摘要
全球已有超過一億七千萬人口感染C 型肝炎病毒，其所造成之疾病與防治措施已是全球衛生不容忽視的重要課題。持續感染HCV 通常會造成慢性肝炎、肝硬化甚至造成肝癌的發生。HCV 可藉由複雜的機制破壞或逃脫免疫系統而造成持續性感染，其中的一種策略即是干擾免疫系統抗病毒干擾素（IFN）的產生。甲型干擾素（Interferon-α）與另一種抗病毒藥物ribavirin（一種核苷酸異構物可影響DNA 及RNA 病毒的複製） 的合併使用，在清除C 型肝炎病毒的治療上是已知最具臨床效果的方式。 雖然Interferon-α/ribavirin是現在臨床上用於治療C型肝炎患者的主要方法，但患者本身的免疫因子及病毒本身特性均可左右Interferon-α/ribavirin合併使用的療效。除此之外，從目前已知的臨床研究中發現，在抗病毒治療過程中，患者免疫反應傾向於Th1 免疫反應模式的激發與HCV清除息息相關。Th1免疫反應主要是由Tc細胞執行細胞毒殺功能，清除受到病毒感染的細胞。而激發Tc細胞的主要訊息，則是由T cell receptor及帶有外來抗原的第一型human leukocyte antigen (HLA-ABC)分子的結合而活化。因此患者本身HLA-ABC的表現，可能扮演了一個與治療效果有關的重要因子。欲了解HLA-ABC表現以及IFN調控於慢性C型肝炎患者當中所可能扮演的角色，我們在本研究當中進行了兩部分的初步探討: 第一，我們長期追蹤接受甲型干擾素與ribavirin合併治療患者，在療程當中HLA-ABC 在B細胞以及單核球細胞 (monocyte) 上的表現量變化情形。研究結果發現，對具有病毒療效的患者，HLA-ABC在B細胞上的表現量在治療中會顯著調升；對未具有病毒療效者，HLA-ABC在B細胞的表現量則不變。此結果顯示免疫反應偏向Th1或許發生在某些特定的病患，且和會受到HCV感染的B細胞上HLA-ABC的調升有關。第二，我們觀測干擾素調控因子3 (interferon regulatory factor 3, IRF-3) 一個能啟動IFN系統的重要抗病毒訊息傳遞分子，在肝臟細胞當中的調控情形，藉此了解IRF-3在in vitro以及病患的IFN系統當中的調控功能。我們所採用的方法是根據Foy E. 等人的研究 (science 2003; 300(5622):1145-8)，他們於實驗室中證明HCV所產生的非結構蛋白3/4A (NS3/4A)具有serine proteinase功能會抑制IRF-3的磷酸化及活化。我們以dsRNA的類似物poly I:C刺激HeLa 細胞以及肝癌細胞株，評估內源性IRF-3的活化情形。結果顯示HeLa細胞於poly I:C刺激後4小時，IRF-3及其下游所調控的基因的表現均會被活化，但是肝癌細胞株包括Huh7、HepG2、Hep3B及PLC則無此現象。令我們感到驚訝，肝癌細胞株經過poly I:C刺激之後沒有觀察到受到活化的IRF-3。依結果我們發現poly I:C活化IRF-3是侷限於某些特定的細胞株，我們推論此應與細胞表面上TLR-3表現量多寡有關，或有屬於特定細胞的TLR-3 dependent 的訊息傳遞路徑。 因此在我們進行研究IRF-3在C型肝炎患者肝細胞當中的調控情形前，IRF-3 在肝癌細胞株當中的訊息傳遞路徑仍需要做更深入的研究於探討。

Abstract
Hepatitis C viruses (HCV) infect more than 170 million people worldwide and persistent HCV infection can resulted in chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. One of the strategies that HCV use to subvert or evade the host immune system for the persistent infection is to disturb the production of antiviral interferon (IFN). Combination of IFN-α and ribavirin (a guanosine analog that can inhibit DNA and RNA virus replication) is the current standard treatment for chronic hepatitis C. Although IFN-α/rivavirin treatment is the main therapeutic strategy for chronic HCV patients, both viral and host factors can affect the clinical outcome of the therapy. In addition, clinical studies have revealed that infected patients, who successfully eradicated the virus, developed immunity towards Th1 biased responses and maintained the Th1 cytokines during IFN-α/rivavirin treatment. It has been well documented that the Th1 cell is responsible for helping of many cell-mediated antiviral functions including the activation and proliferation of cytotoxic-T (Tc) cells. As Tc cells are activated when interact with HLA class I on the antigen presenting cells including viral infected cells, the regulation of HLA class I on the cell surface may play a role in predicting the IFN-α/rivavirin therapeutic outcome. To understand the possible role of HLA expression and IFN regulation in HCV infected patients, we did two preliminary investigations in the present study: First, we longitudinally followed up the levels of HLA-ABC surface expression on B cells and monocytes from patients receiving IFN-α/rivavirin therapy. Our result demonstrated that the expression of HLA-ABC on B cells was up-regulated during IFN-α/rivavirin treatment in virological responders but not in virological non-responders, suggesting that the augmentation of effective Th1 response may be patient specific and correlate with elevated levels of HLA-ABC on B cells infected with HCV. Second, we characterized the levels of activated interferon regulatory factor 3 (IRF3), a key cellular antiviral signaling molecule that activates the IFN system, in cells of hepatic origin in order to address the role of IRF3 in the regulation of IFN both in vitro and in patients infected with HCV. Following the methods and the in vitro experiment system established by Foy E., et al. (Science. 2003 May 16; 300(5622):1145-8), who demonstrated that HCV non-structure protein-NS3/4A serine protease is able to block the phosphorylation and effector function of interferon regulatory factor 3 (IRF-3), we examined the phosphorylation of endogenous IRF-3 in HeLa and several hepatoma cell lines by using dsRNA analog (poly I:C) as a stimulator. Our results indicated that poly I:C treatment for 4 hrs induced IRF-3 phosphorylation and activated the downstream target genes in HeLa cells but not in hepatoma cell lines, including Huh7, HepG2, Hep3B and PLC. It was surprising that in our system we did not observe IRF3 activation in hepatoma cell lines by poly I:C. The result suggested that activation of IRF3 was cell type specific through polyI:C stimulation, which may depend on the levels of Toll like receptor 3（TLR-3）expression on the cell surface or involve TLR-3 independent pathway. Before we investigate the function of IRF-3 in HCV infected patients, the signal pathway of IRF-3 in hepatocyte cell lines need to be carefully defined and investigated.

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