| Purpose: To determine whether seminal B7-H3levels are correlated to semenparameters and affects human sperm functions.Methods: This study consists of three parts.1. Total83healthy donors of proven fertility (22-37years of age) and176infertilemen (21-38years of age) were recruited. Computer-assisted semen analysis (CASA) andenzyme-linked immunosorbent assay were used to assess the correlations between seminalB7-H3levels and semen parameters.2. Flow cytometry and fluorescence microscopy were employed to detect the putativereceptor for B7-H3and its distribution.3. CASA and FITC-conjugated pisum sativum agglutinin staining were performed forassessing sperm motility, capacitation, and acrosome reaction (AR) after incubation withvarious concentrations of B7-H3for0-4h in vitro，and observe the effects of B7-H3onsperm functions in humans.Results:1. Serum B7-H3levels in the healthy donors and infertile men were determined as4.53±1.12and4.49±1.92ng/ml, respectively, with no significant differences between thetwo groups (P=0.962). However, B7-H3in seminal plasma was significantly higher in thehealthy donors (16.67±7.71ng/ml) than that in the infertile men (7.79±4.27ng/ml,P<0.0001).We further analyzed the relationship between B7-H3and semen parameters forall samples. B7-H3was significantly higher in samples with normal PR values(11.53±6.36ng/ml) than others(5.52±3.39ng/ml)(P<0.0001). Furthermore, B7-H3was positivelycorrelated with curvilinear velocity (VCL)(r=0.394, P=0.011), straight-line velocity (VSL)(r=0.542, P=0.002), and average path velocity (VAP)(r=0.498, P=0.003). Samples withnormal sperm concentrations had a relatively higher level of B7-H3(10.72±6.44ng/ml)than that of the abnormal samples (6.18±4.03ng/ml; P=0.0007). 2. To determine whether seminal B7-H3regulates sperm quality in a paracrinemanner, we examined whether a putative receptor is expressed in human sperm. A putativereceptor for B7-H3was detectable on sperm surface from both the healthy donors andinfertile subjects. No significant differences were noted in the percentages of B7-H3receptor expression among the five groups (P=0.976). The B7-H3putative receptor wasdetected mainly in the postacrosomal, neck and middle regions of sperm.3. Sperm were incubated with various concentrations of B7-H3(0,5,10,25ng/ml) ina CO2incubator for4h. Progressive motility was evaluated via CASA analysis at differenttime-points. After2h of incubation, the percentage of sperm motility inasthenozoospermia samples treated with10ng/ml B7-H3increased to33.45±6.91%,which was significantly higher than that at0h (26.05±5.39%)(P=0.008). After4hincubation, the percentage of sperm motility in the healthy donors treated with5ng/mlB7-H3varied from70.35±11.71%to70.71±11.41%(P=0.872), whereas that inasthenozoospermia samples treated with5ng/ml B7-H3was significantly increased (from26.05±5.39%to30.55±3.97%)(P=0.031). Similarly, after incubation with10ng/mlB7-H3for4h, sperm motility in asthenozoospermia was significantly increased to45.76±8.72%(P=0.001). In the healthy donors, sperm motility increased to75.46±8.77%, butthis difference was not significant (P=0.087). Sperm motility in the10ng/mlB7-H3-treated asthenozoospermia group was significantly higher than that in the grouptreated with5ng/ml (P=0.011), indicating that B7-H3promotes sperm motility in a time-and dose-dependent manner. However, the differences between asthenozoospermiasamples treated with10ng/ml and25ng/ml B7-H3were not statistically significant(P=0.897;).While having no significant influence on sperm capacitation and AR.Conclusions: B7-H3showed a favorable effect on human sperm motility, withoutaffecting sperm capacitation and AR. |
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