The peroxisome proliferator-activated receptor-gamma agonist rosiglitazone decreases bone formation and bone mineral density in healthy postmenopausal women: a randomized, controlled trial

Tetrahydrocannabinolic acid is a potent PPARγ agonist with neuroprotective activity

BACKGROUND AND PURPOSE

Phytocannabinoids are produced in Cannabis sativa L. in acidic form and are decarboxylated upon heating, processing and storage. While the biological effects of decarboxylated cannabinoids such as Δ9 -tetrahydrocannabinol have been extensively investigated, the bioactivity of Δ9 -tetahydrocannabinol acid (Δ9 -THCA) is largely unknown, despite its occurrence in different Cannabis preparations. Here we have assessed possible neuroprotective actions of Δ9 -THCA through modulation of PPARγ pathways.

EXPERIMENTAL APPROACH

The effects of six phytocannabinoids on PPARγ binding and transcriptional activity were investigated. The effect of Δ9 -THCA on mitochondrial biogenesis and PPARγ coactivator 1-α expression was investigated in Neuro-2a (N2a) cells. The neuroprotective effect was analysed in STHdhQ111/Q111 cells expressing a mutated form of the huntingtin protein and in N2a cells infected with an adenovirus carrying human huntingtin containing 94 polyQ repeats (mHtt-q94). The in vivo neuroprotective activity of Δ9 -THCA was investigated in mice intoxicated with the mitochondrial toxin 3-nitropropionic acid (3-NPA).

KEY RESULTS

Cannabinoid acids bind and activate PPARγ with higher potency than their decarboxylated products. Δ9 -THCA increased mitochondrial mass in neuroblastoma N2a cells and prevented cytotoxicity induced by serum deprivation in STHdhQ111/Q111 cells and by mutHtt-q94 in N2a cells. Δ9 -THCA, through a PPARγ-dependent pathway, was neuroprotective in mice treated with 3-NPA, improving motor deficits and preventing striatal degeneration. In addition, Δ9 -THCA attenuated microgliosis, astrogliosis and up-regulation of proinflammatory markers induced by 3-NPA.

CONCLUSIONS AND IMPLICATIONS

Δ9 -THCA shows potent neuroprotective activity, which is worth considering for the treatment of Huntington's disease and possibly other neurodegenerative and neuroinflammatory diseases.

Low bone turnover in premenopausal women with type 2 diabetes mellitus as an early process of diabetes-associated bone alterations: a cross-sectional study

BACKGROUND

Individuals with Diabetes Mellitus (DM) are at increased risk for fracture due to the decrease in bone strength and quality. Serum procollagen type I intact N-terminal (P1NP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX) as markers of bone formation and resorption, respectively, have been reported to be decreased in T2DM. It remains unclear whether diabetes-associated alterations in the bone turnover of T2DM individuals are related to the longer duration of the disease or may occur earlier. Furthermore, previous studies on BTMs in T2DM individuals have mostly been done in postmenopausal women with T2DM, which might have masked the DM-induced alterations of bone turnover with concurrent estrogen deficiency. This study aims to assess the levels of serum P1NP and CTX as markers of bone turnover in premenopausal women with and without T2DM.

METHODS

This cross-sectional study involves 41 premenopausal women with T2DM, and 40 premenopausal women without DM. Sampling was done consecutively. P1NP and CTX measurement was done using the electrochemi-luminescence immunoassay (ECLIA) method. Other data collected include levels of HbA1C, ALT, creatinine, eGFR and lipid profile.

RESULTS

Median (interquartile range) P1NP in T2DM is 29.9 ng/ml (24.7-41.8 ng/ml), while in non-DM is 37.3 ng/ml, (30.8-47.3 ng/ml; p = 0.007). Median (interquartile range) CTX in T2DM is 0.161 ng/ml (0.106-0.227 ng/ml), while in non-DM is 0.202 ng/ml (0.166-0.271 ng/ml; p = 0.0035). Levels of P1NP and CTX in the T2DM group did not correlate with the duration of disease, age, BMI or the levels of HbA1C.

CONCLUSIONS

Premenopausal women with T2DM indeed have lower bone turnover when compared with non-DM controls. This significantly lower bone turnover process starts relatively early in the premenopausal age, independent of the duration of DM. Gaining understanding of the early pathophysiology of altered bone turnover may be key in developing preventive strategies for diabetoporosis.

Impact of pioglitazone on bone mineral density and bone marrow fat content

Pioglitazone use is associated with an increased risk of fractures. In this randomized, placebo-controlled study, pioglitazone use for 12 months was associated with a significant increase in bone marrow fat content at the femoral neck, accompanied by a significant decrease in total hip bone mineral density. The change in bone marrow fat with pioglitazone use was predominantly observed in female vs. male participants.

INTRODUCTION

Use of the insulin sensitizer pioglitazone is associated with greater fracture incidence, although the underlying mechanisms are incompletely understood. This study aimed to assess the effect of pioglitazone treatment on femoral neck bone marrow (BM) fat content and on bone mineral density (BMD), and to establish if any correlation exists between the changes in these parameters.

METHODS

In this double-blind placebo-controlled clinical trial, 42 obese volunteers with metabolic syndrome were randomized to pioglitazone (45 mg/day) or matching placebo for 1 year. The following measurements were conducted at baseline and during the treatment: liver, pancreas, and femoral neck BM fat content (by magnetic resonance spectroscopy), BMD by DXA, abdominal subcutaneous and visceral fat, and beta-cell function and insulin sensitivity.

RESULTS

Results were available for 37 subjects who completed the baseline and 1-year evaluations. At 12 months, BM fat increased with pioglitazone (absolute change, +4.1%, p = 0.03), whereas BM fat content in the placebo group decreased non-significantly (-3.1%, p = 0.08) (p = 0.007 for the pioglitazone-placebo response difference). Total hip BMD declined in the pioglitazone group (-1.4%) and increased by 0.8% in the placebo group (p = 0.03 between groups). The change in total hip BMD was inversely and significantly correlated with the change in BM fat content (Spearman rho = -0.56, p = 0.01) in the pioglitazone group, but not within the placebo group (rho = -0.29, p = 0.24). Changes in BM fat with pioglitazone were predominantly observed in female vs. male subjects.

CONCLUSIONS

Pioglitazone use for 12 months compared with placebo is associated with significant increase in BM fat content at the femoral neck, accompanied by a small but significant decrease in total hip BMD.

Adverse bone effects of medications used to treat non-skeletal disorders

There is a growing list of medications used to treat non-skeletal disorders that cause bone loss and/or increase fracture risk. This review discusses glucocorticoids, drugs that reduce sex steroids, antidiabetic agents, acid-reducing drugs, selective serotonin reuptake inhibitors, and heparin. A number of drugs are known to cause bone loss, increase fracture risk, or both. These drugs should be used in the lowest dose necessary to achieve the desired benefit and for the shortest time necessary, but in many cases, long-term treatment is required. Effective countermeasures are available for some.

Type 2 Diabetes and Osteoporosis: A Guide to Optimal Management

CONTEXT

Both type 2 diabetes (T2D) and osteoporosis are affected by aging and quite often coexist. Furthermore, the fracture risk in patients with T2D is increased. The aim of this article is to review updated information on osteoporosis and fracture risk in patients with T2D, to discuss the effects of diabetes treatment on bone metabolism, as well as the effect of antiosteoporotic medications on the incidence and control of T2D, and to provide a personalized guide to the optimal management.

EVIDENCE ACQUISITION

A systematic literature search for human studies was conducted in three electronic databases (PubMed, Cochrane, and EMBASE) until March 2017. Regarding recommendations, we adopted the grading system introduced by the American College of Physicians.

EVIDENCE SYNTHESIS

The results are presented in systematic tables. Healthy diet and physical exercise are very important for the prevention and treatment of both entities. Metformin, sulfonylureas, dipeptidyl peptidase-4 inhibitors, and glucagon-like peptide-1 receptor agonists should be preferred for the treatment of T2D in these patients, whereas strict targets should be avoided for the fear of hypoglycemia, falls, and fractures. Insulin should be used with caution and with careful measures to avoid hypoglycemia. Thiazolidinediones and canagliflozin should be avoided, whereas other sodium-dependent glucose transporter 2 inhibitors are less well-validated options. Insulin therapy is the preferred method for achieving glycemic control in hospitalized patients with T2D and fractures. The treatment and monitoring of osteoporosis should be continued without important amendments because of the presence of T2D.

