The Effect of JAK1/2 Inhibitors on HIV Reservoir Using Primary Lymphoid Cell Model of HIV Latency

Monocyte to macrophage differentiation and changes in cellular redox homeostasis promote cell type-specific HIV latency reactivation

HIV latency regulation in monocytes and macrophages can vary according to signals directing differentiation, polarization, and function. To investigate these processes, we generated an HIV latency model in THP-1 monocytes and showed differential levels of HIV reactivation among clonal populations. Monocyte-to-macrophage differentiation of HIV-infected primary human CD14+ and THP-1 cells induced HIV reactivation and showed that virus production increased concomitant with macrophage differentiation. We applied the HIV-infected THP-1 monocyte-to-macrophage (MLat) model to assess the biological mechanisms regulating HIV latency dynamics during monocyte-to-macrophage differentiation. We pinpointed protein kinase C signaling pathway activation and Cyclin T1 upregulation as inherent differentiation mechanisms that regulate HIV latency reactivation. Macrophage polarization regulated latency, revealing proinflammatory M1 macrophages suppressed HIV reactivation while anti-inflammatory M2 macrophages promoted HIV reactivation. Because macrophages rely on reactive-oxygen species (ROS) to exert numerous cellular functions, we disrupted redox pathways and found that inhibitors of the thioredoxin (Trx) system acted as latency-promoting agents in T-cells and monocytes, but opposingly acted as latency-reversing agents in macrophages. We explored this mechanism with Auranofin, a clinical candidate for reducing HIV reservoirs, and demonstrated Trx reductase inhibition led to ROS induced NF-κB activity, which promoted HIV reactivation in macrophages, but not in T-cells and monocytes. Collectively, cell type-specific differences in HIV latency regulation could pose a barrier to HIV eradication strategies.

Transcriptomic crosstalk between viral and host factors drives aberrant homeostasis of T-cell proliferation and cell death in HIV-infected immunological non-responders

BACKGROUND

Immunological non-responders (INRs) among people living with HIV have inherently higher mortality and morbidity rates. The underlying immunological mechanisms whereby failure of immune reconstitution occurs in INRs require elucidation.

METHOD

HIV-1 DNA and HIV-1 cell-associated RNA (CA-HIV RNA) quantifications were conducted via RT-qPCR. Transcriptome sequencing (RNA-seq), bioinformatics, and biological verifications were performed to discern the crosstalk between host and viral factors. Flow cytometry was employed to analyze cellular activation, proliferation, and death.

RESULTS

HIV-1 DNA and CA-HIV RNA levels were observed to be significantly higher in INRs compared to immunological responders (IRs). Evaluation of CD4/CD8 ratios showed a significantly negative correlation with HIV-1 DNA in IRs, but not in INRs. Bioinformatics analyses and biological verifications showed IRF7/INF-α regulated antiviral response was intensified in INRs. PBMCs of INRs expressed significantly more HIV integrase-mRNA (p31) than IRs. Resting (CD4+CD69- T-cells) and activated (CD4+CD69+ T-cells) HIV-1 reservoir harboring cells were significantly higher in INRs, with the co-occurrence of significantly higher cellular proliferation and cell death in CD4+ T-cells of INRs.

CONCLUSION

In INRs, the systematic crosstalk between the HIV-1 reservoir and host cells tends to maintain a persistent antiviral response-associated inflammatory environment, which drives aberrant cellular activation, proliferation, and death of CD4+ T-cells.

