Background
Latency reversing agents (LRAs) such as TLR agonists and histone deacetylase (HDAC) inhibitors reactivate HIV-1 from latency in adults. We examined the immune effects of the TLR7 agonist GS-9620, alone and in combination with the HDAC inhibitor SAHA, in ex-vivo studies of adolescents with perinatal HIV-1 (AdLWPH), aiming to inform latency reversal strategies for this population.
Methods
Enriched CD4 T cells from 16 AdLWPH (median age 17.8[IQR, 13.8-20.1] yrs; median virologic suppression of 10.4[6-16.2] yrs; 81.3% female) were stimulated with GS-9620, SAHA, or in combination. PHA/PMA/Ionomycin (PPI) and vehicle control (VC) were studied in parallel. HIV-1 reservoir size was measured by the intact proviral DNA assay. Proviral transcription was assessed by induction of multiply spliced (ms) tat/rev HIV-1 RNA transcripts (msRUPM) with the Tat/Rev Limiting Dilution Assay (TILDA). LRA immune effects were analyzed by flow cytometry for immune activation markers. Transcriptomic effects were examined by bulk RNA-seq in 7 participants (71.4% female) for all treatment groups. Participants were categorized as high or low responders based on fold change of msRUPM (>1.1); differential gene expression analyses were applied.
Results
The median intact HIV-1 DNA load was 15.8[4.7-50.0] copies/106 CD4 T cells. With VC, ms-HIV-1 RNA transcripts were detected in 12/16 participants (range 1-22.3). PPI, GS-9620, and GS-9620+SAHA increased ms-HIV-1 RNA relative to VC by 2.0-,1.4- and 1.6-fold. The proportion of intact proviruses induced was significantly increased relative to VC with PPI and GS-9620. PPI was associated with upregulation of activation markers CD69, CD25, and HLA DR, whereas GS-9620, SAHA or the combination were only associated with CD69 upregulation. Across all treatment conditions, IFNγ response was associated with high msRUPM. Without LRA stimulation, IFNγ and IFNα upregulation was associated with high basal msRUPM. IFNγ response was also associated with high msRUPM across all conditions. High GS-9620 responders had upregulation of IFNα, TNFα and IL-2, while high SAHA responders had upregulated TGF-β. High GS-9620+SAHA responders had upregulated TNFα, interferon and estrogen responses (Table 1).
Conclusions
HIV-1 reservoirs in perinatal infections are susceptible to reactivation with TLR7 agonists and HDAC inhibitors through upregulation of pro-inflammatory pathways mediated by IFNs, TGF- β, TNFα and IL-2, offering insights into proviral reactivation and control for AdLWPH.