Ebihara Nobuyuki, Chen Lizhong, Tokura Tomoko, Ushio Hiroko, Iwatsu Minoru, Murakami Akira
Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan.
Ophthalmic Res. 2007;39(3):155-63. doi: 10.1159/000103235. Epub 2007 May 25.
Retinal pigment epithelial cells (RPE cells) are key players in the first-line defense against invading organisms such as viruses and bacteria. The interaction between RPE cells and viral or bacterial components is very important for clearance of these organisms. Toll-like receptors are a family of recognition receptors involved in innate immunity. Each TLR acts as a primary sensor of conserved microbial components and drives the induction of specific biological responses. TLR 3 is involved in the recognition of viral components, such as double-stranded RNA (dsRNA) and poly(I:C), while TLR 9 recognizes viral or bacterial DNA without methylation at CpG motifs. In the present study, we investigated the expression and function of TLR 3 and 9 in RPE cells. PCR analysis revealed expression of genes for TLR 3 and 9 in RPE cells. Expression of TLR 3 and 9 protein was detected in RPE cells by flow cytometry. TLR 3 and 9 showed strong intracellular expression. To detect angiogenetic factors produced by RPE cells, culture supernatant was examined with the Human Angiogenesis Antibody Array, which can simultaneously detect 20 different angiogenetic factors including cytokines, chemokines, soluble cytokine receptors, and growth factors. RPE cells showed high production of interleukin-8 (IL-8) and monocyte chemotactic protein-I (MCP-I). Furthermore, stimulation of RPE cells with the dsRNA analogue poly(I:C) enhanced the secretion of IL-8 and MCP-I, as well as enhancing the expression of junctional adhesion molecule-I (Jam-I) and intracellular adhesion molecule-I (ICAM-I), and promoted the adhesion of monocyte to these cells. In contrast, stimulation with the CpG-DNA motif only enhanced the secretion of IL-8. However, CpG-DNA motif enhanced phagocytosis in RPE cells. These results may indicate that TLR 3 and 9 play a distinct role in the inflammatory response that clears viruses from the retina.
视网膜色素上皮细胞（RPE细胞）是抵御病毒和细菌等入侵生物体的一线防御中的关键参与者。RPE细胞与病毒或细菌成分之间的相互作用对于清除这些生物体非常重要。Toll样受体是参与先天免疫的一类识别受体。每个TLR作为保守微生物成分的主要传感器，并驱动特定生物反应的诱导。TLR 3参与识别病毒成分，如双链RNA（dsRNA）和聚肌胞苷酸（poly(I:C)），而TLR 9识别在CpG基序处未甲基化的病毒或细菌DNA。在本研究中，我们研究了TLR 3和9在RPE细胞中的表达和功能。PCR分析显示RPE细胞中TLR 3和9的基因表达。通过流式细胞术在RPE细胞中检测到TLR 3和9蛋白的表达。TLR 3和9显示出强烈的细胞内表达。为了检测RPE细胞产生的血管生成因子，用人血管生成抗体阵列检测培养上清液，该阵列可以同时检测20种不同的血管生成因子，包括细胞因子、趋化因子、可溶性细胞因子受体和生长因子。RPE细胞显示出高表达白细胞介素-8（IL-8）和单核细胞趋化蛋白-1（MCP-1）。此外，用dsRNA类似物聚肌胞苷酸（poly(I:C)）刺激RPE细胞可增强IL-8和MCP-1的分泌，以及增强连接黏附分子-1（Jam-1）和细胞间黏附分子-1（ICAM-1）的表达，并促进单核细胞与这些细胞的黏附。相比之下，用CpG-DNA基序刺激仅增强了IL-8的分泌。然而，CpG-DNA基序增强了RPE细胞中的吞噬作用。这些结果可能表明TLR 3和9在从视网膜清除病毒的炎症反应中发挥不同的作用。
