Mechanism of lipid-lowering action of the dipeptidyl peptidase-4 inhibitor, anagliptin, in low-density lipoprotein receptor-deficient mice

The Safety and Efficacy of Combining Saxagliptin and Pioglitazone Therapy in Streptozocin-Induced Diabetic Rats

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a chronic progressive disease due to insulin resistance. Oxidative stress complicates the etiology of T2DM. Saxagliptin is a selective dipeptidyl peptidase-4 (DPP-4) inhibitor, while Pioglitazone is a thiazolidinedione insulin sensitizer. This study aimed to assess the effect of Saxagliptin and Pioglitazone monotherapy and combination therapy on the biochemical and biological parameters in streptozotocin (STZ)-induced diabetic rats.

METHODS

The study included thirty-five male albino rats. Diabetes mellitus was induced by intraperitoneal STZ injection (35 mg/kg). For a 1-month duration, rats were divided into five groups. Glucose homeostasis traits, lipid profiles, kidney functions, liver enzymes, and oxidative stress markers were measured. Gene expression of miRNA-29a, phosphoenolpyruvate carboxykinase (PEPCK), phosphoinositide-3-kinase (PI3K), and interleukin 1 beta (IL-1β) was assessed using qRT-PCR.

RESULTS

At a 1-month treatment duration, combination therapy improves oxidative stress markers more than either drug alone. The combination therapy had significantly higher levels of SOD, catalase, and GSH and lower levels of MDA compared to the monotherapy. Additionally, the diabetic group showed a significant increase in the expression levels of miRNA-29a, PEPCK, and IL-1β and a significant decrease in PI3K compared to the normal control group. However, combination therapy of Saxagliptin and Pioglitazone was more effective than either Saxagliptin or Pioglitazone alone in reversing these results, especially for PEPCK and IL-1β.

CONCLUSIONS

Our findings revealed that combining Saxagliptin and Pioglitazone improves glycemic control and genetic and epigenetic expression profiles, which play an essential regulatory role in normal metabolism.

Novel Antidiabetic Agents and Their Effects on Lipid Profile: A Single Shot for Several Cardiovascular Targets

Type-2 diabetes mellitus (DM) represents one of the most important risk factors for cardiovascular diseases (CVD). Hyperglycemia and glycemic variability are not the only determinant of the increased cardiovascular (CV) risk in diabetic patients, as a frequent metabolic disorder associated with DM is dyslipidemia, characterized by hypertriglyceridemia, decreased high-density lipoprotein (HDL) cholesterol levels and a shift towards small dense low-density lipoprotein (LDL) cholesterol. This pathological alteration, also called diabetic dyslipidemia, represents a relevant factor which could promotes atherosclerosis and subsequently an increased CV morbidity and mortality. Recently, the introduction of novel antidiabetic agents, such as sodium glucose transporter-2 inhibitors (SGLT2i), dipeptidyl peptidase-4 inhibitors (DPP4i) and glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs), has been associated with a significant improvement in CV outcomes. Beyond their known action on glycemia, their positive effects on the CV system also seems to be related to an ameliorated lipidic profile. In this context, this narrative review summarizes the current knowledge regarding these novel anti-diabetic drugs and their effects on diabetic dyslipidemia, which could explain the provided global benefit to the cardiovascular system.

Treatment of diabetes mellitus has borne much fruit in the prevention of cardiovascular disease

Cardiovascular (CV) disease is the most alarming complication of diabetes mellitus (DM), and a strategy aiming at cardiovascular event prevention in diabetes mellitus has long been debated. Large landmark clinical trials have shown cardiovascular benefits of intensive glycemic control as a ‘legacy effect’ in newly diagnosed type 2 diabetes mellitus. In contrast, we have learned that excessive intervention aimed at strong glycemic control could cause unexpected cardiovascular death in patients who are resistant to treatments against hyperglycemia. It has also been shown that the comprehensive multifactorial intervention for cardiovascular risk factors that was advocated in the current guideline provided substantial cardiovascular event reduction. The impact of classical antidiabetic agents launched before 1990s on cardiovascular events is controversial. Although there are many clinical or observational studies assessing the impact of those agents on cardiovascular events, the conclusions are inconsistent owing to variable patient backgrounds and concomitant antidiabetic agents among the studies. Moreover, most of them were not large‐scale, randomized, cardiovascular outcome trials. In contrast, GLP‐1RA (glucagon‐like peptide‐1 receptor agonist) and SGLT2 (sodium‐glucose cotransporter 2) inhibitors have demonstrated undeniable cardiovascular benefits in large‐scale, randomized, controlled trials. Whereas GLP‐1RAs decrease atherosclerotic disease, especially stroke, SGLT2 inhibitors mainly prevent heart failure. SGLT2 inhibitors are superior to GLP‐1RAs with respect to hard renal outcomes. Therefore, it can be said that drugs such as GLP‐1RAs and SGLT2 inhibitors that prevent cardiovascular events, in addition to their glucose‐lowering effect, are incredible novel tools that we have gained for use in diabetic treatment.

