Colitis Biopsies Research Articles

Iron regulatory protein 2 contributes to antimicrobial immunity by preserving lysosomal function in macrophages

Colorectal cancer and Crohn's disease patients develop pyogenic liver abscesses due to failures of immune cells to fight off bacterial infections. Here, we show that mice lacking iron regulatory protein 2 (Irp2), globally (Irp2-/-) or myeloid cell lineage (Lysozyme 2 promoter-driven, LysM)-specifically (Irp2ΔLysM), are highly susceptible to liver abscesses when the intestinal tissue was injured with dextran sodium sulfate treatment. Further studies demonstrated that Irp2 is required for lysosomal acidification and biogenesis, both of which are crucial for bacterial clearance. In Irp2-deficient liver tissue or macrophages, the nuclear location of transcription factor EB (Tfeb) was remarkably reduced, leading to the downregulation of Tfeb target genes that encode critical components for lysosomal biogenesis. Tfeb mislocalization was reversed by hypoxia-inducible factor 2 inhibitor PT2385 and, independently, through inhibition of lactic acid production. These experimental findings were confirmed clinically in patients with Crohn's disease and through bioinformatic searches in databases from Crohn's disease or ulcerative colitis biopsies showing loss of IRP2 and transcription factor EB (TFEB)-dependent lysosomal gene expression. Overall, our study highlights a mechanism whereby Irp2 supports nuclear translocation of Tfeb and lysosomal function, preserving macrophage antimicrobial activity and protecting the liver against invading bacteria during intestinal inflammation.

Modulation of WNT signalling by inflammatory factor TWEAK, and its consequences on fibroblast-epithelial communication

BACKGROUND AND AIMS: A single layer of epithelial cells that are supported by resident mucosal fibroblasts, provides an intestinal barrier against pathogens. In Inflammatory Bowel Disease (IBD), this barrier is disrupted by mechanisms which are poorly understood. Intestinal fibroblasts produce WNT, BMP and Notch mediators that contribute to epithelial homeostasis and an impairment on these signals results in the loss of barrier integrity which has been observed in IBD. In fact, fibroblasts producing these signals may be lost during inflammation. Yet the mediators and mechanism that drive this loss of homeostatic stromal-derived signals are unknown. TWEAK is a member of the tumour necrosis factor superfamily (TNFSF) that was found to be upregulated in IBD biopsies and dysregulated tissue repair and promote chronic inflammation in in vivo murine models. However, whether TWEAK exerts its effects on fibroblasts and how these may contribute to barrier breakdown remains unknown. My central hypothesis is that TWEAK dysregulates the crosstalk between fibroblasts and epithelial cells in the intestinal tract by impairing a homeostatic signalling network. METHODS: To assess the effect of TWEAK on WNT signalling and wound healing in fibroblasts and epithelial cells, the expression of WNT ligands and receptors were assessed. Primary human colonic fibroblasts and human colonic epithelial cells were stimulated with TWEAK at various time points and analysed by qPCR, Western blot and Flow cytometry and scratch wound assay. RESULTS: Both Fibroblasts and epithelial cells displayed abundant Fn14 surface receptor, although epithelial cells at a level lower than that found on colonic fibroblasts. Transcriptional signatures at gene RSPO2 (0.5-fold ± decrease, *p<0.05, n=4), WNT5A (1 fold ± decrease, **p<0.01, n=4) and BMP6 (1 fold ± decrease, ***p<0.001, n=4) and protein level RSPO2 (50% ± decrease respectively, n=5) showed a TWEAK-mediated suppression after prolonged exposure (24-48h), but not in epithelial cells. Moreover, TWEAK delayed fibroblast healing capacity after 24h (50% ± decrease in wound closure, n=4) in a wound-scratch assay. CONCLUSION: TWEAK represses the expression of homeostatic factors in colonic fibroblasts but not on epithelial cells, suggesting this mechanism could be specific to the intestinal stroma. The effect that this impairment of WNT signals in stromal cells may have on their differentiation and communication with the epithelium will be subject for further study. UCD Ad Astra PhD Scholarship. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Dysregulation of CD4+ and CD8+ resident memory T, myeloid, and stromal cells in steroid-experienced, checkpoint inhibitor colitis

BackgroundColitis caused by checkpoint inhibitors (CPI) is frequent and is treated with empiric steroids, but CPI colitis mechanisms in steroid-experienced or refractory disease are unclear.MethodsUsing colon biopsies and blood from...

