A164 IDENTIFYING THE MOST IMPORTANT PREDICTORS TO CORRELATE SERUM METABOLITES WITH MRE CHANGES IN PATIENTS WITH PEDIATRIC CROHN DISEASE

Background

Endoscopy has been the gold standard for assessing activity in Pediatric Crohn disease (pCD); however, it is limited by its invasiveness and partial assessment of small intestine and transmural inflammation. To that end, the Pediatric Inflammatory Crohn's MRE Index (PICMI) is a valid, reliable, non-invasive, and responsive index that includes transmural inflammation when assessing disease activity.

The pathogenesis of pCD remains poorly understood, but evidence suggests that endogenous metabolites produced in the intestinal tract might mediate pathogenesis. Despite the important applicability of metabolomics in increasing the understanding of pCD, there has been limited research on this topic.

Purpose

Serum metabolomic profiles are linked to disease activity in pediatric Crohn disease.

Method

ImageKids is a multicenter, prospective, observational cohort study, designed to develop PICMI for pCD. The study was conducted over 18 months with paired serum specimens collected at study initiation and completion for 56 pCD patients. Due to the long time between the visits and the fact that during the study variables that highly affect serum metabolites were not controlled, we considered each patient visit as an individual measure point. Metabolites were identified using a quantitative metabolomics approach through The Metabolomics Innovation Centre (TMIC; University of Alberta). Disease activity was determined by the cutoff values in the total PICMI score of each patient.

The most relevant serum metabolites were identified by medium-level and high-level variable selection analysis. Pearson correlation and hypothesis testing were used to select important metabolites. Decision trees, regularization techniques, and support vector machines were used to assess explicit importance of metabolites in disease activity.

Result(s)

This work provides a strategy to reduce a dimensional dataset from a metabolomic experiment. By medium-level selection analysis we were able to identify 117 statistical important metabolites for disease activity. The high-level selection analysis allowed to indicate the importance of the top 10 metabolites trough disease activity (defined by PICMI index). Results, also show that the evaluation of importance of metabolites through multivariate statistical models is dependent of the intrinsic variable selection model.

Figure 1 reveals that Tryptophan ranked highest in the feature importance scoring. Histidine, Methylhistidine, Citric acid, Isoleucine, and Decanoylcarnitine also correlated well with disease severity.

Image

Conclusion(s)

This work uses a unique approach of multivariate statistical analyses, to identify metabolites associated with pCD disease activity. Tryptophan has been previously identified as significantly altered in the blood of IBD patients compared to controls. Histidine is known to be involved in the mediation of oxidative stress, potentially influencing intestinal inflammation. These metabolites could serve as biomarkers and help define pCD pathogenesis.

Disclosure of Interest

None Declared

A14 TRANSABDOMINAL BOWEL ULTRASOUND AND CLINICAL OUTCOMES OVER ONE YEAR IN CHILDREN WITH NEWLY DIAGNOSED CROHN’S DISEASE

Background

Transabdominal bowel ultrasound (TABUS) is an emerging non-invasive tool for monitoring inflammatory bowel disease (IBD). Its use is particularly increasing in pediatric IBD, given the need for anesthesia during endoscopy. The assessment of TABUS in pediatric IBD has been limited to small numbers of patients with no long-term follow-up.

Purpose

To describe TABUS findings and its relationship with clinical, biochemical, and endoscopic assessments in pediatric patients with Crohn’s disease up to one year post-diagnosis.

Method

Patients (0-18 years) with suspected IBD were prospectively enrolled through the Edmonton Pediatric IBD Clinic. Those with Crohn’s disease were included. Patients underwent repeated TABUS, clinical assessments, blood work, fecal calprotectin (FCP) (baseline, 1-, 3-, 6-, 12-months), and endoscopy (baseline and 6-12 months). The weighted Pediatric Crohn’s Disease Activity Index (wPCDAI), Simple Endoscopic Score for Crohn’s Disease (SES-CD; rectum excluded), and Simple Ultrasound Activity Score for Crohn’s Disease (SUS-CD; rectum excluded) were used. Remission was defined as FCP<250mg/kg, CRP<4mg/L, wPCDAI<12, no upcoming surgery, and SES-CD score ≤2 for any bowel segment.

Result(s)

Fifty-six patients (68% male), median age 12.5 years (range 6-17), were followed for 6 months. Forty (71%) were followed up to 12 months. Median TABUS bowel wall thickness (BWT) and SUS-CD total scores improved in all bowel segments over time. SUS-CD total scores significantly correlated with SES-CD (baseline, 6-, 12-months), wPCDAI (baseline, 1-, 6-, 12-months), CRP (baseline, 1-, 3-, 6-months), ESR (baseline, 1-, 3-, 6-, 12-months), and FCP (baseline, 1-, 6-, 12-months) (rho ranged 0.302-0.732, p<0.05). Patients in remission had sustained significantly thinner BWT of their most affected bowel segment (Figure 1) starting at 1-month (median 3.1mm (IQR 2.7-3.7) vs. 4.1mm (IQR 2.9-5.6; p<0.05), and sustained significantly lower SUS-CD total scores starting at 6 months (median 0 (IQR 0-1) vs. median 2 (IQR 1-3); p<0.05). Seven patients had surgery (n=7/7 ileocecal, n=2/7 jejunal resection). All 7 patients had complex TI disease (n=6 strictures, n=1 long-segment disease >25cm) and proximal small bowel disease (n=2/2) on TABUS. Those with baseline ultrasound findings of a stricture with upstream bowel dilatation (n=7/56) had increased odds (OR=288, p<0.01) and relative risk (RR=42, p<0.01) of needing surgery (n=6/7 with baseline obstructive findings, n=1/49 without) within the first year.

Image

Conclusion(s)

TABUS had significant correlations with clinical, biochemical, and endoscopic markers of Crohn’s disease activity in pediatric patients over one year. Bowel wall thickness of the most affected bowel segment is a helpful measurement, becoming significantly thinner as soon as 1-month post-diagnosis in those who obtain remission. Baseline findings of bowel narrowing and upstream dilation increase the odds and relative risk of needing surgery in the first year.

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None

Disclosure of Interest

None Declared

A50 THE EFFECTS OF SHORT-CHAIN FATTY ACIDS ON EPITHELIAL AND MACROPHAGE RESPONSE TO BACTEROIDES FRAGILIS

Background

Patients with IBD have an altered microbiome and gut microenvironment leading to changes in their Short-Chain Fatty Acid (SCFA) profile. Pathobionts are commensal organisms that become pathogenic under specific conditions, likely related to microenvironmental gut changes. This is especially relevant to children given that early life exposures are critical to microbiome development and impact immune response.

Purpose

The objectives of our study were to: 1) determine if microbes from IBD patients are more proinflammatory compared to non-IBD microbes; and 2) define how SCFAs affect host-response to potential pathobionts.

Method

Fructooligosaccharide (FOS) fermentation and SCFA production were assessed by HPLC-RID using whole-intestinal microbe culture collected as mucosal washes from pIBD (n=10) and non-IBD patients (n=8). Individual anaerobic bacteria were isolated from individual patients and screened for proinflammatory response [interleukin (IL)-1ß] using THP-1 macrophages. Caco-2 (epithelial) or THP-1 cells were pre-exposed to individual SCFAs (50 mM acetate or formate; 10 mM succinate; or 1 mM butyrate or propionate), then infected with Bacteroides fragilis, isolated from patients. Microscopy (bacterial staining with HEMA 3), qPCR, ELISA, TransEpithelial Electrical Resistance (TEER), and culturing were used to determine invasion potential, cytokine expression, barrier, and secretion.

