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ObjectiveIn the management of patients with IBD, there is a need to identify prognostic markers and druggable biological pathways to improve mucosal repair and probe the efficacy of tumour necrosis factor alpha biologics. Vnn1 is a pantetheinase that degrades pantetheine to pantothenate (vitamin B5, a precursor of coenzyme A (CoA) biosynthesis) and cysteamine. Vnn1 is overexpressed by inflamed colonocytes. We investigated its contribution to the tolerance of the intestinal mucosa to colitis-induced injury.DesignWe performed an RNA sequencing study on colon biopsy samples from patients with IBD stratified according to clinical severity and modalities of treatment. We generated the VIVA mouse transgenic model, which specifically overexpresses Vnn1 on intestinal epithelial cells and explored its susceptibility to colitis. We developed a pharmacological mimicry of Vnn1 overexpression by administration of Vnn1 derivatives.ResultsVNN1 overexpression on colonocytes correlates with IBD severity. VIVA mice are resistant to experimentally induced colitis. The pantetheinase activity of Vnn1 is cytoprotective in colon: it enhances CoA regeneration and metabolic adaptation of colonocytes; it favours microbiota-dependent production of short chain fatty acids and mostly butyrate, shown to regulate mucosal energetics and to be reduced in patients with IBD. This prohealing phenotype is recapitulated by treating control mice with the substrate (pantethine) or the products of pantetheinase activity prior to induction of colitis. In severe IBD, the protection conferred by the high induction of VNN1 might be compromised because its enzymatic activity may be limited by lack of available substrates. In addition, we identify the elevation of indoxyl sulfate in urine as a biomarker of Vnn1 overexpression, also detected in patients with IBD.ConclusionThe induction of Vnn1/VNN1 during colitis in mouse and human is a compensatory mechanism to reinforce the mucosal barrier. Therefore, enhancement of vitamin B5-driven metabolism should improve mucosal healing and might increase the efficacy of anti-inflammatory therapy.

Background and Aims NOD2 has emerged as a critical player in the induction of both Th1 and Th2 responses for potentiation and polarisation of antigen-dependent immunity. Loss-of-function mutations in the NOD2-encoding gene and deregulation of its downstream signalling pathway have been linked to Crohn’s disease. Although it is well documented that NOD2 is capable of sensing bacterial muramyl dipeptide, it remains counter-intuitive to link development of overt intestinal inflammation to a loss of bacterial-induced inflammatory response. We hypothesised that a T helper bias could also contribute to an autoimmune-like colitis different from inflammation that is fully fledged by Th1 type cells. Methods An oedematous bowel wall with a mixed Th1/Th2 response was induced in mice by intrarectal instillation of the haptenating agent oxazolone. Survival and clinical scoring were evaluated. At several time points after instillation, colonic damage was assessed by macroscopic and microscopic observations. To evaluate the involvement of NOD2 in immunochemical phenomena, quantitative polymerase chain reaction [PCR] and flow cytometry analysis were performed. Bone marrow chimera experimentation allowed us to evaluate the role of haematopoietic/non-hematopoietic NOD2-expressing cells. Results Herein, we identified a key regulatory circuit whereby NOD2-mediated sensing of a muramyl dipeptide [MDP] by radio-resistant cells improves colitis with a mixed Th1/Th2 response that is induced by oxazolone. Genetic ablation of either Nod2 or Ripk2 precipitated oxazolone colitis that is predominantly linked to a lack of interferon-gamma. Bone marrow chimera experiments revealed that inactivation of Nod2 signalling in non-haematopoietic cells is causing a biased M1-M2 polarisation of macrophages and a decreased frequency of splenic regulatory T cells that correlates with an impaired activation of CD4 + T cells within mesenteric lymph nodes. Mechanistically, mice were protected from oxazolone-induced colitis upon administration of MDP in an interleukin-1- and interleukin-23-dependent manner. Conclusions These findings indicate that Nod2 signalling may prevent pathological conversion of T helper cells for maintenance of tissue homeostasis.

Background & Aims Loss-of-function variants in nucleotide-binding oligomerization domain-containing protein 2 (NOD2) impair the recognition of the bacterial cell wall component muramyl-dipeptide and are associated with an increased risk for developing Crohn’s disease. Likewise, exposure to antibiotics increases the individual risk for developing inflammatory bowel disease. Here, we studied the long-term impact of NOD2 on the ability of the gut bacterial and fungal microbiota to recover after antibiotic treatment. Methods Two cohorts of 20-week-old and 52-week-old wild-type (WT) C57BL/6J and NOD2 knockout (Nod2-KO) mice were treated with broad-spectrum antibiotics and fecal samples were collected to investigate temporal dynamics of the intestinal microbiota (bacteria and fungi) using 16S ribosomal RNA and internal transcribed spacer 1 sequencing. In addition, 2 sets of germ-free WT mice were colonized with either WT or Nod2-KO after antibiotic donor microbiota and the severity of intestinal inflammation was monitored in the colonized mice. Results Antibiotic exposure caused long-term shifts in the bacterial and fungal community composition. Genetic ablation of NOD2 was associated with delayed body weight gain after antibiotic treatment and an impaired recovery of the bacterial gut microbiota. Transfer of the postantibiotic fecal microbiota of Nod2-KO mice induced an intestinal inflammatory response in the colons of germ-free recipient mice compared with respective microbiota from WT controls based on histopathology and gene expression analyses. Conclusions Our data show that the bacterial sensor NOD2 contributes to intestinal microbial community composition after antibiotic treatment and may add to the explanation of how defects in the NOD2 signaling pathway are involved in the etiology of Crohn’s disease., Graphical abstract

In a recently published letter,1 Dr Beaulieu questions our recent publication suggesting that α6 integrin acts as a tumour suppressor gene in colorectal cancer (CRC),2 given the apparent antagonistic role of α6A and α6B integrin isoforms in the intestine. We thank him for raising this important issue and welcome the opportunity of clarifying the topic. We showed that mice failing to express the α6 integrin (both α6A and α6B isoforms) specifically in intestinal epithelial cells (α6ΔIEC) spontaneously develop fully penetrant colitis and adenocarcinoma afterwards.2 These mice display epithelium detachment from the basement membrane, followed …

International audience; Background. Postoperative complications are relatively frequent in Crohn's disease (CD) and several risk factors have been identified. The influence of genetic factors, however is unknown.Methods. CD patients who underwent CD-related bowel resection were identified from the "Nancy IBD cohort." Postoperative complications were defined as intraabdominal infectious complications and non intraabdominal infectious complications occurring within 90 days after operation. The influence of 203 single nucleotide polymorphisms on postoperative complication rates was analyzed.Results. Of the 137 patients who had undergone a CD-related bowel resection in our cohort, postoperative complications occurred in 34 cases (24.8 %). Postoperative intraabdominal infections occurred in 18 cases (13. 1%): 12 had anastomotic leakage and 6 had intraabdominal abscesses. In multivariate analysis, current smoker status (odds ratio [OR], 2.71; 95% CI, 1.18-6.21; P =.02) and homozygosity for the risk allele (T) Nucleotide-binding Oligomerization Domain-containing protein 2 (rs5743289; NOD2; OR, 2.07 [95% CI 1.15-3.72]; P =.01) were independent risk factors of postoperative intraabdominal infectious complications. Current smoker status NOD2 homozygosity for the risk allele (T) were not associated with non intraabdominal infectious complications.Conclusion. Current smoker status was associated with increased risk of postoperative intraabdominal infectious complications. A novel association between the NOD2 allele and an increased risk of postoperative intraabdominal infectious, complications was observed in this study.

