Diagnostic Performance of a Panel of miRNAs (OsteomiR) for Osteoporosis in a Cohort of Postmenopausal Women

An update on bone in diabetes

PURPOSE OF REVIEW

As the prevalence of diabetes mellitus (DM) increases due to urbanization, aging populations, and lifestyle changes, it is crucial to understand the mechanisms, diagnosis, and treatment of diabetes-related bone disorders. This review highlights recent advancements in the field and explores their implications for clinical practice and research.

RECENT FINDINGS

Recent studies have elucidated the complex interplay between diabetes and bone health, emphasizing the roles of advanced glycation end-products (AGEs), inflammation, oxidative stress, senescence, and molecular signaling pathways such as Wnt, mammalian target of rapamycin (mTOR), and exosome-mediated mechanisms. Key findings highlight the significance of bone marrow adipose tissue (BMAT) in bone metabolism and the impact of sarcopenia on fracture risk. Novel diagnostic tools, including miRNA biomarkers and emerging therapeutic strategies like exosome-based therapies and glycogen synthase kinase 3 beta (GSK3β) inhibitors, offer promising opportunities for improving bone health in diabetic patients.

SUMMARY

The findings underscore the need for integrated strategies for managing diabetes-related bone complications. Clinicians should prioritize early screening, lifestyle interventions, and personalized pharmacological treatments to mitigate fracture risk and improve bone health in diabetic patients. Future research should focus on optimizing diagnostic tools and developing targeted therapies to address the unique challenges of bone disorders related to diabetes.

Circulating miR-126-3p is a mechanistic biomarker for knee osteoarthritis

Osteoarthritis is a major contributor to pain and disability worldwide, yet there are currently no validated soluble biomarkers or disease-modifying treatments. Given that microRNAs are promising mechanistic biomarkers that can be therapeutically targeted, in this study, we aimed to identify and prioritize reproducible circulating microRNAs associated with radiographic knee osteoarthritis. Across four independent cohorts, we find circulating miR-126-3p is elevated in knee osteoarthritis versus controls. Across six primary human knee osteoarthritis tissues, miR-126-3p is highest in subchondral bone, fat pad and synovium, and lowest in cartilage. Following both intravenous and intra-articular miR-126-3p mimic treatment in a surgical mouse model of knee osteoarthritis, we show reduced disease severity in males. In human knee osteoarthritis biospecimens, miR-126-3p mimic treatment reduces genes and markers associated with angiogenesis, as well as genes linked to osteogenesis, adipogenesis, and synovitis-processes secondary to angiogenesis. Our findings indicate that miR-126-3p is elevated in knee osteoarthritis and mitigates disease severity, supporting its potential as a biomarker and therapeutic target.

The Role of microRNA in the Regulation of Differentiation and the Functionality of Osteoblasts, Osteoclasts, and Their Precursors in Osteoporosis

Osteoporosis is a complex disease that is affected by a variety of factors, including genetic and epigenetic influences. While DNA markers for osteoporosis have been identified, they do not fully explain the hereditary basis of the disease. Epigenetic factors, such as small microRNAs (miRNAs), may provide a missing link in understanding the molecular mechanisms underlying osteoporosis. miRNAs are a class of non-coding RNAs that play a role in the epigenetic regulation of gene expression. They are known to be involved in various biological processes, including bone formation and remodelling. Differential expression of miRNAs has been linked to the pathological decrease in bone mineral density associated with osteoporosis. It has been shown that an abnormal miRNA expression pattern leads to a decrease in osteoblast activity and an increase in osteoclast activity. Further research into the role of miRNAs in osteoporosis may help to better understand this disease and identify potential therapeutic targets for treatment. Based on these assumptions, the study of miRNA expression patterns in osteoblasts, osteoclasts, and their precursors under normal and osteoporotic conditions is a rapidly growing field of scientific research. Although the results of this research are still incomplete and sometimes contradictory, they require additional scientific analysis to better understand the complex mechanisms involved. The purpose of this paper is to review the current research on miRNAs specifically expressed in osteoblasts and osteoclasts under both normal and pathological conditions. We will also discuss the potential applications of these miRNAs as biomarkers for osteoporosis diagnosis and as targets for osteoporosis treatment.

