Dipeptidyl peptidase-4 independent cardiac dysfunction links saxagliptin to heart failure

Sudden cardiac death due to ventricular arrhythmia in diabetes mellitus: A bench to bedside review

Diabetes mellitus (DM) confers an increased risk of sudden cardiac death (SCD) independent of its associated cardiovascular comorbidities. DM induces adverse structural, electrophysiologic, and autonomic cardiac remodeling that can increase one's risk of ventricular arrhythmias and SCD. Although glycemic control and prevention of microvascular and macrovascular complications are cornerstones in the management of DM, they are not adequate for the prevention of SCD. In this narrative review, we describe the contribution of DM to the pathophysiologic mechanism of SCD beyond its role in atherosclerotic cardiovascular disease and heart failure. On the basis of this pathophysiologic framework, we outline potential preventive and therapeutic strategies to mitigate the risk of SCD in this population of high-risk patients.

Shedding Light on Cardiac Excitation: In Vitro and In Silico Analysis of Native Ca2+ Channel Activation in Guinea Pig Cardiomyocytes Using Organic Photovoltaic Devices

OBJECTIVE

This study aims to explore the potential of organic electrolytic photocapacitors (OEPCs), an innovative photovoltaic device, in mediating the activation of native voltage-gated Cav1.2 channels (ICa,L) in Guinea pig ventricular cardiomyocytes.

METHODS

Whole-cell patch-clamp recordings were employed to examine light-triggered OEPC mediated ICa,L activation, integrating the channel's kinetic properties into a multicompartment cell model to take intracellular ion concentrations into account. A multidomain model was additionally incorporated to evaluate effects of OEPC-mediated stimulation. The final model combines external stimulation, multicompartmental cell simulation, and a patch-clamp amplifier equivalent circuit to assess the impact on achievable intracellular voltage changes.

RESULTS

Light pulses activated ICa,L, with amplitudes similar to voltage-clamp activation and high sensitivity to the L-type Ca2+ channel blocker, nifedipine. Light-triggered ICa,L inactivation exhibited kinetic parameters comparable to voltage-induced inactivation.

CONCLUSION

OEPC-mediated activation of ICa,L demonstrates their potential for nongenetic optical modulation of cellular physiology potentially paving the way for the development of innovative therapies in cardiovascular health. The integrated model proves the light-mediated activation of ICa,L and advances the understanding of the interplay between the patch-clamp amplifier and external stimulation devices.

SIGNIFICANCE

Treating cardiac conduction disorders by minimal-invasive means without genetic modifications could advance therapeutic approaches increasing patients' quality of life compared with conventional methods employing electronic devices.

Influence of Gegenqinlian decoction on pharmacokinetics and pharmacodynamics of saxagliptin in type 2 diabetes mellitus rats

Gegenqinlian decoction (GQD) is a classic prescription of traditional Chinese medicine (TCM), which originated from Shanghanlun. The combination of GQD and hypoglycemic drugs (saxagliptin, Sax, metformin) is often used to treat Type 2 diabetes mellitus (T2DM) in TCM clinics. However, the herb-drug interactions (HDIs) between GQD and hypoglycemic drugs are still unclear. In order to determine the safety of the combination, we assessed the influences of GQD on the pharmacokinetics and pharmacodynamics of Sax in T2DM rats. The plasma concentration of Sax (5 mg/kg) pretreated with GQD (freeze-dried powder, 1.35 g/kg) or not was determined by high-performance liquid chromatography (HPLC), and pharmacokinetics parameters were calculated. The influence of GQD on the pharmacodynamics of Sax was investigated by detecting the levels of weight, (see abbreviations list) OGTT, TC, TG, LDL-C, HDL-C, FBG, FINS, HOMA-IR, QUICKI, AST, ALT, and the liver coefficient. The Cmax , AUC0-t ,and AUC0-∞ of Sax increased significantly in the combination group whether in normal or T2DM rats. The results of pharmacodynamics showed that the weight of rats in each treatment group increased. FBG, TC, TG, LDL-C, and HOMA-IR decreased, HDL-C, FINS, and QUICKI increased significantly (p < 0.05) compared with the model control group. The result showed that the combination of GQD and Sax could not only improve the hypoglycemic effect but also increase the plasma exposure of Sax. The potential HDIs between GQD and Sax should be taken into consideration in clinics. Moreover, for the complexity of the human compared with experimental animals, as well as genetic differences, the in-depth study should be carried out to assess the uniformity of the pharmacokinetics and pharmacodynamics between rats and humans.

Lipopolysaccharide-induced sepsis impairs M2R-GIRK signaling in the mouse sinoatrial node

Sepsis has emerged as a global health burden associated with multiple organ dysfunction and 20% mortality rate in patients. Numerous clinical studies over the past two decades have correlated the disease severity and mortality in septic patients with impaired heart rate variability (HRV), as a consequence of impaired chronotropic response of sinoatrial node (SAN) pacemaker activity to vagal/parasympathetic stimulation. However, the molecular mechanism(s) downstream to parasympathetic inputs have not been investigated yet in sepsis, particularly in the SAN. Based on electrocardiography, fluorescence Ca2+ imaging, electrophysiology, and protein assays from organ to subcellular level, we report that impaired muscarinic receptor subtype 2-G protein-activated inwardly-rectifying potassium channel (M2R-GIRK) signaling in a lipopolysaccharide-induced proxy septic mouse model plays a critical role in SAN pacemaking and HRV. The parasympathetic responses to a muscarinic agonist, namely IKACh activation in SAN cells, reduction in Ca2+ mobilization of SAN tissues, lowering of heart rate and increase in HRV, were profoundly attenuated upon lipopolysaccharide-induced sepsis. These functional alterations manifested as a direct consequence of reduced expression of key ion-channel components (GIRK1, GIRK4, and M2R) in the mouse SAN tissues and cells, which was further evident in the human right atrial appendages of septic patients and likely not mediated by the common proinflammatory cytokines elevated in sepsis.

