People with diabetes have a higher risk of dying if they catch coronavirus - this is due to an overproduction of immune cells in the lungs...
People with diabetes have a higher risk of dying if they catch coronavirus - this is due to an overproduction of immune cells in the lungs, a new study finds.
Experts from Wuhan University found people with high blood glucose levels have a much greater chance of catching more severe strains of the deadly virus.
The team say that COVID-19 increases glucose metabolism through a phenomenon known as a 'cytokine storm' that leads to too many immune cells being produced.
Dr Shi Liu, of Wuhan University in China, said this spike in immune cells often happen in the lungs and increases the risk of a diabetic coronavirus patient dying.
People with diabetes have a higher risk of dying if they catch coronavirus - this is due to an overproduction of immune cells in the lungs, a new study finds
Cytokines are the activating compounds of immune cells and when a patient is exposed to flu or coronavirus there is a dramatic spike in cytokine numbers.
Glucose metabolism and inflammatory cytokine signal networks are known to have evolved together but it has not been clear whether they interact during flu infection.
The finding published in Science Advances is based on experiments in mice.
Lab rodents given glucosamine produced much higher levels of inflammatory cytokines than those that did not receive the sugar supplement.
Additionally, the researchers analysed glucose levels in blood samples from patients diagnosed with flu and compared it to samples from healthy people.
These were collected from volunteers during physical examinations at two Wuhan University hospitals between 2017 and 2019.
This identified a chemical pathway which metabolises glucose as playing an essential role in cytokine storms triggered by the flu virus.
'Glucose serves as a major nutrient that fuels cellular metabolic activities. Glucose metabolism and ]inflammatory cytokine signal network evolved together,' said Liu.
'Nevertheless, it remains unclear whether the two systems interact with each other during flu infection.
'In this study, we identified a previously undescribed mechanism of flu-regulated cytokine storm, in which flu induces cytokine storm by increasing glucose metabolism.'
Cytokines are small proteins released by many different cells in the body, including those of the immune system where they coordinate the body's response against infection and trigger inflammation.
Sometimes the body's response to infection can go into overdrive.
For example, when SARS -CoV-2 – the virus behind the pandemic – enters the lungs, it triggers an immune response.
This attracts immune cells to the region to attack the virus, resulting in localised inflammation.
But in some patients, excessive or uncontrolled levels of cytokines are released which then activate more immune cells, resulting in hyperinflammation.
This can seriously harm or even kill the patient and that is why people with diabetes have a much higher risk of dying from the virus.
Cytokine has been increasingly recognised as a risk to health through the way it triggers inflammatory responses but it must be coupled to specific metabolic programs to support their energetic demands.
Glucose metabolism and inflammatory cytokine signal networks are known to have evolved together but it has not been clear whether they interact during flu infection.
'Although more research is needed to understand the delicate regulatory mechanisms between flu-induced cytokine storm and glucose metabolism, our current findings may provide a potential target for the treatment of flu infection in the future,' said Liu.
Cytokine storms are a common complication not only of Covid-19 and flu but of other respiratory diseases caused by coronaviruses such as SARS and MERS.
They are also associated with non-infectious diseases such as multiple sclerosis and pancreatitis.
The phenomenon became more widely known after the 2005 outbreak of the avian H5N1 influenza virus, also known as 'bird flu', when the high fatality rate was linked to an out-of-control cytokine response.
Cytokine storms might explain why some people have a severe reaction to coronaviruses while others only experience mild symptoms.
They could also be the reason why younger people are less affected, as their immune systems are less developed and so produce lower levels of inflammation-driving cytokines.
In 2006, six healthy young men were left in intensive care with multiple organ failure as a result of an out-of-control cytokine immune response during a preclinical trial of a new kind of drug.
This reaction happened just 90 minutes after receiving a dose of the drug.
The research has been published in the journal Science Advances.
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