C3A ACTIVATION OF LEUKOCYTES IN INFLAMMATION

描述(改编自调查者摘要)：渗透 白细胞是急性和慢性炎症性疾病的特征。 疾病。大量证据表明，中性粒细胞、单核细胞和 嗜酸性粒细胞通过特定的趋化作用被吸引到炎症部位。 因素，包括补体因素，如C3a和C5a，其中 然后，招募的细胞可能会被细胞和/或体液进一步激活 局部组织部位的中介人。C3a是由第三个也是最多的 补体的丰富成分，并已被证明选择性地诱导 嗜酸性粒细胞的趋化和脱颗粒，但不包括中性粒细胞。我们的 已公布的数据表明，中性粒细胞的C3a激活完全是 继发于C3a刺激嗜酸性粒细胞(Daffern等人，J.Exp.地中海医院。 181：2129,1995)。C3a和C5a受体表达于细胞表面 许多炎性细胞和这些细胞通过细胞内被激活 尚未完全确定或了解的机制。我们的 初步的功能研究表明，C3a诱导出更独特的或 嗜酸性粒细胞中不同的信号事件，也许单核细胞也不同 尽管中性粒细胞上存在C3a受体 单元类型。叶博士的实验室最近分离出了编码 七螺旋跨膜的新成员C3a受体(C3aR) 一类称为视紫红质家族的受体(Roglic等人)。BBA， 1305：39,1996)。人类C3aR的cDNA被证明编码一个G 具有独特胞外环的蛋白质偶联受体(-170个氨基酸) 在第四和第五跨膜区域之间。这么大 细胞外环结构是没有观察到的其他成员的特征 视紫红质受体家族迄今已被阐明。我们建议这一点 异常大的胞外环路是成为 完整C3a分子的受体结合/效应部位。我们有 产生抗胞外环C3aR和C3aR的多克隆抗体 这种免疫反应剂检测天然的细胞表面受体。生物活性 合成的C3a多肽类似物，早在几年前就在我们的 实验室，现在也有望成为绘制效应器的宝贵工具 C3a受体上的结合部位。我们的研究将探索C3a 中性粒细胞、单核细胞和嗜酸性粒细胞的信号/转导机制 以及确定C3a/C3aR相互作用的特征和 C3a受体分子上效应部位的作图。在这 应用程序，我们提出了一种协作研究来比较功能 中性粒细胞的反应、结合参数和分子机制 单核细胞和嗜酸性粒细胞被C3a激活 过敏毒素。

DESCRIPTION (Adapted from Investigator's abstract): Infiltration of leukocytes is a characteristic of both acute and chronic inflammatory diseases. Extensive evidence indicates that neutrophils, monocytes and eosinophils are attracted to sites of inflammation by specific chemotactic factors, including complement factors such as C3a and C5a, where the recruited cells may then be further activated by cellular and/or humoral mediators at local tissue sites. C3a is generated from the third and most abundant component of complement and has been shown to selectively induce chemotaxis and degranulation of eosinophils, but not neutrophils. Our published data indicates that C3a activation of neutrophils is entirely secondary to C3a stimulation of eosinophils (Daffern et al., J. Exp. Med. 181:2129, 1995). Receptors to C3a and C5a are expressed on the surface of many inflammatory cells and these cells are activated through intracellular mechanisms that have yet to be fully characterized or understood. Our preliminary functional studies suggest that C3a induces more unique or different signaling events in eosinophils, and perhaps monocytes, than it does in neutrophils despite the presence of C3a receptors on each of these cell types. Dr. Ye's laboratory has recently isolated the cDNA coding for the C3a receptor (C3aR), a new member of the heptahelical transmembrane class of receptors known as the Rhodopsin family (Roglic et al. BBA, 1305:39, 1996). The cDNA for human C3aR has been shown to encode a G protein-coupled receptor with a unique extracellular loop (-170 amino acids) between the fourth and fifth transmembrane regions. This large extracellular loop structure is a feature observed in no other member of the Rhodopsin family of receptors elucidated to date. We propose that this unusually large extracellular loop is a prime candidate for being the receptor binding/effector site of the intact C3a molecule. We have generated polyclonal antibodies to the large extracellular loop of C3aR and this immunoreagent detects the native cell surface receptor. The bioactive synthetic C3a peptide analogues, that were designed years earlier in our laboratory, now also promise to be valuable tools in mapping the effector binding site on the C3a receptor. Our studies will explore C3a signaling/transduction mechanisms in neutrophils, monocytes and eosinophils, as well as determine characteristics of the C3a/C3aR interactions and mapping of the effector site on the C3a receptor molecule. In this application, we propose a collaborative study to compare the functional responses, binding parameters and molecular mechanisms by which neutrophils, monocytes and eosinophils are differentially activated by the C3a anaphylatoxin.