Walking pace is a protective factor for rheumatoid arthritis: a mendelian randomization study.

Walking pace is a simple and functional form of exercise and a strong predictor of health, but little is known about its causal association with rheumatoid arthritis. This study aimed to investigate the causal effect of WP on the developing RA using Mendelian randomization analysis. The genetic variation associated with WP was selected as an instrumental variable from the latest genome-wide association studies. Summary-level data for the outcomes were obtained from the corresponding GWAS. The inverse-variance weighted method was used as the primary MR analysis. The results were further tested using a multivariable MR approach based on Bayesian model averaging. Confounders (BMI, SMK, HBP, TD) with close associations with RA were included in the analysis. An observational study with individual data from UK Biobank was performed to reinforce our findings. The MR results indicated the significant inverse associations of WP with the risk of RA (odds ratio (OR), 0.31; 95% confidence interval (CI), 0.15, 0.62; p = 1.05 × 10 -3). After adjusting for the risk factors, the associations for WP and RA did not change substantially. Observational study results demonstrated the same effect of WP on reducing the risk of RA. The Mendelian randomization analysis and observational study provide evidence suggesting that walking pace is a protective factor for rheumatoid arthritis. Given its simple measurement, walking pace may be a pragmatic target for interventions.

Migrasome, a migration-dependent organelle.

Migrasomes are organelles produced by migrating cells that form on retraction fibers and are released during cell migration. Migrasomes are involved in physiological and pathological processes such as intercellular communication, cell homeostasis maintenance, signal transduction, disease occurrence and development, and cancer metastasis. In addition, methods and techniques for studying migrasomes are constantly evolving. Here, we review the discovery, formation process, regulation, and known functions of migrasomes, summarize the commonly used specific markers of migrasomes, and the methods for observing migrasomes. Meanwhile, this review also discusses the potential applications of migrasomes in physiological processes, disease diagnosis, treatment, and prognosis, and looks forward to their wider application in biomedicine. In addition, the study of migrasomes will also reveal a new perspective on the mechanism of intercellular communication and promote the further development of life science.

Blockade of CD93 in pleural mesothelial cells fuels anti-lung tumor immune responses.

Background: CD93 reportedly facilitates tumor angiogenesis. However, whether CD93 regulates antitumor immunity remains undeciphered. Methods: Lung tumor tissues, malignant pleural effusions (MPEs) were obtained from lung cancer patients. Blood was obtained from healthy volunteers and lung cancer patients with anti-PD-1 therapy. Furthermore, p53fl/flLSL-KrasG12D, Ccr7-/-, Cd93-/- mice and CD11c-DTR mice were generated. Specifically, EM, NTA and western blotting were utilized to identify Tumor extracellular vesicles (TEVs). EV labeling, detection of EV uptake in vitro and in vivo, degradation of EV proteins and RNAs were performed to detect the role of TEVs in tumor progression. Pleural mesothelial cells (pMCs) were isolated to investigate related signaling pathways. Recombinant proteins and antibodies were generated to test which antibody was the most effective one to increase CCL21a in p-pMCs. RNA-Seq, MiRNA array, luciferase reporter assay, endothelial tube formation assay, protein labeling and detection, transfection of siRNAs and the miRNA mimic and inhibitor, chemotaxis assay, immunohistochemical staining, flow cytometry, Real-time PCR, and ELISA experiments were performed. Results: We show that CD93 of pMCs reduced lung tumor migration of dendritic cells by preventing pMCs from secreting CCL21, thereby suppressing systemic anti-lung tumor T-cell responses. TEV-derived miR-5110 promotes CCL21 secretion by downregulating pMC CD93, whereas C1q, increasing in tumor individuals, suppresses CD93-mediated CCL21 secretion. CD93-blocking antibodies (anti-CD93) inhibit lung tumor growth better than VEGF receptor-blocking antibodies because anti-CD93 inhibit tumor angiogenesis and promote CCL21 secretion from pMCs. Anti-CD93 also overcome lung tumor resistance to anti-PD-1 therapy. Furthermore, lung cancer patients with higher serum EV-derived miR-5193 (human miR-5110 homolog) are more sensitive to anti-PD-1 therapy, while patients with higher serum C1q are less sensitive, consistent with their regulatory functions on CD93. Conclusions: Our study identifies a crucial role of CD93 in controlling anti-lung tumor immunity and suggests a promising approach for lung tumor therapy.

