Ileum Biopsies Research Articles

P1222 The macroscopic and microscopic distribution of IBD in patients with PSC: a polytomous latent class analysis on 3177 endoscopies

Abstract Background Inflammatory bowel disease (IBD) in patients with primary sclerosing cholangitis (PSC) is a distinct disease entity requiring specific management1. Data on characterisation of the phenotype of PSC-IBD are limited and subclassification is lacking. Therefore, this study aims to describe the macroscopic and microscopic distribution of IBD in patients with PSC. Methods A retrospective analysis was conducted on data from PSC-IBD patients included in the EpiPSC2 registry, comprising patients from 46 hospitals across the Netherlands. Data on inflammation at macro- and microscopic level in the ileum and 6 colonic segments were collected on every available endoscopy. Data after (hemi)colectomy were excluded. Polytomous latent class analysis was used to identify subgroups of IBD distribution2. First, latent class models (LCM) were fitted on all endoscopic and histologic data and Akaike and Bayesian information criteria were used to determine the optimal number of classes. After random sampling with replacement the LCM with the ideal number of groups was fitted on 20 samples of one endoscopy with inflammation per subject, and the pooled class probability was calculated per subgroup. Results A total of 3177 endoscopies from 522 PSC-IBD patients (median of 5 [IQR 2-9] endoscopies per patient) were included. The maximum depth of insertion was the terminal ileum in 62% and caecum in 27% of endoscopies. Macroscopic inflammation was observed in 1521 (48%) endoscopies from 428 patients. Segmental colon biopsies were obtained during 650 (20%) endoscopies in 237 subjects, and ileum biopsies in 144 (22%) endoscopies in 100 subjects. Microscopic inflammation in any segment was observed in 265 (41%) endoscopies. An LCM with four classes was the best fit to the macro- and microscopic data: no inflammation, right-sided colitis (pooled class probability 36%), left-sided colitis (30%), and pancolitis (34%). In right-sided colitis and pancolitis the probability of ileal involvement was 16% and 22%, whereas left-sided colitis most often displayed an absence of ileal involvement (probability of 4%) [fig.1]. For microscopic inflammation no pooled class probabilities could be calculated due to low sample size. In 139 (21%) endoscopies, LCM showed more extensive inflammation at microscopic assessment as compared to macroscopic assessment. Conclusion Macroscopic and microscopic inflammation in PSC-IBD may be classified into right sided colitis, left sided colitis, and pancolitis. The microscopic extent exceeds macroscopic inflammation in over 20% of endoscopies with segmental biopsies. Future research into the prognostic implication of this subclassification on PSC- and IBD-related outcomes is required.

P0148 Studying the role of adipose tissue in intestinal inflammation using acquired generalized lipodystrophy

Abstract Background Crohn’s disease (CD) is associated with creeping fat, characterized by hyperplasia of mesenteric adipocytes and increased secretion of adipokines, including leptin (1). However, limited models currently exist to study the effect of adipose tissue on intestinal inflammation. Therefore, acquired generalized lipodystrophy and Crohn’s disease (AGLCD), a rare metabolic disorder characterized by the complete loss of fat tissue and intestinal inflammation, could provide a unique model to further elucidate the contribution of adipose tissue to the pathogenesis of inflammatory bowel disease. Methods To decipher the role of adipose tissue, we characterized the immune cell compartment in a patient with AGLCD using mass cytometry, whole exome sequencing and single cell sequencing. Samples collected for the analysis include lamina propria mononuclear cells (LPMCs) isolated from ileum biopsies and peripheral blood mononuclear cells (PBMCs) from blood obtained from 6 CD patients, one AGLCD patient, and 4 non-inflamed controls. Results Using mass cytometry, we were able to identify 17 intestinal immune cell clusters in the LPMCs. Namely, there was a higher frequency of CD8+ CD45RO+ T cells, CD11c+ CD11b+ myeloid cells and CD19+ CCR7+ B cells in the AGLCD sample compared to the fat-proficient CD controls. In addition, single cell sequencing of CD3+ T cells isolated from the blood of the AGLCD patient showed an expansion of CD8+ and CD4+ effector memory T cells compared to a healthy donor, suggesting that adipose tissue plays a role in T cell homeostasis in CD. To confirm that leptin plays a role in the regulation of T cells, we analyzed PBMCs from the AGLCD patient pre and post treatment with recombinant leptin. An increase in the expression of IL-17 producing CD4 T cells were present after treatment with leptin. To further investigate the expansion of CD8+ T cells, analysis of whole exome sequencing of the AGLCD showed a mutation in the NRAS gene, an essential regulator of hematopoietic development. The mutation was confirmed only in CD8 and CD4 T cells in the blood and intestinal biopsies of the AGLCD patient using Sanger sequencing. Conclusion These observations demonstrate that AGLCD is a unique model that can be used to further study the effects of adipose tissue in intestinal inflammation. References (1) Coffey JC, O'Leary DP. The mesentery: structure, function, and role in disease. Lancet Gastroenterol Hepatol 2016;1:238-247.

