Abstract
Anti-retroviral (ARV) –based microbicides are one of the strategies pursued to prevent HIV-1 transmission. Delivery of ARV drugs to subepithelial CD4+ T cells at concentrations for protection is likely determined by drug transporters expressed in the cervicovaginal epithelium. To define the role of drug transporters in mucosal disposition of topically applied ARV-based microbicides, these must be tested in epithelial cell line-based biopharmaceutical assays factoring the effect of relevant drug transporters. We have characterised gene expression of influx and efflux drug transporters in a panel of cervicovaginal cell lines and compared this to expression in cervicovaginal tissue. We also investigated the effect of dapivirine, darunavir and tenofovir, currently at advanced stages of microbicides development, on expression of drug transporters in cell lines. Expression of efflux ABC transporters in cervical tissue was best represented in HeLa, Ect1/E6E7 and End1/E6E7 cell lines. Expression of influx OCT and ENT transporters in ectocervix matched expression in Hela while expression of influx SLCO transporters in vagina was best reflected in VK2/E6E7 cell line. Stimulation with darunavir and dapivirine upregulated MRP transporters, including MRP5 involved in transport of tenofovir. Dapivirine also significantly downregulated tenofovir substrate MRP4 in cervical cell lines. Treatment with darunavir and dapivirine showed no significant effect on expression of BCRP, MRP2 and P-glycoprotein implicated in efflux of different ARV drugs. Darunavir strongly induced expression in most cell lines of CNT3 involved in cell uptake of nucleotide/nucleoside analogue reverse transcriptase inhibitors and SLCO drug transporters involved in cell uptake of protease inhibitors. This study provides insight into the suitability of cervicovaginal cell lines for assessment of ARV drugs in transport kinetics studies. The modulatory effect of darunavir and dapivirine on expression of drug transporters involved in transport of tenofovir points to the possibility of combining these drugs to improve retention of individual drugs at target tissues.
Highlights
Microbicides are one of the strategies pursued to prevent transmission of HIV-1
The following ABC transporters implicated in transport of ARVs were all expressed in ectocervix: P-gp, BCRP, MRP1, MRP2, MRP3, MRP4, MRP5, MRP6 and MRP7 while MRP2, MRP3, MRP4 and MRP6 were not expressed in vaginal samples
Our findings show a good correlation of expression of ABC transporters between HeLa, Ect1/E6E7, End1/E6E7 cells and cervical tissues, except for lower expression of BCRP and P-gp in cell lines compared to ectocervical tissue
Summary
Microbicides are one of the strategies pursued to prevent transmission of HIV-1 They have the potential to inhibit or block early events of HIV-1 infection when applied directly to the vaginal or rectal mucosae. While earlier generation microbicides aimed at disrupting the virus or inhibiting attachment and fusion showed no efficacy in clinical trials [1,2,3,4,5], the CAPRISA 004 trial of vaginally-applied tenofovir gel demonstrated 39% protection against HIV-1 infection providing significant boost for the development of anti-retroviral (ARV)-based microbicides [6]. To exert a protective effect, ARV-based microbicides must cross the cervicovaginal epithelium and distribute to underlying CD4+ T cells which have been confirmed as primary target cells of sexually transmitted HIV-1 particles [10]. The influence of identified drug transporters on the distribution of ARV-based microbicides at target cells of HIV-1 remains to be determined
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