Effect of Dipeptidyl Peptidase-4 Inhibitors on Bone Metabolism and the Possible Underlying Mechanisms

Bone Loss in Diabetes Mellitus: Diaporosis

The objective of this review is to examine the connection between osteoporosis and diabetes, compare the underlying causes of osteoporosis in various forms of diabetes, and suggest optimal methods for diagnosing and assessing fracture risk in diabetic patients. This narrative review discusses the key factors contributing to the heightened risk of fractures in individuals with diabetes, as well as the shared elements impacting the treatment of both diabetes mellitus and osteoporosis. Understanding the close link between diabetes and a heightened risk of fractures is crucial in effectively managing both conditions. There are several review articles of meta-analysis regarding diaporosis. Nevertheless, no review articles showed collected and well-organized medications of antidiabetics and made for inconvenient reading for those who were interested in details of drug mechanisms. In this article, we presented collected and comprehensive charts of every antidiabetic medication which was linked to fracture risk and indicated plausible descriptions according to research articles.

Exploring the anti-osteoporosis potential of Petroselinum crispum (Mill.) Fuss extract employing experimentally ovariectomized rat model and network pharmacology approach

One of the most prevalent secondary osteoporosis is ovariectomy-induced osteoporosis. Parsley (Petroselinum crispum) has potent estrogenic and antioxidant properties and was used traditionally in the treatment of amenorrhea and dysmenorrhea. The present study aimed to characterize parsley leaf extract (PLE) employing RP-HPLC-MS-MS/MS-based method and possible protective effect in ovariectomized (OVX)-induced osteoporosis in rats was assessed. Rats were randomly assigned into SHAM group, OVX group, PLE + OVX group (150 mg/kg/day, p.o), and estradiol benzoate (E2) + OVX group (30 μg/kg/day, s.c). After eight weeks following ovariectomy, biomarkers of bone strength, bone resorption, oxidative stress and histopathology were carried out. A network pharmacology approach investigated the key targets and potential mechanisms by of PLE metabolites against osteoporosis using databases: PubChem, BindingDB server, DisGeNET, ShinyGO, and KEGG Pathway. Moreover, FunRich 3.1.3, Cytoscape 3.10.0, and MOE 2019.0102 softwares were used for network pharmacology analysis and molecular docking studies. Flavones and hydroxycinnamic acid derivatives were predominant among 38 metabolites in PLE. It significantly restored bone strength and bone resorption biomarkers, osteocalcin (OST), oxidative stress biomarkers and histopathological alterations. The employed network pharmacology approach revealed that 14 primary target genes were associated with decreasing the severity of osteoporosis. Molecular docking revealed that cGMP-PKG signaling pathway has the highest fold enrichment and its downstream PDE5A. Luteolin, diosmetin, and isorhamnetin derivatives affected mostly osteoporosis targets. PLE exhibited protective action against ovariectomy-induced osteoporosis in rats and may be a promising therapy for premenopausal bone loss. cGMP-PKG signaling pathway could be a promising target for PLE in treating osteoporosis.

Exploring the Interplay between Vitamin D, Insulin Resistance, Obesity and Skeletal Health

Vitamin D (ViD), plays an important role in calcium absorption and bone mineralization, is associated with bone mineral density. Severe deficiency in ViD has long been linked to conditions such as rickets in children and osteomalacia in adults, revealing its substantial role in skeletal health. Additionally, investigations show an existing interconnection between ViD and insulin resistance (Ins-R), especially in patients with type 2 diabetes mellitus (T2DM). Obesity, in conjunction with Ins-R, may augment the risk of osteoporosis and deterioration of skeletal health. This review aims to examine recent studies on the interplay between ViD, Ins-R, obesity, and their impact on skeletal health, to offer insights into potential therapeutic strategies. Cochrane Library, Google Scholar, and Pubmed were searched to investigate relevant studies until December 2023. Current research demonstrates ViD's impact on pancreatic β-cell function, systemic inflammation, and insulin action regulation. Our findings highlight an intricate association between ViD, Ins-R, obesity, and skeletal health, providing a perspective for the prevention and/or treatment of skeletal disorders in patients with obesity, Ins-R, and T2DM.

