Corporate Banner
Satellite Banner
Immunology
Scientific Community
 
Become a Member | Sign in
Home>News>This Article
  News
Return

Scientists Discover how Cells Distinguish Friend from Foe

Published: Wednesday, April 03, 2013
Last Updated: Wednesday, April 03, 2013
Bookmark and Share
Researchers at UC Davis have shown how the innate immune system distinguishes between dangerous pathogens and friendly microbes.

Like burglars entering a house, hostile bacteria give themselves away by breaking into cells. However, sensing proteins instantly detect the invasion, triggering an alarm that mobilizes the innate immune response. This new understanding of immunity could ultimately help researchers find new targets to treat inflammatory disorders. The paper was published in Nature on March 31.

The immune system has a number of difficult tasks, including differentiating between cells and microbes. However, the body, particularly the digestive tract, contains trillions of beneficial microbes, which must be distinguished from dangerous pathogens.

"We are colonized by microbes. In fact, there are more bacteria in the body than cells," said senior author Andreas Bäumler, professor and vice chair of research in the UC Davis Department of Medical Microbiogy and Immunology. "The immune system must not overreact to these beneficial microbes. On the other hand it must react viciously when a pathogen invades."

The key to distinguishing between pathogenic and beneficial bacteria are their differing goals. Ordinary digestive bacteria are content to colonize the gut, while their more virulent cousins must break into cells to survive. Salmonella achieves this by activating enzymes that rearrange the actin in a cell's cytoskeleton. Fortunately, cellular proteins sense the active enzymes, leading to a rapid immune response.

In the study, the researchers investigated a strain of Salmonella, in both cell lines and animal models, to determine how the innate immune system singles out the bacteria for attack. Salmonella uses a secretion system, a type of molecular syringe, to inject pathogenic proteins, such as SopE, into the cell. SopE activates human GTPase enzymes RAC1 and CDC42, which break down the surrounding actin, allowing the bacterium inside.

But breaking and entering has consequences. Sensing the active GTPase enzymes, and recognizing their pathogenic nature, a protein called NOD1 sends the alarm, signaling other proteins, such as RIP2, that the cell is in danger. Ultimately, this signaling pathway reaches the protein NF-κB, a transcription factor that instructs the genome to mount an immune response, activating genes associated with inflammation, neutrophils and other immune functions.

Though it had been hypothesized that GTPase activation might trigger an immune response to attacking bacteria, prior to this study, no one had identified the pathway to NF-κB. These results were somewhat surprising, as NOD1had been thoroughly studied; leading many researchers to conclude it had no further mysteries to divulge. No one expected it to play such a significant role in alerting the innate immune system that cells were under attack.

These results could help researchers find new targets to combat inflammatory diseases. For example, NF-κB is known to be involved in a variety of conditions, such as inflammatory bowel disease, arthritis, sepsis and others. By understanding the pathways that activate inflammation, scientists and clinicians can develop ways to inhibit it.

"These pathways might be triggered erroneously because the host thinks there's an infection," said Bäumler. "Knowing the pathways and how they are activated is critical to controlling them."


Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,400+ scientific posters on ePosters
  • More than 3,700+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Scientists Create CRISPR/Cas9 Knock-In Mutations in Human T Cells
In a project spearheaded by investigators at UC San Francisco, scientists have devised a new strategy to precisely modify human T cells using the genome-editing system known as CRISPR/Cas9.
Tuesday, July 28, 2015
Engineers Crack DNA Code of Autoimmune Disorders
Researchers have identified an unexpectedly general set of rules that determine which molecules can cause the immune system to become vulnerable to the autoimmune disorders lupus and psoriasis.
Wednesday, June 10, 2015
Using microRNA Fit to a T (Cell)
Researchers show B cells can deliver potentially therapeutic bits of modified RNA.
Friday, November 29, 2013
Autoimmune Disease Strategy Emerges from Immune Cell Discovery
UCSF experiments halt pancreas destruction in mouse model of diabetes.
Wednesday, September 11, 2013
Tuberculosis and Parkinson’s Disease Linked by Unique Protein
UCSF researchers seek way to boost protein to fight both diseases.
Wednesday, September 11, 2013
Therapy Could Treat Breast Cancer that's Spread to Brain
Researchers have successfully combined cellular therapy and gene therapy in a mouse-model system to develop a viable treatment strategy for breast cancer that has spread to a patient's brain.
Tuesday, August 06, 2013
Immune System Molecule Promotes Tumor Resistance
A team of scientists has shown for the first time that a signaling protein involved in inflammation also promotes tumor resistance to anti-angiogenic therapy.
Tuesday, August 06, 2013
Intestinal Bacteria May Fuel Inflammation and Worsen HIV Disease
Changes in intestinal bacteria may help explain why successfully treated HIV patients still experience life-shortening chronic diseases.
Friday, July 12, 2013
Prenatal Maternal Antibodies Affect Child Development
Prenatal exposure to specific combinations of antibodies found only in mothers of children with autism leads to changes in the brain that adversely affect behavior and development.
Wednesday, July 10, 2013
Absence of Gene Leads to Earlier, More Severe Case of Multiple Sclerosis
UCSF finding in animal study may lead to biomarker that predicts course of disease in humans.
Tuesday, June 25, 2013
Developmental Protein Plays Role in Spread of Cancer
A protein used by embryo cells during early development, and recently found in many different types of cancer, apparently serves as a switch regulating metastasis.
Tuesday, June 18, 2013
Depression Linked to Telomere Enzyme, Aging, Chronic Disease
The first symptoms of major depression may be behavioral, but the common mental illness is based in biology — and not limited to the brain.
Thursday, May 23, 2013
Program for Breakthrough Biomedical Research to Celebrate 15 Years
A program that fosters basic science projects of potentially high impact is celebrating 15 years of discovery at UC San Francisco.
Tuesday, May 21, 2013
UCSF Scientists Use Human Stem Cells to Generate Immune System in Mice
Raising hopes for cell-based therapies, UC San Francisco researchers have created the first functioning human thymus tissue from embryonic stem cells in the laboratory.
Friday, May 17, 2013
Tumor-Activated Protein Promotes Cancer Spread
Researchers report that cancers physically alter cells in the lymphatic system to promote the spread of disease.
Tuesday, May 14, 2013
Scientific News
Sorting Through Cellular Statistics
Aaron Dinner, professor in chemistry, and his graduate student Herman Gudjonson are trying to read the manual of life, DNA, as part of the Dinner group’s research into bioinformatics—the application of statistics to biological research.
Women’s Immune System Genes Operate Differently from Men’s
A new technology reveals that immune system genes switch on and off differently in women and men, and the source of that variation is not primarily in the DNA.
Experimental MERS Vaccine Shows Promise in Animal Studies
A two-step regimen of experimental vaccines against Middle East respiratory syndrome (MERS) prompted immune responses in mice and rhesus macaques, report National Institutes of Health scientists who designed the vaccines.
HIV Susceptibility Linked to Little-Understood Immune Cell Class
High levels of diversity among immune cells called natural killer cells may strongly predispose people to infection by HIV, and may be driven by prior viral exposures, according to a new study.
New Weapon in the Fight Against Blood Cancer
This strategy, which uses patients’ own immune cells, genetically engineered to target tumors, has shown significant success against multiple myeloma, a cancer of the plasma cells that is largely incurable.
Scientists Create CRISPR/Cas9 Knock-In Mutations in Human T Cells
In a project spearheaded by investigators at UC San Francisco, scientists have devised a new strategy to precisely modify human T cells using the genome-editing system known as CRISPR/Cas9.
Researchers Develop Vaccine that Protects Primates Against Ebola
A collaborative team from The University of Texas Medical Branch at Galveston and the National Institutes of Health have developed an inhalable vaccine that protects primates against Ebola.
Universal Flu Vaccine in the Works
A new study has demonstrated a potential strategy for developing a flu vaccine with potent, broad protection.
Immunotherapy Shows Promise for Myeloma
A strategy, which uses patients’ own immune cells, genetically engineered to target tumors, has shown significant success against multiple myeloma, a cancer of the plasma cells that is largely incurable.
Immune System 'On Switch' Breakthrough Could Lead to Targeted Drugs
A crucial 'on switch' that boosts the body's defenses against infections has been successfully identified in new scientific research.
SELECTBIO

Skyscraper Banner
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,400+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,700+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FREE!