Drug-induced liver injury associated with anti-retroviral therapy

描述(申请人提供)：与抗逆转录病毒治疗相关的药物不良反应已经出现，对艾滋病毒/艾滋病患者造成严重的健康并发症。这些并发症包括肝毒性，据报道，在接受利托那韦含酶抑制剂方案的患者中，约有10%的患者出现了肝毒性。利托那韦含酶抑制剂方案诱导肝损伤的机制目前尚不清楚。我们研究的长期目标是提高抗逆转录病毒治疗的安全性。本应用的目的是为了了解利托那韦类蛋白水解酶抑制剂方案引起肝毒性的机制。在最近的一系列临床试验中，在接受一线抗结核药物利福平预治疗的受试者中，含有利托那韦的蛋白酶抑制剂方案的肝脏毒性显著增强。利福平还被认为是人类孕烷X受体(PXR)的激活剂，PXR调节包括CYP3A在内的大量蛋白质的基因转录。我们概述了在双转基因人PXR和CYP3A4小鼠中，利福平预处理和利托那韦含酶抑制剂方案对肝脏的毒性。我们发现：(1)人PXR在利福平和利托那韦联合应用所致肝毒性中起关键作用；(2)利托那韦是导致利托那韦联合用药方案肝毒性的关键成分。此外，还确定了CYP3A是利托那韦生物激活的主要酶。我们还观察了利福平和利托那韦对双转基因人PXR和CyP3A小鼠肝脏内质网应激、未折叠蛋白反应和细胞凋亡的影响。我们假设PXR的激活增加了内质网负荷，并增强了细胞色素P450介导的利托那韦的生物激活，从而协同内质网应激并导致肝毒性。为了验证这一假设，提出了以下三个具体目标：(1)确定介导利福平和利托那韦相关肝毒性的代谢酶(S)；(2)阐明与利托那韦诱导的肝毒性相关的利托那韦的代谢途径(S)；以及(3)确定内质网应激在含有利托那韦的蛋白酶抑制剂方案的肝毒性中的作用。该项目的结果有望提供一个与利托那韦蛋白酶抑制剂方案相关的肝损伤的机制理解，这将被应用于开发一种基于证据的方法来改善HIV蛋白酶抑制剂的安全性。

DESCRIPTION (provided by applicant): Adverse drug reactions associated with anti-retroviral therapy have emerged that pose significant health complications to HIV/AIDS patients. These complications include hepatotoxicity, which has been reported in ~10% of patients who receive ritonavir-containing protease inhibitor regimens. The mechanism of ritonavir-containing protease inhibitor regimen-induced liver injury is currently unknown. The long-term goal of our research is to improve the safety of anti-retroviral therapy. The objective of this application is to understan the mechanism of hepatotoxicity caused by ritonavir-containing protease inhibitor regimens. In a recent series of clinical trials, the hepatotoxicity of ritonavir-containing protease inhibitor regimens was significantly enhanced in subjects who were pretreated with rifampicin, a first-line anti-tuberculosis drug. Rifampicin is also known as an activator of human pregnane X receptor (PXR) that regulates the gene transcription of a large number of proteins including CYP3A. We recapitulated the hepatotoxicity associated with rifampicin pretreatment followed by ritonavir-containing protease inhibitor regimens in double transgenic human PXR and CYP3A4 mice. We found: (1) Human PXR is critical in the hepatotoxicity associated with rifampicin pretreatment followed by ritonavir-containing protease inhibitor regimens, and (2) Ritonavir is the key component that causes the hepatotoxicity of ritonavir-containing protease inhibitor regimens. In addition, CYP3A was determined as the primary enzyme contributing to ritonavir bioactivation. We also observed endoplasmic reticulum (ER) stress, unfolded protein response, and apoptosis in livers of double transgenic human PXR and CYP3A mice pretreated with rifampicin followed by ritonavir. We hypothesize that PXR activation increases ER load and potentiates CYP450-mediated ritonavir bioactivation, which synergizes ER stress and results in hepatotoxicity. To test this hypothesis, the following three specific aims are proposed: (1) Identify the metabolic enzyme(s) mediating the hepatotoxicity associated with rifampicin pretreatment followed by ritonavir; (2) Elucidate the metabolic pathway(s) of ritonavir that are associated with ritonavir-induced hepatotoxicity; and (3) Determine the role of ER stress in the hepatotoxicity of ritonavir-containing protease inhibitor regimens. The results from this project are expected to provide a mechanistic understanding of liver injury associated with ritonavir-containing protease inhibitor regimens, which will be applied toward the development of an evidence-based approach to improve the safety profile of HIV protease inhibitors.