Extracellular Vesicles and Host-Pathogen Interactions: A Review of Inter-Kingdom Signaling by Small Noncoding RNA.

Bruce A Stanton

doi:10.3390/genes12071010

Abstract

The focus of this brief review is to describe the role of noncoding regulatory RNAs, including short RNAs (sRNA), transfer RNA (tRNA) fragments and microRNAs (miRNA) secreted in extracellular vesicles (EVs), in inter-kingdom communication between bacteria and mammalian (human) host cells. Bacteria secrete vesicles that contain noncoding regulatory RNAs, and recent studies have shown that the bacterial vesicles fuse with and deliver regulatory RNAs to host cells, and similar to eukaryotic miRNAs, regulatory RNAs modulate the host immune response to infection. Recent studies have also demonstrated that mammalian cells secrete EVs containing miRNAs that regulate the gut microbiome, biofilm formation and the bacterial response to antibiotics. Thus, as evidence accumulates it is becoming clear that the secretion of noncoding regulatory RNAs and miRNAs in extracellular vesicles is an important mechanism of bidirectional communication between bacteria and mammalian (human) host cells. However, additional research is necessary to elucidate how noncoding regulatory RNAs and miRNA secreted in extracellular vesicles mediate inter-kingdom communication.

Highlights

Numerous studies have demonstrated that extracellular vesicles (EVs) play an important role in cell–cell signaling in all three domains of life, and that EVs are an important mechanism of intra-kingdom and inter-kingdom communication, including communication between hosts and pathogens
Many recent studies have shown that outer membrane vesicle (OMV) and BEVs secreted by bacteria deliver short RNAs (sRNA) and transfer RNA (tRNA) fragments (~18 to 50 nucleotides long) to mammalian cells and, many details are lacking, it has been suggested that the sRNA and tRNA fragments regulate target cell gene expression by sequestering regulatory proteins and/or by base pairing with target mRNAs [4,18,22,30,31,32,41,47,48,49,50,51,52,53,54,55,56]
In this review, the focus will be on recent studies describing how sRNAs, tRNA fragments and miRNAs secreted inside vesicles mediate host–pathogen interactions between bacteria and mammalian cells

Summary

Introduction

Many recent studies have shown that OMVs and BEVs secreted by bacteria deliver sRNA and tRNA fragments (~18 to 50 nucleotides (nt) long) to mammalian (human) cells and, many details are lacking, it has been suggested that the sRNA and tRNA fragments regulate target cell gene expression by sequestering regulatory proteins and/or by base pairing with target mRNAs [4,18,22,30,31,32,41,47,48,49,50,51,52,53,54,55,56]. Very few studies have been published describing the role of extracellular vesicles as a delivery mechanism for sRNA, tRNA fragments and miRNAs to target cells and elucidating the mechanism whereby they mediate inter-kingdom signaling.

Results

Conclusion