肝脏γδT细胞功能模式及其在2型自身免疫性肝炎中的意义

Characters)：While extensive studies have focused on the pathogenesis and treatment of autoimmune hepatitis (AIH), it is expected that specific T cell immunity may be the key to uncover the mystery of this disease. The increased number of γδT cells in AIH patients has been reported, but the underlying mechanism is unknown. IL-17 has been demonstrated to be a critical factor involved in experimental autoimmune hepatitis. However, there is controversy with respect to the role of Th17 cells whether it is pathogenic or protective.The underlying mechanism of Treg cells in protecion of male mice from type 2 autoimmune hepatitis remains unknown. γδT lymphocytes have been proved to be multifunctional cells as well as an important source of Th17 or Treg. Herein, we intend to study the immunological roles of γδT cells in a murine model of type 2 AIH - xenoimmunization with human antigens. At different time points of the experimental AIH, the localization, quantification and cytokine production of hepatic γδT cells will be investigated. The change of their killing ability will be determined in vitro. The specific cross-talk among γδT cells and liver cells, NKT cells in AIH will also be explored. Further, we will charaterize the quantitation, localization and cytokine expression of hepatic γδT cells in liver biopsy specimen of patients with type 2 AIH (compared with those of patients with type 1 AIH or chronic hepatitis B). At home and abroad, this hypothesis is novel and practical, with supporting references and mature technology we have established. It is supposed to help clarify the cellular basis of immunopathogenisis of AIH. Specific target-oriented strategy might be designed and improved based on our findings.

自身免疫性肝炎（AIH）的发病机制一直备受关注，特异性T 细胞免疫有望成为揭示病因的突破口。研究发现：AIH 患者γδT 细胞数量增多，但意义不明；实验性AIH中Th17肝致病性和保护性的矛盾结果同时存在，Treg的作用机制尚不明确；γδT 功能模式具多样性特点，也是Th17和Treg的 重要来源。因此，我们拟以人2型AIH肝抗原诱导小鼠AIH为模型，研究AIH 形成中肝脏γδT 定位、定量及相关细胞因子表达，检测γδT 杀伤功能；并探讨γδT 在AIH 中特定功能模式与肝细胞、NKT细胞等的相互影响。同时，我们将研究2型AIH 患者肝组织中γδT 细胞及相关细胞因子表达特点（与1型AIH及慢乙肝比较）。该构想在国内外具有较强新颖性，有充分的立论依据和成熟的技术路线，通过本课题研究，有望明确AIH中的特异性高的细胞靶点，为今后分子或细胞靶向治疗提供依据，具有重要理论意义和良好应用前景。

我们研究目的旨在通过实验性自身免疫性肝炎(experimental autoimmune hepatitis，EAH) 小鼠模型，探讨γδT细胞及其分泌的细胞因子在EAH小鼠中的表达及意义。建立EAH小鼠模型，并予不同的干预措施，用ELISA 检测小鼠肝脏组织中的IL-17 水平，用流式细胞仪检测肝脏淋巴细胞亚群中IL-17 的表达，根据肝脏病理组织学及血清中肝功能生化指标的变化，观察中和抗体对EAH小鼠肝脏损伤程度的影响。研究结果显示：模型组小鼠肝脏IL-17表达较对照组显著升高且与炎症程度正相关(r=0．82，P＜0.01) ，模型组肝脏淋巴亚群比例无明显变化，而γδT细胞中IL-17+比例显著高于对照组( P＜0.01) 。中和IL-17 组小鼠的肝脏炎症明显轻于rat IgG 对照组( P＜0.01) ，接近空白对照组(P＞0.05) ; γδT细胞清除组小鼠的肝脏炎症明显轻于hamster IgG 对照组( P＜0.05) ，但仍高于空白对照组(P＜0.05) 。我们研究发现EAH 小鼠中升高的IL-17主要来源于γδT细胞，中和IL-17或γδT 细胞均可抑制或减轻炎症，提示肝脏γδT 细胞通过IL-17 参与EAH 致病机制。通过本课题研究，提示AIH中存在特异性较高的细胞靶点，为今后分子或细胞靶向治疗提供依据，具有重要理论意义和良好应用前景。