A novel DPP-4 inhibitor teneligliptin scavenges hydroxyl radicals: In vitro study evaluated by electron spin resonance spectroscopy and in vivo study using DPP-4 deficient rats

Teneligliptin Co-Infusion Alleviates Morphine Tolerance by Inhibition of Spinal Microglial Cell Activation in Streptozotocin-Induced Diabetic Rats

Morphine (MOR) is a commonly prescribed drug for the treatment of moderate to severe diabetic neuropathic pain (DNP). However, long-term MOR treatment is limited by morphine analgesic tolerance (MAT). The activation of microglial cells and the release of glia-derived proinflammatory cytokines are known to play an important role in the development of MAT. In this study, we aimed to investigate the effects of the dipeptidyl peptidase-4 inhibitor (DPP-4i) teneligliptin (TEN) on MOR-induced microglial cell activation and MAT in DNP rats. DNP was induced in four groups of male Wistar rats through a single intraperitoneal injection of streptozotocin (STZ) (50 mg/kg, freshly dissolved in 5 mmol/L citrate buffer, pH 4.5). Sham rats were administered with the vehicle. Seven days after STZ injection, all rats were implanted with an intrathecal (i.t) catheter connected to a mini-osmotic pump, divided into five groups, and infused with the following combinations: sham + saline (1 µL/h, i.t), DNP + saline (1 µL/h, i.t), DNP + MOR (15 µg/h, i.t), DNP + TEN (2 µg/h, i.t), and DNP + MOR (15 µg/h, i.t) + TEN (2 µg/h, i.t) for 7 days at a rate of 1 μL/h. The MAT was confirmed through the measurement of mechanical paw withdrawal threshold and tail-flick tests. The mRNA expression of neuroprotective proteins nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1) in the dorsal horn was evaluated by quantitative PCR (qPCR). Microglial cell activation and mononucleate cell infiltration in the spinal cord dorsal horn were assessed by immunofluorescence assay (IFA) and Western blotting (WB). The results showed that co-infusion of TEN with MOR significantly attenuated MAT in DNP rats through the restoration of neuroprotective proteins Nrf2 and HO-1 and suppression of microglial cell activation in the dorsal horn. Though TEN at a dose of 2 μg has mild antinociceptive effects, it is highly effective in limiting MAT.

Teneligliptin Exerts Antinociceptive Effects in Rat Model of Partial Sciatic Nerve Transection Induced Neuropathic Pain

Neuropathic pain (NP), is a chronic pain resulting from nerve injury, with limited treatment options. Teneligliptin (TEN) is a dipeptidyl peptidase-4 inhibitor (DPP-4i) approved to treat type 2 diabetes. DPP-4is prevent the degradation of the incretin hormone glucagon-like peptide 1 (GLP-1) and prolong its circulation. Apart from glycemic control, GLP-1 is known to have antinociceptive and anti-inflammatory effects. Herein, we investigated the antinociceptive properties of TEN on acute pain, and partial sciatic nerve transection (PSNT)-induced NP in Wistar rats. Seven days post PSNT, allodynia and hyperalgesia were confirmed as NP, and intrathecal (i.t) catheters were implanted and connected to an osmotic pump for the vehicle (1 μL/h) or TEN (5 μg/1 μL/h) or TEN (5 μg) + GLP-1R antagonist Exendin-3 (9–39) amide (EXE) 0.1 μg/1 μL/h infusion. The tail-flick response, mechanical allodynia, and thermal hyperalgesia were measured for 7 more days. On day 14, the dorsal horn was harvested and used for Western blotting and immunofluorescence assays. The results showed that TEN had mild antinociceptive effects against acute pain but remarkable analgesic effects against NP. Furthermore, co-infusion of GLP-1R antagonist EXE with TEN partially reversed allodynia but not tail-flick latency. Immunofluorescence examination of the spinal cord revealed that TEN decreased the immunoreactivity of glial fibrillary acidic protein (GFAP). Taken together, our findings suggest that TEN is efficient in attenuation of PSNT-induced NP. Hence, the pleiotropic effects of TEN open a new avenue for NP management.

A Novel Dipeptidyl Peptidase-4 Inhibitor DA-1229 Ameliorates Tubulointerstitial Fibrosis in Cyclosporine Nephrotoxicity in Mice

Cyclosporine A (CyA) is an immunosuppressive agent that induces nephrotoxicity with long-term treatment. The roles of DPP-4 and its inhibitors in cyclosporine nephrotoxicity are not fully understood. Therefore, we investigated the effects of a novel DPP-4 inhibitor, DA-1229, on the progression of renal disease in an experimental cyclosporine nephrotoxicity model. Chronic cyclosporine nephrotoxicity was induced in six-week-old male ICR mice by subcutaneous injections of CyA at a dose of 30 mg/kg for four weeks. Animals were treated with DA-1229 at a dose of 300 mg/kg per day in food for four weeks. Although DPP-4 activity did not increase in the kidneys of mice with induced cyclosporine nephrotoxicity, DA-1229 treatment significantly suppressed DPP-4 activity in both plasma and renal tissues. DPP-4 inhibition by DA-1229 led to significantly decreased albuminuria and urinary excretion of 8-isoprosatane. DPP-4 inhibition also substantially suppressed pro-inflammatory effects, profibrotic molecules, and macrophage infiltration, and led to the improvement in renal structural changes. Our results suggest that DPP-4 inhibition by DA-1229 provides renoprotective effects in an animal model of cyclosporine nephrotoxicity via antioxidant, anti-inflammatory, and anti-fibrotic mechanisms. DPP-4 inhibition may be a useful new therapeutic approach for the management of progressive renal disease in cyclosporine nephrotoxicity.

