Background:

Implantation is initiated when the blastocyst attaches to the endometrium during the peri-implantation period, and appropriate neovascularization is a prerequisite for the success of the subsequent process. The role of the renin–angiotensin system (RAS) in regulation of blood pressure and hydro-electrolyte balance has long been recognized, while its role in the peri-implantation endometrium remains unclear. This manuscript discusses endometrial RAS and its possible pathways in regulating endometrial angiogenesis and its influence on subsequent pregnancy outcomes.

Methods:

A comprehensive search of electronic databases was carried out to identify relevant published articles, and a literature review was then performed. Using immunohistochemistry, we also performed a pilot study to examine expression of angiotensin II receptors, including angiotensin II type 1 (AT1) receptor (AT1-R) and angiotensin II type 2 (AT2) receptor (AT2-R) in the human endometrium around the time of implantation.

Results:

The results of the pilot study showed expression of AT1-R and AT2-R in all endometrial compartments (luminal epithelium, glandular epithelium, stroma cells, and blood vessels), and altered expression was witnessed in women with recurrent miscarriage when compared with fertile control women from our preliminary result.

Conclusion:

Altered vasculature of the endometrium in the peri-implantation period is detrimental to implantation and may lead to recurrent miscarriage. Being an angiogenic mediators, endometrial RAS may play a role around the time of embryo implantation, affecting subsequent pregnancy outcomes.

中文翻译：

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肾素-血管紧张素系统在围着床期调节子宫内膜新生血管中的作用：文献回顾和初步数据。

背景：

胚胎着床期在胚泡附着于子宫内膜时开始着床，适当的新生血管形成是后续过程成功的先决条件。肾素-血管紧张素系统（RAS）在调节血压和水电解质平衡中的作用早已得到认可，而其在着床期子宫内膜中的作用仍不清楚。这份手稿讨论了子宫内膜 RAS 及其调节子宫内膜血管生成的可能途径及其对随后妊娠结局的影响。

方法：

对电子数据库进行全面搜索以识别相关已发表文章，然后进行文献综述。使用免疫组织化学，我们还进行了一项初步研究，以检查血管紧张素 II 受体的表达，包括血管紧张素 II 1 型 (AT1) 受体 (AT1-R) 和血管紧张素 II 2 型 (AT2) 受体 (AT2-R) 在人子宫内膜周围植入的时间。

结果：

初步研究的结果显示 AT1-R 和 AT2-R 在所有子宫内膜隔室（管腔上皮、腺上皮、基质细胞和血管）中的表达，并且与生育控制相比，在复发性流产的女性中观察到表达改变来自我们初步结果的女性。

结论：

着床期子宫内膜血管系统的改变对着床不利，并可能导致反复流产。作为血管生成介质，子宫内膜 RAS 可能在胚胎植入期间发挥作用，影响随后的妊娠结局。