Multiomic analysis reveals cellular, transcriptomic and epigenetic changes in intestinal pouches of ulcerative colitis patients

Total proctocolectomy with ileal pouch anal anastomosis is the standard of care for patients with severe ulcerative colitis. We generated a cell-type-resolved transcriptional and epigenetic atlas of ileal pouches using scRNA-seq and scATAC-seq data from paired biopsy samples of the ileal pouch and the ileal segment above the pouch (pre-pouch) from patients (male=4, female=2), and paired biopsies of the terminal ileum and ascending colon from healthy individuals (male=3, female=3) serving as reference. Our study finds an additional population of absorptive and secretory epithelial cells within the pouch but not the pre-pouch. These pouch-specific enterocytes express a subset of colon-specific genes, including CEACAM5 and CD24. However, compared to normal colonocytes, expression of these genes is lower, and these enterocytes also express inflammatory and secretory genes while maintaining expression of some ileal-specific genes. This cell-type-resolved transcriptomic and epigenetic atlas of the ileal pouch establishes a reference for investigating pouch physiology and pathology.

Multiomic analysis reveals cellular, transcriptomic and epigenetic changes in intestinal pouches of ulcerative colitis patients.

Total proctocolectomy with ileal pouch anal anastomosis is the standard of care for patients with severe ulcerative colitis. We generated a cell-type-resolved transcriptional and epigenetic atlas of ileal pouches using scRNA-seq and scATAC-seq data from paired biopsy samples of the ileal pouch and the ileal segment above the pouch (pre-pouch) from patients (male=4, female=2), and paired biopsies of the terminal ileum and ascending colon from healthy individuals (male=3, female=3) serving as reference. Our study finds previously uncharacterized populations of absorptive and secretory epithelial cells within the pouch but not the pre-pouch. These pouch- specific enterocytes express a subset of colon-specific genes, including CEACAM5 and CD24 . However, compared to normal colonocytes, expression of these genes is lower, and these enterocytes also express inflammatory and secretory genes while maintaining expression of some ileal-specific genes. This cell-type-resolved transcriptomic and epigenetic atlas of the ileal pouch establishes a reference for investigating pouch physiology and pathology.

Successful novel use of dupilumab for gastrointestinal involvement of idiopathic hypereosinophilic syndrome: case report and review of the literature.

Hypereosinophilic syndrome (HES) is characterized by blood and tissue hypereosinophilia leading to organ damage. Gastrointestinal involvement is the third most common manifestation. We present a patient with idiopathic HES with secondary eosinophilic esophagitis (EoE), gastritis, and enteritis, corticosteroids-dependent, azathioprine- and mepolizumab-refractory. The patient achieved clinical and histopathologic remission following dupilumab treatment. A 28year-old female presented with chronic episodic nausea and emesis since childhood and initial diagnosis of primary eosinophilic gastrointestinal disease (EGID), improved with corticosteroids, refractory to azathioprine. She was found to have peripheral eosinophilia and multifactorial anemia, with iron, B12, and folate deficiencies. Esophageal, gastric, duodenal, and terminal ileum biopsies showed significant eosinophilic infiltrate. Bone marrow biopsy at age 31 confirmed HES diagnosis. By age 32, she became total parental nutrition (TPN)-dependent. She failed trials of benralizumab and mepolizumab [anti-interleukin (IL)-5 inhibitors], and cromolyn (mast-cell stabilizer). After developing new esophageal stricture, we initiated dupilumab (IL-4/13 inhibitor), recently FDA-approved for EoE. After 9weeks, esophageal stricture, gut tissue eosinophilia, and prior intestinal ulcerations resolved. She ceased TPN and is tolerating a non-restricted diet, with complete symptom resolution. Our patient's complete remission with dupilumab shows promise for broadening its use in treating GI involvement in HES, along with primary EGIDs.

Volumetric changes of the enteric nervous system under physiological and pathological conditions measured using x-ray phase-contrast tomography.