Preliminary fracture reduction in children with type III supracondylar humerus fractures during the COVID-19 pandemic.

During the COVID-19 pandemic, the time elapsed from injury to definitive surgery necessitated delay in type III pediatric supracondylar humerus fractures. Preliminary fracture reduction was recommended in these fractures while waiting for operative treatment. The purpose of this study was to evaluate whether preliminary reduction afforded a better treatment experience and improved outcomes. A retrospective cohort analysis of 161 type III supracondylar humerus fractures compared treatment with preliminary closed fracture reduction and delayed percutaneous pin placement (110 children) to delayed combined closed reduction and pin placement (51 children) in a children's medical center. Of the preliminary reduction group, 22 (20%) required analgesic pain relief, compared to 18 (35%) in the non-preliminary reduction group ( P  = 0.037), and the preliminary reduction group had statistically less pain (assessed using the Faces Pain Scale-Revised rating) the first night after injury and the first-night post-CRPP ( P  = 0.019, P  = 0.008). Cast splitting was more frequent in the non-preliminary reduction group, 11 patients (22%) than in the preliminary reduction group, 10 patients (9%; P  = 0.029). The operative times in the preliminary reduction group were shorter ( P  < 0.001). If delay is necessary for complete repair of type III supracondylar humerus fractures, a preliminary fracture reduction with a temporary cast can be recommended, as these children will experience a more comfortable interval, with less swelling and pain, and potentially a shorter operation. Level of Evidence: Level III-therapeutic study.

Percutaneous K-wire reduction and cast immobilization for severely displaced radial neck fractures in children.

The purpose of this study was to compare outcomes between percutaneous K-wire reduction cast immobilization (PKRC) and percutaneous K-wire reduction elastic intramedullary nailing combined with cast immobilization (PKRNC) for the treatment of radial neck fractures in children. This was a retrospective analysis of 62 radial neck fractures in children treated with PKRC or PKRNC. Thirty-one children were treated with percutaneous K-wire reduction, K-wire removal after reduction, and cast immobilization while 31 radial neck fractures in controls were managed using PKRNC. There were no significant differences between PKRC and PKRNC with regard to preoperative angulation ( P  = 0.556). The operation time in the PKRC group was significantly shorter than that of the PKRNC group ( P  = 0.023). There was no significant difference in the displacement angle when compared between the two groups on the first day and 1 month after surgery ( P  = 0.617, 0.72). The Mayo elbow performance score of the elbow joint function did not differ significantly between the two groups ( P  = 0.587). Although the hospital stay was not significantly different between groups (4.81 ±â€…1.07 vs. 4.16 ±â€…1.59 days; P  = 0.067), the PKRNC group required a second hospitalization to remove the elastic intramedullary nail 3 months after the operation. PKRC and PKRNC both achieved satisfactory outcomes for radial neck fractures in children. The operation time in the PKRC group was significantly lower than in the PKRNC group. PKRC does not require reoperation to remove internal fixation. Therefore, PKRC is recommended for radial neck fractures in children.

Endothelial cell-derived RSPO3 activates Gαi1/3-Erk signaling and protects neurons from ischemia/reperfusion injury.

