İnvestigation of serum S100 levels in fibromyalgia patients

SUMMARY Assessment of serum S100 protein levels in patients with fibromyalgia Background: Fibromyalgia (FM) is a form of rheumatic disease characterized widespread musculoskeletal pain. One of the hypotheses about the pathophysiology of FM is immunological mechanisms. There are currently no clinically effective biomarkers that detect cognitive and behavioral disturbances in fibromyalgia. S100 proteins are multifunctional proteins with a regulatory role in a variety of cellular processes. Objectives: We aimed to investigate the serum levels of S100 protein in patients with FM and its association with cognitive functions, functional and psychological status and quality of life in FM patients. Materials and Methods: Fifty patients who met the 1990 ACR criteria for the classification of FM and forty healthy controls (HCs) were enrolled to the study. Serum S100 levels were measured by ECLIA. The Fibromyalgia Impact Questionnaire (FIQ) was used to assess the functional status. Short-Form Health Survey (SF-36) was used to assess quality of life. Beck Depression Inventory (BDI) and State-Trait Anxiety Inventory (STAI) to assess depression and anxiety respectively. Mini mental test and clock drawing test were used to assess cognitive functions. Results: Mean serum level of S100 was not significantly different in patients with FM compared to HCs (p=0.459). The scores of SF 36, BDI, STAI I-II, FIQ were significantly higher in FM patients (p< 0.001). Serum S100 levels were not correlated with the scores of SF 36, STAI I-II, BDI, FIQ, mini mental test and clock drawing test (p>0.05). S100 levels were correlated with the weight of individuals (p=0.039, r=0.292). Conclusions: S100 proteins have pivotal roles in many rheumatological diseases but we could not demonstrate their roles in FM. They were suggested to be a marker indicating cognitive dysfunctions in many clinical pathologies. The underlying mechanisms that cause cognitive dysfunctions in these clinical conditions are probably different from the causative mechanisms of cognitive dysfunctions in FM patients. Key words: Fibromyalgia, S100 protein, cognitive dysfunction, functional status, psychological status, quality of