Host modulators of tenofovir exposure and efficacy in the female genital tract

Abstract

In 2022, there were 1.2 million new HIV infections worldwide. With almost half of those new HIV infections in women, there is a critical need for more prevention options. Development of effective HIV preventive drug regimens for women are dependent on identifying defined target concentrations in mucosal tissues that provide complete protection. An ex-vivo human tissue model has been developed to predict target concentrations of tenofovir diphosphate (TFVdp; active metabolite of tenofovir) in cervical tissue but has not been utilized to capture how vaginal microbiota affects TFVdp exposure in female genital tissue (FGT). The goal of this work was to further optimize the ex vivo tissue model by incorporating the vaginal microbiome and to further understand the relationship between tenofovir pharmacokinetics and genital inflammation. In chapter II, I identified anaerobic bacteria taxa that were negatively correlated with TFVdp:dATP ratio in cervical tissue. To further understand and confirm these findings, in chapter III , I used a bedside to bench approach to optimize our ex vivo tissue model to include the vaginal microbiome and develop a tool to study the interaction between TFvdp:dATP ratio and Prevotella bivia. In chapter IV , I demonstrated that as Prevotella bivia concentrations increased, the TFVdp:dATP decreased in the ex vivo vaginal tissue model. However, a robust dose-response relationship between tenofovir concentrations and viral inhibition could not be developed due to narrow tenofovir concentration range. Together, my data suggest that this model will provide a tool to streamline development of topical/inserted prevention options. In addition to the microbiome, I investigated the relationship between TFVdp and immune cells. To further assess the association between TFVdp and IL-17 as found in chapter II, I quantified CD4 and ROR gamma protein, a transcription factor of Th17 cells, using both Western blot and immunohistochemistry, but there was no clear trend between TFVdp and CD4/ROR gamma in chapter V. This suggests that the innate immune response may be playing a role instead of Th17 cells. Overall, this work highlights the complexity of the microenvironment in the female genital tract and the critical need to understand how antiretroviral mucosal pharmacology is affected by the microenvironment. These findings provide steppingstones to streamline the development of future prevention candidates and bring more prevention options to women.