Therapeutic Approach For Asthma Research Articles

Reduced allergic lung inflammation and airway responsiveness in mice lacking the cytoskeletal protein gelsolin.

Airway smooth muscle hyperresponsiveness associated with chronic airway inflammation leads to the typical symptoms of asthma including bronchoconstriction and wheezing. Asthma severity is associated with airway inflammation; therefore, reducing airway inflammation is an important therapeutic target. Gelsolin is an actin capping and severing protein that has been reported to be involved in modulation of the inflammatory response. Using mice genetically lacking gelsolin, we evaluated the role of gelsolin in the establishment of house dust mite (HDM) antigen-induced allergic lung inflammation. The genetic absence of gelsolin was found to be protective against HDM sensitization, resulting in reduced lung inflammation, inflammatory cytokines, and Muc5AC protein in bronchoalveolar lavage (BAL) fluid. The number of eosinophils, lymphocytes, and interstitial macrophages in the BAL were increased after HDM sensitization in wild-type mice but were attenuated in gelsolin-null mice. The observed attenuation of inflammation may be partly due to delayed migration of immune cells, because the reduced eosinophils in the BALs from gelsolin-null mice compared with controls occurred despite similar amounts of the chemoattractant eotaxin. Splenic T cells demonstrated similar proliferation rates, but ex vivo alveolar macrophage migration was delayed in gelsolin-null mice. In vivo, the reduced lung inflammation after HDM sensitization in gelsolin-null mice was associated with significantly diminished airway resistance to inhaled methacholine compared with HDM-treated wild-type mice. Our results suggest that modulation of gelsolin expression or function in selective inflammatory cell types that modulate allergic lung inflammation could be a therapeutic approach for asthma.

Targeting Caspase-4 and pyroptosis as a new therapeutic approach for asthma

Targeting Caspase-4 and pyroptosis as a new therapeutic approach for asthma

Ectopic olfactory receptors in the respiratory system

New findings and concepts on a role of so-called “ectopic” chemosensory receptors arise recently. The ectopic receptors are expressed outside their classical localization (nasal cavity) and referred to as extra-nasal olfactory receptors. Functional investigations of the ectopic olfactory receptors in the lungs are also ongoing. To date, it is well-known that molecules of odorous substances (odorants) bind to the G-protein-associated olfactory receptor (Gαolf) that can activate type III adenylate cyclase and increase concentration of a secondary messenger, cyclic adenosine monophosphate (cAMP). In turn, this induces the opening of cAMP-dependent cationic channels including calcium channels. Olfactory receptor activation in neuroendocrine cells of the lungs affected serotonin release which decreased after the stimulation of those cells by an odorant. Amyl butyrate and burgenal, agonists of OR2AG1 and OR1D2 olfactory receptors, respectively, affect smooth muscle contractibility in human bronchi. Amyl butyrate inhibits histamine-induces muscle contractibility, whereas burgenal increases the smooth muscle contractibility. Both the processes are mediated by cAMP-dependent increase in the intracellular calcium concentration. Data have been published about the receptor expression on immune cells such as monocytes, natural killers, T- and B-lymphocites, and polymorphonuclears. Ectopic olfactory receptors are thought to participate in modulation (controlling) of intrinsic cell functions which provide a special role of inflammatory cells in asthma. In future, the olfactory receptor modulation could be probably used as a novel therapeutic approach in asthma and other chronic inflammatory lung diseases.

Reduction in polyamine catabolism leads to spermine-mediated airway epithelial injury and induces asthma features.

