Abstract
Background & AimsAdherent-invasive E. coli (AIEC) has largely been implicated in the pathogenesis of Crohn’s disease (CD). E. coli strains with similar genetic backgrounds and virulence genes profiles have been associated with other intestinal disorders, such as ulcerative colitis (UC), colorectal cancer (CRC), and coeliac disease (CeD), but the role of AIEC in these diseases remains unexplored. We aimed to assess the distribution, abundance, and pathogenic features of AIEC in UC, CRC, and CeD.MethodsThe AIEC phenotype was investigated in 4,233 E. coli isolated from the ileum and colon of 14 UC and 15 CRC patients and in 38 fecal E. coli strains obtained from 17 CeD and 10 healthy (H) children. AIEC prevalence and abundance were compared with previous data from CD patients and H controls. Clonality, virulence gene carriage, and phylogenetic origin were determined for the AIEC identified.ResultsIn UC, AIEC prevalence was intermediate between CD and H subjects (UC: 35.7%, CD: 55.0%, H: 21.4%), and similar to CD patients with colonic disease (C-CD: 40.0%). In CRC, the prevalence was lower (6.7%) than these groups. In patients with AIEC, the estimated abundance was similar across all intestinal conditions. All AIEC strains isolated from UC and CRC belonged to the B1 phylogroup, except for a strain of the A phylogroup, and the majority (75% of clonally distinct AIEC) harbored the Afa/Dr operon and the cdt gene. None of the E. coli isolated from the CeD cohort were AIEC. Nonetheless, E. coli strains isolated from active CeD patients showed higher invasion indices than those isolated from H and inactive CeD pediatric patients.ConclusionWe support the hypothesis that AIEC-like strains can be involved not only in CD but also in UC. Further works are needed to study the virulence particularities of these groups of strains and to determine if there is a causative link between AIEC and UC. In contrast, we rule out the possible association of AIEC with CRC. In addition, to further study the E. coli strains in CeD for their possible pathogenic role would be of interest.
Highlights
Adherent-invasive Escherichia coli (AIEC) comprises a group of genetically diverse E. coli with adhesion and invasion abilities and intramacrophage survival and replication capacity, genetically distinct from known intestinal pathogenic E. coli pathotypes and close to extraintestinal pathogenic E. coli (ExPEC) [1–4]
At the moment of sampling, two patients had severe disease, whereas the others featured moderate or mild activity, and none was in remission according to both UCDAI (Ulcerative Colitis Disease Activity Index) and Mayo score (Supplementary Table 1)
Concerning the proportion represented by these indole negative strains among the isolates recovered per subject, the lowest abundance was reported in Crohn’s disease (CD) patients (2.2–5.9%), whereas H subjects featured the highest load (1.0–77.1%), followed by colorectal cancer (CRC) subjects (0.4–75.0%) (p >0.05; Table 2)
Summary
Adherent-invasive Escherichia coli (AIEC) comprises a group of genetically diverse E. coli with adhesion and invasion abilities and intramacrophage survival and replication capacity, genetically distinct from known intestinal pathogenic E. coli pathotypes and close to extraintestinal pathogenic E. coli (ExPEC) [1–4]. AIEC has been suggested to be implicated in Crohn’s disease (CD) pathogenesis; first, because its pathogenicity mechanisms have been comprehensively linked to many characteristics of CD physiopathology [see reviews [5–10]]; and second, because several independent studies have revealed a higher prevalence of AIEC in CD patients [1, 2, 11–17]. Some studies show that this prevalence of AIEC in UC is lower than in CD [1, 16], whereas others sustain that it is similar or even higher [15, 18, 19]. Adherent-invasive E. coli (AIEC) has largely been implicated in the pathogenesis of Crohn’s disease (CD). E. coli strains with similar genetic backgrounds and virulence genes profiles have been associated with other intestinal disorders, such as ulcerative colitis (UC), colorectal cancer (CRC), and coeliac disease (CeD), but the role of AIEC in these diseases remains unexplored. We aimed to assess the distribution, abundance, and pathogenic features of AIEC in UC, CRC, and CeD
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