Different Roles of Microglia/Macrophage in Ischemic Stroke and Alzheimer's Disease

Neuroinflammation is a double edge sword: it plays both destructive and regenerative roles in a variety of neurological diseases, such stroke and Alzheimer’s disease (AD). In the central nervous system, these inflammatory changes are restricted exclusively to microglia. Ischemic stroke causes an acute cascade of events, including excitotoxicity, inflammatory responses, oxidative stress and apoptosis, whereas AD is a chronic progressive process. As the blood–brain barrier separates the central nervous system and the peripheral immune system, the brain is used to be considered an immune-privileged organ. However, accumulating evidence reveals mononuclear phagocytes and the resident microglia play a key role in modulating the development and progression of brain pathology. In this mini review, we summarize the role of microglia in the brain and in disease states. Microglia serves different roles at different stages of the diseases. We emphasize the regulatory role of CX3CR1, which may provide a novel and effective means for therapy.