The free-radical theory of male infertility suggests that reactive oxygen species produced by the spermatozoa themselves are a leading cause of sperm dysfunction, including loss of sperm motility. However, the field is overshadowed on several fronts, primarily because: i) the probes used to measure reactive oxygen species (ROS) are imprecise; and ii) many reports suggesting that oxygen radicals are detrimental to sperm function add an exogenous source of ROS. Herein, a more reliable approach to measure superoxide anion production by human spermatozoa based on MS analysis is used. Furthermore, the formation of the lipid-peroxidation product 4-hydroxynonenal (4-HNE) during in vitro incubation using proteomics is also investigated. The data demonstrate that neither superoxide anion nor other free radicals that cause 4-HNE production are related to the loss of sperm motility during incubation. Interestingly, it appears that many of the 4-HNE adducted proteins, found within spermatozoa, originate from the prostate. A quantitative SWATH analysis demonstrate that these proteins transiently bind to sperm and are then shed during in vitro incubation. These proteomics-based findings propose a revised understanding of oxidative stress within the male reproductive tract.

中文翻译：

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质谱揭示了人类精子中超氧阴离子和4-羟基壬醛加成蛋白生产的新见解。

男性不育症的自由基理论表明，由精子自身产生的活性氧是导致精子功能障碍的主要原因，包括精子活力的丧失。然而，该领域在几个方面都被蒙上了阴影，这主要是因为：i）用于测量活性氧（ROS）的探针不精确；ii）许多报道表明氧自由基对精子功能有害，这增加了ROS的外源。在本文中，使用了基于MS分析来测量人精子产生超氧阴离子产生的更可靠的方法。此外，还研究了在使用蛋白质组学的体外温育过程中脂质过氧化产物4-羟基壬烯醛（4-HNE）的形成。数据表明，在孵化过程中，不会产生4-HNE的超氧阴离子或其他自由基都与精子活力的丧失无关。有趣的是，似乎在精子中发现的许多4-HNE加成蛋白都起源于前列腺。定量SWATH分析表明，这些蛋白质会瞬时结合到精子上，然后在体外孵育过程中脱落。这些基于蛋白质组学的发现提出了对男性生殖道内氧化应激的修订认识。