Antiinflammatory effects of various drugs on acetic acid induced colitis in the rat

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

The effect of leukotriene-B4 receptor antagonist,SC-41930, on acetic acid-induced colonic inflammation

SC-41930, 7-[3-(4-acetyl-3-methoxy-2-propylphenoxy)-propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-carboxylic acid, is a potentin vitro leukotriene-B₄ (LTB₄) receptor antagonist. LTB₄ levels are elevated in colonic tissue of inflammatory bowel disease (IBD) patients which may account for the high degree of neutrophil (PMN) infiltration. The guinea pig acetic acid-induced colonic inflammation model has characteristics of IBD including PMN infiltration, edema, ulceration and necrosis. The model was used to evaluate the effect of SC-41930. SC-41930 was given orally, 30 min before and after intrarectal administration of 3% acetic acid. The PMN marker enzyme, myeloperoxidase, was measured along with histological evaluation to assess inflammation. Both parameters showed significantly less inflammation in SC-41930 treated animals with an oral ED₅₀ of 20 mg/kg. These study results with an LTB₄ receptor antagonist indicate a role for LTB₄ in colonic inflammation and that an LTB₄ receptor antagonist may be beneficial for treatment of IBD.     

Colonic inflammation in the rabbit induced by phorbol-12-myristate-13-acetate

Neutrophil (PMNL) infiltration of inflamed colonic tissue is a prominent feature of human inflammatory bowel disease (IBD). Colitis was established in New Zealand white rabbits by the intrarectal instillation of 1.5 mg/kg (in 10 ml 20% ethanol) phorbol-12-myristate-13-acetate (PMA) and assessed by visual grading of colonic inflammation, levels of the neutrophil marker enzyme myeloperoxidase (MPO), and histological examination. After 24 h there was a significant (P<0.001) increase in MPO levels in the PMA-treated colons compared to ethanol control. There was also increased inflammation based on visual scoring. Histologically, PMA-treated colons were necrotic with focal ulceration, heavy PMNL infiltration and edema at 24 h; by 96 h colitis was sustained with mild edema, crypt abscesses, and a staining pattern suggesting altered mucus quality. These results suggest that PMA-induced colitis in rabbits may be a new model of IBD in which to evaluate drugs known to mitigate the inflammatory process.     

5-Lipoxygenase modulates colitis through the regulation of adhesion molecule expression and neutrophil migration

Leukotrienes play a part in inflammatory response. The unique role of the enzyme 5-lipoxygenase (5-LO) in the production of leukotrienes makes it as therapeutic target for inflammatory conditions like inflammatory bowel disease (IBD). In the present study, by comparing the responses in wild-type mice (5-LOWT) and mice lacking the 5-lipoxygenase (5-LOKO), we investigated the role played by this enzyme in the development of experimental colitis. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). When compared to DNBS-treated 5-LOWT mice, DNBS-treated 5-LOKO mice experienced a reduced rate of the extent and severity of the histological signs of colon injury. After administration of DNBS 5-LOWT mice showed hemorrhagic diarrhea, weight loss and large areas of necrosis in the mucosa of the colon. Neutrophil infiltration was associated with the expression of ICAM-1, VCAM-1, P-selectin, E-selectin that were mainly localized around vessels. Absence of a functional 5-LO resulted in a significant reduction of all the above-described parameters. In particular, we have observed a significant reduction of: (i) the degree of colon injury, (ii) the rise in myeloperoxidase (MPO) activity (mucosa), (iii) the increase in staining (immunohistochemistry) for ICAM-1, VCAM-1, P-selectin, E-selectin caused by DNBS in the colon. Similarly, the treatment of 5-LOWT with zileuton (50 mg/kg per os twice a day) resulted in a significant reduction of all the above-described parameters. In addition, in in vitro study a significantly reduced chemotactic response to IL-8 was observed in peripheral blood leukocytes from 5-LOKO in comparison to 5-LOWT polymorphonuclear leukocyte. Similar results were obtained when we analyzed the chemotactic response of 5-LOWT cell incubated for 15 min with zileuton (50 microg/ml). Taken together, our results clearly demonstrate that 5-LO modulates neutrophil infiltration in experimental colitis through the expression of adhesion molecules.     

