Dipeptidyl peptidase-4 inhibitors in cardioprotection: a promising therapeutic approach

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.

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.

The effect of various classes of glucose-lowering medications on the blood vessel elasticity in patients with type 2 diabetes

Aim. To study the effect of various classes of glucose-lowering agents (dipeptidyl peptidase-4 (DPP-4) and sodium-glucose cotransporter-2 (SGLT-2) inhibitors) on the vascular stiffness in patients with type 2 diabetes (T2D) and high cardiovascular risk.

Material and methods. The open-label, prospective 24-week study included 120 patients with T2D and high cardiovascular risk. We evaluated the effect of modern glucose-lowering medications, empagliflozin at a dose of 25 mg/day (SGLT-2 inhibitor) and sitagliptin at a dose of 100 mg/day (DPP-4 inhibitor), on vascular elasticity, central hemodynamic and laboratory parameters.

Results. After 24-week therapy, the target glycated hemoglobin level reached 71% and 80% of patients in the sitagliptin and empagliflozin groups, respectively. In both groups, vascular stiffness and central hemodynamic parameters were improved. However, significant changes were recorded only in the empagliflozin (carotid-femoral pulse wave velocity decreased by 14,4%, augmentation index — by 6%, central pulse pressure — by 7,8%) (p<0,05). Use of sitagliptin was associated with significant improvements in the lipid profile (total cholesterol decreased by 9,5%, triglycerides — by 21%, low density lipoproteins — by 15,1%; high density lipoproteins increased by 15,7%) (p<0,05). In the empagliflozin group, anthropometric parameters were improved (body mass index decreased by 9,1%, waist circumference — by 4,1%) (p<0,05). Patients in both groups had a significant decrease in HOMA-IR index and highly sensitive C-reactive protein: by 34% and 51,6% in the empagliflozin group and by 31,8% and 22,1% in the sitagliptin group, respectively (p<0,05).

Conclusion. The use of empagliflozin is more associated with arterial stiffness decrease in T2D patients with high cardiovascular risk compared with sitagliptin.

Additive effects of atorvastatin combined with sitagliptin on rats with myocardial infarction: a pilot study

INTRODUCTION

Atorvastatin and sitagliptin are able to exert cardio-protective effects. However, whether atorvastatin plus sitagliptin could confer additive benefits for rats with myocardial infarction (MI) is unknown.

MATERIAL AND METHODS

Forty rats with MI were produced and 37 surviving rats were randomly divided into atorvastatin (10 mg/kg daily, n = 9), sitagliptin (10 mg/kg daily, n = 9), combined (10 mg/kg daily atorvastatin plus 10 mg/kg daily sitagliptin, n = 9), and control groups (3 ml normal saline daily, n = 10). Fourteen days later, cardiac function was detected and fasting venous blood was sampled for lipid profiles and glucose evaluation. Cardiac tissues were used for hematoxylin-eosin staining, for interleukin-6 (IL-6) and tumor necrotic factor-α (TNF-α) evaluation, and for rho-associated kinase 2 (ROCK2) assessment.

RESULTS

Fourteen days after MI, the inflammatory reaction regarding the degree of leukocyte infiltration and IL-6 and TNF-α expression in cardiac tissues was ameliorated in atorvastatin and sitagliptin groups compared to the control group (p < 0.05). In addition, ROCK2 was attenuated by either atorvastatin or sitagliptin (p < 0.05). Echocardiography showed that cardiac function was significantly improved with atorvastatin and sitagliptin therapy (p < 0.05). Overall, all these benefits were further enhanced by combined therapy, suggesting that atorvastatin combined with sitagliptin therapy has additive effects on reducing cardiac inflammation and improving cardiac function. No significant changes in lipid profiles or glucose were observed, suggesting that the benefits derived from atorvastatin and sitagliptin therapy might not depend on cholesterol and glucose modulation.

CONCLUSIONS

In rats with MI, atorvastatin plus sitagliptin therapy provides additive effects for cardio-protection, and mechanisms operating in these processes may be due to ROCK2 diminishment.

