Alpha-Mangostin protects rat articular chondrocytes against IL-1β-induced inflammation and slows the progression of osteoarthritis in a rat model

Abstract

Osteoarthritis (OA) is a joint disease characterized by inflammation and cartilage degradation. α-Mangostin (α-MG), which can be isolated from the fruit of the tropical evergreen tree Garcinia mangostana-L, is known to have anti-inflammatory properties. The aim of the study was to investigate the use of α-MG in the treatment of OA, using both rat chondrocytes and an OA rat model induced by destabilization of the medial meniscus (DMM). Rat chondrocytes were pretreated with α-MG (0, 1.25, 2.5, and 5.0μg/ml for 24h) prior to stimulation with interleukin-1β (IL-1β) (10ng/ml for 24h). Nitric oxide (NO) production was determined using the Griess method and prostaglandin E₂ (PGE₂) was assessed using an enzyme-linked immunosorbent assay (ELISA). The expression of inducible nitric oxide synthase (INOS), cyclooxygenase-2 (COX-2), matrix metalloproteinase-3, -9, and -13 (MMP-3, MMP-9, and MMP-13), Collagen II, and Aggrecan were detected by both quantitative real-time PCR (qRT-PCR) and a western blot analysis. Nuclear factor-κB (NF-κB) signaling molecules were detected by western blot analysis. Detection of p65 nuclear translocation of NF-κB was examined using immunofluorescence staining. The OA rats received intraperitoneal injections of α-MG (10mg/kg) or saline every other day. Hematoxylin and eosin and Safranin-O-Fast green staining were used to evaluate the severity of cartilage lesions up to 8weeks following surgery. α-MG inhibited the production of NO and PGE₂. The elevated expression of INOS, COX-2, MMP-3, MMP-9, and MMP-13, and the degradation of Collagen II and Aggrecan, were reversed by α-MG in IL-1β-stimulated chondrocytes. In addition, IL-1β induced considerable phosphorylation of the NF-kB signaling pathway, which was inhibited by α-MG. Furthermore, the immunofluorescence staining demonstrated that α-MG could suppress IL-1β-induced p65 nuclear translocation. In vivo, cartilage treated with α-MG showed attenuated degeneration and had low Osteoarthritis Research Society International (OARSI) scores compared with the control group. Taken together, these results show that α-MG has potential therapeutic value in the treatment of OA.

Keywords: Alpha-Mangostin; Chondrocyte; Inflammation; Interleukin-1β; NF-κB; Osteoarthritis.