Effects Of Dextran Sulfate Sodium Research Articles

Novel probiotic yeast from Miso promotes regulatory dendritic cell IL-10 production and attenuates DSS-induced colitis in mice.

Yeasts are a type of fungi thought to have probiotic functions. In this study, we isolated a novel probiotic yeast (Zygosaccharomyces sapae strain I-6) from Miso (a traditional Japanese fermented food). We examined its effects on phenotypic changes in intestinal dendritic cells (DCs), and evaluated its anti-inflammatory effects in dextran sulfate sodium (DSS)-induced colitis. A single colony was selected from homogenized Miso, based on its ability to produce interleukin (IL)-10 in CD11c+ bone marrow DCs (BMDCs) in vitro. The anti-inflammatory effects of strain I-6 on CD11c+ BMDCs and CD11c+ CD103+ DCs were analyzed in mouse mesenteric lymph nodes in vitro and in a DSS mouse model. The IL-10 concentrations in the co-culture BMDC supernatants treated with I-6 were dramatically higher than in those treated with Saccharomyces cerevisiae (Sc). IL-10 production is mediated by both TLR2 and Dectin-1. β-Glucan extracted from I-6 also induced higher levels of IL-10 production in BMDCs than β-glucan from Sc. The number of mesenteric lymph node CD11c+ CD103+ DCs was significantly increased by I-6 administration, compared with Sc administration. Strain I-6 showed strong anti-inflammatory effects on DSS-induced colitis compared to Sc. Moreover, the adoptive transfer of I-6-treated BMDCs showed anti-inflammatory effects on DSS-induced colitis in mice without oral administration of I-6 cells. Strain I-6 induced phenotypic changes in intestinal CD11c+ DCs characterized by high IL-10 production and exerted strong anti-inflammatory effects on DSS-induced colitis. Traditional Japanese fermented foods may be a valuable source of probiotic yeasts for effective IBD therapy and treatment.

Human Relevance of Preclinical Studies on the Skeletal Impact of Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis.

Inflammatory bowel disease (IBD) is a relapsing chronic idiopathic inflammatory condition. The increased risks of fractures in the spine and decreased BMD at all weight-bearing skeletal sites have been reported in IBD patients. The understanding of the mechanisms of IBD-induced bone loss is far from complete. Appropriate animal models are a prerequisite for studying IBD-induced bone loss, which prompted us to undertake quantitative meta-analyses by pooling data from the available IBD models that assessed various bone parameters. Sufficient data for meta-analysis are obtained from chemically- but not genetically induced models. Among the chemically induced models, only the effects of dextran sulfate sodium (DSS) and 2,4,6-trinitrobenzene sulfonic acid (TNBS) on bone parameters have been reported. Meta-analysis showed that both DSS (Hedge's g = 2.124, p = 0.001) and TNBS (Hedge's g = 6.292, p = 0.000) increased inflammatory disease severity. In pooled analysis, bone volumes in femur (Hedge's g = -3.42, p = 0.000) and tibia (Hedge's g = -2.49, p = 0.000) showed significant losses upon DSS administration. Similarly, bone formation rate was significantly reduced upon IBD induction (Hedge's g = -3.495, p = 0.006). Besides, cortical thickness was reduced and trabecular microstructure deteriorated by IBD induction. Insufficient data precluded us from determining the effect of IBD on bone strength and calciotropic hormones, as well as the impact of proinflammatory cytokines on bone turnover. This meta-analysis showed that IBD induction in rodents causes significant bone loss. Impaired osteoblast function appears to be the cause of this impact.

