Introduction

The intestinal epithelium serves as a site for digestion and absorption of the nutrients and dietary factors, while forming the selective barrier to separate the body’s internal environment from the external luminal environment. The intestinal barrier is established by a combination of several mechanisms, including the mucous layer, antimicrobial peptides, and the intercellular tight junction (TJ)⁽¹⁾. The TJ structure is a multiprotein complex composed of both transmembrane proteins such as claudins and occludin, and cytosolic plaque proteins such as zonula occludens and cingulin, and regulates the paracellular passage of macromolecules, ions, and water. Our and other research groups have shown that the regulation of the intestinal TJ barrier is closely related to intestinal microbial metabolism^(2-4), however, the precise underlying mechanisms are still unclear.

Aims & Methods

The aim of this study was to investigate the role of intestinal microflora in the regulation of the colonic TJ barrier using mice and Caco-2 and MDCKII epithelial cells. In particular, we focused on the molecular mechanisms of n-butyrate-mediated expression of claudin-23. To investigate the effect of intestinal microflora on the TJ expression, RNA sequencing analysis was performed in the colonic tissues from germ-free (GF) and specific pathogen-free (SPF) mice. Claudin-23 expression was also examined in the colon of experimental colitis mice. Human intestinal Caco-2 cells were treated with various microbial metabolites and components including n-butyrate. The TJ barrier function was assessed by measuring the transepithelial resistance (TER) and FITC-dextran (FD) permeability. Claudin-23 expression and transcriptional activity were examined by qRT-PCR, immunoblot, immunofluorescence, and luciferase reporter analyses. The siRNA targeting SP1 and the selective inhibitor of AMPK were used in combination in some experiments. To investigate the role of claudin-23 in the epithelial barrier function, TER and FD permeability were measured in MDCKII epithelial cells stably expressing human claudin-23.

Results

Among several TJ molecules, the claudin-23 mRNA was lower in the colon of GF mice than that of the SPF mice. Claudin-23 mRNA expression was higher in the lower intestinal segments, such as ileum, cecum, and colon, compared with those in the duodenum and jejunum. Claudin-23 expression in the colitis mice was downregulated compared to the normal mice. n-butyrate, but not other microbial metabolites or components, upregulated the claudin-23 expression at both mRNA and protein levels in intestinal Caco-2 cells. N-butyrate enhanced the intestinal TJ barrier integrity, indicated by increased TER and decreased FD permeability. Luciferase reporter assay showed that n-butyrate increased the claudin-23 transcriptional activity. The SP1 siRNA and AMPK inhibitor reduced the n-butyrate-mediated claudin-23 expression and promoter activity. Exogenously expressed claudin-23 localized to the junctional region of MDCKII cells, but did not affect the TER and FD permeability.

Conclusion

Claudin-23 expression in the mouse colon is regulated by a microbial metabolite, n-butyrate. Our results suggest that the transcription factor, SP1, and the AMPK pathway are involved in its transcriptional regulation. Although the precise role of claudin-23 in the intestine is still unclear, the n-butyrate-mediated claudin-23 expression may contribute to the intestinal homeostasis.

References

(1) Suzuki T. Anim Sci J. 2020;91(1):e13357.
(2) Isayama K et al. Exp Cell Res. 2023;425(2):113528.
(3) Yokoo K et al. FASEB J. 2021;35(11):e21854.
(4) Tinh NTT et al. Foods. 2021;10(2):240.

