Differences in the effects and action modes of gut commensals against dextran sulfate sodium-induced intestinal inflammation

Inflammatory bowel disease(IBD)is a complex relapsing inflammatory disease in the gut and is driven by complicated host-gut microbiome interactions.Gut commensals have shown different functions in IBD prevention and treatment.To gain a mechanistic understanding of how different commensals affect intestinal inflammation,we compared the protective effects of 6 probiotics(belonging to the genera Akkermansia,Bifidobacterium,Clostridium,and Enterococcus)on dextran sulfate sodium(DSS)-induced colitis in mice with or without gut microbiota.Anti-inflammatory properties(ratio of interleukin(IL)-10 and IL-12)of these strains were also evaluated in an in vitro mesenteric lymph nodes(MLN)co-culture system.Results showed that 4 probiotics(belonging to the species Bifidobacterium breve,Bifidobacterium bifidum,and Enterococcus faecalis)can alleviate colitis in normal mice.The probiotic strains differed in regulating the intestinal microbiota,cytokines(IL-10,IL-1βand interferon(IFN)-γ),and tight junction function(Zonulin-1 and Occludin).By constrast,Akkermansia muciniphila AH39 and Clostridium butyricum FHuNHHMY49T1 were not protective.Interestingly,B.breve JSNJJNM2 with high anti-inflammatory potential in the MLN model could relieve colitis symptoms in antibiotic cocktail(Abx)-treated mice.Meanwhile,E.faecalis FJSWX25M1induced low levels of cytokines in vitro and showed no beneficial effects.Therefore,we provided insight into the clinical application of probiotics in IBD treatment.

Alkaline sphingomyelinase deficiency impairs intestinal mucosal barrier integrity and reduces antioxidant capacity in dextran sulfate sodium-induced colitis

BACKGROUND Ulcerative colitis is a chronic inflammatory disease of the colon with an unknown etiology.Alkaline sphingomyelinase(alk-SMase)is specifically expressed by intestinal epithelial cells,and has been reported to play an anti-inflammatory role.However,the underlying mechanism is still unclear.AIM To explore the mechanism of alk-SMase anti-inflammatory effects on intestinal barrier function and oxidative stress in dextran sulfate sodium(DSS)-induced colitis.METHODS Mice were administered 3%DSS drinking water,and disease activity index was determined to evaluate the status of colitis.Intestinal permeability was evaluated by gavage administration of fluorescein isothiocyanate dextran,and bacterial translocation was evaluated by measuring serum lipopolysaccharide.Intestinal epithelial cell ultrastructure was observed by electron microscopy.Western blotting and quantitative real-time reverse transcription-polymerase chain reaction were used to detect the expression of intestinal barrier proteins and mRNA,respectively.Serum oxidant and antioxidant marker levels were analyzed using commercial kits to assess oxidative stress levels.RESULTS Compared to wild-type(WT)mice,inflammation and intestinal permeability in alk-SMase knockout(KO)mice were more severe beginning 4 d after DSS induction.The mRNA and protein levels of intestinal barrier proteins,including zonula occludens-1,occludin,claudin-3,claudin-5,claudin-8,mucin 2,and secretory immunoglobulin A,were significantly reduced on 4 d after DSS treatment.Ultrastructural observations revealed progressive damage to the tight junctions of intestinal epithelial cells.Furthermore,by day 4,mitochondria appeared swollen and degenerated.Additionally,compared to WT mice,serum malondialdehyde levels in KO mice were higher,and the antioxidant capacity was significantly lower.The expression of the transcription factor nuclear factor erythroid 2-related factor 2(Nrf2)in the colonic mucosal tissue of KO mice was significantly decreased after DSS treatment.mRNA levels of Nrf2-regulated downstream antioxidant enzymes were also decreased.Finally,colitis in KO mice could be effectively relieved by the injection of tertiary butylhydroquinone,which is an Nrf2 activator.CONCLUSION Alk-SMase regulates the stability of the intestinal mucosal barrier and enhances antioxidant activity through the Nrf2 signaling pathway.

