Implication of TNF-alpha convertase (TACE/ADAM17) in inducible nitric oxide synthase expression and inflammation in an experimental model of colitis

Tumour necrosis factor-alpha (TNF-alpha) is a pro-inflammatory cytokine which is shed in its soluble form by a disintegrin and metalloproteinase (ADAM) called TNF-alpha convertase (TACE; ADAM17). TNF-alpha plays a role in inflammatory bowel disease (IBD) and is involved in the expression of inducible nitric oxide synthase (iNOS) which has also been implicated in IBD. The study was designed to investigate whether colitis induced by trinitrobenzene sulphonic acid (TNBS) in rats produces an increase in TACE activity and/or expression and whether its pharmacological inhibition reduces TNF-alpha levels, iNOS expression and colonic damage in this model. TNBS (30 mg in 0.4 ml of 50% ethanol) was instilled into the colon of female Wistar rats. Saline or TACE inhibitor BB1101 (10 mg/kg/day) was administered intraperitoneally 5 days after TNBS instillation. On day 10, colons were removed and assessed for pathological score, myeloperoxidase (MPO), NO synthase (NOS), TACE enzymatic activity and protein levels, colonic TNF-alpha and NOx- levels. Instillation of TNBS caused an increase in TACE activity and expression and the release of TNF-alpha. TNBS also resulted in iNOS expression and colonic damage. BB1101 blocked TNBS-induced increase in TACE activity, TNF-alpha release and iNOS expression. Concomitantly, BB1101 ameliorated TNBS-induced colonic damage and inflammation. TNBS causes TNF-alpha release by an increase in TACE activity and expression and this results in the expression of iNOS and subsequent inflammation, suggesting that TACE inhibition may prove useful as a therapeutic means in IBD.     

A protective effect of the synthetic coumarine derivative Cloricromene against DNB-colitis in the rat

Biologic therapies, namely antibodies against tumor necrosis factor-alpha (TNF- alpha) or its receptors, have been recently introduced for the treatment of patients with inflammatory bowel disease (IBD). In the present study the effects of cloricromene, an agent with known antithrombotic actions and with demonstrated anti-TNF- alpha activity were investigated in a rat model of experimental colitis induced with dinitrobenzenesulphonic acid (DNB)/ethanol. We investigated three experimental groups: (i) sham-colitis with vehicle-treatment (controls, n = 6), (ii) colitis with vehicle-treatment (saline, 0.1 ml s.c., daily) (DNB-V, n = 7), (iii) colitis with cloricromene-treatment (10 mg/kg/day s.c.; DNB-C, n = 8). After 7 days, the weight gain, colon wet weight, macroscopic damage score, coagulation parameters, colon mucosal myeloperoxidase activity (MPO), and tissue concentrations of TNF- alpha and of macrophage inhibitory peptide-2 (MIP-2) were assessed. The macroscopic damage scores, colon wet weights, and tissue MIP-2 levels were significantly increased in untreated and in cloricromene-treated rats compared with controls. Cloricromene treatment was associated with a minor body weight loss (p < 0.025) and significantly reduced tissue concentrations of MPO and TNF-alpha (p < 0.02, both). Blood coagulation parameters were not affected by treatment. In the DNB-model treatment with cloricromene effectively reduces tissue levels of TNF- alpha and of myeloperoxidase, whereas MIP-2 concentrations were not influenced. Blood coagulation parameters remained unchanged indicating safety of treatment. Since biological therapies frequently fail to improve disease course of IBD, other therapies with similar targets should be further investigated.     

Endothelin in human inflammatory bowel disease: comparison to rat trinitrobenzenesulphonic acid-induced colitis

There have been suggestions that endothelins (ET-1, ET-2, ET-3) are involved in the pathogenesis of human inflammatory bowel disease (IBD). Furthermore, the non-selective endothelin receptor antagonist, bosentan, ameliorates colonic inflammation in TNBS colitis in rats. However, no studies have measured the tissue expression and release of endothelins in human IBD in direct comparison to experimental TNBS colitis. Mucosal biopsies were obtained from 114 patients (42 Crohn's colitis, 35 ulcerative colitis and 37 normal) and compared to whole colonic segments from rats with TNBS colitis. ET-1/2 levels were reduced in human IBD but greatly increased in experimental TNBS colitis. RT-PCR indicated ET-2 was the predominant endothelin isoform in human IBD whereas ET-1 prevailed in the TNBS model. No associations were found between human IBD and tissue expression, content or release of ET-1/2. Our study shows, therefore, that unlike TNBS colitis in rats, in which ET-1/2 levels are greatly elevated and ET receptor antagonists are efficacious, there is no significant link between endothelins and human IBD.     