CONCLUSIONS

Patients with coexisting T2D and osteoporosis should be managed in an optimal way according to scientific evidence.

Review article: effects of type 2 diabetes therapies on bone metabolism

Diabetes complications and osteoporotic fractures are two of the most important causes of morbidity and mortality in older patients, and they share many features, including genetic susceptibility, molecular mechanisms, and environmental factors. Type 2 diabetes mellitus (T2DM) compromises bone microarchitecture by inducing abnormal bone cell function and matrix structure with increased osteoblast apoptosis, diminished osteoblast differentiation, and enhanced osteoclast-mediated bone resorption. The linkage between these two chronic diseases creates a possibility that certain antidiabetic therapies may affect bone function. The treatment of T2DM has been improved in the past two decades with the development of new therapeutic drugs. Each class has a pathophysiologic target related to the regulation of the energy metabolism and insulin secretion. However, both glycemic homeostasis and bone homeostasis are under the control of common regulatory factors. This background allows the individual pharmacological targets of antidiabetic therapies to affect bone quality due to their indirect effects on bone cell differentiation and the bone remodeling process. With a greater number of diabetic patients and antidiabetic agents being launched, it is critical to highlight the consequences of this disease and its pharmacological agents on bone health and fracture risk. Currently, there is little scientific knowledge approaching the impact of most anti-diabetic treatments on bone quality and fracture risk. Thus, this review aims to explore the pros and cons of the available pharmacologic treatments for T2DM on bone mineral density and risk fractures in humans.

Use of CTX-I and PINP as bone turnover markers: National Bone Health Alliance recommendations to standardize sample handling and patient preparation to reduce pre-analytical variability

The National Bone Health Alliance (NBHA) recommends standardized sample handling and patient preparation for C-terminal telopeptide of type I collagen (CTX-I) and N-terminal propeptide of type I procollagen (PINP) measurements to reduce pre-analytical variability. Controllable and uncontrollable patient-related factors are reviewed to facilitate interpretation and minimize pre-analytical variability.

INTRODUCTION

The IOF and the International Federation of Clinical Chemistry (IFCC) Bone Marker Standards Working Group have identified PINP and CTX-I in blood to be the reference markers of bone turnover for the fracture risk prediction and monitoring of osteoporosis treatment. Although used in clinical research for many years, bone turnover markers (BTM) have not been widely adopted in clinical practice primarily due to their poor within-subject and between-lab reproducibility. The NBHA Bone Turnover Marker Project team aim to reduce pre-analytical variability of CTX-I and PINP measurements through standardized sample handling and patient preparation.

METHODS

Recommendations for sample handling and patient preparations were made based on review of available publications and pragmatic considerations to reduce pre-analytical variability. Controllable and un-controllable patient-related factors were reviewed to facilitate interpretation and sample collection.

RESULTS

Samples for CTX-I must be collected consistently in the morning hours in the fasted state. EDTA plasma is preferred for CTX-I for its greater sample stability. Sample collection conditions for PINP are less critical as PINP has minimal circadian variability and is not affected by food intake. Sample stability limits should be observed. The uncontrollable aspects (age, sex, pregnancy, immobility, recent fracture, co-morbidities, anti-osteoporotic drugs, other medications) should be considered in BTM interpretation.

CONCLUSION

Adopting standardized sample handling and patient preparation procedures will significantly reduce controllable pre-analytical variability. The successful adoption of such recommendations necessitates the close collaboration of various stakeholders at the global stage, including the laboratories, the medical community, the reagent manufacturers and the regulatory agencies.

Use of thiazolidinediones and risk of hip fracture in old people in a case-control study in Taiwan

Little research is available on the association between use of thiazolidinediones and hip fracture in old people in Taiwan. We conducted a population-based case-control study to examine this issue.Using the database of the Taiwan National Health Insurance Program, we identified 603 type 2 diabetic subjects 65 years or older in age with newly diagnosed hip fracture in 2000 to 2013 as cases. We randomly selected 603 type 2 diabetic subjects 65 years or older without hip fracture as the controls. Both cases and controls were matched with sex, age, comorbidities, and index year of diagnosing hip fracture. Current use of thiazolidinediones was defined as subjects whose last remaining one tablet of thiazolidinediones was noted ≤30 days before the date of diagnosing hip fracture. Never use of thiazolidinediones was defined as subjects who never had a prescription of thiazolidinediones. The odds ratio (OR) and 95% confidence interval (CI) for hip fracture associated with thiazolidinediones use was estimated by the multivariable unconditional logistic regression analysis.After adjustment for covariables, the multivariable logistic regression analysis revealed that the adjusted OR of hip fracture was 1.64 for subjects with current use of thiazolidinediones (95% CI 1.01, 2.67), when compared with subjects with never use of thiazolidinediones.Our findings suggest that current use of thiazolidinediones is associated with a 64% higher risk of hip fracture in type 2 diabetic old people in Taiwan. Clinicians should consider the possibility of thiazolidinediones-associated hip fracture among type 2 diabetic old people currently using thiazolidinediones.

Thiazolidinedione drugs in the treatment of type 2 diabetes mellitus: past, present and future

Thiazolidinedione (TZD) drugs used in the treatment of type 2 diabetes mellitus (T2DM) have proven effective in improving insulin sensitivity, hyperglycemia, and lipid metabolism. Though well tolerated by some patients, their mechanism of action as ligands of peroxisome proliferator-activated receptors (PPARs) results in the activation of several pathways in addition to those responsible for glycemic control and lipid homeostasis. These pathways, which include those related to inflammation, bone formation, and cell proliferation, may lead to adverse health outcomes. As treatment with TZDs has been associated with adverse hepatic, cardiovascular, osteological, and carcinogenic events in some studies, the role of TZDs in the treatment of T2DM continues to be debated. At the same time, new therapeutic roles for TZDs are being investigated, with new forms and isoforms currently in the pre-clinical phase for use in the prevention and treatment of some cancers, inflammatory diseases, and other conditions. The aims of this review are to provide an overview of the mechanism(s) of action of TZDs, a review of their safety for use in the treatment of T2DM, and a perspective on their current and future therapeutic roles.

IP6K1 Reduces Mesenchymal Stem/Stromal Cell Fitness and Potentiates High Fat Diet-Induced Skeletal Involution

Mesenchymal stem/stromal cells (MSCs) are the predominant source of bone and adipose tissue in adult bone marrow and play a critical role in skeletal homeostasis. Age‐induced changes in bone marrow favor adipogenesis over osteogenesis leading to skeletal involution and increased marrow adiposity so pathways that prevent MSC aging are potential therapeutic targets for treating age‐related bone diseases. Here, we show that inositol hexakisphosphate kinase 1 (Ip6k1) deletion in mice increases MSC yields from marrow and enhances cell growth and survival ex vivo. In response to the appropriate stimuli, Ip6k1^−/− versus Ip6k1^+/+ MSCs also exhibit enhanced osteogenesis and hematopoiesis‐supporting activity and reduced adipogenic differentiation. Mechanistic‐based studies revealed that Ip6k1^−/− MSCs express higher MDM2 and lower p53 protein levels resulting in lower intrinsic mitochondrial reactive oxygen species (ROS) levels as compared to Ip6k1^+/+ MSCs, but both populations upregulate mitochondrial ROS to similar extents in response to oxygen‐induced stress. Finally, we show that mice fed a high fat diet exhibit reduced trabecular bone volume, and that pharmacological inhibition of IP6K1 using a pan‐IP6K inhibitor largely reversed this phenotype while increasing MSC yields from bone marrow. Together, these findings reveal an important role for IP6K1 in regulating MSC fitness and differentiation fate. Unlike therapeutic interventions that target peroxisome proliferator‐activated receptor gamma and leptin receptor activity, which yield detrimental side effects including increased fracture risk and altered feeding behavior, respectively, inhibition of IP6K1 maintains insulin sensitivity and prevents obesity while preserving bone integrity. Therefore, IP6K1 inhibitors may represent more effective insulin sensitizers due to their bone sparing properties. Stem Cells2017;35:1973–1983

Effects of vitamin D combined with pioglitazone hydrochloride on bone mineral density and bone metabolism in Type 2 diabetic nephropathy

