Sequential Correction versus Conventional Correction for Severe and Rigid Kyphoscoliosis: A Retrospective Case Control Study.

OBJECTIVE: Conventional correction techniques were challenging and of high risk of neurological complications for the correction of severe and rigid kyphoscoliosis. A new technical note we developed and named as sequential correction, was used to treat severe and rigid kyphoscoliosis. The present study was to compare the clinical outcomes of sequential correction versus conventional correction for the treatment of severe and rigid kyphoscoliosis. METHODS: This is a respectively case-control study. Between January 2014 and December 2019, 36 adults underwent the surgical correction of severe and rigid kyphoscoliosis and were included in the present study. Among them, 20 adults underwent conventional correction, 16 adults underwent sequential correction. Major curve Cobb angle, kyphotic angle, coronal imbalance, and sagittal vertical axis were compared between two groups. The patient-reported health-related quality of life outcomes, including the Oswestry disability index score, and SRS-22 questionnaire, were recorded. Independent samples t-test, Mann-Whitney U test, and Wilcoxon signed-rank test, were used to compare the differences between two groups according to the results of normal distribution test. RESULTS: In conventional correction group, the mean major curve Cobb angle was 122.50° preoperatively, 40.35° immediately after surgery, and 43.95° at final follow-up postoperatively; the mean kyphotic angle was 97.45° preoperatively, 34.45° immediately after surgery, and 38.30° at final follow-up postoperatively. In the sequential correction group, the mean major angle was 134.44° preoperatively, 44.56° immediately after surgery, and 46.25° at final follow-up postoperatively; the mean kyphotic angle was 112.31° preoperatively, 39.00° immediately after surgery, and 40.38° at final follow-up postoperatively. The mean major curve Cobb angle and kyphotic angle of both groups were improved significantly, while there were no significant differences between two groups (p > 0.001). Improved self-reported quality of life scores were achieved postoperatively and at final follow-up postoperatively, and there were no significant differences between the two groups. The total complication rate of the patients underwent conventional correction was 55%, and the total complication rate of the patients underwent sequential correction was 43.75%. The complication rate of the two groups showed no significant difference. CONCLUSIONS: Sequential correction is an excellent and safe treatment for severe and rigid kyphoscoliosis in adults, with similar clinical outcomes with conventional correction. The total complication rate of the patients who underwent sequential correction was slightly lower than conventional correction.

Sequential correction of severe and rigid kyphoscoliosis: a new technical note and preliminary results.

OBJECTIVE: The present study is to evaluate the clinical outcomes of the sequential correction of severe and rigid kyphoscoliosis. METHODS: Between January 2014 and December 2020, 27 adults with severe and rigid kyphoscoliosis underwent sequential correction combined with posterior grade 4 or grade 5 spinal osteotomy. Radiological parameters, including the major curve Cobb angle, kyphotic angle, coronal imbalance, and sagittal vertical axis (SVA), were compared. Patient self-reported health-related quality of life (HRQOL) scores were used to evaluate clinical outcomes. RESULTS: The mean major curve Cobb angle improved from 134.30 ± 13.24° to 44.48 ± 9.34° immediately after surgery and to 46.11 ± 8.94° at the final follow-up. The mean kyphotic angle improved from 112.15 ± 20.28° to 38.63 ± 15.00° immediately after surgery and to 39.85 ± 14.92° at the final follow-up. The mean preoperative major curve Cobb angle of grade 5 spinal osteotomy group was higher than that of grade 4 spinal osteotomy group. Coronal imbalance and SVA slightly improved. The patient self-reported HRQOL scores improved postoperatively and at the final follow-up. Activity, appearance and total scores of the SRS-22 of the grade 5 spinal osteotomy group at the final follow-up were significantly better than those of the grade 4 spinal osteotomy group. CONCLUSIONS: Sequential correction combined with posterior grade 4 or grade 5 spinal osteotomies is an excellent and safe treatment for severe and rigid kyphoscoliosis in adults. Sequential correction combined with posterior grade 5 spinal osteotomies can be used to correct severe and rigid kyphoscoliosis with higher major curve Cobb angle.

G3BP1 coordinates lysophagy activity to protect against compression-induced cell ferroptosis during intervertebral disc degeneration.

