Efficacy of glucagon-like peptide-1 and estrogen dual agonist in pancreatic islets protection and pre-clinical models of insulin-deficient diabetes

MASLD: Prevalence, Mechanisms, and Sex-Based Therapies in Postmenopausal Women

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease influenced by genetic, lifestyle, and environmental factors. While MASLD is more prevalent in men, women are at increased risk after menopause, highlighting the critical pathogenetic role of sex hormones. The complex interplay between estrogen deficiency, visceral fat accumulation, metabolic syndrome (MetS), and inflammation accelerates disease progression, increases cardiovascular (CV) risk, and triggers a cycle of worsening adiposity, metabolic dysfunction, and psychological problems, including eating disorders. Weight loss in postmenopausal women can significantly improve both metabolic and psychological outcomes, helping to prevent MASLD and related conditions. This review examines the prevalence of MASLD, its comorbidities (type 2 diabetes T2D, CV, mental disorders), pathogenetic mechanisms, and pharmacological treatment with GLP-1 receptor agonists (GLP1-RAs), with a focus on postmenopausal women. Given the use of GLP1-RAs in the treatment of obesity and T2D in MASLD patients, and the increase in MetS and MASLD after menopause, this review analyzes the potential of a stable GLP-1-estrogen conjugate as a therapeutic approach in this subgroup. By combining the synergistic effects of both hormones, this dual agonist has been shown to increase food intake and food reward suppression, resulting in greater weight loss and improved insulin sensitivity, glucose, and lipid metabolism. Therefore, we hypothesize that this pharmacotherapy may provide more targeted therapeutic benefits than either hormone alone by protecting the liver, β-cells, and overall metabolic health. As these effects are only supported by preclinical data, this review highlights the critical need for future research to evaluate and confirm the mechanisms and efficacy in clinical settings, particularly in postmenopausal women.

The role of estrogen in the sex difference for the risk factors of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a major subtype of heart failure, primarily characterized by a normal or mildly reduced left ventricular ejection fraction along with left ventricular diastolic dysfunction. Recent studies have shown that the prevalence of HFpEF is higher in women than that in men, particularly in postmenopausal women. Concurrently, it has been observed that the incidence of risk factors contributing to HFpEF (such as obesity, hypertension, diabetes, and atrial fibrillation) also notably increases post-menopause, affecting the incidence of HFpEF. This review aimed to examine the relationship between estrogen and risk factors associated with HFpEF, clarifying the underlying mechanisms through which estrogen affects these risk factors from epidemiological and pathophysiological perspectives. This review also provides a comprehensive understanding of the association between estrogen and the risk factors for HFpEF, thus helping explore potential targets for HFpEF treatment.

Fibrinogen-to-Albumin Ratio and Glucose Metabolic States in Patients With Coronary Heart Disease

This study investigated the relationship between fibrinogen-to-albumin ratio (FAR) and glucose metabolic state in patients with coronary heart disease (CHD). A total of 52,062 patients were enrolled in this study. Patients were classified according to FAR tertiles (T1: FAR < 0.0073; T2: 0.0073 ≤ FAR ≤ 0.0886; T3: FAR ≥ 0.0887). Patients were also classified into the normal glucose regulation (NGR) and elevated blood glucose (EBG) groups. The relationship between FAR and EBG was analyzed using logistic regression, and the association was evaluated according to sex and age. Among the participants, 32,471 (62.4%) had EBG, which was positively associated with FAR (odds ratio [OR], 1.19; 95% confidence interval [CI] 1.15-1.23). The OR of the FAR for EBG in males was higher than that in females (1.25; 95% CI 1.18-1.33 vs 1.15; 95% CI 1.10-1.20). Moreover, the OR of FAR for EBG was greater in patients aged 60 or younger (OR: 1.25; 95% CI 1.18-1.33) than in the elderly patients (over 60 years of age) (OR: 1.15; 95% CI 1.10-1.20). The results indicated a significant relationship between FAR and EBG and this association was higher in males and middle-aged patients.

