Mrgprb2-mediated mast cell activation exacerbates Modic changes by regulating immune niches.

Modic changes are radiographic features associated with microfracture, low-virulence organism infection and chronic inflammation with inflammatory cell infiltration in the vertebral endplate region. Mast cells, as innate immune cells similar to macrophages, are present in painful degenerated intervertebral discs. However, the involvement and mechanisms of mast cells in the development of Modic changes remain unclear. Herein, we found increased mast cell infiltration in samples from patients with Modic changes and in mouse models of Modic changes. To clarify the role of mast cells in the progression of Modic changes, we used mast cell-deficient (KITW-SH/W-SH) mice to construct a model of Modic changes and found that the severity of Modic changes in KITW-SH/W-SH mice was significantly lower than that in WT mice. These findings were further supported by the use of a mast cell-specific activator (compound 48/80) and a stabilizer (cromolyn). Furthermore, we found that mast cells were not activated via the classic IgE pathway in the Modic change models and that Mrgprb2 is the specific receptor for mast cell activation reported in recent studies. Then, we utilized Mrgprb2 knockout mice to demonstrate that Mrgprb2 knockout inhibited mast cell activation and thus reduced the degree of Modic changes. Transcriptomic sequencing revealed aberrant PI3K-AKT and MAPK pathway activation in the Mrgprb2-deficient mast cells. Additionally, Mrgpbrb2-activated mast cells regulate immune niches by recruiting macrophages, promoting M1 polarization and reducing M2 polarization, thereby promoting the progression of Modic changes. These findings suggest that mast cells may serve as a novel therapeutic target for addressing Modic changes.

FATP2 regulates Osteoclastogenesis by increasing lipid metabolism and ROS production.

Lipid metabolism plays a crucial role in maintaining bone homeostasis, particularly in osteoclasts (OCs) formation. Here, we found the expression level of FATP2, a transporter for long-chain and very-long-chain fatty acids, was significantly upregulated during OC differentiation and in the bone marrow of mice fed a high-fat diet (HFD). Notably, the use of FATP2 siRNA or a specific inhibitor (Lipofermata) resulted in significant inhibition of OC differentiation while only slightly affecting osteoblasts (OBs). In pathological models of bone loss induced by LPS or OVX, in vivo treatment with Lipofermata was able to rescue the loss of bone mass by inhibiting OC differentiation. RNA sequencing (RNA-seq) revealed that Lipofermata reduced fatty acid ß-oxidation and inhibited energy metabolism, while regulating reactive oxygen species (ROS) metabolism to decrease ROS production, ultimately inhibiting OC differentiation. Treatment with Lipofermata, either in vivo or in vitro, effectively rescued the overactivation of OCs, indicating that FATP2 regulated OC differentiation by modulating fatty acid uptake and energy metabolism. These findings suggested that targeting FATP2 may represent a promising therapeutic approach for pathological osteoporosis.

The inhibition of osteoclastogenesis by Lipofermata, a FATP2 inhibitor, was achieved through the reprogramming of energy metabolism and regulation of ROS levels. In both pathological bone loss and HFD-induced osteoporosis models, the expression levels of FATP2 were significantly upregulated and Lipofermata demonstrated potential therapeutic effects in the pathological bone loss model.

In vivo therapy of osteosarcoma using anion transporters-based supramolecular drugs.

