Biology subjects

Swartz, T. H.

Publications and source records attributed to Swartz, T. H..

4 recordsLinked to original sources

bioRxiv2026

A transcriptional continuum links viral burden and host-cell biology in human lymphoid tissue

Human immunodeficiency virus (HIV-1) persistence in lymphoid tissue remains a major barrier to cure, yet infected cells are commonly represented using discrete categories that may obscure biologically meaningful heterogeneity. Using an ex vivo human tonsil explant model and single-cell RNA sequencing of more than 42,000 T cells, we show that HIV transcription spans a structured continuum and that viral transcriptional burden functions as an organizing axis of host-cell biology. Across the continuum, increasing HIV transcription is associated with coordinated remodeling of immune, inflammatory, metabolic, and redox-associated programs. Lower transcriptional tiers were enriched for innate sensing and inflammasome-associated responses, whereas higher tiers exhibited activation of oxidative phosphorylation and redox-buffering pathways. Antiretroviral therapy preferentially depleted highly transcriptionally active populations while preserving lower and intermediate tiers, resulting in compression rather than elimination of the continuum. Together, these findings provide a quantitative framework for interpreting HIV transcriptional heterogeneity within human lymphoid tissue and suggest that persistent viral activity reflects a spectrum of host-virus states rather than a single infected-cell population. By linking viral transcriptional burden to distinct host-cell programs, this framework may inform future strategies to reduce HIV persistence and its associated inflammatory consequences.

immunology↗

bioRxiv2023

HIV-1 infection of genetically engineered iPSC-derived central nervous system-engrafted microglia in a humanized mouse model

The central nervous system (CNS) is a major human immunodeficiency virus type 1 reservoir. Microglia are the primary target cell of HIV-1 infection in the CNS. Current models have not allowed the precise molecular pathways of acute and chronic CNS microglial infection to be tested with in vivo genetic methods. Here, we describe a novel humanized mouse model utilizing human-induced pluripotent stem cell-derived microglia to xenograft into murine hosts. These mice are additionally engrafted with human peripheral blood mononuclear cells that served as a medium to establish a peripheral infection that then spread to the CNS microglia xenograft, modeling a trans-blood-brain barrier route of acute CNS HIV-1 infection with human target cells. The approach is compatible with iPSC genetic engineering, including inserting targeted transgenic reporter cassettes to track the xenografted human cells, enabling the testing of novel treatment and viral tracking strategies in a comparatively simple and cost-effective way vivo model for neuroHIV. ImportanceOur mouse model is a powerful tool for investigating the genetic mechanisms governing CNS HIV-1 infection and latency in the CNS at a single-cell level. A major advantage of our model is that it uses iPSC-derived microglia, which enables human genetics, including gene function and therapeutic gene manipulation, to be explored in vivo, which is more challenging to study with current hematopoietic stem cell-based models for neuroHIV. Our transgenic tracing of xenografted human cells will provide a quantitative medium to develop new molecular and epigenetic strategies for reducing the HIV-1 latent reservoir and to test the impact of therapeutic inflammation-targeting drug interventions on CNS HIV-1 latency.

neuroscience↗

bioRxiv2019

P2X1 selective antagonists block HIV-1 infection through inhibition of envelope conformation-dependent fusion

