Dextran Sulfate Sodium Colitis In Mice Research Articles

Experimental colitis in young Tg2576 mice accelerates the onset of an Alzheimer’s-like clinical phenotype

Systemic inflammation and neuroinflammation affect the natural course of the sporadic form of Alzheimer’s disease (AD), as supported by epidemiological and preclinical data, and several epidemiological studies indicate a higher prevalence of AD in patients with inflammatory bowel disease. In this study, we explored whether colitis induced by dextran sulfate sodium (DSS) in young, presymptomatic/preplaque mice worsens and/or anticipates age-dependent cognitive impairment in Tg2576, a widely used mouse model of AD. We demonstrated that DSS colitis induced in young Tg2576 mice anticipates the onset age of learning and memory deficit in the Morris water maze test. To explore potential mechanisms behind the acceleration of cognitive decline in Tg2576 mice by DSS colitis, we focused on gut microbiota, systemic inflammation and neuroinflammation markers. We observed a Firmicutes/Bacteroidetes ratio change in Tg2576 DSS animals comparable to that of elderly Tg2576 mice, suggesting accelerated microbiota aging in Tg2576 DSS mice, a change not observed in C57BL6 DSS mice. We also observed substantial differences between Tg2576 and WT mice in several inflammation and neuroinflammation-related parameters as early as 3 months of age, well before plaque deposition, a picture which evolved rapidly (between 3 and 5.5 months of age) in contrast to Tg2576 and WT littermates not treated with DSS. In detail, following induction of DSS colitis, WT and Tg2576 mice exhibited contrasting features in the expression level of inflammation-evoked astrocyte-associated genes in the hippocampus. No changes in microglial features occurred in the hippocampus between the experimental groups, whereas a reduced glial fibrillary acidic protein immunoreactivity was observed in Tg2576 vs. WT mice. This finding may reflect an atrophic, “loss-of-function” profile, further exacerbated by DSS where a decreased of GFAP mRNA expression level was detected. In conclusion, we suggest that as-yet unidentified peripheral mediators evoked by DSS colitis and involving the gut-brain axis emphasize an astrocyte “loss-of-function” profile present in young Tg2576 mice, leading to impaired synaptic morphological and functional integrity as a very early sign of AD.

Protective effect of α7 nicotinic acetylcholine receptor activation on experimental colitis and its mechanism

BackgroundInflammatory bowel disease (IBD) is a common chronic remitting disease with no satisfactory treatment. The aim of this study was to investigate the protective effect of α7 nicotinic acetylcholine receptor (α7nAChR), and to determine the underlying mechanism of its activity.MethodsThe expression and distribution of α7nAChR in the intestinal tissue of patients with ulcerative colitis and Crohn’s disease were analyzed. The effects of vagal excitation on murine experimental colitis were investigated. The colitis model was induced in C57BL/6 mice by the administration of 3% dextran sulfate sodium (DSS). The therapeutic group received treatment with the α7nAChR agonist PNU-282987 by intraperitoneal injection.ResultsOur results showed that there was significantly increased expression of α7nAChR in colitis and Crohn’s disease intestinal tissue, and its expression was mainly located in macrophages and neutrophils, which were extensively infiltrated in the disease status. Treatment with an α7nAChR agonist potently ameliorated the DSS-induced illness state, including weight loss, stool consistency, bleeding, colon shortening, and colon histological injury. α7nAChR agonist exerted anti-inflammatory effects in DSS colitis mice by suppressing the secretion of multiple types of proinflammatory factors, such as IL6, TNFα, and IL1β, and it also inhibited the colonic infiltration of inflammatory cells by blocking the DSS-induced overactivation of the NF-κB and MAPK signaling pathways. Mechanistically, activation of α7nAChR decreased the number of infiltrated M1 macrophages in the colitis intestine and inhibited the phagocytosis ability of macrophages, which were activated in response to LPS stimulation.ConclusionThus, an α7nAChR agonist ameliorated colonic pathology and inflammation in DSS-induced colitis mice by blocking the activation of inflammatory M1 macrophages.

The Protective Effect of Sulforaphane on Dextran Sulfate Sodium-Induced Colitis Depends on Gut Microbial and Nrf2-Related Mechanism.