Airway epithelial injury is a crucial component of acute and severe asthma pathogenesis and a promising target for treatment of refractory asthma. However, the underlying mechanism of epithelial injury remains poorly explored. Although high levels of polyamines, mainly spermine, have been found in asthma and comorbidity, their role in airway epithelial injury and the cause of their altered levels in asthma have not been explored. We measured key polyamine metabolic enzymes in lung samples from normal and asthmatic subjects and in mice with OVA-induced allergic airway inflammation (AAI). Polyamine metabolism was modulated using pharmacologic/genetic modulators. Epithelial stress and apoptosis were measured by TSLP levels and TUNEL assay, respectively. We found loss of the polyamine catabolic enzymes spermidine/spermine-N (1)-acetyltransferase-1 (SAT1) and spermine oxidase (SMOX) predominantly in bronchial epithelial cells (BECs) of human asthmatic lung samples and mice with AAI. In naïve mice, SAT1 or SMOX knockdown led to airway hyper-responsiveness, remodeling, and BEC apoptosis. Conversely, in mice with AAI, overexpression of either SAT1 or SMOX alleviated asthmatic features and reduced TSLP levels and BEC apoptosis. Similarly, while pharmacological induction of SAT1 and SMOX using the polyamine analogue bis(ethyl)norspermine (BENSPM) alleviated asthmatic features with reduced TSLP levels and BEC apoptosis, pharmacological inhibition of these enzymes using BERENIL or MDL72527, respectively, worsened them. Spermine accumulation in lungs correlated with BEC apoptosis, and spermine treatment caused apoptosis of human BEAS-2B cells invitro. Spermine induces BEC injury. Induction of polyamine catabolism may represent a novel therapeutic approach for asthma via reversing BEC stress.

Troglitazone, a PPAR-γ agonist, decreases LTC4 concentration in mononuclear cells in patients with asthma.

Asthma is an inflammatory disorder with multiple mediators involved in the inflammatory response. Despite several attempts, no new anti-inflammatory drugs have been registered for asthma treatment for several years. However, thiazolidinediones, peroxisome proliferator-activated receptor agonists, have demonstrated some anti-inflammatory properties in various experimental settings. The aim of this study was to assess the influence of troglitazone on LTC4 and 15-HETE concentrations. It also evaluates TNF-induced eotaxin synthesis in peripheral blood mononuclear cells from 14 patients with mild asthma and 13 healthy controls. PBMCs were isolated from the whole blood of the asthmatics and healthy subjects and pretreated with 0.1, 1 or 10μM of Troglitazone. The cells were then exposed to 10-6M calcium jonophore or 10ng/ml TNF. The production and release of LTC4, 15-HETE and eotaxin were then assessed. Troglitazone caused a dose-dependent inhibition in LTC4 synthesis in both asthmatics and healthy subjects. Troglitazone did not influence 15-HETE or eotaxin production in either asthmatic patients or in healthy individuals. Due to its inhibition of LTC4 synthesis, troglitazone therapy is an interesting potential therapeutic approach in asthma and other LTC4 related inflammatory disorders.

Spleen tyrosine kinase inhibition blocks airway constriction and protects from Th2-induced airway inflammation and remodeling.

Spleen tyrosine kinase (Syk) is an intracellular nonreceptor tyrosine kinase, which has been implicated as central immune modulator promoting allergic airway inflammation. Syk inhibition has been proposed as a new therapeutic approach in asthma. However, the direct effects of Syk inhibition on airway constriction independent of allergen sensitization remain elusive. Spectral confocal microscopy of human and murine lung tissue was performed to localize Syk expression. The effects of prophylactic or therapeutic Syk inhibition on allergic airway inflammation, hyperresponsiveness, and airway remodeling were analyzed in allergen-sensitized and airway-challenged mice. The effects of Syk inhibitors BAY 61-3606 or BI 1002494 on airway function were investigated in isolated lungs of wild-type, PKCα-deficient, mast cell-deficient, or eNOS-deficient mice. Spleen tyrosine kinase expression was found in human and murine airway smooth muscle cells. Syk inhibition reduced allergic airway inflammation, airway hyperresponsiveness, and pulmonary collagen deposition. In naïve mice, Syk inhibition diminished airway responsiveness independently of mast cells, or PKCα or eNOS expression and rapidly reversed established bronchoconstriction independently of NO. Simultaneous inhibition of Syk and PKC revealed additive dilatory effects, whereas combined inhibition of Syk and rho kinase or Syk and p38 MAPK did not cause additive bronchodilation. Spleen tyrosine kinase inhibition directly attenuates airway smooth muscle cell contraction independent of its protective immunomodulatory effects on allergic airway inflammation, hyperresponsiveness, and airway remodeling. Syk mediates bronchoconstriction in a NO-independent manner, presumably via rho kinase and p38 MAPK, and Syk inhibition might present a promising therapeutic approach in chronic asthma as well as acute asthma attacks.

