Modulation of Autoimmunity by Green Tea Polyphenols

描述(申请人提供)：补充和替代医学(CAM)领域中的许多草药和其他植物产品等属于补充和替代医学(CAM)领域，已被发现对多种疾病有益，并受到公众的欢迎；然而，医学界对使用这些药物的科学理由持怀疑态度。这种怀疑的一个原因是，这些植物产品中的许多都没有在受控的实验系统中进行测试，也没有很好地定义它们的作用机制。一些研究人员报道，绿茶多酚部位(茶树)(PGT)具有抗癌和抗炎特性。PGT含有多酚儿茶素，被认为是绿茶在各种研究中观察到的大部分有益效果的原因。我们在人类类风湿关节炎(RA)大鼠佐剂性关节炎(AA)模型上的初步实验表明，在AA诱导之前，Lewis大鼠口服0.8%(w/v)的PGT 2wk可显著预防该病。我们现在建议进一步阐述PGT的抗关节炎活性，并确定其作用的免疫学基础。皮下注射可诱导Lewis大鼠发生AA。热致死结核分枝杆菌(Mtb)。在佐剂性关节炎中，分枝杆菌热休克蛋白(Bhsp65)是关节炎Lewis大鼠T细胞反应的焦点。针对Bhsp65决定簇(表位)180-188/177-191的T细胞是致病的，而针对Bhsp65羧基末端决定簇(BCTD)的T细胞本质上是疾病调节的。这一信息使AA成为测试PGT抗关节炎活性的免疫学基础的理想模型。我们假设，PGT对关节炎(AA)的保护/有益作用涉及对Bhsp65致病和/或调节决定因素的抗原特异性T细胞反应的不同调制。这种作用可能是通过PGT作用于抗原提呈细胞(APC)或作用于Bhsp65特异性T细胞分泌的细胞因子类型，如免疫偏离促炎T辅助细胞1(THL)到抗炎T辅助2(Th2)类细胞因子，或通过促进免疫抑制细胞因子TGF-b的分泌，或两者兼而有之。我们计划通过检测在再生障碍性贫血过程中主要组织相容性复合体(MHC)/共刺激分子B7分子的表面表达的变化和/或Bhsp65(使用表位特异性T细胞系)的加工和呈递效率的变化来确定PGT-(目的1)对T细胞针对Bhsp65的致病决定因素和调节决定因素的增殖和细胞因子反应的影响；以及(目的2)通过确定PGT治疗对于预防再生障碍性贫血或正在进行的再生障碍性贫血的BCTD肽的有益作用是相加的还是协同的，来确定对再生障碍性贫血的T细胞增殖和细胞因子反应的影响。本研究结果将有助于为PGT在自身免疫性关节炎中的应用建立可靠的科学基础，并为开发更好的RA治疗方法提供帮助。

DESCRIPTION (provided by applicant): Many herbs and other plant products in Chinese, Indian, and Nigerian medicine, etc. belonging to the realm of complementary and alternative medicine (CAM) have been found to be beneficial against a variety of diseases and are quite popular with the public; yet, there is skepticism in the medical community about the scientific rationale for the use of these agents. One reason for this skepticism is that many of these plant products have neither been tested in well-controlled experimental systems nor their mechanisms of action have been well defined. Several investigators have reported that the polyphenolic fraction of green tea (Camellia sinensis) (PGT) has anti-cancer and anti- inflammatory properties. PGT contains polyphenolic catechins, which are thought to be responsible for most of the beneficial effects of green tea observed in various studies. Our pilot experiments using the rat adjuvant-induced arthritis (AA) model for human rheumatoid arthritis (RA) have shown that oral feeding of 0.8% (w/v) PGT to Lewis rats for 2 wk before induction of AA affords significant protection from the disease. We now propose to further elaborate on the anti-arthritic activity of PGT, and determine the immunological basis of this effect. AA is inducible in Lewis rats by injection s.c. of heat-killed M. tuberculosis (Mtb). In AA, the 65 kD mycobacterial heat- shock protein (Bhsp65) is the focus of the T cell responses of arthritic Lewis rats. The T cells specific for the determinant (epitope) region 180-188/177-191 of Bhsp65 are pathogenic, whereas those directed against Bhsp65 carboxy-terminal determinants (BCTD) are disease-regulating in nature. This information makes AA an ideal model for testing the immunologic basis of the anti-arthritic activity of PGT. We hypothesize that the protective/beneficial effect of PGT against arthritis (AA) involves differential modulation of the antigen-specific T cell responses to the pathogenic and/or regulatory determinants of Bhsp65. This effect could be achieved by the action of PGT either on the function of the antigen presenting cells (APC) or on the type of cytokines secreted by Bhsp65-specific T cells, e.g., immune deviation from pro-inflammatory T helper 1 (Thl) to anti-inflammatory T helper 2 (Th2) type cytokines, or by facilitating the secretion of immunosuppressive cytokine TGF-b, or both. We plan to determine the effects of PGT- (Aim 1) on the proliferative and cytokine response of T cells against the pathogenic vs. regulatory determinants of Bhsp65, and on the APC by testing both for changes in the surface expression of class n major histocompatibility complex (MHC)/ costimulatory B7 molecules (by flow cytometry) and/or in the efficacy of processing and presentation of Bhsp65 (using epitope-specific T cell lines) during the course of AA; and (Aim 2) on clinical AA by determining whether PGT treatment is additive to, or synergistic with, the beneficial effect of BCTD peptides for the prevention of AA or for treatment of ongoing AA. The results of this study would help in establishing a reliable scientific basis for the use of PGT in autoimmune arthritis, and in developing better therapeutic approaches for RA.