Osteoprotegerin, RANKL, ADMA, and Fetuin-A serum levels in children with type I diabetes mellitus

RANKL/RANK is required for cytokine-induced beta cell death; osteoprotegerin, a RANKL inhibitor, reverses rodent type 1 diabetes

Treatment for type 1 diabetes (T1D) requires stimulation of functional β cell regeneration and survival under stress. Previously, we showed that inhibition of the RANKL/RANK [receptor activator of nuclear factor kappa Β (NF-κB) ligand] pathway, by osteoprotegerin and the anti-osteoporotic drug denosumab, induces rodent and human β cell proliferation. We demonstrate that the RANK pathway mediates cytokine-induced rodent and human β cell death through RANK-TRAF6 interaction and induction of NF-κB activation. Osteoprotegerin and denosumab protected β cells against this cytotoxicity. In human immune cells, osteoprotegerin and denosumab reduce proinflammatory cytokines in activated T-cells by inhibiting RANKL-induced activation of monocytes. In vivo, osteoprotegerin reversed recent-onset T1D in nonobese diabetic/Ltj mice, reduced insulitis, improved glucose homeostasis, and increased plasma insulin, β cell proliferation, and mass in these mice. Serum from T1D subjects induced human β cell death and dysfunction, but not α cell death. Osteoprotegerin and denosumab reduced T1D serum-induced β cell cytotoxicity and dysfunction. Inhibiting RANKL/RANK could have therapeutic potential.

Mechanisms of altered bone remodeling in children with type 1 diabetes

Bone loss associated with type 1 diabetes mellitus (T1DM) begins at the onset of the disease, already in childhood, determining a lower bone mass peak and hence a greater risk of osteoporosis and fractures later in life. The mechanisms underlying diabetic bone fragility are not yet completely understood. Hyperglycemia and insulin deficiency can affect the bone cells functions, as well as the bone marrow fat, thus impairing the bone strength, geometry, and microarchitecture. Several factors, like insulin and growth hormone/insulin-like growth factor 1, can control bone marrow mesenchymal stem cell commitment, and the receptor activator of nuclear factor-κB ligand/osteoprotegerin and Wnt-b catenin pathways can impair bone turnover. Some myokines may have a key role in regulating metabolic control and improving bone mass in T1DM subjects. The aim of this review is to provide an overview of the current knowledge of the mechanisms underlying altered bone remodeling in children affected by T1DM.

Skeletal Response to Insulin in the Naturally Occurring Type 1 Diabetes Mellitus Mouse Model

Patients with type 1 diabetes mellitus (T1DM) exhibit reduced BMD and significant increases in fracture risk. Changes in BMD are attributed to blunted osteoblast activity and inhibited bone remodeling, but these cannot fully explain the impaired bone integrity in T1DM. The goal of this study was to determine the cellular mechanisms that contribute to impaired bone morphology and composition in T1DM. Nonobese diabetic (NOD) mice were used, along with μCT, histomorphometry, histology, Raman spectroscopy, and RNAseq analyses of several skeletal sites in response to naturally occurring hyperglycemia and insulin treatment. The bone volume in the axial skeleton was found to be severely reduced in diabetic NOD mice and was not completely resolved with insulin treatment. Decreased bone volume in diabetic mice was associated with increased sclerostin expression in osteocytes and attenuation of bone formation indices without changes in bone resorption. In the face of blunted bone remodeling, decreases in the mineral:matrix ratio were found in cortical bones of diabetic mice by Raman microspectroscopy, suggesting that T1DM did not affect the bone mineralization process per se, but rather resulted in microenvironmental alterations that favored mineral loss. Bone transcriptome analysis indicated metabolic shifts in response to T1DM. Dysregulation of genes involved in fatty acid oxidation, transport, and synthesis was found in diabetic NOD mice. Specifically, pyruvate dehydrogenase kinase isoenzyme 4 and glucose transporter 1 levels were increased, whereas phosphorylated-AKT levels were significantly reduced in diabetic NOD mice. In conclusion, in addition to the blunted bone formation, osteoblasts and osteocytes undergo metabolic shifts in response to T1DM that may alter the microenvironment and contribute to mineral loss from the bone matrix. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Plasma circulating miR-23~27~24 clusters correlate with the immunometabolic derangement and predict C-peptide loss in children with type 1 diabetes

