Published June 2024 | Published
Journal Article Open

Pseudomonas aeruginosa Activates Quorum Sensing, Antioxidant Enzymes and Type VI Secretion in Response to Oxidative Stress to Initiate Biofilm Formation and Wound Chronicity

Abstract

Pseudomonas aeruginosa (PA) is an opportunistic pathogen frequently isolated from cutaneous chronic wounds. How PA, in the presence of oxidative stress (OS), colonizes chronic wounds and forms a biofilm is still unknown. The purpose of this study is to investigate the changes in gene expression seen when PA is challenged with the high levels of OS present in chronic wounds. We used a biofilm-forming PA strain isolated from the chronic wounds of our murine model (RPA) and performed a qPCR to obtain gene expression patterns as RPA developed a biofilm in vitro in the presence of high levels of OS, and then compared the findings in vivo, in our mouse model of chronic wounds. We found that the planktonic bacteria under OS conditions overexpressed quorum sensing genes that are important for the bacteria to communicate with each other, antioxidant stress genes important to reduce OS in the microenvironment for survival, biofilm formation genes and virulence genes. Additionally, we performed RNAseq in vivo and identified the activation of novel genes/pathways of the Type VI Secretion System (T6SS) involved in RPA pathogenicity. In conclusion, RPA appears to survive the high OS microenvironment in chronic wounds and colonizes these wounds by turning on virulence, biofilm-forming and survival genes. These findings reveal pathways that may be promising targets for new therapies aimed at disrupting PA-containing biofilms immediately after debridement to facilitate the treatment of chronic human wounds.

Copyright and License

© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Funding

This research was funded by the NIH 1 R21 AI156688-01, NIH/NIAU19AG023122. ZRL was supported by a fellowship from the Jane Coffin Childs Memorial Fund for Medical Research.

Contributions

Conceptualization, J.H.K. and M.M.-G.; Methodology, J.H.K., B.H.L., W.Z., W.G., and M.M.-G.; Software, B.H.L. and Z.R.L.; Validation, J.H.K. and B.H.L.; Formal analysis, J.H.K.; Resources, W.Z.; Data curation, J.H.K. and J.D.; Writing—original draft, J.H.K.; Writing—review & editing, J.H.K. and M.M.-G.; Supervision, M.M.-G.; Funding acquisition, T.G., D.K.N. and M.M.-G. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the NIH 1 R21 AI156688-01, NIH/NIAU19AG023122. ZRL was supported by a fellowship from the Jane Coffin Childs Memorial Fund for Medical Research.

Data Availability

The bacterial genome sequences for RPA have been deposited in the National Center for Biotechnology Information (NCBI)’s Sequence Read Archive (SRA) under the BioProject Accession Number PRJNA1112363. The bacterial RNAseq sequences and raw count matrix file have been deposited in NCBI’s Gene Expression Omnibus (GEO) under the GEO Accession Number GSE267862.

Conflict of Interest

The authors declare no conflicts of interest.

Additional Information

(This article belongs to the Special Issue Oxidative Stress in Wound Healing)

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Additional details

Created:
June 27, 2024
Modified:
June 27, 2024