Two-component system RstAB promotes the pathogenicity of adherent-invasive Escherichia coli in response to acidic conditions within macrophages

ABSTRACT

Adherent-invasive Escherichia coli (AIEC) strain LF82, isolated from patients with Crohn’s disease, invades gut epithelial cells, and replicates in macrophages contributing to chronic inflammation. In this study, we found that RstAB contributing to the colonization of LF82 in a mouse model of chronic colitis by promoting bacterial replication in macrophages. By comparing the transcriptomes of rstAB mutant- and wild-type when infected macrophages, 83 significant differentially expressed genes in LF82 were identified. And we identified two possible RstA target genes (csgD and asr) among the differentially expressed genes. The electrophoretic mobility shift assay and quantitative real-time PCR confirmed that RstA binds to the promoters of csgD and asr and activates their expression. csgD deletion attenuated LF82 intracellular biofilm formation, and asr deletion reduced acid tolerance compared with the wild-type. Acidic pH was shown by quantitative real-time PCR to be the signal sensed by RstAB to activate the expression of csgD and asr. We uncovered a signal transduction pathway whereby LF82, in response to the acidic environment within macrophages, activates transcription of the csgD to promote biofilm formation, and activates transcription of the asr to promote acid tolerance, promoting its replication within macrophages and colonization of the intestine. This finding deepens our understanding of the LF82 replication regulation mechanism in macrophages and offers new perspectives for further studies on AIEC virulence mechanisms.

KEYWORDS:

• Adherent-invasive Escherichia coli (AIEC)
• RstAB
• macrophages
• acid
• csgD
• asr
• biofilm

Acknowledgments

We would like to thank Xi Guo, Yanli Xu, and Junli Wu from Nankai University for the materials used in this study and Fenxia Liu for the operation instructions for confocal microscopy.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

YTL designed the study; TY, XML, YKL, YH, WY, RYL, QW, XPL, JRZ, and CJ conducted the experiments and data analyses. TY, YP, and YTL wrote and edited the manuscript.

Data availability statement

RNA sequencing data generated in this study are available from the NCBI SRA database. Accession to cite SRA data: PRJNA984413 https://www.ncbi.nlm.nih.gov/bioproject/?term=PRJNA984413.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19490976.2024.2356642

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China Program under Grant [Grant No. 32100144 and 32270191], the China Postdoctoral Science Foundation Program under Grant [Grant No. 2020M670623], the Fundamental Research Funds for the Central Universities, Nankai University [Grant No. 63233172], and the Fundamental Research Funds for the Central Universities [Grant No. 63241467].