| Dendrobium plants,were widely used as precious traditional Chinese and folk medicine for centuries,also announced by the Ministry of Health as a "drug homologous food".As a rare and endangered perennial herb endemic in China,Dendrobium officinale Kimura et Migo is famous for its unparalleled medicinal value,for the top grade among Dendrobium species,and ranked "the first of the Chinese nine kinds of supernatural medicinal herbs.Basic constituents research has shown that there are several active constituents,such as polysaccharides,alkaloids,amino acids,stilbenoids and some volatile components.Modern medical studies have shown that Dendrobium officinale has various functions to nourish the stomach and promote the production of body fluid,possess immuno-stimulating activities,anti-hyperglycemic,anti-aging and anti-tumor activities.It features favorable effect on curing chronic superficial gastritis,malignant tumor,diabetes and cataract.Thus,the international medicinal plant field called it "Giant Panda among medicinal plants".Curently,Researchs on Dendrobium officinale mainly focused on germplasm identification and tissue culture,stuides for natural products such as polysaccharides focused more on extraction methods and structural analysis,however,little is known about the active components conferring therapeutic properties to these extracts,especially the relationship between the biological activity and its material basis.Therefore,using the theory and technology of modern immunology and molecular biology,profounded on cellular,molecular and gene level to study the regulation effects of Dendrobium officinale shown on immune cells,immune molecules during the immune process of impact,and explore its possible immunoregulatory mechanisms,which would be of great theoretical significance and and clinical practical value for understand the immune pharmacological effect Dendrobium officinale.To assess the impact of Dendrobium officinale on immune function,mouse macrophage cell line RAW264.7 was used as cell model.Research results found that the aqueous extract(AE),crude polysaccharide(C-DOP)and puried polysaccharide isolated from D.officinale(P-DOP)significantly increased RAW 264.7 cell proliferation rate and phagocytic activity,which indicated that DO is low cytotoxic,upregulae the production of nitric oxide(NO)and cytokines including TNF-a,interleukin(IL)-6,IL-12.Moreover,the regulation effect on the release of NO,and cytokine secretion was certified to be at transcription and translation level based on the expression of cytokine mRNA,iNOS protein with RT-PCR and Western blot technology.Furtherly,represented by crude polysaccharide,that the immunoregulatory effect is related to transcription factor,NF-?B transactivation and this may be a possible mechanism whereby this herbal medicine elicits its therapeutic effects.The distinct differences between the biological responses of cells treated with Dendrobium officinale polysaccharide compared with those treated with aqueous extract are influences on the production of TNF-a and interleukin(IL)-12.Polysaccharide-treated group augmented the secretion of TNF-?,IL-12 dose-dependently while aqueous extract treatd group decreased the production of TNF-a,IL-12 in a dose-dependent manner in regulatory way,though it uprglated production of TNF-a,IL-12 in quantity,besides,the other immune enhancement indicators of aqueous extract were much weaker than polysaccharide group,which provide further confirmation that Dendrobium officinale can enhance macrophage function may due to the therapeutic potential of Dendrobium officinale polysaccharide.Mouse spleen lymphocytes was used as cell model to access the affection of Dendrobium officinale polysaccharide.Results showed that C-DOP remarkably activiated the proliferation of spleen lymphocytes;exhibited co-mitogenic activity on ConA-stimulated T lymphocytes,dut not B cells in the presence LPS;elevated CD3+,CD4+ T lymphocyte counts as well as the CD4/CD8 ratio;increased interleukin-2(IL-2),interleukin-4(IL-4)levels in the supernents of splenocytes.These findings indicate that DOP plays an important role in cell immunity,and activation of T lymphocytes by DOP may contribute to one of its immune-enhancement functions.It is conclued that the active component of D.officinale appeared to be polysaccharide which could be used potentially for the modulation of immune response,whether for innate or specific immune response,it had a good facilitation to augment immunologic function from multiple aspects,however,further studies are necessary to identify the concrete immunoregulation mechanism. |
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