TNFα promotes mucosal wound repair through enhanced platelet activating factor receptor signaling in the epithelium

Pathobiology of several chronic inflammatory disorders, including ulcerative colitis and Crohn's disease is related to intermittent, spontaneous injury/ulceration of mucosal surfaces. Disease morbidity has been associated with pathologic release of the pro-inflammatory cytokine tumor necrosis factor alpha (TNFα). In this report, we show that TNFα promotes intestinal mucosal repair through upregulation of the GPCR platelet activating factor receptor (PAFR) in the intestinal epithelium. Platelet activating factor (PAF) was increased in healing mucosal wounds and its engagement with epithelial PAFR leads to activation of epidermal growth factor receptor, Src and Rac1 signaling to promote wound closure. Consistent with these findings, delayed colonic mucosal repair was observed after administration of a neutralizing TNFα antibody and in mice lacking PAFR. These findings suggest that in the injured mucosa, the pro-inflammatory milieu containing TNFα and PAF sets the stage for reparative events mediated by PAFR signaling.

Laparoscopic splenectomy for medically refractory immune thrombocytopenia (ITP): a retrospective cohort study on longtime response predicting factors based on consensus criteria

BACKGROUND

Laparoscopic splenectomy has been proposed to be the standard therapy for adult patients with medically refractory immune thrombocytopenia (ITP). However, due to inconsistent definitions of response, variable rates of long term response have been reported. Furthermore, new medical treatment options are currently challenging the role of splenectomy. The aims of this study were to (1) analyze long term response after splenectomy according to recently defined consensus criteria, (2) identify possible predictive response factors.

METHODS

A case series of 72 consecutive patients with ITP undergoing laparoscopic splenectomy was retrospectively studied using univariate and multivariate analysis as well as logrank tests.

RESULTS

Median follow-up was 32 (2-110) months. Mortality was 0% and morbidity was 8.2%. Response to splenectomy was achieved in of 63/72 patients (87.5%). Loss of response occurred in 19/63 (30.2%) in median after 3 (range 2-42) months. Preoperative platelet counts after boosting with steroids and immunoglobulins as well as the postoperative rise in platelet counts were statistically significant factors for response upon both univariate and multivariate analysis, whereas age, gender, body mass index, ASA classification, disease duration, accessory spleens, splenic weight, conversion to open surgery, or perioperative complications were not. Patients with a postoperative rise in platelet counts >150,000/μL had a significant better chance on stable long term response than those with a smaller increment (P < 0.001).

CONCLUSIONS

Laparoscopic splenectomy is an effective and safe treatment option in order to obtain stable long term response in patients with ITP. Perioperative platelet counts are predictive factors of long term response.

MiRNAs and their association with locoregional staging and survival following surgery for esophageal carcinoma

BACKGROUND

Prognostic and staging information for esophageal cancer impacts clinical decision making. miRNAs, a newly discovered class of biomarkers and their expression might add additional information relevant to this. In this study we evaluated the expression of selected miRNAs and their relationship to tumor stage and survival in patients with locally advanced tumors following esophagectomy.

MATERIALS AND METHODS

A total of 43 individuals undergoing esophagectomy (without neoadjuvant therapy) for locally advanced but not metastatic (pT2/3; pN0/1) disease (22 adenocarcinoma [EAC], 21 squamous cell carcinoma [SCC]) were included in this study. Perioperative clinical and survival data were collected and managed on a database. The expression of miR-21, miR-106a, miR-148a, miR-205 in formalin-fixed paraffin-embedded specimens was evaluated by TaqMan qPCR assays. Expression was compared with clinicopathological features of the cancers and outcome.

RESULTS

In EAC, miR-148a expression levels were inversely associated with cancer differentiation. miR-21 expression levels were higher in SCC if distant lymph node metastases were present. miR-148a levels were lower when EAC was more proximally located, and miR-21 levels were lower when SCC was more proximal. miR-106a and miR-148a were lower in patients with SCC who developed recurrent disease or had a tumor-related death.

CONCLUSIONS

In patients with locally advanced esophageal squamous cell carcinoma, but not adenocarcinoma, alterations in the expression of miR-21 correlate with tumor location and lymph node status. Furthermore, miR-106a and miR-148a expression correlates with disease recurrence and tumor-related mortality. miRNA markers might inform the initial assessment of these patients, and predict those at higher risk of postsurgical recurrence.

Insulin-like growth factor 1-coated sutures improve anastomotic healing in an experimental model of colitis

BACKGROUND

: Exogenously applied insulin-like growth factor (rhIGF-1) may improve normal intestinal healing. This study examined the effect of rhIGF-1-coated sutures on anastomotic healing in experimental colitis.

METHODS

: Acute colitis was induced in rats by dextran sodium sulphate (DSS). Inflammation was assessed by clinical Disease Activity Index (DAI), myeloperoxidase (MPO) measurement and histological examination. A distal colonic anastomosis was performed using sutures coated with rhIGF-1 dissolved in poly(D,L-lactide) (PDLLA) under general anaesthetic. Anastomotic healing was evaluated histologically, and by hydroxyproline measurement and bursting parameters after 1, 3 and 7 days, and compared with healthy, DSS and DSS + PDLLA controls.

