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Cancer surveillance of patients with longstanding ulcerative colitis: a clinical, endoscopical, and histological study.

An eight year endoscopical and histological cancer surveillance programme comprising 71 patients with ulcerative colitis is presented. Forty one patients had total colitis and 30 substantial colitis. Mean duration of the disease was 19.7 years (range 9-46 years). An average of 2.6 colonoscopies per patient in the total colitis group were carried out, and at least two biopsies were taken at 10 locations in the colon. In the total colitis group, seven had either low (four), or high grade dysplasia (two), or Dukes' A cancer (one). In the group with substantial colitis two patients with low grade dysplasia were found. Dysplasia or cancer leading to operation was found above the rectum in four of five operated patients, all having had total colitis for 25 to 44 years. The dysplasia and cancer findings at the colonoscopy preceding surgery corresponded well with the surgical specimens. In three operated patients a sequence of dysplasia development was recorded. With the exception of long duration and dysplasia, nothing in the clinical course distinguished the operated cases. Using this surveillance programme prophylactic colectomy can be limited to patients in a high risk group developing dysplasia. The risk of missing a cancer before it becomes incurable seems to be low.

Adult↗

Surveillance in ulcerative colitis: burdens and benefit.

A review of all patients with ulcerative colitis in one health district between 1975-84 revealed an incidence and prevalence of 7.1 and 84/100,000 population respectively. One hundred and ninety five new patients were diagnosed and 313 patients seen and followed up in the clinic for 1168 patient years. None of these patients died from colitis or a complication. On routine colonoscopy three cases had high grade dysplasia and two asymptomatic carcinomas (Duke's stage A and B). Eighty four patients were known to have ulcerative colitis, but were lost to follow up from the hospital clinic; the total time they were not under hospital surveillance was 315 patient years. At the end of the study these patients were contacted or clinical details obtained from their general practitioners. Five of these patients subsequently presented with symptomatic carcinomas (two Duke's B, one Duke's C and two with metastases); three of these five patients have died from their tumours. Of 48 patients thought to have only mild colitis on initial investigation 21 (43%) had substantial colitis (and two carcinomas) on colonoscopy after eight years of disease. Therefore, patients with apparently distal colitis should be followed in the clinic as well as those with known extensive colitis. For a surveillance programme in a district general hospital, eight patients per 100,000 population need to be seen weekly, 12 colonoscopies/100,000 population need to be carried out annually and the cost for each carcinoma detected is approximately 6015 pounds.

Adolescent↗

Symptoms and stool patterns in patients with ulcerative colitis.

The prevalence of symptoms and stool patterns was assessed prospectively in 96 patients with ulcerative colitis subdivided according to the extent and activity of the disease. Increased frequency of defecation (83%), urgency (85%), a feeling of incomplete evacuation (78%) and tenesmus (63%) were the most frequent symptoms experienced by patients with active colitis. All were significantly more common (p less than 0.001) in patients with active than quiescent colitis and their prevalence was similar in those with total and distal colitis, indicating that these symptoms are related to an inflamed and irritable distal colon. Twenty seven per cent of patients with active colitis voided hard stools indicative of constipation, however, and this was more common in active, than quiescent colitis (p less than 0.05). This feature is probably secondary to faecal stasis in the proximal colon, and an apt description of the bowel disturbance in ulcerative colitis, irrespective of the extent of disease is that the colon suffers from proximal constipation and distal irritability.

Adult↗

Liver histology and follow up of 68 patients with ulcerative colitis and normal liver function tests.

