Microglia are the primary immune cells of the central nervous system, similar to peripheral macrophages. They respond to pathogens and injury by changing morphology and migrating to the site of infection/injury, where they destroy pathogens and remove damaged cells. As part of their response they secrete cytokines, chemokines, prostaglandins, and reactive oxygen species, which help to direct the immune response. Additionally, they are instrumental in the resolution of the inflammatory response, through the production of anti-inflammatory cytokines. Microglia have also been extensively studied for their harmful roles in neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, as well as cardiac diseases, glaucoma, and viral and bacterial infections. (en)