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Giant Cells Protect Potentially Deadly Fungus During Infection

Giant cells called "titan cells" created by the fungus Cryptococcus neoformans protect the fungus during infection, according to two University of Minnesota researchers. Kirsten Nielsen, Ph.D., an assistant professor in the department of microbiology, and recent Ph.D. recipient Laura Okagaki believe their discovery could help develop new ways to fight infections caused by Cryptococcus. The findings will be published in the June 2012 issue of the journal Eukaryotic Cell. Cryptococcus, a fungus frequently found in dust and dirt, is responsible for the deaths of more than 650,000 AIDS patients worldwide each year. It is also a potentially deadly concern among chemotherapy and organ transplant patients. Currently, Cryptococcus causes more annual deaths in sub-Saharan Africa than tuberculosis. "While most healthy individuals are resistant to Cryptococcus infections, the fungus can cause deadly disease for those with already weak immune systems," said Dr. Nielsen. When inhaled, Cryptococcus can cause an infection in the lungs. This infection can spread to the brain and result in meningitis, an often-deadly inflammation of the brain and spine. Drs. Nielsen and Okagaki found that titan cells, or Cryptococcus cells ten to twenty times the size of a normal cell, are too large to be destroyed by the body's immune system. The researchers also found that the presence of titan cells can protect all Cryptococcus cells in the area, even the normal-sized Cryptococcus cells. "This tells us that titan cell formation is an important aspect of the interaction between the human/host and the organism that allows Cryptococcus to cause disease," said Dr. Nielsen. "This information will help us find new ways to treat Cryptococcus infections that are very difficult to treat with currently available drugs." [Press release] [Eukaryotic Cell journal]