Biology subjects

Pasternak, A. O.

Publications and source records attributed to Pasternak, A. O..

3 recordsLinked to original sources

bioRxiv2025

Pure CD32+ CD4+ Cells Are Cytotoxic Memory CD4+ T Lymphocytes Highly Enriched for HIV-1 DNA

The elusive viral reservoir is the major obstacle to an HIV-1 cure. Cell surface protein CD32 has been proposed to pinpoint cells with a very high proviral enrichment, potentially providing a tool for selective therapeutic targeting of the reservoir. However, this finding has been challenged by subsequent reports. In order to clarify the nature of CD32 expression on CD4+ T cells, here we designed a purification strategy allowing single-cell analysis using state-of-the-art technologies. The established multilevel sorting strategy allowed to characterize a rare (median 0.06% of CD4+ T cells) but bona fide CD32+ CD4+ T-cell population. In vitro cell stimulation could not lead to CD32 upregulation. Detailed phenotyping revealed that CD32+ T cells reside mostly in the memory T-cell compartment with heightened levels of acute and chronic activation markers. Single-cell RNA sequencing identified that CD32+ CD4+ T cells are mostly highly cytotoxic CD4+ cells. Importantly. in HIV-1 infected donors under suppressive antiretroviral therapy, we found that these cells are highly enriched for HIV-1 provirus, harbor a clear cytotoxic memory T-cell transcriptome, as well as TCR clonal enrichment. These findings indicate that CD32 remains a promising candidate marker of the HIV-1 reservoir and underline the importance of further investigation of this marker during latent infection.

immunology↗

bioRxiv2025

HIV-specific CD8+ T-cell responses soon after treatment initiation during acute HIV infection are associated with viral reservoir decline

Antiretroviral therapy (ART) initiated in the acute phase of HIV infection (AHI) results in a smaller viral reservoir. However, the impact of early HIV-specific T-cell responses on long- term reservoir dynamics is less well characterized. Therefore, we measured the size of the viral reservoir and functionality of HIV-specific CD8+ T-cell responses after the acute phase at 24 and 156 weeks after ART initiation in individuals who started treatment during AHI. A significant reduction in total and defective HIV DNA and a trend towards a reduction in intact HIV DNA were observed between 24 and 156 weeks. Functional CD8+ T-cell responses against HIV peptides Env, Gag, Nef, and Pol were maintained over three years after treatment initiation. The proliferative capacity of HIV-specific CD8+ T cells at 24 weeks of ART was predictive of the degree of reduction in total and defective HIV DNA between 24 and 156 weeks, suggesting HIV-specific CD8+ T-cells may at least partially drive the decline of the viral reservoir. Therefore, enforcing HIV-specific immune responses as early as possible after diagnosis of AHI should be a central focus of HIV cure strategies.

immunology↗

bioRxiv2021

Novel Role of UHRF1 in DNA methylation-mediated repression of latent HIV-1

The multiplicity, heterogeneity and dynamic nature of HIV-1 latency mechanisms are reflected in the current lack of functional cure for HIV-1 and in the various reported ex vivo potencies of latency- reversing agents. Here, we investigated the molecular mechanisms underlying the potency of the DNA methylation inhibitor 5-aza-2-deoxycytidine (5-AzadC) in HIV-1 latency reversal. Doing so, we uncovered specific demethylation CpG signatures induced by 5-AzadC in the HIV-1 promoter. By analyzing the binding modalities to these CpG, we revealed the recruitment of the epigenetic integrator UHRF1 to the HIV-1 promoter. We further demonstrated the role of UHRF1 in DNA methylation- mediated silencing of the latent HIV-1 promoter. As a proof-of-concept to this molecular characterization, we showed that pharmacological downregulation of UHRF1 in ex vivo HIV+ patient cell cultures resulted in potent reactivation of latent HIV-1. Together, we identify UHRF1 as a novel actor in HIV-1 gene silencing and highlight that it constitutes a new molecular target for HIV-1 curative strategies.

microbiology↗