The Cell Type Specific Immune Regulatory Functions of Amphiregulin in Glomerulonephritis

肾小球肾炎（GN）仍然是世界范围内终末期肾脏疾病的主要原因。自身免疫性疾病，如抗中性粒细胞细胞质抗体（ANCA）相关的血管炎和系统性红斑狼疮（SLE）是典型的潜在病理。由于目前可用的治疗方法相当非特异性和相对毒性，寻找新的和创新的治疗选择是非常有益的。多功能细胞因子双调节蛋白（AREG）是一种新的有前景的治疗靶点。AREG属于表皮生长因子（EGF）家族，通过与混杂的EGF受体（EGFR）结合来调节其作用。最近的研究，包括我们自己过去资助期的数据，已经确定AREG是炎症性疾病的重要介质。更好地了解AREG的免疫功能是非常必要的，因为EGFR阻滞剂已经用于肿瘤治疗，各种AREG导向的化合物目前正在开发中，因此它们也可以用于治疗免疫介导的疾病。然而，值得注意的是，已报道了促和抗炎AREG作用。在这方面，我们和其他人的数据表明，AREG的细胞来源可能对最终功能很重要。虽然常驻组织细胞来源的AREG似乎具有促炎和促纤维化作用，但白细胞来源的AREG被证明主要具有抗炎和修复作用。因此，当前拨款申请的一个主要目标是阐明AREG在急性GN和慢性狼疮性肾炎中的细胞类型特异性差异作用，为AREG定向治疗奠定基础。第二个主要目标将是表征目前尚不明确的由AREG信号启动的免疫调节机制。以前的研究，包括我们过去资助期的数据，都指出AREG对CD4+ T细胞反应有很强的免疫抑制作用。因此，我们的目的是深入分析这一观察的临床相关性，并确定细胞参与者和信号通路。使用的模型将包括抗原特异性免疫，肾毒性肾炎（NTN），类似于人类快速进行性肾炎，以及SLE的一种诱导（pristane）和一种遗传（MRL/lpr）模型。最后，我们将把我们的发现转化为人类GN，并利用RNAseq和多重免疫荧光技术，通过法国和德国集体狼疮肾炎患者的不同细胞来源来表征AREG的表达。我们的研究结果将与临床和组织病理学数据相关联，并为评估AREG作为预后生物标志物以及干预AREG/EGFR轴作为治疗GN的新选择提供基础。

Glomerulonephritis (GN) remains a leading cause of end stage renal disease worldwide. Autoimmune diseases like anti neutrophil cytoplasmic antibody (ANCA) associated vasculitis and systemic lupus erythematosus (SLE) are typical underlying pathologies. Since currently available therapies are rather non-specific and relatively toxic, the search for new and innovative therapeutic options is highly rewarding. A novel and promising therapeutic target is the multi-functional cytokine Amphiregulin (AREG). AREG belongs to the epidermal growth factor (EGF) family and mediates its effects via binding to the promiscuous EGF-receptor (EGFR). Recent studies, including our own data from the past funding period, have identified AREG as an important mediator of inflammatory diseases. A better understanding of AREG´s immune functions is highly warranted, since EGFR blockers are already in use for tumor therapy and various AREG directed compounds are currently being developed, so that they could also be applied to treat immune mediated diseases. It is of note, however, that both, pro- as well as anti-inflammatory AREG effects have been reported. In this respect, data by us and others suggest, that the cellular source of AREG might be important for the resulting function. While resident tissue cell derived AREG seems to have pro-inflammatory and pro-fibrotic effects, leukocyte derived AREG was shown to be predominantly anti-inflammatory and reparative. One main goal of the current grant application is thus to clarify the cell type specific differential roles of AREG in acute GN and chronically developing lupus nephritis to lay the groundwork for AREG directed therapies. The second main goal will be characterization of the currently ill-defined immune-regulatory mechanisms initiated by AREG signaling. Previous studies, including our data from the past funding period have pointed towards strong immunosuppressive effects of AREG on CD4+ T cell responses. We thus aim to in depth analyze the clinical relevance of this observation, and to identify the cellular players and signaling pathways involved herein. Models used will include antigen specific immunization, nephrotoxic nephritis (NTN), which resembles human rapidly progressive GN, as well as one inducible (pristane) and one genetic (MRL/lpr) model of SLE. Finally, we will translate our findings to human GN and characterize AREG expression by its different cellular sources in lupus nephritis patients from French and German collectives, using RNAseq and multiplex immunofluorescence techniques. Our findings will be correlated with clinical and histopathological data and provide the basis for evaluation of AREG as a prognostic biomarker as well as for interventions against the AREG/EGFR axis as novel option for the treatment of GN.