Toll-like receptor 4-dependent activation of macrophages by polysaccharide isolated from the radix of Platycodon grandiflorum.
Platycodon grandiflorum, a traditional oriental herbal medicine, is known to have immunostimulatory and antitumor effects. PG, a polysaccharide isolated from P. grandiflorum, has been reported to activate macrophages and B cells. Here, we investigated the membrane receptor and intracellular signaling responsible for the activation of macrophages by PG. PG induced the production of nitric oxide (NO) and the mRNA expression of iNOS in RAW 264.7 cells. To investigate the membrane receptor involved in the activation of NO production, we examined the effect of PG on the production of NO in mouse peritoneal macrophages isolated from wild type C3H/HeN and functional Toll-like receptor 4 (TLR4)-deficient C3H/HeJ mice. PG induced NO production by macrophages isolated from C3H/HeN mice, but had no effect on NO production by macrophages isolated from C3H/HeJ mice. Moreover, monoclonal antibodies directed to TLR4 blocked PG-mediated induction of NO production. In addition, LBP and sCD14 was also found to be involved in the activation of NO production by PG. To further investigate, we examined the effect of PG on the activation of DNA binding of NF-kappa B, which is a downstream transcriptional regulator of TLR4. PG caused degradation of I kappa B and activation of DNA binding of NF-kappa B. In addition, TPCK, a specific NF-kappa B inhibitor, abolished PG-mediated induction of DNA binding of NF-kappa B, production of NO and mRNA expression of iNOS, demonstrating the involvement of NF-kappa B in PG-mediated macrophage activation. Taken together, these results suggest that PG-mediated induction of NO production and iNOS mRNA expression in macrophages is mediated, at least in part, by TLR4/NF-kappa B signaling pathway.
Yoon
Yeo Dae
YD
College of Pharmacy, Chungnam National University, 220 Gung-dong, Yusong-gu, Taejon 305-764, South Korea.
Han
Sang Bae
SB
Kang
Jong Soon
JS
Lee
Chang Woo
CW
Park
Song-Kyu
SK
Lee
Hyun Sun
HS
Kang
Jong Seong
JS
Kim
Hwan Mook
HM
D000209:Acute-Phase Proteins; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism; D002352:Carrier Proteins; D002450:Cell Communication / Q000276:immunology; D002460:Cell Line; D004247:DNA / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D007444:Inulin / Q000302:isolation & purification* / Q000494:pharmacology; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis / Q000097:blood; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D008262:Macrophage Activation / Q000187:drug effects* / Q000276:immunology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D008518:Medicine, East Asian Traditional; D008562:Membrane Glycoproteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D010936:Plant Extracts / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry*; D031238:Platycodon / Q000737:chemistry*; D011112:Polymyxin B / Q000494:pharmacology; D011134:Polysaccharides / Q000302:isolation & purification* / Q000494:pharmacology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D004247:DNA; D007444:Inulin; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D010936:Plant Extracts; D011112:Polymyxin B; D011134:Polysaccharides; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014108:Tosylphenylalanyl Chloromethyl Ketone; D000099231:Lipopolysaccharide-Binding Protein; C496317:Nos2 protein, mouse