The rare neurological condition, amyotrophic lateral sclerosis (ALS), had confined Stephen Hawking, the renowned cosmologist, to a wheelchair. ALS is a motor neuron disease, implying the neurons responsible for movement in the brain, brainstem, and spinal cord gradually degenerate. As a result, it leads to loss of mobility, impaired speech and breathing difficulties over time.
There is no known cure for ALS yet; scientists worldwide are researching various cellular facets of the condition to develop therapeutic remedies for it. Some studies have shown that astrocytes influence the progression of ALS. Astrocytes are star-shaped cells that supply nutrients and provide structural support and protection to the neurons.
In this context, Dr Yossi Buskila and team from the School of Medicine, Western Sydney University, Australia, have demonstrated how disrupted astrocyte function exacerbates ALS.
“Astrocytes are a type of glial cells that play a key role in multiple mechanisms that support neuronal function, including maintaining the potassium ions concentration, regulation of synaptic plasticity and neuroinflammation,” says Dr Buskila.
Their study results indicate that astrocytes could be potential targets for ALS treatment.
Astrocytes maintain potassium ion levels in the brain, which influence message transmission between neurons. Dysfunction of astrocytes leads to elevated potassium ions, triggering incessant neuron firing and, ultimately, neuron death, the study points.
Reactive stars
Speaking about their latest study at the 2nd International Conference on MND/ALS at the National Institute of Mental Health and Neurosciences, Bengaluru, Dr T R Raju, director of Research at Sankara Academy of Vision, Bengaluru said, “Astrocytes can become protectors or toxic to neurons based on the stimulus they receive.”
Dr Buskila says, “The transition of astrocytes into a reactive state (reactive astrocytes) leads to disease progression because of altered function and morphology.”
Causes of inflammation in ALS
Typically, microglia (a type of glial cells) clean up and eliminate toxic proteins and microbes in the brain. However, in the case of ALS, these activated microglial cells trigger inflammation of neurons and degenerate them.
Dr Raju said that microglial cells in the cerebrospinal fluid of the central nervous system produce a protein called CHIT1, that is found abundantly in those with ALS.
Based on their study findings, Dr Raju said, “This [CHIT 1] can be used as an early diagnostic marker as in our study, we have identified a sensitivity of 87 per cent in people with ALS.”
However, Dr Buskila opines that astrocytes could be better therapeutic targets.
“Although multiple studies indicate that CHIT1 levels are significantly higher in the cerebrospinal fluid in people with ALS, it [CHIT1] is not specific to ALS. Its increased levels are also seen in other conditions like myelopathy, multiple sclerosis, Alzheimer’s, stroke, and cerebrovascular dementia,” she says.
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