Mikroglia

Mikroglia, in English called microglia, are the resident immune cells of the central nervous system. They originate from primitive macrophages in the yolk sac and migrate into the brain early in development, where they remain throughout life. In the adult brain they constitute a minority of glial cells but play a central role in surveillance and response to pathology.

Normal microglia have a ramified morphology with highly branched processes that continually survey the neural milieu. In response to injury, infection, or accumulated debris, they can rapidly transform into an activated state, retracting processes and adopting an amoeboid shape that enables phagocytosis and release of signaling molecules.

Functions include detection of pathogens and damage signals, clearance of cellular debris, and synaptic remodeling through synaptic pruning during development. They secrete cytokines and chemokines, present antigens under certain conditions, and interact with astrocytes and neurons to regulate inflammation and tissue repair. Microglia express receptors such as CSF1R and TREM2, and activity is often studied via markers like Iba1.

Pathological microglial activation is linked to neurodegenerative and neuroinflammatory diseases, including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. In Alzheimer's disease, microglia engage amyloid plaques but may also contribute to chronic inflammation. Research explores modulating microglial states as a therapeutic strategy and uses imaging like TSPO PET to assess microglial activation in vivo.

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