The selective nonpeptide CXCR2 antagonist SB225002 ameliorates acute experimental colitis in mice

Although neutrophils are strongly implicated in eliminating pathogens, excessive recruitment may cause tissue damage. Therefore, reducing cell influx during an inflammatory process may be a potential target for treating inflammatory bowel diseases (IBD). As CXCR2 is involved in neutrophil migration, this study aimed to evaluate whether the systemic therapeutic treatment with selective CXCR2 antagonist SB225002 ameliorates experimental colitis, which was induced in mice by 2,4,6-trinitrobenzene sulfonic acid (TNBS). After colitis establishment (24 h), mice were treated with SB225002. At later time-points, up to 72 h, mice were monitored for body weight loss and overall mortality. At the time of sacrifice, colonic tissues were scored for macro- and microscopic damage, and cytokine levels, myeloperoxidase (MPO) activity, and protein expression were analyzed. TNBS administration induced macro- and microscopic damage in colon tissue, leading in most cases to animal death. Curative treatment with SB225002 significantly reduced all of the parameters analyzed, leading to an improvement of inflammatory signs. SB225002 reduced neutrophil influx, MPO activity, IL-1beta, MIP-2, and keratinocyte-derived chemokine (KC) levels and the expression of vascular endothelial growth factor, inducible NO synthase, and cyclooxygenase-2 proteins into the colon tissue. Levels of IL-4 and IL-10 were increased significantly in the colons of animals treated with SB225002. Additionally, curative treatment with mouse anti-KC significantly reduced MPO activity and colonic damage. These results taken together demonstrate that a selective blockade of CXCR2 consistently reduced TNBS-induced colitis, suggesting that the use of SB225002 is a potential therapeutic approach for the treatment of IBD and other related inflammatory disorders.     

Role of neutrophils in acetic acid-induced colitis in rats

Intrarectal administration of 4% acetic acid produces diffuse inflammation that ultimately results in erosions and ulcerations of the rat colon. Although this model of colitis has been used extensively over the past several years, there are no quantitative data available regarding the relationship between neutrophil infiltration and mucosal injury during times of active inflammation. Therefore, the objective of this study was to define the role of extravasated neutrophils as mediators of mucosal injury and inflammation in acetic acid-induced colitis. We found the intrarectal administration of 4% acetic acid produced an 11-fold increase in colonic mucosal permeability, a 9-fold increase in colonic MPO activity, and a 1.6-fold increase in colon weight at 48 h following administration of acetic acid. In addition, we found significant correlations between colonic MPO activity and mucosal permeability and between colonic MPO activity and colon weight (P < 0.01 for both). These data suggested that inflammatory neutrophils may mediate mucosal injury and inflammation in this model of colitis. To assess the role of circulating neutrophils, rats were rendered neutropenic for 48 h by the intraperitoneal administration of antiserum directed toward rat neutrophils (ANS). Although ANS treatment reduced both the number of circulating neutrophils and colonic MPO activity to less than 10% of control values, it did not attenuate the increases in colonic mucosal permeability nor did it attenuate the increases in colon weight produced by acetic acid. Histological inspection confirmed that ANS treatment was not effective in attenuating the injury to the epithelial barrier. These data demonstrate that infiltrating neutrophils do not mediate the mucosal injury and inflammation observed in acetic acid-induced colitis.This work was supported by grants from the NIH (DK39168), Crohn's and Colitis Foundation of America and Pharmacia LEO Therapeutics (Uppsala, Sweden).     

