1,4-Dihydropyridine (DHP) suppresses against oxidative stress in nucleus pulposus via activating sirtuin-1

Intervertebral disc degeneration (IVDD) is a major cause of many spinal diseases characterized mainly by nucleus pulposus degradation. 1,4-dihydropyridine (DHP), a new activator of sirtuin-1 (sirt1), has been reported to have anti-oxidative effects. The aim of this study is to investigate the effect of DHP on nucleus pulposus (NP) cells in vitro. NP cells were pretreated with IL-1β to establish a degenerated model, and then treated with DHP alone or DHP combined with selisistat (an inhibitor of sirt1). ROS level was analyzed by flow cytometry. Production of IL-6 and TNF-α were evaluated by the enzyme-linked immunosorbent assay (ELISA). The mRNA and protein expression were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot respectively. Immunofluorescence was used to assess the expression of collagen-II and sirt1. We found that DHP inhibited IL-1β-induced upregulation of ROS, TNF-α, IL-6, MMP-3, ADAMTS-5. Besides, DHP remarkably increased the sirt1 and anti-oxidative protein SOD-1 level. Furthermore, DHP significantly protected the IL-1β-induced degradation of collagen-II and aggrecan. However, the inhibitory effect of DHP was obvious abolished by selisistat, suggesting that DHP exerts these effects in NP cells through activating sirt1. Taken together, we found that DHP inhibited the ROS, inflammatory response and ECM degradation through activating Sirt1 in human NP cells.