Quorum Sensing Dependent Interactions with Biofilms and Innate Immunity Defenses

金黄色葡萄球菌是一种条件致病菌，可引起多种急性和慢性疾病。 感染。抗生素耐药性是一个日益严峻的挑战，耐甲氧西林金黄色葡萄球菌(MRSA)感染 更难治疗，导致患者和医疗系统的负担增加。金黄色葡萄球菌引起 大多数皮肤感染发生在平民和军队中，但这种病原体如何在皮肤上定植尚不清楚。 在最近对皮肤外植体的显微镜研究中，金黄色葡萄球菌在皮肤定植过程中形成了生物膜群落， 这些生物膜被发现在农业群体感应系统的控制下产生毒力因子。在……里面 我们的初步研究发现，缺乏agr的MRSA菌株在皮肤外植体定植方面存在显著缺陷， 以及在啮齿动物皮肤定植模型中。我们的中心假设是MRSA的群体感知是必不可少的 用于皮肤定植和逃避宿主防御。此外，我们认为群体感知对 在从皮肤到全身感染的转变过程中起着重要作用。在具体目标1中，我们将确定法定人数的作用- 在MRSA皮肤定植过程中的感知。我们假设MRSA菌株使用agr调节因子来 在皮肤上定植。为了解决这一假设，我们将比较mrsa wt和∆agr突变株在 体外黏附模型，并在小鼠皮肤定植模型中进行比较。我们还将确定农业- 并确定已知的生物被膜因素是否重要。最后， 我们将进行RNAseq以获得对MRSA在皮肤上调节功能的更广泛的评估。以特定的目标 2，我们将确定群体感应对皮肤上MRSA免疫逃避的贡献。我们假设 耐甲氧西林金黄色葡萄球菌使用agr调节因子逃避皮肤免疫。为此，我们将确定 群体感应在抗菌肽诱导和耐药性中的作用及其评价 对皮肤不饱和脂肪酸的反应。我们还将确定MRSA尿素酶和其他AGR调节的 影响pH动态平衡的因素，我们将通过单细胞RNAseq来评估宿主皮肤的反应。在……里面 具体目标3，我们将评估群体感应在殖民传播中的作用。我们 假设MRSA群体感应是全身从皮肤传播所必需的。至 进一步研究这一机制，我们将确定对MRSA群体感应功能的需求，并 AGR调节因子在皮肤向远端扩散中的作用。我们还将对感染进行实时成像 并确定群体感应对逃避寄主免疫的贡献。更好地理解如何 耐甲氧西林金黄色葡萄球菌在皮肤上定植，向感染的过渡可能为开发治疗策略开辟道路 用于最大限度地减少皮肤感染负担。

Staphylococcus aureus is an opportunistic pathogen that causes a broad spectrum of acute and chronic infections. Antibiotic resistance is a growing challenge and methicillin-resistant S. aureus (MRSA) infections are more difficult to treat, resulting in increased burden for both patients and healthcare systems. S. aureus causes the majority of skin infections in civilians and the military, but how this pathogen colonizes the skin is unknown. In recent microscopy studies on skin explants, S. aureus developed biofilm communities during skin colonization, and these biofilms were found to produce virulence factors under control of the agr quorum-sensing system. In our preliminary studies, we found that MRSA strains lacking agr show striking defects in skin explant colonization, and in rodent skin colonization models. Our central hypothesis is that MRSA quorum-sensing is essential for skin colonization and evasion of host defenses. Additionally, we believe quorum-sensing plays a critical role in the transition from skin to systemic infection. In Specific Aim 1, we will determine the role of quorum- sensing during MRSA skin colonization. We hypothesize that MRSA strains use agr-regulated factors to colonize the skin. To address this hypothesis, we will compare MRSA WT and ∆agr mutant strains using in vitro models of adherence and compare them in a mouse skin colonization model. We will also identify agr- regulated factors required for colonization and determine whether known biofilm factors are important. Lastly, we will perform RNAseq to obtain a broader assessment of MRSA regulated functions on skin. In Specific Aim 2, we will determine the contribution of quorum-sensing to MRSA immune evasion on the skin. We hypothesize that MRSA evades skin immunity using agr-regulated factors. Toward this end, we will determine the role of quorum-sensing in the induction and resistance to antimicrobial peptides and assess the quorum-sensing response to skin unsaturated fatty acids. We will also determine whether MRSA urease and other agr-regulated factors contribute to pH homeostasis, and we will evaluate the host skin response by single-cell RNAseq. In Specific Aim 3, we will assess the function of quorum-sensing in dissemination from colonization. We hypothesize that the MRSA quorum-sensing is required for systemic dissemination from the skin. To further investigate this mechanism, we will determine the requirement for MRSA quorum-sensing function and agr-regulated factors in skin dissemination to distal sites. We will also perform real-time imaging of infections and determine the quorum-sensing contribution to evasion of host immunity. An improved understanding of how MRSA colonizes the skin and transitions to infection could open avenues to developing therapeutic strategies for minimizing the skin infection burden.