Inclusion Body Myositis

Continuum (Minneap Minn). 2016 Dec;22(6, Muscle and Neuromuscular Junction Disorders):1871-1888. doi: 10.1212/01.CON.0000511071.58338.1e.

Abstract

Purpose of review: Inclusion body myositis (IBM) is an enigmatic progressive disease of skeletal muscle. This review provides a summary of the clinical and pathophysiologic aspects of IBM.

Recent findings: The development of diagnostic blood testing for IBM followed from the discovery of a B-cell pathway in IBM muscle and circulating autoantibodies against NT5C1A, further establishing IBM's status as an autoimmune disease. The key role of cytotoxic T cells in IBM is further supported by the identification of a link between IBM and T-cell large granular lymphocytic leukemia. The testing of research diagnostic criteria in patients is improving its accuracy. Increases in estimated prevalences may be due to a combination of true increases and improved recognition of disease.

Summary: IBM has high unmet medical need. Advances in the mechanistic understanding of IBM as an autoimmune disease will drive effective therapeutic approaches. The identification of a B-cell pathway has resulted in the first identification of an IBM autoantigen and emphasized its status as an autoimmune disease. The recognition that large granular lymphocyte CD8+ T-cell expansions are present in both blood and muscle provides additional biomarkers for IBM and suggests a mechanistic relationship to the neoplastic disease T-cell large granular lymphocytic leukemia.

Publication types

  • Case Reports
  • Review

MeSH terms

  • Aged
  • Clinical Trials as Topic / methods
  • Electromyography / methods
  • Humans
  • Male
  • Myositis, Inclusion Body / immunology
  • Myositis, Inclusion Body / pathology*
  • Myositis, Inclusion Body / therapy*