Ulrich Wahnschaffe

Changes in expression and distribution of claudin-2, -5 and -8 lead to discontinuous tight junctions and barrier dysfunction in active Crohn's disease

Background: Epithelial barrier function is impaired in Crohn’s disease. Aim: To define the underlying cellular mechanisms with special attention to tight junctions. Methods: Biopsy specimens from the sigmoid colon of patients with mild to moderately active or inactive Crohn’s disease were studied in Ussing chambers, and barrier function was determined by impedance analysis and conductance scanning. Tight junction structure was analysed by freeze fracture electron microscopy, and tight junction proteins were investigated immunohistochemically by confocal laser scanning microscopy and quantified in immunoblots. Epithelial apoptosis was analysed in terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling and 4′,6-diamidino-2-phenylindole staining. Results: Patients with active Crohn’s disease showed an impaired intestinal barrier function as indicated by a distinct reduction in epithelial resistance. As distribution of conductivity was even, focal epithelial lesions (eg, microerosions) did not contribute to barrier dysfunction. Instead, freeze fracture electron microscopy analysis showed reduced and discontinuous tight junction strands. Occludin and the sealing tight junction proteins claudin 5 and claudin 8 were downregulated and redistributed off the tight junction, whereas the pore-forming tight junctions protein claudin 2 was strongly upregulated, which constitute the molecular basis of tight junction changes. Other claudins were unchanged (claudins 1, 4 and 7) or not detectable in sigmoid colon (claudins 11, 12, 14, 15 and 16). Claudin 2 upregulation was less pronounced in active Crohn’s disease compared with active ulcerative colitis and was inducible by tumour necrosis factor α. As a second source of impaired barrier function, epithelial apoptosis was distinctly increased in active Crohn’s disease (mean (SD) 5.2 (0.5)% v 1.9 (0.2)% in control). By contrast, barrier function, tight junction proteins and apoptosis were unaffected in Crohn’s disease in remission. Conclusion: Upregulation of pore-forming claudin 2 and downregulation and redistribution of sealing claudins 5 and 8 lead to altered tight junction structure and pronounced barrier dysfunction already in mild to moderately active Crohn’s disease.

Effect of chronic Giardia lamblia infection on epithelial transport and barrier function in human duodenum

Background:Giardia lamblia causes infection of the small intestine, which leads to malabsorption and chronic diarrhoea. Aim: To characterise the inherent pathomechanisms of G lamblia infection. Methods: Duodenal biopsy specimens from 13 patients with chronic giardiasis and from controls were obtained endoscopically. Short-circuit current (ISC) and mannitol fluxes were measured in miniaturised Ussing chambers. Epithelial and subepithelial resistances were determined by impedance spectroscopy. Mucosal morphometry was performed and tight junction proteins were characterised by immunoblotting. Apoptotic ratio was determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling staining. Results: In giardiasis, mucosal surface area per unit serosa area was decreased to 75% (3%) of control, as a result of which epithelial resistance should increase. Instead, epithelial resistance of giardiasis biopsy specimens was decreased (19 (2) vs 25 (2) Ω cm2; p<0.05) whereas mannitol flux was not significantly altered (140 (27) vs 105 (16) nmol/h/cm2). As structural correlate, reduced claudin 1 expression and increased epithelial apoptosis were detected. Furthermore, basal ISC increased from 191 (20) in control to 261 (12) µA/h/cm2 in giardiasis. The bumetanide-sensitive portion of ISC in giardiasis was also increased (51 (5) vs 20 (9) µA/h/cm2 in control; p<0.05). Finally, phlorizin-sensitive Na+–glucose symport was reduced in patients with giardiasis (121 (9) vs 83 (14) µA/h/cm2). Conclusions:G lamblia infection causes epithelial barrier dysfunction owing to down regulation of the tight junction protein claudin 1 and increased epithelial apoptoses. Na+-dependent d-glucose absorption is impaired and active electrogenic anion secretion is activated. Thus, the mechanisms of diarrhoea in human chronic giardiasis comprise leak flux, malabsorptive and secretory components.

