Efficacy of glucagon-like peptide-1 mimetics for neural regeneration

Glucagon-like peptide 1（GLP-1）is secreted from enteroendocrine L cells in response to nutrient ingestion and exhibits insulinotropic properties by stimulating specific G protein-linked receptors（GLP-1Rs）on pancreaticβcells.Several GLP-1 mimetics,such as exenatide（exendin-4（Ex-4））,liraglutide,and lixisenatide,have been developed and approved as treatments for patients with type 2 diabetes.These peptides show bioactiv-ities almost identical to those of GLP- 1 and have a substantially longer plasma half-life than GLP-1 because of their resistance to dipeptidyl peptidase-4, a GLP-1 degrading enzyme.

Development of therapeutic options on type 2 diabetes in years:Glucagon-like peptide-1 receptor agonist’s role intreatment; from the past to future

Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycemia.Type 2 diabetes (T2DM) accounting for 90% of cases globally.The worldwide prevalence of DM is rising dramatically over the last decades,from 30 million cases in 1985 to 382 million cases in 2013.It’s estimated that 451 million people had diabetes in 2017.As the pathophysiology was understood over the years,treatment options for diabetes increased.Incretin-based therapy is one of them.Glucagon-like peptide-1 receptor agonist (GLP-1 RA) not only significantly lower glucose level with minimal risk of hypoglycemia but also,they have an important advantage in themanagement of cardiovascular risk and obesity.Thus,we will review here GLP-1 RAsrole in the treatment of diabetes.

Solid phase synthesis of fatty acid modified glucagon-like peptide-1(7-36) amide under thermal and controlled microwave irradiation

Fatty acid modified glucagon-like peptide-1(7-36) amide was synthesized efficiently on Rink-Amide-MBHA resin by microwave-assisted solid phase method.The method of thermal and controlled microwave irradiation provided impressive enhancements in product yield,selectivity,and reaction rate.The coupling time was dramatically decreased to 6 min,and the desired products were obtained in high yield and purity.

Pharmacological inhibition of diacylglycerol acyltransferase-1 and insights into postprandial gut peptide secretion

AIM To examine the role that enzyme Acyl-CoA:diacylglycerol acyltransferase-1(DGAT1) plays in postprandial gut peptide secretion and signaling.METHODS The standard experimental paradigm utilized to evaluate the incretin response was a lipid challenge.Following a lipid challenge,plasma was collected via cardiac puncture at each time point from a cohort of 5-8 mice per group from baseline at time zero to 10 h.Incretin hormones [glucagon like peptide-1(GLP-1),peptide tyrosine-tyrosine(PYY) and glucose dependent insulinotropic polypeptide(GIP)] were then quantitated.The impact of pharmacological inhibition of DGAT1 on the incretin effect was evaluated in WT mice.Additionally,a comparison of loss of DGAT1 function either by genetic ablation or pharmacological inhibition.To further elucidate the pathways and mechanisms involved in the incretin response to DGAT1 inhibition,other interventions [inhibitors of dipeptidyl peptidase-IV(sitagliptin),pancreatic lipase(Orlistat),GPR119 knockout mice] were evaluated.RESULTS DGAT1 deficient mice and wildtype C57/BL6J mice werelipid challenged and levels of both active and total GLP-1 in the plasma were increased.This response was further augmented with DGAT1 inhibitor PF-04620110 treated wildtype mice.Furthermore,PF-04620110 was able to dose responsively increase GLP-1 and PYY,but blunt GIP at all doses of PF-04620110 during lipid challenge.Combination treatment of PF-04620110 and Sitagliptin in wildtype mice during a lipid challenge synergistically enhanced postprandial levels of active GLP-1.In contrast,in a combination study with Orlistat,the ability of PF-04620110 to elicit an enhanced incretin response was abrogated.To further explore this observation,GPR119 knockout mice were evaluated.In response to a lipid challenge,GPR119 knockout mice exhibited no increase in active or total GLP-1 and PYY.However,PF-04620110 was able to increase total GLP-1 and PYY in GPR119 knockout mice as compared to vehicle treated wildtype mice.CONCLUSION Collectively,these data provide some insight into the mechanism by which inhibition of DGAT1 enhances intestinal hormone release.

Oral peptide therapeutics for diabetes treatment: State-of-the-art and future perspectives

Diabetes,characterized by hyperglycemia,is a major cause of death and disability worldwide.Peptides,such as insulin and glucagon-like peptide-1(GLP-1)analogs,have shown promise as treatments for diabetes due to their ability to mimic or enhance insulin's actions in the body.Compared to subcutaneous injection,oral administration of anti-diabetic peptides is a preferred approach.However,biological barriers significantly reduce the efficacy of oral peptide therapeutics.Recent advancements in drug delivery systems and formulation techniques have greatly improved the oral delivery of peptide therapeutics and their efficacy in treating diabetes.This review will highlight(1)the benefits of oral anti-diabetic peptide therapeutics;(2)the biological barriers for oral peptide delivery,including pH and enzyme degradation,intestinal mucosa barrier,and biodistribution barrier;(3)the delivery platforms to overcome these biological barriers.Additionally,the review will discuss the prospects in this field.The information provided in this review will serve as a valuable guide for future developments in oral anti-diabetic peptide therapeutics.

