Anti-inflammatory potentials of incretin-based therapies used in the management of diabetes

Modern Management of Cardiometabolic Continuum: From Overweight/Obesity to Prediabetes/Type 2 Diabetes Mellitus. Recommendations from the Eastern and Southern Europe Diabetes and Obesity Expert Group

The increasing global incidence of obesity and type 2 diabetes mellitus (T2D) underscores the urgency of addressing these interconnected health challenges. Obesity enhances genetic and environmental influences on T2D, being not only a primary risk factor but also exacerbating its severity. The complex mechanisms linking obesity and T2D involve adiposity-driven changes in β-cell function, adipose tissue functioning, and multi-organ insulin resistance (IR). Early detection and tailored treatment of T2D and obesity are crucial to mitigate future complications. Moreover, personalized and early intensified therapy considering the presence of comorbidities can delay disease progression and diminish the risk of cardiorenal complications. Employing combination therapies and embracing a disease-modifying strategy are paramount. Clinical trials provide evidence confirming the efficacy and safety of glucagon-like peptide 1 receptor agonists (GLP-1 RAs). Their use is associated with substantial and durable body weight reduction, exceeding 15%, and improved glucose control which further translate into T2D prevention, possible disease remission, and improvement of cardiometabolic risk factors and associated complications. Therefore, on the basis of clinical experience and current evidence, the Eastern and Southern Europe Diabetes and Obesity Expert Group recommends a personalized, polymodal approach (comprising GLP-1 RAs) tailored to individual patient's disease phenotype to optimize diabetes and obesity therapy. We also expect that the increasing availability of dual GLP-1/glucose-dependent insulinotropic polypeptide (GIP) agonists will significantly contribute to the modern management of the cardiometabolic continuum.

Anti-inflammatory benefits of semaglutide: State of the art

Individuals with diabetes often have chronic inflammation and high levels of inflammatory cytokines, leading to insulin resistance and complications. Anti-inflammatory agents are proposed to prevent these issues, including using antidiabetic medications with anti-inflammatory properties like semaglutide, a GLP-1 analogue. Semaglutide not only lowers glucose but also shows potential anti-inflammatory effects. Studies suggest it can modulate inflammatory responses and benefit those with diabetes. However, the exact mechanisms of its anti-inflammatory effects are not fully understood. This review aims to discuss the latest findings on semaglutide's anti-inflammatory effects and the potential pathways involved.

Relationship Between Diabetes Mellitus and Periodontal/Peri-Implant Disease: A Contemporaneous Review

The prevalence of diabetes mellitus (DM), a major chronic disease and a leading cause of death and disability around the world, is rising. According to the latest data, the global prevalence of DM has increased to 463 million (9.3% of adults) in 2019 and is estimated to reach 700 million by 2045. Periodontal disease, result of periodontium inflammation, is a common, chronic disease and has long been considered one of the complications of DM. Moreover, literature reflects a spectrum of conflicting viewpoints on the effect of diabetic conditions on the implant treatment strategies. The current review aims to update the recent epidemiologic evidence regarding the relationship between DM and periodontal/peri-implant disease, emphasising the effects of glycaemic control on the severity of these diseases and describing the pathobiological mechanisms underlying this association. This review's findings indicate a bidirectional relationship between DM and periodontal/peri-implant disease and that this relationship seems causal, implying that controlling these two diseases might help prevent each other's incidence. Additionally, the severity of periodontal/peri-implant disease is directly related to metabolic control. Although patients with diabetes can obtain implant success similar to those in systemically healthy individuals, an increased risk of peri-implantitis has been reported in DM patients. Therefore, the importance of glycaemic control and maintaining proper oral hygiene cannot be overstated.

Therapeutic effects of anti-diabetic drugs on traumatic brain injury

AIMS

In this narrative review, we have analyzed and synthesized current studies relating to the effects of anti-diabetic drugs on traumatic brain injury (TBI) complications.

METHODS

Eligible studies were collected from Scopus, Google Scholar, PubMed, and Cochrane Library for clinical, in-vivo, and in-vitro studies published on the impact of anti-diabetic drugs on TBI.

RESULTS

Traumatic brain injury (TBI) is a serious brain disease that is caused by any type of trauma. The pathophysiology of TBI is not yet fully understood, though physical injury and inflammatory events have been implicated in TBI progression. Several signaling pathways are known to play pivotal roles in TBI injuries, including Nuclear factor erythroid 2-related factor 2 (Nrf2), High mobility group box 1 protein/Nuclear factor kappa B (HMGB1/NF-κB), Adiponectin, Mammalian Target of Rapamycin (mTOR), Toll-Like Receptor (TLR), Wnt/β-catenin, Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT), Nod-like receptor protein3 (NLRP3) inflammasome, Phosphoglycerate kinase 1/Kelch-like ECH-associated protein 1 (PGK1/KEAP1)/Nrf2, and Mitogen-activated protein kinase (MAPK) . Recent studies suggest that oral anti-diabetic drugs such as biguanides, thiazolidinediones (TZDs), sulfonylureas (SUs), sodium-glucose cotransporter-2 inhibitors (SGLT2is), dipeptidyl peptidase-4 inhibitors (DPPIs), meglitinides, and alpha-glucosidase inhibitors (AGIs) could have beneficial effects in the management of TBI complications. These drugs may downregulate the inflammatory pathways and induce antioxidant signaling pathways, thus alleviating complications of TBI.