Schisandrin B and Alantolactone ameliorates experimental autoimmune encephalomyelitis in mice

Abstract Schisandrin B (Sch-B) and Alantolactone (ALT) are two distinct molecules each of which could be extracted from herbs Schisandra chinensis and Inula helenium, respectively, commonly used in traditional Chinese medicine. Previous studies have revealed that both molecules impact STAT3, Nrf2 and Smad-mediated signaling pathways, and that Sch-B has protective effects in dextran sulfate sodium (DSS)-induced colitis models. However, besides a single paper studying Sch-B’s impact on murine Th17/Treg balance, the effects of Sch-B and ALT on human and murine Th17/Treg cells’ ontogeny and functions have not been investigated. In this study, we demonstrated that every other day administration of Sch-B or ALT during induction phase of myelin oligodendrocyte (MOG)35–55-induced experimental autoimmune encephalomyelitis (EAE) dramatically and significantly reduced EAE disease scores, demyelination, disease incidence, and infiltration of leukocytes into central nervous system, particularly IFN-γ+, IL-17+, GM-CSF+ T cells in C57BL/6 mice. Protection from disease correlated with elevated Treg and IL-10 levels. To our knowledge this is the first report demonstrating a prophylactic benefit for Sch B and ALT in a Multiple Sclerosis model and our results warrant further studies as to the use of both molecules after disease onset and mechanism of action.

Galactooligosaccharides protects against DSS-induced murine colitis through regulating intestinal flora and inhibiting NF-κB pathway

Background/aimsPrevious studies have demonstrated that Galactooligosaccharides (GOS), known as “bifidus factor”, has anti-inflammatory effects. Colitis, a kind of colonic inflammatory damage could be induced by different chemicals. The pathogenesis and mechanism of colitis remains unclear, and may be related to intestinal microflora, genetic susceptibility or immune factors. The aim is to explore the effects of GOS on intestinal flora and its anti-inflammatory effects in Dextran Sulfate Sodium (DSS) induced murine colitis and extrapolate the underlying mechanism. Main methodsInitially, 5% DSS was used to induced colitis by free access to drinking water for 5–7 days. Then the mice were treated with GOS 1 day after DSS treatment. Colon samples were evaluated grossly using a microscope. The percentage of Treg and Th17 cells was analyzed by flow cytometry. The levels of cytokines secretion and mRNA expression were detected by ELISA and real-time PCR. The level of protein was detected by western blot. Key findingsGOS attenuated DSS induced body weight loss and also reduced the increase in disease index caused by DSS. GOS ameliorated DSS induced colonic histological damage. The protective effect of GOS on DSS induced colitis may be partly attributed to intestinal flora regulation and Th17/Treg imbalance. Furthermore, GOS markedly decreased cytokines (IL-6, IL-18, IL-13 and IL-33) secretion and mRNA expression in colon tissues, through inhibiting activation of NF-κB pathways. SignificanceGOS could prevent the DSS induced colitis through intestinal flora regulation and reduce the secretion of inflammation related cytokines relying on the NF-κB signaling pathway.

Purification and characterization of turanose, a sucrose isomer and its anti-inflammatory effects in dextran sulfate sodium (DSS)-induced colitis model

Abstract The prevalence of inflammatory bowel disease (IBD) is increasing worldwide, and the key risk factor is high sugar diet. The objective of this study was to investigate anti-inflammatory effects of turanose on IBD in a dextran sulfate sodium (DSS)-induced colitis mouse model. An amylosucrase from Neisseria sicca (NsiAS) was newly identified and successfully expressed. This enzyme exhibited optimal activity at 45 °C and pH 8.5. By utilizing this recombinant enzyme expressed in the E. coli host, turanose yield maximally reached 47% from 2.0 M sucrose. Colitis was induced with two 5-d cycles of 2.5% DSS in drinking water with a 10-d inter-cycle interval. Mice were fed AIN93G diet with 25% and 50% turanose replacement. Improved disease activity index scores, colon length, histopathological features, and myeloperoxidase activity were observed in the turanose supplemented group. Meanwhile, decreases in micro RNA (miR)-21 expression, histone acetylation, expression of pro-inflammatory cytokines, and phosphorylated ERK and STAT3 were observed in colon tissues. Notably, miR-21 and histone acetylation levels were found to positively correlated with expression of tumor necrosis factor α. In conclusion, turanose can attenuate colitis via regulatory effects on miRNA-21 expression and histone acetylation-related proinflammatory mediators. These findings also support further exploration of turanose as a potential therapeutic sugar substitute for patients with IBD.

