Metabolomic profiling reveals correlations between spermiogram parameters and the metabolites present in human spermatozoa and seminal plasma

In 50% of all infertility cases, the male is subfertile or infertile, however, the underlying mechanisms are often unknown. Even when assisted reproductive procedures such as in vitro fertilization and intracytoplasmic sperm injection are performed, the causes of male factor infertility frequently remain elusive. Since the overall activity of cells is closely linked to their metabolic capacity, we analyzed a panel of 180 metabolites in human sperm and seminal plasma and elucidated their associations with spermiogram parameters. Therefore, metabolites from a group of 20 healthy donors were investigated using a targeted LC-MS/MS approach. The correlation analyses of the amino acids, biogenic amines, acylcarnitines, lysophosphatidylcholines, phosphatidylcholines, sphingomyelins and sugars from sperm and seminal plasma with standard spermiogram parameters revealed that metabolites in sperm are closely related to sperm motility, whereas those in seminal plasma are closely related to sperm concentration and morphology. This study provides essential insights into the metabolome of human sperm and seminal plasma and its associations with sperm functions. This metabolomics technique could be a promising screening tool to detect the factors of male infertility in cases where the cause of infertility is unclear.在所有不孕不育病例中，50%的案例由男性生育能力低下或不育导致，但其潜在致病机制往往尚不明确。即便采用体外受精（in vitro fertilization）、卵胞浆内单精子注射（intracytoplasmic sperm injection）等辅助生殖技术，男性因素不孕的病因仍时常难以明确。由于细胞的整体活性与其代谢能力密切相关，本研究对人类精子与精浆中的180种代谢物进行了靶向分析，并阐明了其与精液分析参数（spermiogram parameters）的关联。为此，本研究采用靶向液相色谱-串联质谱（liquid chromatography-tandem mass spectrometry, LC-MS/MS）技术，对20名健康供体的代谢物展开了检测。通过对精子与精浆中的氨基酸、生物胺、酰基肉碱、溶血磷脂酰胆碱、磷脂酰胆碱、鞘磷脂及糖类与标准精液分析参数进行相关性分析，结果显示：精子内的代谢物与精子活力密切相关，而精浆中的代谢物则与精子浓度及精子形态紧密关联。本研究为人类精子与精浆的代谢组（metabolome）及其与精子功能的关联提供了关键见解。该代谢组学技术有望成为不明病因不孕病例中男性不育相关因素的潜在筛查工具。