Proinflammatory cytokine levels in fibromyalgia patients are independent of body mass index

BACKGROUND: Fibromyalgia (FM) is characterized by chronic, widespread muscular pain and tenderness and is generally associated with other somatic and psychological symptoms. Further, circulatory levels of proinflammatory cytokines (IL-1β, TNF-α, and IL-6) may be altered in FM patients, possibly in association with their symptoms. Recently, rises in BMI have been suggested to contribute to increased circulating levels of proinflammatory cytokines in FM patients. Our aim was to measure the circulatory levels of proinflammatory cytokines to determine the influence of BMI on these levels in FM patients and healthy volunteers (HVs). In Spanish FM patients (n = 64) and HVs (n = 25), we measured BMI and serum concentrations of proinflammatory cytokines by capture ELISA. FINDINGS: There were significant differences in BMI levels between FM patients (26.40 ± 4.46) and HVs (23.64 ± 3.45) and significant increase in IL-6 in FM patients (16.28 ± 8.13 vs 0.92 ± 0.32 pg/ml) (P < 0.001). IL-1β and TNF-α decreased in FM patients compared with HVs. By ANCOVA, there was no significant association between BMI and TNF-α (F = 0.098, p = 0.75) or IL-6 (F = 0.221, p = 0.63) levels in FM patients. CONCLUSIONS: Our analysis in FM patients of BMI as a covariate of proinflammatory cytokines levels showed that serum TNF-α and IL-6 levels are independent of BMI. Further studies are necessary to dissect these findings and their implication in future therapeutic approaches for FM patients.