Full-thickness biopsies of the intestinal wall may be used to study and assess damage to the neurons of the enteric nervous system (ENS), that is, enteric neuropathy. The ENS is difficult to examine due to its localization deep in the intestinal wall and its organization with several connections in diverging directions. Histological sections used in clinical practice only visualize the sample in a two-dimensional way. X-ray phase-contrast micro-computed tomography (PC-μCT) has shown potential to assess the cross-sectional thickness and volume of the ENS in three dimensions (3D). The aim of this study was to explore the potential of PC-μCT to evaluate its use to determine the size of the ENS. Full-thickness biopsies of ileum obtained during surgery from five controls and six patients clinically diagnosed with enteric neuropathy and dysmotility were included. Punch biopsies of 1 mm in diameter and 1 cm in length, from an area containing myenteric plexus, were extracted from paraffin blocks, and scanned with synchrotron-based PC-μCT without any staining. The microscopic volumetric structure of the neural tissue (consisting of both ganglia and fascicles) could be determined in all samples. The ratio of neural tissue volume/total tissue volume was higher in controls than in patients with enteric neuropathy (P = 0.013). The patient with the longest disease duration had the lowest ratio. The assessment of neural tissue can be performed in an objective, standardized way, to ensure reproducibility and comparison under physiological and pathological conditions. Further evaluation is needed to examine the role of this method in the diagnosis of enteric neuropathy.

Isolation of mucosa-associated microbiota dysbiosis in the ascending colon in hepatitis C virus post-sustained virologic response cirrhotic patients.

Achieving sustained virologic response (SVR) in patients infected with hepatitis C virus (HCV) reduces all-cause mortality. However, the mechanisms and risk factors for liver fibrosis and portal hypertension post-SVR remain incompletely understood. In the gut-liver axis, mucosa-associated microbiota (MAM) substantially influence immune and metabolic functions, displaying spatial heterogeneity at the anatomical intestinal site. We analyzed MAM composition and function to isolate the locoregional MAM involved in chronic liver disease progression in HCV post-SVR patients. We collected MAM samples from three intestinal sites (terminal ileum, ascending colon, and sigmoid colon) via brushing during colonoscopy in 23 HCV post-SVR patients and 25 individuals without liver disease (controls). The 16S rRNA of bacterial DNA in specimens collected with a brush and in feces was sequenced. The molecular expression of intestinal tissues and hepatic tissues were evaluated by quantitative real-time PCR. In the post-SVR group, the microbial β-diversity of MAM, especially in the ascending colon, differed from the control group and was associated with liver fibrosis progression. In PICRUSt analysis, MAM in the ascending colon in the liver cirrhosis (LC) group showed compromised functions associated with the intestinal barrier and bile acid production, and FGF19 expression was markedly decreased in the terminal ileum biopsy tissue in the LC group. At the genus level, six short-chain fatty acid (SCFA)-producing bacterial genera, Blautia, Alistipes, Roseburia, Agathobaculum, Dorea, and Pseudoflavonifractor were reduced in the ascending colon of post-SVR LC patients. In patients of HCV post-SVR, we identified the association between the degree of liver fibrosis and dysbiosis of mucosa-associated SCFA-producing bacterial genera that may be related to intestinal barrier and bile acid production in the ascending colon.

Number of intraepithelial lymphocytes and presence of a subepithelial band in normal colonic mucosa differs according to stainings and evaluation method

Chronic watery diarrhea is a frequent symptom. In approximately 10% of the patients, a diagnosis of microscopic colitis (MC) is established. The diagnosis relies on specific, but sometimes subtle, histopathological findings. As the histology of normal intestinal mucosa vary, discriminating subtle features of MC from normal tissue can be challenging and therefore auxiliary stainings are increasingly used. The aim of this study was to determine the variance in number of intraepithelial lymphocytes (IELs) and presence of a subepithelial band in normal ileum and colonic mucosa, according to different stains and digital assessment. Sixty-one patients without diarrhea referred to screening colonoscopy due to a positive feacal blood test and presenting with endoscopically normal mucosa were included. Basic histological features, number of IELs, and thickness of a subepithelial band was manually evaluated and a deep learning-based algorithm was developed to digitally determine the number of IELs in each of the two compartments; surface epithelium and cryptal epithelium, and the density of lymphocytes in the lamina propria compartment. The number of IELs was significantly higher on CD3-stained slides compared with slides stained with hematoxylin-and-eosin (HE) (p<0.001), and even higher numbers were reached using digital analysis. No significant difference between right and left colon in IELs or density of CD3-positive lymphocytes in lamina propria was found. No subepithelial band was present in HE-stained slides while a thin band was visualized on special stains. Conclusively, in this cohort of prospectively collected ileum and colonic biopsies from asymptomatic patients, the range of IELs and detection of a subepithelial collagenous band varied depending on the stain and method used for assessment. As assessment of biopsies from patients with diarrhea constitute a considerable workload in the pathology departments digital image analysis is highly desired. Knowledge provided by the present study highlight important differences that should be considered before introducing this method in the clinic.

Aberrant miR-29 is a predictive feature of severe phenotypes in pediatric Crohn's disease.

