Quorum sensing, diversity and skin inflammation

项目摘要 皮肤表面长期寄生着细菌群落，其中包括许多不同的 凝固酶阴性葡萄球菌(CONS)的种类和菌株有越来越多的证据表明这些骗局 防止金黄色葡萄球菌等病原体侵袭皮肤，从而保护皮肤免受 损坏。我们的中心假设是皮肤上的cons使用多肽群体感应系统来限制S。 金黄色葡萄球菌对寄主的伤害。所有葡萄球菌都有一个群体感应系统，也被称为 辅助基因调节因子(AGR)。AGR系统对分泌肽信号(自动诱导肽或 AIP)，该系统控制金黄色葡萄球菌毒素和外源酶的表达。在缺点中，功能 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，并与金黄色葡萄球菌竞争。为了支持这一假设，我们发现有几个 常见的皮肤疾病物种会产生AIP信号，抑制金黄色葡萄球菌的AGR系统，限制皮肤损害。 然而，对这一假设的遗传基础的特定菌株的知识是必不可少的，因为并不是所有的cons菌株 是有益的，有些还会引发炎症。为了更好地理解这些机制及其意义 对于人类皮肤的免疫防御，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 金黄色葡萄球菌。为了实现这一目标，我们将从选定的皮肤癌细胞的培养液中鉴定AIP结构 菌株，并在体外和深部组织感染皮肤模型中测试它们作为金黄色葡萄球菌agr抑制剂的活性。 导致皮肤发炎的浅表定植。我们还将比较CONS和金黄色葡萄球菌多菌 使用外植体和动物模型在皮肤上相互作用，并评估cons agr功能对 抗菌肽的产生与金黄色葡萄球菌混合感染。在目标2中，我们提出了调控失调 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 表皮葡萄球菌ECPA蛋白的高表达促进了表皮损伤和随后的炎症。 我们将研究表皮葡萄球菌ECPA蛋白酶的表达和切割的宿主靶标(S)，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 调查使用AIPs抑制表皮葡萄球菌ECPA产生的保护性假单胞菌。有害物质的定义 机制将使人们能够更好地理解有利于有利与有害的因素生存的因素。在AIM 3，我们将确定CONS如何使用农业调节因子在皮肤上生存。根据我们的初步研究 对于表皮葡萄球菌，我们假设cons菌株使用agr群体感应系统在皮肤上定植。 我们将评估各种agr调节基因对CONS在皮肤上存活的需求，并评估其功能。 已识别的皮肤屏障进入的基因座。我们还将使用RNAseq确定CONS AGR调节子并调查 确定了目标。总的来说，拟议工作的结果将阐明 皮肤微生物群，促进健康，建立动态平衡。

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.