AIMS/HYPOTHESIS

We aimed to analyse the association between plasma circulating microRNAs (miRNAs) and the immunometabolic profile in children with type 1 diabetes and to identify a composite signature of miRNAs/immunometabolic factors able to predict type 1 diabetes progression.

METHODS

Plasma samples were obtained from children at diagnosis of type 1 diabetes (n = 88) and at 12 (n = 32) and 24 (n = 30) months after disease onset and from healthy control children with similar sex and age distribution (n = 47). We quantified 60 robustly expressed plasma circulating miRNAs by quantitative RT-PCR and nine plasma immunometabolic factors with a recognised role at the interface of metabolic and immune alterations in type 1 diabetes. Based on fasting C-peptide loss over time, children with type 1 diabetes were stratified into the following groups: those who had lost >90% of C-peptide compared with diagnosis level; those who had lost <10% of C-peptide; those showing an intermediate C-peptide loss. To evaluate the modulation of plasma circulating miRNAs during the course of type 1 diabetes, logistic regression models were implemented and the correlation between miRNAs and immunometabolic factors was also assessed. Results were then validated in an independent cohort of children with recent-onset type 1 diabetes (n = 18). The prognostic value of the identified plasma signature was tested by a neural network-based model.

RESULTS

Plasma circulating miR-23~27~24 clusters (miR-23a-3p, miR-23b-3p, miR-24-3p, miR-27a-3p and miR-27b-3p) were upmodulated upon type 1 diabetes progression, showed positive correlation with osteoprotegerin (OPG) and were negatively correlated with soluble CD40 ligand, resistin, myeloperoxidase and soluble TNF receptor in children with type 1 diabetes but not in healthy children. The combination of plasma circulating miR-23a-3p, miR-23b-3p, miR-24-3p, miR-27b-3p and OPG, quantified at disease onset, showed a significant capability to predict the decline in insulin secretion 12 months after disease diagnosis in two independent cohorts of children with type 1 diabetes.

CONCLUSIONS/INTERPRETATIONS

We have pinpointed a novel miR-23a-3p/miR-23b-3p/miR-24-3p/miR-27b-3p/OPG plasma signature that may be developed into a novel blood-based method to better stratify patients with type 1 diabetes and predict C-peptide loss.

ADMA elevation does not exacerbate development of diabetic nephropathy in mice with streptozotocin-induced diabetes mellitus

BACKGROUND AND AIMS

Cardiovascular disease is nowadays the major cause of mortality and morbidity worldwide. The risk of developing cardiovascular disease is significantly increased in patients with diabetic nephropathy. It has been suggested that asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO synthases (NOS), may play an important role in the pathogenesis of diabetic nephropathy. ADMA is mainly metabolized by dimethylarginine dimethylaminohydrolase 1 (DDAH1). The goal of this study was to test the hypothesis that elevation of systemic ADMA levels by knocking out DDAH1 would exacerbate functional and structural glomerular abnormalities in a murine model of diabetic nephropathy.

METHODS

Streptozotocin (STZ) was used to induce diabetes in adult DDAH1 knock-out and wild type mice. Healthy mice served as controls. Mice were sacrificed after 20 weeks of diabetes. Plasma ADMA levels were assessed by isotope-dilution tandem mass spectrometry and albumin by ELISA. Kidneys were used for FACS analysis and were also stained for markers of inflammation, cell proliferation, glomerular cells and cell matrix.