Non-Specific Inhibition of Dipeptidyl Peptidases 8/9 by Dipeptidyl Peptidase 4 Inhibitors Negatively Affects Mesenchymal Stem Cell Differentiation

DPP4 may play a relevant role in MSC differentiation into osteoblasts or adipocytes. Dipeptidyl peptidase 4 (DPP4) inhibitors (DPP4i), such as sitagliptin and vildagliptin, are used as antidiabetic drugs. However, vildagliptin is not a specific DPP4i and also inhibits DPP8/9, which is involved in energy metabolism and immune regulation. The aim of this study is to evaluate how sitagliptin, vildagliptin or 1G244 (a DPP8/9 specific inhibitor) may influence cell viability, as well as osteogenic and adipogenic differentiation in human mesenchymal stem cells (MSC). Viability, apoptosis, osteoblastogenesis and adipogenesis markers, as well as protein synthesis of β-catenin, were studied in MSC cultures induced to differentiate into osteoblasts or adipocytes in the presence or absence of sitagliptin, vildagliptin or 1G244. The two tested DPP4i did not affect MSC viability, but 1G244 significantly decreased it in MSC and osteoblast-induced cells. Additionally, 1G244 and vildagliptin inhibited osteogenesis and adipogenesis, unlike sitagliptin. Therefore, inhibition of DPP4 did not affect MSC viability and differentiation, whereas inhibition of DPP8/9 negatively affected MSC. To the best of our knowledge, these results show for the first time that DPP8/9 have an important role in the viability and differentiation of human MSC. This data can be considered for human clinical use of drugs affecting DPP8/9 activity.

Effects of Linagliptin and Pioglitazone on Fracture Healing in an Experimental Type 2 Diabetes Rat Model

AIM

Our study aimed to examine the effects of Linagliptin, Pioglitazone, and their combination on fracture healing in a diabetes rat femur fracture model.

MATERIAL AND METHODS

Type 2 diabetes mellitus (T2DM) induced rats were randomly divided into four groups: non-treated diabetes group (TD), Pioglitazone group (P), Linagliptin group (L), and Pioglitazone and Linagliptin group (PL). Daily oral dosage of pioglitazone (10 mg/kg/day), linagliptin (10 mg/kg/day), and their combination were administered. Femur fractures were stabilized intramedullary. At weeks 2 and 6, rats were sacrificed for evaluation radiologically, biomechanically, histopathologically, histomorphometrically, and immunohistochemically.

RESULTS

Flexural strength of the L and PL groups were significantly higher compared to the P group. The highest healing score was in the L group and lowest in the P group, while the highest inflammation score was in the P group and lowest in the L group. A cluster of differentiation (CD) CD 34 reactivity was highest in the L group and lowest in the PL group.

CONCLUSION

Linagliptin treatment significantly increased histological healing scores, callus volume, biomechanical strength, and vascularity, however, minimized the inflammatory process, which was increased by pioglitazone. The combination of linagliptin and pioglitazone restored BMD and increased biomechanical strength. Linagliptin monotherapy is rarely indicated; hence, T2DM patients with a high risk of bone fractures can be considered for combined therapy of pioglitazone and linagliptin.

Risk of fracture caused by anti-diabetic drugs in individuals with type 2 diabetes: A network meta-analysis

AIMS

Diabetes is associated with increased risk of fracture. This study aims to evaluate the correlation between anti-diabetic agents and fracture risk in patients with type 2 diabetes.

