Pre-existing IgG antibodies cross-reacting with the Fab region of infliximab predict efficacy and safety of infliximab therapy in inflammatory bowel disease.

BACKGROUND: Infliximab (IFX) is a chimeric murine/human anti-TNF antibody (Ab) used for the treatment of Crohn's disease (CD) and ulcerative colitis (UC). Loss of response is common and associated with development of anti-IFX Abs during ongoing therapy. However, human anti-murine immunoglobulin Abs are common and may cross-react with the murine part of IFX. AIM: To investigate if Abs binding to IFX's Fab region (IFX-Fab) are present in IBD patients before exposure to IFX, and whether they predict efficacy and safety of IFX therapy. METHODS: Observational, retrospective cohort study of patients with CD (n = 29) and UC (n = 22). RESULTS: Pre-treatment levels of IFX-Fab reactive IgG Abs were significantly lower in CD patients in remission after 1 year of maintenance IFX (median 91 mU/L, n = 8) than in the rest of the patients (639 mU/L, n = 21; P < 0.01), and lower than in patients with secondary loss of response in particular (692 mU/L, n = 7; P < 0.01). A cut-off concentration of <439 mU IFX-Fab reactive IgG Ab per litre comprised all patients who later obtained long-term sustained remission on IFX (sensitivity 100%, specificity 67%). Similar trends were observed in UC. The pre-treatment levels of IFX-Fab reactive IgG Abs were markedly higher in patients developing infusion reactions to IFX (1037 mU/L, n = 7) than in the remaining patients (349 mU/L, n = 44; P = 0.036). CONCLUSIONS: IFX-Fab reactive IgG antibodies present in serum from IBD patients before infliximab therapy associate with lack of long-term efficacy and safety. Assessments of such antibodies may help clinicians to choose between treatment with infliximab and more humanised agents.

Gram-negative bacteria account for main differences between faecal microbiota from patients with ulcerative colitis and healthy controls.

Detailed knowledge about the composition of the intestinal microbiota may be critical to unravel the pathogenesis of ulcerative colitis (UC), a human chronic inflammatory bowel disease, since the intestinal microbes are expected to influence some of the key mechanisms involved in the inflammatory process of the gut mucosa. The aim of this study was to investigate the faecal microbiota in patients either with UC in remission (n=6) or with active disease (n=6), and in healthy controls (n=6). The composition of Gram-negative bacteria and Gram-positive bacteria was examined. Antigenic structures of Gram-negative bacteria such as lipopolysaccharides have been related to the inflammatory responses and pathogenesis of inflammatory bowel disease. Dice cluster analysis and principal component analysis of faecal microbiota profiles obtained by denaturing gradient gel electrophoresis and quantitative PCR, respectively, revealed that the composition of faecal bacteria from UC patients with active disease differed from the healthy controls and that this difference should be ascribed to Gram-negative bacteria. The analysis did not show any clear grouping of UC patients in remission. Even with the relatively low number of subjects in each group, we were able to detect a statistically significant underrepresentation of Lactobacillus spp. and Akkermansia muciniphila in UC patients with clinically active disease compared to the healthy controls. In line with previous communications, we have shown that the microbiota in UC patients with active disease differ from that in healthy controls. Our findings indicate that alterations in the composition of the Gram-negative bacterial population, as well as reduced numbers of lactobacilli and A. muciniphila may play a role in UC.

Genetic polymorphisms of tumour necrosis factor receptor superfamily 1b and fas ligand are associated with clinical efficacy and/or acute severe infusion reactions to infliximab in Crohn's disease.

