Resolution of NASH and hepatic fibrosis by the GLP-1R/GcgR dual-agonist Cotadutide via modulating mitochondrial function and lipogenesis

Glucagon agonism in the treatment of metabolic diseases including type 2 diabetes mellitus and obesity

Type 2 diabetes mellitus (T2DM) is associated with obesity and, therefore, it is important to target both overweight and hyperglycaemia. Glucagon plays important roles in glucose, amino acid and fat metabolism and may also regulate appetite and energy expenditure. These physiological properties are currently being exploited therapeutically in several compounds, most often in combination with glucagon-like peptide-1 (GLP-1) agonism in the form of dual agonists. With this combination, increases in hepatic glucose production and hyperglycaemia, which would be counterproductive, are largely avoided. In multiple randomized trials, the co-agonists have been demonstrated to lead to significant weight loss and, in participants with T2DM, even improved glycated haemoglobin (HbA1c) levels. In addition, significant reductions in hepatic fat content have been observed. Here, we review and discuss the studies so far available. Twenty-six randomized trials of seven different GLP-1 receptor (GLP-1R)/glucagon receptor (GCGR) co-agonists were identified and reviewed. GLP-1R/GCGR co-agonists generally provided significant weight loss, reductions in hepatic fat content, improved lipid profiles, insulin secretion and sensitivity, and in some cases, improved HbA1c levels. A higher incidence of adverse effects was present with GLP-1R/GCGR co-agonist treatment than with GLP-1 agonist monotherapy or placebo. Possible additional risks associated with glucagon agonism are also discussed. A delicate balance between GLP-1 and glucagon agonism seems to be of particular importance. Further studies exploring the optimal ratio of GLP-1 and glucagon receptor activation and dosage and titration regimens are needed to ensure a sufficient safety profile while providing clinical benefits.

Beta-adrenergic agonism protects mitochondrial metabolism in the pancreatectomised rat heart

The diabetic heart is characterised by functional, morphological and metabolic alterations predisposing it to contractile failure. Chronic sympathetic activation is a feature of the pathogenesis of heart failure, however the type 1 diabetic heart shows desensitisation to β-adrenergic stimulation. Here, we sought to understand the impact of repeated isoprenaline-mediated β-stimulation upon cardiac mitochondrial respiratory capacity and substrate metabolism in the 90% pancreatectomy (Px) rat model of type 1 diabetes. We hypothesised these hearts would be relatively protected against the metabolic impact of stress-induced cardiomyopathy. We found that individually both Px and isoprenaline suppressed cardiac mitochondrial respiration, but that this was preserved in Px rats receiving isoprenaline. Px and isoprenaline had contrasting effects on cardiac substrate metabolism, with increased reliance upon cardiac fatty acid oxidation capacity and altered ketone metabolism in the hearts of Px rats, but enhanced capacity for glucose uptake and metabolism in isoprenaline-treated rats. Moreover, Px rats were protected against isoprenaline-induced mortality, whilst isoprenaline elevated cGMP and protected myocardial energetic status in Px rat hearts. Our work suggests that adrenergic stimulation may be protective in the type 1 diabetic heart, and underlines the importance of studying pathological features in combination when modeling complex disease in rodents.

The Emerging Role of Glucagon-Like Peptide-1 Receptor Agonists for the Treatment of Metabolic Dysfunction-Associated Steatohepatitis

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects 1 in 3-4 adult individuals and can progress to metabolic dysfunction-associated steatohepatitis (MASH) and cirrhosis. Insulin resistance plays a central role in MASLD/MASH pathophysiology with higher rates of MASLD (2 in 3) and MASH with fibrosis (1 in 5) in adults with obesity and diabetes. This review summarizes the role of glucagon-like peptide-1 receptor agonists in treating MASLD/MASH. Although not approved by the Food and Drug Administration for the treatment of MASLD, this class of medication is available to treat obesity and type 2 diabetes and has been shown to reverse steatohepatitis, reduce cardiovascular risk, and is safe to use across the spectrum of MASLD with or without fibrosis.

Hepatic function of glucagon-like peptide-1 and its based diabetes drugs

Incretins are gut-produced peptide-hormones that potentiate insulin secretion, especially after food intake. The concept of incretin was formed more than 100 years ago, even before insulin was isolated and utilized in the treatment of subjects with type 1 diabetes. The first incretin, glucose-dependent insulinotropic polypeptide (GIP), was identified during later 1960's and early 1970's; while the second one, known as glucagon-like peptide-1 (GLP-1), was recognized during 1980's. Today, GLP-1-based therapeutic agents [also known as GLP-1 receptor (GLP-1R) agonists, GLP-1RAs] are among the first line drugs for type 2 diabetes. In addition to serving as incretin, extra-pancreatic functions of GLP-1RAs have been broadly recognized, including those in the liver, despite the absence of GLP-1R in hepatic tissue. The existence of insulin-independent or gut-pancreas-liver axis-independent hepatic function of GLP-1RAs explains why those therapeutic agents are effective in subjects with insulin resistance and their profound effect on lipid homeostasis. Following a brief review on the discovery of GLP-1, we reviewed literature on the exploration of hepatic function of GLP-1 and GLP-1RAs and discussed recent studies on the role of hepatic hormone fibroblast growth factor 21 (FGF21) in mediating function of GLP-1RAs in animal models. This was followed by presenting our perspective views.

Obesity and MASLD: Is weight loss the (only) key to treat metabolic liver disease?

