Oxidative stress is associated with telomere interaction impairment and chromatin condensation defects in spermatozoa of infertile males

Abstract

Telomere length can be influenced by reactive oxygen species (ROS) generated by lifestyle factors or environmental exposure. We sought to determine whether oxidative stress has an impact on sperm nuclear alterations, especially on chromatin organization and telomere interactions in the spermatozoa of infertile males. We performed an observational and prospective study including fifty-two males, allocated in the “case group” (30 infertile males presenting conventional semen parameter alterations) and the “control group” (22 males with normal conventional semen param-eters). ROS detection was determined on spermatozoa using CellROX© probes. Sperm nuclear damage was assessed using quantitative fluorescence in situ hybridization (Q-FISH) for relative telo-mere length and telomere number, aniline blue staining for chromatin condensation, terminal de-oxynucleotidyl transferase dUTP nick-end labeling for DNA fragmentation, and FISH for aneu-ploidy and 8-hydroxy-2′-deoxyguanosine immunostaining for oxidative DNA damages. Infertile males had significantly increased levels of cytoplasmic ROS and chromatin condensation defects as well as a higher mean number of telomere signals per spermatozoon in comparison with controls. In addition, the mean number of sperm telomere signals were positively correlated with the per-centage of spermatozoa with chromatin condensation defect. In infertile males with conventional semen parameter alterations, oxidative stress is associated with telomere interaction impairment and chromatin condensation defects.