JAK/STAT signaling pathway affects CCR5 expression in human CD4+ T cells

CCR5 serves as R5-tropic HIV co-receptor. Knocking out CCR5 in HIV patients, which has occurred <10 times, is believed important for cure. JAK/STAT inhibitors tofacitinib and ruxolitinib inhibit CCR5 expression in HIV+ viremic patients. We investigated the association of JAK/STAT signaling pathway with CCR5/CCR2 expression in human primary CD4+ T cells and confirmed its importance. Six of nine JAK/STAT inhibitors that reduced CCR5/CCR2 expression were identified. Inhibitor-treated CD4+ T cells were relatively resistant, specifically to R5-tropic HIV infection. Furthermore, single JAK2, STAT3, STAT5A, and STAT5B knockout and different combinations of JAK/STAT knockout significantly reduced CCR2/CCR5 expression of both RNA and protein levels, indicating that CCR5/CCR2 expression was positively regulated by JAK-STAT pathway in CD4+ T cells. Serum and glucocorticoid-regulated kinase 1 (SGK1) knockout affected CCR2/CCR5 gene expression, suggesting that SGK1 is involved in CCR2/CCR5 regulation. If cell surface CCR5 levels can be specifically and markedly down-regulated without adverse effects, that may have a major impact on the HIV cure agenda.

Targeting Human Proteins for Antiviral Drug Discovery and Repurposing Efforts: A Focus on Protein Kinases

Despite the great technological and medical advances in fighting viral diseases, new therapies for most of them are still lacking, and existing antivirals suffer from major limitations regarding drug resistance and a limited spectrum of activity. In fact, most approved antivirals are directly acting antiviral (DAA) drugs, which interfere with viral proteins and confer great selectivity towards their viral targets but suffer from resistance and limited spectrum. Nowadays, host-targeted antivirals (HTAs) are on the rise, in the drug discovery and development pipelines, in academia and in the pharmaceutical industry. These drugs target host proteins involved in the virus life cycle and are considered promising alternatives to DAAs due to their broader spectrum and lower potential for resistance. Herein, we discuss an important class of HTAs that modulate signal transduction pathways by targeting host kinases. Kinases are considered key enzymes that control virus-host interactions. We also provide a synopsis of the antiviral drug discovery and development pipeline detailing antiviral kinase targets, drug types, therapeutic classes for repurposed drugs, and top developing organizations. Furthermore, we detail the drug design and repurposing considerations, as well as the limitations and challenges, for kinase-targeted antivirals, including the choice of the binding sites, physicochemical properties, and drug combinations.

Controversies in the Design of Strategies for the Cure of HIV Infection

The cure for chronic human immunodeficiency virus (HIV) infections has been a goal pursued since the antiretroviral therapy that improved the clinical conditions of patients became available. However, the exclusive use of these drugs is not enough to achieve a cure, since the viral load rebounds when the treatment is discontinued, leading to disease progression. There are several theories and hypotheses about the biological foundations that prevent a cure. The main obstacle appears to be the existence of a latent viral reservoir that cannot be eliminated pharmacologically. This concept is the basis of the new strategies that seek a cure, known as kick and kill. However, there are other lines of study that recognize mechanisms of persistent viral replication in patients under effective treatment, and that would modify the current lines of research on the cure of HIV. Given the importance of these concepts, in this work, we propose to review the most recent evidence on these hypotheses, covering both the evidence that is positioned in favor and against, trying to expose what are some of the challenges that remain to be resolved in this field of research.

The Dynamic Linkage between Provirus Integration Sites and the Host Functional Genome Property Alongside HIV-1 Infections Associated with Antiretroviral Therapy

(1) Background: The HIV-1 latent reservoir harboring replication-competent proviruses is the major barrier in the quest for an HIV-1 infection cure. HIV-1 infection at all stages of disease progression is associated with immune activation and dysfunctional production of proinflammatory soluble factors (cytokines and chemokines), and it is expected that during HIV-1 infection, different immune components and immune cells, in turn, participate in immune responses, subsequently activating downstream biological pathways. However, the functional interaction between HIV-1 integration and the activation of host biological pathways is presently not fully understood. (2) Methods: In this work, I used genes targeted by proviruses from published datasets to seek enriched immunologic signatures and host biological pathways alongside HIV-1 infections based on MSigDb and KEGG over-representation analysis. (3) Results: I observed that different combinations of immunologic signatures of immune cell types and proinflammatory soluble factors appeared alongside HIV-1 infections associated with antiretroviral therapy. Moreover, enriched KEGG pathways were often related to "cancer specific types", "immune system", "infectious disease viral", and "signal transduction". (4) Conclusions: The observations in this work suggest that the gene sets harboring provirus integration sites may define specific immune cells and proinflammatory soluble factors during HIV-1 infections associated with antiretroviral therapy.

