Effects of polysaccharides from Dendrobium Officinale on the production of TNF-α by RAW264.7 cells

Aim: To study the effects of polysaccharides from dendrobium officinale (DOP) on the production of TNF-α in RAW264.7 cells and its possible mechanism. Methods: Cell proliferation was measured by MTT assay; Concentration of TNF-α in supernatants was determined by ELISA kit; Expression of TNF-α mRNA was measured by reverse transcription polymerase chain reaction (RT-PCR); Production of I-κBα protein was detected by Western blot. Results: DOP (20-160 mg·L-1) possessed the stimulation effect on macrophages proliferation without cytotoxic. The production of TNF-α was increased in a dose-dependent manner when pretreated with DOP. Compared with control group, expression of TNF-α mRNA was significantly up-regulated. DOP markedly decreased intracellular I-κBα level as demonstrated by Western blot assay. Conclusion: DOP induces TNF-α gene expression followed by TNF-α production in macrophages via decreasing intracellular I-κBα level, activating transcription factor, NF-κB, suggesting that the immunoregulation mechanism of DOP may be related to the induction of TNF-α production in macrophages.