DPP-4 Inhibitors Have Different Effects on Endothelial Low-Grade Inflammation and on the M1-M2 Macrophage Polarization Under Hyperglycemic Conditions

PURPOSE

We explored the anti-inflammatory role of the DPP-4 inhibitor teneligliptin, using sitagliptin as comparator, in different in vitro models of low-grade inflammation (LGI), evaluating the hyperglycemia-induced endothelial inflammation, the macrophage polarization, and the endothelium-macrophage interaction.

METHODS

The effects of DPP-4 and its inhibitors on macrophage polarization were evaluated in THP-1 cells by measuring mRNA expression of M1-M2 markers. HUVEC cells were used to analyze the effects of DPP-4 inhibitors on endothelial inflammation under normal and high glucose conditions. To evaluate the link between eNO and M1-M2 polarization, HUVECs were transfected with eNOS siRNA and co-cultured with THP-1 cells. The effects of DPP-4 inhibitors on macrophage polarization and eNO content were evaluated in a co-culture model of differentiated THP-1 cells + HUVECs under normal glucose (NG), high glucose (HG) and high metabolic memory (HM) conditions.

RESULTS

DPP-4 regulated M1/M2 macrophage polarization. Teneligliptin reduced M1 and enhanced M2 macrophage phenotype under DPP-4 stimulation, and attenuated hyperglycemia-induced endothelial inflammation. In THP-1 cells co-cultured with eNOS depleted HUVECs, M1 markers were enhanced, while M2 reduced, indicating an important role of eNO in polarization to M2 phenotype. In the co-culture model with HUVECs exposed to HG and HM, teneligliptin reduced M1 and enhanced M2 population, by increasing eNO levels. The anti-inflammatory effects of sitagliptin were not observed in these LGI models.

CONCLUSION

Teneligliptin, but not sitagliptin, has anti-inflammatory effects in the various LGI models, by promoting a switch from M1 toward M2 phenotype and by decreasing hyperglycaemia-induced endothelial inflammation, suggesting that effects for LGI are different among DPP-4 inhibitors.

High glucose-induced PRDX3 acetylation contributes to glucotoxicity in pancreatic β-cells: Prevention by Teneligliptin

Chronic hyperglycemia has deleterious effects on pancreatic β-cell function and survival in type 2 diabetes (T2D) due to the low expression level of endogenous antioxidants in the β-cells. Peroxiredoxin-3 (PRDX3) is a mitochondria specific H202 scavenger and protects the cell from mitochondrial damage. However, nothing is known about how glucotoxicity influences PRDX3 function in the pancreatic beta cells. Exposure of rat insulinoma INS-1 cells and human beta cells (1.1B4) to high glucose conditions (30mM) stimulated acetylation of PRDX3 which facilitates its hyper-oxidation causing mitochondrial dysfunction by SIRT1 degradation. SIRT1 deficiency induces beta cell apoptosis via NOX-JNK-p66Shc signalosome activation. Herein we investigated the direct effect of Teneligliptin, a newer DPP-4 inhibitor on beta-cell function and survival in response to high glucose conditions. Teneligliptin treatment enhances SIRT1 protein levels and activity by USP22, an ubiquitin specific peptidase. Activated SIRT1 prevents high glucose-induced PRDX3 acetylation by SIRT3 resulted in inhibition of PRDX3 hyper-oxidation thereby strengthening the mitochondrial antioxidant defense. Notably, we identify PRDX3 as a novel SIRT3 target and show their physical interaction. Intriguingly, inhibition of SIRT1 activity by EX-527 or SIRT1 siRNA knockdown exacerbated the SIRT3 mediated PRDX3 deacetylation which leads to peroxiredoxin-3 hyper-oxidation and beta-cell apoptosis by the activation of NOX-JNK-p66Shc signalosome. Collectively, our results unveil a novel and first direct effect of high glucose on PRDX3 acetylation on beta-cell dysfunction by impaired antioxidant defense and SIRT1 mediated SIRT3-PRDX3 activation by Teneligliptin suppresses high glucose-mediated mitochondrial dysfunction.

Detection of Hydroxyl Radicals Using Cerium Oxide/Graphene Oxide Composite on Prussian Blue

A composite sensor consisting of two separate inorganic layers of Prussian blue (PB) and a composite of cerium oxide nanoparticles (CeNPs) and graphene oxide (GO), is tested with •OH radicals. The signals from the interaction between the composite layers and •OH radicals are characterized using cyclic voltammetry (CV). The degradation of PB in the presence of H₂O₂ and •OH radicals is observed and its impact on the sensor efficiency is investigated. The results show that the composite sensor differentiates between the solutions with and without •OH radicals by the increase of electrochemical redox current in the presence of •OH radicals. The redox response shows a linear relation with the concentration of •OH radicals where the limit of detection, LOD, is found at 60 µM (100 µM without the PB layer). When additional composite layers are applied on the composite sensor to prevent the degradation of PB layer, the PB layer is still observed to be degraded. Furthermore, the sensor conductivity is found to decrease with the additional layers of composite. Although the CeNP/GO/PB composite sensor demonstrates high sensitivity with •OH radicals at low concentrations, it can only be used once due to the degradation of PB.

