Antibody therapy of MRSA colonization and infection

摘要 耐甲氧西林金黄色葡萄球菌（MRSA）定植于健康人的鼻咽和胃肠道， 个人和医院收治的病人。定植是社区获得性和 医院获得性MRSA侵袭性疾病。MRSA感染与治疗失败有关， 发病率和死亡率增加。先前尝试开发疫苗或免疫疗法，可以防止 MRSA定植或侵袭性疾病或改善MRSA感染结果的药物均失败。感染 个体不能产生保护性抗体反应（免疫力），这使得MRSA在体内持续存在。 宿主组织并导致疾病复发。MRSA免疫逃逸是基于免疫球蛋白结合 蛋白质，特别是葡萄球菌蛋白A（SpA）和葡萄球菌免疫球蛋白结合物（Sbi）。spa 和Sbi通过结合抗体的Fc γ结构域阻断人IgG的效应子功能。SpA还与 VH 3-独特型免疫球蛋白的变体重链并交联IgM B细胞受体，从而 激活B细胞增殖和分泌不能识别MRSA的VH 3克隆抗体。这个B细胞 SpA的超抗原活性（BCSA）对于MRSA期间抗体应答的转移至关重要 殖民化和侵袭性疾病。在这里，我们描述了一种单克隆抗体，单克隆抗体3F6，它结合， 中和SpA和Sbi。我们发现，单克隆抗体3F6在Fc γ的半乳糖基化促进C1q结合，单克隆抗体3F6- MRSA的依赖性调理吞噬杀伤（OPK）和针对MRSA血流的小鼠保护 感染此外，我们分离了Fc γ中的氨基酸取代，其消除了SpA和Sbi结合，并增强了SpA和Sbi的结合。 变体MAb 3F6的OPK活性。我们还报告，SpA是必不可少的抑制抗体， 针对细菌定殖因子的BCSA应答，从而使S.金黄色葡萄球菌持久性 鼻咽和胃肠道。将MAb 3F6静脉内给予小鼠可中和循环SpA， 阻断其BCSA，从而促进针对细菌表面抗原的抗体应答， S.金黄色葡萄球菌从鼻咽和胃肠道。在这里，我们将测试的假设，静脉注射给药 在临床前模型中的糖和Fc γ工程化的人3F6-IgG1 针对S.金黄色葡萄球菌，B）促进MSSA和MRSA的去殖民化，c）诱导免疫以防止 再定殖以及侵袭性MSSA和MRSA疾病，和d）改善MRSA的结果 血液感染实现这样的产物谱的糖和Fc γ工程化的3F6抗体可以是 进一步开发用于临床测试，以预防和治疗美国医院的MRSA感染。

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) colonize the nasopharynx and GI tract of healthy individuals and of patients admitted to hospitals. Colonization is the key risk factor for community-acquired and hospital-acquired MRSA invasive diseases. MRSA infection is associated with treatment failure, increased morbidity, and increased mortality. Prior attempts to develop vaccines or immune therapeutics that can prevent MRSA colonization or invasive disease or that improve the outcome of MRSA infections have failed. Infected individuals cannot develop protective antibody responses (immunity), which enables MRSA to persist within host tissues and to cause recurrent disease. MRSA immune escape is based on immunoglobulinbinding proteins, specifically staphylococcal protein A (SpA) and staphylococcal binder of immunoglobulin (Sbi). SpA and Sbi block effector functions of human IgG by binding to the Fcγ domain of antibodies. SpA also binds to the variant heavy chains of VH3-idiotypic immunoglobulin and crosslinks IgM B cell receptors, thereby activating B cell proliferation and the secretion of VH3-clonal antibodies that fail to recognize MRSA. This B cell superantigen activity (BCSA) of SpA is essential for the diversion of antibody responses during MRSA colonization and invasive disease. Here we describe a monoclonal antibody, MAb 3F6, that binds and neutralizes SpA and Sbi. We show that MAb 3F6 galactosylation at Fcγ promotes C1q binding, MAb 3F6- dependent opsonophagocytic killing (OPK) of MRSA and protection of mice against MRSA bloodstream infection. Further, we isolated amino acid substitutions in Fcγ that abolish SpA and Sbi binding and enhance the OPK activity of variant MAb 3F6. We also report that SpA is essential for suppression of antibody responses (BCSA) against bacterial colonization factors, thereby enabling S. aureus persistence in the nasopharynx and GI tract. Intravenous administration of MAb 3F6 into mice neutralizes circulating SpA and blocks its BCSA, thereby promoting antibody responses against bacterial surface antigens and the removal of S. aureus from the nasopharynx and GI tract. Here, we will test the hypotheses that intravenous administration of glyco- and Fcγ-engineered human 3F6-IgG1 in preclinical models a) elicits broad spectrum antibody responses against S. aureus, b) promotes decolonization of MSSA and MRSA, c) induces immunity to prevent re-colonization as well as invasive MSSA and MRSA disease, and d) improves the outcome of MRSA bloodstream infections. Glyco- and Fcγengineered 3F6 antibodies that achieve such product profile can be developed further for clinical testing to prevent and treat MRSA infections in American hospitals.