Cryptococcus Feasts on Inositol in the Brain
A virtual feast could be going on in your brain at this very moment, one in which the Cryptococcus fungi are consuming sugar in the form of inositol. The B vitamin inositol is a favorite food of Cryptococcus, and the human brain and spinal cord are the body’s prime dining sites.
Cryptococcus neoformans, according to the National Institutes of Health, is a fungus that causes cryptococcosis, an infection that may settle in the lungs or spread throughout the body. The fungus is usually found in soil and enters the body when it is inhaled, often when soil is blown by the wind or disturbed in some other manner.
While people who have a healthy immune system typically do not experience any symptoms of the infection, individuals who have a compromised immune system, as do people who have HIV, those taking high doses of corticosteroids, those undergoing chemotherapy, or people who have Hodgkin’s disease, may become ill when the Cryptococcus organism spreads to the brain.
In these individuals, infection with Cryptococcus fungus can result in meningoencephalitis, swelling and irritation of the brain and spinal cord. Symptoms can include double vision, bone and chest pain, confusion, fatigue, fever, headache, nausea, rash, swollen glands, unintentional weight loss, and weakness. Central nervous system involvement can lead to death or permanent damage.
A team of researchers from various institutions, including Duke University, University of Medicine and Dentistry of New Jersey, University of British Columbia, and the University of South Florida, report that Cryptococcus has nearly a dozen genes that permit the fungus to borrow and thrive on inositol in a person’s brain, allowing the fungi to reproduce. Typical fungi have only two such genes.
“Inositol is abundant in the human brain and in the fluid that bathes it,” explains Joseph Heitman, MD, PhD, chairman of the Duke Department of Molecular Genetics and Microbiology, “which may be why this fungus has a predilection to infect the brain and cause meningitis.”
Lead author Chaoyang Xue, PhD, assistant professor at the Public Health Research Institute at the University of Medicine and Dentistry of New Jersey, speculates that Cryptococcus fungi learned to attack inositol in the brain because they adapted to grow on wild plants, which also have high levels of inositol.
Cryptococcus fungi’s love of sugar in the form of inositol may be its downfall some day, says Heitman. “Now scientists may be able to target the fungi by developing ways to put them on the fungal equivalent of an Atkin’s low-carbohydrate diet so they will stop multiplying.” And then life will not be so sweet for this potentially deadly fungus.
Duke University news release
National Institutes of Health