Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0009319 (colitis)
 19,384 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)-propoxy]-3,4-dihydro-8- propyl-2H-1-benzopyran-2-carboxylic acid (SC-41930), a leukotriene B4 (LTB4) receptor antagonist with anti-inflammatory activity in animal models of colitis, was evaluated for effects on superoxide, LTB4 and prostaglandin E2 production. SC-41930 inhibited human neutrophil (PMN) superoxide generation maximally stimulated by f-Met-Leu-Phe (IC50 4 microM) and C5a (IC50 approximately 12 microM). Moreover, postreceptor stimulation of superoxide production by NaF (a G protein activator), but not by phorbol myristate acetate, was significantly inhibited by SC-41930, indicating that SC-41930 may act via attenuation of a G protein-mediated signal transduction. SC-41930 also inhibited A23187-stimulated LTB4 production (IC50 5.3 microM) in human PMN as well as LTB4 (IC50 2.1 microM) and prostaglandin E2 (IC50 2.9 microM) production in HL-60 cells. When coinjected intradermally (400 micrograms/site), SC-41930 inhibited A23187-stimulated increases in LTB4 levels in guinea pig skin. SC-41930 inhibited human synovial phospholipase A2 (IC50 72 microM), A23187-stimulated 5-hydroxy-eicosatetranoic acid production in human PMN (IC50 8.5 microM), and rat peritoneal leukotriene A4 hydrolase (IC50 20 microM), but not ram seminal vesical cyclooxygenase. The results suggest that the anti-inflammatory activity of SC-41930 could be attributed to postreceptor inhibition of inflammatory mediator production by PMN and other cells in addition to antagonism of PMN LTB4 receptors.
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PMID:Multiple actions of the leukotriene B4 receptor antagonist SC-41930. 130 71

The implication of leukotrienes as mediators of inflammation and recent evidence that prostaglandin analogues provide a beneficial effect during experimental colitis led to the speculation that (i) leukotrienes may be injurious and (ii) prostaglandins may be protective to colonic mucosa. Using a 2% acetic acid induced rat colitis model, we administered specific cyclooxygenase (indomethacin) and leukotriene biosynthesis inhibitors (MK-886) to examine the effect of endogenous prostaglandins and leukotrienes on colonic macroscopic injury, mucosal inflammation as measured by myeloperoxidase activity, net in vivo intestinal fluid absorption, and colonic PGE2 and LTB4 levels as measured by in vivo rectal dialysis. Indomethacin treatment prior to induction of colitis reduced endogenous mucosal PGE2 levels and exacerbated macroscopic ulceration and net fluid absorption. Addition of the exogenous PGE1 analogue misoprostol to the indomethacin-exacerbated colitis completely healed colonic macroscopic ulceration and inflammation but only partially improved fluid absorptive injury. The specific leukotriene biosynthesis inhibitor MK-886 administered prior to induction of colitis healed macroscopic ulceration and inflammation but not fluid absorptive injury. This mucosal reparative effect of MK-886 occurred at a dose that reduced colonic LTB4 synthesis while concomitantly enhancing PGE2 levels. Combining MK-886 with misoprostol treatment improved not only macroscopic ulceration and inflammation but also provided a synergistic effect that maintained net colonic fluid absorption at noncolitic control levels. These studies suggest that, during the induction of experimental colitis, endogenous prostaglandins play a pivotal role in providing a mucosal healing effect, and that leukotriene biosynthesis inhibitor may manifest part of its beneficial effect by shifting arachidonic acid metabolism towards production of prostaglandins.
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PMID:Indomethacin worsens and a leukotriene biosynthesis inhibitor accelerates mucosal healing in rat colitis. 133 Feb 56

In rodents colitis can be induced by adding 2% (w/v) carrageenan (CARR) for 4 weeks or 10% (w/v) dextran sulphate sodium (DSS) for 7 days to their drinking water. These models are suitable to test anti-inflammatory drugs used in inflammatory bowel disease in man. Mice were treated with olsalazine (400 mg/kg body wt) starting 7 days before the DSS or CARR administration. Colonic tissues were incubated with [1-14C]-arachidonic acid and stimulated with A23187 and, thereafter, the pattern of eicosanoids was determined by separation on HPLC. DSS and CARR produced a marked diffuse inflammatory response in the colon and a subsequent 5-fold increase of all eicosanoids after DSS, whereas after CARR only a 2-fold increase of PGs was observed. Olsalazine treatment decreased all cyclooxygenase and lipoxygenase products to baseline levels.
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PMID:Experimental colitis in mice: effects of olsalazine on eicosanoid production in colonic tissue. 144 39

