Fig. 2.

JAK inhibition of cytokine pathways involved in the pathogenesis of SpA

Cytokine signaling and production at the enthesis: signaling for a number of key cytokine pathways implicated in the pathogenesis of SpA is blocked through direct inhibition of JAKs, including IFNγ, IL-7, IL-12, IL-15, IL-22 and IL-23. Other important cytokines, such as TNFα, IL-1 and IL-17, signal independently of JAKs, but their expression is regulated by JAK-dependent cytokines and, therefore, may be blocked indirectly via JAK inhibition. These cytokines influence cellular function for a broad range of innate and adaptive cell types, including many of those shown in Fig. 1. JAK, Janus kinase; TYK, tyrosine kinase.