Peptide nucleic acids as epigenetic inhibitors of HIV-1

Summary The advent of highly active antiretroviral therapy (HAART) was once perceived to have transformed deadly HIV/AIDS into a treatable, chronic infectious disease. However, mounting evidence now suggests that the prevalence of multi-drug resistant HIV (MDR-HIV) infection is steadily rising among newly infected individuals in the HAART-experienced countries, raising a concern for a future outbreak of MDR-HIV/AIDS. Our global fight against AIDS must include sustained effort to search and discover a new therapeutic modality for HIV infection. Of plausible viral targets explored to date, HIV gene-targeting approach has not yet seen a considerable success in vivo. The pursuit of anti-HIV gene intervention should include the identification of critical gene targets as well as the optimization of biomolecules that can effectively interact with the intended targets. Using unmodified peptide nucleic acids (PNA) as a biomolecular tool, we discovered a potentially critical HIV gene segment within gag-pol encoding gene. Antisense PNA targeting this specific region effectively disrupted a translation of HIV gag-pol mRNA, abolishing the virion production from chronically HIV-infected cells. This exemplifies the possibility that epigenic HIV inhibitors may be developed in the coming years, if emerging novel technologies permit sufficient and stable in vivo delivery of PNA or other similarly effective biomolecules.     

Peptide nucleic acids as epigenetic inhibitors of HIV-1

Summary The advent of highly active antiretroviral therapy (HAART) was once perceived to have transformed deadly HIV/AIDS into a treatable, chronic infectious disease. However, mounting evidence now suggests that the prevalence of multi-drug resistant HIV (MDR-HIV) infection is steadily rising among newly infected individuals in the HAART-experienced countries, raising a concern for a future outbreak of MDR-HIV/AIDS. Our global fight against AIDS must include sustained effort to search and discover a new therapeutic modality for HIV infection. Of plausible viral targets explored to date, HIV gene-targeting approach has not yet seen a considerable success in vivo. The pursuit of anti-HIV gene intervention should include the identification of critical gene targets as well as the optimization of biomolecules that can effectively interact with the intended targets. Using unmodified peptide nucleic acids (PNA) as a biomolecular tool, we discovered a potentially critical HIV gene segment within gag-pol encoding gene. Antisense PNA targeting this specific region effectively disrupted a translation of HIV gag-pol mRNA, abolishing the virion production from chronically HIV-infected cells. This exemplifies the possibility that epigenic HIV inhibitors may be developed in the coming years, if emerging novel technologies permit sufficient and stable in vivo delivery of PNA or other similarly effective biomolecules.     

HPTN 071 (PopART): A Cluster-Randomized Trial of the Population Impact of an HIV Combination Prevention Intervention Including Universal Testing and Treatment: Mathematical Model

Background

The HPTN 052 trial confirmed that antiretroviral therapy (ART) can nearly eliminate HIV transmission from successfully treated HIV-infected individuals within couples. Here, we present the mathematical modeling used to inform the design and monitoring of a new trial aiming to test whether widespread provision of ART is feasible and can substantially reduce population-level HIV incidence.

Methods and Findings

The HPTN 071 (PopART) trial is a three-arm cluster-randomized trial of 21 large population clusters in Zambia and South Africa, starting in 2013. A combination prevention package including home-based voluntary testing and counseling, and ART for HIV positive individuals, will be delivered in arms A and B, with ART offered universally in arm A and according to national guidelines in arm B. Arm C will be the control arm. The primary endpoint is the cumulative three-year HIV incidence.We developed a mathematical model of heterosexual HIV transmission, informed by recent data on HIV-1 natural history. We focused on realistically modeling the intervention package. Parameters were calibrated to data previously collected in these communities and national surveillance data.We predict that, if targets are reached, HIV incidence over three years will drop by >60% in arm A and >25% in arm B, relative to arm C. The considerable uncertainty in the predicted reduction in incidence justifies the need for a trial. The main drivers of this uncertainty are possible community-level behavioral changes associated with the intervention, uptake of testing and treatment, as well as ART retention and adherence.

Conclusions

The HPTN 071 (PopART) trial intervention could reduce HIV population-level incidence by >60% over three years. This intervention could serve as a paradigm for national or supra-national implementation. Our analysis highlights the role mathematical modeling can play in trial development and monitoring, and more widely in evaluating the impact of treatment as prevention.     