Lysophagy is a form of selective autophagy to remove unwanted lysosomes. However, its role in the pathogenesis of intervertebral disc degeneration (IDD) remains unclear. We intended to investigate the relationship between lysophagy and ferroptosis, as well as the potential involved molecules during IDD. Human nucleus pulposus (NP) cells were obtained from clinical patients. The protein levels, protein colocalization and cellular reactive oxygen species levels were assessed by western blotting, immunofluorescence analysis, immunoprecipitation and flow cytometry, respectively. The in vivo experiments were conducted based on the needle puncture-induced IDD model in rats. Compression pressure induces the lysophagy inactivation and lysosomal damage, resulting in iron overload and ferroptosis in human NP cells. Notably, Ras GTPase-activating protein-binding proteins 1 (G3BP1) resides at lysosomes to coordinate lysophagy activity mainly via the function of G3BP1/TSC2 complex. Dysfunction of G3BP1/TSC2 complex accelerates the lysosomal damage and ferroptosis in NP cells. Besides, inhibition of mTOR signalling ameliorates lysosomal damage and protects against cell ferroptosis. The in vivo experiments also demonstrate that the G3BP1/mTOR signalling is involved in the progression of IDD. These findings illustrate the relationship between lysophagy and compression-induced cell ferroptosis. It also indicates the positive role of G3BP1 and may provide potential targets for IDD treatment.

Sequential correction using satellite rod for the treatment of severe rigid spinal deformity: a retrospective study of 19 cases.

OBJECTIVES: The purpose of this study was to evaluate the effectiveness of sequential correction using satellite rod in patients with severe rigid spinal deformity undergoing posterior-only PVCR. METHODS: 19 patients with severe rigid spinal deformity who underwent PVCR at our center from January 2014 to December 2019 were reviewed. Radiographic measurements, including major coronal Cobb angle, kyphotic curve angle, coronal and sagittal balance were measured. Clinical results were noted, including the SRS-22 questionnaire, the Oswestry Disability Index score, and complications. RESULTS: Total 19 patients were followed at least 2 years. The mean coronal Cobb angle decreased from 122.7° ± 13.17° to 57.89° ± 8.65° postoperatively, and to 58.42° ± 8.98° at final follow-up. Correction rate is 52.8%. The kyphotic curve angle improved from 102.2° ± 17.05° preoperatively to 39.68° ± 13.67° postoperatively, and to 37.74° ± 12.14° at final follow-up. Correction rate is 61.2%. Compared to preoperative results, apex vertebral translation, ODI and SRS-22 were significantly improved at the final follow-up. CONCLUSIONS: For patients with severe rigid spinal deformities, sequential correction with an auxiliary satellite rod can effectively reduce surgical difficulty and improve correction rate.

The REDD1/TXNIP Complex Accelerates Oxidative Stress-Induced Apoptosis of Nucleus Pulposus Cells through the Mitochondrial Pathway.

The death of nucleus pulposus (NP) cells is an important cause of intervertebral disc (IVD) degeneration. Redox disturbance caused by dysfunctional mitochondria has been considered as a vital risk for NP cell survival. It is valuable to identify key proteins maintaining mitochondrial function in NP cells. A previous study found that regulated in development and DNA damage response 1 (REDD1) are upregulated during intervertebral disc degeneration and that REDD1 can cause NP cell apoptosis. Thus, the present study further explores the effect of REDD1 on IVD degeneration. Our results showed that REDD1 promotes NP cell apoptosis via the mitochondrial pathway. Importantly, REDD1 formed a complex with TXNIP to strengthen its own action, and the combination was consolidated under H2O2-induced oxidative stress. The combined inhibition of the REDD1/TXNIP complex was better than that of REDD1 or TXNIP alone in restoring cell proliferation and accelerating apoptosis. Moreover, p53 acts as the transcription factor of REDD1 to regulate the REDD1/TXNIP complex under oxidative stress. Altogether, our results demonstrated that the REDD1/TXNIP complex mediated H2O2-induced human NP cell apoptosis and IVD degeneration through the mitochondrial pathway. Interferences on these sites to achieve mitochondrial redox homeostasis may be a novel therapeutic strategy for oxidative stress-associated IVD degeneration.

