T cells and cytokines in inflamed psoriatic skin. Who's in charge?

Inflammation in psoriasis is driven through the IL-23/IL-17 pathway. Monoclonal antibodies targeting cytokines in the pathway have proven highly effective and are widely used in clinical practice. There is still much to learn, however, about how these pathogenic responses are controlled, particularly with respect to the highly immunologically active molecules produced by the inflamed skin tissue itself. These tissue-derived molecules, which include IL-33, play important roles in modulating chronic inflammation that we are only beginning to understand. Here we highlight new research indicating a role for IL-33 in modulating the inflammatory Th17 response in psoriasis, which may provide avenues for developing new psoriasis treatments.