DPP-4 inhibitors and their potential role in the management of type 2 diabetes

Effects of dipeptidyl peptidase-4 inhibitors on beta-cell function and insulin resistance in type 2 diabetes: meta-analysis of randomized controlled trials

Dipeptidyl peptidase-4 (DPP-4) inhibitors are a novel family of glucose-lowering agents. Accumulating evidence suggests that DPP-4 inhibitors preserve pancreatic beta-cell function, but results in previous studies have been inconsistent. We assessed the effects of DPP-4 inhibitors on the homoeostasis model assessment beta-cell function (HOMA-B) or insulin resistance (HOMA-IR) index in patients with type 2 diabetes through a systematic review and meta-analysis of randomized controlled trials (RCTs). Relevant articles were identified from PubMed, Embase, and Cochrane Library databases up to December 27, 2016. We calculated weighted mean differences (WMDs) and 95% confidence intervals (CIs) in each included trial and pooled the data using a random-effects model. Fifty-two trials were included in the present analysis. Compared with placebo control, DPP-4 inhibitors as monotherapy significantly improved HOMA-B (WMD 9.15; 95% CI 7.48, 10.81). Similarly, DPP-4 inhibitors as add-on therapy in combination with other drugs showed significant improvement in HOMA-B (WMD 9.04; 95% CI 5.72, 12.37). However, we found no significant improvement in HOMA-IR following treatment with DPP-4 inhibitors as mono-therapy or as add-on therapy. In conclusion, DPP-4 inhibitors as monotherapy or as add-on therapy significantly improved beta-cell function but had no significant effect on insulin resistance in type 2 diabetes.

Recent Advances in Effect-directed Enzyme Assays based on Thin-layer Chromatography

Thin-layer chromatography (TLC) together with its more modern form high-performance thin-layer chromatography (HPTLC) is a rapid and cost effective analytical tool with a long tradition in quality control of medicinal plants, extracts and natural products. Separated compounds are fixed on the solid silica phase to form a compound library. Through direct coupling of visualisable enzyme reactions on the TLC plate, this compound library can also be used for activity screening. Such TLC-based bioautographic enzyme and enzyme inhibition assays complement first stage development activity screening assays. They provide not only phytochemical results by chromatographic separation, but also additional information about the activity of constituents or fractions in multi-compound mixtures, and thus can reveal and distinguish artefacts generated by certain compound classes. This review summarises recently introduced TLC bioautographic enzyme assays as well as advances in already existing procedures. Bioautographic enzyme and enzyme inhibitory assays offer a rapid, high-throughput method for screening of secondary metabolite profiles for potential enzyme and enzyme inhibitory activities. Copyright © 2017 John Wiley & Sons, Ltd.

Effects of saxagliptin add-on therapy to insulin on blood glycemic fluctuations in patients with type 2 diabetes: A randomized, control, open-labeled trial

BACKGROUND

To investigate whether saxagliptin add-on therapy to continuous subcutaneous insulin infusion (CSII) further improve blood glycemic control than CSII therapy in patients with newly diagnosed type 2 diabetes (T2D).

METHODS

This was a single-center, randomized, control, open-labeled trial. Newly diagnosed T2D patients were recruited between February 2014 and December 2015. Subjects were divided into saxagliptin add-on therapy to CSII group (n = 31) and CSII therapy group (n = 38). The treatment was maintained for 4 weeks. Oral glucose tolerance test was performed at baseline. Serum samples were obtained before and 30 and 120 minutes after oral administration for glucose, insulin, and C-peptide determination. Continuous glucose monitoring (CGM) was performed before and endpoint.

RESULTS

A total of 69 subjects were admitted. After 4-week therapy, CGM data showed that patients with saxagliptin add-on therapy exhibited further improvement of mean amplitude glycemic excursion (MAGE), the incremental area under curve of plasma glucose >7.8 and 10 mmol/L compared with that of control group. In addition, the hourly mean blood glucose concentrations, especially between 0000 and 0600 in patient with saxagliptin add-on therapy, were significantly lower compared with that of the control patients. Furthermore, patients in saxagliptin add-on group needed lower insulin dose to maintain euglycemic control. In addition, severe hypoglycemic episode was not observed from any group.

CONCLUSION

Saxagliptin add-on therapy to insulin had the ability of further improve blood glycemic controlling, with lower insulin dose required by patients with T2D to maintain euglycemic controlling.

Effect of Sitagliptin and Metformin on Prediabetes Progression to Type 2 Diabetes - A Randomized, Double-Blind, Double-Arm, Multicenter Clinical Trial: Protocol for the Sitagliptin and Metformin in PreDiabetes (SiMePreD) Study

Background

The high prevalence and incidence of type 2 diabetes mellitus (DM), and its associated morbidity and mortality, has prompted growing international interest and effort in the primary prevention of this disease. Primary prevention is possible since type 2 DM is preceded by prediabetes, offering a window opportunity to treat patients, and prevent the emergence of advanced disease. Sitagliptin is an oral dipeptidyl peptidase-IV inhibitor that preserves existing beta cell function and increases beta cell mass. These two effects have been demonstrated both in vitro and in animal studies, and current clinical data show that sitagliptin is safe. Metformin, a biguanide, reduces insulin resistance and inhibits hepatic gluconeogenesis, and has an excellent safety profile. The combination of metformin and sitagliptin, targeting both characteristics of prediabetes (insulin resistance and progressive beta cell degeneration), may potentially slow or halt the progression from prediabetes to type 2 DM. This paper describes the rationale and design of the Sitagliptin and Metformin in PreDiabetes (SiMePreD) study.

Objective

The aim of this study is to determine the effect of sitagliptin and metformin on progression from prediabetes to type 2 DM. The objectives of the study are to determine the effects of metformin and placebo on glycemic endpoints, the effects of sitagliptin and metformin on glycemic endpoints, the effects of metformin and placebo on incidence of cardiovascular disease and death, and the effects of sitagliptin and metformin on incidence of cardiovascular disease and death.

Methods

This is a randomized, double-blind, multicenter clinical study that will determine if the combination of metformin and sitagliptin is effective in preventing the progression from prediabetes to type 2 DM. The study will contain two arms (metformin/sitagliptin and metformin/placebo). Primary endpoints include the number of subjects progressing from prediabetes to type 2 DM, the number of cardiovascular events, and the number of deaths. The planned duration of the study is five years, and 410 subjects will be included in each group. Data analyses will include clinically relevant measures (eg, numbers needed to treat and numbers needed to harm) and will be performed according to the intention-to-treat principle.

Results

This study is currently in the process of acquiring research funding.

Conclusions

The SiMePreD study is the first study to investigate the utility of sitagliptin in combination with metformin for the primary prevention of type 2 DM. 

