Introduction: Collagen cross-linking is a key parameter in extracellular matrix (ECM) maturation, turnover, and stiffness. We examined aspects of collagen cross-linking in dystrophin-deficient murine, canine, and human skeletal muscle.
Methods: DMD patient biopsies and samples from mdx mice and golden retriever muscular dystrophy dog samples (with appropriate controls) were analyzed. Collagen cross-linking was evaluated using solubility and hydroxyproline assays. Expression of the cross-linking enzyme lysyl oxidase (LOX) was determined by real-time polymerase chain reaction, immunoblotting, and immunofluorescence.
Results: LOX protein levels are increased in dystrophic muscle from all species evaluated. Dystrophic mice and dogs had significantly higher cross-linked collagen than controls, especially in the diaphragm. Distribution of intramuscular LOX was heterogeneous in all samples, but it increased in frequency and intensity in dystrophic muscle.
Conclusion: These findings implicate elevated collagen cross-linking as an important component of the disrupted ECM in dystrophic muscles, and heightened cross-linking is evident in mouse, dog, and man. Muscle Nerve 54: 71-78, 2016.
Keywords: collagen cross-linking; extracellular matrix; fibrosis; lysyl oxidase; muscular dystrophy.
© 2015 The Authors. Muscle & Nerve Published by Wiley Periodicals, Inc.