NCOA4-VDACs/FtMt协同介导异位子宫内膜耐受铁死亡的生存机制

Ferroptosis is a programmed cell deathcaused by the accumulation of ferrous ions in the cytoplasm, which can catalyze lipid into a variety of reactive oxygen species (ROS) even exceed the compensatory of the antioxidant system, resulting in DNA damage and modification as well as cell death finally. Bleeding is an important cause of iron imbalance and ferroptosis. Endometriosis involves the theory of menstrual blood reflux, and lesions show the characteristic of periodic bleeding along with hormone level changes, all which will improve the iron accumulation and format the pathological environment specialized with high level iron concentration in the abdominal cavity. Our previous study found that, in the culture medium simulated peritoneal fluid iron concentration, the normal endometrial stromal cells (ESCs) appeared ferroptosis while the ectopic ESCs did not. These results suggested that the transport and storage of intracellular iron may have undergone some adaptive changes to maintain the cytoplasmic iron homeostasis threshold.Thus we put forward that "NCOA4-VDACs/FtMtpathway can improve the viability of ectopic endometrial cells in the cruel environment via changing the iron metabolism and further inhibit subsequent ferroptosis". This study proposed by in vivo and in vitro experiments, through intervention the expressionof NCOA4-VDACs/FtMt, aims to explore the distribution pattern of iron, the oxidation level, the capacity of antioxidant as well as the changes of gene expression in ESCs cultured in different iron concentration medium.The impact of ferroptosis on the formation of endometrial lesions was verified by endometriosis mouse model. We expect this research can not only reveals the molecular mechanism of ferroptosis tolerance but also provide a hormone-independent therapeutic targets in endometriosis in the future.

铁死亡是胞质内铁稳态失衡触发胞内脂质过氧化导致的程序性细胞死亡。出血是引发铁失衡、驱动铁死亡的重要原因。内异症腹腔及病灶微环境分别因周期性经血逆流和出血而存在铁蓄积过载的失衡状态。我们的前期研究发现，模拟腹腔液铁离子浓度培养的正常子宫内膜间质细胞（ESC）发生铁死亡；而异位内膜ESC异乎寻常地并未发生铁死亡。其胞质内铁的转运与贮存可能发生了某种适应性改变从而维护了胞质铁稳态阈值。由此我们提出“异位内膜通过NCOA4-VDACs/FtMt转铁途径维稳胞内铁离子水平，免于启动铁死亡程序而获得生存”的构想。本研究拟行体外及体内实验，通过干预NCOA4-VDACs/FtMt表达，解析不同铁浓度下ESC胞质和贮铁细胞器中铁离子的分布格局、氧化与抗氧化能力、铁死亡基因等变化；借助内异症小鼠模型验证诱导铁死亡对內异灶形成的影响。籍此揭示异位内膜耐受铁死亡的分子机制，探寻内异症非激素治疗的途径或靶点。

子宫内膜异位症（endometriosis，EMS）是一种良性妇科病，却具有异位种植、浸润等恶性生物学特征，临床表现为进行性加重的痛经、性交痛、不孕等，严重影响育龄期女性身心健康。目前发病机制未被完全阐释，故缺乏有效的治疗策略：药物治疗降低雌激素水平虽效果显著，但限于低雌激素所致的负面影响治疗常被迫中断；而手术治疗对生育力的负面影响及术后高复发率亦使治疗效果差强人意。.经血逆流及病灶周期性出血是子宫内膜异位症发病的独特性事件，周而复始形成局部血红素蓄积、铁过载、高氧化应激状态的恶劣环境，而子宫内膜间质细胞（ESC）及巨噬细胞（Mφ）却能在如此恶劣的环境中免于发生“铁死亡”获得生存，本项目对此作了深入研究。我们的研究结果表明，相比于对照组，EMS腹腔液中铁浓度显著升高，异位内膜间质细胞（EESC）中铁转运（TfR1、FPN1）及分布（NCOA4-VDACs/FtMt）调控相关分子表达显著改变，胞内铁蓄积并高效转运，同时细胞内依赖GPX4/GSH的抗氧化能力提高；同样地，EMS腹腔液中血红素蓄积，EESC通过提高细胞内血红素转运相关分子CD91、FLVCR2、ABCG2，血红素代谢酶HO-1的表达水平，增强血红素代谢，提高细胞线粒体功能及ATP产量，进一步增强EESC增殖及迁移能力，Mφ中蓄积的血红素同时抑制了其吞噬能力，更利于子宫内膜间质细胞生存；进一步研究发现，EMS腹腔微环境及病灶中肌酸浓度明显升高，EESC中肌酸合成酶表达增加，而肌酸/磷酸肌酸缓冲体系是其应对恶劣环境获得生存的重要保障，可“挽救”ESC使其免于发生铁死亡，我们通过EMS小鼠模型验证了肌酸能促进EMS进展。以上研究结果为探寻代谢-免疫调控这样的非激素治疗途径提供了实验基础与理论依据。