ORIGINAL RESEARCH article

Front. Cell. Infect. Microbiol.

Sec. Bacteria and Host

Volume 15 - 2025 | doi: 10.3389/fcimb.2025.1582339

Transcriptomic Profiling Reveals RetS-Mediated Regulation of Type VI Secretion System and Host Cell Responses in Pseudomonas aeruginosa Infections

Provisionally accepted
Yinglin  WuYinglin Wu1,2Kai  ZhangKai Zhang3Yangcheng  ShenYangcheng Shen1,2Shebin  ZhangShebin Zhang1,2Shan  HuangShan Huang1,2Haining  XiaHaining Xia1,2Jieying  PuJieying Pu2Cong  ShenCong Shen2Cha  ChenCha Chen1,2*Jian  Ming ZengJian Ming Zeng1,2,4*
  • 1The Second Clinical Medical College, Guangzhou University of Chinese Medicine, State Key Laboratory of Traditional Chinese Medicine Syndrome, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
  • 2Department of Laboratory Medicine, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
  • 3School of Laboratory Medicine, Guangzhou Health Science College,, Guangzhou, China
  • 4Guangdong Provincial Key Laboratory of Research on Emergency in Traditional Chinese Medicine (TCM), Guangzhou, China

The final, formatted version of the article will be published soon.

Pseudomonas aeruginosa is a major opportunistic pathogen that causes chronic infections, particularly in patients with cystic fibrosis and chronic obstructive pulmonary disease (COPD). The type VI secretion system (T6SS) is a primary virulence factor of P. aeruginosa in chronic infections. The objective of this study was to elucidate the regulatory mechanisms and pathogenic effects of the T6SS during P. aeruginosa infection, utilizing transcriptome sequencing and functional assays. We found that T6SS expression is elevated in P. aeruginosa isolated from chronically infected patients. Deletion of the retS gene activates P. aeruginosa PAO1 T6SS while repressing T3SS in vitro. Bacterial and cellular transcriptome sequencing analyses showed that T6SS genes were upregulated, while T3SS genes were downregulated in the ΔretS mutant. Additionally, the expression levels of the fimbriae gene cupC, the histidine phosphotransfer protein hptC (PA0033), and the transcription factor PA0034 were significantly increased. Subsequent experiments revealed that adhesion mediated by cupC enhances the contact-killing activity of the T6SS. Deletion of the hptC-PA0034 operon results in the down-regulation of cupC expression. The ΔretSΔcupC and ΔretSΔhptC-PA0034 mutants exhibited reduced cytotoxicity compared to the ΔretS mutant, similar to the ΔretSΔclpV1ΔclpV2 mutant. The ΔretS infection increased cell death, inflammatory factors (IL-1β, IL-6, TNF-α), and reactive oxygen species compared to a T6SS-inactive strain. Importantly, our study demonstrates that the T6SS activates the PDE4C pathway in epithelial cells, leading to significant cellular alterations. The application of PDE inhibitors effectively mitigates cell damage and inflammatory responses. These findings highlight the critical role of T6SS in modulating host cell signaling and suggest potential therapeutic strategies for conditions associated with T6SS-mediated inflammation.

Keywords: Pseudomonas aeruginosa, Virulence, Type VI Secretion System, chaperone-usher pathway, CupC fimbriae, A549 epithelial cells, PDE4C

Received: 24 Feb 2025; Accepted: 21 May 2025.

Copyright: © 2025 Wu, Zhang, Shen, Zhang, Huang, Xia, Pu, Shen, Chen and Zeng. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Cha Chen, The Second Clinical Medical College, Guangzhou University of Chinese Medicine, State Key Laboratory of Traditional Chinese Medicine Syndrome, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
Jian Ming Zeng, The Second Clinical Medical College, Guangzhou University of Chinese Medicine, State Key Laboratory of Traditional Chinese Medicine Syndrome, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China

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