Metabolic dysfunction-associated steatotic liver disease (MASLD) closely associates with obesity and type 2 diabetes. Lifestyle intervention and bariatric surgery aiming at substantial weight loss are cornerstones of MASLD treatment by improving histological outcomes and reducing risks of comorbidities. Originally developed as antihyperglycemic drugs, incretin (co-)agonists and SGLT2 inhibitors also reduce steatosis and cardiorenovascular events. Certain incretin agonists effectively improve histological features of MASLD, but not fibrosis. Of note, beneficial effects on MASLD may not necessarily require weight loss. Despite moderate weight gain, one PPARγ agonist improved adipose tissue and MASLD with certain benefit on fibrosis in post-hoc analyses. Likewise, the first THRβ-agonist was recently provisionally approved because of significant improvements of MASLD and fibrosis. We here discuss liver-related and metabolic effects induced by different MASLD treatments and their association with weight loss. Therefore, we compare results from clinical trials on drugs acting via weight loss (incretin (co)agonists, SGLT2 inhibitors) with those exerting no weight loss (pioglitazone; resmetirom). Furthermore, other drugs in development directly targeting hepatic lipid metabolism (lipogenesis inhibitors, FGF21 analogs) are addressed. Although THRβ-agonism may effectively improve hepatic outcomes, MASLD treatment concepts should consider all cardiometabolic risk factors for effective reduction of morbidity and mortality in the affected people.

CD9 Counteracts Liver Steatosis and Mediates GCGR Agonist Hepatic Effects

Glucagon receptor (GCGR) agonism offers potentially greater effects on the mitigation of hepatic steatosis. However, its underlying mechanism is not fully understood. Here, it screened tetraspanin CD9 might medicate hepatic effects of GCGR agonist. CD9 is decreased in the fatty livers of patients and upregulated upon GCGR activation. Deficiency of CD9 in the liver exacerbated diet-induced hepatic steatosis via complement factor D (CFD) regulated fatty acid metabolism. Specifically, CD9 modulated hepatic fatty acid synthesis and oxidation genes through regulating CFD expression via the ubiquitination-proteasomal degradation of FLI1. In addition, CD9 influenced body weight by modulating lipogenesis and thermogenesis of adipose tissue through CFD. Moreover, CD9 reinforcement in the liver alleviated hepatic steatosis, and blockage of CD9 abolished the remission of hepatic steatosis induced by cotadutide treatment. Thus, CD9 medicates the hepatic beneficial effects of GCGR signaling, and may server as a promising therapeutic target for hepatic steatosis.

Transforming obesity: The advancement of multi-receptor drugs

For more than a century, physicians have searched for ways to pharmacologically reduce excess body fat. The tide has finally turned with recent advances in biochemically engineered agonists for the receptor of glucagon-like peptide-1 (GLP-1) and their use in GLP-1-based polyagonists. These polyagonists reduce body weight through complementary pharmacology by incorporating the receptors for glucagon and/or the glucose-dependent insulinotropic polypeptide (GIP). In their most advanced forms, gut-hormone polyagonists achieve an unprecedented weight reduction of up to ∼20%-30%, offering a pharmacological alternative to bariatric surgery. Along with favorable effects on glycemia, fatty liver, and kidney disease, they also offer beneficial effects on the cardiovascular system and adipose tissue. These new interventions, therefore, hold great promise for the future of anti-obesity medications.

Molecular dynamics-guided optimization of BGM0504 enhances dual-target agonism for combating diabetes and obesity

The dual activation of glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) has emerged as a promising therapeutic strategy for managing type 2 diabetes and obesity. Tirzepatide, a dual agonist peptide, has exhibited superior clinical efficacy in glycemic and weight control compared to selective GLP-1R agonists. Nevertheless, the structural basis of Tirzepatide's extended half-life, attributed to an acylation side chain on the parent peptide, raises questions regarding its partial agonistic activity. Employing molecular dynamics simulations, we explored the dynamic processes of peptide-receptor interactions. We uncovered a crucial salt bridge between parent peptide and GLP-1R/GIPR at K20, a feature not discernible in cryo-electron microscopy structures. Building upon these insights, we developed an optimization strategy based on the parent peptide which involved repositioning the acylation side chain. The results of both in vitro and in vivo experiments demonstrated that the optimized peptide has twofold to threefold increase in agonistic activity compared to Tirzepatide while maintaining its extended half-life in plasma. This led to the design of BGM0504, which proved to be more effective than its predecessor, Tirzepatide, in both laboratory and animal studies.

A roadmap for clinical trials in MASH-related compensated cirrhosis

Although metabolic dysfunction-associated steatohepatitis (MASH) is rapidly becoming a leading cause of cirrhosis worldwide, therapeutic options are limited and the number of clinical trials in MASH-related compensated cirrhosis is low as compared to those conducted in earlier disease stages. Moreover, designing clinical trials in MASH cirrhosis presents a series of challenges regarding the understanding and conceptualization of the natural history, regulatory considerations, inclusion criteria, recruitment, end points and trial duration, among others. The first international workshop on the state of the art and future direction of clinical trials in MASH-related compensated cirrhosis was held in April 2023 at Vall d'Hebron University Hospital in Barcelona (Spain) and was attended by a group of international experts on clinical trials from academia, regulatory agencies and industry, encompassing expertise in MASH, cirrhosis, portal hypertension, and regulatory affairs. The presented Roadmap summarizes important content of the workshop on current status, regulatory requirements and end points in MASH-related compensated cirrhosis clinical trials, exploring alternative study designs and highlighting the challenges that should be considered for upcoming studies on MASH cirrhosis.

