Manlio Tolomeo

The block-and-lock strategy aims to achieve a functional cure for human immunodeficiency virus type 1 (HIV-1) infection by enforcing durable, drug-independent silencing of proviral transcription. Several latency-promoting agents have been described that effectively limit viral reactivation in vitro or in animal models. However, most approaches induce only partial or reversible transcriptional repression and have not yet been translated into safe and effective clinical interventions. This review summarizes the molecular mechanisms underlying block-and-lock strategies and critically evaluates the limitations of current candidate compounds. We highlight recent advances in understanding HIV-1 integration site selection, focusing on the roles of lens epithelium-derived growth factor p75 (LEDGF/p75) and cleavage and polyadenylation specificity factor subunit 6 (CPSF6) in directing proviral integration toward gene-dense, transcriptionally active chromatin. Pharmacological disruption of the LEDGF/p75–integrase interaction by LEDGF/p75 inhibitors (LEDGINs) redirects proviral integration toward less transcriptionally active genomic regions that are more resistant to reactivation. Recent tandem knockout experiments, however, demonstrate that CPSF6 plays a dominant role in guiding HIV-1 integration toward gene-dense, transcriptionally active chromatin. LEDGIN treatment has been linked to the preferential targeting of proviruses to heterochromatin-rich regions within the nuclear interior. By contrast, CPSF6 knockout redirects integration toward peripheral heterochromatin, especially lamina-associated domains (LADs), genomic regions typically exhibiting stronger and more stable transcriptional repression than interior heterochromatin. These findings suggest that therapeutic modulation of CPSF6 may exert a more profound and durable effect on proviral silencing within a block-and-lock framework. Nevertheless, complete CPSF6 ablation is associated with severe cellular toxicity. The challenges associated with CPSF6-related adverse effects and potential strategies to overcome these limitations are discussed.

The block-and-lock strategy aims to achieve a functional cure for human immunodeficiency virus type 1 (HIV-1) infection by enforcing durable, drug-independent silencing of proviral transcription. Several latency-promoting agents have been described that effectively limit viral reactivation in vitro or in animal models. However, most approaches induce only partial or reversible transcriptional repression and have not yet been translated into safe and effective clinical interventions. This review summarizes the molecular mechanisms underlying block-and-lock strategies and critically evaluates the limitations of current candidate compounds. We highlight recent advances in understanding HIV-1 integration site selection, focusing on the roles of lens epithelium-derived growth factor p75 (LEDGF/p75) and cleavage and polyadenylation specificity factor subunit 6 (CPSF6) in directing proviral integration toward gene-dense, transcriptionally active chromatin. Pharmacological disruption of the LEDGF/p75–integrase interaction by LEDGF/p75 inhibitors (LEDGINs) redirects proviral integration toward less transcriptionally active genomic regions that are more resistant to reactivation. Recent tandem knockout studies, however, demonstrate that CPSF6 plays a dominant role in guiding HIV-1 integration toward gene-dense, transcriptionally active chromatin. LEDGIN treatment has been linked to the preferential targeting of proviruses to heterochromatin-rich regions within the nuclear interior. By contrast, CPSF6 knockout redirects integration toward peripheral heterochromatin, especially lamina-associated domains (LADs), genomic regions typically exhibiting stronger and more stable transcriptional repression than interior heterochromatin. These findings suggest that therapeutic modulation of CPSF6 may exert a more profound and durable effect on proviral silencing within a block-and-lock framework. Nevertheless, complete CPSF6 ablation is associated with severe cellular toxicity. The challenges associated with CPSF6-related adverse effects and potential strategies to overcome these limitations are discussed.