Cardiovascular effectiveness of glucagon-like peptide 1 receptor agonists versus dipeptidyl peptidase-4 inhibitors in type 2 diabetes: A meta-analysis based on propensity score-matched studies

Glucagon-like peptide 1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-4 inhibitors (DPP-4i) are two novel classes of hypoglycemic agents. The relative cardiovascular effectiveness between these two drug classes in patients with type 2 diabetes (T2D) is unestablished due to the absence of large cardiovascular outcome trials directly comparing DPP-4i with GLP-1RA. We aimed to incorporate large propensity score-matched cohort studies to conduct a meta-analysis, to determine the relative effectiveness of GLP-1RA versus DPP-4i on cardiovascular endpoints in T2D patients. Compared to DPP-4i, GLP-1RA was associated with the significantly lower risks of major adverse cardiovascular events [MACE] (HR 0.76, 95% CI 0.63-0.92), cardiovascular mortality (HR 0.59, 95% CI 0.37-0.95), myocardial infarction (HR 0.89, 95% CI 0.80-0.98), stroke (HR 0.86, 95% CI 0.76-0.96), and all-cause mortality (HR 0.63, 95% CI 0.42-0.96) in T2D patients; whereas these two drug classes had the similar risk of hospitalization for heart failure [HHF] (HR 0.95, 95% CI 0.77-1.16). Meta-regression analyses showed that six factors (i.e., mean age, female proportion, cardiovascular disease proportion, heart failure proportion, and the proportions of receiving metformin and insulin at baseline) did not significantly affect the effects of GLP-1RA on MACE and HHF (P ≥ 0.076). This meta-analysis provides the direct evidence regarding the relative cardiovascular effectiveness of GLP-1RA versus DPP-4i from real-world studies, and its findings suggest that among T2D patients GLP-1RA should be considered in preference to DPP-4i as for preventing atherosclerotic cardiovascular events and death in clinical practice.

Comparative Safety of Dipeptidyl Peptidase-4 Inhibitors and Sudden Cardiac Arrest and Ventricular Arrhythmia: Population-Based Cohort Studies

In vivo studies suggest that arrhythmia risk may be greater with less selective dipeptidyl peptidase-4 inhibitors, but evidence from population-based studies is missing. We aimed to compare saxagliptin, sitagliptin, and linagliptin with regard to risk of sudden cardiac arrest (SCA)/ventricular arrhythmia (VA). We conducted high-dimensional propensity score (hdPS) matched, new-user cohort studies. We analyzed Medicaid and Optum Clinformatics separately. We identified new users of saxagliptin, sitagliptin (both databases), and linagliptin (Optum only). We defined SCA/VA outcomes using emergency department and inpatient diagnoses. We identified and then controlled for confounders via a data-adaptive, hdPS approach. We generated marginal hazard ratios (HRs) via Cox proportional hazards regression using a robust variance estimator while adjusting for calendar year. We identified the following matched comparisons: saxagliptin vs. sitagliptin (23,895 vs. 96,972) in Medicaid, saxagliptin vs. sitagliptin (48,388 vs. 117,383) in Optum, and linagliptin vs. sitagliptin (36,820 vs. 78,701) in Optum. In Medicaid, use of saxagliptin (vs. sitagliptin) was associated with an increased rate of SCA/VA (adjusted HR (aHR), 2.01, 95% confidence interval (CI) 1.24-3.25). However, in Optum data, this finding was not present (aHR, 0.79, 95% CI 0.41-1.51). Further, we found no association between linagliptin (vs. sitagliptin) and SCA/VA (aHR, 0.65, 95% CI 0.36-1.17). We found discordant results regarding the association between SCA/VA with saxagliptin compared with sitagliptin in two independent datasets. It remains unclear whether these findings are due to heterogeneity of treatment effect in the different populations, chance, or unmeasured confounding.

Hypochlorite-Modified LDL Induces Arrhythmia and Contractile Dysfunction in Cardiomyocytes

Neutrophil-derived myeloperoxidase (MPO) and its potent oxidant, hypochlorous acid (HOCl), gained attention as important oxidative mediators in cardiac damage and dysfunction. As cardiomyocytes generate low-density lipoprotein (LDL)-like particles, we aimed to identify the footprints of proatherogenic HOCl-LDL, which adversely affects cellular signalling cascades in various cell types, in the human infarcted myocardium. We performed immunohistochemistry for MPO and HOCl-LDL in human myocardial tissue, investigated the impact of HOCl-LDL on electrophysiology and contractility in primary cardiomyocytes, and explored underlying mechanisms in HL-1 cardiomyocytes and human atrial appendages using immunoblot analysis, qPCR, and silencing experiments. HOCl-LDL reduced ICa,L and IK1, and increased INaL, leading to altered action potential characteristics and arrhythmic events including early- and delayed-afterdepolarizations. HOCl-LDL altered the expression and function of CaV1.2, RyR2, NCX1, and SERCA2a, resulting in impaired contractility and Ca2+ homeostasis. Elevated superoxide anion levels and oxidation of CaMKII were mediated via LOX-1 signaling in HL-1 cardiomyocytes. Furthermore, HOCl-LDL-mediated alterations of cardiac contractility and electrophysiology, including arrhythmic events, were ameliorated by the CaMKII inhibitor KN93 and the INaL blocker, ranolazine. This study provides an explanatory framework for the detrimental effects of HOCl-LDL compared to native LDL and cardiac remodeling in patients with high MPO levels during the progression of cardiovascular disease.

