Modulation of Autoimmunity by Green Tea Polyphenols

描述（由申请人提供）：中国、印度、尼日利亚等国医学中属于补充和替代医学（CAM）领域的许多草药和其他植物产品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依据持怀疑态度。这种怀疑的一个原因是，许多这些植物产品既没有在控制良好的实验系统中进行测试，也没有很好地确定其作用机制。一些研究者报道了绿茶（Camellia sinensis） （PGT）的多酚部分具有抗癌和抗炎的特性。PGT含有多酚儿茶素，在各种研究中观察到，绿茶的大部分有益作用被认为是由它产生的。我们利用大鼠佐剂诱导的关节炎（AA）模型对人类类风湿关节炎（RA）进行的中试实验表明，在诱导AA前，给Lewis大鼠口服0.8% （w/v）的PGT 2周，可显著预防该疾病。我们现在建议进一步阐述PGT的抗关节炎活性，并确定这种作用的免疫学基础。通过注射热致死结核分枝杆菌（Mtb） s.c.诱导Lewis大鼠AA。在AA中，65 kD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的决定因子（表位）180-188/177-191区的特异性T细胞是致病性的，而针对Bhsp65羧基末端决定因子（BCTD）的T细胞本质上是疾病调节的。这一信息使AA成为检验PGT抗关节炎活性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致病性和/或调节决定因素的抗原特异性T细胞反应的差异调节。这种作用可以通过PGT对抗原提呈细胞（APC）的功能或对bhsp65特异性T细胞分泌的细胞因子类型的作用来实现，例如，从促炎T辅助1 （Thl）到抗炎T辅助2 （Th2）型细胞因子的免疫偏差，或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AA过程中n类主要组织相容性复合体(MHC)/共刺激B7分子表面表达的变化（通过流式细胞术）和/或Bhsp65加工和呈递的有效性（使用表位特异性T细胞系），来确定PGT- (Aim 1)对T细胞对Bhsp65致病性和调节性决定因子的增殖和细胞因子反应的影响，以及对APC的影响；以及（目标2）通过确定PGT治疗是否与BCTD肽在预防AA或治疗持续AA方面的有益作用相辅相成或协同作用来影响临床AA。本研究的结果将有助于为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RA开发更好的治疗方法。

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.