Mechanisms of skin commensal colonization resistance against opportunistic Staphylococci

项目摘要 最近的研究强调了在大肠杆菌中存在大量的凝固酶阴性葡萄球菌（CoNS）。 健康的皮肤有证据表明，CoNS积极塑造皮肤免疫和微生物环境， 在多种疾病中，包括金黄色葡萄球菌在内的机会性病原体的定植或感染， 这些机制统称为殖民抵抗。最常见的孤立和最好的特点 来自人类皮肤的CoNS是表皮葡萄球菌。鉴于其在皮肤上的相对丰度， 这并不奇怪，S。epidermidis历来用于假定代表所有 弊然而，对定植抗性的研究值得对其他皮肤CoNS进行更广泛的解剖， 特别是考虑到S。表皮葡萄球菌是一种机会致病菌，也是导致医疗植入的主要原因， 相关感染。特别令人感兴趣的是第二个最常见的分离CoNS，葡萄球菌 人类虽然与S相比相对未被研究。epidermidis，目前的证据表明，S.人类可能 在维持皮肤内稳态和定植方面， 阻力S.人型链球菌产生多种抗病原体羊毛硫抗生素，我们的初步研究结果表明S. 人型沙门氏菌不含有与沙门氏菌相同的致病基因。表皮细胞可以用来降解皮肤屏障。 该提案旨在填补我们对特定CoNS的多方面作用的理解中的一个重大空白， 通过确定S.人皮肤定植抗性。 一种潜在的定植抗性机制是辅助基因调节子（agr）群体 传感系统，这是普遍存在的葡萄球菌。这两个组成部分的系统响应其同源 自诱导肽（AIP）信号。in s. agr调控一系列毒力因子的表达 生产性皮肤感染所必需的。一些，但不是所有的CoNS使AIP抑制S。aureus agr and 重要的是，不是所有的S。epidermidis AIPs抑制S.金黄色葡萄球菌agr信号提示其他CoNS也可能 有助于串扰和集群抗性。我们的合作者表明，S。人类至少 一种抗S.金黄色葡萄球菌群体感应通过对健康皮肤S.人型 菌株，我确定S.人型链球菌产生至少六种AIP变体，金黄色葡萄球菌和 表皮细胞聚集感应。根据这些初步数据和临床观察，我假设S。 人及其agr调节因子保护宿主皮肤免受机会性葡萄球菌攻击 病原体为了解决这个假设，我提出了两个创新的具体目标：（1）表征每个S。 人类AIP类型和在种间和种内串扰中的功能，以及（2）确定S.人型 定殖和agr调节因子刺激人皮肤上的保护性抗病原体环境。 总之，这一建议将是第一个提供机械洞察殖民抵抗 一个普遍存在的机制，但研究不足的成员正常人类植物群与潜在的应用， 一种新的益生菌或皮肤病治疗剂。

PROJECT SUMMARY Recent studies highlight the abundance of commensal coagulase-negative staphylococci (CoNS) on healthy skin. Evidence suggests that CoNS actively shape the skin immunological and microbial milieu to resist colonization or infection by opportunistic pathogens, including Staphylococcus aureus, in a variety of mechanisms collectively termed colonization resistance. The most frequently isolated and best characterized CoNS from human skin is Staphylococcus epidermidis. Given its relative abundance on the skin, it is unsurprising that S. epidermidis has historically been used for studies assumed to be representative of all CoNS. However, investigation of colonization resistance merits a wider dissection of other skin CoNS, especially given that S. epidermidis is an opportunistic pathogen and the leading cause of medical implant- associated infections. Of particular interest is the second most frequently isolated CoNS, Staphylococcus hominis. While relatively unstudied compared to S. epidermidis, current evidence suggests that S. hominis may be an underappreciated yet important player in maintaining cutaneous homeostasis and colonization resistance. S. hominis makes multiple anti-pathogen lantibiotics and our preliminary findings suggest S. hominis does not contain the same pathogenic genes that S. epidermidis can use to degrade the skin barrier. This proposal seeks to fill a significant gap in in our understanding of the multifaceted roles of specific CoNS in maintaining skin health by determining mechanisms of S. hominis skin colonization resistance. One potential colonization resistance mechanism is the Accessory Gene Regulator (agr) quorum sensing system, which is ubiquitous among staphylococci. This two component system responds to its cognate auto-inducing peptide (AIP) signal. In S. aureus, agr regulates the expression of a suite of virulence factors necessary for productive skin infection. Some, but not all CoNS make AIPs that inhibit S. aureus agr and importantly, not all S. epidermidis AIPs inhibit S. aureus agr signaling suggesting that other CoNS may also contribute to crosstalk and colonization resistance. Our collaborators showed that S. hominis makes at least one AIP inhibitor of S. aureus quorum sensing. Through analysis of spent media from healthy skin S. hominis strains, I determined that S. hominis makes at least six AIP variants that inhibit both S. aureus and S. epidermidis agr quorum sensing. With these preliminary data and clinical observations, I hypothesize that S. hominis and its agr-regulated factors protect host skin from challenge by opportunistic staphylococcal pathogens. To address this hypothesis, I propose two innovative specific aims to (1) characterize each S. hominis AIP type and function in inter- and intraspecies crosstalk, and (2) determine how S. hominis colonization and agr-regulated factors stimulate a protective anti-pathogen environment on human skin. Together, this proposal will be the first to provide mechanistic insight into the colonization resistance mechanisms of a ubiquitous, yet understudied member of the normal human flora with potential applications as a novel probiotic or therapeutic for skin diseases.