Muscles support a strong immune system

Date:
June 15, 2020
Source:
German Cancer Research Center (Deutsches Krebsforschungszentrum,
DKFZ)
Summary:
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. Scientists have
now found initial evidence in mice that skeletal muscles help to
keep the immune system functional in chronic diseases.



FULL STORY ==========================================================================
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 defence system often becomes exhausted. Scientists at the
German Cancer Research Center (DKFZ) have now found initial evidence in
mice that skeletal muscles help to keep the immune system functional in
chronic diseases.


==========================================================================
In many cases, severe weight loss and a decrease in muscle mass are
the result 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, first indications suggest that there is a connection with
cachexia.

"It is known that T-cells are involved in the loss of skeletal muscle
mass. But whether and how, in turn, skeletal muscles influence the
function of the T- cells is still unclear," explains Guoliang Cui from
the DKFZ.

To find out, the scientists infected mice with lymphocytic
choriomeningitis virus (LCMV). This method is a widely used model
system to study the course of acute or chronic infections in mice. The researchers then analysed 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.

"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,"
said Jingxia Wu, lead author of the study. "This enables the immune
system to fight the virus continuously over a long period." So could
regular training strengthen the immune system? "In our study, 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," explains
Guoliang Cui.


========================================================================== Story Source: Materials provided by
German_Cancer_Research_Center_(Deutsches
Krebsforschungszentrum,_DKFZ). Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Jingxia Wu, Nina Weisshaar, Agnes Hotz-Wagenblatt, Alaa Madi,
Sicong Ma,
Alessa Mieg, Marvin Hering, Kerstin Mohr, Tilo Schlimbach, Helena
Borgers, Guoliang Cui. Skeletal muscle antagonizes antiviral CD8
T cell exhaustion. Science Advances, 2020; 6 (24): eaba3458 DOI:
10.1126/ sciadv.aba3458 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200615092747.htm

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