P-157: TLR5 Gene Expression in Endometrium of Women with Unexplained Recurrent Spontaneous Abortion

Background: Recurrent spontaneous abortion (RSA) is usually defined as three or more consecutive pregnancy losses before 20th week of gestation. Although different factors are considered as etiology of RSA but in some cases, despite of extensive work up, the cause of RSA remains unknown which called unexplained RSA. Immunological factors are suggested as etiological factors of unexplained RSA. On the other hand, pattern recognition receptors (PRRs) are one of the most imperative components of innate immunity which can recognize ligands derived from various pathogens. Toll like receptors (TLRs) as a main group of PRRs consist of at least 10 functional proteins in human. After ligand recognition, TLRs activate intracellular signaling cascade which induce inflammatory and / or anti-viral responses. TLR5 is one of the cell surface TLRs which recognizes bacterial flagellin. In present study, the expression of TLR5 gene was tested in endometrium of women suffering from unexplained RSA. Materials and Methods: Endometrial samples were obtained between day 19th and 24th of menstrual cycle (window of implantation) from 10 women with unexplained RSA and 6 fertile women who had at least one successful pregnancy (control group). TLR5 gene expression was studied by RT-PCR and then quantified by real time PCR. Beta actin was used as housekeeping gene. Results: TLR5 gene expression was detected in endometrium of patients with unexplained RSA and normal women. The mean relative expression of TLR5 gene was higher in endometrium of women with unexplained RSA in compare to normal ones at significant level. Conclusion: This finding suggests that TLR5 might play important role in the pathogenesis of unexplained RSA since TLR5 signaling could result in inflammatory cytokine production. It has been also proposed that increased inflammatory microenvironment of endometrium may lead to implantation failure.