CARDIOVASCULAR EFFECTS OF NON-INSULIN GLUCOSE-LOWERING AGENTS: A COMPREHENSIVE REVIEW OF TRIAL EVIDENCE AND POTENTIAL CARDIOPROTECTIVE MECHANISMS

Type 2 diabetes mellitus (T2DM) is highly prevalent and associated with a 2-fold increased mortality, mostly explained by cardiovascular diseases. Trial evidence on older glucose-lowering agents such as metformin and sulfonylureas is limited in terms of cardiovascular efficacy. Since 2008, after rosiglitazone was observed to increase the risk of myocardial infarction and heart failure (HF), cardiovascular outcome trials (CVOT) have been required by regulators for licensing new glucose-lowering agents. In the following CVOTs, dipeptidyl peptidase 4 inhibitors (DPP4i) have been shown to be safe but not to improve morbidity/mortality, except for saxagliptin which increased the risk of HF. Several glucagon-like peptide-1 receptor agonists (GLP1-Ra) and sodium-glucose cotransporter-2 inhibitors (SGLT2i) have been demonstrated to reduce the risk of cardiovascular morbidity and mortality. SGLT2i have shown a class effect for the reduction in risk of HF events in patients with T2DM, leading to trials testing their efficacy/safety in HF regardless of T2DM. In the DAPA-HF and the EMPEROR-Reduced trials dapagliflozin and empagliflozin, respectively, improved cardiovascular mortality/morbidity in patients with HF and reduced ejection fraction (HFrEF), with and without T2DM. Therefore, these drugs are now key part of HFrEF pharmacotherapy. In the SOLOIST-WHF, sotagliflozin reduced cardiovascular mortality/morbidity in patients with T2DM and a recent acute episode of HF regardless of EF. The DELIVER and the EMPEROR-Preserved are testing dapagliflozin and empagliflozin, respectively, in patients with HF with mildly reduced and preserved EF. A strong renal protective role of SGLT2i has also emerged in trials enrolling patients with and without T2DM.

Frontiers in Bioengineering and Biotechnology: Plant Nanoparticles for Anti-Cancer Therapy

Naturally occurring viral nanomaterials have gained popularity owing to their biocompatible and biodegradable nature. Plant virus nanoparticles (VNPs) can be used as nanocarriers for a number of biomedical applications. Plant VNPs are inexpensive to produce, safe to administer and efficacious as treatments. The following review describes how plant virus architecture facilitates the use of VNPs for imaging and a variety of therapeutic applications, with particular emphasis on cancer. Examples of plant viruses which have been engineered to carry drugs and diagnostic agents for specific types of cancer are provided. The drug delivery system in response to the internal conditions is known as stimuli response, recently becoming more applicable using plant viruses based VNPs. The review concludes with a perspective of the future of plant VNPs and plant virus-like particles (VLPs) in cancer research and therapy.

Dipeptidyl peptidase 4 inhibitors attenuate cardiac ischaemia-reperfusion injury in rats with diabetes mellitus type 2

The aim of our study was to assess and compare the effects of dipeptidyl peptidase 4 (DPP4) inhibitors, saxagliptin and sitagliptin, on metabolic control of disease and cardiac function in rats with diabetes mellitus type 2 (T2DM). This research would provide novel understanding into the potentially protective effects of DPP4 inhibitors in helping salvage of the heart exposed to ischaemia-reperfusion (I-R) injury. Forty-eight Wistar albino rats were randomly divided into four groups: CTRL, Control healthy group; T2DM, rats with T2DM; T2DM + Sit, rats with T2DM treated with 0.6 mg/kg of sitagliptin; T2DM + Sax, rats with T2DM treated with 0.45 mg/kg of saxagliptin for 3 weeks. At the end of the protocol, in vivo cardiac function was assessed by echocardiography, while in the blood samples glucose and insulin were determined. Additionally, ex vivo heart function was estimated on a model of I-R injury using Langendorff apparatus. Immunohistochemical analysis was used to determine the degree of myocardial apoptosis and necrosis, while DPP4 staining was performed to assess the cardiac DPP4 expression. Data were analyzed using a one-way analysis of variance (ANOVA) and the post hoc Bonferroni test for multiple comparisons. Improved glycoregulation was noticed in rats that received DPP4 inhibitors compared to untreated diabetic rats (P < .05). Moreover, better in vivo systolic function was observed in rats treated with both DPP4 inhibitors as evidenced by an increase in fractional shortening when compared to T2DM (P < .05). Most parameters of cardiac function in treated rats remained unaltered during reperfusion, thus suggesting that both drugs protected myocardium during flow restoration. Better effects on coronary circulation were achieved after sitagliptin application. Additionally, both DPP4 inhibitors showed similar potential to attenuate cardiac necrosis and apoptosis. Saxagliptin and sitagliptin might be efficient in preserving myocardial function and morphology in ex vivo induced I-R cardiac injury in rats with T2DM.