Retinopathy of Prematurity and MicroRNAs

Retinopathy of Prematurity (ROP), a leading cause of blindness in preterm infants, arises from dysregulated angiogenesis and inflammation. Without timely intervention, ROP can progress to severe outcomes, including dense fibrovascular plaques and retinal detachment. MicroRNAs (miRNAs) regulate key pathways such as hypoxia response, VEGF signaling, and vascular remodeling. Studies have identified miRNAs (e.g., miR-210, miR-146a, and miR-21) as potential biomarkers and therapeutic targets. Preclinical evidence supports miRNA-based therapies (e.g., miR-18a-5p and miR-181a), targeting HIF-1α and VEGFA to mitigate neovascularization, with nanoparticle delivery systems enhancing stability and specificity. These strategies, combined with anti-VEGF agents, show significant potential for improving ROP management. While promising, miRNA therapies require validation in clinical trials to ensure safety and efficacy. This review discusses the role of miRNAs in ROP, highlighting their relevance as diagnostic and therapeutic tools.

Role of microRNA in Diabetic Osteoporosis

Diabetic osteoporosis (DOP), a complication associated with diabetes mellitus (DM), is a metabolic bone disorder characterized by a reduction in bone mass per unit volume, impaired bone tissue microarchitecture, heightened bone fragility, and increased susceptibility to fractures. Individuals with diabetes exhibit a significantly greater incidence of osteoporosis and related fractures than those without diabetes. These fractures present a significant challenge in terms of the healing process and can result in severe consequences, including fatalities. MicroRNAs (miRNAs), a class of noncoding RNAs, play a pivotal role in numerous human diseases and are implicated in the pathogenesis of DOP. This review initially elucidates the essential role of miRNAs in the pathogenesis of DOP. Next, we emphasize the potential significance of miRNAs as valuable biomarkers for diagnosing DOP and predicting DOP-related fractures. Furthermore, we explore the involvement of miRNAs in managing DOP through various pathways, including conventional pharmaceutical interventions and exercise therapy. Importantly, miRNAs exhibit potential as targeted therapeutic agents for effectively treating DOP. Finally, we highlight the use of novel materials and exosomes for miRNA delivery, which has significant advantages in the treatment of DOP and overcomes the limitations associated with miRNA delivery.

From Genomics to Metabolomics: Molecular Insights into Osteoporosis for Enhanced Diagnostic and Therapeutic Approaches

Osteoporosis (OP) is a prevalent skeletal disorder characterized by decreased bone mineral density (BMD) and increased fracture risk. The advancements in omics technologies-genomics, transcriptomics, proteomics, and metabolomics-have provided significant insights into the molecular mechanisms driving OP. These technologies offer critical perspectives on genetic predispositions, gene expression regulation, protein signatures, and metabolic alterations, enabling the identification of novel biomarkers for diagnosis and therapeutic targets. This review underscores the potential of these multi-omics approaches to bridge the gap between basic research and clinical applications, paving the way for precision medicine in OP management. By integrating these technologies, researchers can contribute to improved diagnostics, preventative strategies, and treatments for patients suffering from OP and related conditions.

