摘要:靈芝具多種的藥理功能,在亞洲已有相當久遠的藥用歷史。現今靈芝的應用涵蓋了冠狀動脈心臟病、動脈硬化症、肝炎、關節炎、腎炎、支氣管炎、氣喘、高血壓、癌症、胃潰瘍等疾病的治療。靈芝的多種組成成分包括多醣、萜類 (terpenoid)、凝集素 (lectin)、腺甘 (adenosine)和蛋白質都被認為有抗發炎、抗腫瘤、抗菌、抑制血小板凝集和調節免疫功能等的活性。
台灣紫芝 (Ganoderma formosanum) 是原生於台灣的一種靈芝,雖然已被發現有二十年之久,但其代謝產物的藥用研究仍十分稀少。在我們初步的研究中,建立了深層液態發酵系統來培養紫芝菌絲體,並生產胞外多醣體。發酵液經過膠體過濾層析後,純化得到 PS-F2 (polysaccharide fraction 2) 多醣,其單體組成包含了甘露糖、半乳糖及葡萄糖。結果顯示 PS-F2 能刺激小鼠巨噬細胞 RAW264.7 產生腫瘤壞死因子-α (TNF-α) 和一氧化氮 (NO),並增強其吞噬能力。刺激 TNF-α 的產生需要活化絲裂原活化蛋白激酶 (mitogen-activated protein kinases) 和 NF-κB。另外 PS-F2 亦可刺激小鼠由骨髓分化之樹突細胞分泌 TNF-α 及 IL-12 p40。在體外培養脾臟細胞培養則可刺激脾臟細胞增生及活化脾臟內 T 和 B 淋巴球。活體試驗中,給予 PS-F2 可使罹癌小鼠展現顯著抗腫瘤能力。
這些初步結果指出台灣紫芝胞外多醣 PS-F2 能調節多種免疫細胞活性,未來具有開發成為免疫調節保健食品及藥物應用之潛力。在這個計畫中,我們欲進一步了解台灣紫芝多醣 PS-F2 的免疫調節及抗腫瘤機制,並建立起 PS-F2 免疫調節的動物模式。本計畫具體目標包括:(1) 探討 PS-F2 活化巨噬細胞的分子機制;(2) 探討 PS-F2 對於 T及B 淋巴球的刺激作用;(3) 探討 PS-F2 作為免疫佐劑的潛力;(4) 探討 PS-F2 對於過敏性氣喘的免疫調節效果;(5) 研究 PS-F2 的抗腫瘤作用機制。
Abstract: The fungus of Ganoderma, called “Ling-Zhi” or “Reishi,” has been used as traditional medicine in Asia for centuries and has been shown to exhibit various pharmacological functions. Modern uses of Ganoderma include treatment of coronary heart diseases, arteriosclerosis, hepatitis, arthritis, nephritis, bronchitis, asthma, hypertension, cancer and gastric ulcer. Ganoderma-derived compounds (e.g. polysaccharides, terpenoids, lectins, adenosine and proteins) have been described to have functions of anti-inflammation, anti-tumor, anti-bacterial activity, anti-platelet aggregation and immunomodulation. Ganoderma formosanum is a native species isolated in Taiwan. Although it was discovered more than two decades ago, there has been very little study regarding the pharmacological activities of its metabolites. In our preliminary studies, we have established a submerged fermentation system for the cultivation of G. formosanum mycelia, and polysaccharides were recovered from the culture broth. After gel filtration chromatography, a major polysaccharide fraction 2 (PS-F2) was purified, which was mainly composed of mannose, galactose, and glucose. We found that PS-F2 stimulated mouse RAW264.7 macrophage cells to produce TNF-α and nitric oxide (NO), and to enhance the phagocytic activity of macrophages. The stimulation of TNF-α production required the activation of MAP kiases and NF-κB pathways. PS-F2 also stimulated TNF-α and IL-12/p40 production in bone marrow-derived dendritic cells (BMDCs). In the ex vivo splenocyte culture, PS-F2 stimulated splenocyte proliferation and the activation of splenic T and B lymphocytes. In vivo, PS-F2 administration in tumor-bearing mice showed significant anti-tumor effects. These preliminary results indicated that G. formosanum polysaccharides PS-F2 has immunomodulating activities for various immune cells and has the potential to be used as an immunomodulating agent in functional food or medicinal applications.
In this proposal, we would like to further elucidate the mechanisms of immunomodulating and anti-tumor effects exerted by G. formosanum PS-F2, and also establish animal models to investigate the potential of using PS-F2 as an immunomodulator in vivo. The Specific Aims of this proposed project are: (1) To study the molecular mechanisms of immune cell activation by PS-F2, (2) To investigate the effect of PS-F2 stimulation on T and B lymphocytes, (3) To study the potential use of PS-F2 as an adjuvant for immunization, (4) To determine the immunomodulating effect of PS-F2 on allergic asthma, and (5) To study the mechanisms of anti-tumor effect of PS-F2.