IL23A and arthritic joint disease: To disentangle the skin–joint axis in psoriatic disease, we adapted the established PsA model of hydrodynamic Il23 gene transfer in B10.RIII mice4,15 by introducing IL-23 overexpression (IL-23OE) into the more resistant inbred strains BALB/c and C57BL/6, aiming for a model system that is resistant to arthritis.