Background:  Highly active anti-retroviral therapy (HAART) has diminished the incidence and severity of HIV-1 associated dementia (HAD).  However, a significant disease prevalence, poor nervous system penetration of many antiretroviral medicines, viral back-mutation (from brain to blood) and a failure to eradicate reservoirs of persistent infection warrant evaluation for improving drug delivery to brain.  Thus, we developed and tested nanosuspensions of antiretroviral medicines (specifically, indinavir; IND) for ability to suppress HIV-1 replication in monocyte-derived macrophages (MDM), the natural target cell for viral infection in brain. 

Methods:  MDM were infected with HIV-1ADA and virus was removed after 12 hours of exposure.  Infected cells were treated with either native IND sulfate or drug nanosuspensions (developed by Baxter Healthcare).  Replicate MDM were left untreated as controls (CON).  Both drugs were used at 0.5 mM (10 times the IND solubility limit) to retain the drug in suspension.  After overnight drug treatment cells were maintained in media supplemented only with sera and antibiotics.  Culture supernatants were collected and assessed for reverse transcriptase (RT) activity every 2 days.  MDM viability was determined at 9 days after infection by the thiazolyl blue, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) conversion assay. 

Results: CON HIV-1-infected MDM showed prominent cytopathicity (ballooning, multinucleated giant cells, and cell death) with sustained high levels of RT activity throughout the 9 day observation period.  IND treated MDM showed low but detectable virus-associated cytopathicity with an up to 97% decrease in the level of viral replication.  IND nanosuspension MDM showed a 99% decrease in RT activity compared to controls with no cytopathicity.  Neither native drug nor drug nanosuspension had any statistically significant effects on MDM viability.

Conclusions:  Single dose loading of IND nanosuspensions effectively suppressed HIV-1 replication and abrogated virus-associated cytopathicity without affecting measures of cell viability.  Studies are planned to evaluate the feasibility of nanosuspension loaded MDM to target ongoing nervous system infection in a murine model of HIV-1 encephalitis.

Keywords: macrophage; antiretroviral; HIV-1 associated dementia