Warr Sophie, Pini Taylor, de Graaf Simon P, Rickard Jessica P
Reproduction. 2025 Jul 4;170(2). doi: 10.1530/REP-24-0465. Print 2025 Aug 1.
Frozen-thawed ram spermatozoa show reduced fertility following cervical artificial insemination, likely attributed to an elevated immune response in the ewe. This paper identifies the immunoprotective effect of ram seminal plasma (SP) against polymorphonuclear neutrophil binding, highlighting potential for fertility improvement.
Following cervical artificial insemination, frozen-thawed (FT) ram spermatozoa display reduced fertility compared to fresh spermatozoa, irrespective of sperm motility and viability, likely attributed to an elevated immune response in the ovine cervix. SP has previously been shown to be beneficial to sperm transport in the ovine cervix, yet the components responsible for this protective effect remain unknown. As such, the present study examined the immune dynamics of frozen-thawed ram spermatozoa with polymorphonuclear neutrophils (PMNs), utilising a neutrophil binding assay. The effect of 25% v/v SP supplementation on binding susceptibility was also investigated. A portion of SP was heat-treated before incubation (HTSP) to isolate the impact of SP proteins. The presence of SP significantly reduced sperm-PMN binding (37.15 ± 0.02%, 46.59 ± 0.02%, 38.83 ± 0.02%) compared to FT alone (62.83 ± 0.02%, 75.74 ± 0.02%, 56.0 ± 0.03%) across all serum groups (no serum, serum and heat-treated serum, respectively). HTSP showed comparable binding susceptibility to the FT treatments, indicating that the protective effect of SP is attributed to a heat-labile factor. Serum significantly increased sperm-neutrophil binding irrespective of SP treatment. However, this was reduced to serum-free levels following heat-treatment, suggesting sperm-neutrophil dynamics are further mediated by protein components within ewe serum, likely complement proteins. The viability of sperm or the presence of freezing medium did not influence PMN binding. Furthermore, PMN viability and therefore binding were not influenced by the presence of serum or SP. Together, the current study presents new evidence for the immunoprotective properties of SP in sheep, which could be leveraged to aid transit through the cervix.
冻融后的公羊精子在经子宫颈人工授精后生育力降低，这可能归因于母羊体内免疫反应增强。本文确定了公羊精浆（SP）对多形核中性粒细胞结合的免疫保护作用，突出了其改善生育力的潜力。
经子宫颈人工授精后，与新鲜精子相比，冻融（FT）公羊精子的生育力降低，无论精子活力和生存力如何，这可能归因于绵羊子宫颈内免疫反应增强。先前已证明SP有利于精子在绵羊子宫颈内的运输，但其发挥这种保护作用的成分尚不清楚。因此，本研究利用中性粒细胞结合试验，研究了冻融公羊精子与多形核中性粒细胞（PMN）的免疫动力学。还研究了添加25%（v/v）SP对结合敏感性的影响。在孵育前对一部分SP进行热处理（HTSP），以分离SP蛋白的影响。与单独的FT（在所有血清组中，分别为62.83±0.02%、75.74±0.02%、56.0±0.03%）相比，SP的存在显著降低了精子与PMN的结合（分别为37.15±0.02%、46.59±0.02%、38.83±0.02%）。HTSP显示出与FT处理相当的结合敏感性，表明SP的保护作用归因于一种热不稳定因子。无论SP处理如何，血清均显著增加精子与中性粒细胞的结合。然而，热处理后这种结合降低到无血清水平，这表明精子与中性粒细胞的动态变化进一步由母羊血清中的蛋白质成分介导，可能是补体蛋白。精子的活力或冷冻介质的存在不影响PMN结合。此外，PMN的活力以及因此的结合不受血清或SP存在的影响。总之，本研究为SP在绵羊中的免疫保护特性提供了新证据，可利用这一特性帮助精子通过子宫颈。