CONCLUSION

Based on this comprehensive literature review, antidiabetic medications might be considered in the TBI treatment protocol. However, evidence from clinical trials in patients with TBI is still warranted.

The SLC6A15-SLC6A20 Neutral Amino Acid Transporter Subfamily: Functions, Diseases, and Their Therapeutic Relevance

The neutral amino acid transporter subfamily that consists of six members, consecutively SLC6A15-SLC620, also called orphan transporters, represents membrane, sodium-dependent symporter proteins that belong to the family of solute carrier 6 (SLC6). Primarily, they mediate the transport of neutral amino acids from the extracellular milieu toward cell or storage vesicles utilizing an electric membrane potential as the driving force. Orphan transporters are widely distributed throughout the body, covering many systems; for instance, the central nervous, renal, or intestinal system, supplying cells into molecules used in biochemical, signaling, and building pathways afterward. They are responsible for intestinal absorption and renal reabsorption of amino acids. In the central nervous system, orphan transporters constitute a significant medium for the provision of neurotransmitter precursors. Diseases related with aforementioned transporters highlight their significance; SLC6A19 mutations are associated with metabolic Hartnup disorder, whereas altered expression of SLC6A15 has been associated with a depression/stress-related disorders. Mutations of SLC6A18-SLCA20 cause iminoglycinuria and/or hyperglycinuria. SLC6A18-SLC6A20 to reach the cellular membrane require an ancillary unit ACE2 that is a molecular target for the spike protein of the SARS-CoV-2 virus. SLC6A19 has been proposed as a molecular target for the treatment of metabolic disorders resembling gastric surgery bypass. Inhibition of SLC6A15 appears to have a promising outcome in the treatment of psychiatric disorders. SLC6A19 and SLC6A20 have been suggested as potential targets in the treatment of COVID-19. In this review, we gathered recent advances on orphan transporters, their structure, functions, related disorders, and diseases, and in particular their relevance as therapeutic targets. SIGNIFICANCE STATEMENT: The following review systematizes current knowledge about the SLC6A15-SLCA20 neutral amino acid transporter subfamily and their therapeutic relevance in the treatment of different diseases.

Mechanisms and clinical applications of incretin therapies for diabetes and chronic kidney disease

PURPOSE OF REVIEW

Diabetic kidney disease (DKD) is the leading cause of kidney failure worldwide. Development of DKD increases risks for cardiovascular events and death. Glucagon-like peptide-1 (GLP-1) receptor agonist have demonstrated improved cardiovascular and kidney outcomes in large-scale clinical trials.

RECENT FINDING

GLP-1 and dual GLP-1/glucose-depending insulinotropic polypeptide (GIP) receptor agonists have robust glucose-lowering efficacy with low risk of hypoglycemia even in advanced stages of DKD. Initially approved as antihyperglycemic therapies, these agents also reduce blood pressure and body weight. Cardiovascular outcome and glycemic lowering trials have reported decreased risks of development and progression of DKD and atherosclerotic cardiovascular events for GLP-1 receptor agonists. Kidney and cardiovascular protection is mediated partly, but not entirely, by lowering of glycemia, body weight, and blood pressure. Experimental data have identified modulation of the innate immune response as a biologically plausible mechanism underpinning kidney and cardiovascular effects.

SUMMARY

An influx of incretin-based therapies has changed the landscape of DKD treatment. GLP-1 receptor agonist use is endorsed by all major guideline forming organizations. Ongoing clinical trials and mechanistic studies with GLP-1 and dual GLP-1/GIP receptor agonists will further define the roles and pathways for these agents in the treatment of DKD.

Novel Drugs for the Management of Diabetes Kidney Transplant Patients: A Literature Review

The management of diabetes and renal failure is changing thanks to the appearance of new drugs such as glucagon-like peptide 1 receptor agonists (GLP1-RA) and sodium-glucose cotransporter type 2 inhibitors (SGLT2i) that have benefits in terms of survival and cardiorenal protection. Based on the potential mechanisms of GLP1-RA, kidney transplant recipients (KTRs) could benefit from their effects. However, high-quality studies are needed to demonstrate these benefits, in the transplant population, especially those related to cardiovascular benefits and renal protection. Studies with SGLT2i performed in KTRs are much less potent than in the general population and therefore no benefits in terms of patient or graft survival have been clearly demonstrated in this population to date. Additionally, the most frequently observed side effects could be potentially harmful to this population profile, including severe or recurrent urinary tract infections and impaired kidney function. However, benefits demonstrated in KTRs are in line with a known potential effects in cardiovascular and renal protection, which may be essential for the outcome of transplant recipients. Better studies are still needed to confirm the benefits of these new oral antidiabetics in the renal transplant population. Understanding the characteristics of these drugs may be critical for KTRs to be able to benefit from their effects without being damaged. This review discusses the results of the most important published studies on KTRs with GLP1-RA and SGLT2i as well as the potential beneficial effects of these drugs. Based on these results, approximate suggestions for the management of diabetes in KTRs were developed.

