Immunological and Microbial Mechanisms in Food Allergy

摘要 食物过敏的日益恶化的流行归因于环境因素的汇合， 现代生活方式，包括改变肠道微生物群，作用于遗传易感个体。中央 食物过敏的发展是口服耐受性的破坏，通常由食物过敏原引起， 特异性T调节（TR）细胞。然而，口服耐受性破坏的机制是 晦涩难懂。通过采用一种涉及功能突变获得的人类食物过敏的创新小鼠模型， 在IL-4受体α链免疫酪氨酸抑制基序（Il 4 raF 709）中，我们已经证明食物 过敏与过敏原特异性诱导的TR（iTR）细胞的形成减少有关。这些iTR细胞 所产生的是功能失调的，不能防止致敏或抑制活动性疾病。该失效 与它们重编程为表达IL-4的Th 2细胞样TR细胞有关，GATA 3水平升高， 降低Tgfb 1转录。我们还观察到过敏原特异性TR细胞中的Th 2细胞样重编程 对食物过敏的人食物过敏的Il 4 raF 709小鼠表现出先天性淋巴样细胞的失调 2型（ILC 2），其通过分泌IL-4在疾病发病机制中发挥必要作用。它们也表现出 致病性的生态失调的水生植物群，如它们促进食物过敏所证明的， 转移到无菌（GF）小鼠中。反过来，食物耐受小鼠的植物群阻止疾病诱导 当移植到GF 114 raF 709小鼠中时。使用最少梭菌或拟杆菌聚生体的治疗可保护 防止食物过敏。因此，在目的1中，我们提出Th 2细胞样TR细胞在疾病中起关键作用 通过指导IgE产生和肥大细胞扩增， 通过TR细胞特异性IL 4/IL 13缺失的Th 2细胞样TR细胞程序挽救了已建立的疾病。我们还将 检查TR细胞中Tgfb 1表达改变对TR细胞小鼠疾病发病机制的贡献， 特异性Tgfb 1缺失或转基因表达。在目的2中，我们将检验IL-4的产生是通过 ILC 2通过抑制iTR细胞形成和诱导Th 2细胞样免疫应答在疾病发病机制中起关键作用。 TR细胞的重编程，并且TR细胞反过来通过IL-33依赖性机制调节ILC。最后在 目的3，我们假设梭菌和拟杆菌聚生体的最小集合拯救活动性疾病， 抑制微生态失调并部分通过TR细胞中MyD 88的信号传导恢复微生态失调， 促进iTR细胞形成，并将肠道免疫球蛋白的产生从IgE转向伊加。 我们提出的研究将确定基本的免疫学和微生物机制， 食物过敏的耐受性被破坏，这将使治愈性疗法的发展成为可能。

ABSTRACT The worsening epidemic of food allergy has been attributed to a confluence of environmental factors reflective of a modern life style, including altered gut microbiota, acting upon genetically susceptible individuals. Central to the development of food allergy is the breakdown of oral tolerance, normally enforced by food allergen- specific T regulatory (TR) cells. However, the mechanisms involved in the breakdown of oral tolerance are obscure. By employing an innovative murine model of human food allergy involving a gain of function mutation in the IL-4 receptor alpha chain immunotyrosine inhibitory motif (Il4raF709), we have demonstrated that food allergy is associated with reduced formation of allergen-specific induced TR (iTR) cells. Those iTR cells that are generated are dysfunctional and fail to prevent sensitization or to suppress active disease. This failure is related to their reprogramming into Th2-cell like TR cells that express IL-4, elevated levels of GATA3 and decreased Tgfb1 transcripts. We have also observed Th2 cell-like reprogramming in allergen-specific TR cells of human food allergic subjects. Food allergic Il4raF709 mice manifest dysregulation of innate lymphoid cells type 2 (ILC2s), which play a requisite role in disease pathogenesis by secreting IL-4. They also exhibit dysbiotic commensal flora that are pathogenic, as evidenced by their promotion of food allergy when transferred into germ-free (GF) mice. Reciprocally, flora of food tolerant mice prevented disease induction when transplanted into GF Il4raF709 mice. Therapy with minimal Clostridia or Bacteroidetes consortia protect against food allergy. Accordingly, in Aim 1, we propose that Th2 cell-like TR cells play a critical role in disease pathogenesis and persistence by directing IgE production and mast cell expansion, and that suppression of the Th2 cell-like TR cell program by TR cell-specific Il4/Il13 deletion rescues established disease. We will also examine the contribution of altered Tgfb1 expression in TR cells to disease pathogenesis in mice with TR cell- specific Tgfb1 deletion or transgene expression. In Aim 2, We will test the hypothesis that IL-4 production by ILC2 plays a crucial role in disease pathogenesis by suppressing iTR cell formation and inducing Th2 cell-like reprogramming of TR cells, and that TR cells in turn regulate ILC by IL-33-dependent mechanisms. Finally, in Aim 3, we hypothesize that a minimal set of Clostridia and Bacteroidetes consortia rescues active disease, suppresses dysbiosis and restores commensalism in part by signaling via MyD88 in TR cells, which would promote iTR cell formation and redirect intestinal immunoglobulin production away from IgE and towards IgA. Our proposed studies will identify fundamental immunological and microbial mechanisms by which oral tolerance is subverted in food allergy, and will enable the development of curative therapies.