A Critical Review of the Evidence Concerning the HIV Latency Reversing Effect of Disulfiram, the Possible Explanations for Its Inability to Reduce the Size of the Latent Reservoir In Vivo, and the Caveats Associated with Its Use in Practice

Adeno-Associated Virus (AAV)-Delivered Exosomal TAT and BiTE Molecule CD4-αCD3 Facilitate the Elimination of CD4 T Cells Harboring Latent HIV-1

Combinatorial antiretroviral therapy (cART) has transformed HIV infection from a death sentence to a controllable chronic disease, but cannot eliminate the virus. Latent HIV-1 reservoirs are the major obstacles to cure HIV-1 infection. Previously, we engineered exosomal Tat (Exo-Tat) to reactivate latent HIV-1 from the reservoir of resting CD4+ T cells. Here, we present an HIV-1 eradication platform, which uses our previously described Exo-Tat to activate latent virus from resting CD4+ T cells guided by the specific binding domain of CD4 in interleukin 16 (IL16), attached to the N-terminus of exosome surface protein lysosome-associated membrane protein 2 variant B (Lamp2B). Cells with HIV-1 surface protein gp120 expressed on the cell membranes are then targeted for immune cytolysis by a BiTE molecule CD4-αCD3, which colocalizes the gp120 surface protein of HIV-1 and the CD3 of cytotoxic T lymphocytes. Using primary blood cells obtained from antiretroviral treated individuals, we find that this combined approach led to a significant reduction in replication-competent HIV-1 in infected CD4+ T cells in a clonal in vitro cell system. Furthermore, adeno-associated virus serotype DJ (AAV-DJ) was used to deliver Exo-Tat, IL16lamp2b and CD4-αCD3 genes by constructing them in one AAV-DJ vector (the plasmid was named pEliminator). The coculture of T cells from HIV-1 patients with Huh-7 cells infected with AAV-Eliminator viruses led to the clearance of HIV-1 reservoir cells in the in vitro experiment, which could have implications for reducing the viral reservoir in vivo, indicating that Eliminator AAV viruses have the potential to be developed into therapeutic biologics to cure HIV-1 infection.

Disulfiram inhibits liver fibrosis in rats by suppressing hepatic stellate cell activation and viability

Background

Liver fibrosis is a wound-healing response to chronic injury, featuring with excess accumulation of extracellular matrix secreted by the activated hepatic stellate cells (HSC). Disulfiram (DSF), also known as Antabuse, has been used for the treatment of alcohol addiction and substance abuse. Recently, overwhelming studies had revealed anti-cancer effects of DSF in multiple cancers, including liver cancer. But the actual effects of DSF on liver fibrosis and liver function remain unknown.

Methods

In this study, we evaluated the effects of low-dose DSF in CCl4- and Bile Duct Ligation (BDL)—induced hepatic fibrosis rat models. Cell proliferation was detected by using the Cell-Light™ EdU Apollo®567 Cell Tracking Kit. Cell apoptosis was analyzed using a TdT-mediated dUTP nick end labeling (TUNEL) kit, viability was measured with Cell Counting Kit-8(CCK8). Relative mRNA expression of pro-fibrogenic was assessed using quantitative RT-PCR. The degree of liver fibrosis, activated HSCs, were separately evaluated through Sirius Red-staining, immunohistochemistry and immunofluorescence. Serum alanine aminotransferase (ALT) and asparagine aminotransferase (AST) activities were detected with ALT and AST detecting kits using an automated analyzer.

Results

Liver fibrosis was distinctly attenuated while liver functions were moderately ameliorated in the DSF-treated group. Activation and proliferation of primary rat HSCs isolated from rat livers were significantly suppressed by low-dose DSF. DSF also inhibited the viability of in vitro cultured rat or human HSC cells dose-dependently but had no repressive role on human immortalized hepatocyte THLE-2 cells. Interestingly, upon DSF treatment, the viability of LX-2 cells co-cultured with THLE-2 was significantly inhibited, while that of THLE-2 co-cultured with LX-2 was increased. Further study indicated that HSCs apoptosis was increased in DSF/CCl4-treated liver samples. These data indicated that DSF has potent anti-fibrosis effects and protective effects toward hepatocytes and could possibly be repurposed as an anti-fibrosis drug in the clinic.

Conclusions

DSF attenuated ECM remodeling through suppressing the transformation of quiet HSCs into proliferative, fibrogenic myofibroblasts in hepatic fibrosis rat models. DSF provides a novel approach for the treatment of liver fibrosis.

Latency Reversing Agents: Kick and Kill of HTLV-1?