The Role of Glucagon-Like Peptide-1 Receptor Agonists in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is one of the common diseases of the respiratory system. As the disease recurs, damage to the airways and lung tissue gradually worsens, leading to a progressive decline in lung function, affecting the patient's workforce and quality of life, and causing a huge social and economic burden. Diabetes is a common comorbidity of COPD and patients with COPD are at increased risk of developing diabetes, while hyperglycemia can also reduce lung function and contribute to the progression and poor prognosis of COPD. Glucagon-like peptide-1 receptor agonist (GLP-1RA) is a new type of hypoglycemic agent that has been shown to regulate blood glucose levels, reduce inflammatory responses and oxidative stress, and regulate lipid metabolism, among other effects. GLP-1RAs may benefit COPD patients by acting directly on the lung from mechanisms such as reducing the inflammatory response, improving oxidative stress, regulating protease/anti-protease imbalance, improving airway mucus homeostasis, and reducing airway remodeling. This study provides a review of the potential role of GLP-1RAs in COPD and offers new ideas for the prevention and treatment of COPD.

Benefits of GLP-1 Mimetics on Epicardial Adiposity

The epicardial adipose tissue, which is referred to as fats surrounding the myocardium, is an active organ able to induce cardiovascular problems in pathophysiologic conditions through several pathways, such as inflammation, fibrosis, fat infiltration, and electrophysiologic problems. So, control of its volume and thickness, especially in patients with diabetes, is highly important. Incretin-based pharmacologic agents are newly developed antidiabetics that could provide further cardiovascular benefits through control and modulating epicardial adiposity. They can reduce cardiovascular risks by rapidly reducing epicardial adipose tissues, improving cardiac efficiency. We are at the first steps of a long way, but current evidence demonstrates the sum of possible mechanisms. In this study, we evaluate epicardial adiposity in physiologic and pathologic states and the impact of incretin-based drugs.

Effects of DPP4 Inhibitor in Platelet Reactivity and Other Cardiac Risk Markers in Patients with Type 2 Diabetes and Acute Myocardial Infarction

Background: The management of acute myocardial infarction (AMI) presents several challenges in patients with diabetes, among them the higher rate of recurrent thrombotic events, hyperglycemia and risk of subsequent heart failure (HF). The objective of our study was to evaluate effects of DPP-4 inhibitors (DPP-4i) on platelet reactivity (main objective) and cardiac risk markers. Methods: We performed a single-center double-blind randomized trial. A total of 70 patients with type 2 diabetes (T2DM) with AMI Killip ≤2 on dual-antiplatelet therapy (aspirin plus clopidogrel) were randomized to receive sitagliptin 100 mg or saxagliptin 5 mg daily or matching placebo. Platelet reactivity was assessed at baseline, 4 days (primary endpoint) and 30 days (secondary endpoint) after randomization, using VerifyNow Aspirin™ assay, expressed as aspirin reaction units (ARUs); B-type natriuretic peptide (BNP) in pg/mL was assessed at baseline and 30 days after (secondary endpoint). Results: Mean age was 62.6 ± 8.8 years, 45 (64.3%) male, and 52 (74.3%) of patients presented with ST-segment elevation MI. For primary endpoint, there were no differences in mean platelet reactivity (p = 0.51) between the DPP-4i (8.00 {−65.00; 63.00}) and placebo (−14.00 {−77.00; 52.00}) groups, as well in mean BNP levels (p = 0.14) between DPP-4i (−36.00 {−110.00; 15.00}) and placebo (−13.00 {−50.00; 27.00}). There was no difference between groups in cardiac adverse events. Conclusions: DPP4 inhibitor did not reduce platelet aggregation among patients with type 2 diabetes hospitalized with AMI. Moreover, the use of DPP-4i did not show an increase in BNP levels or in the incidence of cardiac adverse events. These findings suggests that DPP-4i could be an option for management of T2DM patients with acute MI.

Sodium-glucose co-transporter 2 inhibitors and hematopoiesis

Many patients with diabetes mellitus, especially those with chronic kidney disorders, have some degree of anemia due to a spectrum of causes and underlying pathophysiologic pathways. As such, enhancement in erythropoiesis is important in these patients. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a relatively new class of antidiabetic drugs with confirmed protective effects in kidney and cardiovascular tissues. Recent evidence suggests that these drugs may provide additional benefits in enhancing hematopoietic processes in diabetic patients. Though the exact mediating pathways have not been fully elucidated, cellular mechanisms are likely involved. In the current study, we present the potential pathways by which SGLT2i may modulate hematopoiesis and stimulate erythropoiesis.

The anti-inflammatory and immunological properties of GLP-1 Receptor Agonists

In the last few years, a great interest has emerged in investigating the pleiotropic effects of Glucagon Like Peptide-1 Receptor Agonists (GLP-1RAs). While GLP-1RAs ability to lower plasma glucose and to induce weight loss has allowed them to be approved for the treatment of diabetes and obesity, consistent evidences from in vitro studies and preclinical models suggested that GLP-1RAs have anti-inflammatory properties and that may modulate the immune-system. Notably, such anti-inflammatory effects target different pathways in different tissues, underling the broad spectrum of GLP-1RAs actions. This review examines some of the currently proposed molecular mechanisms of GLP-1RAs actions and explores their potential benefits in reducing inflammatory responses, which may well suggest a future therapeutic use of GLP-1RAs in new indications.