Regulation of Fructose Metabolism in Nonalcoholic Fatty Liver Disease

Elevations in fructose consumption have been reported to contribute significantly to an increased incidence of obesity and metabolic diseases in industrial countries. Mechanistically, a high fructose intake leads to the dysregulation of glucose, triglyceride, and cholesterol metabolism in the liver, and causes elevations in inflammation and drives the progression of nonalcoholic fatty liver disease (NAFLD). A high fructose consumption is considered to be toxic to the body, and there are ongoing measures to develop pharmaceutical therapies targeting fructose metabolism. Although a large amount of work has summarized the effects fructose exposure within the intestine, liver, and kidney, there remains a gap in our knowledge regarding how fructose both indirectly and directly influences immune cell recruitment, activation, and function in metabolic tissues, which are essential to tissue and systemic inflammation. The most recent literature demonstrates that direct fructose exposure regulates oxidative metabolism in macrophages, leading to inflammation. The present review highlights (1) the mechanisms by which fructose metabolism impacts crosstalk between tissues, nonparenchymal cells, microbes, and immune cells; (2) the direct impact of fructose on immune cell metabolism and function; and (3) therapeutic targets of fructose metabolism to treat NAFLD. In addition, the review highlights how fructose disrupts liver tissue homeostasis and identifies new therapeutic targets for treating NAFLD and obesity.

Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial

Retatrutide is a novel triple agonist of the glucose-dependent insulinotropic polypeptide, glucagon-like peptide 1 and glucagon receptors. A 48-week phase 2 obesity study demonstrated weight reductions of 22.8% and 24.2% with retatrutide 8 and 12 mg, respectively. The primary objective of this substudy was to assess mean relative change from baseline in liver fat (LF) at 24 weeks in participants from that study with metabolic dysfunction-associated steatotic liver disease and ≥10% of LF. Here, in this randomized, double-blind, placebo-controlled trial, participants (n = 98) were randomly assigned to 48 weeks of once-weekly subcutaneous retatrutide (1, 4, 8 or 12 mg dose) or placebo. The mean relative change from baseline in LF at 24 weeks was -42.9% (1 mg), -57.0% (4 mg), -81.4% (8 mg), -82.4% (12 mg) and +0.3% (placebo) (all P < 0.001 versus placebo). At 24 weeks, normal LF (<5%) was achieved by 27% (1 mg), 52% (4 mg), 79% (8 mg), 86% (12 mg) and 0% (placebo) of participants. LF reductions were significantly related to changes in body weight, abdominal fat and metabolic measures associated with improved insulin sensitivity and lipid metabolism. The ClinicalTrials.gov registration is NCT04881760 .

Dual glucagon-like peptide-1 and glucagon receptor agonism reduces energy intake in type 2 diabetes with obesity

AIMS

To establish which components of energy balance mediate the clinically significant weight loss demonstrated with use of cotadutide, a glucagon-like peptide-1 (GLP-1)/glucagon receptor dual agonist, in early-phase studies.

MATERIALS AND METHODS

We conducted a phase 2a, single-centre, randomized, placebo-controlled trial in overweight and obese adults with type 2 diabetes. Following a 16-day single-blind placebo run-in, participants were randomized 2:1 to double-blind 42-day subcutaneous treatment with cotadutide (100-300 μg daily) or placebo. The primary outcome was percentage weight change. Secondary outcomes included change in energy intake (EI) and energy expenditure (EE).

RESULTS

A total of 12 participants (63%) in the cotadutide group and seven (78%) in the placebo group completed the study. The mean (90% confidence interval [CI]) weight change was -4.0% (-4.9%, -3.1%) and -1.4% (-2.7%, -0.1%) for the cotadutide and placebo groups, respectively (p = 0.011). EI was lower with cotadutide versus placebo (-41.3% [-66.7, -15.9]; p = 0.011). Difference in EE (per kJ/kg lean body mass) for cotadutide versus placebo was 1.0% (90% CI -8.4, 10.4; p = 0.784), assessed by doubly labelled water, and -6.5% (90% CI -9.3, -3.7; p < 0.001), assessed by indirect calorimetry.

CONCLUSION

Weight loss with cotadutide is primarily driven by reduced EI, with relatively small compensatory changes in EE.

Chronic treatment with glucagon-like peptide-1 and glucagon receptor co-agonist causes weight loss-independent improvements in hepatic steatosis in mice with diet-induced obesity

OBJECTIVES

Co-agonists at the glucagon-like peptide-1 and glucagon receptors (GLP1R/GCGR) show promise as treatments for metabolic dysfunction-associated steatotic liver disease (MASLD). Although most co-agonists to date have been heavily GLP1R-biased, glucagon directly acts on the liver to reduce fat content. The aims of this study were to investigate a GCGR-biased co-agonist as treatment for hepatic steatosis in mice.

METHODS

Mice with diet-induced obesity (DIO) were treated with Dicretin, a GLP1/GCGR co-agonist with high potency at the GCGR, Semaglutide (GLP1R monoagonist) or food restriction over 24 days, such that their weight loss was matched. Hepatic steatosis, glucose tolerance, hepatic transcriptomics, metabolomics and lipidomics at the end of the study were compared with Vehicle-treated mice.