RNA-Binding Proteins as Novel Effectors in Osteoblasts and Osteoclasts: A Systems Biology Approach to Dissect the Transcriptional Landscape

Bone health is ensured by the coordinated action of two types of cells-the osteoblasts that build up bone structure and the osteoclasts that resorb the bone. The loss of balance in their action results in pathological conditions such as osteoporosis. Central to this study is a class of RNA-binding proteins (RBPs) that regulates the biogenesis of miRNAs. In turn, miRNAs represent a critical level of regulation of gene expression and thus control multiple cellular and biological processes. The impact of miRNAs on the pathobiology of various multifactorial diseases, including osteoporosis, has been demonstrated. However, the role of RBPs in bone remodeling is yet to be elucidated. The aim of this study is to dissect the transcriptional landscape of genes encoding the compendium of 180 RBPs in bone cells. We developed and applied a multi-modular integrative analysis algorithm. The core methodology is gene expression analysis using the GENEVESTIGATOR platform, which is a database and analysis tool for manually curated and publicly available transcriptomic data sets, and gene network reconstruction using the Ingenuity Pathway Analysis platform. In this work, comparative insights into gene expression patterns of RBPs in osteoblasts and osteoclasts were obtained, resulting in the identification of 24 differentially expressed genes. Furthermore, the regulation patterns upon different treatment conditions revealed 20 genes as being significantly up- or down-regulated. Next, novel gene-gene associations were dissected and gene networks were reconstructed. Additively, a set of osteoblast- and osteoclast-specific gene signatures were identified. The consolidation of data and information gained from each individual analytical module allowed nominating novel promising candidate genes encoding RBPs in osteoblasts and osteoclasts and will significantly enhance the understanding of potential regulatory mechanisms directing intracellular processes in the course of (patho)physiological bone turnover.

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.

The MicroRNAs in the Pathophysiology of Osteoporosis

Globally, osteoporosis is the most common systemic skeletal disease. There are many factors that influence osteoporosis' development and progression. During the pathogenesis of this disease, bone turnover is imbalanced between resorption and the formation of bone tissue. A growing interest has been devoted to the role that microRNA (miRNA) plays in osteoporosis regulation. A microRNA (miRNA) is a group of small single-stranded RNA molecules involved in regulating gene expression in eukaryotic organisms. As microRNAs (miRNAs) are key regulators of gene expression and can modulate processes related to bone metabolism, they have become increasingly important for studying osteoporosis pathogenesis. The available research suggests that miRNAs play an important role in regulating processes associated with bone metabolism, especially by influencing bone resorption and synthesis. Furthermore, microRNAs can also serve as potential therapeutic targets for osteoporosis, besides being a rapid and specific biomarker.

Week-by-week changes in serum levels of bone-related circulating microRNAs and bone turnover markers

MicroRNAs are involved in post-transcriptional regulation of gene expression. Due to their regulatory role, microRNAs are differently expressed during specific conditions in healthy and diseased individuals, so microRNAs circulating in the blood could be used as diagnostic and prognostic biomarkers for various diseases and conditions. We want to investigate the variability of circulating microRNAs and bone turnover markers in weekly time intervals in older women. In a single-site longitudinal study, a panel of 19 bone-related miRNAs was measured using the osteomiR RT-qPCR assay in serum samples of 35 postmenopausal women divided into 3 groups: healthy controls (n = 12), low BMD (n = 14), and vertebral fractures (n = 9). Blood samples for measurement of CTX, PINP, OC, and bone ALP were collected once per week for 8 weeks at 9:00 AM after overnight fasting. Serum samples from all participants were analyzed for 19 microRNA bone biomarkers and 4 bone turnover markers over 8 weeks. We analyzed the data using a mixed model analysis of variance and found no significant changes between week-by-week time points in any of the groups. To estimate intraindividual variability between weekly time points, we have calculated the median coefficient of variation (CV). This was between 28.4% and 80.2% for microRNA, with an assay CV of 21.3%. It was between 8.5% and 15.6% for bone turnover markers, with an assay CV of 3.5% to 6.5%. The intraindividual variability was similar between groups. Circulating microRNAs measured in serum had a higher weekly intraindividual variability than bone turnover markers due in part to a higher assay CV.

