Characterization of Outer Membrane Vesicles from Fusobacterium nucleatum

Raafat Munshi

doi:10.17485/ijst/2020/v13i02/148492

Abstract

Background/objectives: Fusobacterium nucleatum is an oral pathogen and is associated with the development of colorectal cancer (CRC). This study is to evaluate the ability of outer membrane vesicles (OMV) from F. nucleatum to modulate cellular responses in colonic cells. Methodology: Here we show that infection of colonic epithelial cells with F. nucleatum and its OMV induce pro-inflammatory chemokine and cytokine production and promote an EMT-like pheno- and genotypes in vitro as demonstrated by suppression of E-cadherin and up-regulation of several mesenchymal markers. F. nucleatum and its OMV modulate the barrier function of intestinal monolayers, a process likely related to their demonstrated ability to degrade E-cadherin and suppress its expression. Findings: Analysis of the OMV proteome by mass spectrometry demonstrates that they harbor the known virulence factors that appear to be enriched with proteolytic activity. Novelty/contribution: Taken together, these data indicate that F. nucleatum OMV have the potential to contribute to disease progression in the context of CRC. Keywords: Outer Membrane Vesicles, Fusobacterium nucleatum, Colorectal Cancer, Protease.

Highlights

In colorectal cancer (CRC), mutations in the APC/Wnt pathway in colonic epithelial stem cells lead to the formation of adenomatous lesions [1]
outer membrane vesicles (OMV) isolated from the supernatant of broth grown F. nucleatum were 20–200 nm in diameter and free from intact cells and/or cellular debris (Figure 1A)
Preparations of OMV contained two types of vesicles, single membrane and bi-layered species. The latter type are released by other bacteria and contain both the inner cytoplasmic and outer membrane proteins [21] and likely account for the presence of cytoplasmic components frequently observed associated with OMV

Summary

Introduction

In colorectal cancer (CRC), mutations in the APC/Wnt pathway in colonic epithelial stem cells lead to the formation of adenomatous lesions [1]. Current evidence indicates a role for the microbiota in CRC with specific species/genera and polymicrobial signatures associated with CRC adenomas and tumors [2,3,4]. F. nucleatum adheres to and invades epithelial cells via the adhesin FadA [14] which engages with host E-cadherin resulting in nuclear translocation of β-catenin and activation of the Wnt pathway [6,14]. As F. nucleatum is considered a “bridging” biofilm-promoting organism in the oral cavity, disease progression may be influenced by mechanisms shared between bacterial species rather than just F. nucleatum [15]

Methods

Results

Conclusion