Pathogenic mechanisms responsible for inflammatory bowel disease (IBD) are poorly understood. In an IBD animal model, the oral administration of polysaccharides such as dextran sulfate sodium (DSS) induces colitis, which exhibit several clinical and histological features for IBD. However, pathogenic factors in the development of colitis remain unclear. Therefore, we investigated possible mechanisms for DSS-induced colitis, and mainly focused on biological responses from an intestinal epithelial cell line, Caco-2. Cytotoxicity and cytokine release were measured using MTS assays and ELISA, respectively. The effect of DSS on the transepithelial electrical resistance (TEER) of Caco-2 cell monolayers was also evaluated. Cell cycle progression was estimated using antibodies directed against p53 and cdc-2 proteins. The generation of reactive oxygen species (ROS) was measured using a DCFH-DA method. Pyridylamino-DSS (PA-DSS) was used as a fluorometric label in order to investigate fluorescence-microscopically the location of DSS in Caco-2 cells. DSS induced cytotoxicity on Caco-2 cells at 5%. DSS also induced strong TEER decrease at 3%. DSS induced the weak release of IL-8, IL-6, and TGF-beta1. Remarkably DSS arrested Caco-2 cell cycle and reduced the intracellular generation of ROS. Under fluorescence microscopy, PA-DSS entered cells and bound to the nucleus, indicating this binding of DSS may be involved in the cell cycle arrest of Caco-2 cells. The cell cycle arrest and reduced intracellular generation of ROS may be involved during initiation or throughout the early stages of DSS-induced colitis.
"Although the etiopathogenesis is poorly understood, it is believed that IBD stems from a dysregulated immune response towards otherwise harmless commensal bacteria that are normally present in the colon . DSS is thought to permeablise the mucosal membrane of the colon to enteric bacterial  by inducing epithelial injury . Interestingly, DSS may also elicit colitis by promoting the proliferation of gram-negative bacteria in mice . "
[Show abstract][Hide abstract] ABSTRACT: Inflammatory bowel disease (IBD) is a group of disorders that are characterized by chronic, uncontrolled inflammation in the intestinal mucosa. Although the aetiopathogenesis is poorly understood, it is widely believed that IBD stems from a dysregulated immune response towards otherwise harmless commensal bacteria. Chemokines induce and enhance inflammation through their involvement in cellular trafficking. Reducing or limiting the influx of these proinflammatory cells has previously been demonstrated to attenuate inflammation. CXCR3, a chemokine receptor in the CXC family that binds to CXCL9, CXCL10 and CXCL11, is strongly overexpressed in the intestinal mucosa of IBD patients. We hypothesised that CXCR3 KO mice would have impaired cellular trafficking, thereby reducing the inflammatory insult by proinflammatory cell and attenuating the course of colitis. To investigate the role of CXCR3 in the progression of colitis, the development of dextran sulfate sodium (DSS)-induced colitis was investigated in CXCR3-/- mice over 9 days. This study demonstrated attenuated DSS-induced colitis in CXCR3-/- mice at both the macroscopic and microscopic level. Reduced colitis correlated with lower recruitment of neutrophils (p = 0.0018), as well as decreased production of IL-6 (p<0.0001), TNF (p = 0.0038), and IFN-γ (p = 0.0478). Overall, our results suggest that CXCR3 plays an important role in recruiting proinflammatory cells to the colon during colitis and that CXCR3 may be a therapeutic target to reduce the influx of proinflammatory cells in the inflamed colon.
PLoS ONE 07/2014; 9(7):e101622. DOI:10.1371/journal.pone.0101622 · 3.23 Impact Factor
"DSS is often considered a toxicity model as in vitro studies testing the effects of DSS on epithelial cell lines show that direct exposure causes the cell cycle arrest of epithelial cells . However, these in vitro studies did not take into account the role of the mucus layer found in in vivo conditions. "
[Show abstract][Hide abstract] ABSTRACT: CD4+ T cell responses against oral antigens can develop in inflammatory bowel disease (IBD) patients, which may modulate disease. Dextran sodium sulfate (DSS) colitis is commonly used to study IBD, however, it is not considered the best model in which to study T cell involvement in intestinal disease. Our aim was to determine if antigen-specific T cells could be induced during DSS colitis and if they could be detected after disease resolution. To induce antigen-specific T cells, the tracking antigen, ovalbumin (OVA), was administered orally during colitis initiation. Disease severity was monitored, and the antigen-reactivity of CD4+ T cells examined using CD69 expression. While OVA-directed, CD4+ Foxp3+ regulatory T cells could be detected in the spleens of both OVA-treated control and DSS mice, OVA-reactive, CD4+ Foxp3-T cells were only found in the OVA and DSS-treated mice. These results indicate that during DSS colitis T cells develop that are specific against oral antigens, and they are found systemically after colitis resolution. This gives added depth and utility to the DSS model as well as a way to track T cells that are primed against luminal antigens.
PLoS ONE 07/2013; 8(7):e69936. DOI:10.1371/journal.pone.0069936 · 3.23 Impact Factor
"The Caco-2 monolayers were cocultured with 10 6 to 10 8 cfu/mL of Lb. kefiranofaciens M1 at 37°C for 24 h, followed by the addition of 3% DSS for 30 h (Araki et al., 2006). The TEER values before coculture with M1 and after treatment with DSS were measured. "
[Show abstract][Hide abstract] ABSTRACT: Lactobacillus kefiranofaciens M1, isolated from and identified in Taiwanese milk kefir grain, has demonstrated immune-modulating activity. In the present study, we further investigated the effects of Lb. kefiranofaciens M1 on intestinal epithelial cells in vitro and on dextran sodium sulfate (DSS)-induced colitis in vivo. The possible mechanisms regarding the cytokine products and intestinal epithelial barrier restoration as well as the putative receptor for the protective effects of Lb. kefiranofaciens M1 were investigated. In vitro results indicated that Lb. kefiranofaciens M1 could strengthen the epithelial barrier function in vitro by increasing the transepithelial electrical resistance (TEER) and significantly upregulated the level of the chemokine CCL-20 at both the apical and basolateral sites. The in vivo effects of Lb. kefiranofaciens M1 on the regulation of intestinal physiology indicate that this strain could ameliorate DSS-induced colitis with a significant attenuation of the bleeding score and colon length shortening. Production of proinflammatory cytokines was decreased and that of the antiinflammatory cytokine IL-10 was increased in the DSS-treated mice given Lb. kefiranofaciens M1. The putative receptor for the protective effects of Lb. kefiranofaciens M1 was toll-like receptor 2 (TLR2), which was involved in probiotic-induced cytokine production in vitro and in attenuation of the bleeding score and colon length shortening in vivo. In this study, the kefir lactobacillus Lb. kefiranofaciens M1 clearly demonstrated an anticolitis effect. Based on these results, Lb. kefiranofaciens M1 has the potential to be applied in fermented dairy products as an alternative therapy for intestinal disorders.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.