Arachidonic acid metabolites formed by both the cyclooxygenase and lipoxygenase pathways may contribute to the clinical diarrhea and colitis of inflammatory bowel disease. Patients with active ulcerative colitis have increased levels of leukotriene B4 in their rectal mucosa, and these levels tend to correlate with severity of the disease. In this study, we evaluated the efficacy of ingestion of fish oil n-3-omega-fatty acids, inhibitors of leukotriene synthesis, in the treatment of ulcerative colitis. Eleven patients with ulcerative colitis of mild to moderate severity were studied in a 8-month, double-blind, placebo-controlled, crossover trial of dietary supplementation with fish oil, which provided about 4.2 g of omega-3- fatty acids per day. A disease activity index based on patient symptoms and sigmoidoscopic appearance was used to assess efficacy. Mucosal leukotriene B4 production was measured by radioimmunoassay. Mean disease activity index declined 56% for patients receiving fish oil and 4% for patients on placebo (p less than 0.05). There were no statistically significant differences in histopathologic scores or colonic mucosal leukotriene B4 levels. All patients tolerated fish oil ingestion and showed no alteration in routine blood studies. No patient worsened; anti-inflammatory drugs could be reduced or eliminated in eight patients (72%) while receiving fish oil. We conclude that fish oil dietary supplementation results in clinical improvement of active mild to moderate ulcerative colitis but is not associated with significant reduction in mucosal leukotriene B4 production, compared with placebo therapy. Further studies are needed to elucidate the mechanism of action and optimal dose and duration of fish oil supplementation in ulcerative colitis.
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PMID:Fish oil fatty acid supplementation in active ulcerative colitis: a double-blind, placebo-controlled, crossover study. 155 30

The efficacy of various drugs used to treat ulcerative colitis, (sulfasalazine, 5-aminosalicylate, hydrocortisone) was investigated in a model of acetic acid-induced colitis in the rat. Subsequently, we tested the ability of antioxidant/5-lipoxygenase inhibitors (gossypol and nordihydroguiaretic acid [NDGA]) and a cyclooxygenase inhibitor (indomethacin) to attenuate the macroscopic colonic damage and/or neutrophil influx (myeloperoxidase activity [MPO]) associated with this model of colitis. Oral pretreatment with either sulfasalazine, gossypol, or NDGA significantly decreased colonic MPO activity induced by acetic acid. Intrarectal administration of such drugs resulted in an even larger reduction of the colonic inflammation, with gossypol being the most potent compound. Oral or intrarectal administration of corticosteroids (dexamethasone, hydrocortisone) also attenuated the parameters of acetic acid induced colitis. In contrast, pretreatment with indomethacin was ineffective, or when administered daily after colitis induction, indomethacin actually increased colonic neutrophil influx significantly. Our data suggest that both the route of drug administration and dosing regimen employed affect the antiinflammatory potency and/or efficacy of compounds on colitis induced by acetic acid in the rat. Drugs which were effective against this colitis may act by scavenging of oxygen derived free radicals.
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PMID:Antiinflammatory effects of various drugs on acetic acid induced colitis in the rat. 197 33

Eicosanoids are potent mediators of inflammation and are synthesized in increased quantity in active ulcerative colitis. To elucidate the role of prostaglandin E2, thromboxane A2, prostaglandin I2, and leukotriene B2 in acute chemical colitis induced by 4% acetic acid, we utilized an animal model which has a deficiency of arachidonic acid, the precursor of eicosanoids due to an essential fatty acid deficient diet. Forty-eight hours after colitis was induced, mucosal synthesis of the cyclooxygenase products, prostaglandin E2, thromboxane A2, and prostaglandin I2, was significantly decreased in essential fatty acid deficient rats compared to normal controls. However, the 5-lipoxygenase product, leukotriene B4, was not different between groups. The decrease in cyclooxygenase products did not correlate with any change in the severity of colonic inflammation as assessed by gross morphology, histology, or myleoperoxidase activity. Thus inhibition of formation of the cyclooxygenase products of arachidonate metabolism does not appear to improve the degree of inflammation under the experimental conditions employed in this study.
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PMID:The effect of essential fatty acid deficiency on eicosanoid production in the inflamed rat colonic mucosa. 217 99