RESULTS

: DAI, MPO and histological inflammation scores were significantly increased in all animals treated with DSS. Bursting occurred less often within the anastomotic line on day 3 in the IGF group than in DSS controls (three versus eight of ten). On day 7, the IGF group had significantly increased histological healing scores (mean(s.e.m.) 12.5(0.7) versus 9.2(0.8) (P < 0.050)) and hydroxyproline content (4.6(0.3) versus 3.6(0.1) mg/g tissue; P < 0.050) compared with DSS controls.

CONCLUSION

: IGF-1-coated sutures improve important aspects of anastomotic healing in rats with experimental colitis.

Effect of probiotics on intestinal barrier function

Impairment of the intestinal barrier is a key event in various gastrointestinal diseases, including inflammatory bowel diseases, celiac disease, gastrointestinal infections, diarrhea, and critical illness. Recent studies demonstrated that probiotic bacteria have beneficial effects in these diseases by effectively improving intestinal barrier function. This article reviews available data on the effect of probiotics on intestinal barrier function in vitro, in animal models, and in clinical studies.

Probiotic mixture VSL#3 protects the epithelial barrier by maintaining tight junction protein expression and preventing apoptosis in a murine model of colitis

Changes in epithelial tight junction protein expression and apoptosis increase epithelial permeability in inflammatory bowel diseases. The effect of the probiotic mixture VSL#3 on the epithelial barrier was studied in dextran sodium sulfate (DSS)-induced colitis in mice. Acute colitis was induced in BALB/c mice (3.5% DSS for 7 days). Mice were treated with either 15 mg VSL#3 or placebo via gastric tube once daily during induction of colitis. Inflammation was assessed by clinical and histological scores. Colonic permeability to Evans blue was measured in vivo. Tight junction protein expression and epithelial apoptotic ratio were studied by immunofluorescence and Western blot. VSL#3 treatment reduced inflammation (histological colitis scores: healthy control 0.94 +/- 0.28, DSS + placebo 14.64 +/- 2.55, DSS + VSL#3 8.43 +/- 1.82; P = 0.011). A pronounced increase in epithelial permeability in acute colitis was completely prevented by VSL#3 therapy [healthy control 0.4 +/- 0.07 (extinction/g), DSS + placebo 5.75 +/- 1.67, DSS + VSL#3 0.26 +/- 0.08; P = 0.003]. In acute colitis, decreased expression and redistribution of the tight junction proteins occludin, zonula occludens-1, and claudin-1, -3, -4, and -5 were observed, whereas VSL#3 therapy prevented these changes. VSL#3 completely prevented the increase of epithelial apoptotic ratio in acute colitis [healthy control 1.58 +/- 0.01 (apoptotic cells/1,000 epithelial cells), DSS + placebo 13.33 +/- 1.29, DSS + VSL#3 1.72 +/- 0.1; P = 0.012]. Probiotic therapy protects the epithelial barrier in acute colitis by preventing 1) decreased tight junction protein expression and 2) increased apoptotic ratio.

Expression of tight and adherens junction proteins in ulcerative colitis associated colorectal carcinoma: upregulation of claudin-1, claudin-3, claudin-4, and beta-catenin

BACKGROUND

Tight junction (TJ) proteins play a critical role in cellular adhesion, glandular differentiation, and cellular proliferation. The function of these proteins is compromised in a number of intestinal diseases, including ulcerative colitis that has an increased incidence for colorectal carcinoma (CAC). The aim of this study was to determine the expression of TJ proteins, claudin-1-4, occludin, ZO-1, and the adherens junction (AJ) protein beta-catenin in CAC.

METHODS

Sixteen colectomy specimens with CAC, adjoining intraepithelial neoplasia, and normal mucosa were studied by immunofluorescence. A semiquantitative evaluation of all investigated proteins was performed by scoring the staining intensity, and the TJ and AJ protein expression in neoplastic cells was compared to normal and intraepithelial neoplastic colonic mucosa.

RESULTS

Using an intensity scoring system, mucosa of crypts and surfaces of CAC exhibited significantly elevated expression levels of claudin-1, claudin-3, claudin-4, and beta-catenin compared to intraepithelial neoplasia and normal mucosa (p<0.05). These data were confirmed by a comparative score. The expression of claudin-2, occludin, and ZO-1 showed no differences between the groups.

CONCLUSION

TJ proteins claudin-1, claudin-3, claudin-4, and the AJ protein beta-catenin are overexpressed in CAC. This suggests that these proteins may become potential markers and targets in CAC.

Treatment of thoracic esophageal anastomotic leaks and esophageal perforations with endoluminal stents: efficacy and current limitations

BACKGROUND

Intra-thoracic esophageal leakage after esophageal resection or esophageal perforation is a life-threatening event. The objective of this non-randomized observational study was to evaluate the effects of endoluminal stent treatment in patients with esophageal anastomotic leakages or perforations in a single tertiary care center.

METHODS

Thirty-two consecutive patients with an intrathoracic esophageal leak, caused by esophagectomy (n = 19), transhiatal gastrectomy (n = 3), laparoscopic fundoplication (n = 2), and iatrogenic or spontaneous perforation (n = 8), undergoing endoscopic stent treatment were evaluated. Hospital stay, mortality and morbidity, sealing rate, extraction rates, complications, and long-term effects were measured.

RESULTS

Median time interval between diagnosis and stent treatment was 3 and 5 days, respectively. Eighteen patients had futile surgical closure of the defect before stenting, while in 14 patients, stent placement was the primary treatment for leakage. Stent placement was technically correct in all patients. Functional sealing was achieved in 78%. Mortality was 15.6%. Stent extraction rate was 70%. Overall method-related complications occurred in nine patients (28%).