The study aims to investigate the effect of vitamin D (VD) combined with pioglitazone hydrochloride (PIO) on bone mineral density (BMD) and bone metabolism in patients with Type 2 diabetic nephropathy (T2DN). T2DN patients were selected and assigned into mild, moderate, and severe groups. In each group, three therapy regimens (VD, PIO, and VD plus PIO) were administered. X-ray absorptiometry was used to measure BMD. Intact parathyroid hormone (iPTH) and 25-hydroxyvitamin D3 (25-OH-VD3) were measured by chemiluminescence meter. ELISA was applied to detect levels of osteoprotegerin (OPG), bone gla protein (BGP), C-terminal telopeptides of type I collagen (β-CTX), procollagen type I N-propeptide (PINP), pyridinoline (Pyr), and deoxypyridinoline (D-Pyr). Compared with the mild group, T2DN patients in the moderate and severe groups had longer course of disease and higher levels of total cholesterol (TC), triglyceride (TG), serum phosphorus, fasting plasma glucose (FPG), glycosylated hemoglobin (HbAlc) and creatine (Cr), and lower blood calcium. The BMD in different parts increased among the mild, moderate, and severe groups, and the highest BMD was found after VD plus PIO treatment. OPG, iPTH, BGP, β-CTX, Pyr/Cr, and D-Pyr/Cr levels were reduced, while 25-OH-VD3 and PINP levels were elevated among three groups after different treatments, and the most obvious change was observed after VD plus PIO treatment. Our findings indicate that VD combined with PIO may be more effective in improving BMD and bone metabolism than VD or PIO alone in the treatment of T2DN patients, especially for T2DN patients with mild disease.

Pioglitazone and Risk for Bone Fracture: Safety Data From a Randomized Clinical Trial

CONTEXT

Pioglitazone reduces cardiovascular risk in nondiabetic patients after an ischemic stroke or transient ischemic attack (TIA) but is associated with increased risk for bone fracture.

OBJECTIVE

To characterize fractures associated with pioglitazone by location, mechanism, severity, timing, and sex.

DESIGN, SETTING, AND PATIENTS

Patients were 3876 nondiabetic participants in the Insulin Resistance Intervention after Stroke trial randomized to pioglitazone or placebo and followed for a median of 4.8 years. Fractures were identified through quarterly interviews.

RESULTS

At 5 years, the increment in fracture risk between pioglitazone and placebo groups was 4.9% [13.6% vs 8.8%; hazard ratio (HR), 1.53; 95% confidence interval (CI), 1.24 to 1.89). In each group, ∼80% of fractures were low energy (i.e., resulted from fall) and 45% were serious (i.e., required surgery or hospitalization). For serious fractures most likely to be related to pioglitazone (low energy, nonpathological), the risk increment was 1.6% (4.7% vs 3.1%; HR, 1.47; 95% CI, 1.03 to 2.09). Increased risk for any fracture was observed in men (9.4% vs 5.2%; HR, 1.83; 95% CI, 1.36 to 2.48) and women (14.9% vs 11.6%; HR, 1.32; 95% CI, 0.98 to 1.78; interaction P = 0.13).

CONCLUSIONS

Fractures affected 8.8% of placebo-treated patients within 5 years after an ischemic stroke or TIA. Pioglitazone increased the absolute fracture risk by 1.6% to 4.9% and the relative risk by 47% to 60%, depending on fracture classification. Our analysis suggests that treatments to improve bone health and prevent falls may help optimize the risk/benefit ratio for pioglitazone.

PPARs in the central nervous system: roles in neurodegeneration and neuroinflammation

Over 25 years have passed since peroxisome proliferators-activated receptors (PPARs), were first described. Like other members of the nuclear receptors superfamily, PPARs have been defined as critical sensors and master regulators of cellular metabolism. Recognized as ligand-activated transcription factors, they are involved in lipid, glucose and amino acid metabolism, taking part in different cellular processes, including cellular differentiation and apoptosis, inflammatory modulation and attenuation of acute and chronic neurological damage in vivo and in vitro. Interestingly, PPAR activation can simultaneously reprogram the immune response, stimulate metabolic and mitochondrial functions, promote axonal growth, induce progenitor cells to differentiate into myelinating oligodendrocytes, and improve brain clearance of toxic molecules such as β-amyloid peptide. Although the molecular mechanisms and cross-talk with different molecular pathways are still the focus of intense research, PPARs are considered potential therapeutic targets for several neuropathological conditions, including degenerative disorders such as Alzheimer's, Parkinson's and Huntington's disease. This review considers recent advances regarding PPARs, as well as new PPAR agonists. We focus on the mechanisms behind the neuroprotective effects exerted by PPARs and summarise the roles of PPARs in different pathologies of the central nervous system, especially those associated with degenerative and inflammatory mechanisms.

Diabetes Drug Effects on the Skeleton

Diabetes be it type 1 or type 2 is associated with an increased risk of fragility fractures. The mechanisms underlying this increased risk are just being elucidated. Anti-diabetes medications are crucial for maintaining glucose control and for preventing micro- and macrovascular complications in diabetes. However, they may modulate fracture risk in diabetes in different ways. Thiazolidinediones have demonstrated an unfavorable effect on the skeleton, while metformin and sulfonylureas may have a neutral if not beneficial effect on bone. The use of insulin has been associated with an increased risk of fragility fractures though it is not clear whether it is due to direct influence of insulin or whether it is mediated through hypoglycemia and increased falls risk. The overall effect of incretin mimetics appears to be beneficial; however, this has to be elucidated further. The bone effects of pramlintide, a synthetic analog of amylin, have not been explored fully. Finally, issues regarding bone safety of SGLT2 (sodium-dependent glucose transporter 2) inhibitors, the newest anti-diabetic medications on the market are of concern. The purpose of this review is to provide a comprehensive overview of the effect of these medications on bone metabolism and the studies exploring the risk or lack thereof of these medications on bone loss and fragility fractures.

MANAGEMENT OF ENDOCRINE DISEASE: Morbidity in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine condition in premenopausal women. The syndrome is characterized by hyperandrogenism, irregular menses and polycystic ovaries when other etiologies are excluded. Obesity, insulin resistance and low vitamin D levels are present in more than 50% patients with PCOS, these factors along with hyperandrogenism could have adverse effects on long-term health. Hyperinflammation and impaired epithelial function were reported to a larger extent in women with PCOS and could particularly be associated with hyperandrogenism, obesity and insulin resistance. Available data from register-based and data linkage studies support that metabolic-vascular and thyroid diseases, asthma, migraine, depression and cancer are diagnosed more frequently in PCOS, whereas fracture risk is decreased. Drug prescriptions are significantly more common in PCOS than controls within all diagnose categories including antibiotics. The causal relationship between PCOS and autoimmune disease represents an interesting new area of research. PCOS is a lifelong condition and long-term morbidity could be worsened by obesity, sedentary way of life, Western-style diet and smoking, whereas lifestyle intervention including weight loss may partly or fully resolve the symptoms of PCOS and could improve the long-term prognosis. In this review, the possible implications of increased morbidity for the clinical and biochemical evaluation of patients with PCOS at diagnosis and follow-up is further discussed along with possible modifying effects of medical treatment.

Metformin suppresses adipogenesis through both AMP-activated protein kinase (AMPK)-dependent and AMPK-independent mechanisms

People with Type 2 diabetes mellitus (T2DM) have reduced bone mineral density and an increased risk of fractures due to altered mesenchymal stem cell (MSC) differentiation in the bone marrow. This leads to a shift in the balance of differentiation away from bone formation (osteogenesis) in favour of fat cell development (adipogenesis). The commonly used anti-diabetic drug, metformin, activates the osteogenic transcription factor Runt-related transcription factor 2 (Runx2), which may suppress adipogenesis, leading to improved bone health. Here we investigate the involvement of the metabolic enzyme, AMP-activated protein kinase (AMPK), in these protective actions of metformin. The anti-adipogenic actions of metformin were observed in multipotent C3H10T1/2 MSCs, in which metformin exerted reciprocal control over the activities of Runx2 and the adipogenic transcription factor, PPARγ, leading to suppression of adipogenesis. These effects appeared to be independent of AMPK activation but rather through the suppression of the mTOR/p70^S6K signalling pathway. Basal AMPK and mTOR/p70^S6K activity did appear to be required for adipogenesis, as demonstrated by the use of the AMPK inhibitor, compound C. This observation was further supported by using AMPK knockout mouse embryo fibroblasts (MEFs) where adipogenesis, as assessed by reduced lipid accumulation and expression of the adipogeneic transcription factor, C/EBPβ, was found to display an absolute requirement for AMPK. Further activation of AMPK in wild type MEFS, with either metformin or the AMPK-specific activator, A769662, was also associated with suppression of adipogenesis. It appears, therefore, that basal AMPK activity is required for adipogenesis and that metformin can inhibit adipogenesis through AMPK-dependent or -independent mechanisms, depending on the cellular context.

