精子线粒体膜电位作为综合评估男性生育能力指标的初探

Preliminary exploration on sperm mitochondrial membrane potential as a comprehensive evaluation of male fertility

目的本研究旨在探讨精子线粒体膜电位(MMP)与精液常规、精子形态学以及精子DNA碎片指数(DFI)之间的关联,以及MMP对于临床评估和预测男性生育能力的价值。方法选择2023年4—7月于江苏省中医院男科进行孕前优生检查、生育咨询以及不育症治疗的患者的精液标本为研究对象,按照世界卫生组织(WHO)第5版标准进行精液常规和精子形态学分析,并通过流式细胞术检测精子DFI和MMP。根据不同精液质量分为两组:精液质量各项指标均正常,即精液量>2 ml、pH值7.2~7.8、精子浓度≥15×106/ml,精子前向运动(PR)≥32%、精子形态正常率≥4%、DFI<30%为精液质量正常组(n=57);PR<32%、精子形态正常率<4%、DFI≥30%为精液质量异常组(n=67),比较两组精液质量各项参数;采用Spearman相关性分析,分析MMP与精子浓度、PR、精子形态正常率以及DFI之间的关系;绘制受试者工作特征曲线(ROC),分析MMP对于临床评估男性生育能力的价值。结果两组间平均年龄、精液量比较均无显著差异(P>0.05),精液质量正常组精子浓度、PR、精子形态正常率、MMP显著高于精液质量异常组(P<0.05),DFI显著低于精液质量异常组(P<0.05);Spearman相关性分析结果显示,MMP与精液量无明显相关性(r=-0.065,P=0.475),与精子浓度(r=0.396,P<0.001)、PR(r=0.471,P<0.001)、精子形态正常率(r=0.468,P<0.001)呈显著正相关,与DFI(r=-0.701,P<0.001)呈显著负相关;ROC分析结果显示,MMP对精液质量整体水平预测的ROC曲线下面积(AUC)为0.891,敏感度87.5%,特异性83.3%,截断值53.69%;MMP对精子浓度预测的AUC为0.787,敏感度82.0%,特异性69.2%,截断值43.97%;MMP对PR预测的AUC为0.741,敏感度65.7%,特异性84.2%,截断值56.33%;MMP对精子形态正常率预测的AUC为0.733,敏感度71.1%,特异性69.1%,截断值56.63%;MMP对DFI预测的AUC为0.809,敏感度89.5%,特异性72.1%,截断值54.78%。结论精子MMP与精子浓度、PR、精子形态正常率呈显著正相关,与DFI呈显著负相关。与各单项精液指标相比,MMP能更全面地反映精子能量代谢和凋亡,推荐将MMP 54%作为全面评估和预测男性生育能力的参考值下限。

Objective:To explore the association between sperm mitochondrial membrane potential(MMP)and semen parameters,sperm morphology,and sperm DNA fragmentation index(DFI),as well as the clinical value of MMP for evaluation and prediction of male fertility.Methods:The study focused on semen samples of male clients seeking for preconception health assessments,fertility counseling,and treatment of infertility at the Andrology Department of Jiangsu Provincial Hospital of Traditional Chinese Medicine from April 2023 to July 2023.The 5th edition WHO standards for routine semen analysis and sperm morphology was followed.Additionally,the sperm DFI and MMP were assessed with flow cytometry.Based on semen quality,participants were divided into two groups:the normal semen quality group(n=57)and the abnormal semen quality group(n=67).The former exhibited all parameters within normal ranges,namely semen volume>2 ml,pH 7.2-7.8,sperm concentration≥15×106/ml,progressive motility(PR)≥32%,normal sperm morphology rate≥4%,and DFI<30%.The latter demonstrated parameters below the normal thresholds:PR<32%,normal sperm morphology rate<4%,and DFI≥30%.Various parameters of semen quality between the two groups were compared.The Spearman rank correlation analysis was employed to examine the relationship between MMP and the sperm concentration,PR,the normal rate of sperm morphology,and DFI.The receiver operating characteristic(ROC)curves were generated to evaluate the clinical value of MMP in assessing male fertility.Results:There were no significant differences in the average age and semen volume between the two groups(P>0.05).In the normal semen quality group,sperm concentration,PR,normal sperm morphology rate,and MMP were significantly higher than those in the abnormal semen quality group,whereas DFI was significantly lower(P<0.05).The Spearman rank correlation analysis demonstrated that MMP had no correlation with semen volume(r=-0.065,P=0.475),while showed significant positive correlations with sperm concentration(r=0.396,P<0.001),PR(r=0.471,P<0.001),normal sperm morphology rate(r=0.468,P<0.001),and displayed a significant negative correlation with DFI(r=-0.701,P<0.001).The ROC analysis results indicated that for the prediction of overall semen quality,the area under the ROC curve(AUC)for MMP was 0.891,with the sensitivity of 87.5%,the specificity of 83.3%,and the MMP cutoff value was 53.69%.For predicting normal sperm concentration,the AUC was 0.787,with the sensitivity of 82.0%,the specificity of 69.2%,and the cutoff value was 43.97%.For the prediction of normal PR,the AUC was 0.741,with the sensitivity of 65.7%,the specificity of 84.2%,and the cutoff value was 56.33%.When predicting the normal sperm morphology rate,the AUC was 0.733,with the sensitivity of 71.1%,the specificity of 69.1%,and the cutoff value was 56.63%.Lastly,for predicting normal DFI,the AUC was 0.809,with the sensitivity of 89.5%,the specificity of 72.1%,and the cutoff value was 54.78%.Conclusions:Sperm MMP exhibits significant positive correlations with the sperm concentration,PR,and the normal sperm morphology rate,while showing a significant negative correlation with DFI.In comparison to other semen parameters,MMP provides a more comprehensive reflection of sperm energy metabolism and apoptosis.It is recommended to consider a threshold of 54%for MMP as the lower reference limit for the comprehensive assessment and prediction of male fertility.