Trelagliptin succinate: DPP-4 inhibitor to improve insulin resistance in adipocytes

The Possible Associations between Tauopathies and Atherosclerosis, Diabetes Mellitus, Dyslipidemias, Metabolic Syndrome and Niemann-Pick Disease

Clinical evaluation and treatment of tauopathic syndromes remain a challenge. There is a growing interest in theories concerning their possible associations with metabolic diseases. The possible connection between those diseases might be linked with cerebrovascular dysfunction. The endothelial cell damage and impairment of the blood-brain barrier observed in atherosclerosis or diabetes may play a role in contributing to tauopathic syndrome development. Additionally, the inflammation evoked by pathological metabolic changes may also be involved in this process. Multiple cases indicate the coexistence of metabolic disorders and tauopathic syndromes. These findings suggest that modifying the evolution of metabolic and cerebrovascular diseases may impact the course of neurodegenerative diseases. Obtained data could indicate the possible benefits of introducing routine carotid artery sonography, revascularization operation or antihypertensive medications among patients at high risk for tauopathies. This review has identified this understudied area, which is currently associated with several diseases for which there is no treatment. Due to the pathomechanisms linking metabolic diseases and tauopathies, further investigation of this area of research, including cohort studies, is recommended and may provide new pharmacological perspectives for treatment.

Discovery of Nine Dipeptidyl Peptidase-4 Inhibitors from Coptis chinensis Using Virtual Screening, Bioactivity Evaluation, and Binding Studies

The objective of this study was to identify multiple alkaloids in Coptis chinensis that demonstrate inhibitory activity against DPP-4 and systematically evaluate their activity and binding characteristics. A combined strategy that included molecular docking, a DPP-4 inhibition assay, surface plasmon resonance (SPR), and a molecular dynamics simulation technique was employed. The results showed that nine alkaloids in Coptis chinensis directly inhibited DPP-4, with IC50 values of 3.44-53.73 μM. SPR-based binding studies revealed that these alkaloids display rapid binding and dissociation characteristics when interacting with DPP-4, with KD values ranging from 8.11 to 29.97 μM. A molecular dynamics analysis revealed that equilibrium was rapidly reached by nine DPP-4-ligand systems with minimal fluctuations, while binding free energy calculations showed that the ∆Gbind values for the nine test compounds ranged from -31.84 to -16.06 kcal/mol. The most important forces for the binding of these alkaloids with DPP-4 are electrostatic interactions and van der Waals forces. Various important amino acid residues, such as Arg125, His126, Phe357, Arg358, and Tyr547, were involved in the inhibition of DPP-4 by the compounds, revealing a mechanistic basis for the further optimization of these alkaloids as DPP-4 inhibitors. This study confirmed nine alkaloids as direct inhibitors of DPP-4 and characterized their binding features, thereby providing a basis for further research and development on novel DPP-4 inhibitors.

Effects of the egg protein hydrolysate NWT-03 on cognitive function in men and women with the metabolic syndrome: a randomized, double-blind, placebo-controlled study

Objectives: The metabolic syndrome is associated with cardiovascular diseases and cognitive decline. The egg protein hydrolysate NWT-03 has shown to improve cardiovascular risk factors in humans. This study investigated whether NWT-03 also has an effect on cognitive function.Methods: Men and women with the metabolic syndrome (n = 76) with a mean age of 60 ± 10 years participated in this randomized, double-blind, placebo-controlled, cross-over trial with an intervention (5 g/day NWT-03) and control period (5 g/day maltodextrin) of 4 weeks separated by a wash-out period of 2-8 weeks. Cognitive function was assessed with the anti-cue reaction time test (impulse control) and psychomotor vigilance test (sustained attention) at day 0, 2, and 27 of both periods. Serum brain-derived neurotrophic factor (BDNF) concentrations were measured at the start and end of both periods.Results: NWT-03 consumption significantly improved the change (day 27 - day 0) in response times of the anti-cue reaction time test compared with the control period (P < 0.001), but not of the psychomotor vigilance test (P = 0.487). Serum BDNF concentrations of all subjects did not significantly change (P = 0.241).Conclusion: NWT-03 has the ability to improve cognitive function within the executive function domain. The underlying mechanism warrants further research and could either be indirect via inhibition of dipeptidyl peptidase 4 (DPP4) or direct via passage of small peptides over the blood-brain barrier inducing local effects.Trial registration: ClinicalTrials.gov identifier: NCT02561663.

