Department of Microbiology, Immunology, and Cell Biology, West Virginia University School of Medicine, Morgantown, WV, USA.
Vaccine Development Center, West Virginia University Health Sciences Center, Morgantown, WV, USA.
BMC Genomics. 2022 May 4;23(1):345. doi: 10.1186/s12864-022-08554-0.
Lung airway epithelial cells are part of innate immunity and the frontline of defense against bacterial infections. During infection, airway epithelial cells secrete proinflammatory mediators that participate in the recruitment of immune cells. Virulence factors expressed by bacterial pathogens can alter epithelial cell gene expression and modulate this response. Pseudomonas aeruginosa, a Gram-negative opportunistic pathogen, expresses numerous virulence factors to facilitate establishment of infection and evade the host immune response. This study focused on identifying the role of two major P. aeruginosa virulence factors, type III (T3SS) and type VI (T6SS) secretion systems, on the early transcriptome response of airway epithelial cells in vitro.
We performed RNA-seq analysis of the transcriptome response of type II pneumocytes during infection with P. aeruginosa in vitro. We observed that P. aeruginosa differentially upregulates immediate-early response genes and transcription factors that induce proinflammatory responses in type II pneumocytes. P. aeruginosa infection of type II pneumocytes was characterized by up-regulation of proinflammatory networks, including MAPK, TNF, and IL-17 signaling pathways. We also identified early response genes and proinflammatory signaling pathways whose expression change in response to infection with P. aeruginosa T3SS and T6SS mutants in type II pneumocytes. We determined that T3SS and T6SS modulate the expression of EGR1, FOS, and numerous genes that are involved in proinflammatory responses in epithelial cells during infection. T3SS and T6SS were associated with two distinct transcriptomic signatures related to the activation of transcription factors such as AP1, STAT1, and SP1, and the secretion of pro-inflammatory cytokines such as IL-6 and IL-8.
Taken together, transcriptomic analysis of epithelial cells indicates that the expression of immediate-early response genes quickly changes upon infection with P. aeruginosa and this response varies depending on bacterial viability and injectosomes. These data shed light on how P. aeruginosa modulates host epithelial transcriptome response during infection using T3SS and T6SS.
肺气道上皮细胞是先天免疫的一部分，是抵御细菌感染的第一道防线。在感染过程中，气道上皮细胞分泌促炎介质，参与免疫细胞的募集。细菌病原体表达的毒力因子可以改变上皮细胞的基因表达并调节这种反应。铜绿假单胞菌是一种革兰氏阴性机会性病原体，表达多种毒力因子，以促进感染的建立并逃避宿主免疫反应。本研究旨在确定两种主要的铜绿假单胞菌毒力因子，III 型（T3SS）和 VI 型（T6SS）分泌系统，对体外气道上皮细胞早期转录组反应的作用。
我们对体外感染铜绿假单胞菌时 II 型肺细胞的转录组反应进行了 RNA-seq 分析。我们观察到，铜绿假单胞菌在 II 型肺细胞中差异地上调了即刻早期反应基因和诱导 II 型肺细胞产生促炎反应的转录因子。II 型肺细胞感染铜绿假单胞菌的特征是促炎网络的上调，包括 MAPK、TNF 和 IL-17 信号通路。我们还鉴定了早期反应基因和促炎信号通路，其表达在 II 型肺细胞感染铜绿假单胞菌 T3SS 和 T6SS 突变体时发生变化。我们确定，T3SS 和 T6SS 调节 EGR1、FOS 和许多参与上皮细胞感染时促炎反应的基因的表达。T3SS 和 T6SS 与两个不同的转录组特征相关，与转录因子如 AP1、STAT1 和 SP1 的激活以及促炎细胞因子如 IL-6 和 IL-8 的分泌有关。
综上所述，上皮细胞的转录组分析表明，感染铜绿假单胞菌后，即刻早期反应基因的表达迅速发生变化，而这种反应因细菌活力和注入体而异。这些数据阐明了铜绿假单胞菌如何使用 T3SS 和 T6SS 来调节感染期间宿主上皮细胞转录组反应。