Differential Effects of DPP-4 Inhibitors, Anagliptin and Sitagliptin, on PCSK9 Levels in Patients with Type 2 Diabetes Mellitus who are Receiving Statin Therapy

Aim: Proprotein convertase subtilisin/kexin type 9 (PCSK9) degrades the low-density lipoprotein (LDL) receptor, leading to hypercholesterolemia and cardiovascular risk. Treatment with a statin leads to a compensatory increase in circulating PCSK9 level. Anagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, was shown to decrease LDL cholesterol (LDL-C) levels to a greater extent than that by sitagliptin, another DPP-4 inhibitor, in the Randomized Evaluation of Anagliptin versus Sitagliptin On low-density lipoproteiN cholesterol in diabetes (REASON) trial. We investigated PCSK9 concentration in type 2 diabetes mellitus (T2DM) and the impact of treatment with anagliptin or sitagliptin on PCSK9 level as a sub-analysis of the REASON trial.

Methods: PCSK9 concentration was measured at baseline and after 52 weeks of treatment with anagliptin ( n =122) or sitagliptin ( n =128) in patients with T2DM who were receiving statin therapy. All of the included patients had been treated with a DPP-4 inhibitor prior to randomization.

Results: Baseline PCSK9 level was positively, but not significantly, correlated with LDL-C and was independently associated with platelet count and level of triglycerides. Concomitant with reduction of LDL-C, but not hemoglobin A1c (HbA1c), by anagliptin, PCSK9 level was significantly increased by treatment with sitagliptin (218±98 vs. 242±115 ng/mL, P =0.01), but not anagliptin (233±97 vs. 250±106 ng/mL, P =0.07).

Conclusions: PCSK9 level is independently associated with platelet count and level of triglycerides, but not LDL-C, in patients with T2DM. Anagliptin reduces LDL-C level independent of HbA1c control in patients with T2DM who are on statin therapy possibly by suppressing excess statin-mediated PCSK9 induction and subsequent degradation of the LDL receptor.

Anagliptin Monotherapy for Six Months in Patients With Type 2 Diabetes Mellitus and Hyper-Low-Density Lipoprotein Cholesterolemia Reduces Plasma Levels of Fasting Low-Density Lipoprotein Cholesterol and Lathosterol: A Single-Arm Intervention Trial

Background

Anagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, has been shown to decrease plasma low-density lipoprotein cholesterol (LDL-C) levels. The objective of our study was to elucidate the mechanisms responsible for the anagliptin-mediated improvements in high LDL-C levels (hyper-LDL cholesterolemia).

Methods

We prospectively examined the effects of anagliptin monotherapy on fasting plasma lathosterol, sitosterol, and campesterol levels in patients with type 2 diabetes mellitus and hyper-LDL cholesterolemia for 6 months. We examined 14 patients who did not use hypoglycemic or lipid-lowering drugs for 4 months before initiating the study. Plasma variables related to glucose and lipid metabolism were measured before and after 6 months of treatment and pre- and postprandially using the cookie-loading test.

Results

After treatment, anagliptin monotherapy (n = 14) significantly decreased fasting LDL-C (175.6 to 148.5 mg/dL, mean values before and after the treatment, respectively) and plasma lathosterol levels (3.56 to 2.49 mg/dL), whereas it did not lower fasting sitosterol or campesterol levels. Furthermore, fasting plasma lathosterol levels were negatively correlated with preprandial glucagon-like peptide-1 (GLP-1) levels after anagliptin treatment.

Conclusions

Anagliptin monotherapy may have a beneficial effect on lipid metabolism, which could be mediated by the inhibition of hepatic cholesterol synthesis rather than the inhibition of intestinal lipid transport.

Sitagliptin Reduces Endothelial Dysfunction and Apoptosis Induced by High-Fat Diet and Palmitate in Thoracic Aortas and Endothelial Cells via ROS-ER Stress-CHOP Pathway

Macrovascular disease is tightly associated with obesity-induced metabolic syndrome. Sitagliptin (SIT), an orally stable selective inhibitor of Dipeptidyl peptidase-4 (DPP-4), has protective effects on endothelium. However, the mechanisms enabling SIT to exhibit resistance to diet-induced obesity (DIO) related with reactive oxygen species (ROS) and endoplasmic reticulum (ER) stress in the aorta and endothelial cells have not been reported yet. Therefore, the present study was conducted to determine if SIT exerts protective role in the thoracic aortas isolated from the high-fat diet (HFD)-treated rats and palmitate (PA)-treated endothelial cells by alleviating ROS and ER stress. Male Sprague Dawley rats were randomly divided into standard chow diet (SCD), HFD and HFD plus sitagliptin administration (HFD + SIT) groups. The rats of latter two groups were given HFD fodder for 12 weeks, then the HFD + SIT rats were treated with SIT (10 mg/kg/d) by intragastric administration for another 8 weeks. The body mass, vascular tension, serum oxidative stress indices and inflammatory parameters, pathological changes, protein expression of endothelial nitric oxide synthase (eNOS), the genes associated with ER stress and apoptosis in the thoracic aorta were measured. Furthermore, cell proliferation, ROS and the protein expression associated with ER stress (especially CHOP) and apoptosis were assessed in human umbilical vein endothelial cells (HUVECs) incubated with SIT and PA. Compared to the SCD rats, the HFD rats had higher serum lipid levels, decreased vascular tension, increased inflammation, oxidative and ER stress, and apoptosis of endothelial cells. PA promoted ROS generation, ER stress and apoptosis, inhibited cell proliferation in HUVECs. SIT treatment obviously ameliorated apoptosis via alleviating ROS and ER stress in the thoracic aortas isolated from HFD-fed rats and PA-treated HUVECs. The results suggest that SIT improved endothelial function via promoting cell proliferation and alleviating ROS-ER stress-CHOP pathway both in vivo and in vitro.

