Circulating serum microRNAs including senescent miR-31-5p are associated with incident fragility fractures in older postmenopausal women with type 2 diabetes mellitus

Diagnosis and therapeutic approach to bone health in patients with hypopituitarism

The results of many studies in recent years indicate a significant impact of pituitary function on bone health. The proper function of the pituitary gland has a significant impact on the growth of the skeleton and the appearance of sexual dimorphism. It is also responsible for achieving peak bone mass, which protects against the development of osteoporosis and fractures later in life. It is also liable for the proper remodeling of the skeleton, which is a physiological mechanism managing the proper mechanical resistance of bones and the possibility of its regeneration after injuries. Pituitary diseases causing hypofunction and deficiency of tropic hormones, and thus deficiency of key hormones of effector organs, have a negative impact on the skeleton, resulting in reduced bone mass and susceptibility to pathological fractures. The early appearance of pituitary dysfunction, i.e. in the pre-pubertal period, is responsible for failure to achieve peak bone mass, and thus the risk of developing osteoporosis in later years. This argues for the need for a thorough assessment of patients with hypopituitarism, not only in terms of metabolic disorders, but also in terms of bone disorders. Early and properly performed treatment may prevent patients from developing the bone complications that are so common in this pathology. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary disease.

Aged-vascular niche hinders osteogenesis of mesenchymal stem cells through paracrine repression of Wnt-axis

Age-induced decline in osteogenic potential of bone marrow mesenchymal stem cells (BMSCs) potentiates osteoporosis and increases the risk for bone fractures. Despite epidemiology studies reporting concurrent development of vascular and bone diseases in the elderly, the underlying mechanisms for the vascular-bone cross-talk in aging are largely unknown. In this study, we show that accelerated endothelial aging deteriorates bone tissue through paracrine repression of Wnt-driven-axis in BMSCs. Here, we utilize physiologically aged mice in conjunction with our transgenic endothelial progeria mouse model (Hutchinson-Gilford progeria syndrome; HGPS) that displays hallmarks of an aged bone marrow vascular niche. We find bone defects associated with diminished BMSC osteogenic differentiation that implicate the existence of angiocrine factors with long-term inhibitory effects. microRNA-transcriptomics of HGPS patient plasma combined with aged-vascular niche analyses in progeria mice reveal abundant secretion of Wnt-repressive microRNA-31-5p. Moreover, we show that inhibition of microRNA-31-5p as well as selective Wnt-activator CHIR99021 boosts the osteogenic potential of BMSCs through de-repression and activation of the Wnt-signaling, respectively. Our results demonstrate that the vascular niche significantly contributes to osteogenesis defects in aging and pave the ground for microRNA-based therapies of bone loss in elderly.

Increased circulating microRNA-21 level as a potential indicator for predicting a higher risk of incident fragility fractures

CONTEXT

As a common disease in the elderly, osteoporosis clearly increases the risk of fractures, leading to higher mortality, but the current markers to estimate the risk of fractures are limited. MicroRNA-21 (miR-21) may play an important role in osteoporosis, but the link of this biomarker with fractures was undetermined.

OBJECTIVES

We aimed to investigate the association between miR-21 levels and the presence of fragility fractures.

METHODS

A total of 200 patients were recruited and miR-21 was collected from baseline serum. The correlation between miR-21 and the fracture risk assessment tool (FRAX) score was analyzed. The incidence of fragility fractures was presented by Kaplan-Meier analysis, and Cox regression analysis was utilized to evaluate risk factors. The diagnostic value of miR-21 was conducted by the area under curve (AUC).

RESULTS

The FRAX score was significantly associated with miR-21 level (p<0.001). According to the 50th percentile of miR-21 content in the overall distribution, the cumulative incidence of fragility fractures was significantly higher in patients with higher miR-21 levels than those with lower levels (75.4, 95 % CI: 69.0-81.8 vs. 59.2, 95 % CI: 42.1-76.3, p<0.001). The results of the Cox regression analysis showed that the miR-21 level was an independent risk factor linked to the incidence of fracture (p=0.005). The optimal cut-off value of the miR-21 was 6.08, and the AUC for predicting fracture was 0.718 (95 % CI, 0.645-0.790).

CONCLUSIONS

This study showed that miR-21 has optimal diagnostic performance in the discrimination of fragility fracture, and the circulating miR-21 level in predicting the risk of fragility fracture may have a certain value.

