輔助型T細胞相關細胞激素調控原發性膽道硬化症之研究

Study of Helper T-associated Cytokines on the Regulation of Primary Biliary Cirrhosis

羅家恩(Chia-En Loh)

指導教授 ： 莊雅惠

國立臺灣大學/醫學院/醫學檢驗暨生物技術學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.02881

摘要

原發性膽道硬化症（primary biliary cirrhosis；PBC）為一種肝臟特異性的自體免疫疾病，其病理特徵為淋巴細胞浸潤至門脈三角區且因膽管受到破壞導致膽汁的鬱積，隨著疾病的發展最終走向肝臟衰竭。患者週邊血液之TH1、TH17細胞及IFN-γ與IL-17均較正常人高。在此研究中我們利用本實驗室已建立之xenobiotic (2-OA-OVA)-induced PBC小鼠模式探討發炎細胞激素在PBC致病之角色。首先，我們確定2-OA-OVA/α-GalCer致敏小鼠的肝臟單核細胞經CD3/CD28 抗體刺激後會產生大量的IFN-γ與IL-17，而小鼠肝臟中IFN-γ與IL-17的基因表現量也有上升的情形。接著，我們利用腺相關病毒(adeno-associated virus；AAV)做為載體將不同的細胞激素基因送入小鼠體內，同時誘發小鼠產生PBC，觀察在不同細胞激素的發炎環境下對PBC的影響。我們的結果顯示在給予AAV-mIFN-γ的2-OA-OVA/α-GalCer致敏小鼠，其肝臟中NK細胞及NKT細胞數目顯著上升。此外在不使用α-GalCer的2-OA-OVA致敏小鼠給予AAV-mIFN-γ亦發現肝臟單核細胞數、NK細胞與NKT細胞數上升。給予AAV-mIL-17之2-OA-OVA/α-GalCer致敏小鼠肝臟門脈出現較嚴重的細胞浸潤，但並非淋巴細胞增加。相反地，給予AAV-mIL-4之2-OA-OVA/α-GalCer致敏小鼠，其肝臟單核細胞數明顯降低，但於肝臟切片卻發現肉芽腫數目增加。因此，我們推測IFN-γ能夠活化先天性免疫細胞促使肝臟得以破除免疫耐受性，IL-17則可能造成非淋巴細胞浸潤於門脈，相反地IL-4則有可能透過將TH1免疫反應誘導成TH2反應而降低浸潤至肝臟的免疫細胞數及其活化程度。

關鍵字

原發性膽道硬化症 ； IFN-γ ； IL-17 ； IL-4 ； AAV ； 先天性免疫反應

並列摘要

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by slowly progressive non-suppurative cholangitis caused by immune-mediated destruction of intrahepatic bile ducts. Lymphocytes were recruited to the portal triad accompanied with the presence of antimitochondrial antibodies (AMAs) in the serum of PBC patients, the higher level of proinflammatory cytokines such as IFN-γ can also be detected in serum samples. The frequencies of autoreactive CD4+ T cells, CD8+ T cells and natural killer T (NKT) cells are higher in the liver which suggests a role for the cellular immunity that remain to be determined. CD4+ T cells can be divided into four subsets with distinct functions, including T helper (TH) 1, TH2, TH17 and regulatory T cells. By using a unique compound 2-OA-OVA, accompanied with α-GalCer injection, we established PBC-like syndrome in mice in order to study the cytokines milieus effects on the pathogenesis of PBC. Adeno-associated virus (AAV)-based vector was used to overexpress different cytokines in liver as it only induced minor response in vivo. We found IFN-γ significantly increased NK cells and NKT cells in the liver of 2-OA-OVA/α-GalCer immunized mice. To prevent the IFN-γ production from α-GalCer stimulation, we immunized the mice with 2-OA-OVA without α-GalCer and found that, IFN-γ was still able to induce NK and NKT cells infiltrating to liver and caused activation of NK cells. In contrast to IFN-γ, IL-17 caused the more severe pathological pattern which was not induced by hepatic lymphocytes. Interestingly, IL-4 decreased much of the T cells and NKT cells in liver of immunized mice albeit there were increased granulomas in the liver. We concluded that IFN-γ can induce activation of NK and NKT cells to break immune tolerance when presented antigen by antigen-preseting cells. IL-17 may cause non-lymphoid infiltrating in portal triad, while IL-4 may regulate the inflammatory response by skewing the TH1 responses to TH2 responses.

並列關鍵字

primary biliary cirrhosis ； IFN-γ ； IL-4 ； IL-17 ； AAV ； innate immunity

參考文獻

39. Kunz, M. and S.M. Ibrahim, Cytokines and cytokine profiles in human autoimmune diseases and animal models of autoimmunity. Mediators Inflamm, 2009. 2009: p. 979258.

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