Determinants of polymicrobial diabetic wound infections

项目摘要 B族链球菌（GBS）是一种机会致病菌，其无症状地定殖于泌尿生殖道， 女性生殖道约占25-30%。然而，GBS可导致严重的感染 免疫功能低下的个体，包括糖尿病患者。糖尿病伤口感染是一个主要的公众 健康负担，大约25%的糖尿病患者在其一生中会出现伤口，其中25% 伤口不愈合，28%需要手术截肢。不良感染结果与 许多细菌病原体的存在，GBS，沿着金黄色葡萄球菌，是最常见的病原体之一。 这些伤口中常见的细菌尽管它的流行，没有先前的工作已经做了GBS 糖尿病伤口环境中的发病机制。最近，我们开发了一种2型糖尿病小鼠模型， GBS糖尿病伤口感染leprdb小鼠，并证明GBS形成一个强大的伤口，并持续存在， 这种环境。进一步的观察发现，从糖尿病伤口组织中回收的GBS集落是 色素沉着过度/溶血，表明在糖尿病感染期间选择了毒性更强的GBS突变体。 这些表型模拟covR突变体的表型，因为CovR是GBS毒力因子的主要阻遏物， 如GBS溶血素/色素、核酸酶（NucA）和表面粘附素纤溶酶原结合蛋白PbsP。双 GBS和小鼠伤口的RNA测序显示，这些相同的CovR调节基因在GBS和小鼠伤口中高度表达。 在糖尿病伤口中上调。此外，GBS感染触发了中性粒细胞的募集， 在感染部位的活化和NET形成。最后，我们在小鼠模型中表明， S的存在。金黄色葡萄球菌促进GBS在糖尿病伤口中的持久性。根据这些初步数据，我们有 制定的假设，解决多种机制，其中GBS可能生存和坚持在 糖尿病伤口环境。这些假设将在以下具体目标中得到解决：目标1： 确定CovR调节如何促进糖尿病伤口感染，目的2：表征 PbsP对GBS糖尿病伤口形成、持久性和播散的贡献，目的3：检查 核酸酶活性在促进GBS免疫逃避和创伤持久性中的作用。这些 这些研究将增加我们对GBS糖尿病伤口感染发病机制的了解， 平台进行更多的研究。

PROJECT SUMMARY Group B Streptococcus (GBS), is an opportunistic pathogen that asymptomatically colonizes the urogenital and female reproductive tract of approximately 25-30% of individuals. However, GBS can cause serious infections in immunocompromised individuals including those with diabetes. Diabetic wound infections are a major public health burden, with approximately 25% of diabetic individuals developing a wound in their lifetime, 25% of these wounds not healing and 28% requiring surgical amputation. Poor infection outcomes are correlated with the presence of numerous bacterial pathogens, and GBS, along with Staphylococcus aureus, is one of the most common bacteria found in these wounds. Despite its prevalence, no prior work has been done on GBS pathogenesis in the diabetic wound environment. Recently, we developed a Type 2 diabetic murine model of GBS diabetic wound infection in leprdb mice, and demonstrated that GBS forms a robust wound and persists in this environment. Further observations found that GBS colonies recovered from diabetic wound tissue were hyper-pigmented/hemolytic, suggesting selection of more virulent GBS mutants during diabetic infection. These phenotypes mimic those of a covR mutant, as CovR is a major repressor of GBS virulence factors such as the GBS hemolysin/pigment, nuclease (NucA), and surface adhesin plasminogen binding protein PbsP. Dual RNA-sequencing of GBS and the murine wound revealed that these same CovR regulated genes were highly upregulated in the diabetic wound. In addition, GBS infection triggered the recruitment of neutrophils, neutrophil activation and NET formation at the site of infection. Finally, we have shown in our murine model that the presence of S. aureus promotes GBS persistence in the diabetic wound. With these preliminary data, we have formulated hypotheses which address multiple mechanisms by which GBS may survive and persist in the diabetic wound environment. These hypotheses will be addressed in the following specific aims: Aim 1: Determine how CovR regulation contributes to diabetic wound infection, Aim 2: Characterize the contribution of PbsP to GBS diabetic wound formation, persistence, and dissemination, Aim 3: Examine the contribution of nuclease activity in promoting GBS immune evasion and wound persistence. These studies will increase our understanding of the pathogenesis of GBS diabetic wound infection and will provide a platform for additional studies.