The current study explores the potential function and the underlying mechanisms of endothelial cell-derived R-spondin 3 (RSPO3) neuroprotection against ischemia/reperfusion-induced neuronal cell injury. In both neuronal cells (Neuro-2a) and primary murine cortical neurons, pretreatment with RSPO3 ameliorated oxygen and glucose deprivation (OGD)/re-oxygenation (OGD/R)-induced neuronal cell death and oxidative injury. In neurons RSPO3 activated the Akt, Erk and ß-Catenin signaling cascade, but only Erk inhibitors reversed RSPO3-induced neuroprotection against OGD/R. In mouse embryonic fibroblasts (MEFs) and neuronal cells, RSPO3-induced LGR4-Gab1-Gαi1/3 association was required for Erk activation, and either silencing or knockout of Gαi1 and Gαi3 abolished RSPO3-induced neuroprotection. In mice, middle cerebral artery occlusion (MCAO) increased RSPO3 expression and Erk activation in ischemic penumbra brain tissues. Endothelial knockdown or knockout of RSPO3 inhibited Erk activation in the ischemic penumbra brain tissues and increased MCAO-induced cerebral ischemic injury in mice. Conversely, endothelial overexpression of RSPO3 ameliorated MCAO-induced cerebral ischemic injury. We conclude that RSPO3 activates Gαi1/3-Erk signaling to protect neuronal cells from ischemia/reperfusion injury.

The mitochondrial protein TIMM44 is required for angiogenesis in vitro and in vivo.

The mitochondrial integrity and function in endothelial cells are essential for angiogenesis. TIMM44 (translocase of inner mitochondrial membrane 44) is essential for integrity and function of mitochondria. Here we explored the potential function and the possible mechanisms of TIMM44 in angiogenesis. In HUVECs, human retinal microvascular endothelial cells and hCMEC/D3 brain endothelial cells, silence of TIMM44 by targeted shRNA largely inhibited cell proliferation, migration and in vitro capillary tube formation. TIMM44 silencing disrupted mitochondrial functions in endothelial cells, causing mitochondrial protein input arrest, ATP reduction, ROS production, and mitochondrial depolarization, and leading to apoptosis activation. TIMM44 knockout, by Cas9-sgRNA strategy, also disrupted mitochondrial functions and inhibited endothelial cell proliferation, migration and in vitro capillary tube formation. Moreover, treatment with MB-10 ("MitoBloCK-10"), a TIMM44 blocker, similarly induced mitochondrial dysfunction and suppressed angiogenic activity in endothelial cells. Contrarily, ectopic overexpression of TIMM44 increased ATP contents and augmented endothelial cell proliferation, migration and in vitro capillary tube formation. In adult mouse retinas, endothelial knockdown of TIMM44, by intravitreous injection of endothelial specific TIMM44 shRNA adenovirus, inhibited retinal angiogenesis, causing vascular leakage, acellular capillary growth, and retinal ganglion cells degeneration. Significant oxidative stress was detected in TIMM44-silenced retinal tissues. Moreover, intravitreous injection of MB-10 similarly induced oxidative injury and inhibited retinal angiogenesis in vivo. Together, the mitochondrial protein TIMM44 is important for angiogenesis in vitro and in vivo, representing as a novel and promising therapeutic target of diseases with abnormal angiogenesis.

Efficacy of short-term splint immobilization in the treatment of pediatric discoid lateral meniscus after saucerization management.

There are no universal guidelines for rehabilitation after saucerization for children with discoid lateral meniscus. This study determined if short-term knee splint immobilization and delayed rehabilitation produces the same benefit as early rehabilitation after saucerization in children, in terms of knee function and pain intensity. A retrospective review was performed by categorizing patients into 2 groups depending on whether a splint immobilization was adopted postoperatively: for group A, rehabilitation began early without splint immobilization after surgery, and for group B, a knee splint was immobilized for 2 weeks. Numerical rating scale scores were collected in patients 1, 3, and 7 days, Lysholm scores were measured at 4 and 8 weeks postoperatively, and the gradual return to normal activities was documented. Forty-eight patients and 53 knees were included: group A had 30 patients with 31 knees, and group B had 18 patients with 22 knees. There was no improvement in numerical rating scale scores on the 1st (P=.519), 3rd (P=.421), and 7th (P=.295) postoperative days in group B. The Lysholm scores of group A (62.94 ±â€…8.68) was higher than that of group B (46.68 ±â€…9.82) measured 4 weeks following surgery, but there was no difference at 8 weeks (P=.237), and both groups had similar time to return to normal activities (P=.363). For discoid lateral meniscus patients who underwent isolated saucerization, short-term splint immobilization did not significantly help relieve postoperative pain. There was a comparable time-course for return to normal activities in both study groups.

