IL-9-producing MC precursor ancestry and function in Food Allergy

从2005年到2014年，美国的食物过敏以惊人的速度增加，高得不成比例 2-5岁儿童的发病率。食物过敏(FA)的临床症状从轻微的反应到严重的潜在的 致命的过敏症，FDA批准的食物过敏治疗选择有限，避免进食 仍然是唯一安全的选择。更好地了解免疫机制和信号通路 潜在的食物过敏显然是有根据的，以允许开发有效和安全的治疗方法8。 在过去的15年里，我们的团队做出了几项开创性的贡献，揭示了 IL-9/IL-9R轴和胃肠(GI)肥大细胞(MC)负载在诱导IgE介导的食物过敏中的作用 与此一致，我们已经确定了一个亚颗粒、产生IL-9的MC前体(MCp9)群体 足以在不同品系的小鼠身上引起食物过敏症状。目前的知识差距是 MCp9发育和功能的细胞起源和细胞因子后遗症 在人类体内的这种细胞。 在初步研究中，我们做了几个变革性的观察：1)MCp9是由 来自双潜性嗜碱性粒细胞/MC祖细胞(FcRI-mCp)而不是承诺的MC祖细胞(FcRI+mCp)， 2)转化生长因子和IL-33的序列刺激是Mcp9发生所必需的；3)转化生长因子1启动 Mcp9的形成与Smad2/3活化和转化生长因子R1依赖及3)IL-33诱导IL9有关 表达依赖于NFkB。最后，我们开发了一种来自ips细胞的人类造血培养。 建立并鉴定了人MCP9细胞(CD117+FcRI+7High CD203c-IL-9+)，并揭示了其存在 食物过敏者十二指肠活检标本中类胰蛋白酶+IL-9+细胞。我们假设MCp9 细胞来源于序列依赖的转化生长因子IL-33信号轴诱导的MC前体细胞群 并在食物过敏模型中调节GIMC浓度。为了验证我们的假设，我们提出了三个目标：1)定义 MCp9在小鼠和人中的血统；2)确定MCp9命运中IL9 CNS25增强子元件的要求 3)确定MCp9细胞在食物过敏中对GIMC组织密度的贡献。 关于预期结果，AIM I中提议的研究预计将定义小鼠和 人类Mcp9的祖先和功能；2)定义了序列转化生长因子和IL-33信号在 MCp9形成中IL9 CNS25元件的调节和3)证明了MCp9来源的IL-2的需求 9在食物过敏中，并确定该细胞与花生过敏和口服免疫治疗结果的关系。 成功完成拟议的研究将为我们提供一个新的实质性起点 食物过敏中GIMC密度的潜在分子机制的研究进展 这种细胞在增加MC组织密度的食物过敏中的要求，从而指导了 新的和现有的治疗食物过敏和过敏反应的疗法。

Food allergy has increased at an alarming rate from 2005-2014 in the US, with a disproportionally higher incidence in children2-5. Clinical symptoms of food allergy (FA) range from mild reactions to severe, potentially lethal anaphylaxis6 and there are limited FDA-approved treatment options for food allergy, with food avoidance remaining the only safe option15. A better understanding of the immune mechanisms and signaling pathways underlying food allergy is clearly warranted to permit development of effective and safe therapies8. Over the last 15 years, our team has made several seminal contributions that unveiled a critical role for IL-9/IL-9R-axis and gastrointestinal (GI) mast cells (MC) load in the eliciting of IgE-mediated food allergy. Consistent with this, we have identified a hypogranular, IL-9 producing MC precursor (MCp9) population that is sufficient for induction of food allergy symptoms in different mice strains. The current gap in knowledge is the cellular origin and cytokine sequelae that underlie the development and function of MCp9s and that the presence of this cell in humans. In preliminary studies we have made several transformative observations: 1) that MCp9s are derived from the bipotential basophil / MC progenitor (FcRI- MCp) and not the committed MC progenitor (FcRI+ MCp), 2) sequence stimulation with TGF and IL-33 is required for the development of MCp9; 3) TGF1 priming for MCp9 formation is associated with SMAD2/3 activation and TGFR1-dependent and 3) IL-33-induction of Il9 expression is NFkB-dependent. Finally, we have developed a iPS-cell derived human hematopoietic culture system and identified human MCp9 cells (CD117+ FcRI+ 7high CD203c- IL-9+) cells and revealed the presence of Tryptase+ IL-9+ cells in duodenal biopsy samples from food allergic individuals. We hypothesize that MCp9 cells are derived from a MC precursor population, induced by sequence-dependent TGFIL-33 signaling axis and regulates GI MC density in food allergy models. To test our hypothesis, we propose three aims: 1) Define MCp9 ancestry in mice and humans; 2) Define the requirement of Il9 CNS25 enhancer element in MCp9 fate determination and function and 3) Define the contribution of MCp9 cells to GI MC tissue density in food Allergy. With respect to the expected outcomes, the studies proposed in Aim I are expected to define murine and human MCp9 ancestry and functionality; 2) Define the involvement of sequential TGF and IL-33 signals in the regulation of the Il9 CNS25 element in MCp9 formation and 3) demonstrate a requirement for MCp9-derived IL- 9 in Food Allergy and define the relationship of this cell with peanut allergy and oral immunotherapy outcomes. Successfully completing the proposed studies will provide a new and substantive departure from our current understanding of the underlying molecular mechanisms underpinning GI MC density in food allergy and the requirement of this cell in increased MC tissue density in food allergy, thereby directing the development of new and pre-existing therapeutics for treating food allergy and anaphylaxis.