Sulforaphane (SFN), an isothiocyanate present in cruciferous vegetables such as broccoli and brussels sprouts, has a variety of biological functions. This study was undertaken to assess the potential efficacy of SFN in ameliorating dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice and to elucidate the underlying mechanisms. UC was induced in mice with administration of 2% DSS in drinking water for 7 days. Male C57BL/6 mice were treated with Mesalazine (50 and 100 mg/kg body weight) and various doses of SFN (2.5, 5, 10, and 20 mg/kg body weight). In DSS colitis mice, the hallmarks of disease observed as shortened colon lengths, increased disease activity index (DAI) scores and pathological damage, higher proinflammatory cytokines and decreased expression of tight junction proteins, were alleviated by SFN treatment. SFN also partially restored the perturbed gut microbiota composition and increased production of volatile fatty acids (especially caproic acid) induced by DSS administration. The heatmap correlation analysis indicated that Lactobacillus johnsonii, Bacteroides acidifaciens, unclassified Rikenellaceae RC9, and unclassified Bacteroides were significantly correlated with disease severity. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), Signal Transducer and Activator of Transcription 3 (STAT3), and Phase II enzyme UDP-glucuronosyltransferase (UGT) were involved in the protective effect of SFN against DSS-induced colitis. This study's findings suggest that SFN may serve as a therapeutic agent protecting against UC.

NLRP3 Inflammasome Inhibitor OLT1177 Suppresses Onset of Inflammation in Mice with Dextran Sulfate Sodium-Induced Colitis.

NLRP3 inflammasomes have been reported to have a key role in the initiation and perpetuation of inflammatory bowel diseases (IBD). Here we investigated the effects of OLT1177, a selective inhibitor of NLRP3 inflammasomes, in mice with dextran sulfate sodium (DSS)-induced colitis. C57BL/6J mice were given drinking water containing 3% DSS for 5days. OLT1177 was administered for 5days during the induction phase (simultaneously with DSS treatment) or the recovery phase (after the DSS treatment ended). The body weight and disease activity index were monitored daily. The mice were sacrificed 10days after the start of the experiment, and the severity of inflammation in the colon was determined based on histological and biochemical analyses. Administration of OLT1177 during the induction phase effectively suppressed DSS colitis in terms of weight loss, disease activity index, histological score, and expression of inflammatory cytokines compared to the DSS group. In contrast, OLT1177 administration during the recovery phase did not significantly affect the colitis disease course or the results of histological analyses. OLT1177 was effective in preventing the onset of DSS colitis in mice. These results could guide the use of OLT1177 as a therapy for human IBD.

Pinocembrin alleviates ulcerative colitis in mice via regulating gut microbiota, suppressing TLR4/MD2/NF-κB pathway and promoting intestinal barrier.

Pinocembrin, a plant-derived flavonoid, has a variety of pharmacological activities, including anti-infection, anti-cancer, anti-inflammation, cardiovascular protection, etc. However, the mechanism of pinocembrin on the anti-colitis efficacy remains elusive and needs further investigation. Here, we reported that pinocembrin eased the severity of dextran sulfate sodium (DSS)-induced colitis in mice by suppressing the abnormal activation of toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signal pathway in vivo. In addition, the gut microbiota was disordered in DSS colitis mice, which was associated with a significant decrease in microbiota diversity and a great shift in bacteria profiles; however, pinocembrin treatment improved the imbalance of gut microbiota and made it similar to that in normal mice. On the other hand, in vitro, pinocembrin down-regulated the TLR4/NF-κB signaling cascades in lipopolysaccharide (LPS)-stimulated macrophages. At the upstream level, pinocembrin competitively inhibited the binding of LPS to myeloid differentiation protein 2 (MD2), thereby blocking the formation of receptor multimer TLR4/MD2·LPS. Furthermore, pinocembrin dose-dependently promoted the expression of tight junction proteins (ZO-1, Claudin-1, Occludin and JAM-A) in Caco-2 cells. In conclusion, our work presented evidence that pinocembrin attenuated DSS-induced colitis in mouse, at least in part, via regulating intestinal microbiota, inhibiting the over-activation of TLR4/MD2/NF-κB signaling pathway, and improving the barriers of intestine.

Antiplatelet agents'-ticagrelol and eptifibatide-safety in experimental colitis in mice.