Glucagon-like peptide-1: Are its roles as endogenous hormone and therapeutic wizard congruent?

Glucagon-like peptide-1 (GLP-1) is a peptide derived from differential processing of the precursor for the hormone glucagon. It is secreted predominantly by endocrine cells in the gut epithelium in response to nutrient stimulation. Studies from the last 35 years have given us an idea about its physiological functions. On the basis of some of its many actions, it has also been developed into a pharmaceutical agent for the treatment of obesity and type 2 diabetes (T2DM). It is currently positioned as the most effective anti-obesity agent available and is recommended in both national and international guidelines as an effective second-in line treatment for T2DM, in particular in patients with increased cardiovascular risk. In this review, I first discuss whether the processing of proglucagon may also result in GLP-1 formation in the pancreas and in glucagon in the gut. Next, I discuss the relationship between the physiological actions of GLP-1 and the therapeutic effects of the GLP-1 receptor agonists, which are far from being congruent and generally poorly understood. These relationships illustrate both the difficulties and the benefits of bridging results obtained in the laboratory with those emerging from the clinic.

The effect of Glucagon-like peptide-1 receptor agonists on serum uric acid concentration: A systematic review and meta-analysis

AIMS

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are a class of medications mainly used for the treatment of type 2 diabetes. They improve glucose tolerance, increase insulin secretion, and induce weight loss. There is controversy about the effect of GLP-1RAs on serum uric acid (SUA) concentration. Our systematic review aims to objectively answer whether GLP-1RAs affect SUA levels.

METHODS

We performed a systematic search on PubMed, Web of Science, Embase, Scopus, and Google Scholar datasets up to 27August,2021 with a language restriction of English only. Randomized controlled trials, observational studies, uncontrolled trials, and conference abstracts were included. Studies with insufficient data, irrelevant types of study, and follow-up duration of less than a month were excluded from the review. After critical appraisal by the Joanna Briggs Institute checklists, articles underwent data extraction using a pre-specified Microsoft Excel sheet.

RESULTS

Of 1004 identified studies, 17 were eligible for inclusion in this systematic review. Pre- to post-administration analysis of GLP-1RA effects on SUA demonstrated that GLP-1RAs could significantly reduce SUA concentration (difference in means=-0.341;SE=0.063;P-value<0.001). However, when compared to placebo, GLP-1 RAs did not perform any better in lowering SUA concentration (difference in means=-0.455;SE=0.259;P-value=0.079). Surprisingly, the active controls, that included insulin, metformin, sodium-glucose co-transporter 2 (SGLT-2) inhibitors, and dipeptidyl-peptidase 4 (DPP-4) inhibitors, did outperform GLP-1RAs in reducing SUA concentration (difference in means=0.250;SE=0.038;P-value<0.001).

CONCLUSIONS

Administration of GLP-1RAs can result in a significant reduction in SUA concentration. However, this reduction is less than that seen with the use of insulin, metformin, and SGLT-2 inhibitors.

The Impact of Incretin-Based Medications on Lipid Metabolism

Pathophysiological pathways that are induced by chronic hyperglycemia negatively impact lipid metabolism. Thus, diabetes is commonly accompanied by varying degrees of dyslipidemia which is itself a major risk factor for further macro- and microvascular diabetes complications such as atherosclerosis and nephropathy. Therefore, normalizing lipid metabolism is an attractive goal for therapy in patients with diabetes. Incretin-based medications are a novel group of antidiabetic agents with potent hypoglycemic effects. While the impact of incretins on glucose metabolism is clear, recent evidence indicates their positive modulatory roles on various aspects of lipid metabolism. Therefore, incretins may offer additional beneficial effects beyond that of glucose normalization. In the current review, how these antidiabetic medications can regulate lipid homeostasis and the possible cellular pathways involved are discussed, incorporating related clinical evidence about incretin effects on lipid homeostasis.

GLP-1 Receptor Agonist Effects on Lipid and Liver Profiles in Patients with Nonalcoholic Fatty Liver Disease: Systematic Review and Meta-Analysis

AIMS

This meta-analysis of randomized placebo-controlled clinical trials assessed the effect of glucose-like peptide-1-receptor agonists (GLP-1RA) on the lipid profile and liver enzymes in patients with nonalcoholic fatty liver disease (NAFLD).

MATERIALS AND METHODS

Randomized placebo-controlled trials investigating GLP-1RA on the lipid profile and liver enzymes in patients with NAFLD were searched in PubMed-Medline, Scopus, Web of Science, and Google Scholar databases (from inception to January 2020). A random-effects model and a generic inverse variance method were used for quantitative data synthesis. Sensitivity analysis was conducted. Weighted random-effects meta-regression was performed on potential confounders on lipid profile and liver enzyme concentrations.

