Genetic reduction of the extracellular matrix protein versican attenuates inflammatory cell infiltration and improves contractile function in dystrophic mdx diaphragm muscles

Abstract

There is a persistent, aberrant accumulation of V0/V1 versican in skeletal muscles from patients with Duchenne muscular dystrophy and in diaphragm muscles from mdx mice. Versican is a provisional matrix protein implicated in fibrosis and inflammation in various disease states, yet its role in the pathogenesis of muscular dystrophy is not known. Here, female mdx and male hdf mice (haploinsufficient for the versican allele) were bred. In the resulting F1 mdx-hdf male pups, V0/V1 versican expression in diaphragm muscles was decreased by 50% compared to mdx littermates at 20-26 weeks of age. In mdx-hdf mice, spontaneous physical activity increased by 17% and there was a concomitant decrease in total energy expenditure and whole-body glucose oxidation. Versican reduction improved the ex vivo strength and endurance of diaphragm muscle strips. these changes in diaphragm contractile properties in mdx-hdf mice were associated with decreased monocyte and macrophage infiltration and a reduction in the proportion of fibres expressing the slow type I myosin heavy chain isoform. Given the high metabolic cost of inflammation in dystrophy, an attenuated inflammatory response may contribute to the effects of versican reduction on whole-body metabolism. Altogether, versican reduction ameliorates the dystrophic pathology of mdx-hdf mice as evidenced by improved diaphragm contractile function and increased physical activity. Abbreviations ½ RT ½ Relaxation time ADAMTS A disintegrin-like and metalloproteinase with thrombospondin type-1 motifs CK Creatine kinase CS Chondroitin sulphate DAPC Dystropin-associated protein complex ECM Extracellular matrix GAG Glycosaminoglycan Lo Optimal length MCP-1 Macrophage chemoattractant protein-1

Rare disease research workflow using multilayer networks elucidates the molecular determinants of severity in Congenital Myasthenic Syndromes

“…Patient 2, a 15 years old male, presents compound heterozygous variants in tenascin C ( TNC ), mediating acute ECM response in muscle damage 45 , 48 , and CNVs (specifically, a partial heterozygous copy number loss) in usherin ( USH2A ), which have been associated with hearing and vision loss 49 . Patient 16, a 25 years old female, presents compound variants in tenascin XB ( TNXB ), which is mutated in Ehlers-Danlos syndrome, a disease that has already been reported to have phenotypic overlap with muscle weakness 50 – 53 and whose compound heterozygous variants have been reported for a primary myopathy case 54 , 55 ; and versican ( VCAN ), which has been suggested to modify tenascin C expression 56 and is upregulated in Duchenne muscular dystrophy mouse models 57 , 58 . Patient 13, a 26 years old male, presents compound mutations in laminin α2 chain ( LAMA2 ), a previously reported gene related to various muscle disorders 59 – 61 whose mutations cause reduction of neuromuscular junction folds 62 , and collagen type XV α chain ( COL15A1 ), which is involved in guiding motor axon development 63 and functionally linked to a skeletal muscle myopathy 64 , 65 .…”

Dimethyl fumarate modulates the dystrophic disease program following short-term treatment

“…Macrophage infiltration was quantified as performed previously ( 71 ). TA cryosections of 10 μm were fixed in 4% paraformaldehyde, then reacted with an anti-CD68 primary antibody, a pan macrophage marker (Abcam; ab125212; 1:500 dilution; 90 minutes’ incubation), followed by incubation with an anti-rabbit HRP-linked secondary antibody (Vector Biolabs; PI-1000-1; 1:750 dilution; 75 minutes’ incubation).…”

In dystrophicmdxhindlimb muscles where fibrosis is limited versican haploinsufficiency transiently improves contractile function without decreasing inflammation

“…To assess the effect of versican haploinsufficiency on the pathology of mdx hindlimb muscles, female mdx (C57BL/10ScSn mdx ) mice obtained from the Animal Resource Centre (Australia), were bred with male hdf mice, haploinsufficient for the versican allele (hdf) obtained from Hoffman-La Roche (USA) (39). The resulting F1 mdx and mdx-hdf male pups were confirmed through genotyping and demonstrated the expected Mendelian genetic ratios (24). Juvenile and adult mice were maintained in grouped cages (2-5 mice per cage) until 6-or 20-weeks of age.…”

“…Versican is proteolytically processed by A Distintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS) versicanases into versikine — a pro- inflammatory matrikine (22, 23). In dystrophic muscles, versican and versikine are co-localised to regions of muscle degeneration and inflammation, as well as muscle regeneration (6, 24). The provisional matrix regulates cellular processes relevant to skeletal muscle development and regeneration (25).…”

“…We have previously used a genetic approach to test the hypothesis that versican reduction would ameliorate dystrophic muscle pathology (24). Specifically, female C57BL/10 mdx mice were bred with male heart defect (hdf) mice which are haploinsufficient for the versican allele (33).…”