METHODS

Literature research was conducted using PubMed, Embase, and ClinicalTrials.gov. Search-term included "type 2 diabetes," "fracture," "randomized controlled trial," and seven kinds of anti-diabetic agents. Random-effect models established fractures in the follow-up period as the primary outcome. A network meta-analysis was performed to compare available treatments within a single Bayesian analytical framework.

RESULTS

A total of 191,361 patients were included in 161 studies, with 2916 fractures. DPP-4i (risk ratio [RR] 1.76 [95 % confidence interval (CI) 1.21-2.55]), SGLT-2i (RR 1.5 [95 % CI 1.05-2.16]) and placebo (RR 1.44 [95 % CI 1.04-1.98]) increased fracture risk when compared to GLP1-RA. GLP1-RA (RR 0.5 [95 % CI 0.31-0.79]) and SU (RR 0.56 [95 % CI 0.41-0.77]) provided greater protection against fracture than TZD. DPP-4i increased fracture risk when compared to SU (RR 1.55 [95 % CI 1.08-2.22]), and was comparable in effect to TZD.

CONCLUSIONS

GLP1-RA offered better protection against fracture than placebo. Insulin and SU had effects comparable with GLP1-RA. SU offered greater protection against fractures than TZD and DPP-4i. SGLT-2i increased risk of fracture when compared to GLP1-RA.

Dipeptidyl peptidase-4 inhibitors attenuates osteoporosis in patients with diabetes: A nationwide, retrospective, matched-cohort study in Taiwan

BACKGROUND

Patients with diabetes have a relatively high risk of fracture due to osteoporosis. However, the risk of osteoporosis associated with the use of oral hypoglycemic drugs and dipeptidyl peptidase-4 inhibitor (DPP-4i) by patients with diabetes is unclear. This study aimed to explore the effect of DPP-4i on the risk of osteoporosis in Taiwanese patients with type 2 diabetes mellitus (T2DM).

METHODS

This study enrolled 6339 patients on DPP-4i (DPP-4i group) and 25 356 patients without DPP-4i (non-DPP-4i group). They were matched by 1:4 propensity score matching, using confounding variables including sex, age, comorbidities, medication, and index year. Cox proportional hazards analysis was used to compare hospitalization and mortality during an average follow-up period of 7 years.

RESULTS

The mean age of patients in the two groups was 66 years. Men were slightly higher in number (51.79%) than women. At the end of the follow-up period, 113 (0.36%) patients had osteoporosis, of which 15 (0.24%) were in the case group and 98 (0.39%) in the control group. The risk of all-cause osteoporosis was significantly lower in the DPP-4i group than in the non-DPP-4i group (adjusted hazard ratio [HR] 0.616; 95% confidence interval [CI] 0.358-0.961; p = 0.011). Kaplan-Meier analysis showed that the preventive effect on osteoporosis was positively correlated with the cumulative dose of DPP-4i (log-rank, p = 0.039) with the class effect.

CONCLUSION

Compared with not using DPP-4i, the use of DPP-4i in Taiwanese T2DM patients was associated with a lower risk of osteoporosis due to the class effect, and the preventive effect was dose-dependent. However, larger prospective studies are needed to validate this finding and to explore the possible mechanism of the preventive effect of DPP-4i.

Influence of Dipeptidyl Peptidase-4 (DPP4) on Mesenchymal Stem-Cell (MSC) Biology: Implications for Regenerative Medicine - Review

