κ-carrageenan induces the disruption of intestinal epithelial Caco-2 monolayers by promoting the interaction between intestinal epithelial cells and immune cells

-carrageenan (-CGN) is an important food additive that has been demonstrated to induce colitis in animal models. In the present study, the effects of -CGN were assessed using an in vitro co-culture system that contained intestinal epithelial Caco-2 cells and activated macrophage-like THP-1 cells. The results demonstrated that in single cultures of Caco-2 and THP-1 cells treated with -CGN, the cytotoxicity and the secretion levels of IL-1, IL-6 and TNF- were low. In the co-culture system, however, -CGN treatment resulted in apoptosis and reduced the transepithelial electrical resistance of the Caco-2 cell monolayers. The secretion levels of TNF-, IL-1 and IL-6 from the two cell types were increased significantly by -CGN treatment. Furthermore, pretreatment of the co-culture system with anti-TNF receptor 1 antibody suppressed the -CGN-induced apoptosis and attenuated the changes in the levels of IL-6 and IL-1 in the Caco-2 monolayers. This study indicated that -CGN-induced TNF- secretion is the main contributor to cellular damage in Caco-2 monolayers exposed to -CGN.