In vitro and in vivo effects of hyperglycemia and diabetes mellitus on nucleus pulposus cell senescence

Diabetes mellitus contributes to intervertebral disc degeneration. Nucleus pulposus cell senescence plays an important role in intervertebral disc degeneration. However, the effects of hyperglycemia on human nucleus pulposus cells and the underlying process remains poorly understood. In the current study, we evaluated the effects of high glucose levels on human nucleus pulposus cell senescence in vitro and the effects of hyperglycemia on rat nucleus pulposus aging in vivo. Human nucleus pulposus cells were cultured in high-glucose medium (200 mM glucose) for 48 h. Senescence-associated β-galactosidase staining, western blot analysis, and enzyme-linked immunosorbent assays were performed to evaluate human nucleus pulposus cell senescence. Flow cytometry and enzyme-linked immunosorbent assays were used to evaluate reactive oxygen species and advanced glycation end-product levels. Transcriptome sequencing followed by bioinformatics analysis was used to understand the abnormal biological processes of nucleus pulposus cells cultured in high-glucose medium. Diabetes mellitus rat models were established and histopathological and immunohistochemical analysis was conducted to examine nucleus pulposus tissue senescence in vivo. Exposure to a high glucose concentration promoted human nucleus pulposus cell senescence and increased the senescence-related secretion phenotype in human nucleus pulposus cells in vitro and in rat nucleus pulposus tissue in vivo. Bioinformatics analysis showed that hub genes were involved in nucleus pulposus cell cycle activities and cell senescence. The results suggest that appropriate blood glucose control may be key to preventing intervertebral disc degeneration in diabetic patients.

Zaprinast and avanafil increase the vascular endothelial growth factor, vitamin D3, bone morphogenic proteins 4 and 7 levels in the kidney tissue of male rats applied the glucocorticoid

Objective: This study investigated effect of zaprinast and avanafil on vascular endothelial growth factor (VEGF), bone morphogenic protein (BMP) 4 and 7, and vitamin D₃ levels against the negative effect of dexamethazone.Method: Rats were randomly divided into four groups (n = 6). Control: Empty a syringe was immersed and removed subcutaneously. Dexamethasone (DEX): 120 µg/kg DEX was injected subcutaneously once a day for 28 days. DEX + zaprinast and DEX + avanafil groups: 10 mg/kg zaprinast and avanafil were administrated to rats in addition to the same procedure in the DEX, respectively. VitaminD₃, VEGF, BMP4 and 7 levels by enzyme linked immunosorbent assay (ELISA) and angiogenesis by histopathological/immunohistochemical were evaluated.Results: BMP4 values in the DEX were lower than the other groups (p < .05). DEX + zaprinast and DEX + avanafil exhibited an increase in all the parameters compared to the control and DEX (p < .05). However, these were not significant for the DEX + zaprinast (p > .05). Also, there was a significant increase in angiogenesis in the DEX + zaprinast and DEX + avanafil.Conclusion: Zaprinast and significantly avanafil induced vitamin D₃, BMP4 and 7 levels by increasing angiogenesis in renal.

Encapsulation of Manganese Porphyrin in Chondroitin Sulfate-A Microparticles for Long Term Reactive Oxygen Species Scavenging

Introduction

Oxidative stress due to excess reactive oxygen species (ROS) is related to many chronic illnesses including degenerative disc disease and osteoarthritis. MnTnBuOE-2-PyP5+ (BuOE), a manganese porphyrin analog, is a synthetic superoxide dismutase mimetic that scavenges ROS and has established good treatment efficacy at preventing radiation-induced oxidative damage in healthy cells. BuOE has not been studied in degenerative disc disease applications and only few studies have loaded BuOE into drug delivery systems. The goal of this work is to engineer BuOE microparticles (MPs) as an injectable therapeutic for long-term ROS scavenging.

Methods

Methacrylated chondroitin sulfate-A MPs (vehicle) and BuOE MPs were synthesized via water-in-oil polymerization and the size, surface morphology, encapsulation efficiency and release profile were characterized. To assess long term ROS scavenging of BuOE MPs, superoxide scavenging activity was evaluated over an 84-day time course. In vitro cytocompatibility and cellular uptake were assessed on human intervertebral disc cells.

Results

BuOE MPs were successfully encapsulated in MACS-A MPs and exhibited a slow-release profile over 84 days. BuOE maintained high potency in superoxide scavenging after encapsulation and after 84 days of incubation at 37 °C as compared to naked BuOE. Vehicle and BuOE MPs (100 µg/mL) were non-cytotoxic on nucleus pulposus cells and MPs up to 23 µm were endocytosed.

Conclusions

BuOE MPs can be successfully fabricated and maintain potent superoxide scavenging capabilities up to 84-days. In vitro assessment reveals the vehicle and BuOE MPs are not cytotoxic and can be taken up by cells.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-022-00744-w.

The Brighton Spondylodiscitis Score Does Not Accurately Predict the Need for Surgery: A Retrospective Cohort Study in New Zealand

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Despite pyogenic spondylodiscitis potentially conferring significant morbidity, there is no consensus on optimal treatment. The Brighton Spondylodiscitis Score (BSDS) was developed to identify patients who would likely fail conservative management and therefore benefit from earlier surgical intervention. In this study, we attempt external validation of the BSDS.

METHODS

We carried out a retrospective review of all patients treated at our institution, 2010-2016, for pyogenic spondylodiscitis. 91 met inclusion criteria and 40 progressed to require surgical intervention. The BSDS was calculated for each patient allowing stratification into low-, moderate- and high-risk groups. Calibration and discrimination was assessed with ROC curve analysis and calibration plot.

RESULTS

Area under the curve (AUC) was 0.469 (0.22-0.71) in our external validation, compared with AUC 0.83 and 0.71 (CI 0.50-0.88) in the original study and test populations respectively. Only 60% of patients in the high-risk group required surgery, 50% in the moderate, and 38% of the low indicating poor calibration and predictive accuracy. Operative intervention was not higher overall in our cohort (44% vs. 32%, p = 0.14). We found greater rates of bacteraemia, more distal infection, and more advanced MRI findings in our cohort. The incidence of spondylodiscitis in our region is higher (4/100 000/year).

CONCLUSION

We failed to externally validate the BSDS in our population which is likely a result of unique population characteristics and the inherently variable pathology associated with spondylodiscitis. Clinicians must be cautious in adopting treatment algorithms developed in other health care systems that may comprise significantly different patient and pathogen characteristics.

Management of lumbar spondylolysis in the adolescent athlete: a review of over 200 cases

BACKGROUND

Spondylolysis is a defect of the pars interarticularis of vertebrae, most commonly seen at L5 and L4. The etiology of spondylolysis and isthmic spondylolisthesis is generally considered to be a result of repetitive mechanical stress to the weak portion of the vertebrae. A higher incidence of spondylolysis is observed in young athletes. Symptomatic spondylolysis can be successfully treated conservatively, but there is currently a limited consensus on treatment modalities and a lack of large-scale clinical trials.

PURPOSE

The purpose of the present study was to investigate the optimal treatment algorithm for symptomatic spondylolysis in adolescent athletes and evaluate the functional outcomes of those undergoing the nonoperative treatment.

STUDY DESIGN

A retrospective review.

PATIENT SAMPLE

Two hundred one adolescent patients ranging from age 10 to 19 involved in athletics OUTCOME MEASURES: Injury characteristics (age, mechanism, time), sports played, bone stimulator use, bony healing at 3 months on computed tomography (CT) scans, return to sports, corticosteroid injection use.

METHODS

Two hundred one adolescent athlete patients (62 females and 139 males) diagnosed with spondylolysis between 2007 and 2019 were retrospectively reviewed. Diagnosis was based on plain radiography followed by magnetic resonance imaging. All patients were treated conservatively with cessation of sports activity, thoracolumbosacral orthosis, and external bone stimulator for three months after diagnosis. CT scans were obtained for the 3-month follow-up visits to assess bony healing. Subsequently the patients received 6 weeks of rehabilitation focused on core strengthening. Symptomatic patients after the treatment were referred for steroid injections and continued with the rehabilitation protocol.

RESULTS

The most common age of injury was 15 years old, following a strong normal distribution. The most commonly played sport was football, followed by baseball/softball. The primary mechanism of injury was weight training closely followed by a football injury. The first quarter of the calendar year had the highest incidence of injuries with the most injuries occurring in March and the least occurring in December. One hundred fifty-two athletes reported using bone stimulators as prescribed, and these patients showed a significantly higher rate of bony healing on follow-up CT scans than those who did not use bone stimulators. One hundred ninety-seven patients (98%) returned to sports or similar level of activities. Thirty-seven patients (18%) received facet or epidural steroid injections due to continued pain and one patient underwent a surgical procedure. Follow-up CT scans showed 49.8% bony healing.

