Featured Research

from universities, journals, and other organizations

Light Therapy May Combat Fungal Infections, New Evidence Suggests

Date:
March 24, 2005
Source:
Duke University Medical Center.
Summary:
A newly discovered mechanism by which an infectious fungus perceives light also plays an important role in its virulence, according to Howard Hughes Medical Institute investigators at Duke University Medical Center. The findings suggest that changes in light following fungal invasion of the human body may be an important and previously overlooked cue that sparks infection, the researchers said.

Durham, N.C. – A newly discovered mechanism by which an infectious fungus perceives light also plays an important role in its virulence, according to Howard Hughes Medical Institute investigators at Duke University Medical Center. The findings suggest that changes in light following fungal invasion of the human body may be an important and previously overlooked cue that sparks infection, the researchers said.

Related Articles


The discovery in the human pathogen Cryptococcus neoformans further suggests that light therapy, in combination with anti-fungal drug treatments, might offer an effective method to combat a variety of fungal infections, particularly those of the skin or nails, said HHMI investigator Joseph Heitman, M.D., James B. Duke professor of molecular genetics and microbiology and medicine at Duke.

Light therapy is now used for medical conditions, such as seasonal affective disorder. The most common method, called bright-light therapy, requires that patients sit near a special light box fitted with high-intensity, full-spectrum or white light bulbs. UV irradiation is also used to repigment skin affected by the autoimmune disorder vitiligo.

The findings also have important implications for understanding early fungal evolution, Heitman and study lead author Alexander Idnurm, Ph.D., reported in a forthcoming issue of Public Library of Science Biology, published online March 15, 2005. The National Institute for Allergy and Infectious Diseases and the Burroughs Wellcome Fund supported the research.

The potentially life-threatening fungus C. neoformans invades the central nervous system to cause disease, most commonly in patients who lack a functioning immune system, such as organ transplant recipients, those with HIV/AIDS, and patients treated with steroids or cancer chemotherapy. The fungus' global importance as a health threat has therefore risen in parallel with the increase in immunosuppressive therapies and the worldwide HIV/AIDS epidemic.

Light normally inhibits mating of C. neoformans. The Duke team has now identified two genes responsible for that light response. Loss of the same genes also reduces fungal virulence in mice, they reported.

Earlier studies had linked the genes to light-sensing in another distantly related fungal lineage, an indication that the fungal light sensor arose early in evolution and may be shared by many extant fungal species. Other well-studied fungi, such as Saccharomyces cerevisiae, or baker's yeast, have apparently lost their ability to sense light, Heitman said, and have neither of the conserved light-sensing proteins.

"Fungi have many negative implications for human life as they lead to human disease, as well as plant disease and mold," said Idnurm, a post-doctoral fellow at Duke. "However, fungi also play important beneficial roles, for example, as a source of food and pharmaceuticals.

"Therefore, an understanding of the role of environmental signals such as light in fungal development is vital to increase the benefits and decrease the costs that fungi present."

The researchers first tested the importance of genes with known roles in light sensitivity of another, distantly related fungus. Yeast strains lacking one of those genes, known as white collar 1 (BWC1), mated equally well in the light or the dark, implicating that gene in the fungus' ability to sense light. BWC1 also functions in the fungus' resistance to ultraviolet light, they reported. Further study identified a second, related gene, BWC2, that is also required for C. neoformans normal response to both blue and ultraviolet light.

Moreover, the researchers found, mice inoculated with C. neoformans lacking either of the light-sensing genes remained healthy 30 days later, while those infected with the normal fungus died by day 30.

The finding points to novel virulence pathways, Heitman said, as the BWC1 and BWC2 mutants were not impaired for any of the characteristics previously linked to virulence.

"The genes required for light sensing, while not essential for virulence, do contribute to the rapidity with which the fungus causes lethal infection in the mammalian host," Heitman said. "It is therefore conceivable that light could be used as a therapy for fungal infections, particularly infections at the body surface, such as those of skin or nails." Laser therapy might also be possible for certain fungal sinus infections, he added.

The finding that Cryptococcus shares its light-sensing mechanism with other distantly related fungi also has important implications for understanding fungal evolution, Heitman said. The researchers speculate that evolution of these light-sensing genes more than 400 million years ago may have had major significance for fungal colonization of land, at a time when UV irradiation was particularly intense.


Story Source:

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


Cite This Page:

Duke University Medical Center.. "Light Therapy May Combat Fungal Infections, New Evidence Suggests." ScienceDaily. ScienceDaily, 24 March 2005. <www.sciencedaily.com/releases/2005/03/050323131309.htm>.
Duke University Medical Center.. (2005, March 24). Light Therapy May Combat Fungal Infections, New Evidence Suggests. ScienceDaily. Retrieved February 1, 2015 from www.sciencedaily.com/releases/2005/03/050323131309.htm
Duke University Medical Center.. "Light Therapy May Combat Fungal Infections, New Evidence Suggests." ScienceDaily. www.sciencedaily.com/releases/2005/03/050323131309.htm (accessed February 1, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Sunday, February 1, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nanoscale Sensor Could Help Wine Producers and Clinical Scientists

Nanoscale Sensor Could Help Wine Producers and Clinical Scientists

Reuters - Innovations Video Online (Jan. 30, 2015) A nanosensor that mimics the oral effects and sensations of drinking wine has been developed by Danish and Portuguese researchers. Jim Drury saw it in operation. Video provided by Reuters
Powered by NewsLook.com
Dog-Loving Astronaut Wins Best Photo of 2015

Dog-Loving Astronaut Wins Best Photo of 2015

Buzz60 (Jan. 30, 2015) Retired astronaut and television host, Leland Melvin, snuck his dogs into the NASA studio so they could be in his official photo. As Mara Montalbano (@maramontalbano) shows us, the secret is out. Video provided by Buzz60
Powered by NewsLook.com
U.S. Wants to Analyze DNA from 1 Million People

U.S. Wants to Analyze DNA from 1 Million People

Reuters - US Online Video (Jan. 30, 2015) The U.S. has proposed analyzing genetic information from more than 1 million American volunteers to learn how genetic variants affect health and disease. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Rarest Cat on Planet Caught Attacking Monkeys on Camera

Rarest Cat on Planet Caught Attacking Monkeys on Camera

Buzz60 (Jan. 30, 2015) An African Golden Cat, the rarest large cat on the planet was recently caught on camera by scientists trying to study monkeys. The cat comes out of nowhere to attack those monkeys. Patrick Jones (@Patrick_E_Jones) has the rest. Video provided by Buzz60
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


Plants & Animals

Earth & Climate

Fossils & Ruins

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