Exposure to the herbicide Agent Orange during the Vietnam War was widespread and is associated with numerous adverse health outcomes. A continuing concern of veterans is the possibility that exposure to the dioxin-containing herbicide might induce adverse reproductive outcomes. We sought to assess whether exposure to Agent Orange in Vietnam was associated with changes in DNA methylation in sperm in a subset of Vietnam veterans who participated in the Air Force Health Study (AFHS). We studied 37 members of the AFHS chosen to have no, low, medium or high exposure to Agent Orange, based upon serum dioxin levels obtained during a series of examinations. DNA from stored semen was extracted and DNA methylation assessed on the Illumina 450 K platform. Initial epigenome-wide analysis returned no loci that survived control for false discovery. However, the TEAD3 gene had four different CpG sites that showed loss of DNA methylation associated with dioxin exposure. Analysis assessing regional DNA methylation changes revealed 36 gene regions, including the region of the imprinted gene H19 to have altered DNA methylation associated with high exposure compared to the low exposure group. Additional comparison of our data with sperm DNA methylation data from Russian boys exposed to dioxin found an additional 5 loci that were altered in both studies and exhibited a consistent direction of association. Studying a small number of sperm samples from veterans enrolled in the AFHS, we did not find evidence of significant epigenome-wide alterations associated with exposure to Agent Orange. However, additional analysis showed that the H19 gene region is altered in the sperm of Agent Orange-exposed Ranch Hand veterans. Our study also replicated several findings of a prior study of dioxin-exposed Russian boys. These results provide additional candidate loci for further investigation and may have implications for the reproductive health of dioxin-exposed individuals.

中文翻译：

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接触橙剂的牧场手退伍军人精子中的血清二恶英和 DNA 甲基化

越南战争期间广泛接触除草剂橙剂，并与许多不良健康后果相关。退伍军人持续担心的是，接触含二恶英的除草剂可能会导致不良的生殖后果。我们试图评估参加空军健康研究 (AFHS) 的一部分越南退伍军人的精子 DNA 甲基化变化是否与在越南接触橙剂有关。我们研究了 37 名 AFHS 成员，根据一系列检查期间获得的血清二恶英水平，选择不接触、低度、中度或高度接触橙剂。从储存的精液中提取 DNA，并在 Illumina 450 K 平台上评估 DNA 甲基化。最初的表观基因组范围分析没有返回任何能够在错误发现的控制下幸存的基因座。然而，TEAD3 基因有四个不同的 CpG 位点，显示与二恶英暴露相关的 DNA 甲基化缺失。评估区域 DNA 甲基化变化的分析显示，与低暴露组相比，36 个基因区域（包括印记基因 H19 的区域）发生了与高暴露相关的 DNA 甲基化改变。将我们的数据与暴露于二恶英的俄罗斯男孩的精子 DNA 甲基化数据进行进一步比较，发现另外 5 个基因座在两项研究中都发生了改变，并表现出一致的关联方向。通过研究参加 AFHS 的退伍军人的少量精子样本，我们没有发现与接触橙剂相关的显着表观基因组变化的证据。然而，进一步的分析表明，接触过橙剂的牧场工人退伍军人的精子中的 H19 基因区域发生了改变。我们的研究还复制了之前对暴露于二恶英的俄罗斯男孩的研究的几项结果。这些结果为进一步研究提供了额外的候选位点，并可能对二恶英暴露个体的生殖健康产生影响。