Transcriptomic profiling reveals a pronociceptive role for angiotensin II in inflammatory bowel disease.

Visceral pain is a leading cause of morbidity in inflammatory bowel disease (IBD), contributing significantly to reduced quality of life. Currently available analgesics often lack efficacy or have intolerable side effects, driving the need for a more complete understanding of the mechanisms causing pain. Whole transcriptome gene expression analysis was performed by bulk RNA sequencing of colonic biopsies from patients with ulcerative colitis (UC) and Crohn's disease (CD) reporting abdominal pain and compared with noninflamed control biopsies. Potential pronociceptive mediators were identified based on gene upregulation in IBD biopsy tissue and cognate receptor expression in murine colonic sensory neurons. Pronociceptive activity of identified mediators was assessed in assays of sensory neuron and colonic afferent activity. RNA sequencing analysis highlighted a 7.6-fold increase in the expression of angiotensinogen transcripts, Agt , which encode the precursor to angiotensin II (Ang II), in samples from UC patients ( P = 3.2 × 10 -8 ). Consistent with the marked expression of the angiotensin AT 1 receptor in colonic sensory neurons, Ang II elicited an increase in intracellular Ca 2+ in capsaicin-sensitive, voltage-gated sodium channel subtype Na V 1.8-positive sensory neurons. Ang II also evoked action potential discharge in high-threshold colonic nociceptors. These effects were inhibited by the AT 1 receptor antagonist valsartan. Findings from our study identify AT 1 receptor-mediated colonic nociceptor activation as a novel pathway of visceral nociception in patients with UC. This work highlights the potential utility of angiotensin receptor blockers, such as valsartan, as treatments for pain in IBD.

DOP01 Definitions of histological abnormalities in inflammatory bowel disease: an ECCO position paper

Abstract Background High quality histological examination of ileocolonic biopsies in inflammatory bowel disease (IBD) plays a critical role in optimising clinical management, investigative studies, and clinical trials. The correct assessment of histological features can confirm the diagnosis of IBD, assist with its subclassification (as ulcerative colitis or Crohn’s disease), facilitate the estimation of disease activity and disease extent, and aid the detection of mimics and complication. However, there are surprisingly few universal definitions of each histological abnormalities and the existing definitions are often inconsistent. The main practical concern is that histological scoring schemes, or guidelines on histological diagnosis, include detailed features, and many of these features have, paradoxically, no, or vague definitions. Furthermore, interobserver variability for many histological features in IBD is significantly high, possibly reflecting lack of precision. The aim of this paper is to review and assess any existing histologcal definitions and criteria, selecting the most appropriate where possible, and modifying them or writing new definitions where necessary. Methods The European Crohn's and Colitis Organisation (ECCO) and the project leaders formed a panel of experts in the IBD field, composed of pathologists and gastroenterologists to explore inconsistencies in the definitions of histological abnormalities using the best resources and evidence available. The panel examined existing definitions, peer reviews publications, scoring schemes, guidelines and textbooks. An important contribution was also given by their professional experience and knowledge. Results The literature review process confirmed that most current existing definitions often have no evidence base and vary between sources. The panel of experts developed 40 statements on histological definitions in IBD with accompanying supporting text for each statement. Conclusion The statements represent expert consensus with the support of evidence where available. Further possible development of this process will include attempts to grade histological changes, aiming to improve the consistency of pathological diagnosis, a reduction in currently high rates of interobserver variability, more precision in clinical trial work and research, and to facilitate development of new guidelines and scoring schemes for IBD.

OP17 IBD ulcers are characterized by bioactive interleukin-1 and transcriptomic hallmarks of stromal cell state reprogramming