RESULTS

STZ led to development of diabetes mellitus in all injected animals. Deficiency of DDAH1 led to a significant increase in plasma ADMA levels in healthy and diabetic mice. The diabetic state itself did not influence systemic ADMA levels. Diabetic mice of both genotypes developed albuminuria and had increased glomerulosclerosis index. There were no changes in desmin expression, glomerular cell proliferation rate, matrix expansion and expression of Mac-2 antigen in the diabetic mice of both genotypes as compared to the healthy ones.

CONCLUSIONS

In summary, STZ-induced diabetes led to the development of early features of diabetic nephropathy. Deficiency of DDAH1 and subsequent increase in systemic ADMA levels did not exacerbate these changes, indicating that ADMA is not the major mediator of diabetic nephropathy in this experiment model.

Increased Circulating Osteoprotegerin Levels in Type 1 Diabetes Mellitus: A Systematic Review and Meta-analysis Based on Observational Studies

Objectives: Type 1 diabetes mellitus (T1D) has been disclosed to be associated with an elevated risk of cardiovascular disease (CVD), as well as increased risks of losing bone mass and progression of osteoporosis (OP). Osteoprotegerin (OPG), as a decoy receptor, has been demonstrated to play a critical role in bone metabolism homeostasis and vascular atherosclerotic diseases. This meta-analysis aimed to investigate the associations between OPG levels and T1D. Methods: Related literatures were searched and identified from the database of the Cochrane Library database, PubMed and EMbase inception to August 3, 2019 in English. The pooled standard mean difference (SMD) with its 95% confidence interval (CI) was calculated in using random-effect model analysis. Chi-square Q statistic and I² test were performed to evaluate and quantified the presence of heterogeneity. Results: Twelve studies with 1288 subjects (794 T1D patients and 494 healthy controls) were finally included. The incorporated results indicated that T1D patients have higher plasma/serum OPG levels than in healthy individuals (SMD = 0.64, 95% CI: 0.06, 1.22). Subgroup analyses suggested that Caucasian and glycosylated hemoglobin A1c (HbA1c) <8.5% groups showed higher OPG levels, however, there was no significant differences of OPG levels regarding subgroups of BMI ≥ or <25, children-adolescents or adults and HbA1c ≥8.5%. Conclusions: The current evidence suggested that circulating OPG levels are significantly higher in T1D than in healthy controls, and the increase of OPG levels are influenced by factors of race and HbA1c.

Pediatric endocrinology: an overview of the last decade

Over the past decade, considerable progress has been made in the field of pediatric endocrinology. However, there is still a long way to go regarding the exploration of novel avenues, such as epigenetics, the changing views on the pathophysiology and derived therapy of specific disorders, and the prevention of prevalent diseases. The next decade will hopefully bring the consolidation of most of those achievements and the development of new pathways for further progress.

Relationship of Serum Fetuin A with Metabolic and Clinical Parameters in German Children and Adolescents with Type 1 Diabetes

BACKGROUND AND AIM

The hepatokine fetuin A is upregulated in the metabolic syndrome and in type 2 diabetes (T2D), while its role in adolescent type 1 diabetes (T1D) is unclear. We assessed the relationship between circulating fetuin A levels and metabolic control, comorbidities, and complications in adolescent T1D patients.

METHODS

We studied the relationship between serum fetuin A and clinical diabetes-related data from the DPV registry (Diabetes-Pa-tienten-Verlaufsdokumentation) in 172 adolescent T1D patients with early-onset (<5 years) long-standing (>10 years) T1D. Fetuin A levels were further compared between adolescent T1D and T2D patients.

RESULTS

Serum fetuin A levels in T1D patients (mean 0.267 ± 0.043 g/L) did not correlate with age, diabetes duration, gender, body mass index (BMI), glycated hemoglobin, serum lipid levels, blood pressure, celiac or thyroid disease, nephropathy, or retinopathy. An association of fetuin A levels with insulin requirements was only evident within the subgroup of overweight T1D patients (rs = 0.439, p = 0.028, n = 25, BMI >90th percentile), disappearing after adjustment for multiple testing. Adolescent T1D patients showed distinctly lower fetuin A levels than patients with T2D (p ≤ 0.001).

