Type II arabinogalactan from Anoectochilus formosanus induced dendritic cell maturation through TLR2 and TLR4

Background: Polysaccharides, considered as immunomodulators with the capacity to activate immunity against microbial pathogens and tumors, have been employed for their dietary and medical benefits. Purpose: This study investigated the immunomodulatory effect of polysaccharide such as type II arabinogalactan from Anoectochilus formosanus (AGAF) on dendritic cell (DC) maturation and the underlying molecular mechanisms. Methods and results: Exposing DCs to AGAF induces cell maturation, which is characterized by the upregulation of CD86, CD83, CD80, CD40, and MHC class land class II expression through flow cytometry analysis and morphological change without cytotoxicity. In addition, AGAF-triggered DC2.A cells were involved in priming T-cell activation in vitro and in vivo. Transfection of toll-like receptor (TLR) 2 proteins and TLR4 siRNA suppressed DC maturation, suggesting that AGAF induced DC maturation through TLR2 and TLR4. Conclusion: These findings indicate that AGAF may be a potentially effective immunomodulator in stimulating DC maturation. (C) 2015 Published by Elsevier GmbH.