Role of mucus-bacteria interactions in Enterotoxigenic Escherichia coli (ETEC) H10407 virulence and interplay with human microbiome.

The intestinal mucus layer has a dual role in human health constituting a well-known microbial niche that supports gut microbiota maintenance but also acting as a physical barrier against enteric pathogens. Enterotoxigenic Escherichia coli (ETEC), the major agent responsible for traveler's diarrhea, is able to bind and degrade intestinal mucins, representing an important but understudied virulent trait of the pathogen. Using a set of complementary in vitro approaches simulating the human digestive environment, this study aimed to describe how the mucus microenvironment could shape different aspects of the human ETEC strain H10407 pathophysiology, namely its survival, adhesion, virulence gene expression, interleukin-8 induction and interactions with human fecal microbiota. Using the TNO gastrointestinal model (TIM-1) simulating the physicochemical conditions of the human upper gastrointestinal (GI) tract, we reported that mucus secretion and physical surface sustained ETEC survival, probably by helping it to face GI stresses. When integrating the host part in Caco2/HT29-MTX co-culture model, we demonstrated that mucus secreting-cells favored ETEC adhesion and virulence gene expression, but did not impede ETEC Interleukin-8 (IL-8) induction. Furthermore, we proved that mucosal surface did not favor ETEC colonization in a complex gut microbial background simulated in batch fecal experiments. However, the mucus-specific microbiota was widely modified upon the ETEC challenge suggesting its role in the pathogen infectious cycle. Using multi-targeted in vitro approaches, this study supports the major role played by mucus in ETEC pathophysiology, opening avenues in the design of new treatment strategies.

An adherent-invasive Escherichia coli-colonized mouse model to evaluate microbiota-targeting strategies in Crohn's disease.

Adherent-invasive Escherichia coli (AIEC) were investigated for their involvement in the induction/chronicity of intestinal inflammation in Crohn's disease (CD). AIEC gut establishment is favoured by overexpression of the glycoprotein CEACAM6 in the ileal epithelium. We generated a transgenic mouse model, named 'Vill-hCC6', in which the human CEACAM6 gene was under the control of the villin promoter, conditioning expression in the small intestine. We demonstrated that CEACAM6 is strongly expressed in the small intestine mucosa and is correlated with numerous glycosylations displayed at the brush border of enterocytes. Ex vivo, the AIEC-enterocyte interaction was enhanced by CEACAM6 expression and necessitated the presence of the bacterial adhesive factor FimH. Finally, AIEC bacteria preferentially persisted in a FimH-dependent manner in the ileal mucosa of Vill-hCC6 mice compared to wild-type mice. This preclinical model opens new perspectives in the mechanistic study of the AIEC pathobiont and represents a valuable tool to evaluate the efficacy of new strategies to eliminate AIEC implanted in the ileal mucosa, such as phages, inhibitory and/or anti-virulence molecules, or CRISPR-based strategies targeting virulence or fitness factors of AIEC bacteria.

Epigenetic master regulators HDAC1 and HDAC5 control pathobiont Enterobacteria colonization in ileal mucosa of Crohn's disease patients.

ABBREVIATIONS: AIEC Adherent-Invasive Escherichia coli; BSA Bovine serum albumin; CD Crohn's disease; CEABAC10 Carcinoembryonic antigen bacterial artificial chromosome 10; CEACAM Carcinoembryonic antigen-related cell adhesion molecule; FBS Fetal bovine serum; IBD Inflammatory Bowel Disease; HAT Histone acetyltransferase; HDAC Histone deacetylase; kDa KiloDalton; SAHA Suberoylanilide Hydroxamic Acid; Scr Scramble.

Beneficial Effects of Linseed Supplementation on Gut Mucosa-Associated Microbiota in a Physically Active Mouse Model of Crohn's Disease.

