microglial activation
Process by which resting microglia transform into reactive phenotypes in response to CNS injury or pathological stimuli.
Full Definition
Microglial activation refers to the transformation of resting microglia from their ramified, surveillance state to reactive phenotypes characterized by morphological changes, proliferation, and altered gene expression. Activated microglia become amoeboid-shaped, increase in number, and can adopt either pro-inflammatory (M1-like) or anti-inflammatory/repair (M2-like) functional states. This process is a hallmark of virtually all CNS pathologies, including neurodegeneration, trauma, infection, and tumor. Activated microglia can be identified by increased expression of markers such as CD68, Iba1, and CD11b. While initially protective, chronic microglial activation can contribute to ongoing tissue damage through the release of pro-inflammatory cytokines and reactive oxygen species.
Usage
Usage note: Specify immunohistochemical markers used; distinguish from infiltrating macrophages.
In Context
- "CD68 staining revealed extensive microglial activation throughout the affected cortical regions." — Alzheimer's disease pathology
- "The pattern of microglial activation suggested an ongoing inflammatory response." — Multiple sclerosis lesion analysis