Dysregulated serum and seminal plasma levels of surfactant protein D and MCP-1 in men with genital tract infection/inflammation

Problem Surfactant protein D (SP-D), a multimeric collectin expressed by testicular mucosal epithelia and is positively regulated by testosterone. It exerts antimicrobial effects, modulates inflammation and rescued spermatogenesis in a murine model. Various cytokines and chemokines, including MCP-1, play a key role in regulating the inflammation in rat and human testis. The study aimed to investigate the role of SP-D and involvement of chemokines and cytokines in the male infertility associated with urogenital infections or inflammation. Method of study The cross-sectional study evaluated levels of SP-D, testosterone, estradiol and the cytokines/chemokines including MCP-1 in the serum and semen samples of fertile and infertile Indian men with and without urogenital infections/inflammation (n = 76). Results Both fertile and infertile males with urogenital infection/inflammation had significantly lower levels of SP-D and higher levels of the chemokine, Monocyte chemoattractant protein 1 (MCP-1) in the serum and seminal plasma. Seminal plasma of these males exhibited significantly higher proportion of proteolytically degraded forms of SP-D. The serum SP-D levels positively correlated with testosterone/estradiol (TE) ratio. There was no significant correlation between the SP-D levels in seminal plasma and sperm count/motility. With a significant area under the Receiver Operating Characteristic curves, the serum and seminal plasma SP-D levels exhibited significant potential to predict infertility with high sensitivity and specificity in men with genital infections/inflammation. Conclusions The circulating and seminal plasma SP-D levels were decreased in men with urogenital infection and inflammation. This could be due to their engagement at the site of infection, dysregulated expression owing to the altered hormonal profile and increased proteolytic degradation.