山姜素对葡聚糖硫酸钠诱导小鼠溃疡性结肠炎的保护作用及其作用机制研究

目的探讨山姜素对葡聚糖硫酸钠诱导的溃疡性结肠炎小鼠的保护作用及其作用机制。方法 C57BL/6小鼠随机分为对照组、模型组和25、50、100 mg/kg山姜素组。模型组和治疗组每天给予3%葡聚糖硫酸钠溶液,连续7 d。治疗组每日ip生理盐水0.5 m L+25、50、100 mg/kg山姜素,对照组和模型组每天ip生理盐水0.5 m L,连续7 d。观察小鼠体质量变化、结肠长度、疾病活动指数(DAI)评分、组织学损伤评分等炎症反应;透射电镜观察肠上皮细胞间连接;免疫组织化学法、Western blotting法检测肠道紧密连接蛋白claudin-2、occludin、ZO-1、STAT3、p STAT3、IL-6的表达和STAT3/IL-6信号通路的表达情况。结果与模型组比较,山姜素能够显著缓解小鼠体质量减轻和肠管缩短,降低DAI和组织学评分。山姜素可增强小鼠肠黏膜occludin、ZO-1表达,减弱claudin-2表达,并能够抑制STAT3/IL-6信号通路。结论山姜素能够上调葡聚糖硫酸钠诱导的溃疡性结肠炎小鼠结肠组织occludin、ZO-1的表达,下调claudin-2的表达,通过调节紧密连接蛋白的表达,保护肠上皮细胞屏障的完整性和通透性。通过抑制IL-6/STAT3通路,减轻结肠炎症反应。     

复方肠泰对葡聚糖硫酸钠诱导的溃疡性结肠炎治疗作用的研究

目的 探讨复方肠泰对葡聚糖硫酸钠(DSS)诱导的小鼠慢性溃疡性结肠炎(UC)的治疗作用。方法 随机将C57BL/6小鼠分为正常对照组、DSS模型组、复方肠泰给药组。采用2% DSS溶液对小鼠进行造模,小鼠连续5 d自由饮用DSS水,接着连续5 d自由饮水,重复3个循环。复方肠泰组每天按照18 g/kg ig给药,其他组ig给予相同体积的蒸馏水。每天记录小鼠体质量、疾病活动指数(DAI)评分结果,采用HE染色观察结直肠组织病理学变化,给予组织病理学评分;ELISA检测TNF-α、IL-10表达水平,免疫组化检测COX-2蛋白表达情况。结果 与DSS模型组比较,复方肠泰组小鼠疾病状态得到明显改善,DAI和组织病理学评分显著降低,炎症因子IL-10表达升高,TNF-α、COX-2蛋白的表达降低。结论 复方肠泰对小鼠慢性UC具有显著地治疗作用,可能通过促进抗炎症因子IL-10的表达,同时抑制促炎症因子TNF-α、COX-2蛋白的表达发挥作用。     

Protective role of liriodendrin in mice with dextran sulphate sodium-induced ulcerative colitis