Trelagliptin relieved cognitive impairment of diabetes mellitus rats: Involvement of PI3K/Akt/GSK-3β and inflammation pathway

Cognitive impairment frequently coexists with diabetes. Trelagliptin is a once-weekly taking selective dipeptidyl peptidase-4 (DPP-4) inhibitor and a long-term effective hypoglycemic medicine; nonetheless, its effects for the treatment of diabetes-related cognitive impairment have only sometimes been explored. In this study, a DM model was built using streptozotocin (STZ) and a high-fat diet (HFD). The morris water maze test on DM rats revealed a considerably reduced capacity for spatial learning and memory, but trelagliptin was able to restore function. Trelagliptin could lower the mRNA expression of inflammatory factors such IL-1β, TNF-α, and IL-6 in DM rats. It could also reduce the ratio of p-IKKα/IKKα, and the immunofluorescence result of NF-κB also demonstrated a drop. Trelagliptin partially restored dendritic spines and prevented the loss or shrinkage of neurons, respectively, according to the results of Nissl's staining and golgi staining. Furthermore, PI3K/Akt/GSK-3β has been activated, and synaptic plasticity has been modified during this process. In conclusion, trelagliptin improved the cognitive lesion in DM rats by suppressing the activation of the inflammatory route and by activating the PI3K/Akt/GSK-3β pathway at the same time, as well as interacting with the pathways that protect neurons, which still need further research.

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

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

Empagliflozin versus sitagliptin for ameliorating intrahepatic lipid content and tissue-specific insulin sensitivity in patients with early-stage type 2 diabetes with non-alcoholic fatty liver disease: A prospective randomized study

AIM

To compare the effects of sodium-glucose co-transporter-2 (SGLT2) inhibitors and dipeptidyl peptidase-4 inhibitors on ectopic fat accumulation and tissue-specific insulin sensitivity.

MATERIALS AND METHODS

This randomized controlled trial enrolled 44 patients with type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD). They were randomly assigned to receive either empagliflozin 10 mg/day or sitagliptin 100 mg/day for 12 weeks. The primary endpoint was the change in intrahepatic lipid content (IHL) measured using proton magnetic resonance spectroscopy (¹ H-MRS). The secondary endpoints included intramuscular and extramuscular lipid content seen in ¹ H-MRS, body composition seen through dual-energy X-ray absorptiometry and tissue-specific insulin sensitivity shown through hyperinsulinaemic-euglycaemic clamp using stable isotopic glucose. Liver biopsy samples were pathologically evaluated at baseline.

RESULTS

At baseline, the mean duration of diabetes, HbA1c level and IHL were 3.7 years, 7.2% and 20.9%, respectively. The median NAFLD activity score was 3.0. IHL was significantly more decreased in the empagliflozin group than that in the sitagliptin group (between-group difference was -5.2% ± 1.1% and -1.9% ± 1.2%, respectively, (95% confidence interval); -3.3 (-6.5, -0.1), P = .044). However, there were no significant between-group differences in the change of insulin sensitivity in the liver, muscle or adipose tissues. Interestingly, hepatic insulin sensitivity was significantly increased only in the empagliflozin group and was significantly negatively associated with the change in IHL.

CONCLUSIONS

Empagliflozin significantly improves hepatic steatosis compared with sitagliptin, and this may protect against subsequent hepatic insulin resistance. Early administration of SGLT2 inhibitors is preferable for T2D patients with NAFLD.

Heat-Killed Enterococcus faecalis Prevents Adipogenesis and High Fat Diet-Induced Obesity by Inhibition of Lipid Accumulation through Inhibiting C/EBP-α and PPAR-γ in the Insulin Signaling Pathway