包裹有CTA1-DD蛋白的OCS-DS纳米颗粒的制备及佐剂活性

重组CTA1-DD蛋白具有与完整CT分子相当的全身性和黏膜佐剂功能,但在复杂的生理环境中易被酶或酸降解。本研究以同样具有佐剂活性的O-羧甲基壳聚糖(OCS)和硫酸葡聚糖(DS)为载体,通过离子交联形成纳米颗粒,将CTA1-DD蛋白嵌入其中,使其得到稳定保护。包裹有CTA1-DD蛋白的OCS-DS纳米颗粒的粒径为50~150 nm,Zeta电位约-50 mV,质量浓度1.0 mg/ml的CTA1-DD蛋白投入制备的包裹有CTA1-DD蛋白的OCS-DS纳米颗粒载药率25.33%,包封率86.56%。体外模拟释放试验结果显示CTA1-DD蛋白可在7 d内缓慢释放。将CTA1-DD蛋白与PRV灭活抗原混合后,接种至小鼠鼻腔,结果表明,包裹有CTA1-DD蛋白的OCS-DS纳米颗粒能够同时诱导更高的血清IgG抗体和黏膜IgA抗体表达,证明了其作为黏膜佐剂的高效性。

Dextran sodium sulfate colitis murine model: An indispensable tool for advancing our understanding of inflammatory bowel diseases pathogenesis

Inflammatory bowel diseases(IBD),including Crohn's disease and ulcerative colitis,are complex diseases that result from the chronic dysregulated immune response in the gastrointestinal tract. The exact etiology is not fully understood,but it is accepted that it occurs when an inappropriate aggressive inflammatory respon-se in a genetically susceptible host due to inciting environmental factors occurs. To investigate the path-ogenesis and etiology of human IBD,various animal models of IBD have been developed that provided indispensable insights into the histopathological and morphological changes as well as factors associated with the pathogenesis of IBD and evaluation of therapeutic options in the last few decades. The most widely used experimental model employs dextran sodium sulfate(DSS) to induce epithelial damage. The DSS colitis model in IBD research has advantages over other various chemically induced experimental models due to its rapidity,simplicity,reproducibility and controllability. In this manuscript,we review the newer publicized advances of research in murine colitis models that focus upon the disruption of the barrier function of the intestine,effects of mucin on the development of colitis,alterations found in microbial balance and resultant changes in the metabolome specifically in the DSS colitis murine model and its relation to the pathogenesis of IBD.

Negative impact of bone-marrow-derived mesenchymal stem cells on dextran sulfate sodium-induced colitis

AIM:To investigate the effects of mesenchymal stem cells(MSCs)on dextran sulfate sodium-induced inflammatory bowel disease(IBD).METHODS:C57BL/6 mice were fed 3.5%(g/L)dextran sulfate sodium.On day seven,the mice received intraperitoneal injections of 1×106 MSCs.The survival rate,disease activity index values,and body weight,were monitored daily.On day ten,colon lengths and histopathologic changes were assessed.In addition,immunoregulatory changes following MSC administration were evaluated by determining the levels of effector T cell responses in the spleen and mesenteric lymph nodes,and the expression levels of inflammatory cytokines in homogenized colons.RESULTS:Intraperitoneal administration of MSCs did not prevent development of colitis and did not reduce the clinicopathologic severity of IBD.No significant difference was evident in either survival rate or disease activity index score between the control and MSCtreated group.Day ten-sacrificed mice exhibited no significant difference in either colon length or histopathologic findings.Indeed,the MSC-treated group exhibited elevated levels of interleukin(IL)-6 and transforming growth factor-β,and a reduced level of IL-10,in spleens,mesenteric lymph nodes,and homogenized colons.The IL-17 level was lower in the mesenteric lymph nodes of the MSC-treated group(P=0.0126).In homogenized colons,the IL-17 and tumor necrosis factor-α(P=0.0092)expression levels were also lower in the treated group.CONCLUSION:MSC infusion provided no significanthistopathologic or clinical improvement,thus representing a limited therapeutic approach for IBD.Functional enhancement of MSCs is needed in further study.

Temporal clinical, proteomic, histological and cellular immune responses of dextran sulfate sodium-induced acute colitis

