754
Compartmental Kinetics of Intracellular Tenofovir
Courtney Fletcher*1, T King1, L Bushman1, J Kiser1, P Anderson1, J Brenchley2, D Douek2, and T Schacker3
1Univ of Colorado Hlth Sci Ctr, Denver, US; 2NIAID, NIH, Bethesda, MD, US; and 3Univ of Minnesota, Minneapolis, US
Background: The contribution of pharmacologic
characteristics of antiretroviral (ARV) drugs, such as influx, efflux and phosphorylation
in the case of NRTI, to persistent HIV replication in reservoir sites is
unknown. The objective of this work was to examine intracellular
tenofovir-diphosphate (TFV-DP) concentrations in peripheral blood mononuclear
cells (PBMC) and lymphocytes from lymph node tissue in HIV-infected persons.
Methods: Paired PBMC and lymph node tissue were
obtained from 7 HIV-infected persons participating in a study of antiretroviral
therapy. An inguinal lymph node was biopsied after subjects had received ART
for at least 4 weeks; lymphocytes were isolated from lymph node stromal cells. A
paired venous sample was obtained and PBMC were isolated by density
centrifugation. TFV-DP concentrations were quantified by high-performance
liquid chromatography-mass spectrometry/mass spectrometry.
Results: In these 7 persons, plasma HIV RNA ranged
from <75 to 7547 copies/mL, and CD4 count from 8 to 941 cells/µL at the time
of sample collection. Median TFV-DP in PBMC was 21 (range, 9 to 62) fmol/106
cells. Median TFV-DP in lymph node was 16 (range, 6 to 41) fmol/106
cells. The median lymph node:PBMC ratio of TFV-DP was 0.55 (range, 0.35 to
1.19). The TFV-DP lymph node:PBMC ratio was highest in the participant with the
lowest peripheral blood CD4 cell count (1.19) and lowest in the subject who had
the highest CD4 cell count (0.35). Lymphocytes from gut-associated lymphoid
tissue (GALT) were obtained in one subject: the TFV-DP GALT:PBMC ratio was
0.30 and lymph node:PBMC was 0.76.
Conclusions: Concentrations of TFV-DP, the
pharmacologic active moiety, were quantified in lymphocytes from lymph node
tissue, and in GALT from the one subject sampled. The median ratio of lymph
node to PBMC was 0.55, indicating lower concentrations in the lymph node
compartment. One hypothesis to explain these findings is NRTI phosphorylation
in lymph node and GALT is a function of the cell-activation dependence of the
NRTI and the activation state of these compartments. This study demonstrated
that quantitation of TFV phosphorylated anabolite in lymph node and GALT is
feasible. Together with the observation that TFV-DP concentrations in lymph
node were less than in PBMC, these findings open a new area of research to
evaluate if these pharmacologic characteristics of NRTI contribute to
persistent HIV replication in reservoir sites.
|
