The paraffin-embedded nucleus pulposus tissues were processed for immunohistochemical staining as previously described.33 (link) The primary antibody used was caspase-1 (1:150, Proteintech, Chicago, USA, Cat. No.: 22915-1-AP) and the secondary antibody was goat anti-rabbit IgG (H+L) HRP (1:200, Affinity Biosciences, USA, Cat. #: S0001). The sections were visualized using a microscope (CTR4000B, Leica). Experiments were repeated three times independently.