Correlation between sperm DNA fragmentation and methylation in male partners of couples with idiopathic recurrent pregnancy loss

Abstract

With ∼50% recurrent pregnancy loss cases being termed idiopathic (iRPL), understanding of contribution of male factors to iRPL is still lacking. Higher prevalence of sperm DNA fragmentation index (DFI) and lower sperm 5-methylcytosine (5-mC) levels have been previously reported in male partners of iRPL couples and shed light on importance of the male gamete in maintenance of a successful pregnancy. The present study aimed to determine the serum sex steroid hormone levels, sperm DFI and 5-mC and correlation between them in male partners of fertile and iRPL couples. Further, correlation between sperm DFI and 5-mC with semen parameters and paternal age in both groups were determined. 36 male partners of fertile couples and 45 male partners of women experiencing iRPL were enrolled for this study and semen and blood samples were collected. Serum testosterone and estradiol levels were measured by ELISA; sperm DFI and global 5-mC were determined by TUNEL assay and ELISA respectively. Significantly higher serum testosterone levels were noted in the iRPL group (p = 0.028). Incidence of sperm DNA fragmentation was found to be higher in the iRPL study group but with no significance difference. No significant differences in sperm 5-mC values were noted. Upon correlation analysis within both groups, strong significant negative correlation of sperm DFI % and 5-mC % was observed in the control group (p < 0.001) but not the iRPL group (p = 0.249). Hence, we infer that with lower 5-mC levels in sperm genome, there is a higher incidence of sperm DFI in fertile men. However, this trend is not noted in men of iRPL group which could possibly be due to other underlying epigenetic alterations in genomic regions probably unsusceptible to fragmentation. On the other hand, no significant correlations of semen parameters, testosterone, estradiol and paternal age with sperm DFI and 5-mC were noted in both groups.

Keywords:

• Data correlations
• DNA fragmentation
• DNA methylation
• idiopathic recurrent pregnancy loss
• sex steroid hormone

Ethics approval

Ethical approvals were obtained from the respective institutions: (a) ICMR-National Institute for Research in Reproductive and Child Health (ICMR-NIRRCH), Parel, Mumbai (Ref: D/ICEC/Sci-60/64/2018); (b) Nowrosjee Wadia Maternity Hospital (NWMH), Parel, Mumbai (Ref: IEC/NWMH/01/2019). Written consent was obtained from each study participant after full explanation of the purpose and nature of all procedures used.

Acknowledgments

We thank all the study participants for their enrollment and cooperation. We are grateful for the assistance of Deepshikha Arya, Sunita Kharat, Sharmila Kamat and Tejashree Sontakke in participant recruitment. We also thank Suryakant Mandavkar, Shobha Sonawane, Reshma Goankar, Swati Jadhav, Uma Shinde, Deepak Shelar for their assistance in sample collection. We thank Leena Tendulkar for her aid in staining for sperm morphology studies. Delna Irani thanks Lady Tata Memorial Trust for her research fellowship.

Disclosure statement

The authors declare no conflict of interest.

Authors’ contributions

Conceptualized study: DS, DI; participant enrollment: VB, DT, AP, DI; methodology design: DI, DS, NB; experiments and data analysis: DI; project administration and funding acquisition: DS; original draft: DI; reviewed and edited: DS.

Data availability statement

Data will be made available upon reasonable request.

Additional information

Funding

This work was supported by Indian Council of Medical Research, RA/1334/10-2022 – Core funding.