Crucial pathophysiological role of CXCR2 in experimental ulcerative colitis in mice

Polymorphonuclear leukocyte infiltration and activation into colonic mucosa are believed to play a pivotal role in mediating tissue damage in human ulcerative colitis (UC). Ligands of human CXC chemokine receptor 1 and 2 (CXCR1/R2) are chemoattractants of PMN, and high levels were found in the mucosa of UC patients. To investigate the pathophysiological role played by CXCR2 in experimental UC, we induced chronic experimental colitis in WT and CXCR2(-/-) mice by two consecutive cycles of 4% dextran sulfate sodium administration in drinking water. In wild-type (WT) mice, the chronic relapsing of DSS-induced colitis was characterized by clinical signs and histopathological findings that closely resemble human disease. CXCR2(-/-) mice failed to show PMN infiltration into the mucosa and, consistently with a key role of PMN in mediating tissue damage in UC, showed limited signs of mucosal damage and reduced clinical symptoms. Our data demonstrate that CXCR2 plays a key pathophysiological role in experimental UC, suggesting that CXCR2 activation may represent a relevant pharmacological target for the design of novel pharmacological treatments in human UC.     

Organic peroxides inhibit neutrophil leukotriene B4 biosynthesis.

Leukotriene B4, an autacoid metabolite of arachidonic acid produced by polymorphonuclear neutrophils, induces chemokinesis, chemotaxis, and adhesion of these cells at sites of inflammation. Because neutrophil infiltration is a self-limited process, we hypothesized that oxidized lipid products of neutrophil-damaged tissue might inhibit leukotriene B4 biosynthesis, thereby preventing additional neutrophil infiltration and limiting peroxidative tissue damage. Erythrocyte ghosts exposed to a hydrogen peroxide-generating system served as a model of peroxidized tissue in inflammation and inhibited neutrophil leukotriene B4 production by 50% compared with unoxidized ghosts. Organic peroxides, including tert-butylhydroperoxide, peracetic acid, and linoleic hydroperoxide, resembling the product(s) of tissue membrane peroxidation in lipid solubility and catalase resistance, inhibited leukotriene B4 biosynthesis in a dose-dependent manner (50% inhibitory concentration of 3.9 microM compared to 530 microM for H2O2). Biosynthetic steps prior to the 5-lipoxygenase did not appear to be the site of inhibition. Likewise, the step after the 5-lipoxygenase, the leukotriene A4 hydrolase, was not primarily involved. Thus a possible mechanism for controlling the influx of neutrophils and their oxidative damage during inflammation may be inhibition of the 5-lipoxygenase by catalase-resistant lipid peroxides released by tissue membranes.     

The effect of the cholinergic anti-inflammatory pathway on experimental colitis

Inflammatory bowel diseases (IBD) are characterized by proinflammatory cytokines, tissue damage and loss of neuron in inflamed mucosa, which implies the cholinergic anti-inflammatory pathway may be destroyed during the process of inflammatory response. In the study, we identified the effect of cholinergic agonist as anabaseine (AN) and nicotinic receptor antagonist as chlorisondamine diiodide (CHD) on trinitrobenzene sulfonic acid (TNBS)-induced colitis, to investigate the potential therapeutic effect of the cholinergic anti-inflammatory pathway on IBD. Experimental colitis was induced by TNBS at day 1, 10 mug AN or 1.5 mug CHD was injected i.p. to mouse right after the induction of colitis, and repeated on interval day till the mice were sacrificed at day 8. Colonic inflammation was examined by histological analysis, myeloperoxidase (MPO) activity, and the production of tumour necrosis factor (TNF)-alpha in tissue. Lamina propria mononuclear cells (LPMC) were isolated, and NF-kappaB activation was detected by western blot. The mice with colitis treated by AN showed less tissue damage, less MPO activity, less TNF-alpha production in colon, and inhibited NF-kappaB activation in LPMC, compared with those mice with colitis untreated, whereas the mice with colitis treated by CHD showed the worst tissue damage, the highest MPO activity, the highest TNF-alpha level, and enlarged NF-kappaB activation in LPMC. Agonist of the cholinergic anti-inflammatory pathway inhibits colonic inflammatory response by downregulating the production of TNF-alpha, and inhibiting NF-kappaB activation, which suggests that modulating the cholinergic anti-inflammatory pathway may be a new potential management for IBD.     

