Novel peptide antagonist theraphy for superantigen- induced lethal shock

细菌超抗原 (SAg) 是一种外毒素，会引发过度的免疫反应，从而可能导致 致命的冲击。因为它们能够在极低的浓度下诱导失能并引起 冲击、其易于生产和卓越的稳定性，SAgs 被归类为 B 类生物 武器。尝试通过阻断下游效应器来逆转 SAg 中毒的有害影响 诸如 TNF-a 之类的药物由于诱导的水平过高而失败。我们制备了肽模拟物 SAg 中的接触结构域和新型 SAg 受体对于诱导 Th1 细胞因子至关重要 防止 D-半乳糖胺 (D-GalN) 致敏的 SEB 小鼠模型发生致命性休克 猪丧失能力。由于 SAg 与革兰氏阴性细菌内毒素 (LPS) 的共同暴露可能更 与临床相关，该提案将检验拮抗肽可以预防 SAg/LPS 的假设 协同致死并拯救暴露的动物，同时保留适应性免疫反应。具体来说 目标 I 我们将确定拮抗肽是否可以保护和拯救小鼠免受 LPS/SAg 致死协同作用。 暴露于 SAg 和肠源性 LPS 可能模拟临床情况，以及 SAg 诱导的机制 病理学与 D-GaIN 致敏发生的病理学不同。在具体目标 II 中，我们将定义 拮抗肽介导的保护机制，表明它对 SAgs 具有广谱性，并且 评估肽拮抗剂是否会损害对抗原或宿主防御的免疫刺激的反应 对抗活体感染。在肽存在的情况下，从接受 SAg 攻击的小鼠血清中纯化出 IgG 将通过针对来自 SAg 不同结构域的肽的 ELISA 测试拮抗剂。这些研究将 随后进行交叉抑制 ELISA 研究，以确定 SAg 保守表位特异性的 IgG 水平。自从 最近的研究表明 SAgs 可能会改变 APC 功能，在特定目标 III 中我们将分析是否 肽拮抗剂 (1) 抑制 SAg 对人单核细胞的作用，特别是 Toll 样受体的表达 和细胞因子诱导或 (2) 损害人树突状细胞向 T 呈递炭疽芽孢杆菌抗原的能力 淋巴细胞。这些研究将进一步明确 SAg 信号传导的新机制以及功效和作用 针对多种 SAg 的新型治疗干预的安全性。如果我们成功的话，这些肽 模拟物很快就可以进行第一阶段测试。

Bacterial superantigens (SAg) are exotoxins that trigger an excessive immune response that may lead to lethal shock. Because of their ability to induce incapacitation at exceedingly low concentrations and to elicit shock, their ease of production and their exceptional stability, SAgs are classified as Category B biological weapons. Attempts to reverse the deleterious effects of SAg intoxication by blocking downstream effectors such as TNF-a have failed owing to the massive levels induced. We prepared peptide mimetics of the contact domains in the SAg and a novel SAg receptor essential for the induction of Th1 cytokines which prevent lethal shock in a D-galactosamine (D-GalN)-sensitized mouse model of SEB as well as incapacitation in pigs. Since co-exposure of SAg with Gram-negative bacterial endotoxin (LPS) may be more clinically relevant, this proposal will test the hypothesis that antagonist peptides can prevent SAg/LPS svnergistic lethality and rescue exposed animals, while preserving adaptive immune responses. In Specific Aim I we will determine whether antagonist peptides protect and rescue mice from LPS/SAg lethal synergy. Exposure to SAg and gut-derived LPS likely mimics the clinical situation, and the mechanism of SAg-induced pathology differs from that which occurs with D-GaIN sensitization. In Specific Aim II, we will define the mechanism of antagonist peptide-mediated protection, show that it is broad-spectrum against SAgs, and assess whether peptide antagonists impair responses to immune stimulation with antigens or host defenses against live infection. IgG purified from the serum of mice challenged with SAg in the presence of peptide antagonist will be.tested by ELISA against peptides from different domains of SAg. These studies will be followed by cross-inhibition ELISA studies to identify IgG levels specific for SAg conserved epitopes. Since recent studies suggest that SAgs may alter APC function, in Specific Aim III we will analyze whether peptide antagonists (1) inhibit SAg effects on human monocytes, particularly Toll-like receptor expression and cytokine induction or (2) impair the ability of human dendritic cells to present B. anthracis antigens to T lymphocytes. These studies will further define a new mechanism of SAg signaling and the efficacy and safety of a novel therapeutic intervention against multiple SAgs. If we are successful, these peptide mimetics could soon be ready for phase I testing.