Linagliptin prevents left ventricular stiffening by reducing titin cleavage and hypophosphorylation

The metabolic syndrome (MetS) is an escalating problem worldwide, causing left ventricular stiffening, an early characteristic of diastolic dysfunction for which no treatment exists. As diastolic dysfunction and stiffening in MetS patients are associated with increased circulating dipeptidyl peptidase-4 (DPP-4) levels, we investigated whether the clinically approved DPP-4 inhibitor linagliptin reduces left ventricular stiffness in MetS-induced cardiac disease. Sixteen-week-old obese ZSF1 rats, displaying the MetS and left ventricular stiffness, received linagliptin-supplemented or placebo diet for four weeks. Linagliptin significantly reduced obesity, hyperlipidaemia, and hyperglycaemia and improved left ventricular relaxation. This improved relaxation was related to decreased cardiac fibrosis and cardiomyocyte passive stiffness (Fpassive ). The reduced Fpassive was the result of titin isoform switching from the stiff N2B to the more flexible N2BA and increased phosphorylation of total titin and specifically its N2Bus region (S4080 and S3391). Importantly, DPP-4 directly cleaved titin in vitro, resulting in an increased Fpassive , which was prevented by simultaneous administration of linagliptin. In conclusion, linagliptin improves left ventricular stiffness in obese ZSF1 rats by preventing direct DPP4-mediated titin cleavage, as well as by modulating both titin isoform levels and phosphorylation. Reducing left ventricular stiffness by administering linagliptin might prevent MetS-induced early diastolic dysfunction in human.

Novel Antidiabetic Agents: Cardiovascular and Safety Outcomes

BACKGROUND

Concerns of elevated cardiovascular risk with some anti-diabetic medications warranted trials on the cardiovascular outcome to demonstrate cardiovascular safety of newly marketed anti-diabetic drugs. Although these trials were initially designed to evaluate safety, some of these demonstrated significant cardiovascular benefits.

PURPOSE OF REVIEW

We reviewed the cardiovascular and safety outcomes of novel antidiabetic agents in patients with type 2 diabetes and established cardiovascular disease or at high risk of it. We included the outcomes of safety trials, randomized controlled trials, meta-analysis, large cohort studies, and real-world data, which highlighted the cardiovascular profile of DPP-4is, GLP-1RAs and SGLT-2is.

CONCLUSION

Although DPP-4is demonstrated non-inferiority to placebo, gaining cardiovascular safety, as well market authorization, SGLT-2is and most of the GLP-1RAs have shown impressive cardiovascular benefits in patients with T2D and established CVD or at high risk of it. These favorable effects of novel antidiabetic agents on cardiovascular parameters provide novel therapeutic approaches in medical management, risk stratification and prevention.

Changing Fields-Diabetes Medications Invading the Cardiovascular Space

Cardiovascular disease (CVD) remains the leading cause of mortality in patients with type 2 diabetes, and treatment strategies that impact cardiovascular (CV) outcomes in this population is an area of growing interest. Pharmacologic agents that reduce CVD risk have been developed, and data supporting their use have grown extensively. Glucagon-like peptide 1 agonists and sodium-glucose cotransporter 2 inhibitors when added to metformin therapy provide the most CV benefit and should be considered in most patients. Data available suggest that sulfonylureas should be avoided in patients at risk for CVD and if a thiazolidinedione is utilized, pioglitazone may be preferred. When selecting an agent, the potential benefit, risk, and cost of each agent should be considered prior to initiation. The purpose of this review is to summarize the literature surrounding the CV effects of antidiabetic agents and to provide practical guidance on their use in patients with type 2 diabetes and CVD.

Dipeptidyl peptidase 4 inhibitors in the treatment of type 2 diabetes mellitus

Dipeptidyl peptidase 4 inhibitors (DPP4i) have been available for treating type 2 diabetes mellitus since 2006. Although they are a diverse group, DPP4i are all small, orally available molecules that interact with the catalytic site of DPP4 without disturbing any of its other known functions, including its effects on the immune system. DPP4i have no intrinsic glucose-lowering activity, so their efficacy as anti-diabetic agents is related directly to their ability to inhibit DPP4 activity and is mediated through the effects of the substrates they protect. Of these, the incretin hormone, glucagon-like peptide 1, is probably the most important. As the effects of glucagon-like peptide 1 are glucose-dependent, the risk of hypoglycaemia with DPP4i is low. Class effects, which are directly related to the mechanism of action, are common to all DPP4i; these include their overall good safety profile and tolerability, as well as their efficacy in improving glycaemic control, but also, potentially, a small increased risk of acute pancreatitis. Compound-specific effects are those related to their differing chemistries and/or pharmacokinetic profiles. These compound-specific effects could affect the way in which individual DPP4i are used therapeutically and potentially explain off-target adverse effects, such as hospitalization for heart failure, which is seen only with one DPP4i. Overall, DPP4i have a favourable therapeutic profile and are safe and effective in the majority of patients with type 2 diabetes mellitus.

