The Outer Membrane Vesicles of Aeromonas hydrophila ATCC® 7966TM: A Proteomic Analysis and Effect on Host Cells.

Eric Daniel Avila-Calderón,Jorge Erick Otero-Olarra,Olin Medina-Chávez,Araceli Contreras-Rodríguez,María Rosario Morales-García,Leopoldo Flores-Romo,Ma Guadalupe Aguilera-Arreola,Luis Donis-Maturano,Humberto Peralta,María Del Socorro Ruiz-Palma,Juana Calderón-Amador

doi:10.3389/fmicb.2018.02765

Abstract

Gram-negative bacteria release outer membrane vesicles (OMVs) into the extracellular environment. OMVs have been studied extensively in bacterial pathogens, however, information related with the composition of Aeromonas hydrophila OMVs is missing. In this study we analyzed the composition of purified OMVs from A. hydrophila ATCC® 7966TM by proteomics. Also we studied the effect of OMVs on human peripheral blood mononuclear cells (PBMCs). Vesicles were grown in agar plates and then purified through ultracentrifugation steps. Purified vesicles showed an average diameter of 90–170 nm. Moreover, 211 unique proteins were found in OMVs from A. hydrophila; some of them are well-known as virulence factors such as: haemolysin Ahh1, RtxA toxin, extracellular lipase, HcpA protein, among others. OMVs from A. hydrophila ATCC® 7966TM induced lymphocyte activation and apoptosis in monocytes, as well as over-expression of pro-inflammatory cytokines. This work contributed to the knowledge of the composition of the vesicles of A. hydrophila ATCC® 7966TM and their interaction with the host cell.

Highlights

The release of outer membrane vesicles (OMVs) from bacteria was described about 40 years ago
Virulence factors have been identified in bacterial pathogens; for instance the heat/labile enterotoxin (LT), the Shiga toxins 1 and 2, as well as the ClyA cytotoxic protein found in the OMVs of Escherichia coli (Gankema et al, 1980; Wai et al, 1995, 2003; Kolling and Matthews, 1999)
Even though much information has been published about OMVs from several pathogens, due to the paucity of data on OMVs from A. hydrophila, in this work we aimed to analyze the protein composition of the OMVs purified from A. hydrophila ATCC R 7966TM, as well as to evaluate the capacity to elicit immunological response and cytotoxic effect on host cell

Summary

Introduction

The release of outer membrane vesicles (OMVs) from bacteria was described about 40 years ago. In the last 15 years much information related to these nanovesicles has been published related to the composition, the biogenesis as well as with the regulation in the composition of OMVs (Beveridge, 1999; Kuehn and Kesty, 2005; Mashburn-Warren and Whiteley, 2006; Lee et al, 2008). OMVs have been implicated in many processes including the release of virulence factors such as proteases and toxins, molecules signaling between bacterial and eukaryotic cells, DNA transfer, antibacterial activity, immunomodulation of the host and facilitation of bacterial survival during envelope stress (Kuehn and Kesty, 2005; Mashburn-Warren and Whiteley, 2006; Lee et al, 2008). The cholera toxin (CT) of Vibrio cholerae was associated with OMVs (Chatterjee and Chaudhuri, 2011) Helicobacter pylori OMVs contain the cytotoxins VacA, and CagA (Olofsson et al, 2010)

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