Aberrant miR-145-5p/β-catenin signal impairs osteocyte function in adolescent idiopathic scoliosis

The Involvement of microRNAs in Bone Remodeling Signaling Pathways and Their Role in the Development of Osteoporosis

Bone remodeling, crucial for maintaining the balance between bone resorption and formation, relies on the coordinated activity of osteoclasts and osteoblasts. During osteoclastogenesis, hematopoietic stem cells (HSCs) differentiate into the osteoclast lineage through the signaling pathways OPG/RANK/RANKL. On the other hand, during osteoblastogenesis, mesenchymal stem cells (MSCs) differentiate into the osteoblast lineage through activation of the signaling pathways TGF-β/BMP/Wnt. Recent studies have shown that bone remodeling is regulated by post-transcriptional mechanisms including microRNAs (miRNAs). miRNAs are small, single-stranded, noncoding RNAs approximately 22 nucleotides in length. miRNAs can regulate virtually all cellular processes through binding to miRNA-response elements (MRE) at the 3' untranslated region (3'UTR) of the target mRNA. miRNAs are involved in controlling gene expression during osteogenic differentiation through the regulation of key signaling cascades during bone formation and resorption. Alterations of miRNA expression could favor the development of bone disorders, including osteoporosis. This review provides a general description of the miRNAs involved in bone remodeling and their significance in osteoporosis development.

Investigating the Differential Circulating microRNA Expression in Adolescent Females with Severe Idiopathic Scoliosis: A Proof-of-Concept Observational Clinical Study

Adolescent Idiopathic Scoliosis (AIS) is the most common form of three-dimensional spinal disorder in adolescents between the ages of 10 and 18 years of age, most commonly diagnosed in young women when severe disease occurs. Patients with AIS are characterized by abnormal skeletal growth and reduced bone mineral density. The etiology of AIS is thought to be multifactorial, involving both environmental and genetic factors, but to date, it is still unknown. Therefore, it is crucial to further investigate the molecular pathogenesis of AIS and to identify biomarkers useful for predicting curve progression. In this perspective, the relative abundance of a panel of microRNAs (miRNAs) was analyzed in the plasma of 20 AIS patients and 10 healthy controls (HC). The data revealed a significant group of circulating miRNAs dysregulated in AIS patients compared to HC. Further bioinformatic analyses evidenced a more restricted expression of some miRNAs exclusively in severe AIS females. These include some members of the miR-30 family, which are considered promising regulators for treating bone diseases. We demonstrated circulating extracellular vesicles (EVs) from severe AIS females contained miR-30 family members and decreased the osteogenic differentiation of mesenchymal stem cells. Proteomic analysis of EVs highlighted the expression of proteins associated with orthopedic disease. This study provides preliminary evidence of a miRNAs signature potentially associated with severe female AIS and suggests the corresponding vesicular component may affect cellular mechanisms crucial in AIS, opening the scenario for in-depth studies on prognostic differences related to gender and grade.

Advances in epigenetic research of adolescent idiopathic scoliosis and congenital scoliosis

Scoliosis is a three-dimensional structural deformity of the spine; more than 80% of scoliosis has no specific pathogenesis but is understood to be closely related to genetic, hormonal, and environmental factors. In recent years, the epigenetic alterations observed in scoliosis have been analyzed in numerous studies to determine the pathogenesis and progression of this condition, however, there is currently no comprehensive review of the epigenetic factors to date. We searched PubMed, Embase, and Web of Science databases for relative studies without language and date restrictions in March 2023. Twenty-five studies were included in this review and analyzed from the four main aspects of epigenetic alteration: DNA methylation, non-coding RNAs, histone modifications, and chromatin remodeling. The relationship between DNA methylation, non-coding RNAs, and scoliosis was considerably reported in the literature, and the corresponding related signaling pathways and novel biomarkers observed in scoliosis provide insights into innovative prevention and treatment strategies. However, the role of histone modifications is rarely reported in scoliosis, and few studies have investigated the relationship between scoliosis and chromatin remodeling. Therefore, these related fields need to be further explored to elucidate the overall effects of epigenetics in scoliosis.

Risk factors associated with low bone mineral density in children with idiopathic scoliosis: a scoping review

BACKGROUND

Children with idiopathic scoliosis (IS) have a high risk of osteoporosis and IS with low bone mineral density (BMD) are susceptible to curve progression. This review aims to explore the risk factors of low BMD in children with IS.

