Osteoarthritis (OA), primarily characterized by articular cartilage destruction, is the most common form of age-related degenerative whole-joint disease. No disease-modifying treatments for OA are currently available. Although OA is primarily characterized by cartilage destruction, our understanding of the processes controlling OA progression is poor. Here, we report the association of OA with increased levels of osteoclast-associated receptor (OSCAR), an immunoglobulin-like collagen-recognition receptor. In mice, OSCAR deletion abrogates OA manifestations, such as articular cartilage destruction, subchondral bone sclerosis, and hyaline cartilage loss. These effects are a result of decreased chondrocyte apoptosis, which is caused by the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in induced OA. Treatments with human OSCAR-Fc fusion protein attenuates OA pathogenesis caused by experimental OA. Thus, this work highlights the function of OSCAR as a catabolic regulator of OA pathogenesis, indicating that OSCAR blockade is a potential therapy for OA.

Cinchonine (CN) has been known to exert antimalarial, antiplatelet, and antiobesity effects. It was also recently reported to inhibit transforming growth factor βactivated kinase 1 (TAK1) and protein kinase B (AKT) through binding to tumor necrosis factor receptor-associated factor 6 (TRAF6). However, its role in bone metabolism remains largely unknown. Here, we showed that CN inhibits osteoclast differentiation with decreased expression of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), a key determinant of osteoclastogenesis. Immunoblot and quantitative real-time polymerase chain reaction analysis as well as the reporter assay revealed that CN inhibits nuclear factor-κB and activator protein-1 by regulating TAK1. CN also attenuated the activation of AKT, cyclic AMP response element-binding protein, and peroxisome proliferator-activated receptor-γ coactivator 1β (PGC1β), an essential regulator of mitochondrial biogenesis. Collectively, these results suggested that CN may inhibit TRAF6-mediated TAK1 and AKT activation, which leads to downregulation of NFATc1 and PGC1β resulting in the suppression of osteoclast differentiation. Interestingly, CN not only inhibited the maturation and resorption function of differentiated osteoclasts but also promoted osteoblast differentiation. Furthermore, CN protected lipopolysaccharide-and ovariectomy-induced bone destruction in mouse models, suggesting its therapeutic potential for treating inflammation-induced bone diseases and postmenopausal osteoporosis.

Excessive osteoclast activity can lead to an imbalance between the synthesis and breakdown of bone, with pathologic consequences that include osteoporosis and periodontitis. Thus, controlling osteoclast differentiation and function has significant therapeutic implications. In this study, we investigated the effects of dehydrocostus lactone (DL) on osteoclast differentiation and activation and elucidated the possible mechanisms underlying these processes. DL suppressed osteoclast differentiation by reducing the expression of the nuclear factor of activated T‐cells, cytoplasmic 1. When used to challenge differentiated osteoclasts, DL also effectively inhibited their enlargement and resorption activity, and biochemical approaches revealed that DL attenuates osteoclast activation by inhibiting the migration and lysosome biogenesis and secretion via the down‐regulation of integrin β3, PKC‐β, and autophagy related 5 expression. Furthermore, DL prevented bone destruction in inflammation‐ and ovariectomy‐induced osteolytic mouse models. These results indicate that DL has therapeutic potential to treat bone diseases caused by excessive or hyperactive osteoclasts.—Lee, H. I., Lee, J., Hwang, D., Lee, G.‐R., Kim, N., Kwon, M., Lee, H., Piao, D., Kim, H. J., Kim, N. Y., Kim, H. S., Seo, E. K., Kang, D., Jeong, W. Dehydrocostus lactone suppresses osteoclast differentiation by regulating NFATc1 and inhibits osteoclast activation through modulating migration and lysosome function. FASEB J. 33, 9685–9694 (2019). http://www.fasebj.org

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Acne is a common inflammatory disorder of the human skin and a multifactorial disease caused by the sebaceous gland and Propionibacterium acnes (P. acnes). This study aimed to evaluate the anti-inflammatory effect of micro-current stimulation (MC) on peptidoglycan (PGN)-treated raw 264.7 macrophages and P. acnes-induced skin inflammation. To specify the intensity with anti-inflammatory effects, nitric oxide (NO) production was compared according to various levels of MC. As the lowest NO production was shown at an intensity of 50 μA, subsequent experiments used this intensity. The changes of expression of the proteins related to TLR2/NF-κB signaling were examined by immunoblotting. Also, immunofluorescence analysis was performed for observing NF-κB p65 localization. All of the expression levels of proteins regarding TLR2/NF−κB signaling were decreased by the application of MC. Moreover, the application of MC to PGN−treated raw 264.7 cells showed a significant decrease in the amount of nuclear p65−protein. In the case of animal models with P. acnes−induced skin inflammation, various pro−inflammatory cytokines and mediators significantly decreased in MC−applied mice. In particular, the concentration of IL−1β in serum decreased, and the area of acne lesions, decreased from the histological analysis. We suggest for the first time that MC can be a novel treatment for acne.