Pediatric inflammatory bowel disease: What's new and what has changed?

The incidence and prevalence of inflammatory bowel disease (IBD) is on the rise in North America and worldwide, with young children being the fastest growing patient population. It is therefore essential for pediatricians and pediatric sub-specialists to be able to recognize signs and symptoms suspicious for a new diagnosis of IBD, as well as potential complications associated with IBD or its treatment. This article reviews the most recent literature regarding clinical presentation, helpful diagnostic clues, newer monitoring tools being used by pediatric gastroenterologists, and emerging new biologic and small molecule treatments.

Landscape of TPMT and NUDT15 Pharmacogenetic Variation in a Cohort of Canadian Pediatric Inflammatory Bowel Disease Patients.

BACKGROUND: Patients with inflammatory bowel disease (IBD) exhibit considerable interindividual variability in medication response, highlighting the need for precision medicine approaches to optimize and tailor treatment. Pharmacogenetics (PGx) offers the ability to individualize dosing by examining genetic factors underlying the metabolism of medications such as thiopurines. Pharmacogenetic testing can identify individuals who may be at risk for thiopurine dose-dependent adverse reactions including myelosuppression. We aimed to evaluate PGx variation in genes supported by clinical guidelines that inform dosing of thiopurines and characterize differences in the distribution of actionable PGx variation among diverse ancestral groups. METHODS: Pharmacogenetic variation in TPMT and NUDT15 was captured by genome-wide genotyping of 1083 pediatric IBD patients from a diverse Canadian cohort. Genetic ancestry was inferred using principal component analysis. The proportion of PGx variation and associated metabolizer status phenotypes was compared across 5 genetic ancestral groups within the cohort (Admixed American, African, East Asian, European, and South Asian) and to prior global estimates from corresponding populations. RESULTS: Collectively, 11% of the cohort was categorized as intermediate or poor metabolizers of thiopurines, which would warrant a significant dose reduction or selection of alternate therapy. Clinically actionable variation in TPMT was more prevalent in participants of European and Admixed American/Latino ancestry (8.7% and 7.5%, respectively), whereas variation in NUDT15 was more prevalent in participants of East Asian and Admixed American/Latino ancestry (16% and 15% respectively). CONCLUSIONS: These findings demonstrate the considerable interpopulation variability in PGx variation underlying thiopurine metabolism, which should be factored into testing diverse patient populations.

In a large, pediatric inflammatory bowel disease cohort comprised of 5 genetic ancestry groups, we evaluated the distribution of loss-of-function pharmacogenetic variants in TPMT and NUDT15 and predicted phenotypes (impact on thiopurine metabolism).

Environmental Factors Associated with Risk of Crohn's Disease Development in the Crohn's and Colitis Canada - Genetic, Environmental, Microbial Project.

BACKGROUND & AIMS: To date, it is unclear how environmental factors influence Crohn's disease (CD) risk and how they interact with biological processes. This study investigates the association between environmental exposures and CD risk and evaluates their association with pre-disease biomarkers. METHODS: We studied 4289 healthy first-degree relatives (FDRs) of patients with CD from the Crohn's and Colitis Canada - Genetic, Environmental, Microbial (CCC-GEM) project. Regression models identified environmental factors associated with future CD onset and their association with pre-disease biological factors, including altered intestinal permeability measured by urinary fractional excretion of lactulose to mannitol ratio (LMR); gut inflammation via fecal calprotectin (FCP) levels; and fecal microbiome composition through 16S rRNA sequencing. RESULTS: Over a 5.62-year median follow-up, 86 FDRs developed CD. Living with a dog between ages 5 and 15 (hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.40-0.96; P = .034), and living with a large family size in the first year of life (HR, 0.43; 95% CI, 0.21-0.85; P = .016) were associated with decreased CD risk, whereas having a bird at the time of recruitment (HR, 2.78; 95% CI, 1.36-5.68; P = .005) was associated with an increased CD risk. Furthermore, living with a dog was associated with reduced LMR, altered relative abundance of multiple bacterial genera, and increased Chao1 diversity, whereas bird owners had higher FCP levels. Large family during participants' first year of life was associated with altered microbiota composition without affecting FCP or LMR. CONCLUSION: This study identifies environmental variables associated with CD risk. These variables were also associated with altered barrier function, subclinical inflammation, and gut microbiome composition shifts, suggesting potential roles in CD pathogenesis.

