leukotriene-b4 and Colitis

Prostaglandins, thromboxanes, and leukotrienes (collectively called eicosanoids) are increased at sites of inflammation and contribute to the manifestations of inflammation, such as hyperemia, hyperalgesia, edema, and inflammatory cell infiltration. Inhibition of eicosanoid production is the basic mechanism of action of corticosteroids and of nonsteroidal antiinflammatory drugs. Eicosanoid synthesis is also increased in human and experimental inflammatory bowel disease. Leukotriene B4 is the most potent proinflammatory eicosanoid, and in vivo production of this compound is the predominant eicosanoid in colitis. Recent experimental data demonstrate that selective inhibition of leukotrienes may be a therapeutic strategy to reduce inflammation in inflammatory bowel disease.

Topics: Animals; Anti-Inflammatory Agents; Arachidonic Acid; Arachidonic Acids; Colitis; Colitis, Ulcerative; Humans; Leukotriene B4; Prostaglandin Antagonists; Prostaglandins; SRS-A; Thromboxanes

We investigated whether pretreatment with eicosapentaenoic acid, an inhibitor of leukotriene (LT) B4, could ameliorate acute colonic graft-versus-host disease (GVHD) after bone marrow transplantation (BMT). Seventeen patients undergoing unrelated BMT were divided into two groups, with eight patients receiving eicosapentaenoic acid and nine not receiving it. The grade of GVHD after transplantation was compared with that estimated from the pretransplantation LTB4 level. The levels of LTB4 and several cytokines were also monitored. The actual grade of GVHD was lower than that estimated from LTB4 levels in three of the eight patients from the treated group, and there was a significant difference between the treated and untreated groups (p < 0.05, chi 2 test). The levels of LTB4, tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) were all significantly lower in the treated group (p < 0.05, Student's t-test). These findings suggest that eicosapentaenoic acid may ameliorate acute colonic GVHD when administered from before BMT.

Topics: Acute Disease; Administration, Oral; Adolescent; Adult; Bone Marrow Transplantation; Chi-Square Distribution; Colitis; Eicosapentaenoic Acid; Fatty Acids, Unsaturated; Female; Graft vs Host Disease; Humans; Leukotriene B4; Male

Recent studies have suggested that heparin is effective for treatment of inflammatory bowel disease (IBD) and its various effects (in addition to the anticoagulant effect). We evaluated the effects of argatroban as an antithrombin drug on trinitrobenzene sulfonic acid (TNB)-induced colitis, an established model of IBD.. Rats were randomly assigned to four groups in which mini-osmotic pumps containing saline (TNB-S), argatroban (TNB-A), or 100 U/kg heparin (TNB-H) were intraperitoneally implanted. Three days after the pumps were implanted, TNB was infused via the anus, and colitis was induced. After 5 days, prothrombin time (PT), activated partial prothrombin time (APTT), antithrombin III (AT-III), platelet, fibrinogen, colonic wet weight, macroscopic damage score, histological score, mucosal myeloperoxidase activity and mucosal leukotrien B4 (LTB4) levels were compared among the four groups.. The APTT was prolonged in the heparin treatment group but only slightly prolonged in the argatroban treatment group. The platelet count and the fibrinogen level were higher in the TNB-S group than in the healthy control group and the AT-III level was slightly lower in the TNB-S group than in the healthy control group and lower still in the TNB-H group.. The colonic wet weight was similar among the four groups while the macroscopic damage score, histological score, mucosal myeloperoxidase activity and the mucosal LTB4 level were significantly decreased in the TNB-A and TNB-H groups. Argatroban, as well as heparin may be effective for treatment of TNB-induced colitis.

Topics: Analysis of Variance; Animals; Antithrombins; Arginine; Blood Coagulation Tests; Colitis; Disease Models, Animal; Heparin; Immunoenzyme Techniques; Infusion Pumps, Implantable; Leukotriene B4; Male; Nitrobenzenes; Peroxidase; Pipecolic Acids; Rats; Rats, Wistar; Sulfonamides; Sulfonic Acids

Topics: Adult; Aged; Aged, 80 and over; Animals; Antigens, Ly; Arachidonate 5-Lipoxygenase; Chemokine CCL2; Colitis; Colon; Down-Regulation; Female; Humans; Inflammasomes; Inflammation; Inflammatory Bowel Diseases; Interleukin-1beta; Intestines; Lectins, C-Type; Leukotriene B4; Macrophages; Male; Mannose Receptor; Mannose-Binding Lectins; Mice, Inbred C57BL; Middle Aged; Receptors, CCR2; Receptors, Cell Surface; Signal Transduction; Young Adult

Leukotriene B4 (LTB4) synthesis is enhanced in the colonic mucosa in patients with inflammatory bowel disease (IBD). BLT1, a high-affinity receptor for LTB4, exhibits no effect on the progression of dextran sodium sulfate (DSS)-induced colitis, which mostly relies on innate immunity. Here, we reported that BLT1 regulates trinitrobenzene sulfonic acid (TNBS)-induced colitis, which reflects CD4

Topics: Animals; Cell Differentiation; Cells, Cultured; Colitis; Colon; Cytokines; Dendritic Cells; Disease Models, Animal; Humans; Inflammation Mediators; Inflammatory Bowel Diseases; Leukotriene B4; Mice; Mice, Inbred C57BL; Mice, Knockout; Receptors, Leukotriene B4; Signal Transduction; Th1 Cells; Th17 Cells; Trinitrobenzenesulfonic Acid

Inflammatory bowel diseases (IBD) occurred in genetically predisposed people exposed to environmental triggers. Diet has long been suspected to contribute to the development of IBD. Supplementation with n-3 polyunsaturated fatty acids (PUFA) protects against intestinal inflammation in rodent models while clinical trials showed no benefits. We hypothesized that intervention timing is crucial and dietary fatty acid pattern may influence intestinal environment to modify inflammation genesis. The aim of this study was to evaluate the dietary effect of PUFA composition on intestinal inflammation.. Animals received diet varying in their PUFA composition for four weeks before TNBS-induced colitis. Colon inflammatory markers and gut barrier function parameters were assessed. Inflammatory pathway PCR arrays were determined.. n-3 diet significantly decreased colon iNOS, COX-2 expression, IL-6 production, and LTB4 production but tended to decrease colon TNF. Dietary n-3 PUFA influence colitis development by attenuating inflammatory markers. Further research is required to better define dietary advice with a scientific rationale.

Topics: Animals; Claudin-1; Colitis; Cyclooxygenase 2; Disease Models, Animal; Fatty Acids, Omega-3; Inflammatory Bowel Diseases; Interleukin-6; Leukotriene B4; Male; Nitric Oxide Synthase Type II; Occludin; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha

Cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) play an important role in inflammatory bowel diseases (IBDs). We investigated the effects of flavocoxid, a dual COX/LOX inhibitor, in experimental colitis induced with either dinitrobenzenesulfonic acid (DNBS) or dextrane sulphate sodium (DSS) In the first model, colitis was induced in rats by a single intra-colonic instillation (25mg in 0.8ml 50% ethanol) of DNBS; after 24h animals were randomized to receive orally twice a day, flavocoxid (10mg/kg), zileuton (50mg/kg), or celecoxib (5mg/kg). Sham animals received 0.8ml of saline by a single intra-colonic instillation. Rats were killed 4 days after induction and samples were collected for analysis. In the second model, colitis was induced in rats by the administration of 8% DSS dissolved in drinking water; after 24h animals were randomized to the same above reported treatments. Sham animals received standard drinking water. Rats were killed 5 days after induction and samples were collected for analysis. Flavocoxid, zileuton and celecoxib improved weight loss, reduced colonic myeloperoxydase activity, macroscopic and microscopic damage, and TNF-α serum levels. Flavocoxid and celecoxib also reduced malondialdheyde, 6-keto PGF1α and PGE-2 levels while flavocoxid and zileuton decreased LTB-4 levels. In addition, flavocoxid treatment improved histological features and apoptosis as compared to zileuton and celecoxib; moreover only flavocoxid reduced TXB2, thus avoiding an imbalance in eicosanoids production. Our results show that flavocoxid has protective effect in IBDs and may represents a future safe treatment for inflammatory bowel diseases.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Apoptosis; Arachidonate 5-Lipoxygenase; Body Weight; Catechin; CD3 Complex; Celecoxib; Colitis; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Dinoprostone; Drug Combinations; Eating; Gene Expression Regulation; Hydroxyurea; Leukotriene B4; Lipid Peroxidation; Lipoxygenase Inhibitors; Male; Neutrophil Infiltration; Rats; Rats, Sprague-Dawley; Thromboxane B2; Tumor Necrosis Factor-alpha

The aim of this study was to investigate the effects of the administration of oral arachidonic acid (AA) in rats with or without dextran sulphate sodium (DSS)-induced inflammatory bowel disease. Male Wistar rats were administered AA at 0, 5, 35 or 240 mg/kg daily by gavage for 8 weeks. Inflammatory bowel disease was induced by replacing drinking water with 3 % DSS solution during the last 7 d of the AA dosing period. These animals passed loose stools, diarrhoea and red-stained faeces. Cyclo-oxygenase-2 concentration and myeloperoxidase activity in the colonic tissue were significantly increased in the animals given AA at 240 mg/kg compared with the animals given AA at 0 mg/kg. Thromboxane B2 concentration in the medium of cultured colonic mucosae isolated from these groups was found to be dose-dependently increased by AA, and the increase was significant at 35 and 240 mg/kg. Leukotriene B4 concentration was also significantly increased and saturated at 5 mg/kg. In addition, AA at 240 mg/kg promoted DSS-induced colonic mucosal oedema with macrophage infiltration. In contrast, administration of AA for 8 weeks, even at 240 mg/kg, showed no effects on the normal rats. These results suggest that in rats with bowel disease AA metabolism is affected by oral AA, even at 5 mg/kg per d, and that excessive AA may aggravate inflammation, whereas AA shows no effects in rats without inflammatory bowel disease.

Topics: Animals; Arachidonic Acid; Colitis; Colon; Cyclooxygenase 2; Dextran Sulfate; Diet; Inflammation; Inflammatory Bowel Diseases; Intestinal Mucosa; Leukotriene B4; Macrophages; Male; Peroxidase; Rats, Wistar; Thromboxane B2

CYP4Fs were first identified as enzymes that catalyze hydroxylation of leukotriene B4 (LTB4). CYP4F18 has an unusual expression in neutrophils and was predicted to play a role in regulating LTB4-dependent inflammation. We compared chemotaxis of wild-type and Cyp4f18 knockout neutrophils using an in vitro assay. There was no significant difference in the chemotactic response to LTB4, but the response to complement component C5a increased 1.9-2.25-fold in knockout cells compared to wild-type (P < 0.01). This increase was still observed when neutrophils were treated with inhibitors of eicosanoid synthesis. There were no changes in expression of other CYP4 enzymes in knockout neutrophils that might compensate for loss of CYP4F18 or lead to differences in activity. A mouse model of dextran sodium sulfate colitis was used to investigate the consequences of increased C5a-dependent chemotaxis in vivo, but there was no significant difference in weight loss, disease activity, or colonic tissue myeloperoxidase between wild-type and Cyp4f18 knockout mice. This study demonstrates the limitations of inferring CYP4F function based on an ability to use LTB4 as a substrate, points to expanding roles for CYP4F enzymes in immune regulation, and underscores the in vivo challenges of CYP knockout studies.

Topics: Animals; Bone Marrow Cells; Chemokine CXCL1; Chemotaxis, Leukocyte; Colitis; Complement C5a; Cytochrome P-450 Enzyme System; Cytochrome P450 Family 4; Dextran Sulfate; Female; Gene Expression Profiling; Gene Expression Regulation; Humans; Isoenzymes; Leukotriene B4; Mice; Mice, Inbred C57BL; Mice, Knockout; Neutrophils; Peptides; Peroxidase; Primary Cell Culture; Receptors, Formyl Peptide; Weight Loss

Evidence suggests an important role of intestinal barrier dysfunction in the etiology of inflammatory bowel disease (IBD). Therefore stabilizing mucosal barrier function constitutes a new therapeutic approach in its management. Ectoine is a compatible solute produced by aerobic chemoheterotrophic and halophilic/halotolerant bacteria, where it acts as osmoprotectant and effective biomembrane stabilizer, protecting the producing cells from extreme environmental stress. Since this natural compound was also shown to prevent inflammatory responses associated with IBD, its potential usefulness was studied in a model of colitis. Groups of rats were treated orally with different doses of ectoine (30-300 mg/kg) or sulfasalazine (reference drug) daily for 11 days. On day 8 colitis was induced by intracolonic instillation of 2,4,6-trinitrobenzenesulfonic acid, when overt signs of lesions develop within the next 3 days. On day 12, blood was withdrawn from the retro-orbital plexus of the rats and the animals were sacrificed. The colon was excised and examined macroscopically and microscopically. Relevant parameters of oxidative stress and inflammation were measured in serum and colon homogenates. Induction of colitis led to marked weight loss, significant histopathological changes of the colon, and variable changes in levels of myeloperoxidase, reduced glutathione, malondialdehyde, and all inflammatory markers tested. Treatment with ectoine ameliorated the inflammatory changes in TNBS-induced colitis. This effect was associated with reduction in the levels of TNF-α, IL-1β, ICAM-1, PGE2 and LTB4. The findings suggest that intestinal barrier stabilizers from natural sources could offer new therapeutic measures for the management of IBD.

Topics: Amino Acids, Diamino; Animals; Body Weight; Colitis; Colon; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Glutathione; Intercellular Adhesion Molecule-1; Interleukin-1beta; Leukotriene B4; Male; Malondialdehyde; Rats; Rats, Wistar; Sulfasalazine; Trinitrobenzenesulfonic Acid; Tumor Necrosis Factor-alpha

Epigallocatechin-3-gallate (EGCG), atorvastatin (ATST), and their combination have been previously shown to inhibit colon carcinogenesis in animal models. We further investigated their inhibitory activities in azoxymethane (AOM) and dextran sulfate sodium (DSS)-treated Balb/cJ mice and CD-1 mice in 2 slightly different models. The mice were maintained on the AIN93M diet, or a similar diet containing 0.03%, 0.1%, or 0.3% EGCG; 60-ppm ATST; or a combination of 0.1% EGCG and 60-ppm ATST. Unexpectedly, no significant inhibitory activity was observed, and some of the treatment groups resulted in higher tumor multiplicity. To study the effects of EGCG on colon inflammation, CD-1 or C57BL/6 mice were treated with 1.5% DSS for 7 days and sacrificed 3 days later. DSS induced rectal bleeding and colon shortening; treatment with 0.5% EGCG exacerbated the bleeding and decreased mouse body weight. Dietary 0.5% EGCG also increased serum levels of leukotriene B4 and prostaglandin E2. These results suggest that, in mice bearing colon inflammation, high concentrations of EGCG and ATST enhance colon bleeding and may promote colon carcinogenesis.

