Asthma, Allergy & Lung Biology (AALB) (Research Division)

I am currently researching the molecular mechanisms regulating immunoglobulin heavy chain class switch recombination and the role chromatin structure plays in its regulation. In particular I am focusing on identifying novel transcription factors, chromatin remodelling enzymes and microRNAs that regulate class switching towards IgE; the isotype involved in asthma and allergy. I am also interested in the mechanisms regulating the activity and targeting of the enzyme Activation Induced Cytidine Deaminase (AID). AID is responsible for initiating immunoglobulin gene diversification by somatic hypermutation and class switching and is thought to be responsible for the mutagenic events that lead to B cell malignancies.

Our research focuses on characterisation of G-protein coupled receptors (GPCRs) (the largest family of transmembrane signalling molecules) and their role in immune reactions leading to chronic inflammatory diseases, such as bronchial asthma and allergic diseases. Although, GPCRs are targets for more than 30% of all approved drugs, the expression and function of many of those receptors are incompletely characterized, and many remain orphans (without known ligands). The last years have seen remarkable advances in structural and functional biology of GPCRs that await now for translational medicine research. The understanding of GPCR responsiveness to lipid mediators such as leukotrienes, prostaglandins, lipoxins and lysophospholipids and their role in pathophysiology of asthma and allergic diseases is still based on data obtained long time ago and often does not agree with current discoveries. Newly developed molecular and cellular biology methods allow us to re-evaluate tissue and cell type specific expression, signalling and function of GPCRs and to redefine their role in processes leading to airway inflammation, bronchoconstriction, hyperresponsiveness and airway remodelling. A better understanding of GPCR biology may lead to development of new therapies for asthma and allergy.

The focus of work in the laboratory is to understand the ways that chromatin environments dictate gene expression profiles. Whilst it is now relatively commonplace to determine gene expression profile of cells using microarrays and recently by RNA sequencing, there have been fewer studies of either organisation of post-translationally modified histones or methylated cytosine residues in the genome. We are undertaking such studies using a variety of cell types known to play roles in asthma, such as Th2 cells, airways smooth muscle and bronchial epithelial cells. Our objective is to determine profiles of these marks in healthy cells and determine locations at which differences are observed in cells from people with asthma. From these data we aim to determine whether there are epigenetic signatures that lead to defective gene expression in asthma and whether we can identify the biochemical pathways controlling the epigenetic differences. Further objectives are the mapping of disease associated polymorphisms onto these landscapes with particular focus upon DNA variation at non-exonic sites. We are also studying how viral infection affects both the transcriptome and epigenome using cells from healthy and asthmatic people.

1. Development of interventional bronchoscopy & EBUS in the diagnosis and management of thoracic pathologies particularly cancer. The EBUS service that he leads is one of the largest in the world and provides an integrated approach to clinical delivery and translational research.
2. Biology of adenovirus/host cell interaction and particularly the role of the coxsackie B virus adenovirus receptor (CAR) in cell-cell junction formation and maintenance in the normal and inflamed airway epithelium.
3. Erb receptor biology in non-small cell lung cancer and the development of novel single molecule assays in patient- derived specimens to assess dysregulation of the Erb family of membrane receptors and develop targets for new biological therapies.

The concept of inflammation as a key player in the process of carcinogenesis is well recognised in the literature, but remains poorly understood. Lung cancer, pulmonary fibrosis and mesothelioma are characteristically inflammatory diseases, and are hampered in the clinical arena by a lack of efficacious therapy.

We seek to further examine the relationship between inflammation and lung cancer and examine the role of the inflammatory tumour microenvironment in the perpetuation of the pro-carcinogenic state. We will look at the regulation of proliferation and apoptosis by growth factor and integrin mediated signalling, and examine the impact of key inflammatory populations of cells such as macrophages and fibroblasts in this process. Specifically we aim to investigate the role of galectin-3 and CD98 as mediators of this process in models of early stage and metastatic lung cancer, lung fibrosis and mesothelioma.

