RESUMEN
BACKGROUND: Recessive dystrophic epidermolysis bullosa (RDEB) is a blistering disease caused by mutations in the gene encoding type VII collagen (C7). RDEB is associated with fibrosis, which is responsible for severe complications. The phenotypic variability observed in siblings with RDEB suggests that epigenetic modifications contribute to disease severity. Identifying epigenetic changes may help to uncover molecular mechanisms underlying RDEB pathogenesis and new therapeutic targets. OBJECTIVES: To investigate histone acetylation in RDEB skin and to explore histone deacetylase inhibitors (HDACi) as therapeutic molecules capable of counteracting fibrosis and disease progression in RDEB mice. METHODS: Acetylated histone levels were detected in human skin by immunofluorescence and in RDEB fibroblasts by enzyme-linked immunosorbent assay (ELISA). The effects of givinostat and valproic acid (VPA) on RDEB fibroblast fibrotic behaviour were assessed by a collagen-gel contraction assay, Western blot and immunocytofluorescence for α-smooth muscle actin, and ELISA for released transforming growth factor (TGF)-ß1. RNA sequencing was performed in HDACi- and vehicle-treated RDEB fibroblasts. VPA was systemically administered to RDEB mice and effects on overt phenotype were monitored. Fibrosis was investigated in the skin using histological and immunofluorescence analyses. Eye and tongue defects were examined microscopically. Mass spectrometry proteomics was performed on skin protein extracts from VPA-treated RDEB and control mice. RESULTS: Histone acetylation decreases in RDEB skin and primary fibroblasts. RDEB fibroblasts treated with HDACi lowered fibrotic traits, including contractility, TGF-ß1 release and proliferation. VPA administration to RDEB mice mitigated severe manifestations affecting the eyes and paws. These effects were associated with fibrosis inhibition. Proteomic analysis of mouse skin revealed that VPA almost normalized protein sets involved in protein synthesis and immune response, processes linked to the increased susceptibility to cancer and bacterial infections seen in people with RDEB. CONCLUSIONS: Dysregulated histone acetylation contributes to RDEB pathogenesis by facilitating the progression of fibrosis. Repurposing of HDACi could be considered for disease-modifying treatments in RDEB.
Recessive dystrophic epidermolysis bullosa (or 'RDEB') is a rare skin disease that affects fewer than 5,000 people in the USA. A similar number of people in Europe are affected. RDEB is caused by mutations in the gene that controls the production of a protein called 'type VII collagen' (or 'C7'). A shortage of C7 causes fragile skin that blisters. In severe forms of RDEB, wounds heal slowly and can even affect a person's life expectancy. Differences in the disease are common in people (even identical twins) with RDEB who have similar levels of C7. This suggests that how severe the disease is could be affected by molecular processes that control other genes. Understanding these processes may help us to find treatments for RDEB. This study was done in Italy, in collaboration with centres in Germany and Switzerland. We wanted to see whether a chemical modification called 'histone acetylation' (which influences gene activity) is different in RDEB and whether it can be targeted by a specific treatment. We found that histone acetylation is reduced in RDEB skin and in skin cells grown in the lab called 'fibroblasts'. When we increased histone acetylation in fibroblasts with two drugs called givinostat and valproic acid, the amount of scar tissue produced decreased. This is important because scar tissue can lead to severe symptoms. We carried out more experiments to study the effects of givinostat and valproic acid in mice with RDEB. We found that valproic acid reduces the severity of RDEB by decreasing the disease's harmful effects and reducing the amount of scar tissue. Our findings suggest that abnormal histone acetylation contributes to the scar tissue seen in RDEB. Our study shows that valproic acid could be useful in treating the scarring seen in RDEB and in reducing the effects of the disease. As this drug is used to treat other diseases, there could be potential for rapid repurposing of it for RDEB.
Asunto(s)
Colágeno Tipo VII , Progresión de la Enfermedad , Epidermólisis Ampollosa Distrófica , Fibroblastos , Fibrosis , Inhibidores de Histona Desacetilasas , Piel , Epidermólisis Ampollosa Distrófica/tratamiento farmacológico , Epidermólisis Ampollosa Distrófica/patología , Epidermólisis Ampollosa Distrófica/genética , Animales , Humanos , Inhibidores de Histona Desacetilasas/farmacología , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Colágeno Tipo VII/genética , Piel/patología , Piel/efectos de los fármacos , Ratones , Ácido Valproico/farmacología , Histonas/metabolismo , Acetilación/efectos de los fármacos , Masculino , Femenino , Modelos Animales de Enfermedad , Factor de Crecimiento Transformador beta1/metabolismo , Células Cultivadas , Niño , CarbamatosRESUMEN
Skeletal muscle atrophy is a pathological condition so far without effective treatment and poorly understood at a molecular level. Emerging evidence suggest a key role for circular RNAs (circRNA) during myogenesis and their deregulation has been reported to be associated with muscle diseases. Spermine oxidase (SMOX), a polyamine catabolic enzyme plays a critical role in muscle differentiation and the existence of a circRNA arising from SMOX gene has been recently identified. In this study, we evaluated the expression profile of circular and linear SMOX in both C2C12 differentiation and dexamethasone-induced myotubes atrophy. To validate our findings in vivo their expression levels were also tested in two murine models of amyotrophic lateral sclerosis: SOD1G93A and hFUS+/+, characterized by progressive muscle atrophy. During C2C12 differentiation, linear and circular SMOX show the same trend of expression. Interestingly, in atrophy circSMOX levels significantly increased compared to the physiological state, in both in vitro and in vivo models. Our study demonstrates that SMOX represents a new player in muscle physiopathology and provides a scientific basis for further investigation on circSMOX RNA as a possible new therapeutic target for the treatment of muscle atrophy.