Dexamethasone promotes osteoblast apoptosis through the Chk2/p53 signaling pathway.

BACKGROUND: Glucocorticoids (GCs) are widely used to treat inflammatory or autoimmune diseases. However, several studies have reported that the use of GCs can lead to numerous complications, the most serious of which are osteoporosis and osteonecrosis of the femoral head (ONFH). Osteoblast apoptosis has been identified as an important event in the development of GC-induced osteoporosis and ONFH. However, the mechanisms underlying the regulation of these processes have not yet been explored. OBJECTIVES: To observe the effect of dexamethasone (Dex) on the apoptosis of osteoblasts and explore its mechanism, as well as provide a new therapeutic idea for GC­induced osteoporosis and ONFH. MATERIAL AND METHODS: Cell proliferation and apoptosis of MC3T3-E1 cells after Dex treatment were determined using the CellTiter-Glo® Luminescent Cell Viability Assay kit and Annexin V-FITC/PI Double Staining Apoptosis Detection Kit, respectively. The expression of caspase-3/cleaved caspase-3 and poly(ADP-ribose) polymerase (PARP)/cleaved PARP in MC3T3-E1 cells after Dex treatment was determined with western blotting. The expression of p53 and checkpoint kinase 2 (Chk2) in MC3T3-E1 cells after Dex treatment was analyzed using western blotting and polymerase chain reaction (PCR). The effects of p53 knockdown and Chk2 knockdown on Dex-induced apoptosis of MC3T3-E1 cells were also characterized. RESULTS: Dexamethasone remarkably inhibited cell growth and induced the apoptosis of MC3T3-E1 cells. We also observed that Dex induced osteoblast apoptosis by promoting p53 expression. The regulatory effect of Dex on p53 expression is mediated by the upregulation of Chk2, which interacted with p53 and inhibited p53 degradation. The knockdown of p53 alleviated Dex-induced MC3T3-E1 cell apoptosis by decreasing the expression of cleaved caspase-3 and cleaved PARP. CONCLUSIONS: We demonstrated that Dex increased Chk2 protein expression, which stabilized the protein expression of p53, and in turn promoted osteoblast apoptosis.

Open Reduction of Displaced Radial Neck Fractures in Children by Internal Fixation Techniques: Comparison of Percutaneous Kirschner Wiring and Elastic Stable Intramedullary Nailing.

Background: Although most paediatric radial neck fractures can be treated with closed reduction, some severely displaced fractures require open reduction. The purpose of this study is to compare the effects of ESIN and KW fixation in open reduction of radial neck fracture in children. Methods: Twenty-four patients with mean age of 8.5 years were included. Four of the patients had a Judet type III fracture and 20 had a Judet type IV fracture. Ten patients who underwent percutaneous KW fixation were assigned to group A, while 14 patients who underwent ESIN fixation were assigned to group B. Variables of interest included age, sex, fracture type, associated lesions, surgical time, fracture reduction, cost, follow-up, healing time, X-rays, clinical outcomes, and complications. Results: There were no significant between-group differences in sex, age, additional injuries, fracture type, and quality of reduction. Costs were significantly lower in Group A. Fracture healing was achieved in 23 of 24 patients (10/10 in group A and 13/14 in group B). In a postoperative elbow function assessment based on the Steele and Graham classification, 80% of patients in group A had a score of excellent or good, compared to 78.6% of patients in group B. Two cases of nail shifting and joint protrusion were observed in group B, one of which also presented with nonunion during follow-up. Conclusions: Both KW and ESIN may achieve good clinical outcomes, but KW is associated with lower costs, easier implant removal (without the need for a secondary surgery), and lower iatrogenic complications.

DCAF1-targeting microRNA-3175 activates Nrf2 signaling and inhibits dexamethasone-induced oxidative injury in human osteoblasts.

