Proteomic Interactions in the Mouse Vitreous-Retina Complex

Purpose
Human vitreoretinal diseases are due to presumed abnormal mechanical interactions between the vitreous and retina, and translational models are limited. This study determined whether nonstructural proteins and potential retinal biomarkers were expressed by the normal mouse vitreous and retina.
Methods
Vitreous and retina samples from mice were collected by evisceration and analyzed by liquid chromatography-tandem mass spectrometry. Identified proteins were further analyzed for differential expression and functional interactions using bioinformatic software.
Results
We identified 1,680 unique proteins in the retina and 675 unique proteins in the vitreous. Unbiased clustering identified protein pathways that distinguish retina from vitreous including oxidative phosphorylation and neurofilament cytoskeletal remodeling, whereas the vitreous expressed oxidative stress and innate immunology pathways. Some intracellular protein pathways were found in both retina and vitreous, such as glycolysis and gluconeogenesis and neuronal signaling, suggesting proteins might be shuttled between the retina and vitreous. We also identified human disease biomarkers represented in the mouse vitreous and retina, including carbonic anhydrase-2 and 3, crystallins, macrophage inhibitory factor, glutathione peroxidase, peroxiredoxins, S100 precursors, and von Willebrand factor.
Conclusions
Our analysis suggests the vitreous expresses nonstructural proteins that functionally interact with the retina to manage oxidative stress, immune reactions, and intracellular proteins may be exchanged between the retina and vitreous. This novel proteomic dataset can be used for investigating human vitreoretinopathies in mouse models. Validation of vitreoretinal biomarkers for human ocular diseases will provide a critical tool for diagnostics and an avenue for therapeutics.

研究目的
人类玻璃体视网膜疾病（vitreoretinal diseases）的病因被认为是玻璃体（vitreous）与视网膜（retina）之间异常的机械相互作用，而相关转化模型十分有限。本研究旨在探究正常小鼠玻璃体与视网膜是否表达非结构蛋白（nonstructural proteins）及潜在的视网膜生物标志物（biomarkers）。

研究方法
研究人员通过眼球摘除术采集小鼠玻璃体与视网膜样本，并采用液相色谱-串联质谱法（liquid chromatography-tandem mass spectrometry）对样本进行分析。随后借助生物信息学软件（bioinformatic software）对鉴定出的蛋白进行差异表达及功能相互作用分析。

研究结果
本研究共在视网膜中鉴定出1680种独特蛋白，在玻璃体中鉴定出675种独特蛋白。无偏聚类分析显示，区分视网膜与玻璃体的蛋白通路存在显著差异：视网膜富含氧化磷酸化（oxidative phosphorylation）及神经丝细胞骨架重塑（neurofilament cytoskeletal remodeling）相关通路，而玻璃体则高表达氧化应激（oxidative stress）与先天免疫（innate immunology）通路。部分细胞内蛋白（intracellular proteins）通路在视网膜与玻璃体中均存在，如糖酵解与糖异生（glycolysis and gluconeogenesis）及神经元信号通路（neuronal signaling），这提示蛋白可能在视网膜与玻璃体之间发生转运。本研究同时鉴定出小鼠玻璃体与视网膜中存在的人类疾病相关生物标志物，包括碳酸酐酶2与3（carbonic anhydrase-2 and 3）、晶状体蛋白（crystallins）、巨噬细胞抑制因子（macrophage inhibitory factor）、谷胱甘肽过氧化物酶（glutathione peroxidase）、过氧还蛋白（peroxiredoxins）、S100前体蛋白（S100 precursors）及血管性血友病因子（von Willebrand factor）。

研究结论
本研究分析结果表明，玻璃体可表达非结构蛋白，这些蛋白可与视网膜发生功能性相互作用以调控氧化应激与免疫反应；同时视网膜与玻璃体之间可发生细胞内蛋白的交换。本数据集为全新的蛋白质组学（proteomic）数据集，可用于在小鼠模型中研究人类玻璃体视网膜疾病（vitreoretinopathies）。针对人类眼部疾病的玻璃体视网膜生物标志物进行验证，将为临床诊断提供关键工具，同时为治疗手段开发开辟新路径。