Promising anti-diabetic effect of dextran sulfate sodium: Is it its clinical come back?

Clinical studies showed that dextran sulfate sodium (DSS) alleviates stroke, diabetic retinopathy and hypercholesterolemia, yet its mechanism of action was unrevealed. This study show that DSS reduces hyperglycemia, plasma insulin and enhances glucose utilization by attenuating ROS production, suggesting a novel therapeutic use of DSS in diabetes and its complication.

The flotation separation of scheelite from calcite and fluorite using dextran sulfate sodium as depressant

This paper introduced dextran sulfate sodium, a medical intermediate rich in sulfate group, as a potential depressant for calcite and fluorite in scheelite flotation. The flotation behaviors of scheelite, calcite and fluorite under different pulp pH with dextran sulfate sodium acting as depressant and sodium oleate acting as collector were studied through micro-flotation tests. The results showed that when sodium oleate was used alone, the three minerals floated well and were difficult to separate. Dextran sulfate sodium exhibited a selective depressant effect on calcite and fluorite flotation when it was added before sodium oleate. Using dextran sulfate sodium as depressant could achieve the preferential flotation separation of scheelite from calcite and fluorite by control of pulp pH at 7.0. The selective depressant effect of dextran sulfate sodium on calcite and fluorite was explored through surface analyses including zeta potential measurements, contact angle measurements and FTIR studies on mineral samples treated with dextran sulfate sodium and/or sodium oleate. On the basis of the surface analyses, a selective adsorption model of dextran sulfate sodium on calcite and fluorite was proposed.

Effects of dextran sulfate sodium induced experimental colitis on cytochrome P450 activities in rat liver, kidney and intestine

Dextran sulfate sodium (DSS) induced experimental colitis presents a histologic resemblance to human ulcerative colitis (UC). Altered cytochrome P450s (CYPs) have been reported in this model and patients with UC. In this study, six CYPs activities were quantitatively determined in microsomes of liver (RLMs), kidney (RRMs) and intestine (RIMs) from rats with colitis at acute (5% DSS for 7 days, UCA) and remission (7-day DSS treatment followed by 7-day cessation, UCR) phases and compared with normal rats. Generally, CYPs activities varied with isoform, organ, and disease status. Hepatic CYP1A2, 2B1, 2C6/11, 2E1 and 3A1/2 activities were reduced by acute colitis and completely or partially restored after DSS was halted. Although DSS treatment decreased the Vmax of renal CYP2C6/11 and increased that of CYP2D2, their CLint, in vitro were comparable among normal, acute and remission stages. DSS treatment changed the kinetics of CYP3A1/2-mediated nifedipine metabolism in RRMs from biphasic to classical kinetics. Notably, CYP2D2 activity was elevated in liver and kidney in acute UC, while enhanced in liver and decreased in kidney in remission. In intestine, CYP3A1/2 activity was increased in UCA and further enhanced after DSS withdrawal. These findings highlight the necessity of quantifying enzyme activity for precision drug therapy.

Soy protein concentrate mitigates markers of colonic inflammation and loss of gut barrier function in vitro and in vivo

