Concentration of cytokines in patients with osteoarthritis of the knee and fibromyalgia.

INTRODUCTION

Fibromyalgia and osteoarthritis may present a relationship with the concentration of cytokines. The aim of this study was to compare the serum concentrations of IL-12p70, tumor necrosis factor, IL-10, IL-6, IL-1β, and IL-8 in patients with knee osteoarthritis and fibromyalgia.

MATERIALS AND METHODS

The study included 53 women (71.2±7.6 years old) diagnosed with knee osteoarthritis with moderate-to-severe pain (visual analog scale >4) for at least 3 months. Sixty women (54.1±8.1 years old) diagnosed with fibromyalgia according to the American College of Rheumatology criteria and with moderate-to-severe pain (visual analog scale >4) also participated in this study. For the dosage of cytokines, blood was collected in the morning: 5 mL from the cubital vein. The material was centrifuged at 4°C, separated into 100 μL aliquots and stored at -80°C until processing. Serum concentrations of the studied cytokines were assessed using the BD Cytometric Bead Array method. Data were analyzed with Student's t-test and the Mann-Whitney U test.

RESULTS

We found higher levels of IL-6, IL-10, and IL-1β in fibromyalgia patients. After adjustment of age as a covariate, there was no statistically significant difference in the concentration of any cytokine between fibromyalgia and knee osteoarthritis patients.

CONCLUSION

Patients with knee osteoarthritis and fibromyalgia with the same duration and intensity of pain demonstrate similar concentrations of cytokines. Aging may play a role in cytokine profile, a finding not so extensively addressed in the literature and one that should be further investigated.