Estrogen receptor-β signaling modulates epithelial barrier function

Impaired epithelial barrier function and estrogens are recognized as factors influencing inflammatory bowel disease (IBD) pathology and disease course. Estrogen receptor-β (ERβ) is the most abundant estrogen receptor in the colon and a complete absence of ERβ expression is associated with disrupted tight-junction formation and abnormal colonic architecture. The aim of this study was to determine whether ERβ signaling has a role in the maintenance of epithelial permeability in the colon. ERβ mRNA levels and colonic permeability were assessed in IL-10-deficient mice and HLA-B27 rats by RT-PCR and Ussing chambers. ERβ expression and monolayer resistance were measured in HT-29 and T84 colonic epithelial monolayers by RT-PCR and electric cell-substrate impedance sensing. The effect of 17β-estradiol and an estrogen agonist [diarylpropionitrile (DPN)] and antagonist (ICI 182780) on epithelial resistance in T84 cells was measured. Expression of ERβ and proinflammatory cytokines was investigated in colonic biopsies from IBD patients. Levels of ERβ mRNA were decreased, whereas colonic permeability was increased, in IL-10-deficient mice and HLA-B27 transgenic rats prior to the onset of colitis. T84 cells demonstrated higher resistance and increased levels of ERβ mRNA compared with HT-29 cells. 17β-estradiol and DPN induced increased epithelial resistance in T84 cells, whereas an ERβ blocker prevented the increased resistance. Decreased ERβ mRNA levels were observed in colonic biopsies from IBD patients. This study suggests a potential role for ERβ signaling in the modulation of epithelial permeability and demonstrates reduced ERβ mRNA in animal models of colitis and colon of patients with inflammatory bowel disease.     

Efficacy of Setarud (IMod), a novel drug with potent anti-toxic stress potential in rat inflammatory bowel disease and comparison with dexamethasone and infliximab

The inflammatory bowel disease (IBD) is an idiopathic, immune-mediated and chronic intestinal condition. In the present study, the effect of Setarud (IMOD), a novel natural drug with known immunomodulatory, anti-inflammatory and antioxidant properties was investigated in experimental colitis in rats and compared with the dexamethasone and infliximab. Immunologic colitis was induced by intracolonic administration of a mixture of trinitrobenzene sulfonic acid (TNBS) and absolute ethanol in male Wistar rats. Animals were divided into 6 groups of sham (normal group), control (vehicle-treated), positive control (dexamethasone 1 mg/kg/day given orally and infliximab 5 mg/kg/day given subcutaneously) and 3 Setarud-treated groups (13.3, 20, 30 mg/kg/day given intraperitoneally). The treatment continued for 14 consecutive days and then animals were decapitated on the day 15 and distal colons were removed for macroscopic, microscopic, and biochemical assays. Biochemical markers, including TNF-alpha, IL-1beta, ferric reducing/antioxidant power (FRAP), myeloperoxidase (MPO) activity and thiobarbitoric acid-reactive substance (TBARS) were measured in the homogenate of colonic tissue. A remarkable reduction in macroscopic and histological damage scores was observed in the animals treated with Setarud. These findings were confirmed by decreased levels of TNF-alpha, interleukin-1beta, MPO activity and TBARS, and raised levels of FRAP in the colon tissue. These observations confirmed the immunomodulatory, anti-inflammatory and antioxidant properties of Setarud in experimental colitis, which was comparable to those of dexamethasone and infliximab.     

