Inclusion body myositis: from immunopathology and degenerative mechanisms to treatment perspectives.

Inclusion body myositis is the most common inflammatory myopathy above the age of 50. It becomes clinically apparent around the fourth decade and leads to a slowly, but relentlessly progressive decline in muscular wasting and weakness. The pathology consists of a complex network of inflammatory and degenerative mechanisms, which lead to an attack of muscle fibers by auto-reactive T cells and possibly antibodies. At the same time, various aberrant proteins accumulate within the muscle fibers, including β-amyloid, tau and α-synuclein. Several key components of proinflammatory cell stress mechanisms such as nitric oxide production and macroautophagic processing contribute to the muscle fiber damage. So far, none of the anti-inflammatory or immunomodulatory treatment efforts have been able to halt the disease progression and help the patients. In this summary, the current concept of the complex disease pathology of IBM is reviewed with a focus on recent findings as well as future treatment perspectives.