Development Of IBD Research Articles

Pre- and Perinatal Factors Predicting Inflammatory Bowel Disease: A Population-Based Study with Fifty Years of Follow-Up.

Pre- and perinatal events may be associated with an increased risk of inflammatory bowel disease [IBD]. We aimed to investigate the role of pre- and perinatal factors as potential risk factors for the development of IBD in a population with a follow-up of 50years. We conducted a nested case-control study, reporting IBD incidence among individuals born in 1964-76, for whom pre- and perinatal exposures were reported as part of the Jerusalem Perinatal Study [JPS], by linking them to the database of the epidemiology group of the Israeli IBD Research Nucleus [epi-IIRN], including all IBD patients in Israel since 2005 and their matched controls. We identified 2789 individuals within the epi-IIRN cohort who were also included in the JPS cohort [n=90079]: 746 IBD patients (405 with Crohn's disease [CD] and 341 with ulcerative colitis [UC]) and 2043 non-IBD controls. Those with a 'Non-western' family origin had decreased odds of developing CD and UC. High socioeconomic status was associated with CD but not UC. Low birth weight [≤2500g] occurred less frequently in IBD cases compared to controls, especially in UC patients, showing a protective effect. Being the first born was associated with CD, and having older siblings lowered the odds of developing CD, decreasing 7% with each additional sibling. Smoking and breastfeeding data were available for a subset of individuals, but neither was associated with IBD development. This population-based study identifies several pre- and perinatal variables as predictors of IBD development. This information may be helpful to facilitate implementation of early diagnosis interventions and family follow-up protocols.

DOP06 Antibiotics as a risk factor for older onset IBD: A population-based cohort study

Abstract Background Older adults are the fastest growing subpopulation of patients with IBD, with approximately 15% diagnosed after 60 years-of-age. Moreover, environmental exposures are thought to play a significant role in the development of older-onset IBD, given the lower genetic risk. Antibiotics have been associated with development of IBD in earlier generations, but the impact on IBD risk in older adults is uncertain. In this population-based cohort study, we assessed the impact of cumulative antibiotic use, the timing of antibiotic use, and the association between specific antibiotic classes and the development of older-onset IBD. Methods Using Denmark nationwide registries, a cohort of residents ≥60 years-of-age was established between 2000–2018. Information on exposure to antibiotics was retrieved from the Danish National Prescription Register. The number of courses of antibiotics (overall and specific classes) was considered a time-varying variable. The outcome, IBD, was identified based on ICD-10 codes in the Danish National Patient Register. Incidence rate ratios (IRRs) for IBD according to antibiotic use 1 to 5 years prior to IBD diagnosis were calculated by log-linear Poisson regression, and adjusted for age, sex, and calendar period. Results There were a total of 2,327,796 individuals aged 60 to 90 years included in the cohort, resulting in 22,670,484 person-years of follow-up. There were 10,773 new cases of ulcerative colitis (UC) and 3,825 new cases of Crohn’s disease (CD). Overall, any antibiotic use was associated with an IRR for the development of IBD (IRR 1.64, 95%CI 1.58–1.71), with a positive dose response observed (1 course of antibiotics IRR 1.27 95%CI 1.21–1.33; 2 courses IRR 1.54 95%CI 1.46–1.63; 3 courses IRR 1.66 95%CI 1.67–1.77; 4 courses IRR 1.96 95%CI 1.83–2.09; 5+ courses IRR 2.35, 95%CI 2.24–2.47). A higher IRR was noted between the timeframe of 1–2 years before diagnosis (IRR 1.87, 95%CI 1.79–1.94) as compared to 2–5 years before diagnosis (IRR 1.42, 95%CI 1.36–1.48). Additionally, all antibiotic classes were associated with the development of IBD, including those not used to treat gastrointestinal infections. Antibiotics with the highest IRR were fluoroquinolones (IRR 2.27, 95%CI 2.08–2.48), nitroimidazoles (IRR 2.21, 95%CI 1.95–2.50), and macrolides (IRR 1.74, 95%CI 1.64–1.84). All results remained statistically significant when stratifying by UC and CD, with effect estimates slightly higher for CD as compared to UC. Conclusion Use of antibiotics, regardless of class studied, was associated with an increased risk of older-onset IBD. This risk was highest one to two years prior to diagnosis, but persisted even prior to that, suggesting a link between overall antibiotic use and development of older-onset IBD.

