Mediators and Mechanisms of Innate Immunity in the Lung

肺部先天免疫的介质和机制

• 批准号: 7105905
• 负责人: CRAIG GERARD
• 金额: $ 42.25万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-30 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7105905
• 关键词: G protein; antiinflammatory agents; binding proteins; biological signal transduction; complement; complement receptor; disease /disorder model; genetically modified animals; human genetic material tag; immunity; immunogenetics; immunopathology; inflammation; inhibitor /antagonist; laboratory mouse; lipid metabolism; molecular pathology; phenotype; pituitary adrenal axis; protein protein interaction; protein structure; protein structure function; receptor binding; receptor coupling; receptor expression; septic shock; thin layer chromatography; triglycerides

DESCRIPTION (provided by applicant): C5L2 is an enigmatic serpentine receptor that is co-expressed with the C5a receptor on many cell types including PMN neutrophils. The absence of coupling of C5L2 to G proteins, as well as our preliminary data, suggest that this receptor does not transduce signals like the classical C5a receptor, but may instead modulate the biological activity of C5a. In vivo studies support the concept that C5L2 acts as a decoy receptor. Alternatively, it may affect function through formation of intermolecular complexes (eg., heterodimers) with the C5aR. A distinct signaling mechanism may also exist for C5L2. Mice bearing a targeted deletion of C5L2 exhibit enhanced biological activity of C5a/C5adesArg. Thus, the biological function of C5L2 appears to be to limit the proinflammatory response to the anaphylatoxin utilizing one or more of the mechanisms described above. Accordingly, up-regulation of C5L2 may be of benefit in inflammatory states driven by C5a, potentially in sepsis, asthma, cystic fibrosis and chronic obstructive lung disease. Other potential actions of C5L2 that have been proposed include up-regulation of the anti- inflammatory neuroendocrine axis, regulation of triglyceride synthesis, and homing of stem cells to bone marrow. The tools we have created in the mouse will allow for proof or rejection of these responses as mediated by C5L2. In the current renewal application, we propose to characterize the functional interactions of C5L2 with its ligands, C5a and C5adeSArg, and its relationship with the classical C5a receptor through the following Specific Aims: 1) we will characterize the phenotype of C5L2-/- mice in the naive state, in models of immune complex injury, septic shock, and Th1/Th2 inflammation. We will further investigate the role of C5L2 in triglyceride synthesis and regulation of the adrenocortical axis. 2) We will generate mice in which C5L2 is over-expressed in the lung, and mice in which human C5aR is expressed in place of murine CSaR, allowing pharmacological blockade of the C5aR with receptor antagonists. These animals will be used to evaluate the anti-inflammatory actions of C5L2 in immune complex injury and septic shock. 3) We will determine the structure of C5L2 as a C5a binding protein. Finally, 4) we will examine potential alternative signaling mechanisms mediated by binding of C5a/C5adeSArg to C5L2. Successful completion of this research program will increase our knowledge relevant to acute and chronic lung injury. Potential treatment options for these diseases could arise through translational research inspired by this proposal.

描述（由申请人提供）：C5L2 是一种神秘的蛇形受体，在包括 PMN 中性粒细胞在内的许多细胞类型上与 C5a 受体共表达。 C5L2 与 G 蛋白不存在偶联，以及我们的初步数据表明，该受体不像经典的 C5a 受体那样转导信号，而是可能调节 C5a 的生物活性。体内研究支持 C5L2 作为诱饵受体的概念。或者，它可能通过与 C5aR 形成分子间复合物（例如异二聚体）来影响功能。 C5L2 也可能存在独特的信号传导机制。带有 C5L2 靶向缺失的小鼠表现出 C5a/C5adesArg 增强的生物活性。因此，C5L2的生物学功能似乎是利用上述的一种或多种机制来限制对过敏毒素的促炎反应。因此，C5L2 的上调可能有益于 C5a 驱动的炎症状态，可能有助于败血症、哮喘、囊性纤维化和慢性阻塞性肺病。已提出的 C5L2 的其他潜在作用包括上调抗炎神经内分泌轴、调节甘油三酯合成以及干细胞归巢至骨髓。我们在小鼠中创建的工具将允许证明或拒绝由 C5L2 介导的这些反应。在当前的更新申请中，我们建议通过以下具体目标来表征C5L2与其配体C5a和C5adeSArg的功能相互作用，及其与经典C5a受体的关系：1）我们将表征C5L2-/-小鼠的表型在免疫复合物损伤、感染性休克和 Th1/Th2 炎症模型中的初始状态。我们将进一步研究C5L2在甘油三酯合成和肾上腺皮质轴调节中的作用。 2)我们将产生C5L2在肺中过度表达的小鼠，以及人C5aR代替鼠CSaR表达的小鼠，从而允许用受体拮抗剂对C5aR进行药理学阻断。这些动物将用于评估 C5L2 在免疫复合物损伤和感染性休克中的抗炎作用。 3)我们将确定C5L2作为C5a结合蛋白的结构。最后，4) 我们将研究由 C5a/C5adeSArg 与 C5L2 结合介导的潜在替代信号机制。该研究计划的成功完成将增加我们对急性和慢性肺损伤的了解。通过受该提案启发的转化研究，可能会出现这些疾病的潜在治疗方案。