Autophagy-Based Unconventional Secretory for AIM2 Inflammasome Drives DNA Damage Resistance During Intervertebral Disc Degeneration.

Intervertebral disc degeneration (IDD) is the primary cause of low back pain. Stress-induced DNA damage is closely relevant to the pathogenesis of IDD; however, the underlying mechanisms remain unclear. This study investigated the role of the absent in melanoma 2 (AIM2) inflammasome as a DNA damage sensor in nucleus pulposus (NP) cells. We found that the level of AIM2 increased in degenerated discs and was correlated to the degree of IDD. Knockdown of AIM2 ameliorated H2O2-induced DNA damage and apoptosis in NP cells in vitro, and retarded the progression of IDD in vivo. Furthermore, the induction of autophagy protected against cellular DNA damage via the unconventional secretion of AIM2. We further identified the Golgi re-assembly and stacking protein 55 (GRASP55) as mediator of the transport and secretion of AIM2 via an autophagic pathway. Taken together, our researches illustrate the role and regulatory mechanism of the AIM2 inflammasome during IDD. Targeting the AIM2 inflammasome may offer a promising therapeutic strategy for patients with IDD.

Bone-derived mesenchymal stem cells alleviate compression-induced apoptosis of nucleus pulposus cells by N6 methyladenosine of autophagy.

N6 methyladenosine (m6A) is one of the most prevalent epitranscriptomic modifications of mRNAs, and plays a critical role in various bioprocesses. Bone-derived mesenchymal stem cells (BMSCs) can attenuate apoptosis of nucleus pulposus cells (NPCs) under compression; however, the underlying mechanisms are poorly understood. This study showed that the level of m6A mRNA modifications was decreased, and the autophagic flux was increased in NPCs under compression when they were cocultured with BMSCs. We report that under coculture conditions, RNA demethylase ALKBH5-mediated FIP200 mRNA demethylation enhanced autophagic flux and attenuated the apoptosis of NPCs under compression. Specific silencing of ALKBH5 results in impaired autophagic flux and a higher proportion of apoptotic NPCs under compression, even when cocultured with BMSCs. Mechanistically, we further identify that the m6A "reader" YTHDF2 is likely to be involved in the regulation of autophagy, and lower m6A levels in the coding region of FIP200 lead to a reduction in YTHDF2-mediated mRNA degradation of FIP200, a core molecular component of the ULK1 complex that participates in the initiating process of autophagy. Taken together, our study reveals the roles of ALKBH5-mediated FIP200 mRNA demethylation in enhancing autophagy and reducing apoptosis in NPCs when cocultured with BMSCs.

Keyhole Foraminotomy via a Percutaneous Posterior Full-endoscopic Approach for Cervical Radiculopathy: An Advanced Procedure and Clinical Study.

Endoscopic cervical foraminotomy is increasingly used for cervical spondylotic radiculopathy (CSR), but there is great concern about radiation exposure because of the heavy dependence of this surgical method on fluoroscopy. The objective of this study was to introduce in detail an advanced surgical technique of keyhole foraminotomy via a percutaneous posterior full-endoscopic approach as a treatment for CSR and investigate its clinical outcomes. We retrospectively reviewed 33 consecutive patients with CSR who underwent keyhole foraminotomy via a percutaneous posterior full-endoscopic approach from October 2015 to April 2017. The patients' general characteristics, including operative time, blood loss, hospital stay, complications, and recurrence, were obtained. Clinical outcomes were evaluated using the visual analogue scale (VAS) for radicular pain, the neck disability index (NDI) for functional assessment, and the modified MacNab criteria for patient satisfaction. All operations were successfully performed (mean operation time, 62 min), with no measurable blood loss or severe related complications. The mean follow-up was 25 months. The VAS and NDI scores were significantly improved as compared with those in the preoperative period (preoperative vs. final follow-up: 7.6±1.6 vs. 3.83±7.34 for VAS, P<0.01; 69.5%±10.5% vs. 17.54%±13.40% for NDI, P<0.01). Of the 33 patients, 32 (97.0%) had good-to-excellent global outcomes and all patients obtained symptomatic improvement. In conclusion, keyhole foraminotomy via a percutaneous posterior full-endoscopic approach is an efficient, safe, and feasible procedure for the treatment of CSR. Its simplified single-step blunt incision for localization appears to decrease radiation exposure risks.