We have established murine models of disease and will use detailed functional imaging to illustrate tumour/ stromal interactions. Additionally our in vivo model permits us to investigate the impact of pharmacological and genetic inhibition of these target molecules in terms of inflammation, tumour growth, and metastasis. A better mechanistic understanding of these pathways will allow us to identify potential targets for intervention and develop new therapies for these diseases.

My current research is in three main areas:

• Antenatal lung growth: Impaired antenatal lung growth is a common outcome, pulmonary hypoplasia being found in 15-20% of early neonatal deaths. Reference ranges of normal lung growth have been established, mechanisms have been elucidated and interventions evaluated in various conditions associated with abnormal growth. We have investigated the role of diaphragmatic function in abnormal lung growth, particularly in infants with surgically correctable lung anomalies and developed novel tests of diaphragmatic function in neonates. We are currently evaluating the predictive value of new antenatal assessments with regard to chronic respiratory morbidity.
• Prevention of chronic respiratory morbidity following premature birth, chronic oxygen dependency and associated respiratory morbidity is unfortunately common following very premature birth. Factors important in the development of chronic oxygen dependency have been identified and prophylactic and treatment therapies examined, this has involved the development and evaluation of new techniques of respiratory support. Currently school age children are being assessed who were born very prematurely to determine which respiratory mode is associated with better long term respiratory outcomes. Predictors of chronic lung disease have been assessed in order that prophylactic treatments can be most effectively targeted. Respiratory syncytial virus infection is associated with an increased risk of asthma in childhood in previously healthy infants and prematurely born infants suffer more severe acute RSV infection. Currently, the importance of initial airway size and genetic predisposition in determining the long term respiratory outcome in prematurely born infants who develop RSV infection is being assessed. Prematurely born infants are at increased risk of sudden infant death syndrome. As a consequence, the effect of posture and antenatal smoking exposure on respiratory control and function is being examined.
• Effect of chronic disorders on respiratory function in children is vital to diagnosis and appropriate treatment of respiratory morbidity is quantification of any abnormality. Hence an important area of research has been the development of appropriate lung function tests for all ages, even those receiving intensive care. These tests have been used to facilitate management of young children with asthma and determine the impact of liver disease on pulmonary function. Two cohorts of children with sickle cell disease in South London and Jamaica are being followed. The prevalence of lung function abnormalities in these populations has been determined and ethnically appropriate reference ranges have been established. The role of asthma/reactive airway disease in the development of the acute and chronic respiratory complications in SCD have been determined and the efficacy of prophylactic anti-asthma agents is currently being explored.

Respiratory physiology; Respiratory muscle physiology and the relationship between neural respiratory drive, respiratory load and respiratory muscle pump capacity in health and disease from infancy through to adulthood. Peripheral muscle function and its relationship to functional capacity in health and disease.

In order to find biomarkers of peanut allergy versus tolerance we are analysing gene expression in different T cell subsets pf peanut allergic and non allergic children. I am also involved in a multicentre European study with particular focus on tree-nut and peanut allergy, assessing preventative strategies against allergy and patterns of sensitisation across Europe.

My other clinical and research interests include food allergy diagnostics, preventing the allergic march and venom allergy.

Having pursued research on many aspects of respiratory physiology, particularly related to muscle function, the most fruitful area to concentrate on over the next few years is, the measurement of respiratory muscle electromyogram (EMG) as a measure of neural respiratory drive, and an integrated index of the load on, and the capacity of, the ventilatory system.

In recent years we have measured both the diaphragm and parasternal EMG in a number of studies, in normal subjects and in patient groups (COPD, CF, asthma, obesity) at rest, during exercise, during sleep, in response to bronchodilator therapy, and during exacerbations of disease.

The measurement of NRD using the respiratory muscle EMG is a very powerful clinical research tool. NRD is a biomarker of disease severity and response to treatment and is likely to be more sensitive than lung function or radiology. Parasternal EMG has the advantage of being non-invasive and as such is easily translated to the clinical setting. Assessing the impact of therapy in those diseases where it is difficult to use lung function or radiology represents a great opportunity for the NRD technique (e.g. interstitial lung disease, or paediatrics). Our work on NRD continues with an increasing clinical focus and in my judgement EMG could, and should become a routine lung function test.