Topics: Animals; Atorvastatin; Azoxymethane; Catechin; Colitis; Colon; Colonic Neoplasms; Dextran Sulfate; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Gastrointestinal Hemorrhage; Heptanoic Acids; Leukotriene B4; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Pyrroles; Rectum; Weight Loss

Leukotriene B4 (LTB(4) ) has chemotactic properties for activated T cells expressing the high-affinity receptor BLT(1) . This study investigated whether the LTB(4) antagonist (CP-105,693), selective for BLT(1) receptor, could protect mice from colitis mediated by specific cytotoxic CD8(+) T lymphocytes (CTL).. Virus-specific colitis was induced in C57Bl/6 mice transferred with lymphoid cells from P14 TcR Tg mice which are specific to class I GP33 peptide of LCMV. Mice were immunized with GP33-pulsed dendritic cells and colitis was elicited by intrarectal administration of the peptide. Colitis was evaluated by body weight loss and macroscopic and histological analysis of colon. In vivo priming of specific CD8(+) CTL was determined using interferon (IFN)-γ ELISPOT and in vivo CTL assays. In some experiments mice were treated with a selective LTB(4) receptor antagonist.. Immunization with GP33-pulsed dendritic cells (DCs) induced priming of specific CD8(+) CTL, as shown by the presence of IFN-γ-producing CD8(+) T cells in colon draining lymph nodes and in vivo CTL assays. Intrarectal challenge with GP33 induced severe colitis and recruitment of granzyme B(+) P14 CD8(+) cells in colon. Treatment with the specific LTB(4) receptor antagonist before elicitation of colitis reduced the severity of colitis and decreased the frequency of specific effectors.. Colitis can be induced by IFN-γ-producing cytotoxic CD8(+) CTL specific for viral antigen. Blockade of the LTB(4) /BLT(1) pathway by a selective BLT(1) receptor antagonist attenuates colitis by inhibiting CD8(+) effectors recruitment in colon. These data illustrate the therapeutic potential of LTB(4) receptor selective antagonists in protection from CD8(+) T-cell-mediated intestinal inflammation.

Topics: Animals; Antigens, Viral; CD8-Positive T-Lymphocytes; Cell Membrane; Chemotaxis; Colitis; Colon; Dendritic Cells; Flow Cytometry; Glycoproteins; Leukotriene B4; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Peptide Fragments; Receptors, Leukotriene B4; Signal Transduction; Viral Proteins

Aloe has been a very popular folk remedy for inflammation-related pathological conditions despite the lack of studies reporting its efficacy in vivo. The present study evaluated the anti-inflammatory effects of aloe components (aloin, aloesin and aloe-gel) known to be biologically active in the rat model of colitis.. Male Sprague Dawley rats were fed experimental diets for 2 weeks before and during the induction of colitis. Drinking water containing 3% dextran sulfate sodium (DSS) was provided for 1 week to induce colitis. At the end of the experimental period, clinical and biochemical markers were compared.. Plasma leukotriene B(4) (LTB(4)) and tumor necrosis factor-α (TNF-α) concentrations were significantly decreased in all groups supplemented with aloe components compared to the colitis control group (p<0.05). Animals fed both a 0.1% and 0.5% aloesin supplemented diet showed colonic myeloperoxidase (MPO) activities which were decreased by 32.2% and 40.1%, respectively (p<0.05). Colonic mucosa TNF-α and interleukin-1ß (IL-1β) mRNA expressions were significantly reduced in all animals fed aloin, aloesin, or aloe-gel (p<0.05).. Dietary supplementation of aloe components ameliorates intestinal inflammatory responses in a DSS-induced ulcerative colitis rat model. In particular, aloesin was the most potent inhibitor. Further studies are required for a more complete understanding of the specific mechanism of the action of these supplements.

Topics: Aloe; Animals; Anti-Inflammatory Agents, Non-Steroidal; Chromones; Colitis; Colon; Diet; Dietary Supplements; Disease Models, Animal; Emodin; Gels; Glucosides; Interleukin-1beta; Leukotriene B4; Male; Peroxidase; Plant Preparations; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha

UR-1505 is a novel pentafluoropropoxy derivative of salicylic acid, selected from a series of salicylate derivatives, according to their activity as inhibitors of T-lymphocyte activation. This study describes the anti-inflammatory activity of UR-1505 on trinitrobenzenesulphonic acid-induced colitis in rat, an experimental model that resembles to Crohn's disease (CD), as well as its in vitro effects on T-cells and bone marrow-derived macrophages (BMDM) activation. UR-1505 showed intestinal anti-inflammatory effect, associated with reduced colonic levels of TNFalpha and LTB(4), inhibition of the expression of IFNgamma and iNOS, and lower colonic leukocyte infiltration. The in vitro assays revealed that UR-1505 also inhibited T-lymphocyte proliferation and IL-12/IFNgamma production, two of the main pro-inflammatory cytokines involved in the pathogenesis of CD. However, UR-1505 did not modify LPS- nor IFNgamma-induced activation in BMDM. Thus, UR-1505 specifically affects T-cells without modifying the activation of BMDM. In conclusion, the intestinal anti-inflammatory activity of UR-1505 seems to be mediated by a reduction in the recruitment of immune cells to the inflammatory foci, together with the inhibition of T-cell activation. These results suggest that UR-1505 may be an interesting candidate to be explored for the treatment of CD.

Topics: Animals; Anti-Inflammatory Agents; Cells, Cultured; Colitis; Colon; Crohn Disease; Disease Models, Animal; Female; Glutathione; Interferon-gamma; Leukotriene B4; Macrophages; Mice; Mice, Inbred BALB C; Nitric Oxide Synthase Type II; Rats; Rats, Wistar; Salicylates; Spleen; T-Lymphocytes; Trinitrobenzenesulfonic Acid; Tumor Necrosis Factor-alpha

Cysteinyl leukotrienes play a part in inflammatory processes such as inflammatory bowel diseases. The present study aimed to evaluate the effects of the cys-LT-1 receptor antagonist montelukast on a mild colitis model in rats. Colitis was induced by administrating 4% dextran sulphate sodium (DSS, MW 45,000) in drinking water for 9 days. Montelukast (10 mg/kg/day) or vehicle was given by gastric gavage once daily simultaneously with DSS administration. A healthy control group receiving water as drinking fluid and vehicle by gastric gavage was included. Body weight loss, consistency of faeces (loose/diarrhoea) and occult blood in the faeces/ gross bleeding were assessed on days 6 - 9. After sacrifice, the following were assessed: colonic histology, the expression of inducible nitric oxide synthase, macrophage/monocyte marker ED1, cyclooxygenase-1 and cyclooxygenase-2, as well as the production of leukotriene B(4) and E(4), prostaglandin E(2), its metabolite bicyclic-prostaglandin E(2) and thromboxane B(2) in the colonic tissue incubation in vitro. Rats receiving DSS exhibited bloody diarrhoea from day 6 onwards. Montelukast significantly reduced the occult blood in the faeces/ gross bleeding, maintained normal body weight gain and tended to decrease the ratio of leukotriene B(4)/ prostaglandin E(2) production in the colon in vitro. The results indicate that montelukast has some potential to ameliorate mild experimental colitis induced by DSS.

Topics: Acetates; Administration, Oral; Animals; Blotting, Western; Body Weight; Bridged Bicyclo Compounds; Colitis; Colon; Cyclooxygenase 1; Cyclooxygenase 2; Cyclopropanes; Dextran Sulfate; Dinoprostone; Immunochemistry; Immunoglobulin G; Leukotriene Antagonists; Leukotriene B4; Male; Nitric Oxide Synthase Type II; Occult Blood; Quinolines; Rats; Rats, Wistar; Severity of Illness Index; Sulfides; Thromboxane B2

Inflammatory bowel disease is associated with intestinal oxidative stress. In the present study we test the preventative effect of Lactobacillus fermentum, a probiotic that produces per se glutathione, in the trinitrobenzenesulphonic acid (TNBS) model of rat colitis.. Colitis was induced in rats by intracolonic administration of 10 mg of TNBS dissolved in 0.25 ml of 50% ethanol. L. fermentum was administered orally (5x10(8) CFU suspended in 0.5 ml of skim milk) to a group of rats for 3 weeks, starting 2 weeks before colitis induction. Colonic damage was evaluated both histologically and biochemically, and the colonic luminal contents were used for bacterial studies as well as for short chain fatty acid (SCFA) production.. L. fermentum treatment resulted in an amelioration of the inflammatory response in colitic rats as evidenced histologically and by a significant reduction of colonic MPO activity (P<0.05). The probiotic partially counteracted the colonic glutathione depletion induced by the inflammatory process. In addition, probiotic-treated colitic rats showed significant lower colonic tumour necrosis factor (TNF)alpha levels (P<0.01) and inducible nitric oxide synthase (iNOS) expression when compared to non-treated rats. Finally, the probiotic induced growth of Lactobacilli species and production of SCFA in colonic contents in comparison with control colitic rats.. Administration of the probiotic L. fermentum facilitates the recovery of the inflamed tissue in the TNBS model of rat colitis, an effect associated with increased levels of glutathione as well as with amelioration of the production of some of the mediators involved in the inflammatory response of the intestine, such as TNFalpha and NO.

Topics: Analysis of Variance; Animals; Colitis; Colony Count, Microbial; Disease Models, Animal; Fatty Acids, Volatile; Female; Glutathione; Inflammation Mediators; Intestinal Mucosa; Leukotriene B4; Limosilactobacillus fermentum; Neutrophil Infiltration; Nitric Oxide Synthase Type II; Oxidative Stress; Peroxidase; Probiotics; Rats; Rats, Wistar; Trinitrobenzenesulfonic Acid; Tumor Necrosis Factor-alpha

Omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) are the precursors of potent lipid mediators and play an important role in regulation of inflammation. Generally, n-6 PUFA promote inflammation whereas n-3 PUFA have antiinflammatory properties, traditionally attributed to their ability to inhibit the formation of n-6 PUFA-derived proinflammatory eicosanoids. Newly discovered resolvins and protectins are potent antiinflammatory lipid mediators derived directly from n-3 PUFA with distinct pathways of action. However, the role of the n-3 PUFA tissue status in the formation of these antiinflammatory mediators has not been addressed. Here we show that an increased n-3 PUFA tissue status in transgenic mice that endogenously biosynthesize n-3 PUFA from n-6 PUFA leads to significant formation of antiinflammatory resolvins and effective reduction in inflammation and tissue injury in colitis. The endogenous increase in n-3 PUFA and related products did not decrease n-6 PUFA-derived lipid mediators such as leukotriene B4 and prostaglandin E2. The observed inflammation protection might result from decreased NF-kappaB activity and expression of TNFalpha, inducible NO synthase, and IL-1beta, with enhanced mucoprotection probably because of the higher expression of trefoil factor 3, Toll-interacting protein, and zonula occludens-1. These results thus establish the fat-1 transgenic mouse as a new experimental model for the study of n-3 PUFA-derived lipid mediators. They add insight into the molecular mechanisms of inflammation protection afforded by n-3 PUFA through formation of resolvins and protectins other than inhibition of n-6 PUFA-derived eicosanoid formation.

Topics: Animals; Colitis; Dinoprostone; Eicosanoids; Fatty Acids, Omega-3; Inflammation; Leukotriene B4; Lipids; Mass Spectrometry; Mice; Mice, Inbred C57BL; Mice, Transgenic; Models, Chemical; NF-kappa B; Ultraviolet Rays

Lactulose is a drug used as a laxative that has been shown to promote the growth of lactobacilli and bifidobacteria, acting as a prebiotic and with a potential beneficial effect in inflammatory bowel disease. The present study describes the preventive antiinflammatory activity of lactulose in the trinitrobenzenesulphonic acid (TNBS) model of rat colitis.. Rats were rendered colitic by a colonic instillation of 10 mg of TNBS dissolved in 0.25 mL of 50% ethanol. One group of colitic rats received lactulose, which was incorporated in the drinking water (2.5% wt/vol) for 2 weeks before TNBS instillation, and colonic damage was evaluated 1 week after colitis induction. Different biochemical markers of colonic inflammation were assayed: myeloperoxidase activity, glutathione content, tumor necrosis factor alpha, leukotriene B4 levels, and colonic inducible nitric oxide synthase expression. In addition, bacterial counts (for lactobacilli and bifidobacteria) were performed in colonic contents from colitic rats.. The results show that lactulose exerted a preventive antiinflammatory effect in this model of rat colitis, as evidenced by a significant reduction of myeloperoxidase activity and by a decrease of both colonic tumor necrosis factor alpha and leukotriene B4 production. This effect was also characterized by an inhibition of colonic inducible nitric oxide synthase expression, which is unregulated as a consequence of the inflammatory status. This beneficial effect was associated with increased levels of lactobacilli and bifidobacteria species in colonic contents in comparison with untreated colitic rats.. In conclusion, the intestinal antiinflammatory effect of lactulose could be related to its prebiotic properties, supporting its potential use in human inflammatory bowel disease.