Long non-coding RNA HOTAIR modulates intervertebral disc degenerative changes via Wnt/ß-catenin pathway.

BACKGROUND: Intervertebral disc degeneration (IDD) has a complicated and enigmatic pathogenic process. Accumulating evidence shows that long non-coding RNAs (LncRNAs) play a role in the pathogenesis of IDD. This study aimed to investigate the expression and role of the LncRNA HOTAIR in IDD pathogenesis. METHODS: Nucleus pulposus (NP) tissue samples from 10 patients with idiopathic scoliosis and 10 patients with lumbar disc herniation were collected. qRT-PCR was used to assess the expression of HOTAIR and ECM-related genes; western blotting was used to detect the expression of senescence biomarkers, apoptosis-related proteins, and Wnt/ß-catenin pathway; flow cytometry was used to detect apoptosis; and the MTT assay was used to determine cell proliferation. Moreover, a classic needle-punctured rat tail model was used to investigate the role of HOTAIR in IDD in vivo. RESULTS: The results showed that the expression of HOTAIR significantly increased during IDD progression. The overexpression of HOTAIR was found to induce nucleus pulposus (NP) cell senescence, apoptosis, and extracellular matrix (ECM) degradation. HOTAIR silencing by RNA interference in NP cells prevented interleukin-1ß-induced NP cell senescence, apoptosis, and ECM degradation. Furthermore, we found that the Wnt/ß-catenin pathway played a role in regulating HOTAIR to induce these changes in NP cells. Moreover, HOTAIR inhibition in a rat model effectively attenuated IDD symptoms in vivo. CONCLUSIONS: Our findings confirmed that HOTAIR promoted NP cell senescence, apoptosis, and ECM degradation via the activation of the Wnt/ß-catenin pathway, while silencing HOTAIR attenuated this degeneration process, indicating a potential therapeutic target against IDD.

Angiopoietin-like protein 8 expression and association with extracellular matrix metabolism and inflammation during intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) is considered the primary culprit for low back pain. Although the underlying mechanisms remain unknown, hyperactive catabolism of the extracellular matrix (ECM) and inflammation are suggested to play critical roles in IDD progression. This study was designed to elucidate the role of angiopoietin-like protein 8 (ANGPTL8) in the progression of IDD, especially the relationship of ANGPTL8 with ECM metabolism and inflammation. A positive association between ANGPTL8 expression and degenerative grades of IDD was detected in the analysis of human nucleus pulposus tissue samples. Silencing of ANGPTL8 attenuated the degradation of the anabolic protein type collagen II, and reduced the expression of the catabolic proteins MMP3 and MMP9, and the inflammatory cytokine IL-6 through inhibition of NF-κB signalling activation. In addition, the effect of ANGPTL8 was evaluated in a rat model of puncture-induced IDD. Based on the imaging results and histological examination in animal study, knockdown of ANGPTL8 was demonstrated to ameliorate the IDD progression. These results demonstrate the detrimental role of ANGPTL8 expression in the pathogenesis of IDD and may provide a new therapeutic target for IDD treatment.

Impaired calcium homeostasis via advanced glycation end products promotes apoptosis through endoplasmic reticulum stress in human nucleus pulposus cells and exacerbates intervertebral disc degeneration in rats.

Previous studies identified advanced glycation end products (AGEs) accumulation in the intervertebral disc (IVD) as an essential risk factor associated with IVD degeneration via accelerated cell apoptosis and impeded extracellular-matrix metabolism; however, the underlying mechanisms have not been fully elucidated. Here, we investigated the effects and mechanisms of AGEs-mediated apoptosis in vitro and in vivo. We evaluated the effects of AGEs on endoplasmic reticulum (ER) stress, apoptosis, and subcellular calcium (Ca2+ ) redistribution. Our data indicated time- and concentration-dependent upregulation of ER-stress responses in AGEs-treated nucleus pulposus (NP) cells. Additionally, we observed marked suppression of AGEs-mediated apoptosis following the inhibition of ER stress using 4-phenylbutyric acid. Moreover, AGEs-induced sustained cytosolic Ca2+ ([Ca2+ ]c) elevation and ER luminal Ca2+ ([Ca2+ ]er) depletion in a concentration- and time-dependent manner in NP cells. Furthermore, we observed significant increases and decreases in levels of the ER-resident Ca2+ -release channels inositol 1,4,5-triphosphate receptor and ryanodine receptor and ER Ca2+ -reuptake pumps sarco/endoplasmic reticulum Ca2+ -ATPase, respectively. Pharmacologically blocking ER Ca2+ release using Ca2+ antagonists significantly ameliorated Ca2+ dyshomeostasis, ER stress, and subsequent apoptosis in NP cells and partially attenuated the progression of IVD degeneration in vivo. These results demonstrated that impaired Ca2+ homeostasis plays an essential role in AGEs-mediated ER stress and subsequent apoptosis in NP cells, with blockage of ER Ca2+ release partially ameliorating subcellular Ca2+ redistribution, ER stress, and apoptosis. Our findings provide novel mechanistic insight into the role of AGEs in the pathogenesis of IVD degeneration and a potential therapeutic strategy.