Whereas a number of studies have examined the effects of soy isoflavones and tocopherols on colonic inflammation, few have examined soy protein. We determined the radical scavenging and cytoprotective effects of soy protein concentrate (SPC) in vitro and its anti-inflammatory effects in dextran sulfate sodium (DSS)-treated mice. Cotreatment with SPC protected Caco-2 human colon cells from H2O2-induced cell death and mitigated intracellular oxidative stress. Treatment of differentiated Caco-2 cells with SPC blunted DSS-induced increases in monolayer permeability. Pepsin/pancreatin-digested SPC had reduced radical scavenging activity, but retained the monolayer protective effects of SPC. In vivo, 1.5% DSS caused body weight loss, colon shortening, and splenomegaly in CF-1 mice. Co-treatment with 12% SPC mitigated DSS-induced body weight loss and splenomegaly. DSS increased colonic interleukin (IL)-1β, IL-6, and monocyte chemotactic protein-1 expression. The levels of these markers were significantly lower in mice co-treated with SPC. SPC prevented DSS-mediated reductions in colonic glucagon-like peptide 2 levels, suggesting that SPC can prevent loss of gut barrier function, but no significant effect on claudin 1 and occludin mRNA levels of was observed. SPC-treated mice had lower colonic mRNA expression of toll-like receptor 4 and nucleotide-binding oligomerization domain-containing protein-like receptor family, pyrin domain containing protein 3 (NLRP3), and lower caspase-1 enzyme activity than DSS-treated mice. In summary, SPC exerted antioxidant and cytoprotective effects in vitro and moderated the severity of DSS-induced inflammation and loss of gut barrier function in vivo. These effects appear to be mediated in part through reduced NLRP3 expression and caspase 1 activity.

P110. Cigarette smoke modulates the effect of dextran sulfate sodium–induced colitis on a subpopulation of T-cells in blood and colon in mice

P110. Cigarette smoke modulates the effect of dextran sulfate sodium–induced colitis on a subpopulation of T-cells in blood and colon in mice

Glucagon-like peptide-2-loaded microspheres as treatment for ulcerative colitis in the murine model

Glucagon-like peptide-2 (GLP-2) is an intestinal hormone that promotes intestinal growth, but the rapid degradation by dipeptidyl peptidase-IV limits its applications. PLGA microsphere is a well-developed drug delivery system, while seldom been studied as a solution for prolonging in vivo effects of GLP-2. In this study, we encapsulated porcine GLP-2 (pGLP-2) into microspheres and investigated its therapeutic effects in dextran sulfate sodium (DSS)-treated mice. pGLP-2 microspheres showed 20.36% in initial burst and constant release for at least 9 d. In the DSS-treated mice, a single injection of GLP-2 microspheres significantly increased the body weight, colonic length, small intestinal weight and mRNA expression of Occludin, decreased the colonic damage score, mRNA expression of IL-6, IL-10, TNF-α and IFN-γ. In conclusion, pGLP-2 microspheres were resistant to degradation and decreased the severity of DSS-induced ulcerative colitis which suggested that GLP-2-loaded microspheres could be a proper candidate for the treatment of ulcerative colitis.

Goji berry attenuates dextran sulfate sodium‐induced colitis

Inflammatory bowel diseases (IBD) including ulcerative colitis (UC) and Crohn's disease, are gastrointestinal disorders characterized by intestinal inflammation. Goji berry (Lycium barbarum), also known as wolfberry, is a traditional Chinese herbal medicine, which has long been recognized for its health beneficial effects such as antioxidative effects and diabetes prevention. Nonetheless, little is known regarding its effects in dextran sulfate sodium (DSS)‐induced colitis, a common colitis model of mice, which was investigated in this study. C57BL/6J male mice were first fed a standard rodent diet with or without 1% (w/w) goji berry for 4 weeks, then colitis was induced by supplementing 3% DSS in drinking water for 7 days, followed by a 7‐day recovery period to mimic symptoms of UC. Goji supplementation has no effects on body weight gain and feed intake in mice without DSS‐induced colitis. In DSS‐induced groups, Goji berry ameliorated body weight loss, diminished diarrhea and gross bleeding, resulting in a significantly decreased disease activity index associated with diminished DSS‐induced colon shortening. Histologically, Goji berry improved colonic edema, mucosal damage, and goblet cell depletion induced by DSS. In addition, Goji berry suppressed abnormal IL‐6 and COX2 mRNA expression, as well as apoptosis marker, active caspase‐3 content. In conclusion, for the first time, we demonstrate that dietary Goji berry supplementation confers protective effects against DSS‐induced colitis, suggesting a potential therapeutic value for IBD patients (NIH R15HD073864).