Topics: Animals; Colitis; Disease Models, Animal; Female; Gastrointestinal Agents; Lactobacillaceae; Lactulose; Leukotriene B4; Peroxidase; Rats; Rats, Wistar; Trinitrobenzenesulfonic Acid; Tumor Necrosis Factor-alpha

Neutrophil elastase (NE) is a factor that aggravates colitis. We investigated the influence of thromboxane A2 (TXA2) and leukotriene B4 (LTB4) on NE release in Syrian hamsters with trinitrobenzene sulfonic acid-induced colitis. Colonic specimens with colitis were incubated with U-46619 (a TXA2 analogue) or LTB4 in vitro and NE release was examined. As a result, U-46619 increased NE release, while LTB4 had no effect. The NE release induced by U-46619 was inhibited by a TP-receptor antagonist. To demonstrate that TXA2 caused NE release in vivo as well, while LTB4 did not, colitis animals were treated with nordihydroguaiaretic acid (NDGA), a dual inhibitor of cyclooxygenase/lipoxygenase; and colonic luminal TXB(A)2 and LTB4 levels and NE activity were determined. The TXB(A)2 level was significantly correlated with NE activity, while no correlation was found between LTB4 and NE activity. An inhibitory effect of NDGA on the ulcer area was also observed, and NE activity was significantly correlated with the ulcer area. The suppression of TXA2 production by NDGA may result in the inhibition of NE release so that colonic tissue damage becomes less severe. Regulation of NE release is a new biological action of TXA2 that has not been reported before.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Colitis; Cricetinae; Disease Models, Animal; Leukocyte Elastase; Leukotriene B4; Male; Mesocricetus; Specific Pathogen-Free Organisms; Thromboxane A2; Trinitrobenzenesulfonic Acid; Up-Regulation

The use of radiolabeled leukocytes is considered the gold standard for scintigraphic imaging of inflammatory bowel disease. The disadvantages of (99m)Tc-hexamethylpropyleneamine oxime (HMPAO)-leukocytes, however, encourage the search for new imaging agents with at least similar diagnostic accuracy but without the laborious preparation and subsequent risk of contamination. In this study we investigated the imaging characteristics of a new imaging agent that specifically binds to the leukotriene B(4) (LTB(4)) receptors expressed on neutrophils. Imaging characteristics of the (111)In-labeled LTB(4) antagonist (DPC11870) were compared with those of (18)F-FDG and (99m)Tc-HMPAO-granulocytes in a rabbit model of experimental colitis.. Acute colitis was induced in New Zealand White (NZW) rabbits by infusion of trinitrobenzene sulfonic acid in the descending colon. Forty-eight hours after induction of colitis, all animals were injected intravenously with (99m)Tc-granulocytes, (18)F-FDG, or (111)In-DPC11870. The pharmacokinetics and biodistribution were studied by serial scintigraphic imaging and by ex vivo counting of dissected tissues.. All 3 radiopharmaceuticals showed the inflamed colon as early as 1 h after injection. However, compared with (99m)Tc-granulocytes, both (111)In-DPC11870 and (18)F-FDG were superior in revealing the inflamed lesions. The biodistribution data showed that uptake of (111)In-DPC11870 in the inflamed colon was highest (0.72 +/- 0.18 percentage injected dose per gram [%ID/g]), followed by uptake of (99m)Tc-granulocytes (0.40 +/- 0.11 %ID/g) and of (18)F-FDG (0.16 +/- 0.04 %ID/g). Because of low activity concentrations in the noninflamed colon, the radiolabeled LTB(4) antagonist also revealed the highest ratio of affected colon to unaffected colon (11.6 for (111)In-DPC11870, 5.5 for (99m)Tc-granulocytes, and 4.1 for (18)F-FDG).. The radiolabeled LTB(4) antagonist DPC11870 clearly delineated acute colitis lesions in NZW rabbits within 1 h after injection. Because of high uptake in the inflamed lesions and a low activity concentration in the noninflamed colon, images acquired with (111)In-DPC11870 were better than those acquired with (99m)Tc-granulocytes or (18)F-FDG.

Topics: Animals; Biphenyl Compounds; Colitis; Female; Fluorodeoxyglucose F18; Granulocytes; Isotope Labeling; Leukotriene B4; Neutrophils; Oligopeptides; Organ Specificity; Pyridines; Rabbits; Radionuclide Imaging; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tetrazoles; Tissue Distribution; Whole-Body Counting

1. Diosmectite is a natural silicate effectively used in the treatment of infectious diarrhoea. Its antidiarrhoeal properties involve adsorption of toxins and bacteria and modifications of the rheological characteristics of gastrointestinal mucus. Hence, the aim of this study was to test the intestinal anti-inflammatory activity of diosmectite. 2. Diosmectite (500 mg x kg(-1) day(-1), p.o.) was administered as a post-treatment to rats with chronic trinitrobenzene sulphonic acid colitis. Colonic status was checked 1 and 2 weeks after colitis induction by macroscopic, histological and biochemical examination. 3. Diosmectite post-treatment resulted in amelioration of the morphological signs (intestinal weight, macroscopic damage, necrosed area, histology) and biochemical markers (myeloperoxidase activity, glutathione levels, MUC2 expression, inducible nitric oxide synthase and interleukin-1beta (IL-1beta) and leukotriene B(4) synthesis), as well as in the reduction of the severity of diarrhoea. The effect of the clay was comparable to that of sulphasalazine (50 mg x kg(-1) day(-1)). 4. 5. Diosmectite exhibited a dose-dependent capacity to adsorb proteins in vitro as well as a dose-dependent inhibitory effect on the basolateral secretion of IL-8 by lipopolysaccharide (LPS)-stimulated HT29 cells. Diosmectite had a dose-dependent inhibitory effect on IL-1beta production by LPS-stimulated THP-1 cells. 6. The effect of diosmectite on MUC2 was post-transcriptional, since mRNA levels were unaffected. However, diosmectite is able to upregulate MUC2 mRNA levels in HT29-MTX cells. 7. Diosmectite has anti-inflammatory activity administered as a post-treatment. Possible mechanisms include adsorption of luminal antigens, increase of colonic mucin levels and possibly a direct modulatory action of cytokine production by mucosal cells.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cell Line; Colitis; Cytokines; Disease Models, Animal; Female; Glutathione; Glycoproteins; Haptens; Humans; Interleukin-1; Interleukin-1beta; Intestinal Mucosa; Leukotriene B4; Mucins; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Peptide Fragments; Rats; Rats, Wistar; Silicates; Trinitrobenzenesulfonic Acid

Quercitrin, 3-rhamnosylquercetin, is a bioflavonoid with antioxidant properties, which exerts anti-inflammatory activity in experimental colitis. In the present study, different in vivo experiments were performed in order to evaluate the mechanisms of action involved in this effect, with special attention to its effects on proinflammatory mediators, including nitric oxide (NO). Experimental colitis was induced in female Wistar rats by incorporation of dextran sodium sulfate (DSS) in drinking water. Oral treatment of quercitrin (1 or 5 mg kg(-1) day(-1)) to colitic rats ameliorated the evolution of the inflammatory process induced when administered in a preventative dosing protocol. When quercitrin (1 mg kg(-1) day(-1)) was administered on established colitis, it facilitated the recovery of the inflamed mucosa. The beneficial effects exerted by quercitrin were evidenced both histologically and biochemically, and were associated with an improvement in the colonic oxidative status, altered as a consequence of the colonic insult induced by DSS. In addition, a reduction of colonic NO synthase activity was observed, probably related to a decreased expression in the inducible form of the enzyme via downregulation in the colonic activity of the nuclear factor-kappaB. Immunohistochemical studies showed that quercitrin treatment reduced macrophage and granulocyte infiltration in the inflamed tissue.

Topics: Alkaline Phosphatase; Animals; Anti-Inflammatory Agents; Blotting, Western; Colitis; Colon; Dextran Sulfate; Enzyme Inhibitors; Female; Fluorescent Antibody Technique; Glutathione; Intestinal Mucosa; Leukotriene B4; Macrophage Activation; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Peroxidase; Quercetin; Rats; Rats, Wistar

Although a dextran sodium sulfate (DSS)-induced colitis is commonly used as an ulcerative colitis (UC) model in adult rodents, there are no studies using this model in young animals. We examined differences in the severity of DSS-induced colitis as a function of the concentration of DSS administered and sought to establish a DSS-induced colitis model in young rats.. We administrated different concentrations of DSS solution (2%, 3%, and 4%) to 4-week-old weanling rats and compared their clinical findings, colonic histologic findings, mucosal leukotriene B4 (LTB4) production, and mucosal blood flow with control weanling rats and 8-week-old adult rats given 4% DSS for induced colitis.. Clinical symptoms, such as diarrhea and rectal bleeding, histologic findings, and disturbance of mucosal microcirculation in weanling rats given 4% DSS were significantly more severe than those in adult rats given the same treatment. Three of 10 rats given 2% DSS had no bloody stool and 2 of 10 rats given 4% DSS died during the experimental periods. Clinical symptoms, hemoglobin levels, histologic damage scores, mucosal LTB4 production, and mucosal blood flow became more severely deranged as the concentration of DSS increased from 2% to 4%.. These findings suggest that we can adjust disease severity in UC model for young children by giving different concentrations of DSS to weanling rats.

Topics: Aging; Animals; Colitis; Colon; Dextran Sulfate; Diarrhea; Disease Models, Animal; Dose-Response Relationship, Drug; Gastrointestinal Hemorrhage; Intestinal Mucosa; Leukotriene B4; Male; Rats; Rats, Wistar; Weaning

The molecular mechanisms underlying inflammatory bowel diseases (IBD) are incompletely characterized. MRP-1, normally expressed in the large and small bowel epithelium, serves as a multidrug resistance protein. In this report we explored the role of MRP1 in IBD. Mrp1-deficient mice (mrp1-/-) were subjected to two different models of IBD. The mrp1-/- mice and wild-type (WT) mice showed equal induction of TNBS colitis, a hapten-induced T-cell mediated disease. However, in DSS colitis more severe disease was observed in mrp1-/- mice. In a survival study, mortality of mrp1-/- mice was higher. In nonlethal DSS colitis, the mean histological colitis score was significantly higher in mrp1-/- mice and showed particularly severe epithelial damage. Although endogenous LTB4 levels were significantly increased in mrp1-/- mice, treatment with a LTB4 antagonist did not reduce disease. We conclude that MRP-1 has an important role in the intestinal epithelial resistance to exogenous injury, but MRP-1 does not affect T-lymphocyte mediated mucosal damage.

Topics: Animals; ATP Binding Cassette Transporter, Subfamily B, Member 1; Colitis; Colon; Dextran Sulfate; Leukotriene B4; Leukotriene C4; Mice; T-Lymphocytes; Trinitrobenzenesulfonic Acid

Clinical and experimental findings had indicated that cigarette smoke exposure, and cyclooxygenase-2, are strongly associated with inflammatory bowel disease. The present study aimed to evaluate the role of cyclooxygenase-2 in the pathogenesis of experimental inflammatory bowel disease as well as in the adverse action of cigarette-smoke exposure. Rats were pretreated with different cyclooxygenase-2 inhibitors (indomethacin, nimesulide, or SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide)) along with cigarette-smoke exposure before 2,4,6-trinitrobenzenesulfonic acid-enema. Results indicated that pretreatment with cyclooxygenase-2 inhibitors not only protected against 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also attenuated the potentiating effect of cigarette-smoke exposure on colonic damage. Furthermore, the colonic cyclooxygenase-2 protein and mRNA expression was markedly induced by 2,4,6-trinitrobenzenesulfonic acid-enema, and it was potentiated further by cigarette-smoke exposure, while the cyclooxygenase-1 expression was not changed. The present study suggests that the highly induced cyclooxygenase-2 expression not only plays a pathogenic role in 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also contributes to the adverse action of cigarette-smoke exposure on this disorder.

Topics: Animals; Blotting, Western; Colitis; Colon; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Gene Expression Regulation, Enzymologic; Indomethacin; Inflammation; Inflammatory Bowel Diseases; Isoenzymes; Leukotriene B4; Male; Membrane Proteins; Peroxidase; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sulfonamides; Tobacco Smoke Pollution; Trinitrobenzenesulfonic Acid

Cysteinyl leukotrienes play a part in inflammatory reactions such as inflammatory bowel diseases. The aim of the present study was to evaluate the acute effects of a cys-leukotriene-1 receptor antagonist, montelukast, on trinitrobenzene sulphonic acid (TNBS)-induced colitis in rats. Montelukast (5, 10 or 20 mg kg(-1) day(-1)), a 5-lipoxygenase inhibitor, zileuton (50 or 100 mg kg(-1) day(-1), a positive control), or the vehicle was administered intracolonically to the rats twice daily throughout the study, starting 12 h before the induction of colitis with TNBS. The severity of colitis (macroscopic and histological assessment, as well as myeloperoxidase activity), the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2, and eicosanoid production in colonic tissue incubation were assessed 24 and 72 h after colitis induction. Montelukast increased prostaglandin E(2) production at 24 h and tended to reduce the cyclooxygenase-2 protein expression at 72 h, but did not influence the severity of colitis. Zileuton failed to decrease the inflammatory reaction in spite of reduced leukotriene B(4) production at 72 h. The results suggest that drugs that block cysteinyl leukotriene receptors have limited potential to ameliorate acute TNBS-induced colitis, but that they exert some beneficial effects which make them capable of modulating the course of colitis.

Topics: Acetates; Animals; Colitis; Cyclooxygenase 2; Cyclopropanes; Isoenzymes; Leukotriene Antagonists; Leukotriene B4; Male; Membrane Proteins; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Prostaglandin-Endoperoxide Synthases; Quinolines; Rats; Rats, Wistar; Receptors, Leukotriene; Severity of Illness Index; Sulfides

Morin, a bioflavonoid with antioxidant properties, shows intestinal anti-inflammatory activity in the acute phase of the trinitrobenzenesulphonic acid model of rat colitis.. To assess the anti-inflammatory activity of morin in the chronic stages of trinitrobenzenesulphonic acid-induced rat colitis.. Rats were rendered colitic by a single colonic instillation of 30 mg of the hapten trinitrobenzenesulphonic acid dissolved in 0.25 mL of 50% ethanol. A group of colitic animals was given morin orally at doses of 25 mg/kg daily. Animals were sacrificed every week for 4 weeks. Colonic damage was evaluated macroscopically and microscopically. Different biochemical markers of colonic inflammation were also assayed, including myeloperoxidase activity, leukotriene B4 and interleukin-1beta synthesis, glutathione and malonyldialdehyde levels and nitric oxide synthase activity.. The administration of morin facilitated tissue recovery during the 4 weeks following colonic insult with trinitrobenzenesulphonic acid, as demonstrated macroscopically and microscopically, as well as biochemically by a reduction in myeloperoxidase activity. The intestinal anti-inflammatory effect of morin was accompanied by a significant reduction in colonic leukotriene B4 and interleukin-1beta levels, improvement in colonic oxidative stress and inhibition of colonic nitric oxide synthase activity.. Morin exerts a beneficial anti-inflammatory effect in the chronic phase of trinitrobenzenesulphonic acid-induced rat colitis through the down-regulation of some of the mediators involved in the intestinal inflammatory response, including free radicals, cytokines, leukotriene B4 and nitric oxide.

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antioxidants; Chronic Disease; Colitis; Disease Models, Animal; Female; Flavonoids; Interleukin-1; Intestinal Mucosa; Leukotriene B4; Nitric Oxide; Nitric Oxide Synthase; Peroxidase; Rats; Rats, Wistar; Trinitrobenzenesulfonic Acid

D-002 is a natural mixture of higher aliphatic primary alcohols purified from beeswax and has experimentally proven mild antiinflammatory and effective antiulcer effects. It reduces leukotrienes in the exudate of carrageenan-induced pleurisy and has a protective effect on the preulcerative phase of carrageenan-induced colonic ulceration in the guinea pig. This study was conducted to compare the effect of D-002 and sulfasalazine on acetic acid-induced colitis in rats administered at 1, 5.25 and 100 mg kg-1, 24 h before colitis induction. Significant reductions in wet weight, macroscopic injury, polymorphonuclear infiltration and wall thickness were observed in the colonic mucosa of D-002 and sulfasalazine-treated animals compared with controls, except at the dose of 1 mg kg-1. It was concluded that the effects of D-002 and sulfasalazine were comparable in this experimental model.

