Mechanisms of Group B Streptococcal Pathogenesis in the Diabetic Wound

项目总结 B组链球菌(GBS)是一种无症状地定植于泌尿生殖道和 女性生殖道约占个体的25%-30%。然而，GBS会导致严重的感染 免疫功能受损的人，包括糖尿病患者。糖尿病伤口感染是一种主要的公共疾病 健康负担，大约25%的糖尿病患者在一生中会出现伤口，其中25% 伤口无法愈合，28%需要手术截肢。不良的感染结局与 存在许多细菌病原体，GBS和金黄色葡萄球菌是最常见的 在这些伤口中发现了常见的细菌。尽管GBS很流行，但之前还没有关于GBS的工作 糖尿病伤口环境中的发病机制。最近，我们建立了一种2型糖尿病小鼠模型。 GBS糖尿病创面感染Leprdb小鼠，并证明GBS形成了一个坚固的伤口并持续在 这种环境。进一步观察发现，从糖尿病伤口组织中恢复的GBS集落是 高度色素沉着/溶血，提示在糖尿病感染期间选择毒性更强的GBS突变体。 这些表型与COVR突变体的表型相似，因为COVR是GBS毒力因子的主要抑制因子，如 作为GBS的溶血素/色素、核酸酶(NUCA)和表面粘附素纤溶酶原结合蛋白PbsP。双人 对GBS和小鼠伤口的RNA测序表明，这些相同的COVR调控基因是高度 在糖尿病的伤口上表达上调。此外，GBS感染引发了中性粒细胞、中性粒细胞 在感染部位激活和网状形成。最后，我们已经在我们的小鼠模型中表明， 金黄色葡萄球菌的存在促进了糖尿病伤口中GBS的持续存在。根据这些初步数据，我们有 公式化的假设，解决了GBS生存和持续存在的多种机制 糖尿病创面环境。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，目标2：表征 PbsP在GBS糖尿病创面形成、持续和扩散中的作用，目标3：检查 核酸酶活性在促进GBS免疫逃避和伤口持久性中的作用。这些 研究将增加我们对GBS糖尿病伤口感染机制的理解，并将提供 为进一步研究提供平台。

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.