| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 94 === Ganoderma lucidum (Fr.) Karst, a traditional medicinal fungus in China, had been shown to possess potent anti-tumor, immunomodulatory, anti-viral, anti-pathogen, hypoglycemic, and inhibiting platelet aggregation effects. Both the polysaccharides (PSG) and LZ8 protein from G. lucidum have been reported to have immunomodulatory effects. Although most studies focused on the biological effect of PSG, PSG contains 5-10％ proteins which is hard to be chemically defined. The objectives of this study were to clarify the immunomodulatory roles and related mechanisms of G. lucidum polysaccharides (PSG) and proteins (LZ8). Four different G. lucidum samples, including native LZ8 (nLZ8) extracted from the mycelia, E. coli expressed recombinant LZ8 (rLZ8), PSG, and TCA deproteinated-PSG (dePSG) were prepared for the studies. PSG was a protein-bound polysaccharide consisting of 16 - 18% polysaccharides and 4 - 8% peptides, and the ratio of proteins to polysaccharides in nLZ8 is 6:1. Western blotting reveals that PSG contained LZ8 by LZ8 monoclonal antibody analysis. Additionally, rLZ8 markedly enhanced murine splenocytes proliferation, increased IFN-γ release, and up-regulated the mRNA expression of IFN-γ and IL-2 in vitro. This activation could be further enhanced by treating with both LZ8 and dePSG. rLZ8 was further demonstrated to activate T lymphocytes, and PSG was found only to activate B lymphocytes but not T lymphocytes. On the other hand, PSG induced murine peritoneal macrophages to produce nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α), and to increase the mRNA expression of iNOS, TNF-α, IL-1β, IL-6, IL-12p40, and IL-18. Moreover, rLZ8 was found to increase the mRNA expression of IL-1β, IL-6, IL-12p40, and IL-18 by murine peritoneal macrophages but was incapable to induce NO and TNF-α production. Furthermore, peritoneal macrophages from TLR4-/- mice, but not TLR2-/- mice, were hyporesponsive in TNF-α secretion to PSG, suggesting that PSG activated macrophages through TLR4. Taken together, this study demonstrated that LZ8 and PSG played different roles on modulating immune cells through distinctive mechanisms. In conclusion, LZ8 activated T lymphocytes mainly but PSG activated macrophages and B lymphocytes. Polysaccharide and protein components were conjugated together in natural G. lucidum preparations and hereby activated the immune of the host synergistically.
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