Alternaria and ribonucleases in Th2-type immunity

描述(申请人提供)：该项目的长期目标是更好地了解哮喘和过敏性疾病的免疫学机制。这些疾病通常被认为是由Th2细胞介导的对环境蛋白质和生物体的免疫反应失调造成的。然而，几个根本性的问题仍然存在。患者是如何产生这种不适应的T细胞反应的？为什么所有可检测到血清IgE抗体的患者(例如过敏性鼻结膜炎患者)都不会发展为哮喘？通过使用与人类哮喘有关的交链孢霉真菌，我们一直在研究过敏原特异性CD4T细胞是如何发展的，以及哪些过敏原分子是关键的。我们现在假设，对空气传播的过敏原的所谓“Th2型免疫反应”是由两个不同的CD4T细胞亚群介导的，即Th2细胞和滤泡T(Tfh)细胞，它们分别与嗜酸性炎症和GE抗体的产生密切相关。我们还假设外源性和内源性核糖核酸酶(RNase)参与了病理性Th2细胞的发育。在目标1中，我们将使用小鼠模型，并确定Th2细胞和Tfh细胞在Th2型呼吸道免疫反应中对交链孢霉和其他空气传播变应原的作用。我们将利用细胞因子报告小鼠和基因缺陷小鼠，研究Th2细胞和Tfh细胞的区隔发育。在目标2中，我们将研究TFH细胞在人类呼吸道疾病中的作用。我们将在一组短豚草花粉症患者的血液中鉴定CXCR5 CD4T细胞，这是一种人类对应的TFH细胞，并检测这些细胞在花粉热季节的动态变化。在目标3中，我们将确定交链孢属衍生的核糖核酸酶和内源性核糖核酸酶，如嗜酸性粒细胞衍生的神经毒素，在Th2型免疫反应的发展和加剧中的作用。我们将整合从体外实验和体内小鼠模型获得的数据。重组链格孢菌核糖核酸酶和缺乏这些核糖核酸酶的真菌将被检测。基塔博士和他的合作者、真菌功能基因组学专家劳伦斯博士的实验室里随时可以获得这三个目标所需的技术专业知识。这项拟议的研究可能会更好地了解Th2型免疫对空气传播变应原产生的基本机制，并将为某些过敏性呼吸道疾病患者强烈的呼吸道炎症和IgE抗体产生之间的分离提供解释。这项研究还可能确定参与哮喘病理性T细胞反应发展的潜在关键环境和内源性分子。最终，这些研究将显著提高我们对过敏原诱导的呼吸道炎症所涉及的关键细胞途径(S)和分子(S)的了解，从而为开发治疗或预防哮喘及相关呼吸道疾病的新治疗策略确定关键靶点。

DESCRIPTION (provided by applicant): The long-term goal of this project is to better understand the immunologic mechanisms of asthma and allergic diseases. These diseases are generally thought to result from dysregulated immune responses to environmental proteins and organisms, which are mediated by Th2 cells. However, several fundamental questions still remain. How do patients develop such maladaptive T cell responses? Why don't all patients who have detectable serum IgE antibodies (e.g. patients with allergic rhinoconjunctivitis) develop asthma? By using the Alternaria fungus, which has been implicated in human asthma, we have been studying how allergen-specific CD4+ T cells develop and which allergen molecules are critically involved. We now hypothesize that the so-called "Th2-type immune response" to airborne allergens is mediated by two distinct CD4+ T cell subsets, namely Th2 cells and follicular T (Tfh) cells, which are critically involved in eosinophilic inflammation and gE antibody production, respectively. We also hypothesize that exogenous and endogenous ribonucleases (RNases) are involved in development of pathologic Th2 cells. In Aim 1, we will use mouse models and determine the roles of Th2 cells and Tfh cells in Th2-type airway immune responses to Alternaria and other airborne allergens. We will leverage cytokine reporter mice and gene-deficient mice and investigate the compartmentalized development of Th2 cells and Tfh cells. In Aim 2, we will investigate the roles of Tfh cells in human airway disease. We will characterize blood CXCR5+CD4+ T cells, a human counterpart of Tfh cells, in a cohort of patients with short ragweed hay fever and examine the dynamic changes in these cells during the hay fever season. In Aim 3, we will determine the roles of Alternaria-derived RNases and endogenous RNases, such as eosinophil-derived neurotoxin, in development and exacerbation of Th2 type immune responses. We will integrate data obtained from in vitro experiments and in vivo mouse models. Recombinant Alternaria RNases and the fungi deficient in these RNases will be examined. The technical expertise required for these three Aims is readily available in the laboratories of Dr. Kita and his collaborator, Dr. Lawrence, a fungal functional genomics expert. The proposed studies are likely to provide a better understanding of the fundamental mechanisms underlying the development of Th2-type immunity to airborne allergens and will provide an explanation for the dissociation between robust airway inflammation and IgE antibody production in certain patients with allergic airway disorders. The study will also likely identify potential key environmental and endogenous molecules that participate in the development of pathologic T cell responses in asthma. Ultimately, these studies will significantly enhance our understanding of the key cellular pathway(s) and molecule(s) involved in allergen- induced airway inflammation, allowing for identification of critical targets for development of novel therapeutic strategies to treat or to prevent asthma and related airway disorders.