Abstract Background The programs that perpetuate the inflammation and prevent epithelial repair in Inflammatory Bowel Disease (IBD) remain unclear. Interleukin (IL)-1 plays a role in the maintenance of mucosal homeostasis but also in IBD. Expansion of IL-1 expressing myeloid cells is a hallmark of IBD tissue, including severe and anti-TNF unresponsive disease, and IL-1 expression is highly localized to ulcer beds. However, little is known about the presence of bioactive IL-1 proteins in the cell-free mucosal environment of IBD, nor whether IL-1-driven programs affect epithelial regeneration in IBD ulcers. Methods We established a highly sensitive assay (~500-fold greater than ELISA) to assess bioactive extracellular IL-1 from previously cryopreserved IBD biopsies. We assessed a cohort of Crohn’s Disease (CD, n=23), Ulcerative Colitis (UC, n=18) and non-IBD (n=17) patients, with biopsies from paired inflamed/uninflamed regions (primarily colon but also ileal). We assessed IL-1 bioactivity, including IL-1α vs IL-1β contributions, and performed RNA-seq of samples’ matched cellular compartments. An ulcer-associated gene signature was interrogated in a single-cell (sc)RNA-seq cohort (n=42) of very early onset (VEO)IBD including monogenic disorders, as well as publicly available IBD bulk RNA-seq datasets and scRNA-seq of mouse models of colitis. Results IL-1α and IL-1β bioactivity corresponded with disease and ulcer severity in CD and UC. The most extreme signals were seen in select CD patients with deep ulceration. IL-1α was the predominant contributor to total IL-1 bioactivity in most patients although several with ulcers displayed IL-1β predominance. IL-1 bioactivity correlated with IL-1 transcripts in matched RNA-seq, and weighted gene co-expression network analysis revealed a compelling ulcer-specific module. This module contained transcription factors and genes related to cell state, validated in publicly available datasets (e.g. RISK cohort of ileal CD and scRNA-seq of murine DSS colitis), that when interrogated in a scRNA-seq dataset of VEOIBD (including patients with IL-10RA mutations characterized by deep ulcers), suggests an orchestrated IL-1-driven myeloid/stromal response to epithelial ulceration involving cell state reprogramming and loss of key myofibroblast populations. Conclusion Mucosal ulceration in IBD is associated with bioactive IL-1α and IL-1β proteins, and transcriptomic evaluation of the same correlates with bioactive signal. An ulcer-associated gene module, validated in other datasets, sheds light on IL-1 biology in intestinal epithelial repair. Results strongly suggest the IL-1 signaling pathway being an attractive and precision-based therapeutic target in subsets of IBD patients.

Dietary Iron Is Necessary to Support Proliferative Regeneration after Intestinal Injury

BackgroundTissue repair and regeneration in the gastrointestinal system are crucial for maintaining homeostasis, with the process relying on intricate cellular interactions and affected by micro- and macro-nutrients. Iron, essential for various biological functions, plays a dual role in tissue healing by potentially causing oxidative damage and participating in anti-inflammatory mechanisms, underscoring its complex relationship with inflammation and tissue repair. ObjectiveThe study aimed to elucidate the role of low dietary iron in gastrointestinal tissue repair. MethodsWe utilized quantitative iron measurements to assess iron levels in inflamed regions of patients with ulcerative colitis and Crohn’s disease. In addition, 3 mouse models of gastrointestinal injury/repair (dextran sulfate sodium-induced colitis, radiation injury, and wound biopsy) were used to assess the effects of low dietary iron on tissue repair. ResultsWe found that levels of iron in inflamed regions of both patients with ulcerative colitis and Crohn’s disease are elevated. Similarly, during gastrointestinal repair, iron levels were found to be heightened, specifically in intestinal epithelial cells across the 3 injury/repair models. Mice on a low-iron diet showed compromised tissue repair with reduced proliferation. In standard diet, epithelial cells and the stem cell compartment maintain adequate iron stores. However, during a period of iron deficiency, epithelial cells exhaust their iron reserves, whereas the stem cell compartments maintain their iron pools. During injury, when the stem compartment is disrupted, low iron levels impair proliferation and compromise repair mechanisms. ConclusionsLow dietary iron impairs intestinal repair through compromising the ability of epithelial cells to aid in intestinal proliferation.

Sirtuin 3 ameliorates inflammatory bowel disease via inhibiting intestinal inflammation and oxidative stress.

