Shock-and-kill versus block-and-lock: Targeting the fluctuating and heterogeneous HIV-1 gene expression.
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ABSTRACT:
SUBMITTER: Yeh YJ
PROVIDER: S-EPMC8072369 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Today HIV infection cannot be cured due to the presence of a reservoir of latently infected cells inducing a viral rebound upon treatment interruption. Hence, the latent reservoir is considered as the major barrier for an HIV cure. So far, efforts to completely eradicate the reservoir via a shock-and-kill approach have proven difficult and unsuccessful. Therefore, more research has been done recently on an alternative block-and-lock functional cure strategy. In contrast to the shock-and-kill strategy that aims to eradicate the entire reservoir, block-and-lock aims to permanently silence all proviruses, even after treatment interruption. HIV silencing can be achieved by targeting different factors of the transcription machinery. In this review, we first describe the underlying mechanisms of HIV transcription and silencing. Next, we give an overview of the different block-and-lock strategies under investigation.
| S-EPMC7019976 | biostudies-literature
Project description:The goal of this study was to investigate transcriptome remodeling induced by treatment with a camptothetin analog, Topotecan (TPT), of a primary T cell model of HIV latency. The study aimed to determine whether TPT has a global inhibitory effect on gene expression in primary CD4+ T cells, and identify mechanisms of action of this drug as an HIV “block and lock” agent. Methods: CD4+ T cells were isolated from blood of HIV seronegative study participants (N=3) and utilized to generate an in vitro model of latent HIV infection (model developed in the Spina laboratory and previously described by Spina et al., 2013 and Soto et al., 2022). Following generation of the model, cells were treated with 10 uM Topotecan or its solvent dimethyl sulfoxide (DMSO) for 24 hours. Cells were lyzed with RLT buffer containing beta-mercaptoethanol from a RNeasy micro kit (Qiagen, Inc. cat # 74004). ERCC spikes (Thermo Fisher Scientific, Inc.) were added to cell lysates based on cell number in each sample (10 ul of 1:800 dilution per million cells). RNA was extracted and subjected to deep sequencing at the Institute for Genomics Medicine (IGM) Genomics Center at the University of California San Diego. Filtering low quality reads and removal of the 3’ adapter sequences were performed using the Trim Galore tool. Reads were mapped to the human genome (build hg38) using HISAT2, and to HIV and ERCC references using bowtie. Mapped human reads were counted against the human GENCODE annotation (v37) using HT-Seq. ERCC counts were used to determine whether TPT had global inhibitory effect on transcription in primary CD4+ T cells. Because no such effect was observed, differential gene expression analysis was performed using library EdgeR in Bioconductor R without correction of expression based on ERCC spikes. Genes with false discovery rate (FDR)-corrected p-value less than 0.05 and an absolute fold change in TPT-treated samples compared to DMSO controls greater than 2, were considered significantly modulated by TPT. Pathway and gene ontology (GO) term enrichment analysis was performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) v2022q3. Pathways and GO terms with FDR-corrected p-value less than 0.05 were considered significantly enriched for differentially expressed genes. Results: An average of 19.7 million reads per sample were acquired and mapped to the human genome (build hg38). After applying filtering criteria, 9,678 human genes were identified with the HISAT2 and HTSeq workflow. Differential expression analysis was performed between TPT- and DMSO-treated samples using EdgeR. A total of 1,749 differentially expressed genes (DEGs) were identified with FDR p-value <0.05 and an absolute fold change greater than 2; of which 522 were up- and 1227 downregulated by TPT. Pathway and GO term enrichment analysis revealed that TPT interferes with gene transcription and cell signaling pathways (e.g. T cell receptor signaling, positive regulation of JNK cascade, regulation of actin cytoskeleton and positive regulation of GTPase activity were affected by TPT treatment). Conclusion: The study demonstrated that TPT induces multiple effects on transcriptome in primary CD4+ T cells. Some of these changes may represent direct and indirect mechanisms of action of TPT as an HIV “block and lock” agent.
