naphthoquinones and Osteoarthritis

Osteoarthritis (OA) is a chronic joint degenerative disease characterised by narrowed articular space, formation of surrounding osteophytes, and subchondral bone sclerosis. OA is caused by cartilage degeneration, which is closely correlated with the disequilibrium of anabolism and catabolism in chondrocytes. Previous studies have revealed that autophagy plays a significant role in maintaining the balance of anabolic and catabolic activities. Thus, targeting autophagy may be a promising therapeutic strategy for OA. Shikonin, a traditional Chinese herbal medicine isolated from flavonoid glucuronide, has drawn focus for its role in activating autophagy. In this study, the mRNA and protein level of a disintegrin and metalloproteinase with thrombospondin motifs-5 and matrix metalloproteinases-1 decreased with shikonin treatment, in the IL-1β-induced OA cell model. On the contrary, IL-1β-induced downregulation of Aggrecan and Collagen II was ameliorated following shikonin treatment. In addition, the upregulation of autophagy-related marker genes Beclin-1 and LC3II/LC3I in chondrocytes indicated that autophagy could be activated upon shikonin treatment. Moreover, shikonin's promotion of anabolism in chondrocytes through autophagy activation corresponded with the results from the examination using chloroquine, an autophagy inhibitor. OA mouse cartilage tissues were stained with safranin O and fast green dyes. Results were analysed using the Osteoarthritis Research Society International (OARSI) score, and suggested that mice cartilage degeneration was alleviated after shikonin treatment. Altogether, we identified that shikonin might be a novel promising drug for OA treatment.

Topics: Animals; Autophagy; Cartilage, Articular; Cells, Cultured; Chondrocytes; Interleukin-1beta; Mice; Naphthoquinones; Osteoarthritis

Topics: Cartilage, Articular; Cells, Cultured; Chondrocytes; Humans; Inflammation; Naphthoquinones; Osteoarthritis

Osteoarthritis is a chronic degenerative disease characterized by cartilage destruction. It is the fourth most disabling disease worldwide and is currently incurable. Inflammation and extracellular matrix (ECM) degradation are considered to be substantial reasons for accelerating the progression of OA. β-Hydroxyisoamylshikonin (β-HIVS) is a natural naphthoquinone compound with anti-inflammatory and antioxidant activity. However, the effect of β-HIVS on OA is still unclear. In this study, we found that β-HIVS can down-regulate the expression of NO, PEG2, IL-6, TNF-α, COX-2, and iNOS, suggesting its anti-inflammatory effects in chondrocytes; we also found that β-HIVS may down-regulate the expression of ADAMTS5 and MMP13 and up-regulate the expression of aggrecan and collagen II to inhibit the degradation of ECM. Mechanistically, β-HIVS inhibited the NFκB pathway by activating the Nrf2/HO-1 axis, thereby exerting its anti-inflammatory and inhibitory effects on ECM degradation. In vivo experiments also proved the therapeutic effects of β-HIVS on OA in mice, and Nrf2 is the target of β-HIVS. These findings indicate that β-HIVS may become a new drug for the treatment of OA.

Topics: Animals; Anti-Inflammatory Agents; Chondrocytes; Heme Oxygenase-1; Humans; Interleukin-1beta; Male; Matrix Metalloproteinase 13; Mice; Mice, Inbred C57BL; Naphthoquinones; NF-E2-Related Factor 2; NF-kappa B; Osteoarthritis

Inflammation and inflammatory cytokines have been reported to play vital roles in the development of osteoarthritis (OA). Plumbagin, a quinonoid compound extracted from the roots of medicinal herbs of the Plumbago genus, has been reported to have anti-inflammatory effects. However, the anti-inflammatory effects of plumbagin on OA have not been reported. This study aimed to assess the effects of plumbagin on human OA chondrocytes and in a mouse model of OA induced by destabilization of the medial meniscus (DMM). In vitro, human OA chondrocytes were pretreated with plumbagin (2, 5, 10 μM) for 2 h and subsequently stimulated with IL-1β for 24 h. Production of NO, PGE2, MMP-1, MMP-3, and MMP-13 was evaluated by the Griess reagent and ELISAs. The messenger RNA (mRNA) expression of COX-2, iNOS, MMP-1, MMP-3, MMP-13, aggrecan, and collagen-II was measured by real-time PCR. The protein expression of COX-2, iNOS, p65, p-p65, IκBα, and p-IκBα was detected by Western blot. The protein expression of collagen-II was evaluated by immunofluorescence. In vivo, the severity of OA was determined by histological analysis. We found that plumbagin significantly inhibited the IL-1β-induced production of NO and PGE2; expression of COX-2, iNOS, MMP-1, MMP-3, and MMP-13; and degradation of aggrecan and collagen-II. Furthermore, plumbagin dramatically suppressed IL-1β-stimulated NF-κB activation. In vivo, treatment of plumbagin not only prevented the destruction of cartilage and the thickening of subchondral bone but also relieved synovitis in mice OA models. Taken together, these results suggest that plumbagin may be a potential agent in the treatment of OA.