P085 Paneth cells translate dietary lipid exposure into gut inflammation

Abstract Background Dietary constituents impact the development and course of IBD (1). Especially a Western style diet is associated with an increased incidence and prevalence of IBD (2). The role of polyunsaturated fatty acids (PUFA) in the development of IBD is broadly discussed. Recently we could show that PUFAs elicit a pro-inflammatory response in intestinal epithelial cells (IEC) in a Glutathione peroxidase 4 (GPX4) deficient setting, which resembled phenotypic hallmarks of human CD (3). GPX4, an anti-oxidative enzyme, was described to be a risk gene for the development of CD (4) and is deficient in IECs derived from inflamed areas of the small intestine of CD patients (3). Stress responses in Paneth cells (PC) trigger small intestinal gut inflammation (5). In this study, we describe PC as originators of GPX4-restricted and PUFA-induced intestinal inflammation. Methods We analyzed PC morphology in mice lacking one allele of GPX4 specifically in IECs (GPX4+/-IEC) by electron microscopy. We generated mice lacking both alleles of Gpx4 specifically in PC (GPX4ΔPC) and exposed these mice (and wildtype controls) to a Western diet enriched with PUFAs for 12 weeks. Intestinal inflammation was assessed by histology and immunohistochemistry. Further we analyzed small intestinal whole tissue cultures and evaluated cytokine production by ELISA. Results Paneth cells of mice lacking one allele of Gpx4 showed morphological signs of ER-stress at baseline and after exposure to a PUFA-WD for 12 weeks when compared to WT mice (Fig 1a). Based on these results, we dissected a role for PC in GPX4-restricted gut inflammation. When fed a PUFA WD for 12 weeks GPX4ΔPC mice developed a CD like enteritis while WT controls did not (Fig 1b). A WD did not induce this inflammatory response in GPX4ΔPC or WT mice. The infiltrating leukocytes contained mainly neutrophils and macrophages (indicated by positive F4/80 staining, Fib 1c). Whole tissue cultures derived from GPX4ΔPC mice fed a PUFA WD produced more Interleukin-6 and CXCL-1, the murine homologue of the human Interleukin-8, compared to whole tissue cultures derived from WT mice fed the same diet (Fig 2). Figure legend 1a) % of PC showing massive, medium or no ER dilatation 1b&c) enteritis score and representative H&E and F4/80 staining 2) IL-6 and CXCL-1 in supernatant of whole tissue jejunal samples Conclusion The presented data identify Paneth cells to be crucially involved in the development of PUFA induced enteritis in genetically susceptible hosts.

P245 Dynemics of the Immune-transcriptome and Microbiome in Paediatric Inflammatory Bowel Disease

Abstract Background Inflammatory Bowel Disease (IBD), including Crohn’s disease (CD), ulcerative colitis (UC) and IBD unclassified (IBDU) is characterized by a chronic relapsing inflammation of the gastrointestinal tract, resulting from the complex interplay between genetic make-up, microbiome, environmental factors, and immune response. The potential role of the immune response and microbiome in the development and progression of IBD has been extensively studied, however, markers that can predict disease relapse remain scarce, especially in children with IBD. Developing non-invasive monitoring tools are also extremely needed in the field. Methods Multi-omics analysis provides a global view of changes in immune, microbial, and environmental factors. In this study, we enrolled a total of 85 IBD patients and 57 matching controls living in Qatar and attending Sidra Medicine IBD clinic. Patients were followed- up every 3 months and when they felt unwell. In addition to the phenotypic and clinical data, saliva, blood, and stool samples were collected at each visit. Salivary and gut microbiome analysis was performed using high throughput 16S rRNA gene sequencing. Blood samples were stimulated with a total of 14 ligands before being processed for immune transcriptomics and proteomics. Patients were compared to their matching healthy controls. Results Reduced microbial diversity and increased variability in the microbiome composition was observed in both CD and UC patients compared with controls. Our preliminary data show that Bacteroidetes, Firmicutes, Actinobacteria and Proteobacteria are the common phyla present in both patients and controls. Interestingly, the longitudinal microbiome analysis revealed reduced temporal microbial stability in both CD and UC patients, particularly in patients with changes in disease activity. The microbiome composition of patients in remission appeared similar to healthy controls, whereas dysbiosis was mostly observed in patients with increased disease activity. We then characterized the spectrum of transcriptional responses in blood collected from healthy controls and IBD patients stimulated for 6 hours with 14 ligands. Blood transcriptomics analysis separated patients from controls and a clear clustering was observed when the same patient was in relapse or remission. We aim to identify microbial and immune signatures that can classify patients CD, UC and IBD-U and predict onset of both remission and relapse. Conclusion This is the first paediatric data to show that, by integrating various multi-omics datasets collected from CD, UC and IBD-U patients and comparing their profiles with their matching controls, we are able to identify specific non-invasive predictive markers for disease remission and relapse.

