MIF inhibition attenuates intervertebral disc degeneration by reducing nucleus pulposus cell apoptosis and inflammation.

Nucleus pulposus cells (NPCs) apoptosis and inflammation are the extremely critical factors of intervertebral disc degeneration (IVDD). Nevertheless, the underlying procedure remains mysterious. Macrophage migration inhibitory factor (MIF) is a cytokine that promotes inflammation and has been demonstrated to have a significant impact on apoptosis and inflammation. For this research, we employed a model of NPCs degeneration stimulated by lipopolysaccharides (LPS) and a rat acupuncture IVDD model to examine the role of MIF in vitro and in vivo, respectively. Initially, we verified that there was a significant rise of MIF expression in the NP tissues of individuals with IVDD, as well as in rat models of IVDD. Furthermore, this augmented expression of MIF was similarly evident in degenerated NPCs. Afterwards, it was discovered that ISO-1, a MIF inhibitor, effectively decreased the quantity of cells undergoing apoptosis and inhibited the release of inflammatory molecules (TNF-α, IL-1ß, IL-6). Furthermore, it has been shown that the PI3K/Akt pathway plays a vital part in the regulation of NPCs degeneration by MIF. Ultimately, we showcased that the IVDD process was impacted by the MIF inhibitor in the rat model. In summary, our experimental results substantiate the significant involvement of MIF in the degeneration of NPCs, and inhibiting MIF activity can effectively mitigate IVDD.

M1 macrophage-derived exosomes promote intervertebral disc degeneration by enhancing nucleus pulposus cell senescence through LCN2/NF-κB signaling axis.

Intervertebral disc degeneration (IVDD) is the primary factor contributing to low back pain (LBP). Unlike elderly patients, many young IVDD patients usually have a history of trauma or long-term abnormal stress, which may lead to local inflammatory reaction causing by immune cells, and ultimately accelerates degeneration. Research has shown the significance of M1-type macrophages in IVDD; nevertheless, the precise mechanism and the route by which it influences the function of nucleus pulposus cell (NPC) remain unknown. Utilizing a rat acupuncture IVDD model and an NPC degeneration model induced by lipopolysaccharide (LPS), we investigated the function of M1 macrophage-derived exosomes (M1-Exos) in IVDD both in vivo and in vitro in this study. We found that M1-Exos enhanced LPS-induced NPC senescence, increased the number of SA-ß-gal-positive cells, blocked the cell cycle, and promoted the activation of P21 and P53. M1-Exos derived from supernatant pretreated with the exosome inhibitor GW4869 reversed this result in vivo and in vitro. RNA-seq showed that Lipocalin2 (LCN2) was enriched in M1-Exos and targeted the NF-κB pathway. The quantity of SA-ß-gal-positive cells was significantly reduced with the inhibition of LCN2, and the expression of P21 and P53 in NPCs was decreased. The same results were obtained in the acupuncture-induced IVDD model. In addition, inhibition of LCN2 promotes the expression of type II collagen (Col-2) and inhibits the expression of matrix metalloproteinase 13 (MMP13), thereby restoring the equilibrium of metabolism inside the extracellular matrix (ECM) in vitro and in vivo. In addition, the NF-κB pathway is crucial for regulating M1-Exo-mediated NPC senescence. After the addition of M1-Exos to LPS-treated NPCs, p-p65 activity was significantly activated, while si-LCN2 treatment significantly inhibited p-p65 activity. Therefore, this paper demonstrates that M1 macrophage-derived exosomes have the ability to deliver LCN2, which activates the NF-κB signaling pathway, and exacerbates IVDD by accelerating NPC senescence. This may shed new light on the mechanism of IVDD and bring a fresh approach to IVDD therapy.

Inhibition of MAGL attenuates Intervertebral Disc Degeneration by Delaying nucleus pulposus senescence through STING.