Sirtuin 3 involved in development of various diseases, but its role in inflammatory bowel disease is still unknown. We used inflammatory bowel disease biopsies, colitis animal model, and vitro cells RAW264.7 to study the role of Sirtuin 3 in the pathophysiology of inflammatory bowel disease. Sirtuin 3 negatively correlated with intestinal TNF-α. Sirt3 was less pronounced in pediatric and adult inflammatory bowel disease patients compared with corresponding control group. Sirtuin 3 activator Honokiol suppressed dextran sulfate sodium induced colonic manifestations, while Sirt3 inhibitor caused opposite results. Honokiol inhibited colonic oxidative stress by and reduced intestinal permeability. Honokiol repressed inflammatory response by reducing macrophage infiltration, pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 levels, and inhibiting activation of NF-κB p65 in the colitis mice. However, Sirt3 inhibitor amplified colonic oxidative stress and inflammatory response. In vitro study, Sirt3 inhibitor or siRNA Sirtuin 3 activated NF-κB p65 and enhanced TNF-α, IL-1β, and IL-6 secretion from LPS stimulated RAW264.7, while Honokiol remarkably attenuated these pro-inflammatory cytokines secretion. Finally, knockdown of Sirt3 in Caco-2 cells enhanced TNF-α induced intestinal barrier integrity injury. Sirtuin 3 negatively regulates inflammatory bowel disease progression via reducing colonic inflammation and oxidative stress. Sirtuin 3 is a promising therapeutic target in clinical application for inflammatory bowel disease therapy.

A machine learning approach toward automating spatial identification of LAG3+/CD3+ cells in ulcerative colitis

Over the past decade, automation of digital image analysis has become commonplace in both research and clinical settings. Spurred by recent advances in artificial intelligence and machine learning (AI/ML), tissue sub-compartments and cellular phenotypes within those compartments can be identified with higher throughput and accuracy than ever before. Recently, immune checkpoints have emerged as potential targets for auto-immune diseases. As such, spatial identification of these proteins along with immune cell markers (e.g., CD3+/LAG3+ T-cells) is a crucial step in understanding the potential and/or efficacy of such treatments. Here, we describe a semi-automated imaging and analysis pipeline that identifies CD3+/LAG3+ cells in colorectal tissue sub-compartments. While chromogenic staining has been a clinical mainstay and the resulting brightfield images have been utilized in AI/ML approaches in the past, there are associated drawbacks in phenotyping algorithms that can be overcome by fluorescence imaging. To address these tradeoffs, we developed an analysis pipeline combining the strengths of brightfield and fluorescence images. In this assay, immunofluorescence imaging was conducted to identify phenotypes followed by coverslip removal and hematoxylin and eosin staining of the same section to inform an AI/ML tissue segmentation algorithm. This assay proved to be robust in both tissue segmentation and phenotyping, was compatible with automated workflows, and revealed presence of LAG3+ T-cells in ulcerative colitis biopsies with spatial context preserved.

Definitions of Histological Abnormalities in Inflammatory Bowel Disease: an ECCO Position Paper.

Histological assessment of endoscopic biopsies in inflammatory bowel disease [IBD] plays an important role in clinical management, investigative studies, and clinical trials. Scoring schemes consisting of multiple histological items and offering considerable precision are widely available. However, definitions of histological abnormalities are often inconsistent. Furthermore, interobserver variability for their recognition and assessment may be high. The European Crohn's and Colitis Organisation [ECCO] formed an expert panel to explore definitions of histological abnormalities in IBD, with the aim of improving the quality of diagnosis and facilitating development of scoring schemes. The process confirmed that the current definitions often have no evidence base and vary between sources. Using available evidence and expert knowledge, the panel produced a series of ECCO consensus position statements on histological features in IBD.

Composition of the colon microbiota in the individuals with inflammatory bowel disease and colon cancer.

The human intestine is a habitat for microorganisms and, recently, the composition of the intestinal microbiota has been correlated with the etiology of diseases such as inflammations, sores, and tumors. Although many studies have been conducted to understand the composition of that microbiota, expanding these studies to more samples and different backgrounds will improve our knowledge. In this work, we showed the colon microbiota composition and diversity of healthy subjects, patients with inflammatory bowel disease (IBD), and colon cancer by metagenomic sequencing. Our results indicated that the relative abundance of prokaryotic and eukaryotic microbes differs between the healthy vs. tumor biopsies, tumor vs. IBD biopsies, and fresh vs. paraffin-embedded tumor biopsies. Fusobacterium, Escherichia-Shigella, and Streptococcus genera were relatively abundant in fresh tumor biopsies, while Pseudomonas was significantly elevated in IBD biopsies. Additionally, another opportunist pathogen Malasseziales was revealed as the most abundant fungal clade in IBD biopsies, especially in ulcerative colitis. We also found that, while the Basidiomycota:Ascomycota ratio was slightly lower in tumor biopsies compared to biopsies from healthy subjects, there was a significant increase in IBD biopsies. Our work will contribute to the known diversity of prokaryotic and eukaryotic microbes in the colon biopsies in patients with IBD and colon cancer.

