Circulating cytokine levels compared to pain in patients with fibromyalgia - A prospective longitudinal study over 6 months

Objective. This prospective study examined circulating cytokines in patients with fibromyalgia (FM) over 6 months rather than at only one timepoint, and investigated correlations between serum cytokine concentrations and pain intensity in FM patients receiving multidisciplinary pain therapy. Methods. Serum concentrations of proinflammatory cytokines interleukin 6 (IL-6), IL-8, and tumor necrosis factor-alpha (TNF-alpha) and anti inflammatory cytokines IL-4 and IL-10 were measured (Bio-Plex system) in 20 FM patients and 80 healthy subjects on admission and 10, 21, and 180 days after initiation of treatment and correlated to pain intensity. Results. On admission, serum levels of IL-8 (p < 0.001) and TNF-alpha (p < 0.001), but not IL-6, were elevated in patients with FM. No significant difference in IL-4 and IL-10 was found between FM patients and controls. High IL-8 levels remained consistent during the followup, but TNF-alpha was already reduced after 10 days and until 6 months after therapy. After 6 months' treatment with multidisciplinary pain therapy, IL-8 and TNF-alpha levels were significantly lower than at the beginning (p < 0.05 for IL-8, p < 0.001 for TNF-alpha. IL-8 but not TNF-alpha serum levels were correlated with pain intensity (r = -0.782, p = 0.001) in FM patients after 6 months' multidisciplinary pain therapy. Conclusion. Our results suggest that proinflammatory cytokines TNF-alpha and IL-8 are involved in FM, but they do not apparently provoke the pain of FM directly. Multidisciplinary pain therapy modified the cytokine profile in patients with FM during the observation period.