Linalool inhibits the progression of osteoarthritis via the Nrf2/HO-1 signal pathway both in vitro and in vivo

Osteoarthritis (OA) is a chronic injury of joints, which is characterized by the destruction and degeneration of articular cartilage. Currently, there is a lack of effective treatments for OA. Linalool is a natural compound with anti-inflammatory effects in various diseases. However, the anti-inflammatory effect of linalool in the development of osteoarthritis remains unclear. This study aimed to investigate the anti-inflammatory effect of linalool on IL-1β-induced mouse chondrocytes, as well as its protective effect on joints in a mouse model of OA. Mouse chondrocytes were co-treated with 10 ng/mL IL-1β and different concentration gradients of linalool. These in vitro experiments demonstrated that linalool could inhibit the expression of Interleukin-1β (IL-1β)-induced inflammatory factors, such as nitric oxide synthase, cyclooxygenase-2 (COX-2), nitric oxide (NO), prostaglandin E2 (PGE2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Furthermore, linalool reduced the catabolism of the extracellular matrix (ECM) by inhibiting the expression of matrix metalloproteinase-13 (MMP-13) and thrombospondin motif-5 (ADAMTS5) while upregulating the expression of type II collagen (COL II) and aggrecan. Regarding the mechanism of OA, it was observed that linalool inhibited the signal transduction of nuclear factor kappa B (NF-κB) by activating the nuclear factor-erythroid 2-related factor-2 (Nrf2) in chondrocytes. The inhibitory effect of linalool on the development of OA was demonstrated by the mouse DMM model experiment. The results suggested that linalool may be a potential drug for the treatment of OA.