RELT is overexpressed in human inflammatory bowel disease and breast cancer.

Abstract Receptor Expressed in Lymphoid Tissues (RELT) is a human TNFR member that activates NF-kB and is implicated in several cancers. We therefore sought to characterize the association of RELT with inflammatory bowel disease (IBD) and breast cancer (BC). Additionally, we further characterized the association of RELT with Filamin A (FLNA), an actin-binding protein that can promote tumorigenesis, or counteract tumors, depending on its cellular location. Female CB-17 SCID mice were injected with anti-CD40 monoclonal antibody to induce colitis and euthanized seven days later. Immunohistochemistry (IHC) was utilized to compare RELT expression in the mouse colitis model with uninjected control mice. IHC was utilized to compare the expression of RELT in biopsies of human IBD and non-inflamed tissue, as well as human BC versus non-malignant tissue. Luciferase assays and an X-gal morphology assay were utilized to examine cell death in the BC cell line MDA-MB-231 (231). RELT immunostaining is significantly increased in both mouse colitis and human IBD biopsies in comparison to that of species-matched non-inflamed tissue. An apparent association between colonic histological damage and RELT immunostaining was observed in both mice and human specimens. RELT staining was also increased in human BC biopsies versus patient-matched non-malignant tissue. RELT overexpression induced death in 231 cells, an effect that was not abrogated by a RELT mutation in the binding site for the OXSR1 kinase. However, co-expression of a S2152A mutant of FLNA did abrogate the ability of RELT to induce death in 231 cells. Collectively, these results implicate RELT as being important for human disease and further our understanding of the interaction between RELT and FLNA.

Loss of Claudin-3 Impairs Intestinal Barrier Function and Gut Microbiota to Promote Colitis

Objective: Inflammatory Bowel Disease (IBD) is multifactorial autoimmune disorder where dysregulation of the gut barrier and gut microbiota (Dysbiosis) play critical role in disease onset and progression. A leaky gut often coexists with the dysbiotic gut microbiota, however a pathobiological integration is not well understood. Intestinal claudin-3 expression is robust, and we have reported that its loss promotes gut permeability and colon cancer. Increased gut permeability and colon cancer risk characterize Inflammatory Bowel Disease (IBD). The current study was undertaken to delineate the status and role of claudin-3 expression in IBD. Methods: Multiple murine models of colitis and IBD patient biopsy were used. Claudin-3KO mice were used to determine causal role. Multiplex ELISA, RNAseq and 16S DNA sequencing helped determine inflammatory cytokines, transcriptomic changes, and gut microbiota diversity, respectively. Fecal microbiota transplantation (FMT) and antibiotic treatment studies were done to test the role of claudin-3/gut dysbiosis axis in promoting IBD. Results: A significant decrease in claudin-3 expression was observed in IBD patient samples or the colon of mice subjected to DSS- (2.5% w/v) or C. rodentium-colitis (5 x108 CFU/oral). colitis (p<0.001). To test the causal role, claudin-3KO mice were subjected to DSS-colitis (acute and chronic), and infectious colitis. A significant change in the body weight, colon thickness, and mucosal injury score (p<0.001) characterized the colitis challenged claudin-3KO versus WT mice. P-Stat3 expression was highly upregulated in colitis challenged claudin-3KO mice. Interestingly, administration of an antibiotic cocktail rescued the colitis severity in claudin-3KO mice. The 16s metagenomics further revealed that the gut microbiota of claudin-3KO mice is diverse and clustered distinctly from the WT mice. To determine if gut dysbiosis in claudin-3KO mice promotes susceptibility to colitis, we performed FMT from naïve Claudin-3KO mice to germ-free WT mice. When subjected to DSS-colitis, germ-free mice transplanted with Claudin3-KO gut microbiota showed significantly higher colitis severity versus WT (p<0.05). Conclusion: We summarize that the loss of colonic Cldn3 deregulates mucosal barrier integrity to induce gut dysbiosis and susceptibility to IBD. We propose that claudin-3 can be a novel therapeutic target in strengthening the gut barrier integrity to diminish IBD susceptibility. National Institute of Health, Veterans Administration This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

C-MET immunohistochemical expression in sporadic and inflammatory bowel disease associated lesions.

