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 A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>