Background and aims Post-operative recurrence is frequent in Crohn's disease. Genetic factors associated with post-operative recurrence remain poorly understood. Identification of genetic variants associated with repeat surgery would allow risk stratification of patients who may benefit from early aggressive therapy and/or post-operative prophylactic treatment. Methods Crohn's disease patients who had at least one bowel resection were retrospectively identified from the “Nancy IBD cohort”. Covariates and potential interactions were assessed using the Cox proportional hazard model. Kaplan–Meier curves for time to surgical recurrence were developed for 200 genetic variants and analyzed with the log-rank test. Results 137 patients had at least 1 resection in our cohort: 38 had a surgical recurrence (28%). In multivariate analysis, current smoker status (OR 6.97, 95% CI 1.85–26.22, p = 0.004), post-operative complications after prior surgery (OR 2.72, 95% CI 1.02–7.22, p = 0.044), and Caspase recruitment domain-containing protein 8 (CARD8) homozygosity for the risk allele (OR 7.56, 95% CI 1.13–50.37, p = 0.036) remained significantly and independently associated with surgical recurrence. Conclusion Current smoker status was associated with increased risk of surgical recurrence. A novel association between CARD8 and increased risk of surgical recurrence in Crohn's disease was observed. CARD8 could be a new marker for risk stratification and prevention of recurrent surgery.

ObjectiveLoss of the Crohn’s disease predisposing NOD2 gene results in an intestinal microenvironment conducive for colonisation by attaching-and-effacing enteropathogens. However, it remains elusive whether it relies on the intracellular recruitment of the serine-threonine kinase RIPK2 by NOD2, a step that is required for its activation of the transcription factor NF-κB.DesignColonisation resistance was evaluated in wild type and mutant mice, as well as in ex-germ-free (ex-GF) mice which were colonised either with faeces from Ripk2-deficient mice or with bacteria with similar preferences for carbohydrates to those acquired by the pathogen. The severity of the mucosal pathology was quantified at several time points postinfection by using a previously established scoring. The community resilience in response to infection was evaluated by 16S ribosomal RNA gene sequence analysis. The control of pathogen virulence was evaluated by monitoring the secretion of Citrobacter-specific antibody response in the faeces.ResultsPrimary infection was similarly outcompeted in ex-GF Ripk2-deficient and control mice, demonstrating that the susceptibility to infection resulting from RIPK2 deficiency cannot be solely attributed to specific microbiota community structures. In contrast, delayed clearance of Citrobacter rodentium and exacerbated histopathology were preceded by a weakened propensity of intestinal macrophages to afford innate lymphoid cell activation. This tissue protection unexpectedly required the regenerating family member 3β by instigating interleukin (IL) 17A-mediated neutrophil recruitment to the intestine and subsequent phosphorylation of signal transducer and activator of transcription 3.ConclusionsThese results unveil a previously unrecognised mechanism that efficiently protects from colonisation by diarrhoeagenic bacteria early in infection.

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BACKGROUND & AIMS: The role of tobacco smoke in the etiology of inflammatory bowel disease (IBD) is unclear. We investigated interactions between genes and smoking (gene-smoking interactions) that affect risk for Crohn's disease (CD) and ulcerative colitis (UC) in a case-only study of patients and in mouse models of IBD.METHODS: We used 55 Immunochip-wide datasets that included 19,735 IBD cases (10,856 CD cases and 8879 UC cases) of known smoking status. We performed 3 meta-analyses each for CD, UC, and IBD (CD and UC combined), comparing data for never vs ever smokers, never vs current smokers, and never vs former smokers. We studied the effects of exposure to cigarette smoke in Il10(-/-) and Nod2(-/-) mice, as well as in Balb/c mice without disruption of these genes (wild-type mice). Mice were exposed to the smoke of 5 cigarettes per day, 5 days a week, for 8 weeks, in a ventilated smoking chamber, or ambient air (controls). Intestines were collected and analyzed histologically and by reverse transcription polymerase chain reaction.RESULTS: We identified 64 single nucleotide polymorphisms (SNPs) for which the association between the SNP and IBD were modified by smoking behavior (meta-analysis Wald test P < 5.0 × 10(-5); heterogeneity Cochrane Q test P > .05). Twenty of these variants were located within the HLA region at 6p21. Analysis of classical HLA alleles (imputed from SNP genotypes) revealed an interaction with smoking. We replicated the interaction of a variant in NOD2 with current smoking in relation to the risk for CD (frameshift variant fs1007insC; rs5743293). We identified 2 variants in the same genomic region (rs2270368 and rs17221417) that interact with smoking in relation to CD risk. Approximately 45% of the SNPs that interact with smoking were in close vicinity (≤1 Mb) to SNPs previously associated with IBD; many were located near or within genes that regulate mucosal barrier function and immune tolerance. Smoking modified the disease risk of some variants in opposite directions for CD vs UC. Exposure of Interleukin 10 (il10)-deficient mice to cigarette smoke accelerated development of colitis and increased expression of interferon gamma in the small intestine compared to wild-type mice exposed to smoke. NOD2-deficient mice exposed to cigarette smoke developed ileitis, characterized by increased expression of interferon gamma, compared to wild-type mice exposed to smoke.CONCLUSIONS: In an analysis of 55 Immunochip-wide datasets, we identified 64 SNPs whose association with risk for IBD is modified by tobacco smoking. Gene-smoking interactions were confirmed in mice with disruption of Il10 and Nod2-variants of these genes have been associated with risk for IBD. Our findings from mice and humans revealed that the effects of smoking on risk for IBD depend on genetic variants.