BACKGROUND: Single nucleotide polymorphisms (SNPs) in TNF receptor superfamily (TNFRSF) 1A and 1B, and Fas ligand (FASLG) genes, have been associated with responsiveness to infliximab (IFX) in Crohn's disease. AIM: To investigate if SNPs in TNFRSF1A and 1B, and FAS (TNFRSF6) and FASLG (TNFSF6), associated with short- or long-term clinical and biological efficacy and with acute severe infusion reactions. METHODS: Observational, retrospective and explorative cohort study of IFX-treated Caucasian patients with Crohn's disease classified as primary nonresponders (n = 21), response failures on maintenance therapy (n = 37), maintained remission (n = 47) and occurrence of acute severe infusion reactions (n = 20). RESULTS: During IFX maintenance therapy, minor allele carriage of TNFRSF1B, rs976881 is associated with loss of response [OR 3.3 (1.2-9.1), P = 0.014]. Minor allele homozygosity increased the risk substantially (OR estimated 19, P = 0.006), and furthermore associated with a mean CRP increase of 17 mg/L as compared to a mean decrease of 17 mg/L in all others (P = 0.036). In contrast, minor allele carriage of TNFRSF1B, rs1061622 is associated with beneficial response to IFX induction [OR 4.2 (1.2-18.2), P = 0.014], and with persistence of remission during maintenance therapy [OR 5.5 (1.5-25.5), P = 0.007]. Carriage of the minor allele of FASLG, rs76110 increased risk of severe infusion reactions [OR 4.0 (1.1-22.4), P = 0.041]; minor allele carriage of TNFRSF1B, rs652625 decreased the risk (OR estimated 0.2, P = 0.043 ). CONCLUSIONS: The TNFRSF1B polymorphisms may contribute to predict efficacy of infliximab. Moreover, FASLG and TNFRSF1B polymorphisms may confer genetic susceptibility to severe infusion reactions. These findings could potentially aid clinical decisions if confirmed in larger studies.

Severe infusion reactions to infliximab: aetiology, immunogenicity and risk factors in patients with inflammatory bowel disease.

BACKGROUND: Infliximab (IFX) elicits acute severe infusion reactions in about 5% of patients with inflammatory bowel disease (IBD). AIM: To investigate the role of anti-IFX antibodies (Ab) and other risk factors. METHODS: The study included all IBD patients treated with IFX at a Danish university hospital until 2010 either continuously (IFX every 4-12 weeks) or episodically (reinitiation after >12 weeks). Anti-IFX Ab were measured using radioimmunoassay. RESULTS: Twenty-five (8%) of 315 patients experienced acute severe infusion reactions. Univariate analysis showed that patients who reacted were younger at the time of diagnosis (19 vs. 26 years, P=0.013) and at first IFX infusion (28 vs. 35 years, P=0.012). Furthermore, they more often received episodic therapy (72% vs. 31%, P<0.001) and logistic regression revealed this as the only significant predictor of reactions (OR 5 [2-13]; P<0.001). IFX reinitiation after 6 months intermission further increased the risk (OR 8 [3-20], P<0.001). Most reactions (n=14, 88%) occurred at 2nd infusion in the 2nd treatment series (P=0.006). Anti-IFX IgG Ab were highly positive in 19 of 20 patients (95%) shortly after the reactions (median 84 U/mL). Anti-IFX IgG Ab measured prior to the retreatment series were negative in 7 of 11 patients tested (64%). Anti-IFX IgE Ab were negative in all patients with reactions. CONCLUSIONS: Acute severe infusion reactions were strongly associated with development of anti-IFX IgG Ab, but not with anti-IFX IgE Ab. The risk was particularly high at the 2nd infusion in retreatment series. Negative anti-IFX Ab before reinitiation did not rule out reactions.

Spontaneous and cytokine induced expression and activity of matrix metalloproteinases in human colonic epithelium.

Matrix metalloproteinases (MMPs) have been implicated in tissue damage associated with inflammatory bowel disease (IBD).As the role of the intestinal epithelium in this process is unknown, we determined MMP expression and enzyme activity in human colonic epithelial cells (CEC). MMP mRNA expression was assessed by reverse transcription-polymerase chain reaction in HT-29 and DLD-1 cells and in CEC isolated from biopsies from IBD and control patients. Total MMP activity in the cells was measured by a functional assay, based on degradation of a fluorescent synthetic peptide containing the specific bond for MMP cleavage. HT-29 and DLD-1 expressed several MMPs and levels of MMP-3, -10 and -13 mRNA expression were increased significantly by tumour necrosis factor (TNF)-alpha exposure. Transcripts of MMP-1, -3, -7, -9, -10 and -12 were detected in CECs and all, except MMP12, at significantly increased levels in cells from inflamed IBD mucosa. MMP-2 and -8 mRNA were expressed inconsistently and MMP-11, -13 and -14 mRNA undetectable. Proteolytic MMP activity was detected in CEC supernatants and the level was increased significantly in inflamed IBD epithelium. The enzyme activity was inhibited strongly by a specific MMP inhibitor (GM 6001). A significant TNF-alpha-mediated increase in MMP enzyme activity was also detected in HT-29 cells in vitro. In conclusion, the expression of several MMPs as well as the level of functional MMPactivity is increased in CEC from patients with active IBD. The results suggest that MMPs released by the intestinal epithelium may be involved in the pathogenesis of IBD by promoting local mucosal damage.

