IL-17A expression is modulated pre/post biologic therapy. Baseline and three months serum samples from 38 patients were analysed using IL-17A ELISA. Eleven of these patients showed detectable levels of IL-17A. (a) Data shown are of these 11 patients. (b) Matrix metalloproteinase (MMP)/tissue inhibitor of metalloproteinase (TIMP) ratios are significantly reduced in IL-17A-negative patients three months following biologic therapy.