Interaction of histamine-releasing factor with immunoglobulins in asthma

描述(申请人提供)：哮喘和过敏性疾病的流行率在过去几十年里急剧增加，在工业化国家已经达到流行的程度。目前的治疗方法既不是预防的，也不是治愈的。因此，迫切需要新的治疗策略。组胺释放因子(HRF)能以IgE依赖的方式激活肥大细胞和嗜碱性粒细胞。由于它的分泌是在后期过敏反应的体液中发现的，HRF已被认为与包括哮喘在内的过敏性疾病有关。二十年来，HRF是如何参与过敏反应的一直是个谜。然而，我们2012年的研究改变了这种情况，确定了IgE和IgG分子的一个子集为HRF受体；对HRF分子内免疫球蛋白(Ig)Fab结合位点的图谱导致了基于HRF序列的抑制物N19和H3肽的发现，这些抑制物竞争性地阻断了HRF-Ig相互作用；在肥大细胞和IgE依赖的哮喘模型中，这些抑制物显著减少了呼吸道炎症；鼻腔给药带有HRF的NAéve小鼠以Fc？RI(=高亲和力IgE受体)和肥大细胞依赖的方式引起呼吸道炎症。在这个项目中，为了更深入地了解HRF-Ig相互作用的结构，(I)我们将鉴定HRF反应的IgE和Ig分子的分子特征，以及(Ii)通过X射线结晶学和核磁共振光谱在原子和亚分子水平上分析HRF-Ig相互作用的结构和动力学特征。如果HRF抑制剂应该在临床环境中使用，它们将首先在具有丰富的HRF-Ig相互作用的患者身上进行测试。为了模拟这种情况，(Iii)我们将测试HRF抑制剂是否以及哪些HRF抑制剂对在肺中过度表达HRF或HRF反应性IgE的转基因小鼠的呼吸道炎症有效。在人类和其他哺乳动物基因组中存在几个与HRF相关的假基因。因此，(Iv)我们将测试他们的基因产物是否影响HRF功能。通过这个项目获得的知识将丰富我们对HRF-Ig相互作用的理解，以及HRF-Ig相互作用在哮喘模型中的致病作用，这将对我们未来的临床研究至关重要。

DESCRIPTION (provided by applicant): The prevalence of asthma and allergic diseases has been dramatically increasing for the last few decades and has reached epidemic proportions in industrialized countries. Current therapy is not preventive or curative. Thus, novel therapeutic strategies are urgently needed. Histamine-releasing factor (HRF) can activate mast cells and basophils in an IgE-dependent manner. As its secretion was found in bodily fluids during late-phase allergic reactions, HRF has been implied in allergic diseases including asthma. How HRF is involved in allergic reactions had remained enigmatic for two decades. However, our 2012 study changed this situation by identifying a subset of IgE and IgG molecules as HRF receptors; mapping of the immunoglobulin (Ig) Fab-binding sites within the HRF molecule led to the discovery of HRF sequence-based inhibitors, N19 and H3 peptides, which competitively blocked HRF-Ig interactions; administration of these inhibitors drastically reduced airway inflammation in mast cell- and IgE-dependent models of asthma; intranasal administration of na¿ve mice with HRF caused airway inflammation in an Fc¿RI (= high-affinity IgE receptor) and mast cell-dependent manner. In this project, to gain more structural insights into HRF-Ig interactions, (i) we will identify the molecular signature of HRF-reactive IgE and IgG molecules, and (ii) analyze structural and dynamic features for HRF-Ig interactions at atomic and submolecular levels by X-ray crystallography and NMR spectroscopy. If HRF inhibitors should ever be used in a clinical setting, they would initially be tested on patients with abundant HRF-Ig interactions. To mimic such conditions, (iii) we will test whether and what HRF inhibitors are effective to treat airway inflammation in transgenic mice overexpressing HRF in the lung or HRF-reactive IgE. Several HRF-related pseudogenes are present in human and other mammalian genomes. Therefore, (iv) we will test whether their gene products affect HRF functions. Knowledge to be gained through this project will enrich our understanding of HRF-Ig interactions and the pathogenic roles of HRF-Ig interactions in asthma models, which will be crucial for our future clinical study.