LPA and Edg Receptors in the Pulmonary Immune Respose

LPA 和 Edg 受体在肺免疫反应中的作用

• 批准号: 6733798
• 负责人: Steve N Georas
• 金额: $ 40.88万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2007-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6733798
• 关键词: T lymphocyte; adolescence (12-20); cellular immunity; clinical research; dendritic cells; enzyme linked immunosorbent assay; flow cytometry; gel mobility shift assay; gene expression; helper T lymphocyte; human middle age (35-64); human subject; inflammation; interleukin 13; laboratory mouse; lung; lysophospholipids; messenger RNA; mitogen activated protein kinase; phosphatidate; receptor expression; western blottings; young adult human (21-34)

DESCRIPTION (provided by applicant): The enzymatic metabolism of membrane glycerophospholipids generates bioactive lysophospholipids including lysophosphatidic acid (LPA). LPA is present in normal serum, and is increased in concentration upon physiologic activation of platelets and other cell types. LPA has well-known growth effects on endothelium and lung structural cells, but its effects on other cell types are poorly understood. It was only recently appreciated that LPA exerts its cellular effects by binding a family of cell-surface molecules termed the endothelial differentiation gene, or Edg, receptors. The present study was prompted by our observations that: (i) Edg receptor mRNA is highly expressed in T lymphocytes and dendritic cells, (ii) LPA strikingly enhances the secretion of interleukin 13 (IL-13) from sub maximally activated T cells, and (iii) the concentration of LPA was enhanced in bronchoalveolar lavage fluids after segmental allergen challenge of human subjects. In ongoing research, we found that LPA influences dendritic cell maturation to inhibit IL-12 production, and that co-administration of LPA at the time of allergen sensitization in mice markedly augments lung eosinophilia in response to airway allergen challenge. We have developed a novel method to measure picomolar quantities of LPA and show that activated dendritic cells can release extracellular LPA. In a new collaboration, we have been provided access to a panel of high-titer antibodies directed against the three LPA receptors, and mice bearing targeted deletions in each of the LPA receptor genes Ipa1, Ipa2, and Ipa3. We propose four aims to dissect the role of LPA and its receptors in the allergic pulmonary immune response. In Aim 1, we will define the molecular mechanisms by which LPA augments IL-13 expression in T cells, and test the hypothesis that this involves coupling of LPA receptors to MAPK and NF-kappaB activation. In Aim 2, we will test the hypothesis LPA augments the differentiation of Th2 cells from naive CD4+ precursors under conditions of limiting antigen availability. In Aim 3, we will use a mouse model of allergen sensitization and challenge and test the hypothesis that LPA and its receptors are required for T cell trafficking and pulmonary allergic inflammation. In Aim 4, we will test the hypothesis that LPA primes lung dendritic cells for a Th2-promoting phenotype in vivo. Taken together, these studies will provide the first comprehensive analysis of a novel lysophospholipid and signal transduction pathway in allergic inflammatory diseases.

描述（由申请人提供）：膜甘油磷脂的酶促代谢产生生物活性溶血磷脂，包括溶血磷脂酸（LPA）。 LPA 存在于正常血清中，并且在血小板和其他细胞类型的生理激活后其浓度增加。 LPA 对内皮细胞和肺结构细胞具有众所周知的生长作用，但其对其他细胞类型的作用却知之甚少。 直到最近人们才认识到，LPA 通过结合称为内皮分化基因或 Edg 受体的细胞表面分子家族来发挥其细胞作用。 本研究是由我们的观察结果推动的：(i) Edg 受体 mRNA 在 T 淋巴细胞和树突状细胞中高度表达，(ii) LPA 显着增强次最大激活 T 细胞的白细胞介素 13 (IL-13) 分泌，以及(iii) 对人类受试者进行分段过敏原激发后，支气管肺泡灌洗液中 LPA 的浓度增加。 在正在进行的研究中，我们发现 LPA 影响树突状细胞成熟，从而抑制 IL-12 的产生，并且在小鼠过敏原致敏时联合给予 LPA 会显着增加肺部嗜酸粒细胞增多，以应对气道过敏原的挑战。 我们开发了一种新方法来测量皮摩尔量的 LPA，并表明活化的树突状细胞可以释放细胞外 LPA。 在一项新的合作中，我们获得了一组针对三种 LPA 受体的高滴度抗体，以及 LPA 受体基因 Ipa1、Ipa2 和 Ipa3 中每个受体都有针对性缺失的小鼠。 我们提出四个目标来剖析 LPA 及其受体在过敏性肺部免疫反应中的作用。 在目标 1 中，我们将定义 LPA 增强 T 细胞中 IL-13 表达的分子机制，并测试这涉及 LPA 受体与 MAPK 和 NF-kappaB 激活偶联的假设。 在目标 2 中，我们将检验以下假设：在限制抗原可用性的条件下，LPA 会增强 Th2 细胞从初始 CD4+ 前体细胞的分化。 在目标 3 中，我们将使用过敏原致敏的小鼠模型，并挑战和测试 T 细胞运输和肺部过敏性炎症需要 LPA 及其受体的假设。 在目标 4 中，我们将测试 LPA 在体内启动肺树突状细胞以形成 Th2 促进表型的假设。 总而言之，这些研究将首次对过敏性炎症疾病中的新型溶血磷脂和信号转导途径进行全面分析。