Activation of nuclear-factor-E2-related factor 2 (Nrf2) signaling can protect human osteoblasts from dexamethasone-induced oxidative injury. DDB1 and CUL4 associated factor 1 (DCAF1) is a novel ubiquitin E3 ligase for Nrf2 protein degradation. We identified a novel DCAF1-targeting miRNA, miR-3175. RNA pull-down, Argonaute 2 RNA-immunoprecipitation, and RNA fluorescent in situ hybridization results confirmed a direct binding between miR-3175 and DCAF1 mRNA in primary human osteoblasts. DCAF1 3'-untranslated region luciferase activity and its expression were significantly decreased after miR-3175 overexpression but were augmented with miR-3175 inhibition in human osteoblasts and hFOB1.19 osteoblastic cells. miR-3175 overexpression activated Nrf2 signaling, causing Nrf2 protein stabilization, antioxidant response (ARE) activity increase, and transcription activation of Nrf2-dependent genes in human osteoblasts and hFOB1.19 cells. Furthermore, dexamethasone-induced oxidative injury and apoptosis were largely attenuated by miR-3175 overexpression in human osteoblasts and hFOB1.19 cells. Importantly, shRNA-induced silencing or CRISPR/Cas9-mediated Nrf2 knockout abolished miR-3175 overexpression-induced osteoblast cytoprotection against dexamethasone. Conversely, DFAC1 knockout, by the CRISPR/Cas9 method, activated the Nrf2 cascade and inhibited dexamethasone-induced cytotoxicity in hFOB1.19 cells. Importantly, miR-3175 expression was decreased in necrotic femoral head tissues of dexamethasone-taking patients, where DCAF1 mRNA was upregulated. Together, silencing DCAF1 by miR-3175 activated Nrf2 signaling to inhibit dexamethasone-induced oxidative injury and apoptosis in human osteoblasts.

Treatment Choice of Complete Distal Forearm Fractures in 8 to 14 Years Old Children.

BACKGROUND: New surgical techniques have challenged traditional guidelines for nonsurgical treatment in pediatric and adolescent distal forearm fractures. This study was performed to compare outcomes and costs between closed reduction with percutaneous pinning (CRPP) and closed reduction with casting in the treatment of complete distal forearm fractures in children 8 to 14 years old. METHODS: A retrospective cohort study was performed of 175 displaced distal forearm fractures treated with 2 different methods in the emergency department of a children's trauma center. One hundred and fourteen children were managed using CRPP. The remaining 61 were treated with closed reduction and casting. All patients had initial follow-up radiographs. The quality of reduction and the residual angulation in both the coronal and sagittal planes were recorded. Outcomes included the angulation after reduction, residual angulation at final follow-up, radiation exposure, total immobilization time, days absent from school, total costs, and postoperative complications. RESULTS: The postreduction sagittal plane angulation was significantly lower in the CRPP group (P=0.037). While residual deformity between the groups at the 6-month final follow-up was not significantly different in either the sagittal or coronal planes (P=0.486, 0.726), patients in the nonoperative group received greater radiation than those in the operative group (P<0.001). Patients in the nonoperative group missed fewer classes and sustained lower costs (P<0.001, <0.001). The mean immobilization time in each group was not significantly different (31.4±4.4 vs. 32.8±5.9 d; P=0.227). CONCLUSIONS: Although the postreduction quality was a little better and radiation exposure was less in the CRPP group, there was no difference between the 2 groups in angulation, total immobilization time, or complication rates after 6 months. The cost and time absent from school of patients in the nonoperative group was significantly lower than in the operative group. There is no clear advantage to CRPP treatment on outcomes. Therefore, closed reduction and casting is recommended in complete distal forearm fractures of children 8 to 14 years old. LEVEL OF EVIDENCE: Level III-therapeutic study.

miR-143 is implicated in growth plate injury by targeting IHH in precartilaginous stem cells.