Increasing consumption of food with high caloric density and a sedentary lifestyle have influenced the increasing obesity prevalence worldwide. The recent pandemic has contributed to this problem. Obesity refers to a state in which lipid accumulates excessively in adipocytes and adipose tissues. Dried heat-killed Enterococcus faecalis (EF-2001) prevents allergic mechanisms, inflammation, and tumor progression. In the present study, we investigated the effects of EF-2001 on high fat diet (HFD)-induced obese rats. The degree of obesity in experimental rats was reduced after 6 weeks of oral administration of 3 mg/kg or 30 mg/kg dosages of EF-2001, indicating regulating effects in rats with HFD-induced obesity. We found that EF-2001 decreased the amounts of total cholesterol, triglyceride, and non-high density lipoprotein (HDL) in HFD-induced obese rats. The effects of EF-2001 on 3T3-L1 adipocytes stained with Oil red O stain are shown in reductions of lipid accumulation, respectively. In addition, we examined the relationships between EF-2001 treatment and mechanisms for the insulin signaling of adipogenesis in 3T3-L1 cells. EF-2001 induced down-regulation in phosphorylation of Erk, JNK, and Akt through the inhibition of insulin receptor phosphorylation. EF-2001 inhibits the expressions of C/EBP-α and PPAR-γ, a lipid metabolism-related transcription factor through confocal microscope observation and Western blot on 3T3-L1 adipocytes and HFD-induced obese rats. Based on our results, intake of EF-2001 significantly prevented HFD-induced obesity in rats through inhibition of C/EBP-α and PPAR-γ in the insulin signaling pathway on lipid accumulation.

Investigation of Pharmacokinetic Parameters of Trelagliptin in Egyptian Volunteers Using Sensitive LC-MS/MS: A Comparative Study with a Japanese Population

Trelagliptin (TLN) is a novel once-weekly antidiabetic drug that enhanced the patient compliance in type 2 diabetes. TLN analysis and bioanalysis literature review showed many methods for TLN assay either in dosage form or as biological fluids (pharmacokinetic parameters), but all those methods did not consider the full details dealing with biological assay of TLN. Studies that included information about pharmacokinetic parameters did not mention the used analytical procedures for those determinations and parameters. Although some LC-MS/MS and UPLC-UV methods were reported for TLN bioassay in rats' plasma, they used direct precipitation techniques, and the current described procedure showed lower LLOQ than all the reported methods in spite of that working on human plasma is more complicated than on rats' plasma. In this study, LC-MS/MS bioanalysis of TLN in human plasma (4-1000 nM) was employed successfully with LLOQ of 4 nM which is lower than all reported methods in rats' plasma followed by a preliminary pharmacokinetic study. Alogliptin was used as internal standard (IS) because of its structure similarity to TLN. Pharmacokinetic parameters of TLN were investigated in Egyptian volunteers, and they had been compared to Japanese. Liquid-liquid extraction showed more sensitive results than direct precipitation. The proposed method was successfully applied to a pharmacokinetic study conducted on Egyptian volunteers. No dose modification is required upon comparing the pharmacokinetic parameters of the current study and previous studies on non-Egyptian volunteers.

A dipeptidyl peptidase IV inhibitory peptide relieves palmitic acid-induced endoplasmic reticulum stress in HepG2 cells independent of inhibiting dipeptidyl peptidase IV activity

The peptide VLATSGPG (VLA) is known to inhibit dipeptidyl peptidase IV (DPP-IV), although its mechanism in relieving endoplasmic reticulum (ER) stress is unclear. In this study, we found that treating HepG2 cells with 1.0 mM VLA reduced DPP-IV activity by 73.7 ± 4.8% without changing the DPP-IV mRNA expression level. In addition, 1.0 and 0.5 mM VLA alleviated palmitic acid (PA)-induced cell death and intracellular calcium imbalances. The levels of apoptosis-related proteins (caspase-3, caspase-9, and CHOP) were reduced by VLA treatment, which was presumed to be related to ER stress. Further studies confirmed that VLA alleviated PA-induced morphological damage to the ER and reduced the levels of the ER stress marker proteins (BIP, p-PERK, and p-IRE1α). VLA alleviated PA-induced ER stress in HepG2 cells independent of DPP-IV enzymatic activity inhibition. These findings have implications for developing novel treatment approaches for liver diseases caused by ER stress.

The anti-diabetic drug trelagliptin induces vasodilation via activation of Kv channels and SERCA pumps

AIMS

In this study, we investigated the vasodilatory effects of trelagliptin (a dipeptidyl peptidase-4 inhibitor) and its related mechanisms using rabbit aortic rings.

MAIN METHODS

Arterial tone measurement was performed in rabbit thoracic aortic rings.