CONCLUSIONS

Implantation of self-expanding stents after esophageal resection or perforation is a feasible and safe procedure with an acceptable morbidity even if used as last-choice treatment.

Double balloon enteroscopy: a useful tool for diagnostic and therapeutic procedures in the pancreaticobiliary system

OBJECTIVES

Diagnostic and therapeutic interventions in the biliary and pancreatic system in the previously operated patient by conventional endoscopic retrograde cholangiopancreaticography (ERCP) are difficult and, depending on the surgical procedure, in many cases unsuccessful. We describe our experience of ERCP performed with a double balloon enteroscope (DBE) as an alternative examination technique for these patients.

METHODS

In a retrospective analysis of all DBE procedures at our department between November 2004 and June 2007, 11 patients were identified with various anatomic variations in whom ERCP was performed using a DBE.

RESULTS

In 72% of the patients, previous conventional ERCP examinations failed (8/11). In these patients, DBE-ERCP was successful in 63%. The overall success rate of DBE-ERCP in all patients was 64% (7/11 patients). In those patients, interventions such as papillotomy, calculus extractions, as well as stent placement could be performed even though tools for DBE-ERCP are still very limited. Despite most of the DBE-ERCPs having included therapeutic interventions, no major complications occurred in our case series and minor side effects were restricted to meteorism and mild to moderate abdominal pain.

CONCLUSIONS

DBE-ERCP is an alternative method for diagnostic as well as therapeutic interventions in the biliary as well pancreatic system in the operated patient. However, it should be limited to selected patients, e.g., with contraindications for PTC, as it is a time-consuming as well as a cost-intensive procedure.

Endoscopic ultrasound with conventional probe and miniprobe in preoperative staging of esophageal cancer

BACKGROUND

Using an endoscopic ultrasound (EUS) miniprobe, even highly stenotic esophageal cancers precluding the passage of a conventional probe can be examined without prior dilatation.

OBJECTIVE

To assess: (1) staging accuracy of conventional EUS probe and miniprobe, (2) variables influencing staging accuracy, (3) endoscopic features predicting tumor stage.

METHODS

Ninety-seven consecutive patients with esophageal cancer undergoing complete surgical resection were included. Preoperative EUS was performed using a conventional probe in nonstenotic tumors and a miniprobe in stenotic tumors. Accuracy of EUS for T and N stages was compared to pathohistological staging.

RESULTS

Overall EUS staging accuracy was 73.2% for T stage and 74.2% for N stage. It was similar for the miniprobe used in stenotic tumors vs the conventional probe used in nonstenotic tumors. Based on EUS, 84.5% of the patients would have been assigned to the appropriate therapy protocol (primary surgery vs neoadjuvant therapy). Endoscopic tumor features had no influence on staging accuracy. Tumor length >5 cm predicted advanced T and nodal positive stages.

CONCLUSIONS

The miniprobe allows adequate EUS staging of stenotic esophageal tumors precluding the passage of a conventional probe. Therefore, dilatation therapy of stenotic cancers to conduct conventional EUS should be avoided.

PECAM-1 (CD 31) mediates transendothelial leukocyte migration in experimental colitis

Transendothelial migration of circulating leukocytes into the colonic wall is a key step in the development of the inflammatory infiltrate in inflammatory bowel disease (IBD). The platelet-endothelial cell adhesion molecule-1 PECAM-1 (CD31) is expressed in the tight junction area of endothelial cells, where it is supposed to support the transmigration process. The aim of this study was to determine the role of PECAM-1 in experimental IBD and to show whether blockade of PECAM-1 has therapeutic effects. Chronic colitis was induced in female BALB/c mice by cyclic oral administration of dextran sodium sulfate (DSS) 3% (wt/vol). Expression of PECAM-1 was visualized by immunohistochemistry. In the treatment group animals received 1 mg/kg anti-PECAM-1 (2H8) ip daily starting on day 26. On day 30 leukocyte adhesion and migration was measured during N(2)O-isoflurane anesthesia in the distal colon by intravital microscopy. Disease activity index (DAI), histology, and MPO levels were compared with healthy and diseased controls. PECAM-1 was expressed in colitic mice. Chronic DSS colitis was characterized by a marked increase in rolling, adherent, and transmigrated leukocytes compared with healthy controls. Immunoblockade of PECAM-1 reduced leukocyte transmigration significantly and also diminished leukocyte rolling and sticking in an indirect manner. It also resulted in a significantly diminished DAI and MPO levels, as well as an amelioration of the histological inflammation score. PECAM-1 plays an important role in transendothelial leukocyte migration in DSS colitis. PECAM-1 could be a novel target for antibody-based treatment in IBD.

Intestinal cancer in patients with Crohn's disease

BACKGROUND

Surveillance of intestinal cancer in Crohn's disease (CD) has often been advocated. To date, no clear evidence exists whether CD patients are at special risk for intestinal cancer. An increased incidence of small bowel adenocarcinoma is suggested. However, recent figures also suggest an increased risk of CD associated colorectal cancer. We report our experience with 10 cases of CD complicated by intestinal adenocarcinoma.

MATERIALS AND METHODS

Our institutional database included 330 patients treated for CD between 1988-2005. Data of patients that developed carcinoma within Crohn's lesions of either small or large bowel were analyzed.