BACKGROUNDPost-colonoscopy colorectal cancer (CRC) rates for patients with inflammatory bowel disease (IBD) are unacceptably high. During colonoscopy, an intravenous fluorescent anti-c-MET probe may improve endoscopic detection of lesions. However, c-MET expression in IBD lesions is poorly defined, limiting translational studies. AIMTo comprehensively define c-MET expression in sporadic and IBD-associated colorectal carcinogenesis. METHODSc-MET expression was immunohistochemically assessed in 319 formalin-fixed paraffin-embedded tissue specimens, colonoscopically or surgically retrieved between 1994-2017. Tissue included: 30 normal colorectal biopsies, 30 hyperplastic polyps (HP), 31 sessile serrated lesions (SSL), 55 tubular/tubulovillous adenomas with low (TA-LGD, n = 32) or high grade dysplasia (TA-HGD, n = 23), 26 sporadic (s)-CRCs, 16 quiescent IBD biopsies, 11 active/inflamed IBD biopsies, 18 IBD-associated dysplastic lesions (IBD-dys), and 102 IBD-CRCs. Expression was scored by two independent observers as: 0 = absent, 1 = weak, 2 = moderate or 3 = strong. Mann-Whitney U and Kruskal-Wallis tests were used to assess significance. RESULTSPositive epithelial cytoplasmic and membranous c-MET expression was observed in all tissues, indicating there is ubiquitous expression in the colorectum. c-MET expression was weak in normal colonic epithelium compared with each of the sporadic colonic lesions, including TA-LGD (P < 0.001), TA-HGD (P = 0.004), HP (P < 0.001), SSL (P < 0.001), and s-CRC (P < 0.001). Specifically, in sporadic (non-IBD) lesions, expression was stronger in TA-LGD compared with normal mucosa (P < 0.001), and stronger in s-CRC compared with TA-HGD (P = 0.004). However, there was no significant difference between TA-LGD and TA-HGD (P = 0.852). Further, there was no difference in c-MET expression between HP and SSL (P = 0.065). In IBD, expression was weaker in quiescent colonic mucosa compared with inflamed colonic mucosa (P < 0.001). There was no difference between inflamed colonic mucosa and IBD-dys (P = 0.512) or IBD-CRC (P = 0.296). However, expression was stronger in IBD-dys (P < 0.001) and IBD-CRC (P < 0.001) compared with quiescent IBD colonic mucosa. CONCLUSIONThe characterisation of c-MET expression suggest that an intravenous probe may improve the endoscopic detection of lesions in both non-IBD patients and IBD patients with quiescent disease.

Entamoeba histolytica and Probable Effect on Production Microsatellite Instability in Colorectal Cancer

The mortality rate of Entamoeba histolytica is still high and approximately 100,000 per year. Environmental factors and different pathogens can cause microsatellite instability (MSI) positive, which may be one reason for colorectal cancer. MSI status can play an essential role in treatment.Moreover, E. histolytica might be one of the pathogens which raise the incidence of colorectal cancer.Therefore, the probable relationship of E. histolytica with MSI production was evaluated. Four hundred samples of colorectal biopsies based on pathological reports were divided into four groups: colitis, polyps, hyperplasia or dysplasia, and adenocarcinoma. The prevalence of E. histolytica was examined with PCR and immunohistochemical staining (IHC) for the light chain lectin HK-9.The adenocarcinoma formalin-fixed paraffin-embedded colorectal tumourssections were tested for MSI genes. We detectedE. histolytica in 6% and 4% of colitis samples by PCR and IHC technique, respectively. However, it didnot identify in polyp and hyperplasia samples. The MSI test was examined in the colorectal cancer group, which became positive in 19%. Entamoeba histolytica was detected in 26.3% (5/19) of MSI-positive and 2.5% (2/81) of MSI-negative cases by IHC technique however was not identified by PCR assay in this group. It is concluded PCR and IHC assay is recommended as complementary tests in colitis biopsies. Simultaneous PCR and IHC negative results could confirm the non-existence of the parasite with more confidence. Consequently, E. histolytica might be one of the biotic factors which raise the incidence of colorectal cancer because of the coincidence of the IHC positive results in MSI-positive adenocarcinoma.

P034 DISRUPTive liquid biopsies in Inflammatory Bowel Disease (DISRUPT-IBD): Release of exosomal and molecular tissue signals by transabdominal ultrasound?

