receptors (GPCRs) and require functional phosphoinositide 3-kinase gamma (PI3Kgamma). Adenosine, acting through the A(3) adenosine receptor (A(3)AR) as well as other agonists of G(alphai)-coupled GPCRs, transiently increased PtdIns(3,4,5)P(3) exclusively via PI3Kgamma. PI3Kgamma-derived PtdIns(3,4,5)P(3) was instrumental for initiating a sustained influx of external Ca(2+) and degranulation. Mice lacking PI3Kgamma did not form edema after intradermal injection of adenosine and when challenged by passive systemic anaphylaxis. PI3Kgamma thus relays inflammatory signals through various G(i)-coupled receptors and is central to mast cell function.