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: 6839462
• 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/6839462
• 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(申请人提供)：膜甘油磷脂的酶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，当血小板和其他细胞类型被生理激活时，LPA的浓度会增加。众所周知，LPA对内皮细胞和肺结构细胞有生长作用，但对其他类型细胞的影响知之甚少。直到最近人们才意识到，LPA通过结合一系列称为内皮分化基因或EDG受体的细胞表面分子来发挥其细胞效应。本研究发现：(1)EDG受体mRNA在T淋巴细胞和树突状细胞中高表达；(2)LPA能显著促进亚最大活化T细胞分泌IL-13；(3)人段性变应原刺激后，支气管肺泡灌洗液中LPA浓度升高。在正在进行的研究中，我们发现LPA影响树突状细胞的成熟以抑制IL-12的产生，并且在小鼠变应原致敏时联合应用LPA显著增加了肺嗜酸性粒细胞对呼吸道变应原攻击的反应。我们开发了一种新的方法来测量LPA的皮摩尔量，并表明激活的树突状细胞可以释放细胞外的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，以及携带LPA受体基因Ipa1、Ipa2和Ipa3的靶向缺失的小鼠。我们提出了四个目标来剖析LPA及其受体在变态反应性肺免疫反应中的作用。在目标1中，我们将确定LPA增强T细胞IL-13表达的分子机制，并验证LPA受体与MAPK和NF-kappaB活化偶联的假设。在目标2中，我们将检验LPA在限制抗原可获得性的条件下促进Th2细胞从原始的CD4+前体细胞分化的假设。在目标3中，我们将使用过敏原致敏和挑战的小鼠模型，并测试LPA及其受体在T细胞运输和肺部过敏性炎症中所必需的假设。在目标4中，我们将在体内测试LPA启动肺树突状细胞以获得Th2促进表型的假设。综上所述，这些研究将首次全面分析变态反应性炎症性疾病中一种新的溶血磷脂和信号转导途径。