Viral-bacterial co-infections in the lung

 描述（由申请方提供）：铜绿假单胞菌是囊性纤维化（CF）发病机制中的主要呼吸道病原体，对该病原体的无效免疫应答被认为是导致该疾病特征性肺损伤的主要原因。在CF的后期阶段，铜绿假单胞菌驻留在肺中的生物膜群落中，这是它们对抗生素治疗的抗性的原因。迄今为止，很少有人知道宿主因素，促进铜绿假单胞菌从急性到慢性感染CF的转变。据报道，CF患者显示出清除呼吸道病毒感染期间获得的铜绿假单胞菌的能力降低，并且在呼吸道病毒感染后3周内，CF患者中85%的新假单胞菌定殖。我们已经证明，病毒合并感染，以及随后的抗病毒III型干扰素反应，促进铜绿假单胞菌的生物膜转化。III型干扰素具有有效的抗病毒活性，但此外，据报道干扰素刺激基因（ISG）效应子功能可促进病原体复制，表明病原体已进化为破坏甚至受益于干扰素应答。微生物相互作用的一个基本方面是对营养物质的无情争夺，包括铁， 限制接触病原体的每一种努力，病原体已经发展出复杂的策略，以从宿主获得它们生长所需的营养。使用独特的模型培养与人CF气道上皮细胞相关的铜绿假单胞菌生物膜，我们将检查宿主对病毒感染的反应，即III型干扰素信号传导，是否通过不适当的铁分泌机制促进铜绿假单胞菌的生物膜转化。为此，我们将（1）确定呼吸道上皮细胞中因病毒感染和III型干扰素信号传导而改变的铁调节途径，（2）确定铁被动员到呼吸道表面液体中的机制以及铜绿假单胞菌如何获得宿主铁，以及（3）确定ISG，viperin/RSAD 2，促进气道上皮细胞分泌铁以增强细菌生物膜生长。拟议的实验将提供病毒共感染和慢性细菌定植建立之间的新联系， 在CF肺病的进展中具有重要意义。我们的目标是阐明病毒刺激的细菌生物膜的分子机制，从而确定可以延迟获得和慢性细菌定植的新靶点，或与现有疗法结合使用，以根除CF患者中的铜绿假单胞菌。

 DESCRIPTION (provided by applicant): Pseudomonas aeruginosa is the major respiratory pathogen in the pathogenesis of Cystic Fibrosis (CF) and the ineffective immune response to this pathogen is thought to cause the majority of the lung damage characteristic of this disease. In the later stages of CF, P. aeruginosa reside in biofilm communities in the lung, accounting for their resistance to antibiotic therapies. To date, little is known about host factors that promote the transition of P. aeruginosa from acute to chronic infection in CF. It has been reported that CF patients show a reduced ability to clear P. aeruginosa acquired during respiratory viral infections and 85% of new pseudomonal colonization in CF patients followed a respiratory viral infection within 3 weeks. We have demonstrated that virus co-infection, and the subsequent antiviral type III interferon response, promote biofilm conversion by P. aeruginosa. Type III interferon has potent antiviral activity, but in addition, interferon stimulated gene (ISG) effecto functions have been reported to promote pathogen replication, suggesting that pathogens have evolved to subvert and even benefit from the interferon response. A fundamental aspect in microbial interactions is the relentless battle for nutrients, including iron, where the host makes every effort to restrict access to pathogens and the pathogens have developed sophisticated strategies to acquire the nutrients they require for growth from the host. Using a unique model to culture P. aeruginosa biofilms in association with human CF airway epithelial cells, we will examine whether the host response to viral infection, namely type III interferon signaling, promotes biofilm conversion by P. aeruginosa through a mechanism of inappropriate iron secretion. To this end, we will (1) define the iron regulatory pathways that are altered by virus infection and type III interferon signaling in the airway epithelium, (2) define the mechanism by which iron is mobilized into the airway surface liquid and how P. aeruginosa acquires host iron and (3) define a role for the ISG, viperin/RSAD2, in promoting iron secretion from airway epithelial cells to enhance bacterial biofilm growth. The proposed experiments would provide a novel link between viral co-infection and the establishment of chronic bacterial colonization, with important implications in the progression of CF lung disease. Our goal is to elucidate the molecular mechanism for virus-stimulated bacterial biofilms and thus, identify new targets that could delay acquisition and chronic bacterial colonization, or work in conjunction with existing therapies, to eradicate P. aeruginosa in CF patients.