Melatonin reduces inflammatory injury through inhibiting NF-kappaB activation in rats with colitis

Proinflammatory mediators are important in the pathogenesis of IBD, which are regulated by activation of NF-kappaB. The aim of this study was to investigate whether melatonin reduces inflammatory injury and inhibits proinflammatory molecule and NF-kappaB in rats with colitis. Rat colitis model was established by TNBS enema. NF-kappaB p65, TNF-alpha, ICAM-1, and IkappaBalpha in colon tissue were examined by immunohistochemistry, EMSA, RT-PCR, and Western blot analysis. Expression of proinflammatory molecule and activation of NF-kappaB were upregulated and IkappaB level decreased in rats with colitis. Melatonin reduces colonic inflammatory injury through downregulating proinflammatory molecule mediated by NF-kappaB inhibition and blockade of IkappaBalpha degradation.     

TNF-alpha is crucial for the development of mast cell-dependent colitis in mice

Inflammatory bowel disease (IBD) describes chronic inflammatory conditions of the gastrointestinal tract, and TNF-alpha plays a pivotal role in mediating the response. The proinflammatory cytokine TNF-alpha is rapidly released by mast cells after degranulation. In the present study, we hypothesized TNF-alpha to be an important player in our recently described mast cell-dependent murine model for IBD. The effect of neutralizing anti-TNF-alpha MAb was studied on colonic hypersensitivity in mice induced by a skin application of dinitrofluorobenzene (DNFB) followed by an intrarectal challenge with dinitrobenzene sulfonic acid. Features of the colonic hypersensitivity response included diarrhea, mast cell infiltration and activation, infiltration of inflammatory cells in the colon, colonic patch hypertrophy, and increased mast cell-derived TNF-alpha levels in the colon. Anti-TNF-alpha MAb could effectively abrogate diarrhea in DNFB-sensitized mice 72 h after the challenge. The numbers of colonic patches and total tissue damage scores were reduced by anti-TNF-alpha MAb treatment in DNFB-sensitized mice 72 h after the challenge. Mast cell infiltration and activation remained unaffected by neutralizing anti-TNF-alpha MAb. Treatment with the corticosteroid dexamethasone, a frequently used therapeutic treatment in IBD, resulted in a reduction of diarrhea, cellular infiltration, and total tissue damage scores to the same extent as anti-TNF-alpha MAb. Additionally, dexamethasone treatment could also reduce total TNF-alpha levels in the colon, mast cell numbers, and mast cell activation in both vehicle- and DNFB-sensitized mice 72 h after the challenge. These findings suggest that TNF-alpha can play an instrumental role in causing inflammatory responses in the present murine model for IBD downstream from mast cell activation.     

Green tea polyphenol extract attenuates colon injury induced by experimental colitis

Inflammatory bowel disease (IBD) is characterised by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. The aim of the present study was to examine the effects of green tea extract in rats subjected to experimental colitis induced by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). At 4 days after DNBS administration the rats were sacrificed. Treatment with green tea extract significantly attenuated diarrhoea and loss of body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture, significant reduction of colonic myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-alpha) production. Green tea extract also reduced the appearance of nitrotyrosine immunoreactivity in the colon and reduced the up-regulation of ICAM-1.     

Increased arginase activity and endothelial dysfunction in human inflammatory bowel disease

Nitric oxide (.NO) generation from conversion of l-arginine to citrulline by nitric oxide synthase isoforms plays a critical role in vascular homeostasis. Loss of .NO is linked to vascular pathophysiology and is decreased in chronically inflamed gut blood vessels in inflammatory bowel disease (IBD; Crohn's disease and ulcerative colitis). Mechanisms underlying decreased .NO production in IBD gut microvessels are not fully characterized. Loss of .NO generation may result from increased arginase (AR) activity, which enzymatically competes with nitric oxide synthase for the common substrate l-arginine. We characterized AR expression in IBD microvessels and endothelial cells and its contribution to decreased .NO production. AR expression was assessed in resected gut tissues and human intestinal microvascular endothelial cells (HIMEC). AR expression significantly increased in both ulcerative colitis and Crohn's disease microvessels and submucosal tissues compared with normal. TNF-alpha/lipopolysaccharide increased AR activity, mRNA and protein expression in HIMEC in a time-dependent fashion. RhoA/ROCK pathway, a negative regulator of .NO generation in endothelial cells, was examined. The RhoA inhibitor C3 exoenzyme and the ROCK inhibitor Y-27632 both attenuated TNF-alpha/lipopolysaccharide-induced MAPK activation and blocked AR expression in HIMEC. A significantly higher AR activity and increased RhoA activity were observed in IBD submucosal tissues surrounding microvessels compared with normal control gut tissue. Functionally, inhibition of AR activity decreased leukocyte binding to HIMEC in an adhesion assay. Loss of .NO production in IBD microvessels is linked to enhanced levels of AR in intestinal endothelial cells exposed to chronic inflammation in vivo.     

