Sperm Antioxidant Capacity Discriminates Between Fertile and Infertile Men and Is Strictly Related to Lipid Peroxidation and Lipid Mediator Production

Oxidative stress (OS) and inflammation are common causes of male infertility; antioxidants in spermatozoa and especially in seminal plasma play a protective role. The study aims to evaluate whether OS lipid mediators (F2-isoprostanes: F2-IsoPs; Resolvin D1: RvD1) measured in seminal plasma, and Trolox equivalent antioxidant capacity (TEAC), measured in both seminal plasma and spermatozoa, are associated with male infertility. Semen samples (18 fertile and 62 infertile subjects) were examined following WHO guidelines and with a mathematically elaborated transmission electron microscopy analysis (fertility index-FI-, % sperm pathologies). F2-Isops were measured by GC/NICI-MS/MS, RvD1 by ELISA, and TEAC by a commercially available antioxidant assay. F2-Isops, RvD1, and sperm TEAC (positively interrelated with each other) correlated negatively with seminal parameters and FI and positively with sperm pathologies. F2-Isops, RvD1, and sperm TEAC levels were significantly higher in infertile vs fertile subjects (p < 0.001). ROC curve analysis demonstrated that sperm TEAC (J index: 0.13 mM) and seminal RvD1 (J index: 38.26 pg/mL) discriminated between fertile and infertile subjects. Spermatozoa stimulate antioxidant capacity in the presence of an OS environment; this data suggests an association in which antioxidant defences may vary in relation to the surrounding seminal plasma. Moreover, sperm TEAC, and to a lesser extent seminal RvD1, emerge as potential markers for identifying infertile patients.