Dipeptidyl peptidase IV (DPP4) is a ubiquitous protease that can be found in membrane-anchored or soluble form. Incretins are one of the main DPP4 substrates. These hormones regulate glucose levels, by stimulating insulin secretion and decreasing glucagon production. Because DPP4 levels are high in diabetes, DPP4 inhibitor (DPP4i) drugs derived from gliptin are widespread used as hypoglycemic agents for its treatment. However, as DPP4 recognizes other substrates such as chemokines, growth factors and neuropeptides, pleiotropic effects have been observed in patients treated with DPP4i. Several of these substrates are part of the stem-cell niche. Thus, they may affect different physiological aspects of mesenchymal stem-cells (MSC). They include viability, differentiation, mobilization and immune response. MSC are involved in tissue homeostasis and regeneration under both physiological and pathological conditions. Therefore, such cells and their secretomes have a high clinical potential in regenerative medicine. In this context, DPP4 activity may modulate different aspects of MSC regenerative capacity. Therefore, the aim of this review is to analyze the effect of different DPP4 substrates on MSC. Likewise, how the regulation of DPP4 activity by DPP4i can be applied in regenerative medicine. That includes treatment of cardiovascular and bone pathologies, cutaneous ulcers, organ transplantation and pancreatic beta-cell regeneration, among others. Thus, DPP4i has an important clinical potential as a complement to therapeutic strategies in regenerative medicine. They involve enhancing the differentiation, immunomodulation and mobilization capacity of MSC for regenerative purposes.

Effect of Dipeptidyl Peptidase-4 Inhibitors on Bone Health in Patients with Type 2 Diabetes Mellitus

Patients with type 2 diabetes (T2DM) have a higher risk of bone fracture even when bone mineral density (BMD) values are normal. The trabecular bone score (TBS) was recently developed and used for evaluating bone strength in various diseases. We investigated the effect of DPP-4 inhibitors on bone health using TBS in patients with T2DM. This was a single-center, retrospective case-control study of 200 patients with T2DM. Patients were divided into two groups according to whether they were administered a DPP-4 inhibitor (DPP-4 inhibitor group vs. control group). Parameters related to bone health, including BMD, TBS, and serum markers of calcium homeostasis, were assessed at baseline and after one year of treatment. We found TBS values increased in the DPP-4 group and decreased in the control, indicating a significant difference in delta change between them. The BMD increased in both groups, with no significant differences in delta change between the two groups observed. Serum calcium and 25-hydroxy vitamin D3 increased only in the DPP-4 inhibitor group, while other glycemic parameters did not show significant differences between the two groups. Treatment with DPP-4 inhibitors was associated with favorable effects on bone health evaluated by TBS in patients with T2DM.

Poor bone matrix quality: What can be done about it?

PURPOSE OF THE REVIEW

Bone's ability to withstand load resisting fracture and adapting to it highly depends on the quality of its matrix and its regulators. This review focuses on the contribution of bone quality to fracture resistance and possible therapeutic targets for skeletal fragility in aging and disease.

RECENT FINDINGS

The highly organized, hierarchical composite structure of bone extracellular matrix together with its (re)modeling mechanisms and microdamage dynamics determines its stiffness, strength, and toughness. Aging and disease affect the biological processes regulating bone quality, thus resulting in defective extracellular matrix and bone fragility. Targeted therapies are being developed to restore bone's mechanical integrity. However, their current limitations include low tissue selectivity and adverse side effects. Biological and mechanical insights into the mechanisms controlling bone quality, together with advances in drug delivery and studies in animal models, will accelerate the development and translation to clinical application of effective targeted-therapeutics for bone fragility.

Efficacy / safety balance of DPP-4 inhibitors versus SGLT2 inhibitors in elderly patients with type 2 diabetes