HDAC inhibitors in HIV

Combination antiretroviral therapy (cART) has led to a very substantial reduction in morbidity and mortality in HIV-infected patients; however, cART alone is unable to cure HIV and therapy is lifelong. Therefore, a new strategy to cure HIV is urgently needed. There is now a concerted effort from scientists, clinicians and funding agencies to identify ways to achieve either a functional cure (long-term control of HIV in the absence of cART) or a sterilizing cure (elimination of all HIV-infected cells). Multiple strategies aiming at achieving a cure for HIV are currently being investigated, including both pharmacotherapy and gene therapy. In this review, we will review the rationale as well as in vitro and clinical trial data that support the role of histone deacetylase inhibitors as one approach to cure HIV.     

Gene therapy strategies for intracranial tumours: glioma and pituitary adenomas

Intracranial tumours such as brain gliomas and pituitary adenomas pose a challenging area of research for the development of gene therapy strategies, both from the point of view of the severity of the diseases, to the physiological implication of gene delivery into the central nervous system and pituitary gland. On the one hand, brain gliomas are very malignant tumours, with a life expectancy of six months to a year at the most after the time of diagnosis, in spite of advances in treatment modalities which involve chemotherapy, surgery and radiotherapy. Gene therapy for these tumours is therefore a very attractive therapeutic modality which due to the severity of the disease is already in clinical trials. On the other hand, pituitary tumours are usually benign, and in most cases, treatment is successful. Nevertheless, there are some instances, especially with the macroadenomas and some invasive tumours in which treatment fails. Gene therapy strategies for these adenomas therefore needs to progress substantially in terms of safety, adverse side effects and physiological impact on the normal pituitary gland before clinical implementation. In this paper, we will review gene delivery systems both viral and non-viral and several therapeutic strategies which could be implemented for the treatment of these diseases. These include cytotoxic approaches both conditional and direct, immune-stimulatory strategies, anti-angiogenic strategies and approaches which harness pro-apoptotic and tumour suppressor gene targets. We will also review the models which are currently available in which these gene therapy strategies can be tested experimentally. This new therapeutic modality holds enormous promise, but we still need substantial improvements both from the delivery, efficacy and safety stand points before it can become a clinical reality.     

The status of gene vectors for the treatment of diabetes

Diabetes mellitus type 1 (DM1) represents one of the most obvious targets for successful treatment by gene transfer. The disease provides targets and methods for therapy that include suppression of autoimmunity, restoration of insulin responsiveness, functional replacement of pancreatic islets, and correction of vascular and nerve damage associated with prolonged hyperglycemia. The pathogenesis of DM1 is well understood and gene sequences are known that would support these various approaches for genetic intervention. However, a key limitation at present is the availability of efficient and reliable methods for delivery and sustained expression of the transferred DNA. Most genetic vectors are derived from viruses, and recent improvements in adenovirus-derived, lentivirus-derived, and adeno-associated virus-derived vectors suggest that these will have successful application to diabetes in the future.     

Peptide nucleic acids as epigenetic inhibitors of HIV-1

The advent of highly active antiretroviral therapy (HAART) was once perceived to havetransformed deadly HIV/AIDS into a treatable, chronic infectious disease. However, mountingevidence now suggests that the prevalence of multi-drug resistant HIV (MDR-HIV) infection issteadily rising among newly infected individuals in the HAART-experienced countries, raising aconcern for a future outbreak of MDR-HIV/AIDS. Our global fight against AIDS must include sustainedeffort to search and discover a new therapeutic modality for HIV infection. Of plausible viraltargets explored to date, HIV gene-targeting approach has not yet seen a considerable success invivo. The pursuit of anti-HIV gene intervention should include the identification of critical genetargets as well as the optimization of biomolecules that can effectively interact with theintended targets. Using unmodified peptide nucleic acids (PNA) as a biomolecular tool, we discovereda potentially critical HIV gene segment within gag-polencoding gene. Antisense PNA targetingthis specific region effectively disrupted a translation of HIV gag-polmRNA, abolishing thevirion production from chronically HIV-infected cells. This exemplifies the possibility that epigenic HIV inhibitors may be developed in the coming years, if emerging novel technologies permitsufficient and stable in vivo delivery of PNA or other similarly effective biomolecules.     