Plasma microRNA signature associated with skeletal muscle wasting in post-menopausal osteoporotic women

BACKGROUND

Skeletal muscle mass wasting almost invariably accompanies bone loss in elderly, and the coexistence of these two conditions depends on the tight endocrine crosstalk existing between the two organs, other than the biomechanical coupling. Since the current diagnostics limitation in this field, and given the progressive population aging, more effective tools are needed. The aim of this study was to identify circulating microRNAs (miRNAs) as potential biomarkers for muscle mass wasting in post-menopausal osteoporotic women.

METHODS

One hundred seventy-nine miRNAs were assayed by quantitative real-time polymerase chain reaction in plasma samples from 28 otherwise healthy post-menopausal osteoporotic women (73.4 ± 6.6 years old). The cohort was divided in tertiles based on appendicular skeletal muscle mass index (ASMMI) to better highlight the differences on skeletal muscle mass (first tertile: n = 9, ASMMI = 4.88 ± 0.40 kg·m-2; second tertile: n = 10, ASMMI = 5.73 ± 0.23 kg·m-2; third tertile: n = 9, ASMMI = 6.40 ± 0.22 kg·m-2). Receiver operating characteristic (ROC) curves were calculated to estimate the diagnostic potential of miRNAs. miRNAs displaying a statistically significant fold change ≥ ±1.5 and area under the curve (AUC) > 0.800 (P < 0.05) between the first and third tertiles were considered. A linear regression model was applied to estimate the association between miRNA expression and ASMMI in the whole population, adjusting for body mass index, age, total fat (measured by total-body dual-energy X-ray absorptiometry [DXA]) and bone mineral density (measured by femur DXA). Circulating levels of adipo-myokines were evaluated by bead-based immunofluorescent assays and enzyme-linked immunosorbent assays.

RESULTS

Five miRNAs (hsa-miR-221-3p, hsa-miR-374b-5p, hsa-miR-146a-5p, hsa-miR-126-5p and hsa-miR-425-5p) resulted down-regulated and two miRNAs (hsa-miR-145-5p and hsa-miR-25-3p) were up-regulated in the first tertile (relative-low ASMMI) compared with the third tertile (relative-high ASMMI) (fold change ≥ ±1.5; P-value < 0.05). All the corresponding ROC curves had AUC > 0.8 (P < 0.05). Two signatures hsa-miR-126-5p, hsa-miR-146a-5p and hsa-miR-425-5p; and hsa-miR-126-5p, hsa-miR-146a-5p, hsa-miR-145-5p and hsa-miR-25-3p showed the highest AUC, 0.914 (sensitivity = 77.78%; specificity = 100.00%) and 0.901 (sensitivity = 88.89%; specificity = 100.00%), respectively.

CONCLUSIONS

In this study, we identified, for the first time, two miRNA signatures, hsa-miR-126-5p, hsa-miR-146a-5p and hsa-miR-425-5p; and hsa-miR-126-5p, hsa-miR-146a-5p, hsa-miR-145-5p and hsa-miR-25-3p, specifically associated with muscle mass wasting in post-menopausal osteoporotic women.

Circulating and extracellular vesicle-derived microRNAs as biomarkers in bone-related diseases

MicroRNAs (miRNA) are small non-coding RNA molecules that regulate posttranscriptional gene expression by repressing messengerRNA-targets. MiRNAs are abundant in many cell types and are secreted into extracellular fluids, protected from degradation by packaging in extracellular vesicles. These circulating miRNAs are easily accessible, disease-specific and sensitive to small changes, which makes them ideal biomarkers for diagnostic, prognostic, predictive or monitoring purposes. Specific miRNA signatures can be reflective of disease status and development or indicators of poor treatment response. This is especially important in malignant diseases, as the ease of accessibility of circulating miRNAs circumvents the need for invasive tissue biopsy. In osteogenesis, miRNAs can act either osteo-enhancing or osteo-repressing by targeting key transcription factors and signaling pathways. This review highlights the role of circulating and extracellular vesicle-derived miRNAs as biomarkers in bone-related diseases, with a specific focus on osteoporosis and osteosarcoma. To this end, a comprehensive literature search has been performed. The first part of the review discusses the history and biology of miRNAs, followed by a description of different types of biomarkers and an update of the current knowledge of miRNAs as biomarkers in bone related diseases. Finally, limitations of miRNAs biomarker research and future perspectives will be presented.

