The polysaccharide from the roots of Actinidia eriantha activates RAW264.7 macrophages via regulating microRNA expression.

The polysaccharide from the roots of Actinidia eriantha (AEPS), a potent antitumor agent and immunological adjuvant, has been previously reported to activate RAW264.7 macrophages via TLRs/NF-κB signaling. The objective of this study was to investigate microRNA (miRNA) expression profiles and explore the role of miRNAs in AEPS-activated RAW264.7 cells using microarray assay and specific inhibitor. AEPS induced 82 differentially expressed miRNAs including 43 up-regulated and 39 down-regulated in RAW264.7 cells. A set of 11 differentially expressed miRNAs and their 62 target mRNAs were predicted to involve in activation of RAW264.7 cell induced by AEPS based on computational databases and validated reports. miR-155 inhibitor significantly down-regulated the mRNA expression of proinflammatory factors (IL-1β, IL-6, COX-2 and NOS2), and blocked the production of NO in RAW264.7 cell induced by AEPS. The expression of accessory and costimulatory molecules (CD80, CD86, MHC I and MHC II) in AEPS-activated RAW264.7 cells was also remarkably reduced by miR-155 inhibitor. These results suggested that AEPS may induce macrophage activation through regulating miRNAs expression such as miR-155. This study further expanded current knowledge on the mechanisms of plant polysaccharides.