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Title: Leukotriene E4 receptors in bronchial asthma
Author: Foster, Holly
ISNI:       0000 0004 8505 1738
Awarding Body: King's College London
Current Institution: King's College London (University of London)
Date of Award: 2015
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Cysteinyl leukotriene (LTC4, LTD4 and LTE4) are proinflammatory lipid mediators involved in the pathogenesis of asthma. LTE4 the most stable of the cysteinyl leukotrienes elicits bronchoconstriction, and unlike LTC4 and LTD4 it enhances bronchial hyperresponsiveness. LTE4 can also mediate other features of asthma, such as eosinophilia, increased mucus secretion and vascular permeability. None of these LTE4 activities can be explained by current understanding of classical cysteinyl leukotriene receptors, CysLT1 and CysLT2, suggesting the presence of a novel receptor that preferentially responds to LTE4. LTE4 mediated pulmonary inflammation in a murine model was shown to remain intact in the absence of CysLT1 and CysLT2, and was abrogated by the knockout of the purinergic receptor, P2Y12. This study aimed to elucidate whether LTE4 directly signalled through the P2Y12 receptor. Models of human CysLT1, CysLT2 and P2Y12 overexpressed in HEK293T, CHO cells and human platelets were used to characterise responsiveness to cysteinyl leukotrienes. LTE4 failed to induce any specific signalling responses in cells expressing P2Y12 or in human platelets, showing that LTE4 does not directly signal through P2Y12. Previous reports have shown that LTE4 is a potent agonist in human mast cells and so the aim was to identify the receptor responsible for LTE4-induced responses using two human mast cell lines, LAD2 and LUVA. When intracellular signalling and gene expression were compared in response to stimulation, LUVA cells responded to LTC4 and LTD4 but lacked the potent responses to LTE4 observed in LAD2 cells. Gene screening by microarrays was used to identify 4 target GPCRs which were cloned and their responsiveness to cysteinyl leukotrienes analysed in HEK293T overexpression model. CysLT1 was identified as the only GPCR responding to cysteinyl leukotrienes and differently expressed in LAD2 cells. Stable knockdowns were created and analysed to reveal CysLT1 was responsible for the augmented responses to LTE4 observed in LAD2 cells.
Supervisor: Woszczek, Grzegorz Przemyslaw ; Corrigan, Christopher John ; Pease, James Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available