Expression of Toll-like receptor 9 and response to bacterial CpG oligodeoxynucleotides in human intestinal epithelium.

Recognition of repeat CpG motifs, which are common in bacterial, but not in mammalian, DNA, through Toll-like receptor (TLR)9 is an integral part of the innate immune system. As the role of TLR9 in the human gut is unknown, we determined the spectrum of TLR9 expression in normal and inflamed colon and examined how epithelial cells respond to specific TLR9 ligand stimulation. TLR9 expression was measured in human colonic mucosal biopsies, freshly isolated human colonic epithelial cells and HT-29 cells by reverse transcriptase-polymerase chain reaction or Western blotting. Colonic epithelial cell cultures were stimulated with a synthetic CpG-oligodeoxynucleotide (ODN), exhibiting strong immunostimulatory effects in B cells. Interleukin (IL)-8 secretion was determined by enzyme-linked immunosorbent assay, nuclear factor-kappaB (NF-kB) activity by electrophoretic mobility shift assay and IkB phosphorylation by Western blotting. TLR9 mRNA was equally expressed in colonic mucosa from controls (n = 6) and patients with ulcerative colitis or Crohn's disease disease (n = 13). HT-29 cells expressed TLR9 mRNA and protein and responded to CpG-ODN (P < 0.01), but not to non-CpG-ODN stimulation, by secreting IL-8, apparently in the absence of NF-kB activation. Primary epithelial cells isolated from normal human colon expressed TLR9 mRNA, but were completely unresponsive to CpG-ODN stimulation in vitro. In conclusion, differentiated human colonic epithelial cells are unresponsive to TLR9 ligand stimulation in vitro despite spontaneous TLR9 gene expression. This suggests that the human epithelium is able to avoid inappropriate immune responses to luminal bacterial products through modulation of the TLR9 pathway.

Cyclosporine for induction of remission in Crohn's disease.

