Antibody therapy of MRSA colonization and infection

摘要 耐甲氧西林金黄色葡萄球菌(MRSA)在鼻咽和胃肠道的定植 个人和入院病人的情况。殖民是社区获得性和 医院获得性MRSA侵袭性疾病。MRSA感染与治疗失败有关，增加 发病率和死亡率的增加。先前试图开发疫苗或免疫疗法来预防 耐甲氧西林金黄色葡萄球菌定植或侵袭性疾病或改善耐甲氧西林金黄色葡萄球菌感染结局的努力都失败了。受感染的 个体不能产生保护性抗体反应(免疫)，这使得MRSA能够持续存在于 寄主组织和引起复发的疾病。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剂(SBI)。水疗中心 和sbi通过结合抗体的Fcγ结构域来阻断人免疫球蛋白的效应器功能。SPA还绑定到 VH3-独特型免疫球蛋白的变异重链和交联型IgM B细胞受体，从而 激活B细胞增殖和分泌不能识别MRSA的VH3克隆抗体。这个B细胞 SpA的超抗原活性(BCSA)在MRSA过程中对抗体反应的转移至关重要 殖民和侵袭性疾病。在这里，我们描述了一种单抗，单抗3F6，它结合和 中和水疗和水疗。我们发现，单抗3F6在Fcγ处的半乳糖基化促进C1q结合，单抗3F6- 耐甲氧西林金黄色葡萄球菌的吞噬细胞依赖杀伤作用及其对血流的保护作用 感染。此外，我们分离了Fcγ中的氨基酸替换，这些替换取消了spA和sbi的结合并增强了 变异型单抗3F6的OPK活性。我们还报道，SpA对于抑制抗体是必不可少的。 对细菌定植因素的应答(BCSA)，从而使金黄色葡萄球菌在 鼻咽和胃肠道。小鼠静脉注射单抗3F6可中和循环SpA和 阻断其BCSA，从而促进针对细菌表面抗原的抗体反应和清除 来自鼻咽和胃肠道的金黄色葡萄球菌。在这里，我们将检验静脉给药的假设 在临床前模型中用糖链和Fcγ工程的人3F6-IgG1a)产生广谱抗体 对金黄色葡萄球菌的反应，b)促进MSSA和MRSA的非殖民化，c)诱导免疫以防止 重新定植以及侵袭性MSSA和MRSA病，以及d)改善MRSA的预后 血液感染。Glyco和FCγ设计的3F6抗体可以达到这样的产品特征 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.