Australian researchers have found a link between elevated levels of a specific enzyme and worsening of patients with severe respiratory illnesses, such as influenza and COVID-19. The discovery could help explain why people vary in the severity of viral infections.
The research team, led by Professor Katherine Kedzierska from the University of Melbourne’s Doherty Institute, studied blood samples from patients with severe cases of seasonal influenza, COVID-19 and respiratory syncytial virus. Samples were also analysed from children with inflammation linked to COVID-19.
Scientists found that levels of an enzyme called oleol-ACP-hydrolase were abnormally high in patients with severe cases, including some deaths. This enzyme is important for producing fatty acids that make up cell membranes and store energy.
“Everyone has low levels of oleol-ACP-hydrolase, which is a very important enzyme because it is involved in the production of fatty acids, which are components of fat,” Kedzierska said.
These fats are important for forming cell membranes and storing energy in the body.
“But in some patients with life-threatening illnesses, this enzyme is produced at much higher levels, while in healthy individuals and patients with mild illnesses, it is produced at very low levels,” she said.
survival rate
Other studies in mice have shown that a deficiency of the enzyme oleoyl-ACP-hydrolase reduces the severity of infection and pneumonia and increases survival. Researchers believe that this enzyme may trigger an excessive immune response that leads to severe inflammation.
These results were published in the prestigious scientific journal Cell. Professor Kedzierska hopes to conduct larger studies to evaluate the feasibility of using this enzyme as a diagnostic marker to predict which patients may face serious complications.
Other experts described the discovery as an important advance in understanding why the severity of infection varies between individuals, but stressed the need for more research to determine the exact role of this enzyme and the mechanism of its action.
Professor Peter Openshaw, a respiratory physician and immunologist at Imperial College London, said the findings were “exciting science”.
While Alan Cheng, professor of infectious disease epidemiology at Monash University, described the researchers’ discovery as “potential to enhance our understanding of why some people get severe infections and others don’t.”
But “there are still a lot of questions,” Cheng said, such as whether fat and glycogen are the only important pathway in identifying patients who develop severe disease, and whether there are opportunities for intervention to improve outcomes for these patients.
The research team now aims to develop diagnostic tests based on this discovery to identify patients at risk of severe disease upon admission to hospital.