Abstract
Background Low-dose IL-2 supplementation is a promising treatment of SLE. However, in most of current studies, lack of appropriate control groups lead to uncertainty on its efficacy. We conducted a randomized double-blinded placebo controlled trial to determine the efficacy of low-dose IL-2 on various organ involvement in SLE and the response predictors for this therapy.
Methods SLE patients received either IL-2 (n=30) or placebo (n=30) with standard treatment for 10 weeks. The clinical responses, laboratory features and dynamics of immune cell subsets and molecular profile were determined. The association between these parameters and response to IL-2 treatment was analyzed.
Results The SRI-4 response rate of IL-2 group was significantly higher than that of placebo group from week 6 to week 10. The most obvious improvement on organ involvement was observed in the renal domain. Both of the complete remission tate and partial remission rate of lupus nephritis (LN) in IL-2 group were significantly higher (P<0.05). Arthritis was more improved in IL-2 group than the placebo group. Other organ involvements were all imporved in IL-2 and placebo group, without significant difference. Our further analysis showed that decreased Treg ratio in SLE patients before treatment showed good ability for predicting SRI-4 response with IL-2 treatment. Serum anti-IL-2 autoantibody was increased and associated with disease severity in SLE, but it was not induced by IL-2 treatment and did not predict the clincial response to IL-2 therapy. Our in vivo and in vitro analysis also showed that IL-2 may synergize with glucocorticoid treatment to further promote Treg survial and functions in SLE patients and accelerate the decrease of disease activity.
Conclusions Low-dose IL-2 might be most efficient in treatment of lupus nephritis and synergize with conventional treatment such as glucocorticoid. Low baseline Treg ratio might be an indicator to apply this novel treatment.