ObjectiveIn association with innate and adaptive immunity, the microbiota controls the colonisation resistance against intestinal pathogens. Caspase recruitment domain 9 (CARD9), a key innate immunity gene, is required to shape a normal gut microbiota. Card9–/– mice are more susceptible to the enteric mouse pathogen Citrobacter rodentium that mimics human infections with enteropathogenic and enterohaemorrhagic Escherichia coli. Here, we examined how CARD9 controls C. rodentium infection susceptibility through microbiota-dependent and microbiota-independent mechanisms.DesignC. rodentium infection was assessed in conventional and germ-free (GF) wild-type (WT) and Card9–/– mice. To explore the impact of Card9–/–microbiota in infection susceptibility, GF WT mice were colonised with WT (WT→GF) or Card9–/– (Card9–/–→GF) microbiota before C. rodentium infection. Microbiota composition was determined by 16S rDNA gene sequencing. Inflammation severity was determined by histology score and lipocalin level. Microbiota–host immune system interactions were assessed by quantitative PCR analysis.ResultsCARD9 controls pathogen virulence in a microbiota-independent manner by supporting a specific humoral response. Higher susceptibility to C. rodentium-induced colitis was observed in Card9–/–→GF mice. The microbiota of Card9–/– mice failed to outcompete the monosaccharide-consuming C. rodentium, worsening the infection severity. A polysaccharide-enriched diet counteracted the ecological advantage of C. rodentium and the defective pathogen-specific antibody response in Card9–/– mice.ConclusionsCARD9 modulates the susceptibility to intestinal infection by controlling the pathogen virulence in a microbiota-dependent and microbiota-independent manner. Genetic susceptibility to intestinal pathogens can be overridden by diet intervention that restores humoural immunity and a competing microbiota.

We read with great interest the article by Wu et al 1 showing that the impact of diet on the composition of the gut microbiota was milder than its impact on metabolites produced by the gut microbiota, in healthy humans. Enteral nutrition is an effective treatment to manage active Crohn's disease (CD) in children.2 CD is known to be associated with gut microbial dysbiosis that is characterised by decreased diversity and imbalances in the intestinal microbiome. Recent evidence indicates that exclusive enteral nutrition (EEN) may affect gut microbiota in children with CD,3 but it remains elusive whether the aforementioned changes may occur independently of disease flares. We thus studied the impact of either EEN with Modulen (EXCL-MOD) or partial enteral nutrition (PEN) with Modulen (MOD) IBD on the bacterial composition of the gut microbiota from children with CD during either remission or active phase. In this single-centre, prospective, observational cohort study, 34 children followed at Nancy University Children Hospital …

Although a causing viral infectious agent remains untraceable in Crohn's disease, most recent genome-wide association studies have linked the FUT2 W143X mutation (resulting in asymptomatic norovirus infection) with the pathogenesis of Crohn's ileitis and with vitamin B12 deficiency (i.e., a known risk factor for Crohn's disease with ileal involvement). In line with these findings, host variations in additional genes involved in host response to norovirus infection (such as ATG16L1 and NOD2) predispose humans to Crohn's ileitis. One may therefore presume that asymptomatic norovirus infection may contribute to disruption of the stability of the gut microbiota leading to Crohn's ileitis. These paradigms highlight not only the need to revisit the potential transmissibility of Crohn's disease, but also potential safety issues of forthcoming clinical trials on human probiotic infusions in Crohn's ileitis by rigorous donors screening program.

The peptide transporter PEPT1, expressed in the brush border membrane of enterocytes, mediates the uptake of di- and tripeptides from luminal protein digestion in the small intestine. PEPT1 was proposed not to be expressed in normal colonic mucosa but may become detectable in inflammatory states such as Crohn's disease or ulcerative colitis. We reassessed colonic expression of PEPT1 by performing a systematic analysis of PEPT1 mRNA and protein levels in healthy colonic tissues in mice, rats, and humans. Immunofluorescence analysis of different mouse strains (C57BL/6N, 129/Sv, BALB/c) demonstrated the presence of PEPT1 in the distal part of the colon but not in proximal colon. Rat and human intestines display a similar distribution of PEPT1 as found in mice. However, localization in human sigmoid colon revealed immunoreactivity present at low levels in apical membranes but substantial staining in distinct intracellular compartments. Functional activity of PEPT1 in colonic tissues from mice was assessed in everted sac preparations using [14C]Gly-Sar and found to be 5.7-fold higher in distal compared with proximal colon. In intestinal tissues from Pept1−/−mice, no [14C]Gly-Sar transport was detectable but feces samples revealed significantly higher water content than in wild-type mice, suggesting that PEPT1 contributes to colonic water absorption. In conclusion, our studies unequivocally demonstrate the presence of PEPT1 protein in healthy distal colonic epithelium in mice, rats, and humans and proved that the protein is functional and contributes to electrolyte and water handling in mice.

Objective Epidemiological and clinical data indicate that patients suffering from IBD with long-standing colitis display a higher risk to develop colorectal high-grade dysplasia. Whereas carcinoma invasion and metastasis rely on basement membrane (BM) disruption, experimental evidence is lacking regarding the potential contribution of epithelial cell/BM anchorage on inflammation onset and subsequent neoplastic transformation of inflammatory lesions. Herein, we analyse the role of the alpha 6 beta 4 integrin receptor found in hemidesmosomes that attach intestinal epithelial cells (IECs) to the laminin-containing BM. Design We developed new mouse models inducing IEC-specific ablation of alpha 6 integrin either during development (alpha 6(Delta IEC)) or in adults (alpha 6(Delta IEC-TAM)). Results Strikingly, all alpha 6(Delta IEC) mutant mice spontaneously developed long-standing colitis, which degenerated overtime into infiltrating adenocarcinoma. The sequence of events leading to disease onset entails hemidesmosome disruption, BM detachment, IL-18 overproduction by IECs, hyperplasia and enhanced intestinal permeability. Likewise, IEC-specific ablation of alpha 6 integrin induced in adult mice (alpha 6(Delta IEC-TAM)) resulted in fully penetrant colitis and tumour progression. Whereas broad-spectrum antibiotic treatment lowered tissue pathology and IL-1 beta secretion from infiltrating myeloid cells, it failed to reduce Th1 and Th17 response. Interestingly, while the initial intestinal inflammation occurred independently of the adaptive immune system, tumourigenesis required B and T lymphocyte activation. Conclusions We provide for the first time evidence that loss of IECs/BM interactions triggered by hemidesmosome disruption initiates the development of inflammatory lesions that progress into high-grade dysplasia and carcinoma. Colorectal neoplasia in our mouse models resemble that seen in patients with IBD, making them highly attractive for discovering more efficient therapies.

