How can we limit age-related decrease in muscle capacity
(sarcopenia), which is a major cause of loss of autonomy in the elderly?
Researchers from Inserm, Université Toulouse III – Paul Sabatier and
the Gérontopôle of Toulouse University Hospital might have found,
within the muscles themselves, a formidable ally in fighting this
disease: apelin. This hormone, whose production decreases with age,
is secreted during physical activity and improves muscle capacity. This
research published in Nature Medicine makes it possible to envisage
apelin both as a diagnostic tool for sarcopenia and as a solution for its
treatment.
In 2016, WHO finally recognized the decrease in muscle capacity –also
known as sarcopenia or muscle loss with aging– as a disease. Indeed,
maintaining functional capacity in the elderly is essential to preserve their
independence and quality of life. Associated with limited mobility, sarcopenia
appears to be a primary cause of the progressive loss of autonomy and the
development of age-related pathologies (osteoporosis, cardiac and/or
cognitive impairment) and as a consequence one of the main reasons for
medical institutionalization.
Sarcopenia is the degenerative loss of skeletal muscle mass, quality and
strength. Current treatment strategies produce varying levels of efficacy,
often associated with side effects. There is also a lack of early diagnosis
tools. Physical activity –while presenting the major disadvantage of often
being impractical or fruitless in individuals with reduced motor capacity– is
often considered to be the most effective approach. In previous studies it
was shown that by stimulating activation of the stem cells at the origin of
muscle cells, the muscle contraction generated by physical activity helped
renew the muscle fibers (myofibers) and improve their metabolism.
The Inserm research team from the Institute of Cardiovascular and Metabolic
Diseases, I2MC (U1048 Inserm/Université Toulouse III – Paul Sabatier) in
collaboration with teams from the Gérontopôle of Toulouse University
Hospital looked at the relationship between these mechanisms and the
development of sarcopenia. They identified a hormone, apelin, produced by
the contraction of the muscle during physical activity, and which appears to
be capable of maintaining and even restoring muscle capacity.
Indeed, when apelin was administered to elderly mice, the researchers saw
their muscle capacity improve and their myofibers return to normal. This
improvement is thought to be due to the ability of apelin to stimulate both
the cellular metabolism in the muscle and the regeneration of myofibers from
stem cells.
Finally, the researchers observed that the production of apelin in
response to physical activity diminishes with age. According to Philippe
Valet, co-director of the study and professor at Université Toulouse III –
Paul Sabatier “in the years to come, apelin could be used for therapeutic
purposes in sarcopenia because the results of the study in mice show
that treatment with this hormone significantly improves muscle faculties.
With this research we can envisage apelin both as a tool for the early
diagnosis of sarcopenia and as a promising treatment in the fight against
age-related loss of function.”
Clinical trials will be conducted from 2019 by the Gérontopôle of Toulouse
University Hospital as part of the IHU-Inspire project which focuses on
prevention, aging in good health and regenerative medicine.