DPP (Dipeptidyl Peptidase)-4 Inhibitor Attenuates Ang II (Angiotensin II)-Induced Cardiac Hypertrophy via GLP (Glucagon-Like Peptide)-1-Dependent Suppression of Nox (Nicotinamide Adenine Dinucleotide Phosphate Oxidase) 4-HDAC (Histone Deacetylase) 4 Pathway

Nox4 (NADPH [Nicotinamide adenine dinucleotide phosphate] oxidase 4) is a major source of oxidative stress and is intimately involved in cardiac hypertrophy. DPP (Dipeptidyl peptidase)-4 inhibitor has been reported to regulate Nox4 expression in adipose tissues. However, its effects on Nox4 in cardiac hypertrophy are still unclear. We investigated whether DPP-4 inhibitor could ameliorate cardiac hypertrophy by regulating Nox4 and its downstream targets. Ang II (Angiotensin II; 1.44 mg/kg per day) or saline was continuously infused into C57BL/6J mice with or without teneligliptin (a DPP-4 inhibitor, 30 mg/kg per day) in the drinking water for 1 week. Teneligliptin significantly suppressed plasma DPP-4 activity without any significant changing aortic blood pressure or metabolic parameters such as blood glucose and insulin levels. It attenuated Ang II-induced increases in left ventricular wall thickness and the ratio of heart weight to body weight. It also significantly suppressed Ang II-induced increases in Nox4 mRNA, 4-hydroxy-2-nonenal, and phosphorylation of HDAC4 (histone deacetylase 4), a downstream target of Nox4 and a crucial suppressor of cardiac hypertrophy, in the heart. Exendin-3 (150 pmol/kg per minute), a GLP-1 (glucagon-like peptide 1) receptor antagonist, abrogated these inhibitory effects of teneligliptin on Nox4, 4-hydroxy-2-nonenal, phosphorylation of HDAC4, and cardiac hypertrophy. In cultured neonatal cardiomyocytes, exendin-4 (100 nmol/L, 24 hours), a GLP-1 receptor agonist, ameliorated Ang II-induced cardiomyocyte hypertrophy and decreased in Nox4, 4-hydroxy-2-nonenal, and phosphorylation of HDAC4. Furthermore, exendin-4 prevented Ang II-induced decrease in nuclear HDAC4 in cardiomyocytes. In conclusion, GLP-1 receptor stimulation by DPP-4 inhibitor can attenuate Ang II-induced cardiac hypertrophy by suppressing of the Nox4-HDAC4 axis in cardiomyocytes.

The dipeptidyl peptidase-4 inhibitor, linagliptin, improves cognitive impairment in streptozotocin-induced diabetic mice by inhibiting oxidative stress and microglial activation

OBJECTIVE

Accumulating epidemiological studies have demonstrated that diabetes is an important risk factor for dementia. However, the underlying pathological and molecular mechanisms, and effective treatment, have not been fully elucidated. Herein, we investigated the effect of the dipeptidyl peptidase-4 (DPP-4) inhibitor, linagliptin, on diabetes-related cognitive impairment.

METHOD

Streptozotocin (STZ)-induced diabetic mice were treated with linagliptin (3 mg/kg/24 h) for 17 weeks. The radial arm water maze test was performed, followed by evaluation of oxidative stress using DNP-MRI and the expression of NAD(P)H oxidase components and proinflammatory cytokines and of microglial activity.

RESULTS

Administration of linagliptin did not affect the plasma glucose and body weight of diabetic mice; however, it improved cognitive impairment. Additionally, linagliptin reduced oxidative stress and the mRNA expression of NAD(P)H oxidase component and TNF-α, and the number and body area of microglia, all of which were significantly increased in diabetic mice.

CONCLUSIONS

Linagliptin may have a beneficial effect on diabetes-related dementia by inhibiting oxidative stress and microglial activation, independently of glucose-lowering.

The Unique Pharmacological and Pharmacokinetic Profile of Teneligliptin: Implications for Clinical Practice

Teneligliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that was approved for the treatment of type 2 diabetes mellitus (T2DM) in Japan and Korea and is being researched in several countries. Teneligliptin is a potent, selective, and long-lasting DPP-4 inhibitor with a t_½ of approximately 24 h and unique pharmacokinetic properties: it is metabolized by cytochrome P450 (CYP) 3A4 and flavin-containing monooxygenase 3 (FMO3), or excreted from the kidney in an unchanged form. Because of its multiple elimination pathways, dose adjustment is not needed in patients with hepatic or renal impairment, and it is considered to have a low potential for drug–drug interactions. Clinical studies and postmarketing surveillance show that teneligliptin, administered as monotherapy and/or in combination with antihyperglycemic agents, is effective and well tolerated in T2DM patients, including in elderly patients and those with renal impairment. Furthermore, teneligliptin has antioxidative properties, which induce the antioxidant cascade, as well as ·OH scavenging properties. In addition, it has shown endothelial protective effects in several non-clinical and clinical studies. From its unique profile and clinical data, teneligliptin represents a potential therapeutic option in a wide variety of patients, including elderly diabetic patients and those with renal impairment. The fixed-dose combination (FDC) tablet of teneligliptin and canagliflozin has been approved in Japan; this is the first FDC tablet of a DPP-4 inhibitor and sodium glucose co-transporter 2 inhibitor in Japan, and the third globally. The FDC tablet may also provide additional prescribing and adherence benefits.

