Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Impaired clearance of amyloid-beta causes vascular damage in Alzheimer’s disease

21.07.2005


New research suggests that accumulation of amyloid-â peptides in cerebral blood vessels, as opposed to the brain itself, may be a more important pathological mediator of Alzheimer’s disease. Two independent yet related articles describe such findings in the August issue of The American Journal of Pathology. Both articles are highlighted on the Journal’s cover.



Alzheimer’s disease, the most common form of progressive dementia, affects an estimated 4.5 million Americans according to the Alzheimer’s Association. Amyloid-â (Aâ) deposition is a hallmark of Alzheimer’s disease and other cerebral amyloid angiopathies. However, exactly how Aâ accumulates and causes damage is not fully understood.

In the first article, "Cerebral microvascular Aâ deposition induces vascular degeneration and neuroinflammation in transgenic mice expressing human vasculotropic mutant AâPP," Miao et al. describe early-onset Aâ deposition in Tg-SwDI mice. These mice express Aâ protein with mutations that are found in human early-onset cerebral amyloid angiopathy, causing specific accumulation of Aâ in cerebral blood vessels.


The Aâ peptides accumulated because they could not adequately cross the blood-brain barrier to be cleared from the brain. Over time, Aâ accumulation increased in the cerebral microvessels of the thalamus and subiculum of the brain. This resulted in degeneration of blood vessels as evidenced by reduced vessel density and increased apoptosis. Neuroinflammation also occurred as large numbers of microglia, along with inflammatory cytokines, were found at sites of Aâ accumulation.

The authors conclude that early-onset Aâ accumulation occurs predominantly in the cerebral microvasculature and appears largely responsible for the neuroinflammation in these mice. They also demonstrate the utility of Tg-SwDI mice in studying cerebral amyloid angiopathies, such as Alzheimer’s disease.

The second article, by Kumar-Singh et al., "Dense-core plaques in Tg2576 and PSAPP mouse models of Alzheimer’s disease are centered on vessel walls," utilizes two different transgenic mice: Tg2576 and PSAPP. Both models produce dense-core plaques, highly concentrated deposits of Aâ, and were used to investigate the possible association of blood vessels with Aâ deposits.

In these mice, dense-core plaques associated with cerebral vessels with high specificity. There was also evidence of vessel damage and blood-brain barrier damage, resulting in release of Aâ through the vessel walls and accumulation of plaques next to the vessels. These data confirm previous observations in humans that senile plaques associate with blood vessels, especially in the vasculotropic Flemish type of Alzheimer’s disease.

The authors propose a model of dense-core plaque formation that is dependent on cerebral vessels. As Aâ is cleared from the brain, it exerts a cytotoxic effect on the endothelial cells of the vascular wall (a process that may be exacerbated if clearance is impaired). This leads to loss of vessel integrity and accumulation of Aâ in the area surrounding the compromised vessel wall. Eventually, the damage is so great that the blood vessel deteriorates beyond functional use and new vessels form to pick up the slack. The result is a multicentric dense-core plaque that associates with multiple vessels.

These studies describe several animal models for further examining the pathogenesis and treatment of Alzheimer’s disease and related cerebral amyloid angiopathies. And both studies confirm that Aâ generated by neurons accumulates in blood vessels following attempted clearance of excess Aâ peptides. Thus, study of novel therapies that reduce the blood vessel-associated deposition of Aâ may prove beneficial to patients with Alzheimer’s disease.

Audra Cox | EurekAlert!
Further information:
http://www.asip.org

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>