The Western diet, rich in lipids and in n-6 polyunsaturated fatty acids (PUFAs), favors gut dysbiosis observed in Crohn's disease (CD). The aim of this study was to assess the effects of rebalancing the n-6/n-3 PUFA ratio in CEABAC10 transgenic mice that mimic CD. Mice in individual cages with running wheels were randomized in three diet groups for 12 weeks: high-fat diet (HFD), HFD + linseed oil (HFD-LS-O) and HFD + extruded linseed (HFD-LS-E). Then, they were orally challenged once with the Adherent-Invasive Escherichia coli (AIEC) LF82 pathobiont. After 12 weeks of diet, total energy intake, body composition, and intestinal permeability were not different between groups. After the AIEC-induced intestinal inflammation, fecal lipocalin-2 concentration was lower at day 6 in n-3 PUFAs supplementation groups (HFD-LS-O and HFD-LS-E) compared to HFD. Analysis of the mucosa-associated microbiota showed that the abundance of Prevotella, Paraprevotella, Ruminococcus, and Clostridiales was higher in the HFD-LS-E group. Butyrate levels were higher in the HFD-LS-E group and correlated with the Firmicutes/Proteobacteria ratio. This study demonstrates that extruded linseed supplementation had a beneficial health effect in a physically active mouse model of CD susceptibility. Additional studies are required to better decipher the matrix influence in the linseed supplementation effect.

In Vitro Evaluation of Dietary Fiber Anti-Infectious Properties against Food-Borne Enterotoxigenic Escherichia coli.

Dietary fibers have well-known beneficial effects on human health, but their anti-infectious properties against human enteric pathogens have been poorly investigated. Enterotoxigenic Escherichia coli (ETEC) is the main agent of travelers' diarrhea, against which targeted preventive strategies are currently lacking. ETEC pathogenesis relies on multiple virulence factors allowing interactions with the intestinal mucosal layer and toxins triggering the onset of diarrheal symptoms. Here, we used complementary in vitro assays to study the antagonistic properties of eight fiber-containing products from cereals, legumes or microbes against the prototypical human ETEC strain H10407. Inhibitory effects of these products on the pathogen were tested through growth, toxin production and mucus/cell adhesion inhibition assays. None of the tested compounds inhibited ETEC strain H10407 growth, while lentil extract was able to decrease heat labile toxin (LT) concentration in culture media. Lentil extract and specific yeast cell walls also interfered with ETEC strain H10407 adhesion to mucin beads and human intestinal cells. These results constitute a first step in the use of dietary fibers as a nutritional strategy to prevent ETEC infection. Further work will be dedicated to the study of fiber/ETEC interactions within a complex gut microbial background.

Heteropolysaccharides from S. cerevisiae show anti-adhesive properties against E. coli associated with Crohn's disease.

The Saccharomyces cerevisiae CNCM I-3856 was previously reported to strongly inhibit adherent-invasive Escherichia coli (AIEC) adhesion to intestinal epithelial cells in vitro and to favor AIEC elimination from the gut in a murine model of Crohn's disease in vivo. In order to identify which cell wall components of yeast are responsible for AIEC elimination, constituent polysaccharides of yeast were isolated and their anti-adhesive ability against AIEC adhesion in vitro was screened. A fraction containing mannan, ß-glucan and α-glucan extracted from yeast cell-walls was shown to inhibit 95% of AIEC adhesion in vitro and was thus identified as the strongest anti-adhesive yeast cell wall component. Furthermore, this mannan-glucan-containing fraction was shown to accelerate AIEC decolonization from gut in vivo. This fraction could be proposed as a treatment to eliminate AIEC bacteria in patients with Crohn's disease, a microbial trigger of intestinal inflammation.

Blockage of bacterial FimH prevents mucosal inflammation associated with Crohn's disease.

BACKGROUND: An Escherichia coli (E. coli) pathotype with invasive properties, first reported by Darfeuille-Michaud and termed adherent-invasive E. coli (AIEC), was shown to be prevalent in up to half the individuals with Crohn's Disease (CD), suggesting that these bacteria could be involved in the pathophysiology of CD. Among the genes related to AIEC pathogenicity, fim has the potential to generate an inflammatory reaction from the intestinal epithelial cells and macrophages, as it interacts with TLR4, inducing the production of inflammatory cytokines independently of LPS. Therefore, targeting the bacterial adhesion of FimH-expressing bacteria seems a promising therapeutic approach, consisting of disarming bacteria without killing them, representing a selective strategy to suppress a potentially critical trigger of intestinal inflammation, without disturbing the intestinal microbiota. RESULTS: We analyzed the metagenomic composition of the gut microbiome of 358 patients with CD from two different cohorts and characterized the presence of FimH-expressing bacteria. To assess the pathogenic role of FimH, we used human intestinal explants and tested a specific FimH blocker to prevent bacterial adhesion and associated inflammation. We observed a significant and disease activity-dependent enrichment of Enterobacteriaceae in the gut microbiome of patients with CD. Bacterial FimH expression was functionally confirmed in ileal biopsies from 65% of the patients with CD. Using human intestinal explants, we further show that FimH is essential for adhesion and to trigger inflammation. Finally, a specific FimH-blocker, TAK-018, inhibits bacterial adhesion to the intestinal epithelium and prevents inflammation, thus preserving mucosal integrity. CONCLUSIONS: We propose that TAK-018, which is safe and well tolerated in humans, is a promising candidate for the treatment of CD and in particular in preventing its recurrence. Video abstract.