Crohn's disease (CD) is a chronic inflammatory gut disorder. Molecular mechanisms underlying the clinical heterogeneity of CD remain poorly understood. MicroRNAs (miRNAs) are important regulators of gut physiology, and several have been implicated in the pathogenesis of adult CD. However, there is a dearth of large-scale miRNA studies for pediatric CD. We hypothesized that specific miRNAs uniquely mark pediatric CD. We performed small RNA-Seq of patient-matched colon and ileum biopsies from treatment-naive pediatric patients with CD (n = 169) and a control cohort (n = 108). Comprehensive miRNA analysis revealed 58 miRNAs altered in pediatric CD. Notably, multinomial logistic regression analysis revealed that index levels of ileal miR-29 are strongly predictive of severe inflammation and stricturing. Transcriptomic analyses of transgenic mice overexpressing miR-29 show a significant reduction of the tight junction protein gene Pmp22 and classic Paneth cell markers. The dramatic loss of Paneth cells was confirmed by histologic assays. Moreover, we found that pediatric patients with CD with elevated miR-29 exhibit significantly lower Paneth cell counts, increased inflammation scores, and reduced levels of PMP22. These findings strongly indicate that miR-29 upregulation is a distinguishing feature of pediatric CD, highly predictive of severe phenotypes, and associated with inflammation and Paneth cell loss.

Single nuclear RNA sequencing of terminal ileum in patients with cirrhosis demonstrates multi-faceted alterations in the intestinal barrier

Patients with cirrhosis have intestinal barrier dysfunction but the role of the individual cell types in human small intestine is unclear. We performed single-nuclear RNA sequencing (snRNAseq) in the pinch biopsies of terminal ileum of four age-matched men [56 years, healthy control, compensated, early (ascites and lactulose use) and advanced decompensated cirrhosis (ascites and rifaximin use)]. Cell type proportions, differential gene expressions, cell-type specific pathway analysis using IPA, and cellular crosstalk dynamics were compared. Stem cells, enterocytes and Paneth cells were lowest in advanced decompensation. Immune cells like naive CD4 + T cells were lowest while ITGAE + cells were highest in advanced decompensation patients. MECOM had lowest expression in stem cells in advanced decompensation. Defensin and mucin sulfation gene (PAPSS2) which can stabilize the mucus barrier expression were lowest while IL1, IL6 and TNF-related genes were significantly upregulated in the enterocytes, goblet, and Paneth cells in decompensated subjects. IPA analysis showed higher inflammatory pathways in enterocytes, stem, goblet, and Paneth cells in decompensated patients. Cellular crosstalk analysis showed that desmosome, protease-activated receptors, and cadherin-catenin complex interactions were most perturbed in decompensated patients. In summary, the snRNAseq of the human terminal ileum in 4 subjects (1 control and three cirrhosis) identified multidimensional alteration in the intestinal barrier with lower stem cells and altered gene expression focused on inflammation, mucin sulfation and cell–cell interactions with cirrhosis decompensation.

FXR-FGF19 signaling in the gut–liver axis is dysregulated in patients with cirrhosis and correlates with impaired intestinal defence

Background and aimsExperimental studies linked dysfunctional Farnesoid X receptor (FXR)-fibroblast growth factor 19 (FGF19) signaling to liver disease. This study investigated key intersections of the FXR-FGF19 pathway along the gut–liver axis and their link to disease severity in patients with cirrhosis.MethodsPatients with cirrhosis undergoing hepatic venous pressure gradient measurement (cohort-I n = 107, including n = 53 with concomitant liver biopsy; n = 5 healthy controls) or colonoscopy with ileum biopsy (cohort-II n = 37; n = 6 controls) were included. Hepatic and intestinal gene expression reflecting FXR activation and intestinal barrier integrity was assessed. Systemic bile acid (BA) and FGF19 levels were measured.ResultsSystemic BA and FGF19 levels correlated significantly (r = 0.461; p < 0.001) and increased with cirrhosis severity. Hepatic SHP expression decreased in patients with cirrhosis (vs. controls; p < 0.001), indicating reduced FXR activation in the liver. Systemic FGF19 (r = −0.512, p < 0.001) and BA (r = −0.487, p < 0.001) levels correlated negatively with hepatic CYP7A1, but not SHP or CYP8B1 expression, suggesting impaired feedback signaling in the liver. In the ileum, expression of FXR, SHP and FGF19 decreased in patients with cirrhosis, and interestingly, intestinal FGF19 expression was not linked to systemic FGF19 levels. Intestinal zonula occludens-1, occludin, and alpha-5-defensin expression in the ileum correlated with SHP and decreased in patients with decompensated cirrhosis as compared to controls.ConclusionsFXR-FGF19 signaling is dysregulated at essential molecular intersections along the gut–liver axis in patients with cirrhosis. Decreased FXR activation in the ileum mucosa was linked to reduced expression of intestinal barrier proteins. These human data call for further mechanistic research on interventions targeting the FXR-FGF19 pathway in patients with cirrhosis.Clinical trial number: NCT03267615Graphical abstractPhysiology of enterohepatic FXR-FGF19 signaling and its regulation in patients with advanced chronic liver disease (ACLD). (FXR) farnesoid X receptor; (FGF19) fibroblast growth factor 19; (BA) bile acids; (c/dACLD) compensated/decompensated advanced chronic liver disease; (FXR) farnesoid X receptor; (SHP) small heterodimer partner; (OST-α/-β) organic solute transporter subunit alpha/beta; (CYP7A1) cholesterol 7 alpha-hydroxylase; (NTCP) Na+-taurocholate cotransporting polypeptide; (CYP8B1) sterol 12-alpha-hydroxylase; (HVPG) hepatic venous pressure gradient; (TJ) tight junctions; (AMP) antimicrobial peptides; (ASBT) Apical Sodium Dependent Bile Acid Transporter; (ZO 1) zonula occludens-1; (OCLN) occluding; (DEFA5) alpha-5-defensin.

