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Background & Aims: The efficacy of infliximab for treating patients with ulcerative colitis has been established., Methods: The Active Ulcerative Colitis Trial (ACT)-1 and ACT-2 randomized, double-blind, placebo-controlled studies evaluated infliximab induction and maintenance therapy in moderately to severely active ulcerative colitis. Overall, 728 patients received placebo or infliximab (5 or 10 mg/kg) intravenously at weeks 0, 2, and 6, then every 8 weeks through week 46 (ACT-1) or 22 (ACT-2). Colectomy, hospitalization, and surgery/procedure data through 54 weeks after the first infusion were obtained from ACT-1, ACT-2, and associated data sources. In the prespecified analysis, all data were combined to ascertain time to colectomy. Kaplan-Meier product-limit method was used to estimate the cumulative incidence of colectomy, and log-rank test was used to compare the combined infliximab group and placebo., Results: Eighty-seven percent (630 of 728) of patients had complete colectomy follow-up; 13% (98 of 728) of patients had a median follow-up of 6.2 months. The cumulative incidence of colectomy through 54 weeks was 10% for infliximab and 17% for placebo (P = .02), yielding an absolute risk reduction of 7%. Compared with placebo, fewer ulcerative colitis-related hospitalizations and surgeries/procedures per 100 patient-years of treatment occurred with infliximab therapy: 40 vs 20 (P = .003) and 34 vs 21 (P = .03), respectively. Serious adverse events occurring in infliximab-treated patients included serious infections, tuberculosis, histoplasmosis, listeriosis, and malignancy., Conclusions: Patients with moderately to severely active ulcerative colitis treated with infliximab were less likely to undergo colectomy through 54 weeks than those receiving placebo.

Background & Aims: Sulfhydryl compounds are essential in maintaining mucosal integrity, and nitric oxide may contribute to tissue injury. The aim of this study was to characterize experimental colitis induced by a sulfhydryl blocker., Methods: Colitis was induced in rats by intracolonic administration of 0.1 mL 3% iodoacetamide with and without addition of 0.1 mg/mL NG-nitro-L-arginine methyl ester (L-NAME) to the drinking water. After death, the distal colonic segment was resected and weighed, and mucosal inflammatory mediator, myeloperoxidase, and NO synthase activities were determined., Results: Iodoacetamide induced multifocal mucosal erosions and ulceration that were present for up to 1 week. At 3 weeks, the mucosa was almost intact. Colonic wet weight was maximal at 7 days. Myeloperoxidase activity and NO generation were increased in the first 72 hours, and NO synthase activity and prostaglandin E2 generation were increased up to 21 days. Leukotriene B4 and leukotriene C4 generation were increased up to 14 days. One week after iodoacetamide plus L-NAME treatment, lesion area was reduced by 85% and NO synthase activity by 52%., Conclusions: Inflammatory mediators have an important contribution to the pathogenesis of colonic injury induced by a sulfhydryl alkylator. The protective effect of L-NAME indicates that NO contributes to tissue injury and that its modulation may be a novel approach to treat inflammatory bowel disease.

Background/aims: Enteroadherent Escherichia coli that produce Shiga-like toxins are important causes of human disease, including enterohemorrhagic E. coli-induced colitis (EHEC). The role of Shiga-like toxins in these illnesses is unclear. The aim of this study was to establish an animal model for human EHEC and to determine the role of Shiga-like toxin I (SLT-I) in this model., Methods: E. coli strain RDEC-1 is an enteroadherent rabbit diarrheal pathogen. An isogenic variant of RDEC-1 (termed RDEC-H19A) producing high levels of SLT-I was obtained by infecting RDEC-1 with an SLT-I-converting bacteriophage. The effects of in vivo enteric infection produced in rabbits by RDEC-H19A were compared with those in uninfected and RDEC-1-infected animals., Results: SLT-I-producing RDEC-H19A induced a severe, noninvasive, enteroadherent infection in rabbits. Clinically, infection with RDEC-H19A was more severe than infection with RDEC-1 and caused more serious histological lesions including vascular changes, edema, and more severe inflammation. Interleukin 1 and platelet-activating factor appear to be important inflammatory mediators to this infection., Conclusions: The illness induced by RDEC-H19A in rabbits resembled enterohemorrhagic E. coli-induced colitis of humans. SLT-I is an important virulence factor in the pathogenesis of EHEC.