Human T-cell leukemia virus type 1 (HTLV-1), the cause of adult T-cell leukemia/lymphoma (ATLL), is a retrovirus, which integrates into the host genome and persistently infects CD4⁺ T-cells. Virus propagation is stimulated by (1) clonal expansion of infected cells and (2) de novo infection. Viral gene expression is induced by the transactivator protein Tax, which recruits host factors like positive transcription elongation factor b (P-TEFb) to the viral promoter. Since HTLV-1 gene expression is repressed in vivo by viral, cellular, and epigenetic mechanisms in late phases of infection, HTLV-1 avoids an efficient CD8⁺ cytotoxic T-cell (CTL) response directed against the immunodominant viral Tax antigen. Hence, therapeutic strategies using latency reversing agents (LRAs) sought to transiently activate viral gene expression and antigen presentation of Tax to enhance CTL responses towards HTLV-1, and thus, to expose the latent HTLV-1 reservoir to immune destruction. Here, we review strategies that aimed at enhancing Tax expression and Tax-specific CTL responses to interfere with HTLV-1 latency. Further, we provide an overview of LRAs including (1) histone deacetylase inhibitors (HDACi) and (2) activators of P-TEFb, that have mainly been studied in context of human immunodeficiency virus (HIV), but which may also be powerful in the context of HTLV-1.

The revival of dithiocarbamates: from pesticides to innovative medical treatments

Dithiocarbamates (DTCs) have been used for various applications, including as hardening agents in rubber manufacturing, as fungicide in agriculture, and as medications to treat alcohol misuse disorder. The multi-faceted effects of DTCs rely mainly on metal binding abilities and a high reactivity with thiol groups. Therefore, the list of potential applications is still increasing, exemplified by the US Food and Drug Administration approval of disulfiram (Antabuse) and its metabolite diethyldithiocarbamate in clinical trials against cancer, human immunodeficiency virus, and Lyme disease, as well as new DTC-related compounds that have been synthesized to target diseases with unmet therapeutic needs. In this review, we will discuss the latest progress of DTCs as anti-cancer agents and provide a summary of the mechanisms of action. We will explain the expansion of DTCs' activity in the fields of microbiology, neurology, cardiology, and ophthalmology, thereby providing evidence for the important role and therapeutic potential of DTCs as innovative medical treatments.

Measuring the Success of HIV-1 Cure Strategies

HIV-1 eradication strategies aim to achieve viral remission in the absence of antiretroviral therapy (ART). The development of an HIV-1 cure remains challenging due to the latent reservoir (LR): long-lived CD4 T cells that harbor transcriptionally silent HIV-1 provirus. The LR is stable despite years of suppressive ART and is the source of rebound viremia following therapy interruption. Cure strategies such as "shock and kill" aim to eliminate or reduce the LR by reversing latency, exposing the infected cells to clearance via the immune response or the viral cytopathic effect. Alternative strategies include therapeutic vaccination, which aims to prime the immune response to facilitate control of the virus in the absence of ART. Despite promising advances, these strategies have been unable to significantly reduce the LR or increase the time to viral rebound but have provided invaluable insight in the field of HIV-1 eradication. The development and assessment of an HIV-1 cure requires robust assays that can measure the LR with sufficient sensitivity to detect changes that may occur following treatment. The viral outgrowth assay (VOA) is considered the gold standard method for LR quantification due to its ability to distinguish intact and defective provirus. However, the VOA is time consuming and resource intensive, therefore several alternative assays have been developed to bridge the gap between practicality and accuracy. Whilst a cure for HIV-1 infection remains elusive, recent advances in our understanding of the LR and methods for its eradication have offered renewed hope regarding achieving ART free viral remission.

Nucleolar protein NOP2/NSUN1 suppresses HIV-1 transcription and promotes viral latency by competing with Tat for TAR binding and methylation

Recent efforts have been paid to identify previously unrecognized HIV-1 latency-promoting genes (LPGs) that can potentially be targeted for eradication of HIV-1 latent reservoirs. From our earlier orthologous RNAi screens of host factors regulating HIV-1 replication, we identified that the nucleolar protein NOP2/NSUN1, a m5C RNA methyltransferase (MTase), is an HIV-1 restriction factor. Loss- and gain-of-function analyses confirmed that NOP2 restricts HIV-1 replication. Depletion of NOP2 promotes the reactivation of latently infected HIV-1 proviruses in multiple cell lines as well as primary CD4+ T cells, alone or in combination with latency-reversing agents (LRAs). Mechanistically, NOP2 associates with HIV-1 5' LTR, interacts with HIV-1 TAR RNA by competing with HIV-1 Tat protein, as well as contributes to TAR m5C methylation. RNA MTase catalytic domain (MTD) of NOP2 mediates its competition with Tat and binding with TAR. Overall, these findings verified that NOP2 suppresses HIV-1 transcription and promotes viral latency.