VEGF-A stimulation of leukocyte adhesion to colonic microvascular endothelium: implications for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder characterized by increased leukocyte recruitment and subsequent tissue damage. An increase in the density of the microvasculature of the colon during IBD has been suggested, leading to the concept that angiogenesis may play a pathological role in IBD. Increased tissue and serum levels of the angiogenic cytokine VEGF-A have been reported in cases of active IBD. In this study, we examined the hypothesis that VEGF-A exerts a proinflammatory effect on colon microvascular endothelium that contributes to colonic inflammation. Leukocyte adhesion to VEGF-A-stimulated colon microvascular endothelial cells was examined using a parallel-plate hydrodynamic flow chamber. ICAM-1 adhesion molecule expression on colonic microvascular endothelium also was determined in response to VEGF-A stimulation, along with characterization of leukocyte adhesion molecule expression. High-dose VEGF-A (50 ng/ml) stimulation increased neutrophil and T cell adhesion to and decreased rolling velocities on activated endothelium, whereas low-dose VEGF-A (10 ng/ml) was without effect. Colonic endothelium constitutively expressed ICAM-1, which was significantly increased by treatment with 50 ng/ml VEGF-A or 10 ng/ml TNF-alpha but not 10 ng/ml VEGF-A. T cells expressed CD18 and CD11a with no expression of CD11b, whereas neutrophils expressed CD18, CD11a, and CD11b. Finally, VEGF-A-dependent leukocyte adhesion was found to occur in a CD18-dependent manner. These results demonstrate that VEGF-A levels found in IBD exert a proinflammatory effect similar to other inflammatory agents and suggest that this cytokine may serve as an intermediary between angiogenic stimulation and cell-mediated immune responses.     

BMP signaling in rats with TNBS-induced colitis following BMP7 therapy

Beyond stimulating bone formation, bone morphogenetic proteins (BMPs) are important in development, inflammation, and malignancy of the gut. We have previously shown that BMP7 has a regenerative, anti-inflammatory, and antiproliferative effect on experimental inflammatory bowel disease (IBD) in rats. To further investigate the BMP signaling pathway we monitored the effect of BMP7 therapy on the BMP signaling components in the rat colon during different stages of experimentally induced colitis by 2,4,6-trinitrobenzene sulfonic acid (TNBS). The results showed a significantly decreased BMP7 expression in the acute phase, followed by a significantly increased BMP2 and decreased BMP6 expression during the chronic phase of colitis. BMP7 therapy influenced the expression of several BMPs with the most prominent effect on downregulation of BMP2 and upregulation of BMP4 in the chronic phase of colitis. Importantly, connective tissue growth factor and noggin expression were elevated in the acute stage and significantly decreased upon BMP7 therapy. BMP receptor I expression was unchanged, whereas BMP receptor II was decreased at day 2 and increased at days 14 and 30 of TNBS inflammation. However, an opposite pattern of expression following BMP7 therapy has been observed. BMP7 increased the expression of BR-Smad including Smad3 and Smad4. Inhibitory Smads were increased in colitis and significantly decreased following BMP7 therapy at later stages of the disease. We suggest that BMP signaling was altered during TNBS-induced colitis and was recovered with BMP7 administration, suggesting that IBD is a reversible process.     

