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Exercise induces interleukin-8 expression in human skeletal muscle.
Thorbjorn Akerstrom1, Adam Steensberg, Pernille Keller
1The Copenhagen Muscle Research Centre, Rigshospitalet, Faculty of Health, University of Copenhagen, Denmark .
The Journal of Physiology
|December 25, 2004
Summary
Working muscles produce Interleukin-8 (IL-8), a protein that aids blood vessel growth. This study found IL-8 is expressed in muscle fibers after exercise, suggesting a local role in healing and repair.
Area of Science:
- Exercise physiology
- Immunology
- Endocrinology
Background:
- Skeletal muscle functions as an endocrine organ, producing cytokines with hormonal effects.
- Interleukin-8 (IL-8), a pro-angiogenic chemokine, is present in exercising muscles, but its cellular origin is unknown.
Purpose of the Study:
- To determine if IL-8 protein is expressed in contracting muscle fibers.
- To investigate the release of IL-8 from exercising muscle.
Main Methods:
- Seventeen healthy males underwent 3-hour ergometer bicycle or knee-extensor exercise protocols.
- Muscle biopsy samples were collected from the vastus lateralis during exercise and recovery.
- IL-8 mRNA and protein expression were analyzed.
Main Results:
- Exercise induced a significant increase in IL-8 mRNA in muscle tissue.
- IL-8 protein was detected in muscle fibers during the recovery phase post-exercise, peaking 3-6 hours later.
- A small, transient release of IL-8 from exercising muscle was observed, but systemic plasma levels did not increase.
Conclusions:
- Contracting skeletal muscle fibers express IL-8 protein, particularly after prolonged exercise.
- Muscle-derived IL-8 appears to act locally, potentially in angiogenesis, rather than affecting systemic circulation.