New Science research provides new insights into the invasion of deadly fungi into the lungs

Fungi like Aspergillus are very common in our environment, and we inhale hundreds to thousands of spores every day
.
For healthy people, fungi usually do not pose a threat, but for people with compromised immune systems, they can cause fatal infections
.
However, it is increasingly recognized that viral infections such as influenza or SARS-CoV-2 increase the risk of
invasive Aspergillus infection, even in healthy people.

The World Health Organization (WHO) says invasive fungal infections pose a growing threat to human health and reiterates the need for more research
.
Until now, it was not known how Aspergillus took root or how to get rid of it
.
Researchers at the University of Calgary, in collaboration with researchers at McGill University, have provided new insights
into why the immune system fails.

Nicole Sarden, a PhD candidate at the University of Calgary and first author of the study, said: "We found that influenza and COVID-19 disrupt a previously unknown natural immunity that we need to fight invasive fungal infections
.
"

The findings, published in Science Translational Medicine, show that two types of white blood cells (neutrophils and a unique type of B cell) often work together to fight fungal infections
.
However, viruses like SARS-CoV-2 and influenza can prevent this particular B cell from functioning
.
By studying blood and tissue samples from mice and humans, the researchers were able to see that after a viral infection, neutrophils sensed a fungal infection and gathered nearby, but did not destroy the invaders
as expected.
The scientists dug deeper and found that viral molecules make these B cells indifferent, preventing them from working with neutrophils as they normally would, thus protecting the fungus from destruction
.
Understanding this process leads to the next discovery
.

"We have also found that current treatments can be repurposed in a realistic and meaningful way to replace natural antibodies that cannot be produced by virus-damaged B cells and to re-establish the ability
of neutrophils to fight these infections.
"

"This study was triggered by a young man I was caring for in the intensive care unit who died of flu-associated aspergillosis, and every treatment we tried failed," said Dr.
Bryan Yipp, a clinical researcher at the Cumming School of Medicine and senior author
of the study.
"Our findings are timely
, given the large number of patients infected with multiple respiratory viruses, including influenza.
"

Sarden and Yipp believe the findings will lay the groundwork for new diagnostic tests that predict who is at highest risk of invasive fungal infections based on natural antibody levels, and that currently available antibody replacement strategies could be tested in future clinical trials for the treatment of Aspergillus infection
.

"These findings provide a new understanding
of how we can best support the body against deadly fungal infections," Yipp said.