RESULTS

12 studies were identified (12 GLP-1RA arms; 677 subjects) that showed treatment with GLP-1RA reduced alanine transaminase (ALT) concentrations (WMD = -10.14, 95%CI = [-15.84, -0.44], P < 0.001), gamma-glutamyl transferase (GGT) (WMD = -11.53, 95%CI = [-15.21,-7.85], P < 0.001), and alaline phosphatase (ALP) (WMD = -8.29, 95%CI = [-11.34, -5.24], P < 0.001). Aspartate aminotransferase (AST) (WMD = -2.95, 95% CI = [-7.26, 1.37], P=0.18) was unchanged. GLP-1 therapy did not alter triglycerides (TC) (WMD = -7.07, 95%CI = [-17.51, 3.37], P=0.18), total cholesterol (TC) (WMD = -1.17 (-5.25, 2.91), P=0.57), high-density lipoprotein (HDL-C) (WMD = 0.97, 95%CI = [-1.63, 3.58], P=0.46), or low-density lipoprotein (LDL-C) (WMD = -1.67, 95%CI = [-10.08, 6.74], P=0.69) in comparison with controls.

CONCLUSION

The results of this meta-analysis suggest that GLP-1RA treatment significantly reduces liver enzymes in patients with NAFLD, but the lipid profile is unaffected.

The role of GLP-1 receptor agonists during COVID-19 pandemia: a hypothetical molecular mechanism

INTRODUCTION

A number of anti-diabetic treatments have been favored during the continuing spread of the current SARS-CoV-2 pandemic. Glucagon like peptide-1 receptor agonists (GLP1-RAs) are a group of antidiabetic drugs, the glucose reducing effect of which is founded on augmenting glucose-dependent insulin secretion with concomitant reduction of glucagon secretion and delayed gastric emptying. Apart from their glucose lowering effects, GLP1-RAs also exert a plethora of pleiotropic activities in the form of anti-inflammatory, anti-thrombotic and anti-obesogenic properties, with beneficial cardiovascular and renal impact. All these make this class of drugs a preferred option for managing patients with type 2 diabetes (T2D), and potentially helpful in those with SARS-CoV2 infection.

AREAS COVERED

In the present article we propose a hypothetical molecular mechanism by which GLP1-RAs may interact with SARS-CoV-2 activity.

EXPERT OPINION

The beneficial properties of GLP1-RAs may be of specific importance during COVID-19 infection for the most fragile patients with chronic comorbid conditions such as T2D, and those at higher cardiovascular and renal disease risk. Yet, further studies are needed to confirm our hypothesis and preliminary findings available in the literature.

Anti-Diabetic Drugs GLP-1 Agonists and DPP-4 Inhibitors may Represent Potential Therapeutic Approaches for COVID-19

The fast spread of coronavirus 2019 (COVID-19) calls for immediate action to counter the associated significant loss of human life and deep economic impact. Certain patient populations like those with obesity and diabetes are at higher risk for acquiring severe COVID-19 disease and have a higher risk of COVID-19 associated mortality. In the absence of an effective and safe vaccine, the only immediate promising approach is to repurpose an existing approved drug. Several drugs have been proposed and tested as adjunctive therapy for COVID-19. Among these drugs are the glucagon-like peptide-1 (GLP-1) 2 agonists and the dipeptidylpeptidase-4 (DPP-4) inhibitors. Beyond their glucose-lowering effects, these drugs have several pleiotropic protective properties, which include cardioprotective effects, anti-inflammatory and immunomodulatory activities, antifibrotic effects, antithrombotic effects, and vascular endothelial protective properties. This narrative review discusses these protective properties and addresses their scientific plausibility for their potential use as adjunctive therapy for COVID-19 disease.

The role of incretins and incretin-based drugs in autoimmune diseases

Incretin hormones, including glucagon-like peptide (GLP)-1, GLP-2 and glucose-dependent insulinotropic polypeptide (GIP), are gastrointestinal peptides secreted from enteroendocrine cells. These hormones play significant roles in many physiological processes via binding to G-protein coupled receptors (GPCRs) on different organs and tissues; one of them is the immunomodulatory effect on the immune system and its molecular components such as cytokines and chemokines. Anti-inflammatory effects of incretins and dependent molecules involving long-acting analogs and DPP4 inhibitors through regulation of T and B cell activation may attenuate autoimmune diseases caused by immune system disorders in mistakenly recognizing self as the foreign agent. In this review, we investigate incretin effects on the immune system response and the potential benefits of incretin-based therapy for treating autoimmune diseases.