Aseptic abscesses syndrome (AA) is an inflammatory disease in which non-infectious deep abscesses develop; these respond quickly to corticosteroids. AA is associated with Crohn disease (CD) in 57% of cases and with neutrophilic dermatosis (ND) in 20%. Pyoderma gangrenosum is usually a sporadic ND. A hereditary autosomal dominant syndromic kind of pyoderma gangrenosum, the PAPA syndrome, is linked to mutations in the CD2BP1/PSTPIP1 gene. We systematically screened this gene in French AA patients. One microsatellite (CCTG)n with 3 alleles was identified in the promoter. The longest form (CCTG)7 was significantly more frequent in AA patients than in French controls (P = 0.0154). We also found an association of the (CCTG)7 allele with CD in French patients (P = 0.0351). This association was not found in a sample of Indian patients. The CCTG repeat in the PSTPIP1 promoter may play a role in the pathogenesis of AA and of CD. Further investigations are required to demonstrate the possible modulation of gene expression by the (CCTG)n motif.

OBJECTIVES: Anti- Saccharomyces cerevisiae antibodies (ASCAs) are present in 50 - 60 % of patients with Crohn ' s disease (CD) and in 20 - 25 % of their healthy relatives (HRs). The yeast, Candida albicans , has been shown to generate ASCAs, but the presence of C. albicans in the digestive tract of CD patients and their HRs has never been investigated. Therefore, we studied C. albicans carriage in familial CD and its correlation with ASCAs. METHODS: Study groups consisted of 41 CD families composed of 129 patients and 113 HRs, and 14 control families composed of 76 individuals. Mouth swabs and stool specimens were collected for isolation, identifi cation, and quantifi cation of yeasts. Serum samples were collected for detection of ASCAs and anti- C. albicans mannan antibodies (ACMAs). RESULTS: C. albicans was isolated signifi cantly more frequently from stool samples from CD patients (44 % ) and their HRs (38 % ) than from controls (22 % ) ( P < 0.05). The prevalence of ACMAs was similar between CD patients, their HRs, and controls (22, 19, and 21 % , respectively, P = 0.845), whereas the prevalence of ASCAs was signifi cantly increased in CD families (72 and 34 % in CD and HRs, respectively, in contrast to 4 % in controls, P < 0.0001). AMCA levels correlated with C. albicans colonization in all populations. ASCA levels correlated with C. albicans colonization in HRs but not in CD patients. CONCLUSIONS: CD patients and their fi rst-degree HRs are more frequently and more heavily colonized by C. albicans than are controls. ASCAs correlate with C. albicans colonization in HRs but not in CD. In HRs, ASCAs could result from an altered immune response to C. albicans . In CD, a subsequent alteration in sensing C. albicans colonization could occur with disease onset.

The etiology of Crohn's disease (CD) remains poorly understood. Both mice and human studies suspected a perverse link between the microbiota and the lining of the gut mucosa. There is now emerging evidence that suggests that such a pathologic condition might result from an overly aggressive immune response to microbial antigens in genetically predisposed individuals. However, the multiple pathophysiologic processing steps linking environmental exposure to the clinical expression of CD are, for the most part, unknown. Herein, we review evidences reflecting a general causing defect of the innate immune function of the intestinal mucosa of CD patients, which might lead to a sustained microbial-induced inflammatory response. Changing the paradigms of CD pathophysiology might lead to entirely new therapeutic approaches aiming to boost the innate immune response.

Beyond a defective innate immune response in inflammatory bowel disease (IBD), an increased immunological response toward microbial and self antigens has been intrinsically linked to the pathogenesis of such common immunopathologies of the gut. Mounting evidence indicates that increased seroreactivity toward certain antigens are a predictive and quantitative heritable trait, including the anti-Saccharomyces cerevisiae antibody (ASCA). Consistently, Candida albicans and Crohn's disease-associated NOD2 mutations have been recently identified as immunogen and genetic determinants for ASCA, respectively. In clinical practice, current panels of serological markers are not recommended for diagnosis, stratifying, and monitoring IBD. Therefore, prospective studies and highly sensitive serological panels of markers are eagerly awaited before guiding clinical decisions. Better understanding of the serological response in IBD might also provide new insights into their epidemiology and pathophysiology.

Moderate hyperhomocysteinemia is a complex trait commonly associated with inflammatory bowel disease (IBD). Nutritional deficiencies and genetic determinants have been identified as risk factors for moderate hyperhomocysteinemia, such as folate and vitamin B(12) deprivation and polymorphisms in the 5,10 methylenetetrahydrofolate reductase (MTHFR) encoding gene, respectively. Homocysteine has a crucial role in cellular stress, epigenetic events, inflammatory processes, and host-microbial interactions. Hyperhomocysteinemia might therefore influence the clinical history of IBD, including disease severity, susceptibility to particular enteric infections, and the risk for the development of colorectal cancer. In contrast, homocysteine metabolism does not seem to contribute to the greater risk of thrombosis in IBD subjects. Herein, we review the evidence linking homocysteine metabolism to the pathophysiology of IBD. Furthermore, we discuss the relevance of screening and treating folate and vitamin B(12) deficiencies in IBD subjects. Given the peculiar frequency of such deficiencies in IBD, normalizing vitamin levels should be an integral part of the management of these patients, especially those with active disease, history of intestinal resection, and/or treated with methotrexate.

Background Inflammatory bowel diseases are incurable illnesses of the gastrointestinal tract, which substantially enhance the risk of developing colorectal carcinogenesis. Conventional photodynamic therapy is a clinically approved therapeutic modality used in the treatment of neoplastic diseases. Recent preclinical and clinical studies have shown that photodynamic therapy with low doses of photosensitizer and/or light improves inflammatory conditions, including colitis. This study aims therefore at investigating the therapeutic potential of low-dose photodynamic therapy (LDPDT) with a liposomal formulation of meta-tetra(hydroxyphenyl)chlorin (namely Foslip) in the prevention of colitis-associated cancer in mice. Methods LDPDT efficacy was evaluated by endoscopic, macroscopic, and histological analysis. Myeloperoxidase levels were quantified by enzyme linked immunosorbent assay and cytokines expression by quantitative RT-PCR analysis. The integrity of the intestinal barrier was evaluated by immunostaining, and bacterial composition of the fecal microbiota was determined by 454 pyrosequencing of V3-V4 region of bacterial 16S rRNA genes. Results LDPDT reduced intestinal tumor growth by decreasing the expression of a wide range of inflammatory mediators and by lowering neutrophil influx. LDPDT treatment prevents onset of a dysbiotic microbiota in the colitis-associated cancer model. Conclusions LDPDT with Foslip could be considered as a novel treatment modality to prevent colorectal carcinogenesis in patients with inflammatory bowel disease.

