细胞因子
p38丝裂原活化蛋白激酶
TLR4型
MAPK/ERK通路
肿瘤坏死因子α
生物
免疫印迹
激酶
活力测定
MTT法
信号转导
分子生物学
药理学
化学
细胞生物学
生物化学
细胞生长
免疫学
细胞
基因
作者
Wei Wei,Haitao Xiao,Wan-Rong Bao,Dik‐Lung Ma,Chung‐Hang Leung,Xiaoqiang Han,Chun‐Hay Ko,Clara Bik‐San Lau,Chun‐Kwok Wong,Kwok‐Pui Fung,Ping‐Chung Leung,Zhaoxiang Bian,Quan‐Bin Han
标识
DOI:10.1016/j.jep.2015.12.060
摘要
Polysaccharides of Radix Astragali (Astragalus membranaceus (Fisch) Bge.; Huangqi) are able to induce cytokine production of macrophages and are considered the main active ingredient for the immune-enhancing effect of this commonly used medicinal herb.To investigate the molecular mechanism of immunomodulating activities of a reported Astragalus polysaccharide, RAP, which is a hyperbranched heteroglycan with average molecular weight of 1334kDa.The cytokine production of RAW264.7 cells were analyzed by using ELISA assays while cell viability was assessed by MTT method. Western blot analysis was used for determining protein contents of mitogen-activated protein kinases (MAPKs). In addition, the level of IL-6, iNOS, and TNF-α mRNA was determined by RT-PCR.It has been found that RAP itself did not have any cytotoxic effect on mouse mammary carcinoma 4T1 cells, but it significantly enhanced cytotoxicity of the supernatant of RAW264.7cells on 4T1 cells. Furthermore, RAP enhanced the production of NO and cytokines in RAW264.7 cells, and significantly up-regulated gene expressions of TNF-α, IL-6, iNOS. All these bioactivities were blocked by the inhibitor of TLR4 (Toll-like receptor 4), suggesting that TLR4 is a receptor of RAP and mediates its immunomodulating activity. Further analyses demonstrated that RAP rapidly activated TLR4-related MAPKs, including phosphorylated ERK, phosphorylated JNK, and phosphorylated p38, and induced translocation of NF-κB as well as degradation of IκB-α. These results are helpful to better understand the immunomodulating effects of Radix Astragali.RAP may induce cytokine production of RAW264.7 cells through TLR4-mediated activation of MAPKs and NF-κB.
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