Increased expression of thymic stromal lymphopoietin in induced sputum from asthmatic children

ObjectiveThymic stromal lymphopoietin (TSLP) plays a role in amplifying the inflammatory response in asthmatics. TSLP is also a critical factor in airway remodeling airways. The aim of this study was to assess the expression of TSLP in induced sputum from asthmatic children and to look to the impact of TNF-α and IL-37 on TSLP production in induced sputum from asthmatic children. MethodsForty children with well-controlled asthma (20 moderate and 20 mild asthmatics) were studied. TSLP was measured by enzyme-linked immunosorbent assay (ELISA) in induced sputum (IS) samples, and compared with 22 age- and sex-matched healthy controls. Real-time quantitative PCR was used to determine TSLP mRNA expression in induced sputum cells. Sputum cells (ISCs) from 5 moderate asthmatics and 5 healthy controls (HC) were stimulated either with TNF-α or TNF-α plus recombinant IL-37 (rIL-37) comparing the suppression on TSLP production. ResultsThe expression of TSLP mRNA in asthmatic patients was significantly higher than that observed in healthy controls [P=0.0001]. Induced sputum fluid TSLP and TNF-α levels were significantly higher in asthmatic patients compared to healthy controls and their levels depend on asthma severity. Sputum cells produced high TSLP levels upon stimulation with TNF-α (10pg/ml) in asthmatics. TSLP is merely produced by bronchial epithelial cells. Addition of recombinant IL-37 suppressed partially TSLP production in sputum-cultured cells and in bronchial epithelial cultured cells. ConclusionsThe increase in TSLP and TNF-α level observed in IS fluid was found to correlate with disease severity. The increased TSLP production from asthma sputum cells was abrogated by the addition of rIL-37. Regulation of TSLP pathway may be a therapeutic approach for asthma.

Targeting insulin-like growth factor-I and insulin-like growth factor-binding protein-3 signaling pathways. A novel therapeutic approach for asthma.

Insulin-like growth factor (IGF)-I has been recognized to play critical roles in the pathogenesis of asthma, whereas IGF-binding protein (IGFBP)-3 blocks crucial physiologic manifestations of asthma. IGF-I enhances subepithelial fibrosis, airway inflammation, airway hyperresponsiveness, and airway smooth muscle hyperplasia by interacting with various inflammatory mediators and complex signaling pathways, such as intercellular adhesion molecule-1, and the hypoxia-inducible factor/vascular endothelial growth factor axis. On the other hand, IGFBP-3 decreases airway inflammation and airway hyperresponsiveness through IGFBP-3 receptor-mediated activation of caspases, which subsequently inhibits NF-κB signaling pathway. It also inhibits the IGF-I/hypoxia-inducible factor/vascular endothelial growth factor axis via IGF-I-dependent and/or IGF-I-independent mechanisms. This Translational Review summarizes the role of IGF-I and IGFBP-3 in the context of allergic airway disease, and discusses the therapeutic potential of various strategies targeting the IGF-I and IGFBP-3 signaling pathways for the management of asthma.

Alleviation of Lung Inflammatory Responses by Adeno-Associated Virus 2/9 Vector Carrying CC10 in OVA-Sensitized Mice

Asthma is a chronic airway inflammatory disease characterized by eosinophilic infiltration and airway hyperresponsiveness. The over-activated Th2 and lung epithelium cells express many different cytokines, and chemokines mainly contribute to the severity of lung inflammation. Clara cell 10 kD protein (CC10) is highly expressed in airway epithelium cells and exhibits anti-inflammatory and immunomodulatory effects. Adeno-associated virus (AAV) 2/9 vector, composed of AAV2 rep and AAV9 cap genes, can efficiently and specifically target lung epithelium cells. Thus, AAV2/9 vector might carry therapeutic potential gene sequences for the treatment of asthma. This study tested whether AAV2/9 vector carrying CC10 could reduce inflammatory and asthmatic responses in OVA-induced asthmatic mouse model. The results showed that AAV2/9-CC10 vector virus significantly reduced airway hyperresponsiveness, CCL11, interleukin (IL)-4, IL-5, IL-6, IL-13, and eosinophilia in the lungs of sensitized mice. CC10 level in OVA-sensitized mice was rescued with the administration of AAV2/9-CC10 vector virus. Lung tissue remodeling, including collagen deposition and goblet cell hyperplasia, was also alleviated. However, serum levels of OVA-specific IgG1 and IgE as well as Th2 cytokine levels in OVA-stimulated splenocyte culture supernatants were at the comparable levels to the sensitized control group. The results demonstrate that AAV2/9-CC10 vector virus relieved local inflammatory and asthmatic responses in lung. Therefore, we propose that AAV2/9-CC10 vector virus guaranteed sufficient CC10 expression and had an anti-inflammatory effect in asthmatic mice. It might be applied as a novel therapeutic approach for asthma.

