Macrophage immunity promotion effect of polysaccharide LGP-1 from Guapian tea via PI3K/AKT and NF-κB signaling pathway

Functionalization and bestowing high values upon bioactive tea polysaccharides have been focused recently. For this purpose, the immune activation effect on RAW264.7 macrophages promoted by Lu’an Guapian polysaccharide (LGP-1, 2.35 × 105 Da) was investigated firstly. LGP-1 was obtained and characterized via DEAE 52 ion exchange column, high performance liquid chromatography and atomic force microscope. Immunological assay manifested a remarkable promotion effect on macrophages. LGP-1 could significantly stimulate the phagocytosis of macrophages, promote NO generation and trigger TNF-α, IL-6, IL-1β release dose-dependently. Fluorescence labeling tests confirmed the production level of reactive oxygen species increased obviously. Western blot results demonstrated that the treated macrophages were able to increase PI3K expression and p65 nuclear translocation, indicated that LGP-1 enhanced macrophage immunity via PI3K/AKT and NF-κB signaling pathways. Moreover, TLR4 was involved in the process. These results made clear that LGP-1 could be explored as a bioactive substance applied in functional foods.