Result(s)

FOS fermentation by microbes from IBD patients led to increased acetate and decreased butyrate production. Microbes from IBD patients were more proinflammatory, with increased IL-1ß secretion and reactive oxygen species generation, compared to those from non-IBD patients. B. fragilis isolated from an IBD patient was found to be a potential pathobiont with increased invasion and cytokine production in both epithelial and macrophage cells. Invasion was further increased when cells were exposed to SCFAs, particularly acetate and butyrate. Furthermore, the strain isolated from the IBD patient was observed (by microscopy) to be more adherent to the epithelial barrier, causing a loss of membrane integrity (TEER). The inflammasome pathway were significantly upregulated in Caco-2 cells infected with IBD-isolated B. fragilis and incubated with acetate or butyrate.

Conclusion(s)

The altered microbiome in IBD patients leads to an increased acetate and decreased butyrate, which likely affects host response to microbes and promotes inflammation. This changed microenvironment promotes the development of pathobionts, such as the identified B. fragilis strain we isolated from an IBD patient. The observation that acetate and butyrate increased host susceptibility to this strain indicates that understanding diet and SCFA production are instrumental in treating chronic conditions such as IBD. The role of diet as both a treatment and potential cause of inflammation in IBD is becoming more apparent; therefore, it is crucial that we understand the complex role diet has in host-microbe interactions.

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CIHR, Other

Please indicate your source of funding;

Mitacs- Weston Foundation

Disclosure of Interest

None Declared

A187 DIETARY FIBERS ELICIT GUT IMMUNE AND EPITHELIAL BARRIER MODIFYING EFFECTS IN INFLAMMATORY BOWEL DISEASES BASED ON FOOD SOURCE AND FIBER CHEMICAL FEATURES

Background

Dietary fibers are not digested in the bowel; they are fermented by microbes, typically promoting gut health. However, IBD patients experience sensitivity to consumption of fibers. Our previous findings offered the first mechanistic evidence demonstrating that unfermented dietary β-fructans (inulin and oligofructose) can induce pro-inflammatory cytokines and altered epithelial barrier integrity in a subset of pediatric IBD colonic biopsies cultured ex vivo, and in the SYNERGY-1 (β-fructan) clinical study of adult remission UC patients. Fermentation of β-fructan by whole-microbiota intestinal washes from non-IBD or remission IBD patients (but not non-IBD microbes) reduced pro-inflammatory responses.

Purpose

Here we aimed to expand our findings to uncover the physiologically relevant gut immune and epithelial responses to over 50 unfermented and partially fermented dietary fibers (arabinoxylans, β-glucans, β-mannans, galatooligosaccharides, inulins, oligofructoses, pectins, raffinooligosaccharides, xyloglucans) sourced from commonly consumed fruits, grains, and vegetables to better understand which foods are safe for IBD patients, and in which disease state settings.

Method

Colonic biopsies cultured ex vivo, peripheral blood mononuclear cells (PBMCs), colonic organoids, and cell lines were incubated with individual dietary fibers or mixture of fibers extracted from commonly consumed fruits, grains, and vegetables. Epithelial barrier integrity (TEER, microscopy, FITC-dextran) and immune responses (cytokine secretion [ELISA/MSD] and expression [qPCR]) were assessed. Structural features of the different fibers (e.g., degree of polymerization, phenolic/phytic content, branching, sugar content) were measured by HPLC and gas chromatography and correlated to host cell responses.

Result(s)

Most significantly unfermented inulin, oligofructose, and arabinoxylan induced pro-inflammatory responses, particularly in myeloid cells. Pectin and galatooligosaccharides were either non-inflammatory or anti-inflammatory depending on the food source. The epithelial barrier response to select dietary fibers correlated more significantly with the chemical properties of the fibers; longer fibers (greater degree of polymerization; e.g., inulin) displayed improved barrier integrity while shorter dietary fibers with higher phenolic content displayed reduced barrier integrity. Fiber structural properties varied significantly between different fiber subtypes along with the same fiber subtype sourced from different foods.

Conclusion(s)

Our findings suggest that intolerance and avoidance of fibers in select IBD patients occurs in patients whose gut microbiota do not support fermentation of fibers resulting in increased presence of unfermented dietary fibers in the gut. Here we show which specific dietary fibers from specific food items can elicit gut barrier damage and inflammation in the gut dependent on fiber structural features, suggesting mechanisms underlying IBD patient avoidance of specific high-fiber foods.

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Other

Please indicate your source of funding;

Weston Family Foundation, MMSF, NSERC, CRC

Disclosure of Interest

None Declared

A171 INTESTINAL INTERFERON-LAMBDA RECEPTOR 1 EXPRESSION AND RESPONSES ARE SIGNIFICANTLY DECREASED IN PEDIATRIC INFLAMMATORY BOWEL DISEASE PATIENTS

Background

While interferon-lambdas (IFN-λs) were initially discovered for their role in antiviral immunity at mucosal barriers such as the lung and gut, there are many unanswered questions for how IFN-λs uniquely dampen inflammatory immune responses. In mouse colitis models, IFN-λs were shown to play a significant role in promoting epithelial barrier integrity and mucosal healing. Microbes present in the gut naturally induce IFN-λs, but how chronic inflammation, such as in patients with inflammatory bowel diseases (IBD), affects IFN-λ biology has not been well studied, especially in humans.

Purpose

Here, we tested the hypothesis that children with active, more severe IBD would present with lower intestinal IFN-λR levels and IFN-λ responses which could contribute to IBD pathology through exacerbated inflammation, decreased mucosal healing and impaired barrier function.

Method

We screened 14 novel antibodies to find the optimal clone that accurately stains the unique IFN-λ receptor subunit (IFN-λR1) protein in human intestinal tissue and IFN-λR1 levels were quantified by immunohistochemistry and flow cytometry in biopsy samples from children without IBD, Crohn’s disease, or ulcerative colitis (n=35 total). Fresh patient biopsies (ascending colon or terminal ileum) were also treated in media +/- IFN-λ for 24hrs using our novel ex vivo biopsy assay and changes in gene expression were quantified by RT-qPCR. Intestinal washes were also collected and microbes profiled by shotgun metagenomics.

Result(s)

We identified 2 new antibodies that accurately stained human cell lines and immune cells known to express IFN-λR1 protein (gut epithelial cells and B cells). We found that IFN-λ receptor (IFN-λR) levels are significantly reduced in gut epithelial and immune cells within pediatric IBD intestinal tissue, even at non-inflamed sites (p<0.01, 30-50% reduction) and this was even more pronounced when comparing moderate/severe disease compared to children with no disease activity. This led to lower IFN-λ responsiveness in IBD compared to non-IBD biopsies when investigating IFN-stimulated gene expression (p<0.05, up to 7-fold reduction). Paired patient gut microbe analyses identified specific species that correlated with changes in IFN-λ receptor expression.

Conclusion(s)

Together, our findings demonstrate pediatric IBD patients may be less able to induce critical IFN-λ-mediated antimicrobial responses and protective anti-inflammatory pathways. This work supports the goal to restore and promote IFN-λ responses as a novel therapeutic strategy for pediatric IBD.