Background: Excessive production of nitric oxide, characteristic of inflamed states, may have deleterious effects through its facile conversion (in the presence of O2) to peroxynitrite, which promotes lipid and sulfhydryl oxidation. This study assessed the effect of peroxynitrite on the rat colon., Methods: Peroxynitrite was administered intrarectally to rats. One, 3, 7, and 21 days after treatment, a distal colonic segment was isolated and tissue was obtained for histological evaluation and determination of myeloperoxidase activity and NOX, and eicosanoids generation., Results: Within 24 hours, the exposed segment was edematous and congested with occasional hemorrhagic mucosal ulceration. On day 7, the lumen was narrow; at day 21, there were signs of stenosis. Histological analysis showed transmucosal necrosis, acute inflammation, and exudative edema 24 hours after treatment. Surface re-epithelization and infiltration of granulation tissue were present at 1 week. Resolution of edema, mucin repletion, thickening of muscularis mucosa and propria, and fibrosis were observed at 3 weeks. Significant increase in NOX generation and myeloperoxidase and NO synthase activities were observed at 24 hours, whereas enhanced leukotriene generation was observed only at 21 days., Conclusions: Peroxynitrite-induced colonic inflammation provides a novel model of NO-related tissue injury and offers the opportunity to further explore the potential role of NO in the pathogenesis of inflammatory bowel disease.

Background: Clostridium difficile toxin A is the principal mediator of inflammatory enterocolitis in experimental animals. The purpose of this study was to explore the effect of ketotifen, an anti-inflammatory drug, on toxin A-induced enterotoxicity in rat ileum., Methods: The effects of intragastric administration of ketotifen on secretion, mannitol permeability, histological damage, and mucosal levels of leukotriene B4, leukotriene C4, and platelet activating factor in toxin A-exposed rat ileal loops were measured in vivo. The effects of ketotifen on toxin A-mediated release of rat mast cell protease II (rat mucosa mast cell product) release were also measured in rat ileal explants in vitro. The effect of ketotifen on neutrophil migration in vitro was also evaluated., Results: Ketotifen pretreatment inhibited toxin A-associated intestinal secretion by 42.5% and mannitol permeability by 56.3% and reduced epithelial cell inflammation and necrosis. These effects were associated with reduced levels of leukotriene B4 by 65.8%, leukotriene C4 by 88.8%, platelet activating factor by 77.8%, and inhibition of rat mast cell protease II by 58.4%. In addition, pretreatment of neutrophils with ketotifen inhibited neutrophil migration in vitro., Conclusions: The protective effect of ketotifen in this animal model was associated with significant inhibition of release of mast cells and neutrophil derived mediators, supporting their involvement in C. difficile enteritis.

Background: Interleukin 1 (IL-1) is a key mediator of bowel inflammation, but there is limited knowledge about the amount and site of production of this cytokine in the gastrointestinal tract under physiological or pathological conditions., Methods: Epithelial and lamina propria mononuclear cells were isolated from control, and Crohn's disease- and ulcerative colitis-involved mucosa to investigate the capacity of these cells to generate IL-1 bioactivity, IL-1 alpha and IL-1 beta immunoreactivity, and gene expression., Results: Control lamina propria mononuclear cells produced substantial amounts of IL-1 alpha and IL-1 beta, which increased dramatically when inflammatory bowel disease cells were used. Epithelial cells from control, Crohn's disease, and ulcerative colitis intestine displayed no IL-1 bioactivity or immunoreactivity. Lamina propria mononuclear cells contained moderate to large quantities of IL-1 alpha and IL-1 beta messenger RNA (mRNA), respectively, whereas epithelial cells had none. The absence of IL-1 transcripts in epithelial cells was selective, because mRNA for HLA-DR antigens was present in control and inflammatory bowel disease cells., Conclusions: In normal and inflamed human intestine there is a distinct compartmentalization of IL-1, as mononuclear but not epithelial cells generate this cytokine. The high levels of IL-1 in inflammatory bowel disease may explain several of its local and systemic manifestations, and blockade by specific antagonists could have important therapeutic effects.