Pseudotyped Adeno-Associated Virus 2/9-DeliveredCCL11shRNA Alleviates Lung Inflammation in an Allergen-Sensitized Mouse Model

Airway infiltration by eosinophils is a major characteristic of chronic asthma. CCL11 (eotaxin-1) is secreted by lung epithelial cells and functions as the major chemokine for eosinophil recruitment. Pseudotyped adeno-associated virus (AAV) 2/9, composed by the AAV2 rep and AAV9 cap genes, can efficiently target lung epithelial cells and might carry gene sequences with therapeutic potential for asthma. This study aimed to determine whether pseudotyped AAV2/9 virus carrying the small hairpin RNA targeting CCL11 and expressed by CMV/U6 promoter could reduce eosinophilia and asthmatic responses in mite allergen-sensitized mice. Mice were sensitized by intraperitoneal and challenged by intratracheal injection with recombinant Dermatophagoides pteronyssinus group 2 allergen (rDp2). AAV2/9 viral vectors were intratracheally injected three days before the first challenge. AAV2/9 sh47 virus significantly reduced airway hyperresponsiveness, airway resistance, CCL11 levels, and eosinophilia in the lungs of sensitized mice. Th2 cytokines, including interleukins (IL)-4, IL-5, and IL-10, were also significantly reduced in the bronchoalveolar lavage fluid of AAV2/9 sh47 virus-treated mice. Th2 cytokine levels were also reduced in rDp2-stimulated mediastinal lymphocytes in treated mice. However, serum levels of rDp2-specific IgG1 and IgE, as well as Th2 cytokine levels in rDp2-stimulated splenocyte culture supernatants, were comparable to the sensitized control group. The results suggest that AAV2/9 sh47 virus relieved local instead of systemic inflammatory responses. Therefore, the CMV/U6 promoter with AAV2/9 viral vector, which is preferable to target lung epithelia cells, might be applied as a novel therapeutic approach for asthma.

Intra-airway administration of small interfering RNA targeting plasminogen activator inhibitor-1 attenuates allergic asthma in mice

Recent studies suggest that plasminogen activator inhibitor-1 (PAI-1), a major inhibitor of the fibrinolytic system, may promote the development of asthma. To further investigate the significance of PAI-1 in the pathogenesis of asthma and determine the possibility that PAI-1 could be a therapeutic target for asthma, this study was conducted. First, PAI-1 levels in induced sputum (IS) from asthmatic subjects and healthy controls were measured. In asthmatic subjects, IS PAI-1 levels were elevated, compared with that of healthy controls, and were significantly higher in patients with long-duration asthma compared with short-duration asthma. PAI-1 levels were also found to correlate with IS transforming growth factor-β levels. Then, acute and chronic asthma models induced by ovalbumin were established in PAI-1-deficient mice and wild-type mice that received intra-airway administrations of small interfering RNA against PAI-1 (PAI-1-siRNA). We could demonstrate that eosinophilic airway inflammation and airway hyperresponsiveness were reduced in an acute asthma model, and airway remodeling was suppressed in a chronic asthma model in both PAI-1-deficient mice and wild-type mice that received intra-airway administration of PAI-1-siRNA. These results indicate that PAI-1 is strongly involved in the pathogenesis of asthma, and intra-airway administration of PAI-1-siRNA may be able to become a new therapeutic approach for asthma.