METHODS

Studies were retrieved from 5 databases that were published up to January 2022. Search terms are keywords in titles or abstracts, including subject headings related to "Scoliosis", "Bone Mineral Density", and "Risk Factors". Observational studies on risk factors of low BMD in children with IS were enrolled in this review. The number of studies, sample size, outcome measures, research type, endocrine, and lifestyle-related factors, gene/signal pathway, and other contents were extracted for qualitative analysis.

RESULTS

A total of 56 studies were included in this scoping review. Thirty studies involved genetic factors that may affect BMD, including the Vitamin-D receptor gene, RANK/RANKL signal pathway, the function of mesenchymal stem cells, Runx2, Interleukin-6 (IL-6), and miR-145/β-catenin pathway. Eight studies mentioned the influence of endocrine factors on BMD, and the results showed that serum levels of IL-6, leptin and its metabolites, and ghrelin in children with IS were different from the age-matched controls. In addition, there were 18 articles on lifestyle-related factors related to low BMD in children with IS, consisting of physical activity, calcium intake, Vitamin D level, and body composition.

CONCLUSIONS

Genetic, endocrine, and lifestyle-related factors might relate to low BMD and even osteoporosis in IS. To prevent osteoporosis, the effectiveness of regular screening for low BMD risk factors in children with IS needs to be investigated. Additionally, clear risk factors suggest strategies for bone intervention. Future studies should consider the effectiveness of calcium and vitamin D supplements and physical activity in BMD improvement.

Clinical features and molecular characterization of Chinese patients with FKBP10 variants

BACKGROUND

Osteogenesis imperfecta (OI) is a group of rare skeletal dysplasia. Long bone deformity and scoliosis are often associated with progressively deforming types of OI. FKBP65 (encoded by FKBP10, OMIM *607063) plays a crucial role in the processing of type I procollagen. Autosomal recessive variants in FKBP10 result in type XI osteogenesis imperfecta.

METHODS

Patients diagnosed with OI were recruited for a genetic test. RT-PCR and Sanger sequencing were applied to confirm the splicing defect in FKBP10 mRNA with the splice-site variant. The bone structure was characterized by Goldner's trichrome staining. Bioinformatic analyses of bulk RNA sequencing data were performed to examine the effect of the FKBP10 variant on gene expression.

RESULTS

Here we reported three children from a consanguineous family harboured a homozygous splice-site variant (c.918-3C > G) in FKBP10 intron and developed long bone deformity and early onset of scoliosis. We also observed frequent long bone fractures and spinal deformity in another 3 OI patients with different FKBP10 variants. The homozygous splicing variant identified in the fifth intron of FKBP10 (c.918-3C > G) led to abnormal RNA processing and loss of FKBP65 protein and consequently resulted in aberrant collagen alignment and porous bone morphology. Analysis of transcriptomic data indicated that genes involved in protein processing and osteoblast differentiation were significantly affected in the patient-derived osteoblasts.

CONCLUSION

Our study characterized the clinical features of OI patients with FKBP10 variants and revealed the pathogenesis of the c.918-3C > G variant. The molecular analyses helped to gain insight into the deleterious effects of FKBP10 variants on collagen processing and osteoblast differentiation.

Sirt3 mediates the benefits of exercise on bone in aged mice

Exercise in later life is important for bone health and delays the progression of osteoporotic bone loss. Osteocytes are the major bone cells responsible for transforming mechanical stimuli into cellular signals through their highly specialized lacunocanalicular networks (LCN). Osteocyte activity and LCN degenerate with aging, thus might impair the effectiveness of exercise on bone health; however, the underlying mechanism and clinical implications remain elusive. Herein, we showed that deletion of Sirt3 in osteocytes could impair the formation of osteocyte dendritic processes and inhibit bone gain in response to exercise in vivo. Mechanistic studies revealed that Sirt3 regulates E11/gp38 through the protein kinase A (PKA)/cAMP response element-binding protein (CREB) signaling pathway. Additionally, the Sirt3 activator honokiol enhanced the sensitivity of osteocytes to fluid shear stress in vitro, and intraperitoneal injection of honokiol reduced bone loss in aged mice in a dose-dependent manner. Collectively, Sirt3 in osteocytes regulates bone mass and mechanical responses through the regulation of E11/gp38. Therefore, targeting Sirt3 could be a novel therapeutic strategy to prevent age-related bone loss and augment the benefits of exercise on the senescent skeleton.

