Featured Research

from universities, journals, and other organizations

In the gut, immunity is a two-way street: Complex role of gut bacteria

Date:
July 10, 2014
Source:
RIKEN
Summary:
In recent years, it has become increasingly clear that many diseases are triggered or maintained by changes in bacterial communities in the gut. However, the general view up to now has been rather simple: bacteria stimulate the immune system, leading to inflammation or autoimmune disorders in a single direction. Now scientists have painted a more complex picture: the gut immune system does not simply prevent the influx of pathogens, but is actively involved in the maintenance of a rich and healthy community of gut bacteria.

Cecal bacteria from mice with rich (left panel) or poor (right panel) bacterial communities.
Credit: Image courtesy of RIKEN

In recent years, it has become increasingly clear that many diseases are triggered or maintained by changes in bacterial communities in the gut. However, the general view up into now has been rather simple: bacteria stimulate the immune system, leading to inflammation or autoimmune disorders in a single direction.

Now, in work published in Immunity, scientists led by Sidonia Fagarasan from the RIKEN Center for Integrative Medical Science in Japan have painted a more complex picture: the gut immune system does not simply prevent the influx of pathogens, but is actively involved in the maintenance of a rich and healthy community of gut bacteria. They propose that faults in the immune regulation lead to changes in the bacterial community that in turn feed back into the immune system.

In the study, the group demonstrated that the regulation by immune T cells of immunoglobulin A (IgA), an antibody that plays a key role in immunity in the gut, is critical for the maintenance of rich bacterial communities in mammal guts.

They began by studying mice with various immune deficiencies and attempted to restore the mice by providing the missing components. They monitored the bacterial communities in the mice's guts with or without the reconstitutions and evaluated the flow of information between the immune system and bacteria. They discovered that the precise control of IgA production by regulatory T cells is critical for keeping a rich and balanced bacterial community.

To investigate how bacteria feed back to the host, they looked at germ-free mice (mice born and maintained sterile in special incubators) and young pups that had been transplanted with different bacterial communities (either by injection of bacteria or by painting the fur with fecal bacteria extracts from normal or immune-deficient mice). They discovered that the immune system "sees" and responds differently to different bacterial communities. Rich and balanced bacterial communities seem to be perceived as "self" and induce a quick maturation of the immune system and gut responses (induction of regulatory T cells and IgA), while a poor and unbalanced bacterial community is apparently perceived as "non-self" and induces responses aimed at eliminating it (T cells with inflammatory properties and IgG or IgE responses).

According to Sidonia Fagarasan, who led the work, "This study should have an impact on the way we understand immune-related disorders associated with bacteria dysbiosis in the gut. In order to reestablish a healthy state we need to interfere not only with the bacteria, by providing probiotics or through fecal transplantation, but also with the immune system, by correcting the faults caused either by inherited deficiencies or by aging."

"It was surprising," she continues, "to see how the reconstitution of T cell-deficient mice with a special regulatory T cell type leads to dramatic changes in gut bacterial communities. It was spectacular to see how the immune system perceives and reacts to different bacteria communities. It gives us hopes that with a better knowledge of the symbiotic relationships between the immune system and bacteria in the gut, we could intervene and induce modifications aiming to reestablish balance and restore health."


Story Source:

The above story is based on materials provided by RIKEN. Note: Materials may be edited for content and length.


Journal Reference:

  1. Shimpei Kawamoto, Mikako Maruya, LuciaM. Kato, Wataru Suda, Koji Atarashi, Yasuko Doi, Yumi Tsutsui, Hongyan Qin, Kenya Honda, Takaharu Okada, Masahira Hattori, Sidonia Fagarasan. Foxp3 T Cells Regulate Immunoglobulin A Selection and Facilitate Diversification of Bacterial Species Responsible for Immune Homeostasis. Immunity, 2014; DOI: 10.1016/j.immuni.2014.05.016

Cite This Page:

RIKEN. "In the gut, immunity is a two-way street: Complex role of gut bacteria." ScienceDaily. ScienceDaily, 10 July 2014. <www.sciencedaily.com/releases/2014/07/140710130613.htm>.
RIKEN. (2014, July 10). In the gut, immunity is a two-way street: Complex role of gut bacteria. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2014/07/140710130613.htm
RIKEN. "In the gut, immunity is a two-way street: Complex role of gut bacteria." ScienceDaily. www.sciencedaily.com/releases/2014/07/140710130613.htm (accessed August 2, 2014).

Share This




More Health & Medicine News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Texas Quintuplets Head Home

Texas Quintuplets Head Home

Reuters - US Online Video (Aug. 1, 2014) After four months in the hospital, the first quintuplets to be born at Baylor University Medical Center head home. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Patient Coming to U.S. for Treatment

Ebola Patient Coming to U.S. for Treatment

Reuters - US Online Video (Aug. 1, 2014) A U.S. aid worker infected with Ebola while working in West Africa will be treated in a high security ward at Emory University in Atlanta. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins