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.

Creation of EGD-Derived Gastric Cancer Organoids to Predict Treatment Responses

Gastric adenocarcinoma (GAd) is the third leading cause of cancer-related deaths worldwide. Most patients require perioperative chemotherapy, yet methods to accurately predict responses to therapy are lacking. Thus, patients may be unnecessarily exposed to considerable toxicities. Here, we present a novel methodology using patient-derived organoids (PDOs) that rapidly and accurately predicts the chemotherapy efficacy for GAd patients. Methods:Endoscopic GAd biopsies were obtained from 19 patients, shipped overnight, and PDOs were developed within 24 h. Drug sensitivity testing was performed on PDO single-cells with current standard-of-care systemic GAd regimens and cell viability was measured. Whole exome sequencing was used to confirm the consistency of tumor-related gene mutations and copy number alterations between primary tumors, PDOs, and PDO single-cells. Results:Overall, 15 of 19 biopsies (79%) were appropriate for PDO creation and single-cell expansion within 24 h of specimen collection and overnight shipment. With our PDO single-cell technique, PDOs (53%) were successfully developed. Subsequently, two PDO lines were subjected to drug sensitivity testing within 12 days from initial biopsy procurement. Drug sensitivity assays revealed unique treatment response profiles for combination drug regimens in both of the two unique PDOs, which corresponded with the clinical response. Conclusions:The successful creation of PDOs within 24 h of endoscopic biopsy and rapid drug testing within 2 weeks demonstrate the feasibility of our novel approach for future applications in clinical decision making. This proof of concept sets the foundation for future clinical trials using PDOs to predict clinical responses to GAd therapies.

A144 ISOLATED UPPER ESOPHAGEAL VARICES DUE TO SUPERIOR VENA CAVA SYNDROME: A CASE OF UPPER GI BLEEDING

Background

Esophageal varices represent a cause of upper gastrointestinal bleeding (UGI) with significant associated morbidity and mortality. The majority of variceal bleeds are due to portal hypertension and cirrhosis. In some very rare cases isolated upper esophageal varices may occur. These present management challenges, as typical management options for varices in cirrhosis are not applicable due to differences in pathophysiology. Infusions to decrease portal pressure and TIPS procedures may be used in cirrhosis, but are not effective in patients with SVC syndrome.

Aims

We present a literature review on isolated upper esophageal varices due to SVC syndrome, and present a case that provides further confirmation that surgical vascular reconstruction is a viable option in these cases.

Methods

The case of a 49 year old female with variceal hemorrhage secondary to SVC syndrome was reviewed. A search of the literature was undertaken using the terms “varices + superior vena cava syndrome” and “upper esophageal varices + management.”

Results

Overall, the majority of cases of isolated upper esophageal varices are secondary to SVC syndrome. They typically occur in cases of benign, rather than malignant SVC syndrome. Only one previous case was reported to be managed with surgical vascular reconstruction. We present the case of a 49-year old woman with SVC syndrome secondary to a thrombosed dialysis line who went on to develop isolated upper esophageal varices and large volume UGI bleeding. The pathophysiology of these “downhill” varices differs enough from portal hypertension that typical variceal management options may not be appropriate. Given a previous history of unsuccessful balloon angiography and the risk associated with variceal bleeding, she was taken back to the operating room for surgical vascular reconstruction. A surgical bypass was performed. She did well post-surgery and was discharged. She had no recurrence of bleeding and had a resolution of her edema at 6 month follow up.

Conclusions

Isolated upper esophageal varices are a potentially serious complication of SVC syndrome, and should be considered in cases of upper GI bleeding in patients with dialysis lines as they can have limited management options. This case was successfully managed by surgical vascular reconstruction, which represents an important treatment option in these difficult cases.

Funding Agencies

None

A195 A RARE CAUSE OF SEVERE REFRACTORY DIARRHEA IN A PATIENT WITH COMMON VARIABLE IMMUNE DEFICIENCY ASSOCIATED INTESTINAL ENTEROPATHY

Background

CVID is the most common type of severe antibody deficiency. Gastrointestinal manifestations affect approximately 20–50% of patients. Boland et al. described in a case series that 2/3 CVID patients were able to achieve clinical and endoscopic remission with Vedolizumab. This α4β7 integrin antagonist inhibits intestinal T cell translocation by blocking integrin interactions with mucosal vascular addressin cell adhesion molecule 1, reducing lymphocyte mediated inflammation. However, despite its novel use for this indication, limited data is available on the consequences of this therapy in patients with CVID.