Intervertebral disc degeneration (IVDD) stands as the primary cause of low back pain (LBP). A significant contributor to IVDD is nucleus pulposus cell (NPC) senescence. However, the precise mechanisms underlying NPC senescence remain unclear. Monoacylglycerol lipase (MAGL) serves as the primary enzyme responsible for the hydrolysis of 2-arachidonoylglycerol (2-AG), breaking down monoglycerides into glycerol and fatty acids. It plays a crucial role in various pathological processes, including pain, inflammation, and oxidative stress. In this study, we utilized a lipopolysaccharide (LPS)-induced NPC senescence model and a rat acupuncture-induced IVDD model to investigate the role of MAGL in IVDD both in vitro and in vivo. Initially, our results showed that MAGL expression was increased 2.41-fold and 1.52-fold within NP tissues from IVDD patients and rats induced with acupuncture, respectively. This increase in MAGL expression was accompanied by elevated expression of p16INK4α. Following this, it was noted that the suppression of MAGL resulted in a notable decrease in the quantity of SA-ß-gal-positive cells and hindered the manifestation of p16INK4α and the inflammatory factor IL-1ß in NPCs. MAGL inhibition promotes type II collagen (Col-2) expression and inhibits matrix metalloproteinase 13 (MMP13), thereby restoring the balance of extracellular matrix (ECM) metabolism both in vitro and in vivo. A significant role for STING has also been demonstrated in the regulation of NPC senescence by MAGL. The expression of the STING protein was reduced by 57% upon the inhibition of MAGL. STING activation can replicate the effects of MAGL and substantially increase LPS-induced inflammation while accelerating the senescence of NPCs. These results strongly indicate that the inhibition of MAGL can significantly suppress nucleus pulposus senescence via its interaction with STING, consequently restoring the balance of ECM metabolism. This insight provides new perspectives for potential treatments for IVDD.

Application of Enhanced Recovery After Surgery in Patients with Osteoporotic Vertebral Compression Fractures Undergoing Percutaneous Kyphoplasty.

BACKGROUND: The enhanced recovery after surgery (ERAS) program helps patients recover faster and better, postoperatively. The aim of this retrospective study was to assess the clinical effectiveness of the ERAS program after percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fractures. METHODS: We enrolled patients with osteoporotic vertebral compression fracture who had undergone PKP between January 2019 and June 2021 and divided them into the control group (CG; n = 296), without the ERAS program, and the intervention group (IG; n = 306), with the ERAS program. The visual analog scale (VAS), Oswestry Disability Index (ODI), and Barthel Index scores of the 2 groups were compared on admission and 2 days and 1, 6, and 12 months postoperatively. Perioperative evaluation parameters included the mean surgery time, length of stay (LOS), and hospitalization expenses. In addition, postoperative complications were compared. RESULTS: Regarding perioperative parameters, LOS and hospitalization expenses were significantly better in IG than in CG (P < 0.001), but the mean surgery time did not differ significantly (P > 0.05). The VAS, Barthel Index, and ODI scores were significantly better in IG than in CG at 2 days and 1 month postoperatively (P < 0.001). None of the clinical effectiveness parameters (VAS, Barthel Index, and ODI scores) differed between IG and CG at 6 or 12 months postoperatively. In addition, 141 patients in CG and 56 patients in IG experienced postoperative complications, including pressure ulcers, deep vein thrombosis, nausea and vomiting, and refracture (P = 0.970, P = 0.036, P < 0.001, P = 0.002 respectively). CONCLUSIONS: For patients undergoing PKP, the ERAS program is a reliable and effective perioperative management method that can effectively reduce LOS, postoperative pain, and economic burden and promote recovery of patients.

The role of ferroptosis in intervertebral disc degeneration.

Nucleus pulposus, annulus fibrosus, and cartilage endplate constitute an avascular intervertebral disc (IVD), which is crucial for spinal and intervertebral joint mobility. As one of the most widespread health issues worldwide, intervertebral disc degeneration (IVDD) is recognized as a key contributor to back and neck discomfort. A number of degenerative disorders have a strong correlation with ferroptosis, a recently identified novel regulated cell death (RCD) characterized by an iron-dependent mechanism and a buildup of lipid reactive oxygen species (ROS). There is growing interest in the part ferroptosis plays in IVDD pathophysiology. Inhibiting ferroptosis has been shown to control IVDD development. Several studies have demonstrated that in TBHP-induced oxidative stress models, changes in ferroptosis marker protein levels and increased lipid peroxidation lead to the degeneration of intervertebral disc cells, which subsequently aggravates IVDD. Similarly, IVDD is significantly relieved with the use of ferroptosis inhibitors. The purpose of this review was threefold: 1) to discuss the occurrence of ferroptosis in IVDD; 2) to understand the mechanism of ferroptosis and its role in IVDD pathophysiology; and 3) to investigate the feasibility and prospect of ferroptosis in IVDD treatment.

Thoracolumbar fascia injury in osteoporotic vertebral fracture: the important concomitant damage.