Interleukin-2 activity of intestinal lamina propria mononuclear cells is decreased in Crohn's disease and ulcerative colitis patients compared with control patients with noninflammatory bowel disease. Factors that might be responsible for this phenomenon were investigated. Most interleukin-2 activity was produced by helper (CD4+) T cells. These were present in comparable numbers in both inflammatory bowel disease and control cultures, but the frequency of interleukin-2-producing cells was significantly (3-4 times) lower among Crohn's disease and ulcerative colitis than control cells. In agreement with this finding, levels of interleukin-2 messenger RNA were substantially decreased in both forms of inflammatory bowel disease compared with controls. Mucosal CD8+ T cells and plastic-adherent cells were unable to suppress interleukin-2 activity by autologous or allogeneic CD4+ T cells. The rate of interleukin-2 absorption was similar for inflammatory bowel disease and control cells. Induction of interleukin-2 by different stimuli (phorbol ester, phytohemagglutinin, or anti-CD3 monoclonal antibody) before or after incubation under basal conditions ("resting") failed to normalize the capacity to generate interleukin-2 by Crohn's disease and ulcerative colitis cells. Prostanoids (prostaglandin E2 and 6-keto-prostaglandin F1 alpha) were produced in large amounts in cultures of inflammatory bowel disease cells, but inhibition by indomethacin failed to restore interleukin-2 activity to control levels. Finally, supernatants from Crohn's disease and ulcerative colitis cell cultures failed to suppress interleukin-2 production by control CD4+ T cells. Our results show that the low interleukin-2 activity detected in inflammatory bowel disease mucosa is not caused by activated suppressor cells, excessive lymphokine utilization or immune stimulation, a defective response to activation signals, or production of inhibitory substances. Rather, the low interleukin-2 activity appears to be related to a loss of interleukin-2-producing mucosal CD4+ T cells. It is concluded that abnormalities of intestinal CD4+ T-cell function are associated with the immunopathogenesis of Crohn's disease and ulcerative colitis.

To elucidate the possible role of substance P in the pathogenesis of acute gastric mucosal damage, rats were treated intragastrically with 1.0 mL 96% ethanol, 0.6N HCl, or 25% NaCl, with or without IP coadministration of substance P, senktide, or septide (1 mumol/L per 100 g). All three peptides were found to double the mean lesion area when compared with that induced by ethanol, whereas substance P antagonist (1 mumol/L per 100 g) prevented the expansion of damage extent. The increased damage was associated with increased gastric mucosal levels of platelet activating factor, leukotriene B4, and leukotriene C4. Substance P antagonists also reduced by half the extent of the gastric damage induced by ethanol when administered by itself. WEB 2086 (platelet-activating factor antagonist; Boehringer Ingelheim KG, Germany), hydroxyzine (H1 blocker), and cimetidine (H2 blocker) reduced lesion area by 50%, but only in rats treated with both substance P and ethanol. Ketotifen (mast-cell stabilizer) (100 micrograms/100 g), administered orally 30 minutes before damage induction, totally abolished the extent of the damage induced by either ethanol or the coadministration of ethanol and peptides in the surface epithelium of the entire mucosa. The protective effect of ketotifen was accompanied by significant reduction in mucosal generation of platelet-activating factor, leukotriene C4, and leukotriene B4. Similar mucosal protection was afforded by ketotifen against damage induced by 0.6N HCl, 25% NaCl, or indomethacin. Therefore, it is suggested that substance P is involved in the pathogenesis of acute ethanol-induced gastric mucosal damage. The effective mucosal protection provided by ketotifen indicates the important role of mast cells and their mediators in the pathogenesis of acute gastric mucosal damage and may have therapeutic implications.

