Gamma-oryzanol alleviates osteoarthritis development by targeting Keap1-Nrf2 binding to interfere with chondrocyte ferroptosis.

Osteoarthritis (OA) is a prevalent joint disorder pathologically correlated to chondrocyte ferroptosis. Gamma-oryzanol (γ-Ory), as a first-line drug for autonomic disorders, aroused our interest because of its antioxidant, lipid-lowering, and hypoglycemic potential. The purpose of this study was to investigate the potential impact and mechanism of γ-Ory in treating OA. And the inhibition of γ-Ory in extracellular matrix molecule (ECM) degradation, ferroptosis, and Keap1-Nrf2 binding in IL-1ß-exposed chondrocytes was detected via immunoblotting, immunofluorescence, and co-immunoprecipitation. Micro-CT, SO staining, and immunofluorescence have been conducted to assess the impact of γ-Ory treatment on ACLT-mediated OA in rats at both imaging and histological stages. We found that γ-Ory dose-dependently suppressed IL-1ß-induced ECM deterioration and chondrocyte ferroptosis. Our animal experiments revealed that γ-Ory delayed ACLT-mediated OA development. Mechanistically, γ-Ory interfered with the binding of Keap1 to Nrf2 to promote the latter's nuclear import, thereby increasing the expression of detoxification enzymes. Summarily, our works support γ-Ory's potential as a candidate drug for the treatment of OA.

Poliumoside protects against type 2 diabetes-related osteoporosis by suppressing ferroptosis via activation of the Nrf2/GPX4 pathway.

BACKGROUND: Type 2 diabetes is often linked with osteoporosis (T2DOP), a condition that accelerates bone degeneration and increases the risk of fractures. Unlike conventional menopausal osteoporosis, the diabetic milieu exacerbates the likelihood of fractures and osteonecrosis. In particular poliumoside (Pol), derived from Callicarpa kwangtungensis Chun, has shown promising anti-oxidant and anti-inflammatory effects. Yet, its influence on T2DOP remains to be elucidated. PURPOSE: The focus of this study was to elucidate the influence of Pol in HGHF-associated ferroptosis and its implications in T2DOP. STUDY DESIGN: A murine model of T2DOP was established using a minimal dosage of streptozotocin (STZ) through intraperitoneal infusion combined with a diet high in fat and sugar. Concurrently, to mimic the diabetic condition in a lab environment, bone mesenchymal stem cells (BMSCs) were maintained in a high-glucose and high-fat (HGHF) setting. METHODS: The impact of Pol on BMSCs in an HGHF setting was determined using methods, such as BODIPY-C11, FerroOrange staining, mitochondrial functionality evaluations, and Western blot methodologies, coupled with immunoblotting and immunofluorescence techniques. To understand the role of Pol in a murine T2DOP model, techniques including micro-CT, hematoxylin and eosin (H&E) staining, dual-labeling with calcein-alizarin red, and immunohistochemistry were employed for detailed imaging and histological insights. RESULTS: Our findings suggest that Pol acts against HGHF-induced bone degradation and ferroptosis, as evidenced by an elevation in glutathione (GSH) and a decline in malondialdehyde (MDA) levels, lipid peroxidation, and mitochondrial reactive oxygen species (ROS). Furthermore, Pol treatment led to increased bone density, enhanced GPX4 markers, and reduced ROS in the distal femur region. On investigating the underlying mechanism of action, it was observed that Pol triggers the Nrf2/GPX4 pathway, and the introduction of lentivirus-Nrf2 negates the beneficial effects of Pol in HGHF-treated BMSCs. CONCLUSION: Pol is effective in treating T2DOP by activating the Nrf2/GPX4 signaling pathway to inhibit ferroptosis.

Cinnamaldehyde Alleviates Bone Loss by Targeting Oxidative Stress and Mitochondrial Damage via the Nrf2/HO-1 Pathway in BMSCs and Ovariectomized Mice.

Osteoporosis (OP) is typically brought on by disruption of bone homeostasis. Excessive oxidative stress and mitochondrial dysfunction are believed to be the primary mechanisms underlying this disorder. Therefore, in order to restore bone homeostasis effectively, targeted treatment of oxidative stress and mitochondrial dysfunction is necessary. Cinnamaldehyde (CIN), a small molecule that acts as an agonist for the nuclear factor erythroid 2-related factor (Nrf2), has been found to possess antiapoptotic, anti-inflammatory, and antioxidant properties. We found that CIN, while rescuing apoptosis, can also reduce the accumulation of reactive oxygen species (ROS) to improve mitochondrial dysfunction and thus restore the osteogenic differentiation potential of BMSCs disrupted by hydrogen peroxide (H2O2) exposure. The role of CIN was preliminarily considered to be a consequence of Nrf2/HO-1 axis activation. The ovariectomized mice model further demonstrated that CIN treatment ameliorated oxidative stress in vivo, partially reversing OVX-induced bone loss. This improvement was seen in the trabecular microarchitecture and bone biochemical indices. However, when ML385 was concurrently injected with CIN, the positive effects of CIN were largely blocked. In conclusion, this study sheds light on the intrinsic mechanisms by which CIN regulates BMSCs and highlights the potential therapeutic applications of these findings in the treatment of osteoporosis.