BACKGROUND: Thoracolumbar fascia injury (FI) is rarely discussed in osteoporotic vertebral fracture (OVF) patients in previous literature and it is usually neglected and treated as an unmeaning phenomenon. We aimed to evaluate the characteristics of the thoracolumbar fascia injury and further discuss its clinical significance in the treatment of kyphoplasty for osteoporotic vertebral fracture (OVF) patients. METHODS: Based on the presence or absence of FI, 223 OVF patients were divided into two groups. The demographics of patients with and without FI were compared. The visual analogue scale and Oswestry disability index scores were compared preoperatively and after PKP treatment between these groups. RESULTS: Thoracolumbar fascia injuries were observed in 27.8% of patients. Most FI showed a multi-level distribution pattern which involved a mean of 3.3 levels. Location of fractures, severity of fractures and severity of trauma were significantly different between patients with and without FI. In further comparison, severity of trauma was significantly different between patients with severe and non-severe FI. In patients with FI, VAS and ODI scores of 3 days and 1 month after PKP treatment were significantly worse compared to those without FI. It showed the same trend in VAS and ODI scores in patients with severe FI when compared to those patients with non-severe FI. CONCLUSIONS: FI is not rare in OVF patients and presents multiple levels of involvement. The more serious trauma suffered, the more severe thoracolumbar fascia injury presented. The presence of FI which was related to residual acute back pain significantly affected the effectiveness of PKP in treating OVFs. TRIAL REGISTRATION: retrospectively registered.

Enhanced recovery after surgery (ERAS) relieves psychological stress in patients with osteoporotic vertebral compression fracture undergoing percutaneous kyphoplasty: an observational retrospective cohort study.

STUDY DESIGN: This is an observational retrospective cohort study. OBJECTIVE: The purpose of this study is to investigate the incidence rate of depression and anxiety and the changes in patients treated with percutaneous kyphoplasty (PKP) following ERAS protocol. The incidence of depression and anxiety is not uncommon in patients with osteoporotic vertebral compression fracture (OVCF), which affects the prognosis of surgery. Enhanced recovery after surgery (ERAS) protocols can improve the perioperative stress response of patients. MATERIALS AND METHODS: Patients were treated conventionally in 2019 as the control group (CG) (n = 281), and patients were treated according to the ERAS protocol in 2020 as the intervention group (IG) (n = 251). All patients were evaluated for depression and anxiety using Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 at admission, postoperative 1 week, 1 month and 3, 6, 12 months. RESULTS: The degree of depression statistically decreased in the IG at follow-up periods (p < 0.001), and the degree of anxiety statistically decreased at 1 week (p < 0.001), 1 month (p < 0.001), 3 months (p = 0.017). Patients in the IG could soothe depression and anxiety disorders faster than patients in the CG and maintain psychological stability at the follow-up periods. The percentage of moderate or above depression in the IG was statistically fewer than in the CG at follow-up periods (p < 0.01). The odds ratio (OR) was respectively 0.410, 0.357, 0.294, 0.333, 0.327 from 1 week to 12 months. While the percentage of patients with moderate or above anxiety significantly decreased in the IG at 1 week (p < 0.001), OR = 0.528, 1 month (p = 0.037), OR = 0.309 and 12 months (p = 0.040), OR = 0.554, no differences between 3 months (p = 0.187) and 6 months (p = 0.133). CONCLUSION: PKP following ERAS protocol to treat patients with OVCF had a better effect on relieving postoperative anxiety and depression than following conventional protocol.

A Minimally Invasive Annulus Fibrosus Needle Puncture Model of Intervertebral Disc Degeneration in Rats.

BACKGROUND: The needle puncture model in rats has been accepted as an ordinary model to induce intervertebral disc degeneration (IVDD). However, the model primarily penetrated the whole intervertebral disc, resulting in injury to the nucleus pulposus (NP) and annulus fibrosus (AF). The intention of this research was to explore a minimally invasive approach through needle puncture of the AF percutaneously in rats. METHODS: Twenty SD rats underwent puncture at Co8/9 via a 20 G percutaneous needle. The needle was slowly advanced perpendicular to the tail skin to penetrate the whole AF without damaging the NP limited by a hand-made sheath. The X-rays and magnetic resonance imaging T2 relaxation was evaluated at 1, 2, and 3 weeks to assess the disc height index and signal changes. Histological and immunohistochemical staining of the IVD were obtained under a light microscope. RESULTS: X-rays showed that the disc height had progressively narrowed to 49% of baseline 3 weeks after injury. magnetic resonance imaging evaluation demonstrated that the mean T2-weighted signal intensity at 3 weeks was 43% of that in the uninjured control group at the Co8/9 level. Histological staining demonstrated disorganized lamellae in the AF and decreased proteoglycan content and cellularity within the NP in the injured discs. CONCLUSIONS: The present research demonstrates a reliable and convenient approach to induce an AF tear in rats through percutaneous needle puncture. This model reduces harm to the experimental animals significantly while imitating the progressive degeneration process. More importantly, the model confirmed that AF damage alone could lead to IVDD and provided a research method for AF degeneration in IVDD.