Regulatory mechanisms of microRNAs in endocrine disorders and their therapeutic potential

MicroRNAs (miRNAs) are small endogenous non-coding RNA molecules capable of regulating gene expression at the post-transcriptional level either by translational inhibition or mRNA degradation and have recently been importantly related to the diagnosis and prognosis of the most relevant endocrine disorders. The endocrine system comprises various highly vascularized ductless organs regulating metabolism, growth and development, and sexual function. Endocrine disorders constitute the fifth principal cause of death worldwide, and they are considered a significant public health problem due to their long-term effects and negative impact on the patient's quality of life. Over the last few years, miRNAs have been discovered to regulate various biological processes associated with endocrine disorders, which could be advantageous in developing new diagnostic and therapeutic tools. The present review aims to provide an overview of the most recent and significant information regarding the regulatory mechanism of miRNAs during the development of the most relevant endocrine disorders, including diabetes mellitus, thyroid diseases, osteoporosis, pituitary tumors, Cushing's syndrome, adrenal insufficiency and multiple endocrine neoplasia, and their potential implications as disease biomarkers.

Micro-RNA: A Future Approach to Personalized Diagnosis of Bone Diseases

Osteoporosis is a highly prevalent bone disease worldwide and the most studied bone-associated pathological condition. Although its diagnosis makes use of advanced and clinically relevant imaging and biochemical tools, the information suffers from several limitations and has little or no prognostic value. In this context, circulating micro-RNAs represent a potentially attractive alternative or a useful addition to the diagnostic arsenal and offer a greater prognostic potential than the conventional approaches. These short non-coding RNA molecules act as inhibitors of gene expression by targeting messenger RNAs with different degrees of complementarity, establishing a complex multilevel network, the basis for the fine modulation of gene expression that finally regulates every single activity of a cell. Micro-RNAs may passively and/or actively be released in the circulation by source cells, and being measurable in biological fluids, their concentrations may be associated to specific pathophysiological conditions. Mounting, despite debatable, evidence supports the use of micro-RNAs as markers of bone cell metabolic activity and bone diseases. Indeed, several micro-RNAs have been associated with bone mineral density, fractures and osteoporosis. However, concerns such as absence of comparability between studies and, the lack of standardization and harmonization of the methods, limit their application. In this review, we describe the pathophysiological bases of the association between micro-RNAs and the deregulation of bone cells activity and the processes that led to the identification of potential micro-RNA-based markers associated with metabolic bone diseases.

Bone-Metabolism-Related Serum microRNAs to Diagnose Osteoporosis in Middle-Aged and Elderly Women