Genetic therapies against HIV

Highly active antiretroviral therapy prolongs the life of HIV-infected individuals, but it requires lifelong treatment and results in cumulative toxicities and viral-escape mutants. Gene therapy offers the promise of preventing progressive HIV infection by sustained interference with viral replication in the absence of chronic chemotherapy. Gene-targeting strategies are being developed with RNA-based agents, such as ribozymes, antisense, RNA aptamers and small interfering RNA, and protein-based agents, such as the mutant HIV Rev protein M10, fusion inhibitors and zinc-finger nucleases. Recent advances in T-cell-based strategies include gene-modified HIV-resistant T cells, lentiviral gene delivery, CD8(+) T cells, T bodies and engineered T-cell receptors. HIV-resistant hematopoietic stem cells have the potential to protect all cell types susceptible to HIV infection. The emergence of viral resistance can be addressed by therapies that use combinations of genetic agents and that inhibit both viral and host targets. Many of these strategies are being tested in ongoing and planned clinical trials.     

Targeted gene-delivery strategies for angiostatic cancer treatment

Gene therapy is one of the promising strategies in cancer treatment. Recent studies identified molecular targets on angiogenically activated endothelial cells that can be used to deliver gene-transfer vehicles to the tumor site specifically. Furthermore, non-viral vehicles are emerging as an alternative for traditional viral gene-therapy approaches. Here, we describe how viral and non-viral gene-transfer vehicles have been and can be modified to target tumor endothelial cells for anti-angiogenesis gene therapy. Improving the specificity and safety of existing gene-therapy vehicles will make angiogenesis-targeted cancer gene therapy a valuable tool in the clinical setting.     

Current strategies for the development of peptide-based anti-cancer therapeutics.

The completion of the human genome sequence and the development of new techniques, which allow the visualisation of comprehensive gene expression patterns, has led to the identification of a large number of gene products differentially expressed in tumours and corresponding normal tissues. The task at hand is the sorting of these genes into correlative and causative ones. Correlative genes are merely changed as a consequence of transformation and have no decisive effects upon transformation. In contrast, causative genes play a direct role in the process of cellular transformation and the maintenance of the transformed state, which can be exploited for therapeutic purposes. Oncogenes and tumour suppressor genes are prime targets for the development of new inhibitors and gene therapeutic strategies. However, many target oncogene products do not exhibit enzymatic activity that can be inhibited by conventional small molecular weight compounds. They exert their functions through regulated protein-protein or protein-DNA interactions and might require other compounds for efficient interference with such functions. Peptides are emerging as a novel class of drugs for cancer therapy, which could fulfil these tasks. Peptide therapy aims at the specific inhibition of inappropriately activated oncogenes. This review will focus on the selection procedures, which can be employed to identify useful peptides for the treatment of cancer. Before peptide-based therapeutics can become useful, it will be necessary to increase their stability by modifications or the use of scaffolds. Additionally, various delivery methods including liposomes and particularly the use of protein transduction domains (PTDs) have to be explored. These strategies will yield highly specific and more effective peptides and improve the potential of peptide-based anti-cancer therapeutics.     

Dendritic cells as a conduit to improve HIV vaccines

Many potential HIV vaccine strategies are being explored in both animal model and human settings. The success of any vaccine relies on relevant antigenic determinants being presented to the immune system for the activation of broad and long-lasting immunity. Effective immunity against HIV infection will likely require both the cellular and humoral arms of the immune system, where HIV-specific killer cells eradicate infected targets and neutralizing antibody responses contribute by preventing the initial infection of host cells. As the most potent antigen presenting cell of the immune system, the dendritic cell (DC) orchestrates the activation of adaptive immune responses as well as contributing to the early innate responses to a pathogen, which may also aid in the initial control of infection. It follows therefore, that the efficiency of a vaccine antigen would be greatly enhanced if targeted to the appropriate DCs to ensure optimal presentation to and subsequently activation of the immune system. This review will discuss (i) the current status of DC biology, covering distinct DC subsets and stages of activation and how these influence the types of immune responses that are induced, (ii) how DCs can be exploited to improve the efficacy of HIV vaccine strategies currently under investigation, (iii) what has been learned from in vivo model systems using DCs, and (iv) future considerations to advance HIV vaccinology.     

Gene therapy for HIV infection: what does it need to make it work?

The efficacy of antiviral drug therapy for HIV infection is limited by toxicity and viral resistance. Thus, alternative therapies need to be explored. Several gene therapeutic strategies for HIV infection have been developed, but in clinical testing therapeutically effective levels of the transgene product were not achieved. This review focuses on the determinants of therapeutic efficacy and discusses the potential and also the limits of current gene therapy approaches for HIV infection.     