N19 Improving the standard of care for patients with IBD - translating the N-ECCO Consensus Statements

Abstract Background In 2018 the Second N-ECCO Consensus Statements were published in JCC and presented at the ECCO Congress. The statements aim to show the ‘ideal’ standard of care for patients with IBD and support IBD nursing practice. The statements comprise several sections: Fundamental IBD Nursing, Advanced IBD Nursing, and The benefit of an IBD Nurse. The Statements are presented in English and are available via the ECCO webpage. In order to raise awareness of the Statements and allow the Statements to be used in IBD nursing practice in Denmark, we aimed to translate the statements and to evaluate how the translated version were used. Methods Translation of statements into Danish by a physician who also is a journalist. Supported by the last author of the Statements (Bager). Distribution of the Statements to the Danish Community of IBD nurses. Open e-survey asking IBD nurses about the Danish version. Results Translation were done in autumn 2020. Promotion and distribution were done in spring 2021. This included 2 video recordings explaining the aim of the statements and how they could be used. Furthermore, the statements became online via our national organisation for IBD-nurses. The survey was launched in autumn 2021. As of November 22th. 2021, 16 nurses from across Denmark have responded. A large majority knew about the Danish version and aimed to use the Statements. However, implementation of the statements was delayed due to the covid-pandemic and a 10 weeks long strike among nurses in the summer of 2021. Furthermore, the responders highlighted the statements of most clinical importance. The top 5 most important statements were; 1) Fundamental IBD Nursing, 2) Impact of IBD on patients’ lives, 3) The Advanced IBD Nurse caring for complex patients, 4) The Advanced IBD Nursing assessment, and 5) Patient information and education. Conclusion Translation of the Second N-ECCO Consensus Statements into Danish was appreciated by IBD nurses in Denmark. A majority aimed to include the statements in the development of IBD nursing in clinical practice.

Western and Carnivorous Dietary Patterns are Associated with Greater Likelihood of IBD Development in a Large Prospective Population-based Cohort.

ObjectiveNutrition plays a role in the development of Crohn’s disease [CD] and ulcerative colitis [UC]. However, prospective data on nutrition and disease onset are limited. Here, we analysed dietary patterns and scores in relation to inflammatory bowel disease [IBD] development in a prospective population-based cohort.MethodsWe analysed 125 445 participants of whom 224 individuals developed de novo UC and 97 CD over a maximum 14-year follow-up period. Participants answered health-related [also prospectively] and dietary questionnaires [FFQ] at baseline. Principal component analysis [PCA] was conducted deriving a-posteriori dietary patterns. Hypotheses-based a-priori dietary scores were also calculated, including the protein score, Healthy Eating Index, LifeLines Diet Score [LLDS], and alternative Mediterranean Diet Score. Logistic regression models were performed between dietary patterns, scores, and IBD development.ResultsPCA identified five dietary patterns. A pattern characterised by high intake of snacks, prepared meals, non-alcoholic beverages, and sauces along with low vegetables and fruit consumption was associated with higher likelihood of CD development (odds ratio [OR]: 1.16, 95% confidence interval [CI]: 1.03-1.30, p = 0.013). A pattern comprising red meat, poultry, and processed meat, was associated with increased likelihood of UC development [OR: 1.11, 95% CI: 1.01-1.20, p = 0.023]. A high diet quality score [LLDS] was associated with decreased risk of CD [OR: 0.95, 95% CI: 0.92-0.99, p = 0.009].ConclusionsA Western dietary pattern was associated with a greater likelihood of CD development and a carnivorous pattern with UC development, whereas a relatively high diet quality [LLDS] was protective for CD development. Our study strengthens the importance of evaluating dietary patterns to aid prevention of IBD in the general population.