Clinical Case Summary

Splenic granulomas are a rare extraintestinal manifestation of Crohn’s disease (CD). In previously reported cases, the diagnosis was confirmed by biopsy. However, due to the increased risk of complications associated with biopsy, confirmation by imaging is desirable.
52-year-old male patient presented with a previously diagnosed, currently untreated CD.
Symptoms:

• Abdominal pain in the right lower quadrant for several weeks, postprandial
• Bowel movements: 4-6 times/day for a few weeks, liquid consistency
• No fever or weight loss
• Palpation: tenderness in the lower right abdomen

Findings:

• C-reactive protein and leukocytes: not elevated
• Calprotectin: 184ug/g. Stool culture and intestinal cytomegaly virus PCR biopsy negative
• Tuberculosis interferon-g release assay: negative
• Colonoscopy and magnetic resonance enterography (MRE): ileitis of terminal Ileum (Fig. 1)
• MRE: multiple T2w-hyperintense splenic lesions, increased in number since last imaging 2024 (Fig. 2)
• B-mode ultrasound: splenomegaly, round nodules of mixed echogenicity (Fig. 3)
• Contrast-enhanced ultrasound (CEUS): 1,5ml contrasting agent (sulphur hexafluoride microbubbles): arterial isoenhancement and late phase hypoenhancement of nodules (Fig. 3), atypical for haemangiomas
• 18-Fluorodeoxyglucose positron emission tomography with computed tomography: no uptake in the spleen (Fig. 4)

After excluding malignancy, abscesses, sarcoidosis, and infectious causes, the splenic granulomatous lesions represented an extraintestinal manifestation of CD. The patient was started on prednisolone, 60mg/day, resulting in marked clinical improvement in 4 days; with reduced abdominal pain and decreased stool frequency. Patient declined recommended maintenance therapy with ustekinumab.
This CEUS pattern is novel to CD and resembles previously reported enhancement patterns of inflammatory lesions. This is a rare reported case of splenic granulomas as an extraintestinal manifestation of CD diagnosed non-invasively by CEUS.

References

Figure 1: Colonoscopy shows 2-4mm aphthous ulcers in the terminal Ileum
Figure 2: (A)T2-Haste and (B)T2-STIR MRE depicting multiple hyperintense splenic lesions
Figure 3: B-mode (left) and CEUS (right) of the splenic lesions. (A) Nodules appear mixed in echogenicity, nodules show isoenhancement during the arterial phase. (B) Nodules exhibit hypoenhancement in the late phase
Figure 4: 18F-Fluorodeoxyglucose (FDG) positron emission tomography with computed tomography shows no uptake of FDG in the spleen
1. Castellani L, Sartini A, Marocchi M, Balbi T, Belluzzi A. Splenic granulomas in a patient with severe Crohn's disease associated with multiple extraintestinal manifestations. Inflamm Bowel Dis. 2011 Jun;17(6):E35-7. doi: 10.1002/ibd.21665. Epub 2011 Feb 11. PMID: 21319276.
2. Schulz C, von Arnim U, Kuester D, Fischbach F, Malfertheiner P. Milzbefall - seltene extraintestinale Manifestation bei Morbus Crohn [Splenic granulomas - rare extraintestinal manifestation of Crohn's disease]. Z Gastroenterol. 2010 Dec;48(12):1367-70. German. doi: 10.1055/s-0029-1245562. Epub 2010 Dec 1. PMID: 21125512
3. Safai Zadeh E, Prosch H, Ba-Ssalamah A, Findeisen H, Alhyari A, Raab N, Görg C. Contrast-enhanced ultrasound of the liver: basics and interpretation of common focal lesions. Rofo. 2024 Aug;196(8):807-818. English, German. doi: 10.1055/a-2219-4726. Epub 2024 Jan 4. PMID: 38176437