Unraveling the epigenetic code of cancer for therapy

Alterations in the genome and the epigenome are common in most cancers. Changes in epigenetic signatures, including aberrant DNA methylation and histone deacetylation, are among the most prevalent modifications in cancer and lead to dramatic changes in gene expression patterns. Because DNA methylation and histone deacetylation are reversible processes, they have become attractive as targets for cancer epigenetic therapy, both as single agents and as 'enhancing' agents for other treatment strategies. In this review we discuss our current view of the mammalian epigenome, this view has changed over the years because of the availability of novel technologies. We further demonstrate how the profound understanding of epigenetic alterations in cancer will help develop novel strategies for epigenetic therapies.     

人类人工染色体构建及其作为基因治疗载体的价值

人类人工染色体(HAC)作为基因治疗载体将解决基因治疗存在的一些关键问题。本文探讨了在不完全了解着丝粒、复制起始点、端粒等人类染色体基本功能单位的情况下构建HAC的三种策略。利用染色体基本功能单位在细胞内构建成功的第一代HAC,解决了HAC构建的一些难题,同时也带来了某些新的问题。HAC作为基因治疗载体具有很多优势,但第一代HAC离它作为基因治疗载体还相距很远。为此,作者正在进行解决这些问题的尝试。     

Integration of Social,Cultural, and Biomedical Strategies into an Existing Couple-Based Behavioral HIV/STI Prevention Intervention: Voices of Latino Male Couples

Introduction

Successful HIV prevention and treatment requires evidence-based approaches that combine biomedical strategies with behavioral interventions that are socially and culturally appropriate for the population or community being prioritized. Although there has been a push for a combination approach, how best to integrate different strategies into existing behavioral HIV prevention interventions remains unclear. The need to develop effective combination approaches is of particular importance for men who have sex with men (MSM), who face a disproportionately high risk of HIV acquisition.

Materials and Methods

We collaborated with Latino male couples and providers to adapt Connect ‘n Unite, an evidence-based intervention for Black male couples, for Latino male couples. We conducted a series of three focus groups, each with two cohorts of couples, and one focus group with providers. A purposive stratified sample of 20 couples (N = 40, divided into two cohorts) and 10 providers provided insights into how to adapt and integrate social, cultural, and biomedical approaches in a couples-based HIV/AIDS behavioral intervention.

Results

The majority (N = 37) of the couple participants had no prior knowledge of the following new biomedical strategies: non-occupational post-exposure prophylaxis (nPEP); pre-exposure prophylaxis (PrEP); and HIV self-testing kits. After they were introduced to these biomedical interventions, all participants expressed a need for information and empowerment through knowledge and awareness of these interventions. In particular, participants suggested that we provide PrEP and HIV self-testing kits by the middle or end of the intervention. Providers suggested a need to address behavioral, social and structural issues, such as language barriers; and the promotion of client-centered approaches to increase access to, adaptation of, and adherence to biomedical strategies. Corroborating what couple participants suggested, providers agreed that biomedical strategies should be offered after providing information about these tools. Regarding culturally sensitive and responsive approaches, participants identified stigma and discrimination associated with HIV and sexual identity as barriers to care, language barriers and documentation status as further barriers to care, the couple-based approach as ideal to health promotion, and the need to include family topics in the intervention.

Discussion

We successfully adapted an evidence-based behavioral HIV prevention intervention for Latino male couples. The adapted intervention, called Conectando Latinos en Pareja, integrates social, cultural, behavioral and biomedical strategies to address the HIV epidemic among Latino MSM. The study highlights the promise regarding the feasibility of implementing a combination approach to HIV prevention in this population.     

Gene therapy of T helper cells in HIV infection: Mathematical model of the criteria for clinical effect

The paper presents a mathematical analysis of the criteria for gene therapy of T helper cells to have a clinical effect on HIV infection. The analysis indicates that for such a therapy to be successful, it must protect the transduced cells against HIV-induced death. The transduced cells will not survive as a population if the gene therapy only blocks the spread of virus from transduced cells that become infected. The analysis also suggests that the degree of protection against disease-related cell death provided by the gene therapy is more important than the fraction of cells that is initially transduced. If only a small fraction of the cells can be transduced, transduction of T helper cells and transduction of haematopoietic progenitor cells will result in the same steady-state level of transduced T helper cells. For gene therapy to be efficient against HIV infection, our analysis suggests that a 100% protection against viral escape must be obtained. The study also suggests that a gene therapy against HIV infection should be designed to give the transduced cells a partial but not necessarily total protection against HIV-induced cell death, and to avoid the production of viral mutants insensitive to the gene therapy.     