Pre-Diagnosis Diet Predicts Response to Exclusive Enteral Nutrition and Correlates with Microbiome in Pediatric Crohn Disease.

Exclusive enteral nutrition (EEN) is effective in inducing remission in pediatric Crohn disease (CD). EEN alters the intestinal microbiome, but precise mechanisms are unknown. We hypothesized that pre-diagnosis diet establishes a baseline gut microbiome, which then mediates response to EEN. We analyzed prospectively recorded food frequency questionnaires (FFQs) for pre-diagnosis dietary patterns. Fecal microbiota were sequenced (16SrRNA) at baseline and through an 18-month follow-up period. Dietary patterns, Mediterranean diet adherence, and stool microbiota were associated with EEN treatment outcomes, disease flare, need for anti-tumor necrosis factor (TNF)-α therapy, and long-term clinical outcomes. Ninety-eight patients were included. Baseline disease severity and microbiota were associated with diet. Four dietary patterns were identified by FFQs; a "mature diet" high in fruits, vegetables, and fish was linked to increased baseline microbial diversity, which was associated with fewer disease flares (p < 0.05) and a trend towards a delayed need for anti-TNF therapy (p = 0.086). Baseline stool microbial taxa were increased (Blautia and Faecalibacterium) or decreased (Ruminococcus gnavus group) with the mature diet compared to other diets. Surprisingly, a "pre-packaged" dietary pattern (rich in processed foods) was associated with delayed flares in males (p < 0.05). Long-term pre-diagnosis diet was associated with outcomes of EEN therapy in pediatric CD; diet-microbiota and microbiota-outcome associations may mediate this relationship.

Outcomes Following Acute Severe Colitis at Initial Presentation: A Multi-centre, Prospective, Paediatric Cohort Study.

AIM: To assess contemporary outcomes in children with acute severe ulcerative colitis [ASUC] at initial presentation. METHODS: Between April 2014 and January 2019, children aged <17 years, with new onset ASUC (Paediatric Ulcerative Colitis Activity Index [PUCAI ≥65) were prospectively followed in a Canadian inception cohort study. 16S rRNA amplicon sequencing captured microbial composition of baseline faecal samples. Primary endpoint was corticosteroid-free clinical remission with intact colon at 1 year [PUCAI <10, no steroids ≥4 weeks]. RESULTS: Of 379 children with new onset UC/IBD-unclassified, 105 [28%] presented with ASUC (42% male; median [interquartile range; [IQR]) age 14 [11-16] years; extensive colitis in all). Compared with mild UC, gut microbiome of ASUC patients had lower α-diversity, decreased beneficial anaerobes, and increased aerobes; 54 [51%] children were steroid-refractory and given infliximab [87% intensified regimen]. Corticosteroid-free remission at 1 year was achieved by 62 [61%] ASUC cohort (by 34 [63%] steroid-refractory patients, all on biologics; by 28 [55%] steroid responders,13 [25%] on 5- aminosalicylic acid [5-ASA], 5 [10%] on thiopurines, 10 [20%] on biologics). By 1 year, 78 [74%] escalated to infliximab including 24 [47%] steroid-responders failed by 5-ASA and/or thiopurines. In multivariable analysis, clinical predictors for commencing infliximab included hypoalbuminaemia, greater PUCAI, higher age, and male sex. Over 18 months, repeat corticosteroid course[s] and repeat hospitalisation were less likely among steroid-refractory versus -responsive but -dependent patients (adjusted odds ratio [aOR] 0.71 [95% CI 0.57-0.89] and 0.54 [95% CI 0.45-0.66], respectively). CONCLUSION: The majority of children presenting with ASUC escalate therapy to biologics. Predictors of need for advanced therapy may guide selection of optimal maintenance therapy.