Dipeptidyl peptidase-4 inhibitors (DPP-4is) and sodium-glucose cotransporter type 2 inhibitors (SGLT2is) offer new options for the oral management of type 2 diabetes mellitus (T2DM), with the advantage in the elderly population to be devoid of a high risk of hypoglycaemia. SGLT2is have also shown benefits regarding cardiovascular (heart failure) and renal protection, including in patients with T2DM aged ≥ 65 years while DPP-4is have only proved cardiovascular and renal safety without superiority compared with placebo. The glucose-lowering efficacy of the two pharmacological classes is almost similar including in older patients with T2DM. However, the tolerance and safety profile may be highly different and overall more favourable with DPP-4is than with SGLT2is. Some adverse events have been reported with SGLT2is which may be more prevalent or severe in older patients than in younger patients. The present comprehensive review focuses on the benefit/risk balance in the elderly population with T2DM by comparing the profile of DPP-4is and SGLT2is regarding the following potential issues: metabolic disorders (hypoglycaemia and diabetic ketoacidosis); cardiac and vascular issues (atheromatous cardiovascular disease, heart failure, volume reduction hypotension, and lower limb amputations); renal endpoints including acute renal injury; risk of infections; digestive disorders; bone and skin adverse events; and cancer risk. Both DPP-4is and SGLT2is have their own advantages and disadvantages. Personalised treatment is recommended based upon the efficacy/safety profile of each drug class and individual patient characteristics that may be markedly different among the heterogeneous population of older individuals with T2DM.

Effects of Incretin-Related Diabetes Drugs on Bone Formation and Bone Resorption

Patients with type 2 diabetes have an increased risk of fracture compared to the general population. Glucose absorption is accelerated by incretin hormones, which induce insulin secretion from the pancreas. The level of the incretin hormone, glucagon-like peptide-1 (GLP-1), shows an immediate postprandial increase, and the circulating level of intact GLP-1 is reduced rapidly by dipeptidyl peptidase-4 (DPP-4)-mediated inactivation. Therefore, GLP-1 receptor agonists and DPP-4 inhibitors are effective in the treatment of type 2 diabetes. However, these incretin-related diabetic agents have been reported to affect bone metabolism, including bone formation and resorption. These agents enhance the expression of bone markers, and have been applied to improve bone quality and bone density. In addition, they have been reported to suppress chronic inflammation and reduce the levels of inflammatory cytokine expression. Previously, we reported that these incretin-related agents inhibited both the expression of inflammatory cytokines and inflammation-induced bone resorption. This review presents an overview of current knowledge regarding the effects of incretin-related diabetes drugs on osteoblast differentiation and bone formation as well as osteoclast differentiation and bone resorption. The mechanisms by which incretin-related diabetes drugs regulate bone formation and bone resorption are also discussed.

Trelagliptin stimulates osteoblastic differentiation by increasing runt-related transcription factor 2 (RUNX2): a therapeutic implication in osteoporosis

Osteoporosis, an aging-associated bone metabolic disease, is affecting millions of people worldwide. The deregulated process of osteoblastic differentiation has been linked with the progression of osteoporosis. Trelagliptin is a long-acting inhibitor of DPP-4 used for the management of type 2 diabetes mellitus. However, it is unknown whether Trelagliptin possesses a beneficial effect in osteoblastic differentiation. Interestingly, we found that treatment with Trelagliptin enhanced differentiation and promoted the mineralization of MC3T3-E1 cells. Firstly, Trelagliptin increased the activity of alkaline phosphatase (ALP) and promoted osteoblastic calcium deposition. Additionally, treatment with Trelagliptin upregulated ALP, osteocalcin (OCN), osteopontin (OPN), and bone morphogenetic protein-2 (BMP-2). Notably, Trelagliptin increased RUNX2, a major regulator of osteoblastic differentiation. Mechanistically, Trelagliptin upregulated the levels of p-AMPKα. Blockage of AMPK with compound C abolished the effects of Trelagliptin in RUNX2 and osteoblastic differentiation, suggesting the involvement of AMPK. Our findings suggest that Trelagliptin might possess a potential for the treatment of osteoporosis.

Glucose-Lowering Drugs and Fracture Risk-a Systematic Review

PURPOSE OF REVIEW

Diabetes mellitus (DM) is associated with increased fracture risk. The aim of this systematic review was to examine the effects of different classes of glucose-lowering drugs on fracture risk in patients with type 2 DM. The heterogeneity of the included studies did not allow formal statistical analyses.