Aims

To report on a case assessing the efficacy and outcomes of Vedolizumab for the treatment of CVID associated autoimmune enteropathy.

Methods

We present the case of a 50-year-old male presenting with severe refractory diarrhea and malnutrition. A colonoscopy demonstrated patchy ulceration and biopsies revealed ulcerated active colitis, negative for CMV. He was treated with Vedolizumab and Total Parental Nutrition (TPN). His diarrhea resolved, he gained 20 kg and he was weaned off TPN. In 2019, he re-presented with severe diarrhea. Subsequently endoscopic evaluation revealed patchy edematous colonic mucosa and biopsies demonstrated minimally active colitis, negative for CMV. He again responded to Vedolizumab re-induction, however shortly after, his diarrhea returned aggressively. CT enterography demonstrated active jejunal inflammation. Subsequently, an EGD revealed multiple duodenal ulcers and luminal narrowing. Biopsies of the small bowel were sent to histopathology.

Results

CMV superinfection was diagnosed on pathology (image 1). This patient’s diarrhea completely resolved with IV Gancyclovir and he was discharged on maintenance treatment with oral Valganciclovir.

Conclusions

This represents the first reported case of CMV enteritis secondary to Vedolizumab for the treatment of CVID associated autoimmune enteropathy. In this case, clinical and endoscopic remission was observed with Vedolizumab, however subsequently hampered by CMV reactivation. Hommel et al., published a positive correlation in a single centre retrospective cohort study of CMV reactivation in patients with ulcerative colitis treated with Vedolizumab. A large retrospective review of data from a multicenter consortium database of over 1000 Vedolizumab treated IBD patients reported CMV colitis in only 4 patients. CMV reactivation appears to be an exceptionally rare but important event in patients treated with Vedolizumab. Based on this report, patients with CVID associated enteropathy and refractory diarrhea should be carefully screened for CMV when treated with Vedolizumab. Further prospective data assessing the incidence of CMV reactivation in patients with Vedolizumab therapy is required to further define these findings.

Funding Agencies

None

Examining Psychosocial Mechanisms of Pain-Related Disability in Inflammatory Bowel Disease

Disability in inflammatory bowel disease (IBD) is under-investigated. Models theorize that disability is the result of a disease and its related impairments, limitations, and restrictions. This disablement process can be affected by psychosocial factors. Pain, depression, catastrophizing, and social support are associated with IBD-disability outcomes, but no studies have examined these factors concurrently. This study examined the role of psychosocial factors in the process of IBD disablement within the context of pain. Depressive symptoms, pain catastrophizing, and perceived social support were proposed as mediators in the relationship between pain and pain-related disability in cross-sectional and longitudinal models. Cross-sectionally, the mediation effects of depressive symptoms and pain catastrophizing, but not perceived social support, were significant. Longitudinally, depression was a significant mediator. Depressive symptoms and pain catastrophizing have mechanistic roles in the relationship between IBD patients' pain and pain-related disability and should be targets for intervention.

A164 UPTAKE OF FECAL CALPROTECTIN IN PRACTICE: PATTERNS IN A TERTIARY GI REFERRAL CENTRE

Background

Fecal Calprotectin (FC) is helpful in distinguishing functional from organic bowel disease. Also, it has proven useful in monitoring disease activity in inflammatory bowel disease (IBD). The uptake of its use in clinical practice has increased considerably, though access varies significantly. Studies exploring current practice patterns among GI specialists and how to optimize its use are limited. In 2017, Kingston Health Sciences Centre (KHSC) began funding FC testing at no cost to patients.

Aims

We aimed to better understand practice patterns of gastroenterologists in IBD patients where there is in house access to FC assays, and to generate hypotheses regarding its optimal use in IBD monitoring. We hypothesize that FC is not being used in a regular manner for monitoring of IBD patients.