Non-insulin antihyperglycaemic drugs and heart failure: an overview of current evidence from randomized controlled trials

Type 2 diabetes mellitus (T2DM) is highly prevalent in the general population and especially in patients with heart failure (HF). It is not only a risk factor for incident HF, but is also associated with worse outcomes in prevalent HF. Therefore, antihyperglycaemic management in patients at risk of or with established HF is of importance to reduce morbidity/mortality. Following revision of the drug approval process in 2008 by the Food and Drug Administration and European Medicines Agency, several cardiovascular outcome trials on antihyperglycaemic drugs have recently investigated HF endpoints. Signals of harm in terms of increased risk of HF have been identified for thiazolidinediones and the dipeptidyl peptidase 4 inhibitor saxagliptin, and therefore, these drugs are not currently recommended in HF. Sulfonylureas also have an unfavourable safety profile and should be avoided in patients at increased risk of/with HF. Observational studies have assessed the use of metformin in patients with HF, showing potential safety and potential survival/morbidity benefits. Overall use of glucagon-like peptide 1 receptor agonists has not been linked with any clear benefit in terms of HF outcomes. Sodium-glucose cotransporter protein 2 inhibitors (SGLT2i) have consistently shown to reduce risk of HF-related outcomes in T2DM with and without HF and are thus currently recommended to lower risk of HF hospitalization in T2DM. Recent findings from the DAPA-HF trial support the use of dapagliflozin in patients with HF with reduced ejection fraction and, should ongoing trials with empagliflozin, sotagliflozin, and canagliflozin prove efficacy, will pave the way for SGLT2i as HF treatment regardless of T2DM.

Dipeptidyl peptidase-4 inhibitors as new tools for cardioprotection

Previous studies have demonstrated that individuals with type 2 diabetes mellitus (T2DM) have a two- to fourfold propensity to develop cardiovascular disease (CVD) than nondiabetic population, making CVD a major cause of death and disability among people with T2DM. The present treatment options for management of diabetes propose the earlier and more frequent use of new antidiabetic drugs that could control hyperglycaemia and reduce the risk of cardiovascular events. Findings from basic and clinical studies pointed out DPP-4 inhibitors as potentially novel pharmacological tools for cardioprotection. There is a growing body of evidence suggesting that these drugs have ability to protect the heart against acute ischaemia-reperfusion injury as well as reduce the size of infarction. Consequently, the prevention of degradation of the incretin hormones by the use of DPP-4 inhibitors represents a new strategy in the treatment of patients with T2DM and reduction of CV events in these patients. Here, we discuss the cardioprotective effects of DPP-4 inhibitors as well as proposed pathways that these hypoglycaemic agents target in the cardiovascular system.

Effect of Dipeptidyl Peptidase 4 Inhibitors on Cardiovascular Events in Type-2 Diabetes Patients with Renal Impairment: A Systematic Review and Meta-analysis

BACKGROUND

Recent studies suggested that the increased risk of heart failure by DPP-4 inhibitors may have an interconnection with patients' baseline eGFR. We decided to investigate the effect of DPP-4 inhibitors and the degree of renal function on cardiovascular (CV) safety in type 2 diabetes (T2D) patients.

MATERIALS AND METHODS

Systemic search of literature that examined the DPP-4 inhibitors and reported cardiovascular outcomes in diabetes patients with renal impairment were performed. Studies were examined for inclusion criteria: Randomized controlled trials with reduced renal function taking DPP-4 inhibitors alone or in combination with other anti-diabetes agents reporting evaluable CV events for at least 24 weeks.

RESULT

Analysis of four CV outcome studies (11,789 patients with eGFR ≤60 ml/min/1.73m²) did not find any increase in primary composite endpoints with DPP-4 inhibitors in patients stratified by baseline renal function. Rate of hospitalization due to heart failure (hHF) is found to be non-inferior to placebo group in patients with renal insufficiency (RR 1.07; 95% CI, 0.96-1.20 P = 0.26). In moderate renal dysfunction, there is a significant increase in heart failure risk compared to placebo. (RR 1.27; 95% CI, 1.033 -1.5 8; P = 0.024).

CONCLUSION

Treatment with DPP-4 inhibitors did not affect the risk of cardiovascular events regardless of baseline renal function, however, an increase in the risk of hHF in moderate renal function in T2D patients with high CV risk merits careful consideration. Further research would be necessitated to reach definitive conclusion to understand the effect of declining renal function on CV safety of DPP-4 inhibitors.

Impact of vildagliptin on vascular and fibrotic remodeling of myocardium in experimental diabetic cardiomyopathy

The effect of dipeptidyl peptidase-4 inhibitors (DPP-4is) on myocardium in diabetic cardiomyopathy (DCM) remains a matter of debate. In the current study we investigated the effect of vildagliptin (VILDA, 3 mg/kg/d) on myocardium of DCM focusing on coronary microcirculation as well as on endothelial stress markers (ICAM and VCAM). We divided animals equally into 4 groups; nondiabetic (ND), VILDA per se, DCM and DCM + VILDA and their myocardium was evaluated for the fibro-vascular remodeling immunohistochemically as well as for molecular changes. VILDA had reversed the histological changes occurred in DCM including the disintegration, degeneration, and steatosis of cardiomyocytes with disappearance of the edema fluid. In addition VILDA significantly increased (p < 0.05) density of the coronary microcirculation and relieved endothelial stress. However, it did not prevent the development of fibrotic remodeling including the increased collagen deposition and the significantly upregulated (p < 0.05) corresponding genes. Therefore VILDA may have a positive impact on the microvascular remodeling, but not on fibrotic changes, in DCM.

GLP-1 analog liraglutide-induced cardiac dysfunction due to energetic starvation in heart failure with non-diabetic dilated cardiomyopathy

Background

Glucagon-like peptide-1 (GLP-1) reduces cardiovascular events in diabetic patients; however, its counter-protective effects have also been suggested in patients with heart failure and the clear explanation for its mechanisms have not yet been offered.

Methods

The effects of GLP-1 analog on cardiac function and energy metabolism, especially glycemic and lipid metabolisms were elucidated using non-diabetic J2N-k hamsters which showed spontaneous dilated cardiomyopathy. J2N-k hamsters were treated with PBS (HF group), low-dose (HF-L group) or high-dose liraglutide (HF-H group).

