Genetic regulation of CD177 and the role of CD177-proteinase-3 interactions in ANCA-associated vasculitis.

蛋白酶3(PR3)和髓过氧化物酶(MPO)是抗中性粒细胞胞浆自身抗体(ANCA)介导的小血管炎和坏死性新月体肾炎(NCGN)的主要抗原。整个中性粒细胞群都携带PR3，但在中性粒细胞膜上呈双峰分布，产生膜PR3(MPR3)低和高(MPR3)亚群。在PR3-ANCA所致的血管炎患者中，mPR3高亚群越大，体外对中性粒细胞的激活作用越强，临床病程越差。我们先前将中性粒细胞特异性CD177描述为PR3的膜受体。CD177受体蛋白和全长mRNA在CD177阳性/mPR3高表达人群中表达，而在CD177阴性/mPR3低表达人群中不表达。我们的建议有两个密切相关的实验方面，主要集中在CD177-PR3相互作用上，即(1)CD177表达的调节和(2)CD177-PR3相互作用在PR3-ANCA诱导的小血管炎中的意义。为了(1)建立CD177基因表达受限的遗传或表观遗传学基础，我们将进行CD177基因的DNA和cDNA分析以及全基因组、拷贝数变异分析、TRIO中的单倍型研究、甲基化、组蛋白修饰和非编码RNA的研究。我们将评估血液和干细胞来源的人类中性粒细胞。虽然其他人和我们建立了抗MPO抗体介导的小鼠血管炎模型，但没有抗PR3抗体的小鼠模型存在。小鼠的CD177和PR3与它们的人类同源基因有很大的不同，并且被预测不能进行物理相互作用。我们假设(2)在髓系相关蛋白8(MRP8)启动子下同时表达人CD177和PR3的小鼠将在中性粒细胞表面表达人PR3，并在患者的PR3-ANCA攻击时发生血管炎和NCGN。这些研究将阐明CD177-PR3相互作用在PR3-ANCA诱导的血管炎中的作用，并可能建立CD177-PR3复合体作为新的治疗靶点。

Proteinase 3 (PR3) and myeloperoxidase (MPO) are the major antigens in anti-neutrophil cytoplasmic autoantibody (ANCA)-mediated vasculitis and necrotizing crescentic glomerulonephritis (NCGN). PR3 is harbored by the entire neutrophil population but is bimodally presented on the neutrophil membrane yielding membrane PR3 (mPR3)low and (mPR3)high subsets. The larger the mPR3high subset the stronger the neutrophil activation by PR3-ANCA in vitro and the worse the clinical disease course in patients with PR3-ANCA-induced vasculitis. We described neutrophil-specific CD177 previously as a membrane receptor for PR3. CD177 receptor protein and full-length mRNA are expressed by the CD177positive/mPR3high population, but not by the CD177negative/mPR3low population of neutrophils. Our proposal has two tightly related experimental aspects focusing on the CD177-PR3 interaction, namely (1) the regulation of the CD177 expression and (2) the significance of the CD177-PR3 interaction for PR3-ANCA-induced vasculitis. To (1) establish the genetic or epigenetic basis for a restricted CD177 gene expression, we will perform DNA and cDNA analysis of the CD177 gene and genome-wide, copy-number variation analysis, haplotype studies in trios, studies on methylation, histone modifications, and non-coding RNAs. We will assess blood- and stem cell-derived human neutrophils. Whereas others and we established mouse models for anti-MPO antibody-mediated vasculitis, no murine model for anti-PR3 antibodies exists. Murine CD177 and PR3 differ substantially from their human orthologs and were predicted incapable of physical interaction. We hypothesize that (2) mice expressing both human CD177 and PR3 under the myeloid-related protein 8 (MRP8) promoter will present human PR3 on the neutrophil surface and develop vasculitis and NCGN when challenged with PR3-ANCA from patients. These studies will clarify the role of CD177-PR3 interaction for PR3-ANCA induced vasculitis and possibly establish the CD177-PR3 complex as a novel treatment target.