Brain microglial cells are ordinarily quiescent, but when stimulated can transition to a "primed" or activated state. Both primed and activated microglia express markers that suggest activation, but only activated microglia produce appreciable levels of inflammatory cytokines. Primed microglia, however, are hyper-responsive to signals from the peripheral immune system and thus can produce an exaggerated cytokine response when provoked. The potential for primed microglia to mount an exaggerated response is important because inflammatory cytokines mediate the sickness behavior syndrome, induce deficits in cognition, and are involved in chronic neurodegenerative diseases. One event that may prime microglial cells for an exaggerated response is aging. Signs of neuroinflammation emerge in healthy aged subjects and new findings suggest that aged individuals suffer an exaggerated neuroinflammatory response during peripheral infection. The exaggerated neuroinflammatory response is accompanied by severe, longer-lasting behavioral deficits and may cause acute cognitive disorders that are often reported in elderly patients with peripheral infections.
ASJC Scopus subject areas
- General Neuroscience