Osteopontin is highly expressed in severely dystrophic muscle and seems to play a role in muscle regeneration and fibrosis

Simona Zanotti, Sara Gibertini, Claudia di Blasi, Cristina Cappelletti, Pia Bernasconi, Renato Mantegazza, Lucia Morandi, Marina Mora

Research output: Contribution to journalArticlepeer-review

Abstract

Aims: To increase our understanding of profibrotic mechanisms in dystrophic muscle. Methods and results: Extracellular matrix, fibrosis-related molecules and histopathology were assessed in skeletal muscle of patients with Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and congenital muscular dystrophy type 1A (MDC1A).Osteopontin expression was much higher in DMD and MDC1A than in BMD and control muscle. Osteopontin was expressed in mononuclear cell infiltrates, on some muscle fibre surfaces, in regenerating fibres, and in calcified fibres. In all pathological muscles, matrix metalloproteinase (MMP)-1 was increased around groups of fibres that were also characterized by absence of collagen 1. The amounts of MMP-2, MMP-9 and tissue inhibitor of MMP -1 transcripts were also increased, whereas their proteins were variably expressed in muscle fibres (surface or cytoplasm) and at foci of necrosis and regeneration. Inflammatory cells, fibroblasts and myofibroblasts were more numerous in DMD and MDC1A than in BMD muscle. Conclusions: Several fibrosis-related factors are greatly altered in severely dystrophic skeletal muscle. Osteopontin was the most conspicuously upregulated, both as transcript and as protein, in muscle fibres and infiltrating cells, indicating an intimate involvement in fibrosis, and also in inflammation and muscle regeneration, although its precise roles in these processes remain to be elucidated.

Original languageEnglish
Pages (from-to)1215-1228
Number of pages14
JournalHistopathology
Volume59
Issue number6
DOIs
Publication statusPublished - Dec 2011

Keywords

  • Collagen
  • Extracellular matrix
  • Muscle fibrosis
  • Muscular dystrophy osteopontin

ASJC Scopus subject areas

  • Histology
  • Pathology and Forensic Medicine

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