Dipeptidyl peptidase-4 inhibitor protects against non-alcoholic steatohepatitis in mice by targeting TRAIL receptor-mediated lipoapoptosis via modulating hepatic dipeptidyl peptidase-4 expression

Dipeptidyl peptidase-4 inhibitors (DPP4i) are antidiabetic medications that prevent cleavage of incretin hormones by dipeptidyl peptidase-4 (DPP4). DPP4 is ubiquitously expressed, and its hepatic DPP4 expression is upregulated under non-alcoholic steatohepatitis (NASH) conditions. We investigated the effect of DPP4i treatment on NASH pathogenesis, as well as its potential underlying molecular mechanisms. Mice were randomly divided into three groups: Group 1, chow-fed mice treated with vehicle for 20 weeks; Group 2, high-fat, high-fructose, and high-cholesterol Amylin liver NASH (AMLN) diet-fed mice treated with vehicle for 20 weeks; Group 3, AMLN diet-fed mice treated with vehicle for the first 10 weeks, followed by the DPP4i teneligliptin (20 mg/kg/day) for additional 10 weeks. DPP4i administration reduced serum liver enzyme and hepatic triglyceride levels and markedly improved hepatic steatosis and fibrosis in the AMLN diet-induced NASH model. In vivo, NASH alleviation significantly correlated with the suppression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor-mediated apoptosis and downregulated hepatic DPP4 expression. In vitro, DPP4i treatment significantly decreased the markers of TRAIL receptor-mediated lipoapoptosis and suppressed DPP4 expression in palmitate-treated hepatocytes. In conclusion, DPP4i may efficiently attenuate the pathogenesis of AMLN diet-induced NASH in mice by suppressing lipotoxicity-induced apoptosis, possibly by modulating hepatic DPP4 expression.

Treatment with anagliptin, a DPP-4 inhibitor, decreases FABP4 concentration in patients with type 2 diabetes mellitus at a high risk for cardiovascular disease who are receiving statin therapy

Background

Fatty acid-binding protein 4 (FABP4) acts as a novel adipokine, and elevated FABP4 concentration is associated with obesity, insulin resistance and atherosclerosis. Dipeptidyl peptidase-4 (DPP-4) inhibitors, a class of antidiabetic drugs, have distinct structures among the drugs, possibly leading to a drug class effect and each drug effect. Sitagliptin, a DPP-4 inhibitor, has been reported to decrease FABP4 concentration in drug-naïve and sulfonylurea-treated patients with type 2 diabetes mellitus. Anagliptin, another DPP-4 inhibitor, was shown to decrease low-density lipoprotein cholesterol (LDL-C) level to a greater extent than that by sitagliptin in the Randomized Evaluation of Anagliptin vs. Sitagliptin On low-density lipoproteiN cholesterol in diabetes (REASON) trial.

Aim and methods

As a sub-analysis study using data obtained from the REASON trial, we investigated the effects of treatment with anagliptin (n = 148, male/female: 89/59) and treatment with sitagliptin (n = 159, male/female: 93/66) for 52 weeks on FABP4 concentration in patients with type 2 diabetes mellitus at a high risk for cardiovascular events who were receiving statin therapy.

Results

The DPP-4 inhibitor had been administered in 82% of the patients in the anagliptin group and 81% of the patients in sitagliptin group prior to randomization. Serum FABP4 level was significantly decreased by 7.9% by treatment with anagliptin (P = 0.049) and was not significantly decreased by treatment with sitagliptin (P = 0.660). Change in FABP4 level was independently associated with basal FABP4 level and changes in waist circumference and creatinine after adjustment of age, sex and the treatment group.

Conclusion

Anagliptin decreases serum FABP4 concentration independent of change in hemoglobin A1c or LDL-C in patients with type 2 diabetes mellitus and dyslipidemia who are on statin therapy.

Trial registration ClinicalTrials.gov number NCT02330406. Registered January 5, 2015, https://clinicaltrials.gov/ct2/show/NCT02330406

Comparison of Lipid-Lowering Effects of Anagliptin and Miglitol in Patients With Type 2 Diabetes: A Randomized Trial

Background

Recently, we reported that the level of lathosterol, a cholesterol synthesis marker, was suppressed after 1 month of treatment with anagliptin, a dipeptidyl peptidase-4 inhibitor. In this study, we administered either anagliptin or miglitol, an alpha-glucosidase inhibitor, for 3 months in patients with type 2 diabetes and compared the lipid-lowering effects of anagliptin with those of miglitol.

