Laboratory-grown human muscles show that exercise can prevent ‘almost completely’ chronic inflammation that causes tissue to fall off
- Inflammation stems from the overreaction of the body’s immune system
- Chronic inflammation can waste muscle tissue and lose its structure
- Experts believe that a molecule called ‘interferon gamma’ is behind this waste
- Yet it was unclear how it worked and why exercise seemed to soften it
- To simplify research, American researchers grew their own muscles in the laboratory
- This enabled them to zero in on the cells to focus on the relevant processes
Exercise can ‘almost completely’ prevent chronic inflammation from causing muscle to fall away, a laboratory-grown human tissue study has revealed.
Inflammation occurs when our body’s immune system reacts to bacteria or tissue damage – but it can sometimes overreact and eventually attack its own cells.
And some diseases – such as arthritis and sarcopenia – can lead to long-term ‘chronic inflammation’ that causes muscle wasting.
It is believed that a molecule known as ‘interferon gamma’ is one of the culprits behind various types of muscle wasting and dysfunction.
Previous studies have shown that exercise can alleviate the effects of inflammation in general, but it is unclear what role muscle cells and interferon gamma play.
To find out, researchers from Duke University in the USA developed a platform to grow their own human muscles in the laboratory.
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Exercise can ‘almost completely’ prevent chronic inflammation from causing muscle to fall away, a laboratory-grown human tissue study has revealed. In the photo: long, thin, well-defined muscle fibers (top left) lose their structure after prolonged inflammation (top right), but not when they also undergo exercise (bottom left). The same goes for strength (bottom right)
“A lot of processes take place through the human body during exercise, and it’s hard to tell which systems and cells are doing within an active person,” said paper writer and biological engineer Nenad Bursac.
“Our designed muscle platform is modular, which means we can mix and match different types of cells and tissue components as we wish.”
“But in this case, we discovered that the muscle cells are capable of doing anti-inflammatory actions on their own.”
For their studies, the researchers began by growing functional human skeletal muscle in a Petri dish – after which they added immune cells and reservoirs of stem cells.
When the muscles were mature, the team ‘flooded’ them with a high level of interferon gamma for seven days to mimic the effects of a prolonged chronic inflammation.
As expected, the muscles in the laboratory became smaller and lost much of their strength.
Thereafter, they repeated the experiment, but this time using the muscles through a simulated exercise regimen using electric shocks.
The researchers found that the regimen ‘almost completely’ prevents the effects of chronic inflammation by blocking a specific molecular pathway.
“We know that chronic inflammatory diseases cause muscle atrophy, but we wanted to see if the same thing would happen to our designed human muscles that grew in a Petri dish,” said author and biomedical engineer Zhaowei Chen.
“We did not just confirm that interferon gamma works primarily through a specific signaling pathway,” he continued.
“We have shown that exercising muscle cells can directly counteract this pro-inflammatory signal, independent of the presence of other types or tissues.”
Exercise had the same anti-inflammatory effect as tofacitinib and baricitinib, two drugs commonly used to treat arthritis, the researchers found.
“During exercise, the muscle cells themselves were directly against the inflammatory signal induced by interferon gamma, which we would not expect,” said Professor Bursac.
‘These results show how valuable human muscles can be in the laboratory to discover new mechanisms of disease and possible treatments.
“There are ideas out there that optimal levels and workouts can fight chronic inflammation while not stressing the cells too much.”
“Maybe we can help with our designed muscles to find out if such beliefs are true.”
The full findings of the study were published in the journal Science Advances.