For the first time, researchers have shown that heart problems associated with the flu are not caused by raging inflammation in the lungs, as has long been predicted.
According to an Ohio State University study, electrical difficulties and heart scarring seen in some of the sickest flu patients are caused by direct influenza infection of cardiac cells.
In previous experiments, researchers discovered flu viral particles in cardiac cells of infected mice, but they couldn''t confirm for sure if their presence in the heart was causing cardiac damage. When researchers infected mice with a genetically altered flu virus that wasn''t capable to replicate in heart cells, they developed common inflammatory flu symptoms, but there were no cardiac complications.
Even if you have a very severe infection in the lungs, if you use that virus that can''t replicate in the heart, you do not have any cardiac complications, according to lead author Jacob Yount, an associate professor of microbial infection and immunity in the Ohio State College of Medicine.
This is why it is so prevalent in the heart that it is driving these difficulties. Now we need to understand what direct infection means: Is it killing heart cells? Does it have long-term implications? Do repeated infections have heart problems that develop over time? There are a lot of questions to answer.
The research is published today (May 11, 2022) in the journal Science Advances.
Over the years, it has been established that hospitalized flu patients may develop heart problems. A 2020 research has found that approximately 12% of people in the United States were hospitalized with the flu for eight years.
Yount has studied flu for years, and his lab developed a mouse model lacking IFITM3, the protein that codes for a key protein in viral infections'' innate immune systems. In a 2019 study, flu-infected mice lacking the IFITM3 gene were at a higher risk for developing cardiac problems.