CONCLUSIONS

Conservative treatment of spondylolysis in adolescent athletes with cessation of sports, thoracolumbosacral orthosis, and bone stimulator followed by rehabilitation was associated with excellent outcomes in terms of return to sports.

The Genetic Architecture of the Etiology of Lower Extremity Peripheral Artery Disease: Current Knowledge and Future Challenges in the Era of Genomic Medicine

Lower extremity artery disease (LEAD), caused by atherosclerotic obstruction of the arteries of the lower limb extremities, has exhibited an increase in mortality and morbidity worldwide. The phenotypic variability of LEAD is correlated with its complex, multifactorial etiology. In addition to traditional risk factors, it has been shown that the interaction between genetic factors (epistasis) or between genes and the environment potentially have an independent role in the development and progression of LEAD. In recent years, progress has been made in identifying genetic variants associated with LEAD, by Genome-Wide Association Studies (GWAS), Whole Exome Sequencing (WES) studies, and epigenetic profiling. The aim of this review is to present the current knowledge about the genetic factors involved in the etiopathogenic mechanisms of LEAD, as well as possible directions for future research. We analyzed data from the literature, starting with candidate gene-based association studies, and then continuing with extensive association studies, such as GWAS and WES. The results of these studies showed that the genetic architecture of LEAD is extremely heterogeneous. In the future, the identification of new genetic factors will allow for the development of targeted molecular therapies, and the use of polygenic risk scores (PRS) to identify individuals at an increased risk of LEAD will allow for early prophylactic measures and personalized therapy to improve their prognosis.

Concentration of Selected Macronutrients and Toxic Elements in the Blood in Relation to Pain Severity and Hydrogen Magnetic Resonance Spectroscopy in People with Osteoarthritis of the Spine

Macronutrients and toxic elements may play an important role in the pathogenesis of osteoarthritis of the spine. The objective of this study was to evaluate the relationship between the concentrations of Ca, Mg, Pb, Cd and Hg in blood with the results of hydrogen magnetic resonance spectroscopy and the severity of pain. Patients with osteoarthritis of the spine (n = 90) and control subjects (n = 40) were studied. The concentrations of mineral components in blood were determined by atomic absorption spectrometry (ASA). Spinal pain severity was assessed using the Visual Analog Scale (VAS). Hydrogen magnetic resonance spectroscopy (¹H-MRS) was used to determine the fat/water ratio in the bodies of L1, L5 and the L4/5 intervertebral disc. The median concentration of Mg in the serum of subjects with spinal degenerative disease was significantly lower (p < 0.001) than that in healthy subjects. The median concentration of Cd in the blood of subjects with osteoarthritis of the spine was significantly higher (p < 0.05) than that in the control group. Significantly lower (p < 0.05) median molar ratios of Ca to Cd and Pb as well as Mg to Pb and Cd were observed among patients with osteoarthritis of the spine. Significant differences (p < 0.05) were observed in the value of the fat/water ratio in selected spinal structures, depending on normal or abnormal serum Ca and Mg concentrations. The study showed some abnormal macronutrient concentrations, as well as disturbed ratios of beneficial elements to toxic elements in the blood of people with osteoarthritis of the spine.

Biomechanical characteristics of 2 different posterior fixation methods of bilateral pedicle screws: A finite element analysis

BACKGROUND

To explore the biomechanical characteristics of 2 posterior bilateral pedicle screw fixation methods using finite element analysis.

METHODS

A normal L3-5 finite element model was established. Based on the verification of its effectiveness, 2 different posterior internal fixation methods were simulated: bilateral pedicle screws (model A) were placed in the L3 and L5 vertebral bodies, and bilateral pedicle screws (model B) were placed in the L3, L4, and L5 vertebral bodies. The stability and stress differences of intervertebral discs, endplates, screws, and rods between models were compared.

RESULTS

Compared with the normal model, the maximum stress of the range of motion, intervertebral disc, and endplate of the 2 models decreased significantly. Under the 6 working conditions, the 2 internal fixation methods have similar effects on the stress of the endplate and intervertebral disc, but the maximum stress of the screws and rods of model B is smaller than that of model A.

CONCLUSIONS

Based on these results, it was found that bilateral pedicle screw fixation in 2 vertebrae L3 and L5 can achieve similar stability as bilateral pedicle screw fixation in 3 vertebrae L3, L4, and L5. However, the maximum stress of the screw and rod in model B is less than that in model A, so this internal fixation method can effectively reduce the risk of fracture. The 3-dimensional finite element model established in this study is in line with the biomechanical characteristics of the spine and can be used for further studies on spinal column biomechanics. This information can serve as a reference for clinicians for surgical selection.

Da Vinci robot-assisted laparoscopic retroperitoneal debridement for lumbar septic spondylodiscitis: A two-case report

The anterior approach is one of the widely used surgical treatments for lumbar spondylodiscitis, but it has the disadvantages of large trauma and a high incidence of complications. Our experiences suggested that the laparoscopic retroperitoneal approach could be effective to overcome those disadvantages of the anterior approach. Herein, we report two cases of successfully treated lumbar pyogenic spondylodiscitis using a robot-assisted laparoscopic retroperitoneal approach. The technique utilizes a robot that allows a laparoscopic retroperitoneal approach while offering excellent high-definition images of three-dimensional vision. After the operation, both patients achieved good formation and fusion of the vertebrae. Preliminary evidence suggests that the robot-assisted laparoscopic retroperitoneal approach may be feasible for the treatment of lumbar spondylodiscitis.

A Review of free fatty acid-induced cell signaling, angiopoietin-like protein 4, and skeletal muscle differentiation

Postnatal skeletal muscle differentiation from quiescent satellite cells is a highly regulated process, although our understanding of the contribution of nutritional factors in myogenesis is limited. Free fatty acids (FFAs) are known to cause detrimental effects to differentiated skeletal muscle cells by increasing oxidative stress which leads to muscle wasting and insulin resistance in skeletal muscle. In addition, FFAs are thought to act as inhibitors of skeletal muscle differentiation. However, the precise molecular mechanisms underlying the effects of FFAs on skeletal muscle differentiation remains to be elucidated. There is a clear relationship between dietary FFAs and their ability to suppress myogenesis and we propose the hypothesis that the FFA-mediated increase in angiopoietin-like protein 4 (ANGPTL4) may play a role in the inhibition of differentiation. This review discusses the role of FFAs in skeletal muscle differentiation to-date and proposes potential mechanisms of FFA-induced ANGPTL4 mediated inhibition of skeletal muscle differentiation.

AAV-mediated expression of PFKFB3 in myofibers, but not endothelial cells, improves ischemic muscle function in mice with critical limb ischemia

6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) is a powerful driver of angiogenesis through its modulation of glycolytic metabolism within endothelial cells. Recent work has demonstrated that PFKFB3 modulates the response to muscle ischemia, however the cell specificity of these effects is not fully understood. In this study, we tested the impact of viral mediated expression of PFKFB3, driven by gene promoters specific for myofibers or endothelial cells, on ischemic hindlimb revascularization and muscle function. We hypothesized that both endothelium- and muscle-specific expression of PFKFB3 would attenuate limb pathology following femoral artery ligation. Male and female BALB/cJ mice were injected with adeno-associated virus encoding the either a green fluorescent protein (GFP) or PFKFB3 driven by either the human skeletal actin (ACTA1) or cadherin-5 (Cdh5) promoters. Four weeks after AAV treatment, mice were subjected to unilateral femoral artery ligation and limb perfusion and muscle function were assessed. Both endothelium- and muscle-specific PFKFB3 expression resulted in significantly more perfused capillaries within the ischemic limb muscle, but neither changed myofiber size/area. Muscle-specific, but not endothelium-specific, PFKFB3 expression significantly improved maximal force production in ischemic muscle (P = 0.0005). Notably, there was a significant effect of sex on maximal force levels in both cohorts of mice (P = 0.0075 and P = 0.0481), indicating that female mice had higher ischemic muscle strength compared with male mice, regardless of treatment group. Taken together, these data demonstrate that although both muscle- and endothelium-specific expression of PFKFB3 enhanced ischemic revascularization, only muscle-specific PFKFB3 expression improved muscle function.NEW & NOTEWORTHY Critical limb ischemia (CLI) carries a significant risk for limb amputation, and treatment options remain limited. We tested the impact of expression of PFKFB3 in myofibers or endothelial cells on limb pathology in mice with CLI. Although both muscle and endothelium-specific PFKFB3 expression increased perfused capillary density, only muscle-specific PFKFB3 expression improve contractile function. Regardless of treatment, female mice demonstrated better recovery from limb ischemic compared with male mice.

