Soluble high-affinity T cell receptors prevent MRSA lethality

描述（由申请人提供）：耐甲氧西林金黄色葡萄球菌（MRSA）和甲氧西林敏感金黄色葡萄球菌（MSSA）是高度严重的人类健康威胁，可导致一系列疾病。最近，美国疾病控制和预防中心及其同事报告说，MRSA是美国严重感染和传染病死亡的最重要原因。MRSA和MSSA致死率的一个主要因素是分泌的毒素，被称为超级抗原。由于美国军方在1969年终止的旧生物武器计划下储存了大量葡萄球菌肠毒素B (SEB)，因此人们几十年来一直认识到这些超级抗原的致命性。毒素的作用机制是众所周知的-它们通过与T细胞上的T细胞受体结合并刺激炎症细胞因子的大量释放而在细胞外起作用。这项工作的目的是测试使用一种新的潜在药物的可行性，这种药物是一种可溶性T细胞受体蛋白（G5-8），它被设计成与SEB具有非常高的亲和力结合，以防止致命。将对两种SEB致死性兔模型进行检查，一种是肺部单独暴露于毒素（如生物恐怖事件中发生的那样），另一种是肺部感染产生SEB的MRSA菌株。第一阶段工作的假设是可以提高工程V2蛋白G5-8的产量，并且可以确定减少与SEB暴露相关的肺部疾病的严重程度的剂量和给药时间。具体目的是：1)确定优化V2-TCR G5-8蛋白产量和长期储存的最佳条件；2)观察G5-8对SEB肺内攻击致兔死亡的保护作用；3)确定G5-8对SEB+ CA-MRSA USA400菌株肺内攻击导致家兔死亡的保护效果。在II期工作中，ImmuVen将测试长期储存的G5-8是否能防止暴露于额外SEB+ MRSA菌株的家兔的死亡，以及G5-8是否可以以雾化形式使用。ImmuVen还将开始开发cGMP流程，用于其他临床前和临床研究。G5-8和其他金黄色葡萄球菌外毒素（SEC, TSST-1）的类似蛋白正在开发中，为治疗MRSA和MSSA引起或恶化的一系列疾病提供了临床和商业机会。

DESCRIPTION (provided by applicant): Methicillin resistant Staphylococcus aureus (MRSA) and methicillin sensitive S. aureus (MSSA) are highly significant human health threats that are responsible for a range of diseases. Recently, the CDC and colleagues reported that MRSA are the most significant causes of serious infections and infectious disease deaths in the United States. A major factor involved in the lethality of MRSA and MSSA are secreted toxins, known as superantigens. The lethality associated with these superantigens has been appreciated for decades, as the U.S. military stockpiled large amounts of staphylococcal enterotoxin B (SEB) under its old bioweapons program that was terminated in 1969. The mechanism of action of the toxins is well known - they act extracellularly by binding to the T cell receptor on T cells and stimulating massive release of inflammatory cytokines. The objective of the proposed work is to test the feasibility of using a novel potential drug, a soluble T cell receptor protein (G5-8) that has been engineered for very high-affinity binding to SEB, to prevent lethality. Two rabbit models of SEB-induced lethality will be examined, pulmonary exposure to the toxin alone (as would occur in a bioterrorism incident) or pulmonary infection with a strain of MRSA that produces SEB. The hypotheses of the Phase I work are that yields of the engineered V2 protein G5-8 can be improved, and that the doses and timing of administration that will reduce the severity of pulmonary diseases associated with SEB exposure can be determined. The Specific Aims are: 1) To determine the best conditions for optimizing the yield and long-term storage of the V2-TCR G5-8 protein; 2) To determine the efficacy of using G5-8 to protect rabbits from death due to intrapulmonary challenge with SEB; and 3) To determine the efficacy of using G5-8 to protect rabbits from death due to intrapulmonary challenge with an SEB+ CA-MRSA USA400 strain. In Phase II work, ImmuVen would test whether long-term stored G5-8 prevents lethality in rabbits exposed to additional SEB+ MRSA strains, and whether the G5-8 can be used in nebulized form. ImmuVen will also begin development of a cGMP process for additional pre-clinical and clinical studies. G5-8 and similar proteins in development for other S. aureus exotoxins (SEC, TSST-1) represent clinical and commercial opportunities to treat a host of diseases caused or worsened by MRSA and MSSA. PUBLIC HEALTH RELEVANCE: Antibiotic-resistant Staphylococcus aureus isolates frequently initiate serious human diseases through the bacterium's colonization of respiratory mucosa and skin, followed by secretion of potent toxins referred to as superantigens. Illnesses include serious post- viral pneumonias, allergic skin diseases, and delayed wound healing that affect thousands of individuals each year in the United States. The secreted toxins are directly involved in the disease effects, including death. This application studies a novel protein- based drug that acts to block the disease-causing effects of bronchially-administered superantigens (as would be the case in a bioterrorism agent) and of infections with antibiotic-resistant S. aureus.