Seventy-seven patients presented with gastrointestinal obstruction due to phytobezoars during a 5-mo period. Most of the patients (88.3%) had a history of persimmon ingestion, and all had previous surgery for ulcer disease. Seventy-one patients were treated surgically; 67 because of intestinal obstruction and 4 for extraction of gastric phytobezoars. Five patients were reoperated once and 1 patient twice because of retained phytobezoars. Six patients were treated conservatively. Seventy-five patients recovered after surgical or conservative therapy, and 2 patients died. Patients who have undergone gastric surgery should be warned about the risk of persimmon ingestion.

To investigate the pathogenesis of diarrhea in ulcerative colitis, colonic adenylate cyclase activity was determined in patients and normal subjects. Basal adenylate cyclase activity in 19 patients with active disease [61.5 +/- 9.6 (mean +/- SE) pmol cyclic adenosine monophosphate/mg protein . 10 min] was two times higher (p less than 0.01) than its activity in colonic mucosa of 30 normal subjects or 10 ulcerative colitis patients in remission [31.4 +/- 2.0 and 23.6 +/- 1.9 pmol cyclic adenosine monophosphate/mg protein . 10 min, respectively]. The enzyme activity was stimulated to the same extent in all groups by sodium fluoride, vasoactive intestinal polypeptide, or by substitution in the assay mixture of guanosine triphosphate by its hydrolysis-resistant analogue--GTP gamma S. Prostaglandin E2 significantly stimulated the enzyme activity in tissue obtained from normal subjects, patients with shigellosis, and ulcerative colitis patients in remission while it had no effect on adenylate cyclase activity in colonic mucosa of patients with active ulcerative colitis. These results suggest that stimulation of colonic adenylate cyclase activity, possibly secondary to the reported enhanced colonic prostanoid synthesis, may contribute to the diarrhea in ulcerative colitis.

Platelet-activating factor is released from inflammatory cells. It activates neutrophils, releases secondary messengers, and mediates mucosal ulceration and ischemia in the rat. We assessed its possible role in the pathogenesis of ulcerative colitis. Colonic biopsy specimens from patients with active ulcerative colitis and controls were incubated for 4 h in Tyrode's buffer in the presence or absence of 0.2 microM calcium ionophore (A23187) or 50 microliter of antihuman immunoglobulin E. Platelet-activating factor was determined in the tissue by aggregation assay after extraction with 80% ethanol and was confirmed by thin-layer chromatography and its inactivation by phospholipases. Platelet-activating factor was not detected in normal mucosa. Only A23187 and antihuman immunoglobulin E stimulated its activity: mean +/- SE, 43.2 +/- 8.6 and 33.0 +/- 6.1 pg/10 mg wet wt, respectively. In active ulcerative colitis basal platelet-activating factor activity was 8.9 +/- 3.5 pg/10 mg wet wt. A23187 and antihuman immunoglobulin E induced significantly higher stimulation of platelet-activating factor synthesis when compared with their effects on normal mucosa: 200 +/- 28 and 70 +/- 8.3 pg/10 mg wet wt, respectively. The enhanced stimulation induced by A23187 was dose-dependently inhibited by salazopyrine, 5-amino-salicylic acid, and prednisolone, but not by sulfapyridine. It is thus suggested that platelet-activating factor may be involved in the pathogenesis of the inflammatory response in ulcerative colitis and that its inhibition by steroids, 5-aminosalicylic acid, and salazopyrine may be an additional mechanism to explain their therapeutic effects.