Tissue markers may predict treatment response to antitumor necrosis factor-α agents in children with Crohn's disease.

Patients with moderate-severe Crohn's disease (CD) who are treated with antitumor necrosis factor alpha (TNF-α) agents may be subjected to primary nonresponse or partial response. We aimed to identify tissue markers that may predict response to these agents. Pediatric patients (6-18 years) with either ileal or ileo-colonic CD who were treated with anti-TNF-α were stratified into three different groups based on their overall response to therapy at the end of induction including clinical and laboratory parameters (group 1-full responders [FR], group 2-partial responders [PR], group 3-nonresponders [NR]). Seven tissue markers (fibronectin, interleukin [IL]-23R, IL-23, TNF-α, collagen-III, IL-13R, and hypoxia-inducible factors [HIF]-1α) were evaluated. Immunofluorescence (IF) analyses were performed on biopsies from the terminal ileum, which were retrieved up to 6 months before treatment initiation. Twenty-six CD patients (16 [61.5%] males; age 13.9 ± 2.9 years), including 8 (30.8%) with ileal disease and 18 (69.2%) with ileo-colonic disease, were enrolled. Terminal ileum biopsies from nine patients from group 1, nine from group 2, and eight from group 3 were evaluated. Three antibodies were found to be significantly different between NR and FR groups; Collagen III and fibronectin stains were significantly more prominent in NR patients, while TNF-α stain was significantly more pronounced in FR, p < 0.05 for each. PR could not have been predicted with neither of markers. Decreased tissue IF intensity of fibronectin and collagen III and increased intensity of TNF-α may predict response to anti-TNF-α treatment.

Are biopsies from endoscopically normal terminal ileum necessary?

The terminal ileum is typically examined during colonoscopies, especially in patients with inflammatory bowel disease (IBD) and diarrhea. The yield from performing biopsies of endoscopically normal appearing terminal ileum is less clear, and may be associated with greater costs, healthcare utilization and risk. We aimed to determine whether the biopsy results from endoscopically normal terminal ileum affect clinical management. This was a retrospective chart review of patients who underwent an ileocolonoscopy with terminal ileum biopsy at a multisite tertiary healthcare system. Patients with a diagnosis of IBD, prior ileocecal resection, or endoscopically abnormal appearing terminal ileum were excluded. Clinical and laboratory data were obtained from the electronic medical record. Comparison between patients was performed using Pearson's chi-square test. A total of 1018 consecutive patients were identified. Of the 299 who met the inclusion criteria, the majority were female (62.0%) and white (94.7%). Nearly 40% of the patients had a body mass index of 30 kg/m2 or above (38.1%). Terminal ileum biopsies were abnormal in 13 patients (4.3%): 5 patients had chronic ileitis, 6 had acute ileitis, 1 had acute and chronic ileitis, and 1 had amyloid deposition. All patients with either chronic or acute ileitis had chronic diarrhea listed as an indication for their colonoscopy. In patients with a normal appearing terminal ileum, clinically significant histologic abnormalities on biopsies were found in a very small percentage. Based on our findings, the routine biopsy of endoscopically normal appearing terminal ileum has limited diagnostic and therapeutic utility.