Berberine ameliorates oxidative stress-induced apoptosis by modulating ER stress and autophagy in human nucleus pulposus cells.

AIM: Nucleus pulposus (NP) cell apoptosis induced by oxidative stress is known to be closely involved in the pathogenesis of intervertebral disc (IVD) degeneration. Berberine, a small molecule derived from Rhizoma coptidis, has been found to exert antioxidative activity and preserve cell viability. The present study aims to investigate whether berberine can prevent NP cell apoptosis under oxidative damage and the potential underlying mechanisms. METHODS AND MATERIALS: The effects of berberine on IVD degeneration were investigated both in vitro and in vivo. KEY FINDINGS: Our results showed that berberine significantly mitigated oxidative stress-decreased cell viability as well as apoptosis in human NP cells. Berberine treatment could attenuate oxidative stress-induced ER stress and autophagy in a concentration-dependent manner. With 4-PBA (ER stress specific inhibitor) and 3-MA (autophagy specific inhibitor) administration, we demonstrated that berberine inhibited oxidative stress-induced apoptosis by modulating the ER stress and autophagy pathway. We also found that the IRE1/JNK pathway was involved in the induction of ER stress-dependent autophagy. With Ca2+ chelator BAPTA-AM utilization, we revealed that oxidative stress-mediated ER stress and autophagy repressed by berberine could be restored by inducing intracellular Ca2+ dysregulation. Furthermore, in vivo study provided evidence that berberine treatment could retard the process of puncture-induced IVD degeneration in a rat model. SIGNIFICANCE: Our results indicate that berberine could prevent oxidative stress-induced apoptosis by modulating ER stress and autophagy, thus offering a novel potential pharmacological treatment strategy for IVD degeneration.

Severe Kyphoscoliosis Associated with Multiple Giant Intraspinal Epidural Cysts: A Case Report and Literature Review.

BACKGROUND: Severe kyphoscoliosis associated with multiple giant spinal epidural arachnoid cysts (SEACs) is an extremely rare condition and remains a challenge in clinical practice. This study aimed to present a case of severe spinal deformity associated with multiple giant SEACs and to discuss strategies for the preoperative diagnosis and treatment. CASE DESCRIPTION: A 22-year-old man with severe thoracolumbar kyphoscoliosis associated with multiple giant SEACs presented with progressive scoliosis, spastic paralysis, numbness, and abnormal gait. X-ray and magnetic resonance imaging revealed severe rigid kyphoscoliosis, extensive diffuse cystic space-occupying lesions, and diffuse spinal cord compression. After multidisciplinary consultation and discussion, the patient underwent a cyst-peritoneal shunting surgery followed by posterior vertebral column resection (PVCR) correction. The postoperative course was uneventful. Both kyphosis and scoliosis were significantly corrected, and muscle weakness of the lower extremities and sensory disturbance partially improved. At the 2-year follow-up visit, the patient could freely walk without the aid of crutches, but there were some residual neurologic deficits in both legs. A plain radiograph showed that bony fusion was achieved, and the correction was well maintained. CONCLUSIONS: Cyst-peritoneal shunting surgery followed by PVCR, as in our case, could be an alternative surgical strategy for multiple giant SEACs associated with severe rigid kyphoscoliosis.

Surgical approach and management outcomes for junction tuberculous spondylitis: a retrospective study of 77 patients.