The Effects of Pioglitazone on Bone Formation and Resorption Markers in Type 2 Diabetes Mellitus

Objective The use of thiazolidinediones is reported to be associated with an increased frequency of fractures, especially in women; however, the underlying mechanism is not clear. In this prospective study, we compared the effects of pioglitazone and metformin on bone metabolism in Japanese patients with type 2 diabetes mellitus. Methods A total of 58 patients with type 2 diabetes (24 men and 34 women) were randomly assigned to receive either pioglitazone (30 and 15 mg/day for men and women, respectively) or metformin (750 mg/day). The changes in serum and urinary type 1 cross-linked N-telopeptide (NTX), type 1 cross-linked C-telopeptide (CTX), bone alkaline phosphatase (BAP), homocysteine, and serum pentosidine were evaluated before and after three months of treatment. The primary endpoint was changes in bone resorption markers after three months. Patients The subjects of this research were male and female type 2 diabetes patients, less than 80 years of age. Results Pioglitazone significantly increased the serum and urinary NTX and serum and urinary CTX levels. The rates of changes in the serum and urinary NTX and CTX were significantly greater in the pioglitazone group than in the metformin group. Although the BAP levels decreased significantly in the pioglitazone group, the rates of change were similar between the two groups. In the pioglitazone group, the changes in fasting insulin levels correlated significantly with increased bone resorption, independent of age and gender. Conclusion The results demonstrated that pioglitazone increased bone resorption independent of age and gender in Japanese patients with type 2 diabetes.

Vildagliptin has the same safety profile as a sulfonylurea on bone metabolism and bone mineral density in post-menopausal women with type 2 diabetes: a randomized controlled trial

BACKGROUND

Several antidiabetic therapies affect bone metabolism. Sulfonylureas have the lowest impact on bone among oral antidiabetics. The objective of this study is to compare the effects of vildagliptin and gliclazide modified release (MR) on bone turnover markers (BTMs) and bone mineral density (BMD) in postmenopausal women with uncontrolled type 2 diabetes (T2D).

METHODS

Forty-two postmenopausal women with uncontrolled T2D were randomly allocated into vildagliptin or gliclazide MR (control) groups. The primary endpoint was the change in the BTMs in months 6 and 12 compared with the baseline. The secondary endpoint was the variation in the BMD, which was assessed via dual-energy X-ray absorptiometry at the lumbar spine, femoral neck and total hip at baseline and month 12.

RESULTS

After a 12-month treatment, the BTM serum carboxy-terminal telopeptide of type 1 collagen increased 0.001 ± 0.153 ng/mL in the vildagliptin group versus 0.008 ± 0.060 ng/mL in the gliclazide MR group (p = 0.858). The serum osteocalcin, serum amino-terminal propeptide of procollagen type I and urinary amino-terminal telopeptide of type 1 collagen remained stable in both groups, and there was no statistically significant difference between the effect of vildagliptin and gliclazide MR on these variables. The lumbar spine BMD did not change in the vildagliptin or gliclazide MR groups after a 12-month treatment (0.000 ± 0.025 g/cm² versus -0.008 ± 0.036, respectively, p = 0.434). Furthermore, there was a similar lack of change in the femoral neck and total hip BMD values in both treatments.

CONCLUSIONS

Bone turnover markers and BMD remained unchanged after a 12-month treatment in both groups, which suggests that vildagliptin has the same safety profile as gliclazide MR on bone metabolism. Trial Registration ClinicalTrials.gov number NCT01679899.

Glucagon-like peptide-1(GLP-1) receptor agonists: potential to reduce fracture risk in diabetic patients?

This review summarizes current knowledge about glucagon-like peptide 1 receptor agonists (GLP-1 RA) and their effects on bone metabolism and fracture risk. Recent in vivo and in vitro experiments indicated that GLP-1 RA could improve bone metabolism. GLP-1 could affect the fat-bone axis by promoting osteogenic differentiation and inhibiting adipogenic differentiation of bone mesenchymal precursor cells (BMSCs), which express the GLP-1 receptor. GLP-1 RA may also influence the balance between osteoclasts and osteoblasts, thus leading to more bone formation and less bone resorption. Wnt/β-catenin signalling is involved in this process. Mature osteocytes, which also express the GLP-1 receptor, produce sclerostin which inhibits Wnt/β-catenin signalling by binding to low density lipoprotein receptor-related protein (LRP) 5 and preventing the binding of Wnt. GLP-1 RA also decreases the expression of sclerostin (SOST) and circulating levels of SOST. In addition, GLP-1 receptors are expressed in thyroid C cells, where GLP-1 induces calcitonin release and thus indirectly inhibits bone resorption. Furthermore, GLP-1 RA influences the osteoprotegerin(OPG)/receptor activator of nuclear factor-κB ligand (RANKL)/receptor activator of nuclear factor-κB (RANK) system by increasing OPG gene expression, and thus reverses the decreased bone mass in rats models. However, a recent meta-analysis and a cohort study did not show a significant relationship between GLP-RA use and fracture risk. Future clinical trials will be necessary to investigate thoroughly the relationship between GLP-1 RA use and fracture risk in diabetic patients.

Risk of fractures and diabetes medications: a nationwide cohort study

The effects of diabetes medications on risk of fracture were investigated using the South Korea nationwide claims database. We demonstrated that the use of dipeptidyl peptidase-4 inhibitor could be associated with decreased risk of fracture. Thiazolidinedione use was associated with about 60 % increased risk of fracture in real clinical practice.

INTRODUCTION

The effects of diabetes medication on fracture have important clinical health consequences, since most diabetes patients are at high risk of fracture. We aimed to investigate the effect of diabetes medication on fracture risk.

METHODS

The nationwide medical claim database in South Korea was investigated. Among 2,886,555 subjects with antidiabetes prescriptions, 207,558 subjects aged 50 years and older, who initiated diabetes medication from 2008 to 2011, were analyzed. The subjects were classified based on diabetes medication classes: non-user (insufficient exposure), metformin (MET), sulfonylurea (SU), alpha-glucosidase inhibitor (AGI), MET + SU, MET + thiazolidinedione (TZD), MET + dipeptidyl peptidase-4 inhibitor (DPP4-I), and SU + TZD.

RESULTS

A total of 5996 fractures were observed. The fracture rate varied significantly across type of diabetes medications, with MET + DPP4-I combination group having the lowest rate and SU + TZD combination group having the highest rate. Compared to non-users, MET + DPP4-I inhibitor combination group had significantly reduced composite fracture risk (hazard ratio (HR) = 0.83, P = 0.025) and significantly reduced vertebral fracture risk (HR = 0.73, P = 0.013) in the unadjusted analysis. Compared to MET + SU users, MET + DPP4-I users showed a trend of lower non-vertebral fracture risk (HR = 0.82, P = 0.086) after adjusting for all confounding variables. Patients using TZD had significantly increased risk of fracture (HR = 1.59, P < 0.001) compared with patients not using TZDs adjusting for all confounding variables.

CONCLUSIONS

The results of this nationwide study showed a trend that DPP4 inhibitor might have a protective effect on bone metabolism compared with SU, when added to MET. Clinicians should take these results into consideration when prescribing diabetes medication, especially in elderly patients or those at high risk or fracture.