Effect of Dipeptidyl Peptidase-4 Inhibitor on All-Cause Mortality and Coronary Revascularization in Diabetic Patients

BACKGROUND

Anti-atherosclerotic effect of dipeptidyl peptidase-4 (DPP-4) inhibitors has been suggested from previous studies, and yet, its association with cardiovascular outcome has not been demonstrated. We aimed to evaluate the effect of DPP-4 inhibitors in reducing mortality and coronary revascularization, in association with baseline coronary computed tomography (CT).

METHODS

The current study was performed as a multi-center, retrospective observational cohort study. All subjects with diabetes mellitus who had diagnostic CT during 2007-2011 were included, and 1866 DPP-4 inhibitor users and 5179 non-users were compared for outcome. The primary outcome was all-cause mortality and secondary outcome included any coronary revascularization therapy after 90 days of CT in addition to all-cause mortality.

RESULTS

DPP-4 inhibitors users had significantly less adverse events [0.8% vs. 4.4% in users vs. non-users, adjusted hazard ratios (HR) 0.220, 95% confidence interval (CI) 0.102-0.474, p = 0.0001 for primary outcome, 4.1% vs. 7.6% in users vs. non-users, HR 0.517, 95% CI 0.363-0.735, p = 0.0002 for secondary outcome, adjusted variables were age, sex, presence of hypertension, high sensitivity C-reactive protein, glycated hemoglobin, statin use, coronary artery calcium score and degree of stenosis]. Interestingly, DPP-4 inhibitor seemed to be beneficial only in subjects without significant stenosis (adjusted HR 0.148, p = 0.0013 and adjusted HR 0.525, p = 0.0081 for primary and secondary outcome).

CONCLUSION

DPP-4 inhibitor is associated with reduced all-cause mortality and coronary revascularization in diabetic patients. Such beneficial effect was significant only in those without significant coronary stenosis, which implies that DPP-4 inhibitor may have beneficial effect in earlier stage of atherosclerosis.

Vildagliptin stimulates endothelial cell network formation and ischemia-induced revascularization via an endothelial nitric-oxide synthase-dependent mechanism

Dipeptidyl peptidase-4 inhibitors are known to lower glucose levels and are also beneficial in the management of cardiovascular disease. Here, we investigated whether a dipeptidyl peptidase-4 inhibitor, vildagliptin, modulates endothelial cell network formation and revascularization processes in vitro and in vivo. Treatment with vildagliptin enhanced blood flow recovery and capillary density in the ischemic limbs of wild-type mice, with accompanying increases in phosphorylation of Akt and endothelial nitric-oxide synthase (eNOS). In contrast to wild-type mice, treatment with vildagliptin did not improve blood flow in ischemic muscles of eNOS-deficient mice. Treatment with vildagliptin increased the levels of glucagon-like peptide-1 (GLP-1) and adiponectin, which have protective effects on the vasculature. Both vildagliptin and GLP-1 increased the differentiation of cultured human umbilical vein endothelial cells (HUVECs) into vascular-like structures, although vildagliptin was less effective than GLP-1. GLP-1 and vildagliptin also stimulated the phosphorylation of Akt and eNOS in HUVECs. Pretreatment with a PI3 kinase or NOS inhibitor blocked the stimulatory effects of both vildagliptin and GLP-1 on HUVEC differentiation. Furthermore, treatment with vildagliptin only partially increased the limb flow of ischemic muscle in adiponectin-deficient mice in vivo. GLP-1, but not vildagliptin, significantly increased adiponectin expression in differentiated 3T3-L1 adipocytes in vitro. These data indicate that vildagliptin promotes endothelial cell function via eNOS signaling, an effect that may be mediated by both GLP-1-dependent and GLP-1-independent mechanisms. The beneficial activity of GLP-1 for revascularization may also be partially mediated by its ability to increase adiponectin production.

