Concentrations of Pro-Inflammatory Cytokines Are Not Associated with Senescence Marker p16(INK4a) or Predictive of Intracellular Emtricitabine/Tenofovir Metabolite and Endogenous Nucleotide Exposures in Adults with HIV Infection

OBJECTIVES: As the HIV-infected population ages, the role of cellular senescence and inflammation on co-morbid conditions and pharmacotherapy is increasingly of interest. p16(INK4a) expression, a marker for aging and senescence in T-cells, is associated with lower intracellular concentrations of endogenous nucleotides (EN) and nucleos(t)ide reverse transcriptase inhibitors (NRTIs). This study expands on these findings by determining whether inflammation is contributing to the association of p16(INK4a) expression with intracellular metabolite (IM) exposure and endogenous nucleotide concentrations. METHODS: Samples from 73 HIV-infected adults receiving daily tenofovir/emtricitabine (TFV/FTC) with either efavirenz (EFV) or atazanavir/ritonavir (ATV/r) were tested for p16(INK4a) expression, and plasma cytokine and intracellular drug concentrations. Associations between p16(INK4a) expression and cytokine concentrations were assessed using maximum likelihood methods, and elastic net regression was applied to assess whether cytokines were predictive of intracellular metabolite/endogenous nucleotide exposures. RESULTS: Enrolled participants had a median age of 48 years (range 23–73). There were no significant associations between p16(INK4a) expression and cytokines. Results of the elastic net regression showed weak relationships between IL-1Ra and FTC-triphosphate and deoxyadenosine triphosphate exposures, and MIP-1β, age and TFV-diphosphate exposures. CONCLUSIONS: In this clinical evaluation, we found no relationships between p16(INK4a) expression and cytokines, or cytokines and intracellular nucleotide concentrations. While inflammation is known to play a role in this population, it is not a major contributor to the p16(INK4a) association with decreased IM/EN exposures in these HIV-infected participants.