Age-Related Macular Degeneration: Genetic Variations and Animal Model

老年性黄斑变性(AMD)在全球老年人群中造成不可逆转的中心性视力丧失。各种研究表明，AMD具有重要的遗传成分。目前的证据支持这样一种假设，即基因变异导致了疾病的易感性。2003年，我们招募了晚期AMD患者和年龄匹配、视网膜正常的对照组，从而启动了这一项目。到目前为止，已经登记了482人，收集了107例AMD组织病理学病例。我们继续分析澳大利亚蓝山眼研究项目的835个DNA样本和美国AREDS项目的534个DNA样本的部分样本，因为一些DNA样本已经用完。我们比较了AMD和对照组候选基因中单核苷酸多态(SNPs)的等位基因频率，并通过体外和/或体内实验对这些SNPs的功能进行了研究。通过这种方法，我们已经确定了AMD的遗传危险因素，以及这些基因变异在疾病发病机制中的可能作用。根据上述方法获得的信息，2007年产生了一个基因工程动物(RD8背景小鼠CCL2/CX3CR1双缺陷，DKO RD8)作为AMD模型。 在2013财年，(1)我们发表了使用DKO RD8小鼠模型作为筛选治疗AMD的治疗化合物的平台的优点(Chu，等人)。《生物工程》2013年5：13-15；张等人。Synapse 67：515-531,2013；Wang等人。(2)我们继续与合作者合作，使用我们的DKO RD8模型来研究AMD的疾病发病机制和治疗方案，评估PDGF-CC(与Xuri Li博士合作)、PEDF(与S.Patricia Becera博士合作)、TSG-6(与Darwin Proockop博士合作：J Neurotis e959,2012)和AREDS II公式(Ramakumar，et al)的作用。J Nutr 143：1129-1135,2013)。(3)我们开始了对DKO RD8小鼠视网膜组织中WNT通路的抗体治疗的研究(与马文欣博士合作)；(4)我们提供了DKO RD8视网膜用于研究microRNAs在AMD中的作用(与王树生博士合作)；(5)我们报道了药物基因组学研究(与Catherine Meyerle博士、Richard Rosen博士和Shree Kurup博士合作)，探讨了抗血管内皮生长因子治疗对AMD及其患者基因型的疗效(Wang等人)。MOL VIS 18：2578-2585,2012)；(6)发表了一项关于TIMP在AMD中作用的大规模SNP关联研究。一项关于DNA修复基因RAD51B在AMD中的作用的类似研究已经完成，论文发表在EUR Hum Genet(2013年2月20日DOI：10.1038/ejhg.2013.14)；(7)在该方案中招募的一些受试者被筛选出他们与AMD相关的基因类型，并将用于与Sheldon Miller和Kapil Bharti博士合作的iPS项目；(8)我们使用了基于基因表达的AMD的系统生物学亚型(Abu-Asab，等人)。(9)在此期间，我们共发表了13篇相关的原创或综述论文，包括IL17RC启动子低甲基化在老年性老年痴呆症中的新发现(与Lai wei和Robert Nussenblatt合作：细胞报告2：1151-1158,2012年)以及与AMD相关的7个新的基因座(与Anand Swaroop博士和AMD基因联盟合作，2013年)。

Age-related macular degeneration (AMD) causes irreversible central visual loss in the aged population worldwide. Various studies suggest that AMD has a significant genetic component. Current evidence supports the hypothesis that gene variation creates a predisposition to the disease. In 2003, we initiated this project by recruiting advanced AMD patients and age-matched control individuals with normal retinas. Up to date, 482 individuals have been enrolled and 107 histopathological cases with AMD have been collected. We continue to analyze parts of 835 DNA samples from the Blue Mountain Eye Study in Australia and 534 DNA samples from the AREDS project in USA because some DNA samples had been ran out. We have compared the allelic frequencies of single nucleotide polymorphisms (SNPs) within candidate genes between AMD and control subjects, followed by functional studies of these SNPs by in vitro and/or in vivo experiments. Through this approach, we have identified genetic risk factors of AMD and the possible roles of these gene variations in the pathogenesis of the disease. Based on the information obtained from the above approaches, a genetically engineered animal (Ccl2/Cx3cr1 double deficiencies on rd8 background mice, DKO rd8) was generated to act as an AMD model in 2007. In FY2013, (1) we published the merits of using the DKO rd8 mouse model as a platform to screen therapeutic compounds for AMD treatment (Chu, et al. Bioengineered 5:13-15, 2013; Zhang, et al. Synapse 67:515-531, 2013; Wang, et al. Apoptosis 17:1144-1155, 2012); (2) we continue working with collaborators to use our DKO rd8 model to study disease pathogenesis and therapeutic options of AMD, by evaluating the roles of PDGF-CC (collaboration with Dr. Xuri Li), PEDF (collaboration with Dr. S. Patricia Becerra), TSG-6 (collaboration with Dr. Darwin Prockop: J Neuroinflamm e959, 2012) and AREDS II formula (Ramakumar, et al. J Nutr 143:1129-1135, 2013). The role of AREDS II formula has been published; (3) we initiated a study of antibody therapy to block WNT pathway in the retinal tissue of the DKO rd8 mice (collaboration with Dr. Wen-xin Ma); (4) we provided DKO rd8 retina for studying the microRNAs role in AMD (collaboration with Dr. Shusheng Wang); (5) we reported the pharmacogenomics study (collaboration with Drs. Catherine Meyerle, Richard Rosen and Shree Kurup) on the efficacy of anti-VEGF therapy on AMD and patients genotypes (Wang, et al. Mol Vis 18:2578-2585, 2012); (6) A large scale SNP association study on the role of TIMPs in AMD was published. A similar study on the role of DNA repair gene RAD51B in AMD is completed and the paper is in Eur Hum Genet (2013 Feb 20. doi: 10.1038/ejhg.2013.14); (7). some subjects recruited in this protocol were screened for their AMD related genotypes and will be used in the iPS project in collaboration with Drs. Sheldon Miller and Kapil Bharti; (8) we used a systems biology subtyping of AMD on the basis of gene expression (Abu-Asab, et al. J Ophthalmology 2013, in press) and reviewed how to distinguish AMD from aging (Ardeljan, Prog Retin Eye Res. 2013 Aug 9. doi:pii: S1350-9462(13)00045-1 Epub ahead of print); (9) in this period, we published a total of 13 relevant original or review papers including the novel findings of hypomethylation of the IL17RC promoter in AMD (collaboration with Dr. Lai Wei & Robert Nussenblatt: Cell Report 2:1151-1158, 2012) and the 7 new loci associated with AMD (collaboration with Dr. Anand Swaroop and the AMD Gene Consortium: Nat Genet 45:433-439, 2013).