Pleiotropic effects of insulin and GLP-1 receptor agonists: Potential benefits of the association

GLP-1R agonist liraglutide attenuates pain hypersensitivity by stimulating IL-10 release in a nitroglycerin-induced chronic migraine mouse model

Glucagon-like peptide-1 receptor (GLP-1R) has been indicated to involve in chronic pain, however, the mechanism by which GLP-1R alleviates the central sensitization of chronic migraine (CM) remains unclear. Treatment with GLP-1R agonist liraglutide attenuated trigeminal allodynia and suppressed the protein levels of CM-associated molecules in the trigeminal nucleus caudalis (TNC). Further analysis showed that injection of liraglutide stimulated the release of IL-10 in the TNC. Treatment with IL-10 also alleviated pain hyperalgesia. Our findings illustrated that liraglutide might alleviate the central sensitization of CM by stimulating the release of IL-10, which reveals a novel mechanism of CM.

Therapeutic Mechanisms and Clinical Effects of Glucagon-like Peptide 1 Receptor Agonists in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) can lead to liver fibrosis and cirrhosis. Recently, glucagon-like peptide 1 receptor agonists (GLP-1RAs), a class of drugs used to treat type 2 diabetes and obesity, have shown therapeutic effects against NAFLD. In addition to reducing blood glucose levels and body weight, GLP-1RAs are effective in improving the clinical, biochemical, and histological markers of hepatic steatosis, inflammation, and fibrosis in patients with NAFLD. Additionally, GLP-1RAs have a good safety profile with minor side effects, such as nausea and vomiting. Overall, GLP-1RAs show promise as a potential treatment for NAFLD, and further studies are required to determine their long-term safety and efficacy.

Current and emerging drugs for the treatment of atherosclerosis: the evidence to date

INTRODUCTION

Atherosclerosis can be considered a chronic inflammatory process that stands out as a dominant cause of cardiovascular disease (CVD). Since blood lipids are the leading risk factor for atherosclerosis development, lowering low-density lipoprotein cholesterol (LDL-C) and other apolipoprotein B-containing lipoproteins reduces the risk of future cardiovascular events. However, there has been significant progress in developing lipid-lowering drugs for aggressive management of dyslipidemia, the rates of CVD events remain unacceptably high, so there is great need to identify novel therapeutic pathways targeting the atherosclerosis process.

AREAS COVERED

We discussed the current guidelines on CVD prevention, the role of novel lipid-lowering drugs, as well as emerging drugs for atherosclerosis, emphasizing the current data on compounds targeting inflammatory and oxidant pathways.

EXPERT OPINION

Although novel lipid-lowering drugs all showed their therapeutic efficacy in LDL-C lowering, data regarding their impact on cardiovascular outcomes is still inconclusive. On the other hand, some of the agents targeting inflammatory pathways, especially colchicine, showed promising results in terms of reducing CVD events. In contrast, those pointed at oxidant pathways failed to do so. Finally, exploring ways of targeting new therapeutic venues, such as adaptive immunity and clonal hematopoiesis, is a goal in the future.

Real-World Evaluation of Glycemic Outcomes and Extra-Glycemic Parameters in Diabetic Patients Treated with the Combined Formulation Degludec-Liraglutide (Ideglira)

INTRODUCTION

Combination therapy with both basal insulin (BI) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) is an effective treatment in patients with uncontrolled type 2 diabetes mellitus (T2DM). The recent development and release of a fixed-ratio combination of slow-release insulin degludec and the GLP-1RA liraglutide (IDegLira) represents an improvement to this therapy. We have conducted a real-world evidence study in Italian patients with T2DM to evaluate whether the encouraging clinical trial results obtained with IDegLira, which became available in Italy in January 2018, can be confirmed in Italian clinical practice.

METHODS

This was a multicenter, retrospective, observational study in patients with T2DM treated with IDegLira from January to December 2018. Prior to the initiation of IDegLira therapy, patients were treated with BI with or without one or more concomitant oral antidiabetic drugs (BOT group) or according to the basal bolus protocol (BI and rapid-acting insulin treatment; BB group).

