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     

Reduced susceptibility to dextran sulphate sodium-induced colitis in the interleukin-2 heterozygous (IL-2) mouse

Summary Mice homozygous for an inactivation of the interleukin-2 (IL-2) gene develop a T-cell dependent colitis. Heterozygous (IL-2+/-) mice are clinically healthy but have been shown to express reduced levels of IL-2 in the colon. Splenocytes from the IL-2+/- mice had a poorer proliferative response to polyclonal T-cell activation and these mice have reduced numbers of intestinal regulatory T cells (CD4+ CD25+ cells) when compared to wild type mice. When exposed to dextran sulphate sodium (DSS) IL-2+/- mice showed a markedly reduced susceptibility to DSS-induced colitis. While DSS treatment caused a marked increase in both CD4+ and CD8+ colonic T cells expressing increased levels of IL-2, IL-4, and IL-10 in wild type mice none of these changes were seen in IL-2+/- mice. On the contrary, cytokine expression in intestinal T cells of IL-2+/- mice was actually reduced after DSS treatment. These results suggest that reduced levels of IL-2 leads to attenuated activation and function of intestinal T cells in IL-2+/- mice and a failure to react adequately to DSS exposure.     

Blocking lymphotoxin-beta receptor activation diminishes inflammation via reduced mucosal addressin cell adhesion molecule-1 (MAdCAM-1) expression and leucocyte margination in chronic DSS-induced colitis

The lymphotoxin-beta receptor (LTbetaR) pathway is critical for maintenance of organized lymphoid structures and is involved in the development of colitis. To investigate the mechanisms by which LTbetaR activation contributes to the pathology of chronic inflammation we used a soluble LTbetaR-Ig fusion protein as a competitive inhibitor of LTbetaR activation in the mouse model of chronic colitis induced by oral administration of dextran sulphate sodium. Strong expression of LTbeta which constitutes part of the LTalpha(1)beta(2) ligand complex was detected in colonic tissue of mice with chronic colitis. Treatment with LTbetaR-Ig significantly attenuated the development and histological manifestations of the chronic inflammation and reduced the production of inflammatory cytokines such as TNF, IL-1beta, and IL-6. Moreover, LTbetaR-Ig treatment significantly down-regulated mucosal addressin cell adhesion molecule-1 (MAdCAM-1) expression, leading to reduced leucocyte rolling and sticking in postcapillary and collecting venules and reduced extravasation into the intestinal mucosa as quantified by in vivo fluorescence microscopy. Thus, LTbetaR pathway inhibition ameliorates DSS-induced experimental chronic colitis in mice by MAdCAM-1 down-regulation entailing reduced lymphocyte margination and extravasation into the inflamed mucosa. Therefore, a combined treatment with reagents blocking T cell-mediated perpetuation of chronic inflammation such as LTbetaR-Ig together with direct anti-inflammatory reagents such as TNF inhibitors could constitute a promising treatment strategy for chronic colitis.     

小鼠肠腺瘤类器官培养及其辐射敏感性

目的 建立小鼠肠腺瘤类器官的体外培养方法,观察其对电离辐射的反应。方法 采用氧化偶氮甲烷(azoxymethane,AOM)和葡聚糖硫酸钠(detrain sodium sulfate,DSS)诱导小鼠产生肠腺瘤。体外分离腺瘤类隐窝结构,接种于基质胶。通过培养基筛选,确定肠腺瘤类器官的体外培养条件,采用免疫组化染色检测Ki67和β-catenin表达水平。进一步采用X线照射,观察肠腺瘤类器官损伤情况,比较其与大、小肠类器官的辐射敏感性。 结果 经AOM/DSS诱导,小鼠肠腺瘤成瘤率达95%,肿瘤均位于结肠靠近直肠处,肠腺瘤类器官在改良的小肠类器官中生长良好,Ki67阳性腺瘤细胞比例高且β-catenin入核特征明显。经X线照射,各类器官存活比例随辐射剂量增加而降低。9 Gy照射7天后,腺瘤类器官存活率为11.96%±1.42%,高于同剂量大肠类器官的5.46%±1.22% (t=6.0082,P＜0.01),小肠类器官几乎未见存活。腺瘤类器官剂量存活曲线较大、小肠类器官右移,提示其辐射敏感性低于大肠和小肠。 结论 在AOM/DSS诱导产生的小鼠肠腺瘤中成功分离培养出腺瘤类器官,其辐射敏感性低于大、小肠类器官。     

Inhibitory Effects of Fermented Brown Rice on Induction of Acute Colitis by Dextran Sulfate Sodium in Rats