Methods

This study was a 12-week, open-label, prospective, randomized, parallel-group comparison trial. Fifty-two patients with type 2 diabetes who aged 20 - 70 years with a low-density lipoprotein cholesterol (LDL-C) level of over 120 mg/dL, and with no history of treatment with antihyperlipidemic drugs were enrolled. Patients were randomly assigned to either the anagliptin group or miglitol group. The 100 mg of anagliptin was administered twice a day for the anagliptin group and 50 mg of miglitol was administered thrice a day for miglitol group. The changes in lipids, cholesterol synthesis, and absorption markers were evaluated after 12 weeks.

Results

Fifty-two participants were initially enrolled in the trial, and 47 of them completed the protocol. There was no significant difference in LDL-C, cholesterol synthesis, and the absorption markers between anagliptin and miglitol groups.

Conclusions

Anagliptin and miglitol are similarly effective on lipid and glycemic control.

Dissimilar Effects of Anagliptin and Sitagliptin on Lipoprotein Subclass in Standard or Strong Statin-Treated Patients with Type-2 Diabetes Mellitus: A Subanalysis of the REASON (Randomized Evaluation of Anagliptin versus Sitagliptin on Low-Density LipoproteiN Cholesterol in Diabetes) Trial

The effects of antidiabetic agents on lipoprotein subclasses are assumed to be pivotal, but this assumption has not been studied. We evaluated lipoprotein subclasses in patients, randomly selected from REASON (Randomized Evaluation of Anagliptin versus Sitagliptin On low-density lipoproteiN cholesterol in diabetes) Trial participants, with type-2 diabetes treated with either anagliptin or sitagliptin. We measured total cholesterol (TC) and triglycerides (TG) in 4 (chylomicron (CM), very low-density lipoprotein (VLDL), low density lipoprotein (LDL), and high-density lipoprotein (HDL)) lipoprotein classes and 20 (2 CM, 5 VLDL, 6 LDL, and 7 HDL) lipoprotein subclasses. Between 0 and 52 weeks, TC and TG in lipoprotein and the lipoprotein subclass were distributed differently in patients treated with anagliptin and sitagliptin. The preferable changes in TC and TG levels were observed dominantly in the anagliptin-treated group under standard statin therapy, but the benefits were observed in both the anagliptin- and sitagliptin-treated groups, at least partially under strong statin therapy. In future studies, the atherogenic properties of lipoprotein subclasses might be considered when employing antidiabetic dipeptidyl peptidase-4 (DPP-4) inhibitors, especially in patients with type-2 diabetes who are at risk of atherosclerotic cardiovascular disease (ASCVD) or are undergoing statin treatment.

Differences in lipid metabolism between anagliptin and sitagliptin in patients with type 2 diabetes on statin therapy: a secondary analysis of the REASON trial

Background

Anagliptin, a dipeptidyl peptidase-4 inhibitor, is reported to reduce the level of low-density lipoprotein cholesterol (LDL-C). The underlying mechanism of this effect and effect on lipid metabolism however remains uncertain.

Aim and methods

We therefore evaluate the effects of anagliptin on lipid metabolism-related markers compared with those of sitagliptin. The study was a secondary analysis using data obtained from the Randomized Evaluation of Anagliptin versus Sitagliptin On low-density lipoproteiN cholesterol in diabetes (REASON) trial. This trial in patients with type 2 diabetes at a high risk of cardiovascular events and on statin therapy showed that anagliptin reduced LDL-C levels to a greater extent than sitagliptin. Cholesterol absorption (campesterol and sitosterol) and synthesis (lathosterol) markers were measured at baseline and 52 weeks in the study cohort (n = 353).

Results

There was no significant difference in the changes of campesterol or sitosterol between the two treatment groups (p = 0.85 and 0.55, respectively). Lathosterol concentration was increased significantly at 52 weeks with sitagliptin treatment (baseline, 1.2 ± 0.7 μg/mL vs. 52 weeks, 1.4 ± 1.0 μg/mL, p = 0.02), whereas it did not change in the anagliptin group (baseline, 1.3 ± 0.8 μg/mL vs. 52 weeks, 1.3 ± 0.7 μg/mL, p = 0.99). The difference in absolute change between the two groups showed a borderline significance (p = 0.06).

Conclusion

These findings suggest that anagliptin reduces LDL-C level by suppressing excess cholesterol synthesis, even in combination with statin therapy.

Trial registration ClinicalTrials.gov number NCT02330406. https://clinicaltrials.gov/ct2/show/NCT02330406; registered January 5, 2015.