Spondylolysis

Spondylolysis is a bony defect of the pars interarticularis and most often results from repetitive stress. Although spondylolysis is usually asymptomatic, symptomatic spondylolysis is the most common cause of identifiable back pain in children and adolescent athletes. A thorough history and physical exam, as well as appropriate imaging studies are helpful in diagnosis. General first-ine therapy for spondylolysis is conservative and consists of rest from sports, core strengthening, as well as spinal bracing. Patients who have failed conservative therapy may consider surgical repair. This article aims to review the epidemiology, pathophysiology, presentation, and treatment options of spondylolysis.

New Trends in Aging Drug Discovery

Aging is considered the main risk factor for many chronic diseases that frequently appear at advanced ages. However, the inevitability of this process is being questioned by recent research that suggests that senescent cells have specific features that differentiate them from younger cells and that removal of these cells ameliorates senescent phenotype and associated diseases. This opens the door to the design of tailored therapeutic interventions aimed at reducing and delaying the impact of senescence in life, that is, extending healthspan and treating aging as another chronic disease. Although these ideas are still far from reaching the bedside, it is conceivable that they will revolutionize the way we understand aging in the next decades. In this review, we analyze the main and well-validated cellular pathways and targets related to senescence as well as their implication in aging-associated diseases. In addition, the most relevant small molecules with senotherapeutic potential, with a special emphasis on their mechanism of action, ongoing clinical trials, and potential limitations, are discussed. Finally, a brief overview of alternative strategies that go beyond the small molecule field, together with our perspectives for the future of the field, is provided.

Scientific literature landscape analysis of researches on oxidative stress in intervertebral disc degeneration in web of science

Oxidative stress plays a significant role in the development of disc degeneration and has attracted widespread attention since it was first researched in 2007. Our study aims to analyze the scientific output of oxidative stress in intervertebral disc degeneration (IDD) and drive future research into new publications. Publications focused on this topic were retrieved from the SCI-EXPANDED (SCI-E) of the Web of Science (WOS) core collection database and were screened according to the inclusion criteria. Bibliometric website, VOSviewer, and Citespace software were used to evaluate and visualize the results, including annual publications, citations, authors, organizations, countries, research directions, funds, and journals. As of 16 February 2022, a total of 289 original articles and reviews were included, and the overall trend of the number of publications rapidly increased. China and the United States were the leading countries for research production in worldwide. The retrieved 289 publications received 5,979 citations, with an average of 20.67 citations and an H-index of 40. The most high-yield author, organization, country, research direction, fund, and journal were Wang K from Tongji Medical College, Huazhong University of Science Technology, China, Cell Biology, National Natural Science Foundation of China, Oxidative Medicine and Cellular Longevity, respectively. The majority of most common keywords were related to the mechanisms and regulatory networks of oxidative stress. Furthermore, with accumulating evidence that demonstrates the role of oxidative stress in IDD, “mitochondria” and “senescence” are becoming the new research focus that should be paid more attention to.

Effect of IL-6 -174G/C and -572G/C variants on susceptibility to osteoarthritis in Turkish population

Osteoarthritis (OA) is a complex disorder characterized by degenerative articular cartilage in which inflammatory mechanisms play a major role in the pathogenesis. Interleukin-6 (IL6), a multifunctional cytokine, can trigger osteoclast differentiation and bone resorption. Our purpose in this study was to evaluate the association of IL-6 -174 G/C (rs1800795) and -572 G/C (rs1800796) variants with the susceptibility to OA. One hundred fifty OA patients and 150 healthy individuals were enrolled in the study. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) was used for genotyping the IL-6 gene variants. The results of analyses were evaluated for statistical significance. The pain intensity was assessed using the Visual Analogue Scale (VAS). There was a statistically significant difference in the genotype and allele frequencies of the IL-6 -174 G/C variant between patients with OA and control groups (p = 0.001, p = 0.002, respectively). IL-6 -174 G/C GG genotype and G allele were more prevalent in patients with OA. We found that the IL-6 -572 G/C variant was not different between patients and controls in either genotype distribution and allele frequency. IL-6 174 G/C and -572 G/C loci GG-GG combined genotype was significantly higher in OA patients (p = 0.00). Our study suggests that there was a strong association between the IL-6 -174 G/C variant and OA in the Turkish population. Further studies on populations of different ethnic background are necessary to prove the association of IL-6 variants with OA.

Can zaprinast and avanafil induce the levels of angiogenesis, bone morphogenic protein 2, 4 and 7 in kidney of ovariectomised rats?

OBJECTIVE

This study investigated effects of zaprinast and avanafil on angiogenesis, vascular endothelial growth factor (VEGF), bone morphogenic protein (BMP) 2, 4 and 7.

METHODS

Female rats were randomly divided into four groups (n = 6). Sham; abdomen was approximately 2 cm opened and closed. Ovariectomised (OVX); abdomen was opened 2 cm and the ovaries were cut. OVX + zaprinast and OVX + avanafil groups; after the same procedure with OVX, 10 mg/kg zaprinast and avanafil were orally administered for 2 month, respectively. Angiogenesis and the levels of VEGF, BMP2, 4 and 7 were determined.

RESULTS

VEGF, BMP2, 4 and 7 levels in OVX + zaprinast and especially OVX + avanafil groups were higher than the sham and OVX (p < .05). However, only VEGF and BMP2 levels in OVX + zaprinast group were significant according to sham (p < .05). Also, angiogenesis in OVX + zaprinast and OVX + avanafil groups was dominant according to sham and OVX (p < .05).

CONCLUSIONS

Zaprinast and avanafil induced BMP2, 4 and 7 levels synergistically with increased VEGF and angiogenesis in renal tissue.

Stimulating effects of vardenafil, tadalafil, and udenafil on vascular endothelial growth factor, angiogenesis, vitamin D3, bone morphogenic proteins in ovariectomized rats

OBJECTIVE

This study investigated the effect of vardenafil, tadalafil, and udenafil from phosphodiesterase-5 inhibitors (PDE-5Is) on bone morphogenic-protein (BMP)2 and 4 levels, along with angiogenesis in ovariectomized rat's kidney.

METHOD

Rats were randomly divided into five groups (n = 10). Sham: abdomen was opened, and closed. OVX: ovaries were removed. OVX + vardenafil, OVX + tadalafil, and OVX + udenafil groups: ovaries were removed and closed, and after 6 months from postoperative, 10 mg/kg of vardenafil, tadalafil, and udenafil were administrated as daily a single-dose for 60 days, respectively. Histopathologic and immunohistochemical examinations were performed for angiogenesis, and biochemical analysis for vascular endothelial growth-factor (VEGF), VitaminD₃, BMP2 and 4 levels in rat's kidney.

RESULTS

VEGF, BMP2 and 4, VitaminD₃, and angiogenesis were high in the all inhibitor groups compared with the sham and OVX (p < .05). However, BMP4 levels were only high in the OVX + tadalafil group (p < .05).

CONCLUSION

The results indicated that vardenafil, udenafil, and especially tadalafil increased VEGF, BMP2, and VitaminD₃ levels.

Pulmonary infection by SARS-CoV-2 induces senescence accompanied by an inflammatory phenotype in severe COVID-19: possible implications for viral mutagenesis

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection of the respiratory system can progress to a multisystemic disease with aberrant inflammatory response. Cellular senescence promotes chronic inflammation, named senescence-associated secretory phenotype (SASP). We investigated whether coronavirus disease 2019 (COVID-19) is associated with cellular senescence and SASP.

METHODS

Autopsy lung tissue samples from 11 COVID-19 patients and 43 age-matched non-COVID-19 controls with similar comorbidities were analysed by immunohistochemistry for SARS-CoV-2, markers of senescence and key SASP cytokines. Virally induced senescence was functionally recapitulated in vitro, by infecting epithelial Vero-E6 cells and a three-dimensional alveosphere system of alveolar type 2 (AT2) cells with SARS-CoV-2 strains isolated from COVID-19 patients.