BACKGROUND: Osteosarcoma represents a serious clinical challenge due to its widespread genomic alterations, tendency for drug resistance and distant metastasis. New treatment methods are urgently needed to address those treatment difficulties in osteosarcoma to improve patient prognoses. In recent years, small-molecule based anion transporter have emerged as innovative and promising therapeutic compound with various biomedical applications. However, due to a lack of efficient delivery methods, using ion transporters as therapeutic drugs in vivo remains a major challenge. RESULT: Herein, we developed self-assembled supramolecular drugs based on small-molecule anion transporters, which exhibited potent therapeutic effect towards osteosarcoma both in vitro and in vivo. The anion transporters can disrupt intracellular ion homeostasis, inhibit proliferation, migration, epithelial-mesenchymal transition process, and lead to osteosarcoma cell death. RNA sequencing, western blot and flow cytometry indicated reprogramming of HOS cells and induced cell death through multiple pathways. These pathways included activation of endoplasmic reticulum stress, autophagy, apoptosis and cell cycle arrest, which avoided the development of drug resistance in osteosarcoma cells. Functionalized with osteosarcoma targeting peptide, the assembled supramolecular drug showed excellent targeted anticancer therapy against subcutaneous xenograft tumor and lung metastasis models. Besides good tumor targeting capability and anti-drug resistance, the efficacy of the assembly was also attributed to its ability to regulate the tumor immune microenvironment in vivo. CONCLUSIONS: In summary, we have demonstrated for the first time that small-molecule anion transporters are capable of killing osteosarcoma cells through multiple pathways. The assemblies, OTP-BP-L, show excellent targeting and therapeutic effect towards osteosarcoma tumors. Furthermore, the supramolecular drug shows a strong ability to regulate the tumor immune microenvironment in vivo. This work not only demonstrated the biomedical value of small-molecule anion transporters in vivo, but also provided an innovative approach for the treatment of osteosarcoma.

Induction of cervical disc degeneration and discogenic pain by low concentration Propionibacterium acnes infection: an in vivo animal study.

BACKGROUND: Although cervical intervertebral disc (IVD) degeneration is closely associated with neck pain, its cause remains unclear. In this study, an animal model of cervical disc degeneration and discogenic neck pain induced by a low concentration of Propionibacterium acnes (P. acnes-L) is investigated to explore the possible mechanisms of cervical discogenic pain. METHODS: Cervical IVD degeneration and discitis was induced in 8-week-old male rats in C3-C6 IVDs through the anterior intervertebral puncture with intradiscal injections of low and high concentrations of P. acnes (P. acnes-L, n = 20 and P. acnes-H, n = 15) or Staphylococcus aureus (S. aureus, n = 15), compared to control (injection with PBS, n = 20). The structural changes in the cervical IVD using micro-CT, histological evaluation, and gene expression assays after MRI scans at 2 and 6 weeks post-modeling. The P. acnes-L induced IVD degeneration model was assessed for cervical spine MRI, histological degeneration, pain-like behaviors (guarding behavior and forepaw von Frey), nerve fiber growth in the IVD endplate region, and DRG TNF-α and CGRP. RESULTS: IVD injection with P. acnes-L induced IVD degeneration with decreased IVD height and MRI T2 values. IVD injection with P. acnes-H and S. aureus both lead to discitis-like changes on T2-weighted MRI, trabecular bone remodeling on micro-CT, and osseous fusion after damage in the cartilage endplate adjacent to the injected IVD. Eventually, rats in the P. acnes-L group exhibited significant nociceptive hypersensitivity, nerve fiber ingrowth was observed in the IVD endplate region, inflammatory activity in the DRG was significantly increased compared to the control group, and the expression of the pain neurotransmitter CGRP was significantly upregulated. CONCLUSION: P. acnes-L was validated to induce cervical IVD degeneration and discogenic pain phenotype, while P. acnes-H induced was identified to resemble septic discitis comparable to those caused by S. aureus infection.

Spatial Transcriptomics of Aging Rat Ovaries Reveals Unexplored Cell Subpopulations with Reduced Antioxidative Defense.

