Title: Metabolic activation of 2′, 3′-Didehydro-3′-Deoxythymidine (D4T) in isolated maternal and fetal peripheral blood mononuclear cells at term gestation
Abstract: Administration of anti-HIV drugs to HIV-infected pregnant women during the antepartum period and in labor can reduce the risk of mother-to-child HIV transmission. 2′,3′-Dideoxy-2′,3′-Didehydrothymidine (D4T, stavudine) is a potent antiviral agent for treating HIV-infections. D4T is phosphorylated in cytoplasm of a target cell to produce mono, di, and triphosphate metabolites. The d4T-triphosphate (D4TTP) exerts its antiviral activity by inhibition of HIV reverse transcriptase and termination of viral DNA synthesis. The aims of tudy were to examine the phosphorylation rate and incorporation of d4T into cellular DNA in maternal and fetal isolated peripheral mononuclear cells (PMNCs) at term gestation. Maternal PMNCs were isolated from blood drawn from HIV-seronegative pregnant women (n = 6, 36-40 weeks) prior to delivery. Immediately after delivery, cord blood was collected and fetal PMNCs were isolated. Fresh isolated maternal and fetal PMNCs were maintained in RPMI medium and incubated with [3H]-D4T, 10 μM, 5 μCi/ml, for 24 hrs. Cells were then collected and methanolic extracts were prepared for drug metabolites determination by HPLC. D4T incorporation into cellular DNA was determined by measuring radioactivity in cell pellets. The levels of the mono, and diphosphate of D4T were similar in maternal and fetal PMNCs, while D4TTP levels in fetal PMNCs were significantly higher compared with levels measured in maternal PMNCs, 0.050 ± 0.008 and 0.035 ± 0.011 pmoles/million cells, respectively. Furthermore, no significant difference was found in the levels of D4T incorporated into cellular DNA of maternal and fetal PMNCs, 0.026 ± 0.009 and 0.038 ± 0.027 pmoles/million cells, respectively. Our results demonstrate that fetal PBMCs at term gestation are able to take up D4T and to efficiently generate its active metabolite-D4TTP, even at higher levels than the maternal PBMCs. These results have major importance in enabling better treatment to HIV-infected pregnant women and their fetuses.