Pancreatic pseudocysts: observation, endoscopic drainage, or resection?

BACKGROUND Pancreatic pseudocysts are a common complication of acute and chronic pancreatitis. They are diagnosed with imaging studies and can be treated successfully with a variety of methods: endoscopic transpapillary or transmural drainage, percutaneous catheter drainage, laparoscopic surgery, or open pseudocystoenterostomy. METHODS Relevant publications that appeared from 1975 to 2008 were retrieved from the MEDLINE, PubMed and EMBASE databases for this review. RESULTS Endoscopic pseudocyst drainage has a high success rate (79.2%) and a low complication rate (12.9%). Percutaneous drainage is mainly used for the emergency treatment of infected pancreatic pseudocysts. Open internal drainage and pseudocyst resection are surgical techniques with high success rates (>92%), but also higher morbidity (16%) and mortality (2.5%) than endoscopic treatment (mortality 0.7%). Laparoscopic pseudocystoenterostomy, a recently introduced procedure, is probably similar to the endoscopic techniques with regard to morbidity and mortality. CONCLUSIONS An interdisciplinary approach is best suited for the safe and effective stage-specific treatment of pancreatic pseudocysts. The different interventional techniques that are currently available have yet to be compared directly in randomized trials.

Through the endoscope balloon dilation of ileocolonic strictures: prognostic factors, complications, and effectiveness

Background/aimsAbout half of all Crohn’s disease (CD) patients undergo surgery at some point, many because of strictures. An alternative possibility is to dilate strictures endoscopically. However, little is known about prognostic factors.Patients and methodsThirty-two patients with primary CD (n = 2), radiogenic strictures (n = 1), or postoperative strictures (27 because of CD; 2 after resection because of cancer), were planned to undergo colonoscopic dilatation of which 25 patients were dilated (10 men; 15 women; median age 48). Length of stenosis, diameter of stricture, balloon size, smoking status, ulcer in the stricture, passage postdilatation, hemoglobin level, complications, redilatation, and subsequent surgery were recorded. Only patients with at least 6 months follow up were included.ResultsFive out of 32 patients had no stenosis, marked inflammation, or fistulas adjacent to the stricture. One patient each had a long stricture (8cm) or a filiform stenosis ruling out dilatation [technical success, 25/27 (92.6%)]. Among these 25 patients, 39 colonoscopies with 51 dilatations were performed. After a single dilatation, 52% were asymptomatic while 48% needed another intervention, half of them surgery. Bleeding without need for transfusion occurred in 3 out of 39 colonoscopies and one perforation required surgery. Significant prognostic factors were smoking and ulcers in the stricture (P < 0.05 each). Some ulcers led to intussusception requiring surgery in spite of good dilatation results.ConclusionThrough the endoscope balloon stricture dilatation is a relatively safe and often effective treatment modality in ileocolonic strictures. The presence of ulcers in the stricture have a worse outcome as do smokers.

High rates of complications and substantial mortality in both types of refractory sprue.

Introduction Refractory sprue (RS) is a rare malabsorption syndrome defined by persisting small bowel villous atrophy despite a strict gluten-free diet. The clinical picture and long-term outcome of RS is highly variable and is not well described. Aim To define underlying and accompanying diseases and clinical outcome in consecutive patients with RS. Patients and methods Clinical and histological data from patients with RS at our department were analyzed retrospectively. RS was defined as villous atrophy and malabsorption despite a strict gluten-free diet persisting without improvement for more than 6 months or requiring earlier therapeutic intervention. Results Thirty-two patients with RS were identified (23 RS type I, nine RS type II). Follow-up period was 55 (12–372) months. Two patients progressed from RS type I into type II. Thrombembolic events occurred in nine cases, and additional autoimmune diseases were found in 17 patients. Overt intestinal T-cell lymphoma developed in four patients with RS type II. Three patients with RS type II died during the observation period owing to intestinal T-cell lymphoma and four with RS type I owing to infectious complications. Five-year cumulative survival was 90% (95% confidence interval 76–100) in patients with RS type I and higher than in patients with RS type II (53%, 12–94%; P<0.05). Conclusion RS comprises a very heterogenous group of patients with long-term survival seen even in single patients with RS type II. Overall, survival is shorter in RS type II in comparison with RS type I. Patients with RS type I, however, show similar rates of disease-related complications as well as substantial mortality.