The Role of OmpR in Bile Tolerance and Pathogenesis of Adherent-Invasive Escherichia coli.

Gut microbiota dysbiosis toward adherent-invasive Escherichia coli (AIEC) plays an important role in Crohn's disease (CD). The OmpR transcriptional regulator is required for the AIEC LF82 prototype strain to adhere and invade intestinal epithelial cells. In this study, we explored the role of OmpR in AIEC pathogenesis using a panel of eight Escherichia coli strains isolated from CD patients and identified as AIEC. The deletion of ompR together with the implementation of two cell-based assays revealed that the role of OmpR in adhesion in vitro was not conserved in AIEC clinical strains. Nevertheless, we showed that OmpR was required for robust gut colonization of transgenic mice expressing human CEACAM receptors, suggesting that OmpR is involved in alternative virulence mechanisms in AIEC strains. We found that deletion of ompR compromised the ability of AIEC strains to cope with the stress induced by bile salts, which may be key for AIEC pathogenesis. More specifically, we demonstrated that OmpR was involved in a tolerance mechanism toward sodium deoxycholate (DOC), one of bile salts main component. We showed that the misregulation of OmpF or the loss of outer membrane integrity are not the drivers of OmpR-mediated DOC tolerance, suggesting that OmpR regulates a specific mechanism enhancing AIEC survival in the presence of DOC. In conclusion, the newly discovered role of OmpR in AIEC bile tolerance suggests that OmpR inhibition would interfere with different aspects of AIEC virulence arsenal and could be an alternative strategy for CD-treatment.

Tripartite relationship between gut microbiota, intestinal mucus and dietary fibers: towards preventive strategies against enteric infections.

The human gut is inhabited by a large variety of microorganims involved in many physiological processes and collectively referred as to gut microbiota. Disrupted microbiome has been associated with negative health outcomes and especially could promote the onset of enteric infections. To sustain their growth and persistence within the human digestive tract, gut microbes and enteric pathogens rely on two main polysaccharide compartments, namely dietary fibers and mucus carbohydrates. Several evidences suggest that the three-way relationship between gut microbiota, dietary fibers and mucus layer could unravel the capacity of enteric pathogens to colonise the human digestive tract and ultimately lead to infection. The review starts by shedding light on similarities and differences between dietary fibers and mucus carbohydrates structures and functions. Next, we provide an overview of the interactions of these two components with the third partner, namely, the gut microbiota, under health and disease situations. The review will then provide insights into the relevance of using dietary fibers interventions to prevent enteric infections with a focus on gut microbial imbalance and impaired-mucus integrity. Facing the numerous challenges in studying microbiota-pathogen-dietary fiber-mucus interactions, we lastly describe the characteristics and potentialities of currently available in vitro models of the human gut.

Ulcerative Colitis-associated E. coli pathobionts potentiate colitis in susceptible hosts.

Ulcerative colitis (UC) is a chronic inflammatory condition linked to intestinal microbial dysbiosis, including the expansion of E. coli strains related to extra-intestinal pathogenic E. coli. These "pathobionts" exhibit pathogenic properties, but their potential to promote UC is unclear due to the lack of relevant animal models. Here, we established a mouse model using a representative UC pathobiont strain (p19A), and mice lacking single immunoglobulin and toll-interleukin 1 receptor domain (SIGIRR), a deficiency increasing susceptibility to gut infections. Strain p19A was found to adhere to the cecal mucosa of Sigirr -/- mice, causing modest inflammation. Moreover, it dramatically worsened dextran sodium sulfate-induced colitis. This potentiation was attenuated using a p19A strain lacking α-hemolysin genes, or when we targeted pathobiont adherence using a p19A strain lacking the adhesin FimH, or following treatment with FimH antagonists. Thus, UC pathobionts adhere to the intestinal mucosa, and worsen the course of colitis in susceptible hosts.

Methyl-donor supplementation prevents intestinal colonization by Adherent-Invasive E. coli in a mouse model of Crohn's disease.

