Exploiting Host Polyamines for the Treatment of Skin and Wound Infections

描述（由申请方提供）：皮肤和软组织感染（SSTI）及其相关并发症是美国发病率和死亡率的重要来源，尤其是由多药耐药（MDR）病原体引起时。耐甲氧西林金黄色葡萄球菌（MRSA）是MDR相关SSTI的最常见来源。MRSA SSTI期间的宿主反应涉及两个一般阶段：早期，经典的炎症反应增强，包括浸润的白细胞产生NO*，试图对伤口进行消毒。随后，宿主进入与抗炎介质和生长促进信号相关的伤口消退和再生阶段，包括产生一类称为多胺的化合物（即腐胺，亚精胺和精胺）。NO* 和多胺都是由宿主精氨酸合成的，精氨酸的命运深刻地影响着S。金黄色葡萄球菌感染S.金黄色葡萄球菌对NO* 的细胞毒性作用具有独特的抗性，然而多胺对该病原体具有高毒性。事实上，考虑到正在消退的皮肤病变的高度增殖性，多胺在消退阶段变得足够丰富以直接杀死MRSA。唯一的例外是属于新兴社区相关MRSA USA 300克隆的分离株。这些菌株获得了精胺/亚精胺乙酰转移酶（SpeG），赋予宿主多胺的完全抗性，并有助于这些克隆的显着成功。在这里，我们建议开发新的抑制剂的细菌SpeG同源物，同时优化宿主多胺水平在受感染的皮肤脓肿。这种抗微生物/抗耐药性方法将允许治疗复杂的MRSA SSTI，无论它们是否由SpeG表达的USA 300菌株引起。有趣的是，我们发现消除多种伤口相关MDR病原体（如万古霉素耐药粪肠球菌、鲍曼不动杆菌和大肠杆菌）的SpeG活性。大肠杆菌）通常导致多胺敏感性。因此，这种方法可以扩展到治疗由许多MDR细菌引起的伤口感染。我们概述了我们的计划，以开发一种基于荧光的测定，以量化USA 300 SpeG活性，可以筛选与小分子库有针对性的定义结构-活性关系，以前确定的低亲和力SpeG抑制剂。我们的目标是找到安全有效的SpeG拮抗剂 局部应用于我们优化了多胺水平的皮肤病变。多胺优化可以通过直接局部施用精胺和/或亚精胺与FDA批准的限制多胺催化剂同时进行来实现。或者，我们提出了一系列的实验，测试免疫调节作为多胺优化的机制的可行性。在完成我们的目标后，我们将确定在SSTI期间优化组织多胺的最安全和最有效的机制，并将其与有效的抗SpeG化合物联合收割机结合，该化合物将使许多伤口相关病原体对升高的多胺敏感。我们将确定这是否是一个有效的治疗本身，或更好地服务于加强目前的治疗策略，鉴于多胺杀伤和传统抗生素之间的协同作用。最后，我们希望利用多胺的抗炎性质，同时利用其抗菌作用来改善由多种MDR病原体引起的SSTI的疾病结局。

DESCRIPTION (provided by applicant): Skin and soft tissue infections (SSTIs) and their associated complications represent a significant source of morbidity and mortality in the US, particularly when caused by multidrug-resistant (MDR) pathogens. The most common source of MDR associated SSTI is methicillin-resistant Staphylococcus aureus (MRSA). The host response during MRSA SSTIs involves two general phases: early on, a classical inflammatory response ensues including infiltrating leukocytes generating NO* in an attempt to sterilize the wound. Later, the host shifts into a wound-resolution and regenerative phase associated with anti-inflammatory mediators and growth promoting signals including the production of a class of compounds known as polyamines (i.e. putrescine, spermidine, and spermine). Both NO* and polyamines are synthesized from host arginine and the fate of arginine profoundly affects the outcomes of S. aureus infections. S. aureus is uniquely resistant to the cytotoxic effects of NO*, however polyamines are highly toxic to this pathogen. In fact, given the highly proliferative nature of a resolving skin lesion, polyamines become abundant enough during the resolution phase to directly kill MRSA. The only exceptions are isolates belonging to the emerging community-associated MRSA USA300 clones. These strains acquired a spermine/spermidine acetyltransferase (SpeG) that confers complete resistance to host polyamines and contributes to the remarkable success of these clones. Here we propose to develop novel inhibitors of bacterial SpeG-homologues and simultaneously optimize host polyamine levels in infected skin abscesses. This antimicrobial/anti-resistance approach would allow for the treatment of complicated MRSA SSTIs regardless of whether they are caused by SpeG-expressing USA300 strains. Interestingly, we found that eliminating SpeG-activity from a variety of wound-related MDR pathogens (e.g. Vancomycin-resistant Enterococcus faecalis, Acinetobacter baumannii, and E. coli) generally leads to polyamine sensitivity. Thus, this approach can be extended to treat wound infections caused by a many MDR bacteria. We outline our plan to develop a fluorescence-based assay to quantify USA300 SpeG activity that can be screened with a small molecule library targeted to define structure-activity relationships to previously identified low-affinity SpeG-inhibitors. Our goal is to find effective SpeG antagonists that can be safely applied topically to skin lesions in which we have optimized polyamine levels. Polyamine optimization can be accomplished by direct topical administration of spermine and/or spermidine simultaneously with FDA-approved agents that limit polyamine catabolism. Alternatively, we propose a series of experiments that test the feasibility of immunomodulation as a mechanism of polyamine optimization. Upon completing our aims, we will determine the safest and most effective mechanism of optimizing tissue polyamines during an SSTI and combine this with potent anti-SpeG compounds that will render a number of wound-related pathogens susceptible to elevated polyamines. We will ascertain whether this is an effective treatment on its own, or better serves to augment current treatment strategies given the documented synergy between polyamine- killing and traditional antibiotics. In the end, we hope to harness the anti-inflammatory nature of polyamines and at the same time exploit their antibacterial effects to improve disease outcomes of SSTIs caused by a variety of MDR pathogens.