Menstrual cycle-dependent changes of Toll-like receptors in endometrium

BACKGROUND: Rapid innate immune defences against infection usually involve the recognition of invading pathogens by specific pattern recognition receptors recently attributed to the family of Toll-like receptors (TLRs). Reports from our laboratory and others have demonstrated the existence of TLRs 1-6 in the female reproductive tract. However, little has been done to identify TLRs 7-10 in the female reproductive tract, particularly in the uterus. Also little information exists regarding variation in TLRs in the female reproductive tract during the menstrual cycle. METHOD: The distribution of TLR7-10 protein was detected by immunostaining in timed endometrial biopsies from normal women. RT-PCR was used to show the existence of TLR1-10 genes in endometrial tissue and real-time PCR analysis to investigate the relative expression of these genes during the menstrual cycle in normal human endometrium. RESULTS: TLR7-10 proteins were detected in endometrial epithelium and stroma. TLR1-10 genes were expressed in human endometrial tissue, and the mean relative expression of TLR2-6, 9 and 10 genes was significantly higher during the secretory phase compared with other phases of the menstrual cycle. CONCLUSIONS: TLR7-10 localization is not limited to endometrial epithelium but is also present in the stroma of the endometrial tissue. Endometrial TLR2-6, 9 and 10 genes are cyclically expressed during the menstrual cycle.