Sargentodoxa cuneata, containing syringaresinol and its glycoside liriodendrin as the main bioactive compounds, is a well-known traditional Chinese medicine for treating intestinal inflammation. In our preliminary study, liriodendrin inhibited NF-kB activation in sepsis-induced acute lung injury. The present study was designed to investigate its effect on dextran sulfate sodium (DSS)-induced colitis in a mouse model and to explore the possible related mechanisms. Experimental colitis was established by giving mice drinking water containing 3% (w/v) DSS for 7 days. The mice were pretreated with liriodendrin (100 mg/kg/day, intragastrically) 3 days before DSS treatment. We determined the effects of liriodendrin on disease activity index (DAI), colon length, histopathological examination, antioxidants, and anti-inflammatory activities. Our results showed that liriodendrin greatly decreased MPO and MDA activities and significantly increased SOD and GPx activities in the colon. Moreover, liriodendrin improved DAI, colon length and histological damage in colon and reduced the levels of pro-inflammatory cytokines, such as TNF-a, IL-1β and IL-6. Meanwhile, assessments by western blot revealed that liriodendrin significantly suppressed the activation of Akt and NF-κB pathways and up-regulated the expression of ERβ in the colon. In vitro, liriodendrin down-regulated production of pro-inflammatory cytokines and suppressed NF-κB signalling pathways in LPS-induced RAW 264.7 macrophages in a concentration-dependent manner. In addition, syringaresinol, the hydrolysate of liriodendrin, more potently down-regulated production of pro-inflammatory cytokines and suppressed NF-κB and Akt signalling pathways in LPS-induced RAW 264.7 macrophages,which were abolished by using a pure ER antagonist, ICI182, 780. Taken together, liriodendrin-mediated suppression of inflammatory damage in the colon may be attributable to the in vivo transformation to syringaresinol and liriodendrin may be a promising therapeutic approach preventive agent for colitis treatment.     

Balsalazine decreases intestinal mucosal permeability of dextran sulfate sodium-induced colitis in mice

Aim： To investigate the effect of balsalazine treatment on intestinal mucosal permeability in dextran sulfate sodium （DSS）-induced colitis and to determine the mechanism of the balsalazine-induced changes.
Methods： Experimental colitis was induced in C57BL/6J mice by the administration of 5% DSS. Balsalazine was administered intragastrically at doses of 42, 141, and 423 mg/kg. The disease activity index （DAI） score was evaluated and colon tissue was collected for the assessment of histological changes. The amount of malondialdehyde （MDA） in the colon was determined, along with the activity of myeloperoxidase （MPO）, superoxide dismutase （SOD） and glutathione peroxidase （GSH-Px）. Mucosa from the small intestine was collected to determine the levels of tumor necrosis factor （TNF）-α and interferon （IFN）-γ. The mucosa was ultrastructurally examined with transmission electron microscopy and intestinal permeability was assayed using Evans blue.
Results： Balsalazine was found to reduce the DAI score and the histological index （HI） score, decrease the MDA content and the activity of MPO, and increase the activity of SOD and GSH-Px in colitis mice. At the same time, balsalazine ameliorated microvillus and tight junction structure, resulting in a decrease in the amount of Evans blue permeating into the intestinal wall and the levels of TNF-α and IFN-γ in colitis mice.
Conclusion： In colitis mice, the anti-colitis effect of balsalazine results in a decrease in intestinal mucosal permeability. The mechanism of this effect is partly associated with balsalazine＇s antioxidative and anti-inflammatory effects.     

Anti-inflammatory effects of Vicenin-2 on dextran sulfate sodium-induced colitis in mice

The objective of the present work was to evaluate the anti-inflammatory effects of Vicenin-2 on dextran sulfate sodium (DSS)-induced colitis model. Colitis was induced in C57BL/6J mice by administration of 2% DSS in drinking water for 7 days. In addition to DSS, Vicenin-2 (50 mg kg⁻¹/day⁻¹) was administrated orally to the test group. The ulceration extent and severity were assessed macroscopically, histopathologically, and by disease activity index. The Vicenin-2 treated group showed significant differences in physiological parameters including bodyweight, colon weight, and colon length, compared to DSS-induced colitis group. In addition, Vicenin-2 treatment effectively reduced stool consistency and bleeding scores. Myeloperoxidase (MPO) activity, expressions of pro-inflammatory cytokines, and specific key inflammatory markers (iNOS and COX-2) significantly increased in DSS-induced colitis colon tissues. However, administration of Vicenin-2 effectively reduced the MPO activity, attenuated the expression of pro-inflammatory cytokines and key inflammatory markers, in DSS-induced colitis mice. These results were comparable with sulfasalazine, an anti-inflammatory drug used routinely for ulcerative colitis (UC). These findings suggest that Vicenin-2 effectively suppresses DSS-induced colitis by attenuating expressions of key inflammatory mediators and found to be an attractive therapeutic drug for treating UC.     

