Toll-like Receptor Agonists Enhance HIV-specific T Cell Response Mediated by Plasmacytoid Dendritic Cells in Diverse HIV-1 Disease Progression Phenotypes

Plasmacytoid dendritic cells (pDCs) sense viral and bacterial products through Toll-like receptor (TLR)-7 and -9 and translate this sensing in Interferon-α (IFN-α) production and T cell polarization. These cells are considered a link between innate and adaptive immunity, inducing and maintaining antigen-specific T cell responses and contributing to the control and eventually to the chronic immune activation and disease progression in HIV-1 infection scenario. The understanding of the mechanisms involved in pDCs stimulation may contribute to immunotherapeutic strategies aiming to decrease HIV-1 reservoir. The objective of the present study was to characterize the immunomodulatory effects of TLR agonist stimulations through a pDC/T cell coculture in different HIV-1 disease progression phenotypes and healthy donors (HD). pDCs were previously stimulated with AT-2-HIV-1, CpGA, CpGC and GS9620. After coculture with autologous CD4 or CD8 T cells we observed an increase of pDCs activation markers levels, interferon related genes, HIV-1 restriction factors and cytokines levels. This pDCs coordinate activation was prominent with CpG-C and GS9620 and induced an increase of HIV-specific T cell response. This pDCs dependent HIV-1 specific T-cell response was associated with the upregulation of HIV-1 restriction factors and IFN-α production. Interestingly, pDCs activation in people on ART was similar to that found in people that spontaneously control the virus. These results shed light on the mechanisms associated with TLR-specific pDCs stimulation associated with T cell polarization for eliciting antiviral response which is essential for HIV eradication strategies.