In vitro effects of dextran sulfate sodium on a Caco-2 cell line and plausible mechanisms for dextran sulfate sodium-induced colitis

Abstract

Abstract. 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-ß1. 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.

Increased apoptosis and decreased proliferation of colonic epithelium in dextran sulfate sodium-induced colitis in mice

“…This phenomenon indicates that DSS arrests the cell cycle far from cell proliferation. Our results are consistent with a previous study which showed that DSS decreased the number of proliferating epithelial cells bỹ 90% using the bromodeoxyuridine labeling system (26) and our previous in vitro study using Caco-2 cell line (11). Therefore, increased apoptosis and cell arrest might produce subsequent cell proliferation.…”

“…With respect to the pathogenic factors in this colitis model, our previous studies have postulated the importance of various factors such as the local involvement of reactive oxygen species (8,9), short chain fatty acids (SCFA) (10), and cell cycle arrest observed in vitro (11). In addition, even a certain dietary fiber can alter the intestinal microflora, produce short chain fatty acids, subsequently colitis improved in human and DSS-induced colitis (12)(13)(14)(15).…”

Differential immune and genetic responses in rat models of Crohn's colitis and ulcerative colitis

“…By contrast, Toll-like receptor 4 (TLR4) signaling, which limits bacterial translocation, mediates DSS inflammatory response (13,37). DSS arrests the epithelial cell cycle, resulting in apoptosis, impaired proliferation, and weak release of inflammatory mediators (2,23,49). DSS inflammation occurs in germ-free or severely combined immunodeficiency (scid) mice (11,22).…”

Early-stage formation of an epigenetic field defect in a mouse colitis model, and non-essential roles of T- and B-cells in DNA methylation induction

“…No induction of aberrant DNA methylation by treatment of colonic epithelial cells with DSS in vitro DSS is known to have direct effects on epithelial cells, such as induction of cell growth arrest and production of cytokines (Ni et al, 1996;Araki et al, 2006), and this raised a possibility that DSS might directly induce aberrant DNA methylation in colonic epithelial cells. To address this possibility, immortalized normal mouse colonic epithelial cells (LIF-16) were treated with four concentrations of DSS that inhibited cell growth in a dose-dependent manner ( Figure 3a).…”