BACKGROUND: Cyclosporine was first found to be an effective and well-tolerated immunosuppressive agent in organ transplant recipients, and subsequently in several autoimmune diseases. It was reported in open studies that cyclosporine is effective for induction of remission in Crohn's disease. Four randomized controlled trials have been performed to determine whether the results observed in these open studies were valid. This systematic review summarizes the evidence on the use of oral cyclosporine for the induction of remission in Crohn's disease. OBJECTIVES: To evaluate the effectiveness of oral cyclosporine for induction of remission in patients with active Crohn's disease in the presence and absence of concomitant steroid therapy. Secondary objectives were to evaluate clinical response rates and adverse events associated with cyclosporine. SEARCH STRATEGY: Computer-assisted searches of the on-line bibliographic databases MEDLINE and EMBASE were performed to identify potentially relevant publications between 1980 and July 2004. The MeSH terms "Crohn Disease" or "Inflammatory Bowel disease" and "Cyclosporin" (exploded) were used to perform key word searches of the databases. Manual searches of reference lists from potentially relevant papers were performed in order to identify additional studies that may have been missed. Abstracts from major gastroenterological meetings, The Cochrane Central Register of Controlled Trials and the Cochrane Inflammatory Bowel Disease Group Specialized Trials Register were also searched for relevant studies. Appropriate officials at Sandoz Corporation were contacted to seek information on any unpublished trials. SELECTION CRITERIA: Prospective, randomized, double-blinded, placebo-controlled trials of parallel design with treatment duration of a minimum 12 weeks comparing oral cyclosporine therapy with placebo for treatment of patients with active Crohn's disease were eligible for inclusion. DATA COLLECTION AND ANALYSIS: All data were analyzed on an intention-to-treat basis. Data were extracted from the original research articles and converted into 2x2 tables (cyclosporine vs. placebo). Where available, individual 2x2 tables for strata within studies were also used. Heterogeneity was assessed using the chi-square test (p < 0.10 was regarded as statistically significant). For non-pooled data, p-values were derived using the chi-square test. For pooled data, summary test statistics were derived using the Peto odds ratio and 95% confidence intervals. A fixed effects model was used for pooling of data. For continuous data, summary test statistics were derived using the weighted mean difference and 95% confidence intervals. The definitions of treatment success, remission and clinical improvement were set by the authors of each paper, and the data were combined for analysis only if these definitions were sufficiently similar. MAIN RESULTS: Brynskov 1989a found that patients receiving high dose cyclosporine (median 7.6 mg/kg/day) had statistically significant clinical improvement at 12 weeks compared to placebo patients. None of the other studies found any statistically significant benefit for clinical improvement or induction of remission for low dose cyclosporine treatment (5 mg/kg/day) used by itself or in combination with corticosteroids compared to placebo. Cyclosporine was associated with a significantly higher proportion of adverse events and withdrawals due to adverse events relative to placebo. AUTHORS' CONCLUSIONS: Brynskov 1989a enrolled a small number of patients and the modified clinical grading scale used in the study has not been validated in other studies. Furthermore, statistically significant clinical improvement does not imply induction of clinical remission. Indeed, Brynskov 1989a found no statistically significant differences in the mean Crohn's Disease Activity Index score at 12 weeks indicating that cyclosporine was no more effective than placebo for induction of remission in Crohn's disease. The results of this review demonstrate that low dose (5 mg/kg/day) oral cyclosporine is not effective for the induction of remission in Crohn's disease. Patients treated with low dose oral cyclosporine are more likely than placebo treated patients to experience adverse events including renal dysfunction. The use of low dose oral cyclosporine for the treatment of chronic active Crohn's disease does not appear to be justified. Oral dosing at higher levels or parenteral administration of cyclosporine have not been adequately evaluated in controlled clinical trials. Higher doses of cyclosporine are not likely to be useful for the long-term management of Crohn's disease because of the risk of nephrotoxicity and the availability of other proven interventions.

Expression and localisation of matrix metalloproteinases and their natural inhibitors in fistulae of patients with Crohn's disease.

BACKGROUND: Fistulae are a troublesome complication of Crohn's disease but little is known of the final effector molecules responsible for matrix degradation. Although matrix metalloproteinases (MMPs) have been strongly implicated in tissue injury in Crohn's disease, their role in fistula formation is unknown. AIM: To determine the expression pattern of MMPs and tissue inhibitors of metalloproteinases (TIMPs) in fistulae of patients with Crohn's disease. PATIENTS AND METHODS: Resected fistula specimens were obtained from patients with Crohn's disease (n = 11) and classified according to the predominant histological features-that is, acute versus chronic inflammation. Patients with fistulae due to other diseases (n = 9) and normal colon (n = 5) served as controls. MMP and TIMP protein expression was measured by single or double labelled immunohistochemistry, and mRNA expression by in situ hybridisation. MMP activity was measured by gelatin zymography. RESULTS: Compared with normal colon, strong MMP-3 expression was consistently observed in fistulae in Crohn's disease, irrespective of the stage of inflammatory activity. MMP-3 transcripts and protein were localised in large mononuclear cells and fibroblasts. MMP-9 transcripts and protein were expressed in granulocytes and only in fistulae with acute inflammation. Staining for MMP-1 and MMP-7 was weak and negative for MMP-10, whereas MMP-2 was equally expressed in normal colon and fistulae. TIMP-1, TIMP-2, and TIMP-3 expression was low in all samples. Similar expression patterns were found in fistulae of the disease control group. Fistulae also expressed active MMP-2 and MMP-9, as measured by gelatin zymography. CONCLUSION: MMP-3 and MMP-9 are markedly upregulated in intestinal fistulae and may contribute to fistula formation through degradation of the extracellular matrix, irrespective of the underlying disease process.

Screening for dysplasia and TP53 mutations in closed rectal stumps of patients with ulcerative colitis or Crohn disease.