Although the pathogenic mechanisms of inflammatory bowel diseases are not fully understood, colonic microbiota may affect the induction of colonic inflammation, and some probiotics and prebiotics have been reported to suppress colitis. The inhibitory effects of brown rice fermented by Aspergillus oryzae (FBRA), a fiber-rich food, on the induction of acute colitis by dextran sulfate sodium (DSS) were examined. Feeding a 5% and 10% FBRA-containing diet significantly decreased the ulcer and erosion area in the rat colon stained with Alcian blue. In another experiment, 10% FBRA feeding decreased the ulcer index (percentage of the total length of ulcers in the full length of the colon) and colitis score, which were determined by macroscopic observation. It also decreased myeloperoxidase activity in the colonic mucosa. Viable cell numbers of Lactobacillus in the feces decreased after DSS administration and was reversely correlated with severity of colitis, while the cell number of Enterobacteriaceae increased after DSS treatment and was positively correlated with colitis severity. These results indicate that FBRA has a suppressive effect on the induction of colitis by DSS and suggest FBRA-mediated modification of colonic microbiota.     

Study on the additive protective effect of PGLYRP3 and Bifidobacterium adolescentis Reuter 1963 on severity of DSS-induced colitis in Pglyrp3 knockout (Pglyrp3 −/−) and wild-type (WT) mice

Background and AimsPglyrp3 is a bactericidal innate immunity protein known to sustain the habitual gut microbiome and protect against experimental colitis. Intestinal inflammation and metaflammation are commonly associated with a marked reduction of commensal bifidobacteria. Whether Pglyrp3 and bifidobacteria interact synergistically or additively to alleviate metaflammation is unknown. We investigated the extent to which Pglyrp3 and bifidobacteria regulate metaflammation and gut bacterial dysbiosis in DSS-induced mouse models of intestinal inflammation.Material & Methods8–10 weeks old male mice were used. In both WT and Pglyrp3 ?/? experiments, the mice were randomly divided into three groups of 16 mice per group: (1) a control group receiving sterile tap water, (2) an experimental group receiving sterile tap water supplemented with only 5% DSS, and (3) an experimental group receiving sterile tap water supplemented with 5% DSS and 1 × 10⁹ CFU/ml of Bifidobacterium adolescentis (B.a.) for 7 days. Wild-type (WT) littermates of the respective gene (i.e. Pglyrp3) were used as controls throughout the study. Clinical signs of general health and inflammation were monitored daily. Faecal pellet samples were analysed by qRT-PCR for microbial composition. Histology of relevant organs was carried out on day 8. Metabolic parameters and liver inflammation were determined in serum samples.ResultsIntestinal inflammation in mice of group 2 were significantly increased compared to those of control group 1. There was a significant difference in mean scores for inflammation severity between DSS-treated WT and DSS-treated Pglyrp3 ?/? mice. Buildup of key serum metabolic markers (cholesterol, triglyceride and glucose) was set off by colonic inflammation. qRT-PCR quantification showed that DSS significantly decreased the Clostridium coccoides and Bifidobacterium cell counts while increasing those of Bacteroides group in both WT and Pglyrp3 ?/? mice. These manifestations of DSS-induced dysbiosis were significantly attenuated by feeding B.a. Both the local and systemic ill-being of the mice alleviated when they received B.a.DiscussionThis study shows that Pglyrp3 facilitates recognition of bifidobacterial cell wall-derived peptidoglycan, thus leading additively to a reduction of metaflammation through an increase in the number of bifidobacteria, which were able to mitigate intestinal immunopathology in the context of Pglyrp3 blockade.     

丹参对右旋葡聚糖硫酸钠诱导小鼠结肠炎的疗效观察

目的 :评价丹参预防及治疗右旋葡聚糖硫酸钠 (DSS)结肠炎小鼠的有效性。方法 :2 0只正常小鼠随机分为两组 ,饮用 DSS7d,同时预防组用丹参 ,对照组用 0 .85 %氯化钠溶液。另 2 0只 DSS诱导的结肠炎小鼠随机分为两组 ,治疗组用丹参 ,对照组用 0 .85 %氯化钠溶液 7d。用疾病活动指数 (DAI)、组织学评分和马休斯猩红蓝(MSB)纤维素染色检测微血栓以评价疗效。结果 :丹参在预防组部分降低微血栓的形成 ,对照组 10例有 6例微血栓阳性 ,预防组 3例阳性。丹参治疗组与对照组的 DAI、直肠、横结肠组织学评分分别为 0 .4 5、0 .4 8(P>0 .0 5 ) ,1.36、1.76 (P<0 .0 5 ) ,1.35、1.6 0 (P<0 .0 5 )。结论 :丹参可能部分抑制微血栓形成和减轻 DSS结肠炎小鼠结肠炎症 ,提示丹参用于溃疡性结肠炎治疗也可能有效。