Enhanced E. coli LF82 Translocation through the Follicle-associated Epithelium in Crohn’s Disease is Dependent on Long Polar Fimbriae and CEACAM6 expression, and Increases Paracellular Permeability

Abstract

Background and Aims Patients with Crohn’s disease [CD] harbour an increased number of adherent-invasive E. coli [AIEC]. The strain LF82, identified in the ileal mucosa of CD patients, has been extensively studied for pathogenic mechanisms. However, understanding of the interaction of LF82 with the intestinal mucosa of CD patients is lacking. Methods Here, we investigated the importance of long polar fimbriae [LPF] type 1 pili and the carcinoembryonic antigen-related cell-adhesion molecule 6 [CEACAM6] for translocation of LF82 in an in vitro model of follicle-associated epithelium [FAE], and in the FAE and villus epithelium [VE] of patients with CD and controls, using Ussing chambers. Results Significantly greater LF82 passage occurred in the FAE model compared with in the VE Caco-2cl1 mono-culture. Moreover, bacterial translocation was inhibited by either LPF disruption or pre-incubation with anti-CEACAM6 antibody. Tissue mounted in Ussing chambers showed significantly higher LF82 passage in FAE from patients with CD compared with control FAE, that was diminished in LF82 lacking LPF and by blocking host CEACAM6. Interestingly, addition of LF82 to the CD FAE tissues significantly increased paracellular permeability [of 51Chromium-EDTA] compared with baseline, and the increase was inhibited by anti-CEACAM6. Immunofluorescence and immunoblots showed higher expression of CEACAM6 in FAE of patients with CD compared with in FAE from controls. Conclusions These data suggest that the FAE of CD patients is a site of vulnerability for invasion by LF82 via a mechanism that requires both bacterial LPF and host CEACAM6. Further, LF82 has the ability to increase paracellular passage through the FAE of patients with CD. These data can help define novel therapeutic targets in CD for the prevention of clinical recurrence.

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

“…Lack of an effect of dead E coli-LF82 indicated that viable bacteria attaching to and/or invading the epithelium caused fragmentation of the mitochondrial network. In accordance, epithelia exposed to E coli-LF82 deficient in type 1 pili, which are critical for adhesion and invasion, 9 had mitochondrial networks similar to noninfected epithelia. Furthermore, the AIEC strain NRG857c that was less invasive in T84 epithelia caused little mitochondrial fragmentation compared with E coli-LF82.…”

“…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. 11,12 A comprehensive knowledge of the mechanism(s) by which AIECs participate in IBD is lacking.…”

The Intestinal Barrier and Current Techniques for the Assessment of Gut Permeability

“…Inflammatory bowel disease in vivo; altered expression and distribution of tight junction proteins [5]; ex vivo, increased passage of paracellular probes [6,7] ex vivo; augmented mucosal passage of bacteria and horseradish peroxidase (HRP) [6][7][8] in vivo; increased urinary secretion of probes [9] Irritable bowel syndrome altered expression of tight junction proteins [10]; ex vivo; increased passage of paracellular probes [1,2]. ex vivo; increased transepithelial passage of bacteria and HRP [11] in vivo; increased urinary secretion of probes [12] Celiac disease in vivo: altered structure of tight junction proteins [13,14] ex vivo; increased passage of paracellular probes [15]; alteration in electrophysiological parameters [16] ex vivo; augmented internalization of bacteria [17]; increased transcellular uptake of gliadin [18] in vivo; increased urinary secretion of probes [15,19], increased levels of zonulin in blood [20] Obesity in vivo; altered expression of tight junction proteins [3] ex vivo; increased lipid-induced transcellular permeability [3] in vivo; increased levels of zonulin and lipopolysaccharide (LPS) in blood [3] Diabetes type 2 --in vivo; increased urinary secretion of probes [4]; increased levels of LPS [21] and zonulin [22] in blood…”

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

“…Host-AIEC interaction can also occur through the follicle-associated epithelium (FAE) overlying Peyer's Patches (PP), where M-cells are located, via Long Polar Fimbriae (LPF) expression by the bacteria. Indeed, a lpf -negative AIEC mutant was highly impaired in its ability to interact with mouse and human PP and to translocate across monolayers of M-cells (specialized cells of FAE), demonstrating that LPF, whose expression is dependent of bile salts concentration is a key factor for AIEC-PP interaction [64][65][66]. AIEC could also bind M-cells via the interaction between the FimH adhesin and the glycoprotein 2 (GP2), expressed on the apical membrane of M-cells promoting mucosal immune response to AIEC [67].…”