RESULTS

SARS-CoV-2 was detected by immunocytochemistry and electron microscopy predominantly in AT2 cells. Infected AT2 cells expressed angiotensin-converting enzyme 2 and exhibited increased senescence (p16INK4A and SenTraGor positivity) and interleukin (IL)-1β and IL-6 expression. In vitro, infection of Vero-E6 cells with SARS-CoV-2 induced senescence (SenTraGor), DNA damage (γ-H2AX) and increased cytokine (IL-1β, IL-6, CXCL8) and apolipoprotein B mRNA-editing (APOBEC) enzyme expression. Next-generation sequencing analysis of progenies obtained from infected/senescent Vero-E6 cells demonstrated APOBEC-mediated SARS-CoV-2 mutations. Dissemination of the SARS-CoV-2-infection and senescence was confirmed in extrapulmonary sites (kidney and liver) of a COVID-19 patient.

CONCLUSIONS

We demonstrate that in severe COVID-19, AT2 cells infected by SARS-CoV-2 exhibit senescence and a proinflammatory phenotype. In vitro, SARS-CoV-2 infection induces senescence and inflammation. Importantly, infected senescent cells may act as a source of SARS-CoV-2 mutagenesis mediated by APOBEC enzymes. Therefore, SARS-CoV-2-induced senescence may be an important molecular mechanism of severe COVID-19, disease persistence and mutagenesis.

Spondylolisthesis

Spondylolisthesis refers to the anterior, lateral, or posterior slippage of a superior vertebral disc over the adjacent inferior disc, and is often separated into categories based on the causative etiology. Spondylolisthesis is often asymptomatic but may present with low back pain and neurogenic claudication which is worsened with spinal extension and activity. A detailed history and physical exam, along with appropriate imaging tests are useful in making the diagnosis. Conservative therapy is first-line and includes pain management with physical therapy. Patients who fail conservative therapy may consider surgical decompression, stabilization, and fusion. This review aims to discuss the epidemiology, pathophysiology, presentation, and treatment options of spondylolisthesis.

Pyogenic spinal infections in patients with chronic liver disease: illustrative case and systematic review

BACKGROUND

Pyogenic spinal infections (PSIs) are a group of uncommon but serious infectious diseases that are characterized by inflammation of the endplate–disc unit. PSIs are considered more prevalent and aggressive among patients with chronic immunocompromised states. Association between PSIs and liver disease has not been systematically analyzed. The authors performed a systematic review to study baseline characteristics, clinical presentation, and mortality of patients with PSI in the setting of chronic liver disease.

OBSERVATIONS

The authors presented the case of a 72-year-old female patient with chronic liver disease who presented with severe low back pain and bilateral lower weakness. Imaging studies showed T10–11 spondylodiscitis. The patient received decompression and fusion surgery with partial neurological improvement. The authors performed a systematic literature search of spondylodiscitis and liver disease, and eight published articles met the studies inclusion and exclusion criteria. These studies featured a total of 144 patients, of whom 129 met inclusion criteria (mean age, 60.5 years, range 40 to 83 years; 62% males). Lumbar infection was the most common report (67%), with Staphylococcus aureus (48%) as the main causative microorganism. Neurological compromise was present in 69% of patients. Surgical intervention occurred in 70.5% of patients, and the average duration of antibiotic treatment was 69.4 days. Postoperative complication rate was 28.5%, with a 30- and 90-day mortality of 17.2% and 24.8%, respectively.

LESSONS

Pyogenic spondylodiscitis in patients with liver disease was associated with a high rate of neurological compromise, postoperative complications, and mortality.

What Do We Know about Spondylodiscitis in Children? A Retrospective Study

Pediatric spondylodiscitis (PSD) is a rare disease with a major impact on mobility and functional status. Data concerning demographic and microbiological characteristics, clinical course, treatment, and outcome are scarce. Therefore, the aim of this study was to present clinical experiences of a third-level hospital (2009–2019) in PSD and compare these with adult spondylodiscitis (ASD). Of a total of 10 PSD patients, most of the infants presented with unspecific pain such as hip pain or a limping, misleading an adequate diagnosis of spine origin. Eight patients could be treated conservatively whereas surgery was performed in two cases with one case of tuberculous PSD (tPSD). The causative agent was detected in three of the patients. The diagnosis of PSD is often difficult since clinical symptoms are unspecific and causative pathogens often remain undetected. Nevertheless, empirical anti-infective therapy also seems to be effective. Based on recent studies, clinicians should be encouraged to keep the duration of anti-infective therapy in children short. Since comorbidities are not presented in PSD it is unclear which children suffer from PSD; thus, studies are necessary to identify predisposing factors for PSD. In our study, PSD differs from ASD in diagnostic and especially in therapeutic aspects. Therefore, specific guidelines for PSD would be desirable.

Percutaneous Endoscopic Interbody Debridement and Fusion (PEIDF) Decreases Risk of Sepsis and Mortality in Treating Infectious Spondylodiscitis for Patients with Poor Physical Status, a Retrospective Cohort Study

Background: Postoperative immunosuppression is associated with blood loss and surgical trauma during surgery and subsequently predisposes patients to increased morbidity. Spine endoscopic surgery has been accepted as an effective surgical technique with less surgical trauma and less blood loss for the complication of infectious spondylodiscitis. Therefore, the aim of this study was to investigate whether PEIDF could reduce the morbidity rates for patients with infectious spondylodiscitis. Methods: We launched a retrospective cohort study on the comparison of the perioperative prognosis between PEIDF and conventional open surgery for single-level lumbar infectious spondylodiscitis in patients with poor physical health (ASA ≥ 4) from 2014 to 2019. Results: Forty-four patients were included in this study. Fifteen of them underwent PEIDF, and the rest of the 29 patients were treated with open surgery. Less surgical blood loss (p < 0.001) and intraoperative transfusions (p < 0.001) with a better decline of CRP (p = 0.017) were statistically significant in patients receiving PEIDF. Patients undergoing conventional open surgery encountered more postoperative sepsis (p = 0.030), a higher qSOFA score (p = 0.044), and prolonged-time for CRP normalization (p = 0.001). Conclusions: PEIDF minimizes a poor postoperative outcome due to less surgical trauma, intraoperative blood loss, and the need for a blood transfusion.

GLI3 regulates muscle stem cell entry into GAlert and self-renewal

Satellite cells are required for the growth, maintenance, and regeneration of skeletal muscle. Quiescent satellite cells possess a primary cilium, a structure that regulates the processing of the GLI family of transcription factors. Here we find that GLI3 processing by the primary cilium plays a critical role for satellite cell function. GLI3 is required to maintain satellite cells in a G0 dormant state. Strikingly, satellite cells lacking GLI3 enter the GAlert state in the absence of injury. Furthermore, GLI3 depletion stimulates expansion of the stem cell pool. As a result, satellite cells lacking GLI3 display rapid cell-cycle entry, increased proliferation and augmented self-renewal, and markedly enhanced regenerative capacity. At the molecular level, we establish that the loss of GLI3 induces mTORC1 signaling activation. Therefore, our results provide a mechanism by which GLI3 controls mTORC1 signaling, consequently regulating muscle stem cell activation and fate.

Bidirectional roles of skeletal muscle fibro-adipogenic progenitors in homeostasis and disease

Sarcopenia and myopathies cause progressive muscle weakness and degeneration, which are closely associated with fat infiltration and fibrosis in muscle. Recently, experimental research has shed light on fibro-adipogenic progenitors (FAPs), also known as muscle-resident mesenchymal progenitors with multiple differentiation potential for adipogenesis, fibrosis, osteogenesis and chondrogenesis. They are considered key regulators of muscle homeostasis and integrity. They play supportive roles in muscle development and repair by orchestrating the regulatory interplay between muscle stem cells (MuSCs) and immune cells. Interestingly, FAPs also contribute to intramuscular fat infiltration, fibrosis and other pathologies when the functional integrity of the network is compromised. In this review, we summarize recent insights into the roles of FAPs in maintenance of skeletal muscle homeostasis, and discuss the underlying mechanisms regulating FAPs behavior and fate, highlighting their roles in participating in efficient muscle repair and fat infiltrated muscle degeneration as well as during muscle atrophy. We suggest that controlling and predicting FAPs differentiation may become a promising strategy to improve muscle function and prevent irreparable muscle damage.