Adeno-associated virus-mediated CCL11 shRNA reduced lung inflammatory responses in a mite allergen-sensitized mouse model (107.13)

Abstract Asthma is considered as a chronic pulmonary inflammatory disease, characterized by eosinophilia. Lung epithelium cells secrete CCL11, the major chemokine for the recruitment of eosinophils. Hybrid adeno-associated virus serotype 2/9 might achieve long-term gene delivery specifically to lung epithelium cells. Thus, this study tested whether hybrid AAV2/9 virus carrying shRNA specific for CCL11, sh47 and sh137, could reduce eosinophilia in a mite allergen-sensitized mouse model. Both sh47 and sh137 viruses significantly reduced CCL11 level in CCL11-transformed NIH 3T3 cells, compared with others. Both viruses were delivered into Dp2 (group 2 allergen of Dermatophagoides pteronyssinus) sensitized mice before first challenge. The results showed that sh47 virus significantly reduced airway resistance, airway hyperresponsiveness, CCL11 levels and eosinophilia in the lungs of Dp2-sensitized mice. Th2 cytokines were also significantly reduced in the bronchoalveolar lavage fluid and Dp2-stimulated mediastinal lymphocytes of sh47 virus-treated mice. However, serum levels of Dp2-specific IgG1 and IgE as well as Th2 cytokine levels in Dp2-stimulated splenocytes culture supernatants were at the comparable levels to the untreated group. The results suggest that sh47 virus relieved local instead of systemic inflammatory responses. Therefore, the hybrid AAV2/9 viral vector, which is preferable to target lung epithelia cells, might be applied as a novel therapeutic approach for asthma.

Effect of Inhibition of the Ubiquitin-Proteasome-System and IκB Kinase on Airway Inflammation and Hyperresponsiveness in a Murine Model of Asthma

The current treatment of asthma is far from optimal and there is a need for novel therapeutic approaches. NFkB has recently been highlighted as an important pro-inflammatory transcriptional factor and its blockade is believed to represent a new therapeutic approach for asthma. The purpose of this study is to investigate the effects of blocking the actions of NFkB, through inhibition of the ubiquitin-proteasome system (UPS) or IkB kinase (IKK), in a murine model of asthma. Treatment with the UPS inhibitor, MG-132 (0.03 and 0.1 mg/kg), did not significantly affect the ovalbumin-induced increase in total and differential cell numbers, histological changes such as perivascular and peribronchial inflammatory cell infiltration, perivascular and peribronchial fibrosis or the increased Penh to methacholine. In contrast, treatment of mice with the IKK inhibitor, BAY 11-7085, (3 and 10 mg/kg) dose-dependently inhibited the ovalbumin-induced increase in airway leukocyte influx and decreased the percentage of airway lymphocytes, neutrophils and eosinophils. Also, BAY 11-7085-treated (10 mg/kg) mice showed a significant decrease in the histologically assessed inflammatory indices as well as a significant reduction in the ovalbumin-induced increase in Penh to inhaled methacholine. Furthermore, BAY 11-7085 significantly inhibited the ovalbumin-induced increase in the level of phosphorylation of IkBalpha and extracellular regulated kinases (ERK) 1/2, whilst MG-132 significantly increased the phosphorylation of (ERK) 1/2. These findings confirm the critical role that NFkB plays in airway inflammation, highlight the importance of IKK in regulating the pro-inflammatory activity of NFkB and also suggest that UPS may not be a useful drug target for asthma treatment.

Recent Developments in Targeting Eosinophil Accumulation as a Novel Therapeutic Approach for Asthma

Current therapies for asthma are aimed at controlling disease symptoms and for the majority of patients inhaled glucocorticoid anti-inflammatory therapy is both effective and well-tolerated. However, concerns remain about the adverse effects of glucocorticoids while a subset of asthmatic patients remains symptomatic despite optimal treatment thereby creating a clear unmet medical need. There is considerable evidence that implicates eosinophils as important effector cells and immunomodulators in the inflammation characteristic of asthma. Numerous in vitro and animal studies have demonstrated essential roles for cell adhesion molecules in eosinophil adhesion and transendothelial migration including the selectins, ICAM-1, VCAM-1 together with many of the μ1 and μ2 integrins. A large body of evidence has also implicated several cytokines and chemokines in the selective recruitment of eosinophils to sites of asthmatic inflammation. Biopharmaceutical approaches have been used to identify inhibitory molecules that target key elements in the processes controlling eosinophil accumulation in asthma. This review will summarise the problems and successes regarding recent developments in therapeutic strategies aimed at reducing eosinophil-mediated inflammation in the asthmatic lung.