To evaluate the side effects of two antiplatelet agents - ticagrelor and eptifibatide - in mice with experimentally-induced inflammatory bowel disease. This study was designed as a controlled, animal, drug safety investigation. C57Bl/6 mice were used to establish the ulcerative colitis model by exposure to dextran sulfate sodium (DSS), and divided into three experimental groups: eptifibatide-treated (150 µg/day intraperitoneally; n = 10), ticagrelol-treated (1 mg/day via gastric tube; n = 10), and DSS-control (plain drinking water; n = 10). An unmodeled non-DSS group served as the experimental control. Complete blood count was taken for all mice at baseline (day 0, treatment initiation) and after four days of treatment. On day 4, all animals were sacrificed for autopsy. The primary outcome measure was bleeding, and the secondary outcomes were change in platelet count, hemoglobin level, and hematocrit level. Neither ticagrelor nor eptifibatide treatment produced a significant effect on DSS colitis mice for the safety parameters measured. Platelet count and hemoglobin and hematocrit levels were statistically similar between the three DSS groups and the non-DSS control group (P > 0.05). Autopsy found no evidence of recent bleeding in liver, spleen, central nervous system or serous cavities. The antiplatelet agents ticagrelor and eptifibatide were safe in DSS colitis mice, suggesting their potential in humans suffering from ulcerative colitis, and supporting future safety studies.

The effect of selected Lactobacillus strains on dextran sulfate sodium-induced mouse colitis model.

Inflammatory bowel disease (IBD) comprises two major illnesses: Crohn's disease (CD) and ulcerative colitis (UC). Dextran sulfate sodium (DSS) mouse colitis model has been used in understanding the mechanism of IBD. This study was conducted to examine selected Lactobacillus spp. as potential IBD treatment in the DSS-induced animal model. Balb/c mice were used and colitis was induced by adding 5% dextran sodium sulfate into the drinking water for 8 days. Colon length, disease activity index (DAI) and histological analysis were measured as markers of inflammation in DSS colitis mice. The majority of the Lactobacillus species significantly prevented the shortening of the colon length compared with the DSS group. The DAI scores of mice were significantly reduced following usage of four Lactobacillus strains included: Lactobacillus plantarum 03 and 06, Lactobacillus brevis 02 and Lactobacillus rhamnosus 01. The histological analysis exhibited that oral administration of Lactobacillus strains had therapeutic effects on mice colitis. L. plantarum and L. brevis showed better therapeutic effect against DSS-induced acute colitis mice. The probiotic activities of these three isolates indicated that the probiotic effects were strain specific and none of these useful bacteria could exhibit all of the valued probiotic properties simultaneously.

Obacunone Protects Against Ulcerative Colitis in Mice by Modulating Gut Microbiota, Attenuating TLR4/NF-κB Signaling Cascades, and Improving Disrupted Epithelial Barriers.

Obacunone, a natural limonoid compound abundantly distributed in citrus fruits, possesses various biological properties, such as antitumor, antioxidant, and antiviral activities. Recent studies suggested an anti-inflammatory activity of obacunone in vitro, but its efficacy on intestinal inflammation remains unknown. This study was designed to evaluate the effects and mechanisms of obacunone in ameliorating intestinal inflammation in a mouse model of ulcerative colitis (UC). We found that obacunone efficiently alleviated the severity of dextran sulfate sodium (DSS)-induced mouse UC by modulating the abnormal composition of the gut microbiota and attenuating the excessive activation of toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling. The intestinal epithelial barrier was disrupted in DSS colitis mice, which was associated with activation of inflammatory signaling cascades. However, obacunone promoted the expression of tight junction proteins (TJP1 and occludin) and repressed the activation of inflammatory signaling cascades. In summary, our findings demonstrated that obacunone attenuated the symptoms of experimental UC in mice through modulation of the gut microbiota, attenuation of TLR4/NF-κB signaling cascades, and restoration of intestinal epithelial barrier integrity.

Effects of Human Adipose Tissue-Derived and Umbilical Cord Tissue-Derived Mesenchymal Stem Cells in a Dextran Sulfate Sodium-Induced Mouse Model.