AIM To investigate the temporal clinical, proteomic, histological and cellular immune profiles of dextran sulfate sodium(DSS)-induced acute colitis.METHODS Acute colitis was induced in C57 BL/6 female mice by administration of 1%, 2% or 3% DSS in drinking water for 7 d. Animals were monitored daily for weight loss, stool consistency and blood in the stool, while spleens and colons were harvested on day 8. A time course analysis was performed in mice ingesting 3% DSS, which included colon proteomics through multiplex assay, colon histological scoring by a blinded investigator, and immune response through flow cytometry or immunohistochemistry of the spleen, mesenteric lymph node and colon.RESULTS Progressive worsening of clinical colitis was observed with increasing DSS from 1% to 3%. In mice ingesting 3% DSS, colon shortening and increase in proinflammatory factors starting at day 3 was observed, with increased spleen weights at day 6 and day 8. This coincided with cellular infiltration in the colon from day 2 to day 8, with progressive accumulation of macrophages F4/80^+, T helper CD4^+(Th), T cytotoxic CD8^+(Tcyt) and T regulatory CD25^+(Treg) cells, and progressive changes in colonic pathology including destruction of crypts, loss of goblet cells and depletion of the epithelial barrier. Starting on day 4, mesenteric lymph node and/or spleen presented with lower levels of Treg, Th and Tcyt cells, suggesting an immune cell tropism to the gut. CONCLUSION These results demonstrate that the severity of experimental colitis is dependent on DSS concentration, correlated with clinical, proteomic, histological and cellular immune response on 3% DSS.

Resveratrol alleviates intestinal mucosal barrier dysfunction in dextran sulfate sodium-induced colitis mice by enhancing autophagy

BACKGROUND Intestinal mucosal barrier dysfunction plays an important role in the pathogenesis of ulcerative colitis(UC).Recent studies have revealed that impaired autophagy is associated with intestinal mucosal dysfunction in the mucosa of colitis mice.Resveratrol exerts anti-inflammatory functions by regulating autophagy.AIM To investigate the effect and mechanism of resveratrol on protecting the integrity of the intestinal mucosal barrier and anti-inflammation in dextran sulfate sodium(DSS)-induced ulcerative colitis mice.METHODS Male C57BL/6 mice were divided into four groups:negative control group,DSS model group,DSS+resveratrol group,and DSS+5-aminosalicylic acid group.The severity of colitis was assessed by the disease activity index,serum inflammatory cytokines were detected by enzyme-linked immunosorbent assay.Colon tissues were stained with haematoxylin and eosin,and mucosal damage was evaluated by mean histological score.The expression of occludin and ZO-1 in colon tissue was evaluated using immunohistochemical analysis.In addition,the expression of autophagy-related genes was determined using reverse transcription-polymerase chain reaction and Western-blot,and morphology of autophagy was observed by transmission electron microscopy.RESULTS The resveratrol treatment group showed a 1.72-fold decrease in disease activity index scores and 1.42,3.81,and 1.65-fold decrease in the production of the inflammatory cytokine tumor necrosis factor-α,interleukin-6 and interleukin-1β,respectively,in DSS-induced colitis mice compared with DSS group(P<0.05).The expressions of the tight junction proteins occludin and ZO-1 in DSS model group were decreased,and were increased in resveratrol-treated colitis group.Resveratrol also increased the levels of LC3B(by 1.39-fold compared with DSS group)and Beclin-1(by 1.49-fold compared with DSS group)(P<0.05),as well as the number of autophagosomes,which implies that the resveratrol may alleviate intestinal mucosal barrier dysfunction in DSS-induced UC mice by enhancing autophagy.CONCLUSION Resveratrol treatment decreased the expression of inflammatory factors,increased the expression of tight junction proteins and alleviated UC intestinal mucosal barrier dysfunction;this effect may be achieved by enhancing autophagy in intestinal epithelial cells.

