Modeling Neural Injury Effects of Methamphetamine Metabolism by CYP2D6 in HIV

描述（由申请人提供）：尽管细胞色素P450-2D6 （CYP2D6）是参与甲基苯丙胺（冰毒）代谢的主要酶，但它在冰毒相关脑功能障碍中的作用尚未被研究（在我们自己的工作之外）。我们对一个小临床样本的初步数据表明，编码CYP2D6活性的遗传差异与冰毒使用者对神经认知问题的不同易感性有关。代谢减少基因型的个体似乎比代谢正常的个体产生更少的神经心理损伤。这一有趣的发现暗示了甲基苯丙胺在脑损伤中的代谢产物。它还提出了一种方法来识别那些与冰毒有关的大脑问题风险增加的人。我们的研究小组已经描述了冰毒和艾滋病毒对大脑功能的负面影响。有证据表明，CYP2D6活性可能在HIV中发生改变，因此基因型并不总是与实际的代谢活性表型相对应。此外，HIV患者广泛使用的一些药物是CYP2D6的底物和抑制剂，因此如果同时服用，可能会影响冰毒的代谢。这些药物包括治疗抑郁症的血清素再摄取抑制剂，以及用于促进大多数cART疗法的抗逆转录病毒药物利托那韦（ritonavir）。文献中有关于服用利托那韦的HIV患者的精神活性药物作用延长的报道。为了了解CYP2D6活性差异可能导致冰毒相关脑功能障碍的机制，我们建议在HIV背景下建立冰毒暴露相关神经损伤的自然体外模型。我们将使用来自胎儿组织捐赠的人类混合神经胶质培养物。因此，培养物可以进行基因分型。我们建议用冰毒和HIV来处理培养物，并且(1)测量代谢物的形成；(2)确定CYP2D6活性/代谢物数量是否与细胞损伤程度相关；(3)检查将培养物暴露于临床相关的CYP2D6抑制剂（帕罗西汀和利托那韦）对这些结果的影响。我们预计，具有广泛（野生型）代谢物基因型的培养将产生最多数量的甲基苯丙胺代谢物，进而显示出最大程度的细胞损伤，其次是中间代谢物，然后是差代谢物。在初步工作中，我们已经证明了所提出的实验的各个组成部分的可行性。研究结果证实了我们早期的人体研究，并提供了一种与冰毒相关的HIV损伤机制。结果可能会导致药物干预的发展，以减少脑损伤，并为艾滋病毒吸毒者的治疗选择提供信息。

DESCRIPTION (provided by applicant): Despite being the primary enzyme involved in methamphetamine (meth) metabolism, cytochrome P450-2D6 (CYP2D6) has not been studied (outside of our own work) with regard to its role in meth-related brain dysfunction. Our preliminary data with a small clinical sample suggest that genetic differences coding for the activity of CYP2D6 are associated with differential vulnerability to neurocognitive problems in meth users. Individuals with genotypes corresponding to diminished metabolism seem to incur less neuropsychological impairment than those with normal metabolism. This intriguing finding implicates the metabolic products of methamphetamine in brain injury. It also suggests a way to identify individuals are at increased risk of meth-related brain problems. Our group has described additive negative effects of meth and HIV on brain function. There is evidence that CYP2D6 activity may be altered in HIV, such that the genotype does not always correspond with the actual metabolic activity phenotype. Additionally, there are medications that are widely prescribed to HIV patients that are substrates and inhibitors of CYP2D6 and thus may affect meth metabolism if taken concurrently. These include serotonin reuptake inhibitors for depression as well as the antiretroviral ritonavir, which is used to boost a majority of cART regimens. There are reports in the literature of prolonged psychoactive drug effects in HIV patients taking ritonavir. To understand the mechanisms by which differences in CYP2D6 activity may contribute to meth-related brain dysfunction, we propose to generate a naturalistic in vitro model of neural injury associated with meth exposure in the context of HIV. We will use human mixed neuroglial cultures derived from fetal tissue donation. As such, the cultures can be genotyped. We propose to treat the cultures with meth and HIV, and (1) measure metabolite formation; (2) determine whether CYP2D6 activity / metabolite quantities are related to amount of cellular injury; and (3) examine how these results are affected by exposure of the cultures to clinically relevant CYP2D6 inhibitors (paroxetine and ritonavir). We expect that cultures with extensive (wildtype) metabolizer genotypes will generate the largest quantities of meth metabolites and will in turn show the greatest degree of cellular injury, followed by intermediate and then poor metabolizers. In preliminary work, we have demonstrated the feasibility of the various components of the proposed experiments. Findings stand to confirm our early human studies and provide a mechanism of meth-related injury in the context of HIV. Results could lead to the development of pharmacologic interventions to reduce brain injury as well as inform treatment choices for meth users with HIV.