Expression of peroxiredoxins in the human testis, epididymis and spermatozoa and their role in preventing H2O2-induced damage to spermatozoa.

High levels of reactive oxygen species (ROS) have potential toxic effects on testicular function and sperm quality. Peroxiredoxins (PRDXs) are enzymes with a role as ROS scavenger. The aim of the study was to reveal the presence and localization of PRDXs in human testis, epididymis and spermatozoa, and the protective roles of PRDX2 and PRDX6 in sperm motility. The presence and localization of PRDXs in the human testis, epididymis and spermatozoa were detected by immunohistochemistry, western blot and immunofluorescence. The effect of anti-peroxidative damage to spermatozoa was examined by adding H2O2 to the recombinant protein-treated spermatozoa. There were strong signals of PRDX1 in spermatogonia and round spermatids; PRDX2 in the round spermatids; PRDX4 and 5 in spermatogonia; PRDX6 in Sertoli cells. PRDXs were also found in epididymal epithelial cells where the expression of PRDX1, 4, 5, 6 in the cauda was higher than in the caput of epididymis. PRDX1-6 immunoreactivity was found throughout acrosome, post-acrosomal region, equatorial segment, neck and cytoplasmic droplet, midpiece and principal piece. The H2O2-induced reduction in sperm motility was reversed by recombinant PRDX2 or PRDX6 in a dose-dependent manner. PRDX1-6 in the human testis and epididymis presented cell-specificity. PRDX2 and 6 are potential antioxidant protectors for human spermatozoa.