Cardiovascular biology of the incretin system

[Cardiovascular safety of sitagliptin added to metformin in real world patients with type 2 diabetes]

OBJECTIVE

To assess the safety of sitagliptin added to metformin on cardiovascular adverse events in real world patients with type 2 diabetes mellitus (T2DM).

METHODS

Real world data from Yinzhou Regional Health Care Database were used to select T2DM patients with diagnosis and treatment records in the platform from January 1, 2017 to December 31, 2022. According to drug prescription records, the patients were divided into metformin plus sitagliptin group (combination group) and metformin monotherapy group(monotherapy group). A series of retrospective cohorts were constructed according to the index date.Finally, full retrospective cohorts were constructed according to propensity score model, including baseline covariates that might be related to outcomes, to match the subjects in the combination group and monotherapy group for the purpose of increasing the comparability of baseline characteristics. The participants were followed up from the index date until the first occurrence of the following events: Diagnosis of outcomes, death, or the end of the study period (December 31, 2022). Cox proportional risk model was used to estimate the hazard ratio(HR)and 95% confidence interval (CI) of sitagliptin added to metformin on 3-point major adverse cardiovascular events (3P-MACE) combination outcome and secondary cardiovascular outcomes.

RESULTS

Before propensity score matching, the proportion of the patients in combination group using insulin, α glucosidase inhibitors, sodium-glucose transporter 2 inhibitors (SGLT-2I) and glienides at baseline was higher than that in monotherapy group, and the baseline fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) levels in combination group were higher than those in monotherapy group. After propensity score matching, 5 416 subjects were included in the combination group and the monotherapy group, and baseline characteristics were effectively balanced between the groups. The incidence densities of 3P-MACE were 6.41/100 person years and 6.35/100 person years, respectively. Sitagliptin added to metformin did not increase or decrease the risk of 3P-MACE compared with the metformin monotherapy (HR=1.00, 95% CI: 0.91-1.10). In secondary outcomes analysis, the incidence of cardiovascular death was lower in the combination group than in the monotherapy group (HR=0.59, 95% CI: 0.41-0.85), and no association was found between sitagliptin and the risk of myocardial infarction and stroke (HR=1.12, 95% CI: 0.89-1.41; HR=0.99, 95% CI: 0.91-1.12).

CONCLUSION

In T2DM patients in Yinzhou district of Ningbo, compared with metformin alone, sitagliptin added to metformin may reduce the risk of cardiovascular death, and do not increase the incidence of overall cardiovascular events. The results of this study can provide real-world evidence for post-marketing cardiovascular safety evaluation of sitagliptin.

Comparation of fixed-ratio (IDegLira and iGlarLixi) versus free combination of basal insulin and glucagon-like peptide-1 receptor agonist for uncontrolled type 2 diabetes: A systematic review and network meta-analysis

OBJECTIVE

This study aimed to evaluate the safety and efficacy of the fixed-ratio combination (FRC) and free combination of basal insulin and glucagon-like peptide-1 receptor agonist (GLP-1RA) in patients with type 2 diabetes mellitus (T2DM).

METHODS

PubMed, Web of Science, Embase, The Cochrane Library, and four Chinese databases were searched for relevant studies from inception to April 13, 2023. Phase III clinical trials involving FRC or free combination in patients with uncontrolled T2DM were included. A network meta-analysis (NMA) was used to evaluate the effects of FRC and free combination. The Cochrane Collaboration's tool was used to evaluate the risk-of-bias. The primary outcomes were changes in hemoglobin A1c (HbA1c), body weight, and incident hypoglycemia. Secondary outcomes included changes in systolic blood pressure (SBP) and diastolic blood pressure (DBP). This study was registered with PROSPERO (CRD42023409585).

RESULTS

Forty-two trials with 23,619 patients were included in the NMA, and treatments were categorized as FRC, free combination and NOINSGLP (neither FRC nor free combination). The forest plots revealed comparable HbA1c control (mean difference (MD) = 0.07%, 95% confidence interval (CI): -0.17 to -0.30) between free combination and FRC. However, there were significant differences in the body weight (MD = -2.06 kg; 95% CI: -3.34 to -0.77), SBP (MD = -1.22 mmHg; 95% CI: -2.41 to -0.04), and DBP (MD = -1.09 mmHg; 95% CI: -1.94 to -0.24) between the two groups.

CONCLUSIONS

In patients with uncontrolled T2DM, the safety and efficacy of FRC and free combination therapy were comparable. The use of FRC is justifiable in patients requiring free combination.

A New Age for Secondary Prevention: Optimal Medical Therapy for Stable Ischemic Heart Disease Among Patients with Diabetes and/or Obesity

Patients with type 2 diabetes and/or obesity and established cardiovascular disease are at increased risk for recurrent cardiovascular events. The indications of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter-2 inhibitors have been expanded in the last decade due to benefit in cardiovascular outcome trials and are now considered guideline-recommended therapy for patients with type 2 diabetes and cardiovascular disease. Emerging data have begun to suggest that GLP-1RAs can decrease major adverse cardiovascular events among patients with obesity without diabetes. Overall, prescription of these agents remains low, despite being key to improve disparities in recurrent cardiovascular events. In this review, we discuss optimal medical therapy for secondary prevention for stable ischemic heart disease.

GLP-1R signaling modulates colonic energy metabolism, goblet cell number and survival in the absence of gut microbiota

OBJECTIVES

Gut microbiota increases energy availability through fermentation of dietary fibers to short-chain fatty acids in conventionally raised mice. Energy deficiency in germ-free (GF) mice increases glucagon-like peptide-1 (GLP-1) levels, which slows intestinal transit. To further analyze the role of GLP-1-mediated signaling in this model of energy deficiency, we re-derived mice lacking GLP-1 receptor (GLP-1R KO) as GF.

METHODS

GLP-1R KO mice were rederived as GF through hysterectomy and monitored for 30 weeks. Mice were subjected to rescue experiments either through feeding an energy-rich diet or colonization with a normal cecal microbiota. Histology and intestinal function were assessed at different ages. Intestinal organoids were assessed to investigate stemness.

RESULTS

Unexpectedly, 25% of GF GLP-1R KO mice died before 20 weeks of age, associated with enlarged ceca, increased cecal water content, increased colonic expression of apical ion transporters, reduced number of goblet cells and loss of colonic epithelial integrity. Colonocytes from GLP-1R KO mice were energy-deprived and exhibited increased ER-stress; mitochondrial fragmentation, increased oxygen levels and loss of stemness. Restoring colonic energy levels either by feeding a Western-style diet or colonization with a normal gut microbiota normalized gut phenotypes and prevented lethality.

CONCLUSIONS

Our findings reveal a heretofore unrecognized role for GLP-1R signaling in the maintenance of colonic physiology and survival during energy deprivation.

Safety and Efficacy of GLP-1 Receptor Agonists in Type 2 Diabetes Mellitus with Advanced and End-Stage Kidney Disease: A Systematic Review and Meta-Analysis

Background and Objectives: Limited evidence exists regarding the safety and efficacy of glucagon-like peptide-1 receptor agonists (GLP-1RAs) in type 2 diabetes mellitus (T2DM) patients with advanced chronic kidney disease (CKD) or end-stage kidney disease (ESKD). Thus, we conducted a systematic review and meta-analysis to assess the safety and efficacy of GLP-1RAs in T2DM patients with advanced CKD and ESKD. Materials and Methods: We performed a systematic literature search in MEDLINE, EMBASE, and Cochrane database until 25 October 2023. Included were clinical trials and cohort studies reporting outcomes of GLP-1RAs in adult patients with T2DM and advanced CKD. Outcome measures encompassed mortality, cardiovascular parameters, blood glucose, and weight. Safety was assessed for adverse events. The differences in effects were expressed as odds ratios with 95% confidence intervals (CIs) for dichotomous outcomes and the weighted mean difference or standardized mean difference (SMD) with 95% confidence intervals for continuous outcomes. The Risk of Bias In Non-randomized Studies-of Interventions (ROBIN-I) tool was used in cohort and non-randomized controlled studies, and the Cochrane Risk of Bias (RoB 2) tool was used in randomized controlled trials (RCTs). The review protocol was registered in the International Prospective Register of Systematic Reviews (CRD 42023398452) and received no external funding. Results: Eight studies (five trials and three cohort studies) consisting of 27,639 patients were included in this meta-analysis. No difference was observed in one-year mortality. However, GLP-1RAs significantly reduced cardiothoracic ratio (SMD of -1.2%; 95% CI -2.0, -0.4) and pro-BNP (SMD -335.9 pmol/L; 95% CI -438.9, -232.8). There was no significant decrease in systolic blood pressure. Moreover, GLP-1RAs significantly reduced mean blood glucose (SMD -1.1 mg/dL; 95% CI -1.8, -0.3) and increased weight loss (SMD -2.2 kg; 95% CI -2.9, -1.5). In terms of safety, GLP-1RAs were associated with a 3.8- and 35.7-time higher risk of nausea and vomiting, respectively, but were not significantly associated with a higher risk of hypoglycemia. Conclusions: Despite the limited number of studies in each analysis, our study provides evidence supporting the safety and efficacy of GLP-1RAs among T2DM patients with advanced CKD and ESKD. While gastrointestinal side effects may occur, GLP-1RAs demonstrate significant improvements in blood glucose control, weight reduction, and potential benefit in cardiovascular outcomes.