RESULTS

Dicretin lead to superior reduction of hepatic lipid content when compared to Semaglutide or equivalent weight loss by calorie restriction. Markers of glucose tolerance and insulin resistance improved in all treatment groups. Hepatic transcriptomic and metabolomic profiling demonstrated many changes that were unique to Dicretin-treated mice. These include some known targets of glucagon signaling and others with as yet unclear physiological significance.

CONCLUSIONS

Our study supports the development of GCGR-biased GLP1/GCGR co-agonists for treatment of MASLD and related conditions.

Hepatic glucagon action: beyond glucose mobilization

Glucagon's ability to promote hepatic glucose production has been known for over a century, with initial observations touting this hormone as a diabetogenic agent. However, glucagon receptor agonism [when balanced with an incretin, including glucagon-like peptide 1 (GLP-1) to dampen glucose excursions] is now being developed as a promising therapeutic target in the treatment of metabolic diseases, like metabolic dysfunction-associated steatotic disease/metabolic dysfunction-associated steatohepatitis (MASLD/MASH), and may also have benefit for obesity and chronic kidney disease. Conventionally regarded as the opposing tag-team partner of the anabolic mediator insulin, glucagon is gradually emerging as more than just a "catabolic hormone." Glucagon action on glucose homeostasis within the liver has been well characterized. However, growing evidence, in part thanks to new and sensitive "omics" technologies, has implicated glucagon as more than just a "glucose liberator." Elucidation of glucagon's capacity to increase fatty acid oxidation while attenuating endogenous lipid synthesis speaks to the dichotomous nature of the hormone. Furthermore, glucagon action is not limited to just glucose homeostasis and lipid metabolism, as traditionally reported. Glucagon plays key regulatory roles in hepatic amino acid and ketone body metabolism, as well as mitochondrial turnover and function, indicating broader glucagon signaling consequences for metabolic homeostasis mediated by the liver. Here we examine the broadening role of glucagon signaling within the hepatocyte and question the current dogma, to appreciate glucagon as more than just that "catabolic hormone."

Advances in basic research on glucagon and alpha cells

The regulation of plasma amino acid levels by glucagon in humans first attracted the attention of researchers in the 1980s. Recent basic research using animal models of glucagon deficiency suggested that a major physiological role of glucagon is the regulation of amino acid metabolism rather than to increase blood glucose levels. In this regard, novel feedback regulatory mechanisms that are mediated by glucagon and amino acids have recently been described between islet alpha cells and the liver. Increasingly, hyperglucagonemia in humans with diabetes and/or nonalcoholic fatty liver diseases is reported to likely be a compensatory response to hepatic glucagon resistance. Severe glucagon resistance due to a glucagon receptor mutation in humans causes hyperaminoacidemia and islet alpha cell expansion combined with pancreatic hypertrophy. Notably, a recent report showed that the restoration of glucagon resistance by liver transplantation resolved not only hyperglucagonemia, but also pancreatic hypertrophy and other metabolic disorders. The mechanisms that regulate islet cell proliferation by amino acids largely remain unelucidated. Clarification of such mechanisms will increase our understanding of the pathophysiology of diseases related to glucagon.

Role of gut-liver axis and glucagon-like peptide-1 receptor agonists in the treatment of metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a hepatic manifestation of the metabolic syndrome. It is one of the most common liver diseases worldwide and shows increasing prevalence rates in most countries. MAFLD is a progressive disease with the most severe cases presenting as advanced fibrosis or cirrhosis with an increased risk of hepatocellular carcinoma. Gut microbiota play a significant role in the pathogenesis and progression of MAFLD by disrupting the gut-liver axis. The mechanisms involved in maintaining gut-liver axis homeostasis are complex. One critical aspect involves preserving an appropriate intestinal barrier permeability and levels of intestinal lumen metabolites to ensure gut-liver axis functionality. An increase in intestinal barrier permeability induces metabolic endotoxemia that leads to steatohepatitis. Moreover, alterations in the absorption of various metabolites can affect liver metabolism and induce liver steatosis and fibrosis. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are a class of drugs developed for the treatment of type 2 diabetes mellitus. They are also commonly used to combat obesity and have been proven to be effective in reversing hepatic steatosis. The mechanisms reported to be involved in this effect include an improved regulation of glycemia, reduced lipid synthesis, β-oxidation of free fatty acids, and induction of autophagy in hepatic cells. Recently, multiple peptide receptor agonists have been introduced and are expected to increase the effectiveness of the treatment. A modulation of gut microbiota has also been observed with the use of these drugs that may contribute to the amelioration of MAFLD. This review presents the current understanding of the role of the gut-liver axis in the development of MAFLD and use of members of the GLP-1 RA family as pleiotropic agents in the treatment of MAFLD.

Outcomes of bariatric surgery in the setting of compensated advanced chronic liver disease associated with clinically significant portal hypertension: a multicenter, retrospective, cohort study on feasibility and safety

BACKGROUND

The obesity epidemic has led to an increase in the proportion of patients with chronic liver disease due to metabolic associated steatosic liver disease and in the prevalence of obesity in patients with cirrhosis. Metabolic and bariatric surgery (MBS) has been proven to determine weight loss, obesity-related medical problems remission, and liver steatosis, inflammation, and fibrosis improvement. However, cirrhosis and portal hypertension are well-known risk factors for increased morbidity and mortality after surgery. The aim of this study is to evaluate the safety of MBS in patients with compensated advanced chronic liver disease (cALCD) and clinically significant portal hypertension (CSPH).

