Discovery of Genetic Variants of the Kinases That Activate Tenofovir in a Compartment-specific Manner

Abstract

Tenofovir (TFV) is used in combination with other antiretroviral drugs for human immunodeficiency virus (HIV) treatment and prevention. TFV requires two phosphorylation steps to become pharmacologically active; however, the kinases that activate TFV in cells and tissues susceptible to HIV infection have yet to be identified. Peripheral blood mononuclear cells (PBMC), vaginal, and colorectal tissues were transfected with siRNA targeting nucleotide kinases, incubated with TFV, and TFV-monophosphate (TFV-MP) and TFV-diphosphate (TFV-DP) were measured using mass spectrometry–liquid chromatography. Adenylate kinase 2 (AK2) performed the first TFV phosphorylation step in PBMC, vaginal, and colorectal tissues. Interestingly, both pyruvate kinase isozymes, muscle (PKM) or liver and red blood cell (PKLR), were able to phosphorylate TFV-MP to TFV-DP in PBMC and vaginal tissue, while creatine kinase, muscle (CKM) catalyzed this conversion in colorectal tissue. In addition, next-generation sequencing of the Microbicide Trials Network MTN-001 clinical samples detected 71 previously unreported genetic variants in the genes encoding these kinases. In conclusion, our results demonstrate that TFV is activated in a compartment-specific manner. Further, genetic variants have been identified that could negatively impact TFV activation, thereby compromising TFV efficacy in HIV treatment and prevention.

HIV Prevention Among Transgender Populations: Knowledge Gaps and Evidence for Action

“…While there is no evidence of drug-drug interactions between TDF and estrogen-containing oral contraceptives medications [50], there are tissue specific in vitro differences in TDF pharmacokinetics in the presence of estrogen [51–53]. Therefore, it is feasible that use of exogenous estradiol for medical gender affirmation may affect the pharmacokinetics of TDF in colon tissue – a critical site for PrEP efficacy among people who engage in receptive anal intercourse.…”

Distribution and effects of amino acid changes in drug-resistant α and β herpesviruses DNA polymerase

“…Its mechanism of action requires phosphorylation by cellular kinases and incorporation in the viral genome by viral polymerase (116–118). In its active diphosphate form, tenofovir-DP inhibits HSV-1 DNApol with an IC 50 of 0.38 μg/ml in the presence of competing dATP (at 3.2 μM) (119).…”

HIV Antiretroviral Pre‐Exposure Prophylaxis: Development Challenges and Pipeline Promise

“…Although there are competing methods for incorporation of the dNTP data into complex PK‐viral dynamics models of these interactions, the data help explain the need for at least 6–7 weekly doses of TDF/FTC in women (whose primary risk is receptive vaginal intercourse (RVI)), less frequent 4 per week dosing in MSM and TGW (whose primary risk is receptive anal intercourse (RAI)), and how only a few doses seems to provide rapid protection in MSM and TGW as in Ipergay . Another source of PK variability is that the specific intracellular kinases that phosphorylate TFV and FTC vary anatomically among the cells in blood, cervicovaginal tissue, and colorectal tissue; the kinases are also genetically polymorphic …”

“…Assuming similar adherence, oral TDF/FTC dosing prevents colorectal infection with less frequent dosing (4 per week) compared to preventing vaginal infection (6–7 doses per week), despite the higher risk of infection with RAI. Mucosal TDF and FTC PK and dNTP differences between colorectal and cervicovaginal tissue provide a plausible explanation these outcome difference . However, because systemic NRTI and dNTP PK is no different in MSM (primary RAI risk) compared with women (primary RVI risk), systemic concentration cannot contribute to differences in PrEP effectiveness in MSM and women. When modeling plasma TFV concentration‐seroconversion response relationships across all of the primary RCTs using daily dosing, most of the variation in the relationship is explained by adjusting for anatomic differences of TFV‐DP concentrations at mucosal sites of HIV acquisition and the higher RAI risk in MSM; both are mucosal differences, not systemic …”

“…15 Another source of PK variability is that the specific intracellular kinases that phosphorylate TFV and FTC vary anatomically among the cells in blood, cervicovaginal tissue, and colorectal tissue; the kinases are also genetically polymorphic. [29][30][31] Vaginal microbiome and genital inflammation An abnormal nonlactobacillus dominant vaginal microbiome was associated with reduced cervicovaginal lavage fluid (CVL) and plasma TFV concentrations in different studies, as well as a threefold reduction in HIV protection in the CAPRISA 004 study of TFV vaginal gel. 32,33 Some post hoc analysis concerns were allayed by finding nonlactobacillus dominant microbiome in similar proportions of high and low adherence groups and both TFV and placebo arms.…”