IRF7 expression correlates with HIV latency reversal upon specific blockade of immune activation

The persistence of latent HIV reservoirs allows for viral rebound upon antiretroviral therapy interruption, hindering effective HIV-1 cure. Emerging evidence suggests that modulation of innate immune stimulation could impact viral latency and contribute to the clearing of HIV reservoir. Here, the latency reactivation capacity of a subclass of selective JAK2 inhibitors was characterized as a potential novel therapeutic strategy for HIV-1 cure. Notably, JAK2 inhibitors reversed HIV-1 latency in non-clonal lymphoid and myeloid in vitro models of HIV-1 latency and also ex vivo in CD4+ T cells from ART+ PWH, albeit its function was not dependent on JAK2 expression. Immunophenotypic characterization and whole transcriptomic profiling supported reactivation data, showing common gene expression signatures between latency reactivating agents (LRA; JAK2i fedratinib and PMA) in contrast to other JAK inhibitors, but with significantly fewer affected gene sets in the pathway analysis. In depth evaluation of differentially expressed genes, identified a significant upregulation of IRF7 expression despite the blockade of the JAK-STAT pathway and downregulation of proinflammatory cytokines and chemokines. Moreover, IRF7 expression levels positively correlated with HIV latency reactivation capacity of JAK2 inhibitors and also other common LRAs. Collectively, these results represent a promising step towards HIV eradication by demonstrating the potential of innate immune modulation for reducing the viral reservoir through a novel pathway driven by IRF7.

Senotherapeutics in Cancer and HIV

Cellular senescence is a stress-response mechanism that contributes to homeostasis maintenance, playing a beneficial role during embryogenesis and in normal adult organisms. In contrast, chronic senescence activation may be responsible for other events such as age-related disorders, HIV and cancer development. Cellular senescence activation can be triggered by different insults. Regardless of the inducer, there are several phenotypes generally shared among senescent cells: cell division arrest, an aberrant shape, increased size, high granularity because of increased numbers of lysosomes and vacuoles, apoptosis resistance, defective metabolism and some chromatin alterations. Senescent cells constitute an important area for research due to their contributions to the pathogenesis of different diseases such as frailty, sarcopenia and aging-related diseases, including cancer and HIV infection, which show an accelerated aging. Hence, a new pharmacological category of treatments called senotherapeutics is under development. This group includes senolytic drugs that selectively attack senescent cells and senostatic drugs that suppress SASP factor delivery, inhibiting senescent cell development. These new drugs can have positive therapeutic effects on aging-related disorders and act in cancer as antitumor drugs, avoiding the undesired effects of senescent cells such as those from SASP. Here, we review senotherapeutics and how they might affect cancer and HIV disease, two very different aging-related diseases, and review some compounds acting as senolytics in clinical trials.

JAK-STAT Pathway: A Novel Target to Tackle Viral Infections

Modulation of the antiviral innate immune response has been proposed as a putative cellular target for the development of novel pan-viral therapeutic strategies. The Janus kinase–signal transducer and activator of transcription (JAK-STAT) pathway is especially relevant due to its essential role in the regulation of local and systemic inflammation in response to viral infections, being, therefore, a putative therapeutic target. Here, we review the extraordinary diversity of strategies that viruses have evolved to interfere with JAK-STAT signaling, stressing the relevance of this pathway as a putative antiviral target. Moreover, due to the recent remarkable progress on the development of novel JAK inhibitors (JAKi), the current knowledge on its efficacy against distinct viral infections is also discussed. JAKi have a proven efficacy against a broad spectrum of disorders and exhibit safety profiles comparable to biologics, therefore representing good candidates for drug repurposing strategies, including viral infections.