Reduce and Control: A Combinatorial Strategy for Achieving Sustained HIV Remissions in the Absence of Antiretroviral Therapy

Human immunodeficiency virus (HIV-1) indefinitely persists, despite effective antiretroviral therapy (ART), within a small pool of latently infected cells. These cells often display markers of immunologic memory and harbor both replication-competent and -incompetent proviruses at approximately a 1:100 ratio. Although complete HIV eradication is a highly desirable goal, this likely represents a bridge too far for our current and foreseeable technologies. A more tractable goal involves engineering a sustained viral remission in the absence of ART––a “functional cure.” In this setting, HIV remains detectable during remission, but the size of the reservoir is small and the residual virus is effectively controlled by an engineered immune response or other intervention. Biological precedence for such an approach is found in the post-treatment controllers (PTCs), a rare group of HIV-infected individuals who, following ART withdrawal, do not experience viral rebound. PTCs are characterized by a small reservoir, greatly reduced inflammation, and the presence of a poorly understood immune response that limits viral rebound. Our goal is to devise a safe and effective means for replicating durable post-treatment control on a global scale. This requires devising methods to reduce the size of the reservoir and to control replication of this residual virus. In the following sections, we will review many of the approaches and tools that likely will be important for implementing such a “reduce and control” strategy and for achieving a PTC-like sustained HIV remission in the absence of ART.

Alternate NF-κB-Independent Signaling Reactivation of Latent HIV-1 Provirus

Current combination antiretroviral therapies (cART) are unable to eradicate HIV-1 from infected individuals because of the establishment of proviral latency in long-lived cellular reservoirs. The shock-and-kill approach aims to reactivate viral replication from the latent state (shock) using latency-reversing agents (LRAs), followed by the elimination of reactivated virus-producing cells (kill) by specific therapeutics. The NF-κB RelA/p50 heterodimer has been characterized as an essential component of reactivation of the latent HIV-1 long terminal repeat (LTR). Nevertheless, prolonged NF-κB activation contributes to the development of various autoimmune, inflammatory, and malignant disorders. In the present study, we established a cellular model of HIV-1 latency in J-Lat CD4⁺ T cells that stably expressed the NF-κB superrepressor IκB-α 2NΔ4 and demonstrate that conventional treatments with bryostatin-1 and hexamethylenebisacetamide (HMBA) or ionomycin synergistically reactivated HIV-1 from latency, even under conditions where NF-κB activation was repressed. Using specific calcineurin phosphatase, p38, and MEK1/MEK2 kinase inhibitors or specific short hairpin RNAs, c-Jun was identified to be an essential factor binding to the LTR enhancer κB sites and mediating the combined synergistic reactivation effect. Furthermore, acetylsalicylic acid (ASA), a potent inhibitor of the NF-κB activator kinase IκB kinase β (IKK-β), did not significantly diminish reactivation in a primary CD4⁺ T central memory (T_CM) cell latency model. The present work demonstrates that the shock phase of the shock-and-kill approach to reverse HIV-1 latency may be achieved in the absence of NF-κB, with the potential to avoid unwanted autoimmune- and or inflammation-related side effects associated with latency-reversing strategies.IMPORTANCE The shock-and-kill approach consists of the reactivation of HIV-1 replication from latency using latency-reversing agents (LRAs), followed by the elimination of reactivated virus-producing cells. The cellular transcription factor NF-κB is considered a master mediator of HIV-1 escape from latency induced by LRAs. Nevertheless, a systemic activation of NF-κB in HIV-1-infected patients resulting from the combined administration of different LRAs could represent a potential risk, especially in the case of a prolonged treatment. We demonstrate here that conventional treatments with bryostatin-1 and hexamethylenebisacetamide (HMBA) or ionomycin synergistically reactivate HIV-1 from latency, even under conditions where NF-κB activation is repressed. Our study provides a molecular proof of concept for the use of anti-inflammatory drugs, like aspirin, capable of inhibiting NF-κB in patients under combination antiretroviral therapy during the shock-and-kill approach, to avoid potential autoimmune and inflammatory disorders that can be elicited by combinations of LRAs.

Current and Future Therapeutic Strategies for Lentiviral Eradication from Macrophage Reservoirs

Macrophages, one of the most abundant populations of leukocytes in the body, function as the first line of defense against pathogen invaders. Human Immunodeficiency virus 1 (HIV-1) remains to date one of the most extensively studied viral infections. Naturally occurring lentiviruses in domestic and primate species serve as valuable models to investigate lentiviral pathogenesis and novel therapeutics. Better understanding of the role macrophages play in HIV pathogenesis will aid in the advancement towards a cure. Even with current efficacy of first- and second-line Antiretroviral Therapy (ART) guidelines and future efficacy of Long Acting Slow Effective Release-ART (LASER-ART); ART alone does not lead to a cure. The major challenge of HIV eradication is viral latency. Latency Reversal Agents (LRAs) show promise as a possible means to eradicate HIV-1 from the body. It has become evident that complete eradication will need to include combinations of various effective therapeutic strategies such as LASER-ART, LRAs, and gene editing. Review of the current literature indicates the most promising HIV eradication strategy appears to be LASER-ART in conjunction with viral and receptor gene modifications via the CRISPR/Cas9 system. Graphical abstract A multimodal approach to HIV treatment including gene editing, LASER-ART, and latency reversal agents may provide a means to achieve HIV eradication.