Non-insulin drugs to treat hyperglycaemia in type 1 diabetes mellitus

Insulin treatment of individuals with type 1 diabetes has shortcomings and many patients do not achieve glycaemic and metabolic targets. Consequently, the focus is on novel non-insulin therapeutic approaches that reduce hyperglycaemia and improve metabolic variables without increasing the risk of hypoglycaemia or other adverse events. Several therapies given in conjunction with insulin have been investigated in clinical trials, including pramlintide, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, sodium-glucose co-transporter inhibitors, metformin, sulfonylureas, and thiazolidinediones. These drugs have pleiotropic effects on glucose metabolism and different actions complementary to those of insulin-this Review reports the effects of these drugs on glycaemic control, glucose variability, hypoglycaemia, insulin requirements, and bodyweight. Existing studies are of short duration with few participants; evidence for the efficacy of concomitant treatments is scarce and largely clinically insignificant. A subgroup of patients with type 1 diabetes for whom non-insulin antidiabetic drugs could significantly benefit glycaemic control cannot yet be defined, but we suggest that obese patients prone to hypoglycaemia and patients with residual β-cell function are populations of interest for future trials.

Changes in Characteristics and Treatment Patterns of Patients with Newly Diagnosed Type 2 Diabetes in a Large United States Integrated Health System between 2008 and 2013

To assess changes in the clinical characteristics and treatment patterns of patients with newly diagnosed type 2 diabetes (T2D), the electronic health record system at Cleveland Clinic was used to create cross-sectional summaries of all patients with new-onset T2D in 2008 and 2013. Differences between the 2008 and 2013 data sets were assessed after adjusting for age, gender, race, and income. Approximately one-third of patients with newly diagnosed T2D in 2008 and 2013 had an A1C ≥8%, suggesting the continued presence of a delayed recognition of the disease. Patients with newly diagnosed T2D in 2008 were older than those in 2013. Hypertension, cardiovascular disease, and neuropathy were highly prevalent among patients diagnosed with T2D. The prevalence of neuropathy, cerebrovascular disease, and peripheral vascular disease increased from 2008 to 2013. Metformin was the most commonly prescribed antidiabetic medication. Sulfonylurea usage remained unchanged, while use of thiazolidinediones decreased considerably.

Type 2 Diabetes and Metformin Influence on Fracture Healing in an Experimental Rat Model

Persons with diabetes have a greater incidence of fractures compared with persons without diabetes. However, very little published information is available concerning the deleterious effect of late-stage diabetes on osseous structure and bone healing. The purpose of the present study was to evaluate the role of diabetes on fracture healing in a rat femur repair model. Thirty-six lean and diabetic Zucker rats were subdivided into 3 groups: (1) 12 lean rats as the control group; (2) 12 diabetic rats without blood glucose control (DM group); and (3) 12 diabetic rats treated with 300 mg/kg metformin to reduce the blood glucose levels (DM + Met group). Radiographs were taken every week to determine the incidence of bone repair and delayed union. All the rats were killed at 6 weeks after surgery. In both the sham-operated and the fractured and repaired femurs, significant decreases in the fracture-load/weight and marginal decreases in the fracture-load between the lean and DM groups were found. Metformin treatment significantly reduced the blood glucose and body weight 12 days postoperatively. Furthermore, a decrease in the fracture-load and fracture-load/weight in the repaired femurs was found in the DM + Met group. Diabetes impairs bone fracture healing. Metformin treatment reduces the blood glucose and body weight but had an adverse effect on fracture repair in diabetic rats. Further investigations are needed to reveal the mechanisms responsible for the effects of type 2 diabetes mellitus on bone and bone quality and the effect of medications such as metformin might have in diabetic bone in the presence of neuropathy and vascular disease.

PPARγ Antagonist Gleevec Improves Insulin Sensitivity and Promotes the Browning of White Adipose Tissue

Blocking phosphorylation of peroxisome proliferator-activated receptor (PPAR)γ at Ser(273) is one of the key mechanisms for antidiabetes drugs to target PPARγ. Using high-throughput phosphorylation screening, we here describe that Gleevec blocks cyclin-dependent kinase 5-mediated PPARγ phosphorylation devoid of classical agonism as a PPARγ antagonist ligand. In high fat-fed mice, Gleevec improved insulin sensitivity without causing severe side effects associated with other PPARγ-targeting drugs. Furthermore, Gleevec reduces lipogenic and gluconeogenic gene expression in liver and ameliorates inflammation in adipose tissues. Interestingly, Gleevec increases browning of white adipose tissue and energy expenditure. Taken together, the results indicate that Gleevec exhibits greater beneficial effects on both glucose/lipid metabolism and energy homeostasis by blocking PPARγ phosphorylation. These data illustrate that Gleevec could be a novel therapeutic agent for use in insulin resistance and type 2 diabetes.

Bioactive quinone derivatives from the marine brown alga Sargassum thunbergii induce anti-adipogenic and pro-osteoblastogenic activities

BACKGROUND

Health problems related to the lack of bone formation are a major problem for ageing populations in the modern world. As a part of the ongoing trend to develop natural substances that attenuate bone loss in osteoporosis, the effects of the edible brown alga Sargassum thunbergii and its active contents on adipogenic differentiation in 3T3-L1 fibroblasts and osteoblast differentiation in MC3T3-E1 pre-osteoblasts were evaluated.

RESULTS

Treatment with S. thunbergii significantly reduced lipid accumulation and expression of adipogenic differentiation markers such as peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α and sterol regulatory element binding protein 1c. In addition, S. thunbergii successfully enhanced osteoblast differentiation as indicated by increased alkaline phosphatase activity along raised levels of osteoblastogenesis indicators, namely bone morphogenetic protein-2, osteocalcin and collagen type I. Two compounds, sargaquinoic and sargahydroquinoic acid, were isolated from active extract and shown to be active by means of osteogenesis inducement.

CONCLUSION

S. thunbergii could be a source for functional food ingredients for improved treatment of osteoporosis and obesity.

Associations between bone mineral density and urinary phthalate metabolites among post-menopausal women: a cross-sectional study of NHANES data 2005-2010

Bone mineral density (BMD) decreases with age, especially among post-menopausal women. Exposures to endocrine disruptors, such as phthalate diesters, could alter BMD through a variety of unidentified mechanisms. A hypothesis-generating study investigated associations between urinary phthalate metabolites and BMD at the femoral neck and spine in post-menopausal women (n = 480) participating in the National Health and Nutrition Examination Survey, from 2005 to 2010. Mono-ethyl phthalate (MEP), molar sum of low molecular weight metabolites (mono-n-butyl phthalate (MNBP), mono-isobutyl phthalate (MIBP), MEP), molar sum of estrogenic metabolites (MNBP, MIBP, MEP, mono-benzyl phthalate (MBZP)), and an estrogenic equivalency factor were negatively associated with spinal BMD. Some associations were modified by age or BMI. The cross-sectional study design, uncertainty regarding the critical time window of exposure, the potential for exposure misclassification, and residual confounding limit our abilities to draw causal conclusions regarding phthalate metabolites and BMD in post-menopausal women. Future studies should address these limitations.

Cultured Human Periosteum-Derived Cells Can Differentiate into Osteoblasts in a Perioxisome Proliferator-Activated Receptor Gamma-Mediated Fashion via Bone Morphogenetic Protein signaling

The differentiation of mesenchymal stem cells towards an osteoblastic fate depends on numerous signaling pathways, including activation of bone morphogenetic protein (BMP) signaling components. Commitment to osteogenesis is associated with activation of osteoblast-related signal transduction, whereas inactivation of this signal transduction favors adipogenesis. BMP signaling also has a critical role in the processes by which mesenchymal stem cells undergo commitment to the adipocyte lineage. In our previous study, we demonstrated that an agonist of the perioxisome proliferator-activated receptor γ (PPARγ), a master regulator of adipocyte differentiation, stimulates osteoblastic differentiation of cultured human periosteum-derived cells. In this study, we used dorsomorphin, a selective small molecule inhibitor of BMP signaling, to investigate whether BMP signaling is involved in the positive effects of PPARγ agonists on osteogenic phenotypes of cultured human periosteum-derived cells. Both histochemical detection and bioactivity of ALP were clearly increased in the periosteum-derived cells treated with the PPARγ agonist at day 10 of culture. Treatment with the PPARγ agonist also caused an increase in alizarin red S staining and calcium content in the periosteum-derived osteoblasts at 2 and 3 weeks of culture. In contrast, dorsomorphin markedly decreased ALP activity, alizarin red S staining and calcium content in both the cells treated with PPARγ agonist and the cells cultured in osteogenic induction media without PPARγ agonist during the culture period. In addition, the PPARγ agonist clearly increased osteogenic differentiation medium-induced BMP-2 upregulation in the periosteum-derived osteoblastic cells at 2 weeks of culture as determined by quantitative reverse transcriptase polymerase chain reaction (RT-PCR), immunoblotting, and immunocytochemical analyses. Although further study will be needed to clarify the mechanisms of PPARγ-regulated osteogenesis, our results suggest that the positive effects of a PPARγ agonist on the osteogenic phenotypes of cultured human periosteum-derived cells seem to be dependent on BMP signaling.