Genetic association study of NOD2 and IL23R amino acid substitution polymorphisms in Saudi Inflammatory Bowel Disease patients

BackgroundInflammatory Bowel Disease (IBD) is a complex autoimmune disease whose genetic basis is not well explored in the highly consanguineous Saudi population. Therefore, this study aims to evaluate the relevance of NOD2 and IL23R genes polymorphisms, selected from Caucasian Genome-wide association study (GWAS) findings, as risk markers for IBD pathology in Saudi patients. Materials and MethodsThe genetic status of NOD2 and IL23R polymorphisms of 97 IBD patients and 100 healthy individuals was determined through real-time PCR based TaqMan Allelic Discrimination Assay. Genotype calls of TaqMan assay were further validated by the direct DNA sequencing method. The pathogenicity of the variants was further explored by computational predictions and by 3D structural modelling methods. ResultsOur study found no evidence for a significant association of Caucasian IBD risk alleles, i.e., NOD2 (P268S and R702W) and IL23R (G149R and R381Q) with IBD pathology in Saudi Arabian patients under dominant, recessive or co-dominant genetic models. Moreover, SNP-SNP interaction analysis with multidimensionality reduction assays have also confirmed the above findings. Our computational predictions of the variants suggest the variable deleterious nature and minor structural drifts on the tertiary protein structures. ConclusionThis study expands the genetic heterogeneity of IBD and concludes that Caucasian genetic risk markers have limited or of no use in estimating the risk of IBD development in Saudi patients. Future genetic association studies in Saudi Arabia need to employ genetic markers whose minor allele frequencies exceed 10% in Arab population to have robust outcomes.

Acute Gastroenteritis in the Etiology of Inflammatory Bowel Disease: Systematic Review and Meta-analysis.

Inflammatory bowel disease (IBD) consists of a spectrum of disorders including ulcerative colitis and Crohn's disease, with a rising incidence worldwide. However, despite this prevalence the etiology of IBD remains uncertain. It has been suggested that an episode of gastroenteritis may precipitate IBD. Studies were identified using a literature search of Pubmed/Medline and Embase/Ovid. This review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The primary outcome was incidence of new-onset IBD after gastroenteritis. Secondary outcomes included incidence of IBD after bacterial, viral, and parasitic gastrointestinal infections. Eleven studies (n = 923 608 patients) were included. Four studies assessed patients with gastroenteritis, subsequently developing IBD as the primary outcome. Patients with gastroenteritis had a higher incidence of subsequent IBD but this did not reach statistical significance (odds ratio [OR] 3.81, 95% CI 0.52-27.85, P = .19). Seven studies examined the incidence of antecedent gastroenteritis (primary outcome) in patients with a confirmed diagnosis of IBD, compared to the controlled population. There was no difference between incidence of antecedent gastroenteritis across the 2 population groups (OR 1.07, 95% CI 0.55-2.08, P = .85). There was no association between IBD and bacterial, viral, or parasitic infections. In summary, our meta-analysis has shown that there is considerable heterogeneity in the literature regarding the role of gastroenteritis in the development of IBD. Further higher quality studies need to be performed to ascertain the true nature of this.

Increased incidence of inflammatory bowel disease on etanercept in juvenile idiopathic arthritis regardless of concomitant methotrexate use.

ObjectiveTo describe risk factors for IBD development in a cohort of children with JIA.MethodsJIA patients who developed IBD were identified from the international Pharmachild register. Characteristics were compared between IBD and non-IBD patients and predictors of IBD were determined using multivariable logistic regression analysis. Incidence rates of IBD events on different DMARDs were calculated, and differences between therapies were expressed as relative risks (RR).ResultsOut of 8942 patients, 48 (0.54% ) developed IBD. These were more often male (47.9% vs 32.0%) and HLA-B27 positive (38.2% vs 21.0%) and older at JIA onset (median 8.94 vs 5.33 years) than patients without IBD development. They also had more often a family history of autoimmune disease (42.6% vs 24.4%) and enthesitis-related arthritis (39.6% vs 10.8%). The strongest predictors of IBD on multivariable analysis were enthesitis-related arthritis [odds ratio (OR): 3.68, 95% CI: 1.41, 9.40] and a family history of autoimmune disease (OR: 2.27, 95% CI: 1.12, 4.54). Compared with methotrexate monotherapy, the incidence of IBD on etanercept monotherapy (RR: 7.69, 95% CI: 1.99, 29.74), etanercept with methotrexate (RR: 5.70, 95% CI: 1.42, 22.77) and infliximab (RR: 7.61, 95% CI: 1.27, 45.57) therapy was significantly higher. Incidence on adalimumab was not significantly different (RR: 1.45, 95% CI: 0.15, 13.89).ConclusionIBD in JIA was associated with enthesitis-related arthritis and a family history of autoimmune disease. An increased IBD incidence was observed for etanercept therapy regardless of concomitant methotrexate use.

