Immunotoxicity of indirubin, a plant-based AhR ligand

描述（由申请人提供）：营养品在美国是一个数十亿美元的产业。由于市场策略和解毒证据的原因，东方草药被吹捧为对改善各种疾病有很大的希望。东方草药补充剂也许是美国公众在没有足够的功效或安全知识的情况下容易消费的产品的最好例子。作为一个恰当的例子，已经分离出了从Polygonum tinctorium制备的中药中的活性成分，其抑制细胞周期蛋白依赖性激酶和糖原合成酶激酶，从而抑制白血病细胞的增殖。这种植物的提取物可增强解毒过程，并具有强效的抗炎作用。活性成分的生物活性可追溯至色氨酸的吲哚代谢物，其进一步代谢为两种终产物，靛蓝和靛玉红。靛玉红是目前已知的活性抗肿瘤和抗炎成分在蓼提取物。靛玉红以高亲和力与细胞溶质芳烃受体（AhR）（一种转录因子）结合，并激活配体-受体复合物向细胞核的易位，导致一系列基因的表达。令人惊讶的是，靛玉红以2，3，7，8-四氯二苯并-对-二恶英（TCDD）样亲和力结合AhR。靛玉红与AhR的高亲和力结合是令人担忧的观察结果，因为以高亲和力结合AhR的大多数试剂是免疫毒性的。我们的初步数据表明，靛玉红是一个有效的诱导剂CYP 1A 1在分化的人巨噬细胞。此外，靛玉红增强LPS刺激的巨噬细胞活化。此外，靛玉红改变吲哚胺2，3-双加氧酶（IDO）的表达，IDO是一种尚未被描述为与AhR活化相关的酶。靛玉红对IDO的调节是令人感兴趣的，因为最近的几项研究证实色氨酸代谢和IDO的减少改变了T细胞应答。综合其他初步数据，包括基因阵列分析、RT-PCR和蛋白质表达谱，靛玉红似乎有可能成为一种类TCDD化合物。迄今为止，关于新的植物来源的AhR配体如靛玉红对免疫功能的潜在不利影响的信息缺乏对免疫功能的特别重要性，涉及巨噬细胞分化和活化的细胞和分子事件导致改变的促炎事件可能受到基于植物的AhR配体的影响。下面的提议检验了靛玉红是一种有效的免疫毒性化合物的假设。

DESCRIPTION (provided by applicant): Nutraceuticals are a multibillion dollar industry in the USA. For reasons of both marketing strategy and antidotal evidence, oriental herbals are touted as having great promise for ameliorating a variety of diseases. Oriental herbal supplements are perhaps the best example of products readily consumed by the American public without adequate knowledge of efficacy or safety. As a case in point, an active ingredient in Chinese herbals prepared from Polygonum tinctorium has been isolated that inhibits cyclin-dependent kinases and glycogen synthase kinase thereby inhibiting proliferation of leukemia cells. Extracts from this plant enhance detoxication processes and they have potent antiinflammatory properties. The biological activity of the active ingredient has been traced to an indole-metabolite of tryptophan that is further metabolized to two end products, indigo and indirubin. Indirubin is now known to be the active anti-neoplastic and anti-inflammatory ingredient in Polygonum tinctorium extracts. Indirubin binds to the cytosolic aryl hydrocarbon receptor (AhR), a transcription factor, with high affinity and activates the translocation of the ligand-receptor complex to the nucleus, leading to the expression of a suite of genes. Surprisingly indirubin binds to the AhR with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like affinity. High affinity binding of indirubin to the AhR is an alarming observation because most agents that bind with high affinity to the AhR are immunotoxic. Our preliminary data show that indirubin is a potent inducer of CYP1A1 in differentiated human macrophages. Furthermore indirubin potentiates LPS-stimulated macrophage activation. In addition, indirubin alters the expression of indoleamine 2, 3-dioxygenase (IDO), an enzyme not yet described as being linked to AhR activation. IDO modulation by indirubin is intriguing because several recent studies confirm that tryptophan metabolism and reduction by IDO-alters T-cell responses. Taken together with other preliminary data, including gene array analysis, RT-PGR and protein expression profiles, it appears that indirubin has the potential to act as a TCDD-like compound. To date information regarding potentially adverse effects of novel plant-derived AhR ligands like indirubin on immune function is lacking of particular importance to immune function, cellular and molecular events involved in macrophage differentiation and activation leading to altered proinflammatory events may be affected by plant-based AhR- ligands. The following proposal tests the hypothesis that indirubin is a potent immunotoxic compound.