2023-01-20 | GSE215461 | GEO
Project description:HIV-1/AIDS remains a global public health problem. The world health organization (WHO) reported at the end of 2019 that 38 million people were living with HIV-1 worldwide, of which only 67% were accessing antiretroviral therapy (ART). Despite great success in the clinical management of HIV-1 infection, ART does not eliminate the virus from the host genome. Instead, HIV-1 remains latent as a viral reservoir in any tissue containing resting memory CD4+ T cells. The elimination of these residual proviruses that can reseed full-blown infection upon treatment interruption remains the major barrier towards curing HIV-1. Novel approaches have recently been developed to excise or disrupt the virus from the host cells (e.g., gene editing with the CRISPR-Cas system) to permanently shut off transcription of the virus (block-and-lock and RNA interference strategies), or to reactivate the virus from cell reservoirs so that it can be eliminated by the immune system or cytopathic effects (shock-and-kill strategy). Here, we will review each of these approaches, with the major focus placed on the block-and-lock strategy.
| S-EPMC7765451 | biostudies-literature
Project description:While modern HIV therapy can effectively suppress viral replication, the persistence of the latent reservoir posits the greatest hurdle to complete cure. The "shock and kill" strategy is under investigation for HIV therapy, aiming to reactivate latent HIV, and subsequently eliminate it through anti-retroviral therapy and host immune function. However, thus far, studies have yielded suboptimal results, stemming from a combination of ineffective latency reversal and poor immune clearance. Concomitantly, studies have now revealed the importance of the BCL-2 anti-apoptotic protein as a critical mediator of infected cell survival, reservoir maintenance and immune evasion in HIV. Furthermore, BCL-2 inhibitors are now recognized for their anti-HIV effects in pre-clinical studies. This minireview aims to examine the intersection of BCL-2 inhibition and current shock and kill efforts, hoping to inform future studies which may ultimately yield a cure for HIV.
| S-EPMC9631312 | biostudies-literature
Project description:HIV-1 Tat activates viral transcription and limited Tat transactivation correlates with latency establishment. We postulated a "block-and-lock" functional cure approach based on properties of the Tat inhibitor didehydro-Cortistatin A (dCA). HIV-1 transcriptional inhibitors could block ongoing viremia during antiretroviral therapy (ART), locking the HIV promoter in persistent latency. We investigated this hypothesis in human CD4+ T cells isolated from aviremic individuals. Combining dCA with ART accelerates HIV-1 suppression and prevents viral rebound after treatment interruption, even during strong cellular activation. We show that dCA mediates epigenetic silencing by increasing nucleosomal occupancy at Nucleosome-1, restricting RNAPII recruitment to the HIV-1 promoter. The efficacy of dCA was studied in the bone marrow-liver-thymus (BLT) mouse model of HIV latency and persistence. Adding dCA to ART-suppressed mice systemically reduces viral mRNA in tissues. Moreover, dCA significantly delays and reduces viral rebound levels upon treatment interruption. Altogether, this work demonstrates the potential of block-and-lock cure strategies.
| S-EPMC5653276 | biostudies-literature
Project description:A significant number of people living with human immunodeficiency virus type 1 (HIV-1) suffer from HIV-associated neurocognitive disorders (HAND). Many previous studies investigating HIV in astrocytes as a heterogenous population have established the relevance of astrocytes to HIV-associated neuropathogenesis. However, these studies were unable to differentiate the state of infection, i.e., active or latent, or to evaluate how this affects astrocyte biology. In this study, the pseudotyped doubly labeled fluorescent reporter red/green (R/G)-HIV-1 was used to identify and enrich restricted and active populations of HIV+ astrocytes based on the viral promoter activity. Here, we report that the majority of human astrocytes restricted R/G-HIV-1 gene expression early during infection and were resistant to reactivation by vorinostat and interleukin 1β. However, actively infected astrocytes were inducible, leading to increased expression of viral proteins upon reactivation. R/G-HIV-1 infection also significantly decreased the cell proliferation and glutamate clearance ability of astrocytes, which may contribute to excitotoxicity. Moreover, transcriptome analyses to compare gene expression patterns of astrocyte harboring active versus restricted long terminal repeats (LTRs) revealed that the gene expression patterns were similar and that the active population demonstrated more widespread and robust changes. Our data suggest that harboring the HIV genome profoundly alters astrocyte biology and that strategies that keep the virus latent (e.g., block and lock) or those that reactivate the latent virus (e.g., shock and kill) would be detrimental to astrocyte function and possibly augment their contributions to HAND.IMPORTANCE More than 36 million people are living with HIV-1 worldwide, and despite antiretroviral therapy, 30 to 50% of the people living with HIV-1 suffer from mild to moderate neurocognitive disorders. HIV-1 reservoirs in the central nervous system (CNS) are challenging to address due to low penetration of antiretroviral drugs, lack of resident T cells, and permanent integration of provirus into neural cells such as microglia and astrocytes. Several studies have shown astrocyte dysfunction during HIV-1 infection. However, little is known about how HIV-1 latency affects their function. The significance of our research is in identifying that the majority of HIV+ astrocytes restrict HIV expression and were resistant to reactivation. Further, simply harboring the HIV genome profoundly altered astrocyte biology, resulting in a proinflammatory phenotype and functional changes. In this context, therapeutic strategies to reactivate or silence astrocyte HIV reservoirs, without excising proviral DNA, will likely lead to detrimental neuropathological outcomes during HIV CNS infection.
