ABSTRACT
BACKGROUND: Recent studies have shown that blood monocytes harbor human immunodeficiency virus type 1 (HIV-1) variants that are genotypically distinguishable from those in CD4(+) T cells. However, the biological function of monocyte-derived HIV-1 remains unclear. METHODS: Using pseudovirus assay, we analyzed the phenotype conferred by monocyte-derived HIV-1 envelopes from 8 patients. RESULTS: All pseudoviruses carrying monocyte-derived HIV-1 envelopes used CCR5; however, their use of additional coreceptors delineated 4 phenotypes in which viruses used (1) CCR5 only, (2) CCR5 and CXCR4, (3) CCR3 and CCR5, or (4) multiple coreceptors, including CCR1, CCR3, GPR15, CCR5, and CXCR4. More importantly, we observed 2 distinct cell tropism phenotypes for pseudoviruses carrying monocyte-derived envelopes: (1) monocyte-derived, macrophage-specific R5 (MDMS-R5) virus that, using CCR5 only, could infect monocyte-derived macrophages (MDMs) but not CD4(+) T cells and (2) dual tropic virus that infected both MDMs and primary CD4(+) T cells. We found blood monocytes harboring viruses with multiple phenotypes as early as 25 days before seroconversion and as late as 9 years after seroconversion. CONCLUSIONS: These data suggest that HIV-1 circulating in blood monocytes represents diverse HIV-1 with multiple phenotypes and that MDMS-R5 viruses may play an important role in infection with and persistence of HIV-1 within the monocyte/macrophage lineage.
Subject(s)
HIV-1/classification , Macrophages/virology , Monocytes/virology , Receptors, CCR5/metabolism , Adult , Amino Acid Sequence , CD4-Positive T-Lymphocytes/virology , Female , HIV Envelope Protein gp120/chemistry , HIV Envelope Protein gp120/genetics , HIV Infections , HIV-1/isolation & purification , HIV-1/metabolism , HIV-1/pathogenicity , Humans , Male , Middle Aged , Peptide Fragments/chemistry , Peptide Fragments/genetics , Phenotype , Sequence AlignmentABSTRACT
The pharmacologic variability of nucleoside reverse transcriptase inhibitors such as lamivudine (3TC) includes not only systemic pharmacokinetic variability but also interindividual differences in cellular transport and metabolism. A modeling strategy linking laboratory studies of intracellular 3TC disposition with clinical studies in adolescent patients is described. Data from ex vivo laboratory experiments using peripheral blood mononuclear cells (PBMCs) from uninfected human subjects were first used to determine a model and population parameter estimates for 3TC cellular metabolism. Clinical study data from human immunodeficiency virus type 1-infected adolescents were then used in a Bayesian population analysis, together with the prior information from the ex vivo analysis, to develop a population model for 3TC systemic kinetics and cellular kinetics in PBMCs from patients during chronic therapy. The laboratory results demonstrate that the phosphorylation of 3TC is saturable under clinically relevant concentrations, that there is a rapid equilibrium between 3TC monophosphate and diphosphate and between 3TC diphosphate and triphosphate, and that 3TC triphosphate is recycled to 3TC monophosphate through a 3TC metabolite that remains to be definitively characterized. The resulting population model shows substantial interindividual variability in the cellular kinetics of 3TC with population coefficients of variation for model parameters ranging from 47 to 87%. This two-step ex vivo/clinical modeling approach using Bayesian population modeling of 3TC that links laboratory and clinical data has potential application for other drugs whose intracellular pharmacology is a major determinant of activity and/or toxicity.
Subject(s)
Anti-HIV Agents/metabolism , HIV Infections/drug therapy , HIV-1 , Lamivudine/metabolism , Leukocytes, Mononuclear/metabolism , Reverse Transcriptase Inhibitors/metabolism , Adolescent , Adult , Anti-HIV Agents/pharmacokinetics , Bayes Theorem , Cross-Over Studies , HIV Infections/metabolism , Humans , Lamivudine/administration & dosage , Lamivudine/pharmacokinetics , Models, Biological , Reverse Transcriptase Inhibitors/pharmacokineticsABSTRACT
OBJECTIVE: As tenofovir disoproxil fumarate substantially increases plasma concentrations of didanosine in patients with human immunodeficiency virus-1 infection, we sought to determine whether tenofovir and didanosine showed a similar intracellular interaction in human peripheral blood mononuclear cells (PBMCs). DESIGN: Comparative in vitro incubation of two antiretrovirals in lymphocytes. SETTING: Clinical research laboratory. MATERIAL: Radiolabeled tenofovir and didanosine in human PBMCs. MEASUREMENTS AND MAIN RESULTS: Phosphorylation of 2 and 20 microM didanosine to dideoxyadenosine triphosphate (ddATP) was determined in quiescent and stimulated PBMCs in the presence or absence of 5 microM tenofovir. Similarly, phosphorylation of 5 microM tenofovir to tenofovir diphosphate (TFVpp) was examined in the presence or absence of 2 and 20 microM didanosine. Intracellular amounts of ddATP and TFVpp were determined by incubating PBMCs with radiolabeled tenofovir or didanosine alone and together for up to 16 hours and then separating the anabolites by high-performance liquid chromatography for quantitation. The presence of tenofovir did not affect the amount of ddATP in quiescent or stimulated PBMCs with 2 or 20 microM didanosine. In addition, didanosine did not alter the amount of TFVpp that formed. The amount of ddATP was modestly (1.5-3-fold) but consistently higher in stimulated than in quiescent PBMCs, but the amount of TFVpp did not differ. CONCLUSION: There is no significant interaction between tenofovir and didanosine in human PBMCs as determined by the extent of formation of the phosphorylated anabolites. This suggests that adjusting didanosine dosage, when given with tenofovir, to achieve similar didanosine plasma concentrations, may be sufficient to accommodate the systemic drug interaction.
