Salmonella chronic infection: Biofilm matrix factors and innate immune tolerance

项目总结 沙门氏菌是一种肠杆菌科细菌，可引起人类和动物的一系列疾病，包括肠道疾病 (伤寒)发烧和胃肠炎。伤寒主要由伤寒沙门氏菌(S. 伤寒)，导致一种危及生命的系统性疾病，每年都会导致严重的发病率和 全球范围内的死亡率。大约5%的伤寒沙门氏菌感染者成为慢性伤寒病毒携带者 以胆(GB)为主要存留部位。伤寒沙门氏菌是一种人类限制的病原体，因此 无症状携带者是疾病进一步传播的关键宿主。我们已经证明了 胆结石(GSS)有助于在小鼠模型中发展和维持GB带(利用S。 在小鼠中引起伤寒样疾病的鼠伤寒杆菌)和在人类中作为其底物的 沙门氏菌附着并形成保护性生物膜。因此，生物膜的形成是建立 承运人。众所周知，生物膜中的沙门氏菌对抗生素和宿主免疫具有抵抗力，这对沙门氏菌构成了挑战。 对于传统的治疗方法。慢性伤寒沙门氏菌感染的一个特征是产生细胞外聚合物 GSS上生物膜形成所必需的物质(EPSS)。细菌如何颠覆先天免疫 在生物被膜发育的早期阶段，并建立慢性感染尚不清楚。可能的免疫逃逸 涉及EPS，但对负责这一功能的EPS的完全了解尚不清楚。我们假设 一个或多个EPS在生物膜的发育中起关键作用，并有助于伤寒沙门氏菌的慢性致病 生物膜通过先天免疫逃避。确定基本的每股收益(S)将使我们能够确定其机制 免疫逃避，可能是由于身体屏障功能和调节先天宿主反应的组合。 为了建立在我们的临产前数据基础上，我们将进一步调查哪些EPS对这种扰动负责，并 进行定量检测以评估天然吞噬细胞对WT和EPS突变生物膜的反应。 可溶性因子(如抗菌肽、补体)和中性粒细胞(中性粒细胞)的检测 功能(趋化性、中性粒细胞外捕获和诱导呼吸爆发)已经或将会是 指挥。来自体外和体内GSS的EPS的共聚焦成像将确定每个GSS的结构贡献 EPS在慢性感染中的作用，并将与免疫调节的功能分析相关联。总体而言， 了解生物膜在体内如何发展，以及EPSS如何扭曲先天免疫将是发育的关键 新的治疗和预防方法。携带者状态感染的中断将对 地方性伤寒沙门氏菌的持续和伤寒的传播。

PROJECT SUMMARY Salmonellae are Enterobacteriaceae that cause a spectrum of diseases in humans and animals, including enteric (typhoid) fever and gastroenteritis. Typhoid fever, caused primarily by Salmonella enterica serovar Typhi (S. Typhi), results in a life-threatening systemic disease that is annually responsible for significant morbidity and mortality worldwide. Approximately 5% of individuals infected with S. Typhi become chronic carriers with the gallbladder (GB) as the primary site of persistence. S. Typhi is a human-restricted pathogen, therefore asymptomatic carriers represent a critical reservoir for further spread of disease. We have demonstrated that gallstones (GSs) aid in the development and maintenance of GB carriage in a mouse model (utilizing S. Typhimurium, which causes a typhoid fever-like disease in mice) and in humans, serving as a substrate to which salmonellae attach and form a protective biofilm. Thus, biofilm formation is a key step in the establishment of carriers. Salmonella in biofilms are known to be recalcitrant to antibiotics and host immunity, presenting a challenge for traditional treatment methods. A hallmark of chronic S. Typhi infections is the production of extracellular polymeric substances (EPSs) which are integral to biofilm development on GSs. How the bacteria subvert innate immunity during early stages of biofilm development and establish chronic infections is not known. Immune escape likely involves EPS, but a complete understanding of the EPSs responsible for this function is not known. We hypothesize one or more EPS has a critical role in biofilm development and contributes to the chronic pathogenicity of S. Typhi biofilms via innate immune evasion. Identification of the essential EPS(s) will allow us to determine the mechanism of immune evasion, likely due to a combination of a physical barrier function and regulation of innate host responses. To build on our prelinminary data, we will further investigate which EPSs are responsible for this perturbation and conduct quantitative assays to evaluate innate phagocyte activity in response to WT and EPS mutant biofilms. Assays for soluable factors (e.g. antimicrobial peptides, complement) and polymorphonuclear cell (neutrophil) functions (chemotaxis, neutrophil extracellular trapping, and induction of respiratory burst) have been or will be conducted. Confocal imaging of EPSs from in vitro and in vivo GSs will determine the structural contribution of each EPS during chronic infection and will be correlated to functional assays of immune modulation. Overall, an improved understanding of how biofilms develop in vivo and how EPSs skew innate immunity will be critical for development of new treatment and prevention methods. Disruption of carrier state infections will have a significant impact on endemic S. Typhi persistence and the spread of typhoid fever.