Cross-talk between the dipeptidyl peptidase-4 and stromal cell-derived factor-1 in stem cell homing and myocardial repair: Potential impact of dipeptidyl peptidase-4 inhibitors

Dipeptidyl peptidase-4 (DPP-4), glycyl-prolyl-naphthylamidase, is a serine protease that catalyzes the hydrolysis of various proline-containing polypeptides. It is involved in the inactivation of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), having in this way a profound influence on glucose metabolism. During organ damage, stromal and endothelial cells produce a chemokine known as stromal cell-derived factor-1 (SDF-1), a powerful chemoattractant of stem/progenitor cells. SDF-1 binds to a specific α-chemokine receptor (CXCR4) and can be degraded by proteases, including matrix DPP-4/CD26, presented in the circulation, or activated in injured tissues. DPP-4 inhibition has received considerable attention because of its significant therapeutic benefits in the regulation of insulin secretion and tissue insulin sensitivity, the regulation of tumor growth and metastasis, angiogenesis, tissue repair, especially after myocardial infarction, and regulation of endocrine function. Inhibition of circulating proteases appears to maintain the optimal endogenous SDF-1 concentration and may enhance homing of endothelial progenitor cells. In the present article, we present an overview of some basic facts about the role of DPP-4 in glucose homeostasis, the mechanism of its inhibition, and a brief summary of available DPP-4 inhibitors. Furthermore, since protection against the overactivity of proteases is important for restorating cardiac function and repair after myocardial damage, necrosis and apoptosis, we propose that administration of a DPP-4 inhibitor may also be beneficial following myocardial infarction by the prevention of cleavage of stem cell chemoattractant cytokine SDF-1.

Clinical and genetic predictors of dipeptidyl peptidase-4 inhibitor treatment response in Type 2 diabetes mellitus

AIM

To determine the clinical and genetic predictors of the dipeptidyl peptidase-4 (DPP-4) inhibitor treatment response in Type 2 diabetes mellitus (T2DM) patients.

PATIENTS & METHODS

DPP4, WFS1 and KCNJ11 gene polymorphisms were genotyped in a cohort study of 662 T2DM patients treated with DPP-4 inhibitors sitagliptin, vildagliptin or linagliptin. Genotyping was performed by Applied Biosystems TaqMan SNP genotyping assay.

RESULTS

Patients with triglyceride levels less than 1.7 mmol/l (odds ratio [OR]: 2.2.; 95% CI: 1.031-4.723), diastolic blood pressure (DBP) less than 90 mmHg (OR: 1.7; 95% CI: 1.009-2.892) and KCNJ11 rs2285676 (genotype CC) (OR: 2.0; 95% CI: 1.025-3.767) were more likely to response to DPP-4 inhibitor treatment compared with other patients, as measured by HbA1c levels.

CONCLUSION

Triglycerides, DBP and KCNJ11 rs2285676 are predictors of the DPP-4 inhibitor treatment response in T2DM patients.

Cut to the chase: a review of CD26/dipeptidyl peptidase-4's (DPP4) entanglement in the immune system

CD26/DPP4 (dipeptidyl peptidase 4/DP4/DPPIV) is a surface T cell activation antigen and has been shown to have DPP4 enzymatic activity, cleaving-off amino-terminal dipeptides with either L-proline or L-alanine at the penultimate position. It plays a major role in glucose metabolism by N-terminal truncation and inactivation of the incretins glucagon-like peptide-1 (GLP) and gastric inhibitory protein (GIP). In 2006, DPP4 inhibitors have been introduced to clinics and have been demonstrated to efficiently enhance the endogenous insulin secretion via prolongation of the half-life of GLP-1 and GIP in patients. However, a large number of studies demonstrate clearly that CD26/DPP4 also plays an integral role in the immune system, particularly in T cell activation. Therefore, inhibition of DPP4 might represent a double-edged sword. Apart from the metabolic benefit, the associated immunological effects of long term DPP4 inhibition on regulatory processes such as T cell homeostasis, maturation and activation are not understood fully at this stage. The current data point to an important role for CD26/DPP4 in maintaining lymphocyte composition and function, T cell activation and co-stimulation, memory T cell generation and thymic emigration patterns during immune-senescence. In rodents, critical immune changes occur at baseline levels as well as after in-vitro and in-vivo challenge. In patients receiving DPP4 inhibitors, evidence of immunological side effects also became apparent. The scope of this review is to recapitulate the role of CD26/DPP4 in the immune system regarding its pharmacological inhibition and T cell-dependent immune regulation.

The protective effect of vildagliptin in chronic experimental cyclosporine A-induced hepatotoxicity

The study examined the effect of dipeptidyl peptidase-4 (DPP-4) inhibitor, vildagliptin, in cyclosporine (CsA)-induced hepatotoxicity. Rats were divided into 4 groups treated for 28 days: control (vehicle), vildagliptin (10 mg/kg, orally), CsA (20 mg/kg, s.c.), and CsA-vildagliptin group. Liver function was assessed by measuring serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyltransferase (γGT), lactate dehydrogenase (LDH), and albumin, and histopathological changes of liver were examined. Oxidative stress markers were evaluated. Assessment of nuclear factor-kappa B (NF-κB) activity in hepatic nuclear extract, serum DPP-4, and expression of Bax and Bcl2 were also done. CsA-induced hepatotoxicity was evidenced by increase in serum levels of AST, ALT, and γGT; a decrease in serum albumin; and a significant alteration in hepatic architecture. Also, significant increase in thiobarbituric acid reactive substance (TBARS) and decrease in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione (GSH) levels, increased expression Bax proteins with deceased expression of Bcl2, and increased hepatic activity of NF-κB and serum DPP-4 level were observed upon CsA treatment. Vildagliptin significantly improved all altered parameters induced by CsA administration. Vildagliptin has the potential to protect the liver against CsA-induced hepatotoxicity by reducing oxidative stress, DPP-4 activity, apoptosis, and inflammation.

Pharmacological Modulators of Endoplasmic Reticulum Stress in Metabolic Diseases

The endoplasmic reticulum (ER) is the principal organelle responsible for correct protein folding, a step in protein synthesis that is critical for the functional conformation of proteins. ER stress is a primary feature of secretory cells and is involved in the pathogenesis of numerous human diseases, such as certain neurodegenerative and cardiometabolic disorders. The unfolded protein response (UPR) is a defense mechanism to attenuate ER stress and maintain the homeostasis of the organism. Two major degradation systems, including the proteasome and autophagy, are involved in this defense system. If ER stress overwhelms the capacity of the cell's defense mechanisms, apoptotic death may result. This review is focused on the various pharmacological modulators that can protect cells from damage induced by ER stress. The possible mechanisms for cytoprotection are also discussed.