Effects of intrarectal and intraperitoneal N(G)-nitro-L-arginine methyl ester treatment in 2,4,6-Trinitrobenzenesulfonic acid induced colitis in rats

Inflammatory bowel disease (IBD) has been associated with an increased generation of nitric oxide (NO). Different authors have shown that NO in IBD can be either harmful or protective. The aim of this study was to investigate the efficiency of intrarectal (i.r.) and intraperitoneal (i.p.) application of N(G)-nitro-L-arginine methyl ester (L-NAME), a non-specific nitric oxide synthase inhibitor, in experimental acute colitis in the rats. Acute colitis was induced in rats by 2,4,6-trinitrobenzenesulfonic acid (TNBS) and ethanol. Twenty-eight rats were divided into four groups. L-NAME (50 mg/kg/day) was administered i.p. (Group 1) and i.r. (Group 2) for 7 days following the day when colitis was induced. Group 3 rats were not given any treatment after induction of colitis. Control group rats were given saline solution i.r. instead of TNBS. The presence of hyperemia, inflammation and ulcer was evaluated to score of macroscopic morphologic damage. The severity of colitis was assessed by microscopic criteria including ulceration, mucus cell depletion, crypt abscesses, inflammatory cysts, mucosal atrophy, edema, inflammatory cell infiltration, and vascular dilatation. Rectal tissue myeloperoxidase (MPO) activity and serum-rectal tissue nitrite levels were measured. Serum and rectal tissue nitrite levels increased in Group 3 rats. Both i.p. and i.r. L-NAME treatment significantly reduced serum and rectal tissue nitrite levels, but no effect on MPO activity and histologic damage score was observed. Under the present conditions we concluded i.r. and i.p. L-NAME treatment, applied at the dosage of 50 mg/kg/day, does not have any protective effect on the colonic injury.     

Induction of iNOS in a Rat Model of Acute Colitis

Induction of colitis by 2,4,6-Trinitrobenzenesulphonic acid (TNB) in the rat is a widely used experimental model of inflammatory bowel disease. Action of TNB as a hapten, induces colitis involving infiltration of colonic mucosa by neutrophils and macrophages and increased production of inflammatory mediators. The aim of the present study was to measure nitric oxide synthase (NOS) activity and characterize relations between inducible NOS (iNOS) activity and other signs of inflammation in TNB-induced colitis. A profound and sustained increase in the activity of iNOS was found in the colon. The activity of NOS in the spleen was also increased, but remained at low levels as compared to those in colon. No increases in plasma nitrite + nitrate concentrations were found suggesting local rather than systemic induction of iNOS. The increase in iNOS activity in the colon was preceded by macroscopic inflammatory lesions, like hyperemia, ulcerations and edema formation as well as neutrophil accumulation in the gastric mucosa and increased circulating concentrations of PGE₂ metabolite (PGEM). Concentrations of PGEM in the plasma and myeloperoxidase activity (MPO; marker of neutrophil infiltration) in the gut declined in 48h whereas increased iNOS activity and the macroscopic inflammatory lesions remained over the 72h follow-up period. The results demonstrate increased local iNOS activity in TNB-Induced colitis mimicking the situation in human inflammatory bowel disease.     

The COX-2 inhibitor, rofecoxib, ameliorates dextran sulphate sodium induced colitis in mice

Objective: We have evaluated the efficacy of the selective cyclo-oxygenase (COX)-2 inhibitor, rofecoxib, for the prevention of experimental colitis.Material and methods: To induce colitis BALB/c mice received 5% dextran sulphate sodium (DSS) in their drinking water continuously for 7 days. Rofecoxib (2.5–10 mg/kg body weight, p.o.) was administered throughout the treatment period with DSS. Colitis was quantified by a clinical damage score, colon length, weight loss, stool consistency and rectal bleeding. Inflammatory response was assessed by neutrophil infiltration, determined by histology and myeloperoxidase (MPO) activity. Interleukin (IL)-1, prostaglandin (PG)E₂ and PGD₂ levels in colon mucosa and the immunohistochemical expression of COX-1 and –2 were also studied.Results: The COX-2 inhibitor ameliorated severe colitis, reduced the degree of inflammation through reduction of neutrophil infiltration and IL-1 levels. PGE₂, and PGD₂ synthesis were significantly reduced in DSS-treated groups. Indeed, treatment with rofecoxib diminished the lost of COX-1 caused by DSS in the crypt epithelium whereas expression of COX-2 remained unaffected.Conclusions: Rofecoxib is protective in acute DSS – induced colitis, probably by reducing neutrophil infiltration, inhibiting up-regulation of IL-1 and returning to normal COX-1 expression in the inflamed colonic mucosa.Received 19 April 2004; returned for revision 17 June 2004; accepted by I. Ahnfelt-Rønne 23 November 2004     