The Potential Role of Dysregulated miRNAs in Adolescent Idiopathic Scoliosis and 22q11.2 Deletion Syndrome

Background: Adolescent idiopathic scoliosis (AIS), affecting 2-4% of adolescents, is a multifactorial spinal disease. Interactions between genetic and environmental factors can influence disease onset through epigenetic mechanisms, including DNA methylation, histone modifications and miRNA expression. Recent evidence reported that, among all clinical features in individuals with 22q11.2 deletion syndrome (DS), scoliosis can occur with a higher incidence than in the general population. Methods: A PubMed and Ovid Medline search was performed for idiopathic scoliosis in the setting of 22q11.2DS and miRNA according to PRISMA guidelines. Results: Four papers, accounting for 2841 individuals, reported clinical data about scoliosis in individuals with 22q11.2DS, showing that approximately 35.1% of the individuals with 22q11.2DS developed scoliosis. Conclusions: 22q11.2DS could be used as a model for the study of AIS. The DGCR8 gene seems to be essential for microRNA biogenesis, which is why we propose that a possible common pathological mechanism between scoliosis and 22q11.2DS could be the dysregulation of microRNA expression. In the current study, we identified two miRNAs that were altered in both 22q11.2DS and AIS, miR-93 and miR-1306, thus, corroborating the hypothesis that the two diseases share common molecular alterations.

Biological effect of dysregulated LBX1 on adolescent idiopathic scoliosis through modulating muscle carbohydrate metabolism

BACKGROUND CONTEXT

Abnormal energy metabolism such as lower body weight and body mass index (BMI) and less fat mass is widely reported in patients with adolescent idiopathic scoliosis (AIS) and has been implicated in deformity development. However, the underlying mechanism is largely unclear. LBX1 is one of the promising AIS predisposing genes validated by multicenter studies.

PURPOSE

This study aimed to identify differentially expressed proteins (DEPs) relating to energy metabolism in AIS by using proteomic and metabolic analysis and to explore if the expression of these DEPs is associated with clinical parameters and modulated by LBX1.

STUDY DESIGN

This is a cross-sectional study using clinical data and biological samples followed by basic study using a cellular model.

PATIENT SAMPLE

Plasma samples were collected from Chinese girls with nonprogressive and progressive AIS (N=7 and 8, respectively) and age-matched healthy girls (N=50). Paraspinal muscle tissues were collected intraoperatively from concave and convex side of the apex of the major spinal curve in AIS (N=24) and either side from nonscoliosis patients (N=14).

OUTCOME MEASURES

Radiological Cobb angle and basic anthropometric data of recruited subjects were measured. The DEPs and metabolites were compared in plasma using proteomics and metabolomics technique. The relative expression of selected genes was measured in muscles.

METHODS

Plasma samples from AIS were collected at first clinical visit and were further divided into nonprogressive or progressive groups according to Cobb angle changes in 6-year follow-up. Age-matched healthy girls were recruited as control. High-performance liquid chromatography-mass spectrometry based proteomic analysis was carried out in three groups to identify DEPs and their annotated metabolic pathways. An independent cohort was used for validation by gas chromatography-mass spectrometry based metabolomic analysis. Paraspinal muscles were subjected to quantitative polymerase chain reaction (qPCR) followed by correlation analysis. Human skeletal muscle myoblast (HSMM) was used as the cellular model.

RESULTS

The likelihood of aberrant galactose metabolism and glycolysis was found to be associated with AIS curve progression as evidenced by the thirteen DEPs and seven related metabolites according to proteomic and metabolomic analysis. Some of the DEPs showed significantly altered expression in AIS concave and convex sides paraspinal muscles compared with those in nonscoliosis control. Four DEPs were found significantly and negatively correlated with LBX1 in AIS convex side paraspinal muscles. Overexpressing LBX1 in HSMM cells led to increased expression of three DEPs and decreased expression of three DEPs, respectively.

CONCLUSIONS

This is the first integrated proteomic and metabolomic analysis on AIS. Our findings show dysregulated galactose metabolism and glycolysis pathways in progressive group of AIS, suggesting the presence of abnormal energy metabolism at early stage of this disease, and their association with higher risk of progressing into more severe curvature. Evidence from ex vivo study with human muscle biopsies and in vitro study with human myoblast cells propose the possible effect of LBX1 on these two pathways in skeletal muscles. The present study provides new evidence of LBX1 function in AIS via modulating effect on the expression of energy metabolism related genes. This study might provide new insights into etiopathogenesis and development of novel treatment strategy targeting on abnormal body weight and BMI in patients with AIS. Additionally, the plasma proteomic and metabolomic studies suggested new candidates as biomarkers for establishing predictive model for AIS onset/progression.