Topics: Acetic Acid; Animals; Colitis; Fatty Alcohols; Leukotriene B4; Male; Neutrophils; Rats; Rats, Sprague-Dawley; Sulfasalazine

The pathophysiology of enterohaemorrhagic Escherichia coli (EHEC) infection remains unclear. Eicosanoids have been implicated as pathophysiological mediators in other colitides.. To determine if prostaglandin E(2) (PGE(2)) and leukotriene B(4) (LTB(4)) contribute to mucosal inflammation and dysfunction in EHEC colitis.. Ten day old rabbits were infected with EHEC. For five days after infection, mucosal synthesis of PGE(2) and LTB(4) was measured in distal colonic tissue from control and infected animals and (51)Cr-EDTA permeability was assessed in vivo. Myeloperoxidase activity was measured and histological inflammation and damage were assessed at five days in control and infected animals and after treatment of infected animals with the LTB(4) synthesis inhibitor MK-886. In separate experiments, ion transport was measured in Ussing chambers, before and after in vitro addition of the cyclooxygenase inhibitor indomethacin.. LTB(4) synthesis was increased from day 2 after infection onwards and PGE(2) synthesis was increased on day 3. Mucosal permeability did not increase until day 5 after infection. MK-886 inhibited colonic LTB(4) production but did not reduce diarrhoea, inflammation, or mucosal damage. Electrolyte transport was not significantly altered on day 3 after infection. However, both Cl secretion and reduced Na absorption found on day 5 were partially reversed by indomethacin.. Tissue synthesis of PGE(2) and LTB(4) did not correlate temporally with EHEC induced inflammation or changes in mucosal permeability and ion transport. Cyclooxygenase inhibition partially reversed ion transport abnormalities but lipoxygenase inhibition did not affect mucosal inflammation or histological damage. We conclude that the contribution of eicosanoids to mucosal injury and dysfunction is more complex than previously suggested.

Topics: Animals; Colitis; Dinoprostone; Disease Models, Animal; Eicosanoids; Electrolytes; Escherichia coli Infections; Gastric Mucosa; Gastrointestinal Hemorrhage; Indoles; Leukotriene B4; Lipoxygenase Inhibitors; Permeability; Rabbits

Phospholipase D (PLD) hydrolyzes phosphatidylcholine and produces lipid second messengers. Although cellular PLD has recently been recognized as an important signal-transmitting enzyme, the role of PLD in pathophysiologic conditions is largely unknown. In particular, the regulation of PLD in intestinal inflammation has not been previously investigated. The aim of the present study was to elucidate the role of PLD in experimental colitis.. Rats were intracolonically administered acetic acid and assessed for mucosal damage, mucosal PLD activity, mucosal myeloperoxidase activity, mucosal chemiluminescence and luminal concentration of leukotriene B4. Acetic acid treatment induced acute mucosal injury that was maximal at 24 h after treatment.. Mucosal PLD activity was significantly elevated and correlated with mucosal damage. Chemiluminescence in colitic mucosa was inhibited by the addition of ethanol which suppresses the formation of phosphatidic acid catalyzed by PLD.. These results suggest that PLD is activated in experimental colitis in rats and that PLD may play a role in mucosal damage induced by reactive oxygen metabolites.

Topics: Acetates; Acute Disease; Animals; Central Nervous System Depressants; Colitis; Colon; Data Interpretation, Statistical; Disease Models, Animal; Enzyme Activation; Ethanol; Female; Immunoenzyme Techniques; Intestinal Mucosa; Leukotriene B4; Luminescent Measurements; Peroxidase; Phospholipase D; Phospholipids; Rats; Rats, Wistar; Time Factors

It has been reported that zinc sulphate contributes an anti-inflammatory action in many animal models; however, the impact of zinc in colitis remains unclear. The aim of the present study was to examine the role of zinc sulphate in experimental colitis.. Colitis was induced by 2,4,6-trinitrobenzenesulphonic acid (TNB) in rats. Beginning at the first day of TNB colitis, the rats were treated with a zinc sulphate enema once daily for 6 days. The rats were examined 8 days later.. The TNB induced severe colitis as evidenced by increased mucosal lesion area, mucosal myeloperoxidase (MPO) activity and prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) levels. Six days after the application of the zinc sulphate enema, the mucosal lesion area, MPO activity, PGE2 and LTB4 levels all decreased significantly. Mucosal superoxide dismutase activity remained unchanged after zinc treatments.. Our data suggest that zinc sulphate enemas have an anti-inflammatory action on experimental colitis.

Topics: Animals; Colitis; Dinoprostone; Disease Models, Animal; Enema; Female; Intestinal Mucosa; Leukotriene B4; Peroxidase; Rats; Rats, Sprague-Dawley; Superoxide Dismutase; Zinc Sulfate

Neutrophils have been implicated as major contributors to tissue injury in inflammatory bowel disease. In this study, we have assessed the effects of an inhibitor of neutrophil activation and adherence, NPC-18915 (4-¿2-[2-(2-benzofuranyl)phenyl]-(E)-ethenyl¿benzoic acid sodium salt), in models of both acute and reactivated colitis. Acute colitis was induced by intracolonic administration of a hapten. In other rats, colitis was reactivated 6 wk after a bout of acute colitis by subcutaneous administration of the hapten. NPC-18915 given during the first 4 days after induction of acute colitis significantly reduced tissue injury and the incidence of diarrhea and adhesions. When treatment of NPC-18915 was initiated after colitis was firmly established (48 h posthapten), it did not produce a significant effect. NPC-18915 was effective at significantly reducing colonic injury and granulocyte infiltration in the reactivated colitis model, and a similar effect could be observed in rats treated with antineutrophil serum. These results demonstrate that an inhibitor of neutrophil activation is effective in both acute and reactivated colitis, although in the former case, effectiveness is only seen when the drug is given before full establishment of colitis. These results also suggest that neutrophils, are a critical effector cell of hapten-induced colitis in the rat, particularly in the case of reactivated colitis.

Topics: Acute Disease; Animals; Benzoates; Benzofurans; Colitis; Colon; Ferric Compounds; Immunization, Passive; Leukocyte Count; Leukotriene B4; Male; Neutrophils; Rats; Rats, Wistar; Recurrence; Regional Blood Flow

The flavonoid morin was tested for anti-inflammatory activity in trinitrobenzenesulfonic acid (TNBS)-induced rat colitis. Rats were pretreated orally with several doses of the flavonoid (5, 10, 25, 100 and 200 mg/kg) 48, 24 and 1 h before and 24 h after colitis induction and examined for colonic damage 48 h after colitis induction. Colonic inflammation was characterized by diffuse hemorrhagic necrosis of the mucosa, bowel wall thickening, impairment of fluid absorption, increase in myeloperoxidase (MPO) activity, enhanced leukotriene B4 (LTB4) synthesis, glutathione depletion and increased levels of malonyldialdehyde (MDA). Morin treatment, at doses ranging from 10 to 200 mg/kg, significantly reduced colonic macroscopic damage. This beneficial effect was also confirmed by inhibition of colonic MPO activity. Several mechanisms may contribute to the protective effect exerted by morin. First, inhibition of colonic LTB4 synthesis is a common feature for all the active doses of the flavonoid. Second, the antioxidant properties of morin, which partially prevented colonic glutathione depletion (at doses of 10 and 25 mg/kg) or inhibited colonic MDA production (at doses of 100 and 200 mg/kg), can collaborate in preventing TNBS-induced inflammation.

Topics: Acute Disease; Administration, Oral; Animals; Antioxidants; Colitis; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Flavonoids; Leukotriene B4; Malondialdehyde; Rats; Rats, Wistar; Trinitrobenzenesulfonic Acid

Smoking, probably due to nicotine, has a bivalent effect on inflammatory bowel disease, ameliorating disease activity in ulcerative colitis and with a deleterious effect on Crohn's disease. The effect of nicotine patches in ulcerative colitis is controversial.. To investigate the effect of chronic nicotine use in a rat model of colitis.. Colitis was induced in Sprague-Dawley rats by rectal administration of 30 mg trinitrobenzene sulphonic acid (TNBS) in 50% ethanol. Nicotine was dissolved in drinking water (2.5, 12.5, 25 and 250 microg/ml), with rats drinking ad libitum. Nicotine administration started 10 days prior to damage induction and had no effect on weight gain or daily food intake of rats. Rats were sacrificed 1 and 5 days after TNBS administration, their colons resected, rinsed, weighed, damage assessed macroscopically (mm2) and microscopically and tissue processed for myeloperoxidase (MPO) and nitric oxide synthase (NOS) activities, leukotriene B4 (LTB4), prostaglandin E2 (PGE2) generation and interleukin-1 (IL-1) serum levels.. Nicotine, by itself, caused no damage to the colon. Nicotine had a dose-dependent bivalent effect on colitis, significantly reducing macroscopic damage from 983 +/- 10 mm2 on TNBS alone to 429 +/- 118 mm2 on TNBS plus 12.5 microg/ml of nicotine, and escalating to 1086 +/- 262 mm2 on 250 microg/ml of nicotine. Segmental weight declined significantly (from 2.4 +/- 0.2 to 1.65 +/- 0.20 g/10 cm), on 12.5 microg/ml nicotine, as did MPO activity (from 3.2 +/- 0.4 to 0.7 +/- 0.1 units/g). All these parameters returned to the levels of TNBS alone when the dose of nicotine was increased to 250 microg/ml. Nicotine had no effect on NOS activity, PGE2 generation and serum IL-1 levels, but increased LTB4 generation.. Nicotine has a dose-dependent bivalent effect on TNBS-induced colitis which is not due to reduction in IL-1 serum levels or PGE2 generation, and is not NOS-mediated.

Topics: Animals; Colitis; Colon; Dinoprostone; Dose-Response Relationship, Drug; Interleukin-1; Intestinal Mucosa; Leukotriene B4; Male; Nicotine; Nitric Oxide Synthase; Peroxidase; Rats; Rats, Sprague-Dawley; Trinitrobenzenesulfonic Acid

There is crucial evidence that leukotrienes are significant mediators of inflammation in inflammatory bowel diseases (IBD). Thus, selective inhibition of leukotriene synthesis is believed to provide a novel approach to therapy of IBD. The aim of the study is to study the efficacy of a potent 5-lipoxygenase activating protein inhibitor (FLAP), BAY y 1015 in a dextran sulfate model of mouse colitis.. Outbred female mice weighing approximately 25 grams were used to produce acute or chronic colitis by feeding 5% dextran sulfate in drinking water.. Colitic mice were treated with placebo (3% starch suspension, 0.1 ml. p.o., bid) or BAY y 1015 at 8 or 24 mg/kg, p.o., bid or olsalazine, 150 mg/kg/day, p.o.. Efficacy was determined by measuring daily disease activity index (DAI), quantitative histological scores, qualitative histology and measurement of tissue myeloperoxidase (MPO) and leukotriene B4 (LTB4) levels.. BAY y 1015 was significantly more effective in improving the qualitative histology, inhibiting the DAI, inflammation scores (37-79%), crypt scores (28-71%), MPO (49-57%) and LTB4 levels (56-63%) compared to placebo treatment at all levels of colitis. The two doses of BAY y 1015 were equipotent in decreasing TLB4 levels. BAY y 1015 was significantly better than olsalazine in two of the three protocols used in this study. In the advanced disease level both doses of BAY y 1015 were equipotent in inhibiting crypt and (28-32%) inflammation scores (34-36%), LTB4 (34-56%) and MPO 41-49%) compared to olsalazine.. This study suggests the possibility of investigating the use of this compound for the treatment of human inflammatory bowel diseases.

Topics: Animals; Colitis; Dextran Sulfate; Disease Models, Animal; Female; Leukotriene B4; Lipoxygenase Inhibitors; Mice; Peroxidase; Quinolines

We evaluated the effects of an antagonist of the thromboxane A2 receptor (ONO-NT-126) in an animal model of inflammatory bowel disease (IBD).. Colitis was induced by intracolonic instillation of trinitrobenzenesulfonic acid/ethanol in male Wistar rats. ONO-NT-126 or vehicle alone was administered intraluminally via anus once a day. The rats were killed after 7 days for assessment of colonic damage by the colonic damage score.. ONO-NT-126 markedly reduced the colonic damage. Our findings suggest that the thromboxane-thromboxane receptor system plays an important role in this model of IBD and that antagonism of the thromboxane A2 receptor may prove useful for the treatment of IBD.

Topics: Animals; Bridged Bicyclo Compounds; Colitis; Colon; Dose-Response Relationship, Drug; Ethanol; Fatty Acids, Monounsaturated; Leukotriene B4; Male; Rats; Rats, Wistar; Receptors, Thromboxane; Thromboxane A2; Trinitrobenzenesulfonic Acid

Nitric oxide is thought to play an important role in modulating the inflammatory process. Recently an increase in the inducible form of nitric oxide synthase (iNOS) has been found in the rat trinitrobenzene sulfonic acid model of experimental colitis, and inhibition of nitric oxide synthase activity resulted in an amelioration of tissue injury. The aim of our study was to evaluate in vivo intracolonic release of nitric oxide in this model of colitis. Experimental colitis was induced in male Sprague-Dawley rats by a single intracolonic administration of trinitrobenzene sulfonic acid. Nitrite levels were determined in rectal dialysates by HPLC. The tissue myeloperoxidase and iNOS and the luminal leukotriene B4 were also measured. Nitrite levels were significantly increased in rectal dialysates during colitis and correlated significantly with tissue myeloperoxidase and iNOS activity. The correlation between nitrite dialysate levels and wall iNOS activity confirms that nitrite in dialysates is produced by inflammatory cells and not by colonic bacterial flora. Determination of nitrite levels in rectal dialysates seems a valuable method to monitor colonic inflammation in rat trinitrobenzene sulfonic acid colitis.