Management of type 2 diabetes in patients with compensated liver cirrhosis: Short of evidence, plenty of potential

BACKGROUND AND AIMS

Treatment of type 2 diabetes (T2D) in patients with compensated cirrhosis is challenging due to hypoglycemic risk, altered pharmacokinetics, and the lack of robust evidence on the risk/benefit ratio of various drugs. Suboptimal glycemic control accelerates the progression of cirrhosis, while the frequent coexistence of nonalcoholic fatty liver disease (NAFLD) with T2D highlights the need for a multifactorial therapeutic approach.

METHODS

A literature search was performed in Medline, Google Scholar and Scopus databases till July 2023, using relevant keywords to extract studies regarding the management of T2D in patients with compensated cirrhosis.

RESULTS

Metformin, sodium-glucose co-transporter-2 inhibitors (SGLT2i), and glucagon-like peptide-1 receptor agonists (GLP-1 RA) are promising treatment options for patients with T2D and compensated liver cirrhosis, offering good glycemic control with minimal risk of hypoglycemia, while their pleiotropic actions confer benefits on NAFLD and body weight, and decrease cardiorenal risk. Sulfonylureas cause hypoglycemia, thus should be avoided, while in specific studies, dipeptidyl peptidase-4 inhibitors have been correlated with increased risk of decompensation and variceal bleeding. Despite the benefits of thiazolidinediones in nonalcoholic steatohepatitis, concerns about edema and weight gain limit their use in compensated cirrhosis. Insulin does not exert hepatotoxic effects and can be administered safely in combination with other drugs; however, the risk of hypoglycemia should be considered.

CONCLUSIONS

The introduction of new hepatoprotective diabetes drugs into clinical practice, including tirzepatide, SGLT2i, and GLP-1 RA, sets the stage for future trials to investigate the ideal therapeutic regimen for people with T2D and compensated cirrhosis.

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.

The Role of Perivascular Adipose Tissue in the Pathogenesis of Endothelial Dysfunction in Cardiovascular Diseases and Type 2 Diabetes Mellitus

Cardiovascular diseases (CVDs) and type 2 diabetes mellitus (T2DM) are two of the four major chronic non-communicable diseases (NCDs) representing the leading cause of death worldwide. Several studies demonstrate that endothelial dysfunction (ED) plays a central role in the pathogenesis of these chronic diseases. Although it is well known that systemic chronic inflammation and oxidative stress are primarily involved in the development of ED, recent studies have shown that perivascular adipose tissue (PVAT) is implicated in its pathogenesis, also contributing to the progression of atherosclerosis and to insulin resistance (IR). In this review, we describe the relationship between PVAT and ED, and we also analyse the role of PVAT in the pathogenesis of CVDs and T2DM, further assessing its potential therapeutic target with the aim of restoring normal ED and reducing global cardiovascular risk.

GLP-1RAs and cardiovascular disease: is the endothelium a relevant platform?

Hyperglycemia strongly affects endothelial function and activation, which in turn increases the risk of atherosclerotic cardiovascular disease. Among pharmacotherapies aimed at lowering blood glucose levels, glucagon-like peptide 1 receptor agonists (GLP-1RA) represent a class of drugs involved in the improvement of the endothelium damage and the progression of cardiovascular diseases. They show antihypertensive and antiatherosclerotic actions due at least in part to direct favorable actions on the coronary vascular endothelium, such as oxidative stress reduction and nitric oxide increase. However, cumulative peripheral indirect actions could also contribute to the antiatherosclerotic functions of GLP-1/GLP-1R agonists, including metabolism and gut microbiome regulation. Therefore, further research is necessary to clarify the specific role of this drug class in the management of cardiovascular disease and to identify specific cellular targets involved in the protective signal transduction. In the present review, we provide an overview of the effects of GLP-1RAs treatment on cardiovascular disease with particular attention on potential molecular mechanisms involving endothelium function on formation and progression of atherosclerotic plaque.

Environmentally friendly protocol for the determination of sitagliptin phosphate in pharmaceutical preparations and biological fluids using l-tyrosine as a fluorescence probe

A responsive spectrofluorometric method was developed for the determination of sitagliptin phosphate using l-tyrosine as a fluorescence probe. The fluorescence intensity of l-tyrosine was quenched with sitagliptin phosphate. The fluorescence intensity was recorded at 307 nm using a 272 nm excitation wavelength. The calibration plot between fluorescence intensity and the concentration of drug was linear in the range of 0.1 to 2.0 mM with a good correlation value of 0.997. The limit of detection and quantification were established to be 3.7 × 10-4 and 1.23 × 10-3  mM, respectively. Commonly used excipients did not interfere with sitagliptin phosphate measurement. The proposed method was used to measure the sitagliptin phosphate in its standard type, dosage form, and biological samples. The percent recovery ranged from 97.41-103.36%. The static quenching was shown to be responsible for quenching as indicated by the Stern-Volmer plot. The method was validated using ICH guidelines and profitably applied for the content uniformity test, resulting in a high percent recovery and small relative standard deviation. The proposed approach is effortless, susceptible, selective, economic, and provides a high precision and accuracy, and can be used to determine sitagliptin phosphate in the pharmaceutical industry.

Perivascular Adipose Tissue Oxidative Stress in Obesity

Perivascular adipose tissue (PVAT) adheres to most systemic blood vessels in the body. Healthy PVAT exerts anticontractile effects on blood vessels and further protects against cardiovascular and metabolic diseases. Healthy PVAT regulates vascular homeostasis via secreting an array of adipokine, hormones, and growth factors. Normally, homeostatic reactive oxygen species (ROS) in PVAT act as secondary messengers in various signalling pathways and contribute to vascular tone regulation. Excessive ROS are eliminated by the antioxidant defence system in PVAT. Oxidative stress occurs when the production of ROS exceeds the endogenous antioxidant defence, leading to a redox imbalance. Oxidative stress is a pivotal pathophysiological process in cardiovascular and metabolic complications. In obesity, PVAT becomes dysfunctional and exerts detrimental effects on the blood vessels. Therefore, redox balance in PVAT emerges as a potential pathophysiological mechanism underlying obesity-induced cardiovascular diseases. In this review, we summarise new findings describing different ROS, the major sources of ROS and antioxidant defence in PVAT, as well as potential pharmacological intervention of PVAT oxidative stress in obesity.

Glucagon-Like Peptide-1 Protects Against Atrial Fibrillation and Atrial Remodeling in Type 2 Diabetic Mice

Atrial fibrillation (AF) is highly prevalent in type 2 diabetes where it increases morbidity and mortality. Glucagon-like peptide (GLP)-1 receptor agonists are used in the treatment of type 2 diabetes (T2DM), but their effects on AF in T2DM are poorly understood. The present study demonstrates type 2 diabetic db/db mice are highly susceptible to AF in association with atrial electrical and structural remodeling. GLP-1, as well as the long-acting GLP-1 analogue liraglutide, reduced AF and prevented atrial remodeling in db/db mice. These data suggest that GLP-1 and related analogues could protect against AF in patients with T2DM.