Cytosolic phospholipase A2α has a crucial role in the pathogenesis of DSS‐induced colitis in mice

Colitis, an inflammation of the colon, is a well‐characterized massive tissue injury. Cytosolic phospholipase A₂α (cPLA₂α) upregulation plays an important role in the development of several inflammatory diseases. The aim of the present study was to define the role of cPLA₂α upregulation in the development of colitis. We used a mouse model of dextran sulfate sodium induced colitis. Immunoblotting analysis showed that cPLA₂α and NF‐κB were upregulated and activated in the colon from day 2 of colitis induction. This molecular event preceded the development of the disease, as determined by Disease Activity Index score, body weight, colon length, and the expression of colonic inflammatory markers, including neutrophil infiltration detected by myeloperoxidase and by NIMP‐R14, ICAM‐1, COX‐2, iNOS upregulation and LTB₄ and TNF‐α secretion. Prevention of cPLA₂α upregulation and activity in the colon by i.v. administration of specific antisense oligonucleotides against cPLA₂α 1 day prior and every day of exposure to dextran sulfate sodium significantly impeded the development of the disease and prevented NF‐κB activation, neutrophils infiltration into the colonic mucosa, and expression of proinflammatory proteins in the colon. Our results demonstrate a critical role of cPLA₂α upregulation in inflammation and development of murine colitis.     

Prevention and suppression of experimental allergic encephalomyelitis by an orally active leukocyte recruitment inhibitor,NPC 16570

The therapeutic efficacy of the leukocyte recruitment inhibitor, NPC 15669 (N-[9H-(2,7-dimethylfluoren-9-yl-methoxy)carbonyl]-l-leucine), was evaluated through the time course of acetic acid colitis in rats. Intrarectal (i.r.) administration of dilute acetic acid produced intense inflammation of the colon, neutrophil infiltration, hemorrhage, necrosis and denuding of epithelium. Myeloperoxidase (MPO) accumulation increased ∼40-fold (by day 1) and significant resolution of the disease occurred by day 9. When NPC 15669 (10 mg/kg, i.r.) was administered 24 h after acid, MPO accumulation and colonic lesion scores were significantly inhibited (days 3–9) and histological examination revealed the absence of hemorrhage, epithelial cell regeneration and complete restoration of the mucosal architecture. Thus, NPC 15669 prevents colonic damage and promotes healing of ulcers, even when administered at the peak of the inflammatory response.

     