Combination therapy of mesenchymal stromal cells and sulfasalazine attenuates trinitrobenzene sulfonic acid induced colitis in the rat: The S1P pathway

Adipose derived mesenchymal stem cells (ASCs) transplantation is a novel immunomodulatory therapeutic tool to ameliorate the symptom of inflammatory bowel disease (IBD). The objective of this study was to investigate the therapeutic effects of combined sufasalazine and ASCs therapy in a rat model of IBD. After induction of colitis in rats, ASCs were cultured and intraperitoneally injected (3 × 10⁶cells/kg) into the rats on Days 1 and 5 after inducing colitis, in conjunction with daily oral administration of low dose of sulfasalazine (30 mg/kg). The regenerative effects of combination of ASCs and sulfasalazine on ulcerative colitis were assessed by measuring body weight, colonic weight/length ratio, disease activity index, macroscopic scores, histopathological examinations, cytokine, and inflammation markers profiles. In addition, western blot analysis was used to assess the levels of nuclear factor-kappa B (NF-κB) and apoptosis related proteins in colitis tissues. Simultaneous treatment with ASCs and sulfasalazine was associated with significant amelioration of disease activity index, macroscopic and microscopic colitis scores, as well as inhibition of the proinflammatory cytokines in trinitrobenzene sulfonic acid (TNBS)-induced colitis. Moreover, combined ASCs and sulfasalazine therapy effectively inhibited the NF-κB signaling pathway, reduced the expression of Bax and prevented the loss of Bcl-2 proteins in colon tissue of the rats with TNBS-induced colitis. Furthermore, combined treatment with ASCs and sulfasalazine shifted inflammatory M1 to anti-inflammatory M2 macrophages by decreasing the levels of MCP1, CXCL9 and increasing IL-10, Arg-1 levels. In conclusion, combination of ASCs with conventional IBD therapy is potentially a much more powerful strategy to slow the progression of colitis via reducing inflammatory and apoptotic markers than either therapy alone.     

Clinical and anti-aging effect of mud-bathing therapy for patients with fibromyalgia

This study focuses on two inflammatory diseases, viz., “diabetes mellitus (DM)” that causes serious complications such as retinopathy, nephropathy, and neuropathy, and “ischemic colitis” which is evoked by DM. Ischemic colitis originates from the reduction in mesenteric blood flow to the colon with existence of the occlusive or non-occlusive reasons. Our study objective was to provide early diagnostic approach for ischemic colitis in streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley rats were divided into four groups: (i) control use of 0.1 M citrate buffer, the solvent of streptozotocin (C), (ii). induced ischemia (I), (iii) rats subjected to 60 mg/kg STZ intraperitoneally to induce type 1 diabetes (D) (48 h after STZ injection, blood glucose levels >200 mg/dl were considered as diabetic), and (iv) diabetic rats subjected to intestinal ischemia (D+I). The third diabetic group (D) was not operated. At the end of the experimental period, rats were sacrificed, C-reactive protein (CRP) and calprotectin levels were measured in the serum and colon tissue specimens. Tissue specimens were also analyzed histologically. We found that serum and colon calprotectin levels were elevated in the D+I group compared to the D and/or I group alone, but relatively calprotectin levels increased in I as compared to C group in colon tissues. CRP levels were significantly increased with ischemic colitis in diabetes, while colon CRP levels were decreased. These results provide evidence for the existence of inflammation in the STZ-induced diabetic rats with ischemic colitis. In conclusion, our measurements of serum calprotectin levels of STZ-induced diabetic rats with ischemic colitis provide a practical approach for an early diagnosis of ischemic colitis. Furthermore, these biochemical analyses correlate well with the histopathologic findings of STZ-induced diabetic rats with ischemic colitis. Future studies would be desirable to further strengthen the role of calprotectin in the early diagnosis of ischemic colitis in diabetics clinical settings.     

