Innate immune cells outside of the brain consist of macrophages (including liver Kupffer cells), dendritic cells, mast cells, neutrophils, and other leukocytes. Microglia are brain-specific macrophages and are the main immune-derived cells in the brain while astrocytes, a subtype of glial cells, are also involved in mediating innate immunity in the CNS. Although microglia activation can be pro- or anti-inflammatory, it is the pro-inflammatory mechanisms induced by alcohol that will be discussed here. Innate immune signaling pathways are shared among major tissues; thus brain microglia respond to and initiate innate immune signaling via similar pathways to immune cells in the liver, intestines, and lungs.