Kefir treatment ameliorates dextran sulfate sodium-induced colitis in rats

AIM: To investigate the preventive effect of kefir on colitis induced with dextran sulfate sodium(DSS) in rats.METHODS: Twenty-four male Wistar-albino rats were randomized into four groups: normal control,kefircontrol,colitis,and kefir-colitis groups. Rats in the normal and kefir-control groups were administered tap water as drinking water for 14 d. Rats in the colitis and kefir-colitis groups were administered a 3% DSS solution as drinking water for 8-14 d to induce colitis. Rats in the kefir-control and kefir-colitis groups were administered 5 m L kefir once a day for 14 d while rats in the normal control and colitis group were administered an identical volume of the placebo(skim milk) using an orogastric feeding tube. Clinical colitis was evaluated with reference to the disease activity index(DAI),based on daily weight loss,stool consistency,and presence of bleeding in feces. Rats were sacrificed on the 15 th day,blood specimens were collected,and colon tissues were rapidly removed. Levels of myeloperoxidase(MPO),tumor necrosisfactor(TNF)-α,interleukin(IL)-10,malondialdehyde,and inducible nitric oxide synthase(i NOS) were measured in colon tissue.RESULTS: The DAI was lower in the kefir-colitis group than in the colitis group(on the 3rd and 5th days of colitis induction; P < 0.01). The DAI was also significantly higher in the colitis group between days 2 and 6 of colitis induction when compared to the normal control and kefir-control groups. The DAI was statistically higher only on the 6th day in the kefircolitis group when compared to that in the normal control groups. Increased colon weight and decreased colon length were observed in colitis-induced rats. Mean colon length in the colitis group was significantly shorter than that of the kefir-control group. Kefir treatment significantly decreased histologic colitis scores(P < 0.05). MPO activity in the colitis group was significantly higher than in the kefir-control group(P < 0.05). Kefir treatment significantly reduced the DSS colitis-induced TNF-α increase(P < 0.01). No statistically significant differences were observed among groups for IL-10 and MDA levels. Colon tissue i NOS levels in the colitis group were significantly higher than those in the control and kefir-colitis groups(P < 0.05).CONCLUSION: Kefir reduces the clinical DAI and histologic colitis scores in a DSS-induced colitis model,possibly via reduction of MPO,TNF-α,and i NOS levels.

Dextran sulfate sodium-induced acute colitis impairs dermal lymphatic function in mice

AIM: To investigate whether dermal lymphatic function and architecture are systemically altered in dextran sulfate sodium(DSS)-induced acute colitis.METHODS: Balb/c mice were administered 4% DSS in lieu of drinking water ad libitum for 7 d and monitored to assess disease activity including body weight, diarrhea severity, and fecal bleeding. Control mice received standard drinking water with no DSS. Changes in mesenteric lymphatics were assessed following oral administration of a fluorescently-labelled fatty acid analogue, while dermal lymphatic function and architecture was longitudinally characterized using dynamic near-infrared fluorescence(NIRF) imaging following intradermal injection of indocyanine green(ICG) at the base of the tail or to the dorsal aspect of the left paw prior to, 4, and 7 d after DSSadministration. We also measured dye clearance rate after injection of Alexa680-bovine serum albumin(BSA). NIRF imaging data was analyzed to reveal lymphatic contractile activity after selecting fixed regions of interest(ROIs) of the same size in fluorescent lymphatic vessels on fluorescence images. The averaged fluorescence intensity within the ROI of each fluorescence image was plotted as a function of imaging time and the lymphatic contraction frequency was computed by assessing the number of fluorescent pulses arriving at a ROI. RESULTS: Mice treated with DSS developed acute inflammation with clinical symptoms of loss of body weight, loose feces/watery diarrhea, and fecal blood, all of which were aggravated as disease progressed to 7 d. Histological examination of colons of DSS-treated mice confirmed acute inflammation, characterized by segmental to complete loss of colonic mucosa with an associated chronic inflammatory cell infiltrate that extended into the deeper layers of the wall of the colon, compared to control mice. In situ intravital imaging revealed that mice with acute colitis showed significantly fewer fluorescent mesenteric lymphatic vessels, indicating impaired uptake of a lipid tracer within mesenteric lymphatics. Our in vivo NIRF imaging data demonstrated dilated dermal lymphatic vessels, which were confirmed by immunohistochemical staining of lymphatic vessels, and significantly reduced lymphatic contractile function in the skin of mice with DSS-induced acute colitis. Quantification of the fluorescent intensity remaining in the depot as a function of time showed that there was significantly higher Alexa680-BSA fluorescence in mice with DSSinduced acute colitis compared to pre-treatment with DSS, indicative of impaired lymphatic drainage.CONCLUSION: The lymphatics are locally and systemically altered in acute colitis, and functional NIRF imaging is useful for noninvasively monitoring systemic lymphatic changes during inflammation.

