Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Manipulating Brain Inflammation May Help Clear Brain of Amyloid Plaques

23.10.2009
In a surprising reversal of long-standing scientific belief, researchers at the Mayo Clinic campus in Florida have discovered that inflammation in the brain is not the trigger that leads to buildup of amyloid deposits and development of Alzheimer's disease.

In fact, inflammation helps clear the brain of these noxious amyloid plaques early in the disease development, as seen from studies in mice that are predisposed to the disorder, say the researchers in the online issue of the FASEB Journal.

"This is the opposite of what most people who study Alzheimer's disease, including our research group, believed," says the study's lead investigator Pritam Das, Ph.D., an assistant professor in the Department of Neuroscience. "And it also suggests that we can take advantage of the brain's own immune cells by directing them to remove amyloid plaques from the brain, thus protecting the brain against their harmful effects."

The study tested the widely held belief that inflammation in the brain increases the production and buildup of a toxic protein known as amyloid beta (Aâ). Clumps of this protein in the brain are the hallmark pathological feature of Alzheimer's disease.

"The belief was that when the brain's immune cells, microglia, are activated following the initial buildup of amyloid plaques, the inflammation that ensues stimulates the brain cell's machinery to produce more Aâ, which then leads to more inflammation," Dr. Das says. "This chronic activation of immune cells results in a self-reinforcing feedback loop that promotes more and more Aâ deposition and inflammation, eventually leading to malfunction and death of brain neurons."

Although this notion, which came mostly from studies in laboratory cells, was accepted throughout the scientific community, the Mayo Clinic researchers developed a way to test it in a living organism — and they expected to see the same result.

"We had initiated these studies using our new in vivo model to confirm whether inducing inflammation in the brain would in fact exacerbate the disease," Dr. Das says.

The researchers used a technique known as "Somatic Brain Transgenesis" to increase expression of Interleukin-6 (IL-6), a cytokine that stimulates an inflammatory immune response in the brains of young mice predisposed to developing age-progressive amyloid plaques. This powerful technology allows researchers to express any gene of interest in specific parts of the body by tagging the gene onto Adeno-associated viruses, which are inert. In this way, they can study the function of any protein in the brain, and also test its potential therapeutic use.

They found that IL-6 triggered inflammation throughout the brain, and they expected to see a big buildup of plaque as well as damage to brain neurons. "Instead, to our surprise, we found that the inflammation prevented plaques from forming and cleared whatever plaque that was already there," Dr. Das says.

Given this unexpected result, they performed additional experiments using different strategies. "First, we expressed IL-6 in the brains of newly born mice that are yet to develop any amyloid plaques and, secondly, we expressed IL-6 in the brains of mice with pre-existing plaque pathology," he says. "In both these cases, we got similar results — the presence of IL-6 leads to the clearance of amyloid plaques from the brain."

The researchers then performed experiments to determine how the amyloid plaques were removed from the brain. Their analysis revealed that the inflammation induced by IL-6 in the brain directed the microglia cells to remove the amyloid plaques from the brain. Microglial cells do this by phagocytosis. "They gobble up the plaque, which they 'see' as a foreign invader, and break it apart," Dr. Das says. Researchers also found that activated microglia cells were closely attached to the plaques and expressed proteins that help in removing the amyloid plaques from the brain. Dr. Das hypothesizes that inflammation helps clear plaque early in the development of Alzheimer's disease, but that at some point, continued production of the amyloid clumps in the brain overwhelms the ability of microglial cells to do their job. At that point, inflammation, chronically activated by presence of the amyloid plaque, can produce its own unhealthy effects on brain function.

"Indeed, it may be feasible to transiently and selectively manipulate the microglia cells to alter amyloid plaques in a manner that is both effective and tolerable," he says. "However, given that chronic inflammation over years of insult may be detrimental, any intervention based on activation of the brain's immune system must clearly strike a balance between the neuroprotective and neurotoxic effects," cautions Dr. Das. "We need to study this phenomenon more thoroughly, but if we are right, it could have implications not only for Alzheimer's disease but also other neurodegenerative disorders characterized by protein buildup in the brain, such as Parkinson's disease."

The study was funded by grants from the American Health Assistance Foundation (AHAF), Mayo Clinic and the National Institutes of Health (NIH).

About Mayo Clinic
Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. Doctors from every medical specialty work together to care for patients, joined by common systems and a philosophy of "the needs of the patient come first." More than 3,300 physicians, scientists and researchers and 46,000 allied health staff work at Mayo Clinic, which has sites in Rochester, Minn., Jacksonville, Fla., and Scottsdale/Phoenix, Ariz. Collectively, the three locations treat more than half a million people each year. To obtain the latest news releases from Mayo Clinic, go to www.mayoclinic.org/news. For information about research and education visit www.mayo.edu. MayoClinic.com is available as a resource for your health stories.

Kevin Punsky | EurekAlert!
Further information:
http://www.mayo.edu

More articles from Life Sciences:

nachricht Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology

nachricht Scientists generate an atlas of the human genome using stem cells
24.04.2018 | The Hebrew University of Jerusalem

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Quantum Technology for Advanced Imaging – QUILT

24.04.2018 | Information Technology

AWI researchers measure a record concentration of microplastic in arctic sea ice

24.04.2018 | Earth Sciences

Complete skin regeneration system of fish unraveled

24.04.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>