Results

In failing heart, GLP-1 analog exerted further deteriorated cardiac function (e.g. positive and negative dP/dt; p = 0.01 and p = 0.002, respectively) with overt fibrosis and cardiac enlargement (heart/body weight, 5.7 ± 0.2 in HF group versus 7.6 ± 0.2 in HF-H group; p = 0.02). The protein expression of cardiac muscles indicated the energy starvation status. Indirect calorimetry showed that failing hearts consumed higher energy and carbohydrate than normal hearts; moreover, this tendency was augmented by GLP-1 analog administration. Upon 10% glucose solution loading with GLP-1 analog administration (HF-H-G group) as complementary experiments, the cardiac function and fibrosis significantly ameliorated, whereas carbohydrate utilization augmented further and lipid utilization reduced more. The prognosis of HF-H-G group also significantly improved (p = 0.025).

Conclusions

Glucagon-like peptide-1 analog caused the relative but desperate shortage of glycemic energy source for the failing cardiac muscles and it may restrict ATP synthesis, resulting in cardiac function deterioration. Therefore, appropriate energy supply and amount of carbohydrate intake should be carefully considered when administrating incretin-related drugs to patients with heart failure.

Linagliptin Effects on Heart Failure and Related Outcomes in Individuals With Type 2 Diabetes Mellitus at High Cardiovascular and Renal Risk in CARMELINA

BACKGROUND

Individuals with type 2 diabetes mellitus are at increased risk for heart failure (HF), particularly those with coexisting atherosclerotic cardiovascular disease and/or kidney disease. Some but not all dipeptidyl peptidase-4 inhibitors have been associated with increased HF risk. We performed secondary analyses of HF and related outcomes with the dipeptidyl peptidase-4 inhibitor linagliptin versus placebo in CARMELINA (The Cardiovascular and Renal Microvascular Outcome Study With Linagliptin), a cardiovascular outcomes trial that enrolled participants with type 2 diabetes mellitus and atherosclerotic cardiovascular disease and/or kidney disease.

METHODS

Participants in 27 countries with type 2 diabetes mellitus and concomitant atherosclerotic cardiovascular disease and/or kidney disease were randomized 1:1 to receive once daily oral linagliptin 5 mg or placebo, on top of standard of care. All hospitalization for HF (hHF), cardiovascular outcomes, and deaths were prospectively captured and centrally adjudicated. In prespecified and post hoc analyses of HF and related events, Cox proportional hazards models adjusting for region and baseline history of HF were used. Recurrent hHF events were analyzed using a negative binomial model. In a subset of participants with left ventricular ejection fraction captured within the year before randomization, HF-related outcomes were assessed in subgroups stratified by left ventricular ejection fraction > or ≤50%.

RESULTS

CARMELINA enrolled 6979 participants (mean age, 65.9 years; estimated glomerular filtration rate, mL/min per 1.73m2; hemoglobin A1c, 8.0%; 62.9% men; diabetes mellitus duration, 14.8 years), including 1873 (26.8%) with a history of HF at baseline. Median follow-up was 2.2 years. Linagliptin versus placebo did not affect the incidence of hHF (209/3494 [6.0%] versus 226/3485 [6.5%], respectively; hazard ratio [HR], 0.90; 95% CI, 0.74-1.08), the composite of cardiovascular death/hHF (HR, 0.94; 95% CI, 0.82-1.08), or risk for recurrent hHF events (326 versus 359 events, respectively; rate ratio, 0.94; 95% CI, 0.75-1.20). There was no heterogeneity of linagliptin effects on hHF by history of HF at baseline, baseline estimated glomerular filtration rate or urine albumin-creatinine ratio, or prerandomization left ventricular ejection fraction.

CONCLUSIONS

In a large, international cardiovascular outcome trial in participants with type 2 diabetes mellitus and concomitant atherosclerotic cardiovascular disease and/or kidney disease, linagliptin did not affect the risk of hHF or other selected HF-related outcomes, including among participants with and without a history of HF, across the spectrum of kidney disease, and independent of previous left ventricular ejection fraction.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT01897532.

Physiology and Pharmacology of DPP-4 in Glucose Homeostasis and the Treatment of Type 2 Diabetes

Dipeptidyl peptidase-4 (DPP-4), also known as the T-cell antigen CD26, is a multi-functional protein which, besides its catalytic activity, also functions as a binding protein and a ligand for a variety of extracellular molecules. It is an integral membrane protein expressed on cells throughout the body, but is also shed from the membrane and circulates as a soluble protein in the plasma. A large number of bioactive molecules can be cleaved by DPP-4 in vitro, but only a few of these have been demonstrated to be physiological substrates. One of these is the incretin hormone, glucagon-like peptide-1 (GLP-1), which plays an important role in the maintenance of normal glucose homeostasis, and DPP-4 has been shown to be the key enzyme regulating its biological activity. This pathway has been targeted pharmacologically through the development of DPP-4 inhibitors, and these are now a successful class of anti-hyperglycaemic agents used to treat type 2 diabetes (T2DM). DPP-4 may additionally influence metabolic control via its proteolytic effect on other regulatory peptides, but it has also been reported to affect insulin sensitivity, potentially mediated through its non-enzymatic interactions with other membrane proteins. Given that altered expression and activity of DPP-4 are associated with increasing body mass index and hyperglycaemia, DPP-4 has been proposed to play a role in linking obesity and the pathogenesis of T2DM by functioning as a local mediator of inflammation and insulin resistance in adipose and hepatic tissue. As well as these broader systemic effects, it has also been suggested that DPP-4 may be able to modulate β-cell function as part of a paracrine system involving GLP-1 produced locally within the pancreatic islets. However, while it is evident that DPP-4 has the potential to influence glycaemic control, its overall significance for the normal physiological regulation of glucose homeostasis in humans and its role in the pathogenesis of metabolic disease remain to be established.