The consumer welfare implications of governmental policies and firm strategy in markets for medicines

This paper empirically examines the consumer welfare implications of changes in government policies related to patent protection and compulsory licensing in the Indian market for oral anti-diabetic (OAD) medicines. In contrast to previous studies on the impact of pharmaceutical patents in India, we observe, and estimate the welfare effects accruing from differential pricing and voluntary licensing strategies of patent-holding innovator firms. Three novel molecules belonging to the dipeptidyl peptidase-4 (DPP-4) inhibitor class of OADs have been launched in India by the patent holders, at lower prices than those prevailing in the developed countries. Using aggregate market transaction data, we structurally estimate demand and supply and use the parameter estimates in our model to simulate consumer welfare under various counterfactual scenarios. Our results suggest that the introduction of DPP-4 inhibitors generated a consumer surplus gain of around 7.6 cents per day for a typical DPP-4 inhibitor user under the existing differential pricing and voluntary licensing strategies. If the innovators decide to price at developed-country levels, this surplus is eliminated almost entirely. The issuance of compulsory licensing does not always improve consumer welfare because if innovators defer or delay the introduction of new drugs in response, the loss in consumer welfare could be substantial.

Structure-activity-relationship of amide and sulfonamide analogs of omarigliptin

A series of novel substituted-[(3R)-amino-2-(2,5-difluorophenyl)]tetrahydro-2H-pyran analogs have been prepared and evaluated as potent, selective and orally active DPP-4 inhibitors. These efforts lead to the discovery of a long acting DPP-4 inhibitor, omarigliptin (MK-3102), which recently completed phase III clinical development and has been approved in Japan.

Serum Levels of Soluble CD26/Dipeptidyl Peptidase-IV in Type 2 Diabetes Mellitus and Its Association with Metabolic Syndrome and Therapy with Antidiabetic Agents in Malaysian Subjects

Background

A soluble form of CD26/dipeptidyl peptidase-IV (sCD26/DPP-IV) induces DPP-IV enzymatic activity that degrades incretin. We investigated fasting serum levels of sCD26/DPP-IV and active glucagon-like peptide-1 (GLP-1) in Malaysian patients with type 2 diabetes mellitus (T2DM) with and without metabolic syndrome (MetS), as well as the associations between sCD26/DPP-IV levels, MetS, and antidiabetic therapy.

Methods

We assessed sCD26/DPP-IV levels, active GLP-1 levels, body mass index (BMI), glucose, insulin, A1c, glucose homeostasis indices, and lipid profiles in 549 Malaysian subjects (including 257 T2DM patients with MetS, 57 T2DM patients without MetS, 71 non-diabetics with MetS, and 164 control subjects without diabetes or metabolic syndrome).

Results

Fasting serum levels of sCD26/DPP-IV were significantly higher in T2DM patients with and without MetS than in normal subjects. Likewise, sCD26/DPP-IV levels were significantly higher in patients with T2DM and MetS than in non-diabetic patients with MetS. However, active GLP-1 levels were significantly lower in T2DM patients both with and without MetS than in normal subjects. In T2DM subjects, sCD26/DPP-IV levels were associated with significantly higher A1c levels, but were significantly lower in patients using monotherapy with metformin. In addition, no significant differences in sCD26/DPP-IV levels were found between diabetic subjects with and without MetS. Furthermore, sCD26/DPP-IV levels were negatively correlated with active GLP-1 levels in T2DM patients both with and without MetS. In normal subjects, sCD26/DPP-IV levels were associated with increased BMI, cholesterol, and LDL-cholesterol (LDL-c) levels.

Conclusion

Serum sCD26/DPP-IV levels increased in T2DM subjects with and without MetS. Active GLP-1 levels decreased in T2DM patients both with and without MetS. In addition, sCD26/DPP-IV levels were associated with Alc levels and negatively correlated with active GLP-1 levels. Moreover, metformin monotherapy was associated with reduced sCD26/DPP-IV levels. In normal subjects, sCD26/DPP-IV levels were associated with increased BMI, cholesterol, and LDL-c.

NPY1-36 and PYY1-36 activate cardiac fibroblasts: an effect enhanced by genetic hypertension and inhibition of dipeptidyl peptidase 4

Cardiac sympathetic nerves release neuropeptide Y (NPY)1-36, and peptide YY (PYY)1-36 is a circulating peptide; therefore, these PP-fold peptides could affect cardiac fibroblasts (CFs). We examined the effects of NPY1-36 and PYY1-36 on the proliferation of and collagen production ([(3)H]proline incorporation) by CFs isolated from Wistar-Kyoto (WKY) normotensive rats and spontaneously hypertensive rats (SHRs). Experiments were performed with and without sitagliptin, an inhibitor of dipeptidyl peptidase 4 [DPP4; an ectoenzyme that metabolizes NPY1-36 and PYY1-36 (Y1 receptor agonists) to NPY3-36 and PYY3-36 (inactive at Y1 receptors), respectively]. NPY1-36 and PYY1-36, but not NPY3-36 or PYY3-36, stimulated proliferation of CFs, and these effects were more potent than ANG II, enhanced by sitagliptin, blocked by BIBP3226 (Y1 receptor antagonist), and greater in SHR CFs. SHR CF membranes expressed more receptor for activated C kinase (RACK)1 [which scaffolds the Gi/phospholipase C (PLC)/PKC pathway] compared with WKY CF membranes. RACK1 knockdown (short hairpin RNA) and inhibition of Gi (pertussis toxin), PLC (U73122), and PKC (GF109203X) blocked the proliferative effects of NPY1-36. NPY1-36 and PYY1-36 stimulated collagen production more potently than did ANG II, and this was enhanced by sitagliptin and greater in SHR CFs. In conclusion, 1) NPY1-36 and PYY1-36, via the Y1 receptor/Gi/PLC/PKC pathway, activate CFs, and this pathway is enhanced in SHR CFs due to increased localization of RACK1 in membranes; and 2) DPP4 inhibition enhances the effects of NPY1-36 and PYY1-36 on CFs, likely by inhibiting the metabolism of NPY1-36 and PYY1-36. The implications are that endogenous NPY1-36 and PYY1-36 could adversely affect cardiac structure/function by activating CFs, and this may be exacerbated in genetic hypertension and by DPP4 inhibitors.

Effect of Glucagon-like Peptide-1 on the Differentiation of Adipose-derived Stem Cells into Osteoblasts and Adipocytes

Objectives

Glucagon-like peptide-1 (GLP-1) is an intestinally secreted hormone and it plays an important role in the regulation of glucose homeostasis. However, the possible role of GLP-1 in the differentiation of adipose-derived stem cells (ADSCs) remains unknown. Therefore this study investigated the effect of GLP-1 on the differentiation of ADSCs into osteoblasts and adipocytes.