Glucagon-like peptide 1 receptor agonists: cardiovascular benefits and mechanisms of action

Type 2 diabetes mellitus (T2DM) and obesity are metabolic disorders characterized by excess cardiovascular risk. Glucagon-like peptide 1 (GLP1) receptor (GLP1R) agonists reduce body weight, glycaemia, blood pressure, postprandial lipaemia and inflammation - actions that could contribute to the reduction of cardiovascular events. Cardiovascular outcome trials (CVOTs) have demonstrated that GLP1R agonists reduce the rates of major adverse cardiovascular events in patients with T2DM. Separate phase III CVOTs of GLP1R agonists are currently being conducted in people living with heart failure with preserved ejection fraction and in those with obesity. Mechanistically, GLP1R is expressed at low levels in the heart and vasculature, raising the possibility that GLP1 might have both direct and indirect actions on the cardiovascular system. In this Review, we summarize the data from CVOTs of GLP1R agonists in patients with T2DM and describe the actions of GLP1R agonists on the heart and blood vessels. We also assess the potential mechanisms that contribute to the reduction in major adverse cardiovascular events in individuals treated with GLP1R agonists and highlight the emerging cardiovascular biology of novel GLP1-based multi-agonists currently in development. Understanding how GLP1R signalling protects the heart and blood vessels will optimize the therapeutic use and development of next-generation GLP1-based therapies with improved cardiovascular safety.

Re-evaluation of dipeptidyl peptidase-4 inhibitors in patients with heart failure and diabetes mellitus

OBJECTIVES

The question of whether dipeptidyl peptidase-4 inhibitors (DPP-4i) should be preferred as new glucose-lowering agents in heart failure is controversial. This studyaimed to evaluate the effects of DPP-4i treatment on all-cause mortality and cardiovascular outcomes in patients with heart failure.

METHODS

We searched for available studies of DPP-4i therapy in heart failure and performed a pooled analysis. Outcomes included all-cause mortality, cardiovascular death, hospitalization for heart failure, left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), acute coronary syndrome, and acute myocardial infarction.

RESULTS

Treatment with DPP-4i did not reduce the risk of all-cause death, cardiovascular death, or hospitalization for heart failure. Subgroup analyses showed that DPP-4i significantly reduced all-cause mortality in trials with >40% female patients (OR 0.30, 95% CI [0.16, 0.58], P=0.0003) and in trials with >20% patients with heart failure with preserved ejection fraction (HFpEF) (OR 0.34, 95% CI [0.19, 0.60], P=0.0003). Changes in LVEF and LVEDV showed no statistical differences between the 2 groups. Accordingly, DPP-4i did not alter the risk of acute coronary syndrome and acute myocardial infarction.

CONCLUSIONS

DPP-4i may reduce all-cause mortality in heart failure patients in subgroups of women and HFpEF and has a high coronary safety profile.

Nuclear Factor-κB is a Prime Candidate for the Diagnosis and Control of Inflammatory Cardiovascular Disease

Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is responsible for the regulation of genes involved in inflammation and immune responses. NF-κB may play an important role in cardiovascular diseases (CVDs), atherosclerosis and diabetes. Several therapeutic agents used for the treatment of CVDs and diabetes, such as pimobendan and sodium-glucose cotransporter 2 inhibitors, exert anti-inflammatory effects by inhibiting NF-κB activation; anti-inflammatory therapy may have beneficial effects in CVDs and diabetes. Several pharmacological agents and natural compounds may inhibit NF-κB, and these agents alone or in combination may be used to treat various inflammatory diseases. Immunoglobulin-free light chains could be surrogate biomarkers of NF-κB activation and may be useful for evaluating the efficacy of these agents. This review discusses recent advances in our understanding of how the NF-κB signalling pathway controls inflammation, metabolism and immunity, and how improved knowledge of these pathways may lead to better diagnostics and therapeutics for various human diseases.

Endothelial Autophagy Dysregulation in Diabetes

Diabetes mellitus is a major public health issue that affected 537 million people worldwide in 2021, a number that is only expected to increase in the upcoming decade. Diabetes is a systemic metabolic disease with devastating macro- and microvascular complications. Endothelial dysfunction is a key determinant in the pathogenesis of diabetes. Dysfunctional endothelium leads to vasoconstriction by decreased nitric oxide bioavailability and increased expression of vasoconstrictor factors, vascular inflammation through the production of pro-inflammatory cytokines, a loss of microvascular density leading to low organ perfusion, procoagulopathy, and/or arterial stiffening. Autophagy, a lysosomal recycling process, appears to play an important role in endothelial cells, ensuring endothelial homeostasis and functions. Previous reports have provided evidence of autophagic flux impairment in patients with type I or type II diabetes. In this review, we report evidence of endothelial autophagy dysfunction during diabetes. We discuss the mechanisms driving endothelial autophagic flux impairment and summarize therapeutic strategies targeting autophagy in diabetes.

Links between Metabolic Syndrome and Hypertension: The Relationship with the Current Antidiabetic Drugs

Hypertension poses a significant burden in the general population, being responsible for increasing cardiovascular morbidity and mortality, leading to adverse outcomes. Moreover, the association of hypertension with dyslipidaemia, obesity, and insulin resistance, also known as metabolic syndrome, further increases the overall cardiovascular risk of an individual. The complex pathophysiological overlap between the components of the metabolic syndrome may in part explain how novel antidiabetic drugs express pleiotropic effects. Taking into consideration that a significant proportion of patients do not achieve target blood pressure values or glucose levels, more efforts need to be undertaken to increase awareness among patients and physicians. Novel drugs, such as incretin-based therapies and renal glucose reuptake inhibitors, show promising results in decreasing cardiovascular events in patients with metabolic syndrome. The effects of sodium-glucose co-transporter-2 inhibitors are expressed at different levels, including renoprotection through glucosuria, natriuresis and decreased intraglomerular pressure, metabolic effects such as enhanced insulin sensitivity, cardiac protection through decreased myocardial oxidative stress and, to a lesser extent, decreased blood pressure values. These pleiotropic effects are also observed after treatment with glucagon-like peptide-1 receptor agonists, positively influencing the cardiovascular outcomes of patients with metabolic syndrome. The initial combination of the two classes may be the best choice in patients with type 2 diabetes mellitus and multiple cardiovascular risk factors because of their complementary mechanisms of action. In addition, the novel mineralocorticoid receptor antagonists show significant cardio-renal benefits, as well as anti-inflammatory and anti-fibrotic effects. Overall, the key to better control of hypertension in patients with metabolic syndrome is to consider targeting multiple pathogenic mechanisms, using a combination of the different therapeutic agents, as well as drastic lifestyle changes. This article will briefly summarize the association of hypertension with metabolic syndrome, as well as take into account the influence of antidiabetic drugs on blood pressure control.

Host-Cell Surface Binding Targets in SARS-CoV-2 for Drug Design

The ongoing pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a major public health threat to all countries worldwide. SARS-CoV-2 interactions with its receptor are the first step in the invasion of the host cell. The coronavirus spike protein (S) is crucial in binding to receptors on host cells. Additionally, targeting the SARS-CoV-2 viral receptors is considered a therapeutic option in this regard. In this review of literature, we summarized five potential host cell receptors, as host-cell surface bindings, including angiotensin-converting enzyme 2 (ACE2), neuropilin 1 (NRP-1), dipeptidyl peptidase 4 (DPP4), glucose regulated protein-78 (GRP78), and cluster of differentiation 147 (CD147) related to the SARS-CoV-2 infection. Among these targets, ACE2 was recognized as the main SARS-CoV-2 receptor, expressed at a low/moderate level in the human respiratory system, which is also involved in SARS-CoV-2 entrance, so the virus may utilize other secondary receptors. Besides ACE2, CD147 was discovered as a novel SARS-CoV-2 receptor, CD147 appears to be an alternate receptor for SARSCoV- 2 infection. NRP-1, as a single-transmembrane glycoprotein, has been recently found to operate as an entrance factor and enhance SARS Coronavirus 2 (SARS-CoV-2) infection under in-vitro. DPP4, which was discovered as the first gene clustered with ACE2, may serve as a potential SARS-CoV-2 spike protein binding target. GRP78 could be recognized as a secondary receptor for SARS-CoV-2 because it is widely expressed at substantially greater levels, rather than ACE2, in bronchial epithelial cells and the respiratory mucosa. This review highlights recent literature on this topic.