Circulating MicroRNAs as Biomarkers of Osteoporosis and Fragility Fractures

CONTEXT

Measurement of circulating microRNAs (miRNAs) as potential biomarkers of fragility fracture risk has recently become a subject of investigation.

OBJECTIVE

Measure by next-generation sequencing (NGS), global miRNA expression in serum samples of osteoporotic subjects vs individuals with normal bone mineral density (BMD).

DESIGN

Samples were collected from patients with different bone phenotypes and/or fragility fractures who did not receive any antiresorptive and/or bone-forming drug at the time of blood collection.

SETTING

Samples and data were collected at 7 medical centers in Italy.

PATIENTS

NGS prescreening: 50 osteoporotic patients vs 30 individuals with normal BMD. Droplet digital polymerase chain reaction (ddPCR) validation: 213 patients with different bone phenotypes, including the NGS-analyzed cohort.

RESULTS

NGS identified 5 miRNAs (miR-8085, miR-320a-3p, miR-23a-3p, miR-4497, miR-145-5p) differentially expressed in osteoporosis cases without fractures vs controls. ddPCR validation confirmed lower c-miR-23a-3p expression in osteoporotic patients, with or without fracture, than in osteopenic and normal subjects and increased c-miR-320a-3p expression in osteoporotic patients with fracture and lower expression in osteoporotic patients without fracture. ddPCR analysis showed a significantly increased expression of miR-21-5p in osteoporotic patients, with or without fracture, than in osteopenic and normal subjects, not evidenced by the NGS prescreening.

DISCUSSION

Our study confirmed levels of c-miR-23a-3p and c-miR-21-5p as able to distinguish osteoporotic patients and subjects with normal BMD. Increased levels of c-miR-320a-3p specifically associated with fractures, independently by BMD, suggesting c-miR-320a-3p as a prognostic indicator of fracture risk in osteoporotic patients, to be confirmed in prospective studies on incident fractures.

Upregulation of microRNA-96-5p is associated with adolescent idiopathic scoliosis and low bone mass phenotype

Bone densitometry revealed low bone mass in patients with adolescent idiopathic scoliosis (AIS) and its prognostic potential to predict curve progression. Recent studies showed differential circulating miRNAs in AIS but their diagnostic potential and links to low bone mass have not been well-documented. The present study aimed to compare miRNA profiles in bone tissues collected from AIS and non-scoliotic subjects, and to explore if the selected miRNA candidates could be useful diagnostic biomarkers for AIS. Microarray analysis identified miR-96-5p being the most upregulated among the candidates. miR-96-5p level was measured in plasma samples from 100 AIS and 52 healthy girls. Our results showed significantly higher plasma levels of miR-96-5p in AIS girls with an area under the curve (AUC) of 0.671 for diagnostic accuracy. A model that was composed of plasma miR-96-5p and patient-specific parameters (age, body weight and years since menarche) gave rise to an improved AUC of 0.752. Ingenuity Pathway Analysis (IPA) indicated functional links between bone metabolic pathways and miR-96-5p. In conclusion, differentially expressed miRNAs in AIS bone and plasma samples represented a new source of disease biomarkers and players in AIS etiopathogenesis, which required further validation study involving AIS patients of both genders with long-term follow-up.

Epigenetic and Genetic Factors Related to Curve Progression in Adolescent Idiopathic Scoliosis: A Systematic Scoping Review of the Current Literature

Adolescent idiopathic scoliosis (AIS) is a progressive deformity of the spine. Scoliotic curves progress until skeletal maturity leading, in rare cases, to a severe deformity. While the Cobb angle is a straightforward tool in initial curve magnitude measurement, assessing the risk of curve progression at the time of diagnosis may be more challenging. Epigenetic and genetic markers are potential prognostic tools to predict curve progression. The aim of this study is to review the available literature regarding the epigenetic and genetic factors associated with the risk of AIS curve progression. This review was carried out in accordance with Preferential Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The search was carried out in January 2022. Only peer-reviewed articles were considered for inclusion. Forty studies were included; fifteen genes were reported as having SNPs with significant association with progressive AIS, but none showed sufficient power to sustain clinical applications. In contrast, nine studies reporting epigenetic modifications showed promising results in terms of reliable markers. Prognostic testing for AIS has the potential to significantly modify disease management. Most recent evidence suggests epigenetics as a more promising field for the identification of factors associated with AIS progression, offering a rationale for further investigation in this field.