ADALIMUMAB VERSUS INFLIXIMAB IN LUMINAL PEDIATRIC CROHN'S DISEASE: COMPARABLE OUTCOMES IN A PROSPECTIVE MULTICENTER COHORT STUDY.

BACKGROUND: This study compared real-world effectiveness between adalimumab (ADA) and infliximab (IFX) in children with Crohn's disease (CD). METHODS: Children enrolled into the prospective Canadian Children Inflammatory Bowel Disease Network (CIDsCaNN) National Inception Cohort between 2014 and 2020 who commenced ADA or IFX as first anti-tumor necrosis factor (antiTNF) agent for luminal CD were included. Multivariate logistic regression modelled the propensity of commencing ADA; propensity score matching was used to match IFX-treated children to ADA-treated children. The primary outcome at one year was steroid-free clinical remission (SFCR). Secondary outcomes at one year were I) combined SFCR and c-reactive protein (CRP) remission; II) treatment intensification; and III) antiTNF durability. Odds ratios (aOR) and hazard ratio (aHR) adjusted for concomitant immunomodulator use with 95% confidence interval (CI) are reported. RESULTS: In the propensity score matched cohort of 147 ADA-treated and 147 IFX-treated children, 92 (63%) ADA- and 87 (59%) IFX-treated children achieved SFCR at one year (aOR: 1.4, 95% CI 0.9-2.4); 75 of 140 (54%) ADA- and 85 of 144 (59%) IFX-treated children achieved combined SFCR and CRP remission (aOR: 1.0, 95% CI 0.6-1.6). ADA-treated children less frequently underwent treatment intensification (21 [14%]) compared to IFX-treated children (69 [47%]) (P<0.0001). Discontinuation of antiTNF occurred in 18 (12%) ADA-treated and 15 (10%) IFX-treated children (aHR: 1.2, 95% CI 0.6-2.2). CONCLUSION: Children with Crohn's disease achieved favourable outcomes at one year with either ADA or IFX as first antiTNF agents. Those receiving IFX did not have significantly superior outcomes compared to clinically similar children receiving ADA.

Gut Microbiome Composition Is Associated With Future Onset of Crohn's Disease in Healthy First-Degree Relatives.

BACKGROUND & AIMS: The cause of Crohn's disease (CD) is unknown, but the current hypothesis is that microbial or environmental factors induce gut inflammation in genetically susceptible individuals, leading to chronic intestinal inflammation. Case-control studies of patients with CD have cataloged alterations in the gut microbiome composition; however, these studies fail to distinguish whether the altered gut microbiome composition is associated with initiation of CD or is the result of inflammation or drug treatment. METHODS: In this prospective cohort study, 3483 healthy first-degree relatives (FDRs) of patients with CD were recruited to identify the gut microbiome composition that precedes the onset of CD and to what extent this composition predicts the risk of developing CD. We applied a machine learning approach to the analysis of the gut microbiome composition (based on 16S ribosomal RNA sequencing) to define a microbial signature that associates with future development of CD. The performance of the model was assessed in an independent validation cohort. RESULTS: In the validation cohort, the microbiome risk score (MRS) model yielded a hazard ratio of 2.24 (95% confidence interval, 1.03-4.84; P = .04), using the median of the MRS from the discovery cohort as the threshold. The MRS demonstrated a temporal validity by capturing individuals that developed CD up to 5 years before disease onset (area under the curve > 0.65). The 5 most important taxa contributing to the MRS included Ruminococcus torques, Blautia, Colidextribacter, an uncultured genus-level group from Oscillospiraceae, and Roseburia. CONCLUSION: This study is the first to demonstrate that gut microbiome composition is associated with future onset of CD and suggests that gut microbiome is a contributor in the pathogenesis of CD.

Transition Readiness in Youth with Inflammatory Bowel Disease.

