Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.11.1.7 (peroxidase)
65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In inflammatory bowel disease, prostaglandins are mucosal protective whereas leukotrienes are proinflammatory. Recent evidence suggests that the formation and action of leukotrienes are calcium-dependent, whereas the formation and action of prostaglandins are not. To examine the possibility that, because of differential regulation of arachidonic acid metabolism, calcium channel blockade might alter mucosal eicosanoid synthesis and accelerate healing during inflammatory bowel disease, we treated a 4% acetic acid-induced colitis model with verapamil and/or misoprostol and determined the effects on colonic macroscopic injury, mucosal inflammation as measured by myeloperoxidase activity, in vivo intestinal fluid absorption, and mucosal prostaglandin E2 and leukotriene B4 (LTB4) levels as measured by in vivo rectal dialysis. In colitic animals, verapamil treatment significantly improved colonic fluid absorption and macroscopic ulceration. This mucosal-protective effect of verapamil occurred in the presence of a twofold reduction in mucosal LTB4 synthesis. In noncolitic animals, verapamil alone had no effect on in vivo fluid absorption, macroscopic ulceration, or myeloperoxidase activity but did induce a threefold reduction in LTB4 synthesis in addition to shifting arachidonic acid metabolism towards a sixfold stimulation of prostaglandin E2 synthesis. Our results show that, when administered before the experimental induction of colitis, the calcium channel blocker, verapamil, has a mucosal-protective effect that occurs as a consequence of reduced mucosal leukotriene synthesis and increased prostaglandin synthesis. This differential regulation of arachidonic acid metabolism may play an important role in the development of novel therapeutic agents for inflammatory bowel disease.
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PMID:Verapamil alters eicosanoid synthesis and accelerates healing during experimental colitis in rats. 131 74

Two models of colitis produced in rats that have received significant attention over the past few years are the acetic acid and trinitrobenzene sulfonic acid (TNBS) models. The objective of this study was to quantify and compare the temporal relationship among mucosal permeability, epithelial injury, and inflammation induced by acetic acid, ethanol (vehicle), ethanol plus TNBS (unbuffered, pH 1.0), and ethanol plus TNBS (pH 7.4). Data obtained show that the inflammation induced by these four irritants results from caustic injury to the colonic epithelium and interstitium as measured by the rapid and dramatic increases in mucosal permeability and tissue water content as well as by histological analysis. The injurious nature of TNBS was confirmed in a separate series of studies showing that buffered TNBS (pH 7.4), in the absence of ethanol, is toxic to cultured rat intestinal epithelial cell monolayers. Only after 1-2 days of the initial insult, were signs of classical inflammation observed, including increases in colonic myeloperoxidase activity (neutrophil infiltration) and colon weight as well as hyperemia and mucosal ulcerations. Although ethanol plus TNBS (pH 1.0 or 7.4) tended to produce higher mucosal permeabilities (epithelial cell injury) at 1-2 weeks after the enemas than acetic acid or ethanol groups, only the ethanol plus TNBS (pH 7.4) permeabilities were found to be significantly enhanced. In addition, all four groups showed significant elevations in colonic myeloperoxidase activity and colon weight at 1-2 weeks after enema. It is suggested that these models of colitis are useful to study events that occur at the time of inflammation and repair. However, these models may have significant limitations in understanding events that initiate inflammation of the intestine in human inflammatory bowel disease.
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PMID:A comparative analysis of two models of colitis in rats. 131 49

The in vitro synthesis of leukotriene B4 (LTB4) was evaluated in colorectal biopsy specimens and resection tissue from patients with inflammatory bowel disease. The in vitro formation of LTB4 from biopsy tissues stimulated with calcium ionophore A23187 correlated with the degree of mucosal inflammation assessed at sigmoidoscopy, and with neutrophil infiltration measured as myeloperoxidase activity. Biopsy specimens from patients taking prednisolone formed less LTB4 than those from patients not on prednisolone, with comparable levels of inflammation seen at sigmoidoscopy. The formation of LTB4 was reduced dose-dependently by the acetohydroxamic acid 5-lipoxygenase inhibitor BWA4C, with no significant inhibition of prostaglandin E2 or thromboxane B2 synthesis. In inflamed colonic resection tissue from colitic patients, the IC50 for inhibition of LTB4 formation by BWA4C was 0.03 mumol/l, compared with an IC50 of 0.8 mumol/l for NDGA. Thus, BWA4C is a potent and selective inhibitor of LTB4 synthesis in colonic tissue from patients with ulcerative colitis. Acetohydroxamic acid 5-lipoxygenase inhibitors, exemplified by BWA4C, may be useful to evaluate the clinical importance of LTB4 in ulcerative colitis, and offer a novel therapy for the disease.
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PMID:Colorectal leukotriene B4 synthesis in vitro in inflammatory bowel disease: inhibition by the selective 5-lipoxygenase inhibitor BWA4C. 131 5

