Introduction: Facioscapulohumeral Muscular Dystrophy (FSHD) is one of the most common human muscular dystrophy. The development of this condition has been linked to the abnormal expression of the DUX4 gene. Inflammation seems to have a key role in the pathogenesis of FSHD, and high levels of innate immunity markers have been observed both in serum and skeletal muscles of FSHD patients. Moreover, recent studies have suggested that complement activation could play a role in fostering inflammation associated with FSHD. In fact, elevated levels of complement components (e.g. C3 and C4b) were found FSHD patient plasma and muscles. However, the direct relationship between abnormal DUX4 expression and inflammation remains controversial.
Study protocol: In order to elucidate the role of DUX4 in inducing the innate immune response and the complement activation, we are performing in vitro myotubes-macrophages (THP-1) co-cultures to compare inducible myotubes overexpressing DUX4 (i-DUX4) vs DUX4-KO and DUX4-WT myotubes. Macrophages are plated on Transwell inserts on top of the myotubes and the response of macrophages analyzed by evaluating the levels of pro-inflammatory markers by RT-qPCR and ELISA, and the complement expression/presence into myotubes. By using FSHD patient serum, we will evaluate the presence of circulating factors (among which the complement) crucial to mediate a macrophage response. For this reason, serum of healthy subjects will be used as a control.
By this study, we aim to gain insights into the mechanisms underlying inflammation in FSHD, with the ultimate goal of identifying potential therapeutic targets.