Methods

A retrospective chart audit study was done on all KHSC patients who had FC testing completed from 2017–2018. Qualitative data was gathered from dictated reports using rigorous set definitions regarding indication for the test, change in clinical decision making, and frequency patterns of testing. Specifically, change in use for colonoscopy or in medical therapy was coded only if the dictated note was clear that a decision hinged largely on the FC result. Frequency of testing was based on test order date. Reactive testing was coded as tests ordered to confirm a clinical flare. Variable testing was coded where monitoring tests that varied in intervals greater than 3 months and crossed over the other set frequency codes. Quantitative data regarding FC test values, and dates were also collected. This data was then analyzed using descriptive statistics.

Results

Of the 834 patients in our study, 7 were under 18 years old and excluded. 562(67.34%) of these patients had a pre-existing diagnosis of IBD; 193 (34%) with Ulcerative Colitis (UC), 369 (66%) with Crohn’s Disease (CD). FC testing changed the clinician’s decision for medical therapy in 12.82% of cases and use for colonoscopy 13.06% of the time for all comers. Of the FC tests, 79.8% were sent in a variable frequency pattern and 2.68% with reactive intent. The remaining 17.5% were monitored with a regular pattern, with 8.57% patients having their FC monitored at regular intervals greater than 6 months, 7.68% every 6 months, and 1.25% less than 6 months. The average FC level of patients with UC was 356.2ug/ml and 330.6 ug/ml for CD. The mean time interval from 1st to 2nd test was 189.6 days.

Conclusions

FC testing changed clinical decisions regarding medical therapy and use for colonoscopy about 13% of the time. FC testing was done variably 79.8% of the time, where as 17.5% of patients had a regular FC monitoring schedule. An optimal monitoring interval for IBD flares using FC for maximal clinical benefit has yet to be determined. Large scale studies will be required to answer this question.

Funding Agencies

None

A111 SEVERE FAT MALABSORPTION IN A PATIENT POST ILEAL POUCH ANAL ANASTAMOSIS: A RARE PRESENTATION OF MICROSCOPIC ENTERITIS

Background

Microscopic enteritis (ME) is a rare enteropathy characterized by malabsorptive diarrhea and lymphocytic infiltration +/- collagen deposition in the subepithelial layer of the small bowel. Its etiology is unclear.

Aims

To elucidate a rare cause of fat malabsorption and vitamin deficiency in a patient with ulcerative colitis and an ileoanal pouch.

Methods

A 74 yo male with a prior IPAA was referred to Internal Medicine in August 2018 for a 36 kg weight loss over 18 months and >16 bowel movements (BM) per day (baseline 6, no history of pouchitis). Celiac serology and infectious workup were negative. Medical management and nutritional supplements did not result in weight gain or improvement of diarrhea. He was admitted in June 2019 with ongoing weight loss, AKI, and signs of fat-soluble vitamin deficiency. A 72-hour fecal fat analysis showed an average fecal weight of 2100 g/d (ref <250 g/d), and excretion of 70% of daily fat intake (ref <7%). His fecal elastase (FE) was 147 µg/g, consistent with moderate pancreatic insufficiency (PI) with mild atrophy on CT. EGD and pouch endoscopy were macroscopically normal, with histological findings of intraepithelial lymphocytosis and mild villous blunting in the duodenum and afferent limb. CT enterography excluded small bowel abnormalities. He was started on pancreatic enzyme replacement and discharged. He returned with worsening diarrhea and AKI. He was treated with supportive care and sent home. In the ensuing 3 weeks, he had up to 24 BM per day and 4 kg of weight loss. He returned in August 2019 with AKI, lack of PO intake and worsened nutritional status. Re-examination of duodenal biopsies from June 2019 revealed an added finding of focal subepithelial collagen thickening. Budesonide was started.

Results

On budesonide, his symptoms improved within days. BMs decreased to baseline, and his ability to sustain PO intake improved. At his 4-week follow-up visit, BMs were stable with a 6 kg weight gain and no ensuing laboratory abnormalities.

