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Benjamin Tang

Associate Professor Benjamin Tang

 

When good cells turn bad: How the flu can turn deadly

31 Jul 2019

 

New research shows the cellular foot soldiers your body deploys to fight the flu can turn against you and quickly transform a mild bout of influenza into a severe infection that can kill even the fittest person.

The international study led by Nepean Hospital and published in Nature Communications has for the first time revealed a possible explanation why otherwise healthy people sometimes die from the flu.

Lead author and intensive care specialist at Nepean Hospital, Associate Professor Benjamin Tang says key immune cells drive an ‘over-reaction’ in some patients’ immune systems which damages their lungs.

“We found the immune system becomes disorganised in patients with severe flu infection. Neutrophils, a specific type of immune cell which should be attacking the virus, started to attack healthy lung tissue and produce massive inflammation.

“This causes breathing difficulty, dangerously dropping blood oxygen levels and sadly, in some cases, causing respiratory failure and death,” says Associate Professor Tang, who performed his research in both Nepean Hospital and The Westmead Institute for Medical Research.

Scientists have long known that the immune system can attack the body but previously this was mostly seen in people with autoimmune disease.

“This is the first time we’ve been able to show the immune system turning against the body in otherwise healthy people who are infected with the flu,” says Associate Professor Tang.

In the 2009 global flu pandemic, Associate Professor Tang and his colleagues in the Nepean Hospital intensive care unit were treating patients infected with swine flu.

“Healthy people in the prime of their lives were ending up in our intensive care unit with the flu. It didn’t make sense and it inspired us to look deeper. To look for the mechanism that triggers mild flu to suddenly become severe and potentially deadly,” says Associate Professor Tang.

The Nepean Hospital team reached out to doctors and scientists around Australia, Germany, Canada, the Czech Republic and the USA to build a cross-disciplinary collaboration of physicians, geneticists and scientists.

From 2009 to 2016, the researchers collected blood and airway samples from 720 patients across 20 hospitals in Australia, Canada and Germany to help map out the activity of hundreds of immune pathways in each patient. To help zero in on the triggers for the infection turning from mild to severe, the study authors also accounted for the patient’s age, pre-existing health conditions, the strain of influenza and duration of symptoms.

“In the clinical setting, measuring neutrophil-related abnormal changes may improve our ability to identify which patients are at risk of progressing from mild to severe influenza,” says Associate Professor Tang.

“The discovery also identifies a new pathway for potential treatments to be developed to tame the immune system, reduce the collateral damage caused by the body’s defences against the flu virus and save lives.”

Associate Professor Tang also leads a team at Nepean Hospital who have patented a world-leading blood test which can identify which patients are at risk of developing life-threatening complications while infected with influenza.

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