Precartilaginous stem cells (PCSCs) are able to initiate chondrocyte and bone development. The present study aimed to investigate the role of miR-143 and the underlying mechanisms involved in PCSC proliferation. In a rat growth plate injury model, tissue from the injury site was collected and the expression of miR-143 and its potential targets was determined. PCSCs were isolated from the rabbits' distal epiphyseal growth plate. Cell viability, DNA synthesis, and apoptosis were determined with MTT, BrdU, and flow cytometric analysis, respectively. Real time PCR and western blot were performed to detect the mRNA and protein expression of the indicated genes. Indian hedgehog (IHH) was identified as a target gene for miR-143 with luciferase reporter assay. Decreased expression of miR-143 and increased expression of IHH gene were observed in the growth plate after injury. miR-143 mimics decreased cell viability and DNA synthesis and promoted apoptosis of PCSCs. Conversely, siRNA-mediated inhibition of miR-143 led to increased growth and suppressed apoptosis of PCSCs. Transfection of miR-143 decreased luciferase activity of wild-type IHH but had no effect when the 3'-UTR of IHH was mutated. Furthermore, the effect of miR-143 overexpression was neutralized by overexpression of IHH. Our study showed that miR-143 is involved in growth plate behavior and regulates PCSC growth by targeting IHH, suggesting that miR-143 may serve as a novel target for PCSC-related diseases.

Open reduction and internal fixation for displaced Salter-Harris type II fractures of the distal tibia: a retrospective study of sixty-five cases in children.

BACKGROUND: The treatment for displaced Salter-Harris II (S-H II) distal tibia fractures remains controversial. The purpose of this study was to review S-H II distal tibia fractures and evaluate the rate of premature physeal closure (PPC) treated by open reduction and internal fixation (ORIF). METHODS: We reviewed the charts and radiographs of S-H II fractures of the distal tibia with displacement > 3 mm between 2012 and 2019 treated by ORIF. Patients were followed up for a minimum of 6 months. CT scans of injured side or contralateral ankle radiograph were obtained if there was any evidence of PPC. Any angular deformity or shortening of the involved leg was documented. Multivariable logistic regression was performed to identify risk factors for the occurrence of PPC. RESULTS: A total of 65 patients with a mean age of 11.8 years were included in this study. The mean initial displacement was 8.0 mm. All patients but one were treated within 7 days after injury and the mean interval was 3.7 days. Supination-external rotation injuries occurred in 50 patients, pronation-eversion external rotation in 13, and supination-plantar flexion in two. The residual gap was less than 1 mm in all patients following ORIF and all fractures healed within 4-6 weeks. Superficial skin infection developed in one patient. Ten patients complained of the cosmetic scar. The rate of PPC was 29.2% and two patients with PPC developed a varus deformity of the ankle. Patients with associated fibular fracture had 7 times greater odds of developing PPC. Age, gender, injured side, mechanism of injury, amount of initial displacement, interval from injury to surgery, or energy of injury did not significantly affect the rate of PPC. CONCLUSIONS: ORIF was an effective choice of treatment for S-H II distal tibia fractures with displacement > 3 mm to obtain a satisfactory reduction. PPC is a common complication following ORIF. The presence of concomitant fibula fracture was associated with PPC.

Open reduction and Herbert screw fixation of Pipkin type IV femoral head fracture in an adolescent: A case report.

BACKGROUND: Femoral head fracture is extremely rare in children. This may be the youngest patient with femoral head fracture ever reported in the literature. There are few pediatric studies that focus on cases treated with open reduction via the modified Hardinge approach. CASE SUMMARY: A 14-year-old female adolescent suffered a serious traffic accident when she was sitting on the back seat of a motorcycle. A pelvic radiograph and computed tomography revealed a proximal femoral fracture and slight acetabular rim fracture. This was diagnosed as a Pipkin type IV femoral head fracture. An open reduction and Herbert screw fixation was performed via a modified Hardinge approach. After 1-year follow-up, the patient could walk without aid and participate in physical activities. The X-ray results showed that the fractures healed well with no evidence of complications. CONCLUSION: Open reduction and Herbert screw fixation is an available therapy to treat Pipkin type IV femoral head fractures in children.

