P15.24
Background: The conflicting results of recent pre-exposure prophylaxis (PrEP) trials utilizing tenofovir (TFV) for the prevention of HIV infection in women led us to evaluate intracellular TFV-diphosphate (TFV-DP) in cells from the FRT and whether estradiol (E2) and progesterone (P4) influence the presence of TFV-DP in these cells.
Methods: FRT tissues were obtained following hysterectomy for benign reasons from HIV-negative women. Epithelial cells (EC), fibroblasts and CD4+ T cells from the ectocervix (ECX) endocervix (CX) endometrium (EM) were isolated by enzymatic digestion and/or magnetic bead purification. Cells were treated with TFV for 24hr and intracellular TFV-DP measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS).
Results: We found that TFV-DP concentrations vary significantly with the cell type analyzed and the site in the FRT. EM-EC had 2-fold higher TFV-DP than EC from the CX and ECX. TFV-DP in fibroblasts from EM, CX and ECX were comparable. Concentrations of TFV-DP in EC were ∼5-fold greater than that seen in fibroblasts. In studies with E2 and P4 added in culture to FRT cells, E2 increased TFV-DP in EM, CX/ECX epithelial cells, but had no effect on fibroblasts or CD4+ T cells from FRT tissues. In contrast, P4 alone and in combination with E2 decreased TFV-DP concentrations in FRT CD4+ T cells.
Conclusions: These results demonstrate that TFV-DP is produced by multiple cell types throughout the FRT and that intracellular concentrations vary with the cell type analyzed. Our results suggest that TFV-DP concentrations in epithelial cells and fibroblasts may either be a repository for TFV-DP, which when converted to TFV is available for protection of CD4+ T cells and macrophages, or a potential sink, which interferes with TFV-DP target cell availability. Further, these results indicate that E2 and/or P4 regulate the intracellular concentrations of TFV-DP in epithelial cells and CD4+ T cells and that intracellular TFV-DP varies with cell type and location in the FRT.
