Showing papers by "Donna E. Davies published in 2006"

Role of deficient type III interferon-λ production in asthma exacerbations

Abstract: Rhinoviruses are the major cause of asthma exacerbations, and asthmatics have increased susceptibility to rhinovirus and risk of invasive bacterial infections. Here we show deficient induction of interferon-λs by rhinovirus in asthmatic primary bronchial epithelial cells and alveolar macrophages, which was highly correlated with severity of rhinovirus-induced asthma exacerbation and virus load in experimentally infected human volunteers. Induction by lipopolysaccharide in asthmatic macrophages was also deficient and correlated with exacerbation severity. These results identify previously unknown mechanisms of susceptibility to infection in asthma and suggest new approaches to prevention and/or treatment of asthma exacerbations.

The contribution of transforming growth factor-beta and epidermal growth factor signalling to airway remodelling in chronic asthma.

Abstract: Asthma is increasing in prevalence in the developing world, affecting approximately 10% of the world's population. It is characterised by chronic lung inflammation and airway remodelling associated with wheezing, shortness of breath, acute bronchial hyperresponsiveness to a variety of innocuous stimuli and a more rapid decline in lung function over time. Airway remodelling, involving proliferation and differentiation of mesenchymal cells, particularly myofibroblasts and smooth muscle cells, is generally refractory to corticosteroids and makes a major contribution to disease chronicity. Transforming growth factor-beta is a potent profibrogenic factor whose expression is increased in the asthmatic airways and is a prime candidate for the initiation and persistence of airway remodelling in asthma. This review highlights the role of transforming growth factor-beta in the asthmatic lung, incorporating biosynthesis, signalling pathways and functional outcome. In vivo, however, it is the balance between transforming growth factor-beta and other growth factors, such as epidermal growth factor, which will determine the extent of fibrosis in the airways. A fuller comprehension of the actions of transforming growth factor-beta, and its interaction with other signalling pathways, such as the epidermal growth factor receptor signalling cascade, may enable development of therapies that control airway remodelling where there is an unmet clinical need.

IL-4 Receptor α Is an Important Modulator of IL-4 and IL-13 Receptor Binding: Implications for the Development of Therapeutic Targets

Abstract: IL-4 is a key cytokine associated with allergy and asthma. Induction of cell signaling by IL-4 involves interaction with its cognate receptors, a complex of IL-4Ralpha with either the common gamma-chain or the IL-13R chain alpha1 (IL-13Ralpha1). We found that IL-4 bound to the extracellular domain of IL-4Ralpha (soluble human (sh)IL-4Ralpha) with high affinity and specificity. In contrast with the sequential mechanism of binding and stabilization afforded by IL-4Ralpha to the binding of IL-13 to IL-13Ralpha1, neither common gamma-chain nor IL-13Ralpha1 contributed significantly to the stabilization of the IL-4:IL-4Ralpha complex. Based on the different mechanisms of binding and stabilization of the IL-4R and IL-13R complexes, we compared the effects of shIL-4Ralpha and an IL-4 double mutein (R121D/Y124D, IL-4R antagonist) on IL-4- and IL-13-mediated responses. Whereas IL-4R antagonist blocked responses to both cytokines, shIL-4Ralpha only blocked IL-4. However, shIL-4Ralpha stabilized and augmented IL-13-mediated STAT6 activation and eotaxin production by primary human bronchial fibroblasts at suboptimal doses of IL-13. These data demonstrate that IL-4Ralpha plays a key role in the binding affinity of both IL-13R and IL-4R complexes. Under certain conditions, shIL-4Ralpha has the potential to stabilize binding IL-13 to its receptor to augment IL-13-mediated responses. Thus, complete understanding of the binding interactions between IL-4 and IL-13 and their cognate receptors may facilitate development of novel treatments for asthma that selectively target these cytokines without unpredicted or detrimental side effects.

Understanding the pathophysiology of severe asthma to generate new therapeutic opportunities.