Hepatobiliary disorders are well known complications in patients with ulcerative colitis but it is not possible to predict those patients with ulcerative colitis who will eventually develop liver disease. In this study, liver biopsies from 74 patients with ulcerative colitis have been reevaluated. None of the patients showed clinical or biochemical signs of liver disease at the time of biopsy. Thirty seven (50%) had a completely normal liver biopsy. The others showed minimal portal inflammation or fatty infiltration. The biopsies of three patients displayed concentric, periductular fibrosis, or so called 'onion skin' lesions. None showed other signs of fibrosis or cirrhosis. The histological findings were unrelated to either activity or extent of colitis, except for the onion skin lesions which were seen exclusively in biopsies of patients with involvement of the total colon. Sixty eight of the 74 patients were reviewed after a mean interval of 18 years. The majority had no symptoms of hepatobiliary disorders and only two had developed liver disease; one suffered from cryptogenic cirrhosis, possibly due to non-A, non-B hepatitis and the other of an autoimmune liver disease and later developed a bile duct carcinoma. Both were women with total colonic involvement. At the time of the first liver biopsy one showed no histological abnormalities and the other only minor fatty infiltration. Thus, minor abnormalities in liver tissue are common in patients with ulcerative colitis without biochemical evidence of liver disease. The morphological changes are of little help in predicting the future risk of a patient with ulcerative colitis developing a clinically relevant hepatobiliary complication. The absence of biochemical parameters for liver disease during the early years of ulcerative colitis predict a favourable longterm diagnosis as regards hepatobiliary complications.

Adolescent↗

Dysplasia and carcinoma in longstanding ulcerative colitis: an endoscopic and histological surveillance programme.

From 1976 to 1989 a total of 66 patients with longstanding ulcerative colitis were entered in a colonoscopic surveillance programme in order to detect dysplasia. Thirty patients had extensive or total ulcerative colitis and 36 left sided colitis. The median duration of the disease at the end of the follow up was 15.0 years. Altogether 182 colonoscopies (2.8 per patient), each involving approximately 20 biopsies from different sites of the colon, were performed. In the total or extensive colitis group, five patients had low grade and one patient had high grade dysplasia. In the left sided colitis group, three patients had low grade dysplasia. In three patients low grade dysplasia was detected in a macroscopic lesion or mass of colonic mucosa. Sixty per cent of the dysplasia specimens were from the right colon. The incidence of dysplasia was higher in patients with extensive colitis and increased with the duration of the disease. None of the patients have so far developed colorectal carcinoma. Our results indicate that a colonoscopic surveillance programme is a safe alternative to prophylactic colectomy in longstanding ulcerative colitis.

Adolescent↗

Mr 40,000 human colonic epithelial protein expression in colonic mucosa and presence of circulating anti-Mr 40,000 antibodies in cotton top tamarins with spontaneous colitis.

Saguinus oedipus, Callithrix jacchus, and Saguinus fuscicollis are three species of New World monkeys which develop a form of colitis that is similar to human ulcerative colitis. Only S oedipus, however, develop colon cancer. We examined intestinal tissues from these animals for the presence of an antigen cross reacting to the Mr 40,000 human colonic epithelial protein that acts as an autoantigen in ulcerative colitis. Using an anti-Mr 40,000 monoclonal antibody (7E12H12, IgM isotype), by an immunoperoxidase assay we showed that all colon specimens from S oedipus reacted with 7E12H12; however, the colonic tissue from C jacchus and S fuscicollis did not. In immunotransblot analysis eluted IgG antibody bound to human ulcerative colitis colon (CCA-IgG) reacted with Mr 40,000 protein(s) present in the extracts of colon from S oedipus animals and humans. Small intestinal tissue reacted neither with 7E12H12 nor with CCA-IgG. In S oedipus, the Mr 40,000 protein was localised exclusively to colonic epithelial cells. Preincubation of seven S oedipus colon specimens with eight of 10 sera from animals with acute or chronic colitis and 0 of four sera from animals without colitis almost completely inhibited the binding of 7E12H12 to the colonic epithelium. Four of these 10 sera inhibited the binding of 7E12H12 to the autologous colon. These results show the presence of circulating autoantibodies in S oedipus with colitis against an epitope(s) on Mr 40,000 protein shared by human and S oedipus colon.

Animals↗

Serum antineutrophil cytoplasmic autoantibodies in inflammatory bowel disease are mainly associated with ulcerative colitis. A correlation study between perinuclear antineutrophil cytoplasmic autoantibodies and clinical parameters, medical, and surgical treatment.