Abstract Background A major drawback in diagnosis and monitoring of IBD are insufficient biomarkers that do not correlate well with tissue disease activity. Inflammation and cellular stress lead to an increased release of exosomes (Lipinski et al, 2019, EMBO J) carrying inflammatory signal proteins as cargo (Wozniak et al, 2020, J Cell Biol). Interestingly, colorectal cancer cells strongly release tumor markers after stimulation by sonography waves, probably through the disruptive energy of standard ultrasound (D’Souza et al, 2009, PNAS). We thus hypothesize that application of ultrasound waves on inflamed intestinal tissue in active IBD induces the release of tissue-specific exosomes that can be detected in the peripheral blood and used as novel biomarkers. Methods 26 patients with different degrees of disease activity and various ongoing therapies with IBD were included in a pilot trial. Serum was taken before and 30 minutes after diagnostic transabdominal ultrasound. Serum exosomes were precipitated (using ExoQuick) and exosomal (exo-)miRNA were isolated for miRNA sequencing using SeraMir protocol. Exosomal proteins were isolated for quantification of inflammatory markers (as exosomal cargo). Results We found a correlation between exo-miRNA concentration and disease severity, determined by clinical assessment scores and sonographic findings. Exo-miRNA sequencing revealed a select few miRNAs to be induced by sonography. However, the overall composition of annotated miRNA transcripts did not separate samples according to sampling timepoints. Among these “inducible” exo-miRNA, we found hsa-miR-942, which is involved in cell cycle and Wnt signaling in intestinal epithelial cells, to be significantly induced in higher grade intestinal inflammation. The exosomal protein concentrations did not correlate with disease severity at baseline, but were increased after sonography in severe intestinal inflammation. We did not find markers of the inflammasome apparatus as inducible exosomal cargos. Conclusion Sonography-induced exosomal markers, e.g., exo-miRNAs, could become novel biomarkers for intestinal inflammation in IBD. Further exploration of the functional role of inducible biomarkers and continued investigation of exosomal miRNA and protein profiling will be performed.

P098 Mucosal Microbiota Composition Predicts Infliximab Response in Inflammatory Bowel Diseases

Abstract Background The inflammatory bowel disease (iBD) etiology remain elusive and both genetic and environmental factors have been implicated in the establishment of systemic inflammatory reactions that typify IBD. A basic, modifiable environmental factor is the gut microbiota and dysbiosis seems to be a key factor in IBD pathogenesis. Nowadays, it is well known that anti-TNF therapy significantly improves the rates of remission in patients with inflammatory bowel disease (IBD), however, there is a subgroup of patients who do not respond to treatment. The aim of the present study is to profile changes in the mucosal gut microbiome before and after anti-TNF therapy and investigate its possibility to predict patient response at baseline. Methods Mucosal biopsy samples from IBD patients [14 Crohn’s disease patients (CD), 6 ulcerative colitis (UC) patients] and healthy controls (HC) were examined for differences in microbiota composition (16S rRNA gene sequencing) at baseline and upon completion of anti-TNF treatment, accordingly, via an in silico pipeline. Results Although no statistically significant differences at phylum level were noted, a relative reduction in Bacteroidetes and an increase in Actinobacteria, Fusobacteria and Chloroflexi were detected in IBD versus HC biopsies, however the microbiomes of UC, CD and HC display qualitative differences at the OTU level. At genus level, statistically significant differential abundance between the HC and IBD groups was observed. The genera Parabacteroides, Barnesiella, Butyricimonas, Ruminococcus_1, Ruminococcaceae_UCG013, Phascolarctobacterium, Ruminoclostridium_6, Paraprevotella as well as members of the Eubacterium_ruminantium group appear reduced in IBD, whereas Dialister abundance is increased. The genus Collinsella exhibits an induction during UC versus both HC and CD. Regarding anti-TNF treatment on the microbiome, Alpha-diversity is reduced after anti-TNF treatment. Beta-diversity indicates differences before and after treatment as well as between responders and non-responders. By using the biomarker discovery tool LEfSe, we identified microbial genera associated mainly with anti-TNF responders. Conclusion In the present study, we showed that the response to anti-TNF therapy is related to specific microbiota profiles in the gut mucosa. Correlation analysis between these parameters of response at baseline showed that the assessment of microbial taxa can further distinguish responders from non-responders.

