MicroRNA-155 promotes the pathogenesis of experimental colitis by repressing SHIP-1 expression

AIM To explore the mechanism by which microRNA-155 (miR-155) regulates the pathogenesis of experimental colitis. METHODS A luciferase assay was performed to confirm the binding of miR-155 to the SHIP-1 3'-UTR. MiR-155 mimics, negative controls and SHIP-1 expression/knockdown vectors were established and then utilized in gain-and loss-of-function studies performed in raw264.7 cells and primary bone marrow-derived macrophages (BMDMs). Thereafter, dextran sulfate sodium (DSS)-induced colitis mouse model with or without antagomiR-155 treatment was established, and the levels of miR-155 and SHIP-1, as well as the pro-inflammatory capabilities, were measured by western blot, quantitative polymerase chain reaction, and immunohistochemistry. RESULTS MiR-155 directly bound to the 3'-UTR of SHIP-1 mRNA and induced a significant decrease in SHIP-1 expression in both raw264.7 cells and primary BMDMs. MiR-155 markedly promoted cell proliferation and proinflammatory secretions including IL-6, TNF-alpha, IL-1 beta, and IFN-gamma, whereas these effects could be reversed by the restoration of SHIP-1 expression. In vivo studies showed that antagomiR-155 administration could alleviate DSS-induced intestinal inflammation in Balb/c mice. Moreover, significantly increased SHIP-1 expression, as well as decreased Akt activation and in-flammatory response, were observed in the antagomiR-155-treated mice. CONCLUSION MiR-155 promotes experimental colitis by repressing SHIP-1 expression. Thus, the inhibition of miR-155 might be a promising strategy for therapy.

Favorable response to subcutaneous administration of infliximab in rats with experimental colitis

AIM： To investigate the influence of infliximab （Remicade） on experimental colitis produced by 2,4,6,trinitrobenzene sulfonic add （TNBS） in rats. METHODS： Thirty-six Wistar rats were allocated into four groups （three groups of six animals each and a fourth of 12 animals）. Six more healthy animals served as normal controls （Group 5）. Group 1： colitis was induced by intracolonic installation of 25 mg of TNBS dissolved in 0.25 mL of 50% ethanol and infliximab was subcutaneously administered at a dose of 5 mg/kg BW; Group 2： colitis was induced and infliximab was subcutaneously administered at a dose of 10 mg/kg BW; Group 3： colitis was induced and infliximab was subcutaneously administered at a dose of 15 mg/kg BW; Group 4： colitis was induced without treatment with infliximab. Infliximab was administered on d 2-6. On the 7^th d, all animals were killed. The colon was fixed in 10% buffered formalin and examined by light microscopy for the presence and activity of colitis and the extent of tissue damage. Tumor necrosis factor-alpha （TNF-α） and malondialdehyde （MDA） were also measured. RESULTS： Significant differences concerning the presence of reparable lesions and the extent of bowel mucosa without active inflammation in all groups of animals treated with infliximab compared with controls were found. Significant reduction of the tissue levels of TNF-α in all groups of treated animals as compared with the untreated ones was found （0.47＋0.44, 1.09＋0.86, 0.43＋0.31 vs 18.73＋10.53 respectively）. Significant reduction in the tissue levels of MDA was noticed in group 1 as compared to group 4, as well as between groups 2 and 4. CONCLUSION： Subcutaneous administration of infliximab reduces the inflammatory activity as well as tissue TNF-α and MDA levels in chemical colitis in rats. Infliximab at a dose of 5 mg/kg BW achieves better histological results and produces higher reduction of the levels of TNF-α than at a dose of 10 mg/kg BW. Infliximab at a dose of 5 mg/kg BW produces higher reduction of tissue MDA levels than at a dose of 15 mg/ kg BW.