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Other

Please indicate your source of funding;

Children's Hospital Research Institute of Manitoba

Disclosure of Interest

None Declared

A98 ASSOCIATIONS BETWEEN DISTANCE TO CLINIC AND PATIENT CHARACTERISTICS FOR YOUNG ADULTS WITH IBD AT THE TIME OF PEDIATRIC TO ADULT TRANSFER OF CARE

Background

Patients with inflammatory bowel disease (IBD) in childhood are a vulnerable population. Compared to patients diagnosed in adulthood, they may present more often with extensive disease, delayed growth, and more frequently have perianal disease. Eventually, these patients will transfer care from the pediatric to the adult system, which has been associated with medication nonadherence and increase in health care utilization. Within the literature, travel distance has been cited as a barrier to accessing health care; however, understanding its’ impact on this vulnerable patient population has not been well-established.

Purpose

The study objective was to characterize differences between patients transferring from pediatric to adult care based on distance from an IBD center. To achieve this, the study aims to measure associations between distance to clinic and smoking status, anxiety and depression, history of surgery, and biologics at the time of first appointment in adult care.

Method

A retrospective cross-sectional study is ongoing using electronic medical charts for patients who transferred from pediatric to adult care from January 1, 2014 – October 4, 2022. Transfer was defined as the patient’s first appointment in adult care at the University of Alberta’s IBD clinic. Distance was measured by driving distance from the patient’s postal code to the postal code of the IBD clinic. Distance was categorized as being <50km from IBD clinic and >50km. Binary outcome variables collected at time of transfer included reported biologic use, anxiety and depression, smoking status, and history of surgeries. Descriptive and inferential statistics were used to analyze data.

Result(s)

Of the 185 electronic medical charts were reviewed, 46 (24.9%) patients lived >50km from clinic. The median age at diagnosis for the >50km group was 14.5 (IQR: 15.9-13.6), 41% were female sex, 54% had Crohn disease, 41% had ulcerative colitis (UC), and 26% had completed a fecal calprotectin within the last 6 months. The median age at diagnosis of the 139 patients living <50km from clinic was 14.3 (IQR:15.9-12.5), 45% were female sex, 60% had Crohn disease, 32% had UC, and 59% had completed a fecal calprotectin. Of those who had a fecal calprotectin, in group 1, 26% had a result over >250 ug/g, compared to 60% in the reference group. Univariate analysis (Table 1) showed that those living further than 50 km were more likely than those closer to engage in daily smoking (OR~4.7). Weaker and lack of associations were seen with anxiety and depression (OR~1); being on biologics (OR~0.7); history of surgical intervention (OR~2.2).

Image

Conclusion(s)

When smoking status was reported, patients > 50km away from clinic were 4.7 times more likely to engage in daily smoking at time of transfer compared to those patients within 50km from the clinic. By acknowledging and understanding potential differences and similarities between patients characterized by geographical location, we can use this research to inform personalized care plans.

Disclosure of Interest

None Declared

A199 BIOFILMS IN THE APPENDIX AND OTHER NON-INFLAMED SECTIONS OF THE COLON IN PEDIATRIC PATIENTS WITH INFLAMMATORY BOWEL DISEASES

Background

Biofilms, aggregated bacteria colonizing the extracellular polymeric substances matrix, are associated with the mucosa of inflammatory bowel diseases (IBD) patients with some studies showing a mean density of the mucosal biofilms 2-fold higher in IBD patients than in controls. The appendix, which is a highly immune organ, seems to be involved in IBD pathogenesis.

Purpose

In this study we aimed to evaluate biofilms in the appendix and other non-inflamed regions of the colon in pediatric IBD patients. We hypothesized that biofilms composed of pathobionts in these sections could drive inflammation in IBD patients.

Method

Tissues from the appendix, peri-appendicular region, cecum, and ascending colon (ASC), collected from the resected colons of 9 pediatric IBD patients and one pediatric non-IBD patient, preserved in methanol Carnoy’s solution were processed and paraffin embedded. Combined fluorescence in situ hybridization (FISH) for biofilms (probe: EUB338) and immunofluorescence (IF) mucin staining (MUC2) identified biofilms and their location. Biofilm formation capacity of culturable bacteria (identified through 16S DNA Sanger sequencing) from these sections was measured. Interleukin (IL)-8 (pro-inflammatory chemokine) and IL-10 (anti-inflammatory cytokine) expressions were assessed by tissue qPCR.

Result(s)

FISH demonstrated biofilms in these sections, in close proximity to epithelial cells. We used a biofilm formation assay to assess the ability of the identified bacteria from these sections to form biofilms, illustrating their potential to colonize and evade host defense and potential antibiotics. We found that Enterococcus avium has a significantly higher ability to form biofilms than the negative control. IL-8 and IL-10 both had the highest expression level in the appendix and peri-appendicular region and the lowest in the ASC among all the patients, suggesting an active immune response. Mechanistic experiments are in progress to investigate the type of bacteria involved in the biofilms and their effects on the gut barrier integrity.

Conclusion(s)

Biofilms adjacent to the epithelium, especially in the appendix and peri-appendix, could interact with or invade epithelial cells. The elevated chemokine transcript level in the appendix could reflect the recruitment of immune cells to this section following bacterial invasion, resulting in the activation of the immune system. Identifying the bacteria involved in the biofilms and clarifying their characteristics will aid us in developing novel microbe-altering treatment strategies or personalized medicine.

Disclosure of Interest

None Declared

A237 VIRULENCE POTENTIAL OF BACTERIA ISOLATED FROM NON-INFLAMED COLON IN PATIENTS WITH INFLAMMATORY BOWEL DISEASES

Background

As inflammation can impact microbes, our lab has focused on non-inflamed bowel sections of patients with inflammatory bowel diseases (IBD) and found bacterial alterations in the terminal ileum. We are also interested in the appendix given the involvement of the peri-appendicular region and effects of appendectomy in ulcerative colitis.

Aims

In this study, we aimed to identify and evaluate microbes from the appendix and non-inflamed regions of the colon in IBD patients. We hypothesized that microbes originating from the non-inflamed sections of the colon or appendix are more invasive and could trigger inflammation in IBD patients.

Methods

16S DNA Sanger sequencing was performed on bacteria, aerobically and anaerobically cultured from tissues of the appendix, peri-appendicular region, cecum, and ascending colon, collected from the resected colons of 5 pediatric IBD patients. The invasive capacity of the identified bacteria was evaluated by gentamicin protection assays on Caco-2 intestinal epithelial cells in vitro. Presence of select invasive or adhesive genes in the bacteria was assessed by PCR.

Results

Escherichia coli was the most frequently cultured species in the aerobic cultures; additional aerobic species included Enterococcus and Klebsiella. Bifidobacterium and Erysipelatoclostridium were identified among the anaerobic cultures. Gentamicin protection assays indicated that Klebsiella isolated from the peri-appendicular region was significantly more invasive (mean ~3000 CFU/ml) than HB101 (~1000 CFU/ml; non-invasive control; P<0.05). Enterococcus avium and Enterococcus faecalis were also more invasive than HB101 in the peri-appendicular region (~10000 CFU/ml) and cecum (~4000 CFU/ml; P<0.05), respectively. E. coli isolated from the appendix showed a higher invasive potential (~3000 CFU/ml) than E. coli isolated from other sections. Additionally, PCR showed that E. coli obtained from different sections, except the ascending colon of one the patients, had the fimH gene while the other types of bacteria did not. None of the isolated bacteria had Hemolysin ( hlyA) or attaching and effacing ( eaeA) genes.

