The alternative pathway of complement and properdin in Neisseria

补体(C)的替代途径(AP)是天然免疫防御的关键环节。 淋球菌(Ng)感染。备解素(P)是已知的唯一正向调节C。 本研究的主题是了解P在Ng发病机制中的作用。P最著名的功能是 稳定Ap C3转化酶，促进C3沉积。AP激活的一种新机制--P 最近已经描述了直接结合到表面(包括Ng)和激活AP。在目标1中，我们 将测量宫颈分泌物中的磷，并将磷水平与中性粒细胞(磷的主要储存库)流入和 明确P在宫颈分泌物中激活AP中的作用。我们的合作者已经 研制针对保守的Ng脂低聚糖(LOS)的多肽模拟表位Ng疫苗 结构。我们将研究P在该候选疫苗抗体沉积的C3的AP扩增中的作用。P 还可结合活的完整巨噬细胞(MP)和多种凋亡和坏死性细胞系。我们 假设P与Ng结合，将细菌与细胞联系起来。我们有初步证据表明P的配基 在Ng上的是PorB。在目标2中，我们将限制PorB作为P的Ng配体的身份，并定义 凝血酶原蛋白1重复(TSR)结构域在P(P几乎由6个TSR结构域组成) 与Ng结合。此外，我们将研究P在Ng与MPS和可存活的宫颈之间的联系中的作用 上皮细胞和宫颈上皮细胞处于不同阶段的凋亡和坏死。P具有新型Cmannosyl 它的14个色氨酸残基上的替代品，使它成为C-甘露糖化程度最高的人类 已知的蛋白质。在目标3中，我们将研究甘露糖基残基在结合和激活 AP On Ng.P与正常(非凋亡)MPS结合，先前的一项研究表明，C-甘露糖基化的TSR源于 多肽与MPS结合，增强内毒素诱导的细胞毒作用。我们假设甘露糖残留物 关于P参与MPS上的甘露糖受体(例如MR和DC-SIGN)，以及P-MP相互作用可以 降低TLR-4依赖的LOS信令阈值。我们将描述P甘露糖在体内的作用 与MPS结合并通过LOS调节TLR4依赖的信号。

The alternative pathway (AP) of complement (C) forms a key arm of innate immune defenses against Neisseria gonorrhoeae (Ng) infections. Properdin (P) is the only known positive regulator of C. The central theme of this proposal is to understand the role of P in Ng pathogenesis. The best known function of P is to stabilize AP C3 convertases and enhance C3 deposition. A novel mechanism of AP activation whereby P binds directly to surfaces (including Ng) and inifiates AP activafion has recently been described. In Aim 1 we will measure P in cervical secretions and correlate P levels with PMN (the major reservoir for P) influx and define the role of P in activating the AP in the context of cervical secretions. Our collaborators have developed a pepfide mimitope Ng vaccine directed against a conserved Ng lipooligosaccharide (LOS) structure. We will examine the role of P in AP amplification of C3 deposited by this vaccine candidate Ab. P also binds to live intact macrophages (MP) and a diverse array of apoptotic and necrotic cell lines. We hypothesize that P bound to Ng bridges bacteria to cells. We have preliminary evidence that the ligand for P on Ng is PorB. In Aim 2 we will confinn the identity of PorB as the Ng ligand for P and define the thrombospondin type 1 repeat (TSR) domain in P (P is composed almost enfirely of six TSR domains) that binds to Ng. Further, we will study the role of P in the association of Ng with MPs and viable cervical epithelial cells and cervical epithelial cells at various stages of apoptosis and necrosis. P possesses novel Cmannosyl substitufions at 14 of its tryptophan residues, making it the most heavily C-mannosylated human protein known. In Aim 3, we will examine the role of the mannosyl residues in binding to, and activafing the AP on Ng. P binds to normal (nonapoptofic) MPs and a prior study has shown that C-mannosylated TSRderived peptides bind MPs and enhance LPS-induced cytotoxicity. We hypothesize that mannose residues on P engage mannose receptors (e.g. MR and DC-SIGN) on MPs and that the P-MP interaction could decrease the TLR-4 dependant LOS signaling threshold. We will characterize the role of P mannosylafion in binding to MPs and in modulating TLR4-dependent signaling by LOS.