RESULTS

Ten patients were diagnosed with CD complicated by carcinoma. In nine patients, cancer was present in the colorectum and in one, in Crohn's ileitis. Tumors were in conjunction with fistulae in three and developed within strictures in five patients. Mean age at the time of diagnosis of CD was 43 years. Mean duration of CD until diagnosis of cancer was 14 years. Only five patients were diagnosed for cancer preoperatively. Staging revealed advanced tumors in almost all patients. Mean survival after surgery was 29 months (2-149 months).

CONCLUSIONS

Cancer risk in CD and especially in Crohn's colitis may still be underestimated. Delayed diagnosis resulted in a poor prognosis. The value of colonoscopy as surveillance tool is questioned by the fact that in our patients, carcinoma was diagnosed in some patients preoperatively by routine colonoscopy. Therefore, additional markers should be identified to detect CD patients at risk.

Effect of pyloric drainage procedures on gastric passage and bile reflux after esophagectomy with gastric conduit reconstruction

BACKGROUND AND AIMS

Controversy still exists about the need for pyloric drainage procedures (pyloroplasty or pyloromyotomy) after esophagectomy with esophagogastrostomy and vagotomy. Although pyloric drainage may prevent postoperative delayed gastric emptying, it may also promote bile reflux into the oesophagus. We analysed pyloric drainage methods for their potential effect on gastric outlet obstruction and bile reflux in patients undergoing esophagectomy.

MATERIALS AND METHODS

One hundred and ninety-eight patients with esophageal carcinoma were treated by transthoracal esophagectomy with gastric conduit reconstruction either with pyloromyotomy (group II, n = 118), pyloroplasty (group III, n = 34) or without pyloric drainage (group I, n = 46) between January 2000 and December 2004. The postoperative gastrointestinal passage by radiological investigation, anastomotic leakage rate, mortality and incidence of gastroesophageal reflux by endoscopy within the first postoperative year were retrospectively analysed.

RESULTS

Patient demographics and the types of surgical procedures did not differ between the three groups. There was no difference in hospital mortality, anastomotic leakage rate, gastrointestinal passage and postoperative hospital stay between the three groups. However, more patients with pyloric drainage showed bile reflux (I = 0% vs II+III=14.9%, p = 0.069) and reflux esophagitis (I = 10.3% vs II+III = 34.5%, p < 0.05) compared to patients without pyloric drainage. On the multivariate analysis, pyloric drainage and the anastomotic height were independent and were significant risk factors associated with postoperative reflux esophagitis.

CONCLUSION

Pyloric drainage after esophagectomy with gastric conduit reconstruction should be omitted because it does not improve gastric emptying and may favour biliary reflux esophagitis.

Inflammatory bowel disease and the apical junctional complex

A critical function of the intestinal mucosa is to form a barrier that separates luminal contents from the underlying interstitium. This intestinal barrier is primarily regulated by the apical junctional complex (AJC) consisting of tight junctions (TJs) and adherens junctions (AJs) and is compromised in a number of intestinal diseases, including inflammatory bowel disease (IBD). In vitro studies have demonstrated that proinflammatory cytokines, such as interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha), that are increased in the intestinal mucosa of patients with IBD can induce a leaky mucosal barrier. There is a growing evidence that the increased permeability and altered AJC structure observed in IBD are mediated by internalization of junctional proteins. This review summarizes barrier defects observed in IBD and addresses mechanisms by which proinflammatory cytokines, such as IFN-gamma and TNF-alpha, modulate AJC structure and epithelial barrier function.

Regulation of the intestinal epithelial barrier by the apical junctional complex

PURPOSE OF REVIEW

Epithelial intercellular junctions are important components of the epithelial barrier and are compromised in disorders such as Crohn's disease. We will highlight recent progress in understanding the role of an intercellular junction referred to as the apical junctional complex in regulating small intestinal epithelial permeability in health and disease.

RECENT FINDINGS

Recent studies have implicated aberrant regulation of the AJC as an underlying factor contributing to a leaky epithelial barrier in Crohn's patients. Consequences of increased epithelial permeability include exposure of intestinal tissue to luminal antigens/pathogens which in turn influence disease activity. Furthermore, proinflammatory cytokines released into the milieu of the epithelium in patients with Crohn's disease influence apical junctional complex and epithelial barrier function. Such cytokines induce disassembly of the apical junctional complex by promoting differential endocytosis of component proteins. Additionally, apical junctional complex proteins are targeted by pathogens that use the epithelium as a portal of entry to establish disease in the host.

SUMMARY

The epithelial apical junctional complex is important in determining epithelial barrier properties. Recent studies have highlighted contribution of proinflammatory cytokines and endocytosis of apical junctional complex proteins to the epithelial barrier defect. Continued advances in understanding of this field will yield new therapeutic targets for intestinal disorders.

Interferon-gamma induces internalization of epithelial tight junction proteins via a macropinocytosis-like process

Increased epithelial permeability is observed in inflammatory states. However, the mechanism by which inflammatory mediators such as IFN-gamma increase epithelial permeability is unknown. We recently observed that IFN-gamma induces disassembly of tight junctions (TJ); in this study we asked whether such TJ disassembly is mediated by endocytosis of junctional proteins. The role of three major internalization pathways in disruption of TJ in IFN-gamma-treated intestinal epithelial cells was analyzed using selective inhibitors and markers of the pathways. No role for the clathrin- and caveolar-mediated endocytosis in the IFN-gamma-induced internalization of TJ proteins was observed. However, inhibitors of macropinocytosis blocked internalization of TJ proteins and junctional proteins colocalized with macropinocytosis markers, dextran and phosphatidylinositol-3,4,5-trisphosphate. Internalized TJ proteins were identified in early and recycling endosomes but not in late endosomes/lysosomes. These results for the first time suggest that IFN-gamma produces a leaky epithelial barrier by inducing macropinoytosis of TJ proteins.