Disclosure

Travel grant from Johnson & Johnson

Clinical Case Summary

Introduction: PSC is closely associated with IBD and affects up to 3.6% of Crohn's disease patients, while AIH is also more prevalent in IBD patients, in up to 16% of patients.
Case report: We report a female patient who, at the age of 14, presented with right hypochondrial pain and abnormal liver biochemistry (SGOT: 44 U/l, SGPT: 145 U/l, γ-GT: 300 U/l, ALP: 421 U/l, TBL: 1 mg/dL). The patient underwent MRCP (Figure A) which revealed local strictures with prostenotic dilatation in both intrahepatic and extrahepatic bile ducts, suggestive of PSC. One year later the patient presented with severe abdominal pain and bloody diarrhea. Ileocolonoscopy showed terminal ileitis (Figure B) and segmental colitis. Histological evaluation (Figure C) showed disruption of the architecture, focal erosions of the epithelium, mild mucopenia, inflammatory infiltrate in the dermis, sites of cryptitis and focal formation of crypt abscesses with extension of inflammation to the muscularis mucosae, suggestive of Crohn’s Disease. Two years later, in a regular laboratory test, the patient had abnormal liver function tests (SGOT: 211 U/l, SGPT: 603 U/l, γ-GT: 54 U/l, ALP: 105 U/l, TBL: 0.9 mg/dl). Further evaluation with immunoassay revealed ANA (+) 1/80, AMA (-), SMA (+) 1/160, + F-actin, anti-LKM (-), anti-LC (-), anti-LM (-), p ANCA (+) 1/80, so the patient underwent percutaneous liver biopsy with findings of portal spaces with presence of waxy-containing macrophages, thin fibrous septa, parenchyma with centrolobular necrosis with aggregates of inflammatory cells and waxy macrophages, suggestive of Autoimmune Hepatitis. Today, the patient is in clinical remission under treatment with Ursodeoxycholic acid, Ustekinumab and Mycophenolate Mofetil.
Conclusion: The association of IBD with PSC, AIH and variant forms is now known, however the complexity of the diseases presents a challenge for the clinician and the provision of individualized care.

References

1. Ballotin VR, Bigarella LG, Riva F, Onzi G, Balbinot RA, Balbinot SS, Soldera J. Primary sclerosing cholangitis and autoimmune hepatitis overlap syndrome associated with inflammatory bowel disease: A case report and systematic review. World J Clin Cases. 2020 Sep 26;8(18):4075-4093.
2. Saich R, Chapman R. Primary sclerosing cholangitis, autoimmune hepatitis and overlap syndromes in inflammatory bowel disease. World J Gastroenterol. 2008 Jan 21;14(3):331-7.
3. Rocha HC, Vilela EG. Clinical aspects and prognosis of patients with inflammatory bowel disease associated with autoimmune liver diseases. Gastroenterol Hepatol. 2022 Feb;45(2):83-90. English, Spanish.
4. Malik T, A, Gutierrez A, M, McGuire B, Zarzour J, G, Mukhtar F, Bloomer J: Autoimmune Hepatitis-Primary Sclerosing Cholangitis Overlap Syndrome Complicated by Crohn’s Disease. Digestion 2010;82:24-26.

Clinical Case Summary

Introduction: Eosinophilic enteritis (EoEo) is a rare condition characterized by eosinophilic infiltration of the intestinal wall without an identifiable secondary cause. Clinical presentation varies depending on the affected intestinal segment and layer. While mucosal involvement causes digestive symptoms, muscular involvement may lead to obstruction, and serosal involvement—least common—can present with eosinophilic ascites.
Case Report: A 15-year-old male presented with epigastric pain, vomiting, and oral intolerance. Laboratory tests revealed marked eosinophilia (>5,000/μL). Abdominal CT showed free fluid and ileocecal wall thickening. Diagnostic paracentesis revealed ascitic fluid with a high leukocyte count and eosinophil predominance. Endoscopic studies revealed ileitis, typhlitis, and duodenitis. Biopsies confirmed eosinophilic infiltration of the intestinal wall. Other causes of eosinophilia, including infections and malignancy, were ruled out. The patient was treated with intravenous corticosteroids, with good clinical response, and discharged on oral budesonide. A relapse occurred after tapering steroids, prompting initiation of azathioprine for maintenance. The patient remains clinically stable without further hospitalizations.
Discussion: EoEo with eosinophilic ascites is rare and should be considered in the differential diagnosis of unexplained ascites, particularly in patients with peripheral eosinophilia. Key diagnostic findings include eosinophil-predominant ascitic fluid and GI tract biopsies with eosinophilic infiltration. Early recognition and treatment are essential to prevent complications. It is crucial to rule out parasitic and infectious causes before initiating corticosteroid therapy to avoid worsening an undiagnosed infection.

