Thus, the interplay between the IL-23–IL-17 axis and keratinocytes is central to the IL-17-mediated inflammatory loop in psoriasis (Fig. 3a). Despite the definitive role of keratinocytes in this loop, the complete pathway between the IL-23–IL-17 axis and the other components of the EIME (such as the microbiota and sensory nerves) has not yet been demonstrated (Fig. 3b,c), and the precise features of these elements in driving the IL-17 inflammatory loop in psoriasis remain to be elucidated.