Attenuation of mouse acute colitis by naked hepatocyte growth factor gene transfer into the liver

BACKGROUND: Hepatocyte growth factor (HGF) has multiple biological effects on a wide variety of cells. It modulates intestinal epithelial proliferation and migration, and critically regulates intestinal wound healing. AIMS: To investigate the therapeutic effect of HGF gene transfer, we introduced the HGF gene into the liver of mice with acute colitis. METHODS: The rat HGF expression plasmid vector, pCAGGS-HGF, was injected via the tail vein into C57BL/6 mice, followed by dosing with dextran sulfate sodium in distilled water. Firstly, the HGF gene was injected once on day 0. Secondly, the HGF gene was injected on day 0 and again on day 2. RESULTS: Injection of the HGF gene ameliorated colitis with inhibition of both loss of body weight and shortening of colon length. It protected the colon from epithelial erosions and cellular infiltration. Expression of mRNAs for IFN-gamma, IL18, and TNF-alpha was reduced in the colon. In contrast, expression of mRNA for IL-10 was increased. The numbers of BrdU-positive intestinal epithelial cells were increased, and the numbers of TUNEL-positive apoptotic cells were decreased. Furthermore, a second injection prolonged the elevation of serum HGF levels, and ameliorated the symptoms better than a single injection. The empty pCAGGS plasmid did not ameliorate acute colitis. CONCLUSIONS: HGF gene transfer attenuated acute colitis by facilitating intestinal wound repair as well as inhibiting inflammation, suggesting a new strategy for treatment of IBD.     

5-氨基水杨酸纳米粒对TNBS诱导小鼠结肠炎的治疗作用

目的:评价超临界分散法制备的5-氨基水杨酸(5-ASA)结肠定位纳米粒对小鼠结肠炎的治疗作用。方法:将24只6周龄BABL/c小鼠随机分为空白对照组,结肠炎模型组,5-ASA治疗组,5-ASA纳米粒治疗组。三硝基苯磺酸(TNBS)造模后的第2-7 d分别给予0.9%氯化钠,5-ASA和5-ASA纳米粒灌胃,于第8 d处死所有小鼠,评估小鼠的疾病活动指数(DAI),组织病理形态以及结肠组织学损伤情况;检测结肠组织髓过氧化物酶(MPO)活性。结果:5-ASA和5-ASA纳米粒均能明显减轻结肠重量,缩小溃疡面积,降低MPO活性。超临界分散法制备的5-ASA纳米粒在DAI,减轻局部的炎症程度(MPO水平)方面,其疗效与5-ASA组(50 mg/Kg)相当。结论:超临界分散法制备的5-ASA纳米粒对TNBS诱导小鼠的结肠炎有明显的治疗作用。     

Increased colonic apelin production in rodents with experimental colitis and in humans with IBD

Apelin and its receptor, the APJ receptor, are expressed in the gastrointestinal tract. The aims of this study were to examine the effects of sodium dextran sulfate (DSS)-induced experimental colitis in rats and mice and inflammatory bowel disease (IBD) in humans on intestinal apelin production, and the influence of exogenous apelin on colonic epithelial cell proliferation in mice. In rodents with experimental colitis, colonic apelin mRNA levels were elevated during the inflammatory reaction as well as during the tissue repair phase that ensues after DSS withdrawal. Fluctuations in colonic apelin expression were paralleled by similar changes in apelin immunostaining. Apelin immunostaining was increased in the surface epithelium, in epithelial cells along the length of the tubular gland and in the stem cell region at the gland base. In ulcerative colitis (UC) and Crohn's disease patients, apelin immunostaining revealed a pattern of increased intestinal apelin content similar to that observed in rodents with experimental colitis. Administration of synthetic apelin to mice during the recovery phase of DSS-induced colitis stimulated colonic epithelial cell proliferation significantly. Our observations that colonic apelin production is increased during and after DSS exposure indicate that apelin plays multiple roles during the different stages of colitis. Additionally, the stimulatory action of exogenous apelin on colonic epithelial proliferation suggests that the increased apelin production during intestinal recovery stage may contribute to the repair of the intestinal epithelium in experimental rodent models of colitis and in IBD patients.     