Diabetes medications and risk of HCC

Type 2 diabetes mellitus is a recognized risk factor for HCC in patients with liver disease, independent from the etiology of their liver disease. Hence, prevention and treatment of type 2 diabetes mellitus and its underlying cause, insulin resistance, should be considered a treatment target for patients with liver disease. The drug armamentarium for diabetes is wide and consists of agents with insulin-sensitizing activity, agents that stimulate insulin secretion, insulin itself, and agents that reduce gastrointestinal and urinary glucose absorption. From an endocrinology perspective, the main goal of treatment is the achievement of euglycemia; however, in patients at risk of, or with known underlying liver disease, the choice of diabetic medication as it relates to potential hepatic carcinogenesis remains complex and should be carefully considered. In the last decade, increasing evidence has suggested that metformin may reduce the risk of HCC, whereas evidence for other classes of diabetic medications, particularly some of the newer agents including the sodium glucose cotransporter-2 inhibitors and glucagon-like peptide-1 receptor agonists, is fewer and often inconsistent. In this review, we aim to summarize the current evidence on the potential effects of the most widely used diabetic agents on liver cancer tumorigenesis.

Enhanced Diabetic Wound Healing Using Electrospun Biocompatible PLGA-Based Saxagliptin Fibrous Membranes

Delayed diabetic wound healing is an adverse event that frequently leads to limb disability or loss. A novel and promising vehicle for the treatment of diabetic wounds is required for clinical purposes. The biocompatible and resorbable poly (lactic-co-glycolic acid) (PLGA)-based fibrous membranes prepared by electrospinning that provide a sustained discharge of saxagliptin for diabetic wound healing were fabricated. The concentration of released saxagliptin in Dulbecco’s phosphate-buffered saline was analyzed for 30 days using high-performance liquid chromatography. The effectiveness of the eluted saxagliptin was identified using an endothelial progenitor cell migration assay in vitro and a diabetic wound healing in vivo. Greater hydrophilicity and water storage were shown in the saxagliptin-incorporated PLGA membranes than in the pristine PLGA membranes (both p < 0.001). For diabetic wound healing, the saxagliptin membranes accelerated the wound closure rate, the dermal thickness, and the heme oxygenase-1 level over the follicle areas compared to those in the pristine PLGA group at two weeks post-treatment. The saxagliptin group also had remarkably higher expressions of insulin-like growth factor I expression and transforming growth factor-β1 than the control group (p = 0.009 and p < 0.001, respectively) in diabetic wounds after treatment. The electrospun PLGA-based saxagliptin membranes exhibited excellent biomechanical and biological features that enhanced diabetic wound closure and increased the antioxidant activity, cellular granulation, and functionality.

Genetic disruption of the Gipr in Apoe-/- mice promotes atherosclerosis

OBJECTIVE

The gut hormone glucose-dependent insulinotropic polypeptide (GIP) stimulates beta cell function and improves glycemia through its incretin actions. GIP also regulates endothelial function and suppresses adipose tissue inflammation through control of macrophage activity. Activation of the GIP receptor (GIPR) attenuates experimental atherosclerosis and inflammation in mice, however whether loss of GIPR signaling impacts the development of atherosclerosis is uncertain.

METHODS

Atherosclerosis and related metabolic phenotypes were studied in Apoe^-/-:Gipr^-/- mice and in Gipr^+/+ and Gipr^-/- mice treated with an adeno-associated virus expressing PCSK9 (AAV-PCSK9). Bone marrow transplantation (BMT) studies were carried out using donor marrow from Apoe^-/-:Gipr^-/-and Apoe^-/-:Gipr^+/+mice transplanted into Apoe^-/-:Gipr^-/- recipient mice. Experimental endpoints included the extent of aortic atherosclerosis and inflammation, body weight, glucose tolerance, and circulating lipid levels, the proportions and subsets of circulating leukocytes, and tissue gene expression profiles informing lipid and glucose metabolism, and inflammation.

RESULTS

Body weight was lower, circulating myeloid cells were reduced, and glucose tolerance was not different, however, aortic atherosclerosis was increased in Apoe^-/-:Gipr^-/- mice and trended higher in Gipr^-/- mice with atherosclerosis induced by AAV-PCSK9. Levels of mRNA transcripts for genes contributing to inflammation were increased in the aortae of Apoe^-/-:Gipr^-/- mice and expression of a subset of inflammation-related hepatic genes were increased in Gipr^-/- mice treated with AAV-PCSK9. BMT experiments did not reveal marked atherosclerosis, failing to implicate bone marrow derived GIPR + cells in the control of atherosclerosis or aortic inflammation.

CONCLUSIONS

Loss of the Gipr in mice results in increased aortic atherosclerosis and enhanced inflammation in aorta and liver, despite reduced weight gain and preserved glucose homeostasis. These findings extend concepts of GIPR in the suppression of inflammation-related pathophysiology beyond its classical incretin role in the control of metabolism.

DPP-4 inhibitors and GLP-1RAs: cardiovascular safety and benefits

Glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors are commonly used treatments for patients with type 2 diabetes mellitus (T2DM). Both anti-diabetic treatments function by playing key modulatory roles in the incretin system. Though these drugs have been deemed effective in treating T2DM, the Food and Drug Administration (FDA) and some members of the scientific community have questioned the safety of these therapeutics relative to important cardiovascular endpoints. As a result, since 2008, the FDA has required all new drugs for glycemic control in T2DM patients to demonstrate cardiovascular safety. The present review article strives to assess the safety and benefits of incretin-based therapy, a new class of antidiabetic drug, on the health of patient cardiovascular systems. In the process, this review will also provide a physiological overview of the incretin system and how key components function in T2DM.

Modifying a Hydroxyl Patch in Glucagon-like Peptide 1 Produces Biased Agonists with Unique Signaling Profiles

Glucagon-like peptide-1 (GLP-1) lowers blood glucose by inducing insulin but also has other poorly understood properties. Here, we show that hydroxy amino acids (Thr11, Ser14, Ser17, Ser18) in GLP-1(7-36) act in concert to direct cell signaling. Mutating any single residue to alanine removes one hydroxyl group, thereby reducing receptor affinity and cAMP 10-fold, with Ala11 or Ala14 also reducing β-arrestin-2 10-fold, while Ala17 or Ala18 also increases ERK1/2 phosphorylation 5-fold. Multiple alanine mutations more profoundly bias signaling, differentially silencing or restoring one or more signaling properties. Mutating three serines silences only ERK1/2, the first example of such bias. Mutating all four residues silences β-arrestin-2, ERK1/2, and Ca²⁺ maintains the ligand and receptor at the membrane but still potently stimulates cAMP and insulin secretion in cells and mice. These novel findings indicate that hydrogen bonding cooperatively controls cell signaling and highlight an important regulatory hydroxyl patch in hormones that activate class B G protein-coupled receptors.

Cardiovascular effects of incretins - focus on GLP-1 receptor agonists

GLP-1 receptor agonists (GLP-1 RAs) have been used to treat patients with type 2 diabetes since 2005 and have become popular because of the efficacy and durability in relation to glycaemic control in combination with weight loss in most patients. Today in 2022, seven GLP-1 RAs, including oral semaglutide are available for treatment of type 2 diabetes. Since the efficacy in relation to reduction of HbA1c and body weight as well as tolerability and dosing frequency vary between agents, the GLP-1 RAs cannot be considered equal. The short acting lixisenatide showed no cardiovascular benefits, while once daily liraglutide and the weekly agonists, subcutaneous semaglutide, dulaglutide, and efpeglenatide, all lowered the incidence of cardiovascular events. Liraglutide, oral semaglutide and exenatide once weekly also reduced mortality. GLP-1 RAs reduce the progression of diabetic kidney disease. In the 2019 consensus report from EASD/ADA, GLP-1 RAs with demonstrated cardio-renal benefits (liraglutide, semaglutide and dulaglutide) are recommended after metformin to patients with established cardiovascular diseases or multiple cardiovascular risk factors. European Society of Cardiology (ESC) suggests starting with a SGLT-2 inhibitor or a GLP-1 RA in drug naïve patients with type 2 diabetes and atherosclerotic CVD or high CV Risk. However, the results from cardiovascular outcome trials (CVOT) are very heterogeneous suggesting that some GLP-1RA are more suitable to prevent CVD than others. The CVOTs provide a basis upon which individual treatment decisions for patients with T2D and CVD can be made.