Staphylococcus aureus Infection-Related Glomerulonephritis with Dominant IgA Deposition

Since 1995, when we reported the case of a patient with glomerulonephritis with IgA deposition that occurred after a methicillin-resistant Staphylococcus aureus (MRSA) infection, many reports of MRSA infection-associated glomerulonephritis have accumulated. This disease is being systematized as Staphylococcus infection-associated glomerulonephritis (SAGN) in light of the apparent cause of infection, and as immunoglobulin A-dominant deposition infection-related glomerulonephritis (IgA-IRGN) in light of its histopathology. This glomerulonephritis usually presents as rapidly progressive glomerulonephritis or acute kidney injury with various degrees of proteinuria and microscopic hematuria along with an ongoing infection. Its renal pathology has shown several types of mesangial and/or endocapillary proliferative glomerulonephritis with various degrees of crescent formation and tubulointerstitial nephritis. IgA, IgG, and C₃ staining in the mesangium and along the glomerular capillary walls have been observed on immunofluorescence examinations. A marked activation of T cells, an increase in specific variable regions of the T-cell receptor β-chain-positive cells, hypercytokinemia, and increased polyclonal immune complexes have also been observed in this glomerulonephritis. In the development of this disease, staphylococcal enterotoxin may be involved as a superantigen, but further investigations are needed to clarify the mechanisms underlying this disease. Here, we review 336 cases of IgA-IRGN and 218 cases of SAGN.

Simultaneous Substitution of Fe and Sr in Beta-Tricalcium Phosphate: Synthesis, Structural, Magnetic, Degradation, and Cell Adhesion Properties

β-tricalcium phosphate is a promising bone graft substitute material with biocompatibility and high osteoinductivity. However, research on the ideal degradation and absorption for better clinical application remains a challenge. Now, we focus on modifying physicochemical properties and improving biological properties through essential ion co-substitution (Fe and Sr) in β-TCPs. Fe- and Sr-substituted and Fe/Sr co-substituted β-TCP were synthesized by aqueous co-precipitation with substitution levels ranging from 0.2 to 1.0 mol%. The β-TCP phase was detected by X-ray diffraction and Fourier transform infrared spectroscopy. Changes in Ca–O and P–O bond lengths of the co-substituted samples were observed through X-ray photoelectron spectroscopy. The results of VSM represent the M-H graph having a combination of diamagnetic and ferromagnetic properties. A TRIS–HCl solution immersion test showed that the degradation and resorption functions act synergistically on the surface of the co-substituted sample. Cell adhesion tests demonstrated that Fe enhances the initial adhesion and proliferation behavior of hDPSCs. The present work suggests that Fe and Sr co-substitution in β-TCP can be a candidate for promising bone graft materials in tissue engineering fields. In addition, the possibility of application of hyperthermia for cancer treatment can be expected.

VDR promotes nucleus pulposus cell mitophagy as a protective mechanism against oxidative stress injury

Intervertebral disk degeneration (IDD) is a common aging disease. Excessive apoptosis of nucleus pulposus (NP) cells has been widely considered a main contributor to IDD. Emerging science has shown that autophagy plays a protective role against apoptosis under oxidative stress. Vitamin D receptor (VDR) is a steroid hormone receptor that can regulate autophagy. The purpose of this study was to clarify whether VDR alleviates IDD by promoting autophagy. H₂O₂ stimulation was used to establish oxidative stress conditions. Initially, the expression level of VDR in human degenerative NP tissues was measured by immunohistochemistry. In addition, the CRISPR-dCas9-VPR system and siRNA were utilized to upregulate or downregulate VDR and Parkin expression, respectively. Autophagic and apoptotic markers were determined by Western blotting and RT-qPCR. Transmission electron microscopy was used to monitor the occurrence of autophagy in rat NP cells. VDR expression was downregulated in human degenerative NP tissues and H₂O₂-stimulated rat NP cells, indicating a negative correlation between VDR expression and IDD. VDR overexpression promoted mitophagy and prevented apoptosis and mitochondrial injury under oxidative stress. Additionally, mitophagy inhibition by 3-MA abolished the protective effect of VDR activation in vitro. Furthermore, VDR activation promoted mitophagy via the PINK1/Parkin pathway in H₂O₂-treated NP cells. This study demonstrates that VDR activation ameliorates oxidative damage and decreases NP cell apoptosis by promoting PINK1/Parkin-dependent mitophagy, indicating that VDR may serve as a promising therapeutic target in the management of IDD.

Assessment of perioperative total blood loss during total ankle arthroplasty

BACKGROUND

Although many authors have discussed total blood loss after arthroplasty of the knee, hip, and shoulder, reports on perioperative blood loss after total ankle arthroplasty (TAA) are rare. The purpose of this study was to assess total blood loss after TAA and to identify correlated factors.

METHODS

A total of 103 cases (99 patients) of TAA for end-stage ankle osteoarthritis were enrolled in this study. Perioperative total blood loss was divided into intraoperative and postoperative blood loss. The patient-related variables evaluated for total blood loss were age, sex, body mass index, American Society of Anesthesiologists Classification score, comorbidities, history of previous ankle surgery, preoperative use of anticoagulants, platelet count and prothrombin time/international normalized ratio. Operation-related variables including type of anesthesia, operation time, TAA implant, and procedures performed in addition to TAA (if any) were evaluated to analyze correlations with total blood loss. In addition, the rate of transfusions after surgery was identified, and risk factors for transfusion were statistically analyzed.

RESULTS

The total blood loss was mean 795.5±351.1mL, which included 462.2±248.5mL of intraoperative blood loss and 333.2±228.6mL of postoperative blood loss. Sex, TAA implant, and additional bony procedures performed along with TAA were significantly correlated with total blood loss (p=0.039, 0.024, 0.024, respectively) but the other variables were not significant (p>0.05). Transfusions were administered for 4 cases (3.8%) but no risk factors for transfusion could be identified.

CONCLUSION

The total blood loss after TAA was 795.5mL and the rate of transfusions was 3.8%. This study demonstrated that male sex, use of TAA implants with a larger cutting surface, and bony procedures performed in addition to TAA were associated with an increase in total blood loss after TAA. The findings of this study will help surgeons to better predict blood loss and make optimal surgical plans accordingly.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Hypoallergenic unicompartmental knee arthroplasty and return to sport: comparison between Oxidized Zirconium and Titanium Niobium Nitride

BACKGROUND

The present study aims to compare the rate of return to sports in patients who underwent surgery for mobile-bearing UKA with either hypoallergenic TiNbN or with oxidized zirconium alloy implants.

METHODS

The records of two consecutive cohorts for a total of 90 hypoallergenic implants were prospectively analysed. The first cohort consisted of 41 consecutive series of medial mobile-bearing hypoallergenic TiNbN UKA, whereas the second cohort consisted of 49 consecutive medial fixed-bearing hypoallergenic Uni Oxinium.The clinical evaluation involved evaluating each patient's University of California, Los Angeles (UCLA) activity scoresand the High-Activity Arthroplasty Score(HAAS). Each patient was clinically evaluated on the day before surgery (T0), then after a minimum follow-up period of 12 months (T1), and finally after 24 months (T2).   Results:The only pre-operative difference between the two groups involved pre-operative BMI with significantly higher BMI in TiNbN Group (p<0.001). Both groups reported significant improvement at each follow-up compared with the previous and also at the final follow up with respect to UCLA and HAAS (p<0.05), except for UCLA in TiNbN between T1 and T2(p>0.05). Moreover, BMI improved significantly at the final follow up, but only in TiNbN group (p<0.05).

CONCLUSIONS

Both TiNbN and Oxinium UKA procedures enabled patients to return to an acceptable level of sports activity with excellent radiographic outcomes after the final follow up regardless of the age, gender, BMI, and bearing type.

Primary spinal infections in patients with solid organ transplant: a systematic literature review and illustrative case

BACKGROUND

Primary spinal infections (PSIs) are a group of uncommon but serious infectious diseases considered more prevalent and aggressive among patients with chronic immunocompromised states. Association of PSI and solid organ transplant has not been systematically analyzed. The authors performed a systematic review analyzing clinical presentation and mortality of patients with PSI in the setting of solid organ transplant.

OBSERVATIONS

PSIs in patients with immunosuppressive therapy, such as those with solid organ transplant, may behave differently in terms of epidemiology, clinical presentation, and outcomes compared with nonimmunosuppressed patients. Overall PSI in solid organ transplant patients is associated with a high rate of neurological compromise, postoperative complications, and mortality.

LESSONS

Accurate diagnosis and appropriate treatment of PSI require a multidisciplinary effort. Localized pain is the most frequently reported symptom associated with PSI. As opposed to PSI in patients without transplant, inflammatory and infectious markers such as white blood cells and C-reactive protein are often not elevated. Furthermore, the causative microorganism profile varies significantly when compared to pyogenic spinal infection in patients without transplant. Aspergillus species was responsible for spondylodiscitis in transplant patients in more than 50% of cases, and the incidence of Aspergillus infection is projected to rise in the coming years.