OBJECTIVES: To examine readiness of adolescents and young adults (AYAs) with inflammatory bowel disease (IBD) to transition to adult care. STUDY DESIGN: A cross-sectional multicenter study evaluating transition readiness in individuals with IBD 16-19 years old prospectively recruited from 8 Canadian IBD centers using the validated ON Taking Responsibility for Adolescent to Adult Care (ON TRAC) questionnaire. Secondary aims included (1) screening for depression and anxiety using the 8-item Personal Health Questionnaire Depression Scale and The Screen for Child Anxiety Related Emotional Disorders questionnaires, respectively; (2) evaluating the association between depression and anxiety with readiness and disease activity; and (3) subjectively evaluating AYA readiness based on physician and parent assessments. RESULTS: In total, 186 participants (139 adolescent, 47 young adult) were enrolled, mean age 17.4 years (SD, 0.87). ON TRAC scores determined that 26.6% of AYAs at pediatric and 40.4% at adult centers reached the threshold of readiness. On multivariable linear regression analysis age was positively (P = .001) and disease remission negatively (P = .03) associated with ON TRAC scores. No statistically significant differences were determined across centers. A significant percentage of AYAs reported moderate-to-severe depression (21.7%) and generalized anxiety (36%); however, neither were significantly associated with ON TRAC scores. Notably, physician and parental assessment of AYA readiness correlated poorly with ON TRAC scores (⍴ = 0.11, ⍴ = 0.24, respectively). CONCLUSIONS: Assessment of transition readiness in AYAs with IBD highlighted that a large proportion do not have adequate knowledge or behavior skills needed for transition to adult care. This study infers that readiness assessment tools are essential during transition to identify deficits in knowledge and behavior skills that could be specifically targeted by the youth, caregivers, and multidisciplinary team.

Immune response and barrier dysfunction-related proteomic signatures in preclinical phase of Crohn's disease highlight earliest events of pathogenesis.

OBJECTIVE: The measure of serum proteome in the preclinical state of Crohn's disease (CD) may provide insight into biological pathways involved in CD pathogenesis. We aimed to assess associations of serum proteins with future CD onset and with other biomarkers predicting CD risk in a healthy at-risk cohort. DESIGN: In a nested case-control study within the Crohn's and Colitis Canada Genetics Environment Microbial Project (CCC-GEM) cohort, which prospectively follows healthy first-degree relatives (FDRs), subjects who developed CD (n=71) were matched with four FDRs remaining healthy (n=284). Using samples at recruitment, serum protein profiles using the Olink Proximity Extension Assay platform was assessed for association with future development of CD and with other baseline biomarkers as follows: serum antimicrobial antibodies (AS: positive antibody sum) (Prometheus); faecal calprotectin (FCP); gut barrier function using the fractional excretion of lactulose-to-mannitol ratio (LMR) assay. RESULTS: We identified 25 of 446 serum proteins significantly associated with future development of CD. C-X-C motif chemokine 9 (CXCL9) had the highest OR with future risk of CD (OR=2.07 per SD, 95% CI 1.58 to 2.73, q=7.9e-5), whereas matrix extracellular phosphoglycoprotein had the lowest OR (OR 0.44, 95% CI 0.29 to 0.66, q=0.02). Notably, CXCL9 was the only analyte significantly associated with all other CD-risk biomarkers with consistent direction of effect (FCP: OR=2.21; LMR: OR=1.67; AS: OR=1.59) (q<0.05 for all). CONCLUSION: We identified serum proteomic signatures associated with future CD development, reflecting potential early biological processes of immune and barrier dysfunction.

Inflammatory Bowel Disease Among Canadian Children: Comparison Between Children of Non-European Descent and Children of European Descent.