Effect of switching to teneligliptin from other dipeptidyl peptidase-4 inhibitors on glucose control and renoprotection in type 2 diabetes patients with diabetic kidney disease

AIMS/INTRODUCTION

The objective of the present study was to elucidate the effect of switching to teneligliptin from other dipeptidyl peptidase-4 (DPP-4) inhibitors on glucose control and renoprotection in type 2 diabetes mellitus patients with diabetic kidney disease.

MATERIALS AND METHODS

The present study was a single-arm, open-label, observational study. A total of 23 patients, who had urinary albumin/creatinine ratios (UACR) ≥30 mg/gCr in their first urine in the early morning, and received other DPP-4 inhibitors and renin-angiotensin system inhibitors, switched to teneligliptin 20 mg/day. After switching to teneligliptin for 24 weeks, we evaluated changes in glycated hemoglobin (HbA1c), fasting plasma glucose levels, plasma DPP-4 activity and UACR.

RESULTS

HbA1c, fasting plasma glucose and UACR values showed no significant change after 24 weeks compared with baseline. However, plasma DPP-4 activity was significantly reduced after 24 weeks (0.57 ± 0.26 nmol/min/mL, P = 0.012, vs baseline), compared with baseline (1.49 ± 1.73 nmol/min/mL), and there was a positive relationship between the change rate of plasma DPP-4 activity (Δ%DPP-4) for 24 weeks and the levels of plasma DPP-4 activity (r = -0.5997, P = 0.0025) and fasting plasma glucose (r = -0.4235, P = 0.0440) at baseline. Additionally, the Δ%DPP-4 for 24 weeks was significantly correlated to the change rate of UACR (r = 0.556, P = 0.0059). However, there was no relationship between Δ%DPP-4 and ΔHbA1c (amount of HbA1c change).

CONCLUSIONS

Switching to teneligliptin from other DPP-4 inhibitors for 24 weeks reduces plasma DPP-4 activity, which is associated with a reduction in albuminuria, independent of the change in glucose levels, in type 2 diabetes mellitus patients with diabetic kidney disease.

Linagliptin Suppresses Electrical and Structural Remodeling in the Isoproterenol Induced Myocardial Injury Model

The effect of DPP-4 inhibitor on the electrical and structural remodeling in myocardial injury has not been evaluated. We hypothesized that linagliptin, DPP-4 inhibitor, suppresses myocardial remodeling in the isoproterenol (ISP)-induced myocardial injury model.Sprague-Dawley rats were assigned to 3 groups: 1) sham group, 2) ISP group (subcutaneous ISP injection of 70 mg/kg), and 3) ISP + linagliptin (ISP + Lin) (5 mg/kg/day, p.o.) group. Serum was sampled on day 1 (acute phase) and day 7 (sub-acute phase) to evaluate derivatives of reactive oxidative metabolites (d-ROMs). The electrophysiological study was performed in sub-acute phase for the evaluation of the ventricular effective refractory period (VERP) and monophasic action potential duration (MAPD). The VERP and MAPD were markedly prolonged in the ISP group in comparison with the sham (MAPD20: 14 ± 6 versus 11 ± 3 ms, MAPD90: 57 ± 8 versus 44 ± 7 ms, VERP: 74 ± 22 versus 38 ± 10 ms, P < 0.05). In contrast in the ISP + Lin group, such prolongations were suppressed, and the parameters were shorter than the ISP group (MAPD20: 9 ± 2 ms, MAPD90: 35 ± 6 ms, VERP: 52 ± 13 ms, P < 0.05). ISP treatment induced myocardial injury. The injured area was reduced in the ISP + Lin group in comparison with the ISP group (P < 0.05). Serum d-ROMs level in acute phase was higher in ISP group than the other 2 groups (sham: 214 ± 55 versus ISP: 404 ± 45 versus ISP + Lin: 337 ± 20 U.CARR, P < 0.05).Linagliptin suppressed structural and electrical changes, possibly through the antioxidative effect, in this myocardial injury model.

7,8-Dihydroxyflavone Protects High Glucose-Damaged Neuronal Cells against Oxidative Stress

Oxidative stress is considered a major contributor in the pathogenesis of diabetic neuropathy and in diabetes complications, such as nephropathy and cardiovascular diseases. Diabetic neuropathy, which is the most frequent complications of diabetes, affect sensory, motor, and autonomic nerves. This study aimed to investigate whether 7,8-dihydroxyflavone (7,8-DHF) protects SH-SY5Y neuronal cells against high glucose-induced toxicity. In the current study, we found that diabetic patients exhibited higher lipid peroxidation caused by oxidative stress than healthy subjects. 7,8-DHF exhibits superoxide anion and hydroxyl radical scavenging activities. High glucose-induced toxicity severely damaged SH-SY5Y neuronal cells, causing mitochondrial depolarization; however, 7,8-DHF recovered mitochondrial polarization. Furthermore, 7,8-DHF effectively modulated the expression of pro-apoptotic protein (Bax) and anti-apoptotic protein (Bcl-2) under high glucose, thus inhibiting the activation of caspase signaling pathways. These results indicate that 7,8-DHF has antioxidant effects and protects cells from apoptotic cell death induced by high glucose. Thus, 7,8-DHF may be developed into a promising candidate for the treatment of diabetic neuropathy.