Therapeutic effects of four strains of probiotics on experimental colitis in mice

AIM:To investigate the therapeutic effects of four strains of probiotics(E.feacalis,L.acidophilus,C.butyricum and B.adolescentis) on dextran sulphate sodium(DSS)-induced experimental colitis in Balb/c mice.METHODS:Eighty Balb/c mice were randomly divided into 8 groups.Weight-loss,fecal character,fecal occult blood and hematochezia were recorded daily.Disease activity index(DAI) scores were also evaluated everyday.Length of colon was measured and histological scores were evaluated on the 13th day.Myeloperoxidase(MPO) activity was detected.Interleukin-1(IL-1) and IL-4 expression was detected by ELISA and RT-PCR.RESULTS:The four strains of probiotics relieved the inflammatory condition of DSS-induced experimental colitis in mice.Weight loss was slowed down in all probiotics-treated mice.Even weight gain was observed by the end of probiotics treatment.The DAI and histological scores of probiotics-treated mice were lower than those of mice in the control group(1.9 ± 0.2 vs 8.6 ± 0.4,P < 0.05 for E.faecalis).The length of colon of probiotics-treated mice was longer than that of mice in the control group(10.3 ± 0.34 vs 8.65 ± 0.77,P < 0.05 for E.faecalis).The four strains of probiotics decreased the MP activity and the IL-1 expression,but increased the IL-4 expression.E.faecalis had a better effect on DSS-induced experimental colitis in mice than the other three strains.CONCLUSION:The four strains of probiotics have beneficial effects on experimental colitis in mice.E.faecalis has a better effect on DSS-induced experimental colitis in mice than the other three strains.Supplement of probiotics provides a new therapy for UC.

Anti-inflammatory effect of cannabinoid agonist WIN55, 212 on mouse experimental colitis is related to inhibition of p38MAPK

AIM To investigate the anti-inflammatory effect and the possible mechanisms of an agonist of cannabinoid(CB) receptors, WIN55-212-2(WIN55), in mice with experimental colitis, so as to supply experimental evidence for its clinical use in future. METHODS We established the colitis model in C57BL/6 mice by replacing the animals' water supply with 4% dextran sulfate sodium(DSS) for 7 consecutive days. A colitis scoring system was used to evaluate the severity of colon local lesion. The plasma levels of proinflammatory cytokines, such as tumor necrosis factor-alpha(TNF-α) and interleukin-6(IL-6), and the myeloperoxidase(MPO) activity in colon tissue were measured. The expressions of cannabinoid receptors, claudin-1 protein, p38 mitogen-activated protein kinase(p38MAPK) and its phosphorylated form(p-p38) in colon tissue were determined by immunohistochemistry and Western blot. In addition, the effect of SB203580(SB), an inhibitor of p38, was investigated in parallel experiments, andthe data were compared with those from intervention groups of WIN55 and SB alone or used together. RESULTS The results demonstrated that WIN55 or SB treatment alone or together improved the pathological changes in mice with DSS colitis, decreased the plasma levels of TNF-α, and IL-6, and MPO activity in colon. The enhanced expression of claudin-1 and the inhibited expression of p-p38 in colon tissues were found in the WIN55-treated group. Besides, the expression of CB1 and CB2 receptors was enhanced in the colon after the induction of DSS colitis, but reduced when p38 MAPK was inhibited. CONCLUSION These results confirmed the anti-inflammatory effect and protective role of WIN55 on the mice with experimental colitis, and revealed that this agent exercises its action at least partially by inhibiting p38 MAPK. Furthermore, the results showed that SB203580, affected the expression of CB1 and CB2 receptors in the mouse colon, suggesting a close linkage and cross-talk between the p38 MAPK signaling pathway and the endogenous CB system.