Methods

ADSCs were isolated from human adipose tissues of the abdomens, cultured and characterized by flow cytometry and multi-lineage potential assay. ADSCs were induced in osteogenic and adipogenic media treated with two different doses (10 and 100 nM) of GLP-1, and then the effect of GLP-1 on differentiation of ADSCs into osteoblast and adipocyte was examined. The signaling pathway involved in these processes was also examined.

Results

Isolated human ADSCs expressed mesenchymal stem cell (MSC) specific markers as well as GLP-1 receptor (GLP-1R) proteins. They also showed multiple-lineage potential of MSC. GLP-1 was upregulated the activity and mRNA expression of osteoblast-specific marker, alkaline phosphatase and the mineralization of calcium. In contrast, GLP-1 significantly suppressed the expression of adipocyte-specific markers, peroxisome proliferator-activated receptor gamma (PPAR-γ), lipoprotein lipase (LPL) and adipocyte protein 2 (AP2). This decreased expression of adipocyte specific markers caused by GLP-1 was significantly reversed by the treatment of extracellular signal-regulated kinase (ERK) inhibitor, PD98059 (P < 0.05).

Conclusion

This result demonstrates that GLP-1 stimulates osteoblast differentiation in ADSCs, whereas it inhibits adipocyte differentiation. The ERK signaling pathway seems to be involved in these differentiation processes mediated by GLP-1.

Linagliptin/metformin HCl (fixed combination therapy) for the treatment of Type 2 diabetes mellitus

By the year 2030, diabetes mellitus will globally become the seventh leading cause of death. Currently, 382 million individuals worldwide have diabetes mellitus, with 80% residing in low- and middle-income countries. At present, Type 2 diabetes mellitus (T2DM) accounts for 85-95% of the diabetes burden in high-income countries. Alarmingly, this figure may be higher in the low- and middle-income nations. In an effort to combat this silent but deadly disease, pharmaceutical manufacturers have developed a host of different agents, each targeting a specific biochemical pathway. Among the most recent additions to this armament is linagliptin/metformin HCl, a fixed combination therapy compound manufactured by Boehringer Ingelheim. This novel formulation combines metformin, an insulin sensitizer, with linagliptin, a dipeptidyl peptidase-4 enzyme inhibitor. This review will discuss the pharmacokinetic properties of this molecule, assess clinical efficacy and gauge its place in the treatment algorithm for T2DM.

Development of multiplex mass spectrometric immunoassay for detection and quantification of apolipoproteins C-I, C-II, C-III and their proteoforms

The impetus for discovery and evaluation of protein biomarkers has been accelerated by recent development of advanced technologies for rapid and broad proteome analyses. Mass spectrometry (MS)-based protein assays hold great potential for in vitro biomarker studies. Described here is the development of a multiplex mass spectrometric immunoassay (MSIA) for quantification of apolipoprotein C-I (apoC-I), apolipoprotein C-II (apoC-II), apolipoprotein C-III (apoC-III) and their proteoforms. The multiplex MSIA assay was fast (∼ 40 min) and high-throughput (96 samples at a time). The assay was applied to a small cohort of human plasma samples, revealing the existence of multiple proteoforms for each apolipoprotein C. The quantitative aspect of the assay enabled determination of the concentration for each proteoform individually. Low-abundance proteoforms, such as fucosylated apoC-III, were detected in less than 20% of the samples. The distribution of apoC-III proteoforms varied among samples with similar total apoC-III concentrations. The multiplex analysis of the three apolipoproteins C and their proteoforms using quantitative MSIA represents a significant step forward toward better understanding of their physiological roles in health and disease.

Covalent inhibitors in drug discovery: from accidental discoveries to avoided liabilities and designed therapies

Drugs that covalently bond to their biological targets have a long history in drug discovery. A look at drug approvals in recent years suggests that covalent drugs will continue to make impacts on human health for years to come. Although fraught with concerns about toxicity, the high potencies and prolonged effects achievable with covalent drugs may result in less-frequent drug dosing and in wide therapeutic margins for patients. Covalent inhibition can also dissociate drug pharmacodynamics (PD) from pharmacokinetics (PK), which can result in desired drug efficacy for inhibitors that have short systemic exposure. Evidence suggests that there is a reduced risk for the development of resistance against covalent drugs, which is a major challenge in areas such as oncology and infectious disease.

Gemigliptin improves renal function and attenuates podocyte injury in mice with diabetic nephropathy

Podocytes participate in the formation and regulation of the glomerular filtration barrier. Loss of podocytes occurs during the early stages of diabetic nephropathy and impairs glomerular filtration. Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used as anti-diabetic agents in clinical practice. In this study, we showed that gemigliptin, a novel DPP-4 inhibitor, reduced podocyte apoptosis in type 2 diabetic db/db mice without reducing hyperglycemia. Gemigliptin (100mg/kg/day) was administered orally for 12 weeks in db/db mice. Blood glucose levels and albuminuria were measured. The renal cortex was collected for histological examination, and molecular assays were used to detect 8-hydroxydeoxyguanosine, advanced oxidation protein products (AOPP), the receptor for advanced glycation end products (RAGE), and integrin-linked kinase (ILK). Type 2 diabetic db/db mice exhibited albuminuria, renal histopathological changes, and podocyte loss. Administration of gemigliptin to db/db mice suppressed albuminuria, enzyme activity and expression of DPP-4, and podocyte apoptosis. The effect of gemigliptin on diabetes-induced podocyte loss was associated with the suppression of oxidative damage, AOPP accumulation, RAGE expression, and ILK expression. These results indicate the possible benefits of using gemigliptin in diabetes patients to treat renal impairment without affecting glycemic control.

A grape seed extract increases active glucagon-like peptide-1 levels after an oral glucose load in rats

We have previously reported that procyanidins, a class of flavonoids, improve glycemia and exert an incretin-like effect, which was linked to their proven inhibitory effect on the dipeptidyl-peptidase 4 (DPP4) activity. However, their actual effect on incretin levels has not been reported yet. Therefore, in the present study we have evaluated whether a grape seed extract enriched in procyanidins (GSPE) modulates plasma incretin levels and attempted to determine the mechanisms involved. An acute GSPE treatment in healthy Wistar female rats prior to an oral glucose load induced an increase in plasma active glucagon-like peptide-1 (GLP-1), which was accompanied by an increase in the plasma insulin/glucose ratio and a simultaneous decrease in glucose levels. In agreement with our previous studies, the intestinal DPP4 activity was inhibited by the GSPE treatment. We have also assayed in vitro whether this inhibition occurs in inner intestinal tissues close to GLP-1-producing cells, such as the endothelium of the capillaries. We have found that the main compounds absorbed by intestinal CaCo-2 cells after an acute treatment with GSPE are catechin, epicatechin, B2 dimer and gallic acid, and that they inhibit the DPP4 activity in endothelial HUVEC cells in an additive way. Moreover, an increase in plasma total GLP-1 levels was found, suggesting an increase in GLP-1 secretion. In conclusion, our results show that GSPE improves glycemia through its action on GLP-1 secretion and on the inhibition of the inner intestinal DPP4 activity, leading to an increase in active GLP-1 levels, which, in turn, may affect the insulin release.