A Polysaccharide Purified from Morchella conica Pers. Prevents Oxidative Stress Induced by H₂O₂ in Human Embryonic Kidney (HEK) 293T Cells

Morchella conica Pers. (M. conica) has been used both as a medical and edible mushroom and possesses antimicrobial properties and antioxidant activities. However, the antioxidant properties of polysaccharides purified from M. conica have not been studied. The aim of this study was to investigate the in vitro antioxidant properties of a polysaccharide NMCP-2 (neutral M. conica polysaccharides-2) purified from M. conica, as determined by radical scavenging assay and H₂O₂-induced oxidative stress in HEK 293T cells. Results showed that NMCP-2 with an average molecular weight of 48.3 kDa possessed a much stronger chelating ability on ferrous ions and a higher ability to scavenge radical scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) than the other purified fraction of NMCP-1 from M. conica. Moreover, 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetra-zolium bromide (MTT) assay showed that NMCP-2 dose-dependently preserved cell viability of H₂O₂-induced cells. The NMCP-2 pretreated group reduced the generation of reactive oxygen species (ROS) content and increased the mitochondria membrane potential (MMP) levels. In addition, Hoechst 33342 staining revealed cells treated with NMCP-2 declined nuclear condensation. Ultrastructural observation revealed that NMCP-2 pretreatment alleviated the ruptured mitochondria when exposed to H₂O₂. Furthermore, western blot analysis showed that NMCP-2 prevented significant downregulation of the protein expression of Bax, cleaved caspases 3, and upregulated Bcl-2 levels. These results suggest the protective effects of NMCP-2 against H₂O₂-induced injury in HEK 293T cells. NMCP-2 could be used as a natural antioxidant of functional foods and natural drugs.

Comparison of the Effects of Teneligliptin and Sitagliptin, Two Dipeptidyl Peptidase 4 Inhibitors with Different Half-Lives, on Glucose Fluctuation and Glucagon-Like Peptide-1 in Type 2 Diabetes Mellitus

Our purpose was to determine the effects of teneligliptin and sitagliptin, two dipeptidyl peptidase 4 inhibitors (DPP4-Is) with different half-lives, on glycemic variability and glucagon-like peptide-1 (GLP-1) levels in Japanese patients with type 2 diabetes mellitus (T2DM). The study subjects were 14 drug-naïve patients with T2DM who were allocated to either a 20 mg/day teneligliptin group (n = 7) or a 50 mg/day sitagliptin group (n = 7) for 7 days, then switched to the other treatment for another 7 days. Meal tolerance tests were performed at the time of no treatment, and after treatment with each DPP4-Is at supper. We evaluated the effects of each drug on glucose fluctuation using continuous glucose monitoring (CGM). There was no significant difference between the two groups in the primary endpoint (maximum glucose level after supper), nor in the secondary endpoint: area under the curve (AUC) for plasma glucose (≥140 mg/dl) after supper (18:00 - 24:00). Teneligliptin significantly improved the AUC for plasma glucose (≥140 mg/dl) after supper (20:00-24:00) (P = 0.048), and also significantly increased the GLP-1 level at 30 minutes after the meal load (P = 0.030). No serious adverse effects were noted in either group, apart from a few episodes of asymptomatic hypoglycemia. A daily dose of teneligliptin improved the AUC for plasma glucose at 20:00 to 24:00 (≥140 mg/dl) after the meal tolerance test, and also significantly increased the levels of activated GLP-1 after the test meal.

Dipeptidyl peptidase-4 inhibitor enhances restoration of salivary glands impaired by obese-insulin resistance

OBJECTIVE

Chronic high-fat diet consumption causes not only obese- insulin resistance, but also leads to pathological changes in salivary glands, including increased mitochondrial dysfunction, apoptosis, oxidative stress, and inflammation. Dipeptidyl peptidase-4 inhibitor (vildagliptin) is an oral anti-diabetic drug, using for treatment of type 2 diabetes. Vildagliptin has been shown to exert beneficial effects on several organs in cases of obese-insulin resistant condition. However, the effect of vildagliptin on salivary glands impaired by obese-insulin resistance has not been investigated. The hypothesis in this study is that vildagliptin confers beneficial effects on the salivary gland impaired by obese-insulin resistance via decreasing mitochondrial dysfunction, apoptosis, oxidative stress, and inflammation.

DESIGN

Twenty-four male Wistar rats were divided into two groups. Each group was fed with either a normal (ND; n=8) or a high fat diet (HFD; n=16) for 16 weeks. At week 13, the HFD-fed rats were subdivided into 2 subgroups to receive either a vehicle or vildagliptin (3mg/kg/day) for 28days via gavage feeding. ND-fed rats were treated with the vehicle. At the end of treatment, metabolic parameters were examined, and rats were killed. Submandibular glands were removed to appraise inflammatory markers, apoptosis and mitochondrial function.