Therapeutic effect of curcumin on experimental colitis mediated by inhibiting CD8^+ CD11c^+ cells

AIM To verify whether curcumin (Cur) can treat inflammatory bowel disease by regulating CD8(+)CD11c(+) cells. METHODS We evaluated the suppressive effect of Cur on CD8(+)CD11c(+) cells in spleen and Peyer's patches (PPs) in colitis induced by trinitrobenzene sulfonic acid. Mice with colitis were treated by 200 mg/kg Cur for 7 d. On day 8, the therapeutic effect of Cur was evaluated by visual assessment and histological examination, while co-stimulatory molecules of CD8(+)CD11c(+) cells in the spleen and PPs were measured by flow cytometry. The levels of interleukin (IL)-10, interferon (IFN)-gamma and transforming growth factor (TGF)-beta 1 in spleen and colonic mucosa were determined by ELISA. RESULTS The disease activity index, colon weight, weight index of colon and histological score of experimental colitis were obviously decreased after Cur treatment, while the body weight and colon length recovered. After treatment with Cur, CD8(+)CD11c(+) cells were decreased in the spleen and PPs, and the expression of major histocompatibility complex., CD205, CD40, CD40L and intercellular adhesion molecule-1 was inhibited. IL-10, IFN-gamma and TGF-beta 1 levels were increased compared with those in mice with untreated colitis. CONCLUSION Cur can effectively treat experimental colitis, which is realized by inhibiting CD8(+)CD11c(+) cells.

Probiotic yeasts: Anti-inflammatory potential of various non-pathogenic strains in experimental colitis in mice

AIM: To evaluate the in vitro immunomodulation capacity of various non-pathogenic yeast strains and to investigate the ability of some of these food grade yeasts to prevent experimental colitis in mice.METHODS: In vitro immunomodulation was assessed by measuring cytokines [interleukin (IL)-12p70,IL-10,tumor necrosis factor and interferon γ] released by human peripheral blood mononuclear cells after 24 h stimulation with 6 live yeast strains (Saccharomyces ssp.) and with bacterial reference strains.A murine model of acute 2-4-6-trinitrobenzene sulfonic acid (TNBS)-colitis was next used to evaluate the distinct prophylactic protective capacities of three yeast strains compared with the performance of prednisolone treatment.RESULTS: The six yeast strains all showed similar non-discriminating anti-inflammatory potential when tested on immunocompetent cells in vitro .However,although they exhibited similar colonization patterns in vivo ,some yeast strains showed significant anti-inflammatory activities in the TNBS-induced colitis model,whereas others had weaker or no preventive effect at all,as evidenced by colitis markers (body-weight loss,macroscopic and histological scores,myeloperoxidase activities and blood inflammatory markers).CONCLUSION: A careful selection of strains is required among the biodiversity of yeasts for specific clinical studies,including applications in inflammatory bowel disease and other therapeutic uses.

Effects of Intestinal Trefoil Factor on Colonic Mucosa in Experimental Colitis of Rats

In order to investigate the protective effects of intestinal trefoil factor (ITF) on colonic mucosa in experimental colitis of rats, ITF was detected by RT-PCR and immunohistochemistry at different time points. Three days after colitis induction, rats were treated with either 0.9 % saline solution or rhITF. Pathological changes and the expression of iNOS mRNA, NO, MDA and SOD were measured respectively. It was found that ITF was mainly located in goblet cells, significantly higher in model group than in normal group (P<0.05). rhITF could increase the iNOS mRNA expression and NO contents, and there was statistically significant difference between rhITF group and model group (P<0.05). rhITF also caused an increase of MDA and a decrease of SOD, but there was no significant difference between two groups. These results indicated that ITF has apparent therapeutic effects in ulcerative colitis, which may be associated with iNOS and NO.