Protective effects of panax notoginseng saponin on dextran sulfate sodium-induced colitis in rats through phosphoinositide-3-kinase protein kinase B signaling pathway inhibition

BACKGROUND Intestinal inflammation is a common digestive tract disease, which is usually treated with hormone medicines. Hormone medicines are effective to some extent, but long-term use of them may bring about many complications.AIM To explore the protective effects of panax notoginseng saponin(PNS) against dextran sulfate sodium(DSS)-induced intestinal inflammatory injury through phosphoinositide-3-kinase protein kinase B(PI3K/AKT) signaling pathway inhibition in rats.METHODS Colitis rat models were generated via DSS induction, and rats were divided into control(no modeling), DSS, DSS + PNS 50 mg/k, and DSS + PNS 100 mg/kg groups. Then, the intestinal injury, oxidative stress parameters, inflammatory indices, tight junction proteins, apoptosis, macrophage polarization, and TLR4/AKT signaling pathway in colon tissues from rats in each of the groups were detected. The PI3 K/AKT signaling pathway in the colon tissue of rats was blocked using the PI3K/AKT signaling pathway inhibitor, LY294002.RESULTS Compared with rats in the control group, rats in the DSS group showed significantly shortened colon lengths, and significantly increased disease activity indices, oxidative stress reactions and inflammatory indices, as well as significantly decreased expression of tight junction-associated proteins. In addition, the DSS group showed significantly increased apoptotic cell numbers,and showed significantly increased M1 macrophages in spleen and colon tissues.They also showed significantly decreased M2 macrophages in colon tissues, as well as activation of the PI3K/AKT signaling pathway(all P < 0.05). Compared with rats in the DSS group, rats in the DSS + PNS group showed significantly lengthened colon lengths, decreased disease activity indices, and significantly alleviated oxidative stress reactions and inflammatory responses. In addition, this group showed significantly increased expression of tight junction-associated proteins, significantly decreased apoptotic cell numbers, and significantly decreased M1 macrophages in spleen and colon tissues. This group further showed significantly increased M2 macrophages in colon tissues, and significantly suppressed activation of the PI3K/AKT signaling pathway, as well as a dose dependency(all P < 0.05). When the PI3K/AKT signaling pathway was inhibited, the apoptosis rate of colon tissue cells in the DSS + LY294002 group was significantly lower than that of the DSS group(P < 0.05).CONCLUSION PNS can protect rats against DSS-induced intestinal inflammatory injury by inhibiting the PI3K/AKT signaling pathway, and therefore may be potentially used in the future as a drug for colitis.

Sodium selenite ameliorates dextran sulfate sodiuminduced chronic colitis in mice by decreasing Th1, Th17, and γδT and increasing CD4(+)CD25(+) regulatory T-cell responses

AIM To assess the effect of sodium selenite on the severity of dextran sulfate sodium(DSS)-induced colitis in C57BL/6 mice.METHODS Mice were randomly divided into four groups(n = 10/group): normal group, selenium(Se) group, chronic colitis group, and Se + chronic colitis group. The mice were sacrificed on day 26. Survival rates, clinical symptoms, colon length, and histological changes were determined. The percentages and absolute numbers of immune system cells in the lamina propria lymphocytes(LPL) of the colon, the expression of m RNA in colon tissue, and the concentrations of Th1, Th17, and Treg cytokines in LPL from the large intestine, were measured.RESULTS Se significantly ameliorated the symptoms of colitis and histological injury(P < 0.05 each), increasing the proportions of neutrophils and CD4+ CD25+ T cells(P < 0.05 each) and decreasing the proportions of γδT cells, CD4+, CD4+CD44+, and CD4+ CD69+ T cells in LPL(P < 0.05 each). Moreover, Se reduced the expression of IL-6, IFN-γ, IL-17 A, IL-21, T-bet, and RORγt(P < 0.05 each), but enhanced the expression of IL-10 and Foxp3(P < 0.05 each). CONCLUSION These results suggest that Se protects against DSSinduced chronic colitis perhaps by increasing the number of CD4(+)CD25(+) Tregs that suppress the secretion of proinflammatory cytokines and populations of Th1, Th17, and γδT cells.

New approach of medicinal herbs and sulfasalazine mixture on ulcerative colitis induced by dextran sodium sulfate

BACKGROUND Sulfasalazine has been used as a standard-of-care in ulcerative colitis for decades,however,it results in severe adverse symptoms,such as hepatotoxicity,blood disorders,male infertility,and hypospermia.Accordingly,the new treatment strategy has to enhance pharmacological efficacy and stimultaneously minimize side effects.AIM To compare the anti-inflammatory action of sulfasalazine alone or in combination with herbal medicine for ulcerative colitis in a dextran sodium sulfate(DSS)-induced colitis mouse model.METHODS To induce ulcerative colitis,mice received 5%DSS in drinking water for 7 d.Animals were divided into five groups(n=9 each)for use as normal(non-DSS),DSS controls,DSS+sulfasalazine(30 mg/kg)-treatment experimentals,DSS+sulfasalazine(60 mg/kg)-treatment experimentals,DSS+sulfasalazine(30 mg/kg)+Citrus unshiu peel and Bupleuri radix mixture(30 mg/kg)(SCPB)-treatment experimentals.RESULTS The SCPB treatment showed an outstanding effectiveness in counteracting the ulcerative colitis,as evidenced by reduction in body weight,improvement in crypt morphology,increase in antioxidant defenses,down-regulation of proinflammatory proteins and cytokines,and inhibition of proteins related to apoptosis.CONCLUSIONSCPB may represent a promising alternative therapeutic against ulcerative colitis,without inducing adverse effects.

