Small molecule inhibitors and primary airway fibroblast activation in severe asthma

Asthma is a common and disabling problem for many, particularly those with severe persistent disease that prevents them living a normal life. In these individuals the disease leads to a progressive decline in lung function despite standard asthma therapies and the airways are left permanently impaired. Our research has shown that this can be linked to scarring within the airway wall. Such scarring is due to the deposition of collagen from activated cells called fibroblasts. This research has also demonstrated that fibroblasts, grown in the laboratory from small samples of the airway lining tissue (biopsies), from patient volunteers with severe asthma generate more collagen than do fibroblasts grown from biopsies obtained from the airways of either healthy non-asthmatic volunteers or volunteers with mild asthma. Additional studies have suggested that specific intracellular signalling pathways may be involved in this altered response. This industrial collaboration with UCB Celltech provides access to small molecule pathway inhibitors that allow the undertanding of the relevance of these pathways to the altered synthetic function of these fibroblasts. Through this better understanding it will be possible to target specific disease processes that hopefully will lead to novel therapies that in the future will prevent the progressive decline in lung function in asthma

This proposal addresses an area of significant unmet need, namely severe asthma. In chronic persistent disease there is an exaggerated decline in lung function that leads to airflow obstruction that fails to fully reverse. With progressive airflow obstruction there is greater symptom expression and an increased likelihood of disease exacerbation. This decline in lung function reflects an alteration in airway behaviour and can be attributed to structural airway changes involving extracellular matrix components. Our research has identified that there is increased interstitial deposition of collagen isotypes within the airways in asthma and that this increases with increasing disease severity. Additionally through the use of endobronchial ultrasound we have identified that asthmatics with thicker airway walls have less labile airways, demonstrating less reversibility to a bronchodilator and less constriction with an inhaled bronchoconstrictor. We have thus hypothesised that collagen deposition within the airways, whilst protecting against excessive constriction leads to progressive decline in lung function. To understand this further, primary airway fibroblasts have been cultured from endobronchial biopsies in comparative studies between healthy non-asthmatic volunteers, mild asthmatics and severe asthmatics. These have identified that in severe asthma the airway fibroblasts are in a synthetic phenotype and on stimulation responds with increased gene expression for collagen synthesis. Kinase phosphorylation analysis, in association with stimulation, reveals the involvement of AKT phosphorylation. This is likely to reflect P13 kinase activation. This proposal extends this work in an industrial collaboration with UCB Celltech, through their ability to provide of small molecule inhibitors of high specificity, that permit the assessment of the role of these kinases in the altered of fibroblast response in severe asthma. Specifically this proposal will utilise a pan PI3 and a delta-PI3 kinase inhibitor and an AKT1 and AKT2 inhibitor. This work will then extend to evaluation of P38 and MEK inhibitors. It is proposed that this collaboration will lead to future studies involving gene array analysis and proteinomics to gain detailed insight into the altered fibroblast phenotype in severe asthma.