We tested whether human duodenojejunal mucosa is able to synthesize apoproteins from amino acid precursors because lipoprotein-like particles are visualized by electron microscopy in human absorptive cells and because apoproteins are synthesized by the perfused rat intestine. Duodenojejunal biopsies from 21 normal fasting volunteers were incubated with L-[U-14C]leucine; 15.6 +/- 3.3 nmoles of the [14C]leucine was incorporated into protein by 100 mg wet weight of biopsies during an incubation of 2 hr. No [14C]leucine was incorporated by boiled biopsies. Homogenates of incubated biopsies were fractionated by ultracentrifugation: 43 +/- 2% of the incorporated 14C as found in the d less than 1.006 fraction; 3.2 +/- 0.6%, 8.1 +/- 1.0% and 48 +/- 2% were found to be associated with the d = 1.006 to 1.063, d = 1.063 to 1.25, and d greater than 1.25 fractions, respectively. The specific activity in the d less than 1.006 fraction was 5.6 times greater than that in the other fractions. Of the 14C incorporated into the d less than 1.006 fraction, 10.8, 7.2, and 7.1% were specifically precipitated by rabbit antihuman apoproteins A-I, A-II, and B, respectively. Of the 14C incorporated into the d = 1.006 to 1.063 fraction, 11.3 4.1, and 8.5% were specifically precipitated by rabbit antihuman apoprotein A-I, A-II, and B, respectively. Approximately 5% of the 14C incorporated by the d = 1.063 to 1.25 fractions were precipitated by rabbit antihuman apoprotein A-I or A-II. None of the d less than 1.25 fractions precipitated a significant amount of radioactivity with rabit antihuman apoprotein C-II, or antiarginine-rich apoprotein. None of the antibodies precipitated radioactivity from the d greater than 1.25 fraction. These experiments suggest that human duodenojejunal mucosa is able to synthesize in vitro apoproteins A-I, A-II, and B from amino acid precursors. The specificity of the immunoprecipitates was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis.

Accumulation of 6-ketoprostaglandin F1 alpha and thromboxane B2, the stable metabolites of prostacyclin I2 and thromboxane A2 respectively, by cultured rectal mucosa obtained from patients with active ulcerative colitis was significantly higher than their respective accumulation by cultured biopsy specimens obtained from normal subjects. Accumulation of prostacyclin I2 and thromboxane A2 by rectal mucosa obtained from ulcerative colitis patients in remission was not enhanced. Prostacyclin I2, thromboxane A2, and prostaglandin E2 accumulation was significantly inhibited by the addition to the culture medium of 5-aminosalicylic acid, flufenamic acid, aspirin, azathioprine, and methylprednisolone. Sulfapyridine inhibited significantly only prostaglandin E2 and prostacyclin I2 while sulfasalazine inhibited thromboxane A2, prostaglandin E2, and prostacyclin I2 accumulation. Flufenamic acid potentiated the inhibition of prostaglandin E2 accumulation induced by methylprednisolone when administered alone. These results suggest that in addition to the mediation by prostaglandin E2, thromboxane A2 and prostacylin I2 may also be involved in the inflammatory response in ulcerative colitis. Moreover, the therapeutic effects of steroid hormones and sulfasalazine may be partially related to their inhibition of colonic prostaglandin E2, prostacyclin I2, and thromboxane A2 synthesis.

Synthesis of prostaglandin E2 and 6-keto prostaglandin F1 alpha by cultured antral and fundic gastric mucosa obtained from 86 patients with active duodenal ulcer who were not receiving medication was 50% lower (p less than 0.01) than their respective synthesis by cultured gastric mucosa in normal subjects. Antral and fundic prostanoid synthesis in patients receiving chronic therapy with nonsteroidal antiinflammatory drugs was almost completely inhibited. The decreased synthesis of antral and fundic prostaglandin E2 and 6-keto prostaglandin F1 alpha in duodenal ulcer patients was not affected following ulcer healing achieved after 4 wk of therapy with placebo, arbacet, misoprostol, sucralfate, and pirenzepine. In contrast, following 4 wk of therapy with ranitidine, both antral and fundic prostaglandin E2 synthesis were significantly increased when compared with their respective synthesis before therapy. These results confirm that gastric prostanoid synthesis is decreased in patients with active duodenal ulcer and in subjects treated with nonsteroidal antiinflammatory drugs, suggesting that decreased endogenous prostanoid synthesis may contribute to the pathogenesis of mucosal damage. The induction of endogenous prostanoids by ranitidine may contribute to its therapeutic effect.