Topics: Animals; Colitis; Colon; Disease Models, Animal; Leukotriene B4; Male; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitrites; Peroxidase; Rats; Rats, Sprague-Dawley; Trinitrobenzenesulfonic Acid

This study has examined the response of a rabbit model of inflammatory bowel disease to methylprednisolone. Colitis was induced in the colon of rabbits with 40 mg trinitrobenzenesulphonic acid in 25% ethanol (TNBS). The effect of methylprednisolone (0.5 mg/kg/day) on the development of colitis was determined at one week, by examining the colon's macroscopic and microscopic appearance, the distribution of matrix metalloproteinases (MMPs) and by measuring eicosanoid production. Although there was no difference in the area of ulcerated colonic tissue in the treated and untreated TNBS animals, the increase in polymorphonuclear leucocytes was significantly reduced in TNBS rabbits given methylprednisolone. The only difference in the distribution of MMPs was a reduction in the number of polymorphonuclear leucocytes containing gelatinase B. The release of immunoreactive PGE2 and LTB4, but not 6-keto PGF1 alpha, was increased in the TNBS animals and was unchanged by methylprednisolone. These results show that methylprednisolone does not modify the injury produced by TNBS in this model despite reducing the infiltration of polymorphonuclear leucocytes. Hence it suggests that these cells do not contribute to the injury observed, are not the source of the eicosanoids and that gelatinase B is not required in the healing process in this model.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anti-Inflammatory Agents; Colitis; Colon; Dinoprostone; Disease Models, Animal; Eicosanoids; Leukocyte Count; Leukotriene B4; Metalloendopeptidases; Methylprednisolone; Neutrophils; Rabbits; Random Allocation; Trinitrobenzenesulfonic Acid

1. A controlled-release preparation of mesalazine microgranules (PentasaR; Ferring AS, Vanlose, Denmark) releases the active ingredient over a wide area from the small intestine to the rectum and is consequently expected to bring about therapeutic benefits to patients with ulcerative colitis and Crohn's disease. 2. Mesalazine microgranules (50 or 150 mg/kg per day) were administered orally to each rabbit with carrageenan-induced colitis for six weeks. Its inhibitory effect on colonic mucosal damage was assessed in terms of the microscopic damage scores, leukotriene B4 concentrations and concentrations of mesalazine derivatives. 3. At the end of the experiment, the mesalazine 150 mg group had gained a significantly greater bodyweight than the control group. Microscopic damage was significantly lower in the 150 mg group than in the untreated control group. Tissue concentrations of 5-aminosalicylic acid and acetyl-5-amino-salicylic acid in the small and large intestine were higher in the 150 mg group than in the 50 mg group. Mucosal leukotriene B4 levels tended to be lower in rabbits receiving the larger dose of mesalazine. 4. The present study indicates that slow release 5-amino-salicylic acid at the larger dose reaches the large bowel in sufficiently high concentrations following oral administration and significantly reduces carrageenan-induced colitis in the rabbit.

Topics: Aminosalicylic Acids; Animals; Anti-Inflammatory Agents, Non-Steroidal; Body Weight; Carrageenan; Colitis; Delayed-Action Preparations; Intestinal Mucosa; Leukotriene B4; Male; Mesalamine; Rabbits; Tissue Distribution

To assess the anti-inflammatory action of lexipafant (BB-882), a platelet activating factor antagonist, in an animal model of acute colitis.. An animal intervention study.. Following the rectal instillation of formalin 0.75% into male New Zealand White (NZW) rabbits, 0.85 ml of aggregated immunoglobulin was administered i.v. Treatment groups (0.8 mg/kg, n = 6; 2.4 mg/kg, n = 13; 3.2 mg/kg, n = 10) were given bolus doses of BB-882 two-hourly i.v. (control group, n = 25). Rectal dialysis was performed before induction of colitis and sacrifice. Dialysate leukotriene B4 (LTB4), prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) levels were determined. Tissue was saved for histology and measurement of myeloperoxidase content.. There was a dose-dependent improvement in macroscopic scores (2.4 and 3.2 mg/kg: P < 0.02, P < 0.001) and myeloperoxidase levels (3.2 mg/kg: P < 0.04). Dialysate LTB4 levels fell (2.4 and 3.2 mg/kg: P < 0.03, P < 0.02) as did PGE2 levels. TXB2 concentrations remained unaffected.. The PAF receptor antagonist BB-882 shows efficacy in treating inflammation in an animal model of acute colitis as evidenced by a dose-dependent fall in macroscopic mucosal damage, neutrophil infiltration and reduced generation of inflammatory mediators.

Topics: Animals; Colitis; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Formaldehyde; Injections, Intravenous; Intestinal Mucosa; Leucine; Leukotriene B4; Male; Platelet Membrane Glycoproteins; Rabbits; Receptors, Cell Surface; Receptors, G-Protein-Coupled; Thromboxane B2

Bacterial products released within the gut lumen may alter the course of inflammatory bowel lesions. The effect of intraluminal N-formyl methionyl-leucyl-phenylalanine on mucosal release of inflammatory mediators was investigated in normal and colitis rats (at 1 and 7 days after induction of colitis by trinitrobenzenesulfonic acid). Under anesthesia, the distal colon was perfused using an isosmotic solution with or without synthetic N-formyl methionyl-leucyl-phenylalanine (100 nmol/ml). Effluents were assayed for eicosanoid (PGE2, TXB2 and LTB4) concentration. Myeloperoxidase activity was measured in colonic wall homogenates. In normal rats, peptide perfusion did not change mucosal release of PGE2, TXB2 and LTB4. Colitic rats showed high baseline release of eicosanoids. The peptide did not further increase PGE2 and TXB2 release, but significantly stimulated LTB4 both on days 1 and 7 after induction of colitis. Rats with high myeloperoxidase activity in the colonic wall showed a marked LTB4 response to the peptide. Finally, peptide perfusion increased tissue myeloperoxidase activity in colitis at day 7 but not in colitis at day 1 or in normal rats. In conclusion, bacterial products may activate inflammation. This mechanism of lumen-wall interaction might be involved in the perpetuation of inflammatory lesions of the colonic mucosa.

Topics: Animals; Colitis; Dinoprostone; Disease Models, Animal; Eicosanoids; Intestinal Mucosa; Leukotriene B4; Male; N-Formylmethionine Leucyl-Phenylalanine; Peroxidase; Rats; Rats, Sprague-Dawley; Thromboxane B2; Trinitrobenzenesulfonic Acid

Topics: Acetic Acid; Alkaline Phosphatase; Animals; Biomarkers; Colitis; Disease Models, Animal; Humans; Inflammatory Bowel Diseases; Leukotriene B4; Peroxidase; Quercetin; Rats; Rutin; Trinitrobenzenesulfonic Acid

Capsaicin-sensitive afferent neurons are involved in maintaining the integrity of the gastrointestinal mucosa. These neurons are closely apposed to mast cells and could, therefore, lead to their activation. In the present study, the role of capsaicin-sensitive neurons in the pathogenesis of experimental colitis and the possible involvement of mast cells and nitric oxide were evaluated. Rats were treated with capsaicin subcutaneously, 20, 30, and 50 mg/kg, on three consecutive days, a regimen shown to ablate primary afferent neurons. Colitis was induced two weeks later by flushing 2 ml 5% acetic acid into the proximal colon. Control rats received saline, acetic acid, or capsaicin alone. Another group of rats received ketotifen (100 micrograms/100 g body wt x 2/day) intragastrically 48 hr prior to damage induction and thereafter. Rats were sacrificed 24 hr after damage induction, the colon isolated, damage assessed, explants were organ-cultured for 24 hr for determination of nitric oxide generation, and mucosa extracted for determination of leukotriene B4 generation and nitric oxide synthase activity. Significant increases in colonic weight, nitric oxide synthase activity, and nitric oxide and leukotriene B4 generation accompanied the near tripling of acetic acid-induced damage in capsaicin-pretreated rats. Ketotifen pretreatment significantly decreased the macroscopic damage and the increase in colonic weight. The protection provided by ketotifen was accompanied by a significant decrease in leukotriene B4 generation and nitric oxide synthase activity (80%).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acetates; Acetic Acid; Amino Acid Oxidoreductases; Animals; Capsaicin; Colitis; Colon; Intestinal Mucosa; Ketotifen; Leukotriene B4; Male; Mast Cells; NADPH Dehydrogenase; Neurons, Afferent; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley

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.. 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.. 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%.. 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.

Topics: Amino Acid Oxidoreductases; Animals; Arginine; Colitis; Colon; Dinoprostone; Intestinal Mucosa; Iodoacetamide; Leukotriene B4; Leukotriene C4; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Peroxidase; Rats; Rats, Sprague-Dawley

Colon transmucosal potential difference (TPD), macro- and microscopic lesions, myeloperoxidase activity, and leukotriene levels were studied after the induction of experimental colitis in the rat. Forty-three male Wistar rats were subjected to the instillation of 200 mg/ml 2,4,6-trinitrobenzenesulfonic acid (TNB) solution through a rectal cannula. TPD measurements were made at different distances from the anus before and 24 h and one, two, three, and four weeks after lesion induction. Leukotriene B4 levels were assayed by intracolonic dialysis 24 h and one, two, three and four weeks after lesion induction. Macro- and microscopic evaluations were made of the bowel lesions, and myeloperoxidase activity was assayed. The mean basal TPD was -46.06 mV at 1 cm from the anus, and +10.86 mV in the proximal colon. Twenty-four hours after lesion induction the values proved markedly positive. This was correlated with an abrupt increase in LTB4 levels and myeloperoxidase activity. After one week the TPD values exhibited a greater electronegativity, returning to basal values by the fourth week after lesion induction. This coincided with an improved macroscopic lesion index, LTB4 levels, and myeloperoxidase activity. In conclusion, TPD is a useful indicator of acute colonic lesions and correlates well with LTB4 and myeloperoxidase assays. Moreover, the parameter is able to delimit lesion evolution, reflecting possible ad integrum restoration of the bowel mucosa.

Topics: Animals; Colitis; Colitis, Ulcerative; Fibrosis; Intestinal Mucosa; Leukotriene B4; Leukotrienes; Male; Membrane Potentials; Peroxidase; Rats; Rats, Wistar; Trinitrobenzenesulfonic Acid

TEMPOL, a cyclic nitroxide stable radical blocks biological damage by breaking chain reactions through termination reaction with free radicals, and by inhibiting the catalytic effect of transition metals. This study tested its protective effect on two models of experimental colitis as free radicals play an important part in their pathogenesis. TEMPOL was given intragastrically immediately after induction of colitis with acetic acid or trinitrobenzene sulphonic acid (TNB) and mucosal damage was assessed one, three, or seven days later. Cellular partition of TEMPOL was determined by electron paramagnetic resonance spectroscopy. In vitro experiments showed that TEMPOL immediately penetrates colonic mucosa and, following its intragastric administration, it persists in both gastric and colonic mucosa for several hours. Intragastric administration of TEMPOL, 0.5 g/kg/bw, immediately after intracaecal administration of 5% acetic acid significantly decreased mucosal lesion area, myeloperoxidase activity, and leukotriene B4 and C4 generation when assessed 24 hours after damage induction. Intragastric administration of TEMPOL, 0.5 g/kg/bw, immediately after intracolonic administration of 30 mg TNB in 0.25 ml 50% ethanol, and once daily thereafter, significantly decreased mucosal lesion area assessed after one, three, and seven days, having no effect on LTC4 generation and affecting colonic weight, myeloperoxidase activity, and LTB4 generation only sporadically. In conclusion, TNB and acetic acid induced colitis can be pharmacologically manipulated by TEMPOL. TEMPOL may be beneficial in the treatment or prevention of inflammatory bowel disease.

Topics: Acetates; Animals; Antioxidants; Colitis; Cyclic N-Oxides; Disease Models, Animal; Electron Spin Resonance Spectroscopy; Intestinal Mucosa; Leukotriene B4; Leukotriene C4; Lipoxygenase; Male; Peroxidase; Rats; Rats, Sprague-Dawley; Spin Labels; Time Factors; Trinitrobenzenesulfonic Acid

The time course of disturbances of distal colonic electrolyte transport during experimental colitis in rats was compared with changes in the severity of inflammation and epithelial disruption. Colitis was induced by intracolonic administration of trinitrobenzenesulfonic acid (TNBS). At time points from 1 day to 8 wk thereafter, Na+ and Cl- transport was studied under short-circuited conditions in Ussing chambers, three indexes of tissue inflammation were measured, and histology was performed. Net absorption of Na+ and Cl- was abolished at 1 and 4 days after induction of colitis, but recovered to control levels by 1 wk. All unidirectional electrolyte fluxes were elevated at 1 day and fell significantly, generally to control levels, by 4 days. The indexes of inflammation, tissue myeloperoxidase, and synthetic capacities for prostaglandin E2 and leukotriene B4 were all significantly elevated from 1 day to 2 wk post-TNBS. At 1 and 4 days, there was widespread epithelial necrosis, and reepithelialization was consistently seen by 2 wk. In additional studies, 2 wk post-TNBS, the short-circuit current response to 3-isobutyl-1-methylxanthine was reduced compared with controls. These data suggest that abolition of electrolyte absorption early in this experimental colitis was largely attributable to epithelial damage. Despite demonstrable tissue inflammation 2 wk post-TNBS, basal electrolyte transport was not impaired, while the colitic epithelium was hyporesponsive to a Cl- secretagogue. The data also suggest that gross barrier function was restored prior to reepithelialization.

Topics: Animals; Biological Transport; Colitis; Colon; Dinoprostone; Electrolytes; Leukotriene B4; Male; Peroxidase; Rats; Rats, Wistar; Time Factors; Trinitrobenzenesulfonic Acid

Eicosanoids and platelet-activating factor (PAF) production increases in experimental colitis. Both eicosanoids and PAF seem to arise from similar membrane phospholipids. To support both these suggestions we have investigated whether a fat-free diet, which should alter production of eicosanoids and PAF, affects experimental colitis. Essential fatty acid deficient (EFAD) rats were obtained by putting 4-week-old animals on a fat-free diet for 3 months. Experimental colitis was induced by a single intracolonic administration of 2 ml of 4% acetic acid. One to seven days later the animals were sacrificed and the colon removed to assess macroscopically and histologically intestinal damage. Eicosanoids and PAF levels were also measured in the mucosa scrapings by specific radioimmunoassay. The injury to the colon was more evident in control rats compared with EFAD rats. Besides colonic tissue of control rats showed a highly significant increase of PGE2, LTB4 and PAF, compared with levels in EFAD rats. Our results indicate that fat-free diet reduces tissue damage, and at the same time PGE2, LTB4 and PAF colonic content.

Topics: Acetates; Acetic Acid; Acid Phosphatase; Animals; Colitis; Dietary Fats; Dinoprostone; Fatty Acids; Leukotriene B4; Male; Platelet Activating Factor; Rats; Rats, Wistar

Altered peripheral neutrophil function is a feature of IBD that may contribute to the chronicity and extragastrointestinal manifestations of this disease, but clinical evidence for such alterations is confounded by variations in patient characteristics, disease onset, and use of therapeutics that can influence neutrophil function. The use of a rat model of colitis has permitted us to characterize, in a controlled manner, the causal relationship between colitis and altered peripheral neutrophil function. At various times after induction of colitis with trinitrobenzene sulfonic acid (TNBS), peripheral neutrophils were isolated and assays of phagocytosis, chemotaxis, leukotriene B4 (LTB4) synthesis, and superoxide production were performed using a variety of stimuli. Circulating neutrophil numbers increased about fourfold within 12 hr of TNBS administration and returned to normal levels over the following two weeks. LTB4 synthesis in response to calcium ionophore decreased at 12 hr after induction of colitis, then returned to control levels. The chemotactic responses of peripheral neutrophils to LTB4 and FMLP in vitro and to LTB4 and IL-8 in vivo were profoundly suppressed through the two-week study period. Phagocytosis of nitroblue tetrazolium was significantly enhanced (ca. threefold) at 12 hr after induction of colitis and remained elevated throughout the study period. Superoxide production was also significantly elevated in the early phase of colitis (by ca. fourfold), but was not different from control levels at seven and 14 days. These results demonstrate that colonic inflammation profoundly influences peripheral blood neutrophil function, although the direction and magnitude of the alteration varied among the various functions assessed. The prolonged depression of chemotactic activity may represent a physiological reaction to limit the inflammatory response.

