Featured Research

from universities, journals, and other organizations

Vitamin A Signals Offer Clues To Treating Autoimmunity

Date:
March 10, 2009
Source:
Emory University
Summary:
Dendritic cells, the microbe-sensing alarms of the immune system, can send out a "red alert" to stimulate immunity, or a "calm down" message that tones down excessive immunity that might damage the host. The "calm down" message makes use of vitamin A, providing an explanation for the link between vitamin A deficiency and autoimmune diseases. Bacteria and viruses that cause chronic infections, such as tuberculosis, hepatitis C and HIV, may have evolved strategies that skew this balance of signals in their favor.

Dendritic cells, the microbe-sensing alarms of the immune system, can send out a "red alert" to stimulate immunity, or a "calm down" message that tones down excessive immunity that might damage the host. The "calm down" message makes use of vitamin A, providing an explanation for the link between vitamin A deficiency and autoimmune diseases.

Related Articles


Bacteria and viruses that cause chronic infections, such as tuberculosis, hepatitis C and HIV, may have evolved strategies that skew this balance of signals in their favor.

Distributed around the body, dendritic cells act as the security alarms of the immune system. After sensing the presence of intruders, dendritic cells can transmit the alarm to white blood cells or tell them to relax, depending on the signals they send out.

Researchers at the Emory Vaccine Center and Yerkes National Primate Research Center have discovered that dendritic cells can respond to the same compound, through two different receptors, by sending out both stimulatory and calming messages at once.

The compound is zymosan, a component of yeast cell walls. However, the finding could guide scientists in designing vaccines against many infectious agents since the calming receptor is known to respond to bacteria and viruses as well as yeast. In addition, silencing the calming receptor's messages might boost the immune system's ability to fight a chronic infection.

The results are published in the March 2009 issue of Nature Medicine.

The calming receptor, known as TLR2 (Toll-like receptor 2), uses vitamin A to transmit its signals, which provides an explanation for the connection between vitamin A deficiency and autoimmune diseases. Vitamin A deficiency has been linked to diseases such as rheumatoid arthritis, lupus and type I diabetes.

This "two signals at once" feature of the immune system can be viewed as the result of an evolutionary tug of war, says senior author Bali Pulendran, PhD, professor of pathology and laboratory medicine at Emory University School of Medicine and Yerkes National Primate Research Center.

"The immune system has to provide a defense against infection, while avoiding the destruction of too much of the body along the way," he says. "At the same time, pathogens have evolved strategies to manipulate the immune system for their own purposes."

Working with Pulendran, postdoctoral fellow Santhakumar Manicassamy, PhD, examined which genes are turned on in dendritic cells by zymosan in cell culture. They were surprised to find that both zymosan and live Candida albicans, which causes yeast infections, turned on genes involved in converting vitamin A to its active form, retinoic acid.

"Others have seen that these genes are turned on constitutively in the gut, but seeing how they can be induced elsewhere is new," Pulendran says.

Manicassamy and colleagues found that dendritic cells use retinoic acid along with other chemical messengers to steer white blood cells into a regulatory mode, rather than an attack mode. For dendritic cells to do so, they need TLR2, since zymosan also activates another receptor called dectin-1, which sends out stimulatory signals.

The effects of zymosan and TLR2 can deter white blood cells from attacking nerve tissue in a mouse model of multiple sclerosis, the authors found.

In the model, mice are immunized against myelin, which forms a protective sheath around nerves. Injecting the mice with zymosan at the same time as immunization reduced the damage to their nerves.

The research was supported by the National Institutes of Health.


Story Source:

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


Journal Reference:

  1. S. Manicassamy et al. TLR2-dependent induction of vitamin A metabolizing enzymes in dendritic cells promotes T regulatory responses and inhibits Th-17-mediated autoimmunity. Nature Medicine, March 2009

Cite This Page:

Emory University. "Vitamin A Signals Offer Clues To Treating Autoimmunity." ScienceDaily. ScienceDaily, 10 March 2009. <www.sciencedaily.com/releases/2009/03/090301181421.htm>.
Emory University. (2009, March 10). Vitamin A Signals Offer Clues To Treating Autoimmunity. ScienceDaily. Retrieved October 30, 2014 from www.sciencedaily.com/releases/2009/03/090301181421.htm
Emory University. "Vitamin A Signals Offer Clues To Treating Autoimmunity." ScienceDaily. www.sciencedaily.com/releases/2009/03/090301181421.htm (accessed October 30, 2014).

Share This



More Health & Medicine News

Thursday, October 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Mind-Controlled Prosthetic Arm Restores Amputee Dexterity

Mind-Controlled Prosthetic Arm Restores Amputee Dexterity

Reuters - Innovations Video Online (Oct. 29, 2014) A Swedish amputee who became the first person to ever receive a brain controlled prosthetic arm is able to manipulate and handle delicate objects with an unprecedented level of dexterity. The device is connected directly to his bone, nerves and muscles, giving him the ability to control it with his thoughts. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Google To Use Nanoparticles, Wearables To Detect Disease

Google To Use Nanoparticles, Wearables To Detect Disease

Newsy (Oct. 29, 2014) Google X wants to improve modern medicine with nanoparticles and a wearable device. It's all an attempt to tackle disease detection and prevention. Video provided by Newsy
Powered by NewsLook.com
Can Drinking Milk Lead To Early Death?

Can Drinking Milk Lead To Early Death?

Newsy (Oct. 29, 2014) Researchers in Sweden released a study showing heavy milk drinkers face an increased mortality risk from a variety of causes. Video provided by Newsy
Powered by NewsLook.com
Obama: The US Will Not 'run and Hide' From Ebola

Obama: The US Will Not 'run and Hide' From Ebola

AP (Oct. 29, 2014) Surrounded by health care workers in the White House East Room, President Barack Obama said the U.S. will likely see additional Ebola cases in the weeks ahead. But he said the nation can't seal itself off in the fight against the disease. (Oct. 29) Video provided by AP
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:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

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