Metabolic Consequences of HAART: CYP3A and P-gp

人类免疫缺陷病毒蛋白酶抑制剂（HIV PI）作为与其他高效抗逆转录病毒疗法（HAART）的多种药物治疗的组成部分，深刻地改变了HIV感染个体的预后和生活质量。尽管如此，PI和其他HAART药物不能治愈HIV，并且病毒载量（可能具有耐药形式）从病毒储库（“突破”）的复苏仍然是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药物水平低或检测不到的时期- -可能易导致突破和耐药。变异性的一个主要来源来自HAART药物的动力学与人细胞色素P450-3A（CYP 3A）亚型（其介导HAART药物本身和许多其他化合物的代谢）和P-糖蛋白（P-gp）（一种定位于胃肠道粘膜和血脑屏障中的转运蛋白）的关系。许多重要的HAART药物是CYP 3A和/或P-gp的抑制剂和/或诱导剂，产生涉及其自身代谢的复杂和时间依赖性相互作用（即，自身诱导）以及与其他联合给药类别的药物的相互作用。HIV PI和可能的其他HAART组分对CYP 3A的失调与HIV的代谢后果有关，如脂肪代谢障碍、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组分与CYP 3A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）用作探针CYP 3A底物，以确定利托那韦在以下条件下对肝脏和胃肠道CYP 3A功能的影响：对照，利托那韦暴露前;急性利托那韦暴露（抑制）;利托那韦延长暴露期间（诱导和抑制联合）;利托那韦延长暴露后（仅诱导）。使用非索非那定作为指示底物进行P-gp调节的平行研究。B。基于免疫定量技术以及荧光探针的P-gp依赖性细胞排斥的功能测定，人腺癌细胞培养模型将评价HAART药物上调P-gp的时间过程和浓度依赖性。这一多学科的建议提供了临床和科学依据，以评估目前可用的以及实验HAART药物对人类CYP 3A和P-gp的影响。

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.