Topics: Adjuvants, Immunologic; Animals; Chondrocytes; Disease Progression; Humans; Inflammation; Interleukin-1beta; Mice; Naphthoquinones; NF-kappa B; Osteoarthritis; Signal Transduction

Osteoarthritis (OA) is an inflammatory disorder dealing with the focal degradation of articular cartilage. Oxidative stress and inflammation are the major events in OA. The present study aimed at identifying the mechanism of the potent antioxidant, plumbagin, in protecting against hydrogen peroxide (H2O2)‑induced chondrocyte oxidative stress and inflammatory signaling. Oxidative stress was determined by measuring reactive oxygen species, lipid peroxidation, non‑enzymic (glutathione; GSH) and enzymic antioxidant activities (GSH, glutathione S‑transferase, glutathione peroxidase, superoxide dismutase, catalase). Expression levels of nuclear factor (erythroid‑derived 2)‑like 2 (Nrf‑2), heme oxygenase 1 (HO‑1), NAD(P)H:quinone oxidoreductase 1 (NQO‑1), nuclear factor‑κB (NF‑κB), cyclooxygenase‑2 (COX‑2) and inducible NO synthase (iNOS) were determined by western blot analysis. Pro‑inflammatory cytokine expression levels were assessed using ELISA. Results from reactive oxygen species generation, lipid peroxidation content and antioxidant enzyme activities demonstrated that plumbagin significantly inhibited oxidative stress status in H2O2‑induced chondrocytes. In addition, plumbagin modulated transcription factors involved in redox and inflammation regulation, including NF‑κB and Nrf‑2, by nuclear expression. plumbagin enhanced antioxidant status by increasing the expression levels of Nrf‑2 target genes, including HO‑1 and NQO‑1. An anti‑inflammatory effect against chondrocyte‑induced inflammation was demonstrated by downregulating COX‑2, iNOS and pro‑inflammatory cytokine expression levels (tumor necrosis factor‑α, interleukin (IL)‑6 and IL‑8). The present study identified strong evidence for a protective role of plumbagin against H2O2-induced oxidative stress and inflammation in chondrocytes by modulating redox signaling transcription factors.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Cell Survival; Cells, Cultured; Chondrocytes; Humans; Hydrogen Peroxide; Naphthoquinones; NF-E2-Related Factor 2; NF-kappa B; Osteoarthritis; Oxidative Stress; Rats

Shikonin, a natural product from Lithospermum erythrorhizon, exerts a wide range of anti-inflammatory actions both in vitro and in vivo. Matrix metalloproteinases (MMPs) have long been considered as the major catabolic enzymes involved in osteoarthritis (OA) cartilage erosion. Here, we investigated the anti-inflammatory and effects of shikonin on MMPs in both IL-1β induced rabbit chondrocytes and the experimental rabbit OA model induced by anterior cruciate ligament (ACL) transection and evaluated the potential involvement of nuclear factor kappa B (NF-κB) in the processes. In vitro, rabbit chondrocytes were cultured and pretreated with shikonin (0, 1, 5, 10μM) for 1h (h) with or without IL-1β (10ng/ml) for 24h. The expression of MMPs (MMP-1, MMP-3 and MMP-13) and tissue inhibitors of metalloproteinase-1 (TIMP-1) at mRNA and protein levels were determined by quantitative real-time PCR and ELISA respectively. NF-κB related signaling molecules were investigated by Western blotting. In vivo study, the effects of shikonin on MMPs and TIMP-1 were determined at the gene level and the cartilage damage was evaluated at the histological level after the rabbits sacrificed. We found that shikonin significantly reversed the elevated expression of MMP-1, MMP-3 and MMP-13 and the reduced expression of TIMP-1 at both gene and protein levels in IL-1β induced chondrocytes. Additionally, the reduction of IκBα and the activation of NF-κB p65 induced by IL-1β were subsided by shikonin in rabbit chondrocytes. In vivo, both the cartilage damage and the elevated expression of MMP-1, MMP-3 and MMP-13 and the decreased expression of TIMP-1 were ameliorated in shikonin intra-articular injection knees compared to vehicle knees. Our findings indicated that shikonin have anti-inflammatory and chondro-protective effects and may be a potential therapeutic agent for the treatment of OA.

Topics: Animals; Cartilage; Cell Survival; Chondrocytes; Gene Expression Regulation; I-kappa B Kinase; Inflammation; Interleukin-1beta; Male; Matrix Metalloproteinases; Naphthoquinones; NF-kappa B; Osteoarthritis; Rabbits; Tissue Inhibitor of Metalloproteinase-1