Conclusions

Bacteria, especially E. coli, from non-inflamed bowel in IBD (including the appendix) appear to have increased invasive potential. This suggests that the microenvironment in these regions could be altered, resulting in increased invasion of bacteria or the gut harboring more invasive microbial populations in IBD patients. As a result, inflammation could be triggered or exacerbated through this reservoir of pathobionts.

Funding Agencies

CIHR

A176 UTILITY OF MACHINE LEARNING FOR SERUM METABOLOMIC DATA ANALYSIS IN PEDIATRIC CROHN DISEASE

Background

The pathogenesis of pCD remains poorly understood, but evidence suggests roles for genetics, environment, immune response, and gut microbes. Microbial changes can contribute to chronic inflammation and correlate with disease severity. Metabolomics reflects interactions between host immune and gut microbial function by quantifying compounds in biological samples. Therefore, metabolomics provides a unique opportunity to gain insight into pCD pathogenesis.

Aims

To correlate disease severity, metabolites, and clinical data by applying machine learning algorithms in pediatric Crohn Disease (pCD).

Methods

ImageKids is a multicenter, prospective, cohort observational study, conducted to develop magnetic resonance enterography (MRE) indices for pCD. Paired serum specimens were collected at study initiation (Visit One; V1) and completion (Visit Four; V4; 18 months) for 120 pCD patients. Serum from patients with representative clinical scenarios and paired samples was analyzed at The Metabolomics Innovation Centre (TMIC; University of Alberta) and 131 metabolites were identified. Metabolites were analyzed via Unsupervised (U.ML) and Supervised (S.ML) Machine Learning algorithms based on Scikit-learn library in Python. Principal Component Analysis (PCA) was used to identify the variation pattern of the patients’ metabolome. Classifiers and regression algorithms were trained to assess correlation with disease activity.

Results

Results were available for the 56 paired samples. U.ML demonstrated distinct metabolome profiles with V1 clustering mainly attributed to aspartic acid, glutamic acid, and kynurenine. V4 clustering was mainly attributed to spermidine, spermine, total dimethylarginine. Furthermore, demographics was found as an important environmental factor driving distinct patterns of the metabolomics profile.

After training different classifiers and regressors with S. ML algorithms, metabolome data were correlated with disease severity (defined by C-reactive protein and fecal calprotectin). Isoleucine, p-hydroxyhippuric acid, and putrescine were the top three compounds associated with disease severity. The accuracy of our classification models was of 80% and the coefficient of determination of our regression models was 0.5

Conclusions

Metabolomic analysis can provide insight into disease pathogenesis and help predict disease severity among pCD patients. The correlation between metabolomics and disease severity might allow a better understanding of changes in host-microbe interactions and introduce new diagnostic or therapeutic options.

Funding Agencies

CIHR

A50 IMPACT OF SHORT CHAIN FATTY ACIDS ON PATHOGENICTY OF COMMENSAL BACTERIA IN PEDIATRIC INFLAMMATORY BOWEL DISEASES

Background

Dietary fibers are fermented by microbiota into many different compounds including short-chain fatty acids (SCFA). The gut microenvironment is essential not only for human health but also in maintaining a rich biodiversity of bacterial species. It is well known that the microbiome is altered in Inflammatory Bowel Diseases (IBD), which likely changes the microenvironment and has other health effects on individuals with IBD. Pathobionts are organisms that can induce pathology under specific conditions, and several have already been associated with IBD, such as adherent invasive Escherichia coli (AIEC) and Helicobacter hepaticus. Although these bacteria have been associated with IBD, it is still largely unknown what conditions make these bacteria become pathogenic.

Aims

Determine the role of SCFA composition on the pathogenic potential of commensal bacteria isolated from non-IBD and IBD pediatric patients.

Methods

Anaerobic bacteria were isolated during colonoscopy from pediatric IBD and non-IBD patients and identified using 16S sequencing. PMA-activated human monocytes (THP-1) and colonic epithelial cells (Caco2) were grown in the presence of SCFA (acetate, butyrate, formate, propionate, and succinate). The ability of commensal bacteria ( Bacteroides fragilis, Clostridium innocuum, Ruminococcus, Parabacteroides merdae, Bifidobacterium infantis and E. coli HB101) and the pathobiont AIEC to invade cells was assessed using a gentamicin protection assay. Immune activation was quantified with IL-1b and IL-6 by ELISA, as well as reactive oxygen species (ROS) using DCFDHA.

Results

The SCFA propionate and formate significantly decreased invasion for HB101 and LF82 into macrophages but not epithelial cells. Bacteria isolated from an IBD environment had a higher invasion potential independent of the addition of SCFA, compared to bacteria from a non-IBD environment. However, butyrate was found to significantly increase invasion of non-IBD B. fragilis into Caco2 cells but not macrophages. Bacteria isolated from IBD patients tended to have a higher inflammatory response with both elevated IL-1b as well as ROS production.

Conclusions

Microenvironment changes, such as in SCFA concentrations, during a disease state can affect the host response to microbes including commensals. Commensal bacteria from IBD patients tend to be more proinflammatory, suggesting that they play a role in driving inflammation. SCFA are beneficial factors for gut health; however, what is still unknown is the interaction between microbes and the host after microenvironmental shifts that likely causes bacterial stress. Understanding the host-microbe interactions and the role diet can have on this dynamic relationship has the potential for discovering new therapeutic options for those suffering from IBD.

Funding Agencies

CIHRWeston Family Foundation

A65 PREDICTING TRANSITION SUCCESS IN YOUNG ADULTS WITH INFLAMMATORY BOWEL DISEASE: PRELIMINARY RESULTS

Background

Patients diagnosed with inflammatory bowel disease (IBD) in childhood present more often with extensive disease, are more likely to be admitted to hospital and are less adherent with clinic appointments. Due to these risks, a smooth, uninterrupted transition from pediatric to adult care should be a priority. We have conducted interviews with providers, patients, and parents about their opinions on indicators of successful transition. Themes of successful transition that emerged included independence in seeking care and disease management. Characterizing successful transition based on stakeholder input makes it possible to monitor its achievement and identify its determinants.

Aims

This study aims to: 1) describe the frequency of success indicators in transitioned patients and 2) identify predictors associated with success indicators. We hypothesize that patients with more experience in pediatric care (e.g., younger age at diagnosis or on biologics) are more likely to achieve success.

Methods

We conducted a retrospective medical chart review to obtain data on patients who transitioned to adult care between January, 2014 - September, 2019 at the University of Alberta. We abstracted potential predictors, including social and disease factors, at first adult appointment which had notes on pediatric history. We chose available success indicators related to two themes: independence in seeking care (e.g., attending appointments, communicating for oneself) and disease management (e.g., lab work frequency and medication adherence). We abstracted selected success indicators within a two-year period from first appointment in adult care. We used Poisson and logistic regression to estimate incidence rate ratios (IR) and odds ratios (OR) for the association of potential predictors with success indicators.

Results

We reviewed medical charts of 99 patients. At first adult appointment, the median age at diagnosis was 14.5 years old (IQR: 13.2 – 15.9) and 57.6% of patients were on biologic agents. Within two years, 42.4% of patients required a change to a different therapy, 22.2% had at least two instances where a parent called on their behalf, and 16.2% had notes of medication nonadherence in adult care. Regression analysis (Table 1) estimated that patients who lived > 100km from clinic had a lab work incidence rate in the first year that was two-thirds that of patients who lived closer. Strong predictors of non-adherence in adult care included chart notes on pediatric medication non-adherence (OR~12) and, inversely, taking biologics (OR=0.34).