Deficiencies in methyl-donor molecules (folate, B12 vitamin), DNA methylation alteration and high prevalence of Adherent-Invasive Escherichia coli (AIEC) are frequently observed in Crohn's disease (CD) patients. AIEC bacteria adhere to the enterocytes through abnormally expressed carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) glycoprotein on host cells. This work aims at studying the relationship between methyl-donor molecules and AIEC-induced intestinal inflammatory response. CEABAC10 mice, a mouse model of CD, were fed a control or Methyl-donor Supplemented diet (MS diet). CEACAM6 promoter was hypermethylated in intestinal epithelial cells from mice fed an MS diet, which was associated with a significant decrease in CEACAM6 expression. Transcriptomic analysis revealed increased expression of anti-microbial peptides, increase in HSP70 gene family expression and a decreased expression of inflammatory marker Calprotectin upon MS diet, associated to a lower ability of AIEC bacteria to colonize gut mucosa. We observed in a cohort of CD patients that serum folate concentration was inversely correlated to Crohn's disease endoscopic index of severity and to fecal inflammatory markers. This study demonstrates that methyl-donor supplementation through the diet induces a specific intestinal micro-environment limiting pathobiont colonization of the gut. Clinicians may wish to consider methyl-donor supplementation for methyl-donor deficient CD patients.

Heptylmannose-functionalized cellulose for the binding and specific detection of pathogenic E. coli.

We developed a chemical method to covalently functionalize cellulose nanofibers and cellulose paper with mannoside ligands displaying a strong affinity for the FimH adhesin from pathogenic E. coli strains. Mannose-grafted cellulose proved efficient to selectively bind FimH lectin and discriminate pathogenic E. coli strains from non-pathogenic ones. These modified papers are valuable tools for diagnosing infections promoted by E. coli, such as cystitis or inflammatory bowel diseases, and the concept may be applicable to other life-threatening pathogens.

Oligomannose-Rich Membranes of Dying Intestinal Epithelial Cells Promote Host Colonization by Adherent-Invasive E. coli.

A novel mechanism is revealed by which clinical isolates of adherent-invasive Escherichia coli (AIEC) penetrate into the epithelial cell layer, replicate, and establish biofilms in Crohn's disease. AIEC uses the FimH fimbrial adhesin to bind to oligomannose glycans on the surface of host cells. Oligomannose glycans exposed on early apoptotic cells are the preferred binding targets of AIEC, so apoptotic cells serve as potential entry points for bacteria into the epithelial cell layer. Thereafter, the bacteria propagate laterally in the epithelial intercellular spaces. We demonstrate oligomannosylation at two distinct sites of a glycoprotein receptor for AIEC, carcinoembryonic antigen related cell adhesion molecule 6 (CEACAM6 or CD66c), on human intestinal epithelia. After bacterial binding, FimH interacts with CEACAM6, which then clusters. The presence of the highest-affinity epitope for FimH, oligomannose-5, on CEACAM6 is demonstrated using LC-MS/MS. As mannose-dependent infections are abundant, this mechanism might also be used by other adherent-invasive pathogens.

The potential of FimH as a novel therapeutic target for the treatment of Crohn's disease.

INTRODUCTION: Crohn's disease (CD) is a life-long chronic disorder characterized by intestinal inflammation. Current treatments for CD are directed towards abnormal immune responses rather than the intestinal bacteria that trigger intestinal inflammation. Areas covered: Adherent-Invasive Escherichia coli (AIEC) bacteria abnormally colonize the ileal mucosa in a subgroup of CD patients. They can promote or perpetuate chronic inflammation and are therefore an interesting therapeutic target. Various strategies that target these E. coli strains have been developed to promote their intestinal clearance. Here, we review current AIEC-targeted strategies, especially anti-adhesive strategies, that are based on the development of FimH antagonists. We discuss their potential as personalized microbiota-targeted treatments for CD patients abnormally colonized by AIEC. Expert opinion: A large panel of mannose-derived FimH antagonists were tested for their ability to inhibit E. coli adhesion to host cells. Documented reports suggest that monovalent mannosides are promising candidates that could represent a complementary therapeutic strategy to prevent intestinal inflammation in the E. coli-colonized CD patient subgroup. Ongoing research continues to improve the pharmacokinetic properties of mannosides, and hopefully, clinical trials will be performed in CD patients in the near future.

Physiochemical Tuning of Potent Escherichia coli Anti-Adhesives by Microencapsulation and Methylene Homologation.