BACKGROUND: Inflammatory bowel disease (IBD) phenotypes may differ between countries and ancestral groups. The study aim was to examine ancestry and subtype variations of children newly diagnosed with IBD. METHODS: Children newly diagnosed with IBD enrolled into the Canadian Children Inflammatory Bowel Disease Network inception cohort study were categorized into 8 ancestral groups. Prospectively collected data at diagnosis and follow-up were compared between ancestral groups. RESULTS: Among 1447 children (63.2% Crohn's disease, 30.7% ulcerative colitis), 67.8% were European, 9.4% were South Asian, 3.8% were West Central Asian and Middle Eastern, 2.3% were African, 2.2% were East/South East Asian, 2.0% were Caribbean/Latin/Central/South American, 9.9% were mixed, and 2.6% were other. Children of African descent with ulcerative colitis had an older age of diagnosis compared with children of European descent (median 15.6 years vs 13.3 years; P = .02). Children of European descent had a higher proportion of positive family history with IBD (19.3% vs 12.1%; P = .001) compared with children of non-European descent. Children of European descent also had a lower proportion of immigrants and children of immigrants compared with children of non-European descent (9.8% vs 35.9%; P < .0001; and 3.6% vs 27.2%; P < .0001, respectively) . CONCLUSIONS: Important differences exist between different ancestral groups in pediatric patients with IBD with regard to age of diagnosis, family history, and immigrant status. Our study adds to the knowledge of the impact of ancestry on IBD pathogenesis.

This study explores the ancestral and phenotypic variation of Canadian children newly diagnosed with inflammatory bowel disease. It identifies differences between children of European and non-European descent in phenotypes of inflammatory bowel disease, disease location and behavior, family history, and immigrant status.

Variation in Testing for and Incidence of Celiac Autoimmunity in Canada: A Population-Based Study.

BACKGROUND & AIMS: The incidence of biopsy-confirmed celiac disease has increased. However, few studies have explored the incidence of celiac autoimmunity based on positive serology results. METHODS: A population-based cohort study assessed testing of tissue transglutaminase antibodies (tTG-IgA) in Alberta from 2012 to 2020. After excluding prevalent cases, incident celiac autoimmunity was defined as the first positive tTG-IgA result between 2015 and 2020. Testing and incidence rates for celiac autoimmunity were calculated per 1000 and 100,000 person-years, respectively. Incidence rate ratios (IRRs) were calculated to identify differences by demographic and regional factors. Average annual percent changes (AAPCs) assessed trends over time. RESULTS: The testing rate of tTG-IgA was 20.2 per 1000 person-years and remained stable from 2012 to 2020 (AAPC, 1.2%; 95% confidence interval [CI], -0.5 to 2.9). Testing was higher in female patients (IRR, 1.66; 95% CI, 1.65-1.66), those living in metropolitan areas (IRR, 1.39; 95% CI, 1.38-1.40), and in areas of lower socioeconomic deprivation (lowest compared to highest IRR, 1.24; 95% CI, 1.23-1.25). Incidence of celiac autoimmunity was 33.8 per 100,000 person-years and increased from 2015 to 2020 (AAPC, 6.2%; 95% CI, 3.1-9.5). Among those with tTG-IgA results ≥10 times the upper limit of normal, the incidence was 12.9 per 100,000 person-years. The incidence of celiac autoimmunity was higher in metropolitan settings (IRR, 1.28; 95% CI, 1.21-1.35) and in the least socioeconomically deprived areas compared to the highest (IRR, 1.22; 95% CI, 1.14-1.32). CONCLUSIONS: Incidence of celiac autoimmunity is high and increasing, despite stable testing rates. Variation in testing patterns may lead to underreporting the incidence of celiac autoimmunity in nonmetropolitan areas and more socioeconomically deprived neighborhoods.

Early Infliximab Clearance Predicts Remission in Children with Crohn's Disease.