BACKGROUND: Junction tuberculous spondylitis involves the stress transition zone of the spine and has a high risk of progression to kyphosis or paraplegia. Problems still exist with treatment for spinal junction tuberculosis. This study investigated the surgical approach and clinical outcomes of junction spinal tuberculosis. METHODS: From June 1998 to July 2014, 77 patients with tuberculous spondylitis were enrolled. All patients received 2-3 weeks of anti-tuberculous treatment preoperatively; treatment was prolonged for 2-3 months when active pulmonary tuberculosis was present. The patients underwent anterior debridement and were followed up for an average of 29.4 months clinically and radiologically. RESULTS: The cervicothoracic junction spine (C7-T3) was involved in 15 patients. The thoracolumbar junction spine (T11-L2) was involved in 39 patients. The lumbosacral junction spine (L4-S1) was involved in 23 patients. Two patients with recurrence underwent reoperation; the drugs were adjusted, and all patients achieved bone fusion. The preoperative cervicothoracic and thoracolumbar kyphosis angle and lumbosacral angle were 31.4 ± 10.9°, 32.9 ± 9.2°, and 19.3 ± 3.7°, respectively, and the corresponding postoperative angles were ameliorated significantly to 9.1 ± 3.2°, 8.5 ± 2.9°, and 30.3 ± 2.8°. The preoperative ESR and C-reactive protein level of all patients were 48.1 ± 11.3 mm/h and 65.5 ± 16.2 mg/L which decreased to 12.3 ± 4.3 mm/h and 8.6 ± 3.7 mg/L at the final follow-up, respectively. All patients that had neurological symptoms achieved function status improvement at different degrees. CONCLUSION: For spinal tuberculosis of spinal junctions, anterior debridement, internal fixation, and fusion can be preferred and achieved. If multiple segment lesions are too long or difficult for operation of anterior internal fixation, combining posterior pedicle screw fixation is appropriate.

The involvement of regulated in development and DNA damage response 1 (REDD1) in the pathogenesis of intervertebral disc degeneration.

Regulated in development and DNA damage response 1 (REDD1) is an evolutionarily conserved, ubiquitous protein that responds to various cell stresses. Studies have proved REDD1 is involved in many diseases, such as osteoarthritis and cancer. The present study aimed to investigate the potential role of REDD1 in the pathogenesis of intervertebral disc degeneration (IDD). Analysis of clinical tissue samples showed REDD1 expression was up-regulated during IDD and was correlated with the grade of disc degeneration. Overexpression of REDD1 in normal human nucleus pulposus (NP) cells resulted in extracellular matrix (ECM) degeneration. Further, we investigated the function of REDD1 using a serum deprivation-induced IDD vitro model and found that REDD1 was up-regulated in a temporal manner. However, hypoxia abolished this increase through down-regulation of NF-κB. Knockdown of REDD1 or NF-κB by si-RNA significantly rescued ECM from degeneration both in normoxia and hypoxia. In addition, NF-κB/REDD1 mediated the protection of hypoxia from serum deprivation-induced apoptosis and autophagy in NP cells. These results suggest that REDD1 might play a pivotal role in IDD pathogenesis, thereby potentially providing a new therapeutic target for IDD treatment.

Sirtuin 3-dependent mitochondrial redox homeostasis protects against AGEs-induced intervertebral disc degeneration.

