Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacterium present in eyes with ’wet’ age-related macular degeneration

09.11.2005


Researchers at the Massachusetts Eye and Ear Infirmary (MEEI) have found that Chlamydia pneumoniae, a bacterium linked to heart disease and capable of causing chronic inflammation, was present in the diseased eye tissue of five out of nine people with neovascular, or "wet," age-related macular degeneration (AMD). However, it was not found in the eyes of more than 20 individuals without AMD, providing more evidence that this disease may be caused by inflammation. The study is described in the November issue of Graefe’s Archive for Clinical and Experimental Ophthalmology.

AMD is the leading cause of blindness in Americans over the age of 55. The majority of vision loss is due to neovascular AMD, the advanced form of the disease characterized by the formation of blood vessels in the macula, the center part of the eye’s retina. These blood vessels often leak, thus giving neovascular AMD the name of "wet" AMD.

Researchers at the MEEI and Harvard Medical School (HMS) examined nine wet AMD membranes for the presence of C. pneumoniae and also determined whether this pathogen can change the function of eye cells in ways that can cause wet AMD. They found C. pneumoniae in the eyes of five out of the nine patients with wet AMD. They also tested tissue from more than 20 people who did not have AMD and did not find C. pneumoniae in any of these normal eye tissues.



"The paper showed that C. pneumoniae is capable of modifying the function of important cell types involved in regulating normal eye function," said lead author Murat Kalayoglu, MD, PhD. "We found that C. pneumoniae infection led to increased production of vascular endothelial growth factor (VEGF), the key protein involved in wet AMD. That C. pneumoniae infection of human eye cell types increases VEGF production is therefore significant and could explain in part why VEGF levels are increased in many people with wet AMD." Kalayoglu is an HMS research fellow in ophthalmology at MEEI.

Most of the new medications either marketed or being developed to treat wet AMD, such as Macugen (EyeTech Pharmaceuticals) and Lucentis (Genetech) block VEGF.

The study comes at a time of great interest in inflammatory mediators of AMD. Over the past seven months, a flurry of high-impact papers have shown, in aggregate, that nearly 50 percent of AMD can be explained by variations in a gene called Complement Factor H (CFH). This gene makes a protein that regulates the immune and inflammatory responses of the body.

"Our hypothesis is that C. pneumoniae may be the key link between CFH and AMD," Kalayoglu said. "That is, patients with CFH variations may be particularly susceptible to the damaging effects of chronic infection, and an infectious organism like C. pneumoniae may be particularly effective in accelerating inflammation and driving progression of AMD in these patients."

Kalayoglu and colleagues are currently collaborating with CFH researchers to study this hypothesis. "It may be possible to stop or reverse progression of AMD by identifying susceptible patients by diagnostic testing, and then treating these susceptible patients. Although C. pneumoniae is a bacterium that might respond to some antibiotics, much more work needs to be done before considering antibiotic therapy for AMD," he said.

"This is an important study suggesting that infection with C. pneumoniae may be a critical link between a genetic predisposition to AMD and actual progression to disease," said Gerald I. Byrne, Ph.D., professor and chairman of the Department of Molecular Sciences University of Tennessee Health Sciences Center. "This is yet another example of how an infection may unexpectedly contribute to a chronic disease. Certainly the association of C. pneumoniae with heart disease sets the stage for this pathogen’s involvement in other chronic conditions. This work is, in some ways, reminiscent of studies done more than 15 years ago on infections and ulcers. Those studies were viewed with skepticism, but Drs. Marshal and Warren, the researchers who pioneered that work received the Nobel Prize this year."

The Graefe’s paper builds on data from the same group that showed, for the first time, that an infectious agent is associated with AMD by epidemiological studies (Archives of Ophthalmology, April 2003).

Mary E. Leach | EurekAlert!
Further information:
http://www.meei.harvard.edu

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: 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....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

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

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

NSF-supported researchers to present new results on hurricanes and other extreme events

19.07.2018 | Earth Sciences

Scientists uncover the role of a protein in production & survival of myelin-forming cells

19.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>