Characteristics and Outcomes of Middle East Respiratory Syndrome Coronavirus Patients Admitted to an Intensive Care Unit in Jeddah, Saudi Arabia

BACKGROUND

An increasing number of patients are being infected with Middle East respiratory syndrome coronavirus (MERS-CoV) since the first case was identified in September 2012. We report the characteristics and outcomes of MERS-CoV-confirmed patients who developed critical illness requiring admission to an intensive care unit (ICU).

METHODS

We conducted a prospective cohort study of all MERS-CoV-confirmed cases who were admitted to our ICU from March 20, 2014, till June 1, 2014. Presenting symptoms, comorbid conditions, and details of their ICU stay were recorded.

RESULTS

Eight patients were admitted to the ICU with MERS-CoV infection. All had signs of respiratory distress with 7 requiring mechanical ventilation. Three patients were health care workers. In all, 6 patients had comorbid conditions and 5 patients developed multiorgan system failure (MOSF). In all, 5 patients expired, 2 were discharged alive, and 1 remained intubated at the end of the study period.

CONCLUSIONS

Middle East respiratory syndrome coronavirus carries a high mortality rate in patients who require ICU admission, with a significant number of patients developing MOSF. Further investigation is needed to determine optimal management guidelines for these patients.

Linagliptin improves glycemic control after 1 year as add-on therapy to basal insulin in Asian patients with type 2 diabetes mellitus

OBJECTIVE

To evaluate the efficacy and long-term safety of linagliptin added to basal insulin in Asian patients with type 2 diabetes mellitus (T2DM) inadequately controlled by basal insulin with/without oral agents.

RESEARCH DESIGN AND METHODS

This was a post hoc analysis of Asian patients from a global ≥52 week study in which patients on basal insulin were randomized (1:1) to double-blind treatment with linagliptin 5 mg once daily or placebo (NCT00954447). Basal insulin dose remained stable for 24 weeks, after which adjustments could be made according to the investigator's discretion to improve glycemic control. The primary endpoint was the mean change in glycated hemoglobin (HbA1c) from baseline to 24 weeks.

RESULTS

Data were available for 154 Asian patients (80 linagliptin, 74 placebo). Baseline HbA1c (standard deviation [SD]) was 8.6 (0.9)% (70 [10] mmol/mol). The placebo-corrected mean change (standard error [SE]) in HbA1c from baseline was -0.9 (0.1)% (-10 [1] mmol/mol) (95% confidence interval [CI]: -1.2, -0.7; p<0.0001) at Week 24 and -0.9 (0.1)% (-10 [1] mmol/mol) (95% CI: -1.1, -0.6; p<0.0001) at Week 52. The frequency of adverse events (linagliptin 81.3%, placebo 91.9%) and hypoglycemia (Week 24: linagliptin 25.0%, placebo 25.7%; treatment end: linagliptin 28.8%, placebo 35.1%) was similar between groups. By Week 52, changes (SE) in mean body weight were similar in both groups (linagliptin -0.67 [0.26] kg, placebo -0.38 [0.25] kg).

CONCLUSIONS

This study was limited by the post hoc nature of the analysis and the small number of patients in the subgroup. However, the results suggest that linagliptin significantly improves glycemic control in Asian patients with T2DM inadequately controlled by basal insulin, without increasing the risk for hypoglycemia or weight gain. ClinicalTrials identifier: NCT00954447.

Novel DPP-4 inhibitors against diabetes

DPP-4 specifically degrades the incretin hormone GLP-1 and GIP, both of which are vital modulators of blood glucose homeostasis. Attributed to its potential biological function, DPP-4 inhibition has presently represented an attractive therapeutic strategy for treating diabetes and aroused a significant interest in the pharmaceutical industry. Chemical stability, selectivity and pharmacokinetic properties have been continuously emphasized during the long journey of R&D centered on DPP-4 inhibitors. The current landscape of the development of DPP-4 inhibitors is outlined in this review, with a focus on rational drug design and structural optimization to pursue chemical stability, selectivity and favorable pharmacokinetic properties. In addition, the structure-activity relationships, based on reported DPP-4 inhibitors, will be discussed.

How our bodies fight amyloidosis: effects of physiological factors on pathogenic aggregation of amyloidogenic proteins

The process of protein aggregation from soluble amyloidogenic proteins to insoluble amyloid fibrils plays significant roles in the onset of over 30 human amyloidogenic diseases, such as Prion disease, Alzheimer's disease and type 2 diabetes mellitus. Amyloid deposits are commonly found in patients suffered from amyloidosis; however, such deposits are rarely seen in healthy individuals, which may be largely attributed to the self-regulation in vivo. A vast number of physiological factors have been demonstrated to directly affect the process of amyloid formation in vivo. In this review, physiological factors that influence amyloidosis, including biological factors (chaperones, natural antibodies, enzymes, lipids and saccharides) and physicochemical factors (metal ions, pH environment, crowding and pressure, etc.), together with the mechanisms underlying these proteostasis effects, are summarized.

Pharmaceuticals that contain polycyclic hydrocarbon scaffolds

This review comprehensively explores approved pharmaceutical compounds that contain polycyclic scaffolds and the properties that these skeletons convey.

