Melatonin Suppresses Ferroptosis Induced by High Glucose via Activation of the Nrf2/HO-1 Signaling Pathway in Type 2 Diabetic Osteoporosis

Abstract

Ferroptosis is recently identified, an iron- and reactive oxygen species- (ROS-) dependent form of regulated cell death. This study was designed to determine the existence of ferroptosis in the pathogenesis of type 2 diabetic osteoporosis and confirm that melatonin can inhibit the ferroptosis of osteoblasts through activating Nrf2/HO-1 signaling pathway to improve bone microstructure in vivo and in vitro. We treated MC3T3-E1 cells with different concentrations of melatonin (1, 10, or 100 μM) and exposed them to high glucose (25.5 mM) for 48 h in vitro. Our data showed that high glucose can induce osteoblast cytotoxicity and the accumulation of lipid peroxide, the mitochondria of osteoblast show the same morphology changes as the erastin treatment group, and the expression of ferroptosis-related proteins glutathione peroxidase 4 (GPX4) and cystine-glutamate antiporter (SLC7A11) is downregulated, but these effects were reversed by ferroptosis inhibitor ferrastatin-1 and iron chelator deferoxamine (DFO). Furthermore, western blot and real-time polymerase chain reaction were used to detect the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1); osteogenic capacity was evaluated by alizarin red S staining and the expression of osteoprotegerin, osteocalcin, and alkaline phosphatase; the results showed that the expression levels of these proteins in osteoblasts with 1, 10, or 100 μM melatonins were significantly higher than the high glucose group, but after using Nrf2-SiRNA interference, the therapeutic effect of melatonin was significantly inhibited. We also performed in vivo experiments in a diabetic rat model treated with two concentrations of melatonin (10, 50 mg/kg). Dynamic bone histomorphometry and micro-CT were used to observe the rat bone microstructure, and the expression of GPX4 and Nrf2 was determined by immunohistochemistry. Here, we first report that high glucose induces ferroptosis via increased ROS/lipid peroxidation/glutathione depletion in type 2 diabetic osteoporosis. More importantly, melatonin significantly reduced the level of ferroptosis and improved the osteogenic capacity of MC3T3-E1 through activating the Nrf2/HO-1 pathway in vivo and in vitro.

Role of Ferroptosis in Lung Diseases

“…Previous studies have proven that ferroptosis plays an essential role in the occurrence and progression of various pathological processes and diseases, including intracerebral haemorrhage, 9 ischaemic stroke, 70 sepsis, 71 cancer, 72 and myocardial infarction. 73 More recently, several studies have indicated that ferroptosis is a potential therapeutic target for various lung diseases, such as acute lung injury, chronic obstructive pulmonary disease, pulmonary fibrosis, pulmonary infection and asthma ( Table 1 ).…”

“…[2][3][4][5] Recently, numerous studies have shown that ferroptosis can be inhibited by iron chelators, 6 lipid peroxidation inhibitors, 7 and lipophilic antioxidants 8 and can be tightly regulated by several signalling pathways, such as the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signalling pathway. 9 Therefore, ferroptosis is characterized by the perturbation of intricate metabolic networks and signalling pathways, which we will describe in detail in the following sections.…”

Kaempferol Ameliorates Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Ferroptosis by Activating Nrf2/SLC7A11/GPX4 Axis

“…Nuclear factor-E2-related factor 2 Biomolecules 2021, 11, 923 2 of 14 (Nrf2) is a key transcription factor that controls cellular redox homeostasis and inflammation. Activation of Nrf2 signaling also protects cells against ferroptosis in many chronic diseases [10,11]. In addition, Nrf2 acts as a transcription factor increasing the expression of SLC7A11 and GPX4 [8,10,11].…”

Heme Oxygenase-1 Signaling and Redox Homeostasis in Physiopathological Conditions

“…Indeed, Adedoyin et al, showed HO-1-deficient renal cells are highly sensitive to erastin- and RSL3-induced ferroptosis [ 77 ]. Furthermore, melatonin significantly reduced ferroptosis and improved osteogenesis via the Nrf2/HO-1 pathway [ 97 ] and, additionally, Li and colleagues assessed that selective inhibition of Keap1-Nrf2/HO-1 pathway significantly abolished the anti-ferroptotic functions of panaxydol in lipopolysaccharide-treated cells [ 98 ].…”