Immune modulatory effects of Prunella vulgaris L. on monocytes/macrophages.
Prunella vulgaris L. (Labiatae), a popular Western and Chinese herbal medicine, has long been associated with anti-viral and anti-bacterial effects. While its anti-viral effects are attributed mainly to the inhibition of virus replication, the biological mechanisms of its anti-bacterial effects remain unknown. As a biological response modifier (BRM), the polysaccharides isolated from P. vulgaris have been shown to up-regulate the immune responses of monocytes/macrophages. However, the immune stimulatory effects seem to contradict its well-known anti-inflammatory properties. We hypothesized that the anti-microbial effects exhibited by the polysaccharides isolated from P. vulgaris encompass both anti-inflammatory and immune stimulatory effects. One of the polysaccharide fractions PV2IV markedly stimulated the production of superoxide and nitrite representing nitric oxide from murine macrophage RAW264.7 and brain macrophage BV2 cells. The amount of nitrite and superoxide produced after PV2IV stimulation was as high as that stimulated by bacterial endotoxin lipopolysaccharide (LPS) in a dose-dependent manner. In addition, PV2IV also increased cellular protein levels of inducible nitric oxide synthase (iNOS) and mRNA for tumor necrosis factor-alpha (TNFalpha). Similar to the effects of a high dose of LPS, the fraction PV2 could trigger activation-induced cell death (AICD) by stimulating caspase-3 activity and reduction of MTT uptake in monocytes/macrophages. These results may help our understanding of the molecular mechanism of P. vulgaris, which exhibited both immune stimulatory and anti-inflammatory effects against microbial invasion.
Fang
Xuya
X
Laboratory of Neurodegenerative Diseases, Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong, SAR.
Yu
Mabel Man-Shan
MM
Yuen
Wai-Hung
WH
Zee
Sze Yong
SY
Chang
Raymond Chuen-Chung
RC
D000818:Animals; D001921:Brain / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology*; D005562:Formazans / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007107:Immune System / Q000187:drug effects*; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D051379:Mice; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D031347:Prunella; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013778:Tetrazolium Salts / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D004365:Drugs, Chinese Herbal; D005562:Formazans; D009573:Nitrites; D012333:RNA, Messenger; D013778:Tetrazolium Salts; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; C079782:MTT formazan; D052247:Nitric Oxide Synthase Type II; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases