支气管上皮细胞来源外泌体介导let-7b对铜绿假单胞菌生物膜抑制作用的机制研究

铜绿假单胞菌感染显著增加支气管扩张症患者的住院风险及死亡风险，而生物膜的形成促进感染的持续存在和耐药的发生。外泌体介导microRNA let-7b在不同细胞间传递，抑制病原体的生命活动，但机制未明。我们的前期研究发现40.7%的支气管扩张症患者存在铜绿假单胞菌慢性定植，并且发现其痰液及支气管肺泡灌洗液富集的外泌体中let-7b的表达显著低于其他患者。由此我们提出假设支气管扩张症患者存在let-7b表达缺陷，let-7b可能通过调控胞外多糖pel、psl及藻酸盐等基因的表达来抑制铜绿假单胞菌生物膜的形成。本研究拟构建let-7b过表达外泌体与铜绿假单胞菌共培养模型，验证let-7b对生物膜的抑制作用，进一步探索let-7b对rhlIR、lasIR、pslA、pelA及algD等相关基因和蛋白的表达，深入揭示let-7b抑制生物膜形成的机制，为铜绿假单胞菌生物膜的靶向治疗提供临床思路。

Pseudomonas aeruginosa significantly increases the risk of hospitalization and death in bronchiectasis patients. Due to the formation of biofilm, infection of Pseudomonas aeruginosa persists and drug resistance develops. Exosomes mediate the transmission of microRNA let-7b between different cells and play an important role in inhibiting the life activities of pathogens, but the mechanism is unknown. Our previous studies found that 40.7% of bronchiectasis patients suffered from chronic colonization of Pseudomonas aeruginosa. We also found that the expression of let-7b in exosomes isolated from sputum and bronchoalveolar lavage fluid of bronchiectasis patients were lower than other patients. We hypothesize that the expression of let-7b is defective in bronchiectasis patients and that let-7b inhibits the formation of the biofilm of Pseudomonas aeruginosa by regulating the impression of genes and proteins of biofilm extracellular polysaccharides (such as pel, psl or alginate). This study intends to construct a co-culture model of exosomes derived from let-7b mimic and inhibitor transfected bronchial epithelial cells and Pseudomonas aeruginosa; to determine the genes related to biofilm of Pseudomonas aeruginosa (rhlIR, lasIR, pslA, pelA or algD) that are affected by let-7b; and to detect the metabonomic of Pseudomonas aeruginosa. We aim to reveal the molecular mechanism of let-7b inhibiting biofilm formation, and provide clinical ideas for targeted therapy of Pseudomonas aeruginosa biofilm.