STUDY QUESTION How does ovarian stimulation (OS), which is used to mature multiple oocytes for ART procedures, impact the principal cellular compartments and transcriptome of the human endometrium in the periovulatory and mid-secretory phases? SUMMARY ANSWER During the mid-secretory window of implantation, OS alters the abundance of endometrial immune cells, whereas during the periovulatory period, OS substantially changes the endometrial transcriptome and impacts both endometrial glandular and immune cells. WHAT IS KNOWN ALREADY Pregnancies conceived in an OS cycle are at risk of complications reflective of abnormal placentation and placental function. OS can alter endometrial gene expression and immune cell populations. How OS impacts the glandular, stromal, immune, and vascular compartments of the endometrium, in the periovulatory period as compared to the window of implantation, is unknown. STUDY DESIGN, SIZE, DURATION This prospective cohort study carried out between 2020 and 2022 included 25 subjects undergoing OS and 25 subjects in natural menstrual cycles. Endometrial biopsies were performed in the proliferative, periovulatory, and mid-secretory phases. PARTICIPANTS/MATERIALS, SETTING, METHODS Blood samples were processed to determine serum estradiol and progesterone levels. Both the endometrial transcriptome and the principal cellular compartments of the endometrium, including glands, stroma, immune, and vasculature, were evaluated by examining endometrial dating, differential gene expression, protein expression, cell populations, and the three-dimensional structure in endometrial tissue. Mann–Whitney U tests, unpaired t-tests or one-way ANOVA and pairwise multiple comparison tests were used to statistically evaluate differences. MAIN RESULTS AND THE ROLE OF CHANCE In the periovulatory period, OS induced high levels of differential gene expression, glandular-stromal dyssynchrony, and an increase in both glandular epithelial volume and the frequency of endometrial monocytes/macrophages. In the window of implantation during the mid-secretory phase, OS induced changes in endometrial immune cells, with a greater frequency of B cells and a lower frequency of CD4 effector T cells. LARGE SCALE DATA The data underlying this article have been uploaded to the Genome Expression Omnibus/National Center for Biotechnology Information with accession number GSE220044. LIMITATIONS, REASONS FOR CAUTION A limited number of subjects were included in this study, although the subjects within each group, natural cycle or OS, were homogenous in their clinical characteristics. The number of subjects utilized was sufficient to identify significant differences; however, with a larger number of subjects and additional power, we may detect additional differences. Another limitation of the study is that proliferative phase biopsies were collected in natural cycles, but not in OS cycles. Given that the OS cycle subjects did not have known endometrial factor infertility, and the comparisons involved subjects who had a similar and robust response to stimulation, the findings are generalizable to women with a normal response to OS. WIDER IMPLICATIONS OF THE FINDINGS OS substantially altered the periovulatory phase endometrium, with fewer transcriptomic and cell type-specific changes in the mid-secretory phase. Our findings show that after OS, the endometrial microenvironment in the window of implantation possesses many more similarities to that of a natural cycle than does the periovulatory endometrium. Further investigation of the immune compartment and the functional significance of this cellular compartment under OS conditions is warranted. STUDY FUNDING/COMPETING INTERESTS Research reported in this publication was supported by the National Institute of Allergy and Infectious Diseases (R01AI148695 to A.M.B. and N.C.D.), Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD109152 to R.A.), and the March of Dimes (5-FY20-209 to R.A.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or March of Dimes. All authors declare no conflict of interest.

中文翻译：

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卵巢刺激对人体子宫内膜微环境的影响

研究问题 用于在 ART 手术中使多个卵母细胞成熟的卵巢刺激 (OS) 如何影响排卵期和分泌中期阶段人类子宫内膜的主要细胞区室和转录组？摘要答案 在植入的中期分泌窗口期间，OS 改变子宫内膜免疫细胞的丰度，而在排卵期期间，OS 显着改变子宫内膜转录组并影响子宫内膜腺体和免疫细胞。已知的情况 在 OS 周期中受孕的妊娠存在发生并发症的风险，这些并发症反映了异常胎盘和胎盘功能。 OS 可以改变子宫内膜基因表达和免疫细胞群。与着床窗口期相比，在排卵期，OS 如何影响子宫内膜的腺体、间质、免疫和血管区室尚不清楚。研究设计、规模、持续时间 这项前瞻性队列研究在 2020 年至 2022 年期间进行，包括 25 名接受 OS 的受试者和 25 名处于自然月经周期的受试者。在增殖期、排卵期和分泌中期进行子宫内膜活检。参与者/材料、背景、方法 对血样进行处理以确定血清雌二醇和黄体酮水平。通过检查子宫内膜年代、差异基因表达、蛋白质表达、细胞群和子宫内膜组织的三维结构来评估子宫内膜转录组和子宫内膜的主要细胞区室，包括腺体、间质、免疫和脉管系统。 Mann-Whitney U 检验、不配对 t 检验或单向方差分析和成对多重比较检验用于统计评估差异。主要结果和机会的作用在排卵期，OS 诱导高水平的差异基因表达、腺体-间质不同步以及腺上皮体积和子宫内膜单核细胞/巨噬细胞频率的增加。在分泌中期的着床窗口期，OS 诱导子宫内膜免疫细胞发生变化，B 细胞频率较高，CD4 效应 T 细胞频率较低。大规模数据 本文所依据的数据已上传至基因组表达综合库/国家生物技术信息中心，登录号为 GSE220044。局限性、注意事项 尽管每组中的受试者、自然周期或 OS 的临床特征均相同，但本研究纳入的受试者数量有限。使用的受试者数量足以识别显着差异；然而，随着受试者数量的增加和能力的增强，我们可能会发现更多的差异。该研究的另一个局限性是，增殖期活检是在自然周期中收集的，而不是在 OS 周期中收集的。鉴于 OS 周期受试者没有已知的子宫内膜因素不孕，并且比较涉及对刺激有相似且强烈反应的受试者，因此研究结果可推广到对 OS 反应正常的女性。研究结果的更广泛意义 OS 显着改变了排卵期子宫内膜，在分泌中期的转录组和细胞类型特异性变化较少。我们的研究结果表明，OS后，着床窗口期的子宫内膜微环境比排卵期子宫内膜与自然周期有更多相似之处。有必要进一步研究免疫区室以及该细胞区室在 OS 条件下的功能意义。研究经费/竞争利益 本出版物中报告的研究得到了国家过敏和传染病研究所（R01AI148695 至 AMB 和 NCD）、尤尼斯·肯尼迪·施赖弗国家儿童健康和人类发展研究所（R01HD109152 至 RA）以及 March 10 美分（5-FY20-209 至 RA）。内容完全由作者负责，并不一定代表美国国立卫生研究院或 March of Dimes 的官方观点。所有作者均声明不存在利益冲突。