Randomized Evaluation of Anagliptin vs Sitagliptin On low-density lipoproteiN cholesterol in diabetes (REASON) Trial: A 52-week, open-label, randomized clinical trial

Additional reductions in low-density lipoprotein-cholesterol (LDL-C) via antidiabetic therapies should be considered in statin-using patients with sub-optimal LDL-C levels. We compared the efficacy of anagliptin and sitagliptin, two antidiabetic therapies, in reducing LDL-C in type 2 diabetic patients. A randomized, open-label, parallel-group trial was conducted at 17 centres in Japan between April 2015 and January 2018. Adults (age ≥20 years) with type 2 diabetes, any atherosclerotic vascular lesions, and statin prescriptions were included. Anagliptin or sitagliptin were administered for 52 weeks. Primary and secondary endpoints were changes in LDL-C and haemoglobin A1C (HbA1c) levels, respectively. We assessed the superiority (primary endpoint) and non-inferiority (secondary endpoint) of anagliptin over sitagliptin. This study was registered at Clinicaltrials.gov (NCT02330406). Of 380 participants, 353 were eligible and randomized. Mean participant age was 68 years, and 61% were males. Baseline median LDL-C and HbA1c were 108 mg/dL and 6.9%, respectively. Changes in LDL-C were −3.7 mg/dL with anagliptin and +2.1 mg/dL with sitagliptin at 52 weeks, and the estimated treatment difference was a significant −4.5 mg/dL (P = 0.01 for superiority). Changes in HbA1c were +0.02% with anagliptin and +0.12% with sitagliptin (P < 0.0001 for non-inferiority). Overall, anagliptin was superior to sitagliptin in lowering LDL-C without deteriorating HbA1c.

Effect of Anagliptin and Sitagliptin on Low-Density Lipoprotein Cholesterol in Type 2 Diabetic Patients with Dyslipidemia and Cardiovascular Risk: Rationale and Study Design of the REASON Trial

Background

Reduction of low-density lipoprotein cholesterol (LDL-C) is important for patients with a high risk for atherosclerotic events, such as patients with diabetes and other risk factors. Anagliptin was reported to reduce LDL-C for 12 weeks in phase III trials regardless of the use of statins, but it is uncertain whether this effect is common to other dipeptidylpeptidase-4 (DPP-4) inhibitors.

Methods

A multicenter, randomized, open-label, parallel-group trial was conducted to confirm the superiority of anagliptin to sitagliptin in terms of the primary endpoint of reduction of LDL-C for 52 weeks in patients with type 2 diabetes and atherosclerotic vascular lesions, as well as the non-inferiority of anagliptin to sitagliptin in terms of change in hemoglobin A1c (HbA1c). Patients are randomly assigned to receive anagliptin or sitagliptin at a ratio of 1:1, with those in the anagliptin group receiving anagliptin 100 mg orally twice per day and those in the sitagliptin group receiving sitagliptin 50 mg orally once per day. During the trial period, hypoglycemic agents and anti-dyslipidemia drugs should not be added and neither should their dosages be changed. A total sample size of 300 was estimated to provide a power of 0.8 with a two-sided alpha of 0.05 for LDL-C, considering a 30% dropout rate. Pre-specified factors for subgroup analyses are HbA1c, use of DPP-4 inhibitors, sex, body mass index, LDL-C, age, and the presence of treatment for existing ischemic heart disease.

Discussion

If anagliptin were to be shown to reduce LDL-C in patients with type 2 diabetes and atherosclerotic vascular lesions despite pre-existing statin treatment, more intensive cholesterol management would be appropriate.

Trial Registration

Clinicaltrials.gov NCT02330406

Electronic supplementary material

The online version of this article (10.1007/s10557-018-6776-z) contains supplementary material, which is available to authorized users.

Pharmacology of dipeptidyl peptidase-4 inhibitors and its use in the management of metabolic syndrome: a comprehensive review on drug repositioning

OBJECTIVES

Despite advances in our understanding of metabolic syndrome (MetS) and the treatment of each of its components separately, currently there is no single therapy approved to manage it as a single condition. Since multi-drug treatment increases drug interactions, decreases patient compliance and increases health costs, it is important to introduce single therapies that improve all of the MetS components.

EVIDENCE ACQUISITION

We conducted a PubMed, Scopus, Google Scholar, Web of Science, US FDA, utdo.ir and clinicaltrial.gov search, gathered the most relevant preclinical and clinical studies that have been published since 2010, and discussed the beneficial effects of dipeptidyl peptidase (DPP)-4 inhibitors to prevent and treat different constituent of the MetS as a single therapy. Furthermore, the pharmacology of DPP-4 inhibitors, focusing on pharmacodynamics, pharmacokinetics, drug interactions and their side effects are also reviewed.

RESULTS

DPP-4 inhibitors or gliptins are a new class of oral anti-diabetic drugs that seem safe drugs with no severe side effects, commonly GI disturbance, infection and inflammatory bowel disease. They increase mass and function of pancreatic β-cells, and insulin sensitivity in liver, muscle and adipose tissue. It has been noted that gliptin therapy decreases dyslipidemia. DPP-4 inhibitors increase fatty oxidation, and cholesterol efflux, and decrease hepatic triglyceride synthase and de novo lipogenesis. They delay gastric emptying time and lead to satiety. Besides, gliptin therapy has anti-inflammatory and anti-atherogenic impacts, and improves endothelial function and reduces vascular stiffness.

