Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071, China.
Toxicol Lett. 2024 Jun;397:141-150. doi: 10.1016/j.toxlet.2024.05.010. Epub 2024 May 15.
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.
自噬与孕期不利环境导致的多种器官发育毒性有关。我们之前发现，产前咖啡因暴露（PCE）可使胎儿过度暴露于母源性糖皮质激素，导致软骨发育不良。然而，自噬是否参与其中以及发挥何种作用尚未报道。本研究通过在妊娠第 9-20 天灌胃给予咖啡因（120mg/kg.d）建立 PCE 大鼠模型。结果显示，与对照组相比，PCE 组雄性胎鼠软骨中软骨基质合成减少，自噬增加。此外，PCE 组雄性胎鼠软骨中 mTOR、miR-421-3p 和糖皮质激素受体（GR）的表达增加。在细胞水平上，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）给药分别部分增加或进一步降低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，从而靶向抑制 mTOR 的表达，从而增强自噬。总之，PCE 可导致雄性胎鼠出现软骨发育不良和自噬增强。宫内高皮质酮激活胎儿软骨细胞中的 GR/miR-421-3p 信号通路，下调 mTOR 信号通路，导致自噬增强，可部分代偿皮质酮引起的胎儿软骨发育不良。本研究证实了自噬对 PCE 引起的胎儿软骨发育毒性的代偿保护作用及其表观遗传机制，为探索胎儿起源性骨关节炎的早期干预和治疗靶点提供了新的思路。