Sclerostin and Its Involvement in the Pathogenesis of Idiopathic Scoliosis

Idiopathic scoliosis is a disorder of unknown etiology. Bone biopsies from idiopathic scoliosis patients revealed changes at cellular and molecular level. Osteocytic sclerostin is downregulated, and serum level of sclerostin is decreased. Osteocytes in idiopathic scoliosis appear to be less active with abnormal canaliculi network. Differentiation of osteoblasts to osteocytes is decelerated, while Wnt/β-catenin signaling pathway is overactivated and affects normal bone mineralization that leads to inferior mechanical properties of the bone, which becomes susceptible to asymmetrical forces and causes deformity of the spinal column. Targeting bone metabolism during growth by stimulating sclerostin secretion from osteocytes and restoring normal function of Wnt/β-catenin signaling pathway could, in theory, increase bone strength and prevent deterioration of the scoliotic deformity.

Potential Muscle-Related Biomarkers in Predicting Curve Progression to the Surgical Threshold in Adolescent Idiopathic Scoliosis-A Pilot Proteomic Study Comparing Four Non-Progressive vs. Four Progressive Patients vs. A Control Cohort

Previous studies have reported abnormal muscle morphology and functions in patients with adolescent idiopathic scoliosis (AIS). To answer whether such abnormalities could be reflected in their circulation and their clinical implication for predicting curve progression to the surgical threshold, this preliminary study explored the presence of baseline muscle-related proteins and their association with curve progression. Plasma samples were collected at the first clinical visit for AIS, with patients divided into non-progressive or progressive groups (N = four and four) according to their Cobb angle in six-year follow-ups, with age- and sex-matched healthy subjects (N = 50). Then, the samples were subjected to isobaric tags for relative and absolute quantitation (iTRAQ) for global comparison of untargeted protein expression. Seventy-one differentially expressed proteins (DEPs) were found elevated in progressive AIS. Functional analysis showed that 18 of these are expressed in muscles and play an essential role in muscle activities. Among the muscle-related DEPs, α-actin had the highest fold change in progressive/non-progressive groups. This preliminary study firstly suggested higher circulating levels of muscle structural proteins in progressive AIS, indicating the likelihood of structural damage at the microscopic level and its association with progression to the surgical threshold. Further studies with larger sample sizes are warranted to validate these novel candidates for early diagnosis and predicting progression.

MicroRNAs and osteocytes

MicroRNAs, identified in the early 1990s, are believed to regulate approximately 30% of the human genome. The role of microRNA in bone cells was first reported in 2007 in a manuscript showing that microRNA-223 is essential for osteoclast differentiation in vitro, and a few studies reported a role of microRNAs in osteoblasts the same year. The first report of microRNA actions in osteocytes was published in 2010, in which it was demonstrated that the microRNA cluster 23a~27a~24-2 regulates osteocyte differentiation. Since then, few studies have described the role of these 18-25-nucleotide non-coding RNAs on osteocyte biology, reporting osteocytes both as producers and as targets of the actions of microRNAs. We review here the current knowledge on the effects of microRNAs on osteocyte biology.

Association of higher bone turnover with risk of curve progression in adolescent idiopathic scoliosis

OBJECTIVE

Emerging evidence suggest abnormal bone metabolism and defective bone qualities are associated to etipathogenesis of Adolescent Idiopathic Scoliosis (AIS). Systemic low bone mass is important prognosticator to predict risk of curve progression in AIS. The underlying mechanism is still unclear. We hypothesize that aberrant bone turnover correlates with bone qualities in AIS and associates to risk of curve progression.

SUBJECTS AND METHODS

Two cohorts were included in this study. The case-control study recruited 161 AIS girls and 161 ethnic/age-matched healthy girls. The longitudinal cohort recruited 128 AIS girls with two-year follow-up. Areal bone mineral density (BMD) at femoral necks were measured with dual-energy x-ray absorptiometry (DXA), and bone qualities of distal radius by high-resolution peripheral quantitative computed tomography (HR-pQCT). Time-lapse analysis of registered HR-pQCT images estimated local bone remodeling quantitatively. Serum levels of CTX and P1NP were measured with ELISA kits.