It is becoming increasingly clear that the ‘one microbe-one disease’ paradigm must be reconsidered, because it fails to account for the pathogenesis of several common human illnesses with ever-increasing socioeconomic impacts (such as IBD). Notably, instability within the gut's microbial communities (referred to as dysbiosis) has been linked to loss of gut barrier function in IBD. In particular, IBDs are associated with a greater preponderance of certain Bacteroidetes and a lower abundance of Firmicutes. 1 ,2 Likewise, several targeted approaches in mice have revealed that the major Crohn's disease-predisposing NOD2 gene has a role in protecting against intestinal inflammation afforded by some Bacteroides spp (including B vulgatus ).3 ,4 Remarkably, reciprocal transplantation of faecal microbiota from Nod2 -deficient mice enhanced the vulnerability of control animals to colonic injury.3 In line with reverse genetic studies in mice, subclinical dysbiosis has been observed in healthy, first-degree relatives of patients with Crohn's disease.5 One can therefore reasonably presume that familial similarities in the microbiome are related to similar host genetic compositions.3 ,6 Consistently, twin studies have demonstrated that variations in the host genome may influence the structure and composition of the …

Background: Crohn’s disease is one of the principal human chronic inflammatory bowel diseases. Although its aetiology is still unknown, its complex pathogenesis has environmental, immunological, and genetic determinants. CARD15 is the first susceptibility gene implicated in the predisposition to Crohn’s disease and is known to be expressed only in monocytes. However, its expression in situ has not yet been studied. Aims: To analyse the tissue distribution of CARD15 and identify cells producing CARD15 in samples of colon from patients with Crohn’s disease and control subjects. Patients and methods: We analysed CARD15 gene expression in surgical specimens of colon from eight children with Crohn’s disease and nine controls by immunohistochemistry, in situ hybridisation, and reverse transcription-polymerase chain reaction (RT-PCR). Results: We showed that CARD15 was present only in the cytoplasm of macrophages in the normal colon. Increased CARD15 expression was detected in Crohn’s disease lesions. There were more CARD15 positive cells in Crohn’s disease lesions than in uninvolved areas. Both intestinal epithelial cells, macrophages, and their derivatives overproduced CARD15 in Crohn’s disease. To further assess CARD15 expression by intestinal epithelial cells, we performed RT-PCR on freshly isolated intestinal epithelial cells, and showed that these cells isolated from Crohn’s disease samples contained more CARD15 mRNA than intestinal epithelial cells from controls. Conclusions: We have demonstrated that colonic involvement in active Crohn’s disease is associated with increased CARD15 gene expression in both macrophages and intestinal epithelial cells. Therefore, this deregulation can affect the host-environment interaction and thus contribute to the pathogenesis of this disease.

PEPT1 was proposed to be expressed only in inflamed colonic tissues in which it could contribute to inflammatory bowel disease (IBD) development by transporting bacterial peptides, such as muramyl dipeptide (MDP), that activate intracellular pattern recognition receptors, such as the nucleotide-binding and oligomerization domain 2. To better define the pathological relevance of this transporter, we analyzed PEPT1 expression during intestinal inflammation and studied the susceptibility of Pept1-deficient (Pept1) mice to experimental colitis.Wild-type and Pept1 mice were treated with dextran sulfate sodium and 2,4,6-trinitrobenzene sulfonic acid to induce colitis, and MDP-induced cytokine expression was studied in colonic tissue cultures. PEPT1 expression was characterized in mouse models of Crohn's disease-like ileitis (Tnf) or colitis (Il-10, Il-10XTlr2) and endoscopic tissue samples from descending colon of patients with IBD (n = 11) and controls (n = 17). Moreover, the prevalence of the PEPT1 single-nucleotide polymorphism rs2297322 was tested in German patients with IBD (n = 458) and controls (n = 452).PEPT1 expression was consistently reduced under condition of acute or chronic experimental inflammation. Wild-type and Pept1 mice revealed comparable susceptibility to dextran sulfate sodium-induced and 2,4,6-trinitrobenzene sulfonic acid-induced colitis, and MDP-induced cytokine expression was PEPT1-independent. PEPT1 expression levels were also decreased in descending colon of patients with IBD during acute inflammation, but the rs2297322 single-nucleotide polymorphism was not associated with IBD susceptibility in the German cohort.PEPT1 expression is reduced during intestinal inflammation and PEPT1 is neither required for MDP-induced immune response nor is the PEPT1 rs2297322 single-nucleotide polymorphism associated with IBD susceptibility in our German cohort. These data strongly argue against a primary role of PEPT1 in the initiation or progression of IBD.

Background: The intestinal epithelium accommodates with a myriad of commensals to maintain immunological homeostasis, but the underlying mechanisms regulating epithelial responsiveness to flora-derived signals remain poorly understood. Herein, we sought to determine the role of the Toll/ interleukin (IL)-1 receptor regulator Toll-interacting protein (Tollip) in intestinal homeostasis. Methods: Colitis susceptibility was determined after oral dextran sulfate sodium (DSS) administration or by breeding Tollip-/- on an IL-10-/- background. The intestinal flora was depleted with 4 antibiotics before DSS exposure to assess its contribution in colitis onset. Bone marrow chimeras were generated to identify the cellular compartment, whereby Tollip may negatively regulate intestinal inflammation in response to DSS. Tollip-dependent epithelial barrier functions were studied in vitro by using Tollip-knockdown in Caco-2 cells and in vivo by immunohistochemistry and fluorescein isothiocyanate-labeled dextran gavage. Results: Genetic ablation of Tollip did not lead to spontaneous intestinal inflammatory disorders. However, Tollip deficiency aggravated spontaneous disease onset in IL-10-/- mice and increased susceptibility to DSS colitis. Increased colitis severity in Tollip-deficient mice was not improved by bacterial flora depletion using broad-spectrum antibiotics. In addition, DSS exposure of bone marrow chimeric mice revealed a protective role for Tollip in nonhematopoietic cells. Knockdown of Tollip in epithelial cells led to exaggerated NFκ-B activity and proinflammatory cytokine secretion. Finally, DSS-treated Tollip-/- mice showed enhanced intestinal permeability and increased epithelial apoptosis when compared with wild-type controls, a finding that coincided with tight junction alterations on injury. Conclusion: Overall, our data show an essential role for Tollip on colitis susceptibility in mice. Copyright © 2014 Crohn's and Colitis Foundation of America, Inc.

