Abstract：
Autophagy has been implicated in the developmental toxicity of multiple organs in offspring caused by adverse environmental conditions during pregnancy. We have previously found that prenatal caffeine exposure (PCE) can cause fetal overexposure to maternal glucocorticoids, leading to chondrodysplasia. However, whether autophagy is involved and what role it plays has not been reported. In this study, a PCE rat model was established by gavage of caffeine (120 mg/kg.d) on gestational day 9-20. The results showed that reduced cartilage matrix synthesis in male fetal rats in the PCE group was accompanied by increased autophagy compared to the control group. Furthermore, the expression of mTOR, miR-421-3p, and glucocorticoid receptor (GR) in male fetal rat cartilage of PCE group was increased. At the cellular level, we confirmed that corticosterone inhibited matrix synthesis in fetal chondrocytes while increasing autophagic flux. However, administration of autophagy enhancer (rapamycin) or inhibitor (bafilomycin A1 or 3-methyladenine) partially increased or further decreased aggrecan expression respectively. At the same time, we found that corticosterone could increase the expression of miR-421-3p through GR and target to inhibit the expression of mTOR, thereby enhancing autophagy. In conclusion, PCE can cause chondrodysplasia and autophagy enhancement in male fetal rats. Intrauterine high corticosterone activates GR/miR-421-3p signaling and down-regulates mTOR signaling in fetal chondrocytes, resulting in enhanced autophagy, which can partially compensate for corticosterone-induced fetal chondrodysplasia. This study confirmed the compensatory protective effect of autophagy on the developmental toxicity of fetal cartilage induced by PCE and its epigenetic mechanism, providing novel insights for exploring the early intervention and therapeutic target of fetal-originated osteoarthritis.
摘要：
自噬与怀孕期间不利的环境条件引起的后代多器官的发育毒性有关。我们先前发现，产前咖啡因暴露（PCE）可导致胎儿过度暴露于母体糖皮质激素，导致软骨发育不良.然而,自噬是否参与以及它起什么作用还没有报道.在这项研究中,用咖啡因(120mg/kg。d）在妊娠第9-20天。结果表明，与对照组相比，PCE组雄性胎鼠软骨基质合成的减少伴随着自噬的增加。此外，mTOR的表达，miR-421-3p,PCE组雄性胎鼠软骨糖皮质激素受体(GR)升高。在细胞层面,我们证实皮质酮抑制胎儿软骨细胞基质合成，同时增加自噬通量。然而,自噬增强剂（雷帕霉素）或抑制剂（巴弗洛霉素A1或3-甲基腺嘌呤）的给药分别部分增加或进一步减少了聚集蛋白聚糖的表达。同时,我们发现皮质酮可以通过GR增加miR-421-3p的表达，并以抑制mTOR的表达为靶点，从而增强自噬。总之,PCE可引起雄性胎鼠软骨发育不良和自噬增强。宫内高皮质酮激活GR/miR-421-3p信号并下调胎儿软骨细胞中的mTOR信号,导致自噬增强，可以部分补偿皮质酮诱导的胎儿软骨发育不良。本研究证实了自噬对PCE诱导的胎儿软骨发育毒性的代偿保护作用及其表观遗传机制。为探索胎儿源性骨关节炎的早期干预和治疗靶点提供新的见解。
