Potential role of IL-9 in the pathogenesis of systemic lupus erythematosus

It has been identified that Th cells and their cytokines play a pleiotropic role in the pathogenesis of systemic lupus erythematosus (SLE). Recently, a new effector T cell subset, Th9 cells, which preferentially secrete IL-9, has been identified. Apart from Th9, there is evidence that IL-9 can be produced by several other T cell subsets like Th17. At the same time, IL-9 affecting function of Th cells and mast cell. However, there are no unambiguous conclusions that IL-9 make a contribution for phenotype of SLE. Recently, IL-9 exerts profound anti-inflammatory effects in several cells or experimental autoimmune models. In particular, IL-9 production seems important in mast cell recruitment, defect IL-9/IL-9R axis exhibit a more severe course of EAE and have a defect in the suppressive activity of Tregs, which are implicated a potect role for SLE. In contrast, IL-9 may contribute the proliferation of several CD4+ T cells, suggesting that IL-9 may be therapeutically relevant in SLE. In this article, we briefly discuss the biological features of IL-9 and summarize recent advances focus on the role of IL-9 in the pathogenesis and treatment of SLE.