THE ROLE OF TOLL-LIKE RECEPTORS IN ASSISTED CONCEPTION

UoM administered thesis: Doctor of Medicine

  • Authors:
  • Wedad Aboussahoud

Abstract

AbstractThe University of Manchester, Wedad Aboussahoud, Doctor of Medicine (MD)The Role of Toll-Like Receptors in Assisted Conception, June/2015Background In the last two decades the discovery of the Toll-Like Receptor (TLR) family in humans revealed the importance of innate immunity in providing host defence against invading pathogens. Moreover, TLRs have a vital role in mediating the interactions between the reproductive and immune systems. Similar to TLRs, (NOD)-like receptors (NLRs); retinoic acid-inducible gene-1, RIG-1-like receptors (RLRs) are also important pattern recognition receptors in the female reproductive system. Successful implantation requires effective reciprocal interactions between receptive endometrium and competent embryo. The endometrial innate immunity during implantation has been intensively investigated. However, little is known about the expression of innate immunity during the early stages of human embryo development.Objective: To investigate the expression of innate immunity molecules during the early stages of human embryo development and to determine the functions of TLRs in blastocysts.Material and methodsThe expression of TLRs, a panel of downstream signalling molecules, NLRs, RLRs, inflammatory cytokines, chemokines and the hyaluronic acid system were investigated in the following developmental stages: oocyte, 4- cell, blastomeres, 8- cell, blastocyst, inner cell mass and trophectoderm using Affymetrix Human Genome U133 Plus 2.0 arrays. Microarray data were validated by Q-PCR. TLR function in human blastocysts was investigated by treating day five blastocysts with TLR3 or TLR5 specific ligands; Poly (I:C) and flagellin respectively, for 24 hours. The culture media was analysed for elevated cytokine and chemokine levels using cytometric bead array.ResultsTLRs, NLRs, RLRs, TLR downstream signalling molecules, cytokines and chemokines involved during implantation event and the hyaluronic system were all found to be positively expressed in the early stages of human embryo development. The expression levels of the above molecules were generally moderate to low (CT 24-34) and varied across the embryonic developmental stages. Stimulation of TLR3 and TLR5 in day 5 blastocysts produced cytokines and chemokines. In addition, there were alterations in gene expression patterns in the Poly (I:C) and flagellin treated blastocysts in comparison to the untreated blastocysts. ConclusionThe varied expression levels of the investigated molecules involved in early embryonic developmental suggests a potential role for these molecules in early pregnancy loss and implantation failure. Specifically, the relationship between the level of TLR expression, function and embryo quality is worth investigating in the future as a potential marker for embryo competence

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Original languageEnglish
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Award date1 Aug 2016