Clinical Case Summary

Background and aim: We report the case of a 32-year-old North African man with no significant medical history, presenting with a two-day history of right lower quadrant abdominal pain.
Material and methods: Physical exam revealed localized tenderness with mild guarding, without peritonitis. Blood tests showed elevated C-reactive protein, but clinical scores suggested low likelihood of appendicitis. Ultrasound showed fatty infiltration near the cecum and reactive lymph nodes. A CT scan revealed terminal ileum wall thickening and mesenteric fat stranding anterolateral to the cecum, with a normal appendix. Elevated fecal calprotectin and imaging findings raised suspicion of inflammatory bowel disease (IBD). Colonoscopy up to the terminal ileum showed normal mucosa, and biopsies were histologically unremarkable. Microbiological tests were negative. Empirical antibiotic therapy with ciprofloxacin and metronidazole led to rapid clinical and biochemical improvement.
Results: After one week of antibiotics, the patient achieved complete remission. Follow-up CT enterography showed persistent perivisceral fat thickening without enhancement, suggesting a necrotic focus near the cecum, with normal-appearing distal ileum. A multidisciplinary team including gastroenterologists, radiologists, and surgeons concluded the most likely diagnosis was epiploic appendagitis, based on localized pain, imaging showing a fatty lesion near the cecal serosa, and the favorable response to treatment. IBD, including Crohn’s disease, was ruled out due to the absence of supporting endoscopic, histologic, or radiologic findings. Terminal ileum thickening was considered reactive, and elevated calprotectin interpreted as a nonspecific marker.
Conclusions: This case illustrates how epiploic appendagitis can mimic the presentation of IBD. In such ambiguous scenarios, a multidisciplinary approach is essential to explore less common differential diagnoses.

References

Image 1: contrast enhanced abdominal CT scan. Increased thickness of the terminal ileal mucosa and edema of the mesenteric fat anterolateral to the cecum, with a normal appendix.

Introduction

Barrett’s mucosal neoplasia can be endoscopically cured with minimal risk of lymph node metastasis while submucosally invasive neoplasia poses higher risk and usually requires surgery. Endoscopic optical diagnosis is often challenging to differentiate between the two. We aim to develop an artificial intelligence (AI) system using a deep neural network to stage Barrett’s neoplasia into mucosal (LGD, HGD, pT1a) and submucosally invasive (pT1b) lesions.

Aims & Methods

A VGG16-based deep neural network was used for the staging AI system. The model was trained with 69 images which were carefully selected from 79,159 frame images with histological ground truth. As a pre-trained model for training, the model from initial Barrett’s detection and delineation system was used, which was trained for 1,090,171 images from 161 Barrett's patients¹. We tested staging AI on pre-recorded images and its performance was compared to two experts who regularly perform Barrett's endoscopic resections.

Results

68 neoplastic images (white light, enhanced imaging, near focused/magnification) were used. 43 were mucosal (2 LGD, 31 HGD, 10 pT1a) and 25 were submucosal (6 pT1bSM1 and 19 pT1bSM2/3). The sensitivity, specificity and accuracy of AI were 80%, 84% and 82% while that of experts were 74%, 78% and 76% with no statistical difference (p=0.507).

Conclusion

This suggests that the staging AI system is good at differentiating submucosal neoplasia and it can perform as well as experts. It has the potential to help guide expert clinicians to decide if endoscopic resection of Barrett's neoplasia can be curative while helping non-expert to achieve more yield in targeted biopsy. However, more work is still needed to further refine and validate this staging AI model.

References

1. Mohamed Abdelrahim, Masahiro Saiko, Naoto Maeda, Ejaz Hossain, Asma Alkandari, Sharmila Subramaniam, Adolfo Parra-Blanco, Andres Sanchez-Yague, Emmanuel Coron, Alessandro Repici, Pradeep Bhandari, Development and Validation of Artificial Neural Networks Model for Detection of Barrett’s Neoplasia, a Multicenter Pragmatic Non-Randomized Trial, Gastrointestinal Endoscopy (2022)