Retinal Pigment Epithelial Cells Mitigate the Effects of Complement Attack by Endocytosis of C5b-9.
Retinal Pigment Epithelial Cells Mitigate the Effects of Complement Attack by Endocytosis of C5b-9.
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DOI：
10.4049/jimmunol.1500937
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发表时间：
2015-10-01
期刊：
影响因子：
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通讯作者：
Moss SE
中科院分区：
文献类型：
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作者：
Georgiannakis A;Burgoyne T;Lueck K;Futter C;Greenwood J;Moss SE
视网膜色素上皮（RPE）细胞死亡是年龄相关性黄斑变性的标志。补体激活的替代途径与RPE细胞功能障碍和年龄相关性黄斑变性的损失密切相关;因此，RPE细胞使用分子策略来减轻补体攻击的潜在有害影响至关重要。我们表明，末端补体复合物C5 b-9组装培养的原代猪RPE细胞的基底表面上迅速，但消失超过48小时，没有任何明显的不利影响的细胞。然而，在发动蛋白抑制剂dynasore的存在下，C5 b-9几乎完全保留在细胞表面，这表明，在正常情况下，它是通过内吞途径消除。为了支持这一观点，我们观察到C5 b-9与早期内体标记EEA 1共定位，并且在蛋白酶抑制剂存在下，可以在溶酶体中检测到C5 b-9。阻止RPE细胞对C5 b-9的内吞导致线粒体形态的结构缺陷，这与细胞应激一致。我们的结论是，RPE细胞使用内吞途径，以防止积累的C5 b-9的细胞表面和处理和破坏的C5 b-9通过这种途径是必不可少的RPE细胞的生存。
Retinal pigment epithelial (RPE) cell death is a hallmark of age-related macular degeneration. The alternative pathway of complement activation is strongly implicated in RPE cell dysfunction and loss in age-related macular degeneration; therefore, it is critical that RPE cells use molecular strategies to mitigate the potentially harmful effects of complement attack. We show that the terminal complement complex C5b-9 assembles rapidly on the basal surface of cultured primary porcine RPE cells but disappears over 48 h without any discernable adverse effects on the cells. However, in the presence of the dynamin inhibitor dynasore, C5b-9 was almost completely retained at the cell surface, suggesting that, under normal circumstances, it is eliminated via the endocytic pathway. In support of this idea, we observed that C5b-9 colocalizes with the early endosome marker EEA1 and that, in the presence of protease inhibitors, it can be detected in lysosomes. Preventing the endocytosis of C5b-9 by RPE cells led to structural defects in mitochondrial morphology consistent with cell stress. We conclude that RPE cells use the endocytic pathway to prevent the accumulation of C5b-9 on the cell surface and that processing and destruction of C5b-9 by this route are essential for RPE cell survival.