Effect of dipeptidyl peptidase 4 inhibition on arterial blood pressure is context dependent

Because the effects of dipeptidyl peptidase 4 (DPP4) inhibitors on blood pressure are controversial, we examined the long-term effects of sitagliptin (80 mg/kg per day) on blood pressure (radiotelemetry) in spontaneously hypertensive rats (SHR), Wistar-Kyoto rats, and Zucker Diabetic-Sprague Dawley rats (metabolic syndrome model). In SHR, chronic (3 weeks) sitagliptin significantly increased systolic, mean, and diastolic blood pressures by 10.3, 9.2, and 7.9 mm Hg, respectively, a response abolished by coadministration of BIBP3226 (2 mg/kg per day; selective Y1-receptor antagonist). Sitagliptin also significantly increased blood pressure in SHR treated with hydralazine (vasodilator; 25 mg/kg per day) or enalapril (angiotensin-converting enzyme inhibitor; 10 mg/kg per day). In Wistar-Kyoto rats, chronic sitagliptin slightly decreased systolic, mean, and diastolic blood pressures (-1.8, -1.1, and -0.4 mm Hg, respectively). In Zucker Diabetic-Sprague Dawley rats, chronic sitagliptin decreased systolic, mean, and diastolic blood pressures by -7.7, -5.8, and -4.3 mm Hg, respectively, and did not alter the antihypertensive effects of chronic enalapril. Because DPP4 inhibitors impair the metabolism of neuropeptide Y1-36 (NPY1-36; Y1-receptor agonist) and glucagon-like peptide (GLP)-1(7-36)NH2 (GLP-1 receptor agonist), we examined renovascular responses to NPY1-36 and GLP-1(7-36)NH2 in isolated perfused SHR and Zucker Diabetic-Sprague Dawley kidneys pretreated with norepinephrine (to induce basal tone). In Zucker Diabetic-Sprague Dawley kidneys, NPY1-36 and GLP-1(7-36)NH2 exerted little, if any, effect on renovascular tone. In contrast, in SHR kidneys, both NPY1-36 and GLP-1(7-36)NH2 elicited potent and efficacious vasoconstriction.

IN CONCLUSION

(1) The effects of DPP4 inhibitors on blood pressure are context dependent; (2) The context-dependent effects of DPP4 inhibitors are due in part to differential renovascular responses to DPP4’s most important substrates (NPY1–36 and GLP-1(7–36)NH2) [corrected]; (3) Y1 receptor antagonists may prevent the prohypertensive and possibly augment the antihypertensive effects of DPP4 inhibitors.

Linagliptin improved glycaemic control without weight gain or hypoglycaemia in patients with type 2 diabetes inadequately controlled by a combination of metformin and pioglitazone: a 24-week randomized, double-blind study

AIMS

To investigate the efficacy and safety of the dipeptidyl peptidase-4 inhibitor linagliptin in patients with Type 2 diabetes mellitus inadequately controlled by a combination of metformin and pioglitazone.

METHODS

This was a multi-centre, phase 3, randomized, double-blind, placebo-controlled study comparing linagliptin 5 mg once daily (n = 183) and placebo (n = 89) as add-on to metformin and pioglitazone. The primary endpoint was the change from baseline in glycated haemoglobin (HbA1c ) after 24 weeks.

RESULTS

The placebo-corrected adjusted mean (se) change in HbA1c from baseline to 24 weeks was -6 (1) mmol/mol [-0.57 (0.13)%] (P < 0.0001). In patients with baseline HbA1c ≥ 53 mmol/mol (7.0%), 32.4% of patients in the linagliptin group and 13.8% in the placebo group achieved HbA1c < 53 mmol/mol (7.0%) (odds ratio 2.94; P = 0.0033). The placebo-corrected adjusted mean (se) change from baseline in fasting plasma glucose at week 24 was -0.57 (0.26) mmol/l [-10.4 (4.7) mg/dl] (P = 0.0280). The incidence of serious adverse events was 2.2% with linagliptin and 3.4% with placebo. Investigator-defined hypoglycaemia occurred in 5.5% of the linagliptin group and 5.6% of the placebo group. No meaningful changes in mean body weight were noted for either group.

CONCLUSIONS

Linagliptin as add-on therapy to metformin and pioglitazone produced significant and clinically meaningful improvements in glycaemic control, without an additional risk of hypoglycaemia or weight gain (Clinical Trials Registry No: NCT 00996658).

Saxagliptin efficacy and safety in patients with type 2 diabetes receiving concomitant statin therapy

AIMS

To examine whether concomitant statin therapy affects glycemic control with saxagliptin 2.5 and 5mg/d in patients with type 2 diabetes mellitus (T2DM).

METHODS

Efficacy and safety were analyzed post hoc for pooled data from 9 saxagliptin randomized, placebo-controlled trials with a primary 24-week treatment period (4 monotherapy, 2 add-on to metformin, 1 each add-on to a sulfonylurea, thiazolidinedione, or insulin±metformin). Safety was also assessed in an 11-study, 24-week pool and an extended 20-study pool, which included 9 additional 4- to 52-week randomized studies. Comparisons were performed for patient groups defined by baseline statin use.

RESULTS

Saxagliptin produced greater mean reductions in glycated hemoglobin than placebo, with no interaction between treatment and baseline statin use (P=0.47). In patients receiving saxagliptin 2.5 and 5mg and placebo, the proportion of patients with ≥1 adverse event (AE) was 78.1%, 64.0%, and 63.2%, respectively, in patients with any statin use and 70.6%, 57.9%, and 55.0% in patients with no statin use. Serious AEs, deaths, and symptomatic confirmed hypoglycemia (fingerstick glucose ≤50mg/dL) were few and similar, irrespective of baseline statin use.

CONCLUSIONS

Saxagliptin improves glycemic control and is generally well tolerated in patients with T2DM, irrespective of concomitant statin therapy.

DPP4 inhibitors increase differentially the expression of surfactant proteins in Fischer 344 rats

AIM

Intact surface active agent (surfactant) composed of surfactant-associated proteins (SPs) and lipids is necessary for respiration and prevents alveoli from collapsing. CD26, a transmembrane glycoprotein exerting dipeptidyl peptidase activity (DPP4), highly expressed in lung parenchyma, is involved in inflammatory processes. A pharmacological inhibition of DPP4 influenced not only the inflammation but also elevated the SPs. Thus, DPP4 inhibitors may be a novel drug for treatment of diseases with surfactant deficiency. Therefore, we tested firstly the hypothesis that DPP4 inhibitors increase the expression of SPs in healthy rats.

METHODS

SP mRNA and protein expression were determined different times after nebulization of aerosolized DPP4 inhibitors [L-isoleucine-thiazolidide (L-Ile-Thia), L-valine-pyrrolidide (L-Val-Pyrr)], budesonide, saline or stereoisomers.

RESULTS

Compared with negative controls (1) L-Ile-Thia as well as budesonide led to a significant higher and L-Val-Pyrr had the tendency to a significant higher expression of SP-A mRNA 6 h after nebulization, (2) the expression of SP-D mRNA increased significantly 6 h after nebulization with L-Ile-Thia and 3 and 6 h after nebulization with Val-pyrr, (3) SP-B mRNA levels showed significantly higher values 3 and 6 h after nebulization with L-Val-Pyrr, (4) protein levels of SP-A, SP-B and SP-C were elevated significantly 6 h after nebulization with L-Val-Pyrr as well as with budesonide, and (5) phospholipids were also increased in response to DPP4 inhibition; the minimal surface tension was comparable.