Piceatannol, a stilbene present in grapes, attenuates dextran sulfate sodium-induced colitis

Piceatannol (3,5,3',4'-tetrahydroxy-trans-stilbene; PIC) is a polyphenol found in grapes. It is known as a protein kinase inhibitor that modifies multiple cellular targets, exerting immunosuppressive and antitumorigenic activities in several cell lines. The purpose of the present work was to evaluate the anti-inflammatory effect of PIC on dextran sulfate sodium (DSS)-induced colitis. Experimental colitis was induced in BALB/c mice by dissolving 5% DSS in their drinking water for 7 days. PIC (1, 2.5, 5, or 10 mg/kg body weight) was administrated daily per oral route for 7 days. A significant blunting of weight loss and clinical signs was observed in DSS-exposed, PIC-treated mice when compared to vehicle-treated mice. This was associated with a remarkable amelioration of the disruption of the colonic architecture, a significant reduction in colonic myeloperoxidase (MPO) activity, and a decrease in production of inflammatory mediators such as nitric oxide (NO), prostaglandin (PG) E2, and pro-inflammatory cytokines. The present data indicate that further evaluation of the potential of PIC as an agent for the prevention and/or treatment of inflammatory bowel diseases in human clinical studies is warranted.     

Establishment and validation of a new semi-chronic dextran sulfate sodium-induced model of colitis in mice

BackgroundThe dextran sulfate sodium (DSS)-induced model of colitis is a commonly used model of inflammatory bowel disease (IBD) in animals. However, there were few studies on the therapeutic efficacy of drugs for IBD after the onset of colitis in this model. We established a semi-chronic model of DSS-induced colitis in mice and used it to assess the therapeutic efficacy of agents for IBD.Materials and methodsColitis was induced by administration of 3% DSS in drinking water to mice for 7 days followed by 5 days of normal drinking water.ResultsUlcerative colitis (UC)-like symptoms including diarrhea, bloody stools and body-weight loss were observed from days 3 to 5, and continued until day 12 after DSS administration. Persistent colitis was associated with sustained local production of cytokines and was characterized by infiltration of inflammatory cells, crypt loss and erosion in the distal colon. These features are similar to those found in patients with UC. In this model, anti-tumor necrosis factor (TNF)-α antibody or anti-interleukin (IL)-12/23p40 antibody significantly ameliorated colitis when administered after the onset of colitis. However, treatment with FK506, prednisolone or sulfasalazine provided limited therapeutic benefit.ConclusionThe DSS-induced colitis established here showed similar symptomatic and histopathological features to those seen in human UC. This model may be available for predicting the clinical efficacy of candidate compounds for UC.     

Evaluation of the anti-inflammatory effect of baicalein on dextran sulfate sodium-induced colitis in mice

The anti-inflammatory effect of three flavonoids from the root of Scutellaria baicalensis (baicalein, baicalin and wogonin) was evaluated in a murine model of acute experimental colitis induced by dextran sulfate sodium (DSS). Baicalein, but not baicalin or wogonin, given orally at 20 mg/kg for ten days, ameliorates all the considered inflammatory symptoms of the induced colitis, such as body weight loss, blood haemoglobin content, rectal bleeding and other histological and biochemical parameters. The effect of baicalein was similar to that of sulfasalazine, the reference drug given at 50 mg/kg.     