RESULTS

AIS presented significantly higher serum level of P1NP. In both AIS and control, the negative correlations were consistently observed between serum CTX/P1NP levels and most cortical bone quality parameters after adjustment to age. Significant correlation between serum bone turnover markers and trabecular bone parameters have been observed only in control. Progressive AIS has significant increase of serum P1NP level at first clinic visit. Time lapse register analysis showed high bone resorption and low net bone gain was associated with risk of progression in AIS.

CONCLUSIONS

Our study characterized AIS with higher serum bone turnover markers, which may contribute to defective bone qualities in AIS. For the first time, we showed that progressive AIS had higher systemic bone turnover markers level and local bone remodeling. This fresh evidence indicated association between disrupted bone turnover and risk of progression of AIS, which set the foundation of new prognostic method and of novel treatment target to curve progression. This study demonstrated the importance of bone metabolism in developing disease management of AIS to achieve goal of early prediction and non-surgical modulation.

Research progress on the etiology and pathogenesis of adolescent idiopathic scoliosis

Etiology of adolescent idiopathic scoliosis (AIS), a complicated three-dimensional spinal deformity with early-onset, receives continuous attention but remains unclear. To gain an insight into AIS pathogenesis, this review searched PubMed database up to June 2019, using key words or medical subject headings terms including "adolescent idiopathic scoliosis," "scoliosis," "pathogenesis," "etiology," "genetics," "mesenchymal stem cells," and their combinations, summarized existing literatures and categorized the theories or hypothesis into nine aspects. These aspects include bone marrow mesenchymal stem cell studies, genetic studies, tissue analysis, spine biomechanics measurements, neurologic analysis, hormone studies, biochemical analysis, environmental factor analysis, and lifestyle explorations. These categories could be a guidance for further etiology or treatment researches to gain inspiration.

From genetics to epigenetics to unravel the etiology of adolescent idiopathic scoliosis

Scoliosis is defined as the three-dimensional (3D) structural deformity of the spine with a radiological lateral Cobb angle (a measure of spinal curvature) of ≥10° that can be caused by congenital, developmental or degenerative problems. However, those cases whose etiology is still unknown, and affect healthy children and adolescents during growth, are the commonest form of spinal deformity, known as adolescent idiopathic scoliosis (AIS). In AIS management, early diagnosis and the accurate prediction of curve progression are most important because they can decrease negative long-term effects of AIS treatment, such as unnecessary bracing, frequent exposure to radiation, as well as saving the high costs of AIS treatment. Despite efforts made to identify a method or technique capable of predicting AIS progression, this challenge still remains unresolved. Genetics and epigenetics, and the application of machine learning and artificial intelligence technologies, open up new avenues to not only clarify AIS etiology, but to also identify potential biomarkers that can substantially improve the clinical management of these patients. This review presents the most relevant biomarkers to help explain the etiopathogenesis of AIS and provide new potential biomarkers to be validated in large clinical trials so they can be finally implemented into clinical settings.

Dysregulated Bone Metabolism Is Related to High Expression of miR-151a-3p in Severe Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis (AIS) is a common complex disease, and bone homeostasis plays an important role in its pathogenesis. Recent advances in epigenetic research show that dysregulated miRNAs may participate in the development of orthopedic diseases and AIS. The aim of this study was to detect differentially expressed miRNAs in severe AIS and elucidate the mechanism of miRNA deregulation in the pathogenesis of AIS. In the present study, miRNA expression profiles were detected in severe and mild AIS patients as well as healthy controls by miRNA sequencing. Candidate miRNAs were validated in a larger cohort. Primary osteoblasts from severe AIS patients were extracted and isolated to determine the effect of the candidate miRNAs on bone metabolism. Finally, we determined the methylation level in primary osteoblasts from severe AIS patients. The result showed that miR-151a-3p was overexpressed in severe AIS patients. Reduced GREM1 expression was observed in primary osteoblasts from severe AIS patients. miR-151a-3p directly inhibited GREM1 in primary osteoblasts. Relatively lower methylation levels were detected in primary osteoblasts from severe AIS patients. In conclusion, our study revealed that plasma miR-151a-3p levels may serve as a biomarker for severe AIS. Overexpression of miR-151a-3p may interrupt bone homeostasis via inhibiting GREM1 expression. Our result may provide a new biomarker for the early detection of AIS and increase our understanding of the pathogenesis of AIS.

