Sunday, December 5

Covid can infect cells in the pancreas that produce insulin, research shows | Diabetes

Covid-19 can infect insulin-producing cells in the pancreas and change their function, which could explain why some previously healthy people develop diabetes after contracting the virus.

Doctors are increasingly concerned about the growing number of patients who have developed diabetes while infected with the coronavirus or shortly after recovering.

Various theories have been proposed to explain this increase. One is that the virus infects pancreatic cells through the same ACE2 receptor found on the surface of lung cells and interferes with their ability to produce insulin, a hormone that helps the body regulate blood glucose levels; alternatively, an exuberant antibody response to the virus could accidentally damage pancreatic cells, or inflammation in other parts of the body can make tissues less responsive to insulin.

To investigate, Professor Shuibing Chen of Weill Cornell Medicine in New York examined various cells and organoids (groups of lab-grown cells that mimic the function of organs) to identify which ones might be infected by Covid. The results suggested that organoids in the lung, colon, heart, liver, and pancreas could be infected, as could dopamine-producing brain cells.

Other experiments revealed that the insulin-producing beta cells within the pancreas were also susceptible, and that once infected, these cells produced less insulin, as well as hormones generally made by different pancreatic cells.

“We call it transdifferentiation,” said Chen, who presented the results at the annual meeting of the European Association for the Study of Diabetes on Wednesday. “They are basically changing their cell fate, so instead of being beta cells that secrete a lot of insulin, they start mixing different hormones. It could provide more information on the pathological mechanisms of Covid-19. “

Scientists have observed a similar phenomenon in some people with type 2 diabetes, although the disease is more strongly associated with tissues in the body that are less responsive to insulin.

It is not yet clear whether the changes brought about by the Covid infection are lasting. “However, we know that some patients who had very unstable blood glucose levels when they were in the intensive care unit and recovered from Covid-19, some of them also recovered. [glucose control], which suggests that not all patients will be permanent, ”said Chen.

Separate research by Professor Francesco Dotta of the University of Siena in Italy and his colleagues confirmed that Covid attacks pancreatic cells by targeting the angiotensin converting enzyme 2 (ACE2) protein on their surface, and that beta cells Insulin producers express particularly high levels of it. protein.

They also showed that ACE2 levels increased in inflammatory conditions, which is important because people with existing type 2 diabetes may already have some inflammation in the pancreas. “This means that these insulin-producing beta cells could be even more susceptible to viral infection when they become inflamed,” Dotta said.

This could imply that people with existing diabetes or prediabetes are at a higher risk of pancreatic dysfunction if they contract Covid-19, something he now plans to investigate. “Diabetic patients in general are not more susceptible to Covid-19 infection in terms of frequency, but once they become infected, they develop more serious complications and severe metabolic disorders,” Dotta said.

Professor Francesco Rubino, chair of metabolic surgery at King’s College London, said: “These studies appear to be consistent in supporting a biological rationale for the idea that Covid-19 could increase the risk of developing diabetes in people who are predisposed to it. , or even potentially completely from scratch. ”

He is co-leading an international effort to establish a global database of Covid-19-related diabetes cases, to better understand whether the infection can cause a new form of diabetes or trigger a stress response that leads to type 1 or type 2 diabetes.

“Whether such changes are sufficient to allow this virus to cause diabetes is a question that these studies do not answer, but it gives us another reason to believe that this is a possibility,” he said.

However, this may not be the only way the virus increases the risk of diabetes. “Clinically at least, one of the things we are seeing is that, in some cases, patients who already had type 1 diabetes have started to express severe insulin resistance, which is a typical feature of type 2 diabetes.” Rubino said. This may involve a problem with the way cells in other parts of the body respond to insulin after Covid-19 infection.

Dr Lucy Chambers, Head of Research Communications at Diabetes UK, said: “People with diabetes have been disproportionately affected by Covid-19, and many people with the condition have tragically died as a result. Diabetes is a well-established risk factor for serious illness from Covid-19, and there is emerging evidence that Covid-19 can trigger new cases of diabetes, but how these two conditions are biologically linked is still not well understood.

“This research deepens our understanding of how diabetes and Covid 19 can interact biologically. This will help in the development of new and effective ways to treat people at risk of (or living with) diabetes who have Covid-19. Covid-19 vaccination, including a booster when offered, remains the best form of protection against the virus. “

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