GLP-1-based therapies for type 2 diabetes: from single, dual and triple agonists to endogenous GLP-1 production and L-cell differentiation

Glucagon-like peptide-1 (GLP-1) is an incretin peptide hormone mainly secreted by enteroendocrine intestinal L-cells. GLP-1 is also secreted by α-cells of the pancreas and the central nervous system (CNS). GLP-1 secretion is stimulated by nutrient intake and exerts its effects on glucose homeostasis by stimulating insulin secretion, gastric emptying confiding the food intake, and β-cell proliferation. The insulinotropic effects of GLP-1, and the reduction of its effects in type 2 diabetes mellitus (T2DM), have made GLP-1 an attractive option for the treatment of T2DM. Furthermore, GLP-1-based medications such as GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, have been shown to improve diabetes control in preclinical and clinical trials with human subjects. Importantly, increasing the endogenous production of GLP-1 by different mechanisms or by increasing the number of intestinal L-cells that tend to produce this hormone may be another effective therapeutic approach to managing T2DM. Herein, we briefly describe therapeutic agents/compounds that enhance GLP-1 function. Then, we will discuss the approaches that can increase the endogenous production of GLP-1 through various stimuli. Finally, we introduce the potential of L-cell differentiation as an attractive future therapeutic approach to increase GLP-1 production as an attractive therapeutic alternative for T2DM.

GLP-1 and Its Analogs: Does Sex Matter?

While obesity and diabetes are prevalent in both men and women, some aspects of these diseases differ by sex. A new blockbuster class of therapeutics, glucagon-like peptide 1 (GLP-1) analogs (eg, semaglutide), shows promise at curbing both diseases. This review addresses the topic of sex differences in the endogenous and therapeutic actions of GLP-1 and its analogs. Work on sex differences in human studies and animal research is reviewed. Preclinical data on the mechanisms of potential sex differences in the endogenous GLP-1 system as well as the therapeutic effect of GLP-1 analogs, focusing on the effects of the drugs on the brain and behavior relating to appetite and metabolism, are highlighted. Moreover, recent clinical evidence of sex differences in the therapeutic effects of GLP-1 analogs in obesity, diabetes, and cardiovascular disease are discussed. Lastly, we review evidence for the role of GLP-1 analogs in mood and reproductive function, with particular attention to sex differences. Overall, while we did not find evidence for many qualitative sex differences in the therapeutic effect of clinically approved GLP-1 analogs, a growing body of literature highlights quantitative sex differences in the response to GLP-1 and its analogs as well as an interaction of these therapeutics with estrogens. What also clearly emerges is the paucity of data in female animal models or women in very basic aspects of the science of GLP-1-gaps that should be urgently mended, given the growing popularity of these medications, especially in women.

Synergistic effects of glucose tolerance and BMI on cardiovascular events and all-cause mortality in a healthy population: CA.ME.LI.A study 7 years follow-up

The CA.ME.LI.A (CArdiovascular risks, MEtabolic syndrome, LIver and Autoimmune disease) epidemiological study was conducted in Abbiategrasso (Milan, Italy) to identify risk factors for metabolic and cardiovascular disease in an apparently healthy population of northern Italy. The population (n = 2,545, 1,251 men, 1,254 women) was stratified according to body mass index [normal body weight (NBW): <25 kg/m2; overweight-obese (OWO): ≥25 kg/m2] and according to fasting blood glucose [normal fasting glucose: <100 mg/dL; impaired fasting glucose (IFG): 100-125 mg/dL; diabetes mellitus (DM): ≥126 mg/dL]. The incidence of cardiovascular (CV) events and overall mortality were studied by the Kaplan-Meier method using the log rank test. Univariate analysis was conducted with time-dependent Cox models. During the 7-yr follow-up period, 80 deaths and 149 CV events occurred. IFG [hazard ratio (HR): 2.81; confidence interval (CI): 1.37-5.77; P = 0.005], DM (HR: 4.88; CI: 1.47-16; P = 0.010), or OWO (HR: 2.78; CI:1.68-4.59; P < 0.001) all produced significant increases in CV events and deaths. In the combination IFG/OWO (HR: 5.51; CI: 3.34-9.08; P < 0.001), there was an apparent additive effect of the two conditions, whereas in the combination DM/OWO (HR: 12.71; CI: 7.48-22; P < 0.001), there was an apparent multiplicative effect on the risk for CV events and deaths. In males, the DM/NBW group had a higher incidence of cardiovascular events and deaths than the IFG/OWO group. In contrast, in females, the IFG/OWO group had a higher incidence of cardiovascular events and deaths than the DM/NBW group. In women, there was a greater incidence of CV events in the IFG/OWO group (HR: 6.23; CI: 2.88-13; P < 0.001) than in men in the same group (HR: 4.27; CI: 2.15-8.47; P < 0.001). Consistent with these data, also all-cause mortality was progressively increased by IFG/DM and OWO, with an apparently exponential effect in the combination DM/OWO (HR: 11.78; CI: 6.11-23; P < 0.001). IFG/DM and OWO, alone or in combination, had major effects in increasing mortality for all causes and CV events. The relative contributions of hyperglycemia and overweight/obesity on cardiovascular events and deaths were apparently, to a certain extent, sex dependent. Females were more affected by overweight/obesity either alone or combined with IFG, as compared with males.NEW & NOTEWORTHY For the first time, the combined effects of glucose tolerance and BMI have been investigated in an apparently healthy large population sample of a city in the north of Italy. We found that there are synergistic effects of glucose levels with BMI to increase not only cardiovascular events and deaths but also cancer-related deaths and all-cause mortality.

