Evaluation of Clinical Impact of Interleukin 8 Gene Expression in Patients with Fibromyalgia

Background: Fibromyalgia (FM) is a musculoskeletal syndrome characterized by diffuse and chronic pain associated with other symptoms such as fatigue, sleep/cognition disorders, headache, depression and anxiety, resulting from a change in pain processing. Previous research has shown an increase in some interleukins (IL) in patients with FM when compared to controls, however, there is still no uniformity and consensus in the results. There is no study that evaluates IL8 mRNA expression in FM and its association with obesity and other clinical parameters. This study aims to verify the impact of IL8 mRNA expression on the clinical parameters of patients with FM (FMG) in relation to the comparison group (CG). Method: This study evaluated patients diagnosed with FM treated at the rheumatology service of the Hospital das Clínicas of the Federal University of Pernambuco (HC-UFPE). The CG group was composed of individuals without chronic pain (companions of the patients and hospital employees). Clinical and demographic data were collected in both groups, and questionnaires for fatigue (FACIT-F), impact of FM (FIQ-R), depression (BDI), and sleep (NRS) were applied to both groups. Peripheral blood was collected for evaluation of IL8 gene expression through real time polymerase chain reaction (qPCR). Results: Patients with FM show a lower frequency of IL8 gene expression compared to the CG, but FMG presented mainly up regulated in relation to CG. There was no association of IL8 expression and worse FIQ-R indices, sleep disturbance, BMI or fatigue. However, there was an association between IL8 expression and moderate depression ( p = 0.002) and physical activity ( p = 0.039), where patients in FMG who did express IL8 were practicing less physical activity. Conclusion: Patients in FMG did not have a higher frequency of IL8 expression compared to CG, however patients with IL8 expression have a greater association with moderate depression.