KEY FINDINGS

Trelagliptin induced vasodilation in a dose-dependent manner. Pretreatment with the ATP-sensitive K⁺ channel inhibitor glibenclamide, large-conductance Ca²⁺-activated K⁺ channel inhibitor paxilline, and inwardly rectifying K⁺ channel inhibitor Ba²⁺ did not affect the vasodilatory effect of trelagliptin. However, pretreatment with the voltage-dependent K⁺ (Kv) channel inhibitors 4-aminopyridine and tetraethylammonium significantly attenuated the vasodilatory effect of trelagliptin, suggesting that the vasodilatory effect of trelagliptin is associated with Kv channel activation. Although pretreatment with Kv1.5 and Kv2.1 subtype inhibitors did not affect the response to trelagliptin, pretreatment with a Kv7.X subtype inhibitor effectively reduced the vasodilatory effect of trelagliptin. Furthermore, sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitors also significantly attenuated the vasodilatory effect of trelagliptin. These effects, however, were not affected by pretreatment with Ca²⁺ channel inhibitors, adenylyl cyclase/PKA inhibitors, guanylyl cyclase/PKG inhibitors, or removal of the endothelium.

SIGNIFICANCE

From these results, we concluded that the vasodilatory effect of trelagliptin was associated with the activation of Kv channels (primary the Kv7.X subtype) and SERCA pump regardless of other K⁺ channels, Ca²⁺ channels, cAMP/PKA-related or cGMP/PKG-related signaling pathways, and the endothelium. Therefore, caution is required when prescribing trelagliptin to the patients with hypotension and diabetes.

Trelagliptin stimulates osteoblastic differentiation by increasing runt-related transcription factor 2 (RUNX2): a therapeutic implication in osteoporosis

Osteoporosis, an aging-associated bone metabolic disease, is affecting millions of people worldwide. The deregulated process of osteoblastic differentiation has been linked with the progression of osteoporosis. Trelagliptin is a long-acting inhibitor of DPP-4 used for the management of type 2 diabetes mellitus. However, it is unknown whether Trelagliptin possesses a beneficial effect in osteoblastic differentiation. Interestingly, we found that treatment with Trelagliptin enhanced differentiation and promoted the mineralization of MC3T3-E1 cells. Firstly, Trelagliptin increased the activity of alkaline phosphatase (ALP) and promoted osteoblastic calcium deposition. Additionally, treatment with Trelagliptin upregulated ALP, osteocalcin (OCN), osteopontin (OPN), and bone morphogenetic protein-2 (BMP-2). Notably, Trelagliptin increased RUNX2, a major regulator of osteoblastic differentiation. Mechanistically, Trelagliptin upregulated the levels of p-AMPKα. Blockage of AMPK with compound C abolished the effects of Trelagliptin in RUNX2 and osteoblastic differentiation, suggesting the involvement of AMPK. Our findings suggest that Trelagliptin might possess a potential for the treatment of osteoporosis.

The protective effects of trelagliptin on high-fat diet-induced nonalcoholic fatty liver disease in mice

Nonalcoholic fatty liver disease (NAFLD) occurs in patients with type 2 diabetes mellitus (T2DM). Trelagliptin is an important member of the Gliptins family, which has been recently licensed for the treatment of T2DM. However, the pharmacological function of trelagliptin in NAFLD has not been previously reported. In this study, we aimed to investigate the roles of trelagliptin in the development of NAFLD in a mouse model. To induce NAFLD disease, C57BL/6 mice were fed a high-fat diet for 10 weeks. Our results indicate that trelagliptin reduced plasma lipid levels in NAFLD mice by reducing triglycerides, total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol. Treatment with trelagliptin exhibited an improvement in insulin resistance. More important, trelagliptin improved liver function by reducing alanine transaminase, aspartate transaminase, lactate dehydrogenase, and total bile acid. In addition, trelagliptin ameliorated oxidative stress in the liver of NAFLD mice by reducing malondialdehyde and increasing the levels of reduced glutathione and superoxide dismutase activity. Also, the enzyme-linked immunosorbent assay results indicate that trelagliptin-treated mice displayed anti-inflammatory properties by reducing the levels of interleukin 1β (IL-1β), IL-6, and tumor necrosis factor-α. Hematoxylin and eosin and Oil red O staining show that trelagliptin treatment ameliorates liver tissue damage and hepatic lipid deposition. Mechanistically, we found that the administration of trelagliptin reduced the activity of hepatic nuclear factor-κB but increased the activity of AMP-activated protein kinase. These findings suggest that trelagliptin might become a promising therapeutic agent for the treatment of NAFLD.