International audience; Objective Inflammatory bowel diseases (IBD) have been intrinsically linked to a deregulated cytokine network, but novel therapeutic principles are urgently needed. Here we identify the interleukin (IL)-33 and its receptor ST2 as key negative regulators of wound healing and permeability in the colon of mice.Design Expression of IL-33 and ST2 was determined by qRT-PCR, ELISA, immunohistochemistry and western-blot analysis. Wild-type and St2−/− mice were used in wound healing experiments and in two experimental models of IBD triggered by 2,4,6-trinitrobenzene sulphonic acid or dextran sodium sulphate (DSS). Neutralisation of ST2 was performed by using a specific blocking antibody.Results Nuclear localisation and enhanced expression of IL-33 in myofibroblasts and enterocytes was linked to disease involvement independently of inflammation, while the expression of ST2 was primarily restricted to the colonic epithelia. In two experimental models of IBD, genetic ablation of ST2 significantly improved signs of colitis, while a sustained epithelial expression of the cyto-protective factor connexin-43 was observed in DSS-treated St2-deficient mice. Unexpectedly, absence of ST2 in non-hematopoietic cells was sufficient to protect against colitis. Consistently, specific inhibition of endogenous ST2-mediated signalling by treatment with neutralising antibody improved DSS-induced colitis. In addition, IL-33 treatment impaired epithelial barrier permeability in vitro and in vivo, whereas absence of ST2 enhanced wound healing response upon acute mechanical injury in the colon.Conclusions Our study unveiled a novel non-hematopoietic function of IL-33 in epithelial barrier function and wound healing. Therefore, blocking the IL-33/ST2 axis may represent an efficient therapy in IBD.

International audience

BACKGROUND AND AIMS—Inflammatory bowel disease (IBD) includes ulcerative colitis and Crohn's disease, both of which are multifactorial diseases involving the interaction of genetic and environmental factors. A region on chromosome 12 centred around the marker locus D12S83 has previously been associated with IBD predisposition. The aim of the study was to investigate this genetic region in an independent panel of European families affected by Crohn's disease. METHODS—A sample of 95 families with two or more affected relatives and 75 simplex nuclear families were genotyped for 19 microsatellite loci located on chromosome 12. A search for linkage and linkage disequilibrium was performed using non-parametric two point and multipoint analyses with the Analyze and Genehunter packages. RESULTS—No evidence of linkage or linkage disequilibrium was observed for any of the marker loci, including D12S83 (p=0.35 for the two point linkage test). Multipoint linkage analysis also failed to reveal positive linkage on chromosome 12. Power calculations allowed us to reject the hypothesis that the genetic region of chromosome 12 centred on D12S83 contains a susceptibility locus with a relative risk (λs) equal to or greater than 2.0 in these families. CONCLUSION—Failure to detect linkage or linkage disequilibrium in these families suggests that the chromosome 12 locus previously reported to be associated with genetic predisposition to IBD does not play a role in all European family samples. This observation is compatible with heterogeneity in the genetic basis of susceptibility to the disease and/or exposure to various environmental factors among Caucasian families. Keywords: chromosome 12; inflammatory bowel disease; Crohn's disease; linkage analyses; replication study

Objectives Dysbiosis of the intestinal microbiota is associated with Crohn's disease (CD). Functional evidence for a causal role of bacteria in the development of chronic small intestinal inflammation is lacking. Similar to human pathology, TNFdeltaARE mice develop a tumour necrosis factor (TNF)-driven CD-like transmural inflammation with predominant ileal involvement. Design Heterozygous TNFdeltaARE mice and wildtype (WT) littermates were housed under conventional (CONV), specific pathogen-free (SPF) and germ-free (GF) conditions. Microbial communities were analysed by high-throughput 16S ribosomal RNA gene sequencing. Metaproteomes were measured using LC-MS. Temporal and spatial resolution of disease development was followed after antibiotic treatment and transfer of microbial communities into GF mice. Granulocyte infiltration and Paneth cell function was assessed by immunofluorescence and gene expression analysis. Results GF-TNFdeltaARE mice were free of inflammation in the gut and antibiotic treatment of CONV-TNFdeltaARE mice attenuated ileitis but not colitis, demonstrating that disease severity and location are microbiota-dependent. SPF-TNFdeltaARE mice developed distinct ileitis-phenotypes associated with gradual loss of antimicrobial defence. 16S analysis and metaproteomics revealed specific compositional and functional alterations of bacterial communities in inflamed mice. Transplantation of disease-associated but not healthy microbiota transmitted CD-like ileitis to GF-TNFdeltaARE recipients and triggered loss of lysozyme and cryptdin-2 expression. Monoassociation of GF-TNFdeltaARE mice with the human CD-related Escherichia coli LF82 did not induce ileitis. Conclusions We provide clear experimental evidence for the causal role of gut bacterial dysbiosis in the development of chronic ileal inflammation with subsequent failure of Paneth cell function.

International audience; The gut flora is composed of a huge number of diverse, well-adapted symbionts that interact with epithelial lining throughout the host's entire life. Not all commensals have the same ability to maintain quiescent, protective inflammation. Importantly, instability in the composition of gut microbial communities (referred to as dysbiosis) has been linked to loss of gut barrier in the context of common human illnesses with increasing socio-economic impacts, such as Crohn disease and colorectal cancer. Our recent findings suggest that disease-predisposing dysbiosis can now be intentionally manipulated by targeting the major Crohn disease-predisposing NOD2 gene. That knowledge will not only add a new dimension to the often overlooked microbiology of Crohn disease and colorectal cancer, but will also have a broad impact on biomedical sciences worldwide.

Ulcerative colitis (UC) is a chronic, disabling, progressive inflammatory bowel disease (IBD).1 The condition is associated with an increased risk of colorectal cancer and other serious structural and functional consequences in the long term,1 which include the development of colonic strictures, dysmotility, anorectal dysfunction and impaired permeability.1 In this context, mucosal healing has emerged as a new therapeutic goal in the prevention of the long-term complications of IBD.2 ,3 Indeed, a growing body of evidence indicates that mucosal healing improves the natural course of the disease by lowering the need for colectomy and thus reducing hospitalisation rates in these patients.3 Histological healing is considered as the ultimate marker of quiescent disease activity in UC4 and thus an improvement in the patient's quality of life. However, it is not yet known whether persistent gene expression changes in intestinal tissues are related to incomplete histological healing in asymptomatic UC. Planell et al 5 have attempted to identify a transcriptional signature associated with the involved mucosa in active/remitting UC patients (when …

Besides its role in repelling enteropathogenic infections, the gastrointestinal tract is in intimate contact with commensal microbiota. Tremendous advances have been made in determining the pivotal role of the microbiota, in both tissue homeostasis and metabolism, as well as in the initiation and maintenance of inflammatory lesions in inflammatory bowel diseases. A better understanding of human gut microbiota could provide innovative targets for treating and/or curing such common immunopathologies of the gastrointestinal tract. (C) 2009 Elsevier Masson SAS. All rights reserved.

