IFNy-dependent immune responses are involved in the pathogenesis of PSC

原发性硬化性胆管炎(PSC)是一种以胆道炎症和纤维化为特征的特发性慢性淤胆性肝病。肝内干扰素-γ(干扰素-γ)产生的淋巴细胞数量增加已在PSC患者中得到证实，但其功能作用仍有待确定。MDR2-/-小鼠是研究PSC过程中慢性胆管炎和纤维化机制的已建立模型。利用这些动物以及PSC患者的样本，我们询问干扰素γ是否参与PSC的发病机制。我们以往的研究表明，PSC患者血清中的干扰素γ水平和NK细胞数量均升高。在MDR2-/-小鼠中，肝脏CD8+T细胞和NK细胞是干扰素γ的主要来源，肝脏中干扰素γ诱导的趋化因子表达增强。干扰素γ改变了肝脏CD8+T细胞和NK细胞的表型，增加了细胞毒作用，加重了肝纤维化。因此，我们假设干扰素γ参与了PSC发病过程中肝脏效应细胞的迁移和淋巴细胞的细胞毒作用。由于NK细胞属于在表型和功能上与ILC1相似的先天淋巴样细胞(ILC)，我们将研究ILC1在PSC中的作用。为了进一步确定淋巴细胞细胞毒性在PSC进展中的意义，我们将建立mdr2-/-x GzmB-/-和mdr2-/-x Trail-/-小鼠，并分析疾病病理。为了确定CD8+T细胞在PSC发病机制中的作用，我们将使用抗原特异的PSC模型，在该模型中，OVA特异性CD8+T细胞转移到mdr2/-x K14-OVAp小鼠身上表明会加重肝脏损伤。目前尚不清楚这是否由干扰素γ的表达所介导。因此，我们建立了OT-I×IFNG-/-小鼠，其中卵清蛋白特异的CD8+T细胞不表达干扰素γ。在合作研究中，我们将对MDR2-/-x K14-OVAP小鼠进行过继转移实验，以研究抗原特异性的、产生干扰素γ的CD8+T细胞对肝脏损伤和纤维化的影响。此外，来自OT-1x Gzmb-/-或OT-1x Trail-/-小鼠的CD8+T细胞将用于过继转移实验，以分析CD8+T细胞的细胞毒作用。在一种治疗方法中，我们将使用抗p40抗体来阻断mRd2-/-小鼠的IL-12和IL-23信号。一种抗p40抗体(Ustekinumab)被批准用于治疗炎症性肠病，这种疾病经常与PSC有关。此外，我们还将建立缺乏干扰素γ诱导趋化因子受体的MDR2-/-x CXCR3-/-小鼠，以评估干扰素γ介导的效应细胞募集对前列腺癌病理的影响。此外，我们还将研究CXCR3拮抗剂对mdr2-/-小鼠的治疗作用。因此，我们预计对干扰素γ依赖的免疫反应的研究将为治疗前列腺癌提供新的选择。

Primary sclerosing cholangitis (PSC) is an idiopathic, chronic cholestatic liver disorder characterized by biliary inflammation and fibrosis. Increased numbers of intrahepatic interferon-γ (IFNγ)-producing lymphocytes have been documented in PSC patients, yet their functional role remains to be determined. The Mdr2-/- mouse is an established model to study mechanisms of chronic biliary inflammation and fibrosis during PSC. Using these animals as well as PSC patient samples, we asked whether IFNγ mediates the pathogenesis of PSC. Our previous studies showed that INFγ serum levels and NK cell numbers were increased in PSC patients. In Mdr2-/- mice, hepatic CD8+ T cells and NK cells were the main source of IFNγ and hepatic expression of IFNγ-inducible chemokines was enhanced. IFNγ changed the phenotype of hepatic CD8+ T cells and NK cells towards increased cytotoxicity and aggravated liver fibrosis.Therefore, we hypothesise that IFNγ is involved in hepatic effector cell migration and lymphocyte cytotoxicity during the pathogenesis of PSC.In our work programme, we will analyse phenotype and function of human and murine NK cells in more detail and perform depletion experiments in mice. As NK cells belong to the group of innate lymphoid cells (ILC) resembling ILC1 in phenotype and function, we will examine the role of ILC1 in PSC.To further determine the significance of lymphocyte cytotoxicity for PSC progression, we will generate Mdr2-/- x GzmB-/- and Mdr2-/- x Trail-/- mice and analyse disease pathology. To determine the contribution of CD8+ T cells to PSC pathogenesis, we will use an antigen-specific PSC model, where transfer of OVA-specific CD8+ T cells to Mdr2-/- x K14-OVAp mice was shown to aggravate liver damage. Whether this is mediated by IFNγ expression is not known. Therefore, we generated OT-I x Ifng-/- mice, in which OVA-specific CD8+ T cells do not express IFNγ. In collaborative studies, we will perform adoptive transfer experiments with Mdr2-/- x K14-OVAp mice to study the impact of antigen-specific, IFNγ-producing CD8+ T cells on liver damage and fibrosis. Moreover, CD8+ T cells from OT-1 x Gzmb-/- or OT-1 x Trail-/- mice will be used for adoptive transfer experiments to analyse the role of CD8+ T cell cytotoxicity. In a therapeutic approach, we will use an anti-p40 antibody to block IL-12 and IL-23 signalling in Mrd2-/- mice. An anti-p40 antibody (Ustekinumab) is licenced for treatment of inflammatory bowel diseases, which is frequently associated with PSC. In addition, we will generate Mdr2-/- x Cxcr3-/- mice, which lack a receptor for IFNγ-inducible chemokines, to evaluate the impact of IFNγ-mediated effector cell recruitment for PSC pathology. Moreover, we will study the therapeutic effect of CXCR3 antagonists in Mdr2-/- mice. Hence, we anticipate that investigation of IFNγ-dependent immune responses will provide novel options for treatment of PSC.