Reactive oxygen species-induced alterations in H19-Igf2 methylation patterns, seminal plasma metabolites, and semen quality

PurposeThis study was conducted in order to investigate the effects of reactive oxygen species (ROS) levels on the seminal plasma (SP) metabolite milieu and sperm dysfunction.MethodsSemen specimens of 151 normozoospermic men were analyzed for ROS by chemiluminescence and classified according to seminal ROS levels [in relative light units (RLU)/s/10(6) sperm]: group 1 (n=39): low (ROS<20), group 2 (n=38): mild (20ROS<40), group 3 (n=31): moderate (40ROS<60), and group 4 (n=43): high (ROS60). A comprehensive analysis of SP and semen parameters, including conventional semen characteristics, measurement of total antioxidant capacity (TAC), sperm DNA fragmentation index (DFI), chromatin maturation index (CMI), H19-Igf2 methylation status, and untargeted seminal metabolic profiling using nuclear magnetic resonance spectroscopy (1H-NMR), was carried out.Result(s)The methylation status of H19 and Igf2 was significantly different in specimens with high ROS (P<0.005). Metabolic fingerprinting of these SP samples showed upregulation of trimethylamine N-oxide (P<0.001) and downregulations of tryptophan (P<0.05) and tyrosine/tyrosol (P<0.01). High ROS significantly reduced total sperm motility (P<0.05), sperm concentration (P<0.001), and seminal TAC (P<0.001) but increased CMI and DFI (P<0.005). ROS levels have a positive correlation with Igf2 methylation (r=0.19, P<0.05), DFI (r=0.40, P<0.001), CMI (r=0.39, P<0.001), and trimethylamine N-oxide (r=0.45, P<0.05) and a negative correlation with H19 methylation (r=-0.20, P<0.05), tryptophan (r=-0.45, P<0.05), sperm motility (r=-0.20, P<0.05), sperm viability (r=-0.23, P<0.01), and sperm concentration (r=-0.30, P<0.001).Conclusion(s)Results showed significant correlation between ROS levels and H19-Igf2 gene methylation as well as semen parameters. These findings are critical to identify idiopathic male infertility and its management through assisted reproduction technology (ART).