DNA methylation‐mediated 11βHSD2 downregulation drives the increases in angiotensin‐converting enzyme and angiotensin II within preeclamptic placentas

Preeclampsia (PE) is a complex human-specific complication frequently associated with placental pathology. The local renin-angiotensin system (RAS) in the human placenta, which plays a crucial role in regulating placental function, has been extensively documented. Glucocorticoids (GCs) are a class of steroid hormones. PE cases often have abnormalities in GCs levels and placental GCs barrier. Despite extensive speculation, there is currently no robust evidence indicating that GCs regulate placental RAS. This study aims to investigate these potential relationships. Plasma and placental samples were collected from both normal and PE pregnancies. The levels of angiotensin-converting enzyme (ACE), angiotensin II (Ang II), cortisol, and 11β-hydroxysteroid dehydrogenases (11βHSD) were analyzed. In PE placentas, cortisol, ACE, and Ang II levels were elevated, while 11βHSD2 expression was reduced. Interestingly, a positive correlation was observed between ACE and cortisol levels in the placenta. A significant inverse correlation was found between the methylation statuses within the 11βHSD2 gene promoter and its expression, meanwhile, 11βHSD2 expression was negatively correlated with cortisol and ACE levels. In vitro experiments using placental trophoblast cells confirmed that active GCs can stimulate ACE transcription and expression through the GR pathway. Furthermore, 11βHSD2 knockdown could enhance this activating effect. An in vivo study using a rat model of intrauterine GCs overexposure during mid-to-late gestation suggested that excess GCs in utero lead to increased ACE and Ang II levels in the placenta. Collectively, this study provides the first evidence of the relationships between 11βHSD2 expression, GCs barrier, ACE, and Ang II levels in the placenta. It not only contributes to understanding the pathological features of the placental GCs barrier and RAS under PE conditions, also provides important information for revealing the pathological mechanism of PE.