Chitosan oligosaccharide (COS) inhibits LPS-induced inflammatory effects in RAW 264.7 macrophage cells

The focus of this study was to clarify the relation between the nitric oxide (NO) production and cytokine expression including tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and also investigated the effect of COS on LPS stimuli from RAW 264.7 cell. The lipopolysaccharide (LPS) of Gram-negative bacteria induces the expression of cytokines and potent inducers of inflammatory cytokines such as TNF-α and IL-6. In this experiment, upon stimulation with increasing concentrations of chitosan, the LPS-stimulated TNF-α and IL-6 secretion was significantly recovered within the incubation media of RAW 264.7 cells. Consistently, RT-PCR with mRNA and Western blot with anti-cytokine antiserum including TNF-α and IL-6 showed that the amount of TNF-α and IL-6 secretion in the incubation media recovered with the concentration of chitosan. The LPS-stimulated NO secretion was significantly recovered within the 6 h and 12 h incubation media of RAW 264.7 cells, too. The recovery effect of chitosan on IL-6 and NO secretion may be induced via the stimulus of TNF-α in RAW 264.7 cell. These results once again suggest that chitosan oligosaccharide may have the anti-inflammatory effect via the stimulus of TNF-α in the LPS-stimulated inflammation in RAW 264.7 cells.