Roles of Lipid Peroxidation-Derived Electrophiles in Pathogenesis of Colonic Inflammation and Colon Cancer.

Redox stress is a common feature of gut disorders such as colonic inflammation (inflammatory bowel disease or IBD) and colorectal cancer (CRC). This leads to increased colonic formation of lipid-derived electrophiles (LDEs) such as 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), trans, trans-2,4-decadienal (tt-DDE), and epoxyketooctadecenoic acid (EKODE). Recent research by us and others support that treatment with LDEs increases the severity of colitis and exacerbates the development of colon tumorigenesis in vitro and in vivo, supporting a critical role of these compounds in the pathogenesis of IBD and CRC. In this review, we will discuss the effects and mechanisms of LDEs on development of IBD and CRC and lifestyle factors, which could potentially affect tissue levels of LDEs to regulate IBD and CRC development.

Thymic microbiota-specific T cells role in intestinal inflammation

Abstract Inflammatory bowel disease (IBD) patients, including Crohn’s disease and ulcerative colitis, exhibit dysregulated immune responses. Although IBD etiology remains uncertain, microbiota-reactive T cells are thought to play a role in pathogenesis. It has been shown that gut microbiota and their metabolites play a role in modulating mucosal immune responses and thus, have the potential to influence the development of IBD. Although host-microbe interactions are required to balance effector and regulatory T cells responses, it remains unknown how microbiota-specific T cells are generated. Here we studied how microbiota-specific T cells develop and how they can drive intestinal inflammation. Colonization of mice at weaning induced the expansion of naive microbiota-specific T cells in the thymus before peripheral distribution. Transfer of naive thymic microbiota-specific T cells into immunodeficient mice induced intestinal inflammation by differentiating into Th1 or Th17 cells. We identified that CX3CR1+ dendritic cells (CX3+DCs) were required for this process, as depleting these cells decreased the expansion of thymic microbiota-specific T cells. Transfer of thymic T cells from mice lacking CX3+ DCs induced less colitis in immunodeficient mice compared to wildtype donors. Moreover, inhibiting CX3+ DCs antigen-presentation suppressed induction of microbiota-specific T cells and transfer of these cells promoted less intestinal inflammation. Together, our data suggests CX3+ DCs drive T cell selection of microbiota-specific T cells in the thymus, which can differentiate into intestinal effector T cells mediating pathology in immunodeficient hosts.

Nutrition and Lifestyle Factors Associated with Inflammatory Bowel Disease

Many dietary and lifestyle factors are found to be associated with the pathogenesis of IBD. The purpose of this study is to review the dietary and lifestyle factors associated with IBD. Several studies in IBD were discussed, and highlighted the independent effects of various dietary and lifestyle factors on the risk of IBD. IBD is chronic relapsing intestinal inflammatory disease characterized by complex interactions of multiple factors including smoking, major life stressors, diet and lifestyle. This paper attempts to investigate the association between dietary patterns and IBD risk and compare lifestyle factors among IBD patients. Dietary factors tend to play a pivotal role in the disease etiopathogenesis and course. However, research on food and IBD is contradictory. An excessive intake of sugar and animal fat is considered a risk factor for the development of IBD, whereas a high fiber diet and high intake of fruits and vegetables may play a protective effect. The role of lifestyle factors in IBD is crucial. Amply of evidence suggested that smoking is a causative agent in CD while it is protective against UC. Stress, depression, vitamin D deficiency and impaired sleep have all been all associated with incident IBD. A diet with a modified carbohydrate composition, a semi-vegetarian diet, a diet low in protein and fat and a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols should be taken into consideration for IBD patients.

A167 UNDERSTANDING THE IMPACT OF DOWNSTREAM OF KINASE 4 (DOK4) DAMAGING GENETIC VARIANTS IN THE PATHOGENESIS OF PEDIATRIC INFLAMMATORY BOWEL DISEASE (IBD).

