Abstract:

Objective To investigate the effect of whole ginseng pectin alcohol-precipitated polysaccharide fraction （WGPA） on the phenotype and function of mouse bone marrow-derived dendritic cells （BMDCs）. Methods Three WGPA fractions were extracted using water extraction， ethanol precipitation， and ion-exchange chromatography： the 30% ethanol-precipitated fraction （WGPA₃₀）， the 50% ethanol-precipitated fraction （WGPA₅₀）， and the 70% ethanol-precipitated fraction （WGPA₇₀）. The primary mouse BMDCs were cultured and categorized into immature BMDCs and mature BMDCs. Cell counting kit-8 （CCK-8） method was used to detect the proliferation activities of mature BMDCs in various groups treated with different concentrations of WGPA to determine the effective WGPA fraction and its appropriate concentration. The effective alcohol-precipitated fraction was analyzed for relative molecular mass， infrared spectrum， and monosaccharide composition. Both immature and mature BMDCs were randomly divided into control group， lipopolysaccharide （LPS） group （treated with LPS）， and WGPA group （treated with effective WGPA）. Flow cytometry was used to detect the expression levels of CD80， CD86， and major histocompatibility complex class Ⅱ （MHC-Ⅱ） on the surface of mature BMDCs in various groups. Fluorescent microsphere phagocytosis assay was used to detect the phagocytic efficiency of immature BMDCs in various groups； enzyme-linked immunosorbent assay （ELISA） was used to detect the levels of interleukin-6 （IL-6）， interleukin-12 （IL-12）， and tumor necrosis factor-α （TNF-α） in the culture supernatants of mature BMDCs in various groups. Results The results of CCK-8 method showed that compared with control group， the proliferation activities of mature BMDCs in 800 and 1 600 mg·L^-1 WGPA₃₀ groups were significantly increased （P<0.01），while the proliferation activities of mature BMDCs after treated with WGPA₅₀ or WGPA₇₀ showed no significant change （P>0.05）. Therefore， 800 mg·L^-1 WGPA₃₀ was selected for subsequent experiments.The structural analysis results revealed that WGPA₃₀ had a relative molecular mass of approximately 24 230， and it was a pyranose connected by α-configuration glycosidic bond whose main monosaccharide composition included glucuronic acid， xylose， glucose， and galactose. The flow cytometry results showed that compared with control group， the expression levels of MHC-Ⅱ， CD86， and CD80 on the surface of mature BMDCs in LPS group and WGPA₃₀ group were significantly increased （P<0.01）. Compared with LPS group， the expression levels of MHC-Ⅱ， CD86， and CD80 on the surface of mature BMDCs in WGPA₃₀ group were significantly decreased（P<0.05）. Compared with control group， the phagocytic activities of immature BMDCs in LPS group and WGPA₃₀ group were significantly decreased（P<0.05）.The ELISA results showed that compared with control group， the levels of IL-6， IL-12， and TNF-α in the supernatants of mature BMDCs in LPS group and WGPA₃₀ group were significantly increased （P<0.01）. Compared with LPS group， the levels of IL-12 and TNF-α in the supernatant of mature BMDCs in WGPA₃₀ group were significantly decreased （P<0.01）， while the level of IL-6 showed no statistically significant difference （P>0.05）. Conclusion WGPA₃₀ is a pyranose with α-configuration glycosidic bonds which contains primary active components such as glucose， galactose， and glucuronic acid， and has a relative molecular mass of approximately 24 230. WGPA₃₀ promotes the maturation and modulates the activity of BMDCs by enhancing their proliferation， stimulating the release of cytokines IL-6， IL-12， and TNF-α， upregulating the expression of surface molecules MHC-Ⅱ， CD86， and CD80， and decreasing their phagocytic efficiency.

Key words: Ginseng, Ginseng pectin, Alcohol-precipitated fraction, Bone marrow-derived dendritic cell, Lipopolysaccharide