Quorum sensing, diversity and skin inflammation

项目摘要 皮肤的表面持续地被细菌群落定殖，所述细菌群落包括许多不同的 凝固酶阴性葡萄球菌（CoNS）的种和菌株。有越来越多的证据表明 防止病原体如金黄色葡萄球菌（Staphylococcus aureus）在皮肤上定植，从而保护皮肤免受 损害我们的中心假设是皮肤上的CoNS使用肽群体感应系统来限制S。 金黄色葡萄球菌对宿主造成的伤害所有的葡萄球菌都有一个群体感应系统，也被称为 辅助基因调节子（agr）。agr系统响应于分泌的肽信号（自诱导肽或 AIP），并且该系统控制来自S.金黄色。在CoNS中， agr系统不太清楚，但我们最近的数据表明CoNS使用agr系统在皮肤上生存， 建立多样性，并与S竞争。金黄色。为了支持这一假设，我们发现， 常见的皮肤CoNS种类产生抑制S. aureus agr系统和限制皮肤损伤。 然而，这种假设的遗传基础的菌株特异性知识是必不可少的，因为不是所有的CoNS菌株 是有益的，有些会引发炎症。为了更好地理解这些机制及其意义 对于人类皮肤免疫防御，在目标1中，我们将研究CoNS AIP信号是否通过以下方式防止皮肤损伤： S.金黄色。为了实现这一目标，我们将从选定的皮肤CoNS的培养基中鉴定AIP结构 菌株，并测定其对S.金黄色葡萄球菌AGR抑制剂在体外和皮肤模型中的深部组织感染， 导致皮肤炎症的浅表定植。我们还将比较CoNS和S。金黄色多微生物 使用外植体和动物模型在皮肤上的相互作用，并评估CoNS agr功能对 抗菌肽的产生及与S.金黄色。在目标2中，我们提出， agr调节因子是影响皮肤病的主要机制。我们的初步研究表明， S.表皮EcpA蛋白酶促进表皮损伤和随后的炎症。 我们将研究S。表皮EcpA蛋白酶的表达和宿主靶点的切割，我们将 比较WT和突变菌株，以确定对皮肤屏障破坏和炎症的影响。我们还将 研究使用AIP抑制S. epidermidis EcpA生产。有害的定义 机制将使我们能够更好地了解有利于有益与有害CoNS生存的因素。 3、我们将确定CoNS如何利用agr调节因子在皮肤上存活。根据我们的初步研究 链球菌表皮，我们假设CoNS菌株定殖皮肤使用agr群体感应系统。 我们将评估各种agr调节位点对CoNS在皮肤上存活的需求，并评估其功能。 皮肤屏障进入的位点。我们还将使用RNAseq确定CoNS agr调节子，并研究 确定的目标。总的来说，拟议工作的结果将阐明 皮肤微生物组以促进健康和建立体内平衡。

Project Summary The surface of the skin is persistently colonized with a community of bacteria that includes numerous different species and strains of coagulase negative staphylococci (CoNS). There is mounting evidence that these CoNS prevent colonization of the skin by pathogens such Staphylococcus aureus, thereby protecting the skin from damage. Our central hypothesis is that CoNS on the skin use a peptide quorum-sensing system to limit S. aureus-induced damage to the host. All Staphylococci have a quorum-sensing system, which is also called the accessory gene regulator (agr). The agr system responds to a secreted peptide signal (autoinducing peptide or AIP), and this system controls expression of toxins and exo-enzymes from S. aureus. In CoNS, the function of the agr system is less clear, but our recent data suggest CoNS uses the agr system to survive on the skin, establish diversity, and compete against S. aureus. In support of this hypothesis, we have discovered that several common skin CoNS species produce AIP signals that inhibit the S. aureus agr system and limit skin damage. However, strain-specific knowledge of the genetic basis for this hypothesis is essential since not all CoNS strains are benefical and some can trigger inflammation. To better understand these mechanisms and their significance to human skin immune defense, in Aim 1 we will investigate whether CoNS AIP signals prevent skin damage by S. aureus. To carry out this aim, we will identify the AIP structures from culture media of selected skin CoNS strains, and test their activity as S. aureus agr inhibitors in vitro and in skin models of deep tissue infection and superficial colonization that drives skin inflammation. We will also compare CoNS and S. aureus polymicrobial interactions on the skin using explants and animal models, and assess the contribution of CoNS agr function to antimicrobial peptide production and mixed infection with S. aureus. In Aim 2, we propose that dysregulation of agr-regulated factors is a major mechanism that influences skin disease. Our preliminary studies indicate that high expression of the S. epidermidis EcpA protease promotes epidermal damage and subsequent inflammation. We will investigate S. epidermidis EcpA protease expression and the host target(s) of cleavage, and we will compare WT and mutant strains to define the impact on skin barrier disruption and inflammation. We will also investigate protective CoNS species that use AIPs to inhibit S. epidermidis EcpA production. Defining deleterious mechanisms will enable better understanding of factors favoring survival of beneficial vs harmful CoNS. In Aim 3, we will determine how CoNS use agr-regulated factors to survive on the skin. Based on our preliminary studies with S. epidermidis, we hypothesize that CoNS strains colonize the skin using the agr quorum-sensing system. We will assess the requirement of various agr-regulated loci for CoNS survival on skin and evaluate the function of identified loci for skin barrier entry. We will also determine the CoNS agr regulon using RNAseq and investigate identified targets. Collectively, the findings from the proposed work will elucidate the mechanisms used by the skin microbiome to promote health and establish homeostasis.