Sauchinone inhibits IL-1β induced catabolism and hypertrophy in mouse chondrocytes to attenuate osteoarthritis via Nrf2/HO-1 and NF-κB pathways.

Osteoarthritis (OA) is a common degenerative joint disease for which currently no anti-inflammatory therapy is available. Sauchinone (SAU), a key bioactive compound derived from Saururus chinensis, which has shown remarkable anti-inflammatory effects. To evaluate the effect of SAU on OA progression, mouse chondrocytes were pretreated with SAU and subsequently stimulated with interleukin (IL)-1β. We found that SAU reduced the production of pro-inflammatory cytokines, such as nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α), and IL-6. SAU also inhibited the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) at both the gene and protein level. Moreover, SAU promoted the expression of aggrecan, while inhibiting the expression of catabolic factors, such as matrix metalloproteinases (MMPs) and thrombospondin motifs 5 (ADAMTS-5) in mouse chondrocytes. Col X, vascular endothelial growth factor-A (VEGF)-A, and Runx2, major markers of hypertrophic chondrocytes, were markedly elevated following IL-1β stimulation, and were reduced by SAU treatment while having the opposite effect on Col II. Mechanistically, we found that SAU inhibited nuclear factor kappa B (NF-κB) and activated the Nrf2/HO-1 pathway. The beneficial effects of SAU were also observed in vivo using a mouse OA model. Our findings indicate that SAU may be a potential novel therapeutic for the treatment of OA.

Wu D ，Jin S ，Lin Z ，Chen R ，Pan T ，Kang X ，Huang H ，Lin C ，Pan J ... -  《-》

Sinomenine contributes to the inhibition of the inflammatory response and the improvement of osteoarthritis in mouse-cartilage cells by acting on the Nrf2/HO-1 and NF-κB signaling pathways.

Pathological changes, such as articular cartilage degeneration, destruction, and hyperosteogeny, are regarded as the main features of osteoarthritis (OA). Sinomenine (SIN) is a monomeric component purified from the plant Sinomenium acutum which has been found to have anti-inflammatory effects, however, the mechanism of action of SIN on OA is not clear. In this study, we evaluated whether SIN could regulate the inflammatory response induced by interleukin (IL)-1β and improve outcomes in the instability model of OA (medial meniscus mice (DMM)) by acting on the Nrf2/HO-1 and NF-κ B signaling pathways in chondrocytes. From our experiments, which include Griess reaction, ELISA, Western blot, and immunofluorescence, we found that SIN not only down-regulated the expression of pro-inflammatory factors induced by IL-1β, including; inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nitricoxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), but also decreased the production of IL-1β-induced cartilage matrix catabolic enzymes including; ADAMTS-5 and MMPs, in mouse chondrocytes. In addition, the degradation of aggrecan and type II collagen protein in the extracellular matrix (ECM) stimulated by IL-1β was reversed. Most importantly, we have revealed for the first time that in OA, SIN inhibited the inflammatory response and ECM degradation by activating the Nrf2/HO-1 signaling pathways and inhibiting NF-κB activity in mouse-cartilage cells. In in vivo experiments, SIN treatment helped to improve the cartilage destruction in OA model mice. In conclusion, this study has demonstrated that SIN inhibits the IL-1β-induced inflammatory response and cartilage destruction by activating the Nrf2/HO-1 signaling pathway and inhibiting the NF-κB signaling pathway in mouse chondrocytes, suggesting a new use for SIN in the treatment of OA.

Wu Y ，Lin Z ，Yan Z ，Wang Z ，Fu X ，Yu K ... -  《-》

Activation of Nrf2/HO-1 signal with Myricetin for attenuating ECM degradation in human chondrocytes and ameliorating the murine osteoarthritis.

Osteoarthritis (OA), one of the prevailing joint degenerative disorders, contributes to the disability around the world. However, no effective therapeutic was introduced currently. Myricetin was reported to possess the function of anti-inflammatory, anti-diabetic and anti-cancer. Thus, we investigate the protection role of myricetin in OA progression and the potential molecular mechanism in present study. Quantitative realtime PCR and western blotting were performed to evaluate the expression of MMP-13, Aggrecan, iNOS, and COX-2 at both gene and protein levels. An enzyme-linked immunosorbent assay was used to evaluate the levels of inflammatory factors (PGE2, TNF-α, and IL-6). The PI3K/AKT, Nrf2/HO-1 and nuclear factor kappa B (NF-κB) signaling pathways were analyzed by western blotting, and immunofluorescence was used to assess the expression of Nrf2, Collagen II and MMP13. The in vitro effect of myricetin was evaluated by intragastric administration into a mouse osteoarthritis model induced by destabilization of the medial meniscus. Myricetin not only inhibited the generation of inflammatory mediators and cytokines such as nitric oxide (NO), prostaglandin E2 (PGE2), TNF-α and IL-6, but also suppressed the production of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in human chondrocytes under IL-1β stimulation. Moreover, Metalloproteinase 13 (MMP13) and thrombospondin motifs 5 (ADAMTS5), which resulted in the degradation of cartilage, were also suppressed in chondrocytes with the treatment of myricetin. To explore the potential mechanism, we found out that myricetin suppressed NF-κB signaling pathway through Nrf2/HO-1 axis in human chondrocytes. Besides, myricetin regulated the Nrf2 signaling pathway through PI3K/Akt pathway. In addition, in vivo study demonstrated that myricetin could ameliorated the progression of OA in mice DMM model through PI3K/Akt mediated Nrf2 signaling pathway. Taken together, our data first demonstrated that myricetin possesses the therapeutic potential on OA through PI3K/Akt mediated Nrf2/HO-1 signaling pathway.

Pan X ，Chen T ，Zhang Z ，Chen X ，Chen C ，Chen L ，Wang X ，Ying X ... -  《-》

Eriodictyol inhibits IL-1β-induced inflammatory response in human osteoarthritis chondrocytes.

Osteoarthritis (OA) is a degenerative disease of joints, which is closely associated with cartilage degradation. Eriodictyol, a natural flavonoid compound, has been reported to have anti-inflammatory and anti-osteoclastogenic effects. However, the effect of eriodictyol on inflammatory response in OA has not been investigated. Our results showed that eriodictyol attenuated the inhibition of cell viability in IL-1β-stimulated chondrocytes. In addition, eriodictyol inhibited the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the production of prostaglandin E2 (PGE2) and nitric oxide (NO), which were induced by IL-1β. The induction of inflammatory cytokines and matrix metalloproteinases (MMPs) caused by IL-1β stimulation was also attenuated by eriodictyol. Furthermore, eriodictyol pretreatment inhibited IκBα degradation and the level of p-p65, and enhanced the up-regulation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase 1 (HO-1) in IL-1β-stimulated chondrocytes. Si-Nrf2 treatment significantly inhibited the expressions of Nrf2 and HO-1 in chondrocytes. Additionally, si-Nrf2 transfection also abolished the anti-inflammatory effects of eriodictyol in chondrocytes. These findings indicated that eriodictyol exhibited anti-inflammatory effect in IL-1β-stimulated chondrocytes. The effect was mediated by inhibiting NF-κB via activating the Nrf2/HO-1 signaling pathway.

Wang Y ，Chen Y ，Chen Y ，Zhou B ，Shan X ，Yang G ... -  《-》

Polydatin inhibits the IL-1β-induced inflammatory response in human osteoarthritic chondrocytes by activating the Nrf2 signaling pathway and ameliorates murine osteoarthritis.

Tang S ，Tang Q ，Jin J ，Zheng G ，Xu J ，Huang W ，Li X ，Shang P ，Liu H ... -  《-》