Dipeptidyl peptidase IV inhibitors and ischemic myocardial injury

Diabetes mellitus is a major risk factor for cardiovascular events and patient death. Many animal and clinical studies are now being conducted exploring the potential of antidiabetic drugs such as glucagon-like peptide 1 (GLP-1) agonists and dipeptidyl peptidase IV (DPP-IV) inhibitors to improve cardiovascular outcomes. This review summarizes the effect of DPP-IV inhibitors on myocardial ischemia-reperfusion injury in animal models. The DPP-IV inhibitors prevent the rapid degradation and inactivation of incretins and lead to the accumulation of GLP-1 and other chemokines and cytokines, which appear to have both GLP-1 receptor-dependent and -independent cardioprotective, antiapoptotic, and anti-inflammatory effects. Conflicting results, however, have been reported regarding the effect of DPP-IV inhibitors on infarct size in nondiabetic and diabetic animal models. Some studies suggest that DPP-IV inhibitors given as part of preconditioning can decrease infarct size while others found no difference in infarct size compared to placebo. As postconditioning, one study suggested it does provide cardioprotection. No clinical trials have yet been conducted addressing the effect of DPP-IV inhibitors on infarct size. Thus far, clinical trials have not demonstrated improvement in cardiovascular events or mortality from any cause in high cardiovascular risk, type 2 diabetic patients with the use of DPP-IV inhibitors. Although further experiments and clinical trials will be warranted to confirm the results of these studies, the myocardial protection afforded by DPP-IV inhibitors in preclinical animal studies poses a potential breakthrough role for antidiabetic medications in attenuation of ischemia-reperfusion injury that occurs with cardiovascular disease.

Assessment of the cardiovascular safety of saxagliptin in patients with type 2 diabetes mellitus: pooled analysis of 20 clinical trials

BACKGROUND

It is important to establish the cardiovascular (CV) safety profile of novel antidiabetic drugs.

METHODS

Pooled analyses were performed of 20 randomized controlled studies (N = 9156) of saxagliptin as monotherapy or add-on therapy in patients with type 2 diabetes mellitus (T2DM) as well as a subset of 11 saxagliptin + metformin studies. Adjudicated major adverse CV events (MACE; CV death, myocardial infarction [MI], and stroke) and investigator-reported heart failure were assessed, and incidence rates (IRs; events/100 patient-years) and IR ratios (IRRs; saxagliptin/control) were calculated (Mantel-Haenszel method).

RESULTS

In pooled datasets, the IR point estimates for MACE and individual components of CV death, MI, and stroke favored saxagliptin, but the 95% CI included 1. IRR (95% CI) for MACE in the 20-study pool was 0.74 (0.45, 1.25). The Cox proportional hazard ratio (95% CI) was 0.75 (0.46, 1.21), suggesting no increased risk of MACE in the 20-study pool. In the 11-study saxagliptin + metformin pool, the IRR for MACE was 0.93 (0.44, 1.99). In the 20-study pool, the IRR for heart failure was 0.55 (0.27, 1.12).

CONCLUSIONS

Analysis of pooled data from 20 clinical trials in patients with T2DM suggests that saxagliptin is not associated with an increased CV risk.

DPP-4 inhibitors repress foam cell formation by inhibiting scavenger receptors through protein kinase C pathway

Studies show that dipeptidyl peptidase-4 (DPP-4) inhibitors may have an anti-atherosclerotic effect. Since foam cells are key components of atherosclerotic plaque, we studied the effect of DPP-4 inhibitors on foam cell formation. Foam cell formation was studied by treatment of THP-1 macrophages with oxidized low-density lipoprotein in the absence or presence of DPP-4 inhibitors (sitagliptin and NVPDPP728). The expression of scavenger receptors SRA, CD36 and LOX-1 was measured, and their role in foam cell formation in the presence of DPP-4 inhibitors was examined. In additional studies, role of protein kinase C and A in the effect of DPP-4 inhibitors was examined. Foam cell formation was markedly reduced by both DPP-4 inhibitors, as was the expression of CD36 and LOX-1 (CD36 ≫ LOX-1), but not SRA. Simultaneously, there was a reduction in phosphorylated PKC, but not PKA, content. Recovery of phosphorylated PKC following treatment of cells negated the effect of DPP-4 inhibitors on foam cell formation. Further, overexpression of CD36 or LOX-1 blocked the effect of DPP-4 inhibitors on foam cell formation. DPP-4 inhibitors repress foam cell formation through the inhibition of SRs CD36 and LOX-1, most likely via the inhibition of PKC activity. This study provides novel insights into the mechanism of inhibition of atherosclerosis by DPP-4 inhibitors.