INTRODUCTION: Ovarian aging is characterized by a gradual decline in quantity and quality of oocytes and lower chance of fertility. Better understanding the genetic modulation during ovarian aging can further address available treatment options for aging-related ovarian diseases and fertility preservation. METHODS: A novel technique spatial transcriptomics (ST) was used to investigate the spatial transcriptome features of rat ovaries. Transcriptomes from ST spots in the young and aged ovaries were clustered using differentially expressed genes. These data were analyzed to determine the spatial organization of age-induced heterogeneity and potential mechanisms underlying ovarian aging. RESULTS: In this study, ST technology was applied to profile the comprehensive spatial imaging in young and aged rat ovary. Fifteen ovarian cell clusters with distinct gene-expression signatures were identified. The gene expression dynamics of granulosa cell clusters revealed three sub-types with sequential developmental stages. Aged ovary showed a significant decrease in the number of granulosa cells from the antral follicle. Besides, a remarkable rearrangement of interstitial gland cells was detected in aging ovary. Further analysis of aging-associated transcriptional changes revealed that the disturbance of oxidative pathway was a crucial factor in ovarian aging. CONCLUSIONS: This study firstly described an aging-related spatial transcriptome changes in ovary and identified the potential targets for prevention of ovarian aging. These data may provide the basis for further investigations of the diagnosis and treatment of aging-related ovarian disorders.

A Dual-Targeted Metal-Organic Framework Based Nanoplatform for the Treatment of Rheumatoid Arthritis by Restoring the Macrophage Niche.

Inflammatory infiltration and bone destruction are important pathological features of rheumatoid arthritis (RA), which originate from the disturbed niche of macrophages. Here, we identified a niche-disrupting process in RA: due to overactivation of complement, the barrier function of VSIg4+ lining macrophages is disrupted and mediates inflammatory infiltration within the joint, thereby activating excessive osteoclastogenesis and bone resorption. However, complement antagonists have poor biological applications due to superphysiologic dose requirements and inadequate effects on bone resorption. Therefore, we developed a dual-targeted therapeutic nanoplatform based on the MOF framework to achieve bone-targeted delivery of the complement inhibitor CRIg-CD59 and pH-responsive sustained release. The surface-mineralized zoledronic acid (ZA) of ZIF8@CRIg-CD59@HA@ZA targets the skeletal acidic microenvironment in RA, and the sustained release of CRIg-CD59 can recognize and prevent the complement membrane attack complex (MAC) from forming on the surface of healthy cells. Importantly, ZA can inhibit osteoclast-mediated bone resorption, and CRIg-CD59 can promote the repair of the VSIg4+ lining macrophage barrier to achieve sequential niche remodeling. This combination therapy is expected to treat RA by reversing the core pathological process, circumventing the pitfalls of traditional therapy.

Disc degeneration is easily occurred at the same and adjacent cephalad level in cervical spine when Modic changes are present.

OBJECTIVE: This research aimed to evaluate the influence of Modic changes (MCs) on disc degeneration at the same and adjacent cephalad levels in the cervical spine. METHODS: This research retrospectively reviewed 1036 patients with neck pain, upper limb pain, or numbness who were treated at our out-patient clinic and underwent cervical MRI and cervical anteroposterior/lateral radiography from Jan, 2016 to Jan, 2021. MCs and disc degeneration parameters at same and nearby cephalad levels of MCs were evaluated. Discs were divided into the MCs, adjacent, and control groups, and the association between MCs and disc degeneration at the same and adjacent cephalad levels was investigated. RESULTS: Of the 1036 patients whose MRI scans were reviewed, 986 met the inclusion criteria (503 women and 483 men; average age, 62.8 years; scope of 35-79 years). The prevalence of MCs in the cervical spine was 13.0% (128/986). Type I, II, III changes were observed in 38 (29.69%), 82 (64.06%), and 8 (6.25%) patients, respectively. MCs were most frequently identified at the C5-6 (59/986; 5.98%) and C6-7 (38/986; 3.85%) levels. Disc with MCs showed worse outcomes with regard to disc degeneration grade, anterior osteophyte formation than the adjacent and control groups (p < 0.05), whereas they were more severe in the adjacent group compared to normal group. CONCLUSION: Our findings indicate that MCs increased disc degeneration at the same and nearby cephalad levels in cervical spine, and the severity of degeneration at the same segment was more serious than that at the cephalad level.