RECENT FINDINGS

Sixty studies were included in the review. Metformin, dipeptidylpeptidase-IV inhibitors, glucagon-like peptide-1 receptor agonists, and sodium-glucose cotransporter 2-inhibitors do not appear to increase fracture risk. Results for insulin and sulphonylureas were more disparate, although there may be an increased fracture risk related to hypoglycemia and falls with these treatments. Glitazones were consistently associated with increased fracture risk in women, although the evidence was sparser in men. New glucose-lowering drugs are continuously being developed and better understanding of these is leading to changes in prescription patterns. Our findings warrant continued research on the effects of glucose-lowering drugs on fracture risk, elucidating the class-specific effects of these drugs.

Effect of a DPP-4 Inhibitor on Orthodontic Tooth Movement and Associated Root Resorption

Objectives

Dipeptidyl peptidase-4 (DPP-4) inhibitors are used as a treatment for type 2 diabetes mellitus and have also recently been applied to enhance bone quality and density, and increase the expression of bone markers. This study aimed to investigate the effect of a DPP-4 inhibitor on orthodontic tooth movement (OTM) and related root resorption in a mouse model.

Materials and Methods

Mice were randomly divided into three groups: those undergoing OTM with the addition of a DPP-4 inhibitor (30 μg), those undergoing OTM and receiving phosphate-buffered saline (PBS), and those without force loading (control group). OTM was achieved by means of a nickel-titanium closed coil spring that moved the first molar in a mesial direction for 12 days. The distance of OTM was measured using silicone impression. Maxillae were removed for histological analysis or real-time PCR analysis.

Results

The distance of OTM and the number of osteoclasts were significantly decreased after administration of the DPP-4 inhibitor, which also significantly suppressed the number of odontoclasts and root resorption after OTM. Furthermore, the mRNA expression of tumour necrosis factor-α (TNF-α) and the receptor activator of nuclear factor kappa-B ligand (RANKL) were decreased in DPP-4 inhibitor-treated mice compared with those receiving PBS and control animals.

Conclusion

The DPP-4 inhibitor inhibited tooth movement and associated root resorption by blocking the formation of osteoclasts and odontoclasts, respectively. It also appeared to inhibit osteoclastogenesis and odontoclastogenesis by suppressing the expression of TNF-α and/or RANKL.

Anagliptin stimulates osteoblastic cell differentiation and mineralization

Osteoporosis is a common debilitating bone disease characterized by loss of bone mass and degradation of the bone architecture, which is primarily driven by dysregulated differentiation of mesenchymal stem cells into bone-producing osteoblasts. Osteoblasts contribute to bone formation by secreting various proteins that guide the deposition of bone extracellular matrix, such as alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). The Wnt/β-catenin pathway is widely recognized as a regulator of bone mass and is required to maintain bone homeostasis. Hormones have long been recognized as playing a key role in bone metabolism, and in recent years, growing evidence has shown that diabetes is a risk factor for osteoporosis. In the present study, we investigated the effects of the antidiabetic drug anagliptin on the differentiation and mineralization of osteoblasts induced by osteogenic medium. Anagliptin promotes insulin production via inhibition of dipeptidyl peptidase IV (DPP-4), an enzyme that targets the incretin hormone glucagon-like peptide 1 (GLP-1) for degradation. Our findings show that anagliptin significantly increases the differentiation of MSCs into osteoblasts via activation of RUNX2. Anagliptin significantly increased matrix deposition and mineralization by osteoblasts, as evidenced by elevated levels of ALP, OCN, OPN, and BMP-2. We further demonstrate that anagliptin activates the canonical and noncannonical Wnt signaling pathways and that silencing of Wnt/β-catenin signaling completely abolished the effects of anagliptin. Thus, anagliptin might be a safe, effective therapy for type II diabetes that might show promise as a therapy against osteoporosis.