Saxagliptin but Not Sitagliptin Inhibits CaMKII and PKC via DPP9 Inhibition in Cardiomyocytes

Some oral anti-hyperglycemic drugs, including gliptins that inhibit dipeptidyl peptidase 4 (DPP4), have been linked to the increased risk of heart failure (HF) in type-2 diabetic patients. While the cardiovascular safety trial, TECOS, revealed no link between sitagliptin and the risk of HF, a substantial 27% increase in the hospitalization for HF was observed in type-2 diabetic patients treated with saxagliptin within the SAVOR-TIMI 53 trial. A previous in vitro study revealed that saxagliptin impairs the Ca2+/calmodulin-dependent protein kinase II (CaMKII)-phospholamban (PLB)-sarcoplasmic reticulum Ca2+-ATPase 2a axis and protein kinase C (PKC) activity in cardiomyocytes leading to impaired cardiac contractility and electrophysiological function. However, the link between saxagliptin and its target proteins (CaMKII and PKC) remains to be explored. Since DPP8 and DPP9 (but not DPP4) are expressed by cardiomyocytes and saxagliptin is internalized by cardiomyocytes, we investigated whether DPP8/9 contribute to saxagliptin-mediated inhibition of CaMKII and PKC activity. Structural analysis revealed that the DPP4-saxagliptin interaction motif (S630, Y547) for the cyanopyrrolidine group is conserved in DPP8 (S755, Y669) and DPP9 (S730, Y644). Conversely, F357 that facilitates binding of the anchor lock domain of sitagliptin in the S2 extensive subsite of DPP4 is not conserved in DPP8/9. In parallel, unlike saxagliptin, sitagliptin did not affect phosphorylation of CaMKII/PLB or activity of PKC in HL-1 cardiomyocytes. These findings were recapitulated by pharmacological inhibition (TC-E-5007, a DPP8/9 antagonist) and knock-down of DPP9 (but not DPP8). In primary mouse ventricular cardiomyocytes, saxagliptin (but not sitagliptin) impaired Ca2+ transient relaxation and prolonged action potential duration (APD). These results suggest that saxagliptin-DPP9 interaction impairs the CaMKII-PLB and PKC signaling in cardiomyocytes. We reveal a novel and potential role of DPP9 in cardiac signaling. The interaction of saxagliptin with DPP9 may represent an underlying mechanism for the link between saxagliptin and HF. Elucidation of saxagliptin-DPP9 interaction and downstream events may foster a better understanding of the role of gliptins as modulators of cardiac signaling.

Diabetic Cardiomyopathy: Current and Future Therapies. Beyond Glycemic Control

Diabetes mellitus and the associated complications represent a global burden on human health and economics. Cardiovascular diseases are the leading cause of death in diabetic patients, who have a 2–5 times higher risk of developing heart failure than age-matched non-diabetic patients, independent of other comorbidities. Diabetic cardiomyopathy is defined as the presence of abnormal cardiac structure and performance in the absence of other cardiac risk factors, such coronary artery disease, hypertension, and significant valvular disease. Hyperglycemia, hyperinsulinemia, and insulin resistance mediate the pathological remodeling of the heart, characterized by left ventricle concentric hypertrophy and perivascular and interstitial fibrosis leading to diastolic dysfunction. A change in the metabolic status, impaired calcium homeostasis and energy production, increased inflammation and oxidative stress, as well as an accumulation of advanced glycation end products are among the mechanisms implicated in the pathogenesis of diabetic cardiomyopathy. Despite a growing interest in the pathophysiology of diabetic cardiomyopathy, there are no specific guidelines for diagnosing patients or structuring a treatment strategy in clinical practice. Anti-hyperglycemic drugs are crucial in the management of diabetes by effectively reducing microvascular complications, preventing renal failure, retinopathy, and nerve damage. Interestingly, several drugs currently in use can improve cardiac health beyond their ability to control glycemia. GLP-1 receptor agonists and sodium-glucose co-transporter 2 inhibitors have been shown to have a beneficial effect on the cardiovascular system through a direct effect on myocardium, beyond their ability to lower blood glucose levels. In recent years, great improvements have been made toward the possibility of modulating the expression of specific cardiac genes or non-coding RNAs in vivo for therapeutic purpose, opening up the possibility to regulate the expression of key players in the development/progression of diabetic cardiomyopathy. This review summarizes the pathogenesis of diabetic cardiomyopathy, with particular focus on structural and molecular abnormalities occurring during its progression, as well as both current and potential future therapies.

Revisiting the Diabetes-Heart Failure Connection

PURPOSE OF THE REVIEW

To summarize current clinical data investigating the link between diabetes and heart failure pathophysiology, the association of glucose control with heart failure, and the impact of current antihyperglycemic drugs on heart failure.

RECENT FINDINGS

Although heart failure is one of the most prevalent outcomes occurring in real life and cardiovascular outcome trials, insufficient attention was given to this condition in diabetes research over the last decades. With both beneficial and detrimental findings for heart failure hospitalization in the health authority-mandated outcome trials for new antihyperglycemic agents, research on heart failure and its interplay with diabetes mellitus gained momentum. Diabetes mellitus and heart failure are both prevalent and intertwined conditions. While currently available heart failure therapies have a similar degree of effectiveness in patients with and without diabetes, the choice of glucose-lowering agents can substantially affect heart failure-related outcome.

