Role of T3SS in promoting Pseudomonas aeruginosa internalization in pulmonary epithelial cells via ERK/ROS signaling pathway
10.16016/j.2097-0927.202407056
- VernacularTitle:T3SS通过ERK/ROS信号通路促进铜绿假单胞菌侵袭肺上皮细胞的作用
- Author:
Junzhi XIONG
1
;
Hua YU
;
Xingmin WANG
;
Xiaomei HE
;
Qian DAI
;
Jing QIU
Author Information
1. 400037 重庆,陆军军医大学(第三军医大学)第二附属医院临床医学研究中心
- Keywords:
Pseudomonas aeruginosa;
type three secretion system;
ERK/ROS signaling pathway;
internalization of PA in pulmonary epithelial cells
- From:
Journal of Army Medical University
2024;46(22):2493-2504
- CountryChina
- Language:Chinese
-
Abstract:
Objective To explore the role and underlying mechanism of type Ⅲ secretion system(T3SS)in regulating the internalization of Pseudomonas aeruginosa(PA)into pulmonary epithelial cells.Methods The human non-small cell lung cancer A549 cells were infected with or without PA strains,including wild-type PAO1(a standard experimental PA strain),△exsA(knockout of the critical activator for T3SS genes),△pscJ(T3SS secretion-defective strain)and PAO1-E(EGTA-induced high expression of T3SS genes).The A549 cells pretreated with ERK inhibitor U0126 or reactive oxygen species(ROS)inhibitor apocynin(APO)/N-acetyl-L-cysteine(NAC)were infected with PAO1 or PAO1-E strain.Thus,the experiment was grouped as follows:the mock-treated group,PAO1-or PAO1-E-infected group,inhibitor-treated group,and PAO1/PAO1-E plus inhibitor-treated group.Extracellular bacteria were killed by gentamicin,and the cell lysates were diluted and then plated on PA screening plates.Bacterial amounts were detected by counting colony-forming units(CFUs).The production of ROS was analyzed using fluorescent probe labeling and flow cytometry.The activation of the ERK pathway was detected by Western blotting.Results Compared with the PAO1-infected group,the intracellular bacteria and ROS level in △exsA-or△pscJ-infected cells were lower(P＜0.05,P＜0.01),so was the generation of ROS(P＜0.01);In contrast,those of the PAO1-E strain-infected cells displayed an opposite trend(P＜0.01).Compared with the PAO1-or PAO1-E-infected group,the cells pretreated with APO/NAC followed by PAO1 or PAO1-E infection showed reduced intracellular bacterial amounts(P＜0.01).Compared to the PAO1-infected A549 cells,the phosphorylation level of ERK was increased in the △exsA-or △pscJ-infected cells(P＜0.01),while that level was suppressed in the PAO1-E-treated cells(P＜0.01).Compared with the PAO1-infected group,the PAO1-infected cells pretreated with U0126 displayed reduced ERK activation,elevated ROS production,and increased intracellular counts of PAO1(P＜0.01).Conclusion T3SS-mediated inhibition of the ERK pathway promotes the production of ROS and the internalization of PA in lung epithelial cells.