Targeting TNF-α: A novel therapeutic approach for asthma

Targeting TNF-α: A novel therapeutic approach for asthma

Three Generations of Ongoing Controversies Concerning the Use of Short Acting Beta-Agonist Therapy in Asthma: A Review

An increase in asthma mortality in 1960s noted by British authors stirred a debate about the use of beta-adrenergic therapy that has persisted in the medical literature. The cause appears to be isoproterenol and fenoterol overuse. A second debate evolved around the possible deleterious, pro-inflammatory effects, of the albuterol distomer. Most clinical studies showed improved bronchodilatation, but limited benefits from using levalbuterol. Recently, genotyping has uncovered a single nucleotide polymorphism at codon 16 that appears to affect the long term response to both regular and as needed use of albuterol, calling for a new genotype based therapeutic approach in asthma.

A New Immunotherapy Approach: Mucosal Immunization With An Il-13 Vaccine Suppresses Murine Airway Allergic Responses

RATIONALE: Previously we have shown that subcutaneous administration of an IL-13 peptide-based vaccine, developed in our laboratory, significantly suppresses murine airway allergic inflammation. Now, we sought to assess whether mucosal immunization with the IL-13 vaccine is better than subcutaneous immunization and its underlying mechanisms.METHODS: An IL-13 vaccine employing Hepatitis B core antigen as a carrier with an insert of the selected IL-13 peptide was constructed using gene engineering method and expressed as a fusion protein. BALB/c mice (8/group) were immunized intranasally three times with the vaccine, vaccine carrier, or phosphate-buffered-saline. Another group of mice was immunized subcutaneously with the vaccine. Following immunization, mice were sensitized twice intraperitoneally and challenged once intranasally with ovalbumin. Methacholine-induced airway hyperresponsiveness was measured 2 days and bronchoalveolar lavage fluids (BALF) were collected 5 days after intranasal challenge. IL-13 specific-IgA in BALF and -IgG in serum were assayed using ELISA. Differential cell counts of inflammatory cells in BALF were performed.RESULTS: Mice immunized intranasally, not subcutaneously, with vaccine produced significantly higher levels of IL-13 specific-IgA in BALF. Intranasal immunization also produced stronger serum IL-13 specific-IgG responses than subcutaneous immunization. BALF eosinophil percentages and airway hyperresponsiveness were also significantly reduced in mice receiving intranasal administration of vaccine, when compared to mice receiving carrier intranasally, or receiving vaccine subcutaneously as well as receiving saline.CONCLUSIONS: Intranasal administration of IL-13 vaccine is more effective in suppressing airway allergic responses than subcutaneous immunization, which may provide a potential therapeutic approach in asthma. RATIONALE: Previously we have shown that subcutaneous administration of an IL-13 peptide-based vaccine, developed in our laboratory, significantly suppresses murine airway allergic inflammation. Now, we sought to assess whether mucosal immunization with the IL-13 vaccine is better than subcutaneous immunization and its underlying mechanisms. METHODS: An IL-13 vaccine employing Hepatitis B core antigen as a carrier with an insert of the selected IL-13 peptide was constructed using gene engineering method and expressed as a fusion protein. BALB/c mice (8/group) were immunized intranasally three times with the vaccine, vaccine carrier, or phosphate-buffered-saline. Another group of mice was immunized subcutaneously with the vaccine. Following immunization, mice were sensitized twice intraperitoneally and challenged once intranasally with ovalbumin. Methacholine-induced airway hyperresponsiveness was measured 2 days and bronchoalveolar lavage fluids (BALF) were collected 5 days after intranasal challenge. IL-13 specific-IgA in BALF and -IgG in serum were assayed using ELISA. Differential cell counts of inflammatory cells in BALF were performed. RESULTS: Mice immunized intranasally, not subcutaneously, with vaccine produced significantly higher levels of IL-13 specific-IgA in BALF. Intranasal immunization also produced stronger serum IL-13 specific-IgG responses than subcutaneous immunization. BALF eosinophil percentages and airway hyperresponsiveness were also significantly reduced in mice receiving intranasal administration of vaccine, when compared to mice receiving carrier intranasally, or receiving vaccine subcutaneously as well as receiving saline. CONCLUSIONS: Intranasal administration of IL-13 vaccine is more effective in suppressing airway allergic responses than subcutaneous immunization, which may provide a potential therapeutic approach in asthma.

