As you read this sentence, a group of cells is patrolling your brain. These soldiers shuttle around neurons, using their gangly appendages to search for threats. If one of these cells detects a pathogen or damage, it leaps into action. It puffs up, then swoops down in a voracious attack, releasing chemicals that signal its companions to join the fight.
These specialized immune cells, called microglia, are our brain’s first defenders. They protect us from invaders, clear away debris, and maintain connections between neurons, ensuring the brain stays in optimal condition.
Yet despite their vigilance, microglia can sometimes harm their friends, and growing evidence suggests they may be the culprits behind some of the most intractable brain diseases, such as Alzheimer’s and depression. If so, then targeting our wayward defenders—or even replacing them with rejuvenated soldiers—could lead to exciting new treatments.
Microglia were discovered in 1919 Neuroscientist Pio del Rio HortegaHe discovered these new cells by accident while experimenting with new methods for staining brain tissue, and named them after the Ancient Greek words for “small” and “glue.”
It turns out that description is inappropriate. Aside from their blobby appearance, microglia have few glue-like properties. Instead, they are among the most dynamic cells in the body, roaming the brain with spindly, tentacle-like projections that extend and retract in response to changes in their environment.
How microglia work
Microglia are a type of macrophage, a type of immune cell that…
