Oxidative Stress Contributes to Hyperalgesia in Osteoporotic Mice.

PURPOSE: Chronic pain is one of the most common complications of postmenopausal osteoporosis. Since oxidative stress is involved in the pathogenesis of postmenopausal osteoporosis, we explored whether oxidative stress contributes to postmenopausal osteoporotic pain. METHODS: Osteoporosis was induced in mice by ovariectomy (OVX). Pain-related behaviours were assessed by measuring sensitivity to mechanical, thermal and cold stimulation. The expression of pain-related transcripts, such acid-sensing ion channel 3 (ASIC3), transient receptor potential vanilloid 1 (TRPV1) and calcitonin gene-related peptide (CGRP), was evaluated. Plasma markers of oxidative stress were also measured. In addition, the effects of the reactive oxygen species scavenger phenyl N-tert-butylnitrone (PBN) on these parameters were assessed. RESULTS: The OVX mice presented hyperalgesia, as demonstrated by decreased paw withdrawal thresholds to mechanical stimulation and withdrawal latencies to thermal and cold stimulation, along with upregulated expression of ASIC3, TRPV1 and CGRP in the dorsal root ganglia, spinal cord and thalamus tissue. OVX elevated the plasma levels of malondialdehyde (MDA) and advanced oxidation protein products (AOPPs). However, the administration of PBN alleviated these effects. CONCLUSION: Our results indicated that oxidative stress contributes to hyperalgesia in OVX mice. Enhanced oxidative stress may be associated with osteoporotic pain. Antioxidant treatment could help alleviate chronic pain in postmenopausal osteoporotic patients.

Expression and effects of leukemia inhibitory factor on nucleus pulposus degeneration.

Leukemia inhibitory factor (LIF) is a multifunctional cytokine. The present study aimed to determine the expression and effects of LIF on nucleus pulposus generation. Degenerated nucleus pulposus samples were obtained from animal models and patients with lumbar intervertebral disc herniation. Degradation scores of intervertebral discs were evaluated via magnetic resonance imaging (MRI) and histology, and the protein expression levels of LIF were detected. Furthermore, cultured primary human degenerated nucleus pulposus cells (DNPCs) were stimulated with various concentrations of recombinant human LIF protein (rhLIF), and aggrecan and collagen type II α1 (COL2α1) protein expression levels were detected by western blotting. In addition, aggrecan expression was determined by toluidine blue staining. The effects of rhLIF on proliferation and apoptosis of DNPCs were evaluated by Cell Counting Kit­8 and flow cytometry, respectively. The results revealed that the degradation scores of intervertebral discs were significantly associated with modeling time, as determined by MRI and histology. In addition, the protein expression levels of LIF were initially increased in patients with lumbar disc herniation and in rabbit models, particularly in the 2­week modeling group; however, its expression decreased with the progression of disc degeneration. Notably, LIF expression in each modeling group was higher than that in the control and 0 week modeling group. The in vitro study revealed that the protein expression levels of aggrecan and COL2α1 were significantly increased in response to rhLIF, in a dose­dependent manner, and statistical differences were identified between the treatment groups and control group. The results of toluidine blue staining were consistent with this finding. Although rhLIF had no effect on proliferation, it inhibited apoptosis of DNPCs in a concentration­dependent manner. In conclusion, LIF was upregulated during the process of intervertebral disc degeneration, and may promote the expression of extracellular matrix components. It may also be hypothesized that LIF acts as a potential protective factor by inhibiting apoptosis of DNPCs without affecting cell proliferation.

Solitary Fibrous Tumor of the Lumbar Spine Resembling Schwannoma: Case Report and Review of the Literature.

BACKGROUND: Solitary fibrous tumors (SFTs) are rare tumors derived from mesenchymal tissues. Notably, despite the widespread reports of SFT in various parts of the body, it is extremely rare in the spine, especially the lumbosacral spine, with only 4 previously reported cases. CASE PRESENTATION: A 40-year-old Chinese man had experienced low back and right leg pain for 11 years. Magnetic resonance imaging of the lumbar spine indicated a dumbbell-shaped mass at the right L4 vertebra. After the first surgical resection, the tumor was diagnosed as schwannoma pathologically. Three years later, he presented with low back pain, numbness in both legs, and defecation incontinence. Imaging examination suggested tumor recurrence. Pathologic examination of the second surgical specimen revealed features of SFT. So far, the patient has recovered well through the second extended resection and postoperative radiotherapy. CONCLUSION: To our knowledge, this is the fifth reported case of lumbar spine SFT, and its diagnosis is a difficult challenge. However, accurate diagnosis and complete resection of SFT in a patient suspected of having SFT could extend life or improve quality of life.

