'Copycat' fungus deceives the immune system

Fungus can imitate signals from our immune system and prevent our body from responding to infection, new research has found.

Life-threatening fungal infection is a major killer of people with immune system problems such as blood cancers, HIV infection or following organ transplant. One of the most dangerous infections for people with HIV/AIDS, Cryptococcus neoformans, causes hundreds of thousands of deaths worldwide every year.

Fungi are known to make molecules similar to those of our own immune system, but why fungi make these molecules and what their function is has been a longstanding mystery. Now, scientists led by the University of Sheffield have identified how immune signals called prostaglandins, made by fungi, are able to disarm immune cells.

“We’ve discovered that these immune signals — fungal prostaglandins — deactivate immune cells, preventing them from destroying the infection,” said research leader Dr Simon Johnston.

“We found the fungus was activating a normal immune pathway that prevents overstimulation of the immune system, but is essential in stopping infections.”

The team found that C. neoformans fungi which are not able to make these signals were less able to grow during infection. And given that C. neoformans is potentially life-threatening in those with weakened immune systems, these results could be seen as a vital breakthrough.

“We are now working to find other ways these fungal molecules are affecting immune cells and how the immune cells are deactivated,” Dr Johnston said.

“The same deactivation of immune cells is seen in other diseases such as cancer. Our findings mean that we now have a new approach to solving this problem and will help the development of new treatments.”

The study was published in the journal PLOS Pathogens and funded by the Medical Research Council (MRC) and the British Infection Association. Dr Anna Kinsey, program manager for viral and fungal infections at the MRC, spoke about the importance of research in this field.

“Current antifungal therapies are poorly tolerated and toxic and, significantly, resistance to these agents is increasing,” she said. “As such, there is an urgent need for new treatments, which first requires a better understanding of the interaction of the fungal pathogen with the body’s immune system.”

Image credit: ©stock.adobe.com/au/Kateryna_Kon

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