RESULTS

A total of 244 patients were included in the present study, of whom 186 were in the BOT group and 58 in the BB group. Following the switch to IDegLira therapy, glycemic control improved in both groups, with significant reductions in glycated hemoglobin after 6 and 12 months of treatment in the BOT group and after 6 months of treatment in the BB group. No gain in body weight and body mass index and reductions in fasting plasma glucose and number of concomitant diabetic medications (in BOT patients) were observed. All results obtained during the study were achieved at a moderate dose of IDegLira.

CONCLUSION

The findings from this study show that in a real-world setting, the switch to IDegLira treatment is a valid option for patients who are failing to achieve glycemic control targets and/or struggling with the side effects, such as weight gain and hypoglycemia, of other insulin therapies.

Rationale for Timely Insulin Therapy in Type 2 Diabetes Within the Framework of Individualised Treatment: 2020 Update

Type 2 diabetes is characterised by chronic hyperglycaemia and variable degrees of insulin deficiency and resistance. Hyperglycaemia and elevated fatty acids exert harmful effects on β-cell function, regeneration and apoptosis (gluco-lipotoxicity). Furthermore, chronic hyperglycaemia triggers a vicious cycle of insulin resistance, low-grade inflammation and a cascade of pro-atherogenic processes. Thus, timely near to normal glucose control is of utmost importance in the management of type 2 diabetes and prevention of micro- and macroangiopathy. The majority of patients are multimorbid and obese, with critical comorbidities such as cardiovascular disease, heart failure and chronic kidney disease. Recently published guidelines therefore recommend patient-centred risk/benefit-balanced use of oral glucose-lowering drugs or a glucagon-like peptide 1 (GLP-1) receptor agonist, or switching to insulin with glycated haemoglobin (HbA1c) out of target. This article covers the indications of early insulin treatment to prevent diabetes-related complications, particularly in subgroups with severe insulin deficit, and to achieve recovery of residual β-cell function. Furthermore, the individualised, risk/benefit-balanced, timely initiation of insulin as second and third option is analysed. Timely insulin initiation may prevent diabetes progression, reduce diabetes-related complications and has less serious adverse effects. Basal insulin is the preferred option in most clinical situations with consequences of undertreatment of chronic hyperglycaemia.

Fixed versus flexible combination of GLP-1 receptor agonists with basal insulin in type 2 diabetes: A retrospective multicentre comparative effectiveness study

BACKGROUND AND AIMS

The combination of basal insulin (BI) and GLP-1 receptor agonists (GLP-1RAs) is a rational and effective therapy for patients with uncontrolled type 2 diabetes (T2D). We compared the effectiveness of fixed and flexible BI/GLP-1RA combinations using routinely accumulated clinical data.

METHODS

This was a retrospective, multicentre, real-world study concerning T2D patients initiating a fixed or flexible BI/GLP-1RA combination (NCT03959865). The primary endpoint was change in HbA1c. Secondary endpoints were changes in body weight, fasting plasma glucose (FPG) and systolic blood pressure (SBP). Confounding was addressed by propensity score matching (PSM) or multivariable adjustment (MVA).

RESULTS

A total of 609 patients were included in the study, 131 in the fixed group and 478 in the flexible group. The two groups differed in terms of diabetes duration, body weight and concomitant medications. After 5.7 months, observed HbA1c reductions were 0.6% and 0.8%, and body weight reductions were 2.8 kg and 1.2 kg in the flexible and fixed groups, respectively. Following PSM, HbA1c declined similarly in the two groups, whereas reduction in body weight was significantly in favour of the flexible combination. Findings were robust in sensitivity analyses, with the exception that, with MVA, a significantly higher reduction in HbA1c was detected in the fixed group. Final doses of BI were higher in the fixed group, whereas those of GLP-1RA were higher in the flexible group.

CONCLUSIONS

In routine specialist care, initiation of the fixed or flexible BI/GLP-1RA combination allowed similar improvement in glycaemic control, but greater weight loss was observed with the flexible combination. This difference reflected dosages of BI and GLP-1RAs.

