PGD2 Receptor Subtype Functions in T Cells from Asthmatics

描述(由申请人提供)：产生IL-4和IL-13的2型T细胞，对特应性疾病的发展至关重要，并通过各种机制促进哮喘的发病。PGD2是一种主要由肥大细胞产生的前列腺素，通过GI偶联的G蛋白偶联受体DP2受体(CRTH2)参与嗜酸性粒细胞和2型T细胞的趋化作用。然而，PGD2也激活DP1受体，这是一种GS偶联的GPCR，能够激活PKA，并潜在地拮抗CRTH2受体的信号和作用。2型T细胞和非2型T细胞都表达DP1受体。两种PGD2受体(CRTH2和DP1)的相互作用如何影响2型T细胞功能，包括化学吸引和IL-13+T细胞积聚，目前尚不清楚。我们假设：1)PGD2通过激活CRTH2受体增加有丝分裂原刺激的产生IL-13的T细胞的聚集，但这种作用受到伴随的DP1受体激活的限制；2)平均而言，哮喘患者的T细胞表现出更具优势的CRTH2(与DP1受体相比)受体反应，转化为对PGD2反应的更大的产生IL-13的T细胞的聚集和化学吸引。为了验证这一假说，我们将在特应性哮喘和非哮喘(对照)受试者的外周血淋巴细胞中表征PGD2对2型T细胞功能的受体特异性作用。将被测试的功能包括：1)激活/抑制PKA；2)激活/抑制MAPK和Akt；3)非抗原依赖的2型T细胞聚集；3)2型T细胞的趋化作用。这一建议为研究PGD2受体在哮喘中的作用提供了一种新的方法：1)哮喘和非哮喘人群之间关于PGD2对细胞功能影响的比较以前没有报道；2)这两种PGD2受体对有丝分裂原刺激的积聚2型T细胞的相互作用及其信号机制以前还没有被探索过。了解PGD2的“好”和“坏”效应之间的竞争平衡，对于确定针对哮喘和其他炎症性疾病的PGD2受体亚型的可行治疗策略至关重要。与公共卫生相关。PGD2是哮喘患者暴露于变应原后肺部发现的一种重要的炎症介质。在这项研究中，我们将研究这种分子如何影响暴露在PGD2中的免疫细胞数量的增加，以及哮喘患者是否对PGD2的“坏”影响更加敏感。研究结果将帮助我们了解PGD2如何驱动过敏性炎症的发生，并可能提出从药物上平衡PGD2的“好”和“坏”影响的方法。

DESCRIPTION (provided by applicant): IL-4- and IL-13- producing type 2 T cells, are critical for the development of atopy and contribute to asthma pathogenesis by a variety of mechanisms. PGD2, a prostaglandin produced predominantly by mast cells, is involved in chemoattraction of eosinophils and type 2 T cells via the DP2 receptor (CRTH2), a Gi-coupled G protein-coupled receptor (GPCR). However, PGD2 also activates the DP1 receptor, which is a GS-coupled GPCR capable of activating PKA and potentially antagonizing the signaling and effects of the CRTH2 receptor. Both type 2 and non-type 2 T cells express DP1 receptors. How the interplay of the two PGD2 receptors (CRTH2 and DP1) affects type 2 T cell functions, including chemoattraction and IL-13+ T cell accumulation, is unclear. We hypothesize that: 1) PGD2 increases mitogen-stimulated accumulation of IL-13-producing T cells through activation of CRTH2 receptor, but this effect is constrained by concomitant activation of the DP1 receptor; and 2) T cells from asthmatic subjects exhibit, on average, a more dominant CRTH2 (vs. DP1 receptor) receptor response that translates into greater accumulation and chemoattraction of IL-13-producing T cells in response to PGD2. To test this hypothesis, we will characterize the receptor-specific effects of PGD2 on type 2 T cell functions in peripheral blood lymphocytes from atopic asthmatic and nonasthmatic (control) subjects. Functions to be tested include: 1) activation/inhibition of PKA; 2) activation/inhibition of MAPK's and Akt; 3) antigen -independent and -dependent accumulation of type 2 T cells; and 3) chemoattraction of type 2 T cells. This proposal provides a novel approach for examining the contribution of PGD2 receptors in asthma: 1) comparisons between asthmatic and nonasthmatic populations for the effects of PGD2 on cellular functions have not been previously reported; and 2) the interplay between the two PGD2 receptors on mitogen-stimulated accumulation type 2 T cells, and the signaling mechanisms involved, have not been previously explored. Knowledge of the competitive balance between the "good" and "bad" effects of PGD2 is critical for determining a feasible therapeutic strategy targeting PGD2 receptor subtypes in the treatment of asthma, as well as other inflammatory diseases. PUBLIC HEALTH RELEVANCE. PGD2 is an important inflammatory mediator found in the lungs of asthmatics after exposure to allergen. In this study, we will examine how this molecule affects how immune cells increase in number when exposed to PGD2, and if asthmatics are more sensitive to the "bad" effects of PGD2. Results will help us understand how PGD2 drives allergic inflammation occurs, and may suggest ways to pharmacologically balance the "good" and "bad" effects of PGD2.