Mast Cell Derived PGD2 and LTC4 in Lung Inflammation

肥大细胞衍生的 PGD2 和 LTC4 在肺部炎症中的作用

• 批准号: 7098417
• 负责人: BING K LAM
• 金额: $ 42.08万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7098417
• 关键词: DNA footprinting; X ray crystallography; binding sites; cell line; chimeric proteins; chromatin immunoprecipitation; eicosanoid metabolism; enzyme structure; gel mobility shift assay; genetic mapping; genetic promoter element; genetic regulation; glutathione; glutathione transferase; human tissue; leukotrienes; mast cell; polymerase chain reaction; prostaglandins; site directed mutagenesis; transcription factor

Mast cells (MCs) to respond to activation by innate stimuli or cross linking of the high-affinity receptor for IgE (FceRI) by generating eicosanoids, particularly the cysteinyl leukotrienes (cysLTs) and prostaglandin (PG) D2, providing a direct link to the inflammatory processes in bronchial asthma. While the role of cysLTs in bronchial asthma is established by the efficacy of therapeutic agents that block their synthesis or their action at the type 1 (CysLT-i) receptor, comparable evidence for PGD2 awaits development of specific inhibitors for human use. Our Preliminary studies now reveal that PGD2 unexpectedly suppresses LTC4 synthase (LTC4S) and LTC4 generation by mouse bone marrow-derived MCs (mBMMCs), and that a microbial signal, eptidoglycan (PGN), induces the expression of LTC4S (but not hematopoietic PGD2 synthase) by mBMMCs. Unlike IL-4, PGN upregulates LTC4S by a signal transducer activator of transcription (STAT)6 independent signaling pathway that likely involves nuclear factor KB (NF-icB) and other Toll-like receptor (TLR)-dependent signals. We hypothesize that (1) that PGD2 inhibits LTC4S function by a DP2 receptor-mediated signal directed predominantly to a post translational mechanism, that PGN upregulates LTC4S expression through NF-KB-dependent transcription and that the PGD2 mediated down regulation of LTC4S action will be dominant over the enhancement action of PGN; (2) that in allergen challenge models of pulmonary inflammation, CysLT1 is more important in the inflammatory response and CysLT2 is more relavent to pulmonary remodeling, and that MC-derived PGD2 and PGE2, through suppression of LTC4S, will counter the effects of cysLTs; and (3) that LTC4S functions as homotrimer with each monomer containing four alpha helixes, and that Arg-51 and Tyr-93 are involved in catalysis while lle-27, Val-35, Val-49, Arg-51, Ala-52, Asn-55, Tyr-59, Tyr-93, Tyr-97, and Ala-112 form the binding sites for LTA4 and GSH. We therefore propose the following Specific Aims: 1) To elucidate the mechanism by which PGN upregulates and PGD2 downregulates the expression of LTC4S in mBMMCs; 2) To examine the in vivo role of LTC4 and PGD2 in mast cell dependent models of airway inflammation and in chronic models with remodeling of airways; and 3) To determine the three-dimensional structure of human LTC4S by X-ray crystallography.

肥大细胞（MC）通过产生类花生酸，特别是半胱氨酰白三烯（cysLT）和前列腺素（PG）D2，对先天刺激或IgE高亲和力受体（FceRI）交联激活做出反应，与支气管哮喘的炎症过程直接相关。虽然cysLT在支气管哮喘中的作用是通过阻断其合成或其对1型（CysLT-1）受体的作用的治疗剂的功效来确定的，但PGD 2的类似证据有待开发用于人类的特异性抑制剂。 我们的初步研究现在揭示，PGD 2出乎意料地抑制小鼠骨髓来源的MC（mBMMC）的LTC 4合酶（LTC 4S）和LTC 4生成，并且微生物信号肽聚糖（PGN）诱导mBMMC表达LTC 4S（但不诱导造血PGD 2合酶）。与IL-4不同，PGN通过信号转导转录激活因子（STAT）6独立的信号传导途径上调LTC 4S，该信号传导途径可能涉及核因子KB（NF-κ B）和其他Toll样受体（TLR）依赖性信号。 我们假设：（1）PGD 2通过DP 2受体介导的信号抑制LTC 4S功能，该信号主要针对 翻译后机制，PGN上调LTC 4S的表达，通过 （2）在过敏原激发的肺部炎症模型中，CysLT 1在炎症反应中更重要，CysLT 2与肺重塑更相关，MC衍生的PGD 2和PGE 2通过抑制LTC 4S，对抗CysLT的作用;和（3）LTC 4S作为同源三聚体起作用，每个单体含有四个α螺旋，并且Arg-51和Tyr-93参与催化，而Ile-27、瓦尔-35、瓦尔-49、Arg-51、Ala-52、Asn-55、Tyr-59、Tyr-93、Tyr-97和Ala-112形成LTA 4和GSH的结合位点。因此，我们提出以下具体目标：1）阐明PGN上调和 PGD 2下调mBMMC中LTC 4S的表达; 2）检查LTC 4和PGD 2在气道炎症的肥大细胞依赖性模型和气道重塑的慢性模型中的体内作用;和3）通过X射线晶体学确定人LTC 4S的三维结构。