MATERIAL AND METHODS

This is an international, multicentric, retrospective study on 63 individuals affected by obesity with cALCD and CSPH who underwent MBS in tertiary referral centers with experts hepatobiliary surgeons between January 2010 and October 2022. The primary endpoint was postoperative mortality at 90 days. The secondary endpoints included postoperative weight loss at last follow-up and postoperative complication rate. In addition, the authors performed subgroup analyses of Child-Pugh (A vs. B) score, MELD (≤9 vs. >9) score, and type of surgery.

RESULTS

One patient (1.6%) experienced gastric leakage and mortality. There were three (5%) reported cases of portal vein thrombosis, two (3%) postoperative acute renal failure, and one (1.6%) postoperative encephalopathy. Child-Pugh score A resulted to be a protective factor for intraoperative bleeding requiring transfusion at univariate analysis (OR: 0.73, 95% CI: 0.55-0.97, P =0.046) but not at multivariate analysis. MELD>9 score and the type of surgery did not result to be a risk factor for any postoperative complication.

CONCLUSION

MBS is safe in patients with cALCD and CSPH performed in tertiary bariatric referral centers with hepatobiliary expert surgeons. Larger, prospective studies with longer follow-up periods are needed to confirm these results.

Cryo-electron microscopy for GPCR research and drug discovery in endocrinology and metabolism

G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors, with many GPCRs having crucial roles in endocrinology and metabolism. Cryogenic electron microscopy (cryo-EM) has revolutionized the field of structural biology, particularly regarding GPCRs, over the past decade. Since the first pair of GPCR structures resolved by cryo-EM were published in 2017, the number of GPCR structures resolved by cryo-EM has surpassed the number resolved by X-ray crystallography by 30%, reaching >650, and the number has doubled every ~0.63 years for the past 6 years. At this pace, it is predicted that the structure of 90% of all human GPCRs will be completed within the next 5-7 years. This Review highlights the general structural features and principles that guide GPCR ligand recognition, receptor activation, G protein coupling, arrestin recruitment and regulation by GPCR kinases. The Review also highlights the diversity of GPCR allosteric binding sites and how allosteric ligands could dictate biased signalling that is selective for a G protein pathway or an arrestin pathway. Finally, the authors use the examples of glycoprotein hormone receptors and glucagon-like peptide 1 receptor to illustrate the effect of cryo-EM on understanding GPCR biology in endocrinology and metabolism, as well as on GPCR-related endocrine diseases and drug discovery.

Role of incretins and glucagon receptor agonists in metabolic dysfunction-associated steatotic liver disease: Opportunities and challenges

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become the most common chronic liver disease worldwide, paralleling the rising pandemic of obesity and type 2 diabetes. Due to the growing global health burden and complex pathogenesis of MASLD, a multifaceted and innovative therapeutic approach is needed. Incretin receptor agonists, which were initially developed for diabetes management, have emerged as promising candidates for MASLD treatment. This review describes the pathophysiological mechanisms and action sites of three major classes of incretin/glucagon receptor agonists: glucagon-like peptide-1 receptor agonists, glucose-dependent insulinotropic polypeptide receptor agonists, and glucagon receptor agonists. Incretins and glucagon directly or indirectly impact various organs, including the liver, brain, pancreas, gastrointestinal tract, and adipose tissue. Thus, these agents significantly improve glycemic control and weight management and mitigate MASLD pathogenesis. Importantly, this study provides a summary of clinical trials analyzing the effectiveness and safety of incretin receptor agonists in MASLD management and provides an in-depth analysis highlighting their beneficial effects on improving liver function, hepatic steatosis, and intrahepatic inflammation. There are emerging challenges associated with the use of these medications in the real world, particularly adverse events, drug-drug interactions, and barriers to access, which are discussed in detail. Additionally, this review highlights the evolving role of incretin receptor agonists in MASLD management and suggests future research directions.

RNA expression changes driven by altered epigenetics status related to NASH etiology

Non-alcoholic fatty liver disease (NAFLD) is a growing health problem due to the increased obesity rates, among other factors. In its more severe stage (NASH), inflammation, hepatocellular ballooning and fibrosis are present in the liver, which can further evolve to total liver dysfunction or even hepatocarcinoma. As a metabolic disease, is associated to environmental factors such as diet and lifestyle conditions, which in turn can influence the epigenetic landscape of the cells, affecting to the gene expression profile and chromatin organization. In this study we performed ATAC-sequencing and RNA-sequencing to interrogate the chromatin status of liver biopsies in subjects with and without NASH and its effects on RNA transcription and NASH etiology. NASH subjects showed transcriptional downregulation for lipid and glucose metabolic pathways (e.g., ABC transporters, AMPK, FoxO or insulin pathways). A total of 229 genes were differentially enriched (ATAC and mRNA) in NASH, which were mainly related to lipid transport activity, nuclear receptor-binding, dicarboxylic acid transporter, and PPARA lipid regulation. Interpolation of ATAC data with known liver enhancer regions showed differential openness at 8 enhancers, some linked to genes involved in lipid metabolism, (i.e., FASN) and glucose homeostasis (i.e., GCGR). In conclusion, the chromatin landscape is altered in NASH patients compared to patients without this liver condition. This alteration might cause mRNA changes explaining, at least partially, the etiology and pathophysiology of the disease.

