DSS-exposed Mice Research Articles

Resveratrol (Trans-3,5,4′-trihydroxystilbene) Induces Silent Mating Type Information Regulation-1 and Down-Regulates Nuclear Transcription Factor-κB Activation to Abrogate Dextran Sulfate Sodium-Induced Colitis

Inflammatory bowel disease is a chronic, relapsing, and tissue-destructive disease. Resveratrol (3,4,5-trihydroxy-trans-stilbene), a naturally occurring polyphenol that exhibits beneficial pleiotropic health effects, is recognized as one of the most promising natural molecules in the prevention and treatment of chronic inflammatory disease and autoimmune disorders. In the present study, we investigated the effect of resveratrol on dextran sodium sulfate (DSS)-induced colitis in mice and found that it effectively attenuated overall clinical scores as well as various pathological markers of colitis. Resveratrol reversed the colitis-associated decrease in body weight and increased levels of serum amyloid A, tumor necrosis factor-alpha, interleukin (IL-6), and IL-1beta. After resveratrol treatment, the percentage of CD4(+) T cells in mesenteric lymph nodes (MLN) of colitis mice was restored to normal levels, and there was a decrease in these cells in the colon lamina propria (LP). Likewise, the percentages of macrophages in MLN and the LP of mice with colitis were decreased after resveratrol treatment. Resveratrol also suppressed cyclooxygenase-2 (COX-2) expression induced in DSS-exposed mice. Colitis was associated with a decrease in silent mating type information regulation-1 (SIRT1) gene expression and an increase in p-inhibitory kappaB expression and nuclear transcription factor-kappaB (NF-kappaB) activation. Resveratrol treatment of mice with colitis significantly reversed these changes. This study demonstrates for the first time that SIRT1 is involved in colitis, functioning as an inverse regulator of NF-kappaB activation and inflammation. Furthermore, our results indicate that resveratrol may protect against colitis through up-regulation of SIRT1 in immune cells in the colon.

Granulocyte-macrophage colony-stimulating factor elicits bone marrow-derived cells that promote efficient colonic mucosal healing

Granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy is effective in treating some Crohn's disease (CD) patients and protects mice from colitis induced by dextran sulfate sodium (DSS) administration. However, its mechanisms of action remain elusive. We hypothesized that GM-CSF affects intestinal mucosal repair. DSS colitic mice were treated with daily pegylated GM-CSF or saline and clinical, histological, and inflammatory parameters were kinetically evaluated. Further, the role of bone marrow-derived cells in the impact of GM-CSF therapy on DSS colitis was addressed using cell transfers. GM-CSF therapy reduced clinical signs of colitis and the release of inflammatory mediators. GM-CSF therapy improved mucosal repair, with faster ulcer reepithelialization, accelerated hyperproliferative response of epithelial cells in ulcer-adjacent crypts, and lower colonoscopic ulceration scores in GM-CSF-administered mice relative to untreated mice. We observed that GM-CSF-induced promotion of mucosal repair is timely associated with a reduction in neutrophil numbers and increased accumulation of CD11b(+) monocytic cells in colon tissues. Importantly, transfer of splenic GM-CSF-induced CD11b(+) myeloid cells into DSS-exposed mice improved colitis, and lethally irradiated GM-CSF receptor-deficient mice reconstituted with wildtype bone marrow cells were protected from DSS-induced colitis upon GM-CSF therapy. Lastly, GM-CSF-induced CD11b(+) myeloid cells were shown to promote in vitro wound repair. Our study shows that GM-CSF-dependent stimulation of bone marrow-derived cells during DSS-induced colitis accelerates colonic tissue repair. These data provide a putative mechanism for the observed beneficial effects of GM-CSF therapy in Crohn's disease.

