Metabolic Consequences of HAART: CYP3A and P-gp

人类免疫缺陷病毒蛋白酶抑制剂（HIV pi）作为多种药物治疗与其他高活性抗逆转录病毒疗法（HAART）的组成部分，已经深刻地改变了HIV感染者的预后和生活质量。尽管如此，PIs和其他HAART药物并不能治愈HIV，并且病毒库中病毒载量（可能具有耐药形式）的重新出现（“突破”）仍然是一个持续关注的临床问题。药代动力学变异性——特别是导致一种或多种HAART药物水平较低或无法检测的变异性——可能容易出现突破和耐药性。变异的一个主要来源是HAART药物的动力学与人类细胞色素P450-3A （CYP3A）亚型的关系，后者介导HAART药物本身和许多其他化合物的代谢，以及P-糖蛋白（P-gp），一种定位于胃肠道粘膜和血脑屏障的转运蛋白。许多重要的HAART药物是CYP3A和/或P-gp的抑制剂和/或诱导剂，产生复杂的和时间依赖性的相互作用，涉及它们自身的代谢（即，自身诱导）以及与其他共给药类药物的相互作用。HIV pi和其他HAART成分对CYP3A的失调与HIV的代谢后果有关，如脂肪营养不良、胰岛素抵抗和高脂血症。本提案利用相关的临床和分子技术，以PI利托那韦为指标化合物，提供HAART成分与CYP3A和P-gp相互作用的程度、时间过程和后果的明确数据。a .在临床研究中，咪达唑仑（静脉注射和口服）作为CYP3A底物的探针，在以下条件下测定利托那韦对肝脏和胃肠道CYP3A功能的影响：对照，在利托那韦暴露前；急性利托那韦暴露（抑制）；延长利托那韦暴露期间（联合诱导和抑制）；延长利托那韦暴露后（仅诱导）。以非索非那定为指标底物进行了P-gp调控的平行研究。B.人类腺癌细胞培养模型将基于免疫定量技术和荧光探针对P-gp依赖性细胞排除的功能分析，评估HAART药物上调P-gp的时间过程和浓度依赖性。这一多学科建议为评估目前可用的和实验性HAART药物对人CYP3A和P-gp的影响提供了临床和科学依据。

The human immunodeficiency viral protease inhibitors (HIV PIs), as a component of multiple drug therapy with other Highly Active Anti- Retroviral Therapies (HAART), have profoundly changed the prognosis and quality of life for individuals with HIV infection. Nonetheless PIs and other HAART drugs are not curative of HIV, and resurgence of viral load (possibly with resistant forms) from viral reservoirs ("breakthrough") remains a clinical problem of ongoing concern. Pharmacokinetic variability - - particularly that leading to periods of low or undetectable levels of one or more HAART drugs - - may predispose to breakthrough and resistance. One major source of variability derives from the relation of the kinetics of HAART drugs to the human Cytochrome P450-3A (CYP3A) isoforms, which mediate the metabolism of the HAART drugs themselves and many other compounds, and to P- glycoprotein (P-gp), a transport protein localized in GI tract mucosa and the blood-brain barrier. Many of the important HAART drugs are inhibitors and/or inducers of CYP3A and/or of P-gp, producing complex and time-dependent interactions involving their own metabolism (i.e.,autoinduction) as well as interactions with other coadministered classes of medications. Dysregulation of CYP3A by HIV PIs, and possibly other HAART components, has been linked to metabolic consequences of HIV such as lipodystrophy, insulin resistance, and hyperlipidemia. The present proposal utilizes related clinical and molecular techniques to provide definitive data on the extent, time course, and consequences of the interaction of HAART components with CYP3A and P-gp, using the PI ritonavir as the index compound. A. In clinical studies, midazolam (given I.V. and orally) is used as a probe CYP3A substrate to determine the effects of ritonavir on hepatic and gastrointestinal CYP3A function under the following conditions: control, prior to ritonavir exposure; with acute ritonavir exposure (inhibition); during extended ritonavir exposure (combined induction and inhibition); following extended ritonavir exposure (induction only). Parallel studies of P-gp regulation are performed using fexofenadine as the index substrate. B. A human adenocarcinoma cell culture model will evaluate the time-course and concentration-dependence of P-gp upregulation by HAART drugs, based on immunoquantitative techniques as well as functional assays of P-gp dependent cell exclusion of a fluorescent probe. This multidisciplinary proposal provides a clinical and scientific basis to assess the effects of currently available as well as experimental HAART medications on human CYP3A and P-gp.