Conclusions

These results identified factors that could be used to identify patients likely to have poor outcomes following transition to adult care. These are preliminary results; we plan to analyze a total of 350 medical charts.

Funding Agencies

None

A47 MICROBIAL FUNCTIONS AS BIOMARKERS OF PRO-INFLAMMATORY RESPONSE TO SELECT DIETARY FIBERS IN IBD

Background

Dietary fibers are not digested in the bowel; they are fermented by microbes, typically promoting gut health. However, IBD patients experience sensitivity to consumption of fibers. Our previous findings offered the first mechanistic evidence demonstrating that unfermented dietary β-fructans (inulin and FOS) can induce pro-inflammatory cytokines in a subset of pediatric IBD colonic biopsies cultured ex vivo, and in the SYNERGY-1 (β-fructan) clinical study of adult remission UC patients. Incubating FOS with whole-microbiota intestinal washes from non-IBD or remission IBD patients improved fermentation and reduced pro-inflammatory responses, but not from patients with active disease. Fibre-induced immune responses correlated with microbe functions, luminal metabolites, and fibre avoidance.

Aims

Here we aimed to expand on our findings and define the role of microbial functions in mediating host response to β-fructans.

Methods

Colonic biopsies cultured ex vivo and cell lines in vitro were incubated with FOS (5g/L), or fermentation supernatants (24hr anaerobic fermentation). Immune responses (cytokine secretion [ELISA/MSD] and expression [qPCR]) were assessed. Taxonomic classification of microbial fermentation cultures was conducted with Kraken2 and metabolic profiling by HUMAnN2. HPLC and gas chromatography volatile fatty acid (CG-VFA) analysis were used to identify concentrations of remaining fibre and SCFAs following anaerobic fermentation.

Results

7 microbial enzymes were identified to be predictive of cytokine (IL-1β, IL23, IL-5, IL-8, MIP-1α) secretion in ex vivo colonic biopsies from pediatric Crohn disease (CD; n=38), ulcerative colitis (UC; n=20), and non-IBD (n=21) patients, in response to β-fructans; their use as biomarkers of response was determined in patient stool from the SYNERGY-1 clinical study cohort. Fermentation of FOS by whole-microbe intestinal washes from only non-IBD or remission IBD patients reduced cytokine secretion, and our findings demonstrate that this was due to a combination of reduction of β-fructan present and production of a precise combination of anti-inflammatory SCFAs.

Conclusions

Our findings suggest that intolerance and avoidance of fibers in select IBD patients is associated with the inability to ferment these fibers, mediated by altered microbial functions (enzymes), leading to worsened inflammation. Data indicate that gut microbial function, not composition, predicts patient pro-inflammatory response to β-fructans, supporting our hypothesis that overall community function impacts fibre fermentation and affects associated pro-inflammatory effects. Our work highlights select disease state scenarios in which administration of fermentable fibers should be avoided and tailored dietary interventions considered.

Funding Agencies

CIHRWeston Foundation, Mitacs

The Phenotypic Spectrum of New-onset IBD in Canadian Children of South Asian Ethnicity: A Prospective Multi-Centre Comparative Study

BACKGROUND

Canadian-born children of South Asian [SA] ethnicity develop inflammatory bowel disease [IBD] at similar rates to those among Caucasian children. We evaluated the variation in phenotypic spectrum of IBD in SA and Caucasian children in a national paediatric inception cohort of new-onset IBD.

METHODS

Patients aged <17 years, enrolled in a Canadian nationwide inception cohort study, were included. Baseline demographic and IBD phenotypic features were compared between SA and Caucasian children. Longitudinal outcomes through 18 months of follow-up were compared matched by propensity scores.

RESULTS

Of 1156 children enrolled over 2014 to 2019, 623 were Caucasian [98% and 88% parents Canadian born] and 114 SA [79% Canadian born, 87% parents SA born]. Fewer SAs have a first-degree relative with IBD, 6% vs 19% in Caucasians, p = 0.002. SAs present at a younger age, median age 11.4 years (interquartile range [IQR] 9.2-14.3) vs 13 years [IQR 10.9-15 years], p = 0.03 and more commonly with a UC/IBD-U [ulcerative colitis/IBD-unclassified] subtype [ratio of UC/IBD-U to CD 1.2:1 vs 1:1.8 for Caucasians, p <0.001]. Additionally, a greater proportion of SA CD patients present with colonic-only disease [colonic-only CD/UC/IBD-U in SAs 67% vs 57% for Caucasians, p = 0.001], and among those with CD, colonic CD in SAs 31% vs 23% in Caucasians, p = 0.20]. Perianal fistulising disease was also numerically more common in SAs (14 [27%] vs 64 [18%], p = 0.06]. Adjusting for differences in phenotypic presentation, anti-tumour necrosis factor [TNF] exposure, and time to initiation was similar, and two-thirds of children, whether anti-TNF exposed or naïve, were in corticosteroid-free clinical remission at 18 months irrespective of ethnicity.

CONCLUSIONS

The phenotypic spectrum of new-onset IBD in SA children differs from that of Caucasian children, but treatment and clinical course are similar within phenotypic subgroups.

A190 ATP-INDUCED INFLAMMASOME ACTIVATION GENERATES MITOCHONDRIAL ROS PRODUCTION IN MACROPHAGES

Background

The etiology of Inflammatory Bowel Diseases is unknown; however, a dysfunctional immune response has been well characterized. The role of the NLRP3 inflammasome in IBD is controversial with both beneficial and detrimental results. This pathway is required for the secretion of the proinflammatory cytokine IL-1β. Extracellular ATP is a well characterized inflammasome activator, which we have previously shown can increase the ability of J774A.1 macrophages to clear the mouse pathogen Citrobacter rodentium in an in vitro environment through the generation of reactive oxygen species (ROS).

Aims

Our objectives were to determine: 1) if extracellular ATP was inducing mitochondrial stress, causing the production of ROS, leading to microbial death; and 2) what effects these activated macropahges have on naïve macrophages.

Methods

Murine macrophage J774A.1 cells were infected with C. rodentium; extracellular ATP was added as an inflammasome activator and YVAD as an inhibitor. Lysotracker red and MitoSOX were used to determine cellular location of bacteria and quantify mitochondrial ROS, respectively. Secreted cytokines were measured using ELISA and a proteome profiler, ROS was measured using DCFDA, Gasdermin D and Caspase 11 activities were determined by Western Blot. Supernatants taken from infected macrophages were filtered and then added to naïve macrophages during infection with C. rodentium.

Results

Activation of mitochondrial ROS by ATP was found to be independent of infection. Secreted cytokines sICAM-1, MIP-1α, and MCP-2 were all increased by ATP but not inhibited by YVAD. Cleavage of Gasdermin D was increased with the addition of ATP but not inhibited by YVAD whereas Caspase 11 was unchanged between treatments. Supernatants from ATP-induced macrophages were able to induce IL-1β secretion in naïve macrophages and increase bacterial killing.

Conclusions

Mitochondrial ROS production in response to extracellular ATP may be involved in the decrease of bacterial survival. ATP induces the secretion of cytokines, chemokines, and other factors that affect newly infected macrophages. Gasdermin D cleavage, independent of caspase 11, suggests that a noncannonical pathway is activated; this may explain the lack of pyroptotic cells in our study. In addition, we have shown that these macrophages are able to illicit the same behavior in naive macrophages, suggesting that a corrected dysfunctional pathway in macrophages can have beneficial effects downstream. Understanding how the NLRP3 inflammasome is activated and what the downstream pathways are may lead to potential therapies for inflammatory conditions, including IBD.