Mechanism of IFN-gamma-induced endocytosis of tight junction proteins: myosin II-dependent vacuolarization of the apical plasma membrane

Disruption of epithelial barrier by proinflammatory cytokines such as IFN-gamma represents a major pathophysiological consequence of intestinal inflammation. We have previously shown that IFN-gamma increases paracellular permeability in model T84 epithelial cells by inducing endocytosis of tight junction (TJ) proteins occludin, JAM-A, and claudin-1. The present study was designed to dissect mechanisms of IFN-gamma-induced endocytosis of epithelial TJ proteins. IFN-gamma treatment of T84 cells resulted in internalization of TJ proteins into large actin-coated vacuoles that originated from the apical plasma membrane and resembled the vacuolar apical compartment (VAC) previously observed in epithelial cells that lose cell polarity. The IFN-gamma dependent formation of VACs required ATPase activity of a myosin II motor but was not dependent on rapid turnover of F-actin. In addition, activated myosin II was observed to colocalize with VACs after IFN-gamma exposure. Pharmacological analyses revealed that formation of VACs and endocytosis of TJ proteins was mediated by Rho-associated kinase (ROCK) but not myosin light chain kinase (MLCK). Furthermore, IFN-gamma treatment resulted in activation of Rho GTPase and induced expressional up-regulation of ROCK. These results, for the first time, suggest that IFN-gamma induces endocytosis of epithelial TJ proteins via RhoA/ROCK-mediated, myosin II-dependent formation of VACs.

Epithelial cell spreading induced by hepatocyte growth factor influences paxillin protein synthesis and posttranslational modification

Superficial wounds in the gastrointestinal tract rapidly reseal by coordinated epithelial cell migration facilitated by cytokines such as hepatocyte growth factor (HGF)/scatter factor released in the wound vicinity. However, the mechanisms by which HGF promotes physiological and pathophysiologic epithelial migration are incompletely understood. Using in vitro models of polarized T84 and Caco-2 intestinal epithelia, we report that HGF promoted epithelial spreading and RhoA GTPase activation in a time-dependent manner. Inducible expression of enhanced green fluorescent protein-tagged dominant-negative RhoA significantly attenuated HGF-induced spreading. HGF expanded a zone of partially flattened cells behind the wound edge containing basal F-actin fibers aligned in the direction of spreading. Concomitantly, plaques positive for the focal adhesion protein paxillin were enhanced. HGF induced an increase in the translation of paxillin and, to a lesser extent, beta1-integrin. This was independent of cell-matrix adhesion through beta1-integrin. Subcellular fractionation revealed increased cosedimentation of paxillin with plasma membrane-containing fractions following HGF stimulation, without corresponding enhancements in paxillin coassociation with beta1 integrin or actin. Tyrosine phosphorylation of paxillin was reduced by HGF and was sensitive to the Src kinase inhibitor PP2. With these taken together, we propose that HGF upregulates a free cytosolic pool of paxillin that is unaffiliated with either the cytoskeleton or focal cell-matrix contacts. Thus early spreading responses to HGF may partly relate to increased paxillin availability for incorporation into, and turnover within, dynamic cytoskeletal/membrane complexes whose rapid and transient adhesion to the matrix drives migration.

Antigen transport and cytoskeletal characteristics of a distinct enterocyte population in inflammatory bowel diseases

Intestinal antigen uptake is enhanced in inflammatory bowel disease. We analyzed transcellular transport routes of antigens in different compartments of normal enterocytes and atypical intestinal epithelial cells called "rapid antigen uptake into the cytosol enterocytes" (RACE cells). These cells constitute a recently described population of enterocyte-derived cells, which are increased in inflammatory bowel disease. Mucosa of freshly resected specimens were incubated with the antigens ovalbumin or horseradish peroxidase. Ultrastructural labeling patterns of differentiation-dependent proteins, the brush-border enzyme sucrase-isomaltase and the cytoskeleton proteins villin and actin, were determined in enterocytes. Apoptosis was investigated biochemically and ultrastructurally by cleavage of caspase-3. Both antigens were transported to late endosomes and to trans-Golgi vesicles of enterocytes in inflammatory bowel disease and control specimens. Quantitative evaluation revealed a significantly increased transepithelial antigen transport in both compartments of RACE relative to normal enterocytes. Labeling densities for sucrase-isomaltase, villin, and actin were decreased in RACE relative to normal enterocytes. Caspase-3 was not increased in RACE cells relative to controls. RACE cells are characterized by increased antigen transport to late endosomes and the trans-Golgi network, a disassembled cytoskeleton and lower concentrations of proteins that are markers of cell differentiation.