Mesenchymal stem cells (MSCs) can be acquired from medical waste. MSCs are easily expanded and have multiple functions, including anti-inflammatory effects. We evaluated the effects of human adipose tissue-derived MSCs (AD-MSCs) and umbilical cord tissue-derived MSCs (UC-MSCs) in a dextran sulfate sodium (DSS)-induced mouse model. Human AD-MSCs and UC-MSCs (1 × 106 cells) were injected intravenously into a 7-day DSS-induced colitis model. The therapeutic effects of cell origin, injection timing, and supernatants obtained from MSC cultures were evaluated. We also analyzed messenger RNA (mRNA) expression in MSCs, tissues, and intestinal flora. AD-MSCs and UC-MSCs were found to show strong anti-inflammatory effects when injected on day 3 in a mouse model. On day 11, the mRNA levels of inflammatory factors in colon tissues were significantly decreased after injection of MSCs on day 3. Supernatants from MSCs culture decreased mRNA levels of tumor necrosis factor (Tnf)-α, but had reduced therapeutic effects compared with MSC cell injection. RNA sequencing using colon tissues obtained the day after cell injection revealed changes in the TNF-α/nuclear factor-κB and T cell receptor signaling pathways. Additional analyses showed that several factors, including chromosome 10 open reading frame 54, stanniocalcin-1, and TNF receptor superfamily member 11b were increased in MSCs after adding serum from DSS colitis mice. Furthermore, both AD-MSCs and UC-MSCs maintained the balance of intestinal flora. In conclusion, AD-MSCs and UC-MSCs showed therapeutic effects against inflammation after early cell injection while maintaining the intestinal flora. Although supernatants showed therapeutic effects, cell injection was more effective against inflammation.

Malvidin 3-Glucoside Modulated Gut Microbial Dysbiosis and Global Metabolome Disrupted in a Murine Colitis Model Induced by Dextran Sulfate Sodium.

This study aims to elucidate the mechanisms of the anthocyanin malvidin 3-glucoside (MV) in alleviating gut dysbiosis using a murine colitis model induced by dextran sulfate sodium (DSS). The effect of MV on the structure and function of the colon microbiome and microbial metabolism is evaluated using 16S rRNA gene sequencing, global metabolomics, and a network algorithm based on the random-matrix theory. MV ingestion improved histopathological scores and increased IL10 expression in the colon mucosa of colitis mice. While DSS has a profound effect on the gut microbiome and significantly decreases both microbial richness and evenness, MV further reduces evenness but promotes microbial interactions and restores the Firmicutes/Bacteroidetes ratio repressed by DSS. Moreover, MV reduces the abundance of pathogenic bacteria, such as Ruminococcus gnavus, in colitis mice and has a strong modulatory effect on microbial co-occurrence patterns and gut metabolites. In addition, MV reverses several key inflammatory mediators, including sphingolipid metabolites, from elevated levels in DSS colitis mice. As a bioactive ingredient, MV exerts its effect on the gut microbiome in a mechanism that differs from the whole blueberry. MV ingestion ameliorates intestinal inflammation by modulating colon epithelium integrity, gut microbiome, and key inflammatory mediators.

Vasoactive Intestinal Peptide Nanomedicine for the Management of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic relapsing disorder of the intestine, with increasing incidence worldwide. At present, the management of IBD is an unmet medical need due to the ineffectiveness of currently available drugs in treating all patients, and there is strong demand for novel therapeutics. In this regard, vasoactive intestinal peptide, a potent anti-inflammatory endogenous hormone, has shown promise in managing multiple immune disorders in animal models. However, when administered in the free form, VIP undergoes rapid degradation in vivo, and with continuous infusion, it causes severe dose limiting side effects. To overcome these barriers, we have developed a superior mode to deliver VIP in its native form, using sterically stabilized micelles (VIP-SSM). Our previous studies demonstrated that, VIP, when administered in SSM, prevented joint damage and inflammation in a mouse model of rheumatoid arthritis at a significantly lower dose than the free peptide, completely abrogating the serious side effect of hypotension associated with VIP. In the current study, we demonstrate the therapeutic benefit of VIP-SSM over free peptide in reversing severe colitis associated with IBD. First, we conducted preliminary studies with dextran sulfate sodium (DSS) induced colitis in mice, to determine the effectiveness of VIP administered on alternate days in reducing disease severity. Thereafter, a single intra peritoneal injection of VIP-SSM or the free peptide was used to determine its therapeutic effect on the reversal of colitis and associated diarrhea. The results demonstrated that when administered on alternate days, both VIP-SSM and VIP were capable of alleviating DSS colitis in mice. However, when administered as a single dose, in a therapeutic setting, VIP-SSM showed superior benefits compared to the free peptide in ameliorating colitis phenotype. Namely, the loss of solid fecal pellets and increased fluid accumulation in colon resulting from DSS insult was abrogated in VIP-SSM treated mice and not with free VIP. Furthermore, reduced protein and mRNA levels of the major chloride bicarbonate exchanger, down regulated in adenoma (DRA), seen with DSS was reversed with VIP-SSM, but not with the free peptide. Similarly, VIP-SSM treatment significantly reduced the elevated mRNA levels of pro-inflammatory cytokines and showed significant histologic recovery when compared to mice treated with free VIP. Therefore, these results demonstrated that as a single dose, the anti-inflammatory and antidiarrheal effects of VIP can be achieved effectively when administered as a nanomedicine. Therefore, we propose VIP-SSM to be developed as a potential therapeutic tool for treating ulcerative colitis, a type of IBD.

