RESUMO
Infiltration of immune cells and chronic inflammation substantially affect skeletal and cardiac muscle degeneration in Duchenne muscular dystrophy. In the immune system, extracellular adenosine triphosphate (ATP) released by dying cells is sensed as a danger associated molecular pattern through P2 purinergic receptors. Specifically, the P2X7 subtype has a prominent role in regulating immune system physiology and contributes to inflammasome activation also in muscle cells. Here, we show that in vivo blockade of the extracellular ATP/P2X purinergic signaling pathway by periodate-oxidized ATP delayed the progression of the dystrophic phenotype and dampened the local inflammatory response in mdx mice, a spontaneous mouse model of dystrophin deficiency. Reduced infiltration of leukocytes and macrophages and decreased expression of IL-6 were revealed in the muscles of periodate-oxidized ATP-treated mdx mice. Concomitantly, an increase in Foxp3(+) immunosuppressive regulatory T cells was observed and correlated with enhanced myofiber regeneration. Moreover, we detected reduced concentrations of profibrotic cytokines, including transforming growth factor-ß and connective tissue growth factor, in muscles of periodate-oxidized ATP-treated mdx mice. The improvement of inflammatory features was associated with increased strength and reduced necrosis, thus suggesting that pharmacologic purinergic antagonism altering the adaptive immune component in the muscle infiltrates might represent a promising therapeutic approach in Duchenne muscular dystrophy.
Assuntos
Músculo Esquelético/imunologia , Distrofia Muscular de Duchenne/imunologia , Receptores Purinérgicos P2X/fisiologia , Linfócitos T Reguladores/imunologia , Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/imunologia , Trifosfato de Adenosina/farmacologia , Trifosfato de Adenosina/uso terapêutico , Animais , Progressão da Doença , Avaliação Pré-Clínica de Medicamentos/métodos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos mdx , Músculo Esquelético/patologia , Músculo Esquelético/fisiologia , Distrofia Muscular de Duchenne/patologia , Distrofia Muscular de Duchenne/prevenção & controle , Condicionamento Físico Animal , Antagonistas do Receptor Purinérgico P2X/farmacologia , Antagonistas do Receptor Purinérgico P2X/uso terapêutico , Receptores Purinérgicos P2X/metabolismo , Regeneração/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Linfócitos T Reguladores/efeitos dos fármacosRESUMO
Neuromuscular disorders are a broad group of inherited conditions affecting the structure and function of the motor system with polymorphic clinical presentation and disease severity. Although individually rare, collectively neuromuscular diseases have an incidence of 1 in 3,000 and represent a significant cause of disability of the motor system. The past decade has witnessed the identification of a large number of human genes causing muscular disorders, yet the underlying pathogenetic mechanisms remain largely unclear, limiting the developing of targeted therapeutic strategies. To overcome this barrier, model systems that replicate the different steps of human disorders are increasingly being developed. Among these, the zebrafish (Danio rerio) has emerged as an excellent organism for studying genetic disorders of the central and peripheral motor systems. In this review, we will encounter most of the available zebrafish models for childhood neuromuscular disorders, providing a brief overview of results and the techniques, mainly transgenesis and chemical biology, used for genetic manipulation. The amount of data collected in the past few years will lead zebrafish to became a common functional tool for assessing rapidly drug efficacy and off-target effects in neuromuscular diseases and, furthermore, to shed light on new etiologies emerging from large-scale massive sequencing studies.