Microglia, the brain's chameleon cell, between care and inflammation
It protects the brain... but can also damage it. Find out why researchers are so fascinated by microglia.
What is microglia?
Microglia are resident immune cells in the brain, representing around 5-10% of brain cells. Derived from the yolk sac during embryonic development, it constantly patrols nerve tissue in search of abnormalities.
Its mission: to spot the slightest sign of danger, eliminate cellular debris, neutralize microbes and alert other immune cells to aggression.
A true sentinel of the brain, it plays an essential role in protecting it and ensuring its proper functioning.
Key functions in neurodegenerative diseases
Under normal circumstances, microglia actively contribute to brain balance. It eliminates dead cells, sculpts useless neuronal connections during development, and supports neurons by secreting growth factors.
But as soon as an imbalance is detected - infection, lesion, or abnormal accumulation of proteins - it is activated. This activation is accompanied by a change in shape, behavior and function: microglia migrate to the injured areas, release pro-inflammatory molecules, and reinforce the local immune response.
This mechanism is essential in the short term, but becomes problematic if it takes hold over time.
In diseases such as Alzheimer's, Parkinson's or multiple sclerosis, microglia remain abnormally active for months or even years. This leads to chronic inflammation, disrupting neuronal function, and sometimes aggravating lesions rather than repairing them.
Understanding how to regulate this microglial activation is now a central issue in developing new therapies for neurodegenerative diseases.
What are researchers looking for today?
To better understand brain diseases, scientists are increasingly focusing on microglia. This immune cell, long considered secondary, is in fact essential to the balance of the nervous system, but also to its disruption.
How does microglia change role?
In a healthy brain, microglia protect and support neurons. But under the effect of stress, aging or certain diseases, it can change and adopt toxic behavior. Researchers are seeking to understand the signals that trigger this change, and how to prevent it from becoming chronic.
🩺 The medical challenge: limit brain inflammation and slow the progression of diseases such as Alzheimer's and Parkinson's.
Can microglia be reprogrammed to repair the brain?
Some studies show that microglia may also help rebuild damaged neuronal circuits. Scientists are exploring how to reactivate this restorative potential, without causing side effects.
🩺 Medical challenge: stimulating regeneration in multiple sclerosis or after brain trauma.
The latest discoveries
Researchers at the University of California at Irvine have created human microglia genetically modified (CRISPR) to produce the enzyme neprilysin - a destroyer of amyloid plaques - only where they accumulate.
- Greatly reduce amyloid deposits
- Protect neurons and synapses
- Reduces inflammation
- Reduce markers of neuronal damage
Concrete hope: a "living", targeted and adaptable therapy, raising the prospect of a new class of tailor-made microglial treatments.
Nasal Foralumab: soothing overactive microglia
Biotech Tiziana Life Sciences has tested intranasal administration of an anti-CD3 antibody (Foralumab) in patients with moderate Alzheimer's disease.
Microglial PET-scans (TSPO) show a significant decrease in microglial activation after three months of treatment.
Concrete hope: to reduce brain inflammation via a non-invasive, synergistic route, complementing current treatments.