BACKGROUND AND AIMS: Children with Crohn's disease have lower response rates to infliximab, lower infliximab levels, and higher infliximab clearance on weight-based dosing than adults. We hypothesize infliximab clearance is a predictive of later outcomes on infliximab in children with Crohn's disease. METHODS: In this single-center retrospective study, data were collected from charts on diagnosis, anthropometry, routine labs, infliximab therapeutic drug monitoring, infliximab dosing, disease activity, and other treatments. With these data we generated a population pharmacokinetic model using non-linear mixed effects modeling and calculated infliximab clearance for each patient over time. Patients were classified as in remission, responder-only or non-responder at 5, 10 and 16 months. Regression and ROC analyses were used to assess for early predictors of remission and response to infliximab. RESULTS: Eighty-five subjects were included, with a median follow-up of 22.3 months (IQR 10.1-36.8). Our pharmacokinetic model showed infliximab clearance was positively associated with CRP and weight, while negatively associated with albumin. In regression analyses, early infliximab clearance was the only significant, consistent predictor of remission. A 0.1 L/day increase in infliximab clearance predicted remission with an OR between 0.179 and 0.426. Differences in dosing did not account for differences in outcome. Infliximab clearance alone had moderate predictive accuracy of remission, with an AUC between 0.682 and 0.738. CONCLUSIONS: Early infliximab clearance is strongly associated with remission in children with Crohn's disease. It may be useful as a marker of response in proactive therapeutic drug monitoring to guide early dose optimization and/or changes in treatment for betterment of long-term outcomes.

Intestinal Ultrasound for the Pediatric Gastroenterologist: A Guide for Inflammatory Bowel Disease Monitoring in Children: Expert Consensus on Behalf of the International Bowel Ultrasound Group (IBUS) Pediatric Committee.

Crohn disease and ulcerative colitis are chronic inflammatory bowel diseases (IBD) often diagnosed in childhood. A strict monitoring strategy can potentially alter the disease course and facilitate early effective treatment before irreversible bowel damage occurs. Serial colonoscopy in children, the gold standard for monitoring, is impractical. Accurate, real-time, noninvasive markers of disease activity are needed. Intestinal ultrasound is an accurate, noninvasive, real-time, point-of-care, cross-sectional imaging tool used to monitor inflammation in pediatric IBD patients in Europe, Canada, and Australia. It is now emerging in a few expert centers in the United States as a safe, non-radiating, inexpensive, bedside tool used by the treating gastroenterologist for real-time decision-making. Unlike the standard biomarkers of pediatric IBD activity, C-reactive protein, and fecal calprotectin, intestinal ultrasound (IUS) facilitates disease localization, characterizes severity, extent, and accurately detects complications. Perhaps most importantly, IUS may enhance shared understanding and ease the burden of treatment decision-making for both the gastroenterologist and the patient. There is a lack of standardization for bedside IUS among pediatric gastroenterologists. The purpose is to outline a standardized approach to pediatric bedside IUS, including basic equipment requirements and technique, patient selection, preparation and positioning, technical considerations and limitations, documentation of mesenteric and luminal features of IBD, characterization of penetrating disease and strictures, and provide a proposed pediatric IUS monitoring algorithm to guide care.

Pediatric Patient and Caregiver Satisfaction With the Use of Transabdominal Bowel Ultrasound in the Assessment of Inflammatory Bowel Diseases.

OBJECTIVES: Transabdominal bowel ultrasound (TABUS) is emerging as an attractive, noninvasive tool in inflammatory bowel disease (IBD). Patient and caregiver experience with TABUS is not well described. We aimed to determine pediatric patient and caregiver satisfaction with TABUS and the impact of IBD severity, gender, age, and a history of anxiety on satisfaction. METHODS: Pediatric patients (0-18 years old) with suspected IBD prospectively underwent baseline TABUS, magnetic resonance enterography (MRE), blood work, stool studies, and endoscopy. Patients and their caregiver each completed a cross-sectional satisfaction questionnaire (5-point Likert scale) after the baseline investigations. RESULTS: There were 54 patients included (67% male). The majority were completely satisfied and strongly agree TABUS was better tolerated than other investigations, regardless of disease severity ( P > 0.05). Patients with higher Simple Endoscopic Score for Crohn Disease (SES-CD) scores felt that TABUS increased their understanding of their IBD ( P < 0.05) and disease location ( P < 0.05). Patients with Crohn disease had similar responses to those with ulcerative colitis, but more strongly agreed that TABUS was better than MRE and endoscopy ( P < 0.05). Those with anxiety did not have an increased level of worry about potential ultrasound findings ( P > 0.05). CONCLUSIONS: Pediatric patients and their caregivers were highly satisfied with TABUS, preferring it to other modalities. It did not lead to increased worry, and was particularly important in those with severe IBD. These findings support wider implementation of this well tolerated and preferred monitoring tool in pediatrics.