In this study, mediators of inflammation were characterized in colonic and terminal ileum mucosa from subjects with ulcerative colitis. We considered the role of two different chemotactic factors (interleukin-8 and leukotriene B4) and of myeloperoxidase in the pathology of inflammatory bowel disease. Serial biopsy specimens were taken at different sites, washed in 0.02 M phosphate/saline buffer, homogenized, and then sonically disrupted. In both the proximal and distal regions of the colonic mucosa of ulcerative colitis patients, there was a more than 10-fold increase in interleukin-8 levels over that in control subjects (> 300 pg/mg protein vs. 30 pg/mg protein in controls, p < or = 0.01). However, terminal ileum levels of interleukin-8 were the same in ulcerative colitis and control groups (150 pg/mg protein). There was also a 3- to 5-fold increase in leukotriene B4 levels and a several-fold increase in myeloperoxidase levels throughout the colonic mucosa in patients with ulcerative colitis. This study demonstrates that 1) interleukin-8 may have an immunoregulatory role in the pathogenesis of inflammatory bowel disease, and 2) interleukin-8, myeloperoxidase, and leukotriene B4 may be useful markers for the biochemical identification of inflammatory bowel disease.
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PMID:Interleukin-8 and neutrophil markers in colonic mucosa from patients with ulcerative colitis. 132 95

The mucosal protective prostaglandin analogs misoprostol, enisoprost, and SC-46275 (the 17E-18-cyclopentenyl analog of enisoprost) were tested in mouse and rat colitis induced by the intrarectal instillation of dilute acetic acid. Colitis was assessed by histology and colonic levels of myeloperoxidase (a neutrophil marker enzyme). When given as enemas 30 min ahead of colitis induction, 15(R)-15-methyl-PGE2 (arbaprostil) and 15(S)-15-methyl-PGE1 were inactive; however, misoprostol, enisoprost, and SC-46275 protected against colonic inflammation with ED50 values of 24, 12 and 1.3 micrograms/kg, respectively, in rats and 11, 5, and 1 micrograms/kg, respectively, in mice. These compounds may have utility in the medical management of human inflammatory bowel disease.
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PMID:Mucosal protective activity of prostaglandin analogs in rodent colonic inflammation. 133 49

Reactive oxygen metabolites (ROM) may play a role in the pathophysiology of inflammatory bowel disease (IBD) and ischemia-reperfusion-induced intestinal injury. Although there are many reports of intestinal mucosal injury associated with neutrophil-derived ROM, free radicals themselves have not been reported to induce intestinal mucosal injury. We administered intrarectally 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) to rats, an azo compound that generates free radicals in vitro. Acute mucosal injury was assessed histologically by light microscopy and biochemically by myeloperoxidase (MPO) activity. Intrarectal administration of AAPH (60, 90, 150 mg/kg) caused erythema, edema, and histologically verifiable mucosal inflammation. MPO activity was increased 9- to 18-fold above the control level. The levels of thiobarbituric acid (TBA) reactants and sulfhydryls (SH) were significantly (P less than 0.01) increased and decreased, respectively, by 90 mg/kg AAPH. Sulfasalazine, 5-aminosalicylic acid, the LTB4 receptor antagonist SC-41930, and the antioxidant glutathione prevented the inflammation. This model of mucosal inflammation may be useful in evaluating new therapeutic agents for the treatment of IBD.
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PMID:Induction of colitis in rats by 2-2'-azobis(2-amidinopropane) dihydrochloride. 134 11

Neuropeptides form a part of the brain-gut axis which may regulate gastrointestinal functions, including immune regulation. Various changes in the neuropeptides--most important, vasoactive intestinal peptide and substances P (VIP and SP)--have been described in inflammatory bowel disease. We employed a sensitive immunoperoxidase (avidin-biotin-peroxidase complex) technique, using anti-VIP and anti-SP antibodies to localize and compare the distribution of VIP and SP in the colon. Colon specimens from 19 normal subjects, eight patients with ulcerative colitis (UC), and eight with Crohn's disease (CD) were used. In the normal colon, VIP and SP immunoreactivity (IR) were localized in the muscularis mucosa, circular muscles, walls of blood vessels, nerve fibers, and some distinct cells, probably enterochromaffin cells. SP-IR was also present in the epithelial cells, mainly along the basolateral domain. VIP-IR was considerably diminished at all locations in patients with UC and CD. However, the SP-IR was increased in UC in the colonic epithelial cells along the basolateral areas. The SP-IR was intense in patients with CD, in the epithelium, the granulomas, cells lining the mucosal fissure, and in the muscle layers. In contrast to normals, SP-IR in patients with CD was observed both in the longitudinal and circular muscles. We conclude that VIP-IR and SP-IR are distributed widely in the mucosa, submucosa, and in the circular muscle in normal colon. VIP-IR is decreased in UC and CD, whereas SP-IR is increased in both, but more so in CD.
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PMID:Immunocytochemical localization of vasoactive intestinal peptide and substance P in the colon from normal subjects and patients with inflammatory bowel disease. 137 Aug 72