Septin4 regulates endoplasmic reticulum stress and apoptosis in melatonin‑induced osteoblasts

Idiopathic scoliosis (IS) is a spinal 3-dimensional deformity with an unknown cause. Melatonin is secreted by the pineal body and contributes to the occurrence and progression of IS. In our previous preliminary study, it was reported that high concentrations of melatonin can induce osteoblast apoptosis, thus acting as an IS treatment, but the mechanism of action is unknown. Therefore, the present study was performed to further investigate the possible mechanism underlying the efficacy of melatonin as a treatment for IS. The present results indicated that high concentrations of melatonin mediate endoplasmic reticulum stress (ERS)-induced apoptosis in hFOB 1.19 cells, and this resulted in a significant and dose-dependent increase in the expression of Septin4, as well as the expression levels of glucose-regulated protein (GRP)78, GRP94 and cleaved caspase-3. Furthermore, osteoblasts were overexpressed with Septin4 and the mechanism via which melatonin induces osteoblast ERS was demonstrated to be via the regulation of Septin4. In addition, it was indicated that cytoskeleton destruction, cell morphology changes and the decrease in the number of cells were aggravated after osteoblasts were overexpressed with Septin4, as indicated by phalloidin and DAPI staining. Collectively, the present results suggest that the Septin4 protein may be a target of ERS in melatonin-induced osteoblast apoptosis, which is involved in bone metabolism diseases, thus providing novel evidence for clinical melatonin treatment of IS.

A validated composite model to predict risk of curve progression in adolescent idiopathic scoliosis

BACKGROUND

In adolescent idiopathic scoliosis (AIS), the continuous search for effective prognostication of significant curve progression at the initial clinical consultation to inform decision for timely treatment and to avoid unnecessary overtreatment remains a big challenge as evidence of the multifactorial etiopathogenic nature is increasingly reported. This study aimed to formulate a composite model composed of clinical parameters and circulating markers in the prediction of curve progression.

METHOD

This is a two-phase study consisting of an exploration cohort (120 AIS, mean Cobb angle of 25°± 8.5 at their first clinical visit) and a validation cohort (51 AIS, mean Cobb angle of 23° ± 5.0° at the first visit). Patients with AIS were followed-up for a minimum of six years to formulate a composite model for prediction. At the first visit, clinical parameters were collected from routine clinical practice, and circulating markers were assayed from blood.

FINDING

We constructed the composite predictive model for curve progression to severe Cobb angle > 40° with a high HR of 27.9 (95% CI of 6.55 to 119.16). The area under curve of the composite model is higher than that of individual parameters used in current clinical practice. The model was validated by an independent cohort and achieved a sensitivity of 72.7% and a specificity of 90%.

INTERPRETATION

This is the first study proposing and validating a prognostic composite model consisting of clinical and circulating parameters which could quantitatively evaluate the probability of curve progression to a severe curvature in AIS at the initial consultation. Further validation in clinic will facilitate application of composite model in assisting objective clinical decision.

Emerging roles of non-coding RNAs in scoliosis

Scoliosis, a complex three‐dimensional deformity of the spine with the Cobb angle (a measure of the spinal lateral curvature) >10 degree, encompasses a spectrum of pathologies, including congenital, idiopathic, syndromic and neuromuscular aetiologies. The pathogenesis is multifactorial involving both environmental and genetic factors but the exact cellular and molecular mechanisms of disease development remain largely unknown. Emerging evidence showed that non‐coding RNAs (ncRNAs), namely microRNAs, long ncRNAs and circular RNAs, are deregulated in many orthopaedic diseases, including scoliosis. Importantly, these deregulated ncRNAs functionally participate in the initiation and progression of scoliosis. Here, we review recent progress in ncRNA research on scoliosis.

