Microbiota–host communications: Bacterial extracellular vesicles as a common language

Abstract

Both gram-negative and gram-positive bacteria release extracellular vesicles (EVs) that contain components from their mother cells. Bacterial EVs are similar in size to mammalian-derived EVs and are thought to mediate bacteria–host communications by transporting diverse bioactive molecules including proteins, nucleic acids, lipids, and metabolites. Bacterial EVs have been implicated in bacteria–bacteria and bacteria–host interactions, promoting health or causing various pathologies. Although the science of bacterial EVs is less developed than that of eukaryotic EVs, the number of studies on bacterial EVs is continuously increasing. This review highlights the current state of knowledge in the rapidly evolving field of bacterial EV science, focusing on their discovery, isolation, biogenesis, and more specifically on their role in microbiota–host communications. Knowledge of these mechanisms may be translated into new therapeutics and diagnostics based on bacterial EVs.

Effects of gut microbiota–derived extracellular vesicles on obesity and diabetes and their potential modulation through diet

“…However, the isolation and characterization of the heterogeneous profile of the gut microbiota are far more complex. As it was pointed out by other authors [ 95 ], a major obstacle is the lack of bacterial EV universal markers and their size-similarities to mammalian EVs, which complicate their separation from mammalian EVs in corporal fluids. Nevertheless, research continues to overcome these limitations, and recently Lagos et al [ 75 ] isolated and characterized EVs from pig gut microbiota in vitro, and new methods have been developed to isolate more effectively bacterial EVs from body fluids [ 124 ].…”

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

“…OMVs and BEVs secreted by microbes serve a variety of intra-kingdom functions, including horizontal gene transfer, quorum sensing, biofilm formation, pathogenicity, depredation, antibiotic resistance, defense, and nutrient acquisition [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 38 , 60 , 61 ]. Similar to miRNAs, every bacterial sRNA and tRNA fragment is predicted to have multiple targets, can regulate genes in cis and trans, modulates transcription and translation, and affects mRNA stability [ 2 ].…”

“…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 (reviewed in [1][2][3][4][5][6][7][8][9][10][11][12][13]). The secretion of EVs as a mechanism of intra-kingdom and inter-kingdom communication is evolutionarily conserved, as cells from prokaryotes, plants, and animals release EVs [14][15][16].…”

“…However, studies have shown that RNA and proteins also decorate the extra-vesicular surface of EVs and have biological activity [23]. EVs have been identified in all biological fluids and organs [24], have long half-lives in blood (30 min to 6 h [25,26]), enter cells by a variety of mechanisms, and once inside target cells, release their contents whereupon proteins, small RNAs (sRNAs), tRNA fragments and microRNAs (miRNAs) regulate recipient cell gene expression and function [1][2][3][4][5][6][7][8][9][10][11][12][13]. Currently, eukaryotic EVs are classified into many subgroups, including exosomes, microvesicles, and apoptotic bodies, based on their origin, biogenesis, size (~10 to 1000 nm) and composition [10,21,27,28].…”

“…tRNA fragments have been shown to mediate gene silencing in eukaryotic cells through an argonaute (Ago2)-microRNA-like mechanism and have both negative and positive effects on protein translation [57][58][59]. Many excellent and comprehensive reviews on EVs, OMVs and BEVs have been published [1][2][3][4][5][6][7][8][9][10][11][12][13]. However, 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.…”