Effectiveness and postoperative rehabilitation of one-stage combined anterior-posterior surgery for severe thoracolumbar fractures with spinal cord injury

BACKGROUND

Thoracolumbar fractures are generally combined with spinal cord injury to varying degrees, which may cause deterioration of the patients' condition and increase the difficulty of clinical treatment. At present, anterior or combined anterior-posterior surgery is preferred for severe thoracolumbar fractures.

AIM

To investigate the effectiveness and postoperative rehabilitation of one-stage combined anterior-posterior surgery for severe thoracolumbar fractures with spinal cord injury.

METHODS

One-hundred-and-twenty patients who received surgery for severe thoracolumbar fractures with spinal cord injury at our hospital from February 2018 to February 2020 were randomly enrolled. They were randomly divided into group 1 (one-stage combined anterior-posterior surgery, n = 60) and group 2 (one-stage anterior-approach surgery, n = 60). Treatment efficacy was compared between the two groups.

RESULTS

Blood loss was greater and the operation time was longer in group 1 than in group 2, and the differences were statistically significant (P < 0.05). Incision length, intraoperative X-rays, and length of hospital stay were not significantly different between the two groups (P > 0.05). Preoperative function of the affected vertebrae was not significantly different between the two groups (P > 0.05). In each group, the patients showed significant improvement after surgery. The anterior vertebral height ratio and the posterior vertebral height ratio in group 1 after surgery were significantly higher than those in group 2. The Cobb angle after surgery was significantly lower in group 1 than in group 2 (P < 0.05). The canal-occupying ratio of the affected vertebrae was not significantly different between the two groups (P > 0.05). Before surgery, there was no significant difference in the quality of life scores between the two groups (P > 0.05). The above indicators were significantly improved after surgery compared with before surgery in each group. In addition, these indicators were markedly better in group 1 than in group 2 after surgery (P < 0.05 for each).

CONCLUSION

One-stage combined anterior-posterior surgery effectively improves the function of the affected vertebrae and the life quality of patients with severe thoracolumbar fractures and spinal cord injury. This surgical approach is worthy of popularization in clinical use.

Tumor-Associated Inflammation: The Tumor-Promoting Immunity in the Early Stages of Tumorigenesis

Tumorigenesis is a multistage progressive oncogenic process caused by alterations in the structure and expression level of multiple genes. Normal cells are continuously endowed with new capabilities in this evolution, leading to subsequent tumor formation. Immune cells are the most important components of inflammation, which is closely associated with tumorigenesis. There is a broad consensus in cancer research that inflammation and immune response facilitate tumor progression, infiltration, and metastasis via different mechanisms; however, their protumor effects are equally important in tumorigenesis at earlier stages. Previous studies have demonstrated that during the early stages of tumorigenesis, certain immune cells can promote the formation and proliferation of premalignant cells by inducing DNA damage and repair inhibition, releasing trophic/supporting signals, promoting immune escape, and activating inflammasomes, as well as enhance the characteristics of cancer stem cells. In this review, we focus on the potential mechanisms by which immune cells can promote tumor initiation and promotion in the early stages of tumorigenesis; furthermore, we discuss the interaction of the inflammatory environment and protumor immune cells with premalignant cells and cancer stem cells, as well as the possibility of early intervention in tumor formation by targeting these cellular mechanisms.

The influence of HLA genotype on the development of metal hypersensitivity following joint replacement

Background

Over five million joint replacements are performed across the world each year. Cobalt chrome (CoCr) components are used in most of these procedures. Some patients develop delayed-type hypersensitivity (DTH) responses to CoCr implants, resulting in tissue damage and revision surgery. DTH is unpredictable and genetic links have yet to be definitively established.

Methods

At a single site, we carried out an initial investigation to identify HLA alleles associated with development of DTH following metal-on-metal hip arthroplasty. We then recruited patients from other centres to train and validate an algorithm incorporating patient age, gender, HLA genotype, and blood metal concentrations to predict the development of DTH. Accuracy of the modelling was assessed using performance metrics including time-dependent receiver operator curves.

Results

Using next-generation sequencing, here we determine the HLA genotypes of 606 patients. 176 of these patients had experienced failure of their prostheses; the remaining 430 remain asymptomatic at a mean follow up of twelve years. We demonstrate that the development of DTH is associated with patient age, gender, the magnitude of metal exposure, and the presence of certain HLA class II alleles. We show that the predictive algorithm developed from this investigation performs to an accuracy suitable for clinical use, with weighted mean survival probability errors of 1.8% and 3.1% for pre-operative and post-operative models respectively.

Conclusions

The development of DTH following joint replacement appears to be determined by the interaction between implant wear and a patient's genotype. The algorithm described in this paper may improve implant selection and help direct patient surveillance following surgery. Further consideration should be given towards understanding patient-specific responses to different biomaterials.

Amine Functionalized Trimetallic Nitride Endohedral Fullerenes: A Class of Nanoparticle to Tackle Low Back/Leg Pain

Low back pain is the most common health problem with a prevalence of over 80% worldwide and an estimated annual cost of $100 billion in the United States. Intervertebral disc degeneration accounts for a major cause of low back pain. However, there is still a lack of safe and effective treatment to tackle this devastating condition. In this study, we synthesized four functionalized trimetallic nitride endohedral metallofullerenes (carboxyl-f-Sc3N@C80, carboxyl-f-Gd3N@C80, amino-f-Sc3N@C80, and amino-f-Gd3N@C80) and characterized them with X-ray photoelectron spectroscopy, matrix-assisted laser desorption/ionization-time of flight mass spectrometry, and UV-vis. Via electron paramagnetic resonance, all four metallofullerene derivatives possessed dose-dependent radical scavenging capabilities (hydroxyl radicals and superoxide anions), with the most promising radical scavenging properties shown in the amine functionalized C80 metallofullerenes. Both amino-f-Sc3N@C80 and amino-f-Gd3N@C80 at 1 μM significantly reduced lipopolysaccharide induced reactive oxygen species production and mRNA expressions of pro-inflammatory mediators (inos, tnf-α, il-1, and cox-2) in macrophages without apparent cytotoxicity through regulating activity of p38 MAPK, p65, and nuclear translocation of NF-κB. Furthermore, in an established mouse model of lumbar radiculopathy, amino-f-Sc3N@C80 and amino-f-Gd3N@C80 effectively alleviated ipsilateral mechanical hyperalgesia for up to 2 weeks. In dorsal root ganglia explant culture, we also showed that amino-f-Sc3N@C80 and amino-f-Gd3N@C80 ameliorated TNF-α elicited neuroinflammation. In summary, we presented results for a potent radical scavenging, anti-inflammatory and analgesic nanoparticle, amino-functionalized eighty-carbon metallofullerenes in vitro and in vivo. Our study provides important assets for developing pleiotropic treatment strategies to tackle the inflammation, a significant pathological hallmark in the intervertebral disc degeneration and associated pain.

Identification of Core Genes and Screening of Potential Targets in Intervertebral Disc Degeneration Using Integrated Bioinformatics Analysis

Background: Intervertebral disc degeneration (IDD), characterized by diverse pathological changes, causes low back pain (LBP). However, prophylactic and delaying treatments for IDD are limited. The aim of our study was to investigate the gene network and biomarkers of IDD and suggest potential therapeutic targets.

Methods: Differentially expressed genes (DEGs) associated with IDD were identified by analyzing the mRNA, miRNA, and lncRNA expression profiles of IDD cases from the Gene Expression Omnibus (GEO). The protein–protein interaction (PPI) network, Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis as well as miRNA–lncRNA–mRNA networks were conducted. Moreover, we obtained 71 hub genes and performed a comprehensive analysis including GO, KEGG, gene set enrichment analysis (GSEA), gene set variation analysis (GSVA), Disease Ontology (DO), methylation analysis, receiver operating characteristic (ROC) curve analysis, immune infiltration analysis, and potential drug identification. We finally used qRT-PCR to verify 13 significant DEGs in normal and degenerative nucleus pulposus cells (NPCs).