Saxagliptin Cardiotoxicity in Chronic Heart Failure: The Role of DPP4 in the Regulation of Neuropeptide Tone

Dipeptidyl-peptidase-4 (DPP4) inhibitors are novel medicines for diabetes. The SAVOR-TIMI-53 clinical trial revealed increased heart-failure-associated hospitalization in saxagliptin-treated patients. Although this side effect could limit therapeutic use, the mechanism of this potential cardiotoxicity is unclear. We aimed to establish a cellular platform to investigate DPP4 inhibition and the role of its neuropeptide substrates substance P (SP) and neuropeptide Y (NPY), and to determine the expression of DDP4 and its neuropeptide substrates in the human heart. Western blot, radio-, enzyme-linked immuno-, and RNA scope assays were performed to investigate the expression of DPP4 and its substrates in human hearts. Calcein-based viability measurements and scratch assays were used to test the potential toxicity of DPP4 inhibitors. Cardiac expression of DPP4 and NPY decreased in heart failure patients. In human hearts, DPP4 mRNA is detectable mainly in cardiomyocytes and endothelium. Treatment with DPP4 inhibitors alone/in combination with neuropeptides did not affect viability but in scratch assays neuropeptides decreased, while saxagliptin co-administration increased fibroblast migration in isolated neonatal rat cardiomyocyte-fibroblast co-culture. Decreased DPP4 activity takes part in the pathophysiology of end-stage heart failure. DPP4 compensates against the elevated sympathetic activity and altered neuropeptide tone. Its inhibition decreases this adaptive mechanism, thereby exacerbating myocardial damage.

Discrepancy between the Actions of Glucagon-like Peptide-1 Receptor Ligands in the Protection of the Heart against Ischemia Reperfusion Injury

Tirzepatide is a dual glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist and a promising therapy for type 2 diabetes mellitus (T2DM). GLP-1 is an incretin hormone with therapeutic potential beyond type 2 diabetes mellitus. However, GLP-1 is rapidly degraded by dipeptdyl peptidase-IV (DPP-IV) to GLP-1 (9-36). Exendin-4 (Ex-4) is a DPP-IV-resistant GLP-1 receptor agonist which, when truncated to Ex-4 (9-39), acts as a GLP-1 receptor antagonist. In the present study, hearts isolated from Wistar rats (n = 8 per group) were perfused with a modified Langendorff preparation. Left ventricular (LV) contractility and cardiovascular hemodynamics were evaluated by a data acquisition program and infarct size was evaluated by 2,3,5-Triphenyl-2H-tetrazolium chloride (TTC) staining and cardiac enzyme levels. Hearts were subjected to 30 min regional ischemia, produced by ligation of the left anterior descending (LAD) coronary artery followed by 30 min reperfusion. Hearts were treated during reperfusion with either the non-lipidated precursor of tirzepatide (NLT), GLP-1, GLP-1 (9-36), or Ex-4 in the presence or absence of Ex-4 (9-39). Infusion of GLP-1 (9-36) or Ex-4 protected the heart against I/R injury (p > 0.01) by normalizing cardiac hemodynamic and enzyme levels. Neither GLP-1, NLT, nor Ex-4 (9-39) showed any protection. Interestingly, Ex-4 (9-39) blocked Ex-4-mediated protection but not that of GLP-1 (9-36). These data suggest that Ex-4-mediated protection is GLP-1-receptor-dependent but GLP-1 (9-36)-mediated protection is not.

Treatment of diabetes mellitus has borne much fruit in the prevention of cardiovascular disease

Cardiovascular (CV) disease is the most alarming complication of diabetes mellitus (DM), and a strategy aiming at cardiovascular event prevention in diabetes mellitus has long been debated. Large landmark clinical trials have shown cardiovascular benefits of intensive glycemic control as a ‘legacy effect’ in newly diagnosed type 2 diabetes mellitus. In contrast, we have learned that excessive intervention aimed at strong glycemic control could cause unexpected cardiovascular death in patients who are resistant to treatments against hyperglycemia. It has also been shown that the comprehensive multifactorial intervention for cardiovascular risk factors that was advocated in the current guideline provided substantial cardiovascular event reduction. The impact of classical antidiabetic agents launched before 1990s on cardiovascular events is controversial. Although there are many clinical or observational studies assessing the impact of those agents on cardiovascular events, the conclusions are inconsistent owing to variable patient backgrounds and concomitant antidiabetic agents among the studies. Moreover, most of them were not large‐scale, randomized, cardiovascular outcome trials. In contrast, GLP‐1RA (glucagon‐like peptide‐1 receptor agonist) and SGLT2 (sodium‐glucose cotransporter 2) inhibitors have demonstrated undeniable cardiovascular benefits in large‐scale, randomized, controlled trials. Whereas GLP‐1RAs decrease atherosclerotic disease, especially stroke, SGLT2 inhibitors mainly prevent heart failure. SGLT2 inhibitors are superior to GLP‐1RAs with respect to hard renal outcomes. Therefore, it can be said that drugs such as GLP‐1RAs and SGLT2 inhibitors that prevent cardiovascular events, in addition to their glucose‐lowering effect, are incredible novel tools that we have gained for use in diabetic treatment.

Glucagon-like peptide-1 (GLP-1) receptor agonists and cardiovascular events in patients with type 2 diabetes mellitus: a meta-analysis of double-blind, randomized, placebo-controlled clinical trials

BACKGROUND

The cardiovascular effects of glucagon-like peptide-1 (GLP-1) receptor agonists are still controversial in the treatment of type 2 diabetes mellitus (T2DM) patients. The purpose of this study was to evaluate the risk of cardiovascular events of GLP-1 (albiglutide, exenatide, liraglutide, semaglutide, lixisenatide and dulaglutide) receptor agonists in T2DM patients.

METHODS

PubMed and Embase were searched to find relevant randomized controlled trials (RCTs) from inception to June 2019 that evaluated the effect of GLP-1 receptor agonists on cardiovascular events in patients with T2DM. The T2DM patients of all the eligible trials received either GLP-1 therapy or placebo, and the cardiovascular outcomes included death from cardiovascular causes, fatal or non-fatal myocardial infarction and fatal or non-fatal stroke.

RESULTS

We included 6 multinational double-blind randomized placebo-control trials that included a total of 52821 T2DM patients. The results indicated that GLP-1 receptor agonists reduced the risk of death from cardiovascular causes (RR: 0.90; 95% CI: 0.83-0.97; P = 0.004) and fatal or non-fatal stroke (RR: 0.85; 95% CI: 0.77-0.94; P = 0.001) compared with the placebo controls. But GLP-1 receptor agonists did not significantly alter the fatal or non-fatal myocardial infarction compared with the placebo (RR: 0.91; 95% CI: 0.82 - 1.01; P = 0.06).

CONCLUSION

We concluded that GLP-1 receptor agonist therapy could reduce the risk of death from cardiovascular causes and fatal or non-fatal stroke compared with the placebo in the treatment of T2DM patients in trials with cardiovascular outcomes.

In Silico Development of Combinatorial Therapeutic Approaches Targeting Key Signaling Pathways in Metabolic Syndrome

PURPOSE

Dysregulations of key signaling pathways in metabolic syndrome are multifactorial, eventually leading to cardiovascular events. Hyperglycemia in conjunction with dyslipidemia induces insulin resistance and provokes release of proinflammatory cytokines resulting in chronic inflammation, accelerated lipid peroxidation with further development of atherosclerotic alterations and diabetes. We have proposed a novel combinatorial approach using FDA approved compounds targeting IL-17a and DPP4 to ameliorate a significant portion of the clustered clinical risks in patients with metabolic syndrome. In our current research we have modeled the outcomes of metabolic syndrome treatment using two distinct drug classes.

METHODS

Targets were chosen based on the clustered clinical risks in metabolic syndrome: dyslipidemia, insulin resistance, impaired glucose control, and chronic inflammation. Drug development platform, BIOiSIM™, was used to narrow down two different drug classes with distinct modes of action and modalities. Pharmacokinetic and pharmacodynamic profiles of the most promising drugs were modeling showing predicted outcomes of combinatorial therapeutic interventions.

