大黄素对视网膜退行性疾病的保护作用机制研究

Age-related macular degeneration (AMD) is one of the major causative factor for blindness. To elucidate the AMD mechanism and explore effective treatment drugs, we have previously generated a knockout mouse model for lysyl oxidase-like 1 protein (LOXL1). The studies on this model have revealed that LOXL1 deficiency does lead to a compromised cross-linking degree of elastic fiber, resulting in a prolapse or abnormality for a number of tissues with an increased suscepbility to macular degeneration. To develop effective drugs for AMD treatment, we have established a drug screen protocol for LOXL1 enhancement.By drug screening, we have identified that emodin is an effective molecule for promoting the LOXL1 level, resulting in an enhanced cross-linking formation of elastic fiber.This proposal aims to determine the treatment efficacy of AMD by evaluating the LOXL1 level and the cross-linking degree of elastic fiber, retinal morphology, immunocytohistology and electroretinographic (ERG)recording in animal models mimicking AMD. The accomplishment of this proposal will not only provide important information for our understanding of macular degeneration mechanism but also provide guidelines for the development of effective treatments.

年龄相关性视网膜黄斑病变（AMD）是致盲因素之一, 为揭示AMD的分子机制和探索其有效的治疗药物，我们前期构建了一个催化弹性蛋白交联的赖酰基氧化酶1（LOXL1）的缺陷小鼠，发现LOXL1缺失的确造成弹性纤维交联度的降低,使视网膜黄斑病变的易感性大大增加。 为寻找治疗AMD的有效药物，我们建立了提高LOXL1表达水平的药物筛选方法，通过药物筛选我们发现大黄素能提高LOXL1的表达量从而促进弹性纤维的交联，并对退行性视网膜有保护作用。本课题将利用模拟AMD的动物模型经大黄素喂养后，测定其LOXL1的表达量及弹性纤维交联度，并结合视网膜组织形态学、免疫组化以及视网膜电图确定视网膜黄斑病变易感性的降低程度，以期能为揭示视网膜黄斑病变的机制提供重要信息，也为发展有效的治疗方法提供理论依据。

本项目利用老年小鼠并采用激光诱导视网膜血管再生的方法建立了视网膜退行性模型，在该视网膜退行性模型中，促进弹性纤维交联度形成的交联酶赖酰氨氧化酶蛋白1（LOXL1）随着年龄的生长急剧下降，造成弹性纤维交联度下降，从而加速了视网膜新生血管的形成，影响了感光系统的正常功能. 通过药物筛选发现大黄素等一系列药物分子重新激活LOXL1基因，干预实验表明，大黄素能刺激LOXL1基因的重新活化和表达。进一步研究揭示，LOXL1的提升对弹性纤维交联度的提升有明显促进作用，从而抑制了新生血管再生，对伴随的视网膜性病变也有明显的缓解和治疗效果。这些数据表明，通过刺激LOXL1基因的激活物（如大黄素）有望成为治疗血管再生诱发的视网膜退行性病的新药。