Wang Y, Mei Y, Feng D, Xu L
Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanhai, China.
Clin Exp Immunol. 2006 Sep;145(3):485-92. doi: 10.1111/j.1365-2249.2006.03137.x.
(-)-Epigallocatechin-3-gallate (EGCG) is the major active component of green tea. Increasing evidence has suggested that EGCG exhibits anti-inflammatory, anti-oxidant and immunosuppressive effects. In this study, we investigated the effect of EGCG on concanavalin A (ConA)-induced hepatitis (CIH) in mice, a model of immune-mediated liver injury in humans. We pretreated mice with EGCG before ConA injection, and then measured alanine aminotransferase (ALT) levels in plasma, inflammatory infiltration and hepatocyte apoptosis in liver. Potential therapeutic mechanisms were elucidated further by measuring several inflammatory mediators. Mice pretreated with EGCG exhibited much less increased ALT levels in plasma, reduced inflammatory infiltration and hepatocyte apoptosis in liver compared with control mice pretreated with vehicle solutions. We further investigated the mechanisms of the protective effects of EGCG. In EGCG-pretreated mice, we found abrogated tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma at both protein levels in plasma and mRNA levels in liver. At the same time, the concentration of nitrite in plasma and inducible nitric oxide synthase production in liver were both down-regulated in these mice. Moreover, IFN-inducible protein-10 and macrophage inflammatory protein-1alpha expressions in liver were decreased significantly. Therefore, EGCG is capable of regulating immune-mediated liver injury in vivo. The protective effect depended on its suppressive effect on the production of important inflammatory mediators.
（-）-表没食子儿茶素-3-没食子酸酯（EGCG）是绿茶的主要活性成分。越来越多的证据表明，EGCG具有抗炎、抗氧化和免疫抑制作用。在本研究中，我们调查了EGCG对小鼠伴刀豆球蛋白A（ConA）诱导的肝炎（CIH）的影响，CIH是人类免疫介导性肝损伤的一种模型。我们在注射ConA前用EGCG预处理小鼠，然后测量血浆中的丙氨酸转氨酶（ALT）水平、肝脏中的炎症浸润和肝细胞凋亡情况。通过检测几种炎症介质进一步阐明潜在的治疗机制。与用赋形剂溶液预处理的对照小鼠相比，用EGCG预处理的小鼠血浆中ALT水平升高幅度小得多，肝脏中的炎症浸润和肝细胞凋亡减少。我们进一步研究了EGCG保护作用的机制。在用EGCG预处理的小鼠中，我们发现血浆中蛋白质水平和肝脏中mRNA水平的肿瘤坏死因子（TNF）-α和干扰素（IFN）-γ均被消除。同时，这些小鼠血浆中的亚硝酸盐浓度和肝脏中诱导型一氧化氮合酶的产生均下调。此外，肝脏中IFN诱导蛋白-10和巨噬细胞炎性蛋白-1α的表达显著降低。因此，EGCG能够在体内调节免疫介导的肝损伤。其保护作用取决于对重要炎症介质产生的抑制作用。
