视网膜色素变性并发特征性前囊膜下白内障的分子基础

Posterior subcapsular opacity（PSC）derived from retinitis pigmentosa(RP) are common in practice. However, with our long-term observation, anterior subcapsular cataract (ASC) arising in RP was thought to be another typical manifestation of this disease. This type of subcapsular opacity was located in the central anterior field of lens just in correspondence with the pupil area. Previous studies reported an increased concentration of inflammatory factors or cytokines in aqueous humor in RP cases. We infer that the molecular mechanism of ASCs, which is characteristically located in the pupil zone, involved in proliferation, differentiation and epithelial-mesenchymal transition of the anterior lens epithelial cells (LECs). Besides, it may be connected to the change of lens metabolism and nutrition microenvironment as a result of the inflammatory reaction in retinitis pigmentosa. And most importantly, the featured location of ASC may be closely related to the rhodopsin metabolite accumulation from photoreceptors apoptosis and retinal pigment epithelium dysfunction.We propose that abnormal cell signaling pathway was stimulated by the metabolite which was activated by rays of light in pupillary zone. In this study, detailed clinical data of retinitis pigmentosa with ASC were recorded. Aqueous humor, capsulorhexis specimans and some cortex from the cases that underwent phacoemulsification were obtained during operation. The markers of EMT and proliferation in LECs are planed to be detected by immunocytochemistry and immunofluorescence techniques. To have a further investigation on the molecular mechanism(s) of ASCs in RP patients, inflammatory factors, cytokines levels and retinoic acid (RA) concentrations in aqueous homor will be measured. The ocular partial pressure of oxygen (PO2) is also to be determined in anterior chamber, and in lens. Besides, the gene expression profiling, microRNA sequencing and DNA methylation in the LECs will be determined and analyzed using bioinformatics platform. All those are performed to find out the molecular biological mechanism(s) of ASCs and to analyze the key pathogenic factor(s) of ASCs formation. We looking forward to provide a valuable target for non-operative interference and make a contribution to a new attempt for preservation of residual visual acuity in retinitis pigmentosa population on the basis of our study.

视网膜色素变性(RP)常导致后囊下型（PSC）并发性白内障，课题组经长期临床观察发现前囊下型(ASC)也较多见，表现为特征性的瞳孔区前囊下混浊。现有研究表明RP导致感光细胞变性、降解可引起眼内炎症因子和细胞因子表达增加。我们认为感光细胞代谢产物累积于晶状体和房水中引起眼内微环境变化，可能导致在光照情况下发生晶状体上皮细胞（LEC）增殖分化和上皮间质转化（EMT），导致瞳孔区ASC。本课题选择RP并发ASC需进行手术治疗的病例，首先检测晶状体前囊膜LEC增殖分化与EMT信号表达变化；并且测定房水中炎症因子和生长因子的表达水平以及感光细胞视紫红质的代谢产物维甲酸等含量变化，结合术中房水及晶状体中氧分压差异测定，综合分析ASC发生的相关分子基础。同时进一步检测LEC的基因表达谱、miRNA表达谱和基因组DNA甲基化变化水平，明确RP病程中导致LEC增殖分化和EMT的信号转导调控途径。

视网膜色素变性（retinitis, pigmentosa, RP）是一组遗传异质性视网膜疾病，世界范围的患病率约为1/4000，大约20％至30％的RP患者同时合并其他眼病，其中以RP相关晶体异常较为常见，包括后囊膜下性白内障（posterior subcapsular cataract, PSC）、前囊膜下型白内障（anterior subcapsular cataract, ASC）和晶状体悬韧带异常,且白内障的平均发病年龄较正常人小。在以往的病例报道中，与RP相关的PSC相比，RP相关的ASC要更为少见。然而据课题组临床观察，ASC在RP患者中同样常见，位于瞳孔区晶状体前囊膜下混浊对残存视野产生损害，对此类患者视功能造成严重损害。本研究观察了RP相关ASC患者晶状体的特征性形态学变化及其临床特点，并对于其发生的具体机制进行了探索研究。RP相关ASC患者前囊膜组织的LECs内，hsa-let-7c-3p表达下调，高迁移率族蛋白A2（HMGA2）表达上调，这与在TGFβ2诱导的LECs的EMT模型中观察到的变化一致，提示hsa-let-7c -3p和HMGA2可能参与调节RP并发性ASC的形成过程。进而研究通过细胞模型和人囊膜组织样本证实了hsa-let-7c-3p的负性抑制钙粘蛋白11（cadherin-11, CDH11）基因在转录后水平（而非转录水平）显着抑制LECs的增殖和迁移，同时延缓TGFβ2诱导的EMT作用。此外，HMGA2调节TGFβ2诱导的LECs的EMT过程中TGFβ/ Smad，TGFβ/ ERK和Notch信号通路。研究结果共同表明hsa-let-7c-3p和HMGA2在TGFβ2诱导的EMT中具有显着作用，并且可能是阻止RP并发ASC的LECs发生EMT过程，从而保存此类患者残余视力的治疗靶点。