Deciphering the Neuroprotective Role of Glucagon-like Peptide-1 Agonists in Diabetic Neuropathy: Current Perspective and Future Directions

Diabetic neuropathy is referred to as a subsequential and debilitating complication belonging to type 1 and type 2 diabetes mellitus. It is a heterogeneous group of disorders with a particularly complex pathophysiology and also includes multiple forms, ranging from normal discomfort to death. The evaluation of diabetic neuropathy is associated with hyperglycemic responses, resulting in an alteration in various metabolic pathways, including protein kinase C pathway, polyol pathway and hexosamine pathway in Schwann and glial cells of neurons. The essential source of neuronal destruction is analogous to these respective metabolic pathways, thus identified as potential therapeutic targets. These pathways regulating therapeutic medications may be used for diabetic neuropathy, however, only target specific drugs could have partial therapeutic activity. Various antidiabetic medications have been approved and marketed, which possess the therapeutic ability to control hyperglycemia and ameliorate the prevalence of diabetic neuropathy. Among all antidiabetic medications, incretin therapy, including Glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, are the most favorable medications for the management of diabetes mellitus and associated peripheral neuropathic complications. Besides enhancing glucose-evoked insulin release from pancreatic β-cells, these therapeutic agents also play a vital role to facilitate neurite outgrowth and nerve conduction velocity in dorsal root ganglion. Furthermore, incretin therapy also activates cAMP and ERK signalling pathways, resulting in nerve regeneration and repairing. These effects are evidently supported by a series of preclinical data and investigations associated with these medications. However, the literature lacks adequate clinical trial outcomes related to these novel antidiabetic medications. The manuscript emphasizes the pathogenesis, current pharmacological approaches and vivid description of preclinical and clinical data for the effective management of diabetic neuropathy.

Antioxidative Potentials of Incretin-Based Medications: A Review of Molecular Mechanisms

Glucagon-like peptide 1 receptor agonists and dipeptidyl-peptidase 4 inhibitors are medications used for managing diabetes, mimicking the metabolic effects of incretin hormones. Recent evidence suggests that these medications have antioxidative potentials in the diabetic milieu. The pathophysiology of most diabetic complications involves oxidative stress. Therefore, if incretin-based antidiabetic medications can alleviate the free radicals involved in oxidative stress, they can potentially provide further therapeutic effects against diabetic complications. However, the molecular mechanisms by which these medications protect against oxidative stress are not fully understood. In the current review, we discuss the potential molecular mechanisms behind these pharmacologic agents' antioxidative properties.

Incretin drugs in diabetic kidney disease: biological mechanisms and clinical evidence

As the prevalence of diabetes continues to climb, the number of individuals living with diabetic complications will reach an unprecedented magnitude. The emergence of new glucose-lowering agents - sodium-glucose cotransporter 2 inhibitors and incretin therapies - has markedly changed the treatment landscape of type 2 diabetes mellitus. In addition to effectively lowering glucose, incretin drugs, which include glucagon-like peptide 1 receptor (GLP1R) agonists and dipeptidyl peptidase 4 (DPP4) inhibitors, can also reduce blood pressure, body weight, the risk of developing or worsening chronic kidney disease and/or atherosclerotic cardiovascular events, and the risk of death. Although kidney disease events have thus far been secondary outcomes in clinical trials, an ongoing phase III trial in patients with diabetic kidney disease will test the effect of a GLP1R agonist on a primary kidney disease outcome. Experimental data have identified the modulation of innate immunity and inflammation as plausible biological mechanisms underpinning the kidney-protective effects of incretin-based agents. These drugs block the mechanisms involved in the pathogenesis of kidney damage, including the activation of resident mononuclear phagocytes, tissue infiltration by non-resident inflammatory cells, and the production of pro-inflammatory cytokines and adhesion molecules. GLP1R agonists and DPP4 inhibitors might also attenuate oxidative stress, fibrosis and cellular apoptosis in the kidney.

Antidiabetic Properties of Curcumin: Insights on New Mechanisms

Plant extracts have been used to treat a wide range of human diseases. Curcumin, a bioactive polyphenol derived from Curcuma longa L., exhibits therapeutic effects against diabetes while only negligible adverse effects have been observed. Antioxidant and anti-inflammatory properties of curcumin are the main and well-recognized pharmacological effects that might explain its antidiabetic effects. Additionally, curcumin may regulate novel signaling molecules and enzymes involved in the pathophysiology of diabetes, including glucagon-like peptide-1, dipeptidyl peptidase-4, glucose transporters, alpha-glycosidase, alpha-amylase, and peroxisome proliferator-activated receptor gamma (PPARγ). Recent findings from in vitro and in vivo studies on novel signaling pathways involved in the potential beneficial effects of curcumin for the treatment of diabetes are discussed in this review.

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.

The Effects of Glucagon-Like Peptide-1 Receptor Agonists and Dipeptydilpeptidase-4 Inhibitors on Blood Pressure and Cardiovascular Complications in Diabetes

Glucagon-like peptide-1 receptor (GLP-1R) agonists are a class of newly introduced antidiabetic medications that potentially lower blood glucose by several molecular pathways. DPP-4 inhibitors are the other type of novel antidiabetic medications which act by preventing GLP-1 inactivation and thereby increasing the activity levels of GLP-1, leading to more glucose-induced insulin release from islet β-cells and suppression of glucagon release. Most patients with diabetes have concurrent hypertension and cardiovascular disorder. If antihyperglycemic agents can attenuate the risk of hypertension and cardiovascular disease, they will amplify their overall beneficial effects. There is conflicting evidence on the cardiovascular benefits of GLP-1R induction in laboratory studies and clinical trials. In this study, we have reviewed the main molecular mechanisms by which GLP-1R induction may modulate the cardiovascular function and the results of cardiovascular outcome clinical trials.