CB2R Attenuates Intervertebral Disc Degeneration by Delaying Nucleus Pulposus Cell Senescence through AMPK/GSK3ß Pathway.

Nucleus pulposus (NP) cell (NPC) senescence is one of the main causes of intervertebral disc degeneration (IVDD). However, the underlying mechanism of NPC senescence is still unclear. The cannabinoid type 2 receptor (CB2R) is a member of the cannabinoid system and plays an important role in antioxidative stress, anti-inflammatory and antisenescence activities. In this study, we used a hydrogen peroxide (H2O2)-induced NPC senescence model and a rat acupuncture IVDD model to explore the role of CB2R in IVDD in vitro and in vivo. First, we confirmed that the expression of p16INK4a in the NP tissues of IVDD patients and rat acupuncture IVDD models obviously increased accompanied by a decrease in CB2R expression. Subsequently, we found that activation of CB2R significantly reduced the number of SA-ß-gal positive cells and suppressed the expression of p16INK4a and senescence-related secretory phenotypes [SASP, including matrix metalloproteinase 9 and 13 (MMP9, MMP13) and high mobility group protein b1 (HMGB1)]. In addition, activation of CB2R promoted the expression of collagen type II (Col-2) and SRY-Box transcription factor 9 (SOX9), inhibit the expression of collagen type X (Col-X), and restore the balance of extracellular matrix (ECM) metabolism. In addition, the AMPK/GSK3ß pathway was shown to play an important role in CB2R regulation of NPC senescence. Inhibition of AMPK expression reversed the effect of JWH015 (a CB2R agonist). Finally, we further demonstrated that in the rat IVDD model, the AMPK/GSK3ß pathway was involved in the regulation of CB2R on NPC senescence. In conclusion, our experimental results prove that CB2R plays an important role in NPC senescence. Activation of CB2R can delay NPC senescence, restore the balance of ECM metabolism, and attenuate IVDD.

Melatonin Attenuates Intervertebral Disk Degeneration via Maintaining Cartilaginous Endplate Integrity in Rats.

OBJECTIVE: The aim of this study is to verify whether melatonin (Mel) could mitigate intervertebral disk degeneration (IVDD) in rats and to investigate the potential mechanism of it. METHOD: A rat acupuncture model of IVDD was established with intraperitoneal injection of Mel. The effect of Mel on IVDD was analyzed via radiologic and histological evaluations. The specific Mel receptors were investigated in both the nucleus pulposus (NP) and cartilaginous endplates (EPs). In vitro, EP cartilaginous cells (EPCs) were treated by different concentrations of Mel under lipopolysaccharide (LPS) and Luzindole conditions. In addition, LPS-induced inflammatory response and matrix degradation following nuclear factor kappa-B (NF-κB) pathway activation were investigated to confirm the potential mechanism of Mel on EPCs. RESULTS: The percent disk height index (%DHI) and MRI signal decreased after initial puncture in the degeneration group compared with the control group, while Mel treatment protected disk height from decline and prevented the loss of water during the degeneration process. In the meantime, the histological staining of the Mel groups showed more integrity and well-ordered construction of the NP and EPs in both low and high concentration than that of the degeneration group. In addition, more deep-brown staining of type II collagen (Coll-II) was shown in the Mel groups compared with the degeneration group. Furthermore, in rat samples, immunohistochemical staining showed more positive cells of Mel receptors 1a and 1b in the EPs, instead of in the NP. Moreover, evident osteochondral lacuna formation was observed in rat EPs in the degeneration group; after Mel treatment, the osteochondral destruction alleviated accompanying fewer receptor activator for nuclear factor-κB ligand (RANKL) and tartrate-resistant acid phosphatase (TRAP)-stained positive cells expressed in the EPs. In vitro, Mel could promote the proliferation of EPCs, which protected EPCs from degeneration under LPS treatment. What is more, Mel downregulated the inflammatory response and matrix degradation of EPCs activated by NF-κB pathway through binding to its specific receptors. CONCLUSION: These results indicate that Mel protects the integrity of the EPs and attenuates IVDD by binding to the Mel receptors in the EPs. It may alleviate the inflammatory response and matrix degradation of EPCs activated by NF-κB pathway.

Strontium-calcium phosphate hybrid cement with enhanced osteogenic and angiogenic properties for vascularised bone regeneration.