Perinuclear antineutrophil cytoplasmic antibodies have recently been demonstrated in the sera of patients with inflammatory bowel disease. Three hundred and sixty six sera obtained from 120 patients with ulcerative colitis, 105 patients suffering from Crohn's disease and 49 non-inflammatory bowel disease controls were tested in two laboratories, using an indirect immunofluorescence assay. In addition, a fixed-neutrophil enzyme linked immunoadsorbent assay (ELISA) was evaluated in one of the two laboratories. The results in the immunofluorescence test showed a high degree of correlation between the two laboratories (Kappa coefficient = 0.8). Ninety five of the 120 (79%) ulcerative colitis patients had a positive test whereas only 14 of the 105 (13%) patients with Crohn's disease were positive. Sera from four patients suffering from primary sclerosing cholangitis were positive as well as four of the 45 control sera (9%). The sensitivity of the perinuclear antineutrophil cytoplasmic antibody immunofluorescence test for the diagnosis of ulcerative colitis was 0.75 with a specificity of 0.88 and a positive predictive value of 0.88 (all sera). In the ELISA technique 37 of 94 ulcerative colitis sera and one of the 68 Crohn's disease sera were positive. In the control group only one of the patients suffering from primary sclerosing cholangitis reacted positively (32 non-inflammatory bowel disease sera tested). The ELISA technique had a high specificity (0.97), but a low sensitivity (0.39). There was no relation of perinuclear antineutrophil cytoplasmic antibodies in ulcerative colitis patients or in Crohn's disease patients with disease activity, duration of illness, localisation, extent of disease, previous bowel operations or medical treatment. The clinical significance of perinuclear antineutrophil cytoplasmic antibody positive and negative subsets in both groups of patients thus remains unexplained. Our study confirms that determination of serum antineutrophil cytoplasmatic antibodies in patients with inflammatory bowel disease may differentiate ulcerative colitis from Crohn's disease. Further immunological studies are needed to explain the absence of these antibodies in a subset of ulcerative colitis patients and their role in the pathogenesis of the disease.

Adult↗

Experimental colitis is ameliorated by inhibition of nitric oxide synthase activity.

Enhanced nitric oxide (NO) generation by stimulated NO synthase (NOS) activity may, through its oxidative metabolism contribute to tissue injury in experimental colitis. In this study the possible amelioration of experimental colitis by NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NOS activity, was evaluated. Colitis was induced in rats by intracolonic administration of 30 mg trinitrobenzene sulphonic acid (TNB) dissolved in 0.25 ml 50% ethanol or by flushing the colon of capsaicin pretreated rats with 2 ml of 5% acetic acid. In several experiments, L-NAME 0.1 mg/ml was added to the drinking water at the time of colitis induction with TNB or seven days before acetic acid treatment. Rats were killed at various time intervals after induction of colitis. A 10 cm distal colonic segment was isolated, weighed, lesion area measured, and explants organ cultured for 24 hours for determination of NO generation by the Greiss reaction. The rest of the mucosa was scraped for determination of myeloperoxidase and NOS activities and leukotriene generation. In TNB treated rats mean arterial pressure was also determined up to 72 hours after damage induction, with or without cotreatment with nitroprusside. L-NAME significantly decreased the extent of tissue injury in TNB treated rats. Seven days after TNB treatment lesion area was reduced by 55%, colonic weight by 37%, and myeloperoxidase and NOS activity by 59% and 42%, respectively. Acetic acid induced colitis in capsaicin pretreated rats was also significantly decreased by L-NAME. Twenty four hours after acetic acid treatment lesion area was reduced by 61%, colonic weight by 21% and NOS activity by 39%. Mean (SEM) arterial blood pressure in TNB+L-NAME treated rats was 37.6 (8.1) mm Hg higher than in TNB treated rats, an effect that was only partially abolished by nitroprusside. These results show that inhibition of NO synthesis by an L-arginine analogue significantly ameliorates the extent of tissue injury in two models of experimental colitis, an effect that is not due only to its vasoconstrictor properties. Modulation of NO generation may be a novel therapeutic approach in inflammatory bowel disease.

Animals↗

Colitis and colonic mucosal barrier dysfunction.

