Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists learn role of oxidative stress in estrogen-related bone loss

11.09.2007
Scientists have discovered new information about an immune pathway in mice that explains how oxidative stress that results from acute estrogen deficiency leads to the loss of bone. The finding, published in the Proceedings of the National Academy of Sciences, could help in identifying a new drug target for preventing postmenopausal bone loss.

Previous mouse research has shown that both oxidative stress and increased T cell activity contribute to bone loss following estrogen depletion, which occurs after menopause or when ovaries are removed. Oxidative stress is the toxic accumulation of too much reactive oxygen in cells. Research has shown that T cells contribute to bone loss because they produce a protein called tumor necrosis factor (TNF), which increases the formation of osteoclasts in rodents and humans. Osteoclasts are cells that cause an excessive destruction of bone.

In the current study, scientists at Emory University School of Medicine, with colleagues at the University of Udine, Italy, discovered the "upstream" events that occur after estrogen depletion and lead to T cell overproduction. They found that reactive oxygen stimulates dendritic cells Ð a type of "antigen-presenting cell" that processes and presents antigen material on the surface of other immune cells Ð to up-regulate the immune antigen CD80. CD80 is a "co-stimulatory" molecule that is part of the CD80/CD28 pathway required for activation of T lymphocytes. When this pathway is activated, it leads to increased T cell TNF production and ultimately to bone loss.

In order to try and prevent bone loss in the research mice whose ovaries were removed and determine how reactive oxygen was exerting its toxic effects, the research team treated the mice with the immunosuppressant CTLA4-Ig, which prevents the activation of T cells by blocking the binding of CD80 to CD28. Because CTLA4-Ig did not directly affect osteoclasts or block the direct effects of reactive oxygen on osteoclasts, the data helped prove the researchers' hypothesis that oxidative stress causes bone loss because it activates T cells rather than acting directly on osteoclasts.

The research team was led by Roberto Pacifici, MD, Garland Herndon professor of medicine and director of the Division of Endocrinology at Emory University School of Medicine. Scientists included Francesco Grassi, Gianluca Tell, Michaela Robbie-Ryan, Yuhao Gao, Masakazu Terauchi, Xiaoying Yang, Milena Romanello, Dean P. Jones, and M. Neal Weitzmann.

"Our research provides important information about the pathway leading from estrogen depletion to bone loss following menopause or removal of ovaries," says Dr. Pacifici. "As we learn more and more about these mechanisms, we come closer to new drug targets that could help prevent this challenging problem that affects millions of women."

Holly Korschun | EurekAlert!
Further information:
http://www.emory.edu

Further reports about: Estrogen Oxidative Stress bone loss osteoclasts reactive

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Introduction of a novel system for in vitro analyses of zebrafish oligodendrocyte progenitor cells

23.10.2017 | Life Sciences

Did you know how many parts of your car require infrared heat?

23.10.2017 | Automotive Engineering

3rd Symposium on Driving Simulation

23.10.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>