Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists reveal how disease bacterium survives inside immune system cell

10.05.2005


New research on a bacterium that can survive encounters with specific immune system cells has strengthened scientists’ belief that these plentiful white blood cells, known as neutrophils, dictate whether our immune system will permit or prevent bacterial infections. A paper describing the research was released today online in The Journal of Immunology. Frank R. DeLeo, Ph.D., of Rocky Mountain Laboratories (RML), part of the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health, directed the work at RML, in Hamilton, MT, in collaboration with lead author Dori L. Borjesson, D.V.M., Ph.D., of the University of Minnesota in St. Paul.

Scientists analyzed how neutrophils from healthy blood donors respond to Anaplasma phagocytophilum, a tick-borne bacterium that causes granulocytic anaplasmosis in people, dogs, horses and cows. A. phagocytophilum is carried by the same tick that transmits Lyme disease and was first identified in humans in 1996. Human granulocytic anaplasmosis (HGA) -- formerly called human granulocytic ehrlichiosis -- is prevalent in Minnesota and along the East Coast. HGA typically causes mild symptoms that include fever, muscle aches and nausea. Some 362 U.S. cases were reported to the Centers for Disease Control and Prevention in 2003.

HGA is considered an emerging infectious disease, and Dr. Borjesson is working to understand how it affects blood cells -- and neutrophils in particular. "Few people know about this pathogen, but it is important because it is transmitted by ticks and causes disease in both animals and humans," Dr. Borjesson says.



Neutrophils, which make up about 60 percent of all white blood cells, are the largest cellular component of the human immune system -- billions exist inside each human. Typically, neutrophils ingest and then kill harmful bacteria by producing molecules that are toxic to cells, including a bleach-like substance called hypochlorous acid. Once the bacteria are killed, the involved neutrophils self-destruct in a process known as apoptosis. Recent evidence suggests that this process is vital to resolving human infections.

A. phagocytophilum is unusual in that it can delay apoptosis in human neutrophils, which presumably allows some of the bacteria to replicate and cause infection. "This particular bacterium specifically seeks out neutrophils -- possibly the most lethal of all host defense cells -- and remarkably, can alter their function, multiply within them and thereby cause infection," says NIAID Director Anthony S. Fauci, M.D.

Dr. DeLeo says the findings contrast with what is known about other bacterial pathogens, most notably Staphylococcus aureus, which is of great interest because of its increasing resistance to antibiotic treatment. S. aureus, often simply referred to as "staph," are bacteria commonly found on the skin and in the noses of healthy people. Occasionally, staph can cause infection; most are minor, such as pimples, boils and other skin conditions. However, staph bacteria can also cause serious and sometimes fatal infections, such as bloodstream infections, surgical wound infections and pneumonia.

In their experiments, the research team compared the neutrophil response to A. phagocytophilum with that of a weak strain of S. aureus. Using microarray technology that allowed them to compare about 14,000 different human genes, the researchers discovered how the response to A. phagocytophilum deviates from that of S. aureus, and thus permits the HGA agent to survive.

"This study has given us a global model of how bacteria can inhibit neutrophil apoptosis," says Dr. DeLeo. "Our next step is to look at specific human genes or gene pathways within this model and try to determine which of these molecules help prolong cell life following infection." Information gathered from these and similar studies, he adds, could help researchers develop therapeutics to treat or prevent bacterial infections.

Ken Pekoc | EurekAlert!
Further information:
http://www.niaid.nih.gov

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 >>>