Serum chemerin levels are negatively associated with male fertility and reproductive hormones

STUDY QUESTION: Are chemerin levels different in subfertile men compared to men from the general population, and how does chemerin relate to reproductive hormonal status? SUMMARY ANSWER: Chemerin is negatively associated to LH, SHBG and estradiol and lower levels of chemerin are detected among subfertile men compared to controls. WHAT IS KNOWN ALREADY: Adipokines have pleiotropic effects on tissue homeostasis and have been shown to affect both sex steroid production and action. Among adipokines the newly characterized chemokine chemerin is suggested to influence testosterone production in males, but whether serum levels associate with testosterone or male subfertility has not yet been reported. STUDY DESIGN, SIZE, DURATION: Case control study comprising a consecutive group of men from infertile couples referred to Reproductive Medicine Centre at Skane University Hospital from 2006 through 2012, and age-matched controls. Participants were enrolled in years 2011-2013. PARTICIPANTS/MATERIALS, SETTING, METHODS: Males from infertile couples (n = 180) aged 18-50 years with sperm concentration <20 x 10(6)/ml and age-matched controls (n = 139) from the general population were enrolled. Serum concentrations of total testosterone (TT), calculated free testosterone (cFT), luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2) and sex-hormone binding globuline (SHBG) as well as the adipokines chemerin, adiponectin and leptin were measured. Anthropometrics and biochemical parameters of glucose and lipid metabolism were assessed. MAIN RESULTS AND THE ROLE OF CHANCE: Chemerin levels were lower in subfertile men compared to controls (mean diff. 7.1 ng/ml; 95% CI, 3.7; 11 ng/ml; P < 0.001) even after adjustment for BMI. After adjustment for age, BMI, smoking, leptin and adiponectin, chemerin associated negatively with LH (beta = -4.2; P = 0.02), E2 (beta = -10; P = 0.004) and SHBG (beta = -7.4, P = 0.003). Men with elevated LH levels had lower chemerin levels compared to those with LH levels within the normal range (mean diff. 4.8 ng/ml; 95% CI, 0.16; 9.4 ng/ml; P = 0.04). LIMITATIONS, REASONS FOR CAUTION: Single sample blood test with immunoassays for determination of hormone levels. Heterogeneous group of subfertile subjects. WIDER IMPLICATIONS OF THE FINDINGS: Even though chemerin has been positively associated with BMI, inverse association with subfertility suggests that it is independently linked to reproductive function, a hypothesis that warrants further assessment. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by grants from EU Interreg V (ReproUnion) program as well as Swedish Governmental Fund for Clinical Research. The authors have no conflicts of interest.