Increased immunoglobulin G production by short term cultured duodenal biopsy samples from HIV infected patients

Background—Secretory immunity is a major defence mechanism against infections at mucosal surfaces which are common in HIV infected patients. Aims—To analyse intestinal immunoglobulin production in HIV infection in comparison with that in saliva and serum. Patients and methods—Immunoglobulin G (IgG), A (IgA), and M (IgM) concentrations were determined in supernatants of short term cultured duodenal biopsy samples, serum, and saliva from HIV infected patients (n = 28) and controls (n = 14) by radial immunodiffusion. Results—IgG was increased in the supernatants of short term cultured biopsy samples and saliva from HIV infected patients compared with controls (p<0.01), but IgA and IgM levels were normal. In contrast, both IgG and IgA concentrations in serum were higher in HIV infected patients than in controls (p<0.002). No correlation was found between IgA produced by duodenal biopsy specimens and serum IgA. Conclusion—Abnormalities in mucosal immunoglobulin production in HIV infection were suprisingly small, indicating that specific secretory immunity rather than quantitative immunoglobulin production may be impaired. However, increased production of IgG could contribute to mucosal inflammation by complement activation. Our findings of normal mucosal IgA production and the lack of correlation between serum and mucosal IgA argues against an intestinal origin for the increased serum IgA levels in HIV infected patients.

Diagnostic value of endoscopy for the diagnosis of giardiasis and other intestinal diseases in patients with persistent diarrhea from tropical or subtropical areas.

Objective. Upper endoscopy has been suggested as a valuable tool in the diagnosis of giardiasis. The aim of this study was to compare two methods based on endoscopy, i.e. microscopy of duodenal fluid and histology, with a fluorescent-antibody assay for the detection of Giardia lamblia cysts in stool specimens. The role of endoscopy in the identification of other causes of chronic diarrhea acquired during travel abroad was also evaluated. Material and methods. Thirty-one patients (9 F, 22 M, median age 39 years, range 19–63 years) with persistent diarrhea after returning from tropical or subtropical areas agreed to undergo upper gastrointestinal endoscopy before and after treatment. Lower gastrointestinal endoscopy was subsequently performed. Three stool samples from each patient were examined using the direct fluorescent-antibody assay (DFA) for the detection of G. lamblia, and by routine methods for other protozoal and bacterial enteric pathogens. Each patient underwent upper endoscopy and biopsies and duodenal fluid samples were taken. In 12 patients a further lower endoscopy was performed. Results. In 16 patients G. lamblia was detected in stool samples by DFA (relative sensitivity: 100%). Histology of duodenal biopsies and microscopy of duodenal fluids allowed diagnosis of giardiasis to be made in only 8, and 3 patients, respectively (relative sensitivities: 21% and 44%). Besides giardiasis, upper endoscopic examination revealed an alternative diagnosis (tropical sprue), whereas six additional diagnoses were made by colonoscopy. In six patients the cause of chronic diarrhea remained unclear. Conclusions. Compared to stool examinations using DFA, upper endoscopy is less sensitive for the diagnosis of giardiasis. In patients with negative stool examinations, lower endoscopy yields relevant diagnoses more often than upper endoscopy.

