- 期刊
綠茶主要之成分EGCG對於細胞激素形成具有選擇性免疫調節效果可藉其抑制巨噬細胞中Legionella pneumophila之複製
Legionella pneumophila Replication in Macrophages Inhibited by Selective Immunomodulatory Effects on Cytokine Formation by Epigallocatechin Gallate, a Major form of Tea Catechins
摘要
EGCG(Epigallocatechin gallate)為茶之兒茶素的主要成分，它具有各種不同之生物活性，包括抗腫瘤作用以及對抗某些病房、菌之抗菌作用力(antimicrobial activity)。雖然EGCG之生物性活性已有相當廣泛的研究，可是其免疫性作用怯仍未明。在本研究中，在體外試驗(in vitro)以Legionella pneumophila感染巨噬細胞的模式，檢測EGCG對於巨噬細胞免疫功能之調節能力。在本研究結果顯示EGCG濃度低到0.5μg/ml時可以抑制巨噬細胞中L. pneumophila之生長，但是EGCG對於微生物並無直接抗菌效果。EGCG可在劑量－依賴作用方式下，藉由L. pneumophila感染巨噬細胞後，誘發巨噬細胞所生成之介白素－12(interleukin-12, IL-12)和腫瘤壞死因子－α(tumor necrosis factor-α, TNF-α)有選擇性之向上調節，以及IL-10之生成有選擇性向下調節；但是甚至在高劑量之EGCG之下並沒有改變IL-6的生成。另外也証明巨噬細胞之干擾素－γ (interferon-gamma, IFN-γ)mRNA之濃度亦會因EGCG之使用而向上調節。藉EGCG處理培養巨噬細胞anti-TNF-α和anti-INF-γ單株抗體，可以明顯地將巨噬細胞之anti-L. pneumophilac活性革除。由這樣的結果指出EGCG可以選擇性改變巨噬細胞對於L. pneumophila之免疫反應和TNF-α與INF-γ兩者的生成增加居間導致巨噬細胞對抗L. pneumophila的活性。然而，在體外試驗(in vitro)的抗L. pneumophila活性的增進，可能並非直接藉由出自EGCG增進的IL-10與IL-12生成作用的調整來媒介。因此，本研究之結果顯示EGCG對於巨噬細胞之免疫調節作用，在細菌感染中其有重要之角色。
關鍵字
無資料並列摘要
Epigallocatechin gallate (EGCg) is a major form of tea catechin and has a variety of biological activities, including antitumor as well as antimicrobial activity against some pathogens. Although the biological activities of EGCg have been extensively studied, its immunological effects are not well known. In the present study, the ability of EGCg to modulate macrophage immune functions in an in vitro Legionellα pneumophila infection model of macrophages was examined. The study showed that EGCg inhibited the growth of L. pneumophila in macrophages at a concentration as low as 0.5 mg/ml without any direct antibacterial effect on the organisms. The EGCg selectively upregulated the production of interleukin-12 (IL-12) and tumor necrosis factor alpha (TNF-α) and downregulated IL-10 production of macrophages induced by L. pneumophila infection in a dose-dependent manner, but did not alter IL-6 production even at a high dose. The upregulation of the levels of macrophage gamma interferon (IFN-γ) mRNA by EGCg was also demonstrated. Treatment of macrophage cultures with anti-TNF-α and anti-IFN-γ monoclonal antibodies markedly abolished the anti-L. pneumophila activity of macrophages induced by the EGCg treatment. These results indicate that EGCg selectively alters the immune responses of macrophages to L. pneumophila and leads to an enhanced anti-L. pneumophila activity of macrophages mediated by enhanced production of both TNF-α and IFN-γ However, the enhancement of in vitro anti-L. pneumophila activity by EGCg may not be directly mediated by IL-10 and IL-12 production modulation. Thus, the results of this study revealed the immunomodulatory effect of EGCg on macrophages, which have a critical role in infections.