Low-dose penicillin exposure in early life decreases Th17 and the susceptibility to DSS colitis in mice through gut microbiota modification

Antibiotic exposure in early life can lead to a significant change of the gut microbiota and may contribute to later onset of inflammatory bowel disease (IBD). However, the relationship between early-life antibiotic treatment and IBD is ambiguous, according to contradicting results of epidemiologic studies. In the present study, we demonstrated that low-dose penicillin pre-treatment had a unique protective effect against mouse colitis induced by dextran sodium sulfate (DSS). Low-dose penicillin also suppressed the expression of pro-inflammatory cytokine IL-17 in various intestinal tissues, and decreased the amount of Th17 cells in small-intestine lamina propria. Neither metronidazole nor enrofloxacin had a similar effect. We further confirmed that low-dose penicillin could cause specific changes of the gut microbiota, especially the eradication of segmented filamentous bacteria (SFB). Mice without SFB inoculation showed no disparity when treated with penicillin or water. Taken together, the results showed that low-dose penicillin can achieve a highly specific manipulation of sensitive bacteria and interfere with development of intestinal immune system in early life. The study may further indicate the possibility of achieving a favorable immune state among a certain group of patients with IBD, or other autoimmune diseases, by fine-tuning the gut microbiota.

Caffeic acid ameliorates colitis in association with increased Akkermansia population in the gut microbiota of mice.

Emerging evidence shows that dietary agents and phytochemicals contribute to the prevention and treatment of ulcerative colitis (UC). We first reported the effects of dietary caffeic acid (CaA) on murine experimental colitis and on fecal microbiota. Colitis was induced in C57BL/6 mice by administration of 2.5% dextran sulfate sodium (DSS). Mice were fed a control diet or diet with CaA (1 mM). Our results showed that dietary CaA exerted anti-inflammatory effects in DSS colitis mice. Moreover, CaA could significantly suppress the secretion of IL-6, TNFα, and IFNγ and the colonic infiltration of CD3+ T cells, CD177+ neutrophils and F4/80+ macrophages via inhibition of the activation of NF-κB signaling pathway. Analysis of fecal microbiota showed that CaA could restore the reduction of richness and inhibit the increase of the ratio of Firmicute to Bacteroidetes in DSS colitis mice. And CaA could dramatically increase the proportion of the mucin-degrading bacterium Akkermansia in DSS colitis mice. Thus, CaA could ameliorate colonic pathology and inflammation in DSS colitis mice, and it might be associated with a proportional increase in Akkermansia.

Berberine ameliorates chronic relapsing dextran sulfate sodium-induced colitis in C57BL/6 mice by suppressing Th17 responses

Ulcerative colitis (UC) is an increasingly common condition particularly in developed countries. The lack of satisfactory treatment has fueled the search for alternative therapeutic strategies. In recent studies, berberine, a plant alkaloid with a long history of medicinal use in Chinese medicine, has shown beneficial effects against animal models of acute UC. However, UC usually presents as a chronic condition with frequent relapse in patients. How berberine will act on chronic UC remains unclear. In the present study, we adopted dextran sulfate sodium (DSS)-induced chronic relapsing colitis model to assess the ameliorating activity of berberine. Colitis was induced by two cycles of 2.0% DSS for five days followed by 14days of drinking water plus a third cycle consisting of DSS only for five days. The colitis mice were orally administered 20mg/kg berberine from day 13 onward for 30days and monitored daily. The body weight, stool consistency, and stool bleeding were recorded for determination of the disease activity index (DAI). At the end of treatment, animals were sacrificed and samples were collected and subjected to histological, RT-qPCR, Western blot, and LC–MS analyses. Lymphocytes were isolated from spleens and mesenteric lymph nodes (MLN) and cultured for flow cytometry analysis of IL-17 secretion from CD4+ cells and the Th17 cell differentiation. Results showed that berberine significantly ameliorated the DAI, colon shortening, colon tissue injury, and reduction of colonic expression of tight junction (TJ) protein ZO-1 and occludin of colitis mice. Notably, berberine treatment pronouncedly reduced DSS-upregulated Th17-related cytokine (IL-17 and ROR-γt) mRNAs in the colon. Furthermore, the mRNA expression of IL-6 and IL-23, and the phosphorylation of STAT3 in colon tissues from DSS-treated mice were pronouncedly inhibited by berberine. Moreover, the up-regulation of IL-17 secretion from CD4+ cells of spleens and MLNs caused by DSS were significantly reversed by berberine treatment. Furthermore, Th17 cell differentiation from naive CD4+ cells isolated from above DSS colitis mice were suppressed by berberine in a concentration-dependent manner. In summary, we demonstrated for the first time that berberine reduced the severity of chronic relapsing DSS-induced colitis by suppressing Th17 responses. The demonstration of activity in this mouse model supports the possibility of clinical efficacy of berberine in treating chronic UC.