Funding Agencies

CCC, CIHR

A98 DEFINING TRANSITION SUCCESS ACCORDING TO YOUNG ADULTS WITH INFLAMMATORY BOWEL DISEASE

Background

The incidence of childhood-onset inflammatory bowel disease (IBD) diagnoses is increasing in Canada; therefore, more patients will need to transition from pediatric into adult care. The literature on transition in IBD patients has focused mainly on preparation and while transition success is often referenced, it is not clearly defined. Prior research on IBD transition success has only focused on the perspectives of the health care providers. Taking into consideration that transition is a process that greatly relies on patient involvement, patient perspectives should be represented in defining its success.

Aims

The primary aim is to understand patients’ perspectives on the outcomes that characterize a successful transition from pediatric to adult care.

Methods

This study paired a theoretical position of naturalistic inquiry with the method of qualitative description. Purposive sampling was used to recruit patients from IBD clinics at the University of Alberta and the University of Calgary. Inclusion criteria included transition within the last two years, diagnoses with IBD for at least a year prior to transitioning, and absence of comorbidities. Virtual semi-structured interviews were conducted using an established interview guide. Interviews were transcribed verbatim and then analyzed concurrently with data collection by latent content analysis using NVivo computer software. Participant recruitment and data analysis continued until no further themes emerged from the data, which signaled that thematic saturation was achieved.

Results

Thematic saturation was achieved after 17 interviews. Among participants, 58.8% were female; 47% had a diagnosis of Crohn’s, 47% of ulcerative colitis, and one individual was diagnosed with both. The median age at diagnosis was 15 years (IQR, 3.5). The majority (94%) of participants viewed their transition as being successful. Overall, the major themes that emerged from the data were: 1. relationship with one’s adult care team, characterized predominantly as the patient being comfortable with their new team; 2. health outcomes, characterized by disease remaining stable, and medication adherence; 3. independence in one’s care, characterized by making and attending appointments on their own, asking questions and in general having an awareness about your health and disease; 4. care stability, characterized by no drop off in care, and regular contact and follow up by their provider.

Conclusions

Young adults with IBD define pediatric transition success in four themes: relationship with care team, health outcomes, independence in one’s care, and care stability. Through understanding what transition success looks like from the patients’ perspectives, health care providers can help patients achieve success as they define it.

Funding Agencies

None

A189 ELUCIDATING THE MECHANISTIC ROLE OF GLP-1R IN THE INFLAMMATORY RESPONSE OF MACROPHAGES AND B CELLS TO DIETARY FIBRES

Background

Both diet and the microbiome have been implicated in the pathogenesis of inflammatory bowel diseases (IBD). Fibre is not digested; it is fermented by microbes in the large bowel. High fibre intake is related to lower risk for the development of IBD, and a high fibre diet is usually recommended for individuals with IBD. However, work in our lab suggests that select dietary fibres may be pro-inflammatory in a pediatric IBD cohort. Importantly, large bowel dysbiosis in IBD could limit the fermentation of dietary fibres, leading to reduced production of beneficial microbiome metabolites as well as an accumulation of intact fibre in the large bowel. These intact fibres may then interact with immune cells residing in the large bowel, through specific receptors, and perpetuate the inflammatory state seen in IBD.

Aims

Based on preliminary findings, we hypothesize that the dietary fibre oligofructose acts through GLP-1R on macrophages and B-cells to regulate the inflammatory environment. We expect to find changes in the expression of cytokines and chemokines, and their receptors.

Methods

Changes in immune cell secretions (ELISA) and the expression of selected inflammatory markers (RT-qPCR) were measured to determine potential pathways involved in response to dietary fibres in vitro. Knockdown of proteins of interest (siRNA) was performed to validate the involvement of these pathways in the inflammatory response to dietary fibres. Cells were treated with oligofructose, oligofructose pre-fermented by bacteria, or no fibre. The involvement of the fibre receptor, GLP-1R, was investigated to understand its connection to pathways identified.

Results

Qiagen RT2 profiler array (human inflammatory cytokines and receptors) and cytokine secretion (ELISA) indicated that in response to oligofructose macrophages have a predominantly pro-inflammatory response while B cells have an anti-inflammatory response. Presence of GLP-1R in large bowel and terminal ileum biopsies collected during endoscopy was higher in IBD (Crohn disease n=7; Ulcerative colitis n=7) than non-IBD patients (n=7), and expression was confirmed on both B-cells and macrophages. Knockdown of GLP-1R (siRNA) significantly reduced the pro-inflammatory response (IL-1β ELISA) with oligofructose application in THP-1 macrophage cells

Conclusions

Improving our understanding of the mechanistic link between dietary fibres and immune response will aid us in developing a model for the interactions of oligofructose with the GLP-1R in B cells and macrophages. Findings from this study may be able to inform dietary interventions, prebiotic/probiotic administration, and drug development for treatment of IBDs.

Funding Agencies

CIHRWeston Foundation

A41 LINKING THE APPENDIX MICROBIOME WITH INFLAMMATORY BOWEL DISEASES

Background

The appendix has been shown to be associated with the pathogenesis and health outcomes in inflammatory bowel diseases (IBD). Specifically, post appendectomy patients are found to be protective for development of ulcerative colitis (UC); however, mechanisms of appendix involvement remain unclear.

Aims

Our aim is to examine the microbes associated with the appendix of IBD patients by identifying changes in microbe abundance and interactions with the host in patient cecum luminal washes, collected from close to the neck of the appendix during colonoscopy. We hypothesize that microbes originating in the appendix of IBD patients, through interactions with host-cells in a disrupted microenvironment in the appendix, could contribute to the pathogenesis of UC.

Methods

Shotgun metagenomics was performed on cecum luminal washes of IBD patients and non-IBD controls. Guided by the metagenomic results, we performed gentamicin protection assays to determine virulence of microbes of interest using Caco2 intestinal epithelial cells. Co-culturing them with human host cells in vitro will identify relevant disease-related factors secreted by microbes and/or host cells using disease models and multiomic approaches.

Results

Shotgun metagenomics results showed that among numerous microbes, several bacterial taxa demonstrated differences in abundance between IBD and non-IBD patients: Flavonifractor, Bacteroide fragilis, and Alistipes represented 8%, 10%, and 21% abundance respectively in non-IBD patients, while in IBD patients they were present below 0.1%. In contrast, Bacteroide vulgatus and Escherichia coli were about 9% and 69% respectively, in IBD patients, whilst they were present at 1.7% and 1.2% in non-IBD patients, respectively. Following our recent method for validating pathobionts (Armstrong, 2019), we used the gentamicin protection assays to assess the ability of these bacteria to invade Caco2 cells, demonstrating a correlation between invasive potential of these microbes and cecal abundance. Mechanistic experiments, aimed at identifying factors impacting invasion, are in progress.

Conclusions

These results provide preliminary, but promising findings suggesting mechanisms by which microbiota possibly originating in the appendix may show altered virulence, which may be related to changes in the appendix microenvironment in IBD. With plans in place to increase our patient cohort we will validate these findings. Identifying and profiling these microbes in IBD patients can help improve the understanding of mechanisms underlying microenvironment changes within the appendix and the gut, which could shed light on the role of the appendix in IBD pathogenesis and clarify how microbes drive inflammation in IBD.