Tomato Lycopene Extract Prevents Lipopolysaccharide-Induced NF-κB Signaling but Worsens Dextran Sulfate Sodium-Induced Colitis in NF-κBEGFP Mice

BackgroundThe impact of tomato lycopene extract (TLE) on intestinal inflammation is currently unknown. We investigated the effect of TLE on lipopolysaccharide (LPS)-induced innate signaling and experimental colitis.Methodology/Principal FindingsMice were fed a diet containing 0.5 and 2% TLE or isoflavone free control (AIN-76). The therapeutic efficacy of TLE diet was assessed using dextran sulfate sodium (DSS) exposed mice and IL-10−/−;NF-κBEGFP mice, representing an acute and spontaneous chronic colitis model respectively. A mini-endoscope was used to determine the extent of macroscopic mucosal lesions. Murine splenocytes and intestinal epithelial cells were used to determine the in vitro impact of TLE on LPS-induced NF-κB signaling. In vitro, TLE blocked LPS-induced IκBα degradation, RelA translocation, NF-κB transcriptional activity and MIP-2 mRNA accumulation in IEC-18 cells. Moreover, LPS-induced IL-12p40 gene expression was dose-dependently inhibited in TLE-treated splenocytes. Interestingly, DSS-induced acute colitis worsened in TLE-fed NF-κBEGFP mice compared to control diet as measured by weight loss, colonoscopic analysis and histological scores. In contrast, TLE-fed IL-10−/−;NF-κBEGFP mice displayed decreased colonic EGFP expression compared to control diet. IL-6, TNFα, and MCP-1 mRNA expression were increased in the colon of TLE-fed, DSS-exposed NF-κBEGFP mice compared to the control diet. Additionally, caspase-3 activation and TUNEL positive cells were enhanced in TLE diet-fed, DSS-exposed mice as compared to DSS control mice.Conclusions/ SignificanceThese results indicate that TLE prevents LPS-induced proinflammatory gene expression by blocking of NF-κB signaling, but aggravates DSS-induced colitis by enhancing epithelial cell apoptosis.

917 Activation of T Lymphocytes and Macrophage Contributes to IL-1β-Induced Gastric Inflammation and Carcinogenesis

time RT-PCR of human colon tissue cDNAs showed higher expression of NK-1R in colon tumors than in normal colon. Western blot analyses showed that 3 of 5 different human colon tumor lysates express NK-1R while all matching adjacent normal colon tissues were negative for NK-1R. In NK-1R expressing human colonic cancer cells (transfected and nontransfected) SP induced ERK1/2 phosphorylation (Western blots), stimulated cell proliferation (MTS assay) via an ERK-1/2 dependent pathway, and inhibited cell apoptosis in response to Fas ligand (FasL). In modified Boyden chamber assays, SP augmented cell migration and invasiveness of SW620-NK-1R cells, indicating that SP may promote colon cancer development and metastasis. We next examined whether SP promotes colon cancer development In Vivo. Colitis was induced in colon cancer prone Apc/Min mice (n= 8 per group) by adding 5% dextran sulfate (DSS) in their drinking water for 5 days and then switched to drinking water for 8 week. Apc/Min mice were injected with the NK-1R antagonist CJ12255 5 mg/kg i.p. or vehicle every 2 d during the last two weeks of the experiment, then sacrificed and colon tumors were evaluated. ~80% of DSS-exposed mice in the vehicleinjected group showed an average of 4 colon tumors per mouse with tumor lyates showing elevated Akt and ERK1/2 phosphorylation. CJ-12225 treatment significantly reduced tumor onset, number and size, and inhibited Akt and ERK1/2 phosphorylation. DSS colitis (one week, 2% DSS) also promoted colon tumor formation after treatment with the carcinogen azoxymethane in wild-type mice. However, homozygous NK-1R knockout mice receiving the same treatment showed significantly less tumor onset, number and size. Conclusions: These are the first results indicating that SP and NK-1R participate in the development of colitis-associated colon cancer. Supported by a Research Fellowship from CCFA to HWK and a NIH grant DK47343 to CP.