【摘要】 目的探讨肺表面活性蛋白A(SP-A)与铜绿假单胞菌(P.aeruginosa)弹性蛋白酶在铜绿假单胞菌肺部感染过程中的关系。方法铜绿假单胞菌突变菌株P.aeruginosa野毒株PAO1、弹性蛋白酶LasB突变株△lasB和回复突变株PDO240LasB鼻腔接种C3H小鼠建立肺部感染模型以观察细菌的毒力变化。将同等数量的细菌与SP-A共同孵育,通过Western blot法检测SP-A的体外降解。将预先经SP-A作用过的细菌与小鼠Raw264.7巨噬细胞孵育进行体外吞噬实验以观察细菌被吞噬的情况。结果由于弹性蛋白酶表达的缺失,铜绿假单胞菌突变菌株P.aeruginosa△lasB在通过鼻腔接种C3H小鼠建立的肺部感染模型中,与野毒株PAO1相比毒力显著降低。体外SP-A降解实验显示,△lasB基本失去了降解SP-A的能力。进一步的体外吞噬实验和聚集实验表明,△lasB在SP-A作用下更容易聚集成簇并被鼠巨噬细胞Raw264.7吞噬。结论铜绿假单胞菌弹性蛋白酶可降解SP-A,破坏SP-A介导的细菌聚集作用。更多还原

【Abstract】 Objective To investigate the relationship between Pseudomonas aeruginosa(P.aeruginosa) elastase and pulmonary surfactant protein A(SP-A) in host infected by P. aeruginosa. Methods C3 H mice were intranasally infected with P. aeruginosa wild-type PAO1,△lasB mutant and genetic complement strain PDO240 LasB to determine the difference of virulence between wide type and mutant. The ability to degrade SP-A in vitro by PAO1,△lasB and PDO240 LasB was observed through co-incubation of equal bacteria and SP-A and detected by Western blotting. The susceptibility of bacteria to phagocytosis was assayed by in vitro experiment that bacteria treated with SP-A was incubated with mouse Raw264. 7macrophages. Results Compared with wide-type PAO1,the virulence of △lasB mutant was attenuated in the mouse model of P. aeruginosa infection because of the knock down of elastase expression. The △lasB mutant lost the ability to degrade SP-A when incubated with SP-A in vitro. The in vitro phagocytosis experiments showed that SP-A augmented the phagocytosis of △lasB mutant bacteria more efficiently than the wild-type PAO1. Conclusion P. aeruginosa elastase provides a protection from phagocytic cells by degrading SP-A.更多还原