Immunomodulatory Activities of Polysaccharides from Lobaria kurokawae Yoshim

SHEN Chao-qun; DONG Fang; CHEN Jian

doi:10.13982/j.mfst.1673-9078.2018.6.011

Abstract：The aim of this study was to determine the immunomodulatory activities of the neutral polysaccharide LKY-I extracted from Lobaria kurokawae Yoshim.The polysaccharide LKY-I was isolated sequentially using ultrasonic-assisted water extraction,ethanol precipitation,diethylaminoethyl cellulose (DEAE-52) ion-exchange chromatography,and gel permeation chromatography.We investigated the immunomodulatory activities using different concentrations of LKY-I.The polysaccharide LKY-I at a concentration range of 31.25-500 μg/mL had no obvious in vitro toxic effects in macrophages (RAW 264.7).The phagocytic ability of macrophages treated with 500 μg/mL LKY-I was higher than that of the macrophages in the positive control group treated with lipopolysaccharide (LPS);absorbance,1.39.In addition,LKY-I induced the production of nitric oxide (NO) up to 55.42 ± 1.79 μM.Compared with the control group,the LKY-I group showed an increase in the secretion of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) by 102.3％ and 289.5％,respectively.Furthermore,LKY-I at a dose of 125-500 μg/mL showed a marked increase in the mRNA expression levels of inducible nitric oxide synthase (iNOS),TNF-α,and interleukin 6 (IL-6).LKY-I in combination with LPS or concanavalin A (ConA) significantly promoted the proliferation of lymphocytes.Thus,our findings suggest that LKY-I has immunomodulatory effects and can be used as a health-promoting food supplement.