Immunomodulatary Effect And Underlying Mcchanism Of Ganoderma Atrum Polysaccharide

Ganoderma atrum is known as one of the well-known foods and biopharmaceuticalmaterials with a great deal of interest. Ganoderma atrum has been used as Chinesetraditional medicine and healthful mushroom for thousands of years. Polysaccharideis regarded as the major bioactive substance in Ganoderma atrum. The present studyis designed to investigate the immunomodulatary effect of PSG-1, which is isolatedand purified from Ganoderma atrum cultivated in Ganzhou, Jiangxi province, in vitroand in vivo using cell and molecular biology technologies. This investigation focuseson macrophage and spleen lymphocyte, in order to illustrate the possible underlyingmechanism. The main research results obtained in this dissertation are concluded asfollows:1. PSG-1has potent immunomodulatory on macrophage. PSG-1may promote thephagocytosis and stimulate production of NO, cytokines (TNF-α and IL-1β) and ROSin macrophage.2. TLR4is the major receptor involved in interaction of PSG-1and macrophages.Moreover, NADPH oxidase-derived ROS acts as upstream ofPI3K/Akt/MAPK/NF-κB signaling pathway in the regulation of PSG-1stimulatedTNF-α production. Therefore, we established that a major pathway by which PSG-1exerted its effects on macrophage activation via aTLR4/ROS/PI3K/Akt/MAPK/NF-κB signal pathway3. The study demonstrated the immunomodulatory effect on spleen lymphocyte.PSG-1could enhance the proliferation of spleen T or B lymphocyte with ConA orLPS. PSG-1is also found to directly induce the proliferation of spleen T or Blymphocyte. In addition, PSG-1increased the percentage of CD3+, CD4+, CD19+lymphocyte subgroup, and CD4+/CD8+ratio. Moreover, PSG-1promoted IL-2, IFN-γ,IL-4production by T lymphocyte and Ig secretion by B lymphocyte.4. PSG-1maybe activate spleen lymphocyte via NO/cGMP, cAMP/PKA, Ca2+/PKC/Calcineurin/NFAT pathways; TLR4could be the receptor involved ininteraction of PSG-1and spleen lymphocyte.5. PSG-1protected Cy-treated mice from immunosuppression by promoting thephagocytosis and stimulating production of TNF-α, IL-1β and NO of peritonealmacrophage, which maybe relate to the activation of TLR4and MAPK, PI3K/Akt,NF-κB pathways. PSG-1induced spleen lymphocyte proliferation, enhanced splenicnatural killer cell activity and cytotoxic T lymphocyte activity, elevated CD4+Tlymphocyte counts as well as the CD4+/CD8+ratio dose-dependently in Cy-treatedmice, which maybe relate to the activation of TLR4, NO/cGMP, cAMP/PKA and Ca2+/PKC/Calcineurin pathways.6. PSG-1treatment accelerated recovery dose-dependently of peripheral red bloodcells, white blood cells and platelets in Cy-treated mice, Furthermore, PSG-1restoredthe levels of IL-2, IFN-γ, IL-10, IgA, IgM and IgG, as well as hemolysin in the sera.Finally, PSG-1can also significantly increase the total antioxidant capacity, activitiesof superoxidase dismutase, catalase and glutathione peroxidase, and decrease themalondialdehyde level in vivo.7. In tumor bearing C3H/HeN mice, PSG-1treatment promoted the phagocytosis,increased production of ROS, and activating MAPK, PI3K/Akt, NF-κB pathways inperitoneal macrophage. Moreover, PSG-1induced spleen lymphocyte proliferation,enhanced splenic natural killer cell activity, increased IL-2, TNF-α, IFN-γ, IL-12production, and elevated CD3+, CD4+, CD19+lymphocyte counts. These resultsshowed that PSG-1exerted anti-tumor effect by activating peritoneal macrophage andspleen lymphocyte. However, PSG-1showed no anti-tumor effect in tumor bearingC3H/HeJ mice, and peritoneal macrophage and spleen lymphocyte were not activatedby PSG-1, indicating that TLR4plays an important role in immunomodulatary andanti-tumor activities of PSG-1.