Nav: Home

New mechanism by which Alzheimer's disease spreads through the brain discovered

June 13, 2018

The waste-management system of the cell appears to play an important role in the spread of Alzheimer's disease in the brain. A new study has focused on small membrane-covered droplets known as "exosomes". It was long believed that the main task of exosomes was to help the cell to get rid of waste products. In simple terms, they were thought of as the cell's rubbish bags. However, our understanding of exosomes has increased, and we now know that cells throughout the body use exosomes to transmit information. It's now known that the exosomes can contain both proteins and genetic material, which other cells can absorb.

The Linköping researchers have shown in the new study that exosomes can also transport toxic aggregates of the protein amyloid beta, and in this way spread the disease to new neurons. Aggregated amyloid beta is one of the main findings in the brains of patients with Alzheimer's disease, the other being aggregates of the protein tau. As time passes, they form ever-increasing deposits in the brain, which coincides with the death of nerve cells. The cognitive functions of a person with Alzheimer's disease gradually deteriorate as new parts of the brain are affected.

"The spread of the disease follows the way in which parts of the brain are anatomically connected. It seems reasonable to assume that the disease is spread through the connections in the brain, and there has long been speculation about how this spread takes place at the cellular level," says Martin Hallbeck, associate professor in the Department of Clinical and Experimental Medicine at Linköping University and senior consultant of clinical pathology at Linköping University Hospital.

In a collaboration with researchers at Uppsala University, he and his co-workers have investigated exosomes in brain tissue from deceased persons. The research team at Linköping University found more amyloid beta in exosomes from brains affected by Alzheimer's disease than in healthy controls. Furthermore, the researchers purified exosomes from the brains from people with Alzheimer's disease, and investigated whether they could be absorbed by cells cultured in the laboratory.

"Interestingly, exosomes from patients were absorbed by cultured neurons, and subsequently passed on to new cells. The cells that absorbed exosomes that contained amyloid beta became diseased," says Martin Hallbeck.

The researchers treated the cultured neurons with various substances that prevent exosomes from being formed, released, or absorbed by other cells. They were able to reduce the spread of the aggregated amyloid beta between cells by disrupting the mechanism in these ways. The methods used in these laboratory experiments are not yet suitable for treating patients, but the discovery is important in principle. "Our study demonstrates that it is possible to influence this pathway, and possibly develop drugs that could prevent the spreading. The findings also open up the possibility of diagnosing Alzheimer's disease in new ways, by measuring the exosomes," says Martin Hallbeck. The research has received financial support from donors that include the Swedish Research Council, the Swedish Alzheimer's Foundation, and the Swedish Brain Foundation.
-end-
The article: "Alzheimer disease pathology propagation by exosomes containing toxic amyloid-beta oligomers", Maitrayee Sardar Sinha, Anna Ansell-Schultz, Livia Civitelli, Camilla Hildesjö, Max Larsson, Lars Lannfelt, Martin Ingelsson and Martin Hallbeck, Acta Neuropathologica, published online 13 June 2018, doi: 10.1007/s00401-018-1868-1

Link: https://link.springer.com/article/10.1007/s00401-018-1868-1

For more information, please contact:

Martin Hallbeck, associate professor, martin.hallbeck@liu.se, +46 10 103 1506 or +46 730 555103

Karin Söderlund Leifler, press officer, karin.soderlund.leifler@liu.se, +46 13 28 1395

Linköping University

Related Neurons Articles:

New tool to identify and control neurons
One of the big challenges in the Neuroscience field is to understand how connections and communications trigger our behavior.
Neurons that regenerate, neurons that die
In a new study published in Neuron, investigators report on a transcription factor that they have found that can help certain neurons regenerate, while simultaneously killing others.
How neurons use crowdsourcing to make decisions
When many individual neurons collect data, how do they reach a unanimous decision?
Neurons can learn temporal patterns
Individual neurons can learn not only single responses to a particular signal, but also a series of reactions at precisely timed intervals.
A turbo engine for tracing neurons
Putting a turbo engine into an old car gives it an entirely new life -- suddenly it can go further, faster.
Brain neurons help keep track of time
Turning the theory of how the human brain perceives time on its head, a novel analysis in mice reveals that dopamine neuron activity plays a key role in judgment of time, slowing down the internal clock.
During infancy, neurons are still finding their places
Researchers have identified a large population of previously unrecognized young neurons that migrate in the human brain during the first few months of life, contributing to the expansion of the frontal lobe, a region important for social behavior and executive function.
How many types of neurons are there in the brain?
For decades, scientists have struggled to develop a comprehensive census of cell types in the brain.
Molecular body guards for neurons
In the brain, patterns of neural activity are perfectly balanced.
Engineering researchers use laser to 'weld' neurons
University of Alberta researchers have developed a method of connecting neurons, using ultrashort laser pulses -- a breakthrough technique that opens the door to new medical research and treatment opportunities.

Related Neurons Reading:

The Neuron: Cell and Molecular Biology
by Irwin B. Levitan (Author), Leonard K. Kaczmarek (Author)

From Neuron to Brain (5th Ed)
by John G. Nicholls (Author), A. Robert Martin (Author), David A. Brown (Author), Mathew E. Diamond (Author), David A. Weisblat (Author), Paul A. Fuchs (Author)

The Neuron: Cell and Molecular Biology
by Irwin B. Levitan (Author), Leonard K. Kaczmarek (Author)

The Myth of Mirror Neurons: The Real Neuroscience of Communication and Cognition
by W. W. Norton & Company

From Photon to Neuron: Light, Imaging, Vision
by Philip Nelson (Author)

From Neurons to Neighborhoods : The Science of Early Childhood Development
by Committee on Integrating the Science of Early Childhood Development (Author), Youth, and Families Board on Children (Author), National Research Council (Author), Committee on Integrating the Science of Early Childhood Development (Author), Jack P. Shonkoff (Editor), Deborah A. Phillips (Editor)

Neurons In Action 2: Tutorials and Simulations using NEURON
by John W. Moore (Author), Anne E. Stuart (Author)

From Neuron to Brain: A Cellular and Molecular Approach to the Function of the Nervous System, Fourth Edition
by John G. Nicholls (Author), A. Robert Martin (Author), Bruce G. Wallace (Author), Paul A. Fuchs (Author)

Molecular and Cellular Physiology of Neurons, Second Edition
by Gordon L. Fain (Author), Margery J. Fain (Illustrator), Thomas O'Dell (Illustrator)

From Neurons to Neighborhoods: An Update: Workshop Summary
by National Research Council (Author), Division of Behavioral and Social Sciences and Education (Author), Institute of Medicine (Author), Youth, and Families Board on Children (Author), Steve Olson (Editor)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Dying Well
Is there a way to talk about death candidly, without fear ... and even with humor? How can we best prepare for it with those we love? This hour, TED speakers explore the beauty of life ... and death. Guests include lawyer Jason Rosenthal, humorist Emily Levine, banker and travel blogger Michelle Knox, mortician Caitlin Doughty, and entrepreneur Lux Narayan.
Now Playing: Science for the People

#492 Flint Water Crisis
This week we dig into the Flint water crisis: what happened, how it got so bad, what turned the tide, what's still left to do, and the mix of science, politics, and activism that are still needed to finish pulling Flint out of the crisis. We spend the hour with Dr Mona Hanna-Attisha, a physician, scientist, activist, the founder and director of the Pediatric Public Health Initiative, and author of the book "What the Eyes Don't See: A Story of Crisis, Resistance, and Hope in an American City".