背景：已发现子宫内膜机械损伤引起的宫腔粘连（IUA）是女性不孕症的重要危险因素（例如，人工流产）。雌激素是修复子宫内膜损伤的经典药物，但其在子宫内膜纤维化临床应用中的作用机制尚不清楚。
目的：探讨雌激素治疗IUA的具体作用机制。
方法：建立体内IUA模型和体外分离的子宫内膜基质细胞（ESCs）模型。然后CCK8检测,实时PCR,应用Western印迹和双荧光素酶报告基因测定来确定雌激素对ESC的靶向作用。
结果：发现17β-雌二醇通过下调miR-21-5p水平和激活PPARα信号通路抑制ESCs纤维化。机械上,miR-21-5p显着降低17β-雌二醇对纤维化ESCs（ESCs-F）及其标记蛋白的抑制作用（例如，α-SMA,胶原蛋白I，和纤连蛋白），其中靶向PPARα3'-UTR并阻断其激活和转录，从而降低脂肪酸氧化（FAO）相关关键酶的表达，引起脂肪积累和活性氧（ROS）的产生，导致子宫内膜纤维化。然而，PPARα激动剂咖啡酸抵消了miR-21-5p对ESCs-F的促进作用，这与雌激素干预的疗效一致。
结论：简而言之，上述研究结果表明,miR-21-5p/PPARα信号轴在子宫内膜机械损伤的纤维化过程中发挥了重要作用,并提示雌激素可能是促进其进展的有希望的药物.
Intrauterine adhesion (IUA) caused by endometrial mechanical injury has been found as a substantial risk factor for female infertility (e.g., induced abortion). Estrogen is a classic drug for the repair of endometrial injury, but its action mechanism in the clinical application of endometrial fibrosis is still unclear.
To explore the specific action mechanism of estrogen treatment on IUA.
The IUA model in vivo and the isolated endometrial stromal cells (ESCs) model in vitro were built. Then CCK8 assay, Real-Time PCR, Western Blot and Dual- Luciferase Reporter Gene assay were applied to determine the targeting action of estrogen on ESCs.
It was found that 17β-estradiol inhibited fibrosis of ESCs by down-regulating miR-21-5p level and activating PPARα signaling. Mechanistically, miR-21-5p significantly reduced the inhibitory effect of 17β-estradiol on fibrotic ESCs (ESCs-F) and its maker protein (e.g., α-SMA, collagen I, and fibronectin), where targeting to PPARα 3\'- UTR and blocked its activation and transcription, thus lowering expressions of fatty acid oxidation (FAO) associated key enzyme, provoking fatty accumulation and reactive oxygen species (ROS) production, resulting in endometrial fibrosis. Nevertheless, the PPARα agonist caffeic acid counteracted the facilitation action of miR-21-5p on ESCs-F, which is consistent with the efficacy of estrogen intervention.
In brief, the above findings revealed that the miR-21-5p/PPARα signal axis played an important role in the fibrosis of endometrial mechanical injury and suggested that estrogen might be a promising agent for its progression.