Effects of diabetes drugs on the skeleton

Type 2 diabetes is associated with increased fracture risk and the mechanisms underlying the detrimental effects of diabetes on skeletal health are only partially understood. Antidiabetic drugs are indispensable for glycemic control in most type 2 diabetics, however, they may, at least in part, modulate fracture risk in exposed patients. Preclinical and clinical data clearly demonstrate an unfavorable effect of thiazolidinediones on the skeleton with impaired osteoblast function and activated osteoclastogenesis. The negative effect of thiazolidinediones on osteoblastogenesis includes decreased activity of osteoblast-specific transcription factors (e.g. Runx2, Dlx5, osterix) and decreased activity of osteoblast-specific signaling pathways (e.g. Wnt, TGF-β/BMP, IGF-1). In contrast, metformin has a positive effect on osteoblast differentiation due to increased activity of Runx2 via the AMPK/USF-1/SHP regulatory cascade resulting in a neutral or potentially protective effect on bone. Recently marketed antidiabetic drugs include incretin-based therapies (GLP-1 receptor agonists, DPP-4 inhibitors) and sodium-glucose co-transporter 2 (SGLT2)-inhibitors. Preclinical studies indicate that incretins (GIP, GLP-1, and GLP-2) play an important role in the regulation of bone turnover. Clinical safety data are limited, however, meta-analyses of trials investigating the glycemic-lowering effect of both, GLP-1 receptor agonists and DPP4-inhibitors, suggest a neutral effect of incretin-based therapies on fracture risk. For SGLT2-inhibitors recent data indicate that due to their mode of action they may alter calcium and phosphate homeostasis (secondary hyperparathyroidism induced by increased phosphate reabsorption) and thereby potentially affect bone mass and fracture risk. Clinical studies are needed to elucidate the effect of SGLT2-inhibitors on bone metabolism. Meanwhile SGLT2-inhibitors should be used with caution in patients with high fracture risk, which is specifically true for the use of thiazolidinediones.

Fracture Risk in Type 2 Diabetes: Current Perspectives and Gender Differences

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of osteoporotic fractures, resulting in disabilities and increased mortality. The pathophysiological mechanisms linking diabetes to osteoporosis have not been fully explained, but alterations in bone structure and quality are well described in diabetic subjects, likely due to a combination of different factors. Insulin deficiency and dysfunction, obesity and hyperinsulinemia, altered level of oestrogen, leptin, and adiponectin as well as diabetes-related complications, especially peripheral neuropathy, orthostatic hypotension, or reduced vision due to retinopathy may all be associated with an impairment in bone metabolism and with the increased risk of fractures. Finally, medications commonly used in the treatment of T2DM may have an impact on bone metabolism and on fracture risk, particularly in postmenopausal women. When considering the impact of hypoglycaemic drugs on bone, it is important to balance their potential direct effects on bone quality with the risk of falling-related fractures due to the associated hypoglycaemic risk. In this review, experimental and clinical evidence connecting bone metabolism and fracture risk to T2DM is discussed, with particular emphasis on hypoglycaemic treatments and gender-specific implications.

Incidence of Fractures in Patients With Type 2 Diabetes in the SAVOR-TIMI 53 Trial

OBJECTIVE

Patients with type 2 diabetes have an increased risk of bone fractures, the predisposing factors for which are unknown. Treatment with thiazolidinediones (TZDs) further increases the incidence of osteoporotic fractures. In the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus-Thrombolysis in Myocardial Infarction 53 (SAVOR-TIMI 53) trial, fractures were considered an adverse event of special interest, and information regarding fractures was collected.

RESEARCH DESIGN AND METHODS

We compared the incidence of fractures among the 8,280 patients who were assigned to treatment with saxagliptin with that in the 8,212 patients who were assigned to placebo. We further analyzed the participants' baseline characteristics and fracture risk.

RESULTS

During a median follow-up of 2.1 years, 241 patients (2.9%) in the saxagliptin group and 240 (2.9%) in the placebo group experienced a fracture (hazard ratio [HR] 1.00 [95% CI 0.83-1.19]). Event rates for fractures were the same in both treatment arms: 14.7 per 1,000 patient-years in the entire population and 14.0 in the on-treatment population (first event only). Fracture risk was similar in patients treated with saxagliptin or placebo across different subgroups defined by race, cardiovascular risk, and renal function. A multivariable Cox regression analysis showed that risk of fracture was associated with female sex (P < 0.0001), longer diabetes duration (P < 0.0001), older age (P = 0.002), major hypoglycemic events (P = 0.01), noncompliance with study drug (P = 0.01), and treatment with TZDs (P = 0.03).

CONCLUSIONS

In a large population of older patients with type 2 diabetes, treatment with saxagliptin was not associated with an increased risk of fractures. The association between longer diabetes duration and increased risk of bone fracture is an intriguing finding.

Effects of pioglitazone and fenofibrate co-administration on bone biomechanics and histomorphometry in ovariectomized rats

Pioglitazone, the peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonist is an effective therapy for type 2 diabetes, but has been associated with increased risk for bone fracture. Preclinical studies suggest that PPAR-α agonists (e.g., fenofibrate) increase bone mineral density/content, although clinical data on bone effects of fibrates are lacking. We investigated the effects of pioglitazone (10 mg/kg/day) and fenofibrate (25 mg/kg/day) on bone strength and bone histomorphometric parameters in osteopenic ovariectomized (OVX) rats. An additional group of rats received a combination of pioglitazone + fenofibrate to mimic the effects of a dual PPAR-α/γ agonist. The study consisted of a 13-week treatment phase followed by a 6-week treatment-free recovery period. Pioglitazone significantly reduced biomechanical strength at the lumbar spine and femoral neck compared with rats administered fenofibrate. Co-treatment with pioglitazone + fenofibrate had no significant effect on bone strength in comparison with OVX vehicle controls. Histomorphometric analysis of the proximal tibia revealed that pioglitazone suppressed bone formation and increased bone resorption at both cancellous and cortical bone sites relative to OVX vehicle controls. In contrast, fenofibrate did not affect bone resorption and only slightly suppressed bone formation. Discontinuation of pioglitazone treatment, both in the monotherapy and in the combination therapy arms, resulted in restoration of bone formation and resorption rates, demonstrating reversibility of effects. The above data support the concept that dual activation of PPAR-γ and PPAR-α attenuates the negative effects of PPAR-γ agonism on bone strength.

Effects of TZD Use and Discontinuation on Fracture Rates in ACCORD Bone Study

CONTEXT

In trials, thiazolidinediones (TZDs) increase fracture risk in women, but the effects of discontinuation are unknown.

OBJECTIVE

The objective was to investigate the effects of TZD use and discontinuation on fractures in women and men.

DESIGN

This was a longitudinal observational cohort study using data from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial bone ancillary study. Duration of TZD use and discontinuation during ACCORD, assessed every 2-4 months at clinic visits, were modeled as time-varying covariates in proportional hazards models for occurrence of first non-spine fracture.

PARTICIPANTS

We studied a total of 6865 participants in ACCORD BONE.

MAIN OUTCOME MEASURES

Main outcome measures were centrally adjudicated non-spine fracture.

RESULTS

Average age was 62.4 (SD, 6.6) years; average duration of diabetes was 11.1 (SD, 7.8) years. Rosiglitazone was used by 74% and pioglitazone by 13% of participants. During a mean follow-up of 4.8 (SD, 1.5) years, 262 men and 287 women experienced at least one non-spine fracture. The fracture rate was higher in women with 1-2 years of TZD use (hazard ratio [HR] = 2.32; 95% confidence interval [CI], 1.49, 3.62) or >2 years of TZD use (HR = 2.01; 95% CI, 1.35, 2.98), compared with no use. The fracture rate was reduced in women who had discontinued TZD use for 1-2 years (HR = 0.57; 95% CI, 0.35, 0.92) or > 2 years (HR = 0.42; 95% CI, 0.24, 0.74) compared with current users. TZD use and discontinuation were not associated with non-spine fractures in men.