Abstract: Although asthma is defined in terms of reversibility of airflow obstruction, as the disease becomes more severe and chronic, it adopts different characteristics, including a degree of fixed airflow obstruction and corticosteroid refractoriness. Underlying these phenotypes is evidence of airway wall remodeling, which should be distinguished from the increase in smooth muscle linked to airways hyperresponsiveness. Aberrant epithelial-mesenchymal communication leads to a chronic wound scenario, which is characterized by activation of the epithelial-mesenchymal trophic unit, epithelial damage, the laying down of new matrix, and greater involvement of neutrophils in the inflammatory response. In allergic asthmatic patients who remain symptomatic despite high-dose corticosteroid therapy, blockade of IgE with omalizumab confers appreciable clinical benefit. Chronic severe asthma is also accompanied by a marked increase in TNF-α production that might contribute to corticosteroid refractoriness. Based on this, TNF blockade with the soluble fusion protein entanercept produces improvement in asthma symptoms, lung function, and quality of life paralleled by a marked reduction in airways hyperresponsiveness. Identification of novel susceptibility genes, such as a disintegrin and metalloprotease 33 (ADAM33), will provide further targets against which to direct novel therapies for asthma, especially at the more severe end of the disease spectrum.

Shotgun proteomic analysis of human-induced sputum.

Abstract: Induced sputum is a readily accessible biological fluid whose composition may alter as a consequence of disease. To date, however, the proteins that routinely populate this biofluid are largely unknown, in part due to the technical difficulties in processing such mucin-rich samples. To provide a catalogue of sputum proteins, we have surveyed the proteome of human-induced sputum (sputome). A combination of 2-D gel analysis and GeLC-MS/MS allowed a total of 191 human proteins to be confidently assigned. In addition to the expected components, several hitherto unreported proteins were found to be present, including three members of the annexin family, kallikreins 1 and 11, and peroxiredoxins 1, 2 and 5. Other sets of proteins identified included four proteins previously annotated as hypothetical or conserved hypothetical. Taken together, these data represent the first extensive survey of the proteome of induced sputum and provide a platform for future identification of biomarkers of lung disease.

The genetics of asthma: ADAM33 as an example of a susceptibility gene

Abstract: The ability to identify novel disease genes by positional cloning led to the identification of a disintegrin and metalloprotease (ADAM)33 gene on chromosome 20p13 as a susceptibility gene for asthma. Case-control and family-based association studies have mostly confirmed a link between ADAM33 and asthma. Its restricted expression to mesenchymal cells as well as its association with bronchial hyperresponsiveness and accelerated decline in lung function over time point strongly to its involvement in the structural airway components of asthma, such as remodeling. Extensive alternative splicing, expression during branching morphogensis in the developing fetus, impaired lung function in childhood, the production of a soluble form linked to chronic asthma, and tight epigenetic regulation indicate a level of complexity in the way ADAM33 influences disease phenotype. Its recent association with chronic obstructive pulmonary disease as well as with asthma and lung development points to functions relating to airway wall modeling and remodeling as a general morphogenetic repair gene rather than being restricted to asthma.

IL-13 receptor alpha 2: a regulator of IL-13 and IL-4 signal transduction in primary human fibroblasts.

Abstract: Background IL-13 and IL-4 share many functional properties as a result of their use of a common receptor complex comprising IL-13 receptor α 1 (IL-13Rα1) and IL-4 receptor α (IL-4Rα). The nonsignaling receptor IL-13 receptor α 2 (IL-13Rα2) binds IL-13 with high affinity and specificity and is believed to be a decoy receptor for IL-13. Objective We sought to examine the inhibitory effects of soluble and membrane-bound IL-13Rα2 on IL-13– and IL-4–mediated effects. Methods Primary human fibroblasts were grown from endobronchial biopsy specimens obtained from volunteers. Upregulation of IL-13Rα2 mRNA was measured by means of RT-PCR, and the level of surface expression was measured by means of FACS. Results We found that a recombinant soluble form of IL-13Rα2 blocked the effects of IL-13, but not IL-4, in fibroblasts in vitro . However, we found that the transmembrane form of IL-13Rα2 could attenuate both IL-13 and IL-4 responses, even though the response to TNF-α was unaffected. Furthermore, we found that IL-13Rα2 became associated with IL-4Rα in the presence of IL-4. Addition of a blocking antibody to the extracellular domain of IL-13Rα2 restored responses of both IL-13 and IL-4. Conclusion The ability of IL-13Rα2 to regulate IL-4 was previously unrecognized in primary airway cells. These data reveal a novel role for IL-13Rα2 as a negative regulator of both IL-13 and IL-4 signaling in human bronchial fibroblasts. Clinical implications It appears that IL-13Rα2 might be a powerful suppressor of T H 2-mediated responses and thus represents a potential therapeutic target for the treatment of asthma.