Concurrent ipsilateral Tillaux fracture and medial malleolar fracture in adolescents: management and outcome.

BACKGROUND: The concurrent ipsilateral Tillaux fracture with medial malleolar fracture in adolescents commonly suffer from high-energy injury, making treatment more difficult. The aim of this study was to discuss the mechanism on injury, diagnosis, and treatment of this complex fracture pattern. METHODS: The charts and radiographs of six patients were reviewed. The function was assessed by the American Orthopedic Foot and Ankle Society ankle-hindfoot scores. RESULTS: The mean age at operation was 12.8 years. The mean interval from injury to operation was 7.7 days. Five Tillaux fractures and all medial malleolar fractures were shown on AP plain radiographs. One Tillaux fracture and two cases with avulsion of posterolateral tibial aspect were confirmed in axial computerized tomography. There was talar subluxation laterally with medial space widening in three and syndesmotic disruption in one. There were five patients sustaining ipsilateral distal fibular fractures. All fractures, except nonunion in two medial malleolar fractures and in one Tillaux fracture, healed within 6-8 weeks. There was one case of osteoarthritis of ankle joint. The average AOFAS score was 88.7. CONCLUSIONS: Computerized tomography is helpful in identifying the fracture pattern. Anatomic reduction and internal fixation of Tillaux and medial malleolar fracture was recommended to restore the articular surface congruity and ankle stability.

MiR-132/212 promotes the growth of precartilaginous stem cells (PCSCs) by regulating Ihh/PTHrP signaling pathway.

Precartilaginous stem cells (PCSCs) are adult stem cells that can initiate chondrocytes and bone development. In the present study, we explored whether miR-132/212 was involved in the proliferation of PCSCs via Hedgehog signaling pathway. PCSCs were isolated and purified with the fibroblast growth factor receptor-3 (FGFR-3) antibody. Cell viability, DNA synthesis and apoptosis were measured using MTT, BrdU and flow cytometric analysis. The mRNA and protein expression were detected by real-time PCR and Western blot, respectively. The target gene for miR-132/212 was validated by luciferase reporter assay. Results showed that transfection with miR-132/212 mimic significantly increased cell viability and DNA synthesis, and inhibited apoptosis of PCSCs. By contrast, miR-132/212 inhibitor could suppress growth and promote apoptosis of PCSCs. Luciferase reporter assays indicated that transfection of miR-132/212 led to a marked reduction of luciferase activity, but had no effect on PTCH1 3'-UTR mutated fragment, suggesting that Patched1 (PTCH1) is a target of miR-132/212. Furthermore, treatment with miR-132/212 mimics obviously increased the protein expression of Indian hedgehog (Ihh) and parathyroid hormone related protein (PTHrP), which was decreased after treatment with Hedgehog signaling inhibitor, cyclopamine. We also found that inhibition of Ihh/PTHrP signaling by cyclopamine significantly suppressed growth and DNA synthesis, and induced apoptosis in PCSCs. These findings demonstrate that miR-132/212 promotes growth and inhibits apoptosis in PCSCs by regulating PTCH1-mediated Ihh/PTHrP pathway, suggesting that miR-132/212 cluster might serve as a novel target for bone diseases.

PGK1 depletion activates Nrf2 signaling to protect human osteoblasts from dexamethasone.

Activation of nuclear-factor-E2-related factor 2 (Nrf2) cascade can alleviate dexamethasone (DEX)-induced oxidative injury and death of human osteoblasts. A recent study has shown that phosphoglycerate kinase 1 (PGK1) inhibition/depletion will lead to Kelch-like ECH-associated protein 1 (Keap1) methylglyoxal modification, thereby activating Nrf2 signaling cascade. Here, in OB-6 osteoblastic cells and primary human osteoblasts, PGK1 silencing, by targeted shRNA, induced Nrf2 signaling cascade activation, causing Nrf2 protein stabilization and nuclear translocation, as well as increased expression of ARE-dependent genes (HO1, NQO1, and GCLC). Functional studies demonstrated that PGK1 shRNA largely attenuated DEX-induced oxidative injury and following death of OB-6 cells and primary osteoblasts. Furthermore, PGK1 knockout, by the CRISPR/Cas9 method, similarly induced Nrf2 signaling activation and protected osteoblasts from DEX. Importantly, PGK1 depletion-induced osteoblast cytoprotection against DEX was almost abolished by Nrf2 shRNA. In addition, Keap1 shRNA mimicked and nullified PGK1 shRNA-induced anti-DEX osteoblast cytoprotection. At last we show that PGK1 expression is downregulated in human necrotic femoral head tissues of DEX-taking patients, correlating with HO1 depletion. Collectively, these results show that PGK1 depletion protects human osteoblasts from DEX via activation of Keap1-Nrf2 signaling cascade.