The STAT (Signal Transducer and Activator of Transcription) signaling pathway plays a central role in immune regulation by mediating cytokine responses and orchestrating both innate and adaptive immunity. Although CD4+ T cell depletion is the main driver of HIV-1–induced immunodeficiency, the virus also exerts a significant and often underestimated impact by disrupting the function of STAT family members, thereby exacerbating immune imbalance and accelerating disease progression. Specifically, HIV-1 suppresses STAT1 activation, impairing the induction of antiviral genes; inhibits IL-23–driven STAT3 activation in CD4+ Th17 cells with a reduction in IL-17; alters STAT3-dependent functions in antigen-presenting cells; and imposes profound—and at times opposing—dysregulations of STAT5, including the induction of a truncated isoform that contributes to latency. Notably, pharmacological inhibition of the JAK/STAT axis, particularly with JAK2 inhibitors, has been shown to reduce integrated proviral DNA and viral replication in vitro and in early clinical studies. This review provides an updated overview of the roles of individual STAT proteins in HIV-1 infection and pathogenesis, emphasizing the intricate interplay between viral factors and host signaling, highlighting the potential therapeutic implications, and suggesting that immunological assessment in HIV-1 patients should extend beyond CD4+ T cell counts and the CD4/CD8 ratio to include functional analysis of STAT signaling for deeper insights into immune dysfunction and chronic inflammation.

The STAT (Signal Transducer and Activator of Transcription) signaling pathway plays a central role in immune regulation by mediating cytokine responses and orchestrating both innate and adaptive immunity. Although CD4+ T cell depletion is the main driver of HIV-1–induced immunodeficiency, the virus also exerts a significant and often underestimated impact by disrupting the function of STAT family members, thereby exacerbating immune imbalance and accelerating disease progression. Specifically, HIV-1 suppresses STAT1 activation, impairing the induction of antiviral genes; inhibits IL-23–driven STAT3 activation in CD4+ Th17 cells with reduction of IL-17; alters STAT3-dependent functions in antigen-presenting cells; and imposes profound—and at times opposing—dysregulations of STAT5, including the induction of a truncated isoform that contributes to latency. Notably, pharmacological inhibition of the JAK/STAT axis, particularly with JAK2 inhibitors, has been shown to reduce integrated proviral DNA and viral replication in vitro and in early clinical studies. This review provides an updated overview of the roles of individual STAT proteins in HIV-1 infection and pathogenesis, emphasizing the intricate interplay between viral factors and host signaling, highlighting the potential therapeutic implications, and suggesting that immunological assessment in HIV-1 patients should extend beyond CD4+ T cell counts and the CD4/CD8 ratio to include functional analysis of STAT signaling for deeper insights into immune dysfunction and chronic inflammation.

Antiretroviral therapy (ART) has significantly improved the prognosis of human immunodeficiency virus type 1 (HIV-1) infection. Although ART can suppress plasma viremia below detectable levels, it cannot eradicate the HIV-1 DNA (provirus) integrated into the host cell genome. This integration often results in unrepaired DNA damage due to the HIV-1-induced inhibition of DNA repair pathways. Furthermore, HIV-1 infection causes telomere attrition in host chromosomes, a critical factor contributing to CD4+ T cell senescence and apoptosis. HIV-1 proteins can induce DNA damage, block DNA replication, and activate DNA damage responses across various organs. In this review, we explore multiple aspects of the intricate interactions between HIV-1 and the host genome involved in CD4+ T cell depletion, inflammaging, the clonal expansion of infected cells in long-term-treated patients, and viral latency. We discuss the molecular mechanisms of DNA damage that contribute to comorbidities in HIV-1-infected individuals and highlight emerging therapeutic strategies targeting the integrated HIV-1 provirus.

Antiretroviral therapy (ART) has significantly improved the prognosis of human immunodeficiency virus type 1 (HIV-1) infection. Although ART can suppress plasma viraemia below detectable levels, it cannot eradicate the HIV-1 DNA (provirus) integrated into the host cell genome. This integration often results in unrepaired DNA damage due to HIV-induced inhibition of DNA repair pathways. Furthermore, HIV in-fection causes telomere attrition in host chromosomes, a critical factor contributing to CD4+ T-cell senescence and apoptosis. HIV proteins can induce DNA damage, block DNA replication, and activate DNA damage responses across various organs. In this review, we explore multiple aspects of the intricate interactions between HIV-1 and the host genome involved in CD4+ T-cell depletion, inflammaging, clonal expansion of infected cells in long-term treated patients, and viral latency. We discuss the molecular mechanisms of DNA damage that contribute to comorbidities in HIV-1-infected individuals and highlight emerging therapeutic strategies targeting the integrated HIV provirus.

