Department of Ophthalmology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Cell Commun Signal. 2024 Jul 11;22(1):359. doi: 10.1186/s12964-024-01710-x.
Bietti crystalline dystrophy (BCD) is an inherited retinal degeneration disease caused by mutations in the CYP4V2 gene. Currently, there is no clinical therapy approach available for BCD patients. Previous research has suggested that polyunsaturated fatty acids (PUFAs) may play a significant role in the development of BCD, implicating the involvement of ferroptosis in disease pathogenesis. In this work, we aimed to investigate the interplay between ferroptosis and BCD and to detect potential therapeutic strategies for the disease.
Genetic-edited RPE cell line was first established in this study by CRISPR-Cas9 technology. Cyp4v3 (the homologous gene of human CYP4V2) knock out (KO) mice have also been used. Lipid profiling and transcriptome analysis of retinal pigment epithelium (RPE) cells from Cyp4v3 KO mice have been conducted. Ferroptosis phenotypes have been first investigated in BCD models in vitro and in vivo, including lipid peroxidation, mitochondrial changes, elevated levels of reactive oxygen species (ROS), and altered gene expression. Additionally, an iron chelator, deferiprone (DFP), has been tested in vitro and in vivo to determine its efficacy in suppressing ferroptosis and restoring the BCD phenotype.
Cyp4v3 KO mice exhibited progressive retinal degeneration and lipid accumulation, similar to the BCD phenotype, which was exacerbated by a high-fat diet (HFD). Increased levels of PUFAs, such as EPA (C22:5) and AA (C20:4), were observed in the RPE of Cyp4v3 KO mice. Transcriptome analysis of RPE in Cyp4v3 KO mice revealed changes in genes involved in iron homeostasis, particularly an upregulation of NCOA4, which was confirmed by immunofluorescence. Ferroptosis-related characteristics, including mitochondrial defects, lipid peroxidation, ROS accumulation, and upregulation of related genes, were detected in the RPE both in vitro and in vivo. Abnormal accumulation of ferrous iron was also detected. DFP, an iron chelator administration suppressed ferroptosis phenotype in CYP4V2 mutated RPE. Oral administration of DFP also restored the retinal function and morphology in Cyp4v3 KO mice.
This study represented the first evidence of the substantial role of ferroptosis in the development of BCD. PUFAs resulting from CYP4V2 mutation may serve as substrates for ferroptosis, potentially working in conjunction with NCOA4-regulated iron accumulation, ultimately leading to RPE degeneration. DFP administration, which chelates iron, has demonstrated its ability to reverse BCD phenotype both in vitro and in vivo, suggesting a promising therapeutic approach in the future.
Bietti 结晶性营养不良（BCD）是一种由 CYP4V2 基因突变引起的遗传性视网膜退行性疾病。目前，尚无针对 BCD 患者的临床治疗方法。先前的研究表明，多不饱和脂肪酸（PUFAs）可能在 BCD 的发展中起重要作用，提示铁死亡参与了疾病的发病机制。在这项工作中，我们旨在研究铁死亡与 BCD 之间的相互作用，并发现该疾病的潜在治疗策略。
本研究首先通过 CRISPR-Cas9 技术建立了经基因编辑的 RPE 细胞系。还使用了 Cyp4v3（人类 CYP4V2 的同源基因）敲除（KO）小鼠。对 Cyp4v3 KO 小鼠的视网膜色素上皮（RPE）细胞进行了脂质谱和转录组分析。在体外和体内的 BCD 模型中首次研究了铁死亡表型，包括脂质过氧化、线粒体变化、活性氧（ROS）水平升高和基因表达改变。此外，还在体外和体内测试了一种铁螯合剂——地拉罗司（DFP），以确定其抑制铁死亡和恢复 BCD 表型的功效。
Cyp4v3 KO 小鼠表现出进行性视网膜变性和脂质积累，类似于 BCD 表型，而高脂肪饮食（HFD）则使其加重。在 Cyp4v3 KO 小鼠的 RPE 中观察到多不饱和脂肪酸（如 EPA[C22：5]和 AA[C20：4]）水平升高。Cyp4v3 KO 小鼠 RPE 的转录组分析显示，铁稳态相关基因发生变化，特别是 NCOA4 上调，免疫荧光也证实了这一点。在体外和体内均检测到 RPE 中铁死亡相关特征，包括线粒体缺陷、脂质过氧化、ROS 积累和相关基因上调。还检测到亚铁的异常积累。铁螯合剂 DFP 的给药抑制了 CYP4V2 突变的 RPE 中的铁死亡表型。DFP 的口服给药也恢复了 Cyp4v3 KO 小鼠的视网膜功能和形态。
本研究首次证明了铁死亡在 BCD 发展中的重要作用。CYP4V2 突变导致的多不饱和脂肪酸可能作为铁死亡的底物，可能与 NCOA4 调节的铁积累协同作用，最终导致 RPE 变性。DFP 作为一种铁螯合剂，在体外和体内均显示出逆转 BCD 表型的能力，提示这是一种有前途的治疗方法。