Liraglutide Protects Pancreatic Islet From Ischemic Injury by Reducing Oxidative Stress and Activating Akt Signaling During Cold Preservation to Improve Islet Transplantation Outcomes

BACKGROUND

Islet transplantation is a promising therapy for patients with type 1 diabetes. However, ischemic injury to the donor islets during cold preservation leads to reduced islet quality and compromises transplant outcome. Several studies imply that liraglutide, a glucagon-like peptide-1 receptor agonist, has a positive effect on promoting islet survival, but its impact on islet cold-ischemic injury remains unexplored. Therefore, the aim of this study was to investigate whether liraglutide can improve islet transplantation efficacy by inhibiting cold-ischemic injury and to explore the underlying mechanisms.

METHODS

Liraglutide was applied in a mouse pancreas preservation model and a human islets cold-preservation model, and islet viability, function, oxidative stress levels were evaluated. Furthermore, islet transplantation was performed in a syngeneic mouse model and a human-to-nude mouse islet xenotransplantation model.

RESULTS

The supplementation of liraglutide in preservation solution improved islet viability, function, and reduced cell apoptosis. Liraglutide inhibited the oxidative stress of cold-preserved pancreas or islets through upregulating the antioxidant enzyme glutathione levels, inhibiting reactive oxygen species accumulation, and maintaining the mitochondrial membrane integrity, which is associated with the activation of Akt signaling. Furthermore, the addition of liraglutide during cold preservation of donor pancreas or donor islets significantly improved the subsequent transplant outcomes in both syngeneic mouse islet transplantation model and human-to-nude mouse islet xenotransplantation model.

CONCLUSIONS

Liraglutide protects islets from cold ischemia-related oxidative stress during preservation and hence improved islet transplantation outcomes, and this protective effect of liraglutide in islets is associated with the activation of Akt signaling.

Receptors and Signaling Pathways Controlling Beta-Cell Function and Survival as Targets for Anti-Diabetic Therapeutic Strategies

Preserving the function and survival of pancreatic beta-cells, in order to achieve long-term glycemic control and prevent complications, is an essential feature for an innovative drug to have clinical value in the treatment of diabetes. Innovative research is developing therapeutic strategies to prevent pathogenic mechanisms and protect beta-cells from the deleterious effects of inflammation and/or chronic hyperglycemia over time. A better understanding of receptors and signaling pathways, and of how they interact with each other in beta-cells, remains crucial and is a prerequisite for any strategy to develop therapeutic tools aimed at modulating beta-cell function and/or mass. Here, we present a comprehensive review of our knowledge on membrane and intracellular receptors and signaling pathways as targets of interest to protect beta-cells from dysfunction and apoptotic death, which opens or could open the way to the development of innovative therapies for diabetes.

Hyperglycemia impairs EAAT2 glutamate transporter trafficking and glutamate clearance in islets of Langerhans: implications for type 2 diabetes pathogenesis and treatment

Pancreatic endocrine cells employ a sophisticated system of paracrine and autocrine signals to synchronize their activities, including glutamate, which controls hormone release and β-cell viability by acting on glutamate receptors expressed by endocrine cells. We here investigate whether alteration of the excitatory amino acid transporter 2 (EAAT2), the major glutamate clearance system in the islet, may occur in type 2 diabetes mellitus and contribute to β-cell dysfunction. Increased EAAT2 intracellular localization was evident in islets of Langerhans from T2DM subjects as compared with healthy control subjects, despite similar expression levels. Chronic treatment of islets from healthy donors with high-glucose concentrations led to the transporter internalization in vesicular compartments and reduced [H3]-d-glutamate uptake (65 ± 5% inhibition), phenocopying the findings in T2DM pancreatic sections. The transporter relocalization was associated with decreased Akt phosphorylation protein levels, suggesting an involvement of the phosphoinositide 3-kinase (PI3K)/Akt pathway in the process. In line with this, PI3K inhibition by a 100-µM LY294002 treatment in human and clonal β-cells caused the transporter relocalization in intracellular compartments and significantly reduced the glutamate uptake compared to control conditions, suggesting that hyperglycemia changes the trafficking of the transporter to the plasma membrane. Upregulation of the glutamate transporter upon treatment with the antibiotic ceftriaxone rescued hyperglycemia-induced β-cells dysfunction and death. Our data underscore the significance of EAAT2 in regulating islet physiology and provide a rationale for potential therapeutic targeting of this transporter to preserve β-cell survival and function in diabetes.NEW & NOTEWORTHY The glutamate transporter SLC1A2/excitatory amino acid transporter 2 (EAAT2) is expressed on the plasma membrane of pancreatic β-cells and controls islet glutamate clearance and β-cells survival. We found that the EAAT2 membrane expression is lost in the islets of Langerhans from type 2 diabetes mellitus (T2DM) patients due to hyperglycemia-induced downregulation of the phosphoinositide 3-kinase/Akt pathway and modification of its intracellular trafficking. Pharmacological rescue of EAAT2 expression prevents β-cell dysfunction and death, suggesting EAAT2 as a new potential target of intervention in T2DM.

