A new study led by Canadian researchers reveals how amyotrophic lateral sclerosis (ALS) spreads in the body and suggests it may be possible to stop it with antibodies.
The motor neurons gradually stop working and die, to the point where patients in the later stages of the disease become paralyzed and lose their ability to walk, talk, eat and breathe. Around 140,000 new cases of ALS are diagnosed worldwide every year.
The causes of ALS are unknown, and there is currently no cure.
Important piece in puzzle of how ALS progresses
However, lead researcher Neil Cashman, a professor at the University of British Columbia, where he is also Canada Research Chair in Neurodegeneration and Protein Misfolding, says their study "identifies an important piece of the puzzle in determining how the disease is transmitted throughout the nervous system."
"By understanding how this occurs," he adds, "we can devise the best ways to stop the progressive neurological damage seen in ALS."
The researchers report their findings in the Proceedings of the National Academy of Sciences, PNAS.
Previous investigations have established that ALS is associated with a mutation and misfolding of a protein called SOD1, and that mutant misfolded versions of this protein can cause non-mutant forms to misfold inside living cells - like a prion disease.
Non-mutant, misfolded protein can be transmitted from cell to cell
In their study, Prof. Cashman and colleagues show how misfolded, non-mutant SOD1 can be transmitted from cell to cell and propagate like a domino effect.
They also identify two mechanisms by which this happens: through release and uptake of protein clumps, and via exosomes, small transporter vesicles or bubbles inside the cells.
These mechanisms may explain why sporadic ALS, which has no genetic cause, spreads progressively, from region to region.
In another part of the study, the team also showed how the spread might be stopped with antibodies that bind to specific regions of SOD1 that become exposed when it misfolds.
If, as this study suggests, misfolding of non-mutant SOD1 is the cause of ALS, then antibodies could be a way to halt disease progression, say the researchers.
In October 2013, Medical News Today reported another study that might point to a way to slow progression of ALS. The researchers found that mice with a rapidly progressing form of ALS had reduced neuroprotection and the waste-disposal systems in their cells did not work so well.
Written by Catharine Paddock PhD