The Impact of 24-Month Etanercept Therapy on Changes in Adiponectin, Leptin and Tenascin C Levels in the Blood of Children with Juvenile Idiopathic Arthritis

<b>Background/Objectives</b>: The most commonly diagnosed group of rheumatic diseases in children is juvenile idiopathic arthritis. It is characterized by a chronic inflammatory process that leads to the degradation of the bone and joint system and increased secretion of pro-inflammatory cytokines such as TNF-α, IL-1, and IL-6. These cytokines contribute to the dysregulation of adipocytokine metabolism, including adiponectin and leptin, as well as extracellular matrix components, such as tenascin C. While it is known that children with JIA exhibit TNF-α-stimulated degradation of most ECM cartilage components, the effect of TNF-α antagonists, such as etanercept, on these processes has not yet been evaluated. Therefore, the aim of our study was to assess the dynamics of changes in tenascin C, adiponectin, and leptin levels in the blood of children with JIA, both before and during therapy. <b>Methods</b>: The study material consisted of blood samples collected from 66 children of both sexes, including 40 girls and 26 boys diagnosed with juvenile idiopathic arthritis and treated with etanercept, as well as from 40 healthy children (22 girls and 18 boys). The quantitative assessment of adiponectin, leptin, and tenascin C levels was performed using commercial ELISA tests. <b>Results</b>: The conducted study revealed that untreated children with JIA exhibit altered plasma levels of all examined parameters-adiponectin, leptin, and tenascin C. Specifically, there was an increase in adiponectin concentration and a decrease in leptin as well as TNC levels compared to healthy children. The results demonstrated the beneficial effects of the TNF-α antagonist, i.e., etanercept, which not only improved the clinical condition of children with JIA but also positively influenced the metabolism of both adipokines and tenascin C. <b>Conclusions</b>: The obtained results suggest the potential use of adiponectin, leptin, and tenascin C as biochemical markers of the effectiveness of etanercept therapy in inhibiting the progression of degenerative joint changes in children with JIA treated with TNF-α inhibitors.