Comparison of the Levels of Pro-Inflammatory Cytokines Released in the Vastus Lateralis Muscle of Patients with Fibromyalgia and Healthy Controls during Contractions of the Quadriceps Muscle--A Microdialysis Study

PLoS One. 2015 Dec 1;10(12):e0143856. doi: 10.1371/journal.pone.0143856. eCollection 2015.

Abstract

Objective: Fibromyalgia is associated with central hyperexcitability, but it is suggested that peripheral input is important to maintain central hyperexcitability. The primary aim was to investigate the levels of pro-inflammatory cytokines released in the vastus lateralis muscle during repetitive dynamic contractions of the quadriceps muscle in patients with fibromyalgia and healthy controls. Secondarily, to investigate if the levels of pro-inflammatory cytokines were correlated with pain or fatigue during these repetitive dynamic contractions.

Material and methods: 32 women with fibromyalgia and 32 healthy women (controls) participated in a 4 hour microdialysis session, to sample IL-1β, IL-6, IL-8, and TNF from the most painful point of the vastus lateralis muscle before, during and after 20 minutes of repeated dynamic contractions. Pain (visual analogue scale; 0-100) and fatigue Borg's Rating of Perceived Exertion Scale; 6-20) were assessed before and during the entire microdialysis session.

Results: The repetitive dynamic contractions increased pain in the patients with fibromyalgia (P < .001) and induced fatigue in both groups (P < .001). Perceived fatigue was significantly higher among patients with fibromyalgia than controls (P < .001). The levels of IL-1β did not change during contractions in either group. The levels of TNF did not change during contractions in patients with fibromyalgia, but increased in controls (P < .001) and were significantly higher compared to patients with fibromyalgia (P = .033). The levels of IL-6 and IL-8 increased in both groups alike during and after contractions (P's < .001). There were no correlations between pain or fatigue and cytokine levels after contractions.

Conclusion: There were no differences between patients with fibromyalgia and controls in release of pro-inflammatory cytokines, and no correlations between levels of pro-inflammatory cytokines and pain or fatigue. Thus, this study indicates that IL-1β, IL-6, IL-8, and TNF do not seem to play an important role in maintenance of muscle pain in fibromyalgia.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytokines / analysis
  • Cytokines / metabolism*
  • Fatigue
  • Female
  • Fibromyalgia / physiopathology*
  • Humans
  • Inflammation
  • Microdialysis*
  • Muscle Contraction*
  • Pain
  • Quadriceps Muscle / metabolism*
  • Quadriceps Muscle / physiology

Substances

  • Cytokines

Grants and funding

This study was supported by grants from the Swedish Rheumatism Association (https://reumatikerforbundet.org/); the Swedish Research Council (http://vr.se/); the Health and Medical Care Executive Board of Västra Götaland Region (http://www.vgregion.se/en/Vastra-Gotalandsregionen/Home/Governance/Namnder-och-styrelser/The-Regional-Executive-Board/); ALF-LUA at Sahlgrenska University Hospital (http://www.researchweb.org/is/alfgbg); Linköping University Hospital, Linköping University; Gothenburg Center for Person Centered Care (GPCC); AFA Insurance (https://www.afaforsakring.se/forskning/); ALF—Stockholm County Council (https://forskningsstod.vmi.se/Ansokan/start.asp); and Karolinska Institute Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.