Laminectomy for the Removal of Thoracic Ossification of the Ligamentum Flavum (TOLF) Using Ultrasonic and Conventional Osteotomes.

Thoracic ossification of the ligamentum flavum (TOLF) is a common cause of progressive thoracic myelopathy. TOLF is typically treated with surgical decompression. A variety of surgical techniques, including laminoplasty, laminectomy, and lamina fenestration, are used for the effective treatment of TOLF. However, traditional methods are associated with a substantial risk of perioperative complications, including dural laceration and/or iatrogenic spinal cord injury. Therefore, it is important to develop an efficient and secure surgical technique for TOLF. Herein, we describe a method for laminectomyperformed at the thoracic spine using an ultrasonic osteotome combined with a conventional osteotome. This technique can reduce intraoperative complications. This is a relatively safe and easy-to-learn method that should be recommended for the treatment of TOLF.

The deubiquitinase UCHL1 negatively controls osteoclastogenesis by regulating TAZ/NFATC1 signalling.

The ubiquitin‒proteasome system (UPS) plays a key role in maintaining protein homeostasis and bone remodelling. However, the role of deubiquitinating enzymes (DUBs) in bone resorption is still not well defined. Here, we identified the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) as a negative regulator of osteoclastogenesis by using the GEO database, proteomic analysis, and RNAi. Osteoclast-specific UCHL1 conditional knockout mice exhibited a severe osteoporosis phenotype in an ovariectomized model. Mechanistically, UCHL1 deubiquitinated and stabilized the transcriptional coactivator with PDZ-binding motif (TAZ) at the K46 residue, thereby inhibiting osteoclastogenesis. The TAZ protein underwent K48-linked polyubiquitination, which was degraded by UCHL1. As a substrate of UCHL1, TAZ regulates NFATC1 through a nontranscriptional coactivator function by competing with calcineurin A (CNA) for binding to NFATC1, which inhibits NFATC1 dephosphorylation and nuclear transport to impede osteoclastogenesis. Moreover, overexpression of UCHL1 locally alleviated acute and chronic bone loss. These findings suggest that activating UCHL1 may serve as a novel therapeutic approach targeting bone loss in various bone pathological states.

Emergency surgery for a patient with a thoracic spinal epidural abscess: a case report and literature review.

A man in his early 40s visited the Emergency Department because of no motor function in his lower limbs for 10 hours. Magnetic resonance imaging of his thoracic spine showed that the thoracic spinal canal (T2-T6) was occupied, and the thoracic spinal cord was compressed. In view of the severe symptoms, we quickly completed preoperative preparations and performed a thoracic laminectomy within 24 hours of paralysis of both lower limbs. Postoperatively, the patient underwent rehabilitation exercise. Four weeks later, the patient's lower limbs had full 5/5 strength. We reviewed the related literature to summarize the clinical guidelines with spinal surgeons. Timely diagnosis of thoracic spinal epidural abscess, early surgical treatment, and anti-infection management and rehabilitation exercise are essential for the full recovery of lower limb muscle strength.

Netrin-1 mediates nerve innervation and angiogenesis leading to discogenic pain.

