Department of Obstetrics and Gynaecology, Zhongnan Hospital of Wuhan University, 169 Donghu Road, Wuchang District, Wuhan, 430071, China.
Department of Pharmacology, Basic Medical School of Wuhan University, 185 Donghu Road, Wuchang District, Wuhan, 430071, China.
BMC Med. 2021 Dec 8;19(1):311. doi: 10.1186/s12916-021-02173-4.
Prenatal adverse environments can cause fetal intrauterine growth retardation (IUGR) and higher susceptibility to multiple diseases after birth, related to multi-organ development programming changes mediated by intrauterine overexposure to maternal glucocorticoids. As a glucocorticoid barrier, P-glycoprotein (P-gp) is highly expressed in placental syncytiotrophoblasts; however, the effect of P-gp on the occurrence of IUGR remains unclear.
Human placenta and fetal cord blood samples of IUGR fetuses were collected, and the related indexes were detected. Pregnant Wistar rats were administered with 30 mg/kg·d (low dose) and 120 mg/kg·d (high dose) caffeine from gestational day (GD) 9 to 20 to construct the rat IUGR model. Pregnant mice were administered with caffeine (120 mg/kg·d) separately or combined with sodium ferulate (50 mg/kg·d) from gestational day GD 9 to 18 to confirm the intervention target on fetal weight loss caused by prenatal caffeine exposure (PCE). The fetal serum/placental corticosterone level, placental P-gp expression, and related indicator changes were analyzed. In vitro, primary human trophoblasts and BeWo cells were used to confirm the effect of caffeine on P-gp and its mechanism.
The placental P-gp expression was significantly reduced, but the umbilical cord blood cortisol level was increased in clinical samples of the IUGR neonates, which were positively and negatively correlated with the neonatal birth weight, respectively. Meanwhile, in the PCE-induced IUGR rat model, the placental P-gp expression of IUGR rats was decreased while the corticosterone levels of the placentas/fetal blood were increased, which were positively and negatively correlated with the decreased placental/fetal weights, respectively. Combined with the PCE-induced IUGR rat model, in vitro caffeine-treated placental trophoblasts, we confirmed that caffeine decreased the histone acetylation and expression of P-gp via RYR/JNK/YB-1/P300 pathway, which inhibited placental and fetal development. We further demonstrated that P-gp inducer sodium ferulate could reverse the inhibitory effect of caffeine on the fetal body/placental weight. Finally, clinical specimens and other animal models of IUGR also confirmed that the JNK/YB-1 pathway is a co-regulatory mechanism of P-gp expression inhibition, among which the expression of YB-1 is the most stable. Therefore, we proposed that YB-1 could be used as the potential early warning target for the opening of the placental glucocorticoid barrier, the occurrence of IUGR, and the susceptibility of a variety of diseases.
This study, for the first time, clarified the critical role and epigenetic regulation mechanism of P-gp in mediating the opening mechanism of the placental glucocorticoid barrier, providing a novel idea for exploring the early warning, prevention, and treatment strategies of IUGR.
产前不良环境可导致胎儿宫内生长受限（IUGR），并使其在出生后更容易患上多种疾病，这与宫内暴露于母体糖皮质激素导致的多器官发育编程改变有关。P-糖蛋白（P-gp）作为一种糖皮质激素屏障，在胎盘合体滋养层中高度表达；然而，P-gp 对 IUGR 发生的影响尚不清楚。
收集 IUGR 胎儿的人胎盘和胎儿脐血样本，并检测相关指标。给予妊娠 Wistar 大鼠从妊娠第 9 天至 20 天每天 30mg/kg·d（低剂量）和 120mg/kg·d（高剂量）咖啡因，构建大鼠 IUGR 模型。分别给予妊娠小鼠咖啡因（120mg/kg·d）或联合阿魏酸钠（50mg/kg·d）从妊娠第 9 天至 18 天，以确认产前咖啡因暴露（PCE）导致胎儿体重减轻的干预靶点。分析胎儿血清/胎盘皮质酮水平、胎盘 P-gp 表达及相关指标变化。在体外，用人原代滋养层细胞和 BeWo 细胞证实咖啡因对 P-gp 的作用及其机制。
IUGR 新生儿的临床样本中，胎盘 P-gp 表达明显降低，而脐血皮质醇水平升高，分别与新生儿出生体重呈正相关和负相关。同时，在 PCE 诱导的 IUGR 大鼠模型中，IUGR 大鼠的胎盘 P-gp 表达降低，而胎盘/胎儿血皮质酮水平升高，分别与胎盘/胎儿体重减轻呈正相关和负相关。结合 PCE 诱导的 IUGR 大鼠模型，我们在体外用咖啡因处理胎盘滋养层细胞，证实咖啡因通过 RYR/JNK/YB-1/P300 通路降低组蛋白乙酰化和 P-gp 的表达，从而抑制胎盘和胎儿发育。我们进一步证明 P-gp 诱导剂阿魏酸钠可以逆转咖啡因对胎儿体重/胎盘重量的抑制作用。最后，IUGR 的临床标本和其他动物模型也证实，JNK/YB-1 通路是 P-gp 表达抑制的共同调节机制，其中 YB-1 的表达最为稳定。因此，我们提出 YB-1 可作为胎盘糖皮质激素屏障开放、IUGR 发生和多种疾病易感性的潜在早期预警靶标。
本研究首次阐明了 P-gp 在介导胎盘糖皮质激素屏障开放机制中的关键作用和表观遗传调控机制，为探索 IUGR 的早期预警、预防和治疗策略提供了新的思路。
