Thymic plasmacytoid dendritic cells are susceptible to productive HIV-1 infection and efficiently transfer R5 HIV-1 to thymocytes in vitro

<p>Abstract</p> <p>Background</p> <p>HIV-1 infection of the thymus contributes to the defective regeneration and loss of CD4⁺T cells in HIV-1-infected individuals. As thymic dendritic cells (DC) are permissive to infection by HIV-1, we examined the ability of thymic DC to enhance infection of thymocytes which may contribute to the overall depletion of CD4⁺T cells. We compared productive infection in isolated human thymic and blood CD11c⁺myeloid DC (mDC) and CD123⁺plasmacytoid DC (pDC) using enhanced green fluorescent protein (EGFP) CCR5 (R5)-tropic NL(AD8) and CXCR4 (X4)-tropic NL4-3 HIV-1 reporter viruses. Transfer of productive HIV-1 infection from thymic mDC and pDC was determined by culturing these DC subsets either alone or with sorted thymocytes.</p> <p>Results</p> <p>Productive infection was observed in both thymic pDC and mDC following exposure to R5 HIV-1 and X4 HIV-1. Thymic pDC were more frequently productively infected by both R5 and X4 HIV-1 than thymic mDC (p = 0.03; n = 6). Thymic pDC efficiently transferred productive R5 HIV-1 infection to both CD3^hi(p = 0.01; mean fold increase of 6.5; n = 6) and CD3^lothymocytes (mean fold increase of 1.6; n = 2). In comparison, transfer of productive infection by thymic mDC was not observed for either X4 or R5 HIV-1.</p> <p>Conclusions</p> <p>The capacity of thymic pDC to efficiently transfer R5 HIV-1 to both mature and immature thymocytes that are otherwise refractory to R5 virus may represent a pathway to early infection and impaired production of thymocytes and CD4⁺T cells in HIV-1-infected individuals.</p

Human Immunodeficiency Virus (HIV)-Infected CCR6+ Rectal CD4+ T Cells and HIV Persistence On Antiretroviral Therapy.

BackgroundIdentifying where human immunodeficiency virus (HIV) persists in people living with HIV and receiving antiretroviral therapy is critical to develop cure strategies. We assessed the relationship of HIV persistence to expression of chemokine receptors and their chemokines in blood (n = 48) and in rectal (n = 20) and lymph node (LN; n = 8) tissue collected from people living with HIV who were receiving suppressive antiretroviral therapy.MethodsCell-associated integrated HIV DNA, unspliced HIV RNA, and chemokine messenger RNA were quantified by quantitative polymerase chain reaction. Chemokine receptor expression on CD4+ T cells was determined using flow cytometry.ResultsIntegrated HIV DNA levels in CD4+ T cells, CCR6+CXCR3+ memory CD4+ T-cell frequency, and CCL20 expression (ligand for CCR6) were highest in rectal tissue, where HIV-infected CCR6+ T cells accounted for nearly all infected cells (median, 89.7%). Conversely in LN tissue, CCR6+ T cells were infrequent, and there was a statistically significant association of cell-associated HIV DNA and RNA with CCL19, CCL21, and CXCL13 chemokines.ConclusionsHIV-infected CCR6+ CD4+ T cells accounted for the majority of infected cells in rectal tissue. The different relationships between HIV persistence and T-cell subsets and chemokines in rectal and LN tissue suggest that different tissue-specific strategies may be required to eliminate HIV persistence and that assessment of biomarkers for HIV persistence may not be generalizable between blood and other tissues

Broad activation of latent HIV-1 in vivo

The 'shock and kill' approach to cure human immunodeficiency virus (HIV) includes transcriptional induction of latent HIV-1 proviruses using latency-reversing agents (LRAs) with targeted immunotherapy to purge infected cells. The administration of LRAs (panobinostat or vorinostat) to HIV-1-infected individuals on antiretroviral therapy induces a significant increase in cell-associated unspliced (CA-US) HIV-1 RNA from CD4(+) T cells. However, it is important to discern whether the increases in CA-US HIV-1 RNA are due to limited or broad activation of HIV-1 proviruses. Here we use single-genome sequencing to find that the RNA transcripts observed following LRA administration are genetically diverse, indicating activation of transcription from an extensive range of proviruses. Defective sequences are more frequently found in CA HIV-1 RNA than in HIV-1 DNA, which has implications for developing an accurate measure of HIV-1 reservoir size. Our findings provide insights into the effects of panobinostat and vorinostat as LRAs for latent HIV-1

Understanding factors that modulate the establishment of HIV latency in resting CD4+ T-Cells in <i>vitro</i>

Developing robust in vitro models of HIV latency is needed to better understand how latency is established, maintained and reversed. In this study, we examined the effects of donor variability, HIV titre and co-receptor usage on establishing HIV latency in vitro using two models of HIV latency. Using the CCL19 model of HIV latency, we found that in up to 50% of donors, CCL19 enhanced latent infection of resting CD4+ T-cells by CXCR4-tropic HIV in the presence of low dose IL-2. Increasing the infectious titre of CXCR4-tropic HIV increased both productive and latent infection of resting CD4+ T-cells. In a different model where myeloid dendritic cells (mDC) were co-cultured with resting CD4+ T-cells, we observed a higher frequency of latently infected cells in vitro than CCL19-treated or unstimulated CD4+ T-cells in the presence of low dose IL-2. In the DC-T-cell model, latency was established with both CCR5- and CXCR4-tropic virus but higher titres of CCR5-tropic virus was required in most donors. The establishment of latency in vitro through direct infection of resting CD4+ T-cells is significantly enhanced by CCL19 and mDC, but the efficiency is dependent on virus titre, co-receptor usage and there is significant donor variability

Baseline characteristics, telomere length and telomerase activity by treatment arm.

<p>T/S ratio: TL was expressed as a ratio to a single (S) copy housekeeping gene 36B4 (T/S ratio). All parameters are shown as mean (SD), unless otherwise stated.</p><p>Baseline characteristics, telomere length and telomerase activity by treatment arm.</p