二氢杨梅素对小鼠葡聚糖硫酸钠结肠炎的干预作用

目的探讨二氢杨梅素(DMY)对葡聚糖硫酸钠(DSS)诱导的小鼠溃疡性结肠炎(UC)的作用效果。方法将60只Balb/C小鼠随机分为正常对照组、模型组、DMY低剂量组(50 mg·kg~(-1)·d~(-1))、DMY中剂量组(100 mg·kg~(-1)·d~(-1))、DMY高剂量组(200 mg·kg~(-1)·d~(-1))和5-氨基水杨酸组(50 mg·kg~(-1)·d~(-1)),各10只。正常对照组小鼠每日给予蒸馏水饮用,其余组小鼠给予4%DSS连续饮用7 d,诱导小鼠急性UC模型,与此同时给予对应剂量的药物灌胃治疗。7 d后处死小鼠并计算小鼠疾病活动指数(DAI)、光镜下结肠组织损伤评分(TDI),流式细胞法测定外周血中调节性T淋巴细胞(Treg)、辅助性T细胞17(Th17)占CD4+T细胞的百分比,Western blot及免疫组化法测定结肠组织中基质金属蛋白酶9(MMP 9)的表达水平。结果与正常对照组相比,模型组DAI、TDI明显升高(P<0.01),Treg/Th17比值明显降低(P<0.01),MMP 9表达升高(P<0.05)。与模型组相比,DMY低、中、高剂量组小鼠Treg/Th17比值明显升高(P<0.01),MMP 9表达降低(P<0.05),DMY中、高剂量组小鼠DAI、TDI明显降低(P<0.01),且随着治疗剂量增加,升高或降低幅度愈明显。结论 DMY可以显著缓解DSS诱导的小鼠UC炎症,且与剂量呈正相关。     

Lansoprazole binding to the neutrophils in dextran sulfate sodium-induced rat colitis

To clarify the effector sites of lansoprazole in the colonic mucosa during the formation of colitis, dextran sulfate sodium-induced colitis was induced by the oral administration of 3% aqueous solution for 3 and 7 days. The effector sites of [³H]lansoprazole were examined by the intra-aortic infusion of the radiolabelled compound and the autoradiographic tracing of water-soluble compounds. As a result, the [³H]lansoprazole binding in the control rat colon was negligible, while in dextran sulfate sodium-treated rats specific binding sites of [³H]lansoprazole were recognized in the cytoplasm of the mesenchymal cells, and most of them coincided with polymorphonuclear leucocytes and macrophages.     

Maresin 1 alleviates dextran sulfate sodium-induced ulcerative colitis by regulating NRF2 and TLR4/NF-kB signaling pathway

ObjectiveUlcerative colitis (UC) is one of the most common gastrointestinal diseases, characterized as a chronic, relapsing inflammation that causes damage to the colonic mucosa. Maresin 1 (MaR1), a specialized proresolving mediator, has powerful anti-inflammatory activity that prevents the occurrence of various inflammatory diseases. The aim of this study was to explore the role and potential mechanism of MaR1 in DSS-induced ulcerative colitis.MethodsIn the present study, we established dextran sulfate sodium (DSS)-induced ulcerative colitis rat model in vivo. Rats with colitis received tail vein injection of MaR1, with or without intraperitoneal injection of ML385. The changes of body weight, colon length, disease activity index (DAI), colonic histopathology, inflammatory cytokines, the activity of myeloperoxidase (MPO) and reactive oxygen species (ROS), and infiltration of macrophages expressing F4/80 were analyzed for the evaluation of colitis severity. In addition, protein expressions were detected using western blot.ResultsMaR1 significantly reduced inflammatory cytokines production, and restored body weight, DAI and colonic histopathology. Besides, MaR1 improved the expression of tight junction (TJ) proteins and reduced the infiltration of neutrophil and macrophages, as well as a decreased activity of MPO and ROS. Meanwhile, MaR1 activated Nrf2 signaling and decreased toll-like receptor 4(TLR4)/nuclear factor-κB(NF-κB) activation. Furthermore, ML385, an inhibitor of Nrf2, significantly reversed the protective effect of MaR1.ConclusionMaR1 play a protective role in DSS-induced colitis by activating Nrf2 signaling and inactivating Nrf2-mediated TLR4/NF-κB signaling pathway, which mediate proinflammatory mediators and intestinal TJ proteins in rats, providing novel insights into the therapeutic strategy of colitis.     