5-Lipoxygenase inhibitors for the treatment of inflammatory bowel disease

The unique role of the enzyme 5-lipoxygenase (5-LO) in the production of leukotrienes (LTs) makes it a likely target for biochemical manipulation. The rationale for using 5-LO inhibitors for the treatment of inflammatory bowel disease (IBD) is based on the increased generation of LTs in the inflamed mucosa, LTB₄ being the most potent chemotactic and chemokinetic metabolite of arachidonic acid. Furthermore, conventional drugs, such as corticosteroids, sulphasalazine, and 5-aminosalicylic acid, inhibit LT production and specific 5-LO inhibition accelerates healing in animal models of acute colitis. The compounds identified as 5-LO inhibitors can be divided into antioxidants, substrate-analogous, and a large miscellaneous group of inhibitors, where hydroxamic acids are potent and more selective inhibitors of 5-LO. The benzothiophene hydroxyurea, zileuton, is the first selective 5-LO inhibitor evaluated for the treatment of patients with IBD. An 800-mg oral dose of zileuton was shown to reduce LTB₄, but not prostaglandin E₂, concentrations by 75–85% in rectal dialysates from patients with active ulcerative colitis. The clinical efficacy of zileuton 800 mg b.i.d. has also been tested in a randomized, double-blind, placebo-controlled trial in similar patients. Zileuton significantly improved the symptom scores and the histology score, but not the sigmoidoscopy score, compared to pretreatment conditions and with response to placebo, the beneficial effects being most pronounced in patients not receiving concomitant sulphasalazine treatment. The mean inhibition of LTB₄ in the target tissue of inflammation was 70%. The proof that any putative 5-LO inhibitor is blocking LT production is an important stage in assessing any such drug. The main disadvantage of existing new LT inhibitors relates to the high potency of LTs, and unless a higher level of inhibition can be achieved, endogenous LTs may still be present in sufficient amounts to produce their effects.     

5-Lipoxygenase inhibitors for the treatment of inflammatory bowel disease

The unique role of the enzyme 5-lipoxygenase (5-LO) in the production of leukotrienes (LTs) makes it a likely target for biochemical manipulation. The rationale for using 5-LO inhibitors for the treatment of inflammatory bowel disease (IBD) is based on the increased generation of LTs in the inflamed mucosa, LTB₄ being the most potent chemotactic and chemokinetic metabolite of arachidonic acid. Furthermore, conventional drugs, such as corticosteroids, sulphasalazine, and 5-aminosalicylic acid, inhibit LT production and specific 5-LO inhibition accelerates healing in animal models of acute colitis. The compounds identified as 5-LO inhibitors can be divided into antioxidants, substrate-analogous, and a large miscellaneous group of inhibitors, where hydroxamic acids are potent and more selective inhibitors of 5-LO. The benzothiophene hydroxyurea, zileuton, is the first selective 5-LO inhibitor evaluated for the treatment of patients with IBD. An 800-mg oral dose of zileuton was shown to reduce LTB₄, but not prostaglandin E₂, concentrations by 75–85% in rectal dialysates from patients with active ulcerative colitis. The clinical efficacy of zileuton 800 mg b.i.d. has also been tested in a randomized, double-blind, placebo-controlled trial in similar patients. Zileuton significantly improved the symptom scores and the histology score, but not the sigmoidoscopy score, compared to pretreatment conditions and with response to placebo, the beneficial effects being most pronounced in patients not receiving concomitant sulphasalazine treatment. The mean inhibition of LTB₄ in the target tissue of inflammation was 70%. The proof that any putative 5-LO inhibitor is blocking LT production is an important stage in assessing any such drug. The main disadvantage of existing new LT inhibitors relates to the high potency of LTs, and unless a higher level of inhibition can be achieved, endogenous LTs may still be present in sufficient amounts to produce their effects.     

Transgenic over-expression of macrophage migration inhibitory factor renders mice markedly more susceptible to experimental colitis

Enhanced production of macrophage migration inhibitory factor (MIF) is recognized in patients with inflammatory bowel disease (IBD) and mice with experimental colitis; however, the precise molecular function of MIF in colitis is not fully understood. To further investigate this matter, we examined the pathological features of MIF transgenic mice with dextran sulphate sodium (DSS)-induced colitis. We generated transgenic mice carrying a murine MIF cDNA driven by a cytomegalovirus enhancer and a beta-actin/beta-globin promoter. Mice were orally administered 1-4% DSS in drinking water for 7 days. Clinical disease activity, survival and histological features were evaluated. The level of myeloperoxidase (MPO) activity in the colon tissue was measured to assess neutrophil infiltration. The level of corticosterone in the serum was measured by enzyme linked-immunosorbent assay (ELISA). MIF mRNA and protein were markedly up-regulated in the colon and serum obtained from MIF transgenic mice. The severity of the colitis induced by 1% DSS treatment was markedly higher in MIF transgenic mice than in wild-type mice. We also found that MPO activity was significantly higher in MIF transgenic mice than wild-type mice in response to DSS stimulation. Interestingly, the corticosterone level remained unchanged in MIF transgenic mice. MIF enhances DSS-induced colitis, in part via neutrophil accumulation and inhibition of glucocorticoid bioactivity.     