Inflammatory bowel disease affects millions of people, some with fatal consequences. Little is known about the factors which contribute to its pathogenesis particularly regarding cytokine production and action. In this paper we summarize our recent findings using the rabbit model for immune complex-generated experimental colitis, a model which is similar to ulcerative colitis in humans. Recombinant human IL-1 was perfused through rabbit colons and we observed elevated levels of PGE2, TxB2 and 6-keto-PGF1 alpha, the stable metabolite of PGI2. Using radioimmunoassays specific for rabbit IL-1 alpha and IL-1 beta, we induced immune complex colitis and measured the generation of these IL-1's in various tissues. Markedly elevated levels of IL-1 were detected only in inflamed tissues. The levels of IL-1 correlated with the degree of inflammation as judged by a blinded assessment of pathological changes. Similar to other disease models in which small doses of the agonist can afford protection or result in a state of "desensitization" when administered prior to the onset of the disease, we accordingly injected rabbits with a single, small (300 ng/kg) dose of IL-1 and observed a significant reduction in the inflammatory index and necrosis of immune complex colitis. However, unlike other models of IL-1-induced protection, in this model cyclooxygenase products were required since we prevented the IL-1-induced protection with a single dose of ibuprofen given at the same time as the IL-1. This correlated with the reduction in IL-1-induced PGE2. These results demonstrate that IL-1 plays a key role in the pathogenesis of inflammatory bowel disease in the rabbit and that the protection afforded by a low dose of IL-1 24 hours before the onset of the colitis requires IL-1-induced cyclooxygenase products.
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PMID:Interleukin-1 in the pathogenesis of and protection from inflammatory bowel disease. 270 50

Human and experimental colitis are associated with release of both vasoconstrictor and vasodilator eicosanoids. To determine the pattern of colonic blood flow in vivo and the role of prostaglandins and thromboxanes, immune complex-mediated colitis and delayed hypersensitivity-mediated colitis were induced in rabbits. Organ blood flow was determined in conscious animals by radiolabeled microspheres before and after cyclooxygenase or thromboxane synthetase inhibition. Colonic blood flow was twofold higher in colitis than in control animals. Thromboxane synthetase inhibition with dazoxiben caused a slight further increase of colon perfusion in animals with colitis, but thromboxane receptor blockade had no effect. Prostaglandin inhibition with indomethacin and ibuprofen did not affect blood flow in controls, but in animals with colitis these drugs markedly reduced colonic blood flow to the level of control animals. The data demonstrate that vasodilatory prostaglandins enhance colonic blood flow in acute colon inflammation.
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PMID:Prostaglandin regulation of colonic blood flow in rabbit colitis. 294 24

We recently reported that human inflammatory bowel disease mucosa contains large amounts of leukotriene B4, a potent chemotactic agent formed from arachidonic acid through the lipoxygenase pathway. To more fully evaluate the role of arachidonic acid metabolites in the mediation of intestinal inflammation, we studied arachidonate metabolism in an animal model: acetic acid colitis in the rat. Incubation of acetic acid colitis mucosa with arachidonic acid resulted in the production of leukotriene B4 and a series of monohydroxy fatty acids, all products of the lipoxygenase pathway, plus much smaller amounts of cyclooxygenase products including prostaglandin E2. All of these metabolities were made in significantly greater quantities by mucosa from acetic acid-treated rats than by controls. The pattern of arachidonate metabolism in acetic acid colitis was strikingly similar to that in human inflammatory bowel disease. Moreover, the concentration of leukotriene B4 in acetic acid-treated mucosa was almost identical to that in human inflammatory bowel disease mucosa and was 50 times greater than that in normal rat colonic mucosa. These data indicate that lipoxygenase products, including leukotriene B4, may be important mediators of intestinal inflammation in a wide variety of inflammatory conditions. Moreover, the similarities in the metabolism of arachidonate by human inflammatory bowel disease and by acetic acid colitis may allow the use of this model, and perhaps other animal models of intestinal inflammation, in the screening of potential therapeutic agents for inflammatory bowel disease.
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PMID:Metabolism of arachidonic acid in acetic acid colitis in rats. Similarity to human inflammatory bowel disease. 391 61

Both 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and 5-hydroxyeicosatetraenoic acid (5-HETE) increased the short-circuit current (Isc) in rabbit colonic mucosa mounted in vitro in Ussing chambers. Measurements of chlorine-36 fluxes indicated that the Isc response to 5-HPETE is due to stimulation of active chlorine secretion. 9-, 11-, and 12-HPETE's and leukotrienes C4 and B4 produced either very small increases in Isc or no increase. In contrast to results in rabbit colon, no HPETE, HETE, or leukotriene was effective in rabbit ileal mucosa. The effects of 5-HPETE in the rabbit colon were unaffected by mepacrine, but could be partially blocked by indomethacin. These results suggest that drugs which block both cyclooxygenase and lipoxygenase may be effective antidiarrheals in patients with colitis.
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PMID:Stimulation of colonic secretion by lipoxygenase metabolites of arachidonic acid. 681 Apr 65


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