Pneumococcal capsule and host innate immunity

肺炎球菌荚膜和宿主先天免疫

• 批准号: 8508328
• 负责人: Moon H. Nahm
• 金额: $ 36.63万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8508328
• 关键词: Acetylation; Antibodies; Antimicrobial Cationic Peptides; Bacterial Infections; Binding; Blood; Clinical; Complement; Development; Disease; Drug resistance; Epidemiologic Studies; Future; Genes; Gram-Positive Bacteria; Health; Human; Human body; Immune; Immunity; In Vitro; Individual; Invaded; Knowledge; Laboratories; Lectin; Life; Mannose Binding Lectin; Mannose-Binding Lectins; Measures; Mediating; Membrane; Methods; Molecular; Muramidase; Mus; Mutation; Nasopharynx; Natural Immunity; Nose; Opsonin; Patients; Peptidoglycan; Phagocytosis; Pneumococcal Infections; Pneumococcal conjugate vaccine; Pneumococcal vaccine; Polysaccharides; Prevalence; Resistance; Role; Sepsis; Serine Protease; Serotyping; Serum; Streptococcus pneumoniae; Structure; Testing; Tissues; Transferase; Vaccine Design; Variant; Work; base; capsule; design; ficolin-beta; improved; in vivo; inhibitor/antagonist; innovation; mannose-binding protein-associated serine proteases; mutant; pathogen; sugar; vaccin protein

DESCRIPTION (provided by applicant): Streptococcus pneumoniae is a Gram-positive bacterium that can express more than 90 different capsule types (serotypes) and is often carried as a commensal in the human nasopharynx (NPX), but can also cause serious diseases by invading deeper tissues. Epidemiologic studies show that the prevalence of carriage and the efficiency of invasion are highly variable (>100-fold) among different pneumococcal serotypes. With the use of pneumococcal conjugate vaccines, the most commonly carried serotypes have changed (called "serotype shift"), with serotype 11A having become one. However, serotype 11A has a very low invasiveness, and the molecular basis for 11A's low invasiveness and high rate of carriage is not known. By inactivating serotype 11A's wcjE and thus causing it to lose an acetyl group from its polysaccharide, we discovered that 11A often becomes 11E during the invasive pneumococcal infection of individual patients. We also found that 11A is more resistant to lysozyme than 11E is and that L-ficolin binds to 11A but not to 11E. L-ficolin is a recently discovered innate opsonin in the blood that resembles mannose binding lectin (MBL) in structure, targets acetyl groups, and initiates the lectin-dependent complement cascade by activating MBL- associated serine protease-2 (MASP-2). Based on these observations, we propose the overarching hypothesis that serotype 11A retains WcjE to resist lysozyme and thus survive in the NPX and that it loses WcjE function to become 11E and thus avoid L-ficolin and survive in the blood. To investigate this hypothesis, we will determine 1) whether L-ficolin is protective against serotype 11A but not against 11E isolates by testing L-ficolin's ability to opsonize serotype 11A but not 11E for phagocytosis, by measuring the serum levels of L-ficolin and MASP-2 in individuals with serotype 11A pneumococcal sepsis, and by testing another common wcjE+ serotype with L-ficolin reactivity for an undiscovered wcjE- subtype without L-ficolin reactivity; 2) whether the WcjE of serotype 11A makes pneumococci resistant to the murami- dase activity of lysozyme by comparing serotypes 11A and 11E isolates for their in vitro resistance to normal and mutant lysozymes and for their nasopharyngeal carriage in mice with or without lysozyme; and 3) whether WcjE enhances lysozyme resistance by helping Adr (attenuator of drug resistance) modify peptidoglycan. Our work is broadly relevant because wcjE is found in many different pneumococcal serotypes and because very little is known about L-ficolin's role in bacterial infections. Our work is also directly relevant to pneumococcal vaccin development because 11A has become one of the most common nasopharyngeal serotypes and because other newly emerging serotypes might be like 11A: they may interact with innate opsonins and thus be less of a health threat even if they become more common. Our work would also expand the concept of "serotype" to include serotype specific interactions with innate opsonins, as well as antibodies, and this new concept may bring further innovations in vaccine designs against many pathogens.

描述(申请人提供)：肺炎链球菌是一种革兰氏阳性细菌，可表达90多种不同的被膜类型(血清型)，通常在人类鼻咽(NPX)中作为共生体携带，但也可通过侵袭更深的组织而导致严重疾病。流行病学研究表明，不同肺炎球菌血清型之间的携带率和侵袭效率差异很大(&gt；100倍)。随着肺炎球菌结合疫苗的使用，最常见的携带的血清型发生了变化(称为“血清型转变”)，11A型已成为一种。然而，11A血清型的侵袭力很低，其低侵袭性和高携带率的分子基础尚不清楚。通过灭活血清11A的wcjE，从而使其多糖失去一个乙酰基，我们发现在个体患者的侵袭性肺炎球菌感染过程中，11A经常变成11E。我们还发现，11A比11E对溶菌酶的抗性更强，L-无花果能与11A结合，但不与11E结合。L-无花果蛋白是新近发现的一种天然调理蛋白，其结构类似于甘露糖结合凝集素，靶向乙酰基，通过激活甘露糖结合凝集素相关丝氨酸蛋白酶-2启动凝集素依赖的补体级联反应。基于这些观察，我们提出了最主要的假设，即11A型血清保留WcjE以抵抗溶菌酶，从而在NPx中存活，而它失去WcjE功能，变成11E，从而避开L-无花果而在血液中存活。为了研究这一假说，我们将确定1)L-菲科林是否对11A型而不是11E分离株有保护作用，方法是检测L-菲科林对11A型而不是11E型的吞噬能力，通过检测11A型肺炎球菌败血症患者血清中L-菲科林和MASP2的水平，以及通过检测另一种常见的与L-菲科林反应的WcjE+亚型对一种未发现的L-菲科林反应的WcjE-亚型；2)通过比较11A和11E血清型肺炎球菌对正常溶菌酶和突变溶菌酶的体外抗性以及它们在有或没有溶菌酶的小鼠的鼻咽携带情况，来确定11A血清型WcjE是否使肺炎球菌对溶菌酶的溶菌酶活性产生抗性；以及3)WcjE是否通过帮助ADR(耐药性减弱剂)修饰肽聚糖来增强溶菌酶的耐药性。我们的工作具有广泛的相关性，因为在许多不同的肺炎球菌血清型中都发现了wcjE，而且对L-菲科林在细菌感染中的作用知之甚少。我们的工作也与肺炎球菌疫苗的开发直接相关，因为11A已经成为最常见的鼻咽血清型之一，而且其他新出现的血清型可能类似于11A：它们可能与天生的调理蛋白相互作用，因此即使它们变得更加常见，对健康的威胁也较小。我们的工作还将扩大“血清型”的概念，以包括与天然调理素以及抗体的血清型特异性相互作用，这一新概念可能会在针对许多病原体的疫苗设计方面带来进一步的创新。

项目成果

Commercially available complement component-depleted sera are unexpectedly codepleted of ficolin-2.

市售的补体成分耗尽血清意外地同时去除了 ficolin-2。

• DOI: 10.1128/cvi.00370-14
• 发表时间: 2014
• 期刊: Clinical and vaccine immunology : CVI
• 作者: Brady,AllisonM;Geno,KAaron;Dalecki,AlexG;Cheng,Xiaogang;Nahm,MoonH
• 通讯作者: Nahm,MoonH