This neurodegenerative disease originates from lesions caused by an abnormal accumulation in the brain of two proteins: amyloid-- and Tau. These lesions damage neurons and their synapses, ultimately causing an inability to create new memories.
To block these processes, the scientists injected a mutated amyloid-- protein (Icelandic mutation) into the brains of mice that model the disease. This very rare protein, called amyloid-? , had been discovered in certain individuals of Icelandic origin who presented with improved cognitive ageing and never developed Alzheimer’s disease.
The results were surprising: the synapses returned to their normal state and there were no memory losses characteristic of the disease. Administration of this modified protein 2 thus protected the brains of the mice against all the malfunctions related to the disease. Furthermore, the scientists showed that a single dose was sufficient to trigger this protection, which remained active for several months.
The scientific community had previously agreed to the hypothesis that the administration of amyloid-- proteins could only amplify the pathology because they behave like "pseudo-prion" proteins 3 . This new study published on 14 June 2024 in Molecular Psychiatry, shows for the first time in mice that "pseudo-prion" amyloid-- proteins can protect the brain against the damage characteristic of Alzheimer’s disease. These findings could thus provide a starting point for a new category of preventive therapies to treat people with early-stage neurodegenerative diseases and block the course of the disease, thanks to the injection of protective prions.
1 The laboratories working on this study were the Laboratoire des Maladies Neurodégénératives (CNRS/CEA/Université Paris-Saclay) and the Grenoble Institut des Neurosciences (Université Grenoble Alpes/INSERM/CEA/CNRS).
3 Abnormal prion proteins are generally responsible for severe neurodegenerative diseases such as mad cow disease or Creutzfeldt-Jakob disease. Their normal form is naturally present in our brains. However, when a prion protein changes shape it becomes abnormal and then other surrounding proteins adopt the same abnormal shape, thus amplifying the processes under way. Amyloid-- protein can also behave in this way, so it is considered as a "pseudo-prion".
Transmissible long-term neuroprotective and precognitive effects of 1-42 beta-amyloid with A2T Icelandic mutation in an Alzheimer’s disease mouse model. Marina Célestine, Muriel Jacquier-Sarlin, Eve Borel, Fanny Petit, Fabien Lante, Luc Bousset, Anne-Sophie Hérard, Alain Buisson and Marc Dhenain. Molecular Psychiatry, June 14, 2024.
