Transforming growth factor-beta2 is elevated in skeletal muscle disorders

The transforming growth factor betas (TGF-betas) are multifunctional growth factors that act on both fibroblasts and myosatellite cells. In rodent models of muscle diseases, high levels of TGF-beta2 are expressed by myogenic cells. We have examined whether the expression of TGF-beta2 is also elevated in diseased human muscles. The disorders examined were Duchenne muscular dystrophy, myotonic dystrophy, myotubular myopathy, spinal muscular atrophy, and amyotrophic lateral sclerosis. The levels of TGF-beta2 immunoreactivity were elevated in atrophic, necrotic, and regenerating fibers and in fibers with central nuclei or cytoplasmic masses, irrespective of whether fibrosis was present. We therefore suggest that TGF-beta2 is important for muscle repair and that the presence of a TGF-beta within a muscle only leads to fibrosis if certain other factors are present.