Topics: Animals; Chemotaxis, Leukocyte; Colitis; Inflammatory Bowel Diseases; Leukocyte Count; Leukotriene B4; Male; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Phagocytosis; Rats; Rats, Wistar; Superoxides; Trinitrobenzenesulfonic Acid

We investigated the therapeutic efficacy of n-3 polyunsaturated fatty acids (PUFAs) on trinitro-benzene sulfonic acid (TNBS)-induced colitis in the rats, which condition is considered an experimental Crohn's disease (CD). In rats with TNBS-induced colitis, feeding with an elemental diet (ED) plus 2% n-3 PUEA-rich perilla oil significantly suppressed plasma leukotriene (LT) B4 and ulcer index compared to that in rats fed with ED plus 2% n-6 PUFA-rich safflower oil (34.2 +/- 12.3 s 63.8 +/- 13.2 pg/ml and 8.8 +/- 12.1 vs 66.4 +/- 33.1, P < 0.01, respectively). Moreover, the plasma LTB4 and the ulcer index were significantly correlated (P < 0.05). Feeding with ED plus 2% alpha-linolenic acid (A-LA)-rich vegetable oil significantly reduced plasma LTB4 and colonic weight compared to that in rats fed with ED plus 2% eicosapentaenoic acid (EPA)/docosahexaenonic acid (DHA)-rich fish oil in this model (61.6 +/- 10.5 vs 85.0 +/- 20.9 pg/ml and 0.83 +/- 0.13 vs 0.96 +/- 0.08g, P < 0.05, respectively). This study suggested that dietary fat manipulation with perilla oil can reduce colonic damage and that this is correlated with the suppression of plasma LTB4. The therapeutic efficacy of A-LA in controlling intestinal inflammation in experimental CD may be superior to that of EPA and DHA.

Topics: alpha-Linolenic Acid; Animals; Colitis; Colon; Crohn Disease; Fatty Acids, Omega-3; Fish Oils; Food, Formulated; Leukotriene B4; Male; Organ Size; Rats; Rats, Sprague-Dawley; Safflower Oil; Trinitrobenzenesulfonic Acid

Platelet-activating factor (PAF) is an endogenous phospholipid which may be an important mediator of shock and inflammation. Recent evidence suggests that PAF plays a role in the development of ischemic colitis and inflammatory bowel disease. Its effects are mediated by second messengers, including the arachidonic acid metabolites. Using an ex vivo isolated left colon rabbit perfusion model, our aims were to determine whether exogenously administered trinitrobenzene sulfonic acid (TNB), which produces experimental colitis, stimulates both PAF and eicosanoid release in the colon, and if so, whether this effect can be blocked by a PAF antagonist. Colonic inflammation was induced by the intracolonic administration of 0.25 ml of 50% ethanol containing 30 mg of TNB. Tissue and perfusate concentrations of the eicosanoids, [prostaglandin E (PGE2), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TXB2), leukotriene B4 (LTB4)] and the autocoid PAF were measured by ELISA. During TNB infusion there was a significant increase in tissue levels of PAF compared to control colons. Additional studies performed pretreating the colons with the PAF receptor antagonist WEB-2170 prior to TNB infusion blocked PAF release. TNB stimulated release of luminal eicosanoids except LTB4 and suppressed release of tissue prostanoids. Pretreatment with WEB-2170 prior to TNB inhibited luminal eicosanoids, and inhibited PGE2 and prostacyclin, but not TX tissue suppression. Inhibition of TNB-stimulated PAF release by WEB-2170 suggests that PAF may play a role in TNB-induced colitis and this phenomenon may mediate tissue injury.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Azepines; Colitis; Colon; Dinoprostone; Eicosanoids; Gastrointestinal Contents; Leukotriene B4; Platelet Activating Factor; Rabbits; Second Messenger Systems; Thromboxane B2; Triazoles; Trinitrobenzenesulfonic Acid

As part of our search for novel antiinflammatory drug candidates, we have designed and synthesized a series of 3-pyridylmethyl-substituted 2-amino-6- hydroxybenzothiazoles. Introduction of a 3-pyridylmethyl group into the 2-amino group (type-A) or the benzene ring (type-B) of 2-amino-6-hydroxybenzothiazoles imparted dual inhibitory activity against the production by glycogen-induced peritoneal cells of rat (in vitro) of leukotriene B4 (LTB4) and thromboxane A2 (TXA2), while not significantly inhibiting that of prostaglandin E2 (PGE2). The observed inhibition of the former two arachidonic acid metabolites was indicated to be the result of a direct action on 5-lipoxygenase and TXA2 synthetase by a cell-free in vitro assay. On the other hand, the inhibitory activities against PGE2 production were for most compounds very weak, indicating that they did not inhibit cyclooxygenase. Structure-activity relationship studies concerning the position of the 3-pyridylmethyl group revealed that type-B compounds generally showed about 10-fold stronger inhibitory activity against TXA2 synthetase than type-A compounds. The position of the 3-pyridylmethyl group played an important role in TXA2 synthetase inhibition. When some of these compounds (8, 13a, 26a (E3040), 26b, 27b, and 28b) were orally administered in the rat TNB/ethanol-induced chronic colitis model (100 mg/kg), the production of both LTB4 and TXB2 in the rat colon was reduced (ex vivo). In addition, one type-B compound, 6-hydroxy-5,7-dimethyl-2-(methylamino)-4-(3-pyridylmethyl)benzothiazole (26a), demonstrated a therapeutic effect at treatments of 100 mg/kg po once daily for 11 days and showed almost comparable activity to sulfasalazine at a dose of 500 mg/kg, the reference drug for inflammatory bowel diseases, in this in vivo model.

Topics: Animals; Blood Platelets; Cells, Cultured; Colitis; Dinoprostone; Disease Models, Animal; Humans; Leukotriene B4; Lipoxygenase Inhibitors; Male; Peritoneal Cavity; Rats; Rats, Inbred F344; Sheep; Structure-Activity Relationship; Thiazoles; Thromboxane B2; Thromboxane-A Synthase

A study was made of the role of cytokine-induced neutrophil chemoattractant (CINC), regarded as a member of the interleukin-8 family, in rat experimental colitis induced by trinitrobenzene sulfonic acid and ethanol. Colonic myeloperoxidase (MPO) activity, a marker of tissue neutrophil infiltration, was observed to reach a plateau from 24 h to 1 week following the induction of colitis; tissue CINC levels, as measured by enzyme-linked immunosorbent assay, rose rapidly, peaking at 12 h before the rise in myeloperoxidase activity. The time-course of tissue leukotriene B4, another chemoattractant, was followed by that of MPO activity. Neutrophil accumulation into tissue in this model would thus appear to be under the control of CINC. Anti-CINC was also noted to inhibit 32.9 to 58.1% of chemotactic activity determined by bioassay during the same period, this being further evidence that CINC is a major chemotactic agent in this model. The present results indicate that CINC may have a crucial role in initiating neutrophil infiltration in experimental colitis.

Topics: Animals; Chemokines, CXC; Chemotactic Factors; Colitis; Colon; Enzyme-Linked Immunosorbent Assay; Ethanol; Growth Substances; Intercellular Signaling Peptides and Proteins; Interleukin-8; Leukotriene B4; Male; Neutrophils; Peroxidase; Rats; Rats, Sprague-Dawley; Trinitrobenzenesulfonic Acid

A new, orally active de-N-acetylated lysoglycosphingolipid (WILD20) was evaluated as antiinflammatory agent using a model of chemically-induced inflammatory bowel disease (IBD) in the rat to mimic human ulcerative colitis and Chron's disease. IBD was induced by hapten trinitrobenzenesulphonic acid (TNB). WILD20, orally administered as preventive or curative, was demonstrated to be efficacious at daily dosages of 0.1-1 mg/kg for 4-5 days. Damage scores, body weight, spleen weight, colonic tissular levels of LTB4, myeloperoxidase (MPO) and malondialdehyde (MDA) are influenced and brought into parameters of normality. Histological observation demonstrated quicker healing, better repair, reduced inflammation, and poor eosinophil degranulation. The mechanisms underlying WILD20 antiinflammatory effects were investigated: whereas WILD20 fails to show a direct effect on PKC, it reduces PKC translocation to the membrane; cellular PLA2 was consequently greatly reduced through this mechanism and thought to be responsible for WILD20 efficacy towards chemically-induced IBD.

Topics: Animals; Arachidonic Acid; Carbohydrate Sequence; Colitis; Colon; Gangliosides; Humans; Inflammatory Bowel Diseases; Leukotriene B4; Male; Malondialdehyde; Molecular Sequence Data; Organ Size; Pancreas; Peroxidase; Phospholipases A; Phospholipases A2; Platelet Activating Factor; Platelet Aggregation Inhibitors; Rats; Rats, Wistar; Spleen; Synovial Fluid; Trinitrobenzenesulfonic Acid

SC-41930, 7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)propoxy]-3,4- dihydro-8-propyl-2H-1-benzopyran-2-carboxylic acid, is a selective, orally active, LTB4 receptor antagonist currently in clinical trials for psoriasis and ulcerative colitis. Exhaustive SAR studies found a potential backup compound, SC-50605, which was 7-16 times more potent than SC-41930 in LTB4 receptor binding, chemotaxis and degranulation assays. SC-50605 also inhibited LTB4-induced intradermal chemotaxis in cavine skin at an oral dose of 0.10 mg/kg and displayed good activity in animal models of colitis and epidermal inflammation both orally and topically.

Topics: Animals; Benzopyrans; Binding Sites; Cell Degranulation; Chemotaxis, Leukocyte; Colitis; Dermatitis; Disease Models, Animal; Drug Design; Guinea Pigs; In Vitro Techniques; Leukotriene B4; Mice; Receptors, Leukotriene B4; Thiazoles

To evaluate anti-colitic efficacy, eight cotton-top tamarins (CTTs) with histologically confirmed persistent active colitis were given the anti-inflammatory agent SC-41930 (10 mg/kg BW by gavage BID) for eight weeks. Colonic endoscopy and biopsy observations, CBCs and clinical chemistries, and stool consistency were evaluated pre-, mid-, and posttreatment. Colitic activity was graded histologically from A1 (mild) to A5 (severe); results varied among the seven animals that completed the study: five improved, one worsened, and one was unchanged. Serum enzyme levels were significantly reduced with treatment. Stool condition remained puddly throughout treatment and body weights did not vary from pretreatment levels. However, SC-41930 produced histological evidence (reduced numbers of polymorphonuclear cells) of anti-colitic efficacy over an eight-week treatment period in CTTs with persistent active colitis. These results support the use of the CTT colitis model to evaluate efficacy of therapeutic agents and provide useful predictive information to aid in the medical management of human IBD.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Benzopyrans; Body Weight; Colitis; Colon; Disease Models, Animal; Leukotriene B4; Saguinus

Use of the CTT model provides insight into the inflammatory mediator contribution in the pathogenesis of idiopathic colitis. To evaluate anti-colitic efficacy, the leukotriene B4 receptor antagonist and anti-inflammatory agent, SC-41930, was administered (10 mg/kg BW by gavage BID) for 8 weeks to CTTs with histologically confirmed persistent and defined active colitis. The inflammatory mediators LTB4, PGE2, TXB2, and PAF were assayed in colonic dialysate that was collected after 1 1/2 h from four CTTs pre-, mid-, and post-treatment, frozen at -70 degrees C, and analyzed by RIA after HPLC purification. LTB4 levels were lower at mid- and post-treatment and had little inter-animal variation post-treatment. PGE2 and PAF levels were elevated during SC-41930 treatment, but there was a trend towards lower thromboxane B2 levels. Reduced LTB4 (PMN degranulation and chemotaxis) and increased PGE2 (mucosal-protective effect) may, in part, explain the observed efficacy of SC-41930 in active tamarin colitis.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acids; Benzopyrans; Colitis; Colon; Dinoprostone; Disease Models, Animal; Leukotriene B4; Platelet Activating Factor; Radioimmunoassay; Saguinus; Thromboxane B2

The effect of octreotide, a synthetic analogue of somatostatin, on the modulation of the acetic acid model of experimental colitis was examined. Colitis was induced by intracolonic administration of 2 ml of 5% acetic acid. The inflammatory response elicited by the acetic acid resulted in increased colonic synthesis of platelet activating factor, leukotriene B4 and decreased mucosal somatostatin levels. Subcutaneous administration of octreotide (10 micrograms/rat) 1 hour before or immediately after damage induction, as well as 1 and 23 hours after acetic acid application, resulted in a significant reduction in mucosal damage. The protective effect was accompanied by a significant reduction in platelet activating factor activity, leukotriene B4, and vasoactive intestinal peptide concentrations. There were no significant changes in mucosal leukotriene C4 and calcitonin gene related peptide levels. This study shows that acetic acid induced colitis is pharmacologically manipulated by octreotide. The mechanism of action of octreotide has not yet been fully determined. The potential use of octreotide in treating active inflammatory bowel disease remains to be evaluated.

Topics: Acetates; Acetic Acid; Animals; Colitis; Colon; Intestinal Mucosa; Leukotriene B4; Male; Octreotide; Platelet Activating Factor; Rats; SRS-A

The efficacy of the leukocyte recruitment inhibitor, N-[9H-2,7-dimethylfluoren-9-ylmethoxy)carbonyl]-L-leucine (NPC 15669) was compared with drugs used to treat inflammatory bowel diseases in a rat model, acetic acid-induced colitis.. Colonic damage assessed by visual inspection, histological quantitation of tissue injury, vascular permeability, myeloperoxidase (MPO) accumulation, and synthesis of inflammatory mediators were measured.. Intrarectal pretreatment with NPC 15669 results in a significant reduction of all measured indices of inflammation. The median effective dose (ED50) of NPC 15669 for inhibition of MPO accumulation and vascular permeability is 13.2 mg/kg and 31 mg/kg, respectively. The active moiety of sulfasalazine, 5-aminosalicylic acid (5-ASA), the antioxidant/5-lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA) and the corticosteroids dexamethasone and hydrocortisone, yielded ED50 values (MPO accumulation) of 68 mg/kg, 95 mg/kg, 0.7 mg/kg, and 13 mg/kg, respectively. When formulated suspensions of NPC 15669, 5-ASA, or dexamethasone were used, potency was increased 10-40-fold. Furthermore, NPC 15669 (10 mg/kg) administered 7 hours after acetic acid and evaluated 24 hours after acetic acid administration significantly attenuated neutrophil influx (70% inhibition of MPO accumulation), whereas 5-ASA (100 mg/kg) displayed no therapeutic effects.. NPC 15669 may be useful in the treatment of inflammatory disorders.