Glucagon-Like Peptide-1: New Regulator in Lipid Metabolism

Glucagon-like peptide-1 (GLP-1) is a 30-amino acid peptide hormone that is mainly expressed in the intestine and hypothalamus. In recent years, basic and clinical studies have shown that GLP-1 is closely related to lipid metabolism, and it can participate in lipid metabolism by inhibiting fat synthesis, promoting fat differentiation, enhancing cholesterol metabolism, and promoting adipose browning. GLP-1 plays a key role in the occurrence and development of metabolic diseases such as obesity, nonalcoholic fatty liver disease, and atherosclerosis by regulating lipid metabolism. It is expected to become a new target for the treatment of metabolic disorders. The effects of GLP-1 and dual agonists on lipid metabolism also provide a more complete treatment plan for metabolic diseases. This article reviews the recent research progress of GLP-1 in lipid metabolism.

The effects of Fc fusion protein glucagon-like peptide-1 and glucagon dual receptor agonist with different receptor selectivity in vivo studies

BACKGROUND

Glucagon-like peptide-1 (GLP-1)/glucagon (GCG) dual receptor agonists with different receptor selectivity are under investigation and have shown significant improvement in both weight loss and glycemic control, but the optimal potency ratio between the two receptors to balance efficacy and safety remains unclear.

EXPERIMENTAL APPROACH

We designed and constructed several dual receptor agonists with different receptor potency ratios using Fc fusion protein technology. The long-term effects of the candidates on body weight and metabolic dysfunction-associated steatotic liver disease (MASLD) were evaluated in diet-induced obese (DIO) model mice, high-fat diet (HFD)-ob/ob mice and AMLN diet-induced MASLD mice. Repeat dose toxicity assays were performed to investigate the safety profile of the candidate (HEC-C070) in Sprague Dawley (SD) rats.

KEY RESULTS

The high GCG receptor (GCGR) selectivity of HEC-C046 makes it more prominent than other compounds for weight loss and most MASLD parameters but may lead to safety concerns. The weight change of HEC-C052 with the lowest GCG agonism was inferior to that of selective GLP-1 receptor agonist (GLP-1RA) semaglutide in DIO model mice. The GLP-1R selectivity of HEC-C070 with moderate GCG agonism has a significant effect on weight loss and liver function in obese mice, and its lowest observed adverse effect level (LOAEL) was 30 nmol/kg in the repeat dose toxicity study.

CONCLUSION

We compared the potential of the Fc fusion protein GLP-1/GCG dual receptor agonists with different receptor selectivity to provide the setting for future GLP-1/GCG dual receptor agonists to treat obesity and MASLD.

Glucagon-like peptide-1 analogs: Miracle drugs are blooming?

Glucagon-like peptide-1 (GLP-1), secreted by L cells in the small intestine, assumes a central role in managing type 2 diabetes mellitus (T2DM) and obesity. Its influence on insulin secretion and gastric emptying positions it as a therapeutic linchpin. However, the limited applicability of native GLP-1 stems from its short half-life, primarily due to glomerular filtration and the inactivating effect of dipeptidyl peptidase-IV (DPP-IV). To address this, various structural modification strategies have been developed to extend GLP-1's half-life. Despite the commendable efficacy displayed by current GLP-1 receptor agonists, inherent limitations persist. A paradigm shift emerges with the advent of unimolecular multi-agonists, such as the recently introduced tirzepatide, wherein GLP-1 is ingeniously combined with other gastrointestinal hormones. This novel approach has captured the spotlight within the diabetes and obesity research community. This review summarizes the physiological functions of GLP-1, systematically explores diverse structural modifications, delves into the realm of unimolecular multi-agonists, and provides a nuanced portrayal of the developmental prospects that lie ahead for GLP-1 analogs.

Newer pharmacological interventions directed at gut hormones for obesity

The objective is to review the newer pharmacological interventions for obesity, specifically single, dual and triple incretin receptor agonists that are either available or in the pipeline for treatment of obesity. The three incretin receptor targets are glucagon like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP) and glucagon. There are several approved single or dual incretin agonists which can be administered subcutaneously daily (e.g., liraglutide) or weekly (e.g., semaglutide, dulaglutide, and exenatide QW), and other experimental dual or triple incretin agonists. Analogues of amylin, peptide YY and oxyntomodulin, as well as the combination of a GLP1R agonist and GIPR antagonist also are in development. Oral semaglutide (administered daily) is approved for type 2 diabetes mellitus and is on track for regulatory review for obesity. The review includes specifically perspectives on the effects of these mechanisms and pharmacological agents on gastric emptying, which contribute to satiation and weight loss, in addition to the established evidence on effects on central mechanisms controlling appetite. In the future, it is anticipated that small molecule GLP-1 receptor agonists (e.g., oral danuglipron) will be developed for treating obesity. These pharmacological agents are having significant impact on glycaemic control and obesity and on their co-morbidities.

