Modeling Neural Injury Effects of Methamphetamine Metabolism by CYP2D6 in HIV

描述(申请人提供)：尽管细胞色素P450-2D6(细胞色素P450-2D6)是参与甲基苯丙胺(冰毒)代谢的主要酶，但尚未(在我们自己的工作之外)就其在冰毒相关脑功能障碍中的作用进行研究。我们的初步数据和一个小的临床样本表明，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。与代谢正常的人相比，具有与新陈代谢减弱相对应的基因的个体引起的神经心理损伤似乎更少。这一耐人寻味的发现表明，甲基苯丙胺的代谢产物与脑损伤有关。这也表明了一种识别冰毒相关大脑问题风险增加的方法。我们小组已经描述了冰毒和艾滋病毒对大脑功能的相加负面影响。有证据表明，在HIV中，CYP2D6的活性可能会改变，因此该基因并不总是与实际的代谢活动表型相对应。此外，还有一些药物被广泛开给艾滋病毒患者，这些药物是CYP2D6的底物和抑制剂，因此如果同时服用可能会影响冰毒代谢。这些药物包括治疗抑郁症的5-羟色胺再摄取抑制剂，以及用于促进大多数CART方案的抗逆转录病毒药物利托那韦。有文献报道，服用利托那韦的HIV患者具有长期的精神活性药物效应。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背景下建立一个与冰毒暴露相关的神经损伤的自然主义体外模型。我们将使用来自胎儿组织捐赠的人类混合神经胶质细胞培养。因此，培养物可以进行基因分型。我们建议用冰毒和HIV处理培养物，并(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有关；以及(3)检查培养物暴露于临床相关的CYP2D6抑制剂(帕罗西汀和利托那韦)后，这些结果是如何影响的。我们预计，具有广泛(野生型)代谢物基因的培养物将产生最大量的冰毒代谢物，进而显示出最大程度的细胞损伤，其次是中等代谢物，然后是较差的代谢物。在初步工作中，我们已经论证了拟议实验的各个组成部分的可行性。这些发现证实了我们早期的人体研究，并提供了艾滋病毒背景下冰毒相关伤害的机制。结果可能导致开发药物干预措施，以减少脑损伤，并为携带艾滋病毒的冰毒使用者提供治疗选择的信息。

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.