![\"Orange](\"https:\/\/med.virginia.edu\/bims\/wp-content\/uploads\/sites\/390\/2020\/08\/brain_parasite_header_1-1.jpg\")
More than 30 million Americans are infected with a brain parasite spread by cats and contaminated meat, but most will never show symptoms. A new discovery from the University of Virginia School of Medicine explains why, and that finding could have important implications for brain infections, neurodegenerative diseases and autoimmune disorders.<\/p>\n
The UVA researchers found that the parasite,\u00a0Toxoplasma gondii,<\/em>\u00a0is kept in check by brain defenders called microglia. These microglia release a unique immune molecule, IL-1a,\u00a0that recruits immune cells from the blood to control the parasite in the brain, the scientists discovered. This process works so well that very few people develop symptomatic toxoplasmosis, the disease the parasite causes.<\/p>\n Understanding the role of microglia is essential because they are normally the only immune cells inside the brain. The new finding reveals how they recruit help when needed, and that discovery could apply to any brain condition with an immunological component \u2013 including brain injury, Alzheimer\u2019s disease, stroke, multiple sclerosis and more.<\/p>\n \u201cMicroglia must die to save the brain from this infection,\u201d said researcher Tajie Harris of UVA\u2019s Department of Neuroscience and the interim director of the Center for Brain Immunology and Glia, or BIG. \u201cOtherwise the IL-1a\u00a0remains stuck inside the microglia and wouldn\u2019t alert the immune system that something is wrong.\u201d<\/p>\n UVA\u2019s Department of Neuroscience and the BIG center have in recent years completely rewritten our understanding of the brain\u2019s relationship with the body\u2019s immune system. For decades, textbooks taught that the brain was disconnected from the immune system. UVA research, however, showed that was not the case, to the shock of the scientific community. Many researchers are now exploring the implications of that major discovery.<\/p>\n One area of focus is microglia and their role in defending the brain. This has been a difficult question to answer because microglia are closely related to other immune cells elsewhere in the body. Until recently, laboratory tools made to target microglia have also targeted these other cells, making it hard to distinguish between the two.<\/p>\n UVA researcher Samantha J. Batista, a graduate student in Harris\u2019 lab, used an elegant approach that leveraged the long-lived nature of microglia to understand their role in brain infection. She and her colleagues found that infection caused microglia to die in an inflammatory fashion \u2013 a way that the closely related immune cells do not.<\/p>\nThe Brain and the Immune System<\/strong><\/h3>\n