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，并通过多种机制参与哮喘的发病。PGD2是一种主要由肥大细胞产生的前列腺素，通过DP2受体（一种gi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，PGD2也激活DP1受体，DP1受体是一种gs偶联GPCR，能够激活PKA并潜在地拮抗CRTH2受体的信号传导和作用。2型和非2型T细胞均表达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细胞积累，目前尚不清楚。我们假设：1)PGD2通过激活CRTH2受体增加了丝裂原刺激的il -13生成T细胞的积累，但这种作用受到伴随激活DP1受体的限制；2)哮喘患者的T细胞平均表现出更显性的CRTH2（相对于DP1受体）受体反应，这转化为产生il -13的T细胞对PGD2的更大积累和化学吸引。为了验证这一假设，我们将表征PGD2对特应性哮喘和非哮喘（对照组）受试者外周血淋巴细胞中2型T细胞功能的受体特异性作用。需要测试的功能包括：1)PKA的激活/抑制；2) MAPK和Akt的激活/抑制；3)抗原非依赖性和依赖性2型T细胞的积累；3) 2型T细胞的化学吸引。这一建议为检查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PGD2对细胞功能的影响的比较以前没有报道；2)两种PGD2受体在有丝分裂原刺激积累的2型T细胞上的相互作用，以及所涉及的信号传导机制，此前尚未被探索。了解PGD2“好”和“坏”作用之间的竞争平衡对于确定针对PGD2受体亚型治疗哮喘以及其他炎症性疾病的可行治疗策略至关重要。公共卫生相关性。PGD2是哮喘患者接触过敏原后肺部发现的重要炎症介质。在这项研究中，我们将研究这种分子如何影响暴露于PGD2时免疫细胞数量的增加，以及哮喘患者是否对PGD2的“坏”影响更敏感。研究结果将帮助我们了解PGD2是如何导致过敏性炎症发生的，并可能提出从药理学上平衡PGD2“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.