The discovery that B cells may be crucial mediators between the immune system and organs involved in movement is a major conceptual breakthrough.
Immune cells, which are normally tasked with fighting off invading pathogens, turn out to play a crucial supporting role for muscles during exercise. This is the conclusion of a new study on mice recently published in the journal Cell.
B cells have long been considered the "guardians" of the immune system, specializing in identifying harmful pathogens and actively producing antibodies to destroy them.
However, the role of these cells in the body's metabolism had never been observed before.
Immunologist Peng Jiang from Tsinghua University (Beijing, China), the author of the study, said this is the first time a function of these cells unrelated to the immune system has been described.
He called it "a discovery that completely exceeded our initial expectations."
Dr. Carolin Daniel, Director of the Helmholtz Institute for Metabolism and Immunology in Munich (Germany), shared that interest in the non-immune functions of B cells and T cells is growing.
She noted that the discovery of B cells as potentially playing a crucial role as mediators between the immune system and organs involved in movement is a major conceptual breakthrough.
To clarify this link, Jiang's team conducted endurance tests on a treadmill with two special groups of mice: one group genetically modified to have a low number of B cells, and another group treated with antibody therapy (a method commonly used in humans to kill cancerous B cells).
The researchers continuously increased the machine's speed at predetermined intervals of about 15 minutes, and only stopped when the mice were exhausted.
The results showed that mice with fewer B cells in both experimental groups performed significantly worse on endurance and strength tests compared to the control group of mice with normal B cell levels.
Delving into the biological mechanisms, researchers discovered that mice deficient in B cells had lower levels of the amino acid glutamate in their muscles after exercise.
High levels of glutamate help mitochondria function more efficiently and improve musculoskeletal function. The key lies in the fact that B cells are able to produce a protein called TGF-β1, which stimulates the liver to produce more glutamate.
In the absence of this process, the amount of glutamate available in muscle tissue and blood decreases, leading to a decline in athletic performance as the authors observed.
However, expert Carolin Daniel also noted that the study's conclusions may be oversimplifying the role of B cells in the multifaceted processes that determine physical performance.
She argued that attributing the decline in mobility to such a narrow pathway was interesting, but could also inadvertently overlook the role of the body's broader endocrine network.
She hopes that similar studies will soon be conducted on the human body to provide a more comprehensive and accurate picture.