Title: Skewing severe asthma to a steroid sensitive phenotype by vitamin D
Funder: Asthma UK

Abstract: <p>Asthma is a heterogeneous disease with asthma endotypes (sub-types) defined on the basis of distinct pathophysiological mechanisms and responsiveness to treatment. For example Th2-associated disease is well-controlled by low-dose inhaled steroids in most patients, whilst an IL-17A/Th17 dominant endotype has recently been reported that is poorly controlled by oral steroids. Our recent immunological data indicate that steroids enhance IL-17A synthesis in culture, and that a poor or lack of clinical response to 2-weeks oral prednisolone is associated with high levels of IL-17 synthesis in PBMC cultures. Conversely good steroid responsiveness is positively associated with IL-13 synthesis.</p> <p>&nbsp;</p> <p>A strong association exists between low vitamin D status and increased severity and poor control of asthma. Results emerging from early clinical trials suggest vitamin D may reduce asthma exacerbations in children, whilst our immunological and small clinical study suggest vitamin D has steroid-enhancing effects in steroid-refractory asthma patients who exhibit a high level of vitamin D deficiency. Importantly vitamin D inhibits IL-17A synthesis, overcoming any adverse effects of steroids on this response. Based on the above data, generated as part of two previous Asthma UK grants (08/019; 11/040), we aim to test the following:</p> <p>&nbsp;</p> <p><u>Hypothesis 1</u>: &nbsp;It is possible to predict severe asthma patients who do not respond to steroids based on vitamin D status and immune phenotype.<u></u></p> <p><u>Research Objective: </u></p> <p>Identify genes/biomarkers that can be used to rapidly and non-invasively identify the IL-17Ahigh steroid-refractory asthma endotype. This will utilize cells from clinically-defined steroid-sensitive and steroid-refractory asthma patients archived from our clinical trial that have been stimulated in the presence or absence of dexamethasone in culture. We will perform transcriptional gene arrays in order to identify genes/pathways that are differentially expressed between steroid-sensitive versus steroid-refractory, IL-17Ahigh versus IL-17low phenotypes, or induced by dexamethasone in culture. These will be validated in unmanipulated samples (directly ex vivo) of PBMC and CD4+ T cells from steroid-sensitive and steroid&ndash;refractory patients, and in drug-treated PBMC cultures.</p> <p>&nbsp;</p> <p><u>Hypothesis 2</u>.</p> <p>Vitamin D treatment improves the clinical response to steroids by changing the immune response thereby making it more amenable to steroid inhibition.</p> <p><u>Research Objective:</u></p> <p>To develop a human airway model, based on recently published studies, to assess the impact of vitamin D deficiency and sufficiency on immune phenotype and steroid-responsiveness in the airways at baseline and following allergen challenge. Cytokines associated with asthmatic disease will be assessed in nasal lining fluids. We will investigate whether we can isolate sufficient cells from nasal fluid to culture with and without dexamethasone or to pellet for qRT-PCR analyses to further investigate genes/pathways identified to be of interest in Section 1.</p> <p>&nbsp;</p> <p>&nbsp;</p> <p>Our over-arching goals are to (i) devise methodology to rapidly and non-invasively identify severe asthmatics who respond poorly to steroids, (ii) to increase our understanding of how vitamin D works to improve steroid sensitivity, including in the airways, to optimize its application in asthma and (iii) identify patients most likely to benefit from vitamin D therapy, enabling us to design more conclusive clinical studies to identify its therapeutic potential in asthma.</p>


Research activity codes: 4.1 DISCOVERY AND PRECLINICAL TESTING OF MARKERS AND TECHNOLOGIES
Health categories: RESPIRATORY