Longitudinal analysis of inflammation and microbiota dynamics in a model of mild chronic dextran sulfate sodium-induced colitis in mice

AIM:To characterize longitudinally the inflammation and the gut microbiota dynamics in a mouse model of dextran sulfate sodium(DSS)-induced colitis.METHODS:In animal models,the most common method used to trigger colitis is based on the oral administration of the sulfated polysaccharides DSS.The murine DSS colitis model has been widely adopted to induce severe acute,chronic or semi-chronic colitis,and has been validated as an important model for the translation of mice data to human inflammatory bowel disease(IBD).However,it is now clear that models characterized by mild intestinal damage are more accurate for studying the effects of therapeutic agents.For this reason,we have developed a murine model of mild colitis to study longitudinally the inflammation and microbiota dynamics during the intestinal repair processes,and to obtain data suitable to support the recovery of gut microbiota-host homeostasis.RESULTS:All plasma cytokines evaluated,except IL-17,began to increase(P<0.05),after 7 d of DSS administration.IL-17 only began to increase 4 d after DSS withdrawal.IL-1βand IL-17 continue to increase during the recovery phase,even when clinical signs of colitis had disappeared.IL-6,IL-10 and IFN-γreached their maxima 4 d after DSS withdrawal and decreased during the late recovery phase.TNFαreached a peak(a three-fold increase,P<0.05),after which it slightly decreased,only to increase again close to the end of the recovery phase.DSS administration induced profound and rapid changes in the mice gut microbiota.After 3 d of DSS administration,we observed a major reduction in Bacteroidetes/Prevotella and a corresponding increase in Bacillaceae,with respect to control mice.In particular,Bacteroidetes/Prevotella decreased from a relative abundance of 59.42%-33.05%,while Bacillaceae showed a concomitant increase from 2.77%to 10.52%.Gut microbiota rapidly shifted toward a healthy profile during the recovery phase and returned normal 4 d after DSS withdrawal.Cyclooxygenase 2 expression started to increase 4 d after DSS withdrawal(P<0.05),when dysbiosis had recovered,and continued to increase during the recovery phase.Taken together,these data indicated that a chronic phase of intestinal inflammation,characterized by the absence of dysbiosis,could be obtained in mice using a single DSS cycle.CONCLUSION:Dysbiosis contributes to the local and systemic inflammation that occurs in the DSS model of colitis;however,chronic bowel inflammation is maintained even after recovery from dysbiosis.

Induction of experimental acute ulcerative colitis in rats by administration of dextran sulfate sodium at low concentration followed by intracolonic administration of 30% ethanol

Several models of experimental ulcerative colitis have been reported previously. However, none of these models showed the optimum characteristics. Although dextran sulfate sodium-induced colitis results in inflammation resembling ulcera-tive colitis, an obvious obstacle is that dextran sulfate sodium is very expensive. The aim of this study was to develop an inex-pensive model of colitis in rats. Sprague-Dawley rats were treated with 2% dextran sulfate sodium in drinking water for 3 d fol-lowed by an intracolonic administration of 30% ethanol. The administration of 2% dextran sulfate sodium followed by 30% ethanol induced significant weight loss, diarrhea and hematochezia in rats. Severe ulceration and inflammation of the distal part of rat colon were developed rapidly. Histological examination showed increased infiltration of polymorphonuclear leukocytes, lymphocytes and existence of cryptic abscesses and dysplasia. The model induced by dextran sulfate sodium at lower concentra-tion followed by 30% ethanol is characterized by a clinical course, localization of the lesions and histopathological features similar to human ulcerative colitis and fulfills the criteria set out at the beginning of this study.