Hormone-based pharmacotherapy for metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) has reached epidemic proportions globally in parallel to the rising prevalence of obesity. Despite its significant burden, there is no approved pharmacotherapy specifically tailored for this disease. Many potential drug candidates for MAFLD have encountered setbacks in clinical trials, due to safety concerns or/and insufficient therapeutic efficacy. Nonetheless, several investigational drugs that mimic the actions of endogenous metabolic hormones, including thyroid hormone receptor β (THRβ) agonists, fibroblast growth factor 21 (FGF21) analogues, and glucagon-like peptide-1 receptor agonists (GLP-1RAs), showed promising therapeutic efficacy and excellent safety profiles. Among them, resmetirom, a liver-targeted THRβ-selective agonist, has met the primary outcomes in alleviation of metabolic dysfunction-associated steatohepatitis (MASH), the advanced form of MAFLD, and liver fibrosis in phase-3 clinical trials. These hormone-based pharmacotherapies not only exhibit varied degrees of therapeutic efficacy in mitigating hepatic steatosis, inflammation and fibrosis, but also improve metabolic profiles. Furthermore, these three hormonal agonists/analogues act in a complementary manner to exert their pharmacological effects, suggesting their combined therapies may yield synergistic therapeutic benefits. Further in-depth studies on the intricate interplay among these metabolic hormones are imperative for the development of more efficacious combination therapies, enabling precision management of MAFLD and its associated comorbidities.

Glucagon-like Peptide 1, Glucose-Dependent Insulinotropic Polypeptide, and Glucagon Receptor Agonists in Metabolic Dysfunction-Associated Steatotic Liver Disease: Novel Medication in New Liver Disease Nomenclature

Glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are incretins that regulate postprandial glucose regulation, stimulating insulin secretion from pancreatic β-cells in response to food ingestion. Modified GLP-1 receptor agonists (GLP-1RAs) are being administered for the treatment of obesity and type 2 diabetes mellitus (T2DM). Strongly related to those disorders, metabolic dysfunction-associated steatotic liver disease (MASLD), especially its aggressive form, defined as metabolic dysfunction-associated steatohepatitis (MASH), is a major healthcare burden associated with high morbidity and extrahepatic complications. GLP-1RAs have been explored in MASH patients with evident improvement in liver dysfunction enzymes, glycemic control, and weight loss. Importantly, the combination of GLP-1RAs with GIP and/or glucagon RAs may be even more effective via synergistic mechanisms in amelioration of metabolic, biochemical, and histological parameters of MASLD but also has a beneficial impact on MASLD-related complications. In this current review, we aim to provide an overview of incretins' physiology, action, and signaling. Furthermore, we provide insight into the key pathophysiological mechanisms through which they impact MASLD aspects, as well as we analyze clinical data from human interventional studies. Finally, we discuss the current challenges and future perspectives pertinent to this growing area of research and clinical medicine.

Animal studies on glucagon-like peptide-1 receptor agonists and related polyagonists in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a prevalent metabolic liver disease closely associated with the epidemics of obesity and type 2 diabetes mellitus (T2DM), but without licensed pharmacological treatment to date. As glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) are approved anti-diabetic and anti-obesity medications, they were also considered a potential therapeutic option for NAFLD. Preclinical studies suggest that GLP-1RAs have a beneficial effect on major NAFLD histological outcomes, i.e., hepatic steatosis and inflammation, through multiple intrahepatic mechanisms, including increased fatty acid β-oxidation, activation of autophagy, suppression of inflammation, and oxidative stress. Data on hepatic fibrosis are limited or inconclusive, although some studies reported improvement in indices of fibrosis or prevention of fibrosis initiation or reduction of collagen deposition. Whether the positive impact of GLP-1RAs on hepatic histology is indirect, i.e., through their action on extrahepatic tissues, or whether their action is direct, i.e., through activating GLP-1R on the hepatocytes, is still a controversial issue. Alongside GLP-1RAs, newly emerging peptide polyagonists (i.e., synthetic molecules that combine the amino acid sequences of more than one peptide, thus having the ability to bind more than one receptor) are now being investigated in NAFLD with high expectations. This review summarizes the existing knowledge derived from animal studies on the effects of GLP-1RAs and GLP-1RA related peptide polyagonists on NAFLD in an attempt to illuminate areas of uncertainty and provide the groundwork for future animal and clinical research in the field.

High Doses of Exogenous Glucagon Stimulate Insulin Secretion and Reduce Insulin Clearance in Healthy Humans

Glucagon is generally defined as a counterregulatory hormone with a primary role to raise blood glucose concentrations by increasing endogenous glucose production (EGP) in response to hypoglycemia. However, glucagon has long been known to stimulate insulin release, and recent preclinical findings have supported a paracrine action of glucagon directly on islet β-cells that augments their secretion. In mice, the insulinotropic effect of glucagon is glucose dependent and not present during basal euglycemia. To test the hypothesis that the relative effects of glucagon on hepatic and islet function also vary with blood glucose, a group of healthy subjects received glucagon (100 ng/kg) during fasting glycemia or experimental hyperglycemia (∼150 mg/dL) on 2 separate days. During fasting euglycemia, administration of glucagon caused blood glucose to rise due to increased EGP, with a delayed increase of insulin secretion. When given during experimental hyperglycemia, glucagon caused a rapid, threefold increase in insulin secretion, as well as a more gradual increase in EGP. Under both conditions, insulin clearance was decreased in response to glucagon infusion. The insulinotropic action of glucagon, which is proportional to the degree of blood glucose elevation, suggests distinct physiologic roles in the fasting and prandial states.

ARTICLE HIGHLIGHTS

Dose-response effects on HbA1c and bodyweight reduction of survodutide, a dual glucagon/GLP-1 receptor agonist, compared with placebo and open-label semaglutide in people with type 2 diabetes: a randomised clinical trial

AIMS/HYPOTHESIS

The aim of this study was to assess the dose-response effects of the subcutaneous glucagon receptor/glucagon-like peptide-1 receptor dual agonist survodutide (BI 456906) on HbA1c levels and bodyweight reduction.

