In a new study, researchers have found new evidence that skeletal muscles may help to keep the immune system functions in chronic diseases.
The research was conducted by scientists at the German Cancer Research Center (DKFZ).
In the fight against cancer or chronic infections, the immune system must be active over long periods of time. However, in the long run, the immune defense system often becomes exhausted.
In many cases, severe weight loss and a decrease in muscle mass are the results of cancer or dangerous infections.
In addition to this process known as cachexia, patients often suffer from a weakened immune system.
One of the reasons for this is a loss of function of a group of T-cells, whose task it is to recognize and kill virus-infected cells or cancer cells.
The processes leading to loss of T-cell activity are still largely unexplained. However, the first indications suggest that there is a connection with cachexia.
To find out, the scientists infected mice with lymphocytic choriomeningitis virus (LCMV).
They then analyzed the gene expression in the skeletal muscles of the animals and found that in chronic infections, the muscle cells release an increased amount of the messenger substance interleukin-15.
This cytokine causes T-cell precursors to settle in the skeletal muscles. As a result, they are spatially delimited and protected from contact with the chronic inflammation.
The team says if the T-cells, which actively fight the infection, lose their full functionality through continuous stimulation, the precursor cells can migrate from the muscles and develop into functional T-cells.
This enables the immune system to fight the virus continuously over a long period.
So could regular training strengthen the immune system?
The team says mice with more muscle mass were better able to cope with chronic viral infection than those whose muscles were weaker.
But whether the results can be transferred to humans, future experiments will have to show.
One author of the study is Guoliang Cui from the DKFZ.
The study is published in Science Advances.
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