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 antiinflammatory 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.