Therapeutic effects of mouse bone marrow-derived clonal mesenchymal stem cells in a mouse model of inflammatory bowel disease

Mouse bone marrow-derived clonal mesenchymal stem cells (mcMSCs), which were originated from a single cell by a subfractionation culturing method, are recognized as new paradigm for stem cell therapy featured with its homogenous cell population. Next to proven therapeutic effects against pancreatitis, in the current study we demonstrated that mcMSCs showed significant therapeutic effects in dextran sulfate sodium (DSS)-induced experimental colitis model supported with anti-inflammatory and restorative activities. mcMSCs significantly reduced the disease activity index (DAI) score, including weight loss, stool consistency, and intestinal bleeding and significantly increased survival rates. The pathological scores were also significantly improved with mcMSC. We have demonstrated that especial mucosal regeneration activity accompanied with significantly lowered level of apoptosis as beneficiary actions of mcMSCs in UC models. The levels of inflammatory cytokines including TNF-α, IFN-γ, IL-1β, IL-6, and IL-17 were all significantly concurrent with significantly repressed NF-κB activation compared to the control group and significantly decreased infiltrations of responsible macrophage and neutrophil. Conclusively, our findings provide the rationale that mcMSCs are applicable as a potential source of cell-based therapy in inflammatory bowel diseases, especially contributing either to prevent relapse or to accelerate healing as solution to unmet medical needs in IBD therapy.

Extraintestinal Helminth Infection Limits Pathology and Proinflammatory Cytokine Expression during DSS-Induced Ulcerative Colitis: A Role for Alternatively Activated Macrophages and Prostaglandins.

Chronic inflammation of the intestinal mucosa is characteristic of inflammatory bowel diseases such as ulcerative colitis and Crohn's disease. Helminth parasites have developed immunomodulatory strategies that may impact the outcome of several inflammatory diseases. Therefore, we investigated whether Taenia crassiceps infection is able to decrease the inflammatory effects of dextran sulfate sodium- (DSS-) induced ulcerative colitis in BALB/c and C57BL/6 mice. Preinfection significantly reduced the manifestations of DSS-induced colitis, as weight loss and shortened colon length, and decreased the disease activity index independently of the genetic background of the mice. Taenia infection decreased systemic levels of proinflammatory cytokines while increasing levels of IL-4 and IL-10, and the inflammatory infiltrate into the colon was also markedly reduced. RT-PCR assays from colon showed that T. crassiceps-infected mice displayed increased expression of Arginase-1 but decreased expression of iNOS compared to DSS-treated uninfected mice. The percentages of T regulatory cells were not increased. The adoptive transfer of alternatively activated macrophages (AAMФs) from infected mice into mice with DSS-induced colitis reduced the severity of colon inflammation. Administration of indomethacin abrogated the anticolitic effect of Taenia. Thus, T. crassiceps infection limits the pathology of ulcerative colitis by suppressing inflammatory responses mechanistically associated with AAMФs and prostaglandins.

Agaricus bisporus attenuates dextran sulfate sodium-induced colitis.

Agaricus bisporus (white button mushroom, WBM) is widely consumed in most countries and is reported to have anti-inflammatory and antioxidant activities. However, little is known regarding its effects in dextran sulfate sodium (DSS)-induced colitis, which are related to dysfunction of intestinal immunity. The aim of the present study was to investigate the effects of WBMs in an animal model of DSS-induced colitis. Male, 4-week-old ICR mice (n=10 per group) were fed a normal diet with or without 10% WBM for 4 weeks, and colitis was induced by 3% DSS in drinking water for 7 days. WBMs prevented DSS-induced shortening of colon length (P=.033) and diminished diarrhea (P=.049) and gross bleeding (P=.001), resulting in a decreased disease activity index. Results of histological analysis showed that WBMs suppressed mucosal damage. In addition, WBMs attenuated the DSS-induced increase in myeloperoxidase activity (P=.012) and upregulation of proinflammatory cytokine tumor necrosis factor-α (P=.020) in the colon segment. Taken together, these findings suggest a possible role for the WBM as an immunomodulator that can prevent and/or treat ulcerative colitis.

