Associations between serum interleukin-23 levels and clinical characteristics in patients with systemic lupus erythematosus

OBJECTIVE: To analyse the association between serum interleukin (IL)-23 mRNA levels and clinical characteristics in patients with systemic lupus erythematosus (SLE). METHODS: Serum IL-23 and IL-17 mRNA levels were quantified using real-time reverse transcription-polymerase chain reaction in patients with SLE and healthy controls. Disease activity was assessed using the SLE Disease Activity Index-2k. RESULTS: A total of 108 patients with SLE and 60 control subjects were recruited. IL-23 mRNA levels were significantly higher in patients with SLE compared with healthy controls, and in patients with SLE and renal involvement compared with SLE alone. IL-23 mRNA levels were not different between patients with active or inactive SLE, but the IL-17/IL-23 ratio was significantly higher in patients with active disease. IL-17 and IL-23 mRNA levels were strongly correlated. CONCLUSIONS: Serum IL-23 mRNA was elevated in patients with SLE and renal disease, and the IL-17/IL-23 ratio was higher in patients with active SLE. These findings suggest that IL-23 may play an important role in SLE pathogenesis, and that the IL-17/IL-23 ratio may be useful biomarker for active disease.