Vascularized bone tissue engineering is regarded as one of the optimal treatment options for large bone defects. The lack of angiogenic properties and unsatisfactory physicochemical performance restricts calcium phosphate cement (CPC) from application in vascularized bone tissue engineering. Our previous studies have developed a starch and BaSO4 incorporated calcium phosphate hybrid cement (CPHC) with improved mechanical strength and handling properties. However, the bioactivity-especially the angiogenic ability-is still absent and requires further improvement. Herein, based on the reported CPHC and the osteogenic and angiogenic properties of strontium (Sr) ions, a strontium-enhanced calcium phosphate hybrid cement (Sr-CPHC) was developed to improve both biological and physicochemical properties of CPC. Compared to CPC, the initial setting time of Sr-CPHC was prolonged from 2.2 min to 20.7 min. The compressive strength of Sr-CPHC improved from 11.21 MPa to 45.52 MPa compared with CPC as well. Sr-CPHC was biocompatible and showed promotion of alkaline phosphatase (ALP) activity, calcium nodule formation and osteogenic relative gene expression, suggesting high osteogenic-inductivity. Sr-CPHC also facilitated the migration and tube formation of human umbilical vein endothelial cells (HUVECs) in vitro and up-regulated the expression of the vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang-1). In vivo evaluation showed marked new bone formation in a rat calvarial defect model with Sr-CPHC implanted. Sr-CPHC also exhibited enhancement of neovascularization in subcutaneous connective tissue in a rat subcutaneous implantation model. Thus, the Sr-CPHC with the dual effects of osteogenesis and angiogenesis shows great potential for clinical applications such as the repair of ischemic osteonecrosis and critical-size bone defects.

SIRT3 mitigates intervertebral disc degeneration by delaying oxidative stress-induced senescence of nucleus pulposus cells.

Senescence of nucleus pulposus (NP) cells (NPC) is a major cause of intervertebral disc degeneration (IVDD), so delay NPC senescence may be beneficial for mitigating IVDD. We studied the effect and mechanism of silent information regulator 2 homolog 3 (SIRT3) on NPC senescence in vivo and in vitro. First, we observed SIRT3 expression in normal and degenerated NPC with immunohistochemical and immunofluorescence staining. Second, using SIRT3 lentivirus transfection, reactive oxygen species probe, senescence-associated ß-galactosidase staining, polymerase chain reaction, and western blot to observe the oxidative stress, senescence, and degeneration degree among groups. Subsequently, pretreatment with adenosine monophosphate-activated protein kinase (AMPK) agonists and inhibitors, observing oxidative stress, senescence, and degeneration degree among groups. Finally, the IVDD model was constructed and divided into Ctrl, Vehicle, LV-shSIRT3, and LV-SIRT3 groups. X-ray and magnetic resonance imaging scans were performed on rat's tails after 1 week; hematoxylin and eosin and safranin-O staining were used to evaluate the degree of IVDD; immunofluorescence staining was used to observe SIRT3 expression; immunohistochemical staining was used to observe oxidative stress, senescence, and degeneration degree of NP. We found that SIRT3 expression is reduced in degenerated NP tissues but increased in H2 O2 -induced NPC. Moreover, SIRT3 upregulation decreased oxidative stress, delayed senescence, and degeneration of NPC. In addition, activation of the AMPK/PGC-1α pathway can partially mitigate the NPC oxidative stress, senescence, and degeneration caused by SIRT3 knockdown. The study in vivo revealed that local SIRT3 overexpression can significantly reduce oxidative stress and ECM degradation of NPC, delay NPC senescence, thereby mitigating IVDD. In summary, SIRT3 mediated by the AMPK/PGC-1α pathway mitigates IVDD by delaying oxidative stress-induced NPC senescence.

Single door laminoplasty plus posterior fusion for posterior atlantoaxial dislocation with congenital malformation: A case report and review of literature.

BACKGROUND: Posterior atlantoaxial dislocation (PAD) is a rare type of upper cervical spine disease. We sought to describe a unreported case of old PAD with os odontoideum (OO) and atlas hypoplasia (AH) and our unique treatment approach consisting of C1 single door laminoplasty with C1-3 posterior fixation and fusion. CASE SUMMARY: A 70-year-old male patient who suffered from progressive aggravating numbness and limb weakness for 4 years without trauma, was diagnosed with old PAD with OO and AH. The patient underwent closed reduction and C1 single door laminoplasty with C1-3 posterior fixation and fusion instead of C1 laminectomy with occipitocervical fusion. During the 3-year follow-up, he was able to walk by himself instead of using a wheelchair and with a ± 25° range of head rotation as well as a ± 10° range of flexion-extension. Three-year follow-up images showed satisfactory reduction and fusion. CONCLUSION: C1 single door laminoplasty with cervical fusion in PAD combined with spinal cord compression could be a suitable and effective surgical option. Compared with laminectomy and occipitocervical fusion, it retains more cervical range of motion, has a smaller incision and provides an adequate bone grafting space for atlantoaxial fusion.