Lower cervical levels: Increased risk of early dysphonia following anterior cervical spine surgery.

OBJECTIVES: The present study aimed to re-evaluate the incidence of early dysphonia after anterior cervical spine surgery (ACSS) and to determine the related risk factors. CLINICAL MATERIALS AND METHODS: Patients underwent ACSS between January 2011 and December 2013 at two sites were identified retrospectively from hospital's patient databases. A total of 233 cases were included in this study. Dysphonia developed 1 month postoperatively was recorded. Follow-up was conducted in all positive-response patients. Those reporting severe or persistent voice symptoms were referred to otolaryngologists for further assessments and (or) treatments. Pre and intraoperative factors were collected to determine their relationships with dysphonia one month postoperatively. RESULTS: 45 patients developed dysphonia at one month, including 23 males and 22 females, yielding to an incidence of 19.3%. 34 cases resolved themselves in 3 months, leaving the remaining 11 patients considered to be severe or persistent cases. However, 10 of them recovered spontaneously in the next 9 months, while the last case received vocal cord medialization and returned to almost normal speech function at 18 months. In univariate analysis, only approaching level involving C6-C7 or (and) C7-T1 was significantly associated with postoperative dysphonia (P<0.001). This association was not weakened in multiple logistic regression analysis (OR 2.348, 95% CI 1.467-3.659, P<0.001). CONCLUSION: The incidence of early dysphonia following ACSS was relatively high and approaching at lower cervical levels was an independent predictive factor.

Does cervical disc arthroplasty have lower incidence of dysphagia than anterior cervical discectomy and fusion? A meta-analysis.

OBJECTIVE: Dysphagia is a common occurrence after anterior cervical spine surgery. The aim of this meta-analysis was to evaluate the incidence of dysphagia after ervical disc arthroplasty (CDA) compared with anterior cervical discectomy and fusion (ACDF). MATERIAL AND METHODS: The electronic databases, including PubMed, EMBASE and Cochrane Central Register of Controlled Trials, were searched to identify the randomized controlled trials comparing CDA with ACDF. Studies were included only if the incidence of postoperative dysphagia was investigated. Study selection, "risk of bias" assessment, and data extraction were independently performed by two investigators. Data analyses were conducted with RevMan 5.3 software. RESULTS: Ten studies involving 2711 patients (CDA group, n=1512; ACDF group, n=1199) were identified. All studies were determined to have a low risk of bias. Pooling analysis of these studies showed that the incidence of dysphagia was 9.46% (143/1512) after CDA versus 12.09% (145/1199) after ACDF. Meta-analysis showed the statistical difference between two groups with regards to the incidence of dysphagia (risk ratio 0.76; 95% confidence interval [0.61, 0.94]; P=0.01). CONCLUSION: This meta-analysis indicates that patients have a significantly lower incidence of dysphagia after CDA than after ACDF. Additional studies are needed.

Advanced oxidation protein products induce chondrocyte apoptosis via receptor for advanced glycation end products-mediated, redox-dependent intrinsic apoptosis pathway.

Pro-inflammatory cytokine-induced chondrocyte apoptosis is a primary cause of cartilage destruction in the progression of rheumatoid arthritis (RA). Advanced oxidation protein products (AOPPs), a novel pro-inflammatory mediator, have been confirmed to accumulate in patients with RA. However, the effect of AOPPs accumulation on chondrocyte apoptosis and the associated cellular mechanisms remains unclear. The present study demonstrated that the plasma formation of AOPPs was enhanced in RA rats compared with normal. Then, chondrocyte were treated with AOPPs-modified rat serum albumin (AOPPs-RSA) in vitro. Exposure of chondrocyte to AOPPs activated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and increased expression of NADPH oxidase subunits, which was mediated by receptor for advanced glycation end products (RAGE), but not scavenger receptor CD36. Moreover, AOPPs challenge triggered NADPH oxidase-dependent ROS generation which induced mitochondrial dysfunction and endoplasmic reticulum stress resulted in activation of caspase family that eventually lead to apoptosis. Lastly, blockade of RAGE, instead of CD36, largely attenuated these signals. Our study demonstrated first time that AOPPs induce chondrocyte apoptosis via RAGE-mediated and redox-dependent intrinsic apoptosis pathway in vitro. These data implicates that AOPPs may represent a novel pathogenic factor that contributes to RA progression. Targeting AOPPs-triggered cellular mechanisms might emerge as a promising therapeutic option for patients with RA.