Sinoatrial Beat to Beat Variability Assessed by Contraction Strength in Addition to the Interbeat Interval

Beat to beat variability of cardiac tissue or isolated cells is frequently investigated by determining time intervals from electrode measurements in order to compute scale dependent or scale independent parameters. In this study, we utilize high-speed video camera recordings to investigate the variability of intervals as well as mechanical contraction strengths and relative contraction strengths with nonlinear analyses. Additionally, the video setup allowed us simultaneous electrode registrations of extracellular potentials. Sinoatrial node tissue under control and acetylcholine treated conditions was used to perform variability analyses by computing sample entropies and Higuchi dimensions. Beat to beat interval variabilities measured by the two recording techniques correlated very well, and therefore, validated the video analyses for this purpose. Acetylcholine treatment induced a reduction of beating rate and contraction strength, but the impact on interval variability was negligible. Nevertheless, the variability analyses of contraction strengths revealed significant differences in sample entropies and Higuchi dimensions between control and acetylcholine treated tissue. Therefore, the proposed high-speed video camera technique might represent a non-invasive tool that allows long-lasting recordings for detecting variations in beating behavior over a large range of scales.

Cardiovascular Effects of New Oral Glucose-Lowering Agents: DPP-4 and SGLT-2 Inhibitors

Cardiovascular disease (CVD) is a major challenge in the management of type 2 diabetes mellitus. Glucose-lowering agents that reduce the risk of major cardiovascular events would be considered a major advance, as recently reported with liraglutide and semaglutide, 2 glucagon-like peptide-1 receptor agonists, and with empagliflozin and canagliflozin, 2 SGLT-2 (sodium-glucose cotransporter type 2) inhibitors, but not with DPP-4 (dipeptidyl peptidase-4) inhibitors. The present review is devoted to CV effects of new oral glucose-lowering agents. DPP-4 inhibitors (gliptins) showed some positive cardiac and vascular effects in preliminary studies, and initial data from phase 2 to 3 clinical trials suggested a reduction in major cardiovascular events. However, subsequent CV outcome trials with alogliptin, saxagliptin, and sitagliptin showed noninferiority but failed to demonstrate any superiority compared with placebo in patients with type 2 diabetes mellitus and high CV risk. An unexpected higher risk of hospitalization for heart failure was reported with saxagliptin. SGLT-2 inhibitors (gliflozins) promote glucosuria, thus reducing glucose toxicity and body weight, and enhance natriuresis, thus lowering blood pressure. Two CV outcome trials in type 2 diabetes mellitus patients mainly in secondary prevention showed remarkable positive results. Empagliflozin in EMPA-REG-OUTCOME (EMPAgliflozin Cardiovascular OUTCOME Events in Type 2 Diabetes Mellitus Patients) reduced major cardiovascular events, CV mortality, all-cause mortality, and hospitalization for heart failure. In CANVAS (Canagliflozin Cardiovascular Assessment Study), the reduction in CV mortality with canagliflozin failed to reach statistical significance despite a similar reduction in major cardiovascular events. The underlying protective mechanisms of SGLT-2 inhibitors remain unknown and both hemodynamic and metabolic explanations have been proposed. CVD-REAL studies (Comparative Effectiveness of Cardiovascular Outcomes in New Users of Sodium-Glucose Cotransporter-2 Inhibitors; with the limitation of an observational approach) suggested that these favorable results may be considered as a class effect shared by all SGLT-2 inhibitors (including dapagliflozin) and be extrapolated to a larger population of patients with type 2 diabetes mellitus in primary prevention. Ongoing CV outcome trials with other DPP-4 (linagliptin) and SGLT-2 (dapagliflozin, ertugliflozin) inhibitors should provide additional information about CV effects of both pharmacological classes.

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.

A review of dipeptidyl peptidase-4 inhibitors. Hot topics from randomized controlled trials

The first clinical study to investigate effects of dipeptidyl peptidase-4 (DPP-4) inhibition was published in 2002, and since then, numerous randomized controlled trials (RCTs) have shown that DPP-4 inhibitors are efficacious, safe and well-tolerated. This review will focus upon RCTs which have investigated DPP-4 inhibitors in patient groups which are often under-represented or excluded from typical phase 3 clinical trials. Large cardiovascular (CV) safety outcome trials in patients with established CV disease have confirmed that DPP-4 inhibitors are not associated with any additional CV risk in these already-at-high-risk individuals, while raising awareness of any uncommon adverse events, such as heart failure hospitalization seen in one of the trials. Studies in patients with kidney disease have shown DPP-4 inhibitors to be efficacious without increasing the risk of hypoglycaemia, irrespective of the degree of renal impairment, while data from the large CV trials as well as smaller RCTs have even pointed towards potential renoprotective effects such individuals. The use of DPP-4 inhibitors with insulin when therapy requires intensification may be beneficial without affecting the incidence or severity of hypoglycaemia, with these effects also being replicated in patients with chronic kidney disease, for whom other agents may not be suitable. Attention is now turning towards exploring the potential utility of DPP-4 inhibitors in other circumstances, including for in-hospital management of hyperglycaemia and in other metabolic disorders. Together, these RCTs raise the possibility that in the future, DPP-4 inhibitors may have a broader use which may extend beyond glycaemic control in the typical type 2 diabetes mellitus (T2DM) patient seen in general practice and may encompass conditions other than T2DM.