Microglia, shown in green, are part of the immune response that protect the brain. They could play a role in slowing the progress of prion and other neurodegenerative diseases. NeuroscienceNews.com image is credited to NIAID.
Prion diseases are slow degenerative brain diseases that occur in people and various other mammals. No vaccines or treatments are available, and these diseases are almost always fatal. Scientists have found little evidence of a protective immune response to prion infections. Further, microglia–brain cells usually involved in the first level of host defense against infections of the brain–have been thought to worsen these diseases by secreting toxic molecules that can damage nerve cells.
Now, scientists have used an experimental drug, PLX5622, to test the role of microglia against scrapie, a prion disease of sheep. PLX5622 rapidly kills most of the microglia in the brain. When researchers gave the drug to mice infected with scrapie, microglia were eliminated and the mice died one month faster than did untreated mice. The results, published in the Journal of Virology by researchers from the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, suggest that microglia can defend against a prion infection and thus slow the course of disease. The scientists hypothesize that microglia trap and destroy the aggregated prion proteins that cause brain damage.
Abstract for “Microglia Are Critical in Host Defense Against Prion Disease” by James A. Carroll, Brent Race, Katie Williams, James Striebel and Bruce Chesebro in Journal of Virology. Published May 16 2018.