Muscle weakness and impaired work capacity are commonly observed symptoms in patients with rheumatic diseases. The degree of muscle impairment appears to depend on the severity of the disease and more than 50% reduction in muscle strength has been reported in patients with severe rheumatoid arthritis (RA). The decreased muscle strength is not only caused by a loss of muscle mass, but also by defective function within the skeletal muscle fibers. In fact, severe muscle weakness may occur even with a limited decrease in muscle mass. We have studied mechanisms underlying the defective muscle function in mice with collagen-induced arthritis (CIA), a mouse model that displays many pathological characteristics of human RA. Muscle fibers of CIA mice display impaired function of the contractile proteins as well as altered cellular calcium handling. These changes are accompanied by increased production reactive oxygen and nitrogen species, which results in major redox-induced protein modifications.

Disclosure of Interest None Declared