Trauma, infection, neoplasia, and inflammation can all disrupt the intact intestinal mucosal barrier to intraluminal bacteria and bacterial antigens. This study investigated the relation between colonic inflammation and colonic mucosal barrier function in three experimental models of colitis. There were significantly increased systemic endotoxin concentrations in rats with acetic acid (7.5 (1.7-119.5) pg/ml), ethanol (13.7 (0-111.2) pg/ml), and hapten induced (14.4 (5-31.1) pg/ml) colitis compared with saline controls (3.3 (0-13.7) pg/ml). Data expressed as median (range). There were significant correlations between the systemic endotoxin concentration and both the severity of colitis and of illness in acetic acid induced colitis. A significant increase in colonic permeability to 14C-polyethylene glycol was shown in rats with acetic acid (3.42 (1.36-5.63)%) and hapten induced colitis (2.86 (1.03-8.10)%) compared with saline controls (1.20 (0.67-1.36)%). Data expressed as median (range) of percentage of the intracolonic bolus excreted in urine. There was a significant positive correlation between the severity of colitis and % colonic permeability to 14C-polyethylene glycol. This and other studies provide evidence that mucosal barrier dysfunction is a feature of colitis irrespective of aetiology or species. Such barrier dysfunction may be responsible for the systemic inflammatory response and complications seen in patients with inflammatory bowel disease.

Acetates↗

Kinetic studies on colonocyte metabolism of short chain fatty acids and glucose in ulcerative colitis.

Short chain fatty acids (SCFAs) are potentially valuable as a topical therapy for distal ulcerative colitis. The mechanism of action is unknown but may involve improved intracellular energy production as previous evidence indicates that colonocyte oxidation of butyrate is impaired in ulcerative colitis. No information is, however, available on human mucosal metabolism of acetate and propionate in either health or disease or the Vmax and Km values of butyrate oxidation. The aim of the study was to assess the kinetic parameters, Vmax and Km, of the complete oxidation of short chain fatty acids and glucose by human colonocytes and to explore whether a metabolic abnormality could be confirmed in patients with ulcerative colitis. Colonocytes were isolated from surgical specimens obtained from 14 patients with ulcerative colitis and eight control subjects. Incubations were performed in the presence of a concentration range of 14C-labelled acetate, propionate butyrate, and glucose. Oxidation rates were obtained by quantifying the production of 14CO2. Vmax and Km were calculated by computer fitting of the data to a Michaelis-Menten plot. No significant differences were shown in either Vmax or Km values of any of the SCFAs or glucose comparing controls and patients with ulcerative colitis. Comparing the results obtained regarding the individual SCFAs, the most striking difference was the considerably lower Km value of butyrate. The apparent Vmax of acetate tended to be higher than Vmax of propionate and butyrate. Vmax of glucose oxidation was significantly lower compared with the Vmax values of SCFA oxidation. The study shows the ability of isolated human colonocytes to utilise each of the three major SCFAs, but does not support a pathogenic role for defective metabolism of butyrate in ulcerative colitis. The considerably lower Km of butyrate oxidation supports a specific role of butyrate as an energy source for the colonic mucosa in both health and ulcerative colitis.

Adult↗

Lack of effect of antineutrophil cytoplasmic antibodies associated with ulcerative colitis on superoxide anion production from neutrophils.

BACKGROUND: Antineutrophil cytoplasmic antibodies (ANCAs) from patients with vasculitidis can induce neutrophils to release oxygen radicals in vitro. ANCAs with a perinuclear pattern of immunofluorescence are found in most patients with ulcerative colitis, but several findings are against ANCAs having a pathogenetic role in this disease. AIMS: To evaluate the influence of ANCAs associated with ulcerative colitis on the respiratory burst activity of neutrophils. PATIENTS: Serum samples were obtained from 14 patients with ulcerative colitis, seven of whom showed positivity for p-ANCAs, three patients with vasculitidis, two with positivity for p-ANCAs, and one for c-ANCAs, and seven healthy volunteers. METHODS: A positive ANCA serology was determined with a standard indirect immunofluorescence assay. Purified immunoglobulins (IgGs) were prepared from serum samples by DEAE-Affigel blue chromatography. Human neutrophils were prepared by dextran-Ficoll-Hypaque separation. Superoxide anion (O2-.) generation was measured by following the superoxide dismutase inhibitable reduction of ferricytochrome. RESULTS: There were no significant differences among samples from ulcerative colitis IgG p-ANCA positive, ulcerative colitis IgG p-ANCA negative patients, and controls on O2-. production, whereas ANCA positive IgG from vasculitidis significantly enhanced O2-. release (p < 0.001). CONCLUSIONS: p-ANCAs associated with ulcerative colitis have no effect on the respiratory burst activity of normal human neutrophils in vitro. These results reinforce the hypotheses that ANCAs are unlikely to contribute to the pathogenesis of ulcerative colitis.