RESULTS

Preliminary studies demonstrated that the most promising drugs belong to DPP-4 inhibitors and IL-17A inhibitors. Evogliptin was chosen to be a candidate for regulating glucose control with long term collateral benefit of weight loss and improved lipid profiles. Secukinumab, an IL-17A sequestering agent used in treating psoriasis, was selected as a repurposed candidate to address the sequential inflammatory disorders that follow the first metabolic insult.

CONCLUSIONS

Our analysis suggests this novel combinatorial therapeutic approach inducing DPP4 and Il-17a suppression has a high likelihood of ameliorating a significant portion of the clustered clinical risk in metabolic syndrome.

Novel Biomarkers of Inflammation for the Management of Diabetes: Immunoglobulin-Free Light Chains

Virus infection, inflammation and genetic factors are important factors in the pathogenesis of diabetes mellitus. The nuclear factor-kappa B (NF-κB) is a family of transcription factors that bind the enhancer of the κ light chain gene of B cell immunoglobulin. NF-κB plays an essential role in the activation and development of B cells, and the activation of NF-κB is critical in the inflammation and development of diabetes mellitus. Recently, immunoglobulin-free light chain (FLC) λ was found to be increased in the sera of patients with diabetes mellitus, and the FLC λ and κ/λ ratios are more specific and sensitive markers for the diagnosis of diabetes relative to glycated hemoglobin A1c. Thus, FLCs may be promising biomarkers of inflammation that could relate to the activation of NF-κB. We suggest that NF-κB could be a target for an anti-inflammatory strategy in preventing and treating diabetes when FLCs are modified. FLCs could be a surrogate endpoint in the management of diabetes. In this review, the role of inflammation in the pathogenesis of diabetes, as well as the novel inflammatory biomarkers of FLCs for the management of diabetes, are discussed.

GLP-1 receptor agonists and cardiovascular outcomes in patients with type 2 diabetes: Clinical evidence and best practice

ABSTRACT

Cardiovascular disease (CVD) is a major cause of death and disability among people with type 2 diabetes (T2D), presenting a significant impact on longevity, patient quality of life, and health care costs. In the United States, attainment of recommended glycemic targets is low and T2D-related cardiovascular complications remain a significant burden. Many glucose-lowering treatment options are available, but glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter-2 (SGLT-2) inhibitors are recommended in recent guidelines as the preferred add-on therapy to metformin to improve glycemic control. This is particularly the case for patients with T2D and established atherosclerotic CVD, at high risk of atherosclerotic CVD, and/or with chronic kidney disease. Recommendations were based on GLP-1RA and SGLT-2 inhibitor cardiovascular outcomes trials (CVOTs), which consistently showed that these agents pose no additional cardiovascular risk compared with placebo. Three GLP-1RAs (liraglutide, dulaglutide, and subcutaneous semaglutide) demonstrated significantly lower major adverse cardiovascular events versus placebo and are now approved for this indication. However, to realize improvement in outcomes in the clinical setting, organized, systematic, and coordinated approaches to patient management are also needed. For example, nurse-led diabetes self-management education and support programs have been shown to be effective. This article explores T2D management with emphasis on cardiovascular risk and CVOTs performed to date and reviews the clinical experience with GLP-1RAs for managing hyperglycemia and their impact on cardiovascular risk. In addition, practical guidance is given for key health care providers involved in the care of patients with T2D with cardiovascular risk outside of diabetes clinics/endocrinology centers.

Dipeptidyl peptidase-4 (DPP-IV) inhibitor was associated with mortality reduction in COVID-19 - A systematic review and meta-analysis

INTRODUCTION

This systematic review and meta-analysis aimed to synthesize the latest evidence on the effect of dipeptidyl peptidase-4 (DPP-IV) inhibitor in patients with COVID-19.

METHODS

We performed a systematic literature search from the PubMed, Scopus, Embase, and Clinicaltrials.gov up until 15 July 2021. Studies that met the following criteria were included: prospective or retrospective observational studies or case series or randomized controlled trials (RCTs) reporting DPP-IV inhibitor use in patients with COVID-19 and mortality. The intervention group was patients receiving DPP-IV inhibitor. The control group was patients that did not receive DPP-IV inhibitor. The outcome was mortality reported as odds ratio (OR).

RESULTS

There were 11 studies consisting of 5950 patients in this meta-analysis. DPP-IV inhibitor use was associated with reduced mortality (OR 0.75 [0.56, 0.99], p = 0.043, I²: 42.9, p = 0.064) compared to those that did not receive DPP-IV inhibitor. Sensitivity analysis using the fixed-effect model (OR 0.75 [0.63, 0.88], p < 0.001, I²: 42.9, p = 0.064) also showed mortality benefit. The association between DPP-IV inhibitor and mortality was not significantly affected by age (p = 0.540), sex (p = 0.054), hypertension (p = 0.320), location (continent; p = 0.532), and retrospective/prospective nature of the study (p = 0.840). However, the association was affected by metformin (OR 1.03 [95% CI 1.01, 1.06], p = 0.010) and ACEI/ARB use (OR 1.06 [95% CI 1.02, 1.10], p = 0.004).

CONCLUSION

This meta-analysis showed that DPP-IV inhibitor was associated with reduced mortality in patients with COVID-19.

Inflammation as A Precursor of Atherothrombosis, Diabetes and Early Vascular Aging

Vascular disease was for a long time considered a disease of the old age, but it is becoming increasingly clear that a cumulus of factors can cause early vascular aging (EVA). Inflammation plays a key role in vascular stiffening and also in other pathologies that induce vascular damage. There is a known and confirmed connection between inflammation and atherosclerosis. However, it has taken a long time to prove the beneficial effects of anti-inflammatory drugs on cardiovascular events. Diabetes can be both a product of inflammation and a cofactor implicated in the progression of vascular disease. When diabetes and inflammation are accompanied by obesity, this ominous trifecta leads to an increased incidence of atherothrombotic events. Research into earlier stages of vascular disease, and documentation of vulnerability to premature vascular disease, might be the key to success in preventing clinical events. Modulation of inflammation, combined with strict control of classical cardiovascular risk factors, seems to be the winning recipe. Identification of population subsets with a successful vascular aging (supernormal vascular aging-SUPERNOVA) pattern could also bring forth novel therapeutic interventions.

The Role of GLP-1 Signaling in Hypoglycemia due to Hyperinsulinism

Incretin hormones play an important role in the regulation of glucose homeostasis through their actions on the beta cells and other tissues. Glucagon-like peptide-1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) are the two main incretins and are secreted by enteroendocrine L- and K-cells, respectively. New evidence suggests that incretin hormones, particularly GLP-1, play a role in the pathophysiology of hyperinsulinemic hypoglycemia. In individuals with acquired hyperinsulinemic hypoglycemia after gastrointestinal surgery, including Nissen fundoplication and gastric bypass surgery, the incretin response to a meal is markedly increased and antagonism of the GLP-1 receptor prevents the hyperinsulinemic response. In individuals with congenital hyperinsulinism due to inactivating mutations in the genes encoding the beta cell K_ATP channels, the GLP-1 receptor antagonist, exendin-(9-39), increases fasting plasma glucose and prevents protein-induced hypoglycemia. Studies in human and mouse islets lacking functional K_ATP channels have demonstrated that the effect on plasma glucose is at least in part mediated by inhibition of insulin secretion resulting from lower cytoplasmic cAMP levels. The understanding of the role of incretin hormones in the pathophysiology of hyperinsulinemic hypoglycemia is important for the exploration of the GLP-1 receptor as a therapeutic target for these conditions. In this article, we will review incretin physiology and evidence supporting a role of the incretin hormones in the pathophysiology of hyperinsulinemic hypoglycemia, as well as results from proof-of concept studies exploring a therapeutic approach targeting the GLP-1 receptor to treat hyperinsulinemic hypoglycemia.

Recent therapeutic targets in diabetic nephropathy

BACKGROUND

The prevalence of diabetes mellitus has been increased dramatically which in turn leads to complications including cardiovascular diseases, diabetic kidney disease, and substantially end-stage renal disease.

METHODS

We reviewed articles discussing the pathophysiology of diabetic nephropathy with new agents that may be useful in the management of the disease. We used PubMed, Scopus, Google Scholar and the Open-access searching engines.