RESULTS

Vehicle-treated HFD-fed rats developed obese-insulin resistance with an increase in oxidative stress, inflammation, apoptosis, and mitochondrial dysfunction in the salivary glands. Vildagliptin therapy reduced oxidative stress, inflammation, apoptosis and mitochondrial dysfunction in salivary gland of HFD-fed rats.

CONCLUSION

Vildagliptin prevented salivary gland injury occurring due to obese-insulin resistance.

Potential therapeutic interventions for chronic kidney disease-associated sarcopenia via indoxyl sulfate-induced mitochondrial dysfunction

BACKGROUND

Chronic kidney disease (CKD) patients experience skeletal muscle wasting and decreased exercise endurance. Our previous study demonstrated that indoxyl sulfate (IS), a uremic toxin, accelerates skeletal muscle atrophy. The purpose of this study was to examine the issue of whether IS causes mitochondria dysfunction and IS-targeted intervention using AST-120, which inhibits IS accumulation, or mitochondria-targeted intervention using L-carnitine or teneligliptin, a dipeptidyl peptidase-4 inhibitor which retains mitochondria function and alleviates skeletal muscle atrophy and muscle endurance in chronic kidney disease mice.

METHODS

The in vitro effect of IS on mitochondrial status was evaluated using mouse myofibroblast cells (C2C12 cell). The mice were divided into sham or 5/6-nephrectomized (CKD) mice group. Chronic kidney disease mice were also randomly assigned to non-treatment group and AST-120, L-carnitine, or teneligliptin treatment groups.

RESULTS

In C2C12 cells, IS induced mitochondrial dysfunction by decreasing the expression of PGC-1α and inducing autophagy in addition to decreasing mitochondrial membrane potential. Co-incubation with an anti-oxidant, ascorbic acid, L-carnitine, or teneligliptine restored the values to their original state. In CKD mice, the body and skeletal muscle weights were decreased compared with sham mice. Compared with sham mice, the expression of interleukin-6 and atrophy-related factors such as myostatin and atrogin-1 was increased in the skeletal muscle of CKD mice, whereas muscular Akt phosphorylation was decreased. In addition, a reduced exercise capacity was observed for the CKD mice, which was accompanied by a decreased expression of muscular PCG-1α and increased muscular autophagy, as reflected by decreased mitochondria-rich type I fibres. An AST-120 treatment significantly restored these changes including skeletal muscle weight observed in CKD mice to the sham levels accompanied by a reduction in IS levels. An L-carnitine or teneligliptin treatment also restored them to the sham levels without changing IS level.

CONCLUSIONS

Our results indicate that IS induces mitochondrial dysfunction in skeletal muscle cells and provides a potential therapeutic strategy such as IS-targeted and mitochondria-targeted interventions for treating CKD-induced muscle atrophy and decreased exercise endurance.

A unique polysaccharide purified from Hericium erinaceus mycelium prevents oxidative stress induced by H2O2 in human gastric mucosa epithelium cell

Hericium erinaceus (HE) has been used both as a traditional Chinese medicine and home remedy for treatment of gastric and duodenal ulcers and gastritis. EP-1, a purified polysaccharide isolated from HE mycelium, has recently been identified as the active component responsible for HE anti-gastritis activity. Because oxidative stress has been implicated as a pathogenic cause of gastritis and gastric ulcers, EP-1 antioxidant properties were systematically examined in vitro using the human gastric mucosal epithelial cell line, GES-1. Results showed that EP-1 possessed higher oxygen radical absorbance capacity (ORAC) and 2-3 times higher ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals than a hot water extract of commercially available HE fruiting body. A crude mycelial polysaccharide (CMPS) extract of HE, from which EP-1 was purified, showed slightly stronger radical scavenging activity and ORAC than EP-1, with the exception of DPPH-scavenging activity. Antioxidant activities of these extracts were further studied using hydrogen peroxide (H2O2)-abused GES-1 cells; EP-1 dose-dependently preserved cell viability of abused cells as assessed via MTT assay. Moreover, FACS analysis revealed that EP-1 prevented H2O2-induced apoptotic cell death by inhibiting activation of apoptotic cellular signals within mitochondria-dependent apoptotic pathways. CMPS also prevented H2O2-induced oxidative stress, but to a lesser degree than did EP-1, even though CMPS exhibited comparable or stronger in vitro antioxidant activity than did EP-1.

Teneligliptin in Early Diabetic Kidney Disease: An Observation in Asian Indian Patients with Type 2 Diabetes Mellitus in Real-Life Scenario

INTRODUCTION

Teneligliptin is a recently developed Dipeptidyl Peptidase 4 (DPP4) inhibitor. Teneligliptin is suitable for glycaemic control with renal impairment including end stage renal disease.

AIM

To assess the efficacy and safety of teneligliptin in Asian Indian patients of Type 2 Diabetes Mellitus (T2DM) with early Diabetic Kidney Disease (DKD).

MATERIALS AND METHODS

This was a single centre, retrospective analysis of patients with early DKD, who received teneligliptin 20 mg once daily for 24 weeks. Data related to glycaemic parameters, kidney function, lipid levels, retinopathy, neuropathy and safety variables available at 12 and 24 weeks were analysed. Descriptive statistical analysis was carried out. Statistical significance was assessed at a 5% level.