Ranolazine Improves Glycemic Variability and Endothelial Function in Patients with Diabetes and Chronic Coronary Syndromes: Results from an Experimental Study

BACKGROUND

Ranolazine is a second-line drug for the management of chronic coronary syndromes (CCS). Glucose-lowering and endothelial effects have also been reported with this agent. However, whether ranolazine may improve short-term glycemic variability (GV), strictly related to the prognosis of patients with type 2 diabetes (T2D), is unknown. Thus, we aimed to explore the effects of adding ranolazine to standard anti-ischemic and glucose-lowering therapy on long- and short-term GV as well as on endothelial function and oxidative stress in patients with T2D and CCS.

METHODS

Patients starting ranolazine (n = 16) were evaluated for short-term GV, haemoglobin 1Ac (Hb1Ac) levels, endothelial-dependent flow-mediated vasodilation (FMD), and oxidative stress levels at enrolment and after 3-month follow-up. The same measurements were collected from 16 patients with CCS and T2D that did not receive ranolazine, matched for age, gender, and body mass index.

RESULTS

A significant decline in Hb1Ac levels was reported after 3-month ranolazine treatment (mean change -0.60%; 2-way ANOVA p = 0.025). Moreover, among patients receiving ranolazine, short-term GV indexes were significantly improved over time compared with baseline (p = 0.001 for time in range; 2-way ANOVA p = 0.010). Conversely, no significant changes were reported in patients without ranolazine. Finally, greater FMD and lower oxidative stress levels were observed in patients on ranolazine at 3 months.

CONCLUSIONS

Ranolazine added to standard anti-ischemic and glucose-lowering therapy demonstrated benefit in improving the glycemic status of patients with T2D and CCS. How this improvement contributes to the overall myocardial benefit of ranolazine requires further studies.

The Impact of Diabetes Mellitus in COVID-19: A Mechanistic Review of Molecular Interactions

The ongoing pandemic of COVID-19 is now the major issue in global health. Evidence implies that patients with diabetes are at a higher risk of severe disease or death due to COVID-19 than individuals without diabetes. However, the underlying mechanism for this differential effect in individuals with and without diabetes is not clearly understood. We have reviewed the pathophysiological pathways which may facilitate the entry of virus or an increase in its infectivity in host cells in the diabetic milieu. We suggest that the preexisting pathological pathways in patients with poorly controlled diabetes increase the risk of infectivity and are responsible for the higher levels of tissue injury and death in patients with diabetes.

Exenatide extended release in patients with type 1 diabetes with and without residual insulin production

AIMS

To test whether a long-acting GLP-1 receptor agonist would improve glucose control in patients with type 1 diabetes (T1D) and to determine whether the presence of residual beta cell function would affect the response. In addition, we sought to determine whether the drug would affect beta cell function.

METHODS

We performed a randomized placebo-controlled trial of exenatide extended release (ER) in participants with T1D with and without detectable levels of C-peptide. Seventy-nine participants were randomized to exenatide ER 2 mcg weekly, or placebo, stratified by the presence or absence of detectable C-peptide levels. The primary outcome was the difference in glycated haemoglobin (HbA1c) levels at 24 weeks. Participants were followed for another 6 months off study drug.

RESULTS

At week 24, the time of the primary outcome, the least squares (LS) mean HbA1c level was 7.76% (95% confidence interval [CI] 7.42, 8.10) in the exenatide ER group versus 8.0% (95% CI 7.64, 8.35) in the placebo group (P = 0.08). At week 12 the LS mean HbA1c levels were 7.71% (95% CI 7.37, 8.05) in the exenatide ER group versus 8.05% (95% CI 7.7, 8.4) in the placebo group (P = 0.01). The improvement at week 12 was driven mainly by those with detectable levels of C-peptide. Those treated with exenatide ER lost weight at 12 and 24 weeks compared to those treated with placebo (P <0.001 and P = 0.007). The total insulin dose was lower, but not when corrected for body weight, and was not affected by residual insulin production. Adverse events were more frequent with exenatide ER, but hypoglycaemia was not increased.

CONCLUSION

Treatment with exenatide ER may have short-term benefits in some individuals with T1D who are overweight or who have detectable levels of C-peptide, but short-term improvements were not sustained.

Pyrazole Incorporated New Thiosemicarbazones: Design, Synthesis and Investigation of DPP-4 Inhibitory Effects

Dipeptidyl peptidase-4 (DPP-4) inhibition has been recognized as a promising approach to develop safe and potent antidiabetic agents for the management of type 2 diabetes. In this context, new thiosemicarbazones (2a-o) were prepared efficiently by the reaction of aromatic aldehydes with 4-[4-(1H-pyrazol-1-yl)phenyl]thiosemicarbazide (1), which was obtained via the reaction of 4-(1H-pyrazol-1-yl)phenyl isothiocyanate with hydrazine hydrate. Compounds 2a-o were evaluated for their DPP-4 inhibitory effects based on a convenient fluorescence-based assay. 4-[4-(1H-pyrazol-1-yl)phenyl]-1-(4-bromobenzylidene)thiosemicarbazide (2f) was identified as the most effective DPP-4 inhibitor in this series with an IC₅₀ value of 1.266 ± 0.264 nM when compared with sitagliptin (IC₅₀ = 4.380 ± 0.319 nM). MTT test was carried out to assess the cytotoxic effects of compounds 2a-o on NIH/3T3 mouse embryonic fibroblast (normal) cell line. According to cytotoxicity assay, compound 2f showed cytotoxicity towards NIH/3T3 cell line with an IC₅₀ value higher than 500 µM pointing out its favourable safety profile. Molecular docking studies indicated that compound 2f presented π-π interactions with Arg358 and Tyr666 via pyrazole scaffold and 4-bromophenyl substituent, respectively. Overall, in vitro and in silico studies put emphasis on that compound 2f attracts a great notice as a drug-like DPP-4 inhibitor for further antidiabetic research.