Background: An increased risk of Crohn's disease (CD) has been reported consistently in first-degree relatives of patients. Our aim was to test whether a combination of CD-associated genes involved in innate immunity and/or antibody responses to microbial antigens may be valuable in identifying healthy relatives at risk. Methods: We investigated 86 families from Belgium and northern France, 45 with at least 3 first-degree relatives with CD, 24 with a single case, and 17 control families without inflammatory bowel disease (IBD). The cohort consisted of 186 CD patients, 290 healthy relatives, and 142 controls (total 618). Genetic (NOD2, NOD1, TLR4, CARD8) and serologic markers (ASCA, ACMA, ALCA, ACCA, AΣMA, OmpC, CBir1, I2) were determined in all subjects. All Belgian families were prospectively followed up for 54 months. Results: In multiple-affected families, an increment of affected first-degree relatives and of positive antibodies were additive risks factors for CD (P < 0.0001), independent of NOD2 mutations. When comparing subjects from multiple-affected families, having 3 additional first-degree relatives with CD and 1 additional positive antibody increased the odds for CD to 9.19 (95% confidence interval [CI]: 4.07–20.80). After a follow-up of 54 months among all Belgian families, a total of 4 new diagnoses of IBD were confirmed in the multiple-affected families only, resulting in a 57-fold increase in incidence within multiple-affected families compared to the known incidence of IBD in our region. Conclusions: We found an additive risk increment for CD in subjects from multicase families per additional affected relative and per additional positive antibody, independent of NOD2. Furthermore, a very high disease incidence was observed in these multiple-affected families. Inflamm Bowel Dis 2010

International audience; OBJECTIVE: Yersinia pseudotuberculosis causes ileitis and mesenteric lymphadenitis by mainly invading the Peyer's patches that are positioned in the terminal ileum. Whereas toll-like-receptor 2 (TLR2) controls mucosal inflammation by detecting certain microbiota-derived signals, its exact role in protecting Peyer's patches against bacterial invasion has not been defined. DESIGN: Wild-type, Tlr2-, Nod2- and MyD88-deficient animals were challenged by Y pseudotuberculosis via the oral or systemic route. The role of microbiota in conditioning Peyer's patches against Yersinia through TLR2 was assessed by delivering, ad libitum, exogenous TLR2 agonists in drinking water to germ-free and streptomycin-treated animals. Bacterial eradication from Peyer's patches was measured by using a colony-forming unit assay. Expression of cryptdins and the c-type lectin Reg3 beta was quantified by quantitative reverse transcriptase polymerase chain reaction analysis. RESULTS: Our data demonstrated that Tlr2-deficient mice failed to limit Yersinia dissemination from the Peyer's patches and succumbed to sepsis independently of nucleotide-binding and oligomerisation domain 2 (NOD2). Recognition of both microbiota-derived and myeloid differentiation factor 88 (MyD88)-mediated elicitors was found to be critically involved in gut protection against Yersinia-induced lethality, while TLR2 was dispensable to systemic Yersinia infection. Gene expression analyses revealed that optimal epithelial transcript level of the anti-infective Reg3 beta requires TLR2 activation. Consistently, Yersinia infection triggered TLR2-dependent Reg3 beta expression in Peyer's patches. Importantly, oral treatment with exogenous TLR2 agonists in germ-free animals was able to further enhance Yersinia-induced expression of Reg3 beta and to restore intestinal resistance to Yersinia. Lastly, genetic ablation of Reg3 beta resulted in impaired clearance of the bacterial load in Peyer's patches. CONCLUSIONS: TLR2/REG3 beta is thus an essential component in conditioning epithelial defence signalling pathways against bacterial invasion.

International audience; OBJECTIVES: Anti-S. cerevisiae mannan antibodies (ASCA) are human antibodies associated with Crohn's disease (CD) reacting with Saccharomyces cerevisiae (S. cerevisiae) mannan polymer. As mannan is a complex and variable repertoire of oligomannoses acting as epitopes, we chemically synthesized (Sigma) two major oligomannose epitopes, Man alpha-1,3 Man alpha-1,2 Man (SigmaMan3) and Man alpha-1,3 Man alpha-1,2 Man alpha-1,2 Man (SigmaMan4), and then explored how antisynthetic mannoside antibodies (ASigmaMA) compare with ASCA as markers of CD. METHODS: The study involved different cohorts of CD and ulcerative colitis (UC) patients and healthy controls who had been studied previously in several medical centers in Europe, the United States, and North Africa to determine the clinical value of ASCA in terms of differential diagnosis, evolution of indeterminate colitis (IC), and serotype-phenotype correlations. The comparison of ASigmaMA and ASCA included a total of 1,365 subjects: 772 CD, 261 UC, 43 IC, and 289 controls. RESULTS: The specificity of ASigmaMA was similar to that of ASCA (89% vs 93%), although the sensitivity was lower (38% vs 55%). Unexpectedly, 24% of the CD patients who were negative for ASCA and/or other CD-associated serologic markers were positive for ASigmaMA. ASigmaMA were associated with colonic involvement in CD (odds ratio [OR] 1.609, 95% confidence interval [CI] 1.033-2.506, P = 0.03) and were 100% predictive of CD in patients with IC. CONCLUSIONS: ASigmaMA reveal the heterogeneity of the antioligomannose antibody response in CD patients and increase the sensitivity of CD diagnosis when combined with ASCA. The subset of ASCA-negative CD patients diagnosed by ASigmaMA had preferentially a colonic involvement, which confirms the high predictive value of ASigmaMA for determining IC evolution toward CD.

Background & Aims: The low calcium response V (LcrV) protein synthesized by gram-negative, pathogenic yersiniae participates in bacterial evasion of the host's innate immune response by stimulating synthesis of the anti-inflammatory interleukin (IL)-10 and preventing the activation of proinflammatory cytokines. Methods: We genetically engineered the food-grade bacterium Lactococcus lactis to secrete the LcrV protein from the enteropathogenic species Yersinia pseudotuberculosis . The protective and therapeutic potential of orally administered LcrV-secreting L lactis was evaluated in 2 models of acute experimental colitis (induced by trinitrobenzene sulfonic acid [TNBS] and dextran sodium sulfate [DSS], respectively) in wild-type and knockout mice. Results: Oral administration of LcrV-secreting L lactis led to active delivery of LcrV and induction of IL-10 (via a Toll-like receptor 2–dependent pathway) in the colon and prevented TNBS-induced colitis, in contrast to the L lactis control not producing LcrV. Down-regulation of tissue inflammatory markers correlated well with the reduction in damage to the colonic mucosa. In contrast, TNBS-induced colitis was not prevented in IL-10 −/− mice pretreated with LcrV-secreting L lactis , thus showing that IL-10 is required for LcrV protection. Administration of LcrV-secreting L lactis also proved to be very effective in preventing and treating acute DSS-induced colitis. Conclusions: LcrV-secreting L lactis decreased experimentally induced intestinal inflammation in 2 murine models of colitis. This novel approach highlights the potential of using pathogen-derived immunomodulating molecules in vivo as novel therapeutics for inflammatory bowel diseases.