| S-EPMC7158706 | biostudies-literature
Project description:UnlabelledUnderstanding how some HIV-infected cells resist the cytotoxicity of HIV replication is crucial to enabling HIV cure efforts. HIV killing of CD4 T cells that replicate HIV can involve HIV protease-mediated cleavage of procaspase 8 to generate a fragment (Casp8p41) that directly binds and activates the mitochondrial proapoptotic protein BAK. Here, we demonstrate that Casp8p41 also binds with nanomolar affinity to the antiapoptotic protein Bcl-2, which sequesters Casp8p41 and prevents apoptosis. Further, we show that central memory CD4 T cells (TCM) from HIV-infected individuals have heightened expression of BCL-2 relative to procaspase 8, possibly explaining the persistence of HIV-infected TCMdespite generation of Casp8p41. Consistent with this hypothesis, the selective BCL-2 antagonist venetoclax induced minimal killing of uninfected CD4 T cells but markedly increased the death of CD4 T cells and diminished cell-associated HIV DNA when CD4 T cells from antiretroviral therapy (ART)-suppressed HIV patients were induced with αCD3/αCD28 to reactivate HIVex vivo Thus, priming CD4 T cells from ART suppressed HIV patients with a BCL-2 antagonist, followed by HIV reactivation, achieves reductions in cell-associated HIV DNA, whereas HIV reactivation alone does not.ImportanceHIV infection is incurable due to a long-lived reservoir of HIV(+)memory CD4 T cells, and no clinically relevant interventions have been identified that reduce the number of these HIV DNA-containing cells. Since postintegration HIV replication can result in HIV protease generation of Casp8p41, which activates BAK, causing infected CD4 T cell death, we sought to determine whether this occurs in memory CD4 T cells. Here, we demonstrate that memory CD4 T cells can generate Casp8p41 and yet are intrinsically resistant to death induced by diverse stimuli, including Casp8p41. Furthermore, BCL-2 expression is relatively increased in these cells and directly binds and inhibits Casp8p41's proapoptotic effects. Antagonizing BCL-2 with venetoclax derepresses this antagonism, resulting in death, preferentially in HIV DNA containing cells, since only these cells generate Casp8p41. Thus, BCL-2 antagonism is a clinically relevant intervention with the potential to reduce HIV reservoir size in patients.
| S-EPMC4810548 | biostudies-literature
Project description:Abstract Cell membranes phase separate into ordered
| S-EPMC10427746 | biostudies-literature
Project description:Evaluation of a camptothetin analog, Topotecan, as an HIV "block and lock" agent
| PRJNA890303 | ENA
Project description:Plants have evolved complex mechanisms to balance the efficient use of absorbed light energy in photosynthesis with the capacity to use that energy in assimilation, so avoiding potential damage from excess light. This is particularly important under natural light, which can vary according to weather, solar movement and canopy movement. Photosynthetic acclimation is the means by which plants alter their leaf composition and structure over time to enhance photosynthetic efficiency and productivity. However there is no empirical or theoretical basis for understanding how leaves track historic light levels to determine acclimation status, or whether they do this accurately. We hypothesized that in fluctuating light (varying in both intensity and frequency), the light-response characteristics of a leaf should adjust (dynamically acclimate) to maximize daily carbon gain. Using a framework of mathematical modelling based on light-response curves, we have analysed carbon-gain dynamics under various light patterns. The objective was to develop new tools to quantify the precision with which photosynthesis acclimates according to the environment in which plants exist and to test this tool on existing data. We found an inverse relationship between the optimal maximum photosynthetic capacity and the frequency of low to high light transitions. Using experimental data from the literature we were able to show that the observed patterns for acclimation were consistent with a strategy towards maximizing daily carbon gain. Refinement of the model will further determine the precision of acclimation.
| S-EPMC4629418 | biostudies-literature