Localization of Toll-Like Receptors on Epididymal Epithelial Cells and Spermatozoa

Toll-like receptors (TLRs) are a family of innate immunity receptors that are essential for detecting invading pathogens. Objectives of this study were to identify epididymal cell types expressing TLRs and to determine if TLRs are present on spermatozoa. Immunohistochemical analysis of paraffin-embedded sections from regions of the rat epididymis was used to identify epididymal cell types expressing TLRs. Immunoblot analysis and immunofluorescence were used to detect TLRs on spermatozoa. TLRs 1-9 and 11 are abundantly expressed by the epididymal epithelium in most regions of the duct with the exception of clear cells of the cauda which do not express TLRs 5-7 or 11. TLRs were detected on epididymal spermatozoa and several TLRs showed regional distributions patterns suggesting modification during epididymal transit. The abundance of TLR family members in the epididymal epithelium and on spermatozoa provides strong evidence that TLRs play important roles in innate immunity of the male reproductive tract.