CONCLUSIONS

TZD use was associated with increased non-spine fractures in women, but not men, with type 2 diabetes. When women discontinued TZD use, the fracture effects were attenuated.

The effect of thiazolidinediones on bone mineral density and bone turnover: systematic review and meta-analysis

AIMS/HYPOTHESIS

Thiazolidinediones (TZDs) are associated with an increased risk of fracture but the mechanism is unclear. We sought to determine the effect of TZDs on bone mineral density (BMD) and bone turnover markers.

METHODS

PubMed, EMBASE and Cochrane CENTRAL databases were searched from inception until January 2015 for randomised controlled trials comparing TZDs with metformin, sulfonylureas or placebo, and those reporting changes in BMD and/or bone turnover markers. The primary outcome was percentage change in BMD from baseline and results were pooled with random effects meta-analyses.

RESULTS

In all, 18 trials were included in the primary analyses and another two were included in the sensitivity analyses (n = 3,743, 50% women, mean age 56 years, median trial duration 48 weeks). TZDs decreased BMD at the lumbar spine (difference -1.1% [95% CI -1.6, -0.7]; p < 0.0001), total hip (-1.0% [-1.4, -0.6]; p < 0.0001) and forearm (-0.9% [-1.6, -0.3]; p = 0.007). There were statistically non-significant decreases in BMD at the femoral neck (-0.7% [-1.4, 0.0]; p = 0.06) and total body (-0.3% [-0.5, 0.0]; p = 0.08). Five trials (n = 450) showed no statistically significant difference in percentage change in BMD between the TZD group and controls up to 1 year following TZD withdrawal. In 14 trials, the effect of TZD treatment on turnover markers varied considerably between individual studies.

CONCLUSIONS/INTERPRETATION

Treatment with TZDs results in modest bone loss that may not be reversed 1 year after cessation of treatment.

Involvement of Prolyl Hydroxylase Domain Protein in the Rosiglitazone-Induced Suppression of Osteoblast Differentiation

Rosiglitazone is a well-known anti-diabetic drug that increases insulin sensitivity via peroxisome proliferator-activated receptor γ (PPARγ) activation, but unfortunately it causes bone loss in animals and humans. A previous study showed that prolyl hydroxylase domain protein (PHD) plays a role in rosiglitazone-induced adipocyte differentiation. Based on the inverse relationship between adipocyte and osteoblast differentiation, we investigated whether PHD is involved in the effects of rosiglitazone on osteoblast differentiation. Rosiglitazone inhibited osteoblast differentiation in a concentration-dependent manner, and in parallel induced three PHD isoforms (PHD1, 2, and 3). PHD inhibitors and knockdown of each isoform prevented the inhibitory effects of rosiglitazone on osteoblast differentiation and increased the expression of Runx2, a transcription factor essential for osteoblastogenesis. MG-132, a proteasomal inhibitor also prevented the rosiglitazone-induced degradation of Runx2. Furthermore, both increased PHD isoform expressions and reduced osteoblast differentiation by rosiglitazone were prevented by PPARγ antagonists, indicating these effects were mediated via PPARγ activation. In vivo oral administration of rosiglitazone to female ICR mice for 8 weeks reduced bone mineral densities and plasma alkaline phosphatase (ALP) activity, and increased PHD expression in femoral primary bone marrow cells and the ubiquitination of Runx2. Together, this suggests that the rosiglitazone-induced suppression of osteoblast differentiation is at least partly induced via PPARγ-mediated PHD induction and subsequent promotion of the ubiquitination and degradation of Runx2.

Decreased Bone Mineral Density at the Femoral Neck and Lumbar Spine in South Indian Patients with Type 2 Diabetes

BACKGROUND

With prevalence of diabetes in India reaching epidemic proportions and increase in the population of geriatric age group and risks of falls, it is important to understand the effect that diabetes has on bone health.

AIM

The objective was to assess bone mineral density (BMD) of patients with type 2 diabetes mellitus (T2DM) and to study factors contributing to BMD in patients with T2DM.

MATERIALS AND METHODS

This was a prospective cross-sectional study on 150 patients with T2DM (diagnosed at age > 30 years) and an equal number (n=150) of age and sex matched healthy controls from September 2012 to July 2014 at a tertiary care center located in Southern India. BMD was measured at the femoral neck and lumbar spine (L2-L4) by dual energy absorptiometry (DXA) in cases and controls. Serum total calcium, phosphorus and alkaline phosphatase (ALP) and 25-OH- vitamin D3 was measured in patient group.

RESULTS

Mean age (SD) was 51.29 (±8.05) and 51 (±8.3) years in cases and controls, respectively. The femoral neck and lumbar spine BMD was significantly lower in T2DM cases compared to controls. Also the femoral neck and lumbar spine T-score was significantly lower in T2DM cases compared to controls. Femoral neck BMD among male patients with T2DM was significantly lower compared to controls (men). Among women, BMD at femoral neck as well as lumbar spine was significantly lower in cases when compared to controls. Ninety six out of 150 (64%) T2DM cases had Vitamin D values <20 ng/mL. There was weak negative correlation between age of patient, duration of diabetes and HbA1C with femoral neck BMD. There was weak negative correlation between HbA1C and lumbar spine BMD.

CONCLUSION

Indian subjects with type 2 diabetes have significantly lower BMD at both femoral neck and lumbar spine compared to age and sex matched healthy controls. We conclude that osteopenia and osteoporosis are overlooked complications of diabetes. Longitudinal studies are needed to see for actual incidence of fractures among this high risk group.

The effects of diabetes medications on post-operative long bone fracture healing

PURPOSE

Diabetes has long been known to have an impact on bone repair. More recently, however, most diabetic patients receive medications to normalise this hyperglycaemic environment. To date, no studies have investigated the effects of diabetic medications on fracture healing in humans.

METHOD

Patients were identified from two tertiary trauma centres. Inclusion criteria were adult patients having sustained a closed diaphyseal femoral or tibial fracture, treated surgically. Exclusion criteria were open, pathological or peri-prosthetic fractures, and patients having sustained polytrauma. Matched non-diabetic controls were identified, matched for age, sex, fracture classification and osteosynthesis. Output measures were: time to callus first appearance, bridging of involved cortices and time to union, along with the eventual outcome: union/non-union.

RESULTS

A total of 36 (25 males) eligible patients were identified with a control group of 166 patients (138 males). ANOVA demonstrated class of medication to have a significant effect at two of the three time points and on the eventual outcome. Multiple regression analysis also demonstrated significant impact (p = 0.02).

CONCLUSION

All classes of medication demonstrated anti-osteogenic effects compared to the control cohort. Biguanides demonstrated this in contrast to the in vitro evidence to date. Sulphonylureas demonstrated this to a greater extent; however, no in vitro evidence is available for comparison within this class. Clinicians should be aware of these delays in bone healing when treating diabetic patients and aim for optimal blood glucose control until such time as further research can be undertaken.

Glycemic Control with Thiazolidinedione Is Associated with Fracture of T2DM Patients

Objective

Diabetes is a common diseases and a major problem worldwide. Diabetic osteopathy might be elevated in diabetic patients and is usually caused by bone fracture. Several diabetes medications, such as thiazolidinediones (TZDs), could lead to increased risks of fracture.

Methods

We used the nationwide database to identified 32466 patients who had developed type 2 diabetes from 2000 to 2010 as the diabetic cohort and, from that group, we selected 3427 diabetic patients who had developed bone fracture to survey the possible risk factors, includng commonly used diabetes medication.

Results

We found that TZDs might present increased risks for fracture in patients who used it for an extended period (7 to 730 days before the index date), especially in female patients younger than 64 years old, for whom the risk was elevated from a 1.74- to a 2.58-fold odds ratio.

Conclusions

We recommend that clinics follow up with non-osteoporotic female patients younger than 64 years old who are using TZDs, to avoid the associated risks of fracture.

