Paeonol is the bioactive component in Paeonia lactiflora Pall., Cynanchum paniculatum and Paeonia × suffruticosa Andr. Paeonol has been previously demonstrated to inhibit the release of tumor necrosis factor α (TNF-α) and interluekin 6 (IL-6) in chondrocytes. Sirtuin 1 (SIRT1) is downregulated in degraded cartilage and paeonol could induce nuclear accumulation of SIRT1. Therefore, the present study aims to investigate the possible role of paeonol in chondrocyte inflammation and cartilage protection in osteoarthritis (OA) as well as its regulation of SIRT1. Primary chondrocytes from rat knee joints were transfected with short hairpin (sh) – SIRT1 and (or) paeonol prior to IL-1β exposure, and then inflammatory response, apoptosis, and extracellular matrix (ECM) degradation in the cells were evaluated concurrent with the activation of the nuclear factor κβ (NF-κβ) signaling pathway. Increased levels of TNF-α, IL-17, IL-6, matrix metalloproteinase 1 (MMP-1), MMP-3, and MMP-13 along with decreased tissue inhibitor of metalloproteinases 1 and type II collagen levels were found in IL-1β-stimulated chondrocytes. Chondrocyte apoptosis was elevated and the NF-κβ signaling pathway was activated in response to IL-1β treatment. Paeonol enhanced SIRT1 expression to inactivate the NF-κβ signaling pathway, thereby ameliorating inflammatory cytokine secretion, ECM degradation, and chondrocyte apoptosis. In conclusion, the results of the present study confirm the potential of paeonol as a candidate OA drug.
Objective: To explore the possible role of paeonol on chondrocyte inflammation and cartilage protection in osteoarthritis (OA).Methods: Primary chondrocytes were isolated from rat stifle joints, and were identified through toluidine blue staining and immunofluorescence staining of type II collagen. The chondrocytes were transfected with sh-SIRT1 or/and paeonol (0, 20, 50, 100, 200, 1000 mg/L) before OA modeling induced by IL-1β. ELISA determined the expressions of TNF-α, IL-17 and IL-6, and apoptotic rate was examined by flow cytometry. qRT-PCR and Western blot quantified the expressions of MMP-1, MMP-3, MMP-13, TIMP-1, cleaved-caspase-3, Bax, Bcl-2, and the proteins related to NF-κB pathway.Results: Increases in TNF-α, IL-17, IL-6, MMP-1, MMP-3 and MMP-13 and decrease in TIMP-1 were found in IL-1β stimulated chondrocytes. The apoptotic rate as well as the expressions of cleaved-caspase-3 and Bax was up-regulated, and Bcl-2 expression was suppressed in response to IL-1β treatment. NF-κB pathway was activated in IL-1β-stimulated chondrocytes. Paeonol enhanced SIRT1 expression to inactivate NF-κB pathway, thus ameliorating the secretion of inflammatory cytokines, extracellular matrix degradation and chondrocyte apoptosis.Conclusion: Paeonol inhibits IL-1β induced inflammation and extracellular matrix degradation in chondrocytes through up-regulating SIRT1 and suppressing NF-κB pathway.
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