Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacterial toxins cause deadly heart disease

20.08.2013
Study shows superantigens produced by staph bacteria are required for deadly effects of infective endocarditis and sepsis

University of Iowa researchers have discovered what causes the lethal effects of staphylococcal infective endocarditis - a serious bacterial infection of heart valves that kills approximately 20,000 Americans each year.

According to the UI study, the culprits are superantigens -- toxins produced in large quantities by Staphylococcus aureus (staph) bacteria - which disrupt the immune system, turning it from friend to foe.

"The function of a superantigen is to 'mess' with the immune system," says Patrick Schlievert, Ph.D., UI professor and chair of microbiology at the UI Carver College of Medicine. "Our study shows that in endocarditis, a superantigen is over-activating the immune system, and the excessive immune response is actually contributing very significantly to the destructive aspects of the disease, including capillary leakage, low blood pressure, shock, fever, destruction of the heart valves, and strokes that may occur in half of patients."

Other superantigens include toxic shock syndrome toxin-1, which Schlievert identified in 1981 as the cause of toxic shock syndrome.

Staph bacteria is the most significant cause of serious infectious diseases in the United States, according to the Centers for Disease Control and Prevention (CDC), and infective endocarditis is the most serious complication of staph bloodstream infection. This dangerous condition affects approximately 40,000 people annually and has a death rate of about 50 percent. Among patients who survive the infection, approximately half will have a stroke due to the damage from the aggressive infection of the heart valves.

Despite the serious nature of this disease, little progress has been made over the past several decades in treating the deadly condition.

The new study, led Schlievert, and published Aug. 20 in the online open-access journal mBio, suggests that blocking the action of superantigens might provide a new approach for treating infective endocarditis.

"We have high affinity molecules that neutralize superantigens and we have previously shown in experimental animals that we can actually prevent strokes associated with endocarditis in animal models. Likewise, we have shown that we can vaccinate against the superantigens and prevent serious disease in animals," Schlievert says.

"The idea is that either therapeutics or vaccination might be a strategy to block the harmful effects of the superantigens, which gives us the chance to do something about the most serious complications of staph infections."

The UI scientists used a strain of methicillin resistant staph aureus (MRSA), which is a common cause of endocarditis in humans, in the study. They also tested versions of the bacteria that are unable to produce superantigens. By comparing the outcomes in the animal model of infection with these various bacteria, the team proved that the lethal effects of endocarditis and sepsis are caused by the large quantities of the superantigen staphylococcal enterotoxin C (SEC) produced by the staph bacteria.

The study found that SEC contributes to disease both through disruption of the immune system, causing excessive immune response to the infection and low blood pressure, and direct toxicity to the cells lining the heart.

Low blood flow at the infection site appears to be one of the consequences of the superantigen's action. Increasing blood pressure by replacing fluids reduced the formation of so-called vegetations – plaque-like meshwork made up of cellular factors from the body and bacterial cells -- on the heart valves and significantly protected the infected animals from endocarditis. The researchers speculate that increased blood flow may act to wash away the superantigen molecules or to prevent the bacteria from settling and accumulating on the heart valves.

In addition to Schlievert, the research team included Wilmara Salgado-Pabon, Ph.D., the first author on the study, Laura Breshears, Adam Spaulding, Joseph Merriman, Christopher Stach, Alexander Horswill, and Marnie Peterson.

The research was funded in part by grants from the National Institutes of Health (AI74283, AI57153, AI83211, and AI73366).

Jennifer Brown | EurekAlert!
Further information:
http://www.uiowa.edu

More articles from Health and Medicine:

nachricht Penn studies find promise for innovations in liquid biopsies
30.03.2017 | University of Pennsylvania School of Medicine

nachricht 'On-off switch' brings researchers a step closer to potential HIV vaccine
30.03.2017 | University of Nebraska-Lincoln

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

'On-off switch' brings researchers a step closer to potential HIV vaccine

30.03.2017 | Health and Medicine

Penn studies find promise for innovations in liquid biopsies

30.03.2017 | Health and Medicine

An LED-based device for imaging radiation induced skin damage

30.03.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>