Paeonol reduces IL-1β induced apoptosis and degeneration by regulating MAPK pathway in nucleus pulposus cells

Our study sought to examine paeonol's effects and possible regulatory mechanism in intervertebral disc degeneration (IDD).

In human nucleus pulposus (NP) cells, interleukin-1β (IL-1β) was used to construct IDD cell model. Cell viability, senescence, and apoptosis were checked utilizing cell counting kit-8 assay, β-galactosidase staining, and flow cytometry. The related indicators of cell senescence (cyclin dependent kinase inhibitor 2A, p16INK4a), apoptosis [Bcl-2-associated X protein (Bax) and cleaved caspase-3 (C-caspase-3)], inflammation [interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2)], extracellular matrix (ECM) degradation [(Collagen II, matrix metallopeptidase 13 (MMP13), and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5)], and mitogen-activated protein kinase (MAPK) pathway (p38 and p-p38) were examined by reverse transcription-quantitative polymerase chain reaction, Western blot, or immunofluorescence staining. The possible molecular mechanism of paeonol was explored via network pharmacology analysis.

Under IL-1β treatment, paeonol enhanced NP cell viability, inhibited cell senescence and apoptosis, impeded inflammation and ECM degradation. Furthermore, paeonol reduced the levels of p16INK4a, Bax, C-caspase-3, IL-6, iNOS, COX-2, MMP13, and ADAMTS5 and increased Collagen II levels. Network and pharmacology analysis revealed that paeonol was associated with MAPK signaling pathway and there was a binding between paeonol and MAPK14 (also known as p38). The levels of p38 and p-p38 were decreased by paeonol. In addition, paeonol's promotion on NP cell viability and inhibition on NP cell apoptosis, inflammation, and ECM degradation were reversed by p38 overexpression.

Paeonol exerted a protective role on alleviating IDD by attenuating NP cell apoptosis, inflammation, and ECM degradation through the inhibition of MAPK signaling pathway.