In this respect my main interest is to develop new therapeutic molecules for allergy immunoprevention and immunotherapy. The identification of biomarkers of allergy and tolerance that can be used to design novel immunotherapies that can prevent or cure food and respiratory allergies represents another major interest of mine.

Our research focuses on characterisation of G-protein coupled receptors (GPCRs) (the largest family of transmembrane signalling molecules) and their role in immune reactions leading to chronic inflammatory diseases, such as bronchial asthma and allergic diseases. Although, GPCRs are targets for more than 30% of all approved drugs, the expression and function of many of those receptors are incompletely characterized, and many remain orphans (without known ligands). The last years have seen remarkable advances in structural and functional biology of GPCRs that await now for translational medicine research. The understanding of GPCR responsiveness to lipid mediators such as leukotrienes, prostaglandins, lipoxins and lysophospholipids and their role in pathophysiology of asthma and allergic diseases is still based on data obtained long time ago and often does not agree with current discoveries. Newly developed molecular and cellular biology methods allow us to re-evaluate tissue and cell type specific expression, signalling and function of GPCRs and to redefine their role in processes leading to airway inflammation, bronchoconstriction, hyperresponsiveness and airway remodelling. A better understanding of GPCR biology may lead to development of new therapies for asthma and allergy.

I am interested in why asthma remains uncontrolled in a substantial minority of patients. My research embraces the immunopathogenesis of severe asthma phenotypes such as non-atopic and aspirin sensitive asthma. I also study mechanisms of airways remodelling in asthma to identify new molecular targets which may modify the natural history of this phenomenon. I collaborate particularly with my departmental colleagues Prof Hawrylowicz, who is interested in environmental control of T regulatory cell function in asthma, including the potential roles of new therapeutic agents, Prof Ward with whom I am examining the role of bronchial smooth muscle calcium homoeostatic proteins in maintining bronchial hyperresponsiveness, the cardinal clinical feature of asthma whose genesis remains as yet unexplained, and Prof Gould with whom I investigate the role of IgE-mediated mechanisms, both established and novel, in regulating asthma severity. On the clinical side I manage the Trust omalizumab service and am running a proof of concept study of the worth of omalizumab therapy in non-atopic asthma. As leader of the Guy's allergen immunotherapy service I am also interested in improving products and regimens for immunotherapy, and participate in a number of basic and phase 3 clinical trials to this end. I am a principal investigator in the MRC and Asthma UK Centre for allergic mechanisms of Asthma, a cross-collaborative initiative with King's and Imperial Colleges, the Medical Research Council and the principal asthma charity Asthma UK.

My research focuses on human CD4-positive T-helper cell lineage commitment, with a particular interest in Th2 cell differentiation and function. We have been using microarray platforms for a number of years to identify novel Th2 specific genes and microRNAs. Our current studies are aimed at examining the function of several novel transcription factors and miRNAs in Th2 cell development using in vitro differentiation and lentiviral transduction to overexpress or ‘knock-down’ the gene of interest. In collaboration with the Lavender laboratory we also study the epigenetics of human T-helper cells using ChIP-sequencing and DNA methylation analyses.

I have a longstanding interest in the mechanisms of allergen-specific desensitisation (immunotherapy). We are currently conducting a clinical trial - supported by the MRC-NIHR Efficacy & Mechanism Evaluation programme - to investigate a novel immunotherapy vaccine for grass pollen allergy (www.pollenlite.com). This approach involves the administration of a low dose of allergen by the intradermal route as opposed to the conventional high dose subcutaneous or sublingual route (‘PollenLITE’: Pollen Low dose Intradermal Therapy Evaluation). Mechanisms will be studied in a variety of immune assays to be performed on peripheral blood and skin biopsies. A further interest concerns the properties of T cells within the human respiratory mucosa. To this end we have also recently initiated a project to investigate the phenotype and function of nasal mucosal T cells in both normal immunity and inflammatory disease (polyposis and allergic rhinitis).