Facioscapulohumeral muscular dystrophy (FSHD) is characterized by clinical diversity, with FSHD1 being the most common form. It is associated with a toxic gain of function of the Double homeobox 4 (DUX4) gene, leading to muscle cell death and weakness. Despite the lack of approved treatments, recent studies highlight inflammation's role in early FSHD progression, triggered by inappropriate DUX4 expression.
In understanding inflammation's pivotal role in FSHD, a study assessed serum cytokines in 100 adult FSHD1 patients. Out of the 20 cytokines examined, 10 showed significantly altered expression levels compared to healthy controls of similar age and sex. FSHD1 patients exhibited heightened levels of inflammatory cytokines and diminished anti-inflammatory cytokines, signaling chronic inflammation. Notably, Interleukin-6 (IL-6) emerged as a promising disease activity biomarker, displaying robust correlations with established clinical severity and functional scores.
Given the pathological significance of inflammation and the correlation of IL-6 levels with disease severity, the ReInForce study will explore the satralizumab, an IL6-receptor (IL6-R) antagonist, for its efficacy in specifically reducing muscle and systemic inflammation. By antagonizing IL-6R downstream signaling, satralizumab holds promise in mitigating inflammation and potentially curtailing fibrofatty degeneration in FSHD.