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Cross-talk between human T cells, mast cells and conjunctival epithelial cells

Offiah, I.; (2012) Cross-talk between human T cells, mast cells and conjunctival epithelial cells. Doctoral thesis, UCL (University College London).

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Abstract

The ocular surface is continually exposed to the outside environment and is a common site of inflammation. Conjunctival epithelial cells are thought to play a role in innate responses at the ocular surface. The hypothesis of my study is that conjunctival epithelial cells also contribute to T cell and mast cell effector mechanisms in chronic allergic eye disease via secretion of cytokines. In this study we initially demonstrate that the conjunctiva expresses TLRs, and that the TLR3 ligand (poly I:C) activates conjunctival epithelial cells in vitro to secrete inflammatory mediators as part of the innate immune response. Conjunctival tissues were also shown to express the Th2 associated cytokine, IL-13 as well as TSLP – a cytokine thought to be involved in Th2 differentiation. Conjunctival tissues from chronic allergic eye disease subjects were found to have increased IL-13 and TSLP expression compared to normal controls. Using a human conjunctival epithelial cell line, cells could be induced to express increased levels of TSLP following exposure to poly I:C or pro-inflammatory cytokines. Th17 cells, identified by coexpression of CD4 and IL-17, were also detected in CAED tissues and a high level of expression of IL-17A was localised to the epithelium. However, although capable of secreting IL- 25, IL-17A was not secreted by conjunctival epithelial cells, indicating that the IL-17 observed histologically may have been IL-17 binding to the surface of the epithelium. IL-17 receptor C (IL-17RC) expression was found to be increased in CAED tissues whilst IL-17RA was upregulated when conjunctival epithelial cells were stimulated with pro-inflammatory cytokines together with poly I:C. Blockade of IL-17RA and subsequent stimulation with IL-17 led to increased IL-8 and decreased TGF-β secretion. Although being implicated in the immunopathogenesis of certain diseases, IL-17 and its other family members may potentially serve to play an immunoregulatory role in immunity at the ocular surface.

Type:Thesis (Doctoral)
Title:Cross-talk between human T cells, mast cells and conjunctival epithelial cells
Language:English
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology

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