ANPEP and intervertebral disk degenerative disorder: Figure 1A shows increased NLRP3, caspase-1 and GSDMD-N expression in human degenerated NP tissue, indicating that NP cell pyroptosis is increased during IDD. We next measured APN expression in NP tissue as well as LPS-stimulated NP cells. Decreased APN expression was observed in degenerated NP tissue (Figure 1B). Consistently, stimulation of human NP cells with LPS dramatically attenuated APN levels (Figure 1C).