BACKGROUND: Patients who undergo colectomy due to intractable chronic inflammatory bowel disease (IBD) may keep a closed rectal stump for several years, which may be at increased risk of malignant transformation owing to residual inflammatory activity. We examined a hospital series of patients with ulcerative colitis or Crohn colitis to describe the clinical, endoscopical and histological features of the closed rectal stump and to screen for dysplasia and mutations in the TP53 tumour suppressor gene. METHODS: During rigid proctoscopy, rectal mucosal biopsy specimens and rectal lavage fluid were collected from 42 patients. Biopsy specimens were examined histologically, and genomic DNA extracted from frozen biopsies and lavage fluid was analysed for mutations in TP53 exons 4-9. RESULTS: The median disease duration was 8.5 years (range 1.3-34 years). No endoscopic or histological signs of dysplasia or carcinoma were seen and no mutations in the TP53 gene were detected in any biopsy or lavage fluid specimens. Histological moderate to severe mucosal inflammation was present in 78% (33/42) of the patients, however, and rectal stump involution was noted in 43% (18/42). CONCLUSION: No signs of malignancy or premalignant degeneration were detected in this prospective series of IBD patients with a closed rectal stump. Although this is reassuring for patients, the presence of moderate to severe inflammation in the majority of rectal stumps indicates a role for adjuvant molecular markers to improve colorectal cancer surveillance on this subgroup of IBD patients.

Immunoassays of human trefoil factors 1 and 2: measured on serum from patients with inflammatory bowel disease.

BACKGROUND: The trefoil factors (TFF1-3) are cysteine-rich peptides expressed in the gastrointestinal tract where they play a critical role in mucosal protection and repair. The expression is up-regulated at sites of ulceration in various chronic inflammatory diseases. Recently, we presented an ELISA method for measurement of TFF3. The aims of the present study were to develop and evaluate ELISAs for the other two known human trefoil peptides, TFF1 and TFF2, and to carry out a cross-sectional study on serum TFF levels in patients with inflammatory bowel disease (IBD). METHODS: The TFF1-ELISA was based on two polyclonal rabbit antibodies and the TFF2-ELISA on a monoclonal mouse antibody and a polyclonal rabbit antibody. RhTFF1 and 2 were employed to prepare the calibrators. TFF1-3 were assayed in serum from IBD patients (n=41) and controls (n=13). RESULTS: The TFF1- (TFF2-) ELISA had a detection limit of 3 pmol/L (6 pmol/L) and an analytical imprecision (CV(A)) of 7.0-8.8 for mean concentrations of 24-120 pmol/L (6.1-8.0 for mean concentrations of 17-77 pmol/L). The central reference intervals (n=300) were 140-1400 pmol/L (37-190 pmol/L). There was no variation with age and menstrual cycle. Food intake reduced concentrations of TFF1 by approximately 15%, but did not influence concentrations of TFF2. TFF1 and TFF3 were increased in serum from IBD patients. CONCLUSIONS: We have developed assays for measuring TFF1 and TFF2. Finding increased TFF concentrations in serum from IBD patients suggests that measurements of trefoil peptides may be of clinical relevance in IBD.

Tumour necrosis factor-alpha converting enzyme (TACE) activity in human colonic epithelial cells.

Tumour necrosis factor (TNF)-alpha converting enzyme (TACE) releases biologically active, soluble TNF-alpha from transmembrane pro-TNF-alpha and has attracted interest as a specific therapeutic target in inflammatory bowel disease (IBD). Strong immunoreactivity for TACE protein was demonstrated recently in human colonic epithelium, but the function is unknown. We investigated if human colonic epithelial cells express functional TACE activity and how TACE expression is regulated in response to cytokine stimulation. TACE and TNF-alpha mRNA and protein expression were measured in HT-29 and DLD-1 colonic epithelial cells by reverse-transcription polymerase chain reaction, western blotting or enzyme-linked immunosorbent assay. Monocytic THP-1 cells served as positive control. Functional TACE activity was identified and quantified in detergent extracts of cell lines and freshly isolated colonocytes from 14 IBD patients and five controls by a hydrolysis assay using an oligopeptide spanning the cleavage site in pro-TNF-alpha. HT-29 and DLD-1 cells spontaneously expressed TACE mRNA and the active form of TACE protein at levels similar to those of monocytic cells. Functional TACE activity was demonstrated in all cell lines and in cells of controls or IBD patients irrespective of disease activity. TACE mRNA expression and functional activity remained unchanged in cell lines after stimulation with TNF-alpha despite clear induction of TNF-alpha mRNA expression and release of soluble TNF-alpha protein. The release of soluble TNF-alpha protein was almost completely abolished by CH4474, a synthetic TACE inhibitor. We conclude that functional TACE activity is constitutively expressed in human colonic epithelial cells and responsible for processing of the mature, soluble form of TNF-alpha in response to cytokine stimulation.

