Blood Cells
© GettyThe biomarker predicts hospitalisation and deaths from sepsis.
Scientists have found a biomarker in the blood that can tell if a person is more likely than others to die early from pneumonia or sepsis.

The biomarker is associated with chronic inflammation, perhaps due to microbial infection, and predicts death from infection up to 14 years in the future, said researchers today in the journal Cell Systems.

But, the researchers warned further research was needed before a test for the biomarker would be warranted.

In the past year, scientists have found that when a collection of common proteins called GlycA is elevated in the blood, a person is more likely to die prematurely.

"Per unit increase of GlycA, you get an increased risk of death, from any cause, of between 40 and 50 per cent," said Dr Michael Inouye from the University of Melbourne's Centre for System Genomics. But little was known about the biology of the GlycA biomarker, and how it could lead to early death.

"We wanted to understand why, because without that you can't remove the risk," said Dr Inouye.

He and colleagues analysed data, much of it electronic records, on over 10,000 adults from Finland and found that those who had elevated GlycA tended to be more likely to die from sepsis and pneumonia.

"As GlycA increases, your risk of disease increase," Dr Inouye said.

"There were some strong associations. People who had one unit increase in GlycA levels were at 2.2 fold increased risk from sepsis, which makes up the majority of systemic infections."

Importantly, the study showed that when GlycA levels became elevated they tended to remain so for up to a decade, and GlycA predicted death from infection up to 14 years in the future.

GlycA linked to elevated inflammatory markers

Given that GlycA is involved in the initiation of the body's inflammatory response, Dr Inouye and colleagues decided to use a computer model to look at the relationship between these elevated levels and other parts of the immune system.

The model showed that when GlycA blood levels were high, so were the levels of 30 different immune-signalling molecules, called cytokines.

High levels of cytokines are a sign of an overactive immune system and have been linked to disease, said Dr Inouye.

The study also showed that people who recently had an acute infection had both elevated GlycA and elevated neutrophils, which are cells that are also involved the inflammatory response, particularly to microbial infection.

This suggests that GlycA is linked to premature death because it is a marker of chronic inflammation, which may be triggered by microbial infection, said the researchers.

"Chronic inflammation is a low-level risk factor for all sorts of things," said Dr Inouye.

The link between GlycA and increased risk of death from sepsis seen in the study could be as a result of chronic inflammation making it more difficult for the body to cope with acute infection, he said.

Dr Inouye said further research was needed to confirm the predictive power of GlycA and to understand how it might be possible to intervene to lower the risk it posed.

"It's not a particularly useful biomarker unless you can do something about it," he said.

"In a clinical setting you wouldn't want to be offering a test for GlycA to your patient unless you can do something about it."