P121 Characterisation of the miRNAome in Crohn’s Disease patients reveals transcriptomic changes associated with tissue composition and drug treatment

Abstract Background Gene regulation plays a major role in Crohn's Disease (CD) susceptibility and drug response. MicroRNA (miRNA)-mediated mechanisms tune gene expression at the post-transcriptional level. MiRNAs are 20-to-25-nt long non-coding RNAs that repress protein expression by direct inhibition or cleavage of the targets. Evaluating the miRNAome is emerging as a promising tool to clarify pathogenesis and identify promising biomarkers. We characterised the regulatory miRNAome across disease subtypes, gut tissue locations and infliximab treatment in CD. Methods We generated 120 transcriptomic profiles from terminal ileum and left colon biopsies from Hospital Universitario de la Princesa (Madrid). This cohort is composed of 10 patients with active endoscopy, 10 quiescent CD cases, and 10 controls (30 in total). In a balanced setting, half of the samples were incubated with infliximab for 18 hours at 37ºC and the rest with basal medium (Table 1). We carried out an exploratory analysis to gain insights into the determinants of miRNAome variability, including variance partition analyses and linear mixed modelling to detect significantly altered miRNAs. We also harnessed results from several publications including GSE16879 dataset to perform a comparative study with infliximab response signatures. Results Tissue location is the primary determinant of miRNA expression variability. The Variance Partition model identified 30 top miRNAs whose variability is maximised across regions. However, patient-specific effects also play a relevant role. We also identified 96 differentially expressed miRNAs between terminal ileum and left colon, with an overrepresentation of molecules involved in stress and developmental pathways (Fig.1). Among these, we find miR200s and miR429, that are associated with suppression of epithelial-mesenchymal transition and are up-regulated in colon more than in ileum. Down-regulation of miR196 is also shown in terminal ileum. Regarding the effects of infliximab treatment, we detected nine deregulated miRNAs which are associated with cellular response pathways. These include miR200s and miR192, which targets NOD2 and down-regulates NF-κB. Our results show an up-regulation of miR192 upon infliximab incubation (log2FC=2.37), which is associated with a reduction in TNFα expression and, consequently, with induced overexpression of miR192. We conclude that this miRNA is a potential target for therapy development. Conclusion In short, tissue location, and to a lesser extent disease subtype, are the main determinants of miRNAome in CD. A few treatment-responsive miRNAs like miR192 and miR200s are identified, in spite of detection challenges, emphasizing the need to improve our comprehension of the miRNA dynamics associated with drug response.

Mucosa-Associated Microbiota Dysbiosis in the Terminal Ileum Correlates With Bowel Symptoms in Diarrhea-Predominant Irritable Bowel Syndrome.

The mucosa-associated microbiota (MAM) is not as frequently studied in diarrhea-predominant irritable bowel syndrome (IBS-D) compared with the fecal microbiota. In this study, we examined the MAM in the terminal ileum and its correlation with bowel symptoms in IBS-D. Mucosal biopsies of the terminal ileum from 25 patients with IBS-D and 25 healthy controls were collected for 16S ribosomal RNA gene sequencing. Correlation analysis was performed. Compared with healthy controls, the MAM in the terminal ileum showed a decreased alpha diversity in the IBS-D cohort (Chao1 and Shannon indexes, P < 0.05). And the overall MAM profile clustered separately into 2 groups (ADONIS [PERMANOVA, permutational multivariate analysis of variance], P < 0.05). At the phylum level, the relative abundance of Proteobacteria was significantly higher in the ileal MAM of patients with IBS-D while that of Firmicutes was significantly lower. At the genus level, the relative abundance of Pseudomonas was significantly higher in the IBS-D cohort, with lower Bacteroides and Ruminococcus . Moreover, 40.0% of patients with IBS-D had multiple small nodules (nodular lymphoid hyperplasia) on the mucosal surface of the terminal ileum, which indicated a low-grade inflammation. In patients with IBS-D with nodular lymphoid hyperplasia, the changes of Pseudomonas and Bacteroides were more overt. Correlation analysis revealed that the relative abundance of Pseudomonas positively correlated with abdominal pain and the severity of IBS. Patients with IBS-D showed a dysbiosis of MAM in the terminal ileum, which may be associated with bowel symptoms. Moreover, 40.0% of them displayed mucosal low-grade inflammation, with a more severe mucosal microbial disturbance.

Regional changes in intestinal permeability in cirrhosis are associated with mucosal bacteria.

Several complications of cirrhosis are theorized to result from the translocation of bacteria or their products across the intestinal epithelium. We aimed to assess epithelial permeability and associations with mucosal bacteria in patients with cirrhosis. We collected 247 duodenum, ileum, and colon biopsies from 58 consecutive patients with cirrhosis and 33 controls during clinically indicated endoscopies. Patients with cirrhosis were similarly aged to controls (60 vs. 58y) and had a median Model for End-stage Liver Disease of 8 (interquartile range 7, 10). Biopsies underwent 16S rRNA-encoding gene amplicon sequencing to determine mucosal bacteria composition and transepithelial electrical resistance (TEER) to determine epithelial permeability. In the entire cohort, there were regional differences in TEER with the lowest TEER (ie, more permeable) in the ileum; duodenum TEER was 43% higher and colon TEER 20% higher than ileum TEER (ANOVA p = 0.0004). When comparing patients with cirrhosis and controls, both TEER (26% lower in cirrhosis, p = 0.006) and alpha diversity differed in the duodenum (27% lower in cirrhosis, p = 0.01) but not ileum or colon. A beta-binomial model found that 26 bacteria were significantly associated with TEER. Bifidobacteriaceae Bifidobacterium in duodenal mucosa was protective of epithelial permeability and future hospitalization for hepatic decompensation. Duodenal epithelial permeability was higher, and mucosal bacteria alpha diversity was lower in cirrhosis compared to controls, while no such differences were seen in the ileum or colon. Specific bacteria were associated with epithelial permeability and future hepatic decompensation.