RESULTS

Total 37 patients (21 males; 16 females) were analysed. Compared to baseline, significant reduction in Fasting Plasma Glucose (FPG) (mg/dl) (143.89±28.26 vs. 125.78±20.52, p=0.001); Postprandial Glucose (PPG) (mg/dl) (200.62±41.88 vs. 165.76±26.02, p=0.001); Glycated Haemoglobin (HbA1c) (%)(8.65±0.58 vs. 8.17±0.54, p=0.001) was noted at 12 weeks. This trend was further continued for 24 weeks with significant reduction in mean FPG, PPG and HbA1c to 113.73±16.82 mg/ dl (p=0.008); 142.95±20.76 mg/dl (p=0.001); and 7.65±0.45% (p=0.001) respectively. Significant improvement in serum creatinine (mg/dl) (2.45±0.27 vs. 2.26±0.23, p=0.001) and eGFR (CKD-EPI), (ml/min/1.73 m²) (53.35±4.24 vs. 55.08±4.19, p=0.001) was noted at 12 weeks and continued for 24 weeks with reduction in serum creatinine of 0.37±0.18 mg/ dl (p=0.001) and increase of eGFR of 4.60±1.59 ml/min/1.73 m² (p=0.001). At baseline, proteinuria was noted in all patients while at 24 weeks, 40.5% (p=0.001) patients did not report proteinuria. Significant improvements in lipid parameters with no deterioration in retinopathy and subjective improvement in peripheral neuropathy was also noted. No adverse events were noted.

CONCLUSION

Teneligliptin reported significant and sustained improvement in glycaemic control in Asian Indian Patients of T2DM with early DKD and was well tolerated. Additionally, Teneligliptin reported significant improvement in renal function.

The dipeptidyl peptidase-4 (DPP-4) inhibitor teneligliptin functions as antioxidant on human endothelial cells exposed to chronic hyperglycemia and metabolic high-glucose memory

Dipeptidyl peptidase-4 inhibitors are widely used in type 2 diabetes. Endothelium plays a crucial role maintaining vascular integrity and function. Chronic exposure to high glucose drives to endothelial dysfunction generating oxidative stress. Teneligliptin is a novel dipeptidyl peptidase-4 inhibitor with antioxidant properties. This study is aimed to verify a potential protective action of teneligliptin in endothelial cells exposed to high glucose. Human umbilical vein endothelial cells were cultured under normal (5 mmol/L) or high glucose (25 mmol/L) during 21 days, or at high glucose during 14 days followed by 7 days at normal glucose, to reproduce the high-metabolic memory state. During this period, different concentrations of teneligliptin (0.1, 1.0 and 3.0 µmol/L) or sitagliptin (0.5 µmol/L) were added to cells. Ribonucleic acid and protein expression were assessed for antioxidant response, proliferation, apoptosis and endoplasmic reticulum stress markers. Teneligliptin promotes the antioxidant response in human umbilical vein endothelial cells, reducing ROS levels and inducing Nrf2-target genes messenger ribonucleic acid expression. Teneligliptin, but not sitagliptin, reduces the expression of the nicotine amide adenine dinucleotide phosphate oxidase regulatory subunit P22 -phox , however, both blunt the high glucose-induced increase of TXNIP. Teneligliptin improves proliferation rates in human umbilical vein endothelial cells exposed to high glucose, regulating the expression of cell-cycle inhibitors markers (P53, P21 and P27), and reducing proapoptotic genes (BAX and CASP3), while promotes BCL2 expression. Teneligliptin ameliorates high glucose-induced endoplasmic reticulum stress reducing the expression of several markers (BIP, PERK, ATF4, CHOP, IRE1a and ATF6). Teneligliptin has antioxidant properties, ameliorates oxidative stress and apoptotic phenotype and it can overcome the metabolic memory effect, induced by chronic exposure to high glucose in human endothelial cells.

Glutaraldehyde-polymerized hemoglobin and tempol (PolyHb-tempol) has superoxide dismutase activity that can attenuate oxidative stress on endothelial cells induced by superoxide anion

A Tempol compound with an amine group (4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, NH₂-Tempol) was cross-linked to hemoglobin in a one-step polymerization reaction to produce a novel hemoglobin-based oxygen carrier (HBOC) designated PolyHb-Tempol. The reaction parameters, including the reaction time, pH, temperature, and ratio of reactants, were optimized, and the physiochemical properties of the resulting product were characterized. PolyHb-Tempol didn't show any toxicity towards endothelial cells. Furthermore, from observations of cell morphology and viability, PolyHb-Tempol showed a significant ability to inhibit or eliminate oxidative stress induced by superoxide free radicals. These results suggest that PolyHb-Tempol may potentially be suitable as an HBOC.

Anagliptin ameliorates albuminuria and urinary liver-type fatty acid-binding protein excretion in patients with type 2 diabetes with nephropathy in a glucose-lowering-independent manner

OBJECTIVE

The objective of this study is to elucidate the effect of anagliptin on glucose/lipid metabolism and renoprotection in patients with type 2 diabetic nephropathy.

