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

Abstract

Purpose This 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. Methods Semen 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 (20 ≤ ROS < 40), group 3 (n = 31): moderate (40 ≤ ROS < 60), and group 4 (n = 43): high (ROS ≥ 60). 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).

Efficacy of Antioxidant Supplementation on Conventional and Advanced Sperm Function Tests in Patients with Idiopathic Male Infertility

“…Oxidative stress has been implicated in the pathophysiology of male infertility and the associated increase in free radicals, inducing sperm dysfunction and high SDF [12]. Moreover, imbalance in the levels of ROS and antioxidant enzymes coupled with increased peroxidative damage to sperm plasma membrane and DNA have been frequently reported in male infertility of unknown origin [4,[32][33][34]. In this context, antioxidant supplementation has been recommended as one of the treatment choices for men with idiopathic infertility [4,13].…”

Molecular Biology of Spermatogenesis: Novel Targets of Apparently Idiopathic Male Infertility

“…The exposure to pro-oxidant factors can concomitantly damage both sperm DNA integrity and gene expression by inducing epigenetic modifications. Accordingly, ROS have been found capable of altering H19-Igf2 methylation (by reducing H19 and increasing Igf2 methylation pattern) [32]. Moreover, abnormal methylation of the imprinted genes IGF2 and KCNQ1 at the spermatozoon level has recently been reported in infertile patients, in association with an increased sperm DNA fragmentation [33].…”

A Comparison Between Two Assays for Measuring Seminal Oxidative Stress and their Relationship with Sperm DNA Fragmentation and Semen Parameters

“…Importantly, sperm DNA is exquisitely sensitive to oxidative attack, resulting in impairment of embryo development, increased risk of gene mutations and miscarriage, congenital malformations and a high frequency of diseases in the offspring [3,5,8,11,19,21,22]. A serious consequence of OS is that it interferes with epigenetic modification and there are reports of abnormalities in sperm gene methylation as a direct result of oxidative insult [23,24,25]. There is good evidence to link unexplained infertility and recurrent pregnancy loss with both oxidative stress and sperm DNA fragmentation which are significantly elevated in infertile men [26,27,28,29] and in men whose partners experience miscarriage [11,30,31].…”