Thiazolylaminomannosides (TazMan) are FimH antagonists with anti-adhesive potential against adherent-invasive Escherichia coli (AIEC) promoting gut inflammation in patients with Crohn's disease. The lead TazMan is highly potent in vitro, but shows limited in vivo efficiency, probably due to low pH stability and water solubility. We recently developed a second generation of stable TazMan, but the anti-adhesive effect was lower than the first. Herein we report a co-crystal structure of the lead TazMan in FimH, revealing that the anomeric NH group and the second thiazole moiety provide a positive hydrogen bonding interaction with a trapped water molecule, and π-stacking with Tyr48 of FimH, respectively. Consequently, we developed NeoTazMan homologated with a methylene group for low-pH and mannosidase stability with a conserved NH group and bearing various heterocyclic aglycones. Microencapsulation of the lead NeoTazMan in γ-cyclodextrin dramatically improved water solubility without disrupting the affinity for FimH or the anti-adhesive effect against AIEC isolated from patients with Crohn's disease.

Bacteriophages Targeting Adherent Invasive Escherichia coli Strains as a Promising New Treatment for Crohn's Disease.

BACKGROUND AND AIMS: Adherent invasive Escherichia coli [AIEC] are abnormally predominant on the ileal mucosa of Crohn's disease [CD] patients. They bind to the CEACAM6 receptor expressed on the surface of epithelial cells. We aimed to assess the potential of bacteriophages, viruses infecting bacteria, to decrease the levels of AIEC bacteria associated with the intestinal mucosa. METHODS: We combined ex vivo and in vivo experiments with murine and human intestinal samples to quantify the ability of virulent bacteriophages to target the prototype AIEC strain LF82. RESULTS: We found that three virulent bacteriophages were able to replicate in ileal, caecal and colonic sections and faeces homogenates from murine gut samples colonised with the prototype AIEC strain LF82. A single day of per os treatment with the three bacteriophages cocktail given to LF82-colonised CEABAC10 transgenic mice, expressing the human CEACAM6 receptor for AIEC, decreased significantly the number of AIEC in faeces and in the adherent flora of intestinal sections. In addition, a single dose of the cocktail reduced dextran sodium sulphate-induced colitis symptoms on conventional mice colonised with the strain LF82 over a 2-week period. The cocktail targeted also LF82 bacteria in homogenates of ileal biopsies taken from CD patients. CONCLUSIONS: These findings demonstrate that bacteriophages are a new treatment option for targeting AIEC in CD patients and represent a strong basis for a clinical trial evaluation.

Foodborne enterotoxigenic Escherichia coli: from gut pathogenesis to new preventive strategies involving probiotics.

Enterotoxigenic Escherichia coli (ETEC) are a major cause of traveler's diarrhea and infant mortality in developing countries. Given the rise of antibiotic resistance worldwide, there is an urgent need for the development of new preventive strategies. Among them, a promising approach is the use of probiotics. Although many studies, mostly performed under piglet digestive conditions, have shown the beneficial effects of probiotics on ETEC by interfering with their survival, virulence or adhesion to mucosa, underlying mechanisms remain unclear. This review describes ETEC pathogenesis, its modulation by human gastrointestinal cues as well as novel preventive strategies with a particular emphasis on probiotics. The potential of in vitro models simulating human digestion in elucidating probiotic mode of action will be discussed.

Differentiation of Crohn's Disease-Associated Isolates from Other Pathogenic Escherichia coli by Fimbrial Adhesion under Shear Force.

Shear force exerted on uropathogenic Escherichia coli adhering to surfaces makes type-1 fimbriae stretch out like springs to catch on to mannosidic receptors. This mechanism is initiated by a disruption of the quaternary interactions between the lectin and the pilin of the two-domain FimH adhesin and transduces allosterically to the mannose-binding pocket of FimH to increase its affinity. Mannose-specific adhesion of 14 E. coli pathovars was measured under flow, using surface plasmon resonance detection on functionalized graphene-coated gold interfaces. Increasing the shear had important differential consequences on bacterial adhesion. Adherent-invasive E. coli, isolated from the feces and biopsies of Crohn's disease patients, consistently changed their adhesion behavior less under shear and displayed lower SPR signals, compared to E. coli opportunistically infecting the urinary tract, intestines or loci of knee and hip prostheses. We exemplified this further with the extreme behaviors of the reference strains UTI89 and LF82. Whereas their FimA major pilins have identical sequences, FimH of LF82 E. coli is marked by the Thr158Pro mutation. Positioned in the inter-domain region known to carry hot spots of mutations in E. coli pathotypes, residue 158 is indicated to play a structural role in the allosteric regulation of type-1 fimbriae-mediated bacterial adhesion.