Tumour necrosis factor alpha converting enzyme (TACE) activity in the colonic mucosa of patients with inflammatory bowel disease.

BACKGROUND: Anti-tumour necrosis factor alpha (TNF-alpha) antibodies are effective in Crohn's disease and perhaps ulcerative colitis but antigenicity and the high cost have raised interest in other strategies to block TNF-alpha. These include the TNF-alpha converting enzyme (TACE) which releases soluble TNF-alpha from transmembrane pro-TNF-alpha. AIM: To investigate whether TACE activity is present in human colonic mucosa. MATERIALS AND METHODS: Detergent extracts of cell membranes from colonic biopsies were obtained from 12 controls and 28 patients with inflammatory bowel disease. Enzyme activity was measured by hydrolysis assays using pro-TNF-alpha or oligopeptide substrates spanning the known pro-TNF-alpha cleavage site at Ala(76)-Val(77). Cleavage products were identified by western blotting, high pressure liquid chromatography, or mass spectrometry. TACE protein was localised by immunohistochemistry and identified by western blotting of detergent extracts from purified lamina propria mononuclear cells (LPMNC) or epithelial cells. RESULTS: Detergent extracts released TNF-alpha from pro-TNF-alpha and cleaved a model oligopeptide as predicted. Substrate hydrolysis was sensitive to known TACE/matrix metalloproteinase (MMP) inhibitors, but not trocade which has low activity against TACE. The median TACE level was increased in active ulcerative colitis (147 arbitrary units (AU)/mg; p<0.01) but not in Crohn's disease (81 AU/mg) compared with controls (79 AU/mg). Both the full length proform and the active form of TACE protein were expressed in LPMNC cells and epithelial cells. CONCLUSIONS: Functional TACE activity is ubiquitously expressed in the human colon and increased in ulcerative colitis, raising interest in MMP inhibitors targeting TACE.

Phenol toxicity and conjugation in human colonic epithelial cells.

BACKGROUND: Colonic epithelial cells are exposed to a range of potentially harmful luminal factors. including phenols, but it is unresolved whether these compounds impair the integrity of the epithelium. The aim of this study was to describe the effect of phenol exposure on human colonic epithelial cells in vitro and the conjugation pathways involved in detoxification. METHODS: Primary human colonic epithelial cell cultures or HT-29 cell cultures were exposed to paracetamol, dinitrophenol or phenol (0.1-5 mM) for 24 h. Cell viability was measured using the methyltetrazoleum test. Phenol conjugation products released from cell cultures were identified by high-pressure liquid chromatography. Phenol glucuronidase (PGD) and sulphotransferase (PST) enzyme activities were measured in isolated cell homogenates. RESULTS: Paracetamol, dinitrophenol and phenol (>1.25 mM) significantly impaired the viability of primary colonic epithelial cell cultures. No differences between cell cultures from ulcerative colitis and control patients were observed. Paracetamol (5 mM) also induced significant cell damage in HT-29 cells. Glucuronidation was the preferred conjugation pathway in both cell models, despite the presence of PGD and PST activity. CONCLUSION: Phenols have a direct toxic effect on human colonic epithelial cells in vitro, which supports the view that dietary fermentation metabolites may be involved in the modulation of chronic bowel inflammation.

A simple method to establish short-term cultures of normal human colonic epithelial cells from endoscopic biopsy specimens. Comparison of isolation methods, assessment of viability and metabolic activity.