Treatment of distal metaphyseal tibia fractures using an external fixator in children.

INTRODUCTION: Current treatment of pediatric distal metaphyseal tibial/fibular fractures is challenging due to poor skin and soft tissue coverage and limited blood supply to the distal tibia area in children. It remains unknown whether the SK combined external fixator (made by Double Medical Technology Inc., China) is effective for the treatment of distal metaphyseal tibia/fibula fractures in children. HYPOTHESIS: We hypothesized that SK combined external fixator could achieve satisfying outcomes for pediatric distal metaphyseal tibia/fibula fractures. PATIENTS AND METHODS: A total of 19 pediatric patients with a median age of 6 years (range: 3.8-12.0 years), who had distal tibia/fibula metaphyseal fractures and attended our hospital between January 2017 and November 2017, were evaluated. All patients with tibia fracture had closed reduction and percutaneously fixed SK combined external fixators. Radiographs were taken at an average of every 4 weeks to evaluate the healing of the fracture. Complications were recorded, and the stability of the pin clamp and rod were also checked. Follow-up was conducted for up to 13 months. All patients provided informed consent for publication of the case. RESULTS: All patients achieved a satisfactory clinical outcome at the final follow-up. Weight-bearing exercises were started at post-operative 2 weeks. Bone union was obtained at 8 weeks post-operation on average. No delayed healing or nonunion was observed, although one case of pin site infection and three cases of pin clamp loosening occurred. DISCUSSION: Three-dimensional SK combined external fixators are light, easy to apply, minimally invasive, and result in low rates of complications. They provide excellent stability for pediatric distal tibia/fibula metaphyseal fractures. LEVEL OF EVIDENCE: IV.

Targeting Keap1 by miR-626 protects retinal pigment epithelium cells from oxidative injury by activating Nrf2 signaling.

Activation of the NF-E2-related factor 2 (Nrf2) cascade can offer significant protection against oxidative stress in retinal pigment epithelium (RPE) cells. Here, we identified a novel kelch-like ECH-associated protein 1 (Keap1)-targeting microRNA, microRNA-626 (miR-626) that activates Nrf2 signaling. In ARPE-19 cells and primary human RPE cells, ectopic overexpression of miR-626 targeting the 3'-UTR (3'-untranslated region) of Keap1 downregulated its expression, promoting Nrf2 protein stabilization and nuclear translocation, leading to expression of ARE-dependent genes (HO1, NOQ1 and GCLC). Functional studies showed that miR-626 protected RPE cells from hydrogen peroxide (H2O2)-induced oxidative injury. Conversely, miR-626 inhibition induced Keap1 upregulation and Nrf2 cascade inhibition, exacerbating oxidative injury in RPE cells. Further studies demonstrated that miR-626 was ineffective in Keap1-knockout or Nrf2-knockout RPE cells. Importantly, miR-626 also activated Keap1-Nrf2 signaling cascade in human lens epithelial cells (HLECs) and primary human retinal ganglion cells (RGCs), providing protection from H2O2. At last, we show that plasma miR-626 levels are significantly downregulated in age-related macular degeneration (AMD) patients than those in the healthy donors. We conclude that targeting Keap1 by miR-626 protects RPE cells and other ophthalmic cells from oxidative injury via activation of Nrf2 signaling cascade.