Involvement of lymphocytes in dextran sulfate sodium-induced experimental colitis

瞄准：在葡聚糖硫酸盐的发展调查淋巴细胞的角色导致钠的大肠炎。方法：用葡聚糖硫酸盐钠(决策支持系统)的各种各样的剂量，我们在野类型的 B6 控制和 Rag-1 大美人( H-2b haplotype )导致了大肠炎鼠标，并且评估了大肠炎以征兆并且 histologic 参数例如重量损失，幸存，腹泻的严厉，冒号长度和组织学的变化的缺乏。征兆的参数每天被检查，组织学的变化被获得。结果：尽管在 Rag-1 猛烈老鼠的大肠炎的开发与决策支持系统的高剂量(5%) 对待比得上在 B6 控制老鼠，大肠炎前进在 Rag-1 猛烈老鼠与相比是更可容忍的比在与低剂量(1.5%) 对待的 B6 老鼠决策支持系统。征兆的参数以及组织病理学说的变化在 Rag-1 猛烈鼠标被改进。结论：这些结果显示淋巴细胞的存在在决策支持系统刺激的低剂量贡献大肠炎前进。淋巴细胞可以在导致决策支持系统的大肠炎作为一个加重的因素起作用。

Oral tolerance is inducible during active dextran sulfate sodium-induced colitis

AIM:To investigate whether oral tolerance is inducible during the active phase of dextran sulfate sodium(DSS)-induced colitis.METHODS:Colitis was induced in 6-to 8-wk-old female BALB/c mice by the administration of 2%DSS.To induce oral tolerance,mice that received water with DSS[DSS(+)]and mice that received autoclaved water[DSS(-)]were intragastrically(i.g.)administered ovalbumin(OVA)as a tolerogen before systemic challenge with OVA.Following this,serum levels of OVA-specific Ig E antibodies were measured.In mice with activecolitis,CD4+CD25+Foxp3+cell and B10 cell frequencies were evaluated using flow cytometry.Cytokine m RNA expression profiles were evaluated by reverse transcription real-time polymerase chain reaction.RESULTS:Regardless of the presence of DSS colitis,OVA-specific immunoglobulin E concentrations were significantly reduced in mice that were i.g.administered OVA compared to mice that were i.g.administered PBS[DSS(+):4.4(4.2-9.5)ng/m L vs 83.9(66.1-123.2)ng/m L,P<0.01;DSS(-):27.7(0.1-54.5)ng/m L vs116.5(80.6-213.6)ng/m L,P<0.01].These results demonstrated that oral tolerance was induced in both the presence and absence of colitis.In the spleen and mesenteric lymph nodes(MLN),the frequencies of CD4+CD25+Foxp3+cells and B10 cells,both of which are associated with oral tolerance,did not significantly change.In the spleen,interferon-γm RNA expression significantly decreased in mice with colitis[DSS(+):0.42(0.31-0.53)vs DSS(-):1.00(0.84-1.39),P<0.01].The expression levels of other cytokines did not significantly change.CONCLUSION:Oral tolerance is inducible during active DSS colitis.The stability of regulatory cell populations in the spleen and MLN in colitis might correlate with these results.

Ferruginol alleviates inflammation in dextran sulfate sodium-induced colitis in mice through inhibiting COX-2, MMP-9 and NF-κB signaling

Objective:To assess the anti-inflammatory efficacy of ferruginol on dextran sulfate sodium(DSS)stimulated ulcerative colitis mice.Methods:Ulcerative colitis was induced in C57 BL/6 J mice by administering 2%of DSS through drinking water for 7 d.The mice in the treatment group were treated with DAA+50 mg/kg/day ferruginol orally.In the positive control group,sulfasalazine(50 mg/kg/day)was used alongside with DSS.After induction,the bodyweight,character of stool and feces occult blood were recorded daily,the disease activity index was calculated,and the colon length,colon weight,and spleen weight were recorded.The myeloperoxidase activity was assayed by spectrophotometry.Interleukin(IL)-6,IL-1β,and tumor necrosis factor-αwere determined by ELISA method,and nuclear factor-κB,cyclooxygenase-2,matrix metalloproteinases-9,and inducible nitric oxide synthase by Western blotting assays.Results:Ferruginol significantly increased the bodyweight,colon weight,colon length,and decreased disease activity index and spleen weight.It exhibited anti-inflammatory activity against DSS induced ulcerative colitis in mice by reducing the activities of myeloperoxidase,tumor necrosis factor-α,nuclear factor-κB,IL-1β,cyclooxygenase-2,matrix metalloproteinases-9,IL-6,and inducible nitric oxide synthase.Conclusions:Ferruginol could be used to treat ulcerative colitis by attenuating the inflammation in colon cells and maintaining colonic mucosal barrier integrity.

