Adverse effects of paternal obesity on the motile spermatozoa quality

PLoS One. 2019 Feb 11;14(2):e0211837. doi: 10.1371/journal.pone.0211837. eCollection 2019.

Abstract

Growing evidence suggests that paternal obesity may decrease male fertility potential. During infertility treatment with intra-cytoplasmic sperm injection (ICSI), a morphologically normal motile spermatozoon is injected into a mature egg, when possible. However, sperm motility and morphology per se do not reflect the sperm molecular composition. In this study, we aimed to assess the quality of motile spermatozoa in the context of obesity by analysing their conventional and molecular characteristics as well as their ability to promote early embryonic development. A prospective study was conducted on 128 infertile men divided into three groups: 40 lean, 42 overweight, and 46 obese men. Conventional sperm parameters (concentration, motility and morphology) and sperm molecular status (chromatin composition and integrity, 5-methycytosine (5-mC) and 5-hydroxycytosine (5-hmC) contents and oxidative stress level) were analysed on raw semen and/or on motile spermatozoa selected by density gradient or swim-up techniques. Morphokinetic analysis of the embryos derived from ICSI was performed using the Embryoviewer software. Our results showed that the motile sperm-enriched fraction from obese men exhibited higher levels of retained histones (p<0.001), elevated percentage of altered chromatin integrity (p<0.001), and decreased contents of 5-hmC (p<0.001), and 5-mC (p<0.05) levels as compared to that from lean men. Importantly, there were no statistically significant correlations between these molecular parameters and the percentages of morphologically normal motile spermatozoa. Regarding embryo morphokinetics, the CC1 (p<0.05) and CC3 (p<0.05) embryonic cell cycles were significantly delayed in the cleavage embryos of the obese group as compared to the embryos of the lean group. Our data is of particular interest because, besides demonstrating the negative impacts of obesity on motile spermatozoa molecular composition, it also highlights the possible risk of disturbing early embryonic cell cycles kinetics in the context of paternal obesity.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Chromatin* / metabolism
  • Chromatin* / pathology
  • Embryo, Mammalian
  • Embryonic Development
  • Female
  • Humans
  • Infertility, Male / metabolism
  • Infertility, Male / pathology
  • Male
  • Middle Aged
  • Obesity* / metabolism
  • Obesity* / pathology
  • Prospective Studies
  • Sperm Injections, Intracytoplasmic
  • Sperm Motility*
  • Spermatozoa* / metabolism
  • Spermatozoa* / pathology

Substances

  • Chromatin

Grants and funding

This study was funded by the Agence Nationale de la Recherche” (ANR-12-ADAPT-0022) and the conseil national de la recherche scientifique Liban (CNRS-L). G.R. was supported by a fellowship from CNRS-L. Azoury IVF clinic provided support in the form of salaries for authors JA, KR, and JA. The specific roles of these authors are articulated in the 'author contributions' section.