690. Gene Delivery Targeting CCR3 Using SV40-Derived Vectors: A Novel Therapeutic Approach for Allergic Diseases

CCR3 is constitutively expressed on eosinophils, basophils, mast cells and type 2 T lymphocytes. These cells collectively constitute the majority of the inflammatory infiltrates in many diseases caused by immunologic hypersensitivity. CCR3 is known to act as a receptor for several chemokines: eotaxin, RANTES, MIP1-|[alpha]| and MIP1-|[beta]|. Eotaxin is produced by monocytes and T lymphocytes. It stimulates migration of eosinophils and is involved in maintaining allergic responses. Thus targeting CCR3 for downregulation may be an appealing therapeutic approach in asthma.

The OXE receptor: a new therapeutic approach for asthma?

The eicosanoid 5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-oxo-ETE) has recently been identified as the ligand for the oxoeicosanoid (OXE) receptor. In vitro and in vivo studies have suggested that 5-oxo-ETE has a role in the asthmatic inflammatory response and it has been shown to stimulate eosinophil migration to the airways. New data suggest that eosinophils have an important role in the pathogenesis of asthma, being required for mucus accumulation, airway hyperresponsiveness and remodelling of the airways. However, there are several mediators that can stimulate the recruitment of eosinophils to the airways and the development of antagonists against the OXE receptor is required to evaluate the potential of the OXE receptor as a new therapeutic approach for asthma.

New approaches in the treatment of asthma.

Asthma is a common and complex inflammatory disease of the airways that remains incurable. Current forms of therapy are long term and may exhibit associated side-effect problems. Major participants in the development of an asthma phenotype include the triggering stimuli such as the allergens themselves, cells such as T cells, epithelial cells and mast cells that produce a variety of cytokines including IL-5, GM-CSF, IL-3, IL-4 and IL-13 and chemokines such as eotaxin. Significantly, the eosinophil, a specialized blood cell type, is invariably associated with this disease. The eosinophil has long been incriminated in the pathology of asthma due to its ability to release preformed and unique toxic substances as well as newly formed pro-inflammatory mediators. The regulation of eosinophil production and function is carried out by soluble peptides or factors. Of these IL-5, GM-CSF and IL-3 are of paramount importance as they control eosinophil functional activity and are the only known eosinophilopoietic factors. In addition they regulate the eosinophil life span by inhibiting apoptosis. While one therapeutic approach in asthma is directed at inhibiting single eosinophil products such as leukotrienes or single eosinophil regulators such as IL-5, we believe that the simultaneous inhibition of more than one component is preferable. This may be particularly important with eosinophil regulators in that not only IL-5, but also GM-CSF has been repeatedly implicated in clinical studies of asthma. The fact that GM-CSF is produced by many cells in the body and in copious amounts by lung epithelial cells highlights this need further. Our approach takes advantage of the fact that the IL-5 and GM-CSF receptors (as well as IL-3 receptors) utilize a shared subunit to bind, with high affinity, to these cytokines and the same common subunit mediates signal transduction culminating in all the biological activities mentioned. By generating the monoclonal antibody BION-1 to the cytokine binding region of the common subunit (betac) we have shown that the approach of inhibiting IL-5, GM-CSF and IL-3 binding and the resulting stimulation of eosinophil production and function with a single agent is feasible. Furthermore we have used BION-1 as a tool to crystallize and define the structure of the cytokine binding domain of betac. This knowledge and this approach may lead to the generation of novel therapeutics for the treatment of asthma.