Researchers have made a significant stride in the fight against HIV by exploring a novel treatment approach that targets macrophages in the brain, a major reservoir for the virus. The study, funded by the National Institute of Mental Health (NIMH), investigated the potential of BLZ945, a drug that inhibits the CSF1R protein on macrophages, to eliminate HIV from the brain, where it can persist and evade conventional antiretroviral therapies.
Targeting Macrophages to Reduce Viral Load
Macrophages play a crucial role in HIV replication and spread within the brain. HIV-infected macrophages can persist even during antiretroviral treatment, serving as a source of long-lasting infection. By targeting these cells, researchers aimed to disrupt the virus's ability to maintain a presence in the brain. BLZ945, a small molecule capable of crossing the blood-brain barrier, was chosen for its ability to inhibit the activity of CSF1R, a protein on the surface of macrophages that is essential for their multiplication and activation.
The research team, led by Woong-Ki Kim, Ph.D., treated primates infected with simian immunodeficiency virus (SIV) with daily oral doses of BLZ945 (10 or 30 mg/kg) for 20 to 30 days. The results demonstrated a significant reduction in macrophage levels in the brain, which correlated with a substantial decline in brain-based SIV. These findings confirm BLZ945 as a potential treatment for HIV by specifically targeting macrophages.
Preserving Brain Health and Activating Immune Response
Importantly, the study found that BLZ945 treatment did not significantly affect other immune cells in the brain, such as microglia, which are essential for maintaining brain health. Furthermore, the researchers observed an increase in factors associated with antiviral immune response in the brains of treated animals, suggesting that the drug may help activate the immune system to target and eliminate SIV. There was also evidence of reduced neuroinflammation in the treated animals. Notably, the medication did not impact SIV levels in the blood or plasma, where macrophages don’t contribute as much to the production of the virus, suggesting this treatment specifically targets the brain.
Safety Profile and Clinical Implications
While CSF1R inhibitors have been associated with liver damage in some cases, the study found no evidence of this adverse effect in animals treated with BLZ945 at therapeutic levels, indicating a favorable safety profile. BLZ945 is currently undergoing human clinical trials for solid tumors, providing a potential pathway for studying its effectiveness and safety in treating HIV in humans. This research represents a significant step forward in the ongoing battle against HIV, offering hope for a future where the virus can be effectively eliminated from the brain.