Serum samples from 83 patients (42 women, 41 men, mean age 41 [19-85] years) with chronic inflammatory bowel diseases (ulcerative colitis: n = 41, Crohn's disease: n = 42) of differing degrees of activity were tested for antineutrophil cytoplasmic antibodies (ANCA) by immunofluorescence microscopy and various ELISA techniques. Seven patients with ulcerative colitis and one with Crohn's disease were suffering from associated primary sclerosing cholangitis. ANCA were detected in 18 sera, 13 from patients with ulcerative colitis (31.7%) and five from patients with Crohn's disease (11.9%). Six of the eight patients with primary sclerosing cholangitis were ANCA-positive. Nine sera showed a cytoplasmic (c-ANCA-) pattern and 9 others showed a partially atypical perinuclear (p-ANCA-) pattern. Among the ANCA-positive sera, ELISA techniques showed that two had antibodies against serine proteinase 3, two against lactoferrin, two against elastase and one against myeloperoxidase. There was no correlation between the anatomical pattern or activity of the disease and the presence of ANCA. The antineutrophil cytoplasm antibodies demonstrable in chronic inflammatory bowel disease appear to be directed against so far unknown antigens. They are particularly frequent in patients with associated primary sclerosing cholangitis.
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PMID:[Antineutrophil cytoplasmic antibodies in chronic inflammatory bowel diseases]. 139 27

Antineutrophil cytoplasmic autoantibodies have been recently reported in sera from patients with inflammatory bowel disease. We report our experience based on 90 patients with ulcerative colitis, 148 patients with Crohn's disease, and 60 controls. Determination of antineutrophil cytoplasmic autoantibodies was performed by the indirect immunofluorescence technique on ethanol fixed leucocytes. The specificities for proteinase 3, myeloperoxidase, and lactoferrin were tested by enzyme-linked immunosorbent assay. Forty-three out of 90 (48%) patients with ulcerative colitis, 10 out of 148 (7%) patients with Crohn's disease, and none of controls were positive by indirect immunofluorescence technique. All patients but two with positive immunofluorescence exhibited a perinuclear staining pattern. Among patients with ulcerative colitis, there was no relationship between the presence of perinuclear antineutrophil cytoplasmic autoantibodies and disease location or activity. Seven out of 20 (35%) patients with ulcerative colitis who had a previous colectomy (including 1 with ileoanal anastomosis) had perinuclear antineutrophil cytoplasmic autoantibodies. Antineutrophil cytoplasmic autoantibody specificity was not directed against myeloperoxidase, proteinase 3 or lactoferrin in sera from patients with inflammatory bowel diseases. Inflammatory bowel diseases are associated with a new subset of antineutrophil cytoplasmic autoantibodies. Among patients with Crohn's disease and ulcerative colitis, the sensitivity and specificity of the presence of perinuclear antineutrophil cytoplasmic autoantibodies for ulcerative colitis was 46% and 93%, respectively. Their presence reinforces the likelihood of underlying immunologic dysregulation in ulcerative colitis. Identification of the autoantigen(s) to which these antibodies are directed might facilitate the understanding of inflammatory bowel disease pathophysiology.
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PMID:Antineutrophil cytoplasmic autoantibodies in inflammatory bowel diseases. 142 20

The effects of ketotifen, a 'mast cell stabiliser,' on two models of experimental colitis were examined. The inflammatory response elicited by either trinitrobenzene sulphonic acid or acetic acid resulted in increased colonic synthesis of platelet activating factor, prostaglandin E2, thromboxane B2, leukotrienes B4 and C4, and myeloperoxidase activity. Intragastric administration of ketotifen 100 micrograms/100 grams twice daily significantly decreased mucosal damage when given prophylactically 48 hours before the induction of colitis and then throughout the experiment. This effect was consistent in both models and was accompanied by a significant reduction in mucosal generation of platelet activating factor, prostaglandin E2, thromboxane B2, and leukotrienes C4 and B4. Myeloperoxidase activity was reduced as well, reaching significance only in the acetic acid model. This study shows that both trinitrobenzene sulphonic acid and acetic acid colitis can be pharmacologically manipulated by ketotifen. The mechanism of action of ketotifen has not yet been determined. Ketotifen's potential in the treatment of active inflammatory bowel disease or in the prevention of exacertations, or both, remains to be elucidated.
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PMID:Ketotifen effectively prevents mucosal damage in experimental colitis. 145 75


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