Background
Clonal expansion of HIV infected CD4+ T cells is a barrier to HIV eradication. Previous studies suggested that blocking cell proliferation can accelerate reservoir decay. We recently described a marked reduction in clonally expanded infected CD4+ T cells in a patient with elite control (ES24) after chemoradiation for lung cancer with paclitaxel and carboplatin. We tested the hypothesis that this phenomenon was due to a higher susceptibility of frequently proliferating CD4+ T cell clones to the chemotherapeutic drugs.
Methods
We studied a large CD4+ T cell clone with replication-competent provirus integrated into the ZNF721 gene (ZNF721i), which has been linked to the persistence of intact proviruses. We stimulated CD8-depleted PBMCs from ES24 with the cognate peptide for the ZNF721i clone (peptide 61: Gag 241-255) for 20 hours on day 1. On day 5, the cells were exposed to paclitaxel and/or carboplatin, or the antiproliferative drug, mycophenolate mofetil (MMF). The cells were harvested on days 7 to 9. The frequency of total HIV DNA and the ZNF721i cells was determined by LTR and integration site-specific digital PCR. Single-cell transcriptome analysis and T cell receptor sequencing was also performed on day 7 CD4+ T cells.
Results
There was a 25-to-30-fold increase in the frequency of ZNF721i cells after treatment of cells with peptide 61. The expanded ZNF721i cells had the phenotype of proliferating (MKI67, CDT1) cytotoxic (CCL5, GZMK, NGK7) CD4+ T cells. Both paclitaxel and MMF completely abrogated peptide induced expansion of ZNF721 cells, resulting in a transcriptome signature of cell cycle arrest in the G2 phase. In contrast, carboplatin had no effect. Other peptide-reactive clonotypes were similarly affected, but the drugs did not deplete expanded clones that were not specific for peptide 61.
Conclusions
This strategy of antigen-specific stimulation followed by treatment with an antiproliferative agent may lead to the selective elimination of clonally expanded HIV infected cells.