Differential analysis of intestinal microbiota and metabolites in mice with dextran sulfate sodium-induced colitis

BACKGROUND Intestinal micro-ecological imbalances impair the intestinal barrier and induce intestinal inflammation,for example,ulcerative colitis(UC).According to the latest research,abnormalities in intestinal microbiota structure and their metabolites play a dominant role in UC progression;in addition,they could affect the mucus barrier based on different factors.Although numerous studies have confirmed the important role of intestinal microbiota in UC pathogenesis,the intricate connection between microbiota and metabolites and mucus barrier in UC occurrence remains unclear,and correlation analyses of differential microbiota and their metabolites under UC are relatively scarce.AIM To reveal the differential intestinal microbiota and metabolites in UC pathogenesis and explore more sensitive biomarker compositions.METHODS We used the antibiotic combination method to establish intestinal pseudo-aseptic mice;afterward,dextran sulfate sodium(DSS)was applied to establish an acute experimental colitis mice model.Colitis severity,assessed based on disease activity index,colorectal length,colorectal wet weight,and histological lesions,and mucus-related staining(mucopolysaccharide alcian blue and immunofluorescence of mucin),was compared between the pseudo-aseptic and bacterial colitis mice.Finally,differential intestinal microbiota,metabolites,and their association and correlations,were analyzed by 16s rDNA sequencing in combination with non-targeted metabolomics,through gas chromatography-mass spectrometry.RESULTS Compared with the pseudo-aseptic mice,intestinal bacteria positive mice were more severely ill and their intestinal mucus loss was more pronounced in DSS-induced colitis(P<0.05),suggesting that different microbiota and metabolites could cause the different degrees of colitis.Subsequently,we observed that in addition to Klebsiella,and Bacteroides,which were widely associated with colitis,Candidatus Stoquefichus,Anaerobiospirillum,Muribaculum,and Negativibacillus may be involved in protection against colitis.Furthermore,differential metabolites of the microbiota were mainly enriched in the synthesis-related pathways of key structural sequences of mucin.In combination with the mucin-related staining and immunofluorescence results,the findings indicate that the differential microbiota and their metabolites potentially regulate the composition and function of mucus under colitis.CONCLUSION Microbiota and their metabolites are major factors regulating the composition and function of mucus,in turn influencing the function and structure of intestinal mucus barrier under colitis.The different microbiota and metabolites identified in the present study could be novel biomarkers for colitis.

Calcitriol analog ZK191784 ameliorates acute and chronic dextran sodium sulfate-induced colitis by modulation of intestinal dendritic cell numbers and phenotype

AIM: To investigate the effects of ZK1916784, a low calcemic analog of calcitriol on intestinal inflammation. METHODS: Acute and chronic colitis was induced by dextran sodium sulfate (DSS) according to standard procedures. Mice were treated intraperitoneally with ZK1916784 or placebo and colonic inflammation was evaluated. Cytokine production by mesenterial lymph node (MLN) cells was measured by ELISA. Immunohistochemistry was performed to detect intestinal dendritic cells (DCs) within the colonic tissue, and the effect of the calcitriol analog on DCs was investigated. RESULTS: Treatment with ZK191784 resulted in significant amelioration of disease with a reduced histological score in acute and chronic intestinal inflammation. In animals with acute DSS colitis, down- regulation of colonic inflammation was associated with a dramatic reduction in the secretion of the proinflammatory cytokine interferon (IFN)-γ and a significant increase in intereleukin (IL)-10 by MLN cells. Similarly, in chronic colitis, IL-10 expression in colonic tissue increased 1.4-fold when mice were treated with ZK191784, whereas expression of the Th1-specific transcription factor T-beta decreased by 81.6%. Lower numbers of infiltrating activated CD11c+ DCs were found in the colon in ZK191784-treated mice with acute DSScolitis, and secretion of proinflammatory cytokines by primary mucosal DCs was inhibited in the presence of the calcitriol analog. CONCLUSION: The calcitriol analog ZK191784 demonstrated significant anti-inflammatory properties in experimental colitis that were at least partially mediated by the immunosuppressive effects of the derivate on mucosal DCs.