Five monkeys infected with simian immunodeficiency virus (SIV), a very close relative of HIV, and treated with minocycline had less damage to brain cells, less brain inflammation, and less virus in the central nervous system than six infected monkeys that received no treatment, the researchers have reported in the Journal of the American Medical Association.
In use for more than 30 years, minocycline was specifically designed to cross the blood-brain barrier, the biological ‘wall’ that limits what can pass from the blood into the brain. Other researchers have reported that this antibiotic can protect brain cells in animal models of other diseases, including multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer’s disease, and stroke. The drug is being tested in early clinical trials for some non-HIV-related conditions.
SIV and HIV both affect the same tissues in the same way and use the same tricks to infect cells and outwit treatments, but SIV infects only non-human primates, and HIV only infects people. Antiretroviral drugs target and interfere with the viral proteins needed to accomplish this.
In contrast, minocycline does not target the virus or its proteins. Although more information is needed, the researchers believe that minocycline ‘calms down’ as yet undefined biological pathways involving two specific proteins implicated in damage in neurodegenerative diseases.
A multicenter clinical trial is being planned to test whether minocycline has the same effects in HIV-infected people as it does in SIV-infected monkeys, but it is not expected to start until sometime next year.