Smoking‐induced genetic and epigenetic alterations in infertile men

Male fertility rates have shown a progressive decrease in both developing and industrialised countries in the past 50 years. Clinical and epidemiological studies have demonstrated controversial results about the harmful effects of cigarette smoking on seminal parameters. Some studies could not establish a negative effect by tobacco smoking on sperm quality and function, whereas others have found a significant reduction in sperm quality and function. This study reviews the components in cigarette smoke and discusses the effects of smoking on male fertility by focusing extensively on smoking‐induced genetic and epigenetic alterations in infertile men. Chromosomal aneuploidies, sperm DNA fragmentation and gene mutations are discussed in the first section, while changes in DNA methylation, chromatin remodelling and noncoding RNAs are discussed in the second section as part of epigenetic alterations

Sperm DNA fragmentation: A new guideline for clinicians

Sperm DNA integrity is crucial for fertilization and development of healthy offspring. The spermatozoon undergoes extensive molecular remodeling of its nucleus during later phases of spermatogenesis, which imparts compaction and protects the genetic content. Testicular (defective maturation and abortive apoptosis) and post-testicular (oxidative stress) mechanisms are implicated in the etiology of sperm DNA fragmentation (SDF), which affects both natural and assisted reproduction. Several clinical and environmental factors are known to negatively impact sperm DNA integrity. An increasing number of reports emphasizes the direct relationship between sperm DNA damage and male infertility. Currently, several assays are available to assess sperm DNA damage, however, routine assessment of SDF in clinical practice is not recommended by professional organizations

Pro-inflammatory cytokines and microRNAs in male infertility

Background: Male infertility is a problem that affects 10–15% of men of reproductive age. In particular, gametogenesis is a complex process in which inflammation may play a central role through the secretion of cytokines and the expression of microRNAs. We assessed the potential role of proinflammatory cytokines (TNF-α, IL-6 and IL-1α) and microRNAs (miR-146a-5p, miR-34a-5p and miR-23a-3p) in the seminal plasma of infertile men compared to controls, evaluating their correlation with seminal and biochemical parameters. Methods and results: Expression of cytokines and microRNAs was analyzed by ELISA and q-PCR. Our data shows that IL-1α was significantly increased in the azoospermic group compared to controls, TNF-α mRNA was more expressed in the oligozoospermic group than controls. There were no significant differences in miRNAs expression among the three groups. The correlations between sperm parameters and inflammatory markers were evaluated, however no significance was highlighted. Conclusions: The determination of each inflammatory marker separately in the seminal plasma of subfertile men, despite some significant differences, does not have a diagnostic value in male infertility even if an assay of selective pro-inflammatory cytokines and microRNAs in the semen may improve the diagnosis of male infertility