Poly-Agonist Pharmacotherapies for Metabolic Diseases: Hopes and New Challenges

The use of glucagon-like peptide-1 (GLP-1) receptor-based multi-agonists in the treatment of type 2 diabetes and obesity holds great promise for improving glycaemic control and weight management. Unimolecular dual and triple agonists targeting multiple gut hormone-related pathways are currently in clinical trials, with recent evidence supporting their efficacy. However, significant knowledge gaps remain regarding the biological mechanisms and potential adverse effects associated with these multi-target agents. The mechanisms underlying the therapeutic efficacy of GLP-1 receptor-based multi-agonists remain somewhat mysterious, and hidden threats may be associated with the use of gut hormone-based polyagonists. In this review, we provide a critical analysis of the benefits and risks associated with the use of these new drugs in the management of obesity and diabetes, while also exploring new potential applications of GLP-1-based pharmacology beyond the field of metabolic disease.

Decoding pancreatic endocrine cell differentiation and β cell regeneration in zebrafish

In contrast to mice, zebrafish have an exceptional yet elusive ability to replenish lost β cells in adulthood. Understanding this framework would provide mechanistic insights for β cell regeneration, which may be extrapolated to humans. Here, we characterize a krt4-expressing ductal cell type, which is distinct from the putative Notch-responsive cells, showing neogenic competence and giving rise to the majority of endocrine cells during postembryonic development. Furthermore, we demonstrate a marked ductal remodeling process featuring a Notch-responsive to krt4+ luminal duct transformation during late development, indicating several origins of krt4+ ductal cells displaying similar transcriptional patterns. Single-cell transcriptomics upon a series of time points during β cell regeneration unveil a previously unrecognized dlb+ transitional endocrine precursor cell, distinct regulons, and a differentiation trajectory involving cellular shuffling through differentiation and dedifferentiation dynamics. These results establish a model of zebrafish pancreatic endocrinogenesis and highlight key values of zebrafish for translational studies of β cell regeneration.

Venom Peptides, Polyphenols and Alkaloids: Are They the Next Antidiabetics That Will Preserve β-Cell Mass and Function in Type 2 Diabetes?

Improvement of insulin secretion by pancreatic β-cells and preservation of their mass are the current challenges that future antidiabetic drugs should meet for achieving efficient and long-term glycemic control in patients with type 2 diabetes (T2D). The successful development of glucagon-like peptide 1 (GLP-1) analogues, derived from the saliva of a lizard from the Helodermatidae family, has provided the proof of concept that antidiabetic drugs directly targeting pancreatic β-cells can emerge from venomous animals. The literature reporting on the antidiabetic effects of medicinal plants suggests that they contain some promising active substances such as polyphenols and alkaloids, which could be active as insulin secretagogues and β-cell protectors. In this review, we discuss the potential of several polyphenols, alkaloids and venom peptides from snake, frogs, scorpions and cone snails. These molecules could contribute to the development of new efficient antidiabetic medicines targeting β-cells, which would tackle the progression of the disease.

Therapeutic Strategies Targeting Pancreatic Islet β-Cell Proliferation, Regeneration, and Replacement

Diabetes results from insufficient insulin production by pancreatic islet β-cells or a loss of β-cells themselves. Restoration of regulated insulin production is a predominant goal of translational diabetes research. Here, we provide a brief overview of recent advances in the fields of β-cell proliferation, regeneration, and replacement. The discovery of therapeutic targets and associated small molecules has been enabled by improved understanding of β-cell development and cell cycle regulation, as well as advanced high-throughput screening methodologies. Important findings in β-cell transdifferentiation, neogenesis, and stem cell differentiation have nucleated multiple promising therapeutic strategies. In particular, clinical trials are underway using in vitro-generated β-like cells from human pluripotent stem cells. Significant challenges remain for each of these strategies, but continued support for efforts in these research areas will be critical for the generation of distinct diabetes therapies.