Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers report new pro-inflammatory role for anti-inflammatory enzyme

11.03.2005


Part of the immune system’s pro-inflammatory response to bacterial invasion is to increase nitric oxide levels with an enzyme called inducible nitric oxide synthase. In a study published in the Journal of Biological Chemistry, scientists report that the predominantly anti-inflammatory enzyme, endothelial nitric oxide synthase, is also involved in nitric oxide production in response to infection. This discovery may eventually provide a new target to treat sepsis, which is caused by overproduction of nitric oxide.



The research appears as the "Paper of the Week" in the March 18 issue of the Journal of Biological Chemistry, an American Society for Biochemistry and Molecular Biology journal.

When immune cells are exposed to pro-inflammatory cytokines or bacterial endotoxin (part of the bacterial cell wall) they start to produce inducible nitric oxide synthase (iNOS), an enzyme responsible for the manufacture of nitric oxide (NO). This results in an increase in cellular NO which contributes to inflammation and host defense.


"NO acts as a cytotoxic/cytostatic effector molecule released (predominantly) by immune cells," explains Dr. Adrian J. Hobbs of University College London. "It kills pathogens via a variety of mechanisms, mostly related to inhibition of metabolic enzymes and destruction of DNA."

However, too much NO can be a bad thing. Sustained overproduction of NO can cause septic shock (sepsis). "In sepsis, which is a systemic bacterial infection, the body expresses iNOS which generates relatively high concentrations of NO," says Dr. Hobbs. "This aids host defense by killing the invading organism, but in excessive quantities starts to lead to host-damage. In sepsis, this is manifested predominantly as a profound hypotension, inadequate tissue perfusion and organ failure. This often results in death."

Previously, Dr. Hobbs and colleagues demonstrated in vitro that endothelial nitric oxide synthase (eNOS) also plays a pro-inflammatory role by facilitating iNOS expression. "eNOS is found almost exclusively in the vascular endothelium and the NO that it synthesizes plays a key role in regulation of blood pressure, platelet aggregation, the reactivity of immune cells and growth of vascular smooth muscle cells," explains Dr. Hobbs. "iNOS is not expressed under normal physiological conditions, but is up-regulated for host-defense purposes."

Now, the researchers have validated their hypothesis in vivo using mice that do not produce eNOS. These mutant mice had a marked reduction in iNOS production in response to bacterial endotoxin, as well as lower plasma levels of NO2- and NO3- and less mortality than normal mice. The scientists also showed that endotoxin activates eNOS in macrophages and that this effect is an essential trigger for the induction of iNOS.

"eNOS has until recently been thought to act principally in an anti-inflammatory manner," notes Dr. Hobbs. "The results of our study show clearly that eNOS can also act in a pro-inflammatory manner and accelerate host-defense in response to pathogenic stimuli."

This discovery may eventually lead to new treatments for septic shock and other inflammatory diseases. "Pharmaceutical companies have been developing iNOS inhibitors to treat sepsis," explains Dr. Hobbs. "However, it now appears as if these are ineffective in reducing the mortality associated with the disease. The identification of a pro-inflammatory role for eNOS-derived NO may provide the stimulus for further research in this area and thereby identify novel targets for treatment of inflammatory diseases."

Nicole Kresge | EurekAlert!
Further information:
http://www.asbmb.org

More articles from Life Sciences:

nachricht Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>