The Interplay Between Bone and Glucose Metabolism

The multiple endocrine functions of bone other than those related to mineral metabolism, such as regulation of insulin sensitivity, glucose homeostasis, and energy metabolism, have recently been discovered. In vitro and murine studies investigated the impact of several molecules derived from osteoblasts and osteocytes on glucose metabolism. In addition, the effect of glucose on bone cells suggested a mutual cross-talk between bone and glucose homeostasis. In humans, these mechanisms are the pivotal determinant of the skeletal fragility associated with both type 1 and type 2 diabetes. Metabolic abnormalities associated with diabetes, such as increase in adipose tissue, reduction of lean mass, effects of hyperglycemia per se, production of the advanced glycation end products, diabetes-associated chronic kidney disease, and perturbation of the calcium-PTH-vitamin D metabolism, are the main mechanisms involved. Finally, there have been multiple reports of antidiabetic drugs affecting the skeleton, with differences among basic and clinical research data, as well as of anti-osteoporosis medication influencing glucose metabolism. This review focuses on the aspects linking glucose and bone metabolism by offering insight into the most recent evidence in humans.

An update on therapies for the treatment of diabetes-induced osteoporosis

Introduction: Currently, 424 million people aged between 20 and 79 years worldwide are diabetic. More than 25% of adults aged over 65 years in North America have Type 2 diabetes mellitus (DM). Diabetes-induced osteoporosis (DM-OS) is caused by chronic hyperglycemia, advanced glycated end products and oxidative stress. The increase in the prevalence of DM-OS has prompted researchers to develop new biological therapies for the management of DM-OS. Areas covered: This review covered the current and novel biological agents used in the management of DM-OS. Data were retrieved from PubMed, Scopus, American Diabetes Association and International Osteoporosis Foundation websites, and ClinicalTrials.gov. The keywords for the search included: DM, osteoporosis, and management. Expert opinion: Several biological molecules have been examined in order to find efficient drugs for the treatment of DM-OS. These biological agents include anti-osteoporosis drugs: net anabolics (parathyroid hormone/analogs, androgens, calcilytics, anti-sclerostin antibody), net anti-resorptive osteoporosis drugs (calcitonin, estrogen, selective estrogen receptor modulators, bisphosphonates, RANKL antibody) and anti-diabetic drugs (alpha glucosidase inhibitors, sulfonylureas, biguanides, meglitinides, thiazolidinediones, GLP-1 receptor agonists, dipeptidylpeptidase-4 inhibitors, sodium glucose co-transporter-2 inhibitors, insulin). Biological medications that effectively decrease hyperglycemia and, at the same time, maintain bone health would be an ideal drug/drug combination for the treatment of DM-OS.

Diabetes pharmacotherapy and effects on the musculoskeletal system

Persons with type 1 or type 2 diabetes have a significantly higher fracture risk than age-matched persons without diabetes, attributed to disease-specific deficits in the microarchitecture and material properties of bone tissue. Therefore, independent effects of diabetes drugs on skeletal integrity are vitally important. Studies of incretin-based therapies have shown divergent effects of different agents on fracture risk, including detrimental, beneficial, and neutral effects. The sulfonylurea class of drugs, owing to its hypoglycemic potential, is thought to amplify the risk of fall-related fractures, particularly in the elderly. Other agents such as the biguanides may, in fact, be osteo-anabolic. In contrast, despite similarly expected anabolic properties of insulin, data suggests that insulin pharmacotherapy itself, particularly in type 2 diabetes, may be a risk factor for fracture, negatively associated with determinants of bone quality and bone strength. Finally, sodium-dependent glucose co-transporter 2 inhibitors have been associated with an increased risk of atypical fractures in select populations, and possibly with an increase in lower extremity amputation with specific SGLT2I drugs. The role of skeletal muscle, as a potential mediator and determinant of bone quality, is also a relevant area of exploration. Currently, data regarding the impact of glucose lowering medications on diabetes-related muscle atrophy is more limited, although preclinical studies suggest that various hypoglycemic agents may have either aggravating (sulfonylureas, glinides) or repairing (thiazolidinediones, biguanides, incretins) effects on skeletal muscle atrophy, thereby influencing bone quality. Hence, the therapeutic efficacy of each hypoglycemic agent must also be evaluated in light of its impact, alone or in combination, on musculoskeletal health, when determining an individualized treatment approach. Moreover, the effect of newer medications (potentially seeking expanded clinical indication into the pediatric age range) on the growing skeleton is largely unknown. Herein, we review the available literature regarding effects of diabetes pharmacotherapy, by drug class and/or by clinical indication, on the musculoskeletal health of persons with diabetes.