Inhibition of myeloid differentiation 1 specifically in colon with antisense oligonucleotide exacerbates dextran sodium sulfate-induced colitis

Myeloid differentiation 1 (MD-1), also known as lymphocyte antigen 86 (Ly86), is a soluble protein homologous to MD-2 and forms a complex with radioprotective 105 (RP105). RP105/MD-1 complex negatively regulates toll-like receptor 4 (TLR4) signaling and is involved in several immune disorders. However, the precise role of MD-1 in inflammatory bowel diseases (IBD) remains poorly understood. To further investigate the involvement of MD-1 in IBD, we inhibited MD-1 in colon with antisense oligonucleotide (AS-ODN) and assessed the effect of MD-1 inhibition on dextran sodium sulfate (DSS)-induced colitis. We discovered that MD-1 protein expression was remarkably decreased in both patients with ulcerative colitis and mice with DSS-induced colitis. For the first time, we showed that oral administration of MD-1 AS-ODN to mice significantly suppressed the MD-1 protein levels in colon rather than systemic tissues. Subsequently, we found that MD-1 AS-ODN treated mice were more susceptible to DSS-induced colitis based on loss of body weight, colon length, histological scores, and disease activity index. MD-1 inhibition also significantly enhanced inflammatory cytokines production such as IL-6 and IL-1β in colons. Finally, mice treated with MD-1 AS-ODN exhibited increased messenger RNA levels of TLR4 and MyD88 after DSS exposure and showed enhanced nuclear factor (NF)-κB activation compared with the control. Taken together, specifically suppression of MD-1 in colon tissues with AS-ODN exacerbates DSS-induced experimental colitis in mice, which is possibly related to activation of TLR4/NF-κB signaling.     

Differential Expression and Localization of IGF-I and IGF Binding Proteins in Inflamed Rat Colon

Abstract

Recent studies indicate increased insulin-like growth factor I (IGF-I) expression and altered expression of IGF binding proteins (IGFBP) in the bowel during experimental colitis. This study analyzes the cellular sites of altered IGF-I and IGFBP-expression in large bowel of rats with experimental colitis. Colitis was induced by colonic instillation of 2, 4, 6- trinitrobenzenesulfonic (TNB) acid in ethanol. Animals were sacrificed at 7 days after induction of colitis. Cryostat sections of colon from TNB-treated and control rats were hybridized with ³⁵S-labeled antisense probes for IGF-I, IGFBP-3, IGFBP-4 and IGFBP-5. IGF-I mRNA was up-regulated in lamina propria cells, submucosa and smooth muscle of inflamed colon. IGFBP-3 mRNA was localized to lamina propria and was down-regulated in inflamed colon. IGFBP-4 and IGFBP-5 mRNAs were both up-regulated in inflamed colon. IGFBP-4 mRNA was increased in lamina propria, submucosa and smooth muscle, whereas IGFBP-5 mRNA was increased in smooth muscle. Increased IGF-I expression in mesenchymal layers of colon during experimental colitis supports the hypothesis that IGF-I contributes to hyperplasia and fibrosis in response to inflammation. Altered expression of IGFBP-3, IGFBP-4 and IGFBP-5 in specific bowel layers during colitis suggests that they play a role in modulating IGF-I action.     

Effect of COX-2 inhibitor after TNBS-induced colitis in wistar rats

Inflammatory bowel disease (IBD) is a common chronic gastrointestinal disorder characterized by alternating periods of remission and active intestinal inflammation. Some studies suggest that antiinflammatory drugs are a promising alternative for treatment of the disease. Thus, this study aimed to evaluate the effect of lumiracoxib, a selective-cyclooxygenase-2 (COX-2) inhibitor, on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis. Wistar rats (n = 25) were randomized into four groups, as follows: Group (1) Sham group: sham induced-colitis rats; Group (2) TNBS group: nontreated induced-colitis rats; Group (3) Lumiracoxib control group; and Group (4) Lumiracoxib-treated induced-colitis rats. Our results showed that rats from groups 2 and 4 presented similar histopathological damage and macroscopic injury in the distal colon as depicted by significant statistically differences (P < 0.01; P < 0.05) compared to the other two groups. Weak expression of COX-2 mRNA was detected in normal colon cells, while higher levels of COX-2 mRNA were detected in group 2 and group 4. Therapy with lumiracoxib reduced COX-2 expression by 20–30%, but it was still higher and statistically significant compared to data obtained from the lumiracoxib control group. Treatment with the selective COX-2 inhibitor lumiracoxib did not reduce inflammation-associated colonic injury in TNBS-induced experimental colitis. Thus, the use of COX-2 inhibitors for treating IBD should be considered with caution and warrants further experimental investigation to elucidate their applicability.