Immunoblockade of PSGL-1 attenuates established experimental murine colitis by reduction of leukocyte rolling

Recruitment of circulating leukocytes into the colonic tissue is a key feature of intestinal inflammation. P-selectin glycoprotein ligand-1 (PSGL-1) and very late antigen-4 (VLA-4) are expressed on leukocytes and play an important role in leukocyte-endothelial cell adhesive interactions. We examined the effects of immunoneutralization of PSGL-1 and VLA-4 on leukocyte recruitment in vivo in the development and treatment of experimental colitis. Chronic colitis was induced in balb/c mice by oral administration of dextran sodium sulfate (DSS). Monoclonal antibodies 2PH1 (anti-PSGL-1) and PS/2 (anti-VLA-4) or the combination of both were injected intravenously, and leukocyte adhesion was observed for 60 min in colonic submucosal venules by intravital microscopy (IVM) under isoflurane/N(2)O anesthesia. In addition, mice with established colitis were treated by daily intraperitoneal injections of 2PH1, PS/2, or the combination of both over 5 days. Disease activity index (DAI), histology, and myeloperoxidase (MPO) levels were compared with sham-treated DSS controls. We found that 2PH1 reduced the number of rolling leukocytes (148.7 +/- 29.8 vs. 36.9 +/- 8.7/0.01 mm(2)/30 s, P < 0.05), whereas leukocyte velocity was increased (24.0 +/- 3.6 vs. 127.8 +/- 11.7 microm/s, P < 0.05). PS/2 reduced leukocyte rolling to a lesser extent. Leukocyte firm adhesion was not influenced by 2PH1 but was strongly reduced by PS/2 (24.1 +/- 2 vs. 4.4 +/- 0.9/0.01 mm(2)/30 s, P < 0.05). Combined application did not cause additional effects on leukocyte adhesion. Treatment of chronic colitis with 2PH1 or PS/2 reduced DAI, mucosal injury, and MPO levels significantly. Combined treatment led to a significantly better reduction of DAI (0.4 +/- 0.1 vs. 2.1 +/- 0.2 points) and histology (9.7 +/- 0.9 vs. 21.4 +/- 4.6 points). In conclusion, PSGL-1 and VLA-4 play an important role for leukocyte recruitment during intestinal inflammation. Therapeutic strategies designed to disrupt interactions mediated by PSGL-1 and/or VLA-4 may prove beneficial in treatment of chronic colitis.

RhoA, Rac1, and Cdc42 exert distinct effects on epithelial barrier via selective structural and biochemical modulation of junctional proteins and F-actin

Epithelial intercellular junctions regulate cell-cell contact and mucosal barrier function. Both tight junctions (TJs) and adherens junctions (AJs) are regulated in part by their affiliation with the F-actin cytoskeleton. The cytoskeleton in turn is influenced by Rho family small GTPases such as RhoA, Rac1, and Cdc42, all of which constitute eukaryotic targets for several pathogenic organisms. With a tetracycline-repressible system to achieve regulated expression in Madin-Darby canine kidney (MDCK) epithelial cells, we used dominant-negative (DN) and constitutively active (CA) forms of RhoA, Rac1, and Cdc42 as tools to evaluate the precise contribution of each GTPase to epithelial structure and barrier function. All mutant GTPases induced time-dependent disruptions in epithelial gate function and distinct morphological alterations in apical and basal F-actin pools. TJ proteins occludin, ZO-1, claudin-1, claudin-2, and junctional adhesion molecule (JAM)-1 were dramatically redistributed in the presence of CA RhoA or CA Cdc42, whereas only claudins-1 and -2 were redistributed in response to CA Rac1. DN Rac1 expression also induced selective redistribution of claudins-1 and -2 in addition to JAM-1, whereas DN Cdc42 influenced only claudin-2 and DN RhoA had no effect. AJ protein localization was unaffected by any mutant GTPase, but DN Rac1 induced a reduction in E-cadherin detergent solubility. All CA GTPases increased the detergent solubility of claudins-1 and -2, but CA RhoA alone reduced claudin-2 and ZO-1 partitioning to detergent-insoluble membrane rafts. We conclude that Rho family GTPases regulate epithelial intercellular junctions via distinct morphological and biochemical mechanisms and that perturbations in barrier function reflect any imbalance in active/resting GTPase levels rather than simply loss or gain of GTPase activity.

Proinflammatory cytokines disrupt epithelial barrier function by apoptosis-independent mechanisms

It is well known that inflammatory conditions of the intestinal mucosa result in compromised barrier function. Inflammation is characterized by an influx into the mucosa of immune cells that influence epithelial function by releasing proinflammatory cytokines such as IFN-gamma and TNF-alpha. Mucosal barrier function is regulated by the epithelial apical junctional complex (AJC) consisting of the tight junction and the adherens junction. Since the AJC regulates barrier function, we analyzed the influence of IFN-gamma and TNF-alpha on its structure/function and determined the contribution of apoptosis to this process using a model intestinal epithelial cell line, T84, and IFN-gamma and TNF-alpha. AJC structure/function was analyzed by confocal microscopy, biochemical analysis, and physiologic measurement of epithelial gate/fence function. Apoptosis was monitored by determining cytokeratin 18 cleavage and caspase-3 activation. IFN-gamma induced time-dependent disruptions in epithelial gate function that were potentiated by coincubation with TNF-alpha. Tight junction fence function was somewhat disrupted. Cytokine treatment was associated with internalization of AJC transmembrane proteins, junction adhesion molecule 1, occludin, and claudin-1/4 with minimal effects on the cytoplasmic plaque protein zonula occludens 1. Detergent solubility profiles of junction adhesion molecule 1 and E-cadherin and their affiliation with "raft-like" membrane microdomains were modified by these cytokines. Inhibition of cytokine-induced apoptosis did not block induced permeability defects; further emphasizing their primary influence on the epithelial AJC structure and barrier function. Our findings for the first time clearly separate the proapoptotic effects of IFN-gamma and TNF-alpha from their abilities to disrupt barrier function.

