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

描述（由申请人提供）：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，导致严重疼痛和短暂性听力损失。如果不及时治疗，长期感染可能导致严重的并发症，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（肺炎球菌）是AOM最常见的病原体，也是大多数感染后并发症的病原体。肺炎球菌荚膜结合疫苗可有效预防侵袭性疾病，但由于非疫苗血清型的感染率增加，对AOM的总发作影响不大。这一事实，再加上全球出现的肺炎球菌耐药性菌株，强调迫切需要继续努力，开发有效的预防和治疗剂，以对付肺炎球菌疾病。以前的工作已经从母乳中鉴定出一种蛋白质-脂质复合物（哈姆雷特），它可以有效地杀死沙门氏菌。肺炎，使用与普通抗生素不同的杀菌机制，不易产生细菌耐药性。这种机制是特异性的，并且已经证明用哈姆雷特治疗在显著减少小鼠模型中的体内鼻咽定殖方面是有效的，揭示了未来用于治疗儿童中耳炎的巨大前景。本研究的目的是进一步了解HAMLET诱导S.肺炎，并评估哈姆雷特作为治疗剂的效用。假设哈姆雷特靶向肺炎球菌组分和专门用于细胞自杀的遗传机制，并且这种活性可用于预防和治疗肺炎球菌定植和中耳炎。本提案的具体目标旨在直接检验这些假设。目的1中提出的研究将描述HAMLET诱导肺炎球菌死亡的机制。首先，哈姆雷特的受体结构将通过测试含胆碱的肺炎球菌表面组分的各种制剂来阐明，以确定其抑制HAMLET诱导的死亡并在固相和体外结合试验中与HAMLET相互作用的能力。其次，将筛选标记有特征的转座子突变文库，以鉴定离子转运蛋白或对哈姆雷特活性至关重要的其他肺炎球菌组分。在目标2中，拟定的研究将使用灰鼠（AOM的金标准动物模型）评估哈姆雷特预防和根除鼻咽定植以及预防体内中耳炎的能力。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实用性，并有很大的潜力开发出更好的预防和治疗肺炎球菌定植和AOM的药物，降低耐药性发展的风险。

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.