Ulcerative Colitis: Bojarski C

Schulzke JD, Ploeger S, Amasheh M, Fromm A, Zeissig S, Troeger H, Richter J, Bojarski C, Schumann M, Fromm M. · Department of General Medicine & Pathophysiology of Enteral Nutrition, Charité, Campus Benjamin Franklin, Berlin, Germany. · Ann N Y Acad Sci. · Pubmed #19538319 No free full text.

Abstract: The epithelium in inflamed intestinal segments of patients with Crohn's disease is characterized by a reduction of tight junction strands, strand breaks, and alterations of tight junction protein content and composition. In ulcerative colitis, epithelial leaks appear early due to micro-erosions resulting from upregulated epithelial apoptosis and in addition to a prominent increase of claudin-2. Th1-cytokine effects by interferon-gamma in combination with TNFalpha are important for epithelial damage in Crohn's disease, while interleukin-13 (IL-13) is the key effector cytokine in ulcerative colitis stimulating apoptosis and upregulation of claudin-2 expression. Focal lesions caused by apoptotic epithelial cells contribute to barrier disturbance in IBD by their own conductivity and by confluence toward apoptotic foci or erosions. Another type of intestinal barrier defect can arise from alpha-hemolysin harboring E. coli strains among the physiological flora, which can gain pathologic relevance in combination with proinflammatory cytokines under inflammatory conditions. On the other hand, intestinal barrier impairment can also result from transcellular antigen translocation via an initial endocytotic uptake into early endosomes, and this is intensified by proinflammatory cytokines as interferon-gamma and may thus play a relevant role in the onset of IBD. Taken together, barrier defects contribute to diarrhea by a leak flux mechanism (e.g., in IBD) and can cause mucosal inflammation by luminal antigen uptake. Immune regulation of epithelial functions by cytokines may cause barrier dysfunction not only by tight junction impairments but also by apoptotic leaks, transcytotic mechanisms, and mucosal gross lesions.

Bojarski C, Günther U, Rieger K, Heller F, Loddenkemper C, Grünbaum M, Uharek L, Zeitz M, Hoffmann JC. · Medical Department I Gastroenterology, Infectious Diseases, Rheumatology, Charité Campus Benjamin Franklin, Berlin, Germany. · Endoscopy. · Pubmed #19418398 No free full text.

Abstract: BACKGROUND AND STUDY AIMS: Conventional histology with hematoxylin and eosin (H&E) staining is the accepted standard for diagnosing acute intestinal graft-versus-host disease (GvHD). Confocal endomicroscopy (CEM) is a noninvasive method that allows in vivo histology to be performed during endoscopy. The aim of this study was to evaluate CEM for the diagnosis of acute intestinal GvHD. PATIENTS AND METHODS: This observational pilot study conducted between September 2006 and August 2008 included patients with acute diarrhea after stem cell transplantation, infectious diarrhea, or active ulcerative colitis. CEM (EC-3870CIFK, Pentax, Tokyo, Japan) was performed after intravenous injection of fluorescein 10% and topical application of acriflavine 0.05%. RESULTS: A total of 35 patients with acute diarrhea after stem cell transplantation were examined. In 16 patients, CEM and histology showed no evidence of GvHD. In 14/19 patients with histologically confirmed GvHD, the diagnosis could already be established by CEM during ongoing endoscopy. In GvHD grade IV, near complete destruction of the colonic crypts ("flat mucosa") was visible. Control patients with infectious colitis (N = 15) or ulcerative colitis (N = 15) displayed inflammatory changes but no evidence of GvHD. Altogether, sensitivity of CEM was 74% and specificity was 100 %. CONCLUSIONS: CEM improves rapid diagnosis of acute intestinal GvHD with high accuracy while performing endoscopy. Platelet transfusions and unnecessary biopsy acquisition can be avoided once acute intestinal GvHD has been diagnosed in vivo.