The orphan MRGPRF receptor is expressed in entero-endocrine cells of the human gut mucosa.

In the past years, it has become clear that the family of Mas-related G protein-coupled receptors plays a central role in neuro-immune communication at mucosal barrier surfaces, in particular in the skin. Remarkably, MRGPR expression at other mucosal surfaces remains poorly characterized. To fill this gap in our understanding, the present study was undertaken to screen and verify the expression of the human MRGPR family members in the mucosal biopsies of the human gastrointestinal (GI) tract. Our findings revealed that, of all human MRGPRs family members, only MRGPRF mRNA is expressed at detectable levels in human mucosal biopsies of both terminal ileum and sigmoid colon. Furthermore, immunohistochemical stainings revealed that MRGPRF is specifically expressed by mucosal entero-endocrine cells (EECs). Overall, this study showed for the first time that the human ileum and colonic mucosa represent a novel expression site for the orphan MRGPRF, more specifically in EECs.

Diagnostic yield of random colon biopsy sampling in patients with chronic diarrhea and normal colonoscopy: a systematic review and meta-analysis

Background and AimsMost colonoscopy examinations in patients with chronic unexplained diarrhea do not reveal endoscopic abnormalities, and routine random colon biopsy specimens are taken for further diagnostic assessment. In this study, we aimed to perform a systematic review and meta-analysis to study the pooled diagnostic value of random colon biopsy sampling in this patient population.MethodsMultiple databases (MEDLINE, Scopus, Embase) were searched in May 2022 for studies evaluating the diagnostic yield of random biopsy sampling in patients with chronic diarrhea with normal colonoscopy examinations. Standard meta-analysis methods used the random-effects model, and heterogeneity was assessed using the I2 statistics.ResultsTwenty-one studies were included in the study (3322 patients). The pooled rate of normal colon biopsy sampling was 48% (95% confidence interval [CI], 31-65.2; I2 = 98%), and normal ileal biopsy sampling was 88.5% (95% CI, 51.3-98.3; I2 = 93%). The pooled rate of significant histopathologic change was 30% (95% CI, 20-41; I2 = 96%). The pooled rates of specific diagnoses based on random colon biopsy sampling were as follows: microscopic colitis, 15% (95% CI, 10-21; I2 = 92%); lymphocytic colitis, 9% (95% CI, 6 -13; I2 = 85%); collagenous colitis, 3.5% (95% CI, 2.4-5.7; I2 = 80%); nonspecific colitis, 20% (95% CI, 11-32.8; I2 = 97%); inflammatory bowel disease, 1.7% (95% CI, .8-3.5; I2 = 54%); and eosinophilic colitis, 2.3% (95% CI, 1.1-4.5; I2 = 69%).ConclusionsThis meta-analysis of 21 studies demonstrated significant histopathologic change in 30% and microscopic colitis in 15%. Normal colon biopsy sampling was noted in 48% and normal ileum biopsy sampling in 88.5%. Ileal biopsy data were based on limited data and studies (only 3 included). In studies with a mean patient age <49 years, 40% demonstrated significant histopathologic changes. Most colonoscopy examinations in patients with chronic unexplained diarrhea do not reveal endoscopic abnormalities, and routine random colon biopsy specimens are taken for further diagnostic assessment. In this study, we aimed to perform a systematic review and meta-analysis to study the pooled diagnostic value of random colon biopsy sampling in this patient population. Multiple databases (MEDLINE, Scopus, Embase) were searched in May 2022 for studies evaluating the diagnostic yield of random biopsy sampling in patients with chronic diarrhea with normal colonoscopy examinations. Standard meta-analysis methods used the random-effects model, and heterogeneity was assessed using the I2 statistics. Twenty-one studies were included in the study (3322 patients). The pooled rate of normal colon biopsy sampling was 48% (95% confidence interval [CI], 31-65.2; I2 = 98%), and normal ileal biopsy sampling was 88.5% (95% CI, 51.3-98.3; I2 = 93%). The pooled rate of significant histopathologic change was 30% (95% CI, 20-41; I2 = 96%). The pooled rates of specific diagnoses based on random colon biopsy sampling were as follows: microscopic colitis, 15% (95% CI, 10-21; I2 = 92%); lymphocytic colitis, 9% (95% CI, 6 -13; I2 = 85%); collagenous colitis, 3.5% (95% CI, 2.4-5.7; I2 = 80%); nonspecific colitis, 20% (95% CI, 11-32.8; I2 = 97%); inflammatory bowel disease, 1.7% (95% CI, .8-3.5; I2 = 54%); and eosinophilic colitis, 2.3% (95% CI, 1.1-4.5; I2 = 69%). This meta-analysis of 21 studies demonstrated significant histopathologic change in 30% and microscopic colitis in 15%. Normal colon biopsy sampling was noted in 48% and normal ileum biopsy sampling in 88.5%. Ileal biopsy data were based on limited data and studies (only 3 included). In studies with a mean patient age <49 years, 40% demonstrated significant histopathologic changes.