Curcumin alleviates experimental colitis via a potential mechanism involving memory B cells and Bcl-6-Syk-BLNK signaling

BACKGROUND Immune dysfunction is the crucial cause in the pathogenesis of inflammatory bowel disease(IBD),which is mainly related to lymphocytes(T or B cells,including memory B cells),mast cells,activated neutrophils,and macrophages.As the precursor of B cells,the activation of memory B cells can trigger and differentiate B cells to produce a giant variety of inducible B cells and tolerant B cells,whose dysfunction can easily lead to autoimmune diseases,including IBD.AIM To investigate whether or not curcumin(Cur)can alleviate experimental colitis by regulating memory B cells and Bcl-6-Syk-BLNK signaling.METHODS Colitis was induced in mice with a dextran sulphate sodium(DSS)solution in drinking water.Colitis mice were given Cur(100 mg/kg/d)orally for 14 consecutive days.The colonic weight,colonic length,intestinal weight index,occult blood scores,and histological scores of mice were examined to evaluate the curative effect.The levels of memory B cells in peripheral blood of mice were measured by flow cytometry,and IL-1β,IL-6,IL-10,IL-7A,and TNF-αexpression in colonic tissue homogenates were analyzed by enzyme-linked immunosorbent assay.Western blot was used to measure the expression of Bcl-6,BLNK,Syk,and other signaling pathway related proteins.RESULTS After Cur treatment for 14 d,the body weight,colonic weight,colonic length,colonic weight index,and colonic pathological injury of mice with colitis were ameliorated.The secretion of IL-1β,IL-6,TNF-α,and IL-7A was statistically decreased,while the IL-35 and IL-10 levels were considerably increased.Activation of memory B cell subsets in colitis mice was confirmed by a remarkable reduction in the expression of IgM,IgG,IgA,FCRL5,CD103,FasL,PD-1,CD38,and CXCR3 on the surface of CD19^(+)CD27^(+)B cells,while the number of CD19^(+)CD27^(+)IL-10^(+)and CD19^(+)CD27^(+)Tim-3^(+)B cells increased significantly.In addition,Cur significantly inhibited the protein levels of Syk,p-Syk,Bcl-6,and CIN85,and increased BLNK and p-BLNK expression in colitis mice.CONCLUSION Cur could effectively alleviate DSS-induced colitis in mice by regulating memory B cells and the Bcl-6-Syk-BLNK signaling pathway.

P2X7 receptor antagonist recovers ileum myenteric neurons after experimental ulcerative colitis

BACKGROUND The P2X7 receptor is expressed by enteric neurons and enteric glial cells.Studies have demonstrated that administration of a P2X7 receptor antagonist,brilliant blue G(BBG),prevents neuronal loss.AIM To report the effects of BBG in ileum enteric neurons immunoreactive(ir)following experimental ulcerative colitis in Rattus norvegicus albinus.METHODS 2,4,6-trinitrobenzene sulfonic acid(TNBS group,n=5)was injected into the distal colon.BBG(50 mg/kg,BBG group,n=5)or vehicle(sham group,n=5)was given subcutaneously 1 h after TNBS.The animals were euthanized after 24 h,and the ileum was removed.Immunohistochemistry was performed on the myenteric plexus to evaluate immunoreactivity for P2X7 receptor,neuronal nitric oxide synthase(nNOS),choline acetyltransferase(ChAT),HuC/D and glial fibrillary acidic protein.RESULTS The numbers of nNOS-,ChAT-,HuC/D-ir neurons and glial fibrillary acidic protein-ir glial cells were decreased in the TNBS group and recovered in the BBG group.The neuronal profile area(μm^2)demonstrated that nNOS-ir neurons decreased in the TNBS group and recovered in the BBG group.There were no differences in the profile areas of ChAT-and HuC/D-ir neurons.CONCLUSION Our data conclude that ileum myenteric neurons and glial cells were affected by ulcerative colitis and that treatment with BBG had a neuroprotective effect.Thus,these results demonstrate that the P2X7 receptor may be an important target in therapeutic strategies.

