Muscle fiber dysfunction contributes to weakness in inclusion body myositis

Saskia Lassche, Anke Rietveld, Arend Heerschap, Hieronymus W. van Hees, Maria TE Hopman, Nicol C. Voermans, Christiaan GJ Saris, Baziel GM van Engelen, Coen AC Ottenheijm

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Atrophy and fatty infiltration are important causes of muscle weakness in inclusion body myositis (IBM). Muscle weakness can also be caused by reduced specific force; i.e. the amount of force generated per unit of residual muscle tissue. This study investigates in vivo specific force of the quadriceps and ex vivo specific force of single muscle fibers in patients with IBM. We included 8 participants with IBM and 12 healthy controls, who all underwent quantitative muscle testing, quantitative MRI of the quadriceps and paired muscle biopsies of the quadriceps and tibialis anterior. Single muscle fibers were isolated to measure muscle fiber specific force and contractile properties. Both in vivo quadriceps specific force and ex vivo muscle fiber specific force were reduced. Muscle fiber dysfunction was accompanied by reduced active stiffness, which reflects a decrease in the number of attached actin-myosin cross-bridges during activation. Myosin concentration was reduced in IBM fibers. Because reduced specific force contributes to muscle weakness in patients with IBM, therapeutic strategies that augment muscle fiber strength may provide benefit to patients with IBM.

Original languageEnglish (US)
Pages (from-to)468-476
Number of pages9
JournalNeuromuscular Disorders
Volume29
Issue number6
DOIs
StatePublished - Jun 2019
Externally publishedYes

Keywords

  • Inclusion body myositis
  • MRI
  • Muscle weakness

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Neurology
  • Clinical Neurology
  • Genetics(clinical)

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