Conclusions

ME is a rare enteropathy that presents with malabsorption. Fat-soluble vitamin deficiencies can develop with widespread physiological disruption of the mucosal surface. This patient was a diagnostic challenge. His steatorrhea and reduced FE levels led clinicians down a diagnostic pathway of PI. FE is the most common test used in the diagnosis of PI. Levels <200 µg/g are abnormal. Specificity is highest in chronic pancreatitis; however, this decreases in the presence of mucosal atrophy (i.e. IBD and diffuse small bowel disease). Thus, FE could not delineate the cause of steatorrhea in our patient. We can surmise that he likely has diffuse disease that was underestimated on duodenal biopsy. This is supported by his response to budesonide. This case highlights the heterogeneity of clinical presentations of ME. Awareness can reduce patient morbidity.

Funding Agencies

None

Colonoscopy Trainers Experience Greater Stress During Insertion than Withdrawal: Implications for Endoscopic Curricula

Background

Optimal colonoscopy training curricula should minimize stress and cognitive load. This study aimed to determine whether withdrawal or insertion colonoscopy skills training is associated with less stress or cognitive load for trainees or trainers.

Methods

In Phase I, participants were randomized to train on either insertion or withdrawal in a simulated environment. In Phase II, participants were randomized to begin with either insertion or withdrawal in patient encounters. Salivary cortisol levels, heart rate, and State-Trait Anxiety Inventory (STAI) surveys were used to assess stress in trainees and trainers. NASA Task Load Index (TLX) survey was used to assess cognitive workload in trainees.

Results

In Phase I, trainee stress increased during the simulation training during both withdrawal and insertion compared to baseline, while trainer stress changed minimally. Cognitive load was higher for trainees during withdrawal (P = 0.005). In Phase II, trainers’ STAI scores were greater during insertion training (P = 0.013). Trainees’ stress was highest prior to beginning patient training and decreased during training, while trainer’s stress increased during training. Trainees reported insertion training being of greater value (70.0%), while trainers reported withdrawal was preferred (77.8%).

Conclusion

Trainees and trainers exhibit important differences in stress during colonoscopy skills training. Trainees reported more stress during simulation training and greatest cognitive load during simulation withdrawal, whereas trainers reported greatest stress during patient encounters, particularly training of insertion techniques. Attention to the effect of stress on trainees and trainers and the drivers of stress is warranted and could be incorporated in competency based medical education.

Analysis of Genetic Association of Intestinal Permeability in Healthy First-degree Relatives of Patients with Crohn's Disease

Excessive intestinal permeability or intestinal barrier dysfunction as measured by various assays has been observed in various diseases. However, little is known about the factors contributing to altered gut permeability in these diseases. Our objective was to determine the genetic determinants of altered gut permeability as measured by the lactulose mannitol fractional excretion ratio (LacMan ratio) in 1075 healthy first-degree relatives of patients with Crohn's disease (CD). In a targeted analysis of single nucleotide polymorphisms (SNPs) located in genes associated with intestinal barrier function related or not to inflammatory bowel disease, we did not find a significant association with intestinal permeability. In an untargeted genome-wide association analysis, the top 100 associations were located in 22 genomic loci, although they were not statistically significant after correction for multiple testing (raw P values [1.8 × 10-7 - 1.4 × 10-5]. The lowest P value was obtained for rs9616637 (22q13.33, C22orf34), for which the minor allele A was associated with a decreased LacMan ratio. These results suggest that host genetic background has limited contribution toward intestinal permeability. Despite this, our study is currently the largest of its kind assessing gut permeability in vivo. It remains possible that smaller genetic effect sizes on LacMan ratio are not detectable in this sized cohort. Larger studies are warranted to identify the potential genetic contribution to intestinal permeability.