Treatment of mice with dextran sulfate sodium-induced colitis with human interleukin 10 secreted by transformed Bifidobacterium longum

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) the etiology of which has not yet been fully clarified. Cytokine interleukin-10 (IL-10) plays a central role in downregulating inflammatory cascade in UC and is likely a candidate for therapeutic intervention. However, its intravenous administration is costly and inconvenient. Therefore, we established a novel IL-10 delivery system by transforming a hIL-10-containing plasmid into B. longum (BL-hIL-10) and investigated its effects on 5% dextran sulfate sodium (DSS)-induced ulcerative colitis in mice and the possible underlying mechanism. Our results show that (1) hIL-10 was expressed and secreted into the culture supernatant of BL-hIL-10 after L-arabinose induction in vitro as examined by Western blot, enzyme-linked immunosorbent assay (ELISA) and RT-PCR; (2) addition of BL-hIL-10 culture supernatant had no cytotoxic effect and morphological alteration, but significantly inhibited the enhancement of proinflammatory cytokines by lipopolysaccharide (LPS) in THP-1 cells; (3) oral administration of BL-hIL-10 alleviated colitis syndrome of the model mice, attenuated colitis-activated NF-κB pathway measured by DNA-binding assay and colitis-elevated expression of proinflammatory cytokines examined with CCK cytotoxic kits, and upregulated CD4+CD25+Foxp3+ Treg in blood and mesenteric lymph nodes measured by flow cytometry. In conclusion, BL-hIL-10 as a novel oral hIL-10 delivery system has been successfully established and oral administration of BL-hIL-10 alleviated inflammatory damage of colonic tissue in the model mice by blocking the colitis-activated NF-κB pathway and upregulating CD4+CD25+Foxp3+ Treg in blood and mesenteric lymph nodes in mice.     

The natural plant product tryptanthrin ameliorates dextran sodium sulfate-induced colitis in mice

The therapeutic effects of tryptanthrin (TRYP), a natural product from the medicinal plant Polygonum tinctorium, were examined in a murine model of inflammatory bowel disease (IBD). Colitis was induced by 5% dextran sodium sulfate (DSS) in drinking water for 7 days from day 0. TRYP (100 mg/kg) was administered orally suspended in 5% arabia gum everyday from day 3 for 5 days. Histopathological analysis showed reduced colon damage in TRYP-treated mice on day 6; however, colon injury resumed after treatment was stopped. The production of prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) by untreated and treated mouse colon tissues cultured in vitro were mostly unchanged by TRYP treatment. However, mitogen-stimulated spleen cells from TRYP-treated colitic mice produced less interleukin 2 (IL-2) and less interferon-gamma (IFN-gamma) than untreated colitic mouse spleen cells, early after induction of colitis. When colitis was induced with 5% DSS for 7 days and TRYP was given to the mice for 8 days from day 3, TRYP enhanced the survival of the mice but results were not significant. A significant reduction of weight loss was observed in TRYP-treated mice with colitis induced by 5% DSS for 4 days as compared to control mice. Remarkably, whereas 90% of the vehicle-treated mice died from wasting disease, all the TRYP-treated mice survived, suggesting that TRYP may have a therapeutic effect on colitis.     

