Apios americana Medikus tuber polysaccharide exerts anti-inflammatory effects by activating autophagy

The tubers of Apios americana Medikus possess high nutritional value and have been used as food in many countries for a long time. However, few researches have focused on the tuber polysaccharides. In the present study, a purified polysaccharide (ATP-1) was isolated with the average molecular weights of 12.16 kDa. ATP-1 significantly suppressed the release of nitric oxide (NO) and inflammatory cytokines from LPS-induced RAW 264.7 cells, as well as oxidative stress and mitochondrial dysfunction. Meanwhile, ATP-1 reduced oxidative damage via the NF-κB, MAPKs and Nrf2-Keap1 signaling pathways in RAW264.7 macrophages. Furthermore, autophagy was activated by HMGB1-Beclin1, Sirt1-FoxO1 and Akt-mTOR signaling pathways, leading to a relief of oxidative stress, mitochondrial dysfunction, inflammation and an expression enhancement of autophagy-related proteins, such as LC3, Beclin1, Atg4, Atg5, and Atg7. In summary, our results suggested that ATP-1 might help to activate the anti-inflammation system，resulting in prevention of LPS-induced damage in RAW264.7 cells.