GLP-1 mimetics and cognition

Glucagon-like peptide-1 (GLP-1) receptor agonists are a class of antidiabetic drugs that improve the glycaemia via several molecular pathways. Recent evidence suggest that they also have additional effects modulating pathophysiologic pathways included in cognitive disorders. Since some forms of cognitive dysfunction such as Alzheimer's disease are more common among diabetic patients than in the normal population, antidiabetic drugs that have neuroprotective effects affording protection for cognitive disorders would be of benefit. Therefore, we reviewed the pharmacologic effects of GLP-1 analogues and found that they may have the additional benefit of improving cognitive performance via at least eight molecular mechanisms.

Glucagon-like peptide-1 receptor agonist liraglutide therapy for psoriasis patients with type 2 diabetes: a randomized-controlled trial

OBJECTIVE

There were some clinical studies on GLP-1R agonist liraglutide therapy for psoriasis patients with type 2 diabetes, but there is a lack of randomized controlled trials and the mechanism of which remains unclear.

METHOD

A total of 25 psoriasis patients with type 2 diabetes were randomized 1: 1 divided into the control group (n = 13) or liraglutide group (n = 12) for 12 weeks. We determined the PASI, the DLQI, histopathology of psoriasis skin, and the expression of IL-17, IL-23, and TNF-α in the psoriasis skin.

RESULTS

After 12 weeks of treatment, the mean DLQI of the treatment group decreased from 22.00 ± 5.85 to 3.82 ± 3.60 (p < .05). Compared to week 12, the change in the baseline value of PASI and DLQI in the treatment group showed a significant difference compared with the control group (p < .05). The pathological changes of psoriasis skin and the expression of IL-17, IL-23, TNF-α in the psoriasis skin were improved in the treatment group. No serious adverse events occurred.

CONCLUSION

The skin lesions in psoriasis patients with type 2 diabetes were significantly improved after treatment with liraglutide, which may be related to the inhibition of the expression of inflammatory factors such as IL-23, IL-17, and TNF-α.

Multiplex Bead Array Assay of a Panel of Circulating Cytokines and Growth Factors in Patients with Albuminuric and Non-AlbuminuricDiabetic Kidney Disease

A panel of cytokines and growth factors, mediating low-grade inflammation and fibrosis, was assessed in patients with type 2 diabetes (T2D) and different patterns of chronic kidney disease (CKD). Patients with long-term T2D (N = 130) were classified into four groups: no signs of CKD; estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² without albuminuria; albuminuria and eGFR ≥60 mL/min/1.73 m²; albuminuria and eGFR <60 mL/min/1.73 m². Thirty healthy subjects were acted as control. Twenty-seven cytokines and growth factors were assessed in serum by multiplex bead array assay. Serum hs-CRP, urinary nephrin, podocine, and WFDC2 were measured by ELISA. Patients with T2D showed elevated IL-1Ra, IL-6, IL-17A, G-CSF, IP-10, MIP-1α, and bFGF levels; concentrations of IL-4, IL-12, IL-15, INF-γ, and VEGF were decreased. IL-6, IL-17A, G-CSF, MIP-1α, and bFGF correlated negatively with eGFR; IL-10 and VEGF demonstrated negative associations with WFDC2; no relationships with podocyte markers were found. Adjusted IL-17A and MIP-1α were predictors of non-albuminuric CKD, IL-13 predicted albuminuria with preserved renal function, meanwhile, IL-6 and hsCRP were predictors of albuminuria with eGFR decline. Therefore, albuminuric and non-albuminuric CKD in T2D patients are associated with different pro-inflammatory shifts in the panel of circulating cytokines.

Incretin-based therapies and renin-angiotensin system: Looking for new therapeutic potentials in the diabetic milieu

Incretin-based therapies include pharmacologic agents such as glucagon like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors which exert potent anti-hyperglycemic effects in the diabetic milieu. They are also shown to have extra-pancreatic effects. Renin-angiotensin system is part of the endocrine system which is widely distributed in the body and is closely involved in water and electrolyte homeostasis as well as renal and cardiovascular functions. Hence the renin-angiotensin system is the main target for treating patients with various renal and cardiovascular disorders. There is growing evidence that incretins have modulatory effects on renin-angiotensin system activity; thereby, can be promising therapeutic agents for the management of renal and cardiovascular disorders. But the exact molecular interactions between incretins and renin-angiotensin system are not clearly understood. In this current study, we have reviewed the possible molecular mechanisms by which incretins modulate renin-angiotensin system activity.