Human immunodeficiency virus (HIV) infection remains an important global public health problem. About 40 million people are infected with HIV, and this infection caused about 630,000 deaths in 2022. The hallmark of HIV infection is the depletion of CD4+ T helper lymphocytes (Th cells). There are at least seven different Th subtypes, and not all are the main targets of HIV. Moreover, the effect of the virus in a specific subtype can be completely different from that of the others. Although the most compromised Th subtype in HIV infection is Th17, HIV can induce important dysregulations in other subtypes, such as follicular Th (Tfh) cells and regulatory Th cells (Treg cells or Tregs). Several studies have shown that HIV can induce an increase in the immunosuppressive activity of Tregs without causing a significant reduction in their numbers, at least in the early phase of infection. The increased activity of this Th subtype seems to play an important role in determining the immunodeficiency status of HIV-infected patients, and Tregs may represent a new target for innovative anti-HIV therapies, including the so-called “Kick and Kill” therapeutic method whose goal is the complete elimination of the virus and the healing of HIV infection. In this review, we report the most important findings on the effects of HIV on different CD4+ T cell subtypes, the molecular mechanisms by which the virus impairs the functions of these cells, and the implications for new anti-HIV therapeutic strategies.

The signal transducer and activator of transcription (STAT) 1 protein plays a key role in the immune response against viruses and other pathogens by transducing, in the nucleus, the signal from type I, type II and type III IFNs. STAT1 activates the transcription of hundreds of genes, some of which have been well characterized for their antiviral properties. STAT1 gene deletion in mice and complete STAT1 deficiency in humans both cause rapid death from severe infections. STAT1 plays a key role in the immunoglobulin class-switch recombination through the upregulation of T-bet; it also plays a key role in the production of T-bet+ memory B cells that contribute to tissue-resident humoral memory by mounting an IgG response during re-infection. Considering the key role of STAT1 in the antiviral immune response, many viruses, including dangerous viruses such as Ebola and SARS-CoV-2, have developed different mechanisms to inhibit this transcription factor. The search for drugs capable of targeting the viral proteins implicated in both viral replication and IFN/STAT1 inhibition is important for the treatment of the most dangerous viral infections and for future viral pandemics, as shown by the clinical results obtained with Paxlovid in patients infected with SARS-CoV-2.

Background: Chagas disease, also known as American trypanosomiasis, is a potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi. No progress in the treatment of this pathology has been made since Nifurtimox was introduced more than fifty years ago, and this drug is considered very aggressive and may cause several adverse effects. This drug currently has severe limitations, including a high frequency of undesirable side effects and limited efficacy and availability, so research to discover new drugs for the treatment of Chagas disease is imperative. Many drugs available on the market are natural products as found in nature or compounds designed based on the structure and activity of these natural products. Methods: This study evaluated the in vitro antiparasitic activity of a series of previously synthesized stilbene and terphenyl compounds in T. cruzi epimastigotes and intracellular amastigotes. The action of the most selective compounds was investigated by flow cytometric analysis to evaluate the mechanism of cell death. The ability to induce apoptosis or caspase-1 inflammasomes was assayed in macrophages infected with T. cruzi after treatment, comparing it with that of Nifurtimox. Results: The stilbene ST18 was the most potent compound of the series. It was slightly less active than Nifurtimox in epimastigotes but most active in intracellular amastigotes. Compared to Nifurtimox, it was markedly less cytotoxic when tested in vitro on normal cells. ST18 was able to induce a marked increase in parasites positive for Annexin V and monodansylcadaverine. Moreover, ST18 induced the activation, in infected macrophages, of caspase-1, a conserved enzyme that plays a major role in controlling parasitemia, host survival and the onset of the adaptive immune response in Trypanosoma infection. Conclusions: The antiparasitic activity of ST18 together with its ability to activate caspase-1 in infected macrophages and its low toxicity toward normal cells makes this compound interesting for further clinical investigation.