FR167653,a p38 mitogen-activated protein kinase inhibitor,aggravates experimental colitis in mice

AIM: To investigate the effects of FR167653 on the development of dextran sulfate sodium (DSS)-induced colitis in mice. METHODS: BALB/c mice were fed rodent chow containing 3.5% (wt/wt) DSS. The recipient mice underwent intra-peritoneal injection of vehicles or FR167653 (30 mg/kg per day). The mice were sacrificed on day 14, and the degree of colitis was assessed. Immunohistochemical analyses for CD4+ T cell and F4/80+ macrophage infiltration were also performed. Mucosal cytokine expression was analyzed by RT-PCR. RESULTS: The body weight loss was more apparent in the FR167653-treated DSS mice than in the vehicle- treated DSS mice. The colon length was shorter in the FR167653-treated DSS mice than in the vehicle-treated DSS mice. Disease activity index and histological colitis score were significantly higher in FR167653- than in vehicle-treated DSS animals. Microscopically, mucosal edema, cellular infiltration (CD4 T cells and F4/80 macrophages), and the disruption of the epithelium were much more severe in FR167653-treated mice than in controls. Mucosal mRNA expression for interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were found to be markedly reduced in FR167653-treated DSS mice. CONCLUSION: Treatment with FR167653 aggravated DSS colitis in mice. This effect was accompanied by a reduction of mucosal IL-1β and TNF-α expression, suggesting a role of p38 mitogen-activated protein kinase (MAPK)-mediated proinflammatory cytokine induction in host defense mechanisms.

Antioxidative potential of a combined therapy of anti TNFα and Zn acetate in experimental colitis

AIM:To evaluate whether combination therapy with antitumour necrosis factor α (TNFα) antibody and Zn acetate is beneficial in dextran sodium sulphate (DSS) colitis.METHODS:Colitis was induced in CD1-Swiss mice with 5% DSS for 7 d.The experimental mice were then randomised into the following subgroups:standard diet + DSS treated (induced colitis group);standard diet + DSS + subcutaneous 25 μg anti-TNFα treated group;Zn acetate treated group + DSS + subcutaneous 25 μg anti-TNFα;standard diet + DSS + subcutaneous 6.25 μg anti-TNFα treated group and Zn acetate treated group + DSS + subcutaneous 6.25 μg anti-TNFα.Each group of mice was matched with a similar group of sham control animals.Macroscopic and histological features were scored blindly.Homogenates of the colonic mucosa were assessed for myeloperoxidase activity as a biochemical marker of inflammation and DNA adducts (8OH-dG) as a measure of oxidative damage.RESULTS:DSS produced submucosal erosions,ulcers,inflammatory cell infiltration and cryptic abscesses which were reduced in both groups of mice receiving either anti-TNFα alone or combined with zinc.The effect was more pronounced in the latter group (vs Zn diet,P < 0.02).Myeloperoxidase activity (vs controls,P < 0.02) and DNA adducts,greatly elevated in the DSS fed colitis group (vs controls,P < 0.05),were significantly reduced in the treated groups,with a more remarkable effect in the group receiving combined therapy (vs standard diet,P < 0.04).CONCLUSION:DSS induces colonic inflammation which is modulated by the administration of anti-TNFα.Combining anti-TNFα with Zn acetate offers marginal benefit in colitis severity.

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.

Insights from advances in research of chemically induced experimental models of human inflammatory bowel disease

Inflammatory bowel disease(IBD),the most important being Crohn's disease and ulcerative colitis,results from chronic dysregulation of the mucosal immune system in the gastrointestinal tract.Although the pathogenesis of IBD remains unclear,it is widely accepted that genetic,environmental,and immunological factors are involved.Recent studies suggest that intestinal epithelial defenses are important to prevent inflammation by protecting against microbial pathogens and oxidative stresses.To investigate the etiology of IBD,animal models of experimental colitis have been developed and are frequently used to evaluate new anti-inflammatory treatments for IBD.Several models of experimental colitis that demonstrate various pathophysiological aspects of the human disease have been described.In this manuscript,we review the characteristic features of IBD through a discussion of the various chemically induced experimental models of colitis(e.g.dextran sodium sulfate-,2,4,6-trinitrobenzene sulfonic acid-,oxazolone-,acetic acid-,and indomethacin-induced models).We also summarize some regulatory and pathogenic factors demonstrated by these models that can,hopefully,be exploited to develop future therapeutic strategies against IBD.