CONCLUSION

The gathered data prove the efficacy of DPP-4 inhibitors in managing MetS in some levels beyond anti-diabetic effects. This review could be a lead for designing new DPP-4 inhibitors with greatest effects on MetS in future. Introducing drugs with polypharmacologic effects could increase the patient's compliance and decrease the health cost that there is not in multi-drug therapy. Graphical abstract ᅟ.

Modulating impacts of quercetin/sitagliptin combination on streptozotocin-induced diabetes mellitus in rats

BACKGROUND

Since many diabetic patients require combination therapy, the use of herbal remedies with anti-diabetic activity represents a vital option in diabetes mellitus (DM) management. It has been reported that quercetin has hypoglycemic alongside anti-inflammatory and antioxidant activities.

AIM

The present study aimed to investigate the effectiveness of combining quercetin with sitagliptin; a selective dipeptidyl peptidase-IV (DPP-IV) inhibitor, in the management of streptozotocin (STZ)-induced diabetic rats.

METHODS

DM was induced by a single injection of STZ (45 mg/kg, i.p.) in male adult albino Wistar rats. Diabetic rats were orally treated with sitagliptin (70 mg/kg), quercetin (50 mg/kg) or their combination daily for three consecutive weeks. Serum levels of glucose, C-peptide, total cholesterol, triglycerides, malondialdehyde (MDA), superoxide dismutase, (SOD), reduced glutathione (GSH), tumor necrosis factor alpha, (TNF-α), nuclear factor kappa-B, (NF-κB) and adiponectin were estimated. In addition, histopathological, morphometrical and immunohistochemical examinations of pancreatic tissues were conducted.

RESULTS

The combined administration of quercetin and sitagliptin normalized serum C-peptide, MDA, and significantly increased SOD, GSH and decreased NF-κB more than sitagliptin alone. Moreover, this combination normalized Islet number, β-cells' number, area and perimeter alongside restoring the immunostaining intensity of β-cells.

CONCLUSION

Our results suggest the use of quercetin/sitagliptin combination for treating DM based on the observed improvements in glycemic control, metabolic profile, oxidative and inflammatory status, islet structure as well as β-cells function compared with either treatment alone.

Efficacy of anagliptin as compared to linagliptin on metabolic parameters over 2 years of drug consumption: A retrospective cohort study

AIM

To evaluate the comparative effectiveness of anagliptin and linagliptin on the clinical parameters in patients with type 2 diabetes mellitus (T2DM).

METHODS

A 2-year retrospective cohort study was conducted in patients with T2DM who received anagliptin and linagliptin. We enrolled 234 patients (anagliptin group, 117 patients; linagliptin group, 117 patients).

RESULTS

The glycemic control considerably improved 3, 6, 12, and 24 mo after the administration of both dipeptidyl peptidase-4 (DPP-4) inhibitors. Following the administration of anagliptin, the diastolic blood pressure and serum total cholesterol levels decreased. However, serum high-density lipoprotein cholesterol levels increased and urinary albumin-creatinine ratio decreased following linagliptin administration. Furthermore, the liver function improved after the administration of linagliptin.

CONCLUSION

These findings suggest that that the efficacy of DPP-4 inhibitors on the blood pressure, lipid profile, and liver function differs between anagliptin and linagliptin.

Obesity-Related Asthma: Immune Regulation and Potential Targeted Therapies

Obesity, one of the most severe public health problems of the 21st century, is a common metabolic syndrome due to excess body fat. The incidence and severity of obesity-related asthma have undergone a dramatic increase. Because obesity-related asthma is poorly controlled using conventional therapies, alternative and complementary therapies are urgently needed. Lipid metabolism may be abnormal in obesity-related asthma, and immune modulation therapies need to be investigated. Herein, we describe the immune regulators of lipid metabolism in obesity as well as the interplay of obesity and asthma. These lay the foundations for targeted therapies in terms of direct and indirect immune regulators of lipid metabolism, which ultimately help provide effective control of obesity-related asthma with a feasible treatment strategy.

Effect of Anagliptin on Glycemic and Lipid Profile in Patients With Type 2 Diabetes Mellitus

Background

Anagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor expected to improve the lipid profile as well as glycemic control. However, findings from large-scale prospective trials have not been obtained.

Methods

We performed a multicenter prospective trial in patients with type 2 diabetes receiving anagliptin to evaluate its effect on glycemic control and the lipid profile. A total of 95 patients received anagliptin at 200 mg twice daily. Markers of glucose and lipid metabolism were measured at baseline and after 12 and 24 weeks of administration, and the absolute changes and percent changes were determined.

Results

Both HbA1c and plasma glucose were significantly decreased by anagliptin therapy. Regarding the lipid profile, total cholesterol (TC) showed a significant decrease at 12 weeks, while TC, low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were significantly decreased at 24 weeks. Multivariate analysis revealed that female sex was an independent predictor of greater reduction of TC, LDL-C, and HDL-C, while a baseline TC level ≥ 200 mg/dL predicted greater reduction of TC and a baseline HDL-C level ≥ 40 mg/dL predicted greater reduction of LDL-C and HDL-C.

