Upregulated IL-23 and IL-17 in Behçet patients with active uveitis.

Behçet disease (BD) is a systemic inflammatory disease presumably caused by an autoimmune response. The interleukin (IL)-23/IL-17 pathway has been demonstrated to be involved in the development and maintenance of certain inflammatory diseases. This study was designed to investigate the role of IL-23 and IL-17 in BD. IL-23p19 mRNA in peripheral blood mononuclear cells (PBMCs) was examined using RT-PCR. The levels of IL-23, IL-17, and IFN-gamma in sera or PBMCs were detected by ELISA. Flow cytometry was used to evaluate the frequencies of IL-17-producing and IFN-gamma-producing T cells and the expression of CD45RO. Results showed that the expression of IL-23p19 mRNA, IL-23, IL-17, and IFN-gamma was markedly elevated in BD patients with active uveitis. The frequencies of IL-17-producing and IFN-gamma-producing T cells from PBMCs were significantly upregulated in BD patients with active uveitis. The increased IL-17 (3.10% +/- 0.53%) in BD patients with active uveitis was primarily produced by CD45RO(+) memory T cells. Recombinant (r) IL-23 could upregulate IL-17 production by polyclonally stimulated PBMCs, whereas interferon (IFN)-gamma downregulated IL-17 production. These findings reveal that the levels of IL-23, IL-17, and IFN-gamma are elevated in BD patients with active uveitis, and they suggest that the IL-23/IL-17 pathway together with IFN-gamma is associated with the active intraocular inflammation in BD patients.