Abstract Background IBD is a chronic inflammatory disorder of the gastrointestinal (GI) tract whose precise pathological mechanisms remain elusive. It is thought that in pediatric IBD, pathogenic exposure does not appear sufficient to cause disease, thus genetic variations are critical to disease pathogenesis. The Muise Lab uses genetic sequencing of patients with IBD from all over the world to identify crucial genetic variations that are critical to IBD development. We report two patients with IBD from unrelated families with mutations in DOK4. Both patients had profound extra-intestinal disease complicating their IBD. Downstream of kinase (DOK) proteins are a family of adaptor molecules that are important in regulating cell signaling, especially in immune cells. They are known to suppress MAPK and PI3K/AKT pathways, whose dysregulation result in cancer. DOK4 has not been extensively studied, but research suggests that this gene produces two isoforms. It is known to have negative regulatory effects on immune cell activation but is also expressed across various other tissues, where its function is yet to be determined. Aims We hypothesize that these variations in DOK4 lead to immune cell dysregulation, which manifests in both gastrointestinal and systemic chronic inflammatory disease. Through this study, we aim to elucidate the mechanism of novel genetic defects in DOK4. Methods It will be critical to understand how variants within both patients are contributing to the onset of IBD through in vitro studies. Therefore, we will characterize and quantify how changes in expression of DOK4 alters essential cell signaling pathways. We have established immortalized cell lines from patients bearing these mutations to specifically characterize potential immune defects. We will also be using knock out cell models to understand the effect of loss of function of DOK4 in different cell types. Results Preliminary data shows variation in expression of the protein within patient peripheral blood mononuclear cells (PBMCs) compared to a healthy donor. Overexpression in HEK293T cells shows changes in MAPK and NFkB signaling. Conclusions With this study, we hope to identify new therapeutic targets for patients with DOK4 mutations. Funding Agencies CIHRThe Leona M. and Harry B. Helmsley Charitable Trust

Bariatric Surgery and Risk of New-onset Inflammatory Bowel Disease: A Nationwide Cohort Study.

The aim of this study was to examine the risk of new-onset inflammatory bowel disease [IBD] following bariatric surgery. We conducted a nationwide population-based prospective cohort study of the entire Danish population 18 to 60 years of age, alive, and residing in Denmark, from 1996 to 2018. Bariatric surgery was included as a time-dependent variable, and Cox proportional hazards regression models were used to estimate hazard ratios [HRs] of IBD. We used a model adjusting for age, sex, and birth cohort and a multifactor-adjusted model additionally including educational status and number of obesity-related comorbidities. We followed 3 917 843 individuals of whom 15 347 had a bariatric surgery, for development of new-onset IBD. During 106 420 person-years following bariatric surgery, 100 IBD events occurred [incidence rate 0.940/1000 person-years]. During 55 553 785 person-years without bariatric surgery, 35 294 events of IBD occurred [incidence rate 0.635/1000 person-years]. This corresponded to a multifactor-adjusted hazard ratio [HR] of 1.15 (95% confidence interval[CI], 0.94-1.40) for IBD. Multifactor-adjusted HRs of Crohn's disease [CD] and ulcerative colitis [UC] were 1.85 [95% CI, 1.40-2.44] and 0.81 [95% CI, 0.61-1.08], respectively. Among women, the multifactor-adjusted HR for CD was 2.18 [95% CI, 1.64-2.90]. When limiting the study population to individuals with a diagnosis of overweight/obesity, bariatric surgery remained associated with increased risk of CD, multifactor-adjusted HR 1.59 [95% CI, 1.18-2.13]. This nationwide cohort study shows that bariatric surgery is associated with increased risk of development of new-onset CD, but not of UC. The underlying mechanisms remain elusive.

Restored Macrophage Function Ameliorates Disease Pathophysiology in a Mouse Model for IL10 Receptor-deficient Very Early Onset Inflammatory Bowel Disease

Mutations in IL10 or the IL10 receptor lead to very early onset [VEO] inflammatory bowel disease [IBD], a life-threatening disease which is often unresponsive to conventional medication. Recent studies have demonstrated that defective IL-10 receptor signalling in innate immune cells is a key driver of severe intestinal inflammation in VEO-IBD. Specifically, IL10 unresponsiveness of macrophages, which govern the tight balance between pro- and anti-inflammatory responses in the intestinal system, plays a central role in the events leading to excessive inflammatory responses and the development of IBD. We here evaluated haematopoietic stem cell gene therapy in a VEO-IBD mouse model and demonstrated that the therapeutic response closely correlates with gene correction of the IL10 signalling pathway in intestinal macrophages. This finding prompted us to evaluate the therapeutic efficacy of macrophage transplantation in the Il10rb-/- VEO-IBD mouse model. A 6-week regimen employing a combination of depletion of endogenous hyperinflammatory macrophages followed by intraperitoneal administration of wild-type [WT] macrophages significantly reduced colitis symptoms. In summary, we show that the correction of the IL10 receptor defect in macrophages, either by genetic therapy or transfer of WT macrophages to the peritoneum, can ameliorate disease-related symptoms and potentially represent novel treatment approaches for VEO-IBD patients.