BACKGROUND: Abnormalities in colonic epithelial cell function have been implicated in the pathogenesis of various intestinal disorders, especially inflammatory bowel disease (IBD). The mechanisms, however, remain obscure owing to the lack of representative human colonic epithelial cell models. The aim of this study was to develop and validate a method for establishment of short-term culture of normal human colonic epithelial cells from endoscopic biopsies. METHODS: Epithelial cells were isolated from colonoscopic biopsies by means of ethylenediaminetetraacetic acid/ethylene glycol tetraacetic acid (EDTA/EGTA) (10 or 60 min) or by enzyme treatment and cultured in collagen-coated wells. Viability was measured with a methyltetrazoleum conversion assay, confocal laser, and electron microscopy. Metabolic function was measured by means of butyrate oxidation, 14C-leucine and 3H-glucosamine incorporation; DNA synthesis by means of 3H-thymidine incorporation, and apoptosis with an enzyme-linked immunosorbent assay (ELISA) for histone-associated DNA fragments. Cell types were identified by immunocytochemistry. RESULTS: Ten minutes of EDTA/EGTA treatment released intact crypts and was superior to both the 60-min treatment and enzymatic treatment in terms of viability and nonepithelial cell contamination, respectively. Despite activation of detachment-induced apoptosis, a median 51% of the isolated cells was viable after 24 h of culture and metabolically active as judged by 3H-thymidine, 14C-leucine, and 3H-glucosamine incorporation. Butyrate oxidation followed more complex kinetics (substrate activation) than observed previously in other models. The apparent Km values (medians) were 0.7 mM and 4.5 mM in low and high concentration ranges, respectively. CONCLUSION: We report a simple method to establish culture of human colonic epithelial cells from endoscopically obtained biopsy specimens, producing sufficient viable cells to perform metabolic studies pertinent to the pathogenesis of IBD and related human disorders.

Cytokine-induced impairment of short-chain fatty acid oxidation and viability in human colonic epithelial cells.

Pro-inflammatory cytokines may directly influence the viability and metabolic function of colonic epithelial cells (CEC) as an early event in the development of inflammatory bowel disease. We report here that TNF-alpha+IFN-gamma induced a synergistic, concentration-dependent decline in butyrate oxidation, an essential energy supply, in HT-29 and DLD-1 cells. TNF-alpha+IFN-gamma induced a parallel profound decline in cell viability in HT-29 cells, but not in DLD-1 cells, where impairment of butyrate oxidation seemed to precede later occurrence of cell damage. TNF-alpha+INF-gamma induced CEC damage was independent on NO formation and involved the IFN-gamma signalling pathway as well as induction of apoptosis. If cytokines have similar effects in vivo, these may lead to energy deficiency and thus contribute to CEC damage and disturbance of the epithelial integrity.

A simple classification of Crohn's disease: report of the Working Party for the World Congresses of Gastroenterology, Vienna 1998.

Crohn's disease is a heterogeneous entity. Previous attempts of classification have been based primarily on anatomic location and behavior of disease. However, no uniform definition of patient subgroups has yet achieved broad acceptance. The aim of this international Working Party was to develop a simple classification of Crohn's disease based on objective variables. Eight outcome-related variables relevant to Crohn's disease were identified and stepwise evaluated in 413 consecutive cases, a database survey, and by clinical considerations. Allocation of variables was conducted with well-defined Crohn's disease populations from Europe and North America. Cross-table analyses were performed by chi-square testing. Three variables were finally elected: Age at Diagnosis [below 40 years (A1), equal to or above 40 years (A2)], Location [terminal ileum (L1), colon (L2), ileocolon (L3), upper gastrointestinal (L4)], and Behavior [nonstricturing nonpenetrating (B1), stricturing (B2), penetrating (B3)]. The allocation of patients to these 24 subgroups proved feasible and resulted in specific disease clusters. Cross-table analyses revealed associations between Age at Diagnosis and Location, and between Behavior and Location (all p < 0.001). The Vienna classification of Crohn's disease provides distinct definitions to categorize Crohn's patients into 24 subgroups. Operational guidelines should be used for the characterization of patients in clinical trials as well as for correlation of particular phenotypes with putative biologic markers or environmental factors.