Antibodies, Antineutrophil Cytoplasmic↗

Lymphocytic colitis: clinical presentation and long term course.

BACKGROUND: Lymphocytic colitis is characterised by chronic watery diarrhoea with normal endoscopic or radiological findings and microscopic evidence of pronounced infiltration of the colonic mucosa with lymphocytes. AIM: To investigate the long term clinical and histological evolution of the disease in a large group of patients with well characterised lymphocytic colitis. METHODS: Between 1986 and 1995 the histological diagnosis of lymphocytic colitis was obtained in 35 patients; 27 of these agreed to a follow up examination. All clinical, endoscopic, and histopathological records were reviewed at that time and the patients had a second endoscopic examination with follow up biopsies. RESULTS: The patients initially presented with the typical findings of lymphocytic colitis. After a mean (SD) follow up of 37.8 (27.5) months, diarrhoea subsided in 25 (93%) and histological normalisation was observed in 22 (82%) of the 27 patients. Progression from lymphocytic colitis to collagenous colitis was not observed. CONCLUSIONS: Lymphocytic colitis is characterised by a benign course with resolution of diarrhoea and normalisation of histology in over 80% of patients within 38 months. Considering the benign course of the disease, the potential benefit of any drug treatment should be carefully weighed against its potential side effects.

Adult↗

Role of bile acids and bile acid binding agents in patients with collagenous colitis.

BACKGROUND: In a retrospective study bile acid malabsorption was observed in patients with collagenous colitis. AIMS: To study the occurrence of bile acid malabsorption and the effect of bile acid binders prospectively in patients with chronic diarrhoea and collagenous colitis. METHODS: Over 36 months all patients referred because of chronic diarrhoea completed a diagnostic programme, including gastroscopy with duodenal biopsy, colonoscopy with biopsies, and the (75)Se-homocholic acid taurine ((75)SeHCAT) test for bile acid malabsorption. Treatment with a bile acid binder (cholestyramine in 24, colestipol in three) was given, irrespective of the results of the (75)SeHCAT test. RESULTS: Collagenous colitis was found in 28 patients (six men, 22 women), 27 of whom had persistent symptoms and completed the programme. Four patients had had a previous cholecystectomy or a distal gastric resection. The (75)SeHCAT test was abnormal in 12/27 (44%) of the collagenous colitis patients with (75)SeHCAT values 0.5-9.7%, and normal in 15 patients (56%). Bile acid binding treatment was followed by a rapid, marked, or complete improvement in 21/27 (78%) of the collagenous colitis patients. Rapid improvement occurred in 11/12 (92%) of the patients with bile acid malabsorption compared with 10/15 (67%) of the patients with normal (75)SeHCAT tests. CONCLUSION: Bile acid malabsorption is common in patients with collagenous colitis and is probably an important pathophysiological factor. Because of a high response rate without serious side effects, bile acid binding treatment should be considered for collagenous colitis, particularly patients with bile acid malabsorption.

Adult↗

Butyrate and glucose metabolism by colonocytes in experimental colitis in mice.