CONCLUSION

Overall, we did not observe a clinically relevant association of fetuin A levels with surrogate parameters for insulin sensitivity in our juvenile T1D cohort. A correlation with insulin requirements was detectable in overweight patients only. We hypothesize that multiple factors, such as obesity, puberty, inadequate metabolic control, and hepatic steatosis, have to add up before a clinically relevant effect of fetuin A on insulin sensitivity becomes evident.

Skeletal growth and bone mineral acquisition in type 1 diabetic children; abnormalities of the GH/IGF-1 axis

Type 1 diabetes mellitus (T1DM) is one of the most common chronic diseases diagnosed in childhood. Childhood and adolescent years are also the most important period for growth in height and acquisition of skeletal bone mineral density (BMD). The growth hormone (GH)/insulin like growth factor -1 (IGF-1) axis which regulates growth, is affected by T1DM, with studies showing increased GH and decreased IGF-1 levels in children with T1DM. There is conflicting data as to whether adolescents with TIDM are able to achieve their genetically-determined adult height. Furthermore, data support that adolescents with T1DM have decreased peak BMD, although the pathophysiology of which has not been completely defined. Various mechanisms have been proposed for the decrease in BMD including low osteocalcin levels, reflecting decreased bone formation; increased sclerostin, an inhibitor of bone anabolic pathways; and increased leptin, an adipocytokine which affects bone metabolism via central and peripheral mechanisms. Other factors implicated in the increased bone resorption in T1DM include upregulation of the osteoprotegerin/ receptor-activator of the nuclear factor-κB ligand pathway, elevated parathyroid hormone levels, and activation of other cytokines involved in chronic systemic inflammation. In this review, we summarize the clinical studies that address the alterations in the GH/IGF-I axis, linear growth velocity, and BMD in children and adolescents with T1DM; and we review the possible molecular mechanisms that may contribute to an attenuation of linear growth and to the reduction in the acquisition of peak bone mass in the child and adolescent with T1DM.

MECHANISMS IN ENDOCRINOLOGY: Diabetes mellitus, a state of low bone turnover - a systematic review and meta-analysis

OBJECTIVE

To investigate the differences in bone turnover between diabetic patients and controls.

DESIGN

A systematic review and meta-analysis.

METHODS

A literature search was conducted using the databases Medline at PubMed and EMBASE. The free text search terms 'diabetes mellitus' and 'bone turnover', 'sclerostin', 'RANKL', 'osteoprotegerin', 'tartrate-resistant acid' and 'TRAP' were used. Studies were eligible if they investigated bone turnover markers in patients with diabetes compared with controls. Data were extracted by two reviewers.

RESULTS

A total of 2881 papers were identified of which 66 studies were included. Serum levels of the bone resorption marker C-terminal cross-linked telopeptide (-0.10 ng/mL (-0.12, -0.08)) and the bone formation markers osteocalcin (-2.51 ng/mL (-3.01, -2.01)) and procollagen type 1 amino terminal propeptide (-10.80 ng/mL (-12.83, -8.77)) were all lower in patients with diabetes compared with controls. Furthermore, s-tartrate-resistant acid phosphatase was decreased in patients with type 2 diabetes (-0.31 U/L (-0.56, -0.05)) compared with controls. S-sclerostin was significantly higher in patients with type 2 diabetes (14.92 pmol/L (3.12, 26.72)) and patients with type 1 diabetes (3.24 pmol/L (1.52, 4.96)) compared with controls. Also, s-osteoprotegerin was increased among patients with diabetes compared with controls (2.67 pmol/L (0.21, 5.14)).

CONCLUSIONS

Markers of both bone formation and bone resorption are decreased in patients with diabetes. This suggests that diabetes mellitus is a state of low bone turnover, which in turn may lead to more fragile bone. Altered levels of sclerostin and osteoprotegerin may be responsible for this.