Abnormal predominance of IgG in HIV-specific antibodies produced by short-term cultured duodenal biopsy specimens from HIV-infected patients

The aim of our study was to analyze HIV-specific humoral immunity in the intestinal mucosa at different stages of HIV infection in comparison with serum and saliva. Duodenal biopsy specimens from 30 AIDS patients and 9 HIV-infected patients without AIDS were cultured for 48 hours. Culture supernatants, as well as simultaneously obtained serum and saliva samples, were adjusted to the same immunoglobulin concentrations and tested for HIV-specific IgG and IgA by Western blot. The HIV antigen pattern differed clearly between IgA and IgG but was similar for each isotype independent of its origin (i.e., serum, saliva, or biopsy specimen supernatants). Short-term cultured duodenal biopsy specimens from HIV-infected patients at all stages produced predominantly IgG, which was broadly reactive with HIV antigens. Lower titers of HIV-specific IgA, which recognized few antigens, were found, mostly the glycoprotein gp160. At later stages of the disease compared with earlier stages, the reaction pattern of mucosal IgA from saliva and biopsy supernatants was even more restricted; secretory component was frequently absent. The abnormal predominance of HIV-specific IgG over IgA in mucosal secretions may result from abnormal antibody production in the mucosa rather than from serum leakage. Mucosal inflammation induced by HIV-IgG immune complexes and insufficient immune exclusion by secretory IgA may not only lead to increased mucosal HIV replication but may also contribute to gastrointestinal disease in HIV-infected patients.

EndoClot Polysaccharide Hemostatic System in Nonvariceal Gastrointestinal Bleeding: Results of a Prospective Multicenter Observational Pilot Study.

Background and Study Aims: Hemostatic powders have been introduced to improve the management of gastrointestinal (GI) bleeding and to extend the variety of tools available for emergency endoscopy. The aim of the present pilot study was to evaluate the indication profiles and the short-term outcome of EndoClot. Patients, Materials and Methods: In a prospective observational pilot study patients with acute nonvariceal GI bleeding were included. Primary or secondary application of EndoClot was assessed. Hemoglobin, prothrombine time and platelets were documented before and after hemostasis. The efficacy of EndoClot was assessed 72 hours and 1 week after application. Results: Seventy patients with acute GI bleeding were recruited into the study. Eighty-three percent (58/70) of the patients had upper and 17% (12/70) had lower GI bleeding. In the upper GI tract treatment success was achieved in 64% (30/47, 95% confidence interval, 50%-76%) after primary use and in all patients, when used after established techniques had failed (95% confidence interval, 70%-100%). In lower GI bleeding hemostasis was achieved in 83% of cases (10/12, 95% confidence interval 54%-97%). Rebleeding occurred in 11% (8/70), in 10% EndoClot served as a bridge to surgery (7/70). Conclusions: EndoClot expanded the therapeutic options in the management of GI bleeding. It was applicable as a monotherapy or in combination with other techniques from oozing bleeding type or lower. It was most effective in diffuse or extensive bleeding activity or when access to the bleeding vessel was difficult. EndoClot can be applied as a bridge to surgery when classical methods of hemostasis have failed.

Esophageal giant ulcer in primary human immunodeficiency virus infection is associated with an infiltration of activated T cells

Primary human immunodeficiency virus (HIV) infection is a rarely diagnosed disease. The intestinal lymphocyte population represents a primary target of infection, virus replication, as well as cell infiltration and activation. The purpose of this study was to describe a patient suffering from esophageal giant ulcer as a clinical manifestation of primary HIV. In the present case of primary HIV infection a giant ulcer of the esophagus was diagnosed as the clinical manifestation. An upper endoscopy was performed and the biopsy specimens were further processed for immunohistochemical stainings characterizing the cellular infiltrate as well as cytokine production. In addition, seroconversion was documented and total viral load was determined. The esophageal ulceration presented the clinical manifestation of primary HIV infection since other causes of esophageal ulcerations could be excluded. The ulceration revealed an inflammatory infiltrate consisting of both CD4+ and CD8+ T cells. The vast majority of these cells expressed the activation marker CD38 and several cells showed interferon-γ and interleukin-2 production. Furthermore, a substantial number of tissue infiltrating CD8+ T cells expressed the cytotoxic molecule perforin. In addition, the HIV antigen p24 could be detected in the inflammatory infiltrate. Subsequent steroid treatment resulted in a relief of symptoms and healing of the ulcerations. These observations strongly suggest that infiltration of activated T cells plays a crucial role in the pathogenesis of giant ulcers during primary HIV infection.