What role does interleukin-3 play in COVID-19?
Some people get so seriously ill with COVID-19 that they have to be hospitalized or even die of the disease. A newly identified biomarker can seemingly be used to predict the severe disease progression of COVID-19 and may even lead to new treatments in the future.
The immune messenger substance interleukin-3 seems to be able to predict whether COVID-19 will take a mild or severe course in affected people, according to the result of an investigation with the participation of researchers from the surgical clinic of the German University Hospital Erlangen. The results of the study were published in the English-language journal “Nature Communications”.
Why do some people get so seriously ill with COVID-19?
It is still unclear why such drastic differences in the severity of COVID-19 are observed in different people. It is already known that older people have an increased risk of a more severe course of COVID-19. In addition, smoking, overweight and obesity are also associated with an increased risk of serious illness. When it comes to the question of which mechanisms are responsible for a severe course of COVID-19, much remains unclear.
Leading indicator could predict the course of disease
It is noticeable that people who actually do not belong to any of the known risk groups are also seriously ill with COVID-19. Now it’s the research team, including experts Dr. Georg Weber and Dr. Alan Bénardaus from the surgical clinic at the University Hospital Erlangen, succeeded in identifying a leading indicator that could help predict the course of severe disease.
Low IL-3 plasma levels increase disease severity
IL-3 is an independent prognostic marker for the outcome of a SARS-CoV-2 infection. “In particular, a low IL-3 plasma level is associated with an increased severity, an increased viral load and an increased mortality rate during a SARS-CoV-2 infection,” report the experts.
IL-3 stimulates production of CXCL12
This indicates that interleukin-3 plays an important role in organizing the body’s immune response, the researchers explain. In the event of inflammation in the affected area, it stimulates the cells to produce the protein CXCL12.
IL-3 reduced viral load and mortality
In a model of pulmonary HSV-1 infection in mice, treatment with recombinant IL-3 reduced both viral load and mortality, the research team reports. By promoting the recruitment of plasmacytoid dendritic cells into the airways, IL-3 increases innate antiviral immunity. To do this, IL-3 stimulates the CXCL12 secretion of pulmonary CD123 + epithelial cells, both in mice and in people with lung diseases who do not suffer from COVID-19, the researchers explain.
Overall, IL-3 is a good predictive disease marker for SARS-CoV-2 infections and IL-3 could also be a potential therapeutic target for pulmonary virus infections.
IL-3 improves the immune system
Interleukin-3 is able to massively increase the body’s immune defense. To do this, the protein causes the so-called plasmacytoid dendritic cells, which normally circulate in the bloodstream, to migrate to the affected area, where they restrict the pathogens from multiplying, the researchers report.
The influence of interleukin-3 could explain why younger people and people without certain previous illnesses sometimes get seriously ill with COVID-19. It is possible that people who normally cannot be assigned to any of the risk groups have very little interleukin-3 in their blood. If such people are surprisingly seriously ill with COVID-19, this increases the risk that those affected will receive appropriate medical treatment too late, the team explains.
New immunotherapy in prospect
In the future, the new findings could help ensure that important steps for effective treatment are taken at an early stage, especially in people with only a small amount of interleukin-3 in their blood. According to the experts, it might even be possible to develop an immunotherapy with the help of interleukin-3, in which the lungs are protected from infection by viruses by inhalation, the experts add. (as)
Author and source information
This text complies with the requirements of specialist medical literature, medical guidelines and current studies and has been checked by medical professionals.
- Anne Jacobsen, Maximilian Brunner, Christian Krautz, Bettina Klösch, Izabela Swierzy et al.: Interleukin-3 is a predictive marker for severity and outcome during SARS-CoV-2 infections, in Nature Communications (veröffentlicht 18.02.2021), Nature Communications
This article is for general guidance only and should not be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor.
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