LncRNA SNHG16 Knockdown Promotes Diabetic Foot Ulcer Wound Healing via Sponging MiR-31-5p

Diabetic foot ulcers are caused by nerve abnormalities and vascular lesions in the distal lower limbs of diabetic patients. However, the causes of diabetic foot ulcers are diverse and the treatment process is complex. Therefore, understanding the pathogenesis of diabetic foot ulcers through lncRNA and formulating effective means are the key to the cure of patients. Tissues were collected from 76 diabetic foot ulcer patients and 50 non-diabetic patients undergoing traumatic amputation. Human dermal fibroblasts (HDFs) were induced by high glucose to obtain diabetic foot ulcer cell model. The lncRNA SNHG16 (SNHG16) and miR-31-5p expression in tissues and cells was detected by real-time quantitative reverse transcription PCR (RT-qPCR). Cell Counting Kit-8 (CCK-8) and Transwell assays were used to evaluate the biological behavior of the cells, and the association between SNHG16 and miR-31-5p was explored by luciferase reporting assay. SNHG16 was distinctly expressed in diabetic foot ulcer tissue samples, while miR-31-5p was decreased. In vitro cell function assays confirmed that the proliferation level was inhibited in the constructed diabetic foot ulcer cell model (HG group), as was the migration and invasion ability. After transfection with silencing SNHG16, the biological behavior of the cells was promoted. Mechanistically, SNHG16 sponge miR-31-5p regulated disease progression. Recovery experiments revealed that miR-31-5p inhibitor counteracted the effect of silencing SNHG16 on cell viability. SNHG16 knockdown may regulate the biological function of cells by targeting miR-31-5p to promote wound healing and ameliorate the condition of diabetic foot ulcer patients.

Long-term and sequential treatment for osteoporosis

Osteoporosis is a skeletal disorder that causes impairment of bone structure and strength, leading to a progressively increased risk of fragility fractures. The global prevalence of osteoporosis is increasing in the ageing population. Owing to the chronic character of osteoporosis, years or even decades of preventive measures or therapy are required. The long-term use of bone-specific pharmacological treatment options, including antiresorptive and/or osteoanabolic approaches, has raised concerns around adverse effects or potential rebound phenomena after treatment discontinuation. Imaging options, risk scores and the assessment of bone turnover during initiation and monitoring of such therapies could help to inform individualized treatment strategies. Combination therapies are currently used less often than 'sequential' treatments. However, all patients with osteoporosis, including those with secondary and rare causes of osteoporosis, as well as specific patient populations (for example, young adults, men and pregnant women) require new approaches for long-term therapy and disease monitoring. New pathophysiological aspects of bone metabolism might therefore help to inform and revolutionize the diagnosis and treatment of osteoporosis.

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.

New tools for bone health assessment in secreting pituitary adenomas

Pituitary hormones regulate skeletal physiology, and excess levels affect bone remodeling and alter bone microstructure. Vertebral fractures (VFs) are an early phenomenon of impaired bone health in secreting pituitary adenomas. However, they are not accurately predicted by areal bone mineral density (BMD). Emerging data demonstrate that a morphometric approach is essential for evaluating bone health in this clinical setting and is considered to be the gold standard method in acromegaly. Several novel tools have been proposed as alternative or additional methods for the prediction of fractures, particularly in pituitary-driven osteopathies. This review highlights the novel potential biomarkers and diagnostic methods for bone fragility, including their pathophysiological, clinical, radiological, and therapeutic implications in acromegaly, prolactinomas, and Cushing's disease.

Type 2 diabetes and bone fragility in children and adults

Type 2 diabetes (T2D) is a global epidemic disease. The prevalence of T2D in adolescents and young adults is increasing alarmingly. The mechanisms leading to T2D in young people are similar to those in older patients. However, the severity of onset, reduced insulin sensitivity and defective insulin secretion can be different in subjects who develop the disease at a younger age. T2D is associated with different complications, including bone fragility with consequent susceptibility to fractures. The purpose of this systematic review was to describe T2D bone fragility together with all the possible involved pathways. Numerous studies have reported that patients with T2D show preserved, or even increased, bone mineral density compared with controls. This apparent paradox can be explained by the altered bone quality with increased cortical bone porosity and compr-omised mechanical properties. Furthermore, reduced bone turnover has been described in T2D with reduced markers of bone formation and resorption. These findings prompted different researchers to highlight the mechanisms leading to bone fragility, and numerous critical altered pathways have been identified and studied. In detail, we focused our attention on the role of microvascular disease, advanced glycation end products, the senescence pathway, the Wnt/β-catenin pathway, the osteoprotegerin/receptor-activator of nuclear factor kappa B ligand, osteonectin and fibroblast growth factor 23. The understanding of type 2 myeloid bone fragility is an important issue as it could suggest possible interventions for the prevention of poor bone quality in T2D and/or how to target these pathways when bone disease is clearly evident.

