Fibromyalgia (FM) is a common rheumatologic disease characterized by chronic widespread pain, along with various clinical manifestations including atypical autoimmune characteristics. Despite its high prevalence, there remain no approved laboratory tests to identify specific manifestations of FM, or to rule out FM from other rheumatic diseases. Anti-dense fine speckled 70 (anti-DFS70) antibodies were initially identified as a form of anti-nuclear antibodies in a patient with interstitial cystitis. Anti-DFS70 antibodies are found in ≤ 10% of healthy individuals, but have suggestive negative association with autoimmune diseases; however, the clinical significance of these autoantibodies in FM patients remains poorly understood.
We examined 39 patients with FM, along with 17 patients with systemic lupus erythematosus (SLE), and 19 healthy individuals (HI). Patients were compared based on physical measurements, disease duration, tender point counts, FM Impact Questionnaire (FIQ) scores, visual analog scale (VAS) for pain, somatic symptoms, and anti-DFS70 antibodies.
Levels of anti-DFS70 antibodies were significantly higher in the FM and HI groups than in those with SLE. Both anti-DFS70 antibodies and VAS scores were positively correlated with FM. Within the FM group, patients with arthralgia had higher anti-DFS70 antibody values compared to those without arthralgia (p = 0.024); antibody levels were also higher in patients with sleep disturbances relative to those without sleep issues (p = 0.024). In contrast, there were no correlations between anti-DFS70 antibodies and age, body mass index, disease duration, tender point counts, FIQ, short-form health survey results, or other clinical manifestations.
Anti-DFS70 antibodies may represent a useful biomarker for differentiating between FM and other autoimmune diseases. The levels of anti-DFS70 antibodies were also significantly higher among patients with arthralgia and sleep disturbances. Further investigations are necessary to evaluate the relationships between anti-DFS70 antibodies and other cytokines as a predictive marker for pain.