A TRANSLATIONAL PHASE I STUDY OF TAUROURSODEOXYCHOLIC ACID (TUDCA) TO REDUCE SYMPTOMS AND ER STRESS IN ACTIVE ULCERATIVE COLITIS

Emerging evidence has demonstrated that protein misfolding in the endoplasmic reticulum (ER), i.e., ER stress, plays fundamental roles in IBD development in humans. Patients with active Crohn’s disease and ulcerative colitis exhibit signs of ER stress in their ileal and/or colonic epithelium. Human genetic studies of IBD have identified primary genetic abnormalities in several genes that encode proteins associated with ER stress. We recently reported that oral delivery of tauroursodeoxycholic acid (TUDCA), a naturally occurring bile salt proven to reduce ER stress both in vitro and in vivo, dramatically decreases the clinical, histological and biochemical signs of inflammation in four different IBD mouse models through reducing ER stress in colonic epithelial cells.

DUSP16 IS A NOVEL IBD GENE IMPLICATED IN THE REGULATION OF DIFFERENTIATION AND HOMEOSTASIS OF INTESTINAL EPITHELIAL CELLS

Abstract Inflammatory bowel disease (IBD) are chronic inflammatory diseases including Crohn’s disease (CD) and ulcerative colitis (UC). More than 200 genomic regions have been identified and validated (association values〈 5x10-8) to be associated with CD, UC or IBD. These regions may contain multiple genes and the current challenge lies in identifying the causal gene in each of these. To address this problem, we performed a functional genomic screen of 145 genes from validated IBD loci, in a relevant intestinal epithelial cell model (HT-29). The results of this transcriptome-based screening revealed that the candidate IBD gene DUSP16 (a dual specificity phosphatase targeting MAP kinases (MAPKs) phosphorylation) as well as the known IBD gene KSR1 (a scaffold protein regulating the spatiotemporal activation of the ERK) regulate the expression of genes involved in intestinal differentiation and homeostasis. They induce, among others, the expression of the PIGR gene that encodes the polymeric immunoglobulin receptor. PIGR plays a role in transporting dimeric IgA molecules from the basolateral membrane of epithelial cells to the intestinal lumen, via transcytosis, where they play an essential role in protecting the epithelium against intestinal pathogens. Our hypothesis is that DUSP16 and KSR1 modulate the activity of MAPKs in intestinal epithelial cells to induce PIGR expression, thus participating in the maintenance of homeostasis of the intestinal barrier. To better understand how DUSP16 modulates the expression of PIGR, we used an approach of over- expression (cDNA) and knockdown (shRNA) of DUSP16 in HT-29 cells. Our results confirmed that DUSP16 induction increases the expression of PIGR, whereas a knockdown of DUSP16 reduces the basal level of PIGR. Next we confirmed by Western Blot that the induction of DUSP16 was accompanied by a decrease in MAPK phosphorylation. The involvement of MAPKs was also confirmed through the use of chemical inhibitors specific for each MAPK, with inhibition of ERK and p38 showing the strongest induction of PIGR expression. We are currently analyzing known functional mutants of DUSP16 and KSR1 to determine their impact on MAPK activity and on PIGR expression. This work supports a role for PIGR in disease pathogenesis, adding to two recent studies that documented that patients suffering from UC accumulated somatic mutations in a group of genes regulating the expression of PIGR by Interleukin 17. The mutated genes, including PIGR, were positively selected in inflamed tissues, indicating the importance of the biological function occupied by this gene in the maintenance of homeostasis. In conclusion, our study successfully identified functional links between two genes from independent IBD loci, and suggests that these DUSP16 and KSR1 play a role in the process of epithelial transcytosis and the development of IBD.

A TRANSLATIONAL PHASE I STUDY OF TAUROURSODEOXYCHOLIC ACID (TUDCA) TO REDUCE SYMPTOMS AND ER STRESS IN ACTIVE ULCERATIVE COLITIS