Enhanced upregulation of smooth muscle related transcripts by TGFβ2 in asthmatic (myo) fibroblasts

Abstract: Background: Transforming growth factor beta (TGFβ) upregulates a number of smooth muscle specific genes in (myo)fibroblasts As asthma is characterised by an increase in airway smooth muscle, we postulated that TGFβ 2 favours differentiation of asthmatic (myo)fibroblasts towards a smooth muscle phenotype Methods: Primary fibroblasts were grown from bronchial biopsy specimens from normal (n = 6) and asthmatic (n = 7) donors and treated with TGFβ 2 to induce myofibroblast differentiation The most stable genes for normalisation were identified using RT-qPCR and the geNorm software applied to a panel of 12 “housekeeping” genes Expression of α-smooth muscle actin (αSMA), heavy chain myosin (HCM), calponin 1 (CPN 1), desmin, and γ-actin were measured by RT-qPCR Protein expression was assessed by immunocytochemistry and western blotting Results: Phospholipase A2 and ubiquitin C were identified as the most stably expressed and practically useful genes for normalisation of gene expression during myofibroblast differentiation TGFβ 2 induced mRNA expression for all five smooth muscle related transcripts; αSMA, HCM and CPN 1 protein were also increased but desmin protein was not detectable Although there was no difference in basal expression, HCM, CPN 1 and desmin were induced to a significantly greater extent in asthmatic fibroblasts than in those from normal controls (p = 0041 and 0011, respectively) Conclusions: Although TGFβ 2 induced the transcription of several smooth muscle related genes, not all were translated into protein Thus, while TGFβ 2 is unable to induce a bona fide smooth muscle cell phenotype, it may “prime” (myo)fibroblasts for further differentiation, especially if the cells are derived from asthmatic airways

CD40 ligation protects bronchial epithelium against oxidant-induced caspase-independent cell death

Abstract: CD40 and its ligand regulate pleiotropic biological responses, including cell proliferation, differentiation, and apoptosis. In many inflammatory lung diseases, tissue damage by environmental or endogenous oxidants plays a major role in disease pathogenesis. As the epithelial barrier is a major target for these oxidants, we postulated that CD40, the expression of which is increased in asthma, plays a role in the regulation of apoptosis of bronchial epithelial cells exposed to oxidants. Using 16HBE 14o- cells exposed to oxidant stress, we found that ligation of CD40 (induced by G28-5 monoclonal antibodies) enhanced cell survival and increased the number of cells in G2/M (interphase between DNA synthesis and mitosis) of the cell cycle. This was associated with NF-kappaB and activator protein-1 activation and increased expression of the inhibitor of apoptosis, c-IAP1. However, oxidant stress-induced apoptosis was found to be caspase- and calpain-independent implicating CD40 ligation as a regulator of caspase-independent cell death. This was confirmed by the demonstration that CD40 ligation prevented mitochondrial release and nuclear translocation of apoptosis inducing factor. In conclusion, we demonstrate a novel role for CD40 as a regulator of epithelial cell survival against oxidant stress. Furthermore, we have identified, for the first time, an endogenous inhibitory pathway of caspase-independent cell death.

Interferon lambda therapy for treatment of respiratory diseases

Abstract: The present invention relates to use of one or more interferon lambdas (IFN-λs), also known as IL-29 and IL28a/b, for alleviating or preventing viral-induced exacerbation of a respiratory disorder, especially for example exacerbation of asthma arising from viral infection, most commonly rhino virus infection.

Anti-virus therapy for respiratory diseases

Abstract: The present invention provides the use of IFN-β, an agent that increases the expression of IFN-β, or a polynucleotide which is capable of expressing IFN-β or said agent for the manufacture of a medicament for the treatment of rhinovirus-induced exacerbation of a respiratory disease selected from asthma and chronic obstructive pulmonary disease, wherein said treatment is by airway delivery of said medicament, eg by use of an aerosol nebuliser Also provided is IFN-λ for the same purpose

Screening assay for improvement of epithelial barrier function

Abstract: The present invention relates to the use of an air-liquid interface culture model using asthmatic bronchial epithelial cells, which exhibit impaired epithelial barrier function. It is proposed to use asthmatic epithelial cultures, in the absence of added Th2 or proinflammatory cytokines such as IL-13, as an in vitro model to screen for agents that can act to improve impaired asthmatic epithelial barrier function. Such agents may have therapeutic utility in asthma patients.

Therapie par interferon lambda pour le traitement de maladies respiratoires

Abstract: La presente invention concerne l'utilisation d'un ou plusieurs interferons lambda (IFN-μ), egalement connus sous le nom d'IL-29 et d'IL-28a/b, pour attenuer ou prevenir une exacerbation d'origine virale d'un trouble respiratoire, telle qu'une exacerbation de l'asthme liee a une infection virale, et notamment a une infection a rhinovirus.