The effect of a protein-lipid complex from human milk against pneumococcal otitis

描述(申请人提供)：急性中耳炎(AOM)是美国最常见的儿童感染，超过60%的婴儿在出生后一年内受到影响，导致严重的疼痛和一过性听力损失。如果不治疗，长期感染可能会导致严重的并发症，包括言语和语言发育延迟，甚至永久性听力障碍。肺炎链球菌是AOM最常见的病原菌，也是大多数感染后并发症的致病菌。肺炎球菌衣壳结合疫苗在预防侵袭性疾病方面是有效的，但由于非疫苗血清型的感染率增加，对AOM总发作的影响很小。这一事实，再加上全球出现具有抗药性的肺炎球菌菌株，突出表明迫切需要继续努力开发有效的肺炎球菌疾病预防和治疗药物。以前的工作已经从人乳(Hamlet)中发现了一种蛋白质-脂肪复合体，它使用一种与常见抗生素分开的杀菌机制，有效地杀死肺炎链球菌，并且不容易产生细菌耐药性。这一机制是特定的，哈姆雷特的治疗已被证明在显著减少体内鼻咽在小鼠模型中的定植，揭示了未来用于治疗儿童中耳炎的巨大前景。这项建议的目的是为了更好地了解哈姆雷特诱导肺炎链球菌死亡的机制，并评估哈姆雷特作为治疗剂的有效性。据推测，哈姆雷特的目标是肺炎球菌成分和专门用于细胞自杀的遗传机制，这种活动可以被利用来预防和治疗肺炎球菌定植和中耳炎。这项提案的具体目标旨在直接检验这些假设。在目标1中提出的研究将描述哈姆雷特诱导肺炎球菌死亡的机制。首先，通过检测含有胆碱的肺炎球菌表面成分的各种制剂在固相结合试验和体外结合试验中抑制HAMLET诱导的死亡和与HAMLET相互作用的能力，来阐明HAMLET的受体结构。其次，将筛选带有签名标签的转座子突变文库，以识别离子转运体或其他对哈姆雷特活动至关重要的肺炎球菌成分。在目标2中，拟议的研究将评估Hamlet在体内预防和根除鼻咽定植和预防中耳炎的能力，该模型是AOM的金标准动物模型。这些研究的结果将确定哈姆雷特在未来儿童治疗研究中的用途，并具有巨大的潜力，可以开发出更好的预防和治疗肺炎球菌定植和AOM的药物，并降低耐药性发展的风险。 公共卫生相关性：急性中耳炎是美国最常见的儿童感染诊断。这项建议涉及从人奶中提取的一种蛋白质-脂肪复合体对肺炎链球菌的抗菌机制和潜在的治疗效果。肺炎链球菌是一种与急性中耳炎高度相关的细菌病原体。

DESCRIPTION (provided by applicant): Acute otitis media (AOM) is the most common childhood infection in the United States, affecting over 60% of infants during their first year of life, causing significant pain and transient hearing loss. If left untreated, a prolonged infection can lead to serious complications, including delays in speech and language development and even permanent hearing impairment. Streptococcus pneumoniae (pneumococcal) is the most commonly isolated etiologic agent of AOM, and is also the species responsible for most post-infectious complications. The pneumococcal capsular conjugate vaccine is effective in preventing invasive disease, but has had little impact on total episodes of AOM due to increased rates of infection with non-vaccine serotypes. This fact, coupled with the global emergence of antibiotic-resistant pneumococcal strains, emphasizes the urgent need for continued efforts in developing effective preventive and therapeutic agents against pneumococcal disease. Previous work has identified a protein-lipid complex from human milk (HAMLET) that effectively kills S. pneumoniae, using a bactericidal mechanism that is separate from common antibiotics and is not susceptible to bacterial resistance development. This mechanism is specific, and treatment with HAMLET has been shown to be effective in significantly reducing in vivo nasopharyngeal colonization in a mouse model, revealing great promise for future use in treating otitis media in children. The objectives of this proposal are to develop a greater understanding of the mechanism of HAMLET-induced death in S. pneumoniae, and to assess the utility of HAMLET as a therapeutic agent. It is hypothesized that HAMLET targets pneumococcal components and genetic machinery specifically used for cell suicide, and that this activity can be exploited to prevent and treat pneumococcal colonization and otitis media. The specific aims of this proposal have been designed to directly test these hypotheses. Studies proposed in Aim 1 will characterize the mechanism of HAMLET-induced death in the pneumococcus. First, the receptor structure for HAMLET will be elucidated by testing various preparations of choline-containing pneumococcal surface components for their ability to inhibit HAMLET-induced death and to interact with HAMLET in solid-phase and in vitro binding assays. Secondly, a signature-tagged transposon mutation library will be screened to identify ion transporters or other pneumococcal components critical for HAMLET's activity. In Aim 2, the proposed studies will assess the ability of HAMLET to prevent and eradicate nasopharyngeal colonization and prevent otitis media in vivo using the chinchilla, the gold standard animal model of AOM. Results from these studies will determine the utility of HAMLET for future treatment studies in children and also have great potential to lead to the development of better preventive and therapeutic agents against pneumococcal colonization and AOM, with less risk for resistance development. PUBLIC HEALTH RELEVANCE: Acute otitis media is the most commonly diagnosed childhood infection in the United States. This proposal addresses the anti-bacterial mechanism and potential therapeutic effect of a protein-lipid complex from human milk against Streptococcus pneumoniae, the bacterial pathogen most highly associated with acute otitis media.