Unfermented ß-fructan Fibers Fuel Inflammation in Select Inflammatory Bowel Disease Patients.

BACKGROUND & AIMS: Inflammatory bowel diseases (IBD) are affected by dietary factors, including nondigestible carbohydrates (fibers), which are fermented by colonic microbes. Fibers are overall beneficial, but not all fibers are alike, and some patients with IBD report intolerance to fiber consumption. Given reproducible evidence of reduced fiber-fermenting microbes in patients with IBD, we hypothesized that fibers remain intact in select patients with reduced fiber-fermenting microbes and can then bind host cell receptors, subsequently promoting gut inflammation. METHODS: Colonic biopsies cultured ex vivo and cell lines in vitro were incubated with oligofructose (5 g/L), or fermentation supernatants (24-hour anaerobic fermentation) and immune responses (cytokine secretion [enzyme-linked immunosorbent assay/meso scale discovery] and expression [quantitative polymerase chain reaction]) were assessed. Influence of microbiota in mediating host response was examined and taxonomic classification of microbiota was conducted with Kraken2 and metabolic profiling by HUMAnN2, using R software. RESULTS: Unfermented dietary ß-fructan fibers induced proinflammatory cytokines in a subset of IBD intestinal biopsies cultured ex vivo, and immune cells (including peripheral blood mononuclear cells). Results were validated in an adult IBD randomized controlled trial examining ß-fructan supplementation. The proinflammatory response to intact ß-fructan required activation of the NLRP3 and TLR2 pathways. Fermentation of ß-fructans by human gut whole microbiota cultures reduced the proinflammatory response, but only when microbes were collected from patients without IBD or patients with inactive IBD. Fiber-induced immune responses correlated with microbe functions, luminal metabolites, and dietary fiber avoidance. CONCLUSION: Although fibers are typically beneficial in individuals with normal microbial fermentative potential, some dietary fibers have detrimental effects in select patients with active IBD who lack fermentative microbe activities. The study is publicly accessible at the U.S. National Institutes of Health database (clinicaltrials.gov identification number NCT02865707).

Altered Gut Microbiome Composition and Function Are Associated With Gut Barrier Dysfunction in Healthy Relatives of Patients With Crohn's Disease.

BACKGROUND & AIMS: The gut microbiome has been suggested to play a role in gut barrier hemostasis, but data are scarce and limited to animal studies. We therefore aimed to assess whether alterations in gut microbial composition and functional pathways are associated with gut barrier function in a cohort of healthy first-degree relatives of patients with Crohn's disease. METHODS: We used the Crohn's and Colitis Canada Genetic Environmental Microbial (CCC-GEM) cohort of healthy first-degree relatives of patients with Crohn's disease. Gut barrier function was assessed using the urinary fractional excretion of lactulose-to-mannitol ratio (LMR). Microbiome composition was assessed by sequencing fecal 16S ribosomal RNA. The cohort was divided into a discovery cohort (n = 2472) and a validation cohort (n = 655). A regression model was used to assess microbial associations with the LMR. A random forest classifier algorithm was performed to assess microbial community contribution to barrier function. RESULTS: Individuals with impaired barrier function (LMR >0.025) had reduced alpha-diversity (Chao1 index, P = 4.0e-4) and altered beta-diversity (Bray-Curtis dissimilarity index, R2 = 0.001, P = 1.0e-3) compared with individuals with an LMR ≤0.025. When taxa were assessed individually, we identified 8 genera and 52 microbial pathways associated with an LMR >0.025 (q < 0.05). Four genera (decreased prevalence of Adlercreutzia, Clostridia UCG 014, and Clostridium sensu stricto 1 and increased abundance of Colidextribacter) and 8 pathways (including decreased biosynthesis of glutamate, tryptophan, and threonine) were replicated in the validation cohort. The random forest approach revealed that the bacterial community is associated with gut barrier function (area under the curve, 0.63; P = 1.4e-6). CONCLUSIONS: The gut microbiome community and pathways are associated with changes in gut barrier function. These findings may identify potential microbial targets to modulate gut barrier.

