Effect of the Extracellular Vesicle RNA Cargo From Uropathogenic Escherichia coli on Bladder Cells.

Priscila Dauros-Singorenko,Anthony Phillips,Cherie Blenkiron,Simon Swift,Jiwon Hong

doi:10.3389/fmolb.2020.580913

Priscila Dauros-Singorenko, Anthony Phillips + Show 3 more

Open Access

https://doi.org/10.3389/fmolb.2020.580913

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Abstract

Iron restriction in mammals, part of innate antimicrobial defense, may be sensed as a signal by an infecting pathogen. Iron-dependent regulators not only activate the pathogen’s specific iron acquisition and storage mechanisms needed for survival but also influence a number of other processes. Bacterial extracellular vesicles (EVs) are a conserved communication mechanism, which can have roles in host colonization, transfer of antimicrobial resistance, modulation of the host’s immune response, and biofilm formation. Here we analyze the iron-responsive effect of RNA cargo from Escherichia coli EVs in bladder cells. No differences were found in total RNA quantified from EVs released from representative pathogenic and probiotic strains grown in different iron conditions; nevertheless, lipopolysaccharide (LPS) associated with purified RNA was 10 times greater from EVs derived from the pathogenic strain. The pathogen and probiotic EV-RNA have no substantial toxic effect on the viability of cultured bladder cells, regardless of the iron concentration during bacterial culture. Transcriptomic analysis of bladder cells treated with pathogen EV-RNA delivered in artificial liposomes revealed a gene expression profile with a strong similarity to that of cells treated with liposomes containing LPS alone, with the majority being immune response pathways. EV-RNA from the probiotic strain gave no significant perturbation of gene expression in bladder cells. Cytokine profiling showed that EV-LPS has a role modulating the immune response when internalized by bladder cells, highlighting a key factor that must be considered when evaluating functional studies of bacterial RNA.

Highlights

It is well established that extracellular vesicles (EVs), known as membrane vesicles, are a conserved communication vehicle across prokaryotes (Chernov et al, 2014; Brown et al, 2015; Schwechheimer and Kuehn, 2015; Erdmann et al, 2017)
Extracellular Vesicles from pathogenic uropathogenic Escherichia coli (UPEC) 536 (UPEC) and probiotic Nissle 1917 (Nissle) E. coli strains were purified from 3 independent replicate cultures
Each EV crude preparation was purified by Size Exclusion Chromatography (SEC) and resulting fractions quantified in protein and particle counts to demonstrate EV enrichment in fractions

Summary

Introduction

It is well established that extracellular vesicles (EVs), known as membrane vesicles, are a conserved communication vehicle across prokaryotes (Chernov et al, 2014; Brown et al, 2015; Schwechheimer and Kuehn, 2015; Erdmann et al, 2017). Regardless of the phylogenetic group of origin, EVs are spherical nanostructures derived from the membrane(s) of parental cells that are UPEC EV RNA released into their extracellular milieu (Gill et al, 2019). Bacterial EVs have been described to carry a diverse molecular cargo (proteins, DNA, RNA, glycolipids, organic small molecules) derived from assorted cellular origins (Nagakubo et al, 2020). Antibiotics known to cause DNA damage such as fluoroquinolones trigger a SOS response and lyse cells to induce the production of EVs with a double bilayer EV morphology and predominantly cytoplasm-derived protein content (Devos et al, 2017)

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