CONCLUSION

DPP4 inhibition influence differently the expression of surfactant proteins in healthy rats and may be suitable to elevate surfactant synthesis in different diseases accompanied with surfactant deficiencies.

HD047703, a New Promising Anti-Diabetic Drug Candidate: In Vivo Preclinical Studies

G-protein coupled receptor 119 (GPR119) has emerged as a novel target for the treatment of type 2 diabetes mellitus. GPR119 is involved in glucose-stimulated insulin secretion (GSIS) from the pancreatic β-cells and intestinal cells. In this study, we identified a novel small-molecule GPR119 agonist, HD047703, which raises intracellular cAMP concentrations in pancreatic β-cells and can be expected to potentiate glucose-stimulated insulin secretion from human GPR119 receptor stably expressing cells (CHO cells). We evaluated the acute efficacy of HD047703 by the oral glucose tolerance test (OGTT) in normal C57BL/6J mice. Then, chronic administrations of HD047703 were performed to determine its efficacy in various diabetic rodent models. Single administration of HD047703 caused improved glycemic control during OGTT in a dose-dependent manner in normal mice, and the plasma GLP-1 level was also increased. With respect to chronic efficacy, we observed a decline in blood glucose levels in db/db, ob/ob and DIO mice. These results suggest that HD047703 may be a potentially promising anti-diabetic agent.

Control of cardiovascular risk factors in revascularized patients with diabetes: a subanalysis of the ICP-Bypass study

INTRODUCTION AND OBJECTIVES

Patients with type 2 diabetes and revascularized coronary disease are a group with very high cardiovascular risk that has been rarely studied. This ICP-Bypass substudy analyzes the clinical characteristics and risk factor control of these patients.

METHODS

The analysis selected patients with type 2 diabetes who had participated in an earlier multicenter, observational, cross-sectional study (ICP-Bypass) conducted in 2293 patients > 18 years of age who had undergone coronary surgery or percutaneous coronary intervention. Demographic and therapeutic variables, as well as clinical and analytical parameters, were collected and comparatively analyzed.

RESULTS

The mean age (standard deviation) of the 771 diabetic patients included in the analysis was 67.7 (9.6) years (71.4% men; mean time since revascularization, 3.5 years). Most (57.8%) were receiving treatment with oral hypoglycemics alone, whereas 30.4% were receiving insulin alone or in combination. The mean glycohemoglobin figure was 7.1% (in 70%,<7.5%); 74.8% had been diagnosed with dyslipidemia. Mean low-density lipoprotein cholesterol was 93.5 mg/dL (in 73%, > 70 mg/dL). Among these patients, 93.6% were receiving statins and 18.7% a statin combined with ezetimib. A total of 78.1% had been diagnosed with hypertension; systolic/diastolic blood pressure was < 130/80 mmHg in 52% and < 140/90 mmHg in 93%.

CONCLUSIONS

Cardiovascular risk and prevention may be improved in revascularized diabetic patients in Spain through further control of risk factors, particularly dyslipidemia. Patients with glycohemoglobin > 7.5% should be individually assessed in terms of glycemic targets.

Effects of dipeptidyl-peptidase 4 inhibitor about vascular inflammation in a metabolic syndrome model

Background

In this study, we used vidagliptin(V) to examine the role of the DDP-IV, incretin system component, in the activation of different molecular inflammatory cytokines, NF-kB and VCAM-1 to generate a microenvironment that supports cardiovascular remodeling.

Methods

Male WKY and SHR were separated into five groups: Control, FFR: WKY rats receiving a 10% (w/v) fructose solution during all 12 weeks, SHR, FFHR: SHR receiving a 10% (w/v) fructose solution during all 12 weeks and FFHR+V: (5 mg/kg per day for 6 weeks) (n = 8 each group). Metabolic variables and systolic blood pressure were measured. The TBRAS, eNOS activity, and NAD(P)H oxidase activity were estimated to evaluate oxidative stress. Cardiac and vascular remodeling were evaluated. To assess the cytokine, NF-kB and VCAM-1 immunostaining techniques were used.

Results

The FFHR experimental model presents metabolic syndrome criteria, vascular and cardiac remodeling, vascular inflammation due to increased expression of NF-kB, VCAM-1, and pro-atherogenic cytokines. Chronic treatment with V was able to reverse total or partiality of variables studied.

Conclusions

Data demonstrated an important effect of DDP-IV in reducing vascular inflammation, accompanied by a favorable reduction in metabolic and structural parameters.

GLP-1R activation for the treatment of stroke: updating and future perspectives

Stroke is the leading cause of adult disability in Westernized societies with increased incidence along ageing and it represents a major health and economical threat. Inactive lifestyle, smoking, hypertension, atherosclerosis, obesity and diabetes all dramatically increase the risk of stroke. While preventive strategies based on lifestyle changes and risk factor management can delay or decrease the likelihood of having a stroke, post stroke pharmacological strategies aimed at minimizing stroke-induced brain damage are highly needed. Unfortunately, several candidate drugs that have shown significant preclinical neuroprotective efficacy, have failed in clinical trials and no treatment for stroke based on neuroprotection is available today. Glucagon-like peptide 1 (GLP-1) is a peptide originating in the enteroendocrine L-cells of the intestine and secreted upon nutrient ingestion. The activation of the GLP-1R by GLP-1 enhances glucose-dependent insulin secretion, suppresses glucagon secretion and exerts multifarious extrapancreatic effects. Stable GLP-1 analogues and inhibitors of the proteolytic enzyme dipeptidyl peptidase 4 (DPP-4) (which counteract endogenous GLP-1 degradation) have been developed clinically for the treatment of type 2 diabetes. Besides their antidiabetic properties, experimental evidence has shown neurotrophic and neuroprotective effects of GLP-1R agonists and DPP-4 inhibitors in animal models of neurological disorders. Herein, we review recent experimental data on the neuroprotective effects mediated by GLP-1R activation in stroke. Due to the good safety profile of the drugs targeting the GLP-1R, we also discuss the high potential of GLP-1R stimulation in view of developing a safe clinical treatment against stroke based on neuroprotection in both diabetic and non-diabetic patients.

