Impact of Cigarette Smoking on the Expression of Oxidative Stress-Related Genes in Cumulus Cells Retrieved from Healthy Women Undergoing IVF

Abstract

The female reproductive system represents a sensitive target of the harmful effects of cigarette smoke, with folliculogenesis as one of the ovarian processes most affected by this exposure. The aim of this study was to analyze the impact of tobacco smoking on expression of oxidative stress-related genes in cumulus cells (CCs) from smoking and non-smoking women undergoing IVF techniques. Real time PCR technology was used to analyze the gene expression profile of 88 oxidative stress genes enclosed in a 96-well plate array. Statistical significance was assessed by one-way ANOVA. The biological functions and networks/pathways of modulated genes were evidenced by ingenuity pathway analysis software. Promoter methylation analysis was performed by pyrosequencing. Our results showed a down-regulation of 24 genes and an up-regulation of 2 genes (IL6 and SOD2, respectively) involved in defense against oxidative damage, cell cycle regulation, as well as inflammation in CCs from smoking women. IL-6 lower promoter methylation was found in CCs of the smokers group. In conclusion, the disclosed overall downregulation suggests an oxidant-antioxidant imbalance in CCs triggered by cigarette smoking exposure. This evidence adds a piece to the puzzle of the molecular basis of female reproduction and could help underlay the importance of antioxidant treatments for smoking women undergoing IVF protocols.

A Systematic Review of the Effects of High-Fat Diet Exposure on Oocyte and Follicular Quality: A Molecular Point of View

“…A fatty-acid-enriched diet increases the levels of the different hormones, such as FSH and LH, involved in the hypothalamic–pituitary–adrenal (HPA) axis, but also the concentration of ROS produced in the ovary and all stages of follicular growth, contributing to manifestation of oxidative stress. The relationship between oxidative stress and reproductive performance has been thoroughly studied [ 10 , 21 , 22 ], underlining that severe oxidative stress can concretely compromise follicular and ovarian development [ 37 ], and as a consequence, a balance of free radicals in the ovary is of vital importance. It has been demonstrated that due to high lipid levels, following ROS-induced lipid peroxidation in the ovaries of obese women, consequent oocyte apoptosis could be a contributing factor to significant follicular damage [ 38 ], negatively affecting ovarian function and female reproductive potential [ 32 ].…”

“…Granulosa cells not only provide various energetic substrates necessary for the nourishment of the oocyte, but also have a fundamental role in the formation of corpus luteum (CL), making them indispensable for the quality of the oocyte and embryo [ 8 ]. There are many factors related to the individual’s lifestyle that are able to negatively affect female fertility, such as high consumption of caffeine and alcohol, competitive sports, stress, cigarette smoking, chronic exposure to environmental pollutants and improper eating habits [ 10 , 11 , 12 , 13 ]. There is accumulating evidence that non-modifiable risk factors, such as genetic mechanisms and old age, are involved in the onset of infertility [see 1 for an extensive review].…”

The Aftermath of Long-Term Cigarette Smoking on Telomere Length and Mitochondrial DNA Copy Number in Human Cumulus Cells Prior to In Vitro Fertilization—A Pilot Study

“…Smoking in women of reproductive age is known to severely impact the ovaries and reproductive cells such as oocytes [ 6 ] and CCs [ 10 ] and potentially carry a risk for premature menopause, premature birth, abnormal fetal growth, low birth weight, and miscarriage [ 17 ]. As we previously described [ 10 ], several differentially expressed key genes related primarily to OS were identified in CCs following chronic exposure to cigarette smoke, suggesting a lower antioxidant capacity in CCs of smoking versus non-smoking women.…”

“…The procedure used for the CCs isolation from COCs is the same as previously described in our study [ 10 ]. Briefly, the removal of CCs from COCs was aided with the exposure of COCs to hyaluronidase solution (HYASE-10XTM, Vitrolife, Goteborg, Sweden).…”

“…The paracrine interactions between the oocyte and surrounding granulosa cells are critical for optimal oocyte quality and embryonic development during folliculogenesis, making them vital for its correct growth and development [ 8 ]. More specifically, exposure to the harmful chemicals in cigarettes may overall contribute to subfertility and premature ovarian failure [ 9 ] as well as induce alterations in luteal steroidogenesis; follicular loss and apoptosis; oxidative stress (OS) and related gene expression [ 10 ]; autophagy; and irreparable damage to the telomeres, mitochondrial DNA (mtDNA), and mtDNA copy number (mtDNA-CN) [ 11 ].…”