BACKGROUND/AIMS: Impaired colonocyte metabolism of butyrate has been implicated in the aetiopathogenesis of ulcerative colitis. Colonocyte butyrate metabolism was investigated in experimental colitis in mice. METHODS: Colitis was induced in Swiss outbred white mice by oral administration of 4% dextran sulphate sodium (DSS). Colonocytes isolated from colitic and normal control mice were incubated with [(14)C]butyrate or glucose, and production of (14)CO(2), as well as of intermediate metabolites (acetoacetate, beta-hydroxybutyrate and lactate), was measured. The effect of different substrate concentrations on oxidation was also examined. RESULTS: Butyrate oxidation (micromol/h per mg protein; mean (SEM)) was significantly reduced in DSS colitis, values on day 7 of DSS administration being 0.177 (0.007) compared with 0.406 (0.035) for control animals (p<0.001). Glucose oxidation (micromol/h per mg protein; mean (SEM)) on day 7 of DSS administration was significantly higher than in controls (0.06 (0.006) v 0.027 (0.004), p<0.001). Production of beta-hydroxybutyrate was decreased and production of lactate increased in DSS colitis compared with controls. Increasing butyrate concentration from 10 to 80 mM enhanced oxidation in DSS colitis (0.036 (0.002) to 0.285 (0.040), p<0.001), although it continued to remain lower than in controls. Surface and crypt epithelial cells showed similar ratios of butyrate to glucose oxidation. When 1 mM DSS was added to normal colonocytes in vitro, it did not alter butyrate oxidation. The initial histological lesion of DSS administration was very patchy and involved crypt cells. Abnormal butyrate oxidation became apparent only after six days of DSS administration, at which time histological abnormalities were more widespread. CONCLUSIONS: Colonocyte metabolism of butyrate, but not of glucose, is impaired in DSS colitis, and may be important in pathophysiology. Histological abnormalities preceded measurable defects in butyrate oxidation.

Animals↗

Effects of appendicectomy on the course of ulcerative colitis.

BACKGROUND: Appendicectomy reduces the risk of having ulcerative colitis. However, its effect on the natural history of ulcerative colitis remains uncertain. AIM: To determine whether appendicectomy reduces the overall severity of ulcerative colitis. PATIENTS AND METHODS: Appendicectomy status and smoking habits were specified by direct interview in 638 patients seen consecutively between 1997 and 2000. Severity of ulcerative colitis was assessed by reviewing therapeutic needs from the onset of colitis. Additionally, the annual incidence of flare up was assessed prospectively between 1997 and 2000 in patients who had not been colectomised. RESULTS: The 10 year risk of colectomy was 16 (7)% in previously appendicectomised patients (n=49) compared with 33 (2)% in non-appendicectomised patients (n=589, p=0.05). Cox regression showed that previous appendicectomy and current smoking were independent factors protecting against colectomy (adjusted hazard ratio and 95% confidence intervals: 0.40 (0.20-0.78) and 0.60 (0.40-0.95), respectively). The respective proportions of appendicectomised and non-appendicectomised patients who required oral steroids and immunosuppressive therapy were not significantly different (67% v 70% and 27% v 19%, respectively). Between 1997 and 2000, ulcerative colitis was active for 48% of the time in appendicectomised patients (47 of 98 patient years) and for 62% of the time in non-appendicectomised patients (631 of 1024 patient years; p<0.01). CONCLUSION: Previous appendicectomy is associated with a less severe course of ulcerative colitis. The beneficial effect of appendicectomy on the risk of colectomy is additive to that of current smoking.

Adult↗

Neutrophil cytoplasmic antibodies (p-ANCA) in ulcerative colitis.

AIMS: To study ulcerative colitis associated neutrophil cytoplasmic antibodies (p-ANCA) in respect of class and subclass distribution, antigen specificity, and (sub)cellular localisation of the antigen(s) to which these antibodies are directed. METHODS: p-ANCA positivity was determined using the standard indirect immunofluorescence test (IIFT). The immunoglobulin (Ig) subclass distribution of p-ANCA was investigated using monoclonal antibodies directed against IgG1, IgG2, IgG3, and IgG4. Intracellular antigen localisation studies were performed on (fractionated) neutrophils using antigen-specific antibodies. RESULTS: In contrast to vasculitis associated ANCA, ulcerative colitis p-ANCA are mainly of IgG1 and IgG3 subclass and lack IgG4. Ulcerative colitis p-ANCA are myeloid specific. IIFT data indicate that the related antigen(s) seem(s) to be located not in the cytosol, but in the granules (most likely the azurophil granules) of the neutrophil. CONCLUSIONS: p-ANCA in ulcerative colitis have a different immunoglobulin subclass distribution than the ANCA of systemic necrotising vasculitis and necrotising and crescentic glomerulonephritis. This may point to differences in immune regulation between these diseases. Both cathepsin G and lactoferrin are recognised by a subpopulation of ulcerative colitis p-ANCA. In our series, eight out of 36 (22%) of ulcerative colitis associated p-ANCA react with lactoferrin and seven (19.5%) other sera with cathepsin G. None of them recognised both antigens. The main target antigen(s) of ulcerative colitis p-ANCA still remain(s) to be identified.