RESULTS

The recent recommendations primarily depend on glycaemic and blood pressure control and the use of standard renin-angiotensin system blockade. Currently, the use of agents with nephroprotective effects beyond the hyperglycaemic lowering effect has been evidenced clinically.

CONCLUSIONS

In his review, the pathophysiology, clinical manifestations, and lines of treatment of diabetic nephropathy are discussed. In addition, a focus on the clinical role and nephroprotective effects of the emerging therapeutic class, dipeptidyl peptidase IV (DPP-4) inhibitors, is addressed in detail.

Cardiovascular protective effects of GLP-1:A focus on the MAPK signaling pathway

Cardiovascular and related metabolic diseases are significant global health challenges. Glucagon-like peptide 1 (GLP-1) is a brain-gut peptide secreted by ileal endocrine that is now an established drug target in type 2 diabetes (T2DM). GLP-1 targeting agents have been shown not only to treat T2DM, but also to exert cardiovascular protective effects through regulating multiple signaling pathways. The mitogen-activated protein kinase (MAPK) pathway, a common signal transduction pathway for transmitting extracellular signals to downstream effector molecules, is involved in regulating diverse cell physiological processes, including cell proliferation, differentiation, stress, inflammation, functional synchronization, transformation and apoptosis. The purpose of this review is to highlight the relationship between GLP-1 and cardiovascular disease (CVD), and discuss how GLP-1 exerts cardiovascular protective effects through MAPK signaling pathway. This review also discusses the future challenges in fully characterizing and evaluating the CVD protective effects of GLP-1 receptor agonists (GLP-1RA) at the cellular and molecular level. A better understanding of MAPK signaling pathway that are disregulated in CVD may aid in the design and development of promising GLP-1RA.

Oral semaglutide in the management of type 2 DM: Clinical status and comparative analysis

BACKGROUND

In the incretin system, Glucagon-like peptide-1 (GLP-1) is a hormone that inhibits the release of glucagon and regulates glucose-dependent insulin secretion. In type 2 diabetes, correcting the impaired incretin system using GLP-1 agonist is a well-defined therapeutic strategy.

OBJECTIVES

This review article aims to discuss the mechanism of action, key regulatory events, clinical trials for glycaemic control and comparative analysis of semaglutide with the second-line antidiabetic drugs.

DESCRIPTION

Semaglutide is a glucagon-like peptide 1 (GLP 1) receptor agonist with enhanced glycaemic control in diabetes patients. In 2019, USFDA approved the first oral GLP-1 receptor agonist, semaglutide to be administered as a once-daily tablet. Further, recent studies highlight the ability of semaglutide to improve the glycaemic control in obese patients with a reduction in body weight. Still, in clinical practice, in type 2 DM treatment paradigm the impact of oral semaglutide remains unidentified. This review article discusses the mechanism of action, pharmacodynamics, key regulatory events, and clinical trials regarding glycaemic control.

CONCLUSION

The review highlights the comparative analysis of semaglutide with the existing second-line drugs for the management of type 2 diabetes mellitus by stressing on its benefits and adverse events.

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.

Comparison of New Oral Hypoglycemic Agents on Risk of Urinary Tract and Genital Infections in Type 2 Diabetes: A Network Meta-analysis

INTRODUCTION

Dipeptidyl peptidase 4 (DPP4) inhibitors and sodium-glucose co-transporter 2 (SGLT2) inhibitors have often been used for patients with T2DM because of the reduced risk of hypoglycemia. However, DPP4 inhibitors and SGLT2 inhibitors may increase the risk of infectious diseases. This network meta-analysis (NMA) was performed to investigate the risk of urinary tract and genital infections associated with the use of two new glucose-lowering drug classes in patients with type 2 diabetes.

METHODS

PubMed, Web of Science, Embase, and the Cochrane Library were comprehensively searched for articles from the date of database inception until September 8, 2020. Placebo-controlled or head-to-head trials of the two new drug classes used for treatment of adults with type 2 diabetes were included. The primary outcome was the incidence of any confirmed urinary tract infection; genital infection was also used as an important outcome indicator.

RESULTS

Fifty-five studies were identified, covering 29,574 participants. Regarding urinary tract infections, SGLT2 inhibitors were not associated with increased risk, and among all drugs, sitagliptin, ipragliflozin, and linagliptin were the safest according to probability ranking. Regarding genital infections, saxagliptin was associated with significantly reduced risk in pairwise comparisons with placebo (RR 0.12, 95% CI 0.00-0.78), linagliptin (RR 0.09, 95% CI 0.00-0.78), canagliflozin (RR 0.04, 95% CI 0.00-0.31), dapagliflozin (RR 0.04, 95% CI 0.00-0.26), empagliflozin (RR 0.03, 95% CI 0.00-0.25), and ertugliflozin (RR 0.03, 95% CI 0.00-0.24). Among all drugs, saxagliptin, sitagliptin, and ipragliflozin were the safest according to probability ranking. Considering both urinary tract and genital infection risks, DPP4 inhibitors showed greater reductions than SGLT2 inhibitors and placebo. Saxagliptin was the safest drug according to probability ranking for both infection risks.

CONCLUSIONS

This NMA showed that, to reduce genital infection risk, current evidence favors DPP4 inhibitors over SGLT2 inhibitors. Most SGLT2 inhibitors may not be associated with the risk of urinary tract infections. Considering both infection risks, saxagliptin may be the safest drug. Finally, mechanistic studies are needed to better understand the physiological basis for these effects.

Sitagliptin: a potential drug for the treatment of COVID-19?

Recently, an outbreak of a fatal coronavirus, SARS-CoV-2, has emerged from China and is rapidly spreading worldwide. Possible interaction of SARS-CoV-2 with DPP4 peptidase may partly contribute to the viral pathogenesis. An integrative bioinformatics approach starting with mining the biomedical literature for high confidence DPP4-protein/gene associations followed by functional analysis using network analysis and pathway enrichment was adopted. The results indicate that the identified DPP4 networks are highly enriched in viral processes required for viral entry and infection, and as a result, we propose DPP4 as an important putative target for the treatment of COVID-19. Additionally, our protein-chemical interaction networks identified important interactions between DPP4 and sitagliptin. We conclude that sitagliptin may be beneficial for the treatment of COVID-19 disease, either as monotherapy or in combination with other therapies, especially for diabetic patients and patients with pre-existing cardiovascular conditions who are already at higher risk of COVID-19 mortality.

Platelet Effects of Anti-diabetic Therapies: New Perspectives in the Management of Patients with Diabetes and Cardiovascular Disease

In type 2 diabetes, anti-thrombotic management is challenging, and current anti-platelet agents have demonstrated reduced efficacy. Old and new anti-diabetic drugs exhibited—besides lowering blood glucose levels—direct and indirect effects on platelet function and on thrombotic milieu, eventually conditioning cardiovascular outcomes. The present review summarizes existing evidence on the effects of glucose-lowering agents on platelet properties, addressing pre-clinical and clinical research, as well as drug–drug interactions with anti-platelet agents. We aimed at expanding clinicians’ understanding by highlighting new opportunities for an optimal management of patients with diabetes and cardiovascular disease. We suggest how an improvement of the thrombotic risk in this large population of patients may be achieved by a careful and tailored combination of anti-diabetic and anti-platelet therapies.

Comparative Renal Effects of Dipeptidyl Peptidase-4 Inhibitors and Sodium-Glucose Cotransporter 2 Inhibitors on Individual Outcomes in Patients with Type 2 Diabetes: A Systematic Review and Network Meta-Analysis

BACKGROUND

To compare the renal effects of dipeptidyl peptidase-4 (DPP-4) inhibitors and sodium-glucose cotransporter 2 (SGLT2) inhibitors on individual outcomes in patients with type 2 diabetes.

METHODS

We searched electronic databases (MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials) from inception to June 2019 to identity eligible randomized controlled trials of DPP-4 inhibitors or SGLT2 inhibitors that reported at least one kidney outcome in patients with type 2 diabetes. Outcomes of interest were microalbuminuria, macroalbuminuria, worsening nephropathy, and end-stage kidney disease (ESKD). We performed an arm-based network meta-analysis using Bayesian methods and calculated absolute risks and rank probabilities of each treatment for the outcomes.

