Meningitis Causing Fungi Change its Shape to Enter the Brain

Scientists have found a fungus that can alter its shape to fit inside the brain. According to a report published in the journal Cell Host & Microbe, a pathogenic fungus can change its shape to fit past the blood-brain barrier that keeps pathogens out of the brain.

Cryptococcus Neoformans

The culprit pathogenic fungus is called Cryptococcus neoformans (C. neoformans), C. neoformans is a naturally occurring organism that lives on decaying wood or in bird droppings. The CDC states that if the fungus is inhaled, it can cause cryptococcal meningitis by infecting the lungs as well as other organs like the brain.

A pathologist from the University of Utah and co-author of the study, Jessica Brown, told Newsweek that the changes that the substance goes through when it first enters the body are pretty incredible and that researchers are still working to understand them.

Cryptococcal Meningitis

Since cryptococcal meningitis is a relatively uncommon condition, the majority of healthy people are not at risk of contracting it. It most frequently affects those with compromised immune systems.

According to Medical News Today, people with low CD4 counts are more prone to developing cryptococcal meningitis. White blood cells, called CD4 cells, sometimes referred to as T cells, are essential for the immune system.

Low CD4 counts are common among those with HIV and AIDS, making them far more susceptible to developing cryptococcal meningitis than healthy individuals.

Cryptococcus Neoformans Enters the Brain

The researchers discovered that the tiniest C. neoformans made their way into the brains of the mice they were researching. This caused changes to the surfaces of the small cells.

Brown noted that the Cryptococcus cells in the lungs are quite diverse, coming in a variety of shapes and sizes. She said that she was startled when her graduate student showed her images of the homogeneity of brain cells.

Scientists show that extrapulmonary organ entrance depends on the development of a tiny C. neoformans morphotype, also known as seed cells, because of their tendency to colonize. Fungal cell size and surface expression variations in seed cells lead to improved macrophage uptake.

According to Brown, the altered cell surface of these seed cells makes macrophages suck them up.

Macrophages pick up invaders and try to sequester and eliminate them. They believe that seed cells take advantage of this tendency to be taken by the macrophage into the organ more easily and that if the conditions are suitable, as they are in the brain, they can then escape and grow in their new organ habitat.

Seed Cells in the Brain

The first type of cells to emerge when a seed cell enters the brain is known as titan cells because they are enormous and have at least four times as much DNA as a normal C. neoformans cell. These infected seed cells immediately give rise to these titan cells. The small cells that enter the brain and serve as the study's seed cells most likely do not originate as a result of another cell shrinking.

Instead, they believe that seed cells develop across multiple generations: after receiving a signal, a normal or titan cell divides to create a new cell, but instead of producing another one exactly like it, it produces a seed cell. When the seed cells divide, they probably produce other seed cells.

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