Antibodies, Antineutrophil Cytoplasmic↗

Acute colitis induced by dextran sulfate sodium progresses to chronicity in C57BL/6 but not in BALB/c mice: correlation between symptoms and inflammation.

Exposure to dextran sulfate sodium (DSS) induces acute colitis, which is normally resolved after DSS removal. To study chronicity, mice are typically subjected to three to five cycles of weekly DSS exposures, each followed by a 1- to 2-wk rest period. Here, we describe a novel and convenient way of inducing chronic, progressive colitis by a single exposure to DSS. C57BL/6 mice exposed to DSS for 5 days developed acute colitis that progressed to severe chronic inflammation. The plasma haptoglobin levels remained high during the chronic phase, showing that the inflammation was active. Surprisingly, the mice regained their original weight along with the progression of colitis, and the only apparent symptom was loose feces. Histopathological changes 4 wk after DSS removal were dense infiltrates of mononuclear cells, irregular epithelial structure, and persistent deposits of collagen. A progressive production of the cytokines IL-1beta, IL-12 p70, and IL-17 correlated with the extensive cellular infiltration, whereas high IFN-gamma production was mainly found late in the chronic phase. Similar to C57BL/6 mice, BALB/c mice exposed to 5 days of DSS developed acute colitis as previously described. The acute colitis was accompanied by elevated plasma levels of haptoglobin and increased colonic levels of IL-1alpha/beta, IL-6, IL-18, and granulocyte colony-stimulating factor. However, soon after DSS removal, BALB/c mice recovered and were symptom free within 2 wk and completely recovered 4 wk after DSS removal in terms of histopathology, haptoglobin levels, and local cytokine production. In summary, these data stress the effect of genetic background on the outcome of DSS provocation. We believe that the present protocol to induce chronic colitis in C57BL/6 mice offers a robust model for validating future therapies for treatment of inflammatory bowel disease.

Acute Disease↗

Effect of acute experimental colitis on rabbit colonic smooth muscle.

The membrane potential and contractile activity of colonic circular smooth muscle from New Zealand White rabbits were studied after the production of acute experimental colitis. Colitis was induced in the distal colon by rectal infusion of formaldehyde solution, followed by an intravenous bolus of soluble immune complexes. Despite active mucosal inflammation, there are only occasional inflammatory cells in the muscularis. Electrophysiological studies on tissue from control rabbits and rabbits with colitis were performed using double sucrose gap and intracellular microelectrode techniques. The resting membrane potential was lower (-44 +/- 3 mV) in muscle from rabbits with colitis compared with control animals (-54 +/- 2 mV) (P less than 0.02). Amplitude of the electrotonic potential after a hyperpolarizing current pulse was decreased (P less than 0.05) and the time constant was shortened (P less than 0.01) in muscle from animals with colitis compared with normal animals. Amplitude (13.1 +/- 2.3 mV) and maximum rate of rise (0.24 +/- 0.06 V/s) of the spike potential, initiated by a depolarizing current pulse, were decreased in muscle from animals with colitis compared with muscle from healthy animals (P less than 0.001). Isometric tension generation after electrical and chemical depolarization of the membrane or bethanechol administration was decreased (P less than 0.001) in muscle from colitic animals. These studies suggest 1) membrane resistance and membrane potential are decreased in muscle strips from animals with colitis; and 2) there is a disturbance in the electrical and mechanical response of these tissues after stimulation.

Action Potentials↗