Galectin-3 Modulates Experimental Colitis

Background: We recently identified galectin-3 (gal-3) as a new and strong fibroblast activator produced by colonic epithelial cells. Very little is known about the influence of gal-3 in inflammatory bowel disease. We, therefore, investigated the impact of gal-3 on dextran sodium sulfate (DSS)-induced colitis in a mouse model. Methods: Colonic lamina propria fibroblasts of healthy controls were used for co-incubation studies of gal-3 with gal-1, TGF-β1, IFNγ, IL-4 and IL-10. Acute and chronic DSS colitis was induced by 3% DSS in drinking water in female Balb/c mice weighing 20-22 g. Recombinant gal-3 was expressed by the pET vector system and used for a 5-day treatment in different concentrations intraperitoneally. The distal third of the colon was used for histologic analysis. Colonic cytokine expression was determined by quantitative RT-PCR. Results: In vitro, gal-3 induced IL-8 secretion was significantly reduced by co-incubation with IL-10 (5 ng/ml) and IL-4 (10 ng/ml). Acute DSS-induced colitis was ameliorated by gal-3 treatment as indicated by increased colonic length and reduced weight loss compared to that of controls. In acute and chronic colitis, gal-3 treatment resulted in a significant suppression of colonic IL-6. Conclusion: Gal-3 significantly reduces inflammation in acute and chronic DSS colitis in mice indicating a potential role in intestinal inflammation.

Tu1397 Somatostatin Regulates NHE8 Protein Expression via the MAPK -ERK1/2 Pathway in Colitis Mice

Background and aim:diarrhea is a common disease in gastroenterology which is caused by various affects such as intestinal infection, non-infectious inflammation, tumors and so on. The imbalance of fluid/sodium absorption and secretion is considered playing a crucial role in diarrhea. Sodium, as an important electrolyte, involves three mechanisms to transport. Of note, sodium/hydrogen exchanger (NHE) may occupy a crucial position in modulating intestinal water and sodium absorption. Previous study had shown that somatostatin (SST) could stimulate NHE8 expression in physiological intestine. To determine the benefical effect of SST on NHE8 protein expression in colitis mice and its mechanisms, experimental colitis was induced in mice utilizing dextran sulfate sodium (DSS), models of Caco-2 cells intervened by TNF-α were also established to further explore the mechanism of somatostatin modulating NHE8 expression. Methods: To induce diarrhea via intestinal inflammation, mice were fed with 3% Dextran sulfate sodium (DSS) water for seven days. On the eighth day, treatment groups were administrated with octreotide at dose of 50 μg/ kg body weight three times a day for three days. On the eleventh day, mice were euthanized and colonic tissues were collected. Diarrheal symptoms were assessed every other day. Diarrheal score was recorded based on fecal shape, color and hardness. For the TNF-α study, Caco-2 cells were incubated with TNF-α for 18 hours before adding somatostatin. Cells were exposed to somatostatin for 1 hour before harvest. To further explore the mechanism of somatostatin modulating NHE8 expression, Caco-2 cells were incubated with TNF-α for 18 hours. Subsequently, Caco-2 cells pretreated with MAPKK inhibitor (PD98059) were administratedwith SST for 1 hour before harvest.Results: For DSS colitis mice, the expression of somatostatin in colon were decreased in DSS colitis mice compared with the control mice. Moreover, SST could not only ameliorate diarrhea in inflammatory colitis (diarrheal score: 1.7 ± 0.78 vs. 3.6 ± 0.16, n = 3, P<0.05) but also stimulate NHE8 expression in proximal and distal colon compared with DSS colitis mice (proximal colon: 0.61±0.08 vs. 0.31±0.04, n=3, P<0.05; distal colon: 0.74±0.1 vs. 0.36±0.06, n=3, P<0.05). For TNF-α intervened Caco-2 cells, SST could stimulate NHE8 expression compared with TNF-α intervened cells (0.5 ± 0.04 vs. 0.25 ± 0.01; n=3, P<0.05). Furthermore, compared with TNF-α intervened cells, SST could decline the phosphorylation of ERK1/2 (P<0.05). conclusions :In conclusion, the present study suggested that somatostatin could up-regulate the expression of NHE8 protein in both DSS colitis mice and TNF-α intervened Caco-2 cells by blocking the activation of the MAPK-ERK1/2 pathway.

