Case Control Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Methodol. Jun 26, 2016; 6(2): 163-170
Published online Jun 26, 2016. doi: 10.5662/wjm.v6.i2.163
Mild oxidative stress is beneficial for sperm telomere length maintenance
Swetasmita Mishra, Rajeev Kumar, Neena Malhotra, Neeta Singh, Rima Dada
Swetasmita Mishra, Rima Dada, Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India
Rajeev Kumar, Department of Urology, All India Institute of Medical Sciences, New Delhi 110029, India
Neena Malhotra, Neeta Singh, Department of Obstetrics and Gynaecology, All India Institute of Medical Sciences, New Delhi 110029, India
Author contributions: Mishra S carried out all the experiments, did data analysis and manuscript writing; Kumar R contributed to referring infertility patients from the Urology OPD, concept designing and manuscript writing; Malhotra N contributed to referring infertility patients from the Obstetrics and Gynaecology OPD and manuscript writing; Singh N contributed to referring infertility patients from the Obstetrics and Gynaecology OPD and manuscript writing; Dada R contributed to concept designing, data analysis and manuscript writing.
Supported by Department of Biotechnology (DBT), Government of India, No. 1369.
Institutional review board statement: This study was approved by the Ethics Committee Room of All India Institute of Medical Sciences, New Delhi, India.
Informed consent statement: All patients gave informed consent.
Conflict-of-interest statement: None of the authors have any conflict of interest.
Data sharing statement: No additional data available for this manuscript.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Rima Dada, MD, PhD, Professor, Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India. rima_dada@rediffmail.com
Telephone: +91-011-26546716 Fax: +91-011-26588663
Received: June 17, 2015
Peer-review started: June 18, 2015
First decision: September 23, 2015
Revised: March 16, 2016
Accepted: March 22, 2016
Article in press: March 23, 2016
Published online: June 26, 2016
Processing time: 372 Days and 17.4 Hours
Abstract

AIM: To evaluate telomere length in sperm DNA and its correlation with oxidative stress (normal, mild, severe).

METHODS: The study included infertile men (n = 112) and age matched fertile controls (n = 102). The average telomere length from the sperm DNA was measured using a quantitative real time PCR based assay. Seminal reactive oxygen species (ROS) and 8-Isoprostane (8-IP) levels were measured by chemiluminescence assay and ELISA respectively.

RESULTS: Average sperm telomere length in infertile men and controls was 0.609 ± 0.15 and 0.789 ± 0.060, respectively (P < 0.0001). Seminal ROS levels in infertile was higher [66.61 ± 28.32 relative light units (RLU)/s/million sperm] than in controls (14.04 ± 10.67 RLU/s/million sperm) (P < 0.0001). The 8-IP level in infertile men was significantly higher (421.55 ± 131.29 pg/mL) than in controls (275.94 ± 48.13 pg/mL) (P < 0.001). When correlated to oxidative stress, in normal range of oxidative stress (ROS, 0-21.3 RLU/s/million sperm) the average telomere length in cases was 0.663 ± 0.14, in mild oxidative stress (ROS, 21.3-35 RLU/s/million sperm) it was elevated (0.684 ± 0.12) and in severe oxidative stress (ROS > 35 RLU/s/million sperm) average telomere length was decreased to 0.595 ± 0.15.

CONCLUSION: Mild oxidative stress results in lengthening of telomere length, but severe oxidative stress results in shorter telomeres. Although telomere maintenance is a complex trait, the study shows that mild oxidative stress is beneficial in telomere length maintenance and thus a delicate balance needs to be established to maximize the beneficial effects of free radicals and prevent harmful effects of supra physiological levels. Detailed molecular evaluation of telomere structure, its correlation with oxidative stress would aid in elucidating the cause of accelerated telomere length attrition.

Keywords: Telomere; Oxidative stress; Reactive oxygen species; Infertility; 8-Isoprostane

Core tip: In the present study we found that infertile men experienced oxidative stress evident from increased seminal reactive oxygen species and 8-Isoprostane levels. Infertile men also had shorter telomeres as compared to the controls. Severe oxidative stress negatively affected sperm telomere length but surprisingly mild oxidative stress resulted in lengthening of telomere and thus may aid in maintaining genomic integrity. To the best of our knowledge we are the first to report positive effect of mild oxidative stress on sperm telomere length.