What happens to the immune system when a person is obese? Understanding those changes are helping Professor Lydia Lynch to figure out why people with obesity are at greater risk of some cancers, and possibly of severe illness in COVID-19.

“Studies of COVID-19 patients in New York City and in Wuhan in China have found that older age was one risk factor for having severe disease, and being obese was another,” explains Professor Lynch, who carries out research in Trinity College Dublin and Harvard University in Boston.

“I think the immune system could be a common factor in the increased risks of severe disease in ageing and obesity.”

Professor Lynch’s past research, funded by SFI, has shown that immune cells from obese people are less effective at killing viruses and cancer cells. “When we take blood samples from people with obesity, we can see that the immune cells that normally protect us from viruses and cancer are exhausted in people with obesity,” she explains.

Her research group also recently found that in cancer, tumours from people who are obese have fewer immune cells, and this is linked to worse outcome from the cancer.

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So where does COVID-19 come in? “From our research we can see that obesity exhausts or ages the immune system, and we know that older people also have a reduced immune system,” says Professor Lynch. “There are immune differences between men and women too, and we know that men have a higher risk of severe disease in COVID-19.”

Professor Lynch is now starting to analyse samples from patients in Ireland with COVID-19, to look at their immune profiles and see if there are relationships with age, obesity and gender, with a view to tailoring treatment: “We want to figure out what is happening with the immune response in different groups of patients, because there may be treatments that can specifically help them to fight off this virus.”