Decreased autophagic activity in spermatozoa from infertile men adversely affects early embryonic development

Oligoasthenoteratozoospermia (OAT) is a complex reproductive health problem characterized by impaired sperm parameters. Autophagy serves critical functions in diverse stages of male reproduction and has been shown to be functionally active in mature ejaculate spermatozoa from healthy men. The present study aims to investigate the level of autophagic activity in spermatozoa from OAT patients and its association with embryo development following intracytoplasmic sperm injection (ICSI). 42 OAT men with healthy spouses and 21 age-matched fertile controls were included in the study. Following semen analysis, semen samples were processed for sperm protein isolation and protein concentrations were measured by BCA assay. Autophagic activity levels in spermatozoa, i.e. LC3 conversion, p62 and Beclin-1 protein levels, were measured by Western blotting. In vitro fertilization was performed by routine ICSI. Fertilization and embryo development rates were calculated accordingly. Spermatozoal autophagic activity was significantly decreased in OAT patients compared to fertile controls, as demonstrated by concurrently decreased LC3-II and increased p62 protein levels. Beclin-1 levels did not significantly change between the two groups. Evaluation of p62 correlation and LC3-II regression analyses with ICSI success rates revealed that low spermatozoal autophagic activity is significantly associated with a decline in day 3 embryo development. Our findings reveal an adverse late paternal effect on early embryonic development, which suggests an involvement of sperm DNA damage as a consequence of decreased sperm autophagy. Understanding the interplay between sperm autophagy and embryo quality will help develop novel therapeutic strategies to increase sperm autophagic activity in OAT patients in the future.