Distinct Cytokine Profiles in Patients with Oligoarticular Juvenile Idiopathic Arthritis after <i>in</i> <i>Vitro</i> Blockade of Interleukin (IL)-1 and Tumor Necrosis Factor (TNF)-α

Abstract

Oligoarticular juvenile idiopathic arthritis (oJIA) is an antigen-driven and lymphocyte-mediated autoimmune disorder with irregularity in the adaptive immune system. Auto reactive T cells, activated by cartilage-derived auto antigens, produce pro-inflammatory cytokines as IFN-γ and IL-17. Failure of regulatory T cells leads to decreased anti-inflammatory cytokine IL-10 production and results in the loss of immune tolerance. This activation of innate and adaptive immunity stimulates the release of pro-inflammatory cytokines IL-1, IL-6 and TNF-α. Thus, inhibition of these cytokines is considered as an appropriate therapeutic strategy for oJIA. The aim of this study was to investigate whether the blockade of a single cytokine pathway in the present cytokine setting causes an unfavourable imbalance in the cytokine system or whether the blockade is sufficient to suppress the inflammatory condition. We examined the cytokine secretion after in vitro inhibition of IL-1 and TNF-α of patients with oJIA and healthy subjects. This single center cohort study consisted of oJIA affected children and control subjects. Cytokine profiles from cell culture supernatants were examined with multiplex fluorescent bead immunoassay by flow cytometry. Adalimumab prevents highly effective and very selective effect of the cytokine TNF-α. Due to its structure, the mode of action of etanercept is difficult to display. In addition, adalimumab and etanercept appear in vitro suppressive to IFN-γ. The efficiency of both substances is particularly supported by the increased secretion of anti-inflammatory cytokine IL-4. In contrast, anakinra unselectively inhibits the pro-inflammatory macrophage cytokines. To conclude, our observations suggest that inhibition of IL-1 or TNF-α may contribute to the unselective decline of other pro-inflammatory cytokines in oJIA patients. The selective anti-inflammatory effect of cytokine inhibitors is most likely supported by an increase of IL-4 or IL-10. It still remains to be elucidated whether the reduced IFN-γ secretion is maybe causative for the increased susceptibility to infections with opportunistic pathogens.