Purinergic receptors detect extracellular ATP and promote inflammatory processes. Emerging literature has demonstrated that inhibition of these proinflammatory receptors can block HIV-1 productive infection. The specificity of receptor type and mechanism of interaction has not yet been determined. Here we characterize the inhibitory activity of P2X1 receptor antagonists, NF279 and NF449 in cell lines, primary cells, and in a variety of envelope clades. NF279 and NF449 blocked productive infection at the level of viral membrane fusion with a range of inhibitory activities against different HIV-1 envelopes. A mutant virus carrying a truncation deletion of the C-terminal tail of HIV-1 envelope (Env) glycoprotein 41 (gp41) showed reduced sensitivity to P2X1 antagonists, indicating that the sensitivity of inhibition by these molecules is modulated by Env conformation. By contrast, a P2X7 antagonist, A438079, had limited effect on productive infection and fusion. Inhibition with NF449 interfered with the ability of the V1V2 targeted broadly neutralizing antibody PG9 to block productive infection, suggesting that these drugs may antagonize HIV-1 Env at gp120 V1V2 to block viral membrane fusion. Our observations indicate that P2X1 antagonism can inhibit HIV-1 replication at the level of viral membrane fusion through interaction with Env. Future studies will probe the nature of these compounds in inhibiting HIV-1 fusion and in development of a different class of small molecules to block HIV-1 entry.\n\nIMPORTANCEWhile effective treatment can lower the severe morbidity and mortality associated with HIV-1 infection, patients infected with HIV-1 suffer from significantly higher rates of non-communicable comorbidities associated with chronic inflammation. Emerging literature suggests a key role for P2X1 receptors in mediating this chronic inflammation but the mechanism is still unknown. Here, we demonstrate that HIV-1 infection is reduced by P2X1 receptor antagonism. This inhibition is mediated by interference with HIV-1 Env and can impact a variety of viral clades. These observations highlight the importance of P2X1 antagonists as potential novel therapeutics that could serve to block a variety of different viral clades with additional benefits for their anti-inflammatory properties.

microbiology↗

bioRxiv2018

P2X antagonists inhibit HIV-1 productive infection and inflammatory cytokines IL-10 and IL-1β in a human tonsil explant model

HIV-1 causes a persistent infection of the immune system that is associated with chronic comorbidities. The mechanisms that underlie this inflammation are poorly understood. Emerging literature has implicated pro-inflammatory purinergic receptors and downstream signaling mediators in HIV-1 infection. This study probed whether inhibitors of purinergic receptors would reduce HIV-1 infection and HIV-1 stimulated inflammation. A human ex vivo human tonsil histo-culture infection model was developed to support HIV-1 productive infection and stimulated inflammatory cytokine interleukin-1 beta (IL-1{beta}) and immunosuppressive cytokine, interleukin-10 (IL-10). This study tests whether inhibitors of purinergic receptors would reduce HIV-1 infection and HIV-1 stimulated inflammation. The purinergic P2X1 receptor antagonist, NF449, the purinergic P2X7 receptor antagonists, A438079, and azidothymidine (AZT) were tested in HIV-1 infected human tonsil explants to compare inhibition of HIV-1 infection and HIV-stimulated inflammatory cytokine production. All drugs limited HIV-1 productive infection but P2X-selective antagonists (NF449, and A438079) significantly lowered HIV-stimulated IL-10 and IL-1{beta}. We further observed that P2X1- and P2X7-selective antagonists can act differentially as inhibitors of both HIV-1 infection and HIV-1-stimulated inflammation. Our findings highlight the differential effects of HIV-1 on inflammation in peripheral blood as compared to lymphoid tissue. For the first time, we demonstrate that P2X-selective antagonists act differentially as inhibitors of both HIV-1 infection and HIV-1-stimulated inflammation. Drugs that block these pathways can have independent inhibitory activities against HIV-1 infection and HIV-induced inflammation.\n\nImportancePatients who are chronically infected with HIV-1 experience sequelae related to chronic inflammation. The mechanisms of this inflammation have not been elucidated. Here we describe a class of drugs that target the P2X pro-inflammatory signaling receptors in a human tonsil explant model. This model highlights differences in HIV-1 stimulation of lymphoid tissue inflammation and peripheral blood. These drugs serve to both block HIV-1 infection and production of IL-10 and IL-1{beta} in lymphoid tissue suggesting a novel approach to HIV-1 therapeutics in which both HIV-1 replication and inflammatory signaling are simultaneously targeted.

immunology↗