Conclusions

This study suggested that anagliptin significantly reduced TC, LDL-C, and HDL-C levels, as well as improving glycemic control, particularly in female patients.

Dipeptidyl peptidase 4 inhibitor anagliptin ameliorates hypercholesterolemia in hypercholesterolemic mice through inhibition of intestinal cholesterol transport

Aims/Introduction

Recent data showed that dipeptidyl peptidase 4 (DPP‐4) inhibitors exert a lipid‐lowering effect in diabetes patients. However, the mechanism of action is not yet clearly understood. We investigated the effect of anagliptin on cholesterol metabolism and transport in the small intestine using non‐diabetic hyperlipidemic animals, to clarify the mechanisms underlying the cholesterol‐lowering action.

Materials and Methods

Male apolipoprotein E (ApoE)‐deficient mice were orally administered anagliptin in the normal chow. Serum cholesterol levels and lipoprotein profiles were measured, and cholesterol transport was assessed by measuring the radioactivity in the tissues after oral loading of ¹⁴C‐labeled cholesterol (¹⁴C‐Chol). In additional experiments, effects of exendin‐4 in mice and of anagliptin in DPP‐4‐deficient rats were assessed. Effects on target gene expressions in the intestine were analyzed by quantitative polymerase chain reaction in normal mice.

Results

The serum total and non‐high‐density lipoprotein cholesterol concentrations decreased after anagliptin treatment in the ApoE‐deficient mice. The cholesterol‐lowering effect was predominantly observed in the chylomicron fraction. The plasma ¹⁴C‐Chol radioactivity was significantly decreased by 26% at 2 h after cholesterol loading, and the fecal ¹⁴C‐Chol excretion was significantly increased by 38% at 72 h. The aforementioned effects on cholesterol transport were abrogated in rats lacking DPP‐4 activity, and exendin‐4 had no effect on the ¹⁴C‐Chol transport in ApoE‐deficient mice. Furthermore, significant decreases of the intestinal cholesterol transport‐related microsomal triglyceride transfer protein, acyl‐coenzyme A:cholesterol acyltransferase 2, ApoA2 and ApoC2 messenger ribonucleic acid expressions were observed in the mice treated with repeated doses of anagliptin.

Conclusions

These findings suggest that anagliptin might exert a cholesterol‐lowering action through DPP‐4‐dependent and glucagon‐like peptide 1‐independent suppression of intestinal cholesterol transport.

Comparison of effects of anagliptin and alogliptin on serum lipid profile in type 2 diabetes mellitus patients

INTRODUCTION

Anagliptin (ANA) improves dyslipidemia in addition to blood glucose levels. However, there are no comparative studies on the effects of ANA and other dipeptidyl peptidase-4 inhibitors on serum lipid profile. We compared the effects of ANA on serum lipid profile with those of alogliptin (ALO) in type 2 diabetes mellitus outpatients.

MATERIALS AND METHODS

The study participants were 87 type 2 diabetes mellitus patients who had been treated with dipeptidyl peptidase-4 inhibitors for ≥8 weeks and had a low-density lipoprotein cholesterol (LDL-C) level of ≥120 mg/dL. Participants were switched to either 200 mg/day ANA or 25 mg/day ALO for 24 weeks.

RESULTS

There was no significant difference in percentage change in LDL-C level at 24 weeks between the ANA and ALO groups. Treatment with ANA for 12 weeks significantly decreased LDL-C levels, one of the secondary end-points. Treatment with ANA for 24 weeks significantly improved apolipoprotein B-100 levels, and the percentage change in LDL-C levels at 24 weeks correlated significantly with the percentage change in apolipoprotein B-100 levels in the ANA group.

CONCLUSIONS

The LDL-C-lowering effects of ANA and ALO at 24 weeks were almost similar in patients with type 2 diabetes mellitus. However, the results showed a tendency for a decrease in LDL-C level at 24 weeks in the ANA group, and that such improvement was mediated, at least in part, through the suppression of apolipoprotein B-100 synthesis.

The effects of vildagliptin compared with metformin on vascular endothelial function and metabolic parameters: a randomized, controlled trial (Sapporo Athero-Incretin Study 3)

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) inhibitors may have protective effects in the early stage of atherosclerosis in patients with type 2 diabetes, although similar effects in advanced atherosclerosis were not shown in recent randomized placebo-controlled studies. Therefore, we investigated the efficacy of DPP-4 inhibitor on endothelial function and glycemic metabolism compared with high-dose metformin.

METHODS

In this multicenter, open-labeled, prospective, randomized, parallel-group comparison study, patients with type 2 diabetes treated with low-dose metformin (500-750 mg/day) were enrolled and randomly assigned to a vildagliptin, a DPP-4 inhibitor, add-on group (Vilda) or a double dose of metformin group (high Met) for 12 weeks. Flow-mediated dilation (FMD) and serum metabolic markers were assessed before and after treatment. In addition, glycemic control and metabolic parameters were also assessed.