METHODS

This Phase II, multicentre, randomised, double-blind, parallel-group, placebo-controlled study, conducted in clinical research centres, assessed survodutide in participants aged 18-75 years with type 2 diabetes, an HbA1c level of 53-86 mmol/mol (7.0-10.0%) and a BMI of 25-50 kg/m2 on a background of metformin therapy. Participants were randomised via interactive response technology to receive survodutide (up to 0.3, 0.9, 1.8 or 2.7 mg once weekly [qw; dose group (DG) 1-4, respectively] or 1.2 or 1.8 mg twice weekly [DG 5 and 6, respectively]), placebo or semaglutide (up to 1.0 mg qw). Participants and all those involved in the trial conduct/analysis were blinded; the semaglutide arm was open-label. The primary endpoint was absolute change from baseline in HbA1c after 16 weeks' treatment. The key secondary endpoint was relative change from baseline in bodyweight after 16 weeks' treatment.

RESULTS

A total of 413 participants were randomised (DG1, n=50; DG2, n=50; DG3, n=52; DG4, n=50; DG5, n=51; DG6, n=50; semaglutide, n=50; placebo, n=60). The full analysis set comprised 411 treated participants (DG6, n=49; placebo, n=59). Adjusted mean (95% CI) HbA1c decreased from baseline (mean ± SD 64.7±9.2 mmol/mol [8.07±0.84%] after 16 weeks' treatment: DG1 (n=41), -9.92 mmol/mol (-12.27, -7.56; -0.91% [-1.12, -0.69]); DG2 (n=46), -15.95 mmol/mol (-18.27, -13.63; -1.46% [-1.67, -1.25]); DG3 (n=36), -18.72 mmol/mol (-21.15, -16.29; -1.71% [-1.94, -1.49]); DG4 (n=33), -17.01 mmol/mol (-19.59, -14.43; -1.56% [-1.79, -1.32]); DG5 (n=44), -17.84 mmol/mol (-20.18, -15.51; -1.63% [-1.85, -1.42]); DG6 (n=36), -18.38 mmol/mol (-20.90, -15.87; -1.68% [-1.91, -1.45]). The mean reduction in HbA1c was similar with low-dose survodutide (DG2: -15.95 mmol/mol [-1.46%]; n=46) and semaglutide (-16.07 mmol/mol [-1.47%]; n=45). Mean (95% CI) bodyweight decreased dose-dependently up to -8.7% (-10.1, -7.3; DG6, n=37); survodutide ≥1.8 mg qw produced greater bodyweight reductions than semaglutide (-5.3% [-6.6, -4.1]; n=45). Adverse events (AEs) were reported for 77.8% of survodutide-treated participants (mainly gastrointestinal), 52.5% receiving placebo and 52.0% receiving semaglutide.

CONCLUSIONS/INTERPRETATION

Survodutide reduced HbA1c levels and bodyweight after 16 weeks' treatment in participants with type 2 diabetes. Dose-related gastrointestinal AEs could be mitigated with slower dose escalations.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04153929 and EudraCT 2019-002390-60.

FUNDING

Boehringer Ingelheim Pharma GmbH & Co. KG, Ingelheim, Germany.

Design and discovery of a highly potent ultralong-acting GLP-1 and glucagon co-agonist for attenuating renal fibrosis

The role of co-agonists of glucagon-like peptide-1 receptor (GLP-1R) and glucagon receptor (GCGR) in chronic kidney disease (CKD) remains unclear. Herein we found that GLP-1R and GCGR expression levels were lower in the kidneys of mice with CKD compared to healthy mice and were correlated with disease severity. Interestingly, GLP-1R or GCGR knockdown aggravated the progression of kidney injury in both diabetic db/db mice and non-diabetic mice undergoing unilateral ureteral obstruction (UUO). Based on the importance of GLP-1R and GCGR in CKD, we reported a novel monomeric peptide, 1907-B, with dual-agonism on both GLP-1R and GCGR. The data confirmed that 1907-B had a longer half-life than long-acting semaglutide in rats or cynomolgus monkeys (∼2-3 fold) and exhibited better therapeutic contribution to CKD than best-in-class monoagonists, semaglutide, or glucagon, in db/db mice and UUO mice. Various lock-of-function models, including selective pharmacological activation and genetic knockdown, confirmed that 1907-B's effects on ameliorating diabetic nephropathy in db/db mice, as well as inhibiting kidney fibrosis in UUO mice, were mediated through GLP-1 and glucagon signaling. These findings highlight that 1907-B, a novel GLP-1R and GCGR co-agonist, exerts multifactorial improvement in kidney injuries and is an effective and promising therapeutic option for CKD treatment.

Recent advances in age-related metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects approximately 25% of the world's population and has become a leading cause of chronic liver disease. In recent years, an increasing amount of data suggests that MASLD is associated with aging. As the population ages, age-related MASLD will become a major global health problem. Targeting an aging will become a new approach to the treatment of MASLD. This paper reviews the current studies on the role of aging-related factors and therapeutic targets in MASLD, including: Oxidative stress, autophagy, mitochondrial homeostasis, bile acid metabolism homeostasis, and dysbiosis. The aim is to identify effective therapeutic targets for age-related MASLD and its progression.

Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) and Thyroid Function in Childhood Obesity: A Vicious Circle?

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a multisystem disorder characterized by the presence of fatty liver degeneration associated with excess adiposity or prediabetes/type 2 