Immunotoxicity of indirubin, a plant-based AhR ligand

描述(由申请人提供)：营养食品在美国是一个价值数十亿美元的行业。出于营销策略和解药证据的原因，东方草药被吹捧为有很大希望改善各种疾病。东方草药补充剂可能是美国公众在没有足够的疗效或安全性知识的情况下容易消费的产品的最好例子。作为一个很好的例子，从中药中分离出一种有效成分，它能抑制细胞周期蛋白依赖性激酶和糖原合成酶，从而抑制白血病细胞的增殖。这种植物的提取物可以促进解毒过程，并具有强大的抗炎特性。活性成分的生物活性被追溯到色氨酸的吲哚代谢物，该代谢物进一步代谢成两个最终产物，即靛蓝和靛玉红。现已知，蓝宝石是何首乌提取物中具有抗肿瘤和抗炎活性的成分。靛玉红与胞质芳香烃受体(AhR)高亲和力结合，激活配体-受体复合体移位到细胞核，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)样的亲和力结合到AhR上。靛玉红与AhR的高亲和力结合是一个令人震惊的观察结果，因为大多数与AhR高亲和力结合的试剂都是免疫毒性的。我们的初步数据显示，在分化的人巨噬细胞中，靛玉红是一种有效的细胞色素P1A1的诱导剂。此外，靛玉红增强了内毒素刺激的巨噬细胞的激活。此外，靛玉红还改变了吲哚胺2，3-双加氧酶(IDO)的表达，该酶尚未被描述为与AhR激活有关。吲哚红对IDO的调节很有趣，因为最近的几项研究证实，IDO-的色氨酸代谢和减少会改变T细胞的反应。结合其他初步数据，包括基因阵列分析、RT-PGR和蛋白质表达谱，蓝宝石似乎具有作为TCDD样化合物的潜力。到目前为止，关于新型植物来源的AhR配体对免疫功能的潜在不利影响的信息缺乏对免疫功能的特殊重要性，参与巨噬细胞分化和激活导致致炎事件改变的细胞和分子事件可能受到植物来源的AhR配体的影响。下面的建议验证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.