Objective: Postmenopausal osteoporosis (PMOP), a chronic systemic metabolic disease prevalent in middle-aged and elderly women, heavily relies on bone mineral density (BMD) measurement as the diagnostic indicator. In this study, we investigated serum microRNAs (miRNAs) as a possible screening tool for PMOP. Methods: This investigation recruited 83 eligible participants from 795 community-dwelling postmenopausal women between June 2020 and August 2021. The miRNA expression profiles in the serum of PMOP patients were evaluated via miRNA microarray (six PMOP patients and four postmenopausal women without osteoporosis (n-PMOP) as controls). Subsequently, results were verified in independent sample sets (47 PMOP patients and 26 n-PMOP controls) using quantitative real-time PCR. In addition, the target genes and main functions of the differentially expressed miRNAs were explored by bioinformatics analysis. Results: Four highly expressed miRNAs in the serum of patients (hsa-miR-144-5p, hsa-miR-506-3p, hsa-miR-8068, and hsa-miR-6851-3p) showed acceptable disease-independent discrimination performance (area under the curve range: 0.747-0.902) in the training set and verification set, outperforming traditional bone turnover markers. Among four key miRNAs, hsa-miR-144-5p is the only one that can simultaneously predict changes in BMD in lumbar spine 1-4, total hip, and femoral neck (β = -0.265, p = 0.022; β = -0.301, p = 0.005; and β = -0.324, p = 0.003, respectively). Bioinformatics analysis suggested that the differentially expressed miRNAs were targeted mainly to YY1, VIM, and YWHAE genes, which are extensively involved in bone metabolism processes. Conclusions: Bone-metabolism-related serum miRNAs, such as hsa-miR-144-5p, hsa-miR-506-3p, hsa-miR-8068, and hsa-miR-6851-3p, can be used as novel biomarkers for PMOP diagnosis independent of radiological findings and traditional bone turnover markers. Further study of these miRNAs and their target genes may provide new insights into the epigenetic regulatory mechanisms of the onset and progression of the disease.

A Mini Review on Osteoporosis: From Biology to Pharmacological Management of Bone Loss

Osteoporosis refers to excessive bone loss as reflected by the deterioration of bone mass and microarchitecture, which compromises bone strength. It is a complex multifactorial endocrine disease. Its pathogenesis relies on the presence of several endogenous and exogenous risk factors, which skew the physiological bone remodelling to a more catabolic process that results in net bone loss. This review aims to provide an overview of osteoporosis from its biology, epidemiology and clinical aspects (detection and pharmacological management). The review will serve as an updated reference for readers to understand the basics of osteoporosis and take action to prevent and manage this disease.

Circulating miRNAs associated with bone mineral density in healthy adult baboons

MicroRNAs (miRNAs) regulate gene expression post-transcriptionally and circulate in the blood, making them attractive biomarkers of disease state for tissues like bone that are challenging to interrogate directly. Here, we report on five miRNAs-miR-197-3p, miR-320a, miR-320b, miR-331-5p, and miR-423-5p-associated with bone mineral density (BMD) in 147 healthy adult baboons. These baboons ranged in age from 15 to 25 years (45-75 human equivalent years) and 65% were female with a broad range of BMD values including a minority of osteopenic animals. miRNAs were generated via RNA sequencing from buffy coats collected at necropsy and areal BMD (aBMD) measured postmortem via dual-energy X-ray absorptiometry (DXA) of the lumbar vertebrae. Differential expression analysis controlled for the underlying pedigree structure of these animals to account for genetic variation which may drive miRNA abundance and aBMD values. While many of these miRNAs have been associated with the risk of osteoporosis in humans, this finding is of interest because the cohort represents a model of normal aging and bone metabolism rather than a disease cohort. The replication of miRNA associations with osteoporosis or other bone metabolic disorders in animals with healthy aBMD suggests an overlap in normal variation and disease states. We suggest that these miRNAs are involved in the regulation of cellular proliferation, apoptosis, and protein composition in the extracellular matrix throughout life; and age-related dysregulation of these systems may lead to disease. These miRNAs may be early indicators of progression to disease in advance of clinically detectible osteoporosis.

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.

Menopausal Transition: Prospective Study of Estrogen Status, Circulating MicroRNAs, and Biomarkers of Bone Metabolism

OBJECTIVE

Osteoporosis is associated with an impaired balance between bone resorption and formation, which in turn leads to bone loss and fractures. Many recent studies have underlined the regulatory role of microRNAs (miRNAs) in bone remodeling processes and their potential as biomarkers of osteoporosis. The purpose of this study was to prospectively examine the association of circulating miRNAs and bone biomarkers with estrogen status in women before and after oophorectomy, as well as in oophorectomized women on estrogen therapy.

