Protective effect of oligochitosan on LPS-induced inflammation of the intestinal epithelial cells

Abstract

Objective To investigate the protective effect of oligochitosan on lipopolysaccharide (LPS) induced inflammation of the intestinal epithelial cells. Methods intestinal epithelial cells Caco-2 were divided into five groups: normal control group, model group, high-, medium-and low-level oligochitosan groups. In the oligochitosan groups, the cells were pre-treated with 0.25, 0.5 and 1.0 g/L oligochitosan, respectively, at 2 h before LPS stimulation. MTT method was used for cell viability assay. ELISA was used to measure the levels of inflammation related cytokines, such as tumor necrotizing factor-related factor alpha (TNF-α) , interleukin-8 (IL-8) and prostaglandin E2 (PGE2) , in the cell culture supernatant. Western blotting was used to detect the changes in expression of Toll-like receptor 4 (TLR4) , nuclear factor κB (NF-κB) and cyclooxygenase 2 (COX-2). Results The Caco-2 cell viability was not affected by treatment with oligochitosan and/or LPS. Compared with the model group, 0.25, 0.5 and 1.0 g/L oligochitosan reduced the production of TNF-α (352.5±21.6, 298.4±25.1, 203.4±20.0 vs 436 .8±38.7 μg/L, P<0.05) and PGE2 (632.2±35.6, 522.6±26.7, 402.4±30.2 vs 822.3±23.5 μg/L, P<0.01) in Caco-2 cells in a dose dependent manner; 0.5 and 1.0 g/L oligochitosan reduced COX 2 expression (P<0.05 and P<0.01) ; medium-and high-level oligochitosan was significantly associated with lowered expression of TLR4 compared with the model group (P<0.05) ; the expression of NF-κB in each group of oligochitosan dosage was significantly lowered (P<0.05; P<0.01). Conclusion Oligochitosan may reverse LPS-induced inflammation of the intestinal epithelial cells and therefore may be potentially protective against inflammatory bowel diseases. The underlysing mechanism of this action may be related to inhibition of TLR4/NF-κB signaling pathway. Key words: Inflammation; Intestinal epithelial cells; Lipopolysaccharide; Oligochitosan; TLR4