RESULTS

Ninety-seven subjects (aged 58.7 ± 11.0 years; body mass index, 25.9 ± 4.4 kg/m2; HbA1c, 7.3 ± 0.5%; FMD, 5.8 ± 2.6%) were enrolled. Eight subjects dropped out by the end of the study. There were no significant differences between the two groups in baseline characteristics. After 12 weeks, HbA1c was significantly improved in the Vilda group compared with the high Met group (- 0.80 ± 0.38% vs. - 0.40 ± 0.47%, respectively; p < 0.01). However, there were no significant differences in FMD (- 0.51 [- 1.08-0.06]% vs. - 0.58 [- 1.20-0.04]%). Although the apolipoprotein B/apolipoprotein A1 ratio was significantly reduced in the Vilda group compared with baseline (0.66-0.62; p < 0.01), the change did not differ significantly between the two groups (- 0.04 vs. 0.00; p = 0.27). Adiponectin levels were significantly increased in the Vilda group compared with the high Met group (0.75 μg/mL vs. 0.01 μg/mL; p < 0.01).

CONCLUSIONS

Regardless of glycemic improvement, combination therapy of vildagliptin and metformin did not affect endothelial function but may exert favorable effects on adipokine levels and lipid profile in patients with type 2 diabetes without advanced atherosclerosis.

Long-Term Effect of Alogliptin on Glycemic Control in Japanese Patients With Type 2 Diabetes: A 3.5-Year Observational Study

Background

The goal of the current study was to investigate the long-term effects (after 3 years or more) of alogliptin on glycemic control in Japanese patients with type 2 diabetes.

Methods

We retrospectively studied the effect of alogliptin on glycemic control in the patients with type 2 diabetes who had participated in our previous 3-month study and who continued to take alogliptin for at least 36 months.

Results

The mean duration of alogliptin treatment was 42.8 ± 2.2 months. In all 39 patients, a significant reduction in hemoglobin A1c (HbA1c) levels was noted between the baseline and final visit: 7.8±0.6% to 7.2±1.0% (P = 0.0001). A significant reduction in HbA1c levels was found in a subgroup of patients who did not change their anti-diabetic drugs or did decrease the dose of their sulfonylureas (SUs) or did change to a lower strength repaglinide (n = 32): 7.7±0.6% to 7.2±1.0% (P = 0.0005). A significant decrease in low-density lipoprotein cholesterol (LDL-C) levels was observed in all of the patients that had LDL-C levels determined (P = 0.0406) (n = 37), and in a subgroup of patients who had not taken either statins, fibrates, or pioglitazone, or who had taken one or more of these drugs but the doses were not changed during the observation period (P = 0.0250) (n = 27).

Conclusion

The current study found that alogliptin performed well for glycemic control when evaluated by HbA1c levels in a long-term observation period exceeding 3 years in Japanese patients with type 2 diabetes. Alogliptin may also decrease circulating LDL-C levels with long-term use.

Mechanism of lipid-lowering action of the dipeptidyl peptidase-4 inhibitor, anagliptin, in low-density lipoprotein receptor-deficient mice

Aims/Introduction

Dipeptidyl peptidase‐4 inhibitors are used for treatment of patients with type 2 diabetes. In addition to glycemic control, these agents showed beneficial effects on lipid metabolism in clinical trials. However, the mechanism underlying the lipid‐lowering effect of dipeptidyl peptidase‐4 inhibitors remains unclear. Here, we investigated the lipid‐lowering efficacy of anagliptin in a hyperlipidemic animal model, and examined the mechanism of action.

Materials and Methods

Male low‐density lipoprotein receptor‐deficient mice were administered 0.3% anagliptin in their diet. Plasma lipid levels were assayed and lipoprotein profile was analyzed using high‐performance liquid chromatography. Hepatic gene expression was examined by deoxyribonucleic acid microarray and quantitative polymerase chain reaction analyses. Sterol regulatory element‐binding protein transactivation assay was carried out in vitro.

Results

Anagliptin treatment significantly decreased the plasma total cholesterol (14% reduction, P < 0.01) and triglyceride levels (27% reduction, P < 0.01). Both low‐density lipoprotein cholesterol and very low‐density lipoprotein cholesterol were also decreased significantly by anagliptin treatment. Sterol regulatory element‐binding protein‐2 messenger ribonucleic acid expression level was significantly decreased at night in anagliptin‐treated mice (15% reduction, P < 0.05). Anagliptin significantly suppressed sterol regulatory element‐binding protein activity in HepG2 cells (21% decrease, P < 0.001).

Conclusions

The results presented here showed that the dipeptidyl peptidase‐4 inhibitor, anagliptin, exhibited a lipid‐lowering effect in a hyperlipidemic animal model, and suggested that the downregulation of hepatic lipid synthesis was involved in the effect. Anagliptin might have beneficial effects on lipid metabolism in addition to a glucose‐lowering effect.