Mediterranean-Like Dietary Pattern Associations With Gut Microbiome Composition and Subclinical Gastrointestinal Inflammation.

BACKGROUND & AIMS: Case-control studies have shown that patients with Crohn's disease (CD) have a microbial composition different from healthy individuals. Although the causes of CD are unknown, epidemiologic studies suggest that diet is an important contributor to CD risk, potentially via modulation of bacterial composition and gut inflammation. We hypothesized that long-term dietary clusters (DCs) are associated with gut microbiome compositions and gut inflammation. Our objectives were to identify dietary patterns and assess whether they are associated with alterations in specific gut microbial compositions and subclinical levels of gut inflammation in a cohort of healthy first-degree relatives (FDRs) of patients with CD. METHODS: As part of the Genetic, Environmental, Microbial (GEM) Project, we recruited a cohort of 2289 healthy FDRs of patients with CD. Individuals provided stool samples and answered a validated food frequency questionnaire reflecting their habitual diet during the year before sample collection. Unsupervised analysis identified 3 dietary and 3 microbial composition clusters. RESULTS: DC3, resembling the Mediterranean diet, was strongly associated with a defined microbial composition, with an increased abundance of fiber-degrading bacteria, such as Ruminococcus, as well as taxa such as Faecalibacterium. The DC3 diet was also significantly associated with lower levels of subclinical gut inflammation, defined by fecal calprotectin, compared with other dietary patterns. No significant associations were found between individual food items and fecal calprotectin, suggesting that long-term dietary patterns rather than individual food items contribute to subclinical gut inflammation. Additionally, mediation analysis demonstrated that DC3 had a direct effect on subclinical inflammation that was partially mediated by the microbiota. CONCLUSIONS: Overall, these results indicated that Mediterranean-like dietary patterns are associated with microbiome and lower intestinal inflammation. This study will help guide future dietary strategies that affect microbial composition and host gut inflammation to prevent diseases.

Anti-TNF therapy for inflammatory bowel disease in patients with neurodegenerative Niemann-Pick disease Type C.

Background:  Blockade of tumour necrosis factor (anti-TNF) is effective in patients with Crohn's Disease but has been associated with infection risk and neurological complications such as demyelination. Niemann-Pick disease Type C1 (NPC1) is a lysosomal storage disorder presenting in childhood with neurological deterioration, liver damage and respiratory infections. Some NPC1 patients develop severe Crohn's disease. Our objective was to investigate the safety and effectiveness of anti-TNF in NPC1 patients with Crohn's disease. Methods: Retrospective data on phenotype and therapy response were collected in 2019-2020 for the time period 2014 to 2020 from patients in the UK, France, Germany and Canada with genetically confirmed NPC1 defects and intestinal inflammation. We investigated TNF secretion in peripheral blood mononuclear cells treated with NPC1 inhibitor in response to bacterial stimuli . Results: NPC1 inhibitor treated peripheral blood mononuclear cells (PBMCs) show significantly increased TNF production after lipopolysaccharide or bacterial challenge providing a rationale for anti-TNF therapy. We identified 4 NPC1 patients with Crohn's disease (CD)-like intestinal inflammation treated using anti-TNF therapy (mean age of onset 8.1 years, mean treatment length 27.75 months, overall treatment period 9.25 patient years). Anti-TNF therapy was associated with reduced gastrointestinal symptoms with no apparent adverse neurological events. Therapy improved intestinal inflammation in 4 patients. Conclusions: Anti-TNF therapy appears safe in patients with NPC1 and is an effective treatment strategy for the management of intestinal inflammation in these patients.