Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why doesn't the immune system attack the small intestine?

11.01.2007
New study provides unexpected answer

Answering one of the oldest questions in human physiology, researchers at Dana-Farber Cancer Institute have discovered why the body's immune system - perpetually on guard against foreign microbes like bacteria – doesn't attack tissues in the small intestine that harbor millions of bacteria cells.

In a study in the February issue of Nature Immunology, and which is currently available on the journal's Web site as an advanced online publication, investigators led by Shannon Turley, PhD, of Dana-Farber identify an unlikely group of peacemakers: lymph node cells that instruct key immune system cells to leave healthy tissue alone. The finding, which illuminates a previously unknown corner of the human immune system, may lead to new forms of treatment for autoimmune diseases such as Type 1 diabetes and multiple sclerosis.

"We've discovered that cells not generally thought of as part of the immune system actually play an important role in protecting the intestine from immune system attack," says Turley. "Because the cells are found in lymph nodes throughout the body, they may offer a way of suppressing a variety of autoimmune diseases," which result from immune system assault on healthy tissue.

The immune system distinguishes between normal and foreign agents by small proteins, called antigens, on the cell surface. In parts of the body, such as the pancreas, that are sheltered from the outside environment, cells known as dendritic cells display the antigens of their normal neighbors in a way that puts the immune system "at ease." By reading those antigens without being on alert, the immune system's T cells learn that such cells are off-limits to attack.

For years, scientists have wondered whether the same mechanism is at work in tissues that come in regular contact with bacteria and other microbial organisms. The small intestine, for example, which absorbs essential nutrients from food and drink and protects the body from invasive microbes, is literally teeming with bacteria, which help break down waste. The presence of so many bacteria is a potential trigger for an immune system response. Why do T cells almost always ignore the small intestine, leaving this vital tissue unharmed?

"It's obvious that T cells must be able to ignore – or become 'tolerized' to – normal intestinal tissue," states Turley, who is also an assistant professor of pathology at Harvard Medical School. "But it has been unclear how dendritic cells, which are extremely sensitive to microbial agents such as bacteria, teach T cells to resist attacking healthy intestinal cells."

In the new study, Turley and her colleagues found that, in fact, dendritic cells aren't essential in creating tolerance in T cells. Instead, and unexpectedly, tolerance is produced by stromal cells from nearby lymph nodes. Although they aren't classified as "professional antigen-presenters," as dendritic cells are, the stromal cells serve the same purpose: exhibiting normal-cell antigens to the immune system.

"Our study points to a previously unknown mechanism of immune system tolerance," Turley explains. "When you think of the conditions in the small intestine, with so many millions of bacteria cells and so much opportunity for dendritic cells to stimulate an immune attack, it's remarkable that intestinal tissue is so rarely the target of an immune attack. Our findings demonstrate that the immune system has features that remain to be discovered."

Bill Schaller | EurekAlert!
Further information:
http://www.dfci.harvard.edu
http://www.dana-farber.org

More articles from Studies and Analyses:

nachricht Study relating to materials testing Detecting damages in non-magnetic steel through magnetism
23.07.2018 | Technische Universität Kaiserslautern

nachricht Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Quantum material is promising 'ion conductor' for research, new technologies

17.08.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>