The Antiadhesive Strategy in Crohn's Disease: Orally Active Mannosides to Decolonize Pathogenic Escherichia coli from the Gut.

Blocking the adherence of bacteria to cells is an attractive complementary approach to current antibiotic treatments, which are faced with increasing resistance. This strategy has been particularly studied in the context of urinary tract infections (UTIs), in which the adhesion of pathogenic Escherichia coli strains to uroepithelial cells is prevented by blocking the FimH adhesin expressed at the tips of bacteria organelles called fimbriae. Recently, we extended the antiadhesive concept, showing that potent FimH antagonists can block the attachment of adherent-invasive E. coli (AIEC) colonizing the intestinal mucosa of patients with Crohn's disease (CD). In this work, we designed a small library of analogues of heptyl mannoside (HM), a previously identified nanomolar FimH inhibitor, but one that displays poor antiadhesive effects in vivo. The anomeric oxygen atom was replaced by a sulfur or a methylene group to prevent hydrolysis by intestinal glycosidases, and chemical groups were attached at the end of the alkyl tail. Importantly, a lead compound was shown to reduce AIEC levels in the feces and in the colonic and ileal mucosa after oral administration (10 mg kg(-1) ) in a transgenic mouse model of CD. The compound showed a low bioavailability, preferable in this instance, thus suggesting the possibility of setting up an innovative antiadhesive therapy, based on the water-soluble and non-cytotoxic FimH antagonists developed here, for the CD subpopulation in which AIEC plays a key role.

Development of Heptylmannoside-Based Glycoconjugate Antiadhesive Compounds against Adherent-Invasive Escherichia coli Bacteria Associated with Crohn's Disease.

UNLABELLED: The ileal lesions of Crohn's disease (CD) patients are colonized by adherent-invasive Escherichia coli (AIEC) bacteria. These bacteria adhere to mannose residues expressed by CEACAM6 on host cells in a type 1 pilus-dependent manner. In this study, we investigated different antagonists of FimH, the adhesin of type 1 pili, for their ability to block AIEC adhesion to intestinal epithelial cells (IEC). Monovalent and multivalent derivatives of n-heptyl α-d-mannoside (HM), a nanomolar antagonist of FimH, were tested in vitro in IEC infected with the AIEC LF82 strain and in vivo by oral administration to CEACAM6-expressing mice infected with LF82 bacteria. In vitro, multivalent derivatives were more potent than the monovalent derivatives, with a gain of efficacy superior to their valencies, probably owing to their ability to form bacterial aggregates. Of note, HM and the multi-HM glycoconjugates exhibited lower efficacy in vivo in decreasing LF82 gut colonization. Interestingly, HM analogues functionalized with an isopropylamide (1A-HM) or ß-cyclodextrin pharmacophore at the end of the heptyl tail (1CD-HM) exerted beneficial effects in vivo. These two compounds strongly decreased the amount of LF82 bacteria in the feces of mice and that of bacteria associated with the gut mucosa when administered orally at a dose of 10 mg/kg of body weight after infection. Importantly, signs of colitis and intestinal inflammation induced by LF82 infection were also prevented. These results highlight the potential of the antiadhesive compounds to treat CD patients abnormally colonized by AIEC bacteria and point to an alternative to the current approach focusing on blocking proinflammatory mediators. IMPORTANCE: Current treatments for Crohn's disease (CD), including immunosuppressive agents, anti-tumor necrosis factor alpha (anti-TNF-α) and anti-integrin antibodies, focus on the symptoms but not on the cause of the disease. Adherent-invasive Escherichia coli (AIEC) bacteria abnormally colonize the ileal mucosa of CD patients via the interaction of the mannose-specific adhesin FimH of type 1 pili with CEACAM6 mannosylated proteins expressed on the epithelial cell surface. Thus, we decided to develop an antiadhesive strategy based on synthetic FimH antagonists specifically targeting AIEC bacteria that would decrease intestinal inflammation. Heptylmannoside (HM)-based glycocompounds strongly inhibit AIEC adhesion to intestinal epithelial cells in vitro. The antiadhesive effect of two of these compounds of relatively simple chemical structure was also observed in vivo in AIEC-infected CEACAM6-expressing mice and was associated with a reduction in the signs of colitis. These results suggest a new therapeutic approach for CD patients colonized by AIEC bacteria, based on the development of synthetic FimH antagonists.