Results: We identified 305 DEGs closely related to IDD. The GO and KEGG analyses indicated that changes in IDD are significantly associated with enrichment of the inflammatory and immune response. GSEA analysis suggested that cell activation involved in the inflammatory immune response amide biosynthetic process was the key for the development of IDD. The GSVA suggested that DNA repair, oxidative phosphorylation, peroxisome, IL-6-JAK-STAT3 signaling, and apoptosis were crucial in the development of IDD. Among the 71 hub genes, the methylation levels of 11 genes were increased in IDD. A total of twenty genes showed a high functional similarity and diagnostic value in IDD. The result of the immune cell infiltration analysis indicated that seven genes were closely related to active natural killer cells. The most relevant targeted hub genes for potential drug or molecular compounds were MET and PIK3CD. Also, qRT-PCR results showed that ARHGAP27, C15orf39, DEPDC1, DHRSX, MGAM, SLC11A1, SMC4, and LINC00887 were significantly downregulated in degenerative NPCs; H19, LINC00685, mir-185-5p, and mir-4306 were upregulated in degenerative NPCs; and the expression level of mir-663a did not change significantly in normal and degenerative NPCs.

Conclusion: Our findings may provide new insights into the functional characteristics and mechanism of IDD and aid the development of IDD therapeutics.

The cGAS-STING Pathway Affects Vertebral Bone but Does Not Promote Intervertebral Disc Cell Senescence or Degeneration

The DNA-sensing cGAS-STING pathway promotes the senescence-associated secretory phenotype (SASP) and mediates type-I interferon inflammatory responses to foreign viral and bacterial DNA as well as self-DNA. Studies of the intervertebral disc in humans and mice demonstrate associations between aging, increased cell senescence, and disc degeneration. Herein we assessed the role of STING in SASP promotion in STING gain- (N153S) and loss-of-function mouse models. N153S mice evidenced elevated circulating levels of proinflammatory markers including IL-1β, IL-6, and TNF-α, showed elevated monocyte and macrophage abundance in the vertebral marrow, and exhibited a mild trabecular and cortical bone phenotype in caudal vertebrae. Interestingly, despite systemic inflammation, the structural integrity of the disc and knee articular joint remained intact, and cells did not show a loss of their phenotype or elevated SASP. Transcriptomic analysis of N153S tissues demonstrated an upregulated immune response by disc cells, which did not closely resemble inflammatory changes in human tissues. Interestingly, STING^-/- mice also showed a mild vertebral bone phenotype, but the absence of STING did not reduce the abundance of SASP markers or improve the age-associated disc phenotype. Overall, the analyses of N153S and STING^-/- mice suggest that the cGAS-STING pathway is not a major contributor to SASP induction and consequent disc aging and degeneration but may play a minor role in the maintenance of trabecular bone in the vertebrae. This work contributes to a growing body of work demonstrating that systemic inflammation is not a key driver of disc degeneration.

Silibinin Can Promote Bone Regeneration of Selenium Hydrogel by Reducing the Oxidative Stress Pathway in Ovariectomized Rats

Osteoporosis-related bone defects are a major public health concern. Considering poor effects of a singular pharmacological treatment, many have sought combination therapies, including local treatment combined with systemic intervention. Based on recent evidence that selenium and silibinin increase bone formation and bone mineral density, it is hypothesized that systemic administration with silibinin plus local treatment with selenium may have an additive effect on bone regeneration in an OVX rat model with bone defects. To verify this hypothesis, 3-month-old ovariectomized Sprague- Dawley rats (n = 10/gp) were intraperitoneally with a dose of 50 mg/kg silibinin with selenium hydrogel scaffolds implanted into femoral metaphysis bone defect. Moreover, the MC3T3-E1 cells were co-cultured with selenium and silibinin, and observed any change of cell viability, ROS, and osteogenic activity. Experiment results show that the cell mineralization and osteogenic activity of silibinin plus selenium (SSe) group is enormously higher than the control (Con) group and selenium (Se) group, while ROS appears to be immensely reduced. Osteogenic protein expressions such as SIRT1, SOD2, RUNX-2 and OC of SSe group are significantly higher than Con group and Se group. Micro-CT and Histological analysis evaluation display that group SSe, compared with Con group and Se group, presents the strongest effect on bone regeneration, bone mineralization and higher expression of SIRT1 and SOD2. RT-qPCR analysis indicates that SSe group manifests increased SIRT1, SOD1, SOD2 and CAT than the Con group and Se group (p < 0.05). Our current study demonstrates that systemic administration with SIL plus local treatment with Se is a scheme for rapid repair of femoral condylar defects, and these effects may be achieved via reducing the oxidative stress pathway.

Investigation into the anti-inflammatory properties of metformin in intervertebral disc cells

Introduction

Intervertebral disc degeneration (IDD) is closely related to heightened inflammation in the annulus fibrosis (AF) and nucleus pulposus (NP) cells in the intervertebral disc. An imbalanced matrix homeostasis has been shown to contribute to disc degeneration and associated discogenic low back pain. Metformin, a diabetes medication, has been noted to exhibit anti-inflammatory properties through upregulation of the AMPK pathway, leading to various anti-inflammatory-related responses in hepatocytes. However, it is still unclear how metformin influences disc cellular response to inflammatory stress and the corresponding mechanism. Hence, the objective of this study is to elucidate the effects of metformin on expression of key pro-inflammatory, catabolic, and anabolic factors within rat AF cells in response to inflammatory stimulation and mechanical tensile stress.

Methods

Five Fischer 344 rats were sacrificed and their spines isolated. AF cells were cultured and plated in flexible silicone membrane-based six-well plates. Wells were split into eight groups and subjected to metformin, IL-1β, mechanical stretch, and combined treatments. Relative gene expressions of MMP-13, COX-2, iNOS, AGC, and Col1 were assessed with quantitative real-time polymerase chain reaction (qRT-PCR), and downstream prostaglandin E2 (PGE2) production was quantified with enzyme-linked immunosorbent assay (ELISA). NF-kB nuclear translocation was also quantified.

Results

Metformin in the presence of the combined stress treatments (M + IL/S) significantly increased Col1, COX-2, and MMP-13 gene expression, decreased PGE2 production compared to IL/S conditions alone. Metformin treatment of cultured rat annulus fibrosus cells significantly reduced the nuclear translocation of NF-κB after 4 h of IL-1β treatment from 43.1% in case of IL-1β treatment down to 26.2% in the case of metformin + IL-1β treatment.

Discussion

The lack of metformin-mediated suppression of inflammatory response in the nonstretch groups indicates that metformin may be enacting its effects through a stretch-dependent manner. These results suggest a foundation for pursuing further research into metformin's potential role as an anti-inflammatory agent for curtailing intervertebral disc degeneration.

Percutaneous lumbar annular puncture: A rat model to study intervertebral disc degeneration and pain-related behavior

Background

Previous animal models of intervertebral disc degeneration (IDD) rely on open surgical approaches, which confound the degenerative response and pain behaviors due to injury to surrounding tissues during the surgical approach. To overcome these challenges, we developed a minimally invasive percutaneous puncture procedure to induce IDD in a rat model.

Methods

Ten Fischer 344 male rats underwent percutaneous annular puncture of lumbar intervertebral discs (IVDs) at L2-3, L3-4, and L4-5. Ten unpunctured rats were used as controls. Magnetic resonance imagings (MRIs), serum biomarkers, and behavioral tests were performed at baseline and 6, 12, and 18 weeks post puncture. Rats were sacrificed at 18 weeks and disc histology, immunohistochemistry, and glycosaminoglycan (GAG) assays were performed.

Results

Punctured IVDs exhibited significant reductions in MRI signal intensity and disc volume. Disc histology, immunohistochemistry, and GAG assay results were consistent with features of IDD. IVD-punctured rats demonstrated significant changes in pain-related behaviors, including total distance moved, twitching frequency, and rearing duration.

Conclusions

This is the first reported study of the successful establishment of a reproducible rodent model of a percutaneous lumbar annular puncture resulting in discogenic pain. This model will be useful to test therapeutics and elucidate the basic mechanisms of IDD and discogenic pain.

Bushen Huoxue Formula Modulates Autophagic Flux and Inhibits Apoptosis to Protect Nucleus Pulposus Cells by Restoring the AMPK/SIRT1 Pathway

Background

Low back pain (LBP) has the characteristics of chronic and persistence, which is a heavy social burden. Intervertebral disc degeneration (IVDD) is a major cause of LBP. The typical features of IVDD are extracellular matrix (ECM) degradation and nucleus pulposus cell (NP) apoptosis. Bushen Huoxue Formula (BSHXF) has good clinical effects on LBP. However, the mechanism of BSHXF affecting ECM and NP cells is still unclear. Aim of the Study. In this study, the impact of BSHXF on autophagy and apoptosis of NP cells was studied through the AMPK/SIRT1 pathway. Material and Methods. NP cells were extracted through the digestion of collagenase and trypsin, and the components of BSHXF were identified. Cell Counting Kit-8 was applied to detect the impact of BSHXF on NP cells. Mitochondrial function was detected using MitoTracker assay, ATP kit, and SOD kit. Autophagy and apoptosis were detected by RT-qPCR, western blotting, and flow cytometry.

