Researchers have just discovered a process that links inflammation and motor dysfunction in fruit flies, providing researchers with a potential target for treating the persistent muscle fatigue that accompanies many infections.
Long COVID Many symptomsIntolerance to exercise is More debilitating.
“This isn’t just a matter of not wanting to move because you’re feeling unwell.” To tell “These processes reduce energy levels in skeletal muscles, reducing their ability to move and function normally,” says Aaron Johnson, a developmental biologist at the University of Washington.
The more new infections there are, SARS-CoV-2 virusour Risk of experiencing long COVID-19 Increases. Almost 18 million American adults I am facing this now Prolonged fatigue And that Physical symptoms accompanied by fatigue.
many These symptoms teeth Familiarcontains Frustrating loss of energy This is a symptom seen in about half of long COVID patients. Muscle fatigue is also seen in other post-viral symptoms and in people with neurodegenerative diseases. Alzheimer’s disease and Parkinson’s disease.
What these conditions have in common is inflammation of the central nervous system. Brain injury It has also been identified in COVID patients.
So developmental biologist Shuo Yang of the University of Washington and his colleagues used animal models to explore how inflamed neurons cause muscle dysfunction. In both flies and mice, they identified a signaling pathway between brain cells and muscles that leads to loss of muscle function.
“Flies and mice with COVID-related proteins in their brains had impaired motor function. The flies could not climb as well as they should, and the mice could not run as well as control mice.” explain Johnson.
“We saw a similar effect on muscle function when the brain was exposed to bacteria-associated proteins and the Alzheimer’s protein amyloid-beta, and we also saw evidence that this effect can be chronic: even if the infection is quickly cleared, the decline in muscle performance in our experiments persisted for several days.”
In humans, inflammation triggers neurons to release immunity Cytokines Interleukin-6 (IL-6The team found a similar protein that travels through the bloodstream to the muscles of lab animals and activates cellular programs. JAK-STATJAK-STAT then reduced the amount of energy produced by muscle tissue. Mitochondria Power plant.
“It’s unclear why the brain produces protein signals that are so detrimental to muscle function across a range of disease categories.” To tell Johnson.
“If we want to speculate as to why this process has persisted in us throughout human evolution, despite the damage it causes, it could be that it is the brain’s way of reallocating resources to itself when fighting disease. Further research is needed to better understand this process and its effects on the whole body.”
Yan and team They then used a drug that blocks this pathway in flies and found they could reverse the process, as shown in previous mouse studies. IL-6 inhibitors are already being used effectively to treat autoimmune diseases such as rheumatoid arthritis. Showed promise Some serious COVID-19 Previous cases.
“The brain-muscle axis appears likely to be activated by respiratory infections via the cerebrospinal fluid. [cerebrospinal fluid]”…and continue to send signals long after the initial infection has cleared up,” the researchers say. Write in a paper“Thus, long COVID may be caused by chronic cytokine signaling.”
The researchers caution that some parts of the puzzle, such as how SARS-CoV-2 enters the human central nervous system and causes this inflammation, are still unknown, but this new information could lead to much-needed relief for people suffering from a variety of chronic diseases.
By altering the chemicals secreted by neurons, the study sheds light on how brain inflammation caused by a variety of conditions can have such profound physical effects on the entire body.
This study Science Immunology.