Inflammation Enhanced X-irradiation-Induced Colonic Tumorigenesis in the Min mouse

Inflammation is potential risk factor of various human malignancies. Inflammatory bowel syndromes such as ulcerative colitis are well known as risk factors for colon cancer. Here, we examined enhancing effects of dextran sulfate sodium (DSS)-associated inflammation on X-irradiation induced colonic tumorigenesis in Min and wild-type (WT) mice. Animals were X-irradiated at 1.5 Gy at 5 weeks of age (at 0 experimental week) and 2% DSS in drinking water was administered at 5 or 11 experimental weeks. Mice were sacrificed at 16 weeks and incidence and multiplicity of colonic tumors were assessed. Incidence of colonic tumors in Min mouse was increased from 33.3% to 100% (p<0.05) with X-irradiation alone, whereas no tumors were developed in WT mice. In DSS-treated Min mice, X-irradiation increased the number of colonic tumors. Total number of colonic tumors was increased 1.57 times to 30.7±3.83 tumors/mouse with X-irradiation+DSS at 5 weeks comapared to 19.6±2.9 in corresponding DSS alone group (p<0.05). When the duration of inflammation was compared, longer period of DSS effect promoted more colonic tumorigenesis. Collectively, we conclude that X-irradiation and DSS-induced inflammation act synergistically for colonic tumorigenesis.

Role of metallothionein in murine experimental colitis

Metallothioneins (MTs) are a family of cysteine-rich low molecular-weight proteins that can act as reactive oxygen species scavengers. Although it is known that the induction of MT expression suppresses various inflammatory disorders, the role of MTs in intestinal inflammation remains unclear. In this study, we investigated the effects of dextran sulfate sodium (DSS) administration in mice with targeted deletions of the MT-I/II genes. Acute colitis was induced by 2% DSS in male MT-I/II double knockout (MT-null) and C57BL/6 (wild-type) mice. The disease activity index (DAI) was determined on a daily basis for each animal, and consisted of a calculated score based on changes in body weight, stool consistency and intestinal bleeding. Histology, colon length, myeloperoxidase (MPO) activity and colonic mRNA expression and the concentration of inflammatory cytokines were evaluated by real-time-PCR and enzyme-linked immunosorbent assay (ELISA). The localization of MTs and macrophages was determined by immunohistological and immunofluorescence staining. To investigate the role of MTs in macrophages, peritoneal macrophages were isolated and their responses to lipopolysaccharide were measured. Following DSS administration, the DAI score increased in a time-dependent manner and was significantly enhanced in the MT-I/II knockout mice. Colonic MPO activity levels and inflammatory cytokines [tumor necrosis factor (TNF)-α, interferon (IFN)-γ and interleukin (IL)-17] production increased following DSS administration, and these increases were significantly enhanced in the MT-I/II knockout mice compared with the wild-type mice. MT-positive cells were detected in the lamina propria and submucosal layer by immunohistochemical and immunofluorescence staining, and were mainly co-localized in F4/80-positive macrophages. The production of inflammatory cytokines (TNF-α, IFN-γ and IL-17) from isolated peritoneal macrophages increased following lipopolysaccharide stimulation, and these increases were significantly enhanced in the macrophages obtained from the MT-I/II knockout mice. These data indicate that MTs play an important role in the prevention of colonic mucosal inflammation in a mouse model of DSS-induced colitis, thus suggesting that endogenous MTs play a protective role against intestinal inflammation.

