Activation of RAW264.7 macrophages by the polysaccharide from the roots of Actinidia eriantha and its molecular mechanisms

• We investigated the activation of macrophages by AEPS and its molecular mechanisms.
• AEPS induce the expression of accessory and costimulatory molecules on macrophages.
• AEPS promote the production of proinflammatory factors from macrophages.
• AEPS activate macrophages and elicit a balanced M1/M2 response via TLR/NF-κB pathway.
• This study further expands our knowledge on mechanism how AEPS acts as a potent adjuvant.

The polysaccharide from the roots of Actinidia eriantha (AEPS), a potent antitumor agent and immunological adjuvant, was investigated for the immunomodulatory effects on RAW264.7 macrophages and its molecular mechanisms. AEPS could significantly enhance the pinocytic and phagocytic activity, induce the production of NO, TNF-α, IL-10, IL-1β and IL-6, and promote the expression of accessory and costimulatory molecules in RAW264.7 cells. PCR array assay revealed that AEPS up-regulated 28 genes including TLRs (TLR2, TLR8, TLR9), proinflammatory factors (IL-1β, G-CSF, IL-1α, GM-CSF, IL-6, COX-2, TNF-α, IFN-β, CXCL10, CCL2, TNF-β, IL-10), and the genes involved in NF-κB signaling pathway, and down-regulated 6 genes such as TLR3, TLR4, PGLYRP1, EIF2αK2, MAP3K1 and IRF1. AEPS was further showed to promote cytoplasmic IκB-α degradation and increase nuclear NF-κB p65 levels in RAW264.7 cells. These results suggested that AEPS activated RAW264.7 macrophages and elicited a M1 and M2 response through TLRs/NF-κB signaling pathway.