The peroxisome proliferator activated receptor γ (PPARγ) is a nuclear receptor highly expressed in the colon and playing a key role in bacterial induced inflammation. Regulation of colon inflammation by this receptor has been well demonstrated in many experimental models of colitis but also in patients with ulcerative colitis, characterised by impaired expression of PPARγ confined to their colon epithelial cells. Recent data showing that PPARγ was the major functional receptor mediating the common aminosalicylate activities in inflammatory bowel diseases (IBD) have also reinforced the roles of this receptor in the control of intestinal inflammation. The aims of this review are to discuss the potential roles of PPARγ in the physiopathology of IBD, as well as the emerging therapeutic strategies targeting this receptor. Current evidence suggests that Crohn’s disease (CD) and ulcerative colitis (UC) result from a complex interplay between genetic and environmental factors, leading to an abnormal innate and adaptive immune response of the gut directed against luminal constituents in genetically determined patients. Identification of cytoplasmic receptors of bacterial peptidoglycan, namely nucleotide oligomerisation domain (NOD)2/caspase recruitment domain (CARD)15 and NOD1/CARD4, as CD susceptibility genes reinforced the pivotal role of the interactions between enteric microbes and the intestinal immune system in the physiopathology of IBD.1–3 Furthermore, recent advances in our laboratory and others also indicate the involvement of another key receptor, PPARγ, which regulates colon inflammation. This represents a new target in the development of therapeutic molecules in IBD. PPARγ is a nuclear receptor discovered in mammals in 1993 as an orphan receptor.4 Until recently, PPARγ was known as a receptor mainly expressed by adipose tissue and involved in the regulation of insulin resistance. PPARγ is activated by antidiabetic thiazolidinedione drugs.5 In 1998, the first studies were published reporting a potential link between this receptor and …

Several clinical and biological phenotypes define complex diseases such as inflammatory bowel disease (IBD). There is a critical role of the caspase recruitment domain protein 15/nucleotide-binding oligomerization protein 2–dependent (CARD15-NOD2) sensing of bacterial cell wall components in health and disease. The current etiologic model for IBD emphasizes an interaction between susceptibility and modifier genes along with environmental factors. Together, these lead to disease progression. However, further work should clarify the pathophysiological mechanisms leading to IBD and how innate immune signaling confers susceptibility to intestinal inflammation. This is a prerequisite for rational clinical management of IBD. Genetic, functional, serologic testing and development of therapeutics in IBD are discussed.

Background and aims: Inflammatory bowel diseases (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are complex genetic disorders. CARD15/NOD2, a member of the Ced4 superfamily which includes Apaf-1 and CARD4/NOD1, has recently been associated with genetic predisposition to CD but additional genetic factors remain to be identified. Because CARD4/NOD1 shares many structural and functional similarities with CARD15, we tested its putative role in IBD. Patients and methods: The 11 exons of CARD4 were screened for the presence of variants in 63 unrelated IBD patients. The only non-private genetic variation encoding for a substitution in the peptidic chain was genotyped in 381 IBD families (235 CD, 58 UC, 81 mixed, and seven indeterminate colitis families) using a polymerase chain reaction-restriction fragment length polymorphism procedure. Genotyping data were analysed by the transmission disequilibrium test. Results: Five of nine sequence variations identified in the coding sequence of the gene encoded for non-conservative changes (E266K, D372N, R705Q, T787M, and T787K). Four were present in only one family. The remaining variant (E266K), which exhibited an allele frequency of 0.28, was not associated with CD, UC, or IBD. Furthermore, IBD patients carrying sequence variations in their CARD4 gene had a similar phenotype to those with a normal sequence. Conclusion: Our results suggest that CARD4 does not play a major role in genetic susceptibility to IBD.

BackgroundThe pancreatitis-associated protein (PAP) is increased in the serum of active inflammatory bowel disease (IBD) patients and its levels seem to be correlated with disease activity. Our aim was to evaluate the usefulness of serum and fecal PAP measurements to predict relapse in patients with inactive IBD.Materials and methodsWe undertook a 12-month prospective study that included 66 Crohn's disease (CD) and 74 ulcerative colitis (UC) patients. At inclusion, patients were in clinical remission, defined by a Harvey-Bradshaw (HB) Index≤4 (CD) or a partial Mayo Score (MS)ResultsActive CD patients had an increased mean serum PAP at the diagnosis of the flare (104.1 ng/ml) and 3 months prior to activity (22.68 ng/ml) compared with patients in remission (13.26 ng/ml), pConclusionSerum PAP is increased only in active CD patients, but this marker does not predict disease activity. Inactive UC patients have marked low levels of PAP in fecal samples compared with CD patients.

Antimicrobial peptides, including defensins, are essential effectors in host defence and in the maintenance of immune homeostasis. Clinical studies have linked the defective expression of both α- and β-defensin to the reduced killing of certain microorganisms by the intestinal mucosa of patients suffering from ileal and colonic Crohn’s disease (CD), respectively. Only recently have the events leading to defective expression of defensins in CD been further elucidated, and are discussed herein. These events may account for CD-associated alterations in the microbiome and may subsequently precipitate the development of granulomatous inflammatory lesions in genetically-predisposed patients. We also address how these discoveries may pave the way for the development of a molecular medicine aimed at restoring gut barrier function in CD.

Background and aims: Ulcerative colitis (UC) is chronic relapsing-remitting disease. Whereas it has been well characterized how various drug induce remission, the mechanisms involved in relapse are not known. We have previously shown that the epithelial expression of SOCS3, a negative regulator of cytokine signaling, was persistently upregulated in both active and inactive UC. Since the expression of SOCS3 during inactive disease may make the epithelial cells more vulnerable to various insults, we investigated whether this expression during remission was associated with the time till relapse. Materials and methods: 41 chronic UC patients in clinical remission underwent a first surveillance colonoscopy between 20012004, and were followed up till 2010. Biopsies from the first surveillance colonoscopy after remission were stained for SOCS3 protein expression and scored according to percentage of positive epithelial cells. Only biopsies from patients with clinical remission and without signs of histological inflammation were included. Clinical data, endoscopy and histology reviews were collected from patient charts. Results: 23 Patients (57.0%) of the 41 chronic UC patients developed histological relapse, and 19 patients (46.3%) had endoscopic relapse of colitis during the course of surveillance. SOCS3 protein expression in colon biopsies of inactive UC patients had a negative correlation with the time till histological (p