TY - JOUR
T1 - TLR-4 may mediate signaling pathways of Astragalus polysaccharide RAP induced cytokine expression of RAW264.7 cells
AU - Wei, Wei
AU - Xiao, Hai-Tao
AU - Bao, Wan-Rong
AU - Ma, Dik-Lung
AU - Leung, Chung-Hang
AU - Han, Xiao-Qiang
AU - Ko, Chun-Hay
AU - Lau, Clara Bik-San
AU - Wong, Chun-Kwok
AU - Fung, Kwok-Pui
AU - Leung, Ping-Chung
AU - Bian, Zhao-Xiang
AU - Han, Quan-Bin
N1 - Funding Information:
This study was supported by HKSAR Innovation and Technology Fund (ITF), Tier 3, ITS/311/09 ; HKSAR Health Medical Research Fund , No. 11122531 ; and Hong Kong Baptist University (RC-start up grant), No. 38-40-025.
PY - 2016/2
Y1 - 2016/2
N2 - Ethnopharmacological relevance 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. Aim of study To investigate the molecular mechanism of immunomodulating activities of a reported Astragalus polysaccharide, RAP, which is a hyperbranched heteroglycan with average molecular weight of 1334 kDa. Materials and methods 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. Results 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. Conclusions RAP may induce cytokine production of RAW264.7 cells through TLR4-mediated activation of MAPKs and NF-κB.
AB - Ethnopharmacological relevance 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. Aim of study To investigate the molecular mechanism of immunomodulating activities of a reported Astragalus polysaccharide, RAP, which is a hyperbranched heteroglycan with average molecular weight of 1334 kDa. Materials and methods 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. Results 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. Conclusions RAP may induce cytokine production of RAW264.7 cells through TLR4-mediated activation of MAPKs and NF-κB.
KW - Astragalus polysaccharides
KW - RAW264.7 macrophages
KW - MAPKs
KW - NF-κB
UR - http://www.scopus.com/inward/record.url?scp=84952935901&partnerID=8YFLogxK
U2 - 10.1016/j.jep.2015.12.060
DO - 10.1016/j.jep.2015.12.060
M3 - Journal article
C2 - 26743224
AN - SCOPUS:84952935901
SN - 0378-8741
VL - 179
SP - 243
EP - 252
JO - Journal of Ethnopharmacology
JF - Journal of Ethnopharmacology
ER -