Preoperative steroid administration: effect on morbidity among patients undergoing intestinal bowel resection for Crohńs disease

Long-term steroid therapy may predispose to increased perioperative morbidity in patients undergoing surgery with bowel anastomoses. The aim of our study was to review our data to determine if the steroid dosage is associated with the incidence of early complications after bowel resection in patients with prolonged steroid therapy for Crohńs disease (CD). Altogether, 397 patients underwent bowel resection with primary intestinal anastomoses for CD between 1982 and 2000 in our institution. The mortality and morbidity rates, anastomotic leakage, wound infections, intraabdominal abscesses, reoperation rate, and length of postoperative hospitalization in patients who were having high-dose (>/= 20 mg of prednisolone per day, n = 73) and low-dose (< 20 mg prednisolone per day, n = 146) steroid therapy for more than 1 month before surgery were compared with those of patients ( n = 177) who were not receiving steroids. Statistical analysis was performed using Fisher's exact test and Student's t-test, with p < 0.05 considered significant. The three groups were similar in terms of gender, duration since first diagnosis, American Society of Anesthesiologists classification, and obesity. Mortality, morbidity, anastomotic leakage, wound infections, intraabdominal abscesses, reoperation rate, and average postoperative stay were not statistically different in patients with high-dose, low-dose, or no steroid therapy. The only factor associated with increased morbidity was a low preoperative hemoglobin level. Our results demonstrate that, in patients who are undergoing bowel resection for CD, even high-dose prolonged preoperative systemic steroid therapy is not associated with increased postoperative complications.

Is colonoscopy alone sufficient to screen for ulcerative colitis-associated colorectal carcinoma?

Patients with ulcerative colitis (UC) are at increased risk for colorectal carcinoma (CAC). Despite the fact that patients at risk are followed closely by colonoscopy to screen for dysplasia, the prevalence of CAC is still unacceptably high. The aim of this study was to evaluate the prevalence of risk factors for CAC, such as dysplasia, and to determine the relevance of colonoscopic surveillance in the group who went on to develop cancer. A series of 24 patients with UC were diagnosed with CAC. The patients' records were analyzed retrospectively for duration of UC, prevalence of preoperative dysplasia, and other cancer risk factors (CRFs) (e.g., pancolitis, primary sclerosing cholangitis, early onset of UC, and backwash ileitis). The mean age of the patients at the time of cancer diagnosis was 43 years with an average UC duration of 15 years (6 patients had had UC less than 8 years). CAC was identified preoperatively by colonoscopy in 15 of 24 patients, with an additional 7 of 15 showing flat dysplasia. Five of nine patients without preoperatively diagnosed CAC had flat dysplasia. Overall, 19 patients had additional CRFs, most of them with at least two more CRFs. Despite a regular colonoscopic follow-up for most patients with UC, flat dysplasia was missed in 12 patients preoperatively. Therefore we suggest that patient information should also always include surgical options in each case where significant cancer risk factors are found.

Intraoperative radiation therapy (IORT) in primary locally advanced and recurrent carcinoma of the rectum at a "non-dedicated" facility

BACKGROUND

Primary locally advanced and recurrent colorectal cancer still present a significant clinical challenge. Local failure rates are high in both situations. Promising results have been reported by combined radiochemotherapy, extensive surgery and intraoperative radiation therapy (IORT). Our aim was to perform IORT at a "non-dedicated" facility to improve the local tumour control rate without increasing the complication rate.

MATERIALS AND METHODS

From February 1997 to April 2001, 19 patients with recurrent and 4 patients with primary locally advanced colorectal cancer underwent surgery and IORT. The histology was adenocarcinoma in all cases. A complete removal of the tumour was possible in 11 patients, while an incomplete resection was achieved in 12 cases. IORT doses ranged from 10-20 Gy and electron energies from 6-14 MeV were used. Fourteen patients had pre- or postoperative external beam radiochemotherapy.

RESULTS

After a median follow-up of 27 months, 18 patients (78%) are alive. Five of these patients have a progressive disease. Five patients (22%) died in progressive disease. The amount of residual cancer remaining after surgery is an important factor regarding treatment outcome. Complications were observed in 8 patients (35%). These complications were severe only in 4 patients (17%). Fifteen patients (65%) have had no complications at all. No perioperative or postoperative deaths were seen.

CONCLUSION

IORT combined with radical surgery, external beam radiotherapy and systemic chemotherapy is feasible at a "non-dedicated" facility without increasing the postoperative complications. A complete resection is the most important factor for a favourable outcome.

