Immunotoxicity of indirubin, a plant-based AhR ligand

描述（由申请人提供）：营养药品在美国是一个价值数十亿美元的产业。由于营销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。东方草药补充剂可能是美国公众在没有充分了解其功效或安全性的情况下轻易消费的产品的最好例子。例如，从黄蓼制备的中草药中分离出一种抑制细胞周期蛋白依赖性激酶和糖原合成酶激酶的活性成分，从而抑制白血病细胞的增殖。这种植物的提取物增强解毒过程，并具有有效的抗炎特性。活性成分的生物活性可追溯到色氨酸的吲哚代谢物，该代谢物进一步代谢为两种最终产物，靛蓝和靛红色。靛玉红是黄蓼提取物中有效的抗肿瘤和抗炎成分。靛红色与转录因子细胞质芳烃受体（AhR）结合，具有高亲和力，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，靛玉红与AhR结合具有2,3,7,8-四氯二苯并-对二恶英（TCDD）样亲和力。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高亲和力结合的药物具有免疫毒性。我们的初步数据显示，靛玉红在分化的人巨噬细胞中是一种有效的CYP1A1诱导剂。此外，吲哚红增强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，这种酶尚未被描述为与AhR激活有关。靛玉红对IDO的调节很有趣，因为最近的一些研究证实，色氨酸的代谢和IDO的减少会改变t细胞的反应。结合其他初步数据，包括基因阵列分析、RT-PGR和蛋白表达谱，靛玉红似乎具有作为一种类似于tcdd的化合物的潜力。迄今为止，关于新型植物源性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激活的细胞和分子事件导致促炎事件的改变可能受到植物源性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.