Advanced Oxidation Protein Products as a Novel Marker of Oxidative Stress in Postmenopausal Osteoporosis.

BACKGROUND: Advanced oxidation protein products (AOPPs) are acknowledged as a novel marker of oxidation-mediated protein damage. This study aimed to investigate the plasma levels of AOPPs in postmenopausal osteoporotic women, and to determine the relationship between AOPPs accumulation and lumbar bone mineral destiny (BMD) or bone turnover markers. MATERIAL AND METHODS: Lumbar BMD was measured by dual-energy X-ray absorptiometry. Plasma AOPPs levels as a marker of protein oxidation damage and malondialdehyde (MDA) levels as a marker of lipid peroxidation were measured by spectrophotometry. The concentrations of 2 specific markers of bone turnover, bone-specific alkaline phosphatase (BALP) and tartrate-resistant acid phosphatase5b, (TRACP 5b) were quantified using ELISA kits. RESULTS: We recruited 60 postmenopausal women meeting osteoporosis (OP) diagnostic criteria of World Health Organization (WHO) and 60 postmenopausal women without OP. Plasma levels of AOPPs (P<0.001), BALP (P<0.001) and TRACP 5b (P<0.001) were statistically significantly increased in the postmenopausal osteoporotic women compared with controls, but there was no statistically significant difference in MDA (P=0.124) between the 2 groups. Plasma AOPPs levels were negatively correlated with lumbar BMD and positively correlated with bone turnover markers both in postmenopausal osteoporotic women and in all subjects. However, plasma MDA levels were not correlated with lumbar BMD or bone turnover markers. CONCLUSIONS: In postmenopausal osteoporotic women elevated AOPPs is associated with reduced BMD and increased bone turnover markers. Because AOPPs is stable and easy to detect it may be used as a simple plasma marker to predict the severity of postmenopausal OP.

Advanced oxidation protein products accelerate bone deterioration in aged rats.

Advanced oxidation protein products (AOPPs) are novel markers of oxidation-mediated protein damage, and accumulation of AOPPs is involved in many pathophysiological conditions. Our previous studies demonstrated that the serum level of AOPPs negatively correlated with the age-related change in bone mineral density (BMD) in rats and that AOPPs inhibited rat osteoblast-like cell proliferation and differentiation in vitro. However, whether AOPPs are involved in senile osteoporosis is still largely unknown. The present study aimed to test the hypothesis that accumulation of AOPPs might accelerate bone deterioration in aged rats. Seventy 18-month-old male Sprague Dawley (SD) rats were randomized to intravenous injection of vehicle, native rat serum albumin (RSA), AOPPs-modified RSA (AOPPs-RSA) with or without oral administration of apocynin (a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor), or apocynin alone. After treatment for 8 weeks or 16 weeks, seven rats in each group were sacrificed. Bone and blood samples were harvested for BMD measurement, micro-computed tomographic (micro-CT) imaging, and biochemical analysis of circulating bone biomarkers. Compared to RSA- or vehicle-treated rats, AOPPs-RSA-treated animals displayed significantly decreased total vertebral BMD and deteriorated microstructure in both the tibias and the lumbar vertebral bodies, which were associated with down-regulated plasma bone-specific alkaline phosphatase concentration and up-regulated tartrate-resistant acid phosphatase 5b concentration. These AOPPs-induced perturbations in aged rats could be prevented by the oral administration of apocynin. However, no significant differences in BMD were detected in the femurs or the biomechanical parameters tested between the different treatment groups. These data suggest that accumulation of AOPPs accelerates bone deterioration in aged rats, likely via the activation of NADPH oxidase. This study provides new information toward understanding the pathogenic basis of senile osteoporosis and may provide targets for intervention.

Advanced oxidation protein products induce inflammatory response in fibroblast-like synoviocytes through NADPH oxidase -dependent activation of NF-κB.

