Evaluating T cell subsets in neutrophilic asthmatics and in exacerbation models of asthma and COPD

  • Antonia Banyard

    Student thesis: Master of Philosophy

    Abstract

    BACKGROUND: Asthma and COPD are both complex inflammatory lung diseases. The hallmark features of these lung diseases are variable airflow obstruction, bronchial hyperreactivity and airway inflammation. T lymphocytes play a central role in the pathogenesis of airway inflammation. It is recognized that disease phenotypes exist, comprising subgroups of patients with distinct clinical or pathological characteristics associated with different prognosis or response to treatment. Neutrophilic airway inflammation in asthma and COPD patients is associated with exacerbations (from infection) and limited steroid response. Determining the level of T cell populations within distinct subgroups is essential for developing effective therapy.The aims of this thesis were: to develop a multi-parametric flow cytometry method to evaluate the subpopulations of Th1, Th2, Treg and Th17 T cell subsets both systemically and within the lung; to compare the response of asthmatic and healthy control Th1, Th2, Treg and Th17 cells (both systemic and lung) in vitro to a T cell specific stimulus; To determine the T cell profile within patients with neutrophilic airway inflammation, namely neutrophilic asthmatics and asthmatics and COPD patients post an inhaled LPS challenge.METHODS: 1) 6 neutrophilic asthmatics and age matched healthy controls were recruited and underwent a bronchoscopy and blood draw. Th1, Th2, Th17 and Tregs cell expression was measured after PMA/ionomycin ex-vivo stimulation using a multi-parametric flow cytometry method. This method was developed and validated within this study.2) Flow cytometry was also used to measure Th17 and Tregs in 6 asthmatic patients 0 and 24 hour post LPS inhalation and 11 COPD patients 0 and 4 hours post LPS inhalation.RESULTS: 1) Th1, Th2 and Th17 cells increased in the lung and the peripheral blood upon ex-vivo stimulation. There was no significant difference between the asthma group and the healthy controls. Treg expression did not increase upon stimulation and there was no significant difference between the asthma and healthy control groups. 2) In asthmatics there was no increase in Th17 or Treg cells 24 hours after LPS inhalation within the lung or the blood. In COPD patients there was a significant increase in Th17 cells in the blood 4 hours post LPS inhalation.CONCLUSIONS: 1) This cohort of neutrophilic asthmatics did not show signs of favouring a specific T cell phenotype compared to healthy controls upon ex-vivo stimulation. However there a higher expression of T cells cytokines in the lung than the blood suggesting a more reactive environment within the lung. 2) 24 hours post LPS challenge showed no differences in T cell expression in asthmatics in the lung or blood. In COPD patients Th17 cells significantly increased after 4 hours suggesting an innate rapid response in the blood after inhalation of LPS in these patients. This further understanding of the T cell immunology during both stable and exacerbated states may enable better directed therapies for these diseases.
    Date of Award1 Aug 2014
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorSukh Singh (Supervisor) & Jonathan Plumb (Supervisor)

    Cite this

    '