Wu Xin-yi, Gao Jian-lu, Ren Mei-yu
Department of Ophthalmology, Qilu Hospital, Shandong University, Jinan 250012, China.
Chin Med J (Engl). 2007 May 20;120(10):893-7.
Toll-like receptors play an important role in the human immune system. This study was conducted to investigate the expression profiles and function of Toll-like receptor (TLR) 1 - 9 in human corneal epithelium.
The expression of TLR1 - 9 mRNA in 20 human donor corneal epithelia samples abraded during photorefractive keratotomy (PRK) and cultivated telomerase-immortalized human corneal epithelial cells (THCEs) was examined by semi-quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) analysis. Human peripheral blood mononuclear cells (PBMCs) were used as positive controls. The expression of the TLR2 and TLR4 proteins was detected by Western analysis. ELISA was used to detect IL-8 secretion from THCEs challenged with ligands for TLR3 and TLR4 with and without antibody blockade.
The expression of TLR1 - 9 at the mRNA level was detected in the epithelia of 20 patients and in THCE. Significant differences among individuals were observed. One patient was found to lack of the expression of TLR3, 4, 6 and 8, whereas another did not express TLR5. The expression of TLR2 and TLR4 protein was detected in human corneal epithelial cells. As THCE cells express TLR1 - 9, cells were challenged with lipopolysaccharides (LPS) and poly I:C to determine whether TLR4 and TLR3 were functional. The results showed that secretion of IL-8 by cells stimulated with LPS and Poly I:C was 7 to 10 fold greater than secretion by unchallenged cells. Blocking TLR4 with an anti-TLR4 antibody significantly inhibited the LPS-induced IL-8 production by THCE (P < 0.05).
Human corneal epithelial cells express multiple TLRs and are able to recognize LPS and poly I:C. Different expression profiles among individuals suggest that differences in the susceptibilities and sensitivities to bacterial and viral infection in human populations relate to different patterns of TLR expression.
Toll样受体在人类免疫系统中发挥重要作用。本研究旨在调查Toll样受体（TLR）1 - 9在人角膜上皮中的表达谱及功能。
通过半定量逆转录聚合酶链反应（RT-PCR）分析，检测20例在准分子激光原位角膜磨镶术（PRK）过程中被刮除的人供体角膜上皮样本以及培养的端粒酶永生化人角膜上皮细胞（THCEs）中TLR1 - 9 mRNA的表达。人外周血单个核细胞（PBMCs）用作阳性对照。通过蛋白质印迹分析检测TLR2和TLR4蛋白的表达。采用酶联免疫吸附测定（ELISA）检测在有或无抗体阻断的情况下，用TLR3和TLR4配体刺激的THCEs分泌白细胞介素-8（IL-8）的情况。
在20例患者的上皮组织及THCE中检测到了TLR1 - 9在mRNA水平的表达。个体间存在显著差异。发现1例患者缺乏TLR3、4、6和8的表达，而另1例患者不表达TLR5。在人角膜上皮细胞中检测到了TLR2和TLR4蛋白的表达。由于THCE细胞表达TLR1 - 9，因此用脂多糖（LPS）和聚肌苷酸:聚胞苷酸（poly I:C）刺激细胞，以确定TLR4和TLR3是否具有功能。结果显示，LPS和Poly I:C刺激的细胞分泌IL-8的量比未刺激细胞分泌量高7至10倍。用抗TLR4抗体阻断TLR4可显著抑制THCE中LPS诱导的IL-8产生（P < 0.05）。
人角膜上皮细胞表达多种TLR，并且能够识别LPS和poly I:C。个体间不同的表达谱表明，人群中对细菌和病毒感染的易感性和敏感性差异与TLR表达的不同模式有关。