Aspirin-Mediated Attenuation of Intervertebral Disc Degeneration by Ameliorating Reactive Oxygen Species In Vivo and In Vitro.

Intervertebral disc (IVD) degeneration (IDD) is a major cause of low back pain. The pathogenesis of IDD is associated with the disturbance of reactive oxygen species (ROS) equilibrium, inflammation, and matrix loss. Aspirin is a nonsteroidal anti-inflammatory drug that effectively inhibits inflammation and oxidative stress and has been widely used for the treatment of back pain. Therefore, we hypothesize that aspirin reverses the IDD process via antioxidative and anti-inflammatory effects on the AMPK signaling pathway. In vitro, aspirin diminished cellular oxygen free radicals (ROS, nitric oxide (NO)) and inflammatory cytokines (interleukin- (IL-) 1ß and IL-6 and tumor necrosis factor alpha (TNF-α)) induced by lipopolysaccharides (LPS) in nucleus pulposus cells (NPCs). We found that aspirin preserved the extracellular matrix (ECM) content of collagen type II (COL2) and aggrecan while inhibiting the expression of matrix-degenerating enzymes, including matrix metalloproteinase 3 and 13 (MMP-3 and MMP-13) and A disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS-4, ADAMTS-5). Aspirin significantly promoted the ratios of p-AMPK to AMPK and p-ACC to ACC expression in NPCs. Furthermore, pretreatment with the AMPK inhibitor compound C abrogated the antioxidant effects of aspirin. In vivo, an IDD model was established in Sprague-Dawley rats via percutaneous disc puncture with the 20-gauge needle on levels 8-9 and 9-10 of the coccygeal vertebrae. Imaging assessment showed that after aspirin treatment, improvements in disc height index (DHI) ranged from 1.22-fold to 1.54-fold and nucleus pulposus signal strength improved from 1.26-fold to 1.33-fold. Histological analysis showed that aspirin treatment prevented the loss of COL2 and decreased MMP-3 and MMP-13, inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), IL-1ß, and TNF-α expression in the IVD tissues. These results suggest that treatment with aspirin could reverse the IDD process via the AMPK signaling pathway, which provides new insights into the potential clinical applications of aspirin, particularly for IDD treatment.

Protein phosphatase 2A as a new target for downregulating osteoclastogenesis and alleviating titanium particle-induced bone resorption.

Receptor activator of nuclear factor-кB ligand (RANKL)-induced osteoclastogenesis is believed to play a critical role in osteolytic diseases including peri-prosthetic osteolysis (PPO), the primary reason for implant failure and revision surgery. In this study, we observed that protein phosphatase 2A (PP2A), a major serine-threonine phosphatase, was highly expressed in human periprosthetic interface membranes with aseptic loosening and in a murine osteolysis model induced by titanium particle irritation. PP2A inhibition effectively alleviated titanium particle-induced bone destruction at osteolytic sites. In addition, PP2A downregulation significantly decreased osteoclast numbers and RANKL expression, compared with in animals treated with only titanium. Mechanistically, a PP2A selective inhibitor or PP2A siRNA suppressed osteoclastogenesis and alleviated osteoclastic resorption by inhibiting the RANKL-induced nuclear factor-кB and c-Jun N-terminal kinase signaling pathways. Downstream NFATc1 and c-Fos expression were also substantially suppressed by PP2A inhibition or knockdown. Our findings support the importance of PP2A during osteoclastogenesis, identifying PP2A as a novel target for treating particle-induced or other osteoclast-mediated bone resorption diseases. STATEMENT OF SIGNIFICANCE: Excessive osteoclast activation disrupts bone homeostasis and leads to osteoclast-mediated bone resorption diseases, such as peri-prosthetic osteolysis, regarded as the primary reason for implant failure and revision surgery. Here, we firstly demonstrated protein phosphatase 2A (PP2A), a major serine-threonine phosphatase, was highly expressed in human periprosthetic interface membranes with aseptic loosening and murine osteolysis model. Moreover, PP2A inhibition effectively alleviated titanium particle-induced bone destruction and decreased osteoclast numbers. Meanwhile, a PP2A selective inhibitor or PP2A siRNA suppressed osteoclastogenesis and alleviated osteoclastic resorption by inhibiting the nuclear factor-кB and c-Jun N-terminal kinase signaling pathways. Thus, PP2A is involved in osteoclastogenesis and could be a promising target for regulating bone homeostasis and osteolytic responses.

Naturally occurring antiviral drug resistance in HIV patients who are mono-infected or co-infected with HBV or HCV in China.

