Department of Animal Physiology, Slovak University of Agriculture in Nitra, Nitra, Slovakia.
Department of Genetics and Plant Breeding, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Nitra, Slovakia.
Syst Biol Reprod Med. 2021 Dec;67(6):438-449. doi: 10.1080/19396368.2021.1958028. Epub 2021 Aug 27.
Although bacterial contamination of ejaculates may cause difficulties in cattle reproduction, standard protocols for a routine microbiological analysis of bovine semen are still missing. Understanding of the mechanisms of bacterial damage to spermatozoa may contribute to the prevention and management of bacteriospermia in the future. Therefore, this study was designed to investigate bacterial profiles of fresh bovine ejaculates (n = 30), while at the same time we focused on assessing the relationships between bacteriospermia and selected sperm quality parameters as well as an array of oxidative stress and inflammatory markers. The samples were divided into three quality groups according to the sperm motility: Excellent (EX) - over 90% > Good (GO) - between 89% and 80% > Moderate (MO) - under 80%. The results showed a significant increase in reactive oxygen species (ROS) generation in the GO group when compared to the EX group. In the MO group, a deterioration of almost all quality parameters was observed when compared to the EX group. In particular, sperm motility, mitochondrial membrane potential, ROS production and IL-6 concentration exhibited a significant decline. Pearson correlation analysis revealed positive associations among bacterial load and the presence of leukocytes in semen (r = 0.965), malondialdehyde concentration (r = 0.816) and DNA fragmentation (r = 0.784). MALDI-TOF MS Biotyper analysis showed a prevalence of the genus. The quantification of bacterial colonies revealed a significantly increased (P < 0.01) bacterial load in the MO group when compared with the EX as well as the GO group. Overall, our results suggest that sperm quality may be affected by both, bacterial composition, and bacterial load. It appears that an increased presence of bacterial species triggers the immune response, causes oxidative stress, and thereby contributes to sperm structural alterations while diminishing their fertilization ability. EX: Excellent; GO: Good; MO: Moderate; MOT: Motility; ROS: Reactive Oxygen Species; MMP: Mitochondrial Membrane Potential; IL-1: Interleukin 1; IL-6: Interleukin 6; IL-8: Interleukin 8; IL-12: Interleukin 12; CRP: C-reactive protein; DNA: Deoxyribonucleic acid; MALDI-TOF MS: Matrix-assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry; LPO: Lipid peroxidation; CFU: Colony-forming units MDA: Malondialdehyde; CASA: Computer-assisted Sperm Analysis; WS: Working solution; RIPA: Radio-immunoprecipitation assay; TBARS: Thiobarbituric Acid Reactive Substances; BHB: D-β-hydroxybutyrate.
虽然精液中的细菌污染可能会给牛的繁殖带来困难，但目前仍缺乏牛精液常规微生物分析的标准方案。了解细菌对精子的损伤机制可能有助于未来预防和管理细菌性精子症。因此，本研究旨在调查新鲜牛精液的细菌谱（n=30），同时我们还重点评估了细菌性精子症与选定的精子质量参数以及一系列氧化应激和炎症标志物之间的关系。根据精子运动能力将样本分为三组：优秀（EX）-超过 90%>良好（GO）-在 89%和 80%之间>中等（MO）-低于 80%。结果显示，与 EX 组相比，GO 组的活性氧（ROS）生成显著增加。与 EX 组相比，MO 组几乎所有的质量参数都明显恶化。特别是精子运动能力、线粒体膜电位、ROS 生成和 IL-6 浓度显著下降。Pearson 相关分析显示，精液中细菌负荷和白细胞的存在与丙二醛浓度（r=0.816）和 DNA 片段化（r=0.784）之间存在正相关。MALDI-TOF MS Biotyper 分析显示属的流行。细菌菌落的定量显示，与 EX 组和 GO 组相比，MO 组的细菌负荷显著增加（P<0.01）。总的来说，我们的结果表明，精子质量可能受到细菌组成和细菌负荷的影响。似乎细菌种类的增加会引发免疫反应，导致氧化应激，从而导致精子结构改变，同时降低其受精能力。EX：优秀；GO：良好；MO：中等；MOT：运动能力；ROS：活性氧；MMP：线粒体膜电位；IL-1：白细胞介素 1；IL-6：白细胞介素 6；IL-8：白细胞介素 8；IL-12：白细胞介素 12；CRP：C-反应蛋白；DNA：脱氧核糖核酸；MALDI-TOF MS：基质辅助激光解吸/电离飞行时间质谱法；LPO：脂质过氧化；CFU：集落形成单位；MDA：丙二醛；CASA：计算机辅助精子分析；WS：工作溶液；RIPA：放射免疫沉淀测定；TBARS：硫代巴比妥酸反应物质；BHB：D-β-羟基丁酸。
