After a cold, many people don't pay much attention to it. They have a runny nose and a cough? Only when you have a fever or more serious can you go to the hospital for medicine and injection. However, a new study in science progress suggests that if it is not the common cold, but the cold symptoms caused by the influenza virus, the consequences are likely to be serious and even cause direct damage to the heart.
Some previous studies have speculated that the heart problems associated with influenza may be caused by lung inflammation, but the Ohio State University research team confirmed through mice that the serious symptoms such as cardiac electrical signal disorder and myocardial damage seen in influenza patients are caused by infected heart cells.
In fact, the probability of heart problems in influenza patients is not low. According to a report released by the CDC of the United States last year, one in eight patients hospitalized for influenza may have heart problems.
Some past studies by Professor Jacob Yount of Ohio State University have actually suggested this possibility. He and his colleagues have found influenza virus particles in the heart cells of mice infected with influenza.
In the new research, they further promoted the progress of relevant research. Based on their past experience in gene analysis, they constructed a group of mice lacking the key immune gene IFITM3, which can encode a protein in the innate immune system and effectively fight viral infection.
Mice lacking IFITM3 expression were more prone to heart problems after influenza infection. They are not only highly susceptible to influenza viruses, but also lack some anti viral proteins. The proportion of lacking IFITM3 expression in different populations is about 4% - 20%, which means that many people themselves will be more vulnerable to virus infection.
Subsequently, the H1N1 influenza virus was modified, and these mutant influenza viruses could not replicate in heart cells. They injected control and modified viruses into normal mice and IFITM3 deficient mice, respectively.
After a period of time, both viruses can cause severe lung and systemic inflammation in mice, and a large number of viruses can be detected in their bodies. However, ordinary mice injected with defective influenza virus basically have no virus particles in their heart cells, and IFITM3 deficient mice with weak resistance have only low concentration of defective virus particles in their hearts.
These mice infected with the defective virus had less myocardial damage, less fibrosis and scarring in the heart tissue, and no abnormal electrical signal problems. Professor Yount explained: "with the help of these defective viruses and mice, we can distinguish pneumonia caused by influenza from heart problems. If there is no active replication virus in the heart, it will not cause heart damage."
Studies have shown that influenza viruses tend to concentrate in the lungs rather than in the blood or other organs, but they can accidentally attack the heart. This shows that it is necessary to reduce the number of viruses in time after a cold to prevent the occurrence of heart problems.
Of course, the research team still has some problems to solve in the future. Will these influenza viruses entering the heart kill cells? Will it have a long-term impact on cardiac function? If so, the impact of a cold may be more serious than expected, which is worthy of our vigilance!
reference material:
[1] Flu causes cardiac complications by directly infecting the heart。 Rerieved May 12th， 2022 from https：//medicalxpress.com/news/2022-05-flu-cardiac-complications-infecting-heart.html
[2] Adam D。 Kenney et al， Influenza virus replication in cardiomyocytes drives heart dysfunction and fibrosis， Science Advances （2022）。 DOI： 10.1126/sciadv.abm5371。