Dual effects of TGF‐β inhibitor in ALS ‐ inhibit contracture and neurodegeneration

Abstract

AbstractAs persistent elevation of transforming growth factor‐β (TGF‐β) promotes fibrosis of muscles and joints and accelerates disease progression in amyotrophic lateral sclerosis (ALS), we investigated whether inhibition of TGF‐β would be effective against both exacerbations. The effects of TGF‐β and its inhibitor on myoblasts and fibroblasts were tested in vitro and confirmed in vivo, and the dual action of a TGF‐β inhibitor in ameliorating the pathogenic role of TGF‐β in ALS mice was identified. In the peripheral neuromuscular system, fibrosis in the muscles and joint cavities induced by excessive TGF‐β causes joint contracture and muscular degeneration, which leads to motor dysfunction. In an ALS mouse model, an increase in TGF‐β in the central nervous system (CNS), consistent with astrocyte activity, was associated with M1 microglial activity and pro‐inflammatory conditions, as well as with neuronal cell death. Treatment with the TGF‐β inhibitor halofuginone could prevent musculoskeletal fibrosis, resulting in the alleviation of joint contracture and delay of motor deterioration in ALS mice. Halofuginone could also reduce glial cell‐induced neuroinflammation and neuronal apoptosis. These dual therapeutic effects on both the neuromuscular system and the CNS were observed from the beginning to the end stages of ALS; as a result, treatment with a TGF‐β inhibitor from the early stage of disease delayed the time of symptom exacerbation in ALS mice, which led to prolonged survival.