Mucosal Architectural Change is an Important Feature in Distinguishing Crohn's Disease From Others in Terminal Ileum Ulcer Biopsy.

Besides Crohn's disease (CD), there are a variety of other causes that can also lead to ulcerations in the terminal ileum. The purpose of this study was to identify useful diagnostic features for CD when evaluating terminal ileum biopsies in patients with endoscopic finding of ulcers. Five hundred and seventy-one patients with endoscopic finding of ulcers were included in this retrospective study. Five main histological features were analysed, which were crypt irregularity, mucosal thickening, villous stromal widening (including villous atrophy), granulomas, and pseudopyloric gland metaplasia. Clinical and pathological features were determined by uni- and multivariable logistic regression. Then another independent cohort of 99 patients was established for verifying this nomogram. The crypt irregularity, mucosal thickening, and villous stromal widening were combined to be considered as one new variable named mucosal architectural change which was an independent variable in diagnosing CD. We found that mucosal architectural change, age <40 years, the presence of granulomas, and the presence of pseudopyloric gland metaplasia were independent factors for the pathological diagnosis of CD. Then nomogram was developed, with receiver operating characteristic (ROC) curve (area under the ROC curve [AUC] = 0.927) in training sets, and ROC curve (AUC = 0.913) in validation sets. We found mucosal architectural change is very helpful in distinguishing CD from non-CD patients. In the context of small biopsy which may lack full scope of changes, the model developed by combining these key features is valuable in predicting a diagnosis of CD, especially in younger patients (age <40 years).

P036 Analysis of intestinal tissue from newly diagnosed patients with inflammatory bowel disease reveals distinct proteomic profiles

Abstract Background Inflammatory bowel disease (IBD) is a complex multi-factorial disease characterized by chronic inflammation of the gastrointestinal tract. Despite significant efforts to understand the pathogenetic mechanisms of IBD, the elucidation of its etiopathology and progression is far from fully understood. The direct analysis of the intestinal tissue from the endoscopy which leads to IBD diagnosis (before starting any treatment) would be the ideal sample to elucidate IBD pathogenesis. Methods High-throughput mass-spectrometry-based quantitative proteomic analysis was performed using formalin-fixed paraffin-embedded human intestinal samples from newly diagnosed patients to elucidate the potential mechanisms responsible for gut inflammation in Crohn′s disease (CD) and ulcerative colitis (UC). For this purpose, 192 formalin-fixed paraffin-embedded samples from 40 active UC patients, 67 active CD patients and 46 normal biopsies from healthy controls (HC) were analyzed (Figure 1). Proteins with p-value &amp;lt; 0.05 were considered as significantly dysregulated. Moreover, we used Ingenuity Pathway Analysis (IPA) to analyze the pathways and functions in different locations of the gut (ileum or left colon) that could be related to IBD pathogenesis. Results A total of 2,903 proteins were identified, of which 1,010 were differentially expressed between left colon from CD patients and HC. 1,242 proteins were differentially expressed between left colon from UC patients and HC, and 952 differential proteins discriminated between left colon from CD and UC patients. In the comparative study of ileum biopsies from Crohn’s disease patients and healthy controls, 956 proteins were differentially expressed (Figure 2). IPA revealed multiple canonical pathways, including EIF2 signaling, regulation of eIF4 and serine/threonine kinase P7056K signaling, mitochondrial dysfunction, and oxidative phosphorylation altered in ileum biopsies from CD patients compared to HC (Figure 3). Regarding the proteomic study in left colon samples, the main canonical pathways enrichment in the comparison of UC and CD with HC were the following: neutrophil extracellular trap signaling pathways, fatty acid oxidation, sirtuin signaling pathway, tRNA charging, and mitochondrial dysfunction (Figure 4). Conclusion The proteomic results revealed dysregulated proteins and pathways in ileum and left colon biopsies from patients with active CD and UC compared to HC that may unravel key mechanisms contributing to the pathogenesis of these diseases. The results of the study serve as a starting point for hypotheses to understand the pathogenesis and search for therapeutic targets.