Consensus Recommendations on GLP-1 RA Use in the Management of Type 2 Diabetes Mellitus: South Asian Task Force

The advent of incretin mimetics such as glucagon-like peptide-1 receptor agonists (GLP-1 RAs) has enriched the armamentarium for diabetes management owing to their glycaemic as well as extra-glycaemic benefits. The approval status and availability of this class of drugs vary widely across the globe. Being a relatively newer class of drug with numerous benefits, several national and international guidelines are working towards addressing clinical questions pertaining to the optimal use of GLP-1 RAs for the management of diabetes. Although the newer class of drugs are associated with significant benefits such as patient-centric approach, these drugs demand the providers to be vigilant and knowledgeable about the medication. The South Asian population is at higher risk of type 2 diabetes mellitus (T2DM) because of their genetic predisposition and lifestyle changes. Hence, prevention and management of T2DM and its associated complications in this population are of paramount importance. The current report aims to present an overview of current knowledge on GLP-1 RAs based on pragmatic review of the available clinical evidence. In addition, this report is a consensus of expert endocrinologists representing South Asian countries including India, Pakistan, Bangladesh, Nepal, Sri Lanka, Afghanistan and the Maldives on essential recommendations related to the use of GLP-1 RAs in a real-world scenario.

Management of Diabetes Mellitus in Normal Renal Function, Renal Dysfunction and Renal Transplant Recipients, Focusing on Glucagon-Like Peptide-1 Agonist: A Review Based upon Current Evidence

Diabetes Mellitus (DM) is a leading cause of both Cardiovascular Disease (CVD) and End-stage Renal Disease (ESRD). After 2008, there has been much evidence presented, and recently the guidelines for sugar control have changed to focus on being more disease orientated. GLP-1 Receptor Agonists (GLP-1R) and sodium glucose cotransporter-2 inhibitors are suggested as the first line towards fighting all DM, CVD and ESRD. However, the benefits of GLP-1R in organ transplantation recipients remain very limited. No clinical trials have been designed for this particular population. GLP-1R, a gastrointestinal hormone of the incretin family, possesses antidiabetic, antihypertensive, anti-inflammatory, anti-apoptotic and immunomodulatory actions. There are few drug–drug interactions, with delayed gastric emptying being the major concern. The trough level of tacrolimus may not be significant but should still be closely monitored. There are some reasons which support GLP-1R in recipients seeking glycemic control. Post-transplant DM is due to an impaired β-cell function and glucose-induced glucagon suppression during hyperglycemia, which can be reversed by GLP-1R. GLP-1R infusion tends to relieve immunosuppressant related toxicity. Until now, in some cases, glycemic control and body weight reduction can be anticipated with GLP-1R. Additional renal benefits have also been reported. Side effects of hypoglycemia and gastrointestinal discomfort were rarely reported. In conclusion, GLP-1R could be implemented for recipients while closely monitoring their tacrolimus levels and any potential side effects. Any added benefits, in addition to sugar level control, still require more well-designed studies to prove their existence.

LRG ameliorates steatohepatitis by activating the AMPK/mTOR/SREBP1 signaling pathway in C57BL/6J mice fed a high‑fat diet

The pathogenesis of nonalcoholic fatty liver disease non‑alcoholic steatohepatitis (NASH) has not been fully elucidated, and there are currently no effective treatments for NASH. The aim of the present study was to explore the therapeutic effects of the glucagon‑like peptide‑1 (GLP‑1) receptor agonist liraglutide (LRG) on NASH and the underlying mechanisms. C57BL6J mice were fed a high‑fat diet (HFD) for 8 weeks to induce hepatic steatosis, and then LRG was injected subcutaneously for 4 weeks. The expression of sterol regulatory element‑binding protein 1 (SREBP1) and adenosine monophosphate‑activated protein kinase (AMPK) as well as the phosphorylation of mechanistic target of rapamycin (mTOR) and p70 ribosomal S6 kinase (p70S6K) were determined by western blot analysis. The intracellular distribution of SREBP1 was assessed by immunofluorescence staining. The results revealed that LRG treatment ameliorated HFD‑induced hepatic lipid accumulation and inhibited body weight gain. In addition, LRG treatment significantly suppressed the expression of hepatic SREBP1 as well as the phosphorylation of mTOR and p70S6K; it also increased the phosphorylation of AMPK and acetyl coenzyme A carboxylase. Furthermore, LRG treatment inhibited the hepatic nuclear translocation of SREBP1. It was suggested that the GLP‑1 receptor agonist LRG may have ameliorated hepatic steatosis by activating the AMPK/mTOR/SREBP1 signaling pathway as opposed to inhibiting body weight gain.

