Moore Jordan L, Parks Seth J, James Emma R, Aston Kenneth I, Jenkins Timothy G
Brigham Young University, Department of Cell Biology and Physiology, 4005 Life Sciences Building (LSB), Provo, UT 84602, United States.
University of Utah School of Medicine, Department of Surgery, Division of Urology, 30 N Mario Capecchi Drive, Salt Lake City, UT 84112, United States.
Reprod Toxicol. 2025 Mar;132:108850. doi: 10.1016/j.reprotox.2025.108850. Epub 2025 Feb 1.
A number of environmental factors have been shown to impact the sperm epigenome. Air pollution is one of the largest health and environmental hazards in the world today and has been implicated in many modern diseases. Recently, air pollution has been shown to alter methylation signatures in some body tissues, indicating that air pollution may also affect the sperm epigenome. The present experiment was conducted to analyze how seasonal air pollution in the Salt Lake Valley may impact DNA methylation patterns in sperm and to establish a relationship between air pollution and sperm epigenetic health as measured by DNA methylation. Sperm DNA methylation patterns were assessed in 74 individuals, who presented at the University of Utah Andrology Clinic for semen analysis, using the Illumina Human MethylationEPIC BeadChip array. Each semen sample collected, as per the fifth edition of WHO reference values for human semen characterization, was deemed normal. Two sample groups from the Salt Lake Valley, Urban Winter (UW, n = 20), Urban Summer (US, n = 21), and two sample groups east of the Wasatch mountains, Rural Winter (RW, n = 19) and Rural Summer (RS, n = 14), were compared to assess the effect of air pollution on sperm DNA methylation patterns. Due to seasonal inversions, urban winters are characterized by increased air pollution compared to summer months. Therefore, the UW sample group was designated as treatment and the three remaining groups (US, RW, RS) were designated as control. We conducted multiple differential methylation analyses using a sliding window approach which utilized the USeq software package. A sliding window analysis of UW versus US was conducted first, followed by a confirmatory analysis comparing UW versus RW and RS. Outputs from the USeq analysis were assessed using several tools including the Stanford GREAT analysis and an analysis of methylation instability at key promoter regions in sperm. The sliding window analysis identified six differentially methylated regions (DMRs) between the UW and US groups (Wilcoxon FDR ≥ 40, corresponding p-value of ∼0.0001). Three of these six regions were confirmed with the second confirmatory analysis of UW versus RS/RW (Wilcoxon FDR ≥ 20, p-value<0.01). According to a GREAT analysis, each of the identified regions exhibited multiple gene ontology associations. Air pollution subtly alters DNA methylation in sperm, indicating that certain regions of the sperm epigenome may be susceptible to air pollution-induced modification with possible implications for reproductive and offspring health.
多项环境因素已被证明会影响精子表观基因组。空气污染是当今世界最大的健康和环境危害之一，与许多现代疾病有关。最近，空气污染已被证明会改变某些身体组织中的甲基化特征，这表明空气污染也可能影响精子表观基因组。本实验旨在分析盐湖谷的季节性空气污染如何影响精子中的DNA甲基化模式，并建立空气污染与通过DNA甲基化测量的精子表观遗传健康之间的关系。使用Illumina Human MethylationEPIC BeadChip芯片对74名前往犹他大学男科诊所进行精液分析的个体的精子DNA甲基化模式进行了评估。根据世界卫生组织人类精液特征参考值第五版收集的每份精液样本均被视为正常。比较了来自盐湖谷的两个样本组，城市冬季组（UW，n = 20）、城市夏季组（US，n = 21），以及瓦萨奇山脉以东的两个样本组，农村冬季组（RW，n = 19）和农村夏季组（RS，n = 14），以评估空气污染对精子DNA甲基化模式的影响。由于季节性逆温，城市冬季的空气污染比夏季月份增加。因此，UW样本组被指定为处理组，其余三个组（US、RW、RS）被指定为对照组。我们使用滑动窗口方法进行了多次差异甲基化分析，该方法利用了USeq软件包。首先对UW与US进行滑动窗口分析，然后进行比较UW与RW和RS的验证性分析。使用包括斯坦福大学GREAT分析和精子关键启动子区域甲基化不稳定性分析在内的多种工具评估USeq分析的输出结果。滑动窗口分析在UW和US组之间确定了六个差异甲基化区域（DMRs）（Wilcoxon FDR≥40，相应的p值约为0.0001）。这六个区域中的三个在UW与RS/RW的第二次验证性分析中得到了确认（Wilcoxon FDR≥20，p值<0.01）。根据GREAT分析，每个确定的区域都表现出多个基因本体关联。空气污染会微妙地改变精子中的DNA甲基化，这表明精子表观基因组的某些区域可能易受空气污染诱导的修饰影响，这可能对生殖和后代健康产生影响。