The adenosine 2b receptor is recruited to the plasma membrane and associates with E3KARP and Ezrin upon agonist stimulation

We have previously shown that adenosine is formed in the intestinal lumen during active inflammation from neutrophil-derived 5'-AMP. Acting through the adenosine A2b receptor (A2bR), the luminally derived adenosine induces vectorial chloride secretion and a polarized secretion of interleukin-6 to the intestinal lumen. Although some G protein-coupled receptors interact with anchoring or signaling molecules, not much is known in this critical area for the A2bR. We used the model intestinal epithelial cell line, T84, and Caco2-BBE cells stably transfected with GFP-A2b receptor to study the intestinal A2bR. The A2bR is present in both the apical and basolateral membranes of intestinal epithelia. Apical or basolateral stimulation of the A2bR induces recruitment of the receptor to the plasma membrane and caveolar fractions. The A2bR co-immunoprecipitates with E3KARP and ezrin upon agonist stimulation. Ezrin interacts with E3KARP and PKA and the interaction between ezrin and E3KARP is enhanced by agonist stimulation. Our data suggest that the A2bR is recruited to the plasma membrane upon apical or basolateral agonist stimulation and interacts with E3KARP and ezrin. We speculate that such an interaction may not only anchor the A2bR to the plasma membrane but may also function to stabilize the receptor in a signaling complex in the plasma membrane.

Metallothionein: early marker in the carcinogenesis of ulcerative colitis-associated colorectal carcinoma

Metallothioneins (MTs) are zinc-binding proteins whose overexpression may lead to sequestration of zinc ions and consequently to functional inactivation of the p53 tumor suppressor gene. The aim of the study was to investigate the potential role of MTs in the carcinogenesis of ulcerative colitis (UC) as well as possible effects on p53 function. The monoclonal antibodies E9 (anti-MT), DO-7, and 1801 (anti-p53) and the polyclonal antibody CM-1 (anti-p53) were used to stain formalin-fixed, paraffin-embedded colon specimens obtained from 14 patients with UC-associated colorectal carcinoma (CAC), 13 with high-grade dysplasia (HGD), 10 with low-grade dysplasia (LGD), and 30 with UC without dysplasia or carcinoma. Statistical significance (p <0.05) was assessed using Fisher's exact test. Positive MT staining (> 20% of tumor, dysplastic, or epithelial cells) was found in most UC and LGD but in only a small percentage of HGD and CAC (p <0.01 for CAC vs. UC and LGD vs. HGD). Positive p53 immunoreactivity was observed predominantly in HGD and CAC but not in LGD and UC (p <0.01 for CAC vs. UC and HGD vs. LGD). In histologically normal tissue neighboring CAC, significant MT expression was found in six of seven specimens with simultaneous lack of p53 expression. MT overexpression may represent an important early step in the development of CAC independent of p53 expression and should be investigated in the long term as an independent cancer risk factor in UC.

Role of intercellular adhesion molecule 1 in indomethacin-induced ileitis

Adhesion molecules have been implicated in the pathogenesis of inflammatory bowel diseases. We investigated their expression and contribution to leukocyte recruitment in experimental intestinal inflammation. Ileitis was induced in Sprague-Dawley rats by two injections of indomethacin (7.5 mg/kg), given 24 h apart. Endothelial intercellular adhesion molecule-1 (ICAM-1) expression was quantified using the dual radiolabeled monoclonal antibody technique and Mac-1 (CD11b/CD18) expression on leukocytes by flow cytometry. Leukocyte infiltration was monitored by tissue myeloperoxidase (MPO) activity. The first indomethacin injection induced a time- and site-dependent increase of ICAM-1 expression in ileal mucosa and muscularis. The second injection resulted in a reduction of ICAM-1 expression below constitutive levels whereas Mac-1 was upregulated. MPO changes paralleled lesion development over 48 h. ICAM-1 and MPO values were correlated for the first 24 h. Immunoneutralization of either ICAM-1 or Mac-1 attenuated mucosal injury. We conclude that (i) indomethacin-induced ileitis is associated with a temporally disassociated upregulation of ICAM-1 and (ii) despite a reduction in ICAM-1 after 24 h, ICAM-1, in concert with Mac-1, contributes to mucosal injury and leukocyte infiltration elicited by indomethacin.

Changes in intestinal transit time after proctocolectomy assessed by the lactulose breath test

After proctocolectomy with ileal pouch-anal anastomosis (IPAA) patients have increased stool frequency and intermittently use antidiarrheal medication. In addition to other factors, gastrointestinal transit time (MTT) could influence stool frequency. The aim of this study was to investigate how MTT changes after IPAA and to study whether MTT has an influence on daily stool frequency. In a prospective trial MTT was investigated with the lactulose breath test in 12 patients undergoing surgery for chronic ulcerative colitis (CUC) or familial adenomatous polyposis coli (FAPC) at different stages: before proctocolectomy, after IPAA with loop ileostomy, and 3 months and 1 year after ileostomy closure. MTT was also measured in 12 patients with IPAA, 12 patients with subtotal colectomy and ileorectal anastomosis (IRA), and 8 patients with conventional proctocolectomy and Brooke ileostomy (CPC) several years after surgery. Twelve healthy volunteers served as controls. Before IPAA, MTT was prolonged in CUC versus FAPC and controls. After restoration of gut continuity MTT was markedly accelerated. After 1 year MTT was slowed again, though values before proctocolectomy and those in controls were not reached. Several years after surgery MTT was significantly prolonged in IPAA and IRA versus controls. In CPC, MTT could not be determined by lactulose breath test. Stool frequency showed an inverse correlation to MTT in IPAA. In conclusion, this study shows that orocecal and oropouch transit are accelerated in the early postoperative period after (procto)colectomy but prolonged in the long-term course. Adaptation of the small bowel takes longer than 1 year. Impairment of stool frequency may be partly due to this adaptation.