Gender differences in plasma growth arrest-specific protein 6 levels in adult subjects

Growth-arrest-specific 6 (Gas6) is recognized as a secreted vitamin K-dependent protein, as it interacts with receptor tyrosine kinases of the TAM (Tyro-3, Axl, Mer) family. The plasma Gas6 are important to the inflammatory process, and are involved in diverse human diseases. Few studies have shown plasma Gas6 concentration varies with genders. We determined whether plasma Gas6 concentrations are associated with sex hormones in both genders.

A total of 589 adult subjects, including 361 male and 228 female were recruited. Plasma Gas6 concentration, biochemical, testosterone, estradiol (E2), and sex hormone-binding globulin were assayed. The indices of free androgen (FAI) and free E2 (FEI) were calculated.

Significantly higher Gas6 concentrations were observed in adult male rather than female (P<0.05). In univariate regression analysis, plasma Gas6 concentrations were positively associated with FAI in male (β=0.167, P=0.002) and both E2 and FEI in female (β=0.384, P<0.001 andβ=0.292, P<0.001, respectively). Otherwise, Gas6 concentrations were inversely associated with ages in both genders (β=-0.234, P<0.001 in male and β=-0.226, P=0.001 in female, respectively). In multivariate regression analysis, only age in male and E2 in female were independent variables to determine the plasma Gas6 concentrations (β=-0.231, P=0.002 and β=0.458, P=0.001).

Plasma Gas6 is associated with sex hormones in female and ages in male, indicating a potential role of sex hormones and ages involving the Gas6/TAM system.