The Novel p38 Inhibitor, Pamapimod, Inhibits Osteoclastogenesis and Counteracts Estrogen-Dependent Bone Loss in Mice

Prussian Blue Nanozyme Normalizes Microenvironment to Delay Osteoporosis

Osteoporosis (OP) is the most common orthopedic disease in the elderly and the main cause of age-related mortality and disability. However, no satisfactory intervention is currently available in clinical practice. Thus, an effective therapy to prevent or delay the development of OP should be devised. Osteoclastogenesis overactivation and excessive bone resorption are the main characteristics of OP. Accordingly, a paradigm for nanozyme-mediated normalization of the disease microenvironment to regulate osteoclast differentiation and delay OP is proposed. Hollow Prussian blue nanozymes (HPBZs) are prepared via template-free hydrothermal synthesis and selected as representative nanozymes. The intrinsic osteoclast activity-remodeling bioactivities of the HPBZs are explored in vitro and in vivo, focusing on their impact on osteogenesis and specific molecular mechanisms using an OP murine model. The HPBZs significantly normalize the OP microenvironment, thereby inhibiting osteoclast formation and osteoclast resorption, possibly owing to the suppression of intracellular reactive oxygen species generation, the mitogen-activated protein kinase, and nuclear factor κB signaling pathways. Consistently, in an ovariectomy-induced OP murine model, HPBZ treatment significantly attenuates osteoporotic bone loss in vivo. The findings confirm the HPBZ-mediated normalization of the disease microenvironment for the treatment of OP and suggest its application to other inflammation-related diseases.

GSK 650394 Inhibits Osteoclasts Differentiation and Prevents Bone Loss via Promoting the Activities of Antioxidant Enzymes In Vitro and In Vivo

Osteoporosis (OP) is one of the most common bone disorders among the elderly, characterized by abnormally elevated bone resorption caused by formation and activation of osteoblast (OC). Excessive reactive oxygen species (ROS) accumulation might contribute to the formation process of OC as an essential role. Although accumulated advanced treatment target on OP have been proposed in recent years, clinical outcomes remain unexcellence attributed to severe side effects. The purpose of present study was to explore the underlying mechanisms of GSK 650394 (GSK) on inhibiting formation and activation of OC and bone resorption in vitro and in vivo. GSK could inhibit receptor activator of nuclear-κB ligand (RANKL-)-mediated Oc formation via suppressing the activation of NF-κB and MAPK signaling pathways, regulating intracellular redox status, and downregulate the expression of nuclear factor of activated T cells c1 (NFATc1). In addition, quantitative RT-PCR results show that GSK could suppress the expression of OC marker gene and antioxidant enzyme genes. Consistent with in vitro cellular results, GSK treatment improved bone density in the mouse with ovariectomized-induced bone loss according to the results of CT parameters, HE staining, and Trap staining. Furthermore, GSK treatment could enhance the capacity of antioxidant enzymes in vivo. In conclusion, this study suggested that GSK could suppress the activation of osteoclasts and therefore maybe a potential therapeutic reagent for osteoclast activation-related osteoporosis.