Pharmacological activity of the second generation leukotriene B4 receptor antagonist,SC-53228:

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. SC-53228(+)-(S)-7-[3-[2(-cyclopropylmethyl)-3-methoxy-4-[(methylamino)carbonyl]phenoxy]propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2-propanoic acid, a second generation LTB₄ receptor antagonist, was evaluated for therapeutic efficacy in a rodent model of acute colonic inflammation induced by short chain organic acids, as well as for effects on rodent liver. When given intracolonically to mice, SC-53228 inhibited neutrophil infiltration, assessed by myeloperoxidase (MPO) levels, with an ED₅₀ value of 9±1.2 mg/kg. When given by gavage, SC-53228 inhibited neutrophil influx in colitic mice with an ED₅₀ value of 30 mg/kg. These results were also confirmed histologically. Furthermore, high dose oral SC-53228 treatment had no effect on liver cytochrome P-450 content, fatty acyl CoA oxidase or liver weight in rats and mice. Together, these data suggest that SC-53228 may be efficacious orally and locally, as well as safe for use in trials for the medical management of IBD.     

阿魏酸钠对结肠炎大鼠结肠巨噬细胞功能的影响

目的:探讨阿魏酸钠在整体水平下对结肠炎大鼠结肠巨噬细胞功能的影响及其机制。方法:建立大鼠免疫性结肠炎模型。阿魏酸钠(SF)灌肠用药21d后检测结肠组织MDA、NO、PGE₂含量,SOD、IL-1、TNF-α、MPO活性及NF-κBp65表达水平。结果:阿魏酸钠(200、400、800mg/kg)灌肠用药剂量依赖性降低模型组大鼠显著升高的MDA、NO、PGE₂含量,IL-1、TNF-α、MPO活性及NF-κBp65表达水平,同时升高显著降低的SOD活性。结论:SF整体水平下减弱结肠炎大鼠结肠活化巨噬细胞的生物活性,缓解结肠炎症反应,机制可能与抑制NF-κB表达有关。     

Treatment with bindarit, an inhibitor of MCP-1 synthesis, protects mice against trinitrobenzene sulfonic acid-induced colitis

OBJECTIVE: Chemokines play a fundamental role in trafficking and activation of leukocytes in colonic inflammation. We investigated the ability of bindarit, an inhibitor of monocyte chemoattractant protein-1 (MCP-1/CCL2) synthesis, to inhibit chemokine production by human intestinal epithelial cells (HT-29) and its effect in trinitro-benzene sulfonic acid (TNBS)-induced colitis in mice.MATERIALS AND METHODS: HT-29 cells were incubated with bindarit in the presence of TNF-alpha/IFN-gamma and 24 h later supernatants were collected for MCP-1, IL-8 and RANTES measurement. A 1 mg enema of TNBS was given to BALB/c mice, and bindarit (100 mg/kg) was orally administered twice daily starting from two days before colitis induction. Weight loss, histology, and MCP-1 level and myeloperoxidase (MPO) activity in colon extracts were assessed.RESULTS: In HT-29 cells, bindarit concentration-dependently and selectively inhibited MCP-1 secretion (as well as mRNA expression) primed by TNF-alpha/IFN-gamma. Moreover treatment with bindarit reduced clinical and histopathological severity of TNBS-induced colitis. These effects were associated with significant inhibition of MCP-1 and MPO in colon extracts.CONCLUSIONS: Bindarit exhibits a potent bioactivity in reducing leukocyte infiltration, down-regulating MCP-1 synthesis, and preventing the development of severe colitis in a mice model of TNBS-induced colitis. These observations suggest a potential use of MCP-1 synthesis blockers in intestinal inflammation in humans.