Netrin-1 regulates colon-kidney cross talk through suppression of IL-6 function in a mouse model of DSS-colitis

Organ cross talk is increasingly appreciated in human disease, and inflammatory mediators are shown to mediate distant organ injury in many disease models. Colitis and intestinal injury are known to be mediated by infiltrating immune cells and their secreted cytokines. However, its effect on other organs, such as the kidney, has never been studied. In the current study, we examined the effect of dextran sulfate sodium (DSS)-colitis on kidney injury and inflammation. In addition, we hypothesized that netrin-1 could modulate colon-kidney cross talk through regulation of inflammation and apoptosis. Consistent with our hypothesis, DSS-colitis induced acute kidney injury in mice. Epithelial-specific overexpression of netrin-1 suppressed both colitis and colitis-induced acute kidney injury, which was associated with reduced weight loss, neutrophil infiltration into colon mucosa, intestinal permeability, epithelial cell apoptosis, and cytokine and chemokine production in netrin-1 transgenic mice colon and kidney. To determine whether netrin-1-protective effects were mediated through suppression of IL-6, IL-6 knockout mice were treated with DSS and acute kidney injury was determined. IL-6 knockout was resistant to colitis and acute kidney injury. Moreover, administration of IL-6 to netrin-1 transgenic mice did not affect the netrin-1-protective effects on the colon and kidney, suggesting that netrin-1 may reduce both IL-6 production and its activity. The present study identifies previously unrecognized cross talk between the colon and kidney, and netrin-1 may limit distant organ injury by suppressing inflammatory mediators and apoptosis.

Effects of co-treatment of dextran sulfate sodium and MeIQx on genotoxicity and possible carcinogenicity in the colon of p53-deficient mice

To investigate the effects of dextran sulfate sodium (DSS) and/or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) on in vivo genotoxicity in the colon, male C57BL/6 p53 (+/+), p53 (+/-) or p53 (-/-) gpt delta mice were twice given 1-week treatment with DSS, 2 weeks apart, and then sacrificed after 2 and 14 weeks. Although colon length was significantly shortened after DSS treatment in all genotypes at each time point, no significant difference in gpt mutant frequency (MF) and tumorigenicity was found between DSS and control groups regardless of genotype. Then, male B6C3F(1) p53 (+/+) or p53 (+/-) gpt delta mice were given DSS as described above and/or fed 300 ppm MeIQx for 7 weeks. Colon length was significantly shortened with DSS in either genotype at weeks 7 and 26, but no effects of co-treatment with MeIQx or p53 deficiency were evident. MeIQx showed a tendency to increase gpt MF in the colon of mice with either genotype, but co-treatment with DSS did not affect these increments. Appreciable incidences of colonic aberrant crypt foci (ACFs) were reported in DSS as well as co-treatment groups of each genotype. Colonic adenomas were observed in co-treatment groups of both genotypes as well as the DSS-only group of p53 (+/+). No effects of the combination of DSS and MeIQx on colon pre- and neoplastic lesions were reported. Our results indicate that MeIQx may take more than 7 weeks to induce genotoxicity in the colon and that the co-treatment of mice did not enhance colon tumorigenicity even in p53-deficient mice.

The Role of Dendritic Cells in the Development of Acute Dextran Sulfate Sodium Colitis

Dendritic cells (DCs) are essential mediators of the host immune response to surrounding microbes. In this study, we investigate the role of DCs in the pathogenesis of a widely used colitis model, dextran sulfate sodium-induced colitis. The effect of dextran sulfate sodium on the production of proinflammatory cytokines and chemokines by bone marrow-derived DCs (BM-DCs) was analyzed. BM-DCs were adoptively transferred into C57BL/6 mice or DCs were ablated using transgenic CD11c-DTR/GFP mice before treatment with 5% dextran sulfate sodium in drinking water. We found that dextran sulfate sodium induced production of proinflammatory cytokines (IL-12 and TNF-alpha) and chemokines (KC, MIP-1alpha, MIP-2, and MCP-1) by DCs. Adoptive transfer of BM-DCs exacerbated dextran sulfate sodium colitis while ablation of DCs attenuated the colitis. We conclude that DCs are critical in the development of acute dextran sulfate sodium colitis and may serve a key role in immune balance of the gut mucosa.