Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Subversive strep bug strategy revealed

29.08.2003


Researchers at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), have discovered how Streptococcus pyogenes (S. pyogenes), the bacterium responsible for "flesh-eating" infections, gains a foothold in the body by subverting a key immune system cell.



"The ability of this very common bug, which causes strep throat and other infections, to modulate the gene activity of an immune system cell is remarkable and has never before been seen on this scale," says Frank R. DeLeo, Ph.D., a researcher at NIAID’s Rocky Mountain Laboratories (RML) in Hamilton, MT. The findings are scheduled to be published in Proceedings of the National Academy of Sciences, USA this week.

Insight into streptococcal infection is one product of a comprehensive picture of immune cell–bacteria interactions developed by the RML scientists. Using microarray technology, Dr. DeLeo and his colleagues created a "snapshot" of how all the genes in a type of white blood cell, called a neutrophil, react following exposure to a variety of bacteria.


"This is work of seminal importance," says NIAID Director Anthony S. Fauci, M.D. "By demonstrating that neutrophils respond with altered gene expression to bacterial invasion, the investigators have exposed dozens of possible targets for drug therapies. These findings are likely to be broadly applicable to many types of microorganisms that cause disease in humans, and could lead to new treatments that augment the immune response against multiple pathogens," he adds.

Neutrophils are the most abundant type of white blood cell and a central player in the body’s innate immune system. Like a S.W.A.T. team, neutrophils swarm to the site of infection in the first few minutes after a bacterial attack. Quickly they engulf the invading organisms and destroy them.

Neutrophils are genetically programmed to shut themselves down after they engulf and kill microbes. Because of this controlled shutdown, cellular debris is cleared away from the site of the infection, and any inflammation subsides. Ordinarily, neutrophils are highly effective at their job. Indeed, notes Dr. DeLeo, the vast majority of infectious organisms never make it past this first line of defense.

The broad outlines of neutrophil action were known previously, Dr. DeLeo says, but details have been scarce because the cells are difficult to study. For example, scientists believed that the fate of a neutrophil was set during its maturation, well before any encounter with a disease organism.

The NIAID scientists examined the struggle between bug and blood cell as it played out at the gene level. First, they mixed neutrophils extracted from the blood of healthy volunteers with bacteria derived from clinical cases of such diverse conditions as pharyngitis, tick-borne relapsing fever, cellulitis, pneumonia and meningitis. Neutrophils engulfed most kinds of bacteria rapidly, between 10 and 60 minutes after encountering them. Three to six hours later, microarray analysis revealed that neutrophil genes involved in recruiting other immune system cells to the site of infection were active, as were genes required for controlled self-destruction. The degree of genetic activity by neutrophils surprised the researchers, Dr. DeLeo says. Far from being mere passive receptacles for microorganisms, neutrophils exhibit considerable genetic complexity and reactivity, the investigators discovered.

The greatest surprise in the study came when the researchers examined S. pyogenes. S. pyogenes stimulated almost 400 neutrophil genes that had not been activated by the other kinds of bacteria. Furthermore, activation occurred much sooner following engulfment. Most significantly, the bacterium caused neutrophils to self-destruct in an uncontrolled fashion. Essentially, explains Dr. DeLeo, S. pyogenes prevents the neutrophil from either recruiting help or completing an orderly shutdown sequence.

"Dr. DeLeo and his co-investigators have gained an important new insight into how S. pyogenes creates conditions favoring its survival," says Thomas Kindt, Ph.D., director of NIAID’s Division of Intramural Research. "Knowing how this extremely common bug evades our immune defenses opens exciting new avenues for research into ways to hamper this evasive maneuver."

NIAID is a component of the National Institutes of Health (NIH), which is an agency of the Department of Health and Human Services. NIAID supports basic and applied research to prevent, diagnose and treat infectious and immune-mediated illnesses, including HIV/AIDS and other sexually transmitted diseases, illness from potential agents of bioterrorism, tuberculosis, malaria, autoimmune disorders, asthma and allergies.


Reference: S D Kobayashi et al. Bacterial pathogens modulate an apoptosis differentiation program in human neutrophils. Proceedings of the National Academy of Sciences. DOI: 10.1073.pnas.1833375100.


Anne A. Oplinger | EurekAlert!
Further information:
http://www.niaid.nih.gov

More articles from Health and Medicine:

nachricht Biofilm discovery suggests new way to prevent dangerous infections
23.05.2017 | University of Texas at Austin

nachricht Another reason to exercise: Burning bone fat -- a key to better bone health
19.05.2017 | University of North Carolina Health Care

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>