Funding Agencies

CIHR

A31 COMPLEX ROLE OF DIETARY FIBERS IN IBD: MICROBES MEDIATE FIBER-INDUCED INFLAMMATION

Background

Dietary fibers pass through the bowel undigested and are fermented within the intestine by microbes, typically promoting gut health. However, many IBD patients describe experiencing sensitivity to fibers. β-glucan, found on the surface of fungal cells during fungal infection, has been shown to bind to fiber receptors, such as Dectin-1, on host immune cells, resulting in a pro-inflammatory response. These fungal fibres share properties with dietary fibers.

Aims

As an altered gut microbial composition has been associated with IBD, we hypothesized that the loss of fiber-fermenting microbes populating the gut in IBD could lead to dietary fibers not being efficiently broken down into their beneficial biproducts (e.g. short chain fatty acids; SCFA), resulting in binding of intact fibers to pro-inflammatory host cell receptors.

Methods

Immune and epithelial cell lines and colonic biopsies cultured ex vivo were incubated with oligofructose or inulin (5g/L), or pre-fermented fibers (24hr anaerobic fermentation). Immune responses were measured by cytokine secretion (ELISA), and expression (qPCR). Barrier integrity was measured by transepithelial resistance (TEER). Food frequency questionnaire (FFQ) data of patient fiber consumption were correlated with gut microbes (shotgun sequencing) and immune responses to fiber in patient biopsies.

Results

Unfermented oligofructose induced IL-1β secretion in leukocytes (macrophage, T cell, neutrophil) and in colon biopsies from pediatric Crohn disease (CD; n=38) and ulcerative colitis (UC; n=20) patients cultured ex vivo, but not in non-IBD patients (n=21). IL-1β secretion was greater in patients with more severe disease. Pre-fermentation of oligofructose by whole-microbe intestinal washes from non-IBD patients or remission patients reduced secretion of IL-1β, while whole microbe intestinal washes from severe IBD patients were unable to ferment oligofructose or reduce cytokine secretion. Fiber effects on IL-1β secretion in biopsies positively correlated with effects on barrier integrity in T84 cells. Fiber-associated immune responses in patient biopsies cultured ex vivo (ELISA) correlated with fiber avoidance (FFQ) and gut microbiome (sequencing) in matching patient samples.

Conclusions

Our findings demonstrate that intolerance and avoidance of prebiotic fibers in select IBD patients is associated with the inability to ferment these fibers, leading to pro-inflammatory immune responses and intestinal barrier disruption. This highlights select disease state scenarios, in which administration of fermentable fibers should be avoided and tailored dietary interventions should be considered in IBD patients.

Funding Agencies

CIHRWeston Foundation

Phenotypic Variation in Paediatric Inflammatory Bowel Disease by Age: A Multicentre Prospective Inception Cohort Study of the Canadian Children IBD Network

BACKGROUND AND AIMS

Incidence of paediatric inflammatory bowel disease [IBD] in Canada is among the highest worldwide, and age of onset may be decreasing. In a multicentre nationwide inception cohort study, we examined variation in phenotype of IBD throughout the paediatric age spectrum.

METHODS

Children aged ≥2 years [y] and <17y [A1 age at diagnosis], with new onset IBD, were systematically evaluated at sites of the Canadian Children IBD Network. Prospectively recorded phenotypic data were compared between age groups.

RESULTS

Among 1092 children (70% Caucasian; 64% Crohn's disease [CD], 36% ulcerative colitis/inflammatory bowel disease unclassified [UC/IBD-U]; median age 13 y, interquartile range [IQR] 11-15 y), 210 [19%] were diagnosed before the age of age 10 y [Paris A1a] and 43 [4%] before age 6 y (very-early-onset [VEO-IBD]). CD was less common in younger children [42%, 56%, 66%, respectively, of VEO-IBD, A1a; A1b]. Colon-only IBD [UC/IBDU or CD-colon] was present in 81% of VEO-IBD and 65% of A1a; ileal disease increased progressively, reaching plateau at age 10 y. CD location was ileocolonic [L3] in 53% overall. Ileitis [L1] increased with age [6% of VEO-IBD; 13% of A1a; 21% of A1b], as did stricturing/penetrating CD [4% of A1a; 11% of A1b]. At all ages UC was extensive [E3/E4] in >85%, and disease activity moderate to severe according to Physician's Global Assessment [PGA] and weighted Paediatric Crohn's Disease Activity Index/Paediatric Ulcerative Colitis Activity Index [wPCDAI/PUCAI] in >70%. Heights were modestly reduced in CD [mean height z score -0.30 ± 1.23], but normal in UC/IBD-U.

CONCLUSIONS

Paris classification of age at diagnosis is supported by age-related increases in ileal disease until age 10 years. Other phenotypic features, including severity, are similar across all ages. Linear growth is less impaired in CD than in historical cohorts, reflecting earlier diagnosis.

A207 RIPK2 AND AMPK AS EMERGING THERAPEUTIC TARGETS FOR INFLAMMATORY BOWEL DISEASE

Background

Persistent inflammation can trigger altered epigenetic, inflammation and bioenergetics states. Inflammatory bowel disease (IBD) is a heterogeneous disease with an abnormal inflammatory state and subsequent metabolic syndrome disorder. Current IBD therapeutics are directed to inhibit inflammatory pathways, such as inflammation of the epithelial cells in the colonic crypts. We hypothesize that in order to achieve mucosal healing and to keep patients in remission we must (i) inhibit inflammatory mediators and (ii) resolve secondary effects of inflammation such a reset of metabolic dysfunction.

Aims

The aims of this study are to explore correlations between inflammation/metabolic markers and the severity of the disease to uncover emerging new therapeutic players.

Methods

More than one hundred patients were recruited and underwent colonoscopy. In order to explore how biomarkers change with disease and time, all patients had IBD for more than 10 years or less than 5 years. Those diagnosed with cancer, celiac sprue, or diabetes were excluded. The activity of key metabolic markers (such as AMPK) was tracked using phospho-specific antibodies. Immunohistochemistry and immunoblotting were carried out, as described by Gordon et al., PLOSone 2013. All patients were consented under our IBD ethics protocol (Pro00001523 and Pro00077868).

Results

Using intestinal biopsies from non-IBD, UC and CD patients, we explored the expression/activation levels of markers of inflammation (such as obligate NOD2 kinase RIPK2) and metabolism (AMPK) in order to gain insight into correlations with clinical severity of the disease. We confirm that the loss in the activity of AMPK occurs with a gain of activity of RIPK2 that drives the inflammatory phenotype of the gut in patients with long-standing IBD (&gt;10 years). (If inflammation is inhibited in a mouse model of IBD, metabolic reset occurs to regain AMPK and promote mucosal healing). However, RIPK2 remains elevated in patients that are currently on IBD therapeutics.

Conclusions

Therapeutics inhibiting inflammation (RIPK2) and stimulating metabolic (AMPK) drivers of the disease may be a useful combination therapy to completely eliminate inflammation, reset abnormal metabolism and achieve full remission in IBD patients with longstanding disease.