Tu1398 Direct and Specific Inhibition of Constitutive Nitric Oxide Mediated Regulation of Brush Border Membrane NHE3 and SGLT1 in Intestinal Epithelial Cells

Background and aim:diarrhea is a common disease in gastroenterology which is caused by various affects such as intestinal infection, non-infectious inflammation, tumors and so on. The imbalance of fluid/sodium absorption and secretion is considered playing a crucial role in diarrhea. Sodium, as an important electrolyte, involves three mechanisms to transport. Of note, sodium/hydrogen exchanger (NHE) may occupy a crucial position in modulating intestinal water and sodium absorption. Previous study had shown that somatostatin (SST) could stimulate NHE8 expression in physiological intestine. To determine the benefical effect of SST on NHE8 protein expression in colitis mice and its mechanisms, experimental colitis was induced in mice utilizing dextran sulfate sodium (DSS), models of Caco-2 cells intervened by TNF-α were also established to further explore the mechanism of somatostatin modulating NHE8 expression. Methods: To induce diarrhea via intestinal inflammation, mice were fed with 3% Dextran sulfate sodium (DSS) water for seven days. On the eighth day, treatment groups were administrated with octreotide at dose of 50 μg/ kg body weight three times a day for three days. On the eleventh day, mice were euthanized and colonic tissues were collected. Diarrheal symptoms were assessed every other day. Diarrheal score was recorded based on fecal shape, color and hardness. For the TNF-α study, Caco-2 cells were incubated with TNF-α for 18 hours before adding somatostatin. Cells were exposed to somatostatin for 1 hour before harvest. To further explore the mechanism of somatostatin modulating NHE8 expression, Caco-2 cells were incubated with TNF-α for 18 hours. Subsequently, Caco-2 cells pretreated with MAPKK inhibitor (PD98059) were administratedwith SST for 1 hour before harvest.Results: For DSS colitis mice, the expression of somatostatin in colon were decreased in DSS colitis mice compared with the control mice. Moreover, SST could not only ameliorate diarrhea in inflammatory colitis (diarrheal score: 1.7 ± 0.78 vs. 3.6 ± 0.16, n = 3, P<0.05) but also stimulate NHE8 expression in proximal and distal colon compared with DSS colitis mice (proximal colon: 0.61±0.08 vs. 0.31±0.04, n=3, P<0.05; distal colon: 0.74±0.1 vs. 0.36±0.06, n=3, P<0.05). For TNF-α intervened Caco-2 cells, SST could stimulate NHE8 expression compared with TNF-α intervened cells (0.5 ± 0.04 vs. 0.25 ± 0.01; n=3, P<0.05). Furthermore, compared with TNF-α intervened cells, SST could decline the phosphorylation of ERK1/2 (P<0.05). conclusions :In conclusion, the present study suggested that somatostatin could up-regulate the expression of NHE8 protein in both DSS colitis mice and TNF-α intervened Caco-2 cells by blocking the activation of the MAPK-ERK1/2 pathway.

