TNF and psoriatic arthritis: In addition to the classical pro-inflammatory cytokines interleukin (IL)-1, IL-6 and Tumor Necrosis Factor (TNF)α, whose role in IMIDs has been amply described (47), the IL-23/17 axis is emerging as a common feature in several IMIDs among which IBD, psoriasis, uveitis, psoriatic arthritis and evidence are accumulating about its role in RA (48, 49).