Objective: Discogenic low back pain (LBP) is associated with nociceptive nerve fibers that grow into degenerated intervertebral discs (IVD) but the etiopathogenesis of disease is not fully understood. The purpose of this study was to clarify the role of Netrin-1 in causing discogenic LBP. Methods: The level of nociceptive nerve innervation was examined in disc degenerative patients and rat needle-punctured models by immunohistochemistry. Nucleus pulposus (NP) cells were isolated from IVD tissues of rats and induced degeneration by interleukin-1ß (IL-1ß) or tumor necrosis factor α (TNFα). The candidate genes related to neuron outgrowth and migration were selected by Next-generation sequencing (NGS). CRISPR/Cas9 was used to knockdown Netrin-1 in NP cells. The impact of Netrin-1 on nerve innervation were evaluated with P2X2、NF200 staining and microfluidics assay. Meanwhile the CD31 staining and transwell assay were used to evaluate the impact of Netrin-1 in angiogenesis. The proteins and RNA extracted from NP cells related to catabolism and anabolism were examined by western blot assay and RT-qPCR experiment. ChIP and luciferase experiments were used to assess the intracellular transcriptional regulation of Netrin-1. Further, a needle-punctured rat model followed by histomorphometry and immunofluorescence histochemistry was used to explore the potential effect of Netrin-1 on LBP in vivo. Results: The level of nerve innervation was increased in severe disc degenerative patients while the expression of Netrin-1 was upregulated. The supernatants of NP cells stimulated with IL-1ß or TNFα containing more Netrin-1 could promote axon growth and vascular endothelial cells migration. Knocking down Netrin-1 or overexpressing transcription factor TCF3 as a negative regulator of Netrin-1 attenuated this effect. The needle-punctured rat model brought significant spinal hypersensitivity, nerve innervation and angiogenesis, nevertheless knocking down Netrin-1 effectively prevented disc degeneration-induced adverse impacts. Conclusion: Discogenic LBP was induced by Netrin-1, which mediated nerve innervation and angiogenesis in disc degeneration. Knocking down Netrin-1 by CRISPR/Cas9 or negatively regulating Netrin1 by transcription factor TCF3 could alleviate spinal hypersensitivity. The translational potential of this article: This study on Netrin-1 could provide a new target and theoretical basis for the prevention and treatment for discogenic back pain.

The Role of Hounsfield Unit in Intraoperative Endplate Violation and Delayed Cage Subsidence with Oblique Lateral Interbody Fusion.

STUDY DESIGN: Retrospective clinical case series. OBJECTIVES: To investigate the risk factors for intraoperative endplate violations and delayed cage subsidence after oblique lateral interbody fusion (OLIF) surgery. Secondly, to examine whether low Hounsfield unit (HU) values at different regions of the endplate are associated with intraoperative endplate violation or delayed cage subsidence. METHODS: 61 patients (aged 65.1 ± 9.5 years; 107 segments) who underwent OLIF with or without posterior instrumentation from May 2015 to April 2019 were retrospectively studied. Intraoperative endplate violation was measured on sagittal reconstructed computerized tomography (CT) images immediate postoperatively, while delayed cage subsidence was evaluated using lateral radiographs and defined at 1-month follow-up or later. Demographic information and clinical parameters such as age, body mass index, bone mineral density, number of surgical levels, cage dimension, disc height restoration, visual analogue scale (VAS), and HU at different regions of the endplate were obtained. RESULTS: Total postoperative cage subsidence was identified in 45 surgical levels (42.0%) in 26 patients (42.6%) up till postoperative 1-year follow-up. Low HU value at the ipsilateral epiphyseal ring was an independent risk factor for intraoperative endplate violation (P = .008) with a cut-off value of 326.21 HUs. Low HU values at the central endplate had a significant correlation with delayed cage subsidence in stand-alone cases (P = .013) with a cut-off value of 296.42 HUs. VAS scores were not different at 1 week postoperatively in cases with or without intraoperative endplate violation (3.12 ± .73 vs 2.89 ± .72, P = .166) and showed no difference at 1 year with or without delayed cage subsidence (1.95 ± .60 vs 2.26 ± .85, P = .173). CONCLUSIONS: Intraoperative endplate violation and delayed cage subsidence are not uncommon with OLIF surgery. HUs of the endplate are good predictors for intraoperative endplate violation and cage subsidence since they can represent the regional bone quality of the endplate in contact with the implant. VAS improvements were not affected by intraoperative endplate violation or delayed cage subsidence at 1-year follow-up. LEVEL OF EVIDENCE: Level III.