RESULTS

Seventeen studies with 87,263 patients were included. SGLT2 inhibitors significantly lowered the risks of individual kidney outcomes, including microalbuminuria (odds ratio [OR], 0.64; 95% credible interval [CrI], 0.41 to 0.93), macroalbuminuria (OR, 0.48; 95% CrI, 0.24 to 0.72), worsening nephropathy (OR, 0.65; 95% CrI, 0.44 to 0.91), and ESKD (OR, 0.65; 95% CrI, 0.46 to 0.98) as compared with placebo. However, DPP-4 inhibitors did not lower the risks. SGLT2 inhibitors were considerably associated with higher absolute risk reductions in all kidney outcomes than DPP-4 inhibitors, although the benefits were statistically insignificant. The rank probabilities showed that SGLT2 inhibitors were better treatments for lowering the risk of albuminuria and ESKD than placebo or DPP-4 inhibitors.

CONCLUSION

SGLT2 inhibitors were superior to DPP-4 inhibitors in reducing the risk of albuminuria and ESKD in patients with type 2 diabetes.

Concurrent diabetes and heart failure: interplay and novel therapeutic approaches

Diabetes mellitus increases the risk of developing heart failure, and the co-existence of both diseases worsens cardiovascular outcomes, hospitalization and the progression of heart failure. Despite current advancements on therapeutic strategies to manage hyperglycemia, the likelihood of developing diabetes-induced heart failure is still significant, especially with the accelerating global prevalence of diabetes and an ageing population. This raises the likelihood of other contributing mechanisms beyond hyperglycemia in predisposing diabetic patients to cardiovascular disease risk. There has been considerable interest in understanding the alterations in cardiac structure and function in the diabetic patients, collectively termed as "diabetic cardiomyopathy". However, the factors that contribute to the development of diabetic cardiomyopathies is not fully understood. This review summarizes the main characteristics of diabetic cardiomyopathies, and the basic mechanisms that contribute to its occurrence. This includes perturbations in insulin resistance, fuel preference, reactive oxygen species generation, inflammation, cell death pathways, neurohormonal mechanisms, advanced glycated end-products accumulation, lipotoxicity, glucotoxicity, and posttranslational modifications in the heart of the diabetic. This review also discusses the impact of antihyperglycemic therapies on the development of heart failure, as well as how current heart failure therapies influence glycemic control in diabetic patients. We also highlight the current knowledge gaps in understanding how diabetes induces heart failure.

Quality Matters? The Involvement of Mitochondrial Quality Control in Cardiovascular Disease

Cardiovascular diseases are one of the leading causes of death and global health problems worldwide. Multiple factors are known to affect the cardiovascular system from lifestyles, genes, underlying comorbidities, and age. Requiring high workload, metabolism of the heart is largely dependent on continuous power supply via mitochondria through effective oxidative respiration. Mitochondria not only serve as cellular power plants, but are also involved in many critical cellular processes, including the generation of intracellular reactive oxygen species (ROS) and regulating cellular survival. To cope with environmental stress, mitochondrial function has been suggested to be essential during bioenergetics adaptation resulting in cardiac pathological remodeling. Thus, mitochondrial dysfunction has been advocated in various aspects of cardiovascular pathology including the response to ischemia/reperfusion (I/R) injury, hypertension (HTN), and cardiovascular complications related to type 2 diabetes mellitus (DM). Therefore, mitochondrial homeostasis through mitochondrial dynamics and quality control is pivotal in the maintenance of cardiac health. Impairment of the segregation of damaged components and degradation of unhealthy mitochondria through autophagic mechanisms may play a crucial role in the pathogenesis of various cardiac disorders. This article provides in-depth understanding of the current literature regarding mitochondrial remodeling and dynamics in cardiovascular diseases.

Interplay Between Systemic Metabolic Cues and Autonomic Output: Connecting Cardiometabolic Function and Parasympathetic Circuits

There is consensus that the heart is innervated by both the parasympathetic and sympathetic nervous system. However, the role of the parasympathetic nervous system in controlling cardiac function has received significantly less attention than the sympathetic nervous system. New neuromodulatory strategies have renewed interest in the potential of parasympathetic (or vagal) motor output to treat cardiovascular disease and poor cardiac function. This renewed interest emphasizes a critical need to better understand how vagal motor output is generated and regulated. With clear clinical links between cardiovascular and metabolic diseases, addressing this gap in knowledge is undeniably critical to our understanding of the interaction between metabolic cues and vagal motor output, notwithstanding the classical role of the parasympathetic nervous system in regulating gastrointestinal function and energy homeostasis. For this reason, this review focuses on the central, vagal circuits involved in sensing metabolic state(s) and enacting vagal motor output to influence cardiac function. It will review our current understanding of brainstem vagal circuits and their unique position to integrate metabolic signaling into cardiac activity. This will include an overview of not only how metabolic cues alter vagal brainstem circuits, but also how vagal motor output might influence overall systemic concentrations of metabolic cues known to act on the cardiac tissue. Overall, this review proposes that the vagal brainstem circuits provide an integrative network capable of regulating and responding to metabolic cues to control cardiac function.

Do GLP-1 Receptor Agonists Increase the Risk of Breast Cancer? A Systematic Review and Meta-analysis

CONTEXT

Risk of cancer is a major concern in the development of drugs for the treatment of obesity and diabetes. In randomized controlled trials (RCTs) of the Liraglutide Clinical Development Program, subjects treated with a glucagon-like peptide-1 receptor agonist (GLP-1RA) had a higher absolute number of breast cancer events.

OBJECTIVE

To assess whether patients treated with GLP-1RAs had a higher risk of breast neoplasms.

DATA SOURCES

We searched MEDLINE, Embase, Web of Science, and CENTRAL from July 31, 2019 to February 8, 2020.

STUDY SELECTION

Reviewers assessed abstracts and full-text articles for RCTs of GLP-1RAs in adults with excessive weight and/or diabetes and a minimum follow-up of 24 weeks.

DATA EXTRACTION

Researchers extracted study-level data and assessed within-study risk of bias with the RoB 2.0 tool and quality of evidence with Grading of Recommendations Assessment, Development and Evaluation (GRADE).

DATA SYNTHESIS

We included 52 trials, of which 50 reported breast cancer events and 11 reported benign breast neoplasms. Overall methodological quality was high. Among 48 267 subjects treated with GLP-1RAs, 130 developed breast cancer compared with 107 of 40 755 controls (relative risk [RR], 0.98; 95% confidence interval [CI], 0.76-1.26). Subset analyses according to follow-up, participant/investigator blinding, and type of GLP-1RA did not reveal any differences. The risk of benign breast neoplasms also did not differ between groups (RR, 0.99; 95% CI, 0.48-2.01). Trial sequential analysis provided evidence that the sample size was sufficient to avoid missing alternative results.

CONCLUSIONS

Treatment with GLP-1RAs for obesity and diabetes does not increase the risk of breast neoplasms.

Effects of the Antidiabetic Drugs Evogliptin and Sitagliptin on the Immune Function of CD26/DPP4 in Th1 Cells

This study aimed to investigate whether the antidiabetic drugs dipeptidyl peptidase 4 (DPP4) inhibitors such as evogliptin and sitagliptin affect the membrane DPP4 (mDPP4) enzymatic activity and immune function of T helper1 (Th1) cells in terms of cytokine expression and cell profiles. The mDPP4 enzymatic activity, cytokine expression, and cell profiles, including cell counts, cell viability, DNA synthesis, and apoptosis, were measured in pokeweed mitogen (PWM)-activated CD4⁺CD26⁺ H9 Th1 cells with or without the DPP4 inhibitors, evogliptin and sitagliptin. PWM treatment alone strongly stimulated the expression of mDPP4 and cytokines such as interleukin (IL)-2, IL-10, tumor necrosis factor-alpha, interferon-gamma, IL-13, and granulocyte-macrophage colony stimulating factor in the CD4⁺CD26⁺ H9 Th1 cells. Evogliptin or sitagliptin treatment potently inhibited mDPP4 activity in a dose-dependent manner but did not affect either the cytokine profile or cell viability in PWM-activated CD4⁺CD26⁺ H9 Th1 cells. These results suggest that, following immune stimulation, Th1 cell signaling pathways for cytokine expression function normally after treatment with evogliptin or sitagliptin, which efficiently inhibit mDPP4 enzymatic activity in Th1 cells.