Drug-Induced Reactivation of Apoptosis Abrogates HIV-1 Infection

HIV-1 blocks apoptosis, programmed cell death, an innate defense of cells against viral invasion. However, apoptosis can be selectively reactivated in HIV-infected cells by chemical agents that interfere with HIV-1 gene expression. We studied two globally used medicines, the topical antifungal ciclopirox and the iron chelator deferiprone, for their effect on apoptosis in HIV-infected H9 cells and in peripheral blood mononuclear cells infected with clinical HIV-1 isolates. Both medicines activated apoptosis preferentially in HIV-infected cells, suggesting that the drugs mediate escape from the viral suppression of defensive apoptosis. In infected H9 cells, ciclopirox and deferiprone enhanced mitochondrial membrane depolarization, initiating the intrinsic pathway of apoptosis to execution, as evidenced by caspase-3 activation, poly(ADP-ribose) polymerase proteolysis, DNA degradation, and apoptotic cell morphology. In isolate-infected peripheral blood mononuclear cells, ciclopirox collapsed HIV-1 production to the limit of viral protein and RNA detection. Despite prolonged monotherapy, ciclopirox did not elicit breakthrough. No viral re-emergence was observed even 12 weeks after drug cessation, suggesting elimination of the proviral reservoir. Tests in mice predictive for cytotoxicity to human epithelia did not detect tissue damage or activation of apoptosis at a ciclopirox concentration that exceeded by orders of magnitude the concentration causing death of infected cells. We infer that ciclopirox and deferiprone act via therapeutic reclamation of apoptotic proficiency (TRAP) in HIV-infected cells and trigger their preferential elimination. Perturbations in viral protein expression suggest that the antiretroviral activity of both drugs stems from their ability to inhibit hydroxylation of cellular proteins essential for apoptosis and for viral infection, exemplified by eIF5A. Our findings identify ciclopirox and deferiprone as prototypes of selectively cytocidal antivirals that eliminate viral infection by destroying infected cells. A drug-based drug discovery program, based on these compounds, is warranted to determine the potential of such agents in clinical trials of HIV-infected patients.

人类免疫缺陷病毒1型（HIV-1）会阻断细胞凋亡——即程序性细胞死亡——这是细胞对抗病毒入侵的固有防御机制。然而，通过干预HIV-1基因表达的化学制剂，可在HIV感染的细胞中选择性重新激活细胞凋亡。本研究选取了两种全球广泛使用的药物——外用抗真菌药环吡酮（ciclopirox）与铁螯合剂去铁酮（deferiprone），探究二者对HIV感染的H9细胞，以及感染临床HIV-1分离株的外周血单个核细胞（peripheral blood mononuclear cells, PBMC）中细胞凋亡的影响。两种药物均优先在HIV感染的细胞中激活细胞凋亡，提示此类药物可介导病毒解除对防御性凋亡的抑制。在感染的H9细胞中，环吡酮与去铁酮可增强线粒体膜电位去极化，启动细胞凋亡的内源性通路直至执行阶段，这一效应可通过半胱天冬氨酸蛋白酶3（caspase-3）激活、多聚ADP核糖聚合酶[poly(ADP-ribose) polymerase, PARP]蛋白水解、DNA降解以及凋亡细胞形态学变化得到证实。在感染分离株的外周血单个核细胞中，环吡酮可将HIV-1的病毒复制水平降至病毒蛋白与RNA的检测极限以下。尽管接受了长期单药治疗，环吡酮并未引发病毒突破现象；即使在停药12周后，也未观察到病毒重现，提示该药物可清除HIV前病毒储存库。在针对人类上皮细胞毒性的小鼠预实验中，当环吡酮的浓度较感染细胞致死浓度高出数个数量级时，未检测到组织损伤或细胞凋亡激活现象。本研究推断，环吡酮与去铁酮通过在HIV感染细胞中实现治疗性恢复凋亡能力（therapeutic reclamation of apoptotic proficiency, TRAP）发挥作用，并触发感染细胞的选择性清除。病毒蛋白表达的异常提示，两种药物的抗逆转录病毒活性源于其可抑制与细胞凋亡及病毒感染密切相关的细胞蛋白的羟基化修饰，其中以真核翻译起始因子5A（eIF5A）为典型代表。本研究结果将环吡酮与去铁酮确定为一类选择性杀病毒抗病毒药物的原型，此类药物通过破坏感染细胞来清除病毒感染。基于此类化合物开发针对性的药物研发项目，以评估这类制剂在HIV感染患者临床试验中的应用潜力，是十分必要的。