TNF and intervertebral disk degenerative disorder: As expected, given its central role in regulating inflammation, dysfunctions in the IL-17 cytokine/IL-17R signaling axis can promote the production of several pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), and increase the activity of metalloproteinases (MMPs), which play important roles in disc degeneration [33].