Drug resistance mutations (DRMs) may reduce the efficacy of antiviral therapy. However, the studies focused on naturally occurring, pre-existing DRMs among co-infected patients in China are limited. To investigate DRMs prevalence in treatment-naïve human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) mono- and co-infected patients in China, a total of 570 patients were recruited for this study. DRMs sequences were amplified and successfully sequenced in 481 of these patients, who were grouped into three cohorts: (i) The HBV cohort included 100 HIV/HBV co-infected and 110 HBV mono-infected patients who were sequenced for HBV; (ii) The HCV cohort included 91 patients who were HIV/HCV co-infected and 72 who were HCV mono-infected for HCV sequencing; and (iii) The HIV cohort included 39 HIV mono-infected, 22 HIV/HCV, and 47 HIV/HBV co-infected patients for HIV sequencing. Next-generation sequencing and Sanger sequencing were used in this study. The results showed that in the HCV cohort, HCV genotypes 6a (P < 0.001) and 3b (P = 0.004) were more prevalent in HIV/HCV co-infected patients, however, the prevalence of HBV and HIV genotypes were similar within the HBV and HIV cohorts. HBV DRMs prevalence was significantly higher in HIV/HBV co-infected than HBV mono-infected patients (8.0% vs 0.9%, P = 0.015), whereas HCV and HIV DRMs did not differ within the HCV and HIV cohort (P > 0.05). This study revealed that HBV DRMs were more prevalent in HIV/HBV co-infected patients in China, while DRMs in HCV and HIV patients did not differ. Further dynamic surveillance of DRMs may be needed.

Prolactin inhibits the progression of intervertebral disc degeneration through inactivation of the NF-κB pathway in rats.

Intervertebral disc degeneration (IVDD) is one of the key predisposing factors for low back pain. Although the exact mechanism remains unclear, inflammatory response and nucleus pulposus (NP) apoptosis are known to play important roles in this process. Prolactin protects against inflammation-associated chondrocyte apoptosis in arthritis. Based on prior studies, we hypothesized that prolactin might have therapeutic effects on IVDD by inhibiting the apoptosis of degenerative human disc NP cells. An experimental model of IVDD was established in 3-month-old Sprague-Dawley rats by submitting them to percutaneous disc puncture with a 20-gauge needle on levels 7-8 and 8-9 of the coccygeal vertebrae. Then the rats were injected with 20 or 200 ng prolactin on a weekly basis. Radiologic and histologic analyses were performed on days 4, 7, 14, and 28. The expression of prolactin and its receptor was analyzed in human tissue obtained from symptomatic patients undergoing microencoscopy discectomy, or from scoliosis patients undergoing deformity correction surgery. The results showed that intradiscal injection of prolactin maintained disc height and the mean signal intensity of the punctured disc. Histological analysis indicated that prolactin treatment significantly retained the complete structure of the NP and annulus fibrosus compared with the vehicle group. In addition, more collagen II, but fewer collagen I-containing tissues were detected in the prolactin treatment groups compared to the vehicle group. Moreover, low levels of tumor necrosis factor-α, interleukin-1ß, cleaved-caspase 3, and TUNEL staining were observed in the prolactin treatment groups. We also demonstrated that prolactin impaired puncture-induced inflammation and cell apoptosis by downregulating activation of the NF-κB pathway. The degenerated NP tissues from patients had decreased expression of prolactin and its receptor, whereas expression was increased in the NP tissues removed from scoliosis patients. These results suggest that prolactin may be a novel therapeutic target for the treatment of IVDD.

Inhibitory effects of melatonin on titanium particle-induced inflammatory bone resorption and osteoclastogenesis via suppression of NF-κB signaling.