The metabolism of 14C-labeled bile salts was studied in vitro during their absorption from infused segments of rat intestine. The transported bile salts were recovered in transudates which were collected from the serosal surface of infused segments. In the jejunum, 36% of transported [14C]deoxycholate and 48% of transported [14C]chenodeoxycholate were recovered as metabolites which migrated as a seemingly single polar compound on thin layer chromatography; 52 to 72% of these metabolites could be deconjugated by cholylglycine hydrolase to yield original [14C]deoxycholate or [14C]chenodeoxycholate, respectively. The jejunum metabolized 9 times more [14C]chenodeoxycholate than the ileum (38.1 nmoles per hr per g compared with 4.2 nmoles per hr per g), despite the fact that both segments transferred the same amount of radioactivity. In contrast, [14C]cholate, [14C]glycocholate, and [14C]glycodeoxycholate were transferred intact by the jejunum, ileum, and colon. Human jejunal and rectal mucosa were able to metabolize [14C]chenodeoxycholate to polar metabolites in vitro. Polar metabolites were also found in the portal plasma and jejunal wall 20 min after the feeding of [14C]chenodeoxycholate to bile fistula rats. It is suggested that these results complicate the interpretation of in vitro experiments on absorption of dihydroxy bile salts, and that they indicate that the human small intestine may be able to metabolize chenodeoxycholate.

Prostanoid synthesis by cultured peripheral blood mononuclear cells and monocytes in inflammatory bowel disease patients was determined because monocytosis was reported in inflammatory bowel diseases and prostanoids are synthesized by peripheral blood mononuclear cells in response to inflammatory stimuli. Prostaglandin E2 and thromboxane B2 accumulation in the medium of cultured peripheral blood mononuclear cells isolated from patients with active Crohn's disease was two and three times higher than their respective accumulation by peripheral blood mononuclear cells isolated from normal subjects or patients in remission. In ulcerative colitis, prostaglandin E2 and thromboxane B2 accumulation was not enhanced. 6-Keto-prostaglandin F1 alpha was not detected in any of the cultured medium. The absolute number of monocytes was determined according to their adherence to plastic surfaces, and the percent of phagocytic cells was significantly higher among peripheral blood mononuclear cells in patients with Crohn's disease and ulcerative colitis as compared with peripheral blood mononuclear cells isolated from normal subjects. However, prostaglandin E2 secretion, by the same number of cultured monocytes isolated from all groups of patients, was similar. Flufenamic acid, methylprednisolone, and 5-aminosalicylic acid significantly inhibited prostaglandin E2 and thromboxane B2 accumulation. These results suggest that in Crohn's disease enhanced prostanoid synthesis is probably due to the monocytosis, whereas in ulcerative colitis the monocytosis is not accompanied by a significant increase in prostanoid synthesis in vitro.

The effect of misoprostol and cimetidine on gastric cell turnover was studied. Endoscopic biopsy specimens of fundic and antral mucosa were obtained from duodenal ulcer patients before and after 4 wk of therapy with cimetidine 1.2 g/day or misoprostol 800 micrograms/day. Biopsy specimens were incubated with [3H]thymidine. Glandular column length and number of labeled cells were determined after autoradiography. There was no significant difference in column length of antral or fundic glands before or after therapy with cimetidine and misoprostol. The number of antral and fundic labeled cells was significantly decreased after misoprostol treatment (3.6 +/- 0.3 and 4.6 +/- 0.4, mean +/- SE), as opposed to their respective number before therapy (6.9 +/- 0.5 and 8.3 +/- 0.8) (p less than 0.01). On the other hand, after treatment with cimetidine, the number of antral and fundic labeled cells was significantly higher (11.8 +/- 0.9 and 7.5 +/- 1.0, respectively) as compared with their number before therapy (5.7 +/- 0.5 and 5.6 +/- 0.6, respectively). The decreased gastric cell turnover induced by misoprostol indicates that the trophic effect of prostanoids on gastric mucosa is not due to an increase in cellular kinetics. The increased gastric cell turnover induced by cimetidine may contribute to its therapeutic effect in peptic ulcer disease.