Apocynin exerts cytoprotective effects on dexamethasone-induced osteoblasts by inhibiting oxidative stress through the Nrf2 signalling pathway.

Steroid-induced femoral head necrosis (SIFHN) is a serious clinical complication that is caused by prolonged or excessive use of glucocorticoids (GCs). Osteoblast apoptosis and osteogenic differentiation dysfunction caused by GC-induced oxidative stress and mitochondrial impairment are strongly implicated in SIFHN. Apocynin (APO) is a kind of acetophenone extracted from an herb. In recent years, APO has received much attention for its antiapoptotic and antioxidant properties. This study aimed to investigate whether APO could protect against SIFHN and explore the mechanism. In our study, low-dose APO had no toxic effects on osteoblasts and restored dexamethasone (Dex)-treated osteoblasts by improving survival, inhibiting OS and restoring mitochondrial dysfunction. Mechanistically, APO alleviated Dex-induced osteoblast injury by activating the Nrf2 pathway, and the use of ML385 to block Nrf2 significantly eliminated the protective effect of APO. In addition, APO could reduce the formation of empty lacunae, restore bone mass and promote the expression of Nrf2 in SIFHN rats. In conclusion, APO protects osteoblasts from Dex-induced oxidative stress and mitochondrial dysfunction through activation of the Nrf2 pathway and may be a beneficial drug for the treatment of SIFHN.

Oxidative Stress Induced Osteocyte Apoptosis in Steroid-Induced Femoral Head Necrosis.

OBJECTIVE: To investigate the effect and mechanism of Glucocorticoids (GCs) induced oxidative stress and apoptosis on necrosis of the femoral head in patients and rats. METHODS: Eight patients with steroid-induced avascular necrosis of the femoral head (SINFH) and eight patients with developmental dysplasia of the hips (DDH) were enrolled in our study. In animal model, twenty male Sprague-Dawley rats were randomly divided into two groups (SINFH group and NS group). The SINFH model group received the methylprednisolone (MPS) injection, while control group was injected with normal saline (NS). MRI was used to confirm SINFH rat model was established successfully. Then, the rats were sacrificed 4 weeks later and femoral head samples were harvested. Histopathological staining was preformed to evaluate osteonecrosis. TUNEL staining was performed with 8-OHdG and DAPI immunofluorescence staining to evaluate oxidative injury and osteocyte apoptosis. Immunohistochemistry staining was used to detect Nox1, Nox2, and Nox4 protein expression. RESULTS: MRI showed signs of typical osteonecrosis of femoral head in SIHFH patients. Histopathological staining showed that the rate of empty lacunae in SINFH patients was significantly higher (56.88% ± 9.72% vs 19.92% ± 4.18%, T = -11.04, P < 0.001) than that in DDH patients. The immunofluorescence staining indicated that the TUNEL-positive cell and 8-OHdG-positve cell in SINFH patients were significantly higher (49.32% ± 12.95% vs 8.00% ± 2.11%, T = -7.04, P = 0.002, 54.6% ± 23.8% vs 9.75% ± 3.31%, T = -4.17, P = 0.003) compared to the DDH patients. The immunohistochemistry staining showed that the protein expression of NOX1, NOX2 and NOX4 in SINFH patients were significantly increased (64.50% ± 7.57% vs 37.58% ± 9.23%, T = -3.88, P = 0.018, 90.84% ± 2.93% vs 49.56% ± 16.47%, T = -5.46, P = 0.001, 85.46% ± 9.3% vs 40.69% ± 6.77%, T = -8.03, P = 0.001) compared to the DDH patients. In animal model, MRI showed signs of edema of femoral head in MPS group, which represents SINFH rat model was established successfully. Histological evaluation showed the rate of empty lacunae in MPS group was significantly higher (25.85% ± 4.68% vs 9.35% ± 1.99%, T = -7.96, P < 0.001) than that in NS group. The immunofluorescence staining indicated that the TUNEL-positive cell and 8-OHdG-positve cell (in MPS group were significantly increased (31.93% ± 1.01% vs 11.73% ± 1.16%, T = -32.26, P < 0.001, 47.59% ± 1.39% vs 22.07% ± 2.45%, T = -22.18, P < 0.001) compared to the NS group. The immunohistochemistry staining showed that the expression of NOX2 in MPS group was significantly increased (76.77% ± 8.34% vs 50.32% ± 10.84%, T = -4.74, P = 0.001) compare with NS group. CONCLUSION: Our findings indicated that GC-induced NOXs expression may be an important source of oxidative stress, which could lead to osteocyte apoptosis in the process of SINFH.

NADPH Oxidase Isoforms Are Involved in Glucocorticoid-Induced Preosteoblast Apoptosis.

