Sperm DNA methylation changes after nut supplementation in healthy men consuming a Western-style diet. Sperm DNA methylation changes after nut supplementation in healthy men consuming a Western-style diet

Background Many environmental and lifestyle factors have been implicated in the decline of sperm quality, with diet being one of the most plausible factors identified in recent years. Moreover, several studies have reported a close association between the alteration of specific sperm DNA methylation signatures and semen quality. Objectives To evaluate the effect of tree nuts consumption on sperm DNA methylation patterns in healthy individuals reporting eating a Western‐style diet. Material and Methods This is a post‐hoc analysis conducted in a subset of participants (healthy, non‐smoking, and young) from the FERTINUTS 14‐wk randomized‐controlled, parallel‐trial, recruited between December 2015 and February 2017. The participants included in the current study (n=72) were randomly selected in a proportion 2:1 from the original FERTINUTS trial between the 98 participants that completed the entire dietary intervention (nut group, n=48; control group, n=24). Sperm DNA methylation patterns were examined at baseline and after 14 weeks in 48 individuals consuming 60 g/d of mixed nuts (nuts group) and in 24 individuals following the usual Western‐style diet avoiding consumption of nuts (control group). Results Over the course of the trial, no significant changes in global methylation were observed between groups. However, in the nuts group, we identified 36 genomic regions that were significantly differentially methylated between the baseline and the end of the trial and 97.2% of the regions displayed hypermethylation. We identified no such change in the control group over the same period of time. We also utilized the recently developed germ line age calculator to determine if nut consumption resulted in alterations to the epigenetic age of cells and no significant differences were found. Discussion and Conclusion Adding nuts to a regular Western‐style diet subtly impacts sperm DNA methylation in specific regions, demonstrating that there are some sperm epigenome regions that could respond to diet. Overall design: Bisulphite converted DNA from the 96 samples (24 baseline and 24 after nuts consumption (nuts group) and 24 baseline and 24 after non nuts consumption (control group)) were hybridised to the Infinium® MethylationEPIC BeadChip microarrays.

【背景】诸多环境与生活方式因素被认为与精子质量下降相关，其中饮食是近年被证实的最具合理性的影响因素之一。此外，多项研究已报道，特定精子DNA甲基化特征的改变与精液质量存在密切关联。
【研究目的】评估食用树坚果（tree nuts）对进食西式饮食的健康人群精子DNA甲基化模式的影响。
【材料与方法】本研究为事后分析（post‐hoc analysis），基于FERTINUTS为期14周的随机对照平行试验（randomized‐controlled parallel‐trial）的亚组人群展开，该试验于2015年12月至2017年2月间招募受试者，纳入对象为健康、非吸烟的年轻人群。本研究从完成全部膳食干预的98名原试验受试者中，按2:1的比例随机选取72名作为研究对象，其中坚果组48名，对照组24名。本研究分别在基线期与14周干预后，对两组人群的精子DNA甲基化模式进行检测：坚果组每日食用60g混合树坚果，对照组则维持常规西式饮食且避免摄入坚果。
【研究结果】试验全程中，两组人群的全基因组甲基化水平均未出现组间显著差异。但在坚果组中，本研究共鉴定出36个在基线期与试验结束时存在显著甲基化差异的基因组区域，其中97.2%的区域呈现高甲基化状态。对照组在同期未出现此类甲基化改变。本研究同时借助新近开发的生殖系年龄计算器，评估食用坚果是否会引发细胞表观遗传年龄的改变，结果未发现显著差异。
【讨论与结论】在常规西式饮食中添加树坚果，可对特定区域的精子DNA甲基化产生轻微影响，这表明部分精子表观基因组区域可对膳食干预产生响应。
【整体实验设计】本研究共纳入96份经亚硫酸氢盐转化的DNA样本（其中坚果组：24份基线样本、24份干预后样本；对照组：24份基线样本、24份非坚果干预后样本），将上述样本与Infinium® MethylationEPIC微珠芯片（Infinium® MethylationEPIC BeadChip）进行杂交。