Pharmacophore Modeling and Molecular Docking Studies on Pinus roxburghii as a Target for Diabetes Mellitus

The present study attempts to establish a relationship between ethnopharmacological claims and bioactive constituents present in Pinus roxburghii against all possible targets for diabetes through molecular docking and to develop a pharmacophore model for the active target. The process of molecular docking involves study of different bonding modes of one ligand with active cavities of target receptors protein tyrosine phosphatase 1-beta (PTP-1β), dipeptidyl peptidase-IV (DPP-IV), aldose reductase (AR), and insulin receptor (IR) with help of docking software Molegro virtual docker (MVD). From the results of docking score values on different receptors for antidiabetic activity, it is observed that constituents, namely, secoisoresinol, pinoresinol, and cedeodarin, showed the best docking results on almost all the receptors, while the most significant results were observed on AR. Then, LigandScout was applied to develop a pharmacophore model for active target. LigandScout revealed that 2 hydrogen bond donors pointing towards Tyr 48 and His 110 are a major requirement of the pharmacophore generated. In our molecular docking studies, the active constituent, secoisoresinol, has also shown hydrogen bonding with His 110 residue which is a part of the pharmacophore. The docking results have given better insights into the development of better aldose reductase inhibitor so as to treat diabetes related secondary complications.

Sitagliptin prevents inflammation and apoptotic cell death in the kidney of type 2 diabetic animals

This study aimed to evaluate the efficacy of sitagliptin, a dipeptidyl peptidase IV (DPP-IV) inhibitor, in preventing the deleterious effects of diabetes on the kidney in an animal model of type 2 diabetes mellitus; the Zucker diabetic fatty (ZDF) rat: 20-week-old rats were treated with sitagliptin (10 mg/kg bw/day) during 6 weeks. Glycaemia and blood HbA1c levels were monitored, as well as kidney function and lesions. Kidney mRNA and/or protein content/distribution of DPP-IV, GLP-1, GLP-1R, TNF-α, IL-1β, BAX, Bcl-2, and Bid were evaluated by RT-PCR and/or western blotting/immunohistochemistry. Sitagliptin treatment improved glycaemic control, as reflected by the significantly reduced levels of glycaemia and HbA1c (by about 22.5% and 1.2%, resp.) and ameliorated tubulointerstitial and glomerular lesions. Sitagliptin prevented the diabetes-induced increase in DPP-IV levels and the decrease in GLP-1 levels in kidney. Sitagliptin increased colocalization of GLP-1 and GLP-1R in the diabetic kidney. Sitagliptin also decreased IL-1β and TNF-α levels, as well as, prevented the increase of BAX/Bcl-2 ratio, Bid protein levels, and TUNEL-positive cells which indicates protective effects against inflammation and proapoptotic state in the kidney of diabetic rats, respectively. In conclusion, sitagliptin might have a major role in preventing diabetic nephropathy evolution due to anti-inflammatory and antiapoptotic properties.

Interaction potential of Carmegliptin with P-glycoprotein (Pgp) transporter in healthy volunteers

Objective

The primary objective of this study was to investigate the interaction potential of carmegliptin with P-glycoprotein transporter in vitro and in vivo. A secondary objective was to investigate the safety and tolerability of carmegliptin alone or co-administered with verapamil.

Research design and methods

The inhibition potential of carmegliptin was tested in vitro and in a non-randomized open-label study in 16 healthy male volunteers. On day 1 a single dose of carmegliptin (150 mg) was given, followed by a single dose of verapamil (80 mg) on day 7, on day 10 a single dose of carmegliptin (150 mg) together with verapamil (80 mg t.i.d.), and verapamil (80 mg t.i.d.) on days 11–14. Finally, on day 15 a single dose of 150 mg carmegliptin together with 80 mg t.i.d. verapamil was administered. Pharmacokinetic and safety parameters were assessed.

Results

Carmegliptin showed in vitro a low cell permeability and was a good substrate for human MDR1 cells. When carmegliptin was taken with verapamil, the mean exposure and C_max to carmegliptin increased by 29% and 53%, respectively. Increases in exposure were slightly greater on the sixth day of verapamil dosing than on the first day. Verapamil C_max was 17% lower on average when given with carmegliptin than when verapamil was taken alone, and similar trends were apparent in corresponding norverapamil pharmacokinetics. All reported adverse events (n = 28) were mild in intensity, and verapamil had no apparent effect on the pattern or incidence of events.

Conclusions

In vitro, carmegliptin is a substrate but not an inhibitor of human Pgp. Consistently, the co-administration of carmegliptin with verapamil altered the pharmacokinetics of carmegliptin slightly and moderately increased the exposure. Peak exposure of verapamil and its metabolite norverapamil tended to be lower when co-administered with carmegliptin. The combination of carmegliptin and verapamil was generally well tolerated. Although the observed overall changes in pharmacokinetics were small and dose adjustments in clinics are currently not expected, co-administration of carmegliptin with Pgp inhibitors should be carefully monitored in future clinical trials.

Dipeptidyl peptidase-4 inhibitor reduces infarct size and preserves cardiac function via mitochondrial protection in ischaemia-reperfusion rat heart

AIM

We hypothesized that dipeptidyl peptidase (DPP)-4 inhibitor (vildagliptin) reduces fatal arrhythmias, cardiac dysfunction and infarct size caused by ischaemia-reperfusion (I/R) injury via its attenuation of cardiac mitochondrial dysfunction.

METHODS

In total, 26 rats were randomized to receive either 1 mL normal saline solution or 2.0 mg/kg vildagliptin intravenously (n = 13/group) 30 min prior to a 30-min left anterior descending coronary artery occlusion, followed by a 120-min reperfusion. Arrhythmia scores, cardiac functions, infarct size and mitochondrial function were evaluated.

RESULTS

Vildagliptin reduced the infarct size by 44% and mitigated cardiac dysfunction by preserving cardiac function without altering the incidence of cardiac arrhythmias. Vildagliptin increased expression of Bcl-2 and pro-caspase3 in the ischaemic area, whereas Bax and phosphorylated-connexin43/total-connexin43 were not altered. Vildagliptin attenuated cardiac mitochondrial dysfunction by reducing the reactive oxygen species level and mitochondrial swelling.

CONCLUSIONS

DPP-4 inhibitor provides cardioprotection by reducing the infarct size and ameliorating cardiac dysfunction in I/R hearts by attenuating cardiac mitochondrial dysfunction and cardiomyocyte apoptosis.

Molecular dynamic simulations reveal the mechanism of binding between xanthine inhibitors and DPP-4

We apply molecular docking, molecular dynamics (MD) simulation, and binding free energy calculation to investigate and reveal the binding mechanism between five xanthine inhibitors and DPP-4. The electrostatic and van der Waals interactions of the five inhibitors with DPP-4 are analyzed and discussed. The computed binding free energies using MM-PBSA method are in qualitatively agreement with experimental inhibitory potency of five inhibitors. The hydrogen bonds of inhibitors with Ser630 and Asp663 can stabilize the inhibitors in binding sites. The van der Waals interactions, especially the key contacts with His740, Asn710, Trp629, and Tyr666 have larger contributions to the binding free energy and play important roles in distinguishing the variant bioactivity of five inhibitors.