Sex hormones enhance TLR3 response to its specific ligand in human fallopian tube epithelial cells

Abstract

Toll-Like Receptors (TLRs) are the main family of pathogen pattern recognition receptors and constitute a major part of the innate immune system. Reports from our laboratory and others have demonstrated the existence of TLRs in the human female reproductive tract. However, little has been done to identify TLRs function in the female reproductive tract, particularly in the fallopian tubes. Sex hormones can influence TLRs expression in the female reproductive tract. However, it is not known if sex hormones can influence TLRs function in the fallopian tubes. The aim of the current investigation was to test the existence of TLR3 in an immortalised human fallopian tube epithelial cell line (OE-E6/E7) and to test the effect of sex hormones on the function of TLR3 in this cell line. TLR3 protein was detected by immunostaining in OE-E6/E7. RT-PCR was also used to show the existence of TLR3 gene in OE-E6/E7. To study the function of TLR3 in OE-E6/E7 cells, these cells were exposed to TLR3 specific ligand (poly I:C) and the levels of IL-1 and IL-6 released were measured in OE-E6/E7 culture media using ELISA. The effect of sex hormones on the function of TLR3 in OE-E6/E7 cells was investigated by treating these cells with poly I:C (25 microgram/ml for 24 hours) in the presence of different concentrations of estradiol and progesterone. Cells were divided into following groups; control (without any additional treatment of sex hormones), E1 (1nM/ml estradiol), E10 (10nM/ml estradiol), E1000 (1000nM/ml estradiol), P1 (1nM/ml progesterone), P10(10nM/ml progesterone), P100 (100nM/ml progesterone) and P1000 (1000nM/ml progesterone) respectively. Both immunohistochemistry and RT-PCR verified the existence of TLR3 in OE-E6/E7 cells. These cells did not produce any detectable amount of IL-1 in the presence or absence of TLR3 ligand. However, the production of IL-6 was significantly increased in the presence of poly (I:C). Although both sex hormones had a suppressive and biphasic effect on the production of IL-6 in the presence and absence of poly (I:C), when the ratio level of responses between control and test groups to Poly (I:C) in the presence of different concentrations of sex hormones was calculated, it was apparent that the presence of increasing levels of sex hormones enhanced TLR3 response to its specific ligand (poly (I:C)) in OE-E6/E7 cells. It seems sex hormones regulate the function of TLRs in the female reproductive tract during different stages of the female reproductive/menstrual cycle.