Fungi That Modifies Itself to Spread Infection

A fungus that frequently causes fungal meningitis undergoes a stunning change once it enters the body, enabling it to infect the brain. Mice studies reveal that the fungal invader shrinks and develops traits that aid in spreading infection as it moves through the body within a few days. The finding might inspire novel tactics for thwarting Cryptococcus neoformans infection and averting negative consequences for the host. C. neoformans is the most common cause of a fatal swelling of the brain. It affects people with compromised immune systems.

“Cryptococcus cells in the lungs are very diverse, with different sizes and different appearances. So, when my graduate student showed me pictures of the uniformity of cells from the brain, I was shocked. It suggested that there was some very strong reason why only this population of cells were making it that far into the body,” said Jessica Brown, PhD, associate professor of pathology at University of Utah Health and the study’s senior author.

Can Cryptococcus neoformans Adapt to Different Microenvironments in the Body?

The fungus adapts quickly to the microenvironments of the body. The fact that the fungus grows in so many diverse environments is what initially piqued Brown's interest in it. The organism can be found alive in decaying wood and bird droppings in the wild. On accidental inhalation of the fungus, it can persist in the lungs before moving through the circulation to the brain and other organs. Each of these organs have a different microenvironment.

In the past, other researchers have discovered that the fungus grows to 10 times its size to survive in the lungs, presumably because it is too big for the host immune system to kill. Nevertheless, fungus cells are significantly smaller in other areas of the body. Brown pondered whether the extra-small size of the cells could serve as a benefit of some sort.

Brown's team discovered that a particular chemical- phosphate-could cause the shift after looking for triggers. Brown hypothesizes that the chemical builds up in the lungs. It is the first place for the fungus to settle after entering the body, because phosphate is released when tissue gets harmed during infection. As a result, the fungal cells might change into seed cells, aiding in infection spread.

Bird Guano’s Role in Aiding Cryptococcus neoformans to Target the Brain

Oddly enough, bird guano may have played a role in the fungus's capacity to target the brain successfully. Pigeon droppings, which contain a lot of the chemical phosphate that activates seed cells, provide a favourable environment for C. neoformans to flourish. Like nothing else they had tried, Brown's team discovered that the sticky material pushes C. neoformans into that other condition.

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According to Brown, this might show how the fungus's pathogenicity first developed. “We think that selective pressures from environmental niches like pigeon guano are somehow able to confer on C. neoformans the ability to infect mammals,” she says.

Regardless of how the fungus acquired its spreading capacity, Brown's team is currently attempting to disable it with FDA-approved medications. They are investigating if a substance that prevents C. neoformans from developing into seed cells might already exist. It can be a ready-to-use treatment for preventing or treating fungal meningitis.

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Source-Medindia