Small bowel review: normal physiology part 1

In the past year there have been many advances in the area of small bowel physiology and pathology and therapy. In preparation for this review, over 1500 papers were assessed. The focus is on presenting clinically useful information for the practising gastroenterologist. Selected important clinical learning points include the following: (1) glucose absorption mediated by SGLT1 is controlled by mRNA abundance, as well as by posttranscriptional processes including protein trafficking; (2) inducers of cytochrome P-450 decrease glucose and fructose absorption and increase glucose consumption in the intestine; (3) the regulated release of nutrients from the stomach into the upper intestine ensures that the modest intestinal transport reserve capacity is not exceeded; (4) hepatocyte growth factor and short-chain fatty acids may enhance intestinal adaptation and prevent the atrophy seen when total parenteral nutrition is infused; (5) inhibitors of pancreatic lipase and phospholipase H2 may be useful clinically to reduce absorption as part of a treatment program for obesity and hyperlipidemia; (6) several membrane-bound and cytosolic proteins have been identified in the enterocyte as well as in the hepatocyte and may be the target for the future therapeutic manipulation of bile acid metabolism and control of hyperlipidemia; (7) suspect bile acid malabsorption in the patient with otherwise unexplained chronic diarrhea; (8) a proportion of lipid absorption is protein-mediated, and this opens the way to targeting these proteins and thereby therapeutically modifying lipid absorption; (9) a high protein diet may be useful to increase the intestinal absorption of drugs transported by the H+/dipeptide cotransporter; (10) a metal transporter DCT1 has been identified, and this may open the way to a better understanding of disorders of, for example, iron and zinc metabolism; (11) the nutrient transporters such as SGLT1 are responsible for a portion of the intestinal absorption of water; (12) the influence of nitric oxide on intestinal water absorption and secretion depends on its concentration; (13) a trial of bile acid-sequestering agent may prove useful in the treatment of the patient who experiences diarrhea while taking an enteral diet; (14) a proteolytic extract from pineapple stems may prove to be useful to treat diarrhea, although the mechanism of this effect remains to be established; and (15) the antisecretory effect of the new peptide, sorbin, needs to be tested in a clinical situation on patients with diarrhea. Other new and promising antidiarrheal agents include bromelain, an extract from pineapple stems, and igmesine, a final sigma ligand.

Small bowel review: normal physiology part 2

In the past year there have been many advances in the area of small bowel physiology and pathology and therapy. In preparation for this review, over 1500 papers were assessed. The focus is on presenting clinically useful information for the practising gastroenterologist. Selected important clinical learning points include the following: (1) numerous peptides are being identified which stimulate the proliferation and functional response of the small intestine to disease or resection, and may in time find a clinical use; (2) under usual in vivo conditions, absorption of nutrients has little effect on the paracellular movement of water; (3) the permeability of the intestine is modified by the function of the tight junctions, and measuring intestinal permeability may be useful to reflect the presence of disease; (4) the release of serotonin is influenced by cholinergic, adrenergic, and nonadrenergic, noncholinergic mechanisms, and serotonin agonists and antagonists may play an important future role in the treatment of motility disorders; (5) the use of endothelin receptor antagonists may be useful for the treatment of intestinal anaphylaxis; (6) the alterations in intestinal pH and motility in patients with Crohn's disease may influence the action of pH- or time-dependent release medications; and (7) patients with irritable bowel syndrome may also have abnormalities in gastric and small intestinal motility.

Small bowel review: diseases of the small intestine

In the past year there have been many advances in the area of small bowel physiology and pathology and therapy. In preparation for this review, over 1500 papers were assessed. The focus is on presenting clinically useful information for the practicing gastroenterologist. Selected important clinical learning points include the following: (1) glutamine may restore the AIDs-associated increased intestinal permeability to normal; (2) substance P is a major mediator of diarrhea caused by Costridium difficile toxin A, acting by binding to a G-protein-coupled receptor, and represents a possible 2therapeutic target; (3) the serological diagnosis of celiac disease has been greatly enhanced with the use of anti-endomysial antibody testing, and the recent antitransglutaminase; (4) a quarter of patients with celiac disease may have secondary pancreatic insufficiency and require enzyme replacement therapy; (5) in the patient with unexplained elevation in the serum transaminase concentration, consider celiac disease as an obscure possibility; (6) bosentan and endothelin receptor agonist may prove to be useful in reducing gut ischemia in patients with septic shock; and (7) the administration of recombinant human fibroblast growth factor-2 may prove to be useful to prevent radiation damage to the gastrointestinal tract.