Induction of angiogenic cytokine expression in cultured RPE by ingestion of oxidized photoreceptor outer segments
Induction of angiogenic cytokine expression in cultured RPE by ingestion of oxidized photoreceptor outer segments
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DOI：
10.1167/iovs.02-0742
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发表时间：
2003-04-01
影响因子：
4.4
通讯作者：
Redmond, HP
中科院分区：
文献类型：
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作者：
Higgins, GT;Wang, JH;Redmond, HP
目的.正常衰老与视网膜色素上皮（RPE）中脂褐素色素的积累有关。这可能是由于吞噬作用和氧化的光感受器外节（POS）的不完全降解。本研究旨在确定吞噬紫外线照射的POS（人工脂褐素）是否会增加RPE中各种趋化性和血管生成细胞因子的表达。将ARPE-19细胞暴露于乳胶珠（0.76 μ m）、未处理的牛POS和UV照射的POS（Ox-POS; 2 × 10（7）/mL），并在18和36小时收集上清液。通过ELISA测定上清液中的IL-8、单核细胞趋化蛋白-（MCP）-1和TNF-α。蛋白质合成和NF κ B活性分别被放线菌素D和SN 50抑制。通过流式细胞术评估吞噬作用和细胞内活性氧的产生。还进行了共聚焦和电子显微镜研究以验证吞噬作用和细胞完整性。单纯POS组IL-8和MCP-1水平降低（IL-8：473.76 +/- 66.9 pg/mL，P = 0.0005; MCP-1：550.1 +/- 21.8 pg/mL，P = 0.0001），但在Ox-POS组中增加8 +/-164.9pg/mL; MCP-1：1772.28 +/-65.19pg/mL）与对照组（IL-8：741.09 +/-39.8pg/mL; MCP-1：1413.47 +/-38.4pg/mL）和乳胶珠粒组（数据未显示）进行比较。TNF-α水平不受影响。在12小时（但不是在6小时），Ox-POS组中的ROS增加。观察到的细胞因子增加依赖于从头蛋白质合成和NF-κ B依赖性。RPE摄入氧化的牛POS刺激趋化和血管生成因子IL-8和MCP-1的表达，这些因子具有直接促进血管生成的能力，或通过免疫细胞如巨噬细胞的积累间接促进血管生成的能力，巨噬细胞本身可以释放血管生成促进剂并降解布鲁赫膜。这可能在渗出性AMD的发展中具有重要意义。
PURPOSE. Normal aging is associated with accumulation of lipofuscin pigment in the retinal pigment epithelium (RPE). This may occur as a result of phagocytosis and incomplete degradation of oxidized photoreceptor outer segments (POS). This study was undertaken to determine whether phagocytosis of UV-irradiated POS (artificial lipofuscin) would increase expression in the RPE of various chemotactic and angiogenic cytokines.METHODS. ARPE-19 cells were exposed to latex beads (0.76 mum), naive bovine POS, and UV-irradiated POS (Ox-POS; 2 x 10(7)/mL), and supernatants were collected at 18 and 36 hours. The supernatants were assayed for IL-8, monocyte chemotactic protein-(MCP)-1, and TNF-alpha by ELISA. Protein synthesis and NFkappaB activity were inhibited by actinomycin D and SN50, respectively. Phagocytosis and generation of intracellular reactive oxygen species were assessed by flow cytometry. Confocal and electron microscopy studies were also performed to verify phagocytosis and cellular integrity.RESULTS. IL-8 and MCP-1 levels were decreased in the naive POS group (IL-8: 473.76 +/- 66.9 pg/mL, P = 0.0005; MCP-1: 550.1 +/- 21.8 pg/mL, P = 0.0001), but were increased in the Ox-POS group (IL-8: 1348.8 +/- 164.9 pg/mL; MCP-1: 1772.28 +/- 65.19 pg/mL) compared with the control (IL-8: 741.09 +/- 39.8 pg/mL; MCP-1: 1413.47 +/- 38.4 pg/mL) and latex bead groups (data not shown). TNF-a levels were not affected. At 12 hours (but not at 6 hours), ROS were increased in the Ox-POS group. The cytokine increases observed were dependent on de novo protein synthesis and were NF-kappaB dependent.CONCLUSIONS. Ingestion by RPE of oxidized bovine POS stimulates expression of the chemotactic and angiogenic factors IL-8 and MCP-1 that have the capability to promote angiogenesis directly, or indirectly through the accumulation of immune cells such as macrophages, which themselves may release angiogenic promoters and degrade Bruch's membrane. This, may be of significance in the development of exudative AMD.