Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Flesh-eating bacteria escape body’s safety net

21.02.2006


Researchers at the University of California, San Diego (UCSD) School of Medicine have discovered that so-called flesh-eating "Strep" bacteria use a specific enzyme to break free of the body’s immune system, a finding which could potentially lead to new treatments for serious infections in human patients.



The research, reported in the February 21, 2006 issue of the journal Current Biology, focuses on the major human pathogen group A Streptococcus. Among the most important of all bacterial pathogens, strep is responsible for a wide range of diseases – from simple throat and skin infections to life-threatening conditions such as necrotizing fasciitis ("flesh-eating disease") and toxic shock syndrome.

"These findings suggest a novel approach to treating serious Strep infections, such as flesh-eating disease, by assisting our body’s own defense system," said senior author Victor Nizet, M.D., UCSD associate professor of pediatrics and an infectious diseases physician at Children’s Hospital, San Diego.


The UCSD investigators examined the interaction of Strep bacteria with neutrophils, specialized white blood cells that play a front line role in human’s immune defense against pathogenic microbes. Recent research by European investigators had shown that neutrophils are particularly effective defenders because they release "nets" composed of DNA and toxic compounds to entrap and kill invading bacteria. In the current study, the UCSD scientists proved that disease-causing Strep release an enzyme that degrades these DNA nets, thereby allowing the organism to escape the neutrophil net and spread in body tissues.

The UCSD team used a molecular genetic approach for their studies, knocking out the gene encoding the DNA-degrading enzyme from a pathogenic Strep strain that was originally isolated from a patient suffering from necrotizing fasciitis.

"Deprived of this single enzyme, the mutant Strep strain was easily killed by human neutrophils", said lead author John Buchanan, Ph.D., research scientist in the UCSD department of pediatrics. "In addition, the mutant Strep bacteria no longer produced a spreading infection when injected into the skin of experimental mice."

The critical role of the DNA-degrading Strep enzyme was confirmed by cloning the corresponding gene into a normally non-pathogenic bacterial strain. Addition of the single gene allowed these bacteria to degrade DNA, escape neutrophil killing, and produce a spreading ulcer in the mouse infection model. Special fluorescent microscopy techniques were used to observe how the Strep enzyme dissolved the DNA nets and allowed bacteria to float away from the neutrophils.

"The experiments explain how this DNA-degrading enzyme contributes to the severe infections produced by certain strains of Strep bacteria, while simultaneously confirming just how important neutrophil DNA nets are to our normal immune defense," said Buchanan.

Recognizing the critical role played by the DNA-degrading enzyme in progression of Strep disease, the UCSD researchers examined whether it could represent a target for therapy. Mice experimentally infected with Strep were treated by injecting a chemical inhibitor of the DNA-degrading enzyme at the site of infection. A dramatic reduction in bacterial counts and tissue injury was observed following the inhibitor treatment, when compared to controls receiving a placebo.

Nizet explained that the researchers’ findings could lead to novel treatments for Strep-related diseases. "Instead of attempting to kill the bacteria directly with standard antibiotics, a treatment strategy to inhibit the Strep DNA-degrading enzyme could disarm the pathogen, making it susceptible to clearance by our normal immune defenses," he said.

Debra Kain | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht A cell senses its own curves: New research from the MBL Whitman Center
29.04.2016 | Marine Biological Laboratory

nachricht A New Discovery in the Fight against Cancer: Tumor Cells Switch to a Different Mode
29.04.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

Im Focus: New world record for fullerene-free polymer solar cells

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences (CAS). This work is about avoiding costly and unstable fullerenes.

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences...

Im Focus: Ultra-thin glass is up and coming

As one of the leading R&D partners in the development of surface technologies and organic electronics, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP will be exhibiting its recent achievements in vacuum coating of ultra-thin glass at SVC TechCon 2016 (Booth 846), taking place in Indianapolis / USA from May 9 – 13.

Fraunhofer FEP is an experienced partner for technological developments, known for testing the limits of new materials and for optimization of those materials...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

Winds a quarter the speed of light spotted leaving mysterious binary systems

29.04.2016 | Physics and Astronomy

Fiber optic biosensor-integrated microfluidic chip to detect glucose levels

29.04.2016 | Health and Medicine

A cell senses its own curves: New research from the MBL Whitman Center

29.04.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>