Delineating the role of TIMP3 in macular degeneration

摘要 视网膜中的视网膜色素上皮（RPE）细胞是许多疾病发病机制的主要部位， 黄斑变性疾病在这些黄斑病变的一个子集中，主要病理表现为 定位于RPE-细胞外基质（RPE-ECM）复合物，表明ECM异常 有助于这些黄斑病变中的潜在疾病机制和RPE功能障碍。事实上， TIMP 3是一种参与ECM调节的基因，其突变导致Sorsby眼底营养不良（SFD）， 遗传性黄斑病，其表型改变类似于年龄相关性黄斑变性（AMD）。在 此外，TIMP 3的罕见变体与AMD的发展密切相关，并且TIMP 3在其下积聚， SFD和AMD中的RPE。总之，这些发现表明TIMP 3生物学在 维持RPE-ECM内稳态和TIMP 3功能障碍有助于一些视网膜病变的病理生理学。 黄斑病变然而，TIMP 3功能障碍对RPE生理学的后果及其在视网膜色素变性中的作用尚不清楚。 黄斑变性的发展尚未确定。在本建议中，我们将阐明 使用患者来源的人- SFD的诱导多能干细胞（hiPSC）-RPE模型。在初步研究中，SFD hiPSC-RPE开发 该疾病的关键病理学表现包括玻璃疣形成和TIMP 3在组织中的积累。 细胞外基质此外，与TIMP 3的生物学功能和病理生理学一致， 影响RPE-ECM完整性的黄斑病变，SFD hiPSC-RPE显示1）促血管生成因子的表达改变， TIMP 3-靶向基质金属蛋白酶（MMP; MMP 2，MMP 14），2）TNF转化酶（TACE）和3） 补体途径基因这些结果支持SFD中TIMP 3功能障碍导致 ECM-转换的失调以及促血管生成和促炎信号的激活， 从而导致玻璃疣形成和RPE介导的CNV。为了验证这一假设，我们将评估 在我们的模型系统中的以下预测1））SFD中ECM中TIMP 3积累增加改变ECM 2）TIMP 3，其通过调节组合物/周转并引发补体活化，进而促进玻璃疣形成， 功能障碍导致MMP、MMP 2和MMP 14的表达/活性增加，从而损害屏障 SFD中RPE细胞的完整性和VEGF释放，以及3）TIMP 3功能障碍导致TNF诱导的促凋亡。 通过RPE的炎症信号传导。这些拟议的实验将提供明确的答案， 玻璃疣生物发生和RPE介导的CNV中的TIMP 3突变/功能障碍最终，我们获得的知识 这项研究将有助于确定针对TIMP 3诱导的SFD中RPE-ECM改变的潜在药物疗法 以及其他黄斑病变

ABSTRACT Retinal pigment epithelium (RPE) cells in the retina are the major site of disease pathogenesis in numerous macular degenerative diseases. In a subset of these maculopathies, the primary pathological manifestations are localized to the RPE-extracellular matrix (RPE-ECM) complex, suggesting that ECM abnormalities contribute to the underlying disease mechanisms and RPE dysfunction in these maculopathies. In fact, mutations in TIMP3, a gene involved in ECM regulation, leads to Sorsby's fundus dystrophy (SFD), an inherited maculopathy with phenotypic alterations that mimic age-related macular degeneration (AMD). In addition, rare variants of TIMP3 are strongly linked to AMD development and TIMP3 accumulates underneath the RPE in both SFD and AMD. Together, these findings suggest that TIMP3 biology plays a central role in maintaining RPE-ECM homeostasis and that TIMP3 dysfunction contributes to pathophysiology of some maculopathies. However, the consequence of TIMP3 dysfunction on RPE physiology and its role in the development of macular degeneration has not been established. In this proposal, we will elucidate the molecular and pathological consequences of TIMP3 mutation in RPE cells using a patient-derived human- induced pluripotent stem cell (hiPSC)-RPE model of SFD. In preliminary studies, SFD hiPSC-RPE develops key pathological manifestation of the disease including, drusen formation and accumulation of TIMP3 in the extracellular matrix. Furthermore, consistent with TIMP3's biological function and pathophysiology of maculopathies affecting RPE-ECM integrity, SFD hiPSC-RPE displays altered expression of 1) pro-angiogenic TIMP3-target matrix metalloproteinases (MMPs; MMP2, MMP14), 2) TNF converting enzyme (TACE) and 3) complement pathway genes. These results support the hypothesis that TIMP3 dysfunction in SFD leads to dysregulation of ECM-turnover and activation of pro-angiogenic and pro-inflammatory signaling that consequently leads to drusen formation and RPE-mediated CNV. To test this hypothesis, we will assess the following predictions in our model system 1)) increased TIMP3 accumulation in ECM in SFD alters ECM composition/turnover and instigates complement activation in turn promoting drusen formation, 2) TIMP3 dysfunction leads to increased expression/activity of MMPs, MMP2 and MMP14, and thereby impaired barrier integrity and VEGF release by RPE cells in SFD and 3) TIMP3 dysfunction leads to TNF-induced pro- inflammatory signaling by RPE. These proposed experiments will provide clear answers the specific role of TIMP3 mutation/dysfunction in drusen biogenesis and RPE-mediated CNV. Ultimately, the knowledge gained in this study will help identify potential drug therapies for targeting TIMP3-induced RPE-ECM alterations in SFD and other maculopathies.!