DPP-4 inhibitor impedes lipopolysaccharide-induced osteoclast formation and bone resorption in vivo

OBJECTIVES

Dipeptidyl peptidase 4 (DPP-4) inhibition is a new therapeutic strategy for type 2 diabetic patients. DPP-4 has been reported to enhance inflammation. However, the effect of DPP-4 inhibition on inflammation remains unknown. Lipopolysaccharide (LPS) is a strong inducer of inflammation and osteoclast formation. In this study, we investigated in vivo effects of DPP-4 inhibition on LPS-induced osteoclast formation and bone resorption, as well as in vitro effects of DPP-4 inhibition on RANKL-induced osteoclastogenesis and TNF-α-induced osteoclastogenesis.

METHODS

LPS with or without a DPP-4 inhibitor was subcutaneously injected into mouse calvaria for 5 days. Histological sections of calvaria were stained for tartrate-resistant acid phosphatase, and osteoclast numbers were determined. The ratio of calvaria bone resorption was evaluated via microfocal computed tomography reconstruction images.

RESULTS

Osteoclast number and bone resorption were significantly lower in mice that underwent LPS and DPP-4 inhibitor co-administration than in those that underwent LPS administration alone. Moreover, RANKL, TNF-α, and M-CSF expression was reduced in the LPS and DPP-4 inhibitor co-administration group. In vitro, there were no direct effects of DPP-4 inhibitor or DPP-4 on RANKL- and TNF-α-induced osteoclastogenesis, or on LPS-induced RANKL expression in stromal cells. Nevertheless, macrophages from LPS and DPP-4 inhibitor co-administered mice exhibited lower TNF-α expression than macrophages from LPS-only mice. Notably, TNF-α expression was not reduced in LPS and DPP-4 inhibitor co-treated macrophages in vitro, compared with macrophages treated with LPS alone.

The safety of gliptins : updated data in 2018

INTRODUCTION

Dipeptidyl peptidase-4 inhibitors (DPP-4is) are generally considered as glucose-lowering agents with a safe profile in type 2 diabetes.

AREAS COVERED

An updated review of recent safety data from randomised controlled trials, observational studies, meta-analyses, pharmacovigilance reports regarding alogliptin, linagliptin, saxagliptin, sitagliptin, and vildagliptin, with a special focus on risks of hypoglycemia, pancreatitis and pancreatic cancer, major cardiovascular events, hospitalisation for heart failure and other new safety issues, such as bone fractures and arthralgia. The safety of DPP-4i use in special populations, elderly patients, patients with renal impairment, liver disease or heart failure, will also be discussed.

EXPERT OPINION

The good tolerance/safety profile of DPP-4is has been largely confirmed, including in more fragile populations, with no gastrointestinal adverse effects and a minimal risk of hypoglycemia. DPP-4is appear to be associated with a small increased incidence of acute pancreatitis in placebo-controlled trials, although most observational studies are reassuring. Most recent studies with DPP-4is do not confirm the increased risk of hospitalisation for heart failure reported with saxagliptin in SAVOR-TIMI 53, but further post-marketing surveillance is still recommended. New adverse events have been reported such as arthralgia, yet a causal relationship remains unclear.