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细胞对特应性的发展至关重要，并通过多种机制促进哮喘发病机制。PGD 2是一种主要由肥大细胞产生的前列腺素，通过DP 2受体（CRTH 2）（一种G i偶联G蛋白偶联受体（GPCR））参与嗜酸性粒细胞和2型T细胞的化学吸引。然而，PGD 2也激活DP 1受体，DP 1受体是一种GS偶联的GPCR，能够激活PKA并潜在拮抗CRTH 2受体的信号传导和作用。2型和非2型T细胞都表达DP 1受体。两种PGD 2受体（CRTH 2和DP 1）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细胞积累，目前尚不清楚。我们假设：1）PGD 2通过CRTH 2受体的活化增加产生IL-13的T细胞的促分裂原刺激的积累，但这种作用受到DP 1受体的伴随活化的限制;和2）来自哮喘受试者的T细胞，平均而言，一个更占优势的CRTH 2（相对于DP 1受体）受体应答，其转化为产生IL-13的T细胞响应于PGD 2的更大积累和化学吸引。为了验证这一假设，我们将描述PGD 2对特应性哮喘和非哮喘（对照）受试者外周血淋巴细胞2型T细胞功能的受体特异性作用。待测试的功能包括：1）PKA的活化/抑制; 2）MAPK和Akt的活化/抑制; 3）2型T细胞的抗原非依赖性和抗原依赖性积累;和3）2型T细胞的化学吸引。这一提议为研究PGD 2受体在哮喘中的作用提供了一种新的方法：1）以前没有报道过哮喘和非哮喘人群之间PGD 2对细胞功能影响的比较; 2）以前没有研究过两种PGD 2受体在促分裂原刺激的2型T细胞蓄积中的相互作用及其相关的信号传导机制。了解PGD 2的“好”和“坏”效应之间的竞争平衡对于确定靶向PGD 2受体亚型治疗哮喘以及其他炎性疾病的可行治疗策略至关重要。公共卫生相关性。PGD 2是一种重要的炎症介质，在哮喘患者暴露于过敏原后的肺中发现。在这项研究中，我们将研究这种分子如何影响免疫细胞在暴露于PGD 2时数量的增加，以及哮喘患者是否对PGD 2的“坏”影响更敏感。结果将帮助我们了解PGD 2如何驱动过敏性炎症的发生，并可能建议如何平衡PGD 2的“好”和“坏”影响。

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.