Wear debris-induced peri-implant osteolysis challenges the longevity of implants. The host response to wear debris causes chronic inflammation, promotes bone resorption, and impairs bone formation. We previously demonstrated that melatonin enhances bone formation and attenuates wear debris-induced bone loss in vivo. However, whether melatonin inhibits chronic inflammation and bone resorption at sites of wear debris-induced osteolysis remains unclear. In this study, we examined the potential inhibitory effects of melatonin on titanium particle-induced inflammatory osteolysis in a murine calvarial model and on RANKL-induced osteoclastic formation in bone marrow-derived macrophages. We found that the exogenous administration of melatonin significantly inhibited wear debris-induced bone resorption and the expression of inflammatory cytokines in vivo. Additionally, melatonin inhibited RANKL-induced osteoclast differentiation, F-actin ring formation, and osteoclastic resorption in a concentration-dependent manner in vitro. We also showed that melatonin blocked the phosphorylation of IκB-α and p65, but not IKKα, and significantly inhibited the expression of NFATc1 and c-Fos. However, melatonin had no effect on MAPK or PI3K/AKT signaling pathways. These results provide novel mechanistic insight into the anti-inflammatory and anti-bone resorptive effects of melatonin on wear debris-induced bone loss and provide an evidence-based rationale for the protective effects of melatonin as a treatment for peri-implant osteolysis. STATEMENT OF SIGNIFICANCE: Wear debris-induced chronic inflammation, osteoclastic activation and osteoblastic inhibition have been identified as critical factors of peri-implant bone loss. We previously demonstrated that melatonin, a bioactive indolamine secreted mainly by the pineal gland, activates Wnt/ß-catenin signaling pathway and enhances bone regeneration at osteolytic site in vivo. In the current study, we further demonstrated that melatonin significantly suppresses wear debris-induced bone resorption and inflammatory cytokine expression in vivo. In addition, melatonin inhibits receptor activator of nuclear factor kappa-B ligand induced osteoclast formation and osteoclastic bone resorption in vitro. Meanwhile, we found that melatonin mediates its anti-inflammation and anti-bone resorption effects by abrogating nuclear factor kappa-B activation. These results further support the protective effects of melatonin on wear debris-induced peri-implant bone loss, and strongly suggest that melatonin could be considered as a potential candidate for the prevention and treatment of wear debris-induced osteolysis and subsequent aseptic loosening.

Downregulation of miR-106b attenuates inflammatory responses and joint damage in collagen-induced arthritis.

Objective: miRNAs are small, signal-strand, non-coding RNAs that function in post-transcriptional regulation. We analysed the in vivo effect of miR-106b (miR-106b-5p) on inflammatory bone loss in CIA mice. Methods: CIA mice are developed by injecting DAB/1 mice with bovine type II collagen containing Freund's adjuvant and then the in vivo effect of miR-106b is examined. On day 22, mice were given lentiviral negative control, lentiviral-mediated miR-106b mimics or lentiviral-mediated miR-106b inhibitor via orbital injection on a weekly basis. Morphological changes in the ankle joints were assessed via micro-CT and histopathology and cytokine expression levels were examined via immunohistochemical staining, ELISA or flow cytometric analysis. miR-106b and osteoclastic-related gene expression was evaluated via quantitative real-time PCR. Results: CIA mice were found to have increased miR-106b expression and CIA-associated bone loss and inflammatory infiltration. miR-106b inhibitor treatment markedly decreased arthritis incidence and attenuated bone destruction and histological severity compared with the control group. Moreover, miR-106b inhibitor treatment suppressed RANK ligand (RANKL) expression, increased osteoprotegerin (OPG) expression and reduced the RANKL:OPG ratio in CIA mice. miR-106b inhibition also significantly decreased inflammatory mediator production in joint sections and reduced serum pro-inflammatory cytokine levels when compared with the control group. Additionally, miR-106b inhibition decreased tartrate-resistant acid phosphatase-positive cell numbers and suppressed murine bone marrow macrophage differentiation. Conclusion: These findings indicate that miR-106b inhibition can ameliorate CIA-associated inflammation and bone destruction and thus may serve as a potential therapeutic for human RA treatment.

Titanium particle-induced osteogenic inhibition and bone destruction are mediated by the GSK-3ß/ß-catenin signal pathway.

Wear debris-induced osteogenic inhibition and bone destruction are critical in the initiation of peri-prosthetic osteolysis. However, the molecular mechanism underlying this phenomenon is poorly understood. In this study, we analyzed the involvement of the GSK-3ß/ß-catenin signal pathway, which is important for bone formation in this pathological condition. We established a titanium (Ti) particle-stressed murine MC3T3-E1 cell culture system and calvariae osteolysis model to test the hypothesis that Ti particle-induced osteogenic inhibition and bone destruction are mediated by the GSK-3ß/ß-catenin signal pathway. Our findings showed that Ti particles reduced osteogenic differentiation induced by osteogenesis-related gene expression, alkaline phosphatase activity and matrix mineralization, as well as pSer9-GSK-3ß expression and ß-catenin signal activity. Downregulation of GSK-3ß activity attenuated Ti particle-induced osteogenic inhibition, whereas the ß-catenin inhibitor reversed this protective effect. Moreover, the GSK-3ß/ß-catenin signal pathway mediated the upregulation of RANKL and downregulation of OPG in Ti particle-stressed MC3T3-E1 cells. In addition, our in vivo results showed that Ti particles induced bone loss via regulating GSK-3ß and ß-catenin signals. Based on these results, we concluded that the GSK-3ß/ß-catenin signal pathway mediates the adverse effects of Ti particles on osteoblast differentiation and bone destruction, and can be used as a potential therapeutic target for the treatment of peri-prosthetic osteolysis.