Oxidative stress induced by long-term glucocorticoid (GC) use weakens the repair capacity of bone tissue. Nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase (NOX) is a superoxide-generating enzyme that plays an important role in regulating bone metabolism. To clarify the role of nonphagocytic NOX isoforms in osteoblast reactive oxygen species (ROS) generation and apoptosis, dexamethasone was used to establish a high-dose GC environment in vitro. A dose-dependent increase in intracellular ROS generation was demonstrated, which was accompanied by increased osteoblastic MC3T3-E1 cell apoptosis. Addition of the ROS inhibitor NAC (N-acetyl-L-cysteine) or NOX inhibitor DPI (diphenyleneiodonium) reversed this effect, indicating that NOX-derived ROS can induce osteoblast apoptosis under high-dose dexamethasone stimulation. NOX1, NOX2, and NOX4 are NOX homologs recently identified in bone tissue. To clarify the NOX isoforms that play a role in osteoblast ROS generation, Nox1, Nox2, and Nox4 mRNA expression and NOX2 and NOX4 protein expression were analyzed. Nox1 and Nox4 mRNA expression was elevated in a dose-dependent manner after culture in 100 nM, 250 nM, 500 nM, or 1000 nM dexamethasone, and the increased expression of NOX1 mRNA was more significant compared with NOX4 mRNA. Small interfering RNAs (siRNAs) were used to confirm the role of NOX1 and NOX4 in ROS generation. To clarify the signaling pathway in ROS-induced osteoblast apoptosis, mitogen-activated protein kinase (MAPK) signaling molecules were analyzed. Phosphorylated ASK1 and p38 levels were significantly higher in the 1000 nM dexamethasone group, which NAC or DPI markedly attenuated. However, the total mRNA and protein levels of ASK1 and p38 between the dexamethasone group and control were not significantly different. This is related to ROS regulating the posttranslational modification of ASK1 and p38 in MC3T3-E1 cell apoptosis. Altogether, NOX1- and NOX4-derived ROS plays a pivotal role in high-dose dexamethasone-induced preosteoblast apoptosis by increasing phosphorylated ASK1 and p38 and may be an important mechanism in steroid-induced avascular necrosis of the femoral head (SANFH).

Unburied versus buried wires for fixation of pediatric lateral condyle distal humeral fractures: A meta-analysis.

Open reduction and internal fixation with Kirschner (K) wires has been reported as an efficient and convenient technique for pediatric lateral condyle distal humeral fractures. However, no single study has been large enough to definitively determine whether the K-wires should be buried or unburied. Therefore, we performed a meta-analysis pooling the results from several clinical trials to compare the outcome of using buried versus unburied K-wires. Potential academic articles were identified from the Cochrane Library, Medline (1966-2017.3), PubMed (1966-2017.3), Embase (1980-2017.3), ScienceDirect (1985-2017.3), and other databases. Gray studies were identified from the references of included literature reports. RevMan 5.1 was used to analyze the pooling of data. Nonrandomized controlled trials were included in this meta-analysis. There was a significant difference in the duration of wires in situ (MD = -13.28, 95% confidence interval: -16.42 to -10.14, P < .00001). No significant differences were found regarding infection, superficial infection, total complications, delayed union, or reoperation. Unburied K-wire fixation for treatment of lateral condyle distal humeral fractures in children does not increase the total infection rate, superficial infection, reoperation rate, or complications. However, unburied K-wire fixation is of benefit for early extraction and impartial cost savings.

A 53-year-old man with a sclerosing rib lesion: A case report.

RATIONALE: Sclerosing osteomyelitis of Garré is a rare condition that occurs most commonly in tubular bones and the mandible. Its nontypical symptoms, low morbidity, and insidious process make its diagnosis difficult at an early stage. In this article, we reported a case of chronic sclerosing osteomyelitis which occurred in flat bone. PATIENT CONCERNS: A 53-year-old man was diagnosed with rib sclerosing osteomyelitis of Garré who had an 8-year course of intermittent local pain and swelling, which radiated toward the left side of his chest wall. Chest computed tomography (CT) showed irregular sclerosis of the diaphysis of the 10th rib, with periosteal reaction and narrowing of the medullary cavity, and magnetic resonance imaging (MRI) showed T2 heterogeneous low-signal intensity over the 10th rib. DIAGNOSES: Based on the features of the clinical signs and radiography and biopsy of the lesion, diagnosis of rib sclerosing osteomyelitis of Garré was made. INTERVENTIONS: The patient was treated with surgical excision of a 10-cm-long lesion after failed conservative treatment. OUTCOMES: Postoperatively, the patient achieved good functional recovery at the 10-year follow-up. LESSONS: Rib sclerosing osteomyelitis of Garré is an unusual condition and represents a noninfective course in the rib with a low morbidity. The surgical management was successful in relieving the patient's symptom.