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Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Biol Chem. Apr 7, 2020; 11(1): 1-13
Published online Apr 7, 2020. doi: 10.4331/wjbc.v11.i1.1
Why the discovery of adherent-invasive Escherichia coli molecular markers is so challenging?
Carla Camprubí-Font, Margarita Martinez-Medina
Carla Camprubí-Font, Margarita Martinez-Medina, Laboratory of Molecular Microbiology, Department of Biology, University of Girona, Girona 17003, Spain
Author contributions: All authors equally contributed to this paper with conception and design of the study, literature review and analysis, drafting and critical revision and editing, and final approval of the final version.
Supported by the Spanish Ministry of Economy and Competitiveness, No. SAF2017-82261-P.
Conflict-of-interest statement: Authors declare no conflict of interests for this article.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Margarita Martinez-Medina, PhD, Associate Professor, Laboratory of Molecular Microbiology, Department of Biology, Universitat de Girona, C/Maria Aurèlia Capmany, 40, Girona 17003, Spain. marga.martinez@udg.edu
Received: December 23, 2019
Peer-review started: December 23, 2019
First decision: February 18, 2020
Revised: March 18, 2020
Accepted: April 1, 2020
Article in press: April 1, 2020
Published online: April 7, 2020
Processing time: 105 Days and 18.9 Hours
Abstract

Adherent-invasive Escherichia coli (AIEC) strains have been extensively related to Crohn’s disease (CD) etiopathogenesis. Higher AIEC prevalence in CD patients versus controls has been reported, and its mechanisms of pathogenicity have been linked to CD physiopathology. In CD, the therapeutic armamentarium remains limited and non-curative; hence, the necessity to better understand AIEC as a putative instigator or propagator of the disease is certain. Nonetheless, AIEC identification is currently challenging because it relies on phenotypic assays based on infected cell cultures which are highly time-consuming, laborious and non-standardizable. To address this issue, AIEC molecular mechanisms and virulence genes have been studied; however, a specific and widely distributed genetic AIEC marker is still missing. The finding of molecular tools to easily identify AIEC could be useful in the identification of AIEC carriers who could profit from personalized treatment. Also, it would significantly promote AIEC epidemiological studies. Here, we reviewed the existing data regarding AIEC genetics and presented those molecular markers that could assist with AIEC identification. Finally, we highlighted the problems behind the discovery of exclusive AIEC biomarkers and proposed strategies to facilitate the search of AIEC signature sequences.

Keywords: Crohn’s disease; Adherent-invasive Escherichia coli; Molecular markers; Genetics; Inflammatory bowel disease; Signature sequences

Core tip: In this review, we thoroughly review the approaches for deciphering adherent-invasive Escherichia coli (AIEC) genetics. The characteristics of putative AIEC molecular markers that could assist in AIEC identification are described. We then discuss several aspects that could explain the difficulty behind the discovery of suitable biomarkers and highlight the importance of standardizing AIEC protocols in order to increase the probability of finding these biomarkers. Finally, we point out new approaches for looking for signature sequences that need to take into account the AIEC phylogenetic origin and strain virulence under particular experimental conditions.