Attenuation of dextran sodium sulphate induced colitis in matrix metalloproteinase-9 deficient mice

AIM: To study whether matrix metalloproteinase-9 (MMP-9) is a key factor in epithelial damage in the dextran sodium sulphate (DSS) model of colitis in mice.METHODS: MMP-9-deficient and wild-type (wt) mice were given 5% DSS in drinking water for 5 d followed by recovery up to 7 d. On d 5 and 12 after induction of colitis, gelatinases, MMP-2 and MMP-9, were measured in homogenates of colonic tissue by zymography and Western blot, whereas tissue inhibitor of metalloproteinases (TIMPs) were measured by reverse zymography. The gelatinolytic activity was also determined in supernatants of polymorphonuclear leukocytes (PMN) isolated from mice blood. Moreover, intestinal epithelial cells were stimulated with TNF-α to study whether these cells were able to produce MMPs. Finally, colonic mucosal lesions were measured by microscopic examination. RESULTS: On d 5 of colitis, the activity of MMP-9 was increased in homogenates of colonic tissues (0.24 ± 0.1 vs 21.3 ± 6.4, P < 0.05) and PMN from peripheral blood in wt (0.5 ± 0.1 vs 10.4 ± 0.7, P < 0.05), but not in MMP-9-deficient animals. The MMP-9 activity was also up-regulated by TNF-α in epithelial intestinal cells (2.5 ± 0.5 vs 14.7 ± 3.0, P < 0.05). Although colitis also led to increase of TIMP-1 activity, the MMP-9/TIMP-1 balance remained elevated. Finally, in the MMP-9-deficient colitic mice both the extent and severity of intestinal epithelialinjury were significantly attenuated when compared with wt mice. CONCLUSION: We conclude that DSS induced colitis is markedly attenuated in animals lacking MMP-9. This suggests that intestinal injury induced by DSS is modu-lated by MMP-9 and that inhibition of this gelatinase may reduce inflammation.

Therapeutic and prophylactic thalidomide in TNBS-induced colitis: Synergistic effects on TNF-α, IL-12 and VEGF production

AIM： To evaluated the therapeutic and prophylactic effect of thalidomide on 2, 4, 6-trinitrobenzene sulfonic acid （TNBS）-induced colitis. Thalidomide has been reported to downregulate the expression of tumor necrosis factor α （TNF-α）, IL-12, and vascular endothelial growth factor （VEGF）, hallmarks of intestinal inflammation in Crohn＇s disease （CD）. METHODS： Male Wistar rats were divided in five groups of ten animals each. Four groups received a rectal infusion of TNBS in ethanol. The first group was sacrificed 7 d after colitis induction. The second and third groups received either thalidomide or placebo by gavage and were sacrificed at 14 d. The fourth group received thalidomide 6 h before TNBS administration, and was sacrificed 7 d after induction. The fifth group acted as the control group and colitis was not induced. Histological inflammatory scores of the colon were performed and lamina propria CD4＋ T cells, macrophages, and VEGF＋ cells were detected by immunohistochemistry. TNF-α and IL-12 were quantified in the supernatant of organ cultures by ELISA. RESULTS： Significant reduction in the inflammatory score and in the percentage of VEGF＋ cells was observed in the group treated with thalidomide compared with animals not treated with thalidomide. Both TNF-α and IL-12 levels were significantly reduced among TNBS induced colitis animals treated with thalidomide compared with animals that did not receive thalidomide. TNF-α levels were also significantly reduced among the animals receiving thalidomide prophylaxis compared with untreated animals with TNBS-induced colitis. Intestinal levels of TNF-α and IL-12 were significantly correlated with the inflammatory score and the number of VEGF＋ cells. CONCLUSION： Thalidomide significantly attenuates TNBS-induced colitis by inhibiting the intestinal production of TNF-α, IL-12, and VEGF. This effect may support the use of thalidomide as an alternate approach in selected patients with CD.