P072 Melanocortin MC3 and MC5 receptors expression is different according to colonic disease activity in Crohn’s Disease and Ulcerative Colitis biopsies: results from an immunohistochemical observational study

Abstract Background MC3-R and MC5-R receptors belong to the complex melanocortin system, which has shown a strong immunomodulatory activity in several studies. Data on the role of these receptors in relation to inflammatory bowel disease are still missing and not fully elucidated. In this observational study we wanted to evaluate the expression profile of them in the colonic mucosa of Crohn’s Disease and Ulcerative Colitis patients both in the tracts directly affected by the disease activity and in the tracts spared. Methods We conducted on colonic biopsies of patients with histological diagnosis of inflammatory bowel disease immunohistochemical analyses in order to assess the degree of expression of MC3-R and MC5-R. Biopsies were performed on both the traits with macroscopic signs of inflammation and the macroscopically normal traits to assess whether the expression of the two receptors was different in relation to disease activity. Results In both Crohn’s disease and ulcerative colitis diseased tracts MC3-R (CD: +7.7 fold vs normal mucosa, P &amp;lt; 0.01; UC: +5.6 fold vs normal mucosa, P &amp;lt; 0.01) and MC5-R (CD: +5.5 fold vs normal mucosa, P &amp;lt; 0.01; UC: +8.1 fold vs normal mucosa, P &amp;lt; 0.01) were significantly increased compared to healthy mucosa. Conclusion MC3-R and MC5-R are expressed in the colon of patients with Crohn’s Disease and Ulcerative Colitis. In addition, expression is different with a higher degree of expression in the traits most affected by disease activity in both Crohn’s Disease and Ulcerative Colitis providing a potential use of these receptors in inflammatory bowel diseases pharmacology.

Branching crypts in inflammatory bowel disease revisited.

Histologic sections from patients with inflammatory bowel disease (IBD) usually exhibit crypts with architectural distortions and branching crypts. It has been postulated that crypt branching should be assessed only in well-oriented, upright crypts. However, those crypts are mostly found in sections from colectomy specimens and colon mucosectomies. Sections from endoscopic biopsies are fortuitously cut in a horizontal plane, a procedure mostly revealing cross-cut crypt rings. In endoscopic biopsies from UC patients we previously detected cross-cut crypts heralding the crest domain of branching crypts. Recently, the scrutiny of biopsies from IBD patients revealed that branching-crest domains concurred either with crypts in symmetric branching, typified by twin, amalgamating back-to-back isometrics crypt-rings, or with crypts in asymmetric branching, characterized by ≥2 amalgamating anisometric crypt-rings; both symmetric and asymmetric branching-crest domains were encased by a thin muscularis mucosae. Quantitative studies in biopsies from Swedish and German patients with IBD showed that crypts in asymmetric branching outnumbered those in symmetric branching. Because crypt-branching seldom occurs in the normal colon in adults and considering that colon crypts typically divide once or twice during a lifetime, the accruing of asymmetric branching crypts in IBD biopsies emerges as a significant histologic parameter. Although the biological significance of asymmetric crypt-branching in IBD remains at present elusive, their occurrence deserves to be further investigated. The future policy will be to include in our pathologic reports, the number of crypts in asymmetric branching, in order to monitor their frequency in prospective surveillance biopsies in patients with IBD.

DNA Repair Protein Expression and Oxidative/Nitrosative Stress in Ulcerative Colitis and Sporadic Colorectal Cancer.

Chronic inflammation generates large quantities of reactive oxygen and nitrogen species that damage DNA. DNA repair is important for cellular viability and genome integrity. Expression levels of the DNA repair proteins OGG1, XPA, MLH1, PARP1, and XRCC6, which function in base excision repair, nucleotide excision repair, mismatch repair, single-strand break repair and double-strand break repair, respectively, were assessed using immunohistochemistry in ulcerative colitis and sporadic colorectal cancer biopsies. Levels of oxidative/ nitrosative stress biomarkers were also assessed. Ulcerative colitis and colorectal cancer lesions expressed significantly higher levels of all DNA repair proteins and oxidative/ nitrosative stress biomarkers compared to normal colonic mucosa. Ulcerative colitis had the highest XPA and XRCC6 expression. Oxidative/nitrosative stress is prevalent in the colon of both diseases. Nucleotide excision repair and non-homologous end-joining double-strand break repair may be compromised in colorectal cancer, but not in ulcerative colitis.