Relationships between metabolic status, seminal adipokines, and reproductive functions in men from infertile couples.

Adipokines could be a link between metabolic syndrome (MS) and infertility. While the association between circulating adipokines and fertility has been extensively studied in females, this relationship in males was less investigated, although some adipokines are detectable in seminal plasma (SP). The aim of this study was to determine adipokine levels in blood and SP and to assess the relationships between adipokines, MS and semen parameters in men from infertile couples. Male partners of infertile couples referred to four medical French centers were enrolled in years 2013-2016. Subjects (n = 160) aged 18-45 years were assessed for anthropometric, biochemical, sperm, and circulating hormonal parameters. Leptin, adiponectin, resistin, chemerin, visfatin, and IL-6 were measured in serum and SP. Infertility duration was higher in men with than without MS. Adipokine concentrations were higher in blood than in SP, except for IL-6 and visfatin. The most striking result was the significant correlation observed between seminal IL-6 and spermatozoid concentration, progressive motility, and sperm vitality. Moreover, while men with MS exhibited an expected lower adiponectinemia, they displayed 2.1-fold higher adiponectin levels in SP than men without MS. Finally, logistic regression analysis showed that BMI, infertility duration, and adiponectin serum/SP ratio were independently associated with MS. These results suggest an involvement of seminal adipokines to modulate fertility in men with MS and that seminal IL-6 could play a beneficial role on sperm functionality. Further mechanistic studies are necessary to investigate the precise roles of these adipokines in male reproduction.