CD274 (PD-L1), CXCL13, BIRC5, and SMPD3 play the following roles in the IL-17a and IL-23 pathways: CD274 (PD-L1): The IL-17a and IL-23 pathways are closely related to the pathogenesis of autoimmune diseases like psoriasis. Here, SMPD3 is linked to psoriasis.