METHODS

Twenty-five patients with type 2 diabetic nephropathy received anagliptin 200 mg/day for 24 weeks, and 20 patients who were switched to anagliptin from other dipeptidyl peptidase-4 (DPP-4) inhibitors were analyzed regarding primary and secondary endpoints. The primary endpoint was change in hemoglobin A1c (HbA1c) during treatment with anagliptin. Additionally, we evaluated changes in lipid data (low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol and triglyceride), blood pressure (BP), urinary albumin to creatinine ratio (UACR), liver-type fatty acid-binding protein to creatinine ratio (ULFABP) and renal function (estimated glomerular filtration rate and serum cystatin C) as secondary endpoints.

RESULTS

After switching to anagliptin from other DPP-4 inhibitors, the levels of HbA1c in the 20 participants showed no significant change, 7.5%±1.2% at 24 weeks compared with 7.3%±0.9% at baseline. The levels of the log10-transformed UACR were significantly reduced from 1.95±0.51 mg/g creatinine (Cr) at baseline to 1.76±0.53 mg/g Cr at 24 weeks after anagliptin treatment (p<0.01). The percentage change in the UACR (Δ%UACR) from baseline to 24 weeks was also significantly lower by -10.6% (p<0.001). Lipid data, systolic BP and renal function were not changed during anagliptin treatment. Additionally, ULFABP in eight participants, who had ≥5 µg/g Cr at baseline, was significantly decreased from baseline (8.5±2.8 µg/g Cr) to 24 weeks (3.1±1.7 µg/g Cr, p<0.01) after anagliptin treatment, and the percentage change in the ULFABP during anagliptin treatment was -58.1% (p<0.001).

CONCLUSIONS

Anagliptin induced no significant change in HbA1c, lipid data, systolic BP and renal function. However, anagliptin reduced the UACR and ULFABP, although without a corresponding change in HbA1c, indicating direct action of anagliptin on renoprotection in patients with type 2 diabetic nephropathy.

Impact of teneligliptin on oxidative stress and endothelial function in type 2 diabetes patients with chronic kidney disease: a case-control study

Background

The aim of the present study was to elucidate the effect of teneligliptin on oxidative stress and endothelial function in Japanese patients with type 2 diabetes and chronic kidney disease (CKD).

Methods

Forty-five patients with type 2 diabetes and CKD who received sitagliptin for at least 12 months were randomized to either continue sitagliptin (n = 23) or switch to teneligliptin (n = 22) for 24 weeks. The following parameters were evaluated at baseline and after 24 weeks of treatment with continued sitagliptin or teneligliptin: blood pressure, haemoglobin A1c (HbA1c), estimated glomerular filtration rate (eGFR), urinary albumin excretion, endothelial function by reactive hyperaemia index (RHI; EndoPAT^® system), reactive oxygen metabolites (ROMs) measured by the d-ROMS test, 8-hydroxy-2′-deoxyguanosine, urinary liver-type fatty acid binding protein (L-FABP), and urinary 8-isoprostane.

Results

The two groups did not significantly differ with regard to age, male-to-female ratio, duration of diabetes, body mass index, HbA1c, eGFR, or urinary albumin excretion levels at baseline. We found no significant differences in changes of HbA1c, eGFR, or urinary albumin excretion levels between the two groups after 24 weeks of treatment. However, treatment with teneligliptin, but not sitagliptin, significantly improved RHI values and was correlated with the percent changes in RHI and d-ROMs.

Conclusions

The present study demonstrated that teneligliptin, can improve endothelial function and reduce renal and vascular oxidative stress in patients with type 2 diabetes and CKD, independently of reducing albuminuria or improving glucose control.

Trial registration UMIN000017180

Effects of teneligliptin on PDMPs and PAI-1 in patients with diabetes on hemodialysis

Background

Cardiovascular disease (CVD) is the main cause of death among hemodialysis (HD) patients. The effects of the dipeptidyl peptidase-4 inhibitor teneligliptin on CVD-related biomarkers in patients with type 2 diabetes mellitus (T2DM) receiving HD treatment are poorly understood. To determine whether teneligliptin has anti-CVD properties, we assessed its effects on soluble P-selectin (sP-selectin), platelet-derived microparticles (PDMPs), plasminogen activator inhibitor 1 (PAI-1), soluble E-selectin (sE-selectin), soluble vascular adhesion molecule 1 (sVCAM-1), and adiponectin plasma levels in HD and non-HD patients with T2DM.

Methods

Patients with T2DM eligible for teneligliptin monotherapy or combination therapy (eg, teneligliptin plus a sulfonylurea) were administered teneligliptin (20 mg/d) once daily for 6 months. Plasma levels of sP-selectin, PDMPs, PAI-1, sE-selectin, sVCAM-1, and adiponectin were measured by enzyme-linked immunosorbent assay at baseline and after 3 months and 6 months of treatment.

Results

Teneligliptin therapy significantly reduced plasma levels of sP-selectin, PDMPs, and PAI-1 compared with baseline levels, while significantly increasing adiponectin levels. sE-selectin and sVCAM-1 levels were significantly decreased only at 6 months. The reduction in sP-selectin, PDMPs, and PAI-1 was more significant in HD patients than in non-HD patients. However, the improvement in adiponectin levels was unchanged with HD treatment.

Conclusion

By modulating PDMPs or PAI-1, teneligliptin shows an antiatherothrombotic effect that may be beneficial in the primary prevention of CVD in patients with T2DM on HD.