Wang Xiaoran, Chen Baoxin, Chen Jieping, Huang Mi, Huang Shan
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology Visual Science, Guangzhou, China.
Invest Ophthalmol Vis Sci. 2025 May 1;66(5):35. doi: 10.1167/iovs.66.5.35.
Pathological epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) plays a crucial role in the formation of lens fibrosis, particularly in fibrotic posterior capsular opacification and anterior subcapsular cataract (ASC). Here we investigated the potential roles of endoplasmic reticulum (ER) stress in the development of lens fibrosis.
RNA sequencing was performed to examine global gene expression changes in patients with ASC, as well as in TGFβ2-induced human lens explants and rabbit primary LECs. Rabbit LECs were treated with TGFβ2 in the presence or absence of the ER stress modulator, PERK inhibitor ISRIB, and autophagy inducer for in vitro studies. In vivo investigations were carried out using a mouse model of injury-induced capsular fibrosis, with ISRIB administration. To uncover the underlying mechanisms, we conducted lipidomics analysis, transmission electron microscopy, immunostaining, quantitative PCR, Western blot, and capillary Western immunoassay.
ER stress genes were upregulated in patients with ASC, TGFβ2-stimulated human explants and primary LECs. Pharmacologic ER stress induction promoted EMT, while its inhibition reduced TGFβ2-induced mesenchymal gene levels. Blocking the PERK axis of ER stress with ISRIB or targeting downstream factor ATF4 suppressed EMT, whereas the IRE1 axis showed no effect. Consistent with these in vitro observations, anterior chamber injection of ISRIB also reduced subcapsular plaque formation in a mouse model of lens fibrosis by suppressing SMAD2/3 activation. Mechanistically, ISRIB suppressed LC3-II conversion and P62 degradation, indicating autophagy suppression. Lipidomics revealed phosphatidylethanolamine (PE), essential for autophagosome formation, was downregulated in TGFβ2-treated LECs and upregulated with ISRIB cotreatment. Inducing autophagy with rapamycin significantly rescued the mesenchymal gene suppression by ISRIB, whereas autophagy inhibitor CQ produced opposite effects.
ER stress, particularly the PERK axis, promotes LECs' EMT through autophagy and PE metabolism, offering potential therapeutic targets for the treatment of lens fibrosis.
晶状体上皮细胞（LECs）的病理性上皮-间质转化（EMT）在晶状体纤维化形成中起关键作用，尤其是在纤维化后囊膜混浊和前囊下白内障（ASC）中。在此，我们研究了内质网（ER）应激在晶状体纤维化发展中的潜在作用。
进行RNA测序以检查ASC患者、转化生长因子β2（TGFβ2）诱导的人晶状体外植体和兔原代LECs中的全局基因表达变化。在有或没有ER应激调节剂、PERK抑制剂ISRIB和自噬诱导剂的情况下，用TGFβ2处理兔LECs用于体外研究。使用损伤诱导的囊膜纤维化小鼠模型并给予ISRIB进行体内研究。为了揭示潜在机制，我们进行了脂质组学分析、透射电子显微镜检查、免疫染色、定量PCR、蛋白质免疫印迹和毛细管蛋白质免疫测定。
ER应激基因在ASC患者、TGFβ2刺激的人外植体和原代LECs中上调。药理学诱导ER应激促进EMT，而其抑制降低了TGFβ2诱导的间充质基因水平。用ISRIB阻断ER应激的PERK轴或靶向下游因子ATF4可抑制EMT，而IRE1轴则无作用。与这些体外观察结果一致，在前房注射ISRIB还通过抑制SMAD2/3激活减少了晶状体纤维化小鼠模型中的囊下斑块形成。机制上，ISRIB抑制LC3-II转化和P62降解，表明自噬受到抑制。脂质组学显示，对自噬体形成至关重要的磷脂酰乙醇胺（PE）在TGFβ2处理的LECs中下调，并在与ISRIB共同处理时上调。用雷帕霉素诱导自噬可显著挽救ISRIB对间充质基因的抑制作用，而自噬抑制剂氯喹则产生相反的效果。
ER应激，特别是PERK轴，通过自噬和PE代谢促进LECs的EMT，为晶状体纤维化的治疗提供了潜在的治疗靶点。