Electroacupuncture for functional dyspepsia and the influence on serum Ghrelin, CGRP and GLP-1 levels

Objective： To observe the clinical efficacy of electroacupuncture for functional dyspepsia（FD）, and explore the corresponding mechanism.Methods： Sixty-four FD patients were randomly divided into electroacupuncture group and western medicine group, with 32 cases in each group. In electroacupuncture group, electroacupuncture at Zusanli（足三里ST 36）,Sanyinjiao（三阴交SP 6）,Gongsun（公孙SP 4） and Neiguan（内关PC 6） was performed for once a day, and the needles were retained for 30 min. In western medicine group, oral administration of mosapride citrate dispersible tablets in a dosage of 5 mg/time was carried out for 3 times a day. Treatment was conducted for 30 consecutive days in both groups. The scores of Leeds dyspepsia questionnaire（LDQ） and functional digestive disorder quality of life（FDDQL） of patients in both groups were recorded before and after treatment. Serum Ghrelin, CGRP and GLP-1 levels of patients were tested before and after treatment respectively, and the clinical efficacy of patients in both groups was evaluated after treatment.Results： In western medicine group, LDQ score after treatment was lower than that before treatment（P 0.05）, FDDQL score after treatment was higher than that before treatment, while the differences were not statistically significant（P0.05）. LDQ score in electroacupuncture group after treatment was lower than that before treatment（P0.05）, and also lower than that in western medicine group at the same time point（P 0.05）. FDDQL score in electroacupuncture group after treatment was higher than that before treatment（P0.05）, and also higher than that in western medicine group at the same time point（P0.05）. In western medicine group, Ghrelin level after treatment was higher than that before treatment（P 0.05）, CGRP level reduced, and the differences were not statistically significant（P 0.05）. GLP-1 level after treatment was also higher than that before treatment（P0.05）. In electroacupuncture group,Ghrelin level after treatment was higher than that before treatment, CGRP level reduced, and GLP-1 level after treatment was also higher than that before treatment（both P 0.05）. According to the comparison of values of each index between electroacupuncture group and western medicine group after treatment,the differences were all statistically significant（all P 0.05）. The total effective rate in electroacupuncture group was 90.63%（29/32） which was higher than that in western medicine group 68.75%（22/32）, and the differences were statistically significant（P0.05）.Conclusion： Electroacupuncture at ST 36, SP 6, SP 4 and PC 6 can effectively improve the clinical symptoms of FD patients, and the mechanism might be related with the increase of serum Ghrelin and GLP-1 levels and the decrease of serum CGRP level.

Fighting type 2 diabetes: Formulation strategies for peptide-based therapeutics

Diabetes mellitus is a major health problem with increasing prevalence at a global level.The discovery of insulin in the early 1900 s represented a major breakthrough in diabetes management,with further milestones being subsequently achieved with the identification of glucagon-like peptide-1(GLP-1)and the introduction of GLP-1 receptor agonists(GLP-1 RAs)in clinical practice.Moreover,the subcutaneous delivery of biotherapeutics is a well-established route of administration generally preferred over the intravenous route due to better patient compliance and prolonged drug absorption.However,current subcutaneous formulations of GLP-1 RAs present pharmacokinetic problems that lead to adverse reactions and treatment discontinuation.In this review,we discuss the current challenges of subcutaneous administration of peptide-based therapeutics and provide an overview of the formulations available for the different routes of administration with improved bioavailability and reduced frequency of administration.

Effect of vildagliptin as add-on therapy to a low-dose metformin

AIM:To evaluate the efficacy and safety of the addition of vildagliptin to low-dose metformin and compare it to an uptitration of metformin in type 2 diabetes mellitus(T2DM) patients who have inadequate control with metformin monotherapy.METHODS:Eligible patients were randomized to receive vildagliptin 100 mg qd or metformin(500 mg qd for 2 wk and then 500 mg bid) added to open label me tformin 500 mg bid for the 24 wk.The primary endpoi nt was baseline to endpoint hemoglobin A1c(HbA1c) change.RESULTS:The adjusted mean change from baseline in HbA1c at the 24th wk was-0.51% in the vildagliptin/metformin group(mean baseline HbA1c:7.4%) and-0.37% in the metformin monothera py group(mean baseline HbA1c:7.3%).The mean diffe rence was-0.14% with 95% Confidence Interval(-0.24%,-0.05%).As non-inf e riority(margin of 0.4%) was achieved,a test for superiority was performed.This test showed statistically significant superiority of the combination over monotherapy group(P = 0.002).Gastrointestinal(GI) adverse events were signif icantly more frequent in the metformin group than the combin ation group(21.0% vs 15.4%,P = 0.032).CONCLUSION:In patients with T2DM inadequately controlled with metformin up to 1000 mg daily,the addition of vildagliptin 100 mg daily achieved larger HbA1c reduction with fewer GI events than with increa sing the metformin dose.