Funding Agencies

None

A217 DEFINING THE RELATIONSHIP BETWEEN DIETARY FIBERS AND INFLAMMATORY RESPONSE IN PEDIATRIC INFLAMMATORY BOWEL DISEASES

Background

The incidence rates of inflammatory bowel diseases (IBD), Crohn disease (CD) and ulcerative colitis (UC) are increasing in children. Although the etiology of IBD is poorly understood, factors such as urban lifestyle, diet, increased hygiene, and reduced microbial biodiversity have been implicated as risk factors. Compositional changes and reduced microbial biodiversity have been linked to therapy failure in pediatric IBD. Non-digestible dietary carbohydrates, such as fiber, must undergo fermentation by gut microbiota within the large bowel, producing short chain fatty acids (SCFAs). Animal studies have shown that dietary fibers can inhibit IBD-associated inflammation, and clinical trials have demonstrated that SCFAs can prevent intestinal atrophy and allow for tissue recovery in IBD patients. In disease settings with altered gut microbes, fermentation of dietary fibers may be greatly affected. Unfermented fibers interact with receptors on host immune cells and can induce proinflammatory immune response, production of oxygen species and inflammation, or an inhibition of proinflammatory receptors.

Aims

Based on this rationale, we hypothesize that dysbiosis in the IBD gut leads to decreased fiber fermenting microbes, resulting in reduced SCFA production. This contributes to increased inflammatory responses both in in vitro cell lines, as well as ex vivo patient biopsies. Because intact fibers can bind to host cell receptors, this promotes inflammatory response and continued dysbiosis.

Methods

To assess effects of intact fiber on immune cells, macrophage and T-cell in vitro cultures were used to measure cytokine response to inulin (5mg/mL) and oligofructose (5mg/mL) through ELISAs/qPCR. These cell lines and ex vivo patient biopsies were treated with whole fibers and IL-1β secretion was measured. Fibers were also pre-fermented with microbes of interest or whole microbe patient intestinal washes and used to treat cell lines and patient biopsies.

Results

Whole fibers induced a pro-inflammatory response in macrophage cells but not T-cells, and this pro-inflammatory response was mitigated by pre-fermenting the fibers. Intestinal washes from severe IBD patients were unable to successfully ferment oligofructose or reduce fiber-associated inflammation in macrophage cell lines, whereas washes from remission or non-IBD samples reduced IL-1β. Oligofructose was found to increase IL-1β secretion in UC and CD patient biopsies, but not in non-IBD specimens. This increase was also correlated with disease severity.

Conclusions

These results indicate that a lack of fiber-fermenting microbes and presence of whole fibers can lead to pro-inflammatory responses, both in cell lines and patient biopsies. However, the presence of appropriate fermenting microbes can reduce fiber-associated inflammation.

Funding Agencies

CCCWCHRI, Weston Foundation

A265 SERIAL FECAL MICROBIOTA TRANSPLANT PLUS FIDAXOMICIN IN THE TREATMENT OF SEVERE OR FULMINANT CLOSTRIDIOIDES DIFFICILE INFECTION

Background

Severe and fulminant Clostridioides Difficile infection(CDI) is associated with increased mortality and morbidity. Current guidelines recommend high dose vancomycin with metronidazole for treatment. Surgery is a high risk for patients failing medical therapy partly due to multiple comorbidities. Emerging evidence suggests efficacy of sequential fecal microbiota transplantation(FMT) by colonoscopy combined with vancomycin in patients failing maximal medical therapy. Fidaxomicin is non-inferior to vancomycin in treating CDI; however, it has not been studied in severe/fulminant cases. It is not known if FMT by enema combined with fidaxomicin is efficacious and safe in this patient population.

Aims

This single center, prospective, open-label pilot study aimed to determine the efficacy and safety of combined sequential FMT by enema plus fidaxomicin in severe or fulminant CDI not responding to maximal medical therapy. Primary outcome was resolution of diarrhea 2 weeks following final FMT. Secondary outcomes were resolution of diarrhea 8 weeks following final FMT, safety of proposed treatment protocol and colectomy rate.

Methods

Consecutive patients with severe or fulminant CDI, who fulfilled study inclusion criteria were recruited. Sequential cycles of FMT, administered by enema daily over three days(720cc followed by 360cc and 180cc), plus fidaxomicin 200mg PO BID were given. Clinical symptoms and inflammatory markers were monitored during the study and subsequent cycles of FMT were administered when clinical or biochemical improvement plateaued. A final FMT was administered with CDI resolution.

Results

A total of three patients were enrolled between Jan 22 to Aug 8, 2019, shown in Table 1. One patient had fulminant CDI due to shock, and the others had severe CDI. All had severe pseudomembranous colitis seen on endoscopy at enrollment. Two of three patients reached both primary and secondary outcomes with 2 FMT cycles. The only patient who did not reach the primary was successfully managed with long term vancomycin suppression. This patient had failed multiple FMTs prior to enrollment. There were no adverse events noted and no colectomy was required during this study.

Conclusions

This pilot study is the first to demonstrate efficacy and safety of combined sequential FMT by enema and fidaxomicin in treating severe or fulminant CDI patients. An adequately powered study is required to validate these findings.

Funding Agencies

CIHRAlberta Health Services, University of Alberta Hospital Foundation

A15 MICROBES MEDIATE FIBER-INDUCED INFLAMMATION IN IBD

Background

The etiology of inflammatory bowel diseases (IBD) remains unknown, although gut microorganisms and diet have been implicated. Dietary fibers pass through the bowel undigested and are fermented within the intestine by microbes, promoting gut health. However, many IBD patients describe experiencing sensitivity to fibres. Interestingly, fiber receptors on immune cells are able to interact with fibers typically found on the surface of fungal cells (which share properties with dietary fibers), for example, resulting in a paradoxical pro-inflammatory response.

Aims

As an altered microbial composition is a hallmark of IBD, we hypothesized that the loss of fiber fermenting-microbes populating the IBD gut could lead to dietary fibers not being efficiently broken down into their beneficial biproducts, resulting in binding of intact fibers to pro-inflammatory host cell receptors. This can ultimately drive pro-inflammatory responses and a microenvironment that promotes continued dysbiosis and increased pathogenicity of select microbes, as observed in IBD.

Methods

Fiber receptor expression gut was examined using immunohistochemistry and flow cytometry and demonstrated elevated receptor expression due to increased presence of immune cells in IBD patient biopsies. Cytokine secretion, in response to fiber (5mg/mL) or pre-fermented fibers, cultured with microbes of interest, was measured by ELISAs in cell lines in vitro and biopsy tissues cultured ex vivo.

Results

Whole-fibers induced pro-inflammatory cytokine production in macrophage, monocytes, and neutrophils. Specific microbes were capable of fermenting fiber, measured by gas chromatography. Pre-fermentation of fibers by these microbes reduced inflammatory cytokine production. The fiber oligofructose increased IL-1β in pediatric CD (n=44) and UC (n=29) biopsies cultured ex vivo but not in non-IBD (n=25). The increase was greater in patients with more severe disease. Pre-fermentation of oligofructose by bacteria reduced this secretion of IL-1β. Whole-microbe intestinal washes from severe IBD patients were unable to ferment oligofructose or reduce fiber-associated inflammation in macrophage cells compared to remission or non-IBD children. Statistical analysis of food frequency questionnaire (FFQ) data on fiber consumption demonstrated that fiber-associated inflammation in patient biopsies cultured ex vivo (ELISA and qPCR) correlated with fiber avoidance (FFQ).

Conclusions

Comparing in vitro findings to our patient FFQs, intestinal washes (microbe abundance), and detailed patient history will better define the relationship between microbes, dietary fibers, and gut inflammation in IBD. This will allow for tailored dietary intervention through dietary recommendations, prebiotic, and/or probiotic therapies.

Funding Agencies

CCCWeston Foundation, WCHRI