Reducing the methylation of a key messenger RNA can promote migration of macrophages into the brain and ameliorate symptoms of Alzheimer’s disease in a mouse model, according to a new study publishing March 7 in the open access journal PLOS Biology by Rui Zhang of Air Force Medical University in Xian, Shaanxi, China. The results illuminate one pathway for entrance of peripheral immune cells into the brain, and may provide a new target for treatment of Alzheimer’s disease.