The effects of chitosan oligosaccharide on the activation of murine spleen CD11c+ dendritic cells via Toll-like receptor 4

To investigate the effects of chitosan oligosaccharide (COS) on dendritic cells (DCs) and the role of Toll-like receptor 4 (TLR4) in this immune process, Murine spleen CD11c+ dendritic cells (SDCs) were isolated and cultured with S-COS and B-COS with polymeration degree of 3–7 and 7–16, respectively. The results showed that B-COS up-regulated the expressions of MHCII and CD86 on SDCs, promoted the secretion of TNF-α from SDCs. SDCs treated with B-COS stimulated the proliferation of the CD4+T cells. However, these effects were not observed on SDCs treated with S-COS. Importantly, silencing the TLR4 expressions on SDCs by RNA interference approach attenuated the expression of CD86, MHCII on SDCs, and the secretion of TNF-α from SDCs, and the stimulating CD4+T cells proliferation capacity of SDCs induced by B-COS. These results suggest that B-COS, but not S-COS, promotes the activation of SDCs and TLR4 plays a bridge role in this process.