Effect of Anti-Osteoporotic Treatments on Circulating and Bone MicroRNA Patterns in Osteopenic ZDF Rats

Bone fragility is an adverse outcome of type 2 diabetes mellitus (T2DM). The underlying molecular mechanisms have, however, remained largely unknown. MicroRNAs (miRNAs) are short non-coding RNAs that control gene expression in health and disease states. The aim of this study was to investigate the genome-wide regulation of miRNAs in T2DM bone disease by analyzing serum and bone tissue samples from a well-established rat model of T2DM, the Zucker Diabetic Fatty (ZDF) model. We performed small RNA-sequencing analysis to detect dysregulated miRNAs in the serum and ulna bone of the ZDF model under placebo and also under anti-sclerostin, PTH, and insulin treatments. The dysregulated circulating miRNAs were investigated for their cell-type enrichment to identify putative donor cells and were used to construct gene target networks. Our results show that unique sets of miRNAs are dysregulated in the serum (n = 12, FDR < 0.2) and bone tissue (n = 34, FDR < 0.2) of ZDF rats. Insulin treatment was found to induce a strong dysregulation of circulating miRNAs which are mainly involved in metabolism, thereby restoring seven circulating miRNAs in the ZDF model to normal levels. The effects of anti-sclerostin treatment on serum miRNA levels were weaker, but affected miRNAs were shown to be enriched in bone tissue. PTH treatment did not produce any effect on circulating or bone miRNAs in the ZDF rats. Altogether, this study provides the first comprehensive insights into the dysregulation of bone and serum miRNAs in the context of T2DM and the effect of insulin, PTH, and anti-sclerostin treatments on circulating miRNAs.

MicroRNA and Diabetic Bone Disease

PURPOSE OF REVIEW

The incidence of diabetes is increasing worldwide. Diabetes mellitus is characterized by hyperglycemia, which in the long-term damages the function of many organs including the eyes, the vasculature, the nervous system, and the kidneys, thereby imposing an important cause of morbidity for affected individuals. More recently, increased bone fragility was also noted in patients with diabetes. While patients with type 1 diabetes mellitus (T1DM) have low bone mass and a 6-fold risk for hip fractures, patients with type 2 diabetes mellitus (T2DM) have an increased bone mass, yet still display a 2-fold elevated risk for hip fractures. Although the underlying mechanisms are just beginning to be unraveled, it is clear that diagnostic tools are lacking to identify patients at risk for fracture, especially in the case of T2DM, in which classical tools to diagnose osteoporosis such as dual X-ray absorptiometry have limitations. Thus, new biomarkers are urgently needed to help identify patients with diabetes who are at risk to fracture.

RECENT FINDINGS

Previously, microRNAs have received great attention not only for being involved in the pathogenesis of various chronic diseases, including osteoporosis, but also for their value as biomarkers. Here, we summarize the current knowledge on microRNAs and their role in diabetic bone disease and highlight recent studies on miRNAs as biomarkers to predict bone fragility in T1DM and T2DM. Finally, we discuss future directions and challenges for their use as prognostic markers.

Evaluation of Quality and Bone Microstructure Alterations in Patients with Type 2 Diabetes: A Narrative Review

Bone fragility is a common complication in subjects with type 2 diabetes mellitus (T2DM). However, traditional techniques for the evaluation of bone fragility, such as dual-energy X-ray absorptiometry (DXA), do not perform well in this population. Moreover, the Fracture Risk Assessment Tool (FRAX) usually underestimates fracture risk in T2DM. Importantly, novel technologies for the assessment of one microarchitecture in patients with T2DM, such as the trabecular bone score (TBS), high-resolution peripheral quantitative computed tomography (HR-pQCT), and microindentation, are emerging. Furthermore, different serum and urine bone biomarkers may also be useful for the evaluation of bone quality in T2DM. Hence, in this article, we summarize the limitations of conventional tools for the evaluation of bone fragility and review the current evidence on novel approaches for the assessment of quality and bone microstructure alterations in patients with T2DM.

Prevalence and Risk Factors of Osteoporosis in Patients with Type 2 Diabetes Mellitus in Nanchang (China): A Retrospective Cohort Study

OBJECTIVE

To retrospectively review the clinical data of type 2 diabetes mellitus (T2DM) patients hospitalized in Nanchang, China, summarized the prevalence of osteoporosis (OP) in T2DM patients in this area, and analyzed related influencing factors.

METHODS

The clinical data of hospitalized patients with T2DM were collected retrospectively. According to the results of bone mineral density test, the subjects were divided into the normal bone mass group, the osteopenia group, and the OP group. Age, gender, educational background, body mass index (BMI), waist-to-hip ratio (WHR), duration of T2DM, glycosylated hemoglobin, serum lipids, and complications of T2DM in the three groups were analyzed and compared.

RESULTS

The prevalence of OP in patients with T2DM was 35.77%. There were statistically significant differences in age, gender, BMI, WHR, duration of T2DM, educational background, the level of high-density lipoprotein cholesterol (HDL-C), the prevalence of diabetic retinopathy (DR), and diabetic peripheral neuropathy among the three groups (P < 0.05). Logistic regression analysis showed that increasing age, prolonged duration of T2DM, low BMI, high levels of HDL-C, and complicated DR were risk factors for osteopenia and OP.

CONCLUSION

The prevalence of OP in T2DM was high. Risk factors for abnormal bone mass in T2DM might be females, advanced age, long duration of T2DM, low BMI, high levels of HDL-C, and diabetic microangiopathy.