Red Light-Mediated Photoredox Catalysis Triggers Nitric Oxide Release for Treatment of Cutibacterium Acne Induced Intervertebral Disc Degeneration.

Intervertebral disc degeneration (IVDD) has been known as a highly prevalent and disabling disease, which is one of the main causes of low back pain and disability. Unfortunately, there is no effective cure to treat this formidable disease, and surgical interventions are typically applied. Herein, we report that the local administration of nitric oxide (NO)-releasing micellar nanoparticles can efficiently treat IVDD associated with Modic changes in a rat model established by infection with Cutibacterium acnes (C. acnes). By covalent incorporation of palladium(II) meso-tetraphenyltetrabenzoporphyrin photocatalyst and coumarin-based NO donors into the core of micellar nanoparticles, we demonstrate that the activation of the UV-absorbing coumarin-based NO donors can be achieved under red light irradiation via photoredox catalysis, although it remains a great challenge to implement photoredox catalysis reactions in biological conditions due to the complex microenvironments. Notably, the local delivery of NO can not only efficiently eradicate C. acnes pathogens but also inhibit the inflammatory response and osteoclast differentiation in the intervertebral disc tissues, exerting antibacterial, anti-inflammatory, and antiosteoclastogenesis effects. This work provides a feasible means to efficiently treat IVDD by the local administration of NO signaling molecules without resorting to a surgical approach.

Small Preoperative Dural Sac Cross-Sectional Area and Anteriorly Placed Fusion Cages Are Risk Factors for Indirect Decompression Failure after Oblique Lateral Interbody Fusion.

OBJECTIVE: 1) To investigate if implant-related factors such as cage size and cage position are associated with radiologic improvement after indirect decompression with oblique lateral interbody fusion (OLIF). 2) To investigate the risk factors associated with indirect decompression failure (IDF) at the surgical levels after OLIF. METHODS: From February 2015 to December 2019, 92 consecutive patients (188 levels) with lumbar spinal stenosis who underwent indirect decompression via OLIF with or without posterior instrumentation were studied retrospectively. Radiographic variables were measured preoperatively and postoperatively. The radiographic results were compared for cages with different heights and positions. IDF was defined as revision surgery within 6 months or persistent compressive symptoms 6 months after surgery. RESULTS: Postoperative improvements were observed in all measured radiographic parameters except for segmental lordosis. Taller cages were associated with more shrinkage of the bulging disc and greater increase in dural sac diameter. Cages placed posteriorly showed larger postoperative subarticular diameters. Twelve patients (16 levels) had IDF. Multivariate logistic regression showed that after adjusting for age, sex, and body mass index, smaller preoperative dural sac cross-sectional area and anterior positioning of cages were both independent risk factors for IDF. CONCLUSIONS: OLIF is an effective procedure for indirect decompression. To avoid reoperation for lumbar spinal stenosis, surgeons should aim to place the center of the cage at the posterior half of the lower endplate. Surgical levels with a preoperative dural sac cross-sectional area <44 mm2 may not be suitable for indirect decompression.

Methyl 3,4-dihydroxybenzoate inhibits RANKL-induced osteoclastogenesis via Nrf2 signaling in vitro and suppresses LPS-induced osteolysis and ovariectomy-induced osteoporosis in vivo.

Osteoporosis deteriorates bone mass and biomechanical strength and is life-threatening to the elderly. In this study, we show that methyl 3,4-dihydroxybenzoate (MDHB), an antioxidant small-molecule compound extracted from natural plants, inhibits receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclastogenesis in vitro. Furthermore, MDHB attenuates the activation of mitogen-activated protein kinase (MAPK) and NF-κB pathways by reducing the levels of reactive oxygen species (ROS), which leads to downregulated protein expression of c-Fos and nuclear factor of activated T cells c1 (NFATc1). We also confirm that MDHB upregulates the protein expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), an important transcription factor involved in ROS regulation, by inhibiting the ubiquitination-mediated proteasomal degradation of Nrf2. Next, animal experiments show that MDHB has an effective therapeutic effect on lipopolysaccharide (LPS)- and ovariectomized (OVX)-induced bone loss in mice. Our study demonstrates that MDHB can upregulate Nrf2 and suppress excessive osteoclast activity in mice to treat osteoporosis.

