Discrepancies between Protease Inhibitor Concentrations and Viral Load in Reservoirs and Sanctuary Sites in Human Immunodeficiency Virus-Infected Patients

Abstract

The variable penetration of antiretroviral drugs into sanctuary sites may contribute to the differential evolution of human immunodeficiency virus (HIV) and the emergence of drug resistance. We evaluated the penetration of indinavir, nelfinavir, and lopinavir-ritonavir (lopinavir/r) in the central nervous system, genital tract, and lymphoid tissue and assessed the correlation with residual viral replication. Plasma, cerebrospinal fluid (CSF), semen, and lymph node biopsy samples were collected from 41 HIV-infected patients on stable highly active antiretroviral therapy regimens to determine drug concentrations and HIV RNA levels. When HIV RNA was detectable, sequencing of the reverse transcriptase and protease genes was performed. Ratios of the concentration in semen/concentration in plasma were 1.9 for indinavir, 0.08 for nelfinavir, and 0.07 for lopinavir. Only indinavir was detectable in CSF, with a concentration in CSF/concentration in plasma ratio of 0.17. Differential penetration into lymphoid tissue was observed, with concentration in lymph node tissue/ concentration in plasma ratios of 2.07, 0.58, and 0.21 for indinavir, nelfinavir, and lopinavir, respectively. HIV RNA levels were <50 copies/ml in all CSF samples of patients in whom HIV RNA was not detectable in plasma. HIV RNA was detectable in the semen of three patients (two patients receiving nelfinavir and one patient receiving lopinavir/r), and its detection was associated with multiple resistance mutations, while the viral load in plasma was undetectable. HIV RNA was detectable in all lymph node tissue samples. Differential drug penetration was observed among the three protease inhibitors in the sanctuary sites, but there was no correlation between drug levels and HIV RNA levels, suggesting that multiple factors are involved in the persistence of viral reservoirs. Further studies are required to clarify the role and clinical relevance of drug penetration in sanctuaries in terms of long-term efficacy and drug resistance.

Inhibition of P-glycoprotein Activity at the Primate Blood-Brain Barrier Increases the Distribution of Nelfinavir into the Brain but Not into the Cerebrospinal Fluid

“…In the absence of zosuquidar, nelfinavir's poor distribution into the brain and the CSF was in agreement with studies in humans (Polis et al, 2003;Sols et al, 2003) and rodents (Choo et al, 2000;Anderson et al, 2006). As in humans, nelfinavir concentration in the macaque CSF was low and highly variable.…”

“…Because of the reported low concentrations of nelfinavir in human CSF (Polis et al, 2003;Sols et al, 2003), for this study we developed a highly sensitive ultra performance liquid chromatography method with a limit of quantification of 0.5 ng/ml nelfnavir. In the absence of zosuquidar, nelfinavir's poor distribution into the brain and the CSF was in agreement with studies in humans (Polis et al, 2003;Sols et al, 2003) and rodents (Choo et al, 2000;Anderson et al, 2006).…”

HIV-1 regulation of latency in the monocyte-macrophage lineage and in CD4+ T lymphocytes

“…However, phylogenetic approaches also point to an ongoing replication at a low level in certain infected cells. Moreover, these cells are often found in tissue sanctuary sites, where penetration of drugs is restricted, as in the brain [152][153][154]. Furthermore, several RT inhibitors are ineffective in chronically infected macrophages [29], and protease inhibitors have significantly lower activities in these cells compared with lymphocytes [155].…”

Quantification of antiretroviral drugs for HIV-1 in the male genital tract: current data, limitations and implications for laboratory analysis

“…Some authors diluted semen with plasma (1:1), presumably to reduce matrix effects; however, evidence for the appropriateness of this practice was not presented (van Praag et al 2000(van Praag et al , 2001aTaylor et al 1999Taylor et al , 2001bSankatsing et al 2002;Solas et al 2003; (Wang et al 2007).…”

“…Validation data limited for human plasma only. Solas et al (2003) Indinavir, nelfinavir, lopinavir and ritonavir Assays cited were validated for indinavir and nelfinavir only in human plasma. Taylor et al (2001b) Indinavir ritonavir and saquinavir…”