Recombinant human glucagon-like peptide-1 protects against chronic intermittent hypoxia by improving myocardial energy metabolism and mitochondrial biogenesis

BACKGROUND AND AIMS

Obstructive sleep apnea syndrome is a chronic disease associated with intermittent hypoxia (IH) and is an important risk factor for cardiovascular disease. Glucagon-like peptide (GLP-1) is a naturally occurring incretin used as a promising therapeutic agent in the treatment of acute myocardial infarction, dilated cardiomyopathy, and advanced heart failure. However, whether GLP-1 can protect against IH-induced cardiac injury is still unclear. Accordingly, in this study, we evaluated the effects of recombinant human GLP-1 (rhGLP-1) on cardiac health in mice.

METHODS

Mice were subjected to repetitive 5% O₂ for 30 s and 21% O₂ for 30 s, for a total of 8 h/day for 4 weeks. Subsequently, mice received subcutaneous injection of saline or rhGLP-1 (100 μg/kg, three times per day). Cardiac function, myocardial apoptosis and fibrosis, energy metabolism, and mitochondrial biogenesis were examined for evaluation of cardiac injury.

RESULTS

A reduction in diastolic function (E/A ratio) in mice exposed to IH was significantly reversed by rhGLP-1. IH induced marked cardiomyocyte apoptosis and myocardial fibrosis. Additionally, IH resulted in a shift from fatty acid to glucose metabolism in the myocardium with downregulation of peroxisome proliferator-activated receptor (PPAR) α and PPARγ. Moreover, IH caused a reduction in mitochondrial DNA (mtDNA) replication and transcription, together with reduced mtDNA content and impaired mitochondrial ultrastructure. These changes were abolished by rhGLP-1 via activation of PGC-1α and Akt signaling.

CONCLUSIONS

rhGLP-1 protects against IH-induced cardiac injury by improving myocardial energy metabolism and enhancing the early adaptive changes of mitochondrial biogenesis.

GLP-1 receptor agonists in NAFLD

Non-alcoholic fatty liver disease (NAFLD) is very common in patients with type 2 diabetes (T2D), with approximately two-thirds having a diagnosis of the disease. Currently, the only validated treatment for NAFLD is weight loss. A number of studies of animal models and human trials have evaluated the effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on liver fat content and suggest that the treatment could represent a new alternative for NAFLD management. In this review, our focus is on the main studies regarding the effects of GLP-1RAs on NAFLD. Also, the mechanisms that might explain their beneficial effects on liver diseases are analyzed.

Semaglutide: Review and Place in Therapy for Adults With Type 2 Diabetes

Guidelines increasingly highlight the importance of multifactorial management in type 2 diabetes, in contrast to the more traditional focus on glycemic control. Semaglutide, a recently approved glucagon-like peptide-1 receptor agonist, is indicated in Canada for adults with type 2 diabetes to improve glycemic control as monotherapy with diet and exercise when metformin is inappropriate or as an add-on to either metformin alone or metformin plus a sulfonylurea or basal insulin. The Semaglutide Unabated Sustainability in Treatment of Type 2 Diabetes (SUSTAIN) clinical trial program for semaglutide comprises 6 pivotal global phase 3a trials (SUSTAIN 1 through 6) and 2 Japanese phase 3a trials. Phase 3b trials include SUSTAIN 7, and SUSTAIN 8 and 9 (both ongoing). Results from the completed trials support the superiority of semaglutide for reduction of glycated hemoglobin levels and weight loss vs. placebo as well as active comparators, including sitagliptin, exenatide extended-release, dulaglutide and insulin glargine. SUSTAIN 6 trial data confirmed cardiovascular safety and demonstrated significant reductions in major cardiovascular events with semaglutide vs. placebo, an outcome that confirmed the noninferiority of semaglutide. The robust and sustained effects of semaglutide on glycated hemoglobin levels and weight loss vs. comparators, as well as its safety and possible cardiovascular benefit, address an unmet need in the treatment of type 2 diabetes. This article overviews data from across the semaglutide clinical trial program, including efficacy and safety results and findings from post hoc analyses. The potential place of semaglutide in clinical practice is discussed.