人免疫缺陷病毒/艾滋病细胞免疫疫苗研究进展

由于人免疫缺陷病毒(HIV)具有变异快、亚型多、攻击免疫系统等特殊的生物学特点,HIV/艾滋病疫苗至今尚未研制成功。20多年来,艾滋病疫苗研究主要采用中和抗体为主和细胞免疫为主等两种策略,然而目前仍没有实质性突破。诱发广谱有效的强CD8+T细胞反应是研制有效HIV疫苗的重要策略。以次要保护性抗原为靶抗原、优化目的基因表达、多抗原联合使用策略,为研究HIV细胞免疫疫苗引入了新的思路。综合分析这些进展,对于重新思考艾滋病疫苗的研究策略可能会有所帮助。     

Effectiveness and cost effectiveness of expanding harm reduction and antiretroviral therapy in a mixed HIV epidemic: a modeling analysis for Ukraine

Background

Injection drug use (IDU) and heterosexual virus transmission both contribute to the growing mixed HIV epidemics in Eastern Europe and Central Asia. In Ukraine—chosen in this study as a representative country—IDU-related risk behaviors cause half of new infections, but few injection drug users (IDUs) receive methadone substitution therapy. Only 10% of eligible individuals receive antiretroviral therapy (ART). The appropriate resource allocation between these programs has not been studied. We estimated the effectiveness and cost-effectiveness of strategies for expanding methadone substitution therapy programs and ART in mixed HIV epidemics, using Ukraine as a case study.

Methods and Findings

We developed a dynamic compartmental model of the HIV epidemic in a population of non-IDUs, IDUs using opiates, and IDUs on methadone substitution therapy, stratified by HIV status, and populated it with data from the Ukraine. We considered interventions expanding methadone substitution therapy, increasing access to ART, or both. We measured health care costs, quality-adjusted life years (QALYs), HIV prevalence, infections averted, and incremental cost-effectiveness. Without incremental interventions, HIV prevalence reached 67.2% (IDUs) and 0.88% (non-IDUs) after 20 years. Offering methadone substitution therapy to 25% of IDUs reduced prevalence most effectively (to 53.1% IDUs, 0.80% non-IDUs), and was most cost-effective, averting 4,700 infections and adding 76,000 QALYs compared with no intervention at US$530/QALY gained. Expanding both ART (80% coverage of those eligible for ART according to WHO criteria) and methadone substitution therapy (25% coverage) was the next most cost-effective strategy, adding 105,000 QALYs at US$1,120/QALY gained versus the methadone substitution therapy-only strategy and averting 8,300 infections versus no intervention. Expanding only ART (80% coverage) added 38,000 QALYs at US$2,240/QALY gained versus the methadone substitution therapy-only strategy, and averted 4,080 infections versus no intervention. Offering ART to 80% of non-IDUs eligible for treatment by WHO criteria, but only 10% of IDUs, averted only 1,800 infections versus no intervention and was not cost effective.

Conclusions

Methadone substitution therapy is a highly cost-effective option for the growing mixed HIV epidemic in Ukraine. A strategy that expands both methadone substitution therapy and ART to high levels is the most effective intervention, and is very cost effective by WHO criteria. When expanding ART, access to methadone substitution therapy provides additional benefit in infections averted. Our findings are potentially relevant to other settings with mixed HIV epidemics. Please see later in the article for the Editors'' Summary     

Gene therapy for Parkinson's disease

Parkinson's disease (PD) is a debilitating neurodegenerative disorder arising from loss of dopaminergic neurons in the substantia nigra pars compacta and subsequent depletion of striatal dopamine levels, which results in distressing motor symptoms. The current standard pharmacological treatment for PD is direct replacement of dopamine by treatment with its precursor, levodopa (L-dopa). However, this does not significantly alter disease progression and might contribute to the ongoing pathology. Several features of PD make this disease one of the most promising targets for clinical gene therapy of any neurological disease. The confinement of the major pathology to a compact, localised neuronal population and the anatomy of the basal ganglia circuitry mean that global gene transfer is not required and there are well-defined sites for gene transfer. The multifactorial aetiology of idiopathic PD means that it is unlikely any single gene will cure the disease, and as a result at least three separate gene-transfer strategies are currently being pursued: transfer of genes for enzymes involved in dopamine production; transfer of genes for growth factors involved in dopaminergic cell survival and regeneration; and transfer of genes to reset neuronal circuitry by switching cellular phenotype. The merits of these strategies are discussed here, along with remaining hurdles that might impede transfer of gene therapy technology to the clinic as a treatment for PD.