Bauman Susanne J, Kuehn Meta J
Department of Biochemistry, Duke University Medical Center, Duke University Medical Center, Durham, NC 27710, USA.
BMC Microbiol. 2009 Feb 3;9:26. doi: 10.1186/1471-2180-9-26.
Pseudomonas aeruginosa is the major pathogen associated with chronic and ultimately fatal lung infections in patients with cystic fibrosis (CF). To investigate how P. aeruginosa-derived vesicles may contribute to lung disease, we explored their ability to associate with human lung cells.
Purified vesicles associated with lung cells and were internalized in a time- and dose-dependent manner. Vesicles from a CF isolate exhibited a 3- to 4-fold greater association with lung cells than vesicles from the lab strain PAO1. Vesicle internalization was temperature-dependent and was inhibited by hypertonic sucrose and cyclodextrins. Surface-bound vesicles rarely colocalized with clathrin. Internalized vesicles colocalized with the endoplasmic reticulum (ER) marker, TRAPalpha, as well as with ER-localized pools of cholera toxin and transferrin. CF isolates of P. aeruginosa abundantly secrete PaAP (PA2939), an aminopeptidase that associates with the surface of vesicles. Vesicles from a PaAP knockout strain exhibited a 40% decrease in cell association. Likewise, vesicles from PAO1 overexpressing PaAP displayed a significant increase in cell association.
These data reveal that PaAP promotes the association of vesicles with lung cells. Taken together, these results suggest that P. aeruginosa vesicles can interact with and be internalized by lung epithelial cells and contribute to the inflammatory response during infection.
铜绿假单胞菌是与囊性纤维化（CF）患者慢性且最终致命的肺部感染相关的主要病原体。为了研究铜绿假单胞菌衍生的囊泡如何导致肺部疾病，我们探讨了它们与人类肺细胞结合的能力。
纯化的囊泡与肺细胞结合，并以时间和剂量依赖的方式被内化。来自CF分离株的囊泡与肺细胞的结合能力比实验室菌株PAO1的囊泡高3至4倍。囊泡内化是温度依赖性的，并受到高渗蔗糖和环糊精的抑制。表面结合的囊泡很少与网格蛋白共定位。内化的囊泡与内质网（ER）标记物TRAPα以及内质网定位的霍乱毒素和转铁蛋白池共定位。铜绿假单胞菌的CF分离株大量分泌PaAP（PA2939），一种与囊泡表面相关的氨肽酶。来自PaAP基因敲除菌株的囊泡与细胞的结合减少了40%。同样，过表达PaAP的PAO1菌株的囊泡与细胞的结合显著增加。
这些数据表明PaAP促进囊泡与肺细胞的结合。综上所述，这些结果表明铜绿假单胞菌囊泡可以与肺上皮细胞相互作用并被内化，并在感染期间促进炎症反应。