Schulzke JD, Bojarski C, Zeissig S, Heller F, Gitter AH, Fromm M. · Medizinische Klinik I, Department of Gastroenterology, Infectious Diseases and Rheumatology, Charité, Campus Benjamin Franklin, 12200 Berlin, Germany. · Ann N Y Acad Sci. · Pubmed #17057208 No free full text.

Abstract: Epithelial barrier function is determined by trans- and paracellular permeabilities, the latter of which is mainly influenced by tight junctions (TJs) and apoptotic leaks within the epithelium. The present article aims to present experimental evidence for a functional role of epithelial apoptoses by means of cell culture models as well as in tissues from patients with inflammatory bowel disease. It is shown that epithelial apoptoses are sites of elevated conductance within the intestinal epithelium and that proinflammatory cytokines like TNF-alpha upregulate both the apoptotic rate and single apoptotic conductivity, making cytokine-induced apoptosis functionally far more relevant than is spontaneous apoptosis. In ulcerative colitis and Crohn's disease (CD), but not in collagenous colitis, apoptotic rates are increased to about 5%, in mild-to-moderately inflamed colon specimens, where as the control apoptotic rate is about 2%. Thus, epithelial apoptoses lead to a loss of ions and water into the intestinal lumen, causing leak flux diarrhea and enabling small antigens of <4,000 Da in the intestinal lumen to enter the intestinal mucosa, thereby perpetuating inflammatory responses. In addition to TNF-alpha, interleukin (IL)-13 is an important inductor of epithelial apoptosis in Th2 immune responses. Therapeutically,TNF-alpha-antibodies (infliximab) can restore barrier function in Crohn's disease by downregulating epithelial apoptoses, while epithelial TJs are unaffected.

Heller F, Florian P, Bojarski C, Richter J, Christ M, Hillenbrand B, Mankertz J, Gitter AH, Bürgel N, Fromm M, Zeitz M, Fuss I, Strober W, Schulzke JD. · Department of Gastroenterology, Charité, Campus Benjamin Franklin, Berlin, Germany. · Gastroenterology. · Pubmed #16083712 No free full text.

Abstract: BACKGROUND & AIMS: Ulcerative colitis (UC) is characterized by a Th2 immune response with inflammation and epithelial barrier dysfunction. So far, Th2 cytokines have not been shown to directly influence epithelial barrier function. METHODS: Lamina propria mononuclear cells (LPMCs) were stimulated and interleukin (IL)-13 was measured by enzyme-linked immunosorbent assay. Functional IL-13 and IL-4 effects were studied on HT-29/B6 colonic epithelial cells in Ussing chambers and by conductance scanning. Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assays. IL-13/IL-4 receptors were analyzed by reverse-transcription polymerase chain reaction and immunofluorescence. Western blotting combined with immunofluorescence was used to detect tight junction proteins. Furthermore, restitution velocity was measured. Finally, mucosal biopsy specimens from patients with UC were compared with cultured cells for these features. RESULTS: LPMCs from patients with UC produced large amounts of IL-13 (985 +/- 73 pg/mL), much more than from controls or patients with Crohn's disease. IL-13Ralpha1 and IL-4Ralpha receptors were present in HT-29/B6 cells and colonic epithelial cells of control patients and patients with UC. IL-13 had a dose-dependent effect on transepithelial resistance of HT-29/B6 monolayers (reduction to 60% +/- 4%), whereas IL-4 had no effect. This was due to an increased number of apoptotic cells (5.6-fold +/- 0.9-fold) and an increased expression of the pore-forming tight junction protein claudin-2 to 295% +/- 37%, both of which contributed equally. Finally, epithelial restitution velocity decreased from 15.1 +/- 0.6 to 10.6 +/- 0.5 microm/h after treatment with IL-13. Parallel changes were observed in human samples, with an increase in claudin-2 expression to 956% +/- 252%. CONCLUSIONS: IL-13 was identified as an important effector cytokine in UC that impairs epithelial barrier function by affecting epithelial apoptosis, tight junctions, and restitution velocity.