IRF4在Tac诱导Th17/Treg失衡所致肝移植术后过度免疫抑制中的作用及机制

免疫抑制剂应用剂量相关的毒副作用是影响肝脏移植受者长期生存的主要危险因素。探寻评估肝脏移植后免疫抑制状态的特异性标记物指导优化免疫抑制方案是亟需解决的关键问题。我们及国外同行的研究显示，他克莫司(Tac)大剂量治疗组模型动物Th17/Treg降低、T细胞能荷下降、IRF4表达下调，提示Tac可能通过降低Th17/Treg诱导过度免疫抑制。本研究拟采用大鼠肝移植术后应用不同剂量Tac的动物模型，采用ELISA检测血浆IL-2、IL-17、TGF-β水平，流式细胞术计数Th17/Treg，MLR及能荷试验检测Th17、Treg功能，探讨Tac浓度与免疫抑制状态及移植肝免疫损伤间的量效及时效关系。通过增强/干扰IRF4表达，探讨IRF4在Tac障碍Th17/Treg分化中作用以及Tac对IRF4表达调控的信号转导机制。研究结果将为评估肝脏移植受者免疫功能、建立个体化免疫抑制方案提供理论依据。

Liver transplantation(LTx) is the most effective treatment for acute and chronic irreversible liver diseases, attaining survival rates greater than 85% and 70% at 1 and 5 years, respectively. However, chronic use of immunosuppressants is associated with significant toxicity, leading to development of hypertension, hyperlipidemia, diabetes, renal failure, and de novo tumors and these toxic and side effects are the most important risk factors influencing long-term survival of LTx recipients. Therefore, there is an urgent need and ongoing challenge in modern transplant medicine to tailor immunosuppression to maintain efficacy while minimizing toxicity of LTx patients requiring specific, sensitive and non-invasive biomarkers for immunologic graft monitoring. Our recent studies and the references have shown that the number and ratio of Th17 cells and regulatory T cells(Treg) were significantly reduced in the high-dose Tacrolimus(Tac), the most widely used immunosuppressant in LTx patients, treatment regimen group animals. High concentration Tac can lower the energy charge of total T cells and down-regulate the expression of interferon regulatory factor 4(IRF4). We presume that the total number and ratio of Th17/Treg cells can be used to monitor immune function status of LTx recipients. In this study, we establish different doses of Tac treatment regimen rat LTx model to explore the relationship between the Tac dose and immune function status and immune damage of transplanted liver. We use ELISA to detect the change of cytokine expression level of IL-17, IL-2 and TGF-beta. Flow cytometry is applied to count total number and the ratio of Th17, Tregs. Mixed lymphocyte reaction and the energy charge experiment will be used to detecte Th17/Treg cell function and immune damage indicators of liver tissue. We will explore the effect of Th17/Treg differentiation by IRF4 and the signal transduction mechanism of IRF4 gene expression and regulation by Tac, and the enhancement or interference IRF4 expression at the cellular level. Our ongoing prospective studies will poise to gain further mechanistic insights into the Tac immune suppression and enable immune monitoring with customized, patient tailored treatment strategies for LTx recipients.