Poststatin era in atherosclerosis management: lessons from epidemiologic and genetic studies

PURPOSE OF REVIEW

Cardiovascular diseases (CVD) are the leading cause of death worldwide with over 17 million deaths every year and represent a major public health challenge. The last decade has seen the emergence of novel antiatherogenic therapies.

RECENT FINDINGS

Despite intensive lipid and blood pressure interventions, the burden of CVD is expected to markedly progress because of the global aging of the population and increasing exposure to detrimental lifestyle-related risk. Epidemiologic and genetic studies helped to better apprehend the biology of atherosclerosis and allowed pharmaceutical innovation and recent translational successes. This includes the development of novel lipid and glucose-lowering therapies and the leverage of anti-inflammatory therapies.

SUMMARY

Here, we discuss promises and expectations of emerging scientific and pharmaceutical innovations and translational successes to meet the global therapeutic demand.

Post-Liver Transplantation Diabetes Mellitus: A Review of Relevance and Approach to Treatment

Post-liver transplantation diabetes mellitus (PLTDM) develops in up to 30% of liver transplant recipients and is associated with increased risk of mortality and multiple morbid outcomes. PLTDM is a multicausal disorder, but the main risk factor is the use of immunosuppressive agents of the calcineurin inhibitor (CNI) family (tacrolimus and cyclosporine). Additional factors, such as pre-transplant overweight, nonalcoholic steatohepatitis and hepatitis C virus infection, may further increase risk of developing PLTDM. A diagnosis of PLTDM should be established only after doses of CNI and steroids are stable and the post-operative stress has been overcome. The predominant defect induced by CNI is insulin secretory dysfunction. Plasma glucose control must start immediately after the transplant procedure in order to improve long-term results for both patient and transplant. Among the better known antidiabetics, metformin and DPP-4 inhibitors have a particularly benign profile in the PLTDM context and are the preferred oral agents for long-term management. Insulin therapy is also an effective approach that addresses the prevailing pathophysiological defect of the disorder. There is still insufficient evidence about the impact of newer families of antidiabetics (GLP-1 agonists, SGLT-2 inhibitors) on PLTDM. In this review, we summarize current knowledge on the epidemiology, pathogenesis, course of disease and medical management of PLTDM.

Sitagliptin attenuates inflammatory responses in lipopolysaccharide-stimulated cardiomyocytes via nuclear factor-κB pathway inhibition

Glucagon-like peptide-1 (GLP-1) and GLP-1 receptors (GLP-1Rs) are responsible for glucose homeostasis, and have been shown to reduce inflammation in preclinical studies. The aim of the present study was to determine whether sitagliptin, an inhibitor of the enzyme dipeptidyl peptidase-4 (DPP-4), as a GLP-1 receptor agonist, exerts an anti-inflammatory effect on cardiomyoblasts during lipopolysaccharide (LPS) stimulation. Exposure to LPS increased the expression levels of tumor necrosis factor (TNF)-α, interleukin-6 (IL)-6 and IL-1β in H9c2 cells, and also resulted in elevations in cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression and nuclear factor-κB (NF-κB) nuclear translocation. Treatment with the DPP-4 inhibitor sitagliptin dose-dependently downregulated the mRNA levels of IL-6, COX-2 and iNOS in LPS-stimulated H9c2 cells. In addition, sitagliptin inhibited the increased protein expression of IL-6, TNF-α and IL-1β. NF-κB mRNA expression was reduced and its translocation to the nucleus was suppressed by treatment with sitagliptin. The present results demonstrated that sitagliptin exerts a beneficial effect on cardiomyoblasts exposed to LPS by inhibiting expression of inflammatory mediators and suppressing NF-κB activation. These findings indicate that the DPP-4 inhibitor sitagliptin may serve a function in cardiac remodeling attributed to sepsis-induced inflammation.