Abstract Background Emerging evidence has demonstrated that protein misfolding in the endoplasmic reticulum (ER), i.e., ER stress, plays fundamental roles in IBD development in humans. Patients with active Crohn’s disease and ulcerative colitis exhibit signs of ER stress in their ileal and/or colonic epithelium. Human genetic studies of IBD have identified primary genetic abnormalities in several genes that encode proteins associated with ER stress. We recently reported that oral delivery of tauroursodeoxycholic acid (TUDCA), a naturally occurring bile salt proven to reduce ER stress both in vitro and in vivo, dramatically decreases the clinical, histological and biochemical signs of inflammation in four different IBD mouse models through reducing ER stress in colonic epithelial cells. Aim Based on this, our aim was to test the efficacy and safety of TUDCA in an open label, Phase I trial for patients with symptomatic ulcerative colitis. Methods TUDCA was administered at 2000 mg divided TID for 6 weeks. Baseline and 6 week colonoscopy/flexible sigmoidoscopy with biopsy was performed. Outcome measures include safety, tolerability, Mayo score, and change in markers of ER stress from colon biopsies. Results To date, complete data is available on 9 of a planned 12 patients. TUDCA was well tolerated and safe with no Grade 3 or greater CTCAE adverse events and no Serious Adverse Events. A significant reduction of 4.6 points on the complete Mayo score was observed from baseline to week 6 (Avg. 8.6 ± 2.5 → 4.00 ± 2.7, P=0.004) with 100% of patients seeing a decrease. Clinical remission, clinical response and mucosal healing were observed in 22%, 67% and 56% respectively. Fecal calprotectin decreased in 67% of patients. As diarrhea can be a side effect of TUDCA treatment at these doses, we also assessed the Partial Mayo Score at two weeks after completion of the trial (8 weeks from baseline). At this time point the Partial Mayo Score significantly decreased by 3.8 points (Avg. 6.2 ± 2.1 → 2.4 ± 1.9, P=0.004) with 67% achieving clinical response and 56% remission. The Robarts Histopathology Index decreased in 8 of 9 patients with a mean reduction of 2.67 points (Avg. 6.4 ± 3.2 → 3.8 ± 2.9, P=0.003). Total serum bile acid profiles changed, but not significantly so, from Wk0 to Wk6. ER stress markers Bip, eIF2a and p-eIF2a were increased in inflamed colon tissue and were lowered post TUDCA treatment in a subset of patients. Conclusions Preliminary results from a Phase I clinical trial demonstrate that the dietary supplement TUDCA is safe, well tolerated and is associated with significant clinical improvement in a majority of patients with moderate to severely active ulcerative colitis. Mucosal healing and reductions in markers of ER stress were observed in a subset of patients. Study completion and analysis of gene expression and microbiome are underway.

The Oral Microbiome in Pediatric IBD: A Source of Pathobionts or Biomarkers?

The oral cavity is continuous with the gastrointestinal tract and in children, oral health may be closely linked with the overall health of the GI tract. In the case of pediatric Crohn's disease (CD), oral manifestations are an important clinical indicator of intestinal disease. Recent studies of the microbiome in IBD suggest that translocation of oral microbes to the gut may be a common feature of the microbial dysbiosis which is a signature of both CD and ulcerative colitis (UC). Murine studies suggest that translocation of oral bacteria and yeasts to the lower GI tract may trigger inflammation in susceptible hosts, providing a mechanistic link to the development of IBD. Conversely, some studies have shown that dysbiosis of the oral microbiome may occur, possibly as a result of inflammatory responses and could represent a useful source of biomarkers of GI health. This review summarizes our current knowledge of the oral microbiome in IBD and presents current hypotheses on the potential role of this community in the pathogenesis of these diseases.

Alterations in Bile Acid Metabolism Associated With Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disorder closely related to gut dysbiosis, which is associated with alterations in an important bacterial metabolite, bile acids (BAs). Although certain findings pertinent to BA changes in IBD vary among studies owing to the differences in sample type, quantitated BA species, study methodology, and patient characteristics, a specific trend concerning variations of BAs in IBD has been identified. In elaborating on this observation, it was noted that primary BAs and conjugated BAs are augmented in fecal samples but there is a reduction in secondary BAs in fecal samples. It is not entirely clear why patients with IBD manifest these changes and what role these changes play in the onset and development of IBD. Previous studies have shown that IBD-associated BA changes may be caused by alterations in BA absorption, synthesis, and bacterial modification. The complex relationship between bacteria and BAs may provide additional and deeper insight into host-gut microbiota interactions in the pathogenesis of IBD. The characteristic BA changes may generate profound effects in patients with IBD by shaping the gut microbiota community, affecting inflammatory processes, causing BA malabsorption associated with diarrhea, and even leading to intestinal dysplasia and cancer. Thus, therapeutic strategies correcting the alterations in the composition of BAs, including the elimination of excess BAs and the supplementation of deficient BAs, may prove promising in IBD.