Abnormal lacuno-canalicular network and negative correlation between serum osteocalcin and Cobb angle indicate abnormal osteocyte function in adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a prevalent spinal deformity occurring during peripubertal growth period that affects 1-4% of adolescents globally without clear etiopathogenetic mechanism. Low bone mineral density is an independent and significant prognostic factor for curve progression. Currently, the cause underlying low bone mass in AIS remains elusive. Osteocytes play an important role in bone metabolism and mineral homeostasis, but its role in AIS has not been studied. In the present study, iliac bone tissues were harvested from 21 patients with AIS (mean age of 14.3 ± 2.20 yr old) with a mean Cobb angle of 55.6 ± 10.61° and 13 non-AIS controls (mean age of 16.5 ± 4.79 yr old) intraoperatively. Acid-etched scanning electron microscopy (SEM) images of AIS demonstrated abnormal osteocytes that were more rounded and cobblestone-like in shape and were aligned in irregular clusters with shorter and disorganized canaliculi. Further quantitative analysis with FITC-Imaris technique showed a significant reduction in the canalicular number and length as well as an increase in lacunar volume and area in AIS. SEM with energy-dispersive X-ray spectroscopy analysis demonstrated a lower calcium-to-phosphorus ratio at the perilacunar/canalicular region. Moreover, microindentaion results revealed lower values of Vickers hardness and elastic modulus in AIS when compared with controls. In addition, in the parallel study of 99 AIS (27 with severe Cobb angle of 65.8 ± 14.1° and 72 with mild Cobb angle of 26.6 ± 9.1°) with different curve severity, the serum osteocalcin level was found to be significantly and negatively associated with the Cobb angle. In summary, the findings in this series of studies demonstrated the potential link of abnormal osteocyte lacuno-canalicular network structure and function to the observed abnormal bone mineralization in AIS, which may shed light on etiopathogenesis of AIS.-Chen, H., Zhang, J., Wang, Y., Cheuk, K.-Y., Hung, A. L. H., Lam, T.-P., Qiu, Y., Feng, J. Q., Lee, W. Y. W., Cheng, J. C. Y. Abnormal lacuno-canalicular network and negative correlation between serum osteocalcin and Cobb angle indicate abnormal osteocyte function in adolescent idiopathic scoliosis.

LncRNA-SULT1C2A regulates Foxo4 in congenital scoliosis by targeting rno-miR-466c-5p through PI3K-ATK signalling

Congenital scoliosis (CS) is the result of anomalous vertebrae development, but the pathogenesis of CS remains unclear. Long non‐coding RNAs (lncRNAs) have been implicated in embryo development, but their role in CS remains unknown. In this study, we investigated the role and mechanisms of a specific lncRNA, SULT1C2A, in somitogenesis in a rat model of vitamin A deficiency (VAD)‐induced CS. Bioinformatics analysis and quantitative real‐time PCR (qRT‐PCR) indicated that SULT1C2A expression was down‐regulated in VAD group, accompanied by increased expression of rno‐miR‐466c‐5p but decreased expression of Foxo4 and somitogenesis‐related genes such as Pax1, Nkx3‐2 and Sox9 on gestational day (GD) 9. Luciferase reporter and small interfering RNA (siRNA) assays showed that SULT1C2A functioned as a competing endogenous RNA to inhibit rno‐miR‐466c‐5p expression by direct binding, and rno‐miR‐466c‐5p inhibited Foxo4 expression by binding to its 3′ untranslated region (UTR). The spatiotemporal expression of SULT1C2A, rno‐miR‐466c‐5p and Foxo4 axis was dynamically altered on GDs 3, 8, 11, 15 and 21 as detected by qRT‐PCR and northern blot analyses, with parallel changes in Protein kinase B (AKT) phosphorylation and PI3K expression. Taken together, our findings indicate that SULT1C2A enhanced Foxo4 expression by negatively modulating rno‐miR‐466c‐5p expression via the PI3K‐ATK signalling pathway in the rat model of VAD‐CS. Thus, SULT1C2A may be a potential target for treating CS.

LncRNA BRE-AS1 interacts with miR-145-5p to regulate cancer cell proliferation and apoptosis in prostate carcinoma and has early diagnostic values

Long non-coding RNA (LncRNA) BRE-AS1 has recently proven to be a tumor suppressor in lung cancer. The present study aimed to investigate the involvement of lncRNA BRE-AS1 in prostate carcinoma (PC). In the present study we found that plasma BRE-AS1 and miR-145-5p were both down-regulated in PC patients than in healthy controls. Down-regulation of BRE-AS1 and miR-145-5p effectively distinguished early-stage PC patients from healthy controls. A significant and positive correlation between BRE-AS1 and miR-145-5p was only found in PC patients. BRE-AS1 overexpression mediated miR-145-5p up-regulation in PC cells, while miR-145-5p overexpression did not significantly affect BRE-AS1. Overexpression of BRE-AS1 and miR-145-5p led to inhibited proliferation and promoted apoptosis of PC cells. miR-145-5p inhibitor attenuated the effects of BRE-AS1 overexpression on cancer cell behaviors. Therefore, lncRNA BRE-AS1 may regulate cancer cell proliferation and apoptosis in PC by interacting with miR-145-5p.