METHODS

In this prospective study, we included 11 women before oophorectomy and hysterectomy and at 201 ± 24 days after the surgery. Another 11 women were evaluated 508 ± 127 days after oophorectomy and hysterectomy and after an additional 203 ± 71 days of estradiol treatment. Serum miRNAs were profiled by sequencing. Estrogen status and biomarkers of bone metabolism were quantified. Bone mineral density was assessed in the lumbar spine.

RESULTS

Our analysis revealed 17 miRNAs associated with estrogen levels. Of those miRNAs that were upregulated with estrogen deficiency and downregulated after estrogen therapy, miR-422a correlated with serum beta-carboxy-terminal type I collagen crosslinks (β-CTX) and procollagen 1 N-terminal propeptide (P1NP); and miR-1278 correlated with serum β-CTX, P1NP, osteocalcin, sclerostin, and Dickkopf-1(Dkk1). In contrast, we found an inverse association of miR-24-1-5p with estrogen status and a negative correlation with serum β-CTX, P1NP, osteoprotegerin, and sclerostin levels.

CONCLUSION

The reported miRNAs associated with estrogen status and bone metabolism could be potential biomarkers of bone pathophysiology and would facilitate studies on the prevention of postmenopausal osteoporosis. Our findings require validation in an extended cohort.

A regulatory role of circRNA-miRNA-mRNA network in osteoblast differentiation

Osteoblast differentiation is an important process in skeletal development and bone remodelling. Serious bone diseases occur from any delay, defect, or imbalance in osteoblastic differentiation. Non-coding RNAs (ncRNAs) play a regulatory role in controlling the expression of proteins under physiological and pathological conditions via inhibiting mRNA translation or degrading mRNA. Circular RNAs (circRNAs) and microRNAs (miRNAs) are the long and small ncRNAs, respectively, which have been reported to regulate the expression of osteoblast marker genes directly or indirectly. Also, recent studies identified the regulatory mechanisms involving the crosstalk among circRNAs, miRNAs, and mRNAs during osteoblast differentiation. Understanding these regulatory mechanisms behind osteoblastic differentiation would help to diagnose or treat bone and bone-related disorders. Hence, the current review comprehensively discussed the regulatory relationship of circRNAs, miRNAs and mRNAs, and their functional role as circRNA-miRNA-mRNA axis in osteoblast differentiation.

Circulating miR-122-5p and miR-375 as Potential Biomarkers for Bone Mass Recovery after Parathyroidectomy in Patients with Primary Hyperparathyroidism: A Proof-of-Concept Study

Primary hyperparathyroidism (PHPT) is the leading cause of secondary osteoporosis. Although bone mineral density (BMD) tends to recover after parathyroidectomy in PHPT patients, the degree of recovery varies. Circulating microRNAs (miRNAs) profiles are known to be correlated with osteoporosis and fracture. We aimed to investigate whether osteoporotic fracture-related miRNAs are associated with postoperative BMD recovery in PHPT. Here, 16 previously identified osteoporotic fracture-related miRNAs were selected. We analyzed the association between the preoperative level of each miRNA and total hip (TH) BMD change. All 12 patients (among the 18 patients enrolled) were cured of PHPT after parathyroidectomy as parathyroid hormone (PTH) and calcium levels were restored to the normal range. Preoperative miR-19b-3p, miR-122-5p, and miR-375 showed a negative association with the percent changes in TH BMD from baseline. The association remained robust for miR-122-5p and miR-375 even after adjusting for sex, age, PTH, and procollagen type 1 N-terminal propeptide levels in a multivariable model. In conclusion, preoperative circulating miR-122-5p and miR-375 levels were negatively associated with TH BMD changes after parathyroidectomy in PHPT patients. miRNAs have the potential to serve as predictive biomarkers of treatment response in PHPT patients, which merits further investigation.