Anterior cervical transpedicular screw fixation system in subaxial cervical spine: A finite element comparative study.

Multilevel cervical corpectomy has raised the concern among surgeons that reconstruction with the anterior cervical screw plate system (ACSPS) alone may fail eventually. As an alternative, the anterior cervical transpedicular screw (ACTPS) has been adopted in clinical practice. We used the finite element analysis to investigate whether ACTPS is a more reasonable choice, in comparison with ACSPS, after a 2-level corpectomy in the subaxial cervical spine. These 2 types of implantation models with the applied 75 N axial pressure and 1 N • m pure moment of the couple were evaluated. Compared with the intact model, the range of motion (ROM) at the operative segments (C4-C7) decreased by 97.5% in flexion-extension, 91.3% in axial rotation, and 99.3% in lateral bending in the ACTPS model, whereas it decreased by 95.1%, 73.4%, 96.9% in the ACSPS model respectively. The ROM at the adjacent segment (C3/4) in the ACTPS model decreased in all motions, while that of the ACSPS model increased in axial rotation and flexion-extension compared with the intact model. Compared to the ACSPS model, whose stress concentrated on the interface between the screws and the titanium plate, the stress of the ACTPS model was well-distributed. There was also a significant difference between the maximum stress value of the 2 models. ACTPS and ACSPS are biomechanically favorable. The stability in reducing ROM of ACTPS may be better and the risk of failure for internal fixator is relatively low compared with ACSPS fixation except for under lateral bending in reconstruction the stability of the subaxial cervical spine after 2-level corpectomy.

Sigma-1 receptor attenuates osteoclastogenesis by promoting ER-associated degradation of SERCA2.

Sigma-1 receptor (Sigmar1) is a specific chaperone located in the mitochondria-associated endoplasmic reticulum membrane (MAM) and plays a role in several physiological processes. However, the role of Sigmar1 in bone homeostasis remains unknown. Here, we show that mice lacking Sigmar1 exhibited severe osteoporosis in an ovariectomized model. In contrast, overexpression of Sigmar1 locally alleviated the osteoporosis phenotype. Treatment with Sigmar1 agonists impaired both human and mice osteoclast formation in vitro. Mechanistically, SERCA2 was identified to interact with Sigmar1 based on the immunoprecipitation-mass spectrum (IP-MS) and co-immunoprecipitation (co-IP) assays, and Q615 of SERCA2 was confirmed to be the critical residue for their binding. Furthermore, Sigmar1 promoted SERCA2 degradation through Hrd1/Sel1L-dependent ER-associated degradation (ERAD). Ubiquitination of SERCA2 at K460 and K541 was responsible for its proteasomal degradation. Consequently, inhibition of SERCA2 impeded Sigmar1 deficiency enhanced osteoclastogenesis. Moreover, we found that dimemorfan, an FDA-approved Sigmar1 agonist, effectively rescued bone mass in various established bone-loss models. In conclusion, Sigmar1 is a negative regulator of osteoclastogenesis, and activation of Sigmar1 by dimemorfan may be a potential treatment for osteoporosis in clinical practice.

Different responses of cervical intervertebral disc caused by low and high virulence bacterial infection: a comparative study in rats.

