P-17: Expression of Cell Surface Toll-Like Receptors in the Human Male Reproductive Tract

Background: Male infertility refers to the inability of a male to achieve a pregnancy in a fertile female. The root of many causes of infertility is miscommunication between immune and reproductive system. Male reproductive system is very sensitive and vulnerable, infections can hinder maturation and movement of spermatozoa lead to impaired fertility.All species need an immediate reply to the microbial pathogens that is part of an effective immune response. This reply is known as the innate immune response. The innate immune system uses a series of pattern recognition receptors to detect the presence of pathogens. A key component of such phenomena receptors are Toll-like receptors (TLRs). TLRs are a family of receptors that recognize different pathogen-associated molecular patterns (PAMPs) present in pathogens. To date, 10 functional members of TLRs have been discovered in human. Among them TLR1, TLR2, TLR4, TLR5, TLR6 and TLR10 are expressed on the cell surface while others are expressed in cytoplasmic organelles, mainly the endosomes. Cell surface TLRs mostly identified bacterial and fungal infections. TLR2 and its associated receptors TLR1, TLR6 and TLR10 are mainly involved in the detection of molecules from Gram-positive bacteria. However, TLR4 and TLR5 recognize mainly gram-negative bacterials. TLR4 is a receptor for bacterial LPS and chlamydial heat shock proteins. While, TLR5 can recognize flagellin of bacterial and fungi. Considering to the important roles of innate immunity in reproductive health, the objective in this study is detecting cell surface TLRs expression in the human male reproductive tract and spermatozoa. Materials and Methods: Tissues were obtained from men who underwent TESE, Vasectomy, Prostatectomy for benign reasons and Prepuce surgery. All men taking part in this study had not history of infection and congenital disorder. RT-PCR was used to show the existence of cell surface TLR genes in the male reproductive tract, Q-PCR analysis used to investigate the relative expression of TLR2 and TLR4 genes and Immunoblot analysis was used for detect TLR2 and TLR4 on spermatozoa. Results: All cell surface TLR mRNAs were expressed in all regions of the human male reproductive tract. Q-PCR has shown relative TLR2 expression in TESE (-) patient is lower than TESE (+) patient while there was no difference between TLR4 expression in TESE (+) compared to TESE (-). Existence of TLR2 and 4 in spermatozoa has been shown by using immunoblot. Conclusion: Because, cell surface TLRs mostly identified bacterial and fungal infections, the expression of cell surface TLR mRNAs in the human male reproductive tract and TLR2 and TLR4 expression on spermatozoa provides strong evidence that they play important roles in innate immunity of the male reproductive tract. Also TLR2 expression in testis is affected by the presence of spermatozoa while spermatogenesis have no effect on TLR4 expression in testis.