Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Scientists reveal how disease bacterium survives inside immune system cell


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:

More articles from Life Sciences:

nachricht Biologists unravel another mystery of what makes DNA go 'loopy'
16.03.2018 | Emory Health Sciences

nachricht Scientists map the portal to the cell's nucleus
16.03.2018 | Rockefeller University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>