Luteolin ameliorates dextran sulfate sodium-induced colitis in mice possibly through activation of the Nrf2 signaling pathway

BackgroundLuteolin has a reputation for being a safe and effective natural antioxidant that has strong radical scavenging and cell protective properties. The role of oxidative stress in inflammatory bowel disease (IBD) has been well established and is increasingly highlighted. Thus, we studied the protective effect of luteolin administration in a mouse model of experimental colitis.MethodsExperimental acute colitis was induced by administering 3% dextran sulfate sodium (DSS) in the drinking water of mice for 7 days. The disease activity index (DAI); colon length; histological assessment; mRNA levels of nuclear factor-erythroid 2-related factor 2 (Nrf2), tumor necrosis factor (TNF-α), interleukin-6 (IL-6), heme oxygenase-1 (HO-1), and NADP(H): quinone oxidoreductase 1 (NQO-1); protein expression of Nrf2 and inducible nitric oxide synthase (iNOS); colon malondialdehyde (MDA) levels; and the activity levels of colonic superoxide dismutase (SOD) and catalase (CAT) were examined.ResultsLuteolin (20 and 50 mg/kg) significantly attenuated the DAI, colon shortening and histological damage. In addition, luteolin administration effectively decreased the expression of inflammatory mediators, such as iNOS, TNF-α and IL-6. Luteolin also decreased the colonic content of MDA. The activities of colonic SOD and CAT and the levels of Nrf2 and its downstream targets, HO-1 and NQO1, were elevated by luteolin treatment.ConclusionThese observations indicate that luteolin may suppress experimental colitis through the Nrf2 signaling pathway.     

The protective effect of syringic acid on dextran sulfate sodium-induced experimental colitis in BALB/c mice

Inflammatory bowel diseases involve chronic intestinal inflammation which is mostly caused by Crohn's disease and ulcerative colitis (UC) conditions. Patients having UC are prone to colorectal cancer and dysplastic polyps, and also have sporadic adenomas. Syringic acid (SA) possesses many health benefits including antioxidant, anti-bacterial, and anti-cancer. This study was aimed to identify the effects of SA on UC, using a murine experimental model. Clinical symptoms and weight loss were significantly reduced in mice induced with dextran sulfate sodium (DSS) and treated with SA, compared to untreated mice. The effects of SA exhibited in DSS-induced mice were associated with significant decrease in the expressions levels of inflammatory mediators such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), pro-inflammatory cytokines (tumor necrosis factor [TNF-α], interleukin [IL-1β and IL-6]), remarkable amelioration of colonic architectural disruption, and a significant reduction in the activity of colonic myeloperoxidase. To further confirm the anti-inflammatory property of SA, RAW 264.7 cells were stimulated with lipopolysaccharides. SA dose-dependently inhibited the cytokines TNF-α, IL-1β, and IL-6. It also decreased the expressions of p65-NF-κB and IκB, thus reducing the activation and nuclear accumulation of p-STAT-3^Y705. This prohibited the degradation of inhibitory protein, IκB, as well as inhibited the nuclear translocation of p65-NF-κB in colonic tissue. It was concluded that SA has a potential to limit inflammation via inhibiting the p65-NF-κB and STAT3 signaling; hence it can be used for therapeutic purposes.     

Administration of geniposide ameliorates dextran sulfate sodium-induced colitis in mice via inhibition of inflammation and mucosal damage

Ulcerative colitis (UC), an idiopathic inflammatory bowel disease, not only affects millions of patients worldwide, but also increases the risk of colon cancer. Geniposide is an iridoid glycoside and has many biological activities such as anti-inflammatory and antioxidant. However, its protective efficacy and mechanism of action against UC are still unclear. In this study, we aimed to investigate the protective effects and mechanisms of geniposide on dextran sulfate sodium (DSS)-induced experimental colitis in mice. The results revealed that geniposide alleviated body weight loss, disease activity index, colon length shortening and colonic pathological damage induced by DSS. Geniposide significantly suppressed pro-inflammatory cytokines by regulating NF-κB and PPARγ pathways in vivo and in vitro. Furthermore, geniposide also significantly regulated the expressions of ZO-1 and occludin in DSS-induced experimental colitis in mice and lipopolysaccharide (LPS)-triggered inflammation in Caco-2 cells. These findings indicated that geniposide may be a new natural chemopreventive agent to combat UC.