Sato Ken, Ishikawa Tetsuya, Okumura Akihiko, Yamauchi Taeko, Sato Sayaka, Ayada Minoru, Matsumoto Eiji, Hotta Naoki, Oohashi Tomohiko, Fukuzawa Yoshitaka, Kakumu Shinichi
Division of Gastroenterology, Department of Internal Medicine, Aichi Medical University School of Medicine, Aichi, Japan.
J Gastroenterol Hepatol. 2007 Oct;22(10):1627-32. doi: 10.1111/j.1440-1746.2006.04783.x.
Toll-like receptors (TLRs) are involved in innate immunity. Certain viruses interact with TLRs and mediate antiviral effects as well as immune responses. The aim of this study was to investigate the effect of TLRs on pathogenesis in hepatitis C virus (HCV)-infected patients.
Peripheral blood mononuclear cells (PBMC) and CD14+ (monocytes) or CD14- cells from 25 patients with chronic liver disease and 15 healthy subjects were studied for expression of TLRs 2-9 and cytokines of extracted RNA using real-time PCR. Then TLR expression was examined in HepG2 cells transfected with entire or parts (core-NS3, NS3-NS5B) of the HCV open reading frame. TLR expression was calculated as the relative mRNA levels.
Expression of TLRs 4, 7 and 8 in CD14+ cells of PBMC was increased in patients. Levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and IL-12 p35 for PBMC were also increased in patients. When PBMC were incubated with HCV core protein, enhancement of TLR2 expression and suppression of TLR4 and TLR7 were noted in patients. Similar alteration of TLRs expression was observed in controls. Among HepG2 transfectants, only TLR3 expression was changed; it was suppressed in entire gene transfectant and enhanced in core-NS3 transfectant. Expression of some proteins related to the TLR signaling pathway was suppressed in the entire gene transfectant.
The results suggest a correlation between expression levels of TLRs and cytokines, and chronic HCV infection. TLR3 recognizes double-stranded RNA and induces type 1 interferon synthesis. Collectively, suppressed expression of TLR3 in cells transfected with entire HCV may be responsible for continuous HCV infection, although a part of the HCV gene enhances its expression.
Toll样受体（TLRs）参与固有免疫。某些病毒与TLRs相互作用，介导抗病毒效应以及免疫反应。本研究的目的是调查TLRs对丙型肝炎病毒（HCV）感染患者发病机制的影响。
使用实时聚合酶链反应（PCR），对25例慢性肝病患者和15名健康受试者的外周血单个核细胞（PBMC）以及CD14+（单核细胞）或CD14-细胞进行研究，以检测TLRs 2 - 9的表达以及提取RNA中的细胞因子。然后在转染了HCV开放阅读框全部或部分（核心-NS3、NS3-NS5B）的HepG2细胞中检测TLR表达。TLR表达以相对mRNA水平计算。
患者PBMC的CD14+细胞中TLRs 4、7和8的表达增加。患者PBMC的肿瘤坏死因子（TNF）-α、白细胞介素（IL）-6和IL-12 p35水平也升高。当PBMC与HCV核心蛋白孵育时，患者中TLR2表达增强，TLR4和TLR7表达受到抑制。在对照组中也观察到TLRs表达的类似变化。在HepG2转染细胞中，只有TLR3表达发生改变；在全基因转染细胞中其表达受到抑制，而在核心-NS3转染细胞中表达增强。全基因转染细胞中一些与TLR信号通路相关的蛋白表达受到抑制。
结果表明TLRs表达水平与细胞因子以及慢性HCV感染之间存在关联。TLR3识别双链RNA并诱导I型干扰素合成。总体而言，转染了完整HCV的细胞中TLR3表达受到抑制可能是导致HCV持续感染的原因，尽管HCV基因的一部分会增强其表达。