The aims of this study were to investigate the outcomes of low- and high-virulence bacterial cervical intervertebral discs (IVDs) infection and its association with cervical IVDs degeneration in rats. A total of 75 clean grade male rats were used to establish the corresponding animal models of low and high virulent bacterial cervical disc infection via an anterior cervical approach, with injection of Propionibacterium acnes (P. acnes) and Staphylococcus epidermidis (S. epidermidis) with a 29 G needle to cervical IVDs. Specimens were collected for evaluation of Blood routine (Blood-RT), histological staining, and gene expression assays after a magnetic resonance imaging (MRI) scan. There were no statistical differences in all groups in white blood cells (WBC) at 2 and 6 weeks postoperatively (P = 0.136). The highest percentage of neutrophils was found in the S. epidermidis group at 2 weeks postoperatively (P = 0.043). MRI and histology showed that at 6 weeks postoperatively, the puncture group and P. acnes group had similar disc degeneration. In the S. epidermidis group, the disc and subchondral bone structure had been destroyed and bony fusion had occurred after the discitis. The upregulation of pro-inflammatory factor expression had the strongest effect of S. epidermidis on the early stage, while the upregulation in the puncture and P. acnes groups was more persistent. P. acnes infection of the cervical IVDs can lead to degenerative changes, whereas S. epidermidis infection leads to the manifestation of septic discitis. The correlation between P. acnes infection and cervical IVDs degeneration found in clinical studies was confirmed.

Urolithin A Promotes Angiogenesis and Tissue Regeneration in a Full-Thickness Cutaneous Wound Model.

The treatment of chronic wound is an important topic of current clinical issue. Neovascularization plays a crucial role in skin wound healing by delivering fresh nutrients and oxygen to the wound area. The aim of this study was to investigate the mechanisms of urolithin A (UA) in angiogenesis during wound healing. The results of in vitro experiments showed that treatment with UA (5-20 µM) promoted the proliferation, migration, and angiogenic capacity of HUVECs. Furthermore, we investigated the effect of UA in vivo using a full-thickness skin wound model. Subsequently, we found that UA promoted the regeneration of new blood vessels, which is consistent with the results of accelerated angiogenesis in vitro experiments. After UA treatment, the blood vessels in the wound are rapidly formed, and the deposition and remodeling process of the collagen matrix is also accelerated, which ultimately promotes the effective wound healing. Mechanistic studies have shown that UA promotes angiogenesis by inhibiting the PI3K/AKT pathway. Our study provides evidence that UA can promote angiogenesis and skin regeneration in chronic wounds, especially ischemic wounds.

[Establishment of finite element model of anterior cervical transpedicular system for reconstruction of cervical stability after subtotal resection of two segments of lower cervical spine].

OBJECTIVE: To establish the fixation model of anterior cervical transpedicular system (ACTPS) after subtotal resection of two segments of lower cervical spine(C3-C7) in order to provide a finite element modeling method for anterior cervical reconstruction. METHODS: The CT data of the cervical segment (C1-T1) of a 30-year-old adult healthy male volunteer was collected. Used Mimics 10.0, Rapidform XOR3, HyperMesh 10.0, CATIA5V19 and ANSYS 14.0 to establish the three-dimensional nonlinear complete model of lower cervical spine(C3-C7) as the intact group. The number of units and nodes of the complete model were recorded. After the effectiveness of the complete model was verified, the C5 and C6 vertebral subtotal resection was performed, and the ACTPS model was established as the ACTPS group. The axial force of 75 N and moment couple of 1N·m was loaded on the upper surface of C3 in intact group and ACTPS group, the range of motion(ROM)and stress distribution in states of flexion extension, lateral flexion, rotation was compared between two groups. RESULTS: There were 85 832 elements and 23 612 nodes in the complete model of lower cervical spine(C3-C7) which was established in this experiment. The stress distribution of ACTPS internal fixation model was relatively uniform. Comparing with the intact group, the overall range of motion in ACTPS group was decreased in flexion extension, lateral flexion and rotation directions, and the corresponding compensation of adjacent C3,4 segment was increased slightly. CONCLUSION: The stress distribution of ACTPS fixation system is uniform, there is no stress concentration area at the joint of screw and titanium plate, and the fracture risk of internal fixation is low. It is suitable for stability reconstruction after anterior decompression of two or more cervical segments.