BACKGROUND: Advanced oxidation protein products (AOPPs), a marker of oxidative stress, are prevalent in many kinds of disorders. Rheumatoid arthritis (RA), mainly resulting from the dysfunction of fibroblast-like synoviocytes (FLSs), is related to oxidative stress. Although the increased levels of AOPPs in RA patients were reported, the effect of AOPPs on FLSs function still remains unclear. Therefore, our study aims to investigate whether AOPPs have an effect on the inflammatory response of FLSs in vitro. METHODS: FLSs obtained from both knees of rats were treated with or without AOPPs-modified rat serum albumin (AOPPs-RSA) in vitro. The mRNA and protein expression of tumor necrosis factor (TNF)-α, interleukin(IL)-1ß, matrix metalloproteinases(MMP)-3, MMP-13 and vascular endothelial growth factor (VEGF) were measured by real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA), respectively. Reactive oxygen species (ROS) generation was detected by fluorescent microscope and fluorescence microplate reader. Immunoprecipitation, Co-Immunoprecipitation and western blot were performed to examine the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and nuclear factor kappa B (NF-κB). RESULTS: Exposure of FLSs to AOPPs upregulated the mRNA and protein expression of TNF-α, IL-1ß, MMP-3, MMP-13 and VEGF in a concentration dependent manner. AOPPs treatment triggered ROS production in FLSs, which was significantly abolished by ROS scavenger N-acetyl-L-cysteine (NAC), superoxide dismutase (SOD), NADPH oxidase inhibitors diphenyleneiodonium (DPI) and apocynin. Challenged AOPPs induced phosphorylation of p47(phox), triggered an interaction between p47(phox), p22(phox) and gp91(phox), and significantly upregulated expression of NADPH oxidase subunits p47(phox), p22(phox) and gp91(phox). IκB degradation and nuclear translocation of NF-κB p65 induced by AOPPs were significantly blocked by SOD, NAC, DPI and apocynin. CONCLUSIONS: These data indicate that AOPPs induce inflammatory response in FLSs is medicated through NADPH oxidase-dependent activation of NF-κB.

Effect of melatonin on the proliferation and differentiation of chondrocytes from rat vertebral body growth plate in vitro.

PURPOSE: Abnormal growth of vertebral body growth plate (VBGP) is considered as one of the etiologic factors in the adolescent idiopathic scoliosis (AIS). It was well-known that melatonin was correlated with the emergence and development of AIS. This study aimed to investigate the effect of melatonin on rat VBGP chondrocytes in vitro. METHODS: Chondrocytes were isolated from rat VBGP, and treated with or without melatonin. Cell proliferation was measured by the Alamar Blue assay. Gene expression of collagen type II and aggrecan were evaluated by real-time PCR. Expression of the melatonin receptors (MT1, MT2), proliferating cell nuclear antigen (PCNA, a cell proliferation marker), Sox9 (a chondrocytic differentiation marker) and Smad4 (a common mediator in regulating the proliferation and differentiation of chondrocytes) were detected by Western blotting. RESULTS: Expression of melatonin receptors (MT1, MT2) were detected in the rat VBGP chondrocytes. Melatonin, at 10 and 100 µg/mL concentration, significantly inhibited the proliferation of VBGP-chondrocytes and the gene expression of collagen type II and aggrecan, and down-regulated the protein expression of PCNA, Sox9 and Smad4. In addition, the inhibitory effect of melatonin was reversed by luzindole, a melatonin receptor antagonist. CONCLUSIONS: These results suggest that melatonin at high concentrations can inhibit the proliferation and differentiation of VBGP chondrocytes, which might give some new insight into the pathogenic mechanism of AIS.

Early dysphagia complicating anterior cervical spine surgery: incidence and risk factors.

BACKGROUND: Dysphagia is a common complication of anterior cervical spine surgery, and most of them occurred in the early postoperative period. This study aimed to determine the incidence of early dysphagia after anterior cervical spine surgery and to identify its risk factors. METHODS: A review of 186 consecutive patients undergoing anterior cervical spine surgeries in a 3-year period was performed. Dysphagia at postoperative 1 month was surveyed, and the severity of dysphagia was evaluated. Demographic information and procedural characters were collected to determine their relationships to dysphagia. RESULTS: A total of 50 patients developed early postoperative dysphagia, including 23 males and 27 females. The incidence of early dysphagia after anterior cervical spine surgery was 26.9 % in this study. Mild, moderate, and severe dysphagia were found in 30, 14, and 6 patients, respectively. Female, advanced age, multi-levels surgery, use of plate, and a big protrusion of plate were found to be significantly increased early dysphagia after anterior cervical spine surgery. CONCLUSION: There is a relatively high incidence of early dysphagia after anterior cervical spine surgery, which may be attributable to multiple factors.