Adherent-Invasive E. coli: Update on the Lifestyle of a Troublemaker in Crohn’s Disease

Abstract

Besides genetic polymorphisms and environmental factors, the intestinal microbiota is an important factor in the etiology of Crohn’s disease (CD). Among microbiota alterations, a particular pathotype of Escherichia coli involved in the pathogenesis of CD abnormally colonizes the intestinal mucosa of patients: the adherent-invasive Escherichia coli (AIEC) pathobiont bacteria, which have the abilities to adhere to and to invade intestinal epithelial cells (IECs), as well as to survive and replicate within macrophages. AIEC have been the subject of many studies in recent years to unveil some genes linked to AIEC virulence and to understand the impact of AIEC infection on the gut and consequently their involvement in CD. In this review, we describe the lifestyle of AIEC bacteria within the intestine, from the interaction with intestinal epithelial and immune cells with an emphasis on environmental and genetic factors favoring their implantation, to their lifestyle in the intestinal lumen. Finally, we discuss AIEC-targeting strategies such as the use of FimH antagonists, bacteriophages, or antibiotics, which could constitute therapeutic options to prevent and limit AIEC colonization in CD patients.

The Intestinal Microbiota and Colorectal Cancer

“…E. faecalis infection induces superoxide production, which damages DNA in epithelial cells (50,52). Although Escherichia coli (E. coli) is a gut commensal bacterium, studies have reported higher levels of colonic colonization by mucosa-associated E. coli in CRC patients compared with that in healthy people (53,54,58). Yu et al found Peptostreptococcus anaerobius (P. anaerobius) was significantly enriched in fecal and mucosal microbiotas from patients with CRC (55,56).…”

Crohn’s Disease Pathobiont Adherent-Invasive E coli Disrupts Epithelial Mitochondrial Networks With Implications for Gut Permeability

“…1 Tissues from patients with IBD often have increased numbers of Escherichia coli compared with those from healthy individuals, 2 and a subgroup therein, the adherent-invasive E coli (AIEC), has emerged as pathobionts. 3,4 Attaching via pili and long polar fimbriae, 5,6 AIEC can cause reactive oxygen species (ROS) and proinflammatory cytokine production by epithelial cells 7,8 and increase epithelial permeability. 9 AIECs have enhanced survival within macrophages, 10 and can exaggerate the severity of murine colitis.…”

The Interplay between Immune System and Microbiota in Inflammatory Bowel Disease: A Narrative Review

“…The most recurring and contrasted finding is the increase of adherent-invasive E. coli in the gut of IBD patients; this infectious agent is able to adhere to and cross the intestinal mucus barrier, invading the gut epithelial layer. Moreover, this species is capable of surviving and replicating in macrophages, leading to TNFα secretion and inflammation [ 92 , 120 ].…”