Intervertebral disc (IVD) degeneration contributes largely to pathoanatomical and degenerative changes of spinal structure that increase the risk of low back pain. Apoptosis in nucleus pulposus (NP) can aggravate IVD degeneration, and increasing studies have shown that interventions targeting NP cell apoptosis can ameliorate IVD degeneration, exhibiting their potential for use as therapeutic strategies. Recent data have shown that advanced glycation end products (AGEs) accumulate in NP tissues in parallel with the progression of IVD degeneration and form a microenvironment of oxidative stress. This study examined whether AGEs accumulation aggravates NP cell apoptosis and IVD degeneration, and explored the mechanisms underlying these effects. We observed that the viability and proliferation of human NP cells were significantly suppressed by AGEs treatment, mainly due to apoptosis. Furthermore, activation of the mitochondrial apoptosis pathway was detected after AGEs treatment. In addition, the molecular data showed that AGEs could significantly aggravate the generation of mitochondrial reactive oxygen species and prolonged activation of the mitochondrial permeability transition pore, as well as the increased level of Bax protein and decreased level of Bcl-2 protein in mitochondria. These effects could be reduced by antioxidant (2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride (MitoTEMPO) and Visomitin (SKQ1). Importantly, we identified that impairment of Sirtuin3 (SIRT3) function and the mitochondrial antioxidant network were vital mechanisms in AGEs-induced oxidative stress and secondary human NP cell apoptosis. Finally, based on findings that nicotinamide mononucleotide (NMN) could restore SIRT3 function and rescue human NP cell apoptosis through adenosine monophosphate-activated protein kinase and peroxisome proliferator-activated receptor-γ coactivator 1α (AMPK-PGC-1α) pathway in vitro, we confirmed its protective effect on AGEs-induced IVD degeneration in vivo. In conclusion, our data demonstrate that SIRT3 protects against AGEs-induced human NP cell apoptosis and IVD degeneration. Targeting SIRT3 to improve mitochondrial redox homeostasis may represent a potential therapeutic strategy for attenuating AGEs-associated IVD degeneration.

MicroRNA-494 promotes apoptosis and extracellular matrix degradation in degenerative human nucleus pulposus cells.

PURPOSE: This study investigated the expression and function of the microRNA-494 in intervertebral disc degeneration (IDD). RESULTS: MicroRNA-494 expression was upregulated during IDD progression; its overexpression increased the expression of ECM catabolic factors such as matrix metalloproteinase and A disintegrin and metalloproteinase with thrombospondin motif in NP cells while decreasing that of anabolic genes such as type II collagen and aggrecan; it also induced the apoptosis of NP cells, as determined by flow cytometry. These effects were reversed by microRNA-494 inhibitor treatment. SOX9 was identified as a target of negative regulation by microRNA-494. Promoter hypomethylation and NF-κB activation were associated with microRNA-494 upregulation in IDD. MATERIALS AND METHODS: MicroRNA-494 expression in degenerative nucleus pulposus (NP) tissue was assessed by quantitative real-time PCR. The effect of microRNA-494 on extracellular matrix (ECM) metabolism and NP cell apoptosis was evaluated by transfection of microRNA-494 mimic or inhibitor. The regulation of SRY-related high mobility group box (SOX)9 expression by microRNA-494 was assessed with the luciferase reporter assay, and the methylation status of the microRNA-494 promoter was evaluated by methylation-specific PCR and bisulfite sequencing PCR. The role of activated nuclear factor (NF)-κB in the regulation of microRNA-494 expression was evaluated using specific inhibitors. CONCLUSIONS: MicroRNA-494 promotes ECM degradation and apoptosis of degenerative human NP cells by directly targeting SOX9.

MicroRNA-15b silencing inhibits IL-1ß-induced extracellular matrix degradation by targeting SMAD3 in human nucleus pulposus cells.

OBJECTIVES: To determine the role of microRNA-15b (miR-15b) in interleukin-1 beta (IL-1ß)-induced extracellular matrix (ECM) degradation in the nucleus pulposus (NP). RESULTS: MiR-15b was up-regulated in degenerative NP tissues and in IL-1ß-stimulated NP cells, as compared to the levels in normal controls (normal tissue specimens from patients with idiopathic scoliosis). Bioinformatics and luciferase activity analyses showed that mothers against decapentaplegic homolog 3 (SMAD3), a key mediator of the transforming growth factor-ß signaling pathway, was directly targeted by miR-15b. Functional analysis demonstrated that miR-15b overexpression aggravated IL-1ß-induced ECM degradation in NP cells, while miR-15b inhibition had the opposite effects. Prevention of IL-1ß-induced NP ECM degeneration by the miR-15b inhibitor was attenuated by small-interfering-RNA-mediated knockdown of SMAD3. In addition, activation of MAP kinase and nuclear factor-κB up-regulated miR-15b expression and down-regulated SMAD3 expression in IL-1ß-stimulated NP cells. CONCLUSIONS: MiR-15b contributes to ECM degradation in intervertebral disc degeneration (IDD) via targeting of SMAD3, thus providing a novel therapeutic target for IDD treatment.