Schisandra extract ameliorates arthritis pathogenesis by suppressing the NF‐κB and MAPK signalling pathways

Schisandra chinensis is a medicinal plant used to treat various diseases. Extracts from the leaves or fruits of S. chinensis and their components are used in osteoarthritis (OA). The OA inhibitory effect of schisandrol A, one of its components, has been previously confirmed. We aimed to confirm the OA inhibitory effect of Schisandra (including components like schisandrol A) to identify why the inhibitory effect of the Schisandra extract is better. First, we investigated the effects of the Schisandra extract on OA as a potential therapeutic. Experimental OA was induced in a mouse model via destabilized medial meniscus surgery. The animals were orally administered the Schisandra extract; the inhibition of cartilage destruction was confirmed using histological analysis. In vitro analysis showed that the Schisandra extract attenuated osteoarthritic cartilage destruction by regulating IL‐1β‐induced MMP3 and COX‐2 levels. The Schisandra extract inhibited IL‐1β‐induced degradation of IκB (NF‐κB pathway) and IL‐1β‐induced phosphorylation of p38 and JNK (mitogen‐activated protein kinase (MAPK) pathway). RNA‐sequencing analysis showed that the Schisandra extract decreased the expression of IL‐1β‐induced MAPK and NF‐κB signalling pathway‐related genes more than schisandrol A alone. Therefore, Schisandra extract may be more effective than schisandrol A in preventing OA progression by regulating MAPK and NF‐κB signalling.