Intracellular Tenofovir Diphosphate Levels Research Articles

Correlates of Adherence to Oral and Vaginal Pre-exposure Prophylaxis (PrEP) Among Adolescent Girls and Young Women (AGYW) Participating in the MTN-034/REACH Trial.

We evaluated correlates of adherence to PrEP, including daily oral tenofovir disoproxil fumarate in combination emtricitabine (oral FTC/TDF)and the monthly dapivirine ring (ring)among adolescent girls and young women (AGYW) in the MTN-034/REACH study. We enrolled 247 AGYW aged 16-21years in South Africa, Uganda and Zimbabwe (ClinicalTrials.gov: NCT03074786). Participants were randomized to the order of oral FTC/TDF or ring use for 6months each in a crossover period, followed by a 6-month choice period. We assessed potential adherence correlates-individual, interpersonal, community, study, and product-related factors-quarterly via self-report. We measured biomarkers of adherence monthly; high adherence was defined as > 4mg dapivirine released from returned rings or intracellular tenofovir diphosphate levels ≥ 700 fmol/punch from dried blood spots (DBS). We tested associations between correlates and objective measures of high adherence using generalized estimating equations. High adherence to oral FTC/TDF was significantly associated with having an older primary partner (p = 0.04), not having exchanged sex in the past 3months (p = 0.02), and rating oral FTC/TDF as highly acceptable (p = 0.003). High ring adherence was significantly associated with unstable housing (p = 0.01), disclosing ring use to a male family member (p = 0.01), and noting a social benefit from study participation (p = 0.03). All associations were moderate, corresponding to about 6%-10% difference in the proportion with high adherence. In our multinational study, correlates of adherence among African AGYW differed for oral FTC/TDF and the ring, highlighting the benefit of offering multiple PrEP options.

Experiences of oral pre-exposure prophylaxis (PrEP) use disclosure among South African adolescent girls and young women and its perceived impact on adherence.

There is limited understanding of how social dynamics impact pre-exposure prophylaxis (PrEP) adherence among adolescent girls and young women (AGYW) in generalized HIV-epidemic settings. We examined experiences of oral PrEP use disclosure to various social groups with the goal of identifying supportive relationships that can be leveraged to promote adherence. We used qualitative methods to explore experiences disclosing PrEP use and the perceived impact of disclosure on adherence among 22 South African AGYW (16-25 years) taking daily oral PrEP. Serial in-depth-interviews (IDIs) were conducted 1-, 3-, and 12-months post-PrEP initiation. Respondents also self-reported their disclosures separately for various social groups and adherence was assessed using intracellular tenofovir-diphosphate levels. Qualitative respondents had a median age of 20.5 years and reported disclosing their PrEP use to friends (n = 36 total disclosures), partners, siblings, other family members (n = 24 disclosures each), and parents (n = 19 disclosures). IDI data revealed that parents and partners provided the most support to respondents and a lack of support from these groups was most often perceived as negatively affecting PrEP use. AGYW described difficulties explaining PrEP to their mothers, who believed PrEP was HIV treatment or would lead to HIV infection. Disclosure to household members was notably meaningful for AGYW (both positively and negatively). Respondents reported leveraging supportive relationships for pill reminders. For respondents who perceived a household member would be unsupportive, however, non-disclosure was less feasible and PrEP use was often stigmatized. To avoid stigma, several respondents hid or discontinued PrEP. While supportive relationships may facilitate PrEP use, disclosure can also lead to stigma. Counselors should support AGYW in disclosing to key people in their social networks and provide AGYW with materials that lend credibility to explanations of PrEP. Community education is necessary to alleviate PrEP-related stigma and facilitate disclosure.

Epithelial Cells and Fibroblasts from the Human Female Reproductive Tract Accumulate and Release TFV and TAF to Sustain Inhibition of HIV Infection of CD4+ T cells

Tenofovir (TFV) treatment of female reproductive tract (FRT) cells results in differential accumulation of intracellular Tenofovir diphosphate (TFV-DP) in different cell types, with greater concentrations in epithelial cells (100-fold) and fibroblasts (10-fold) than in CD4+ T cells. The possibility that TFV-DP accumulation and retention in epithelial cells and fibroblasts may alter TFV availability and protection of CD4+ T cells against HIV infection, prompted us to evaluate TFV and/or Tenofovir alafenamide (TAF) release from FRT cells. Endometrial, endocervical and ectocervical polarized epithelial cells and fibroblasts were pre-loaded with TFV or TAF, and secretions tested for their ability to inhibit HIV infection of activated blood CD4+ T cells. Epithelial cell basolateral secretions (1, 2 and 3 days post-loading), but not apical secretions, suppressed HIV infection of CD4+ T cells, as did secretions from pre-loaded fibroblasts from each site. Intracellular TFV-DP levels in epithelial cells following preloading with TFV or TAF correlated directly with ARV protection of CD4+ T cells from HIV infection. When added apically to epithelial cells, TFV/TAF was released basolaterally, in part through Multidrug Resistant Protein transporters, taken up by fibroblasts and released into secretions to partially protect CD4+ T cells. These findings demonstrate that epithelial cells and fibroblasts release TFV/TAF for use by CD4+ T cells and suggest that the tissue environment plays a major role in the sustained protection against HIV infection.

Tenofovir-induced Fanconi syndrome and osteomalacia in two HIV-infected patients: Role of intracellular tenofovir diphosphate levels and review of the literature

We present 2 human immunodeficiency virus-infected patients with tenofovir disoproxil fumarate-induced Fanconi syndrome, leading to osteomalacia. Intracellular tenofovir diphosphate levels were measured in 1 patient and were found to be very high, with plasma tenofovir levels just slightly elevated. Fibroblast growth factor-23, a phosphaturic hormone, was decreased in both patients and is therefore unlikely to have a pathophysiological role in this pathology. The different potential factors contributing to the development of tenofovir-related kidney proximal tubular dysfunction are discussed and the data presented may help to further elucidate its pathogenesis.