Results

BSHXF promoted NP cell survival in a concentration-dependent manner, and the elimination of rat serum did not increase cell proliferation; TNF-α accelerated ECM degradation, ROS accumulation, and NP cell apoptosis and decreased autophagic flux. BSHXF restored mitochondrial function and autophagic flux. In addition, AMPK/SIRT1 pathway activation was associated with IVDD.

Conclusions

BSHXF regulates autophagy and enhances autophagic flux to suppress excessive ROS production and restore mitochondrial function in an AMPK/SIRT1-dependent manner. However, the protection of BSHXF on TNF-α-treated cells was eliminated by 3-MA. Furthermore, the protective impact of BSHXF on ECM degradation and apoptosis induced by TNF-α was restrained by an AMPK inhibitor. Therefore, maintaining the proper autophagy illustrates treatment strategy for IVDD.

A murine model of large-scale bone regeneration reveals a selective requirement for Sonic Hedgehog

Building and maintaining skeletal tissue requires the activity of skeletal stem and progenitor cells (SSPCs). Following injury, local pools of these SSPCs become active and coordinate to build new cartilage and bone tissues. While recent studies have identified specific markers for these SSPCs, how they become activated in different injury contexts is not well-understood. Here, using a model of large-scale rib bone regeneration in mice, we demonstrate that the growth factor, Sonic Hedgehog (SHH), is an early and essential driver of large-scale bone healing. Shh expression is broadly upregulated in the first few days following rib bone resection, and conditional knockout of Shh at early but not late post-injury stages severely inhibits cartilage callus formation and later bone regeneration. Whereas Smoothened (Smo), a key transmembrane component of the Hh pathway, is required in Sox9+ lineage cells for rib regeneration, we find that Shh is required in a Prrx1-expressing, Sox9-negative mesenchymal population. Intriguingly, upregulation of Shh expression and requirements for Shh and Smo may be unique to large-scale injuries, as they are dispensable for both complete rib and femur fracture repair. In addition, single-cell RNA sequencing of callus tissue from animals with deficient Hedgehog signaling reveals a depletion of Cxcl12-expressing cells, which may indicate failed recruitment of Cxcl12-expressing SSPCs during the regenerative response. These results reveal a mechanism by which Shh expression in the local injury environment unleashes large-scale regenerative abilities in the murine rib.

Decompression only versus fusion in octogenarians with spinal epidural abscesses: early complications, clinical and radiological outcome with 2-year follow-up

Despite increased life expectancy due to health care quality improvements globally, pyogenic vertebral osteomyelitis (PVO) treatment with a spinal epidural abscess (SEA) remains challenging in patients older than 80 years. We aimed to assess octogenarians for PVO prevalence with SEA and compare after-surgery clinical outcomes of decompression and decompression and instrumentation. A retrospective review of electronic medical records at a single institution was conducted between September 2005 and December 2020. Patient demographics, surgical characteristics, complications, hospital course, and 90-day mortality were collected. Comorbidities were assessed using the age-adjusted Charlson comorbidity index (CCI). Over 16 years, 35 patients aged ≥80 years with PVO and SEA were identified. Eighteen patients underwent surgical decompression (“decompression group”), and 17 underwent surgical decompression with instrumentation (“instrumentation group”). Both groups had a CCI >6 (mean±SD, 8.9±2.1 vs. 9.6±2.7, respectively; p=0.065). Instrumentation group patients had a significantly longer hospital stay but no ICU stay. In-hospital and 90-days mortality rates were similar in both groups. The mean follow-up was 26.6±12.4 months. No further surgeries were performed. Infection levels and neurological status were improved in both groups at discharge. At the second-stage analysis, significant improvements in the blood infection parameters and the neurological status were detected in the decompression group. Octogenarians with PVO and SEA have a high adverse events risk after surgical procedures. Surgical decompression might contribute to earlier clinical recovery in older patients. Thus, the surgical approach should be discussed with patients and their relatives and be carefully weighed.

Clinical results of restoration of pars interarticularis defect in adults with percutaneous intralaminar screw fixation

OBJECTIVE

This study aims to report the clinical outcomes associated with the percutaneous intralaminar screw repair performed for pars defects in adults.

METHODS

Adult patients who got their lumbar L5 spondylolysis repaired via the modified Buck's procedure between 2017 and 2020 were retrospectively evaluated. The preoperative and postoperative clinical outcomes at 1, 3, 6, and 12 months were evaluated for patients with and without fusion using the visual analog scale (VAS), Oswetry Disability Index (ODI), and the Short Form Health Survey 36 (SF-36). At 12 months, the fusion status of all the patients was assessed using bilateral direct X-rays.

RESULTS

Thirty patients with spondylolysis were identified (11 men and 19 women). All patients had bilateral L5 pars defects, and at 12 months, the fusion rate was 60% (18/30). There was no difference between the fusion and nonfusion groups in terms of their VAS, ODI, SF-36-physical component summary (PCS), and SF-36-mental component summary (MCS) scores (p > 0.05). Within-group comparisons of the two groups revealed significant changes at follow-up (p < 0.05).

CONCLUSIONS

Minimally invasive repair of lumbar spondylolysis with percutaneous intralaminar screw fixation restores the motion segment and can provide early resumption of physical activity with minimal muscle damage, smaller skin incision, and less soft tissue dissection.

The Protective Role of pVHL in Imiquimod-Induced Psoriasis-like Skin Inflammation

Psoriasis is a chronic inflammatory disease distinguished by an excessive proliferation and abnormal differentiation of keratinocytes. Immune cells, such as T lymphocytes and neutrophils, and inflammatory cytokines, such as Tumor Necrosis Factor-α (TNF-α) and interleukin 17 (IL-17), are essential for maintaining psoriatic lesions. Additionally, a hypoxic milieu present in the skin promotes the expression of transcriptional factor hypoxia-inducible factor-1 alpha (HIF-1α). This protein regulates the expression of angiogenic and glycolytic factors, such as vascular endothelial grown factor and lactate dehydrogenase (LDH), both relevant in chronic inflammation. The von Hippel–Lindau protein (pVHL) is a negative regulator of HIF-1α. Previously, we found that pVHL was almost absent in the lesions of psoriasis patients; therefore, we investigated the impact of rescue pVHL expression in lesional skin. We used the imiquimod-induced psoriasis-like mouse model as an adenoviral vector that allowed us to express pVHL in the skin. Our data show that, in lesional skin, pVHL expression was reduced, whereas HIF-1α was increased. Remarkably, the retrieval of pVHL prevented psoriatic lesions, diminishing erythema, scale, and epidermal and vascular thickness. Furthermore, pVHL expression was capable of reducing HIF-1α, LDH, TNF-α and immune cell infiltration (mainly IL-17⁺ neutrophils). In conclusion, our results demonstrate that pVHL has a protective role to play in the pathophysiology of psoriasis.

Evaluation of local tissue peri-implant reaction in total knee arthroplasty failure cases

Introduction:

Implant-related hypersensitivity is emerging as a causative factor as a potential source of total knee arthroplasty (TKA) failure. Mechanistically, this type IV hypersensitivity reaction (T4HR) is mediated by effector T-cells, macrophages, and leukocytes that infiltrate to the site of implant and react to metal exposure and induce inflammatory tissue damage.

Methods:

A case–control study was performed where cortical bone was taken at the time of revision surgery for all patients operated on for primary TKA in which metal allergy was suspected and for revision TKA cases done for presumed metal allergy. Cytof was used to determine the cell density of inflammatory cells, specifically Th1, Th2, M1, and M2 cells.

Results:

Comparing the mean cell density of primary versus revision TKA, revision TKA patients had significantly higher number of Th2 cells compared with Th1 cells ( p = 0.0043). Among revision cases, there were significantly more M1 versus M2 macrophages ( p = 0.034) within a patient. When comparing mean cell density of M1 versus M2 macrophages, there was a significant difference in both primary and revision TKA surgeries ( p = 0.0041 primary, p < 0.001 revision). Among revision patients who had a predominance of Th2 cells, four (44%) of nine patients had a negative LTT/patch test.

Conclusion:

These data support metal hypersensitivity, mediated by a T4HR, for some cases of TKA failure. Current methods to screen patients for metal hypersensitivity prior to primary TKA have been inclusive. This study demonstrates the need for a more sensitive screening test from specimens in the knee joint, to more accurately identify patients who will exhibit a T4HR to metal.