Juvenile ferric iron prevents microbiota dysbiosis and colitis in adult rodents

AIM: To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice. METHODS: Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe2+) iron salt or ferric (Fe3+) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated usingquantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria. RESULTS: Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg proteinvs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po - 6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po - 6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood.CONCLUSION: Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.

Effect of Baicalin on TNBS-Induced Colonic Inflammatory Injury in Rats

Objective: The aim is to observe the protective effect of baicalin on trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis in mice and explore its mechanism. Methods: The mice were divided into 4 groups: ethanol control group, TNBS model group, baicalin low-dose group and baicalin high-dose group. The model of experimental colitis in mice was induced by TNBS enema. After 2 hours of TNBS enema, baicalin was given by gavage, QD × 7D. The animals were sacrificed on the 8th day to observe the extent of colonic mucosal damage, and the Peroxidase activity, Malondialdehyde (MDA) and glutathione (GSH) contents were measured. Results: Compared with the TNBS model group, the body weight, gross injury score and histological changes were significantly improved;MPO enzyme activity and MDA content were significantly decreased in the low and high-dose baicalin groups;and the content of glutathione increased. Conclusion: Baicalin can alleviate TNBS-induced colitis in mice, and the mechanism is related to the antioxidation of baicalin.

Colon-specific prodrugs of 4-aminosalicylic acid for inflammatory bowel disease

Despite the advent of biological products, such as anti-tumor necrosis factor-&#x003b1; monoclonal antibodies (infliximab and adalimumab), for treatment of moderate to severe cases of inflammatory bowel disease (IBD), most patients depend upon aminosalicylates as the conventional treatment option. In recent years, the increased knowledge of complex pathophysiological processes underlying IBD has resulted in development of a number of newer pharmaceutical agents like low-molecular-weight heparin, omega-3 fatty acids, probiotics and innovative formulations such as high-dose, once-daily multi-matrix mesalamine, which are designed to minimize the inflammatory process through inhibition of different targets. Optimization of delivery of existing drugs to the colon using the prodrug approach is another attractive alternative that has been utilized and commercialized for 5-aminosalicylic acid (ASA) in the form of sulfasalazine, balsalazide, olsalazine and ipsalazine, but rarely for its positional isomer 4-ASA - a well-established antitubercular drug that is twice as potent as 5-ASA against IBD, and more specifically, ulcerative colitis. The present review focuses on the complete profile of 4-ASA and its advantages over 5-ASA and colon-targeting prodrugs reported so far for the management of IBD. The review also emphasizes the need for reappraisal of this promising but unexplored entity as a potential treatment option for IBD.

Rebamipide promotes healing of colonic ulceration through enhanced epithelial restitution

AIM:To investigate the efficacy of rebamipide in a rat model of colitis and restitution of intestinal epithelial cells in vitro.METHODS:Acute colitis was induced with trinitrobenzene sulfonic acid(TNBS)in male Wistar rats.Rats received intrarectal rebamipide treatment daily starting on day 7 and were sacrificed on day 14 after TNBS administration.The distal colon was removed to evaluate the various parameters of inflammation.Moreover,wound healing assays were used to determine the enhanced restitution of rat intestinal epithelial(RIE)cells treated with rebamipide.RESULTS:Intracolonic administration of rebamipide accelerated TNBSinduced ulcer healing.Increases in the wet weight of the colon after TNBS administration were significantly inhibited by rebamipide.The wound assay revealed that rebamipide enhanced the migration of RIE cells through phosphorylation of extracellular signalregulated kinase(ERK)and activation of Rho kinase.CONCLUSION:Rebamipide enema healed intestinal injury by enhancing restitution of RIE cells,via ERK activation.Rebamipide might be a novel therapeutic approach for inflammatory bowel disease.