Effect of Roux-en-Y gastric bypass surgery on intestinal Akkermansia muciniphila

AIM: To investigated changes in intestinal Akkermansia muciniphila(A. muciniphila) and explored the mechanism underlying the therapeutic effects of Roux-en-Y gastric bypass(RYGB) surgery on type 2 diabetes in diabetic Goto-Kakizaki(GK) rats. METHODS: Male diabetic GK rats(n = 12) aged 8 wk were randomly assigned to the surgery group(GK-RYGB) or sham surgery group(GK-Sham)(n = 6 per group), and another 6 male Wistar rats aged 8 wk served as controls(WS-Sham). In the surgery group, RYGB surgery was conducted, and a sham operation was performed in both sham groups. Fasting blood glucose(FBG) levels before and after surgery, fasting levels of serum insulin and serum glucagon-like peptide-1(GLP-1) and levels 30 min after intragastric injection of glucose, and the amount of A. muciniphila in the stool were determined. Insulin and GLP-1 were measured by enzyme-linked immunosorbent assay, and A. muciniphila were detected by fluorescence-based quantitative polymerase chain reaction. RESULTS: The FBG was improved, and serum GLP-1 and insulin increased significantly(P < 0.05) in the GKRYGB group after surgery compared to levels before surgery and to levels in the GK-Sham group. Before surgery, the amounts of A. muciniphila in the GK-RYGB and GK-Sham groups were significantly lower than in the WS-Sham group(P < 0.05). After surgery, the amount of A. muciniphila in the GK-RYGB group increased markedly compared to that before surgery and to that in the GKSham and WS-Sham groups(P < 0.05). In addition, the A.muciniphila amount was positively related to GLP-1(r = 0.86, P < 0.05). CONCLUSION: Our results demonstrated RYGB surgery may increase GLP-1 secretion, elevate serum insulin after intragastric injection of glucose, and improve insulin resistance in diabetic GK rats, thereby contributing to a significant reduction in blood glucose. The increased amount of A. muciniphila after RYGB surgery may be related to elevated GLP-1 secretion.

Exenatide reduces doxorubicin-induced cardiac injury

Objective Doxorubicin(Dox)is an effective antitumor drug,which is limited due to its lethal cardiac injury in clinical application.Exenatide(Exe)is a glucagon-like peptide-1(GLP-1)analog,it can not only regulate blood glucose,but protect the myocardium by reducing inflammation,oxidative stress and cell apoptosis.Since doxorubicininduced cardiac injury is currently thought to be mainly caused by inflammation,oxidative stress and cell apoptosis,we hypothesized that prophylactic treatment with exenatide may alleviate doxorubicin-induced cardiac injury.

Cystic fibrosis-related diabetes:The unmet need

Cystic fibrosis(CF)is a common autosomal recessive disease.Life expectancy of patients with CF continues to improve mainly driven by the evolving therapies for CF-related organ dysfunction.The prevalence of CF-related diabetes(CFRD)increases exponentially as patients’age.Clinical care guidelines for CFRD from 2010,recommend insulin as the mainstay of treatment.Many patients with CFRD may not require exogenous insulin due to the heterogeneity of this clinical entity.Maintenance of euglycemia by enhancing endogenous insulin production,secretion and degradation with novel pharmacological therapies like glucagonlike peptide-1 agonist is an option that remains to be fully explored.As such,the scope of this article will focus on our perspective of glucagon-like peptide-1 receptor agonist in the context of CFRD.Other potential options such as sodiumglucose cotransporter-2 and dipeptidyl peptidase 4 inhibitors and their impact on this patient population is limited and further studies are required.

Advances in reducing cardiovascular risk in the management of patients with type 2 diabetes mellitus

Treatment intended to lower cardiovascular (CV) risk in patients with diabetes has always been a primary goal of diabetes treatment. Due to the subdued effects of reducing hemoglobin A1c (HbA1c) on macrovascular complications, controlling other CV risk factors such as hypertension and hyperlipidemia instead of hyperglycemia has been the mainstay treatment to improve CV outcome in patients with type 2 diabetes mellitus (T2DM) until recent years. This review is intended to summarize and compare the results from the available cardiovascular outcome trials (CVOTs) for the two classes of glucose lowering drug: sodium-glucose cotransporter 2 inhibitor (SGLT2i) and glucagon-like peptide-1 receptor agonist (GLP-1 RA). The results including the EMPA-REG, CANVAS program and DECLARE-TIMI 58 trials for SGLT2i, and the ELIXA, LEADER, SUSTAIN-6, EXSCEL and HARMONY trials for GLP-1 RA were summarized. The potential mechanisms of these CV beneficial effects and the optimal CV risk reduction treatment in patients with T2DM based on patient risk stratification and evidence from these CVOTs in real-world setting were discussed.