Preventative oral methylthioadenosine is anti-inflammatory and reduces DSS-induced colitis in mice

Methylthioadenosine (MTA) is a precursor of the methionine salvage pathway and has been shown to have anti-inflammatory properties in various models of acute and chronic inflammation. However, the anti-inflammatory properties of MTA in models of intestinal inflammation are not defined. We hypothesized that orally administered MTA would be bioavailable and reduce morbidity associated with experimental colitis. We examined clinical, histological, and molecular markers of disease in mice provided oral MTA before (preventative) or after (therapy) the induction of colitis with 3% dextran sulfate sodium (DSS). We found a reduction in disease activity, weight loss, myeloperoxidase activity, and histological damage in mice given preventative MTA compared with DSS alone. We also found that equivalent supplementation with methionine could not reproduce the anti-inflammatory effects of MTA, and that MTA had no detectable adverse effects in control or DSS mice. Expression microarray analysis of colonic tissue showed several dominant pathways related to inflammatory cytokines/chemokines and extracellular matrix remodeling were upregulation by DSS and suppressed in MTA-supplemented mice. MTA is rapidly absorbed in the gastrointestinal tract and disseminated throughout the body, based on a time course analysis of an oral bolus of MTA. This effect is transient, with MTA levels falling to near baseline within 90 min in most organs. Moreover, MTA did not lead to increased blood or tissue methionine levels, suggesting that its effects are specific. However, MTA provided limited therapeutic benefit when administered after the onset of colitis. Our results show that oral MTA supplementation is a safe and effective strategy to prevent inflammation and tissue injury associated with DSS colitis in mice. Additional studies in chronic inflammatory models are necessary to determine if MTA is a safe and beneficial option for the maintenance of remission in human inflammatory bowel disease.

Mitochondrial electron transport chain complex dysfunction in the colonic mucosa in ulcerative colitis

Ulcerative colitis (UC) is characterized by an energy deficiency state of the colonic epithelium. This study evaluated mitochondrial electron transport chain (ETC) complex activity in normal and disease mucosa in patients with UC. Alterations in ETC complexes were also investigated in experimental colitis in mice. Biopsies were obtained from macroscopically normal and diseased colonic mucosa of 43 patients with UC and 35 controls undergoing screening colonoscopy and ETC complex activity was assayed biochemically. ETC complex activities were also assayed in colonic epithelial cells isolated from Swiss albino mice with dextran sodium sulfate (DSS)-induced colitis at various stages of induction of colitis. Mucosal nitrite levels and protein carbonyl content were determined. The activity of Complex II was significantly decreased in colonic biopsies from UC patients compared with controls, while activities of other mitochondrial complex were normal. Complex II activity was equally decreased in diseased and normal mucosa in UC; the degree of reduction did not correlate with clinical, endoscopic, or histological grading of disease activity. In DSS-fed mice, a reduction in activity of Complex IV and Complex II was observed. Activity of other complex was not affected. Administration of aminoguanidine, an inducible nitric oxide synthase (iNOS) inhibitor, attenuated all parameters of colitis as well as the reductions in Complex IV and Complex II activity. Reduction in Complex II activity appears to be a specific change in UC, present in quiescent and active disease. Mitochondrial complex dysfunction occurs in DSS colitis in mice and appears to be mediated by nitric oxide.

Salvinorin A has antiinflammatory and antinociceptive effects in experimental models of colitis in mice mediated by KOR and CB1 receptors*

Salvinorin A (SA) has a potent inhibitory action on mouse gastrointestinal (GI) motility and ion transport, mediated primarily by kappa-opioid receptors (KOR). The aim of the present study was to characterize possible antiinflammatory and antinociceptive effects of SA in the GI tract of mice. Colonic damage scores and myeloperoxidase activity were determined after intraperitoneal (i.p.), intracolonic (i.c.), and oral (p.o.) administration of SA using the trinitrobenzene sulfonic acid (TNBS) and dextran sodium sulfate (DSS) models of colitis in mice. Additionally, KOR, cannabinoid (CB)1, and CB2 western blot analysis of colon samples was performed. The antinociceptive effect of SA was examined based on the number of behavioral responses to i.c. instillation of mustard oil (MO). The i.p. (3 mg/kg, twice daily) and p.o. (10 mg/kg, twice daily) administration of SA significantly attenuated TNBS and DSS colitis in mice. The effect of SA was blocked by KOR antagonist nor-binaltorphimine (10 mg/kg, i.p.). Western blot analysis showed no influence of SA on KOR, CB1, or CB2 levels. SA (3 mg/kg, i.p. and 10 mg/kg, i.c.) significantly decreased the number of pain responses after i.c. instillation of MO in the vehicle- and TNBS-treated mice. The antinociceptive action of SA was blocked by KOR and CB1 antagonists. The analgesic effect of i.c. SA was more potent in TNBS-treated mice compared to controls. Our results suggest that the drugs based on the structure of SA have the potential to become valuable antiinflammatory or analgesic therapeutics for the treatment of GI diseases.