Oral anti-diabetic drugs and fracture risk, cut to the bone: safe or dangerous? A narrative review

Fracture risk is higher in older adults with type 2 diabetes and may be influenced by treatments for diabetes. Oral anti-diabetic drugs have different effects on bone metabolism. The purpose of this review is to describe the effects of these drugs on bone metabolism and fracture risk. Osteoporosis is a progressive skeletal disorder that is characterized by compromised bone strength and increased risk of fracture. This condition has become an important global health problem, affecting approximately 200 million people worldwide. Another chronic and highly prevalent condition is diabetes mellitus, which affects more than 380 million people; both type 1 and type 2 diabetes are risk factors for fracture. Type 2 diabetes, in particular, is associated with impaired bone strength, although it is characterized by normal or elevated bone mineral density. Several therapeutic strategies are available to achieve the best outcomes in the management of diabetes mellitus but these have different effects on bone metabolism. The purpose of this narrative review is to describe the effects of oral hypoglycemic agents (metformin, sulfonylureas, thiazolidinediones, meglitinides, dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists and sodium-dependent glucose transporter 2 inhibitors) on bone metabolism and on the risk of developing fragility fractures in patients with type 2 diabetes. Both diabetes and osteoporosis represent a significant burden in terms of healthcare costs and quality of life. It is very important to choose therapies for diabetes that ensure good metabolic control whilst preserving skeletal health.

n-3 polyunsaturated fatty acids stimulate osteoclastogenesis through PPARγ-mediated enhancement of c-Fos expression, and suppress osteoclastogenesis through PPARγ-dependent inhibition of NFkB activation

n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been reported to suppress osteoclastogenesis in vivo. In this study, the effect of PUFAs on receptor for activation of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis was examined using bone marrow-derived monocytes/macrophage precursor cells (BMMs) or bone marrow cells (BMCs) in vitro. EPA and DHA stimulated the osteoclastic differentiation of BMMs, but n-6 PUFAs, linoleic acid and arachidonic acid had no effect. The stimulation of osteoclastogenesis of BMMs by EPA and DHA was associated with enhancement of the gene expressions of c-Fos, tartrate-resistant acid phosphatase, cathepsin K and peroxisome proliferator-activated receptor-γ (PPARγ) and the protein levels of c-Fos, PPARγ and nuclear factor of activated T cells, cytoplasmic, calcineurin-dependent-1 (NFATc1). The PPARγ agonists, rosiglitazone and GW1929, also stimulated the osteoclastogenesis of BMMs. The PPARγ antagonists, T0070907 and GW9662, inhibited the stimulations of osteoclastogenesis and c-Fos expression by EPA or DHA. However, EPA and DHA inhibited the osteoclastogenesis in BMCs including BMMs and mesenchymal stem cells (MSCs). This inhibition was associated with suppression of the expression of RANKL and nuclear factor-κB (NFκB)-regulating genes, cyclooxygenase 2, TNFα and IL-6 in BMCs and MSCs. The agonists and antagonists of PPARγ showed that the inhibitions of NFκB transcriptional activity and osteoclastogenesis by EPA and DHA were PPARγ-dependent. These results suggest that EPA and DHA directly act on BMMs and stimulate osteoclastogenesis through enhancing c-Fos expression mediated by PPARγ but suppress osteoclastogenesis through the PPARγ-dependent inhibition of NFκB activation of MSCs in BMCs.

The impact of diabetes and diabetes medications on bone health

Patients with type 2 diabetes mellitus (T2DM) have an increased risk of fragility fractures despite increased body weight and normal or higher bone mineral density. The mechanisms by which T2DM increases skeletal fragility are unclear. It is likely that a combination of factors, including a greater risk of falling, regional osteopenia, and impaired bone quality, contributes to the increased fracture risk. Drugs for the treatment of T2DM may also impact on the risk for fractures. For example, thiazolidinediones accelerate bone loss and increase the risk of fractures, particularly in older women. In contrast, metformin and sulfonylureas do not appear to have a negative effect on bone health and may, in fact, protect against fragility fracture. Animal models indicate a potential role for incretin hormones in bone metabolism, but there are only limited data on the impact of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 agonists on bone health in humans. Animal models also have demonstrated a role for amylin in bone metabolism, but clinical trials in patients with type 1 diabetes with an amylin analog (pramlintide) have not shown a significant impact on bone metabolism. The effects of insulin treatment on fracture risk are inconsistent with some studies showing an increased risk and others showing no effect. Finally, although there is limited information on the latest class of medications for the treatment of T2DM, the sodium-glucose co-transporter-2 inhibitors, these drugs do not seem to increase fracture risk. Because diabetes is an increasingly common chronic condition that can affect patients for many decades, further research into the effects of agents for the treatment of T2DM on bone metabolism is warranted. In this review, the physiological mechanisms and clinical impact of diabetes treatments on bone health and fracture risk in patients with T2DM are described.

Promoting effect of triterpenoid compound from Agrimonia pilosa Ledeb on preadipocytes differentiation via up-regulation of PPARγ expression

Background:

Agrimonia Pilosa Ledeb (APL), a traditional Chinese medicine, has been reported a variety of biological activities, including treating T2DM.

Objective:

Triterpenoid compound (TC) was collected from APL. The aim of this study was to investigate the effects of TC on 3T3-L1 preadipocytes differentiation and genes related to differentiation and IR.

Materials and Methods:

Column chromatography was used to collect TC from ALP. 3T3-L1 cell differentiation was induced typically in the presence of various concentrations of TC or pioglitazone. Oil red O staining and measurement of intracellular TG content were performed on the seventh day of differentiation. Then quantitative polymerase chain reaction (Q-PCR) was used to test the expressions of three transcription factors (PPARγ, CCAAT enhancer binding protein-α (C/EBP-α), and sterol regulatory element-binding protein 1 (SREBP-1)) and the target genes of PPARγ including glucose transporter (GLUT4), lipoprotein lipase (LPL), fat acid binding protein (AP2), and adiponectin in 3T3-L1 cells.

Results:

At the concentration of 5, 25 and 125 μg/mL, TC significantly promoted triglyceride accumulation. Further study showed that TC could promote the expression of PPARγ, C/EBPα and ADD1/SREBP1 significantly at 125 μg/mL. As for downstream genes controlled by PPARγ, TC at 25 and 125 μg/mL could significantly promote the expression of GLUT4 and adiponectin. However, the expression of aP2 related to lipid metabolism and adiposity in the TC group was significantly lower than that in the pioglitazone group.

Conclusion:

TC could promote preadipocytes differentiation through activating PPARγ and downstream controlled genes. TC has the ideal insulin sensitization with lower adipogenic action than classical TZDs in vitro. So TC from Agrimonia Pilosa Ledeb has a good prospect as a natural drug for IR and T2DM.

Diabetes medications and bone

Type 2 diabetes mellitus (T2DM) is a common chronic disease that may be associated with an increased risk of fracture. Evidence that thiazolidinediones (TZDs) increase fracture risk in women with T2DM has focused attention on the skeletal effects of treatments for diabetes. Only scant, low-quality evidence is available for non-TZD diabetes medications and bone health, but it suggests that there are no clinically important effects.

[Pharmacogenic osteoporosis beyond cortisone. Proton pump inhibitors, glitazones and diuretics]

BACKGROUND

[corrected] There are many drugs which can cause osteoporosis or at least favor its initiation. The effect of hormones and drugs with antihormonal activity, such as glucocorticoids and aromatase inhibitors, on initiation of osteoporosis is well known. In addition, proton pump inhibitors, glitazones and diuretics also influence the formation of osteoporosis.

MATERIAL AND METHODS

The results of currently available studies on the correlation between proton pump inhibitors, glitazones and diuretics on formation of osteoporosis were evaluated and summarized.

RESULTS

Proton pump inhibitors and glitazones increase the risk for osteoporotic fractures. Loop diuretics may slightly increase fracture risk, whereas thiazides were shown to be osteoprotective by reducing fracture probability on a relevant scale.

CONCLUSION

Proton pump inhibitors should not be prescribed without serious consideration and then only as long as necessary. Alternatively, the administration of the less effective H2 antagonists should be considered when possible due to the reduction of acid secretion. Because the long-term intake of thiazides is associated with a clinically relevant reduction in the risk of fractures and they are economic and well-tolerated, prescription can be thoroughly recommended within the framework of differential diagnostic considerations in an appropriate clinical context. The briefly increased risk of falling immediately after starting diuretic therapy is the only point which needs to be considered.