Assessing the Impact of IL-6 and Serotonin on Pain and Symptomatology in Fibromyalgia: An Exploratory Clinical Study

Abstract

Background and Objectives: Fibromyalgia (FM) is a chronic musculoskeletal pain syndrome characterized by widespread pain and a variety of other symptoms, including fatigue, cognitive dysfunction, and sleep disturbances. Recent research has highlighted the potential role of pro-inflammatory cytokines and neurotransmitters in the pathophysiology of FM. This study aimed to investigate the relationship between serum levels of interleukin-6 (IL-6) and serotonin with the clinical parameters observed in patients with fibromyalgia. Additionally, it sought to analyze the similarities and differences among the different groups classified by symptom severity. Materials and Methods: This cross-sectional study included 26 female patients aged 20–70 diagnosed with FM according to the American College of Rheumatology (ACR) 2016 criteria and 14 healthy controls (HCs). Serum levels of IL-6 and serotonin were measured using electrochemiluminescence and high-performance liquid chromatography (HPLC), respectively. Results: FM patients exhibited significantly higher pain scores (VAS), anxiety, and depression levels compared to HCs. FIQ-R scores were significantly elevated in FM patients, with stratification showing 3.8% mild, 65.4% moderate, 23.1% severe, and 7.7% very severe cases. While no significant difference in IL-6 levels was observed between the FM patients and HCs, a trend towards increased IL-6 levels in patients with higher FIQ-R scores was noted. Serum serotonin levels were significantly lower in the FM patients than in the HCs, with moderate patients having lower levels than those classified as severe and very severe. Conclusions: The study underscores the potential role of IL-6 and serotonin in the pathophysiology of FM, suggesting that these biomarkers could be relevant in assessing the severity and impact of FM. Further research is needed to elucidate these relationships and their implications for developing personalized treatment strategies.