published_or_final_version / Pathology / Master / Master of Medical Sciences

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[ Truncated abstract ] Atopic diseases such as asthma are thought to be driven to a significant extent by T helper memory cells which are programmed to respond in a harmful way to environmental allergens (e.g. house dust mite). Previous studies in humans and in animal models have established that activation of TH2 cytokine genes in T memory responses to allergens is central to the disease process. However, only a subset of atopics harbouring a TH2-memory response phenotype manifests clinical symptoms of disease. Moreover, clinical trials with TH2 antagonists in atopic patients have proven disappointing, suggesting underlying complexities in disease pathogenesis which escape regulation via these approaches. It was thus hypothesised that additional genes involved in the activation program of allergen-specific T memory cells which are central to disease pathogenesis remain unidentified. The aim of the current study was to identify such novel genes by applying microarray technology to survey genome-wide expression patterns in an in vitro model of allergen-driven human T cell activation. In contrast to previous human microarray studies in this area focusing on mitogen activated T cell lines and clones, the current study avoided the use of strong activation stimuli which have the potential to distort patterns of gene expression, and reports for the first time the findings of microarray analysis of house dust mite allergen-driven acute gene activation in recirculating T memory cells harvested from the peripheral blood of human atopics. ... Finally, methodology was established to investigate the function of the novel atopy-associated genes. In loss-of-function experiments, expression of DACT1 and CAMK2D was silenced in primary T cell responses driven by bacterial superantigens, a model system for studying T cell responses under conditions which mimic antigen-specific activation. Whilst silencing DACT1 and CAMK2D expression did not influence classical readouts of T cell function including proliferation and cytokine production, microarray profiling was employed to identify putative downstream transcriptional targets of each gene. The experimental strategy and optimised methodology presented herein can now be employed to investigate the molecular circuitry linking the novel atopy-associated genes to the T cell activation process. In conclusion, several novel genes associated with allergen-driven T memory responses in atopics have been first described in this thesis and represent logical candidates for more detailed immunological and genetic studies related to the pathogenesis of atopic diseases.

Wang, Shuxin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 191-212). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese; appendixes includes Chinese.