Mystery Unfolded Between Heart Problems and Inflammatory Flu: Soon to Humans

The research team looked at the virus particles in the heart cells of mice that had been affected in previous work, but could not confirm whether their presence in the heart affected it or not. When researchers infected mice with a genetically modified inflammatory flu virus that could not replicate in heart cells, the mice developed classic inflammatory flu symptoms – but no heart problems.


“We showed that even when you have a very serious lung infection, if you use the virus that can not replicate in the heart, you do not get those heart complications,” says lead author Jacob Yount, associate professor. at Ohio State’s College of Medicine.

“It proves that it is direct infection in the heart that drives these complications. Now we have to find out what direct infection does: Does it kill heart cells? Does it have long-term consequences? Do repeated infections have heart complications that build up over time? There are many questions now for us to answer. “

It has been established for some time that fever patients who are hospitalized can develop heart problems. In a study from 2020, 12% of the adults who were hospitalized with the flu in the United States for eight years had developed sudden, serious heart problems.

Yount has been studying the inflammatory flu for many years, and his lab has developed a mouse model that does not contain IFITM3, a gene that represents an important protein for eliminating viral infections in the endocrine system. A 2019 study by his team found that mice infected with the mutated IFIDM3 gene were at higher risk of developing heart problems.

These mice are not only susceptible to the inflammatory flu, but also have a deficiency of the same antiviral protein that some people do not have: about 20% of the Chinese population and 4% of Europeans have a genetic variant that causes IFITM3 deficiency.

“We know these people are more susceptible to serious flu infections, and our mouse research would suggest that they are also more susceptible to flu complications with the flu,” said Yount, also a program director for the Virus and Emerging Pathogens Program at the Ohio State Infectious Diseases Institute.

Implementation change study

For this study, the researchers had mutated the gene from the H1N1 flu strain so that the virus could not pass on to the heart cells to copy itself. They injected the mutated virus and the control virus into normal mice and mice without IFITM3.

Both viruses caused pneumonia (pneumonia) and systemic inflammation and produced high concentrations of virus particles in mice, but the mutated virus was not detected in normal mouse heart cells and was found in significantly lower concentrations in IFITM3-deficient mouse hearts. These findings enabled direct comparisons between the hearts of mice with and without strong viral replication.

The researchers found less heart muscle damage, fewer biomarks for cell damage, less scarring of heart tissue or fibrosis and electrical signal problems in the hearts of mice infected with the genetically modified virus.

“We have this mouse model and this virus that allowed us to distinguish between the severe pneumonia and the direct replication of the virus in the heart. We could not have distinguished the two things before,” Yount said. “If you do not have the virus that replicates strongly in the heart, you will not see the same electrical abnormalities or the same fibrotic response.”

There is still much more to learn. Influenza focuses most of its efforts on infiltrating the lungs, but usually in the bloodstream or other organs. But it goes to the heart – and finding out how this is done is part of the ongoing work in Yount’s lab.

It is too early to say how this research will have an impact on the treatment of hospitalized influenza patients with heart problems, but these findings suggest that elimination of the viral infection is important to minimize the complications of febrile complications in the heart.

“One thing this tells us is that this is another reason to get your flu shot, because you do not want your heart to be infected with the flu – and it’s a possibility,” he said.

Source: Medindia

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