Syringaresinol attenuates osteoarthritis via regulating the NF-κB pathway

Osteoarthritis (OA) is a now regarded as a worldwide whole joint disease with synovial inflammation, cartilage degeneration, and subchondral sclerosis. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used drugs for OA treatment which only relieve the symptoms and restrain the progression of OA. However, various severe adverse effects often occur in patients with long-term NSAIDs use, which heavily burdens the healthcare system and impacts the quality of life. Therefore, it is much imperative to identify alternative drugs with increased efficacy. Syringaresinol (Syr), a naturally occurring phytochemical which belonging to the lignan group of polyphenols, shows anti-tumor and anti-oxidant activities, which to benefit human health. Studies has shown Syr can regulate the inflammatory response by modulating the secretion and expression level of cytokines IL-6, IL-8, and tumor necrosis factor (TNF)-α. it also shows the inhibitory effect on NF-κB pathway in mouse cells. In the present study, we aimed to demonstrate the anti-inflammatory effects of Syr in OA. In vitro Syr treatment in IL-1β-activated mouse chondrocytes significantly restrained the expression of NO, PGE2, IL-6, TNF-α, INOS, COX-2 and MMP-13. Moreover, it considerably ameliorated the degradation of aggrecan and collagen II. Furthermore, the phosphorylation of the NF-kB signaling pathway was significantly suppressed by Syr. Moreover, in vivo, the cartilage degeneration was attenuated and the increased Osteoarthritis Research Society International (OARSI) scores were reversed in the DMM + Syr group, comprared to those in the DMM group. In sum, our study demonstrated that Syr can attenuate the inflammation in vitro and further verified its effect on OA in vivo. Thus, Syr might be a potent therapeautic alternative for OA treatment.