Topics: Acetates; Acetic Acid; Aminosalicylic Acids; Animals; Anti-Inflammatory Agents, Non-Steroidal; Capillary Permeability; Colitis; Colon; Dexamethasone; Fluorenes; Glycine; Hydrocortisone; Leucine; Leukotriene B4; Male; Masoprocol; Mesalamine; Neutrophils; Peroxidase; Rats; Rats, Sprague-Dawley; Thromboxane B2

The ability of nonsteroidal anti-inflammatory drugs to exacerbate experimental colitis, and the possible contributions of the "shunting" of arachidonate via the 5-lipoxygenase pathway, were investigated using a rat model in which colitis was induced by intracolonic administration of trinitrobenzene sulfonic acid in a vehicle of 50% ethanol. Twice daily treatment with indomethacin (0.1-1 mg/kg SC) during the first week after trinitrobenzene sulfonic acid/ethanol administration resulted in dose-dependent increases in the severity of colitis and in the incidence of mortality. Mortality was not observed in vehicle-treated colitic rats or in normal rats treated with indomethacin. Similar exacerbation of colitis was observed in rats treated with naproxen (5 mg/kg). Whereas treatment with a 5-lipoxygenase inhibitor, PF-5901 (100 mg/kg PO), resulted in a significant reduction of the severity of colitis, concomitant administration of PF-5901 and indomethacin (0.5 mg/kg SC) did not inhibit the exacerbative effects of the indomethacin in this model. In separate studies, administration of indomethacin was found to significantly increase colonic myeloperoxidase activity (a measure of tissue granulocyte numbers) and suppress colonic prostaglandin E2 synthesis, while not significantly affecting colonic leukotriene B4 synthesis. The effect on myeloperoxidase activity was seen during the period 21-24 hours after trinitrobenzene sulfonic acid ethanol administration, but not during the period 45-48 hours after induction of colitis. In in vitro studies using samples of inflamed colon and in vivo studies in which colonic eicosanoid production was measured by colonic dialysis, inhibition of prostaglandin E2 synthesis was not accompanied by significant changes in leukotriene B4 synthesis. These results suggest that inhibitors of colonic prostaglandin synthesis can markedly exacerbate colitis, and that this effect is unrelated to alterations in colonic leukotriene B4 synthesis. Endogenous prostaglandins may exert anti-inflammatory effects during the acute stages of colitis.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Colitis; Colon; Dinoprostone; Drug Combinations; Indomethacin; Leukotriene B4; Male; Misoprostol; Naproxen; Peroxidase; Quinolines; Rats; Rats, Inbred Strains

Intestinal mucus protects the underlying epithelium against adhesion and invasion by microbial pathogens and their products. In inflamed colonic mucosa there are both histochemical and biochemical changes in the major organic constituent of mucus, goblet cell-derived mucin. To determine if these changes result in differences in functional properties of mucin, inhibition of adherence of piliated Escherichia coli, strain RDEC-1 (serotype O15:H-), by mucin purified from distal colons of normal rabbits was compared with inhibition by mucin from colons of rabbits with dinitrochlorobenzene-induced colitis. Histology from inflamed colons revealed evidence of chronicity with a chronic inflammatory cell infiltrate, depletion of mucous glands, and branching of crypts. Mucin was purified from crude mucus of distal colonic mucosa by sequential ultracentrifugation and characterized by gel electrophoresis and amino acid analysis. The rabbit enteropathogen RDEC-1 was grown to promote expression of adherence pili. A nonpiliated mutant, strain M34, was used as a negative control. A concentration-dependent inhibition of piliated RDEC-1 binding was shown using mucins derived from both inflamed and noninflamed colons. However, equivalent dry weights of mucin purified from inflamed colons showed less inhibition of bacterial binding (10.3% inhibition +/- 5.2%; mean +/- SD) compared with mucin from normal colons (47.6% +/- 10.8%; P less than 0.05). Mucin purified from additional animals with hapten-induced colitis but treated with the oral leukotriene B4-receptor antagonist SC-41930 showed intermediate inhibition of RDEC-1 binding (35.6% +/- 14.3%). It is concluded that mucin derived from inflamed distal colon of rabbits failed to inhibit in vitro binding of piliated RDEC-1, and by decreasing mucosal inflammation, this functional alteration of mucin was partially reversed.

Topics: Animals; Bacterial Adhesion; Colitis; Colon; Dinitrochlorobenzene; Escherichia coli; Guinea Pigs; Leukotriene B4; Male; Mucins; Rabbits

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.

Topics: Animals; Colitis; Colon; Dinoprostone; Intestinal Absorption; Leukotriene B4; Male; Peroxidase; Rats; Rats, Inbred Strains; Verapamil

The effect of highly purified eicosapentaenoic acid ethyl ester (EPA-E) on colitis was investigated using a guinea pig model. The technique for preparing a degraded carrageenan with a molecular weight of about 30,000 from commercial iota-carrageenan was first refined. When this degraded carrageenan was fed to guinea pigs, localized ulcerations occurred in the cecum with infiltration of numerous mononuclear phagocytes. Oral administration of 300 mg.kg-1.day-1 of EPA-E for 3 weeks significantly prevented the development of colitis. The amounts of prostaglandin E2, thromboxane B2, and leukotriene B4 released from the cecal mucosa were also measured. The release of prostaglandin E2 and thromboxane B2 was significantly decreased in the animals fed EPA-E compared with those given olive oil or a vehicle alone. In addition, there was a positive correlation between the amounts of these eicosanoids and the degree of ulcer formation. However, there was no difference in the amount of leukotriene B4 among various experimental groups of animals. Furthermore, EPA-E feeding induced a significant decrease in the level of arachidonic acid and a significant increase in that of EPA in peritoneal macrophages. These results suggest that EPA has a prophylactic effect on the development of carrageenan-induced colitis, which may be ascribed in part to reduced eicosanoid production.

Topics: Animals; Body Weight; Carrageenan; Cecal Diseases; Colitis; Dinoprostone; Dose-Response Relationship, Drug; Eicosapentaenoic Acid; Fatty Acids; Guinea Pigs; Leukotriene B4; Macrophages; Male; Occult Blood; Thromboxane B2; Ulcer

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.

Topics: Acetates; Animals; Body Fluids; Colitis; Dialysis; Dinoprostone; Indoles; Indomethacin; Intestinal Mucosa; Leukotriene Antagonists; Leukotriene B4; Male; Misoprostol; Peroxidase; Rats; Rats, Sprague-Dawley

Intracolonic administration of trinitrobenzene sulfonic acid in ethanol results in the development of colitis in the rat. Previous studies have demonstrated that the severity of this colitis can be markedly reduced by repeated treatment with inhibitors of leukotriene synthesis, although such treatment does not appear to affect the initial migration of granulocytes into the colon. The present study evaluated the contribution of leukotrienes and interleukin-1 to the recruitment of granulocytes into the colon during the first 12 h after induction of colitis. Rats were treated with a leukotriene synthesis inhibitor (PF-5901), a leukotriene B4 receptor antagonist (SC-41930), an IL-1 receptor antagonist or a corticosteroid (prednisolone) prior to induction of colitis. Granulocyte infiltration was assessed by measurement of colonic myeloperoxidase activity and severity of colonic damage was blindly scored. Despite significant inhibition of leukotriene synthesis, PF-5901 did not affect colonic myeloperoxidase activity or the severity of colonic injury at any time point. Similarly, SC-41930 was without significant effect. However, both the interleukin-1 receptor antagonist and prednisolone significantly reduced colonic myeloperoxidase activity (by approximately 50%) and severity of colonic damage at 6 h after induction of colitis, without significantly affecting colonic leukotriene synthesis. These beneficial effects were no longer apparent at 12 h after induction of colitis. This study demonstrates that the infiltration of granulocytes into the colon during the acute phase of colitis in the rat occurs independent of leukotriene synthesis and appears to be at least in part attributable to interleukin-1.

Topics: Analysis of Variance; Animals; Benzopyrans; Chemotaxis, Leukocyte; Colitis; Interleukin-1; Kinetics; Leukotriene B4; Male; Neutrophils; Peroxidase; Quinolines; Rats; Rats, Wistar; Trinitrobenzenesulfonic Acid

Spontaneous colitis in CTT's presents cytological characteristics similar to chronic ulcerative colitis in humans, e.g. inflammatory cell infiltrate and crypt abscesses. To better characterize CTT colitis as a potential model for human inflammatory bowel disease (IBD), inflammatory mediators identified in colonic tissue of human IBD patients and/or experimental colitis models were assayed. Inflammatory mediator changes in plasma and colon from tamarins with acute (n = 10) and chronic (n = 10) colitis (by mucosal biopsy) were assayed by RIAs. Similar inflammatory mediators were found in the CTT's with acute colitis. In the plasma, PAF and PGE2 levels were lower in acute colitis CTT's, no LTB4 was detected, and histamine levels were not different from chronic colitic animals. In the colon, myeloperoxidase and interleukin-1 beta were significantly higher in acute colitis, PGE2 and LTB4 were higher but not significantly, and PAF was not different from chronic CTT's. These data suggest that a combination of events are occurring in the pathogenesis of tamarin colitis that involves some of the same mediators that are found in the human disease and in other experimental models. The importance of these findings to human IBD remains for further investigation; however, the spontaneous primate model offers an exciting approximation of the disease development and merits further investigation for understanding the pathogenesis of human IBD as well as to aid in development of targeted therapeutics.

Topics: Acute Disease; Animals; Chronic Disease; Colitis; Dinoprostone; Disease Models, Animal; Histamine; Interleukin-1; Leukotriene B4; Peroxidase; Platelet Activating Factor; Saguinus

Eicosanoids, as modulators of inflammation, may be involved in the pathogenesis of inflammatory bowel disease. We investigated their potential role in a rat model of chronic granulomatous colonic inflammation induced by trinitrobenzene sulphonic acid. Luminal eicosanoid release was quantified in vivo using a dialysis bag placed into the distal colon. We tested the effect of drugs known to modify inflammatory activity or arachidonic acid metabolism. Three days after intracolonic injection of trinitrobenzene sulphonic acid at different dose levels, the dialysates showed a highly significant increase of prostaglandin E2, 6-keto-prostaglandin F1 alpha, thromboxane B2 (TXB2), and leukotriene B4, compared with levels in controls not subjected to the toxic agent. Remarkably, the release of TXB2 continued to increase during the stage of chronic inflammation (up to day 21), whereas the levels of the remainder eicosanoids declined. Treatment with prednisone or 5-aminosalicylic acid reduced TXB2 levels in the chronic stage of the inflammatory disease and improved the morphological damage as assessed macroscopically and histologically. Moreover, two selective thromboxane synthetase inhibitors, OKY 1581 and R70416, significantly reduced the development of chronic inflammatory lesions in the colon while inhibiting the release of TXB2. Our results indicate that (1) luminal release of thromboxane increases in the chronic stage of colonic inflammation, (2) anti-inflammatory treatment reduces tissue damage and thromboxane release, and (3) selective thromboxane synthetase inhibition improves the course of the disease in our experimental model.

Topics: 6-Ketoprostaglandin F1 alpha; Aminosalicylic Acids; Animals; Colitis; Dinoprostone; Indomethacin; Leukotriene B4; Male; Mesalamine; Methacrylates; Pentanoic Acids; Prednisone; Pyridines; Rats; Rats, Inbred Strains; Thromboxane B2; Thromboxane-A Synthase; Trinitrobenzenesulfonic Acid

Bacterial chemotactic peptides from the intestinal lumen could potentially induce inflammation if they reached the mucosa. We tested several peptides chemotactic for different inflammatory cells, as well as a nonchemotactic peptide, bradykinin, for their ability to induce colitis in vivo in rabbits. These peptides were also assessed for their ability to stimulate release of the eicosanoids leukotrienes B4 and C4 and prostaglandin E2 from normal rabbit colons perfused ex vivo. Intracolonic administration of n-formyl-methionyl-leucyl-phenylalanine (chemotactic for neutrophils); its methyl ester (chemotactic for monocytes), and alanyl-glycyl-seryl-glutamic acid (chemotactic for eosinophils) all produced colitis (assessed grossly and histologically) within 4 days. Bradykinin did not induce colitis although it did release prostaglandin E2. n-Formyl-methionyl-leucyl-phenylalanine methyl ester induced the greatest degree of colitis in vivo and released prostaglandin E2 and leukotrienes ex vivo. n-Formyl-methionyl-leucyl-phenylalanine and alanyl-glycyl-seryl-glutamic acid induced comparable degrees of inflammation, but alanyl-glycyl-seryl-glutamic acid produced no eicosanoid release while n-formyl-methionyl-leucyl-phenylalanine released both prostaglandin E2 and leukotriene B4 and leukotriene C4 products from normal ex vivo perfused colons. Thus alanyl-glycyl-seryl-glutamic acid produces colitis independent of proinflammatory eicosanoids while eicosanoid release could contribute to colitis produced by n-formyl-methionyl-leucyl-phenylalanine methyl ester. This experimental model of colitis may reflect one possible etiology of inflammatory bowel disease in humans, when bacterial chemotactic peptides breach mucosal defenses in susceptible individuals.

Topics: Animals; Bradykinin; Chemotactic Factors; Chemotactic Factors, Eosinophil; Chemotaxis, Leukocyte; Colitis; Dinoprostone; Leukotriene B4; Male; N-Formylmethionine Leucyl-Phenylalanine; Oligopeptides; Rabbits; SRS-A

The ability of various leukotrienes, platelet-activating factor and N-formyl-methyl-leucyl-phenylalanine to augment colonic damage induced by 30% ethanol was investigated in the rat. Each of the mediators was tested at a dose of 2 nmol, administered intracolonically in the ethanol vehicle. When colonic damage was assessed 72 hr later, only leukotriene B4 significantly augmented damage compared to the controls. The incidence of ulcers increased from 35% in the control group to 90% in the group receiving leukotriene B4. Leukotriene B4 administration also resulted in significant increases in colonic myeloperoxidase activity and colonic leukotriene B4 synthesis. To assess the possible contribution of infiltrating neutrophils to the increase in colonic leukotriene B4 synthesis that accompanies colonic inflammation, colitis was induced in normal and neutropenic rats by intracolonic administration of trinitrobenzene sulfonic acid. Neutropenia was achieved by treatment with an antineutrophil serum. In the neutropenic animals killed 4 hr after induction of colitis significant changes in leukotriene B4 synthesis were not observed, whereas a fourfold increase was observed in the controls. From these studies we conclude the following: (1) leukotriene B4, at a dose of 2 nmol, can significantly potentiate the colonic ulceration induced by 30% ethanol; (2) this action of leukotriene B4 is not shared by the same dose of the other inflammatory mediators tested; and (3) infiltrating neutrophils are the major source of colonic leukotriene B4 synthesis in a rat model of colitis.

