Facioscapulohumeral Muscular Dystrophy (FSHD), a genetic disorder causing loss of muscular function, primarily impacts the muscles in the face, shoulders, and upper arms. FSHD ranks as the number three most common form of muscular dystrophy and has an estimated prevalence of about 1 case per 20,000 individuals. As a progressive disease with limited therapeutic options, FSHD patients would benefit from a method to quickly and easily identify potential disease severity to facilitate symptom management.
The pathology of FSHD is highly dependent on inflammation, and circulating immune cells are correlated with accelerated disease progression. The documented role of immunity and inflammation in FSHD progression led a team of researchers to investigate specific inflammatory mediators, known as cytokines. The study's findings, recently published in the Journal of Neuromuscular Disease, suggest an inflammatory marker plays an essential role in FSHD progression.
Cytokines are proteins that regulate the immune system. Some cytokines, known as pro-inflammatory cytokines, are associated with an active immune response. Others, called anti-inflammatory cytokines, slow down the immune system. The researchers analyzed a panel of 20 cytokines in blood samples of 100 adult FSHD patients. The cytokine levels were then correlated to disease severity. The investigators used several methods to define disease severity, including Clinical Severity Scoring, Manual Muscle Testing, and Brooke and Vignos scoring.
The investigators identified interleukin-6 (IL-6) as the only cytokine which correlated to disease severity. The study also demonstrated that patients with FSHD express higher IL-6 levels than healthy controls. Finally, serum IL-6 concentration among FSHD patients increased relative to severity.
The results of the study suggest that IL-6 could serve as an effective biomarker to predict disease severity in FSHD patients. In addition, the authors suggest that IL-6 could serve as a potential candidate for developing targeted therapies for the treatment of FSHD. Notably, two monoclonal antibodies against IL-6, tocilizumab and sarilumab, have already been developed to treat rheumatoid arthritis. As these medications are established, the regulatory approval process could be accelerated if IL-6 proves a viable target for FSHD.