Topics: Administration, Rectal; Animals; Colitis; Drug Synergism; Ethanol; Leukotriene B4; Leukotrienes; Male; N-Formylmethionine Leucyl-Phenylalanine; Neutropenia; Platelet Activating Factor; Rats; Rats, Inbred Strains; Ulcer

Interleukin 1 (IL-1) may be a key mediator of inflammation and tissue damage in inflammatory bowel disease (IBD). In rabbits with immune complex-induced colitis, IL-1 alpha and beta mRNA levels were detectable at 4 h, peaked at 12 but were absent at 96 h after the induction of colitis. Colonic IL-1 tissue levels were measured by specific radioimmunoassays. IL-1 alpha was significantly elevated at 4 h (9.4 +/- 1.5 ng/g colon), progressively increased at 48 h (31 +/- 5.8 ng/g) and then decreased by 96 h (11.5 +/- 3.4 ng/g). IL-1 beta levels were 2.0 +/- 0.5 ng/g colon at 4 h, 5.0 +/- 1.6 ng/g at 48 h and undetectable by 96 h. By comparison, colonic levels of PGE2 and LTB4 were unchanged during the first 12 h and did not become elevated until 24 h. IL-1 alpha levels were highly correlated with inflammation (r = 0.885, P less than 0.0001), edema (r = 0.789, P less than 0.0001) and necrosis (r = 0.752, P less than 0.0005). Treatment with a specific IL-1 receptor antagonist (IL-1 ra) before and during the first 33 h after the administration of immune complexes markedly reduced inflammatory cell infiltration index (from 3.2 +/- 0.4 to 1.4 +/- 0.3, P less than 0.02), edema (from 2.2 +/- 0.4 to 0.6 +/- 0.3, P less than 0.01) and necrosis (from 43 +/- 10% to 6.6 +/- 3.2%, P less than 0.03) compared to vehicle-matched colitis animals. These studies demonstrate that (a) IL-1 gene expression and synthesis occur early in the course of immune complex-induced colitis; (b) are significantly elevated for 12 h before the appearance of PGE2 and LTB4; (c) tissue levels of IL-1 correlate with the degree of tissue inflammation and; (d) specific blockade of IL-1 receptors reduces the inflammatory responses associated with experimental colitis.

Topics: Antigen-Antibody Complex; Blotting, Northern; Colitis; Edema; Gene Expression; Interleukin-1; Leukotriene B4; Necrosis; Prostaglandins E; Receptors, Immunologic; Receptors, Interleukin-1; Time Factors

Inflammatory bowel disease is a chronic inflammatory disorder of the gastrointestinal tract that includes ulcerative colitis and Crohn's disease. Leukotriene B4 is thought to be a prominent proinflammatory mediator in these diseases, in that leukotriene B4 levels are increased in the colonic mucosa of inflammatory bowel disease patients and there is increased polymorphonuclear leukocyte infiltration of these tissues. We evaluated the efficacy of 7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)-3,4-dihydro-8-propyl -2H-1-benzopyran-2-carboxylic acid (SC-41930), a potent, orally active leukotriene B4 receptor antagonist, in a model of inflammatory bowel disease. Colonic mucosal inflammation was induced in rats, guinea pig and rabbits by rectal instillation of a dilute solution of acetic acid. Twenty-four hours later, mucosal levels of myeloperoxidase (a marker enzyme for neutrophil infiltration) and extravasation of i.v. administered Evans blue dye (a marker of vascular disruption and increased permeability) were measured. Tissues were also evaluated histologically. The animals received either SC-41930 or vehicle, intrarectally, 30 min after or 1 hr before and 1 hr after the acetic acid. When given 30 min after acetic acid instillation SC-41930 prevented the rise in myeloperoxidase and dye extravasation observed in the acetic acid inflammed tissue. The SC-41930-treated tissues were less edematous and had fewer neutrophils within the subepithelial space. Median effective dose (ED50) values for vascular protection were approximately 20 mg/kg for both rat and guinea pig. ED50 values for inhibition of granulocyte accumulation were 20 mg/kg for rat, 24 mg/kg for guinea pig and 30 mg/kg for rabbit. These data indicate that SC-41930 is effective locally to prevent acute colonic inflammation.

Topics: Animals; Benzopyrans; Capillary Permeability; Colitis; Dose-Response Relationship, Drug; Guinea Pigs; Leukotriene B4; Male; Neutrophils; Peroxidase; Rabbits; Rats; Rats, Inbred Strains; Receptors, Immunologic; Receptors, Leukotriene B4

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.

Topics: Acetates; Acetic Acid; Animals; Colitis; Eicosanoids; Fatty Acids, Essential; Female; In Vitro Techniques; Intestinal Mucosa; Leukotriene B4; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Inbred Strains

The role of leukotrienes in the pathogenesis of chronic colitis was investigated using a rat model. Ulceration and inflammation of the distal colon was initiated by the intracolonic administration of the hapten trinitrobenzene sulfonic acid in 50% ethanol. Leukotriene B4 synthesis increased significantly within 4 h after induction of damage, with the greatest increase observed 24-72 h after administration of the hapten. The increase in leukotriene B4 synthesis correlated well (r = 0.88) with an increase in colonic myeloperoxidase activity, a biochemical marker of neutrophil infiltration. Daily intracolonic treatment with a specific 5-lipoxygenase inhibitor, L651,392, during the first 4 days after initiation of colitis, resulted in significant reductions of colonic leukotriene B4 synthesis, colonic damage score, and colon wet weight. When examined 2 wk after initiation of colitis, the group treated with L651,392 (for the first 4 days) showed significantly less colonic damage (assessed macroscopically and histologically) and colonic inflammation (assessed histologically and by measurement of myeloperoxidase activity). The healing produced by treatment with L651,392 was comparable to that observed after treatment with 5-aminosalicylic acid in a similar manner. Although a reduction of colonic damage could be produced in this model by intracolonic pretreatment with a prostaglandin E1 analogue (rioprostil), the mechanism of action of L651,392 did not appear to be through prevention of the initial injury induced by the hapten and ethanol solution. These results demonstrate that inhibition of leukotriene synthesis results in a marked acceleration of the healing of colonic ulcers and resolution of colonic inflammation in this animal model of chronic colitis. The results are therefore consistent with the hypothesis that leukotrienes play an important role in the pathogenesis of intestinal inflammation.

Topics: 6-Ketoprostaglandin F1 alpha; Aminosalicylic Acids; Animals; Chronic Disease; Colitis; Colon; Leukotriene B4; Lipoxygenase Inhibitors; Male; Mesalamine; Peroxidase; Phenothiazines; Prostaglandins E; Rats; Rats, Inbred Strains; Rioprostil

Topics: Animals; Benzopyrans; Chemical Phenomena; Chemistry; Chemotaxis, Leukocyte; Colitis; Cytoplasmic Granules; Guinea Pigs; Humans; Leukotriene B4; Molecular Structure; Neutrophils; Peroxidase; Receptors, Immunologic; Receptors, Leukotriene B4

Colonic inflammation was induced in rats by intracolonic administration of 0.25 ml of 50% ethanol containing 30 mg of trinitrobenzene sulfonic acid (TNB). Control rats were treated with 0.25 ml of 50% ethanol or with 30 mg of TNB in 0.25 ml of saline. After 24 h, mucosal ulceration and hemorrhage were observed in TNB/ethanol-, 50% ethanol-, and to a lesser extent, in TNB/saline-treated rats. After 1 wk, mucosal damage was completely resolved in the 50% ethanol and TNB/saline-treated rats but the lesions in the TNB/ethanol-treated rats persisted and progressed to a chronic active inflammatory process after 3 wk. Myeloperoxidase activity was significantly elevated in mucosal scrapings from all treatment groups at all time intervals when macroscopic and microscopic mucosal injury was evident. Interleukin-1 was found to be the most sensitive indicator of mucosal inflammation, and its mucosal values correlated with myeloperoxidase activity. Leukotriene B4 was increased in control rats at 1 wk and in TNB/ethanol-treated rats at all time intervals. The maximal increase in leukotriene B4 was observed at 1 wk. Thromboxane B2 generation was reduced while platelet activating factor generation was not increased in TNB/ethanol-treated rats. These results indicate that in this TNB/ethanol model of gut inflammation, myeloperoxidase activity and interleukin-1 are reliable and sensitive indicators of colonic inflammation, and that thromboxane B2 is not involved in the acute lesions, whereas leukotriene B4 appears in the chronic active inflammatory response.

Topics: Animals; Colitis; Colon; Ethanol; Interleukin-1; Intestinal Mucosa; Leukotriene B4; Male; Peroxidase; Platelet Activating Factor; Rats; Rats, Inbred Strains; Thromboxane B2; Trinitrobenzenesulfonic Acid

To compare the local release of arachidonic acid metabolites in inflammatory diarrheal disease, in vivo equilibrium dialysis of the rectum was done in consecutive untreated patients with ulcerative colitis (n = 20), Crohn's colitis (n = 10), and Clostridium difficile colitis (n = 7). All patients had endoscopically proven rectal inflammation. Eicosanoid profiles were determined in rectal dialysates by radioimmunoassay after preliminary purification. Concentrations of prostaglandin E2, prostaglandin F2 alpha, and thromboxane B2, but not 6-keto-prostaglandin F1 alpha, were raised in all groups and compared with healthy controls. The highest levels within each group were obtained in patients with widespread epithelial damage, as judged by endoscopy. In patients with ulcerative colitis, an extreme rise in prostaglandin E2 and thromboxane B2 were observed. Similarly, concentrations of leukotriene B4 were substantially increased in ulcerative colitis, but in Crohn's colitis and Clostridium difficile colitis only those patients with rectal ulcerations showed elevations. These findings probably reflect more severe tissue damages in ulcerative colitis, but differences between disease groups in cell-to-cell interaction may also contribute. The data suggest, therefore, that therapeutic inhibition of lipoxygenase pathways may prove more effective in ulcerative colitis than in Crohn's disease.

Topics: Adolescent; Adult; Aged; Arachidonic Acid; Arachidonic Acids; Colitis; Colitis, Ulcerative; Crohn Disease; Dialysis; Dinoprost; Dinoprostone; Eicosanoic Acids; Enterocolitis, Pseudomembranous; Female; Humans; Leukotriene B4; Male; Middle Aged; Prostaglandins E; Prostaglandins F; Rectum; Thromboxane B2

1. The effects of anti-inflammatory drugs on eicosanoid formation and colonic damage in a chronic model of inflammatory bowel disease (IBD) in the rat were investigated. 2. A single colonic instillation of the hapten, trinitrobenzene sulphonic acid (TNB) resulted in ulceration and inflammation which persisted for 3 weeks. 3. The macroscopic colonic damage, present 3 weeks after TNB, was correlated with an increase in immunoreactive 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and leukotriene B4 (LTB4) synthesis by the rat colon. 4. Anti-inflammatory drugs were administered 2 weeks after TNB, when there was substantial colonic damage, and continued for a week. The experimental drug BW755C inhibited the increased formation of 6-keto-PGF1 alpha and LTB4 by the inflamed colon. Indomethacin and aspirin markedly inhibited prostanoid formation in both inflamed and control colon. Sulphasalazine or prednisolone also inhibited the formation of 6-keto-PGF1 alpha but the effects were less marked. 5. None of the anti-inflammatory drugs significantly reduced the colonic damage induced by TNB. 6. The results suggest that eicosanoids, including LTB4, have only a minor role in maintaining the chronic macroscopic damage induced in the rat colon by TNB. The role of such eicosanoids in the underlying infiltration and activity of inflammatory cells in this model of IBD, however, is not known.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anti-Inflammatory Agents; Colitis; Eicosanoic Acids; In Vitro Techniques; Leukotriene B4; Male; Radioimmunoassay; Rats; Rats, Inbred Strains

The role of increased prostaglandin production and the effects of exogenous prostaglandins on inflammation of colitis are not established. We administered intramuscular 16,16-dimethyl prostaglandin E2 (DiM-PGE2) and indomethacin to rabbits with formalin immune-complex colitis and measured leukotriene B4 (LTB4), prostaglandin E2 (PGE2) and severity of inflammation. DiM-PGE2 (100 micrograms/kg/BID) reduced LTB4 production (from 401 +/- 108 to 216 +/- 58 pg/ml) and infiltration of neutrophils, mucosal necrosis, inflammatory exudate and edema (all P less than 0.05). Other studies determined that parenteral DiM-PGE2 did not reduce the initial chemical damage induced by formalin, suggesting that cytoprotection of chemical insult was not the mechanism of suppressed inflammation in the immune colitis model. Indomethacin (10 mg/kg/d) reduced endogenous PGE2 by 80%, but did not reduce leukotriene production or inflammation. Exogenous prostaglandins cause a dose-dependent suppression of inflammation in experimental colitis, by a mechanism other than cytoprotection of chemical-induced mucosal injury.

Topics: Animals; Colitis; Colon; Dinoprostone; Dose-Response Relationship, Drug; Indomethacin; Leukotriene B4; Male; Necrosis; Prostaglandins E, Synthetic; Rabbits

Topics: Animals; Colitis; Leukotriene B4; Rabbits; SRS-A

Leukotriene B4, a proinflammatory compound, recently has been identified as the major metabolite of arachidonic acid in tissue incubations of human and animal colitis. To determine the relationship of inflammation to the in vivo production of leukotrienes, rabbit colitis was induced by formalin enema followed by intravenous infusion of immune complexes, and serial samples were collected by rectal dialysis. Leukotrienes B4 and C4 were measured by radioimmunoassay after high-pressure liquid chromatography. Prostaglandin E2 was assayed after Sephadex chromatography. Leukotrienes were not detected in control animals. Eicosanoid production progressively increased during development of inflammation and correlated with severity of inflammatory cell infiltration (p less than 0.01). Methylprednisolone decreased prostaglandin E2 but did not significantly reduce leukotrienes or inflammation. These data demonstrate that in vivo production of leukotrienes B4 and C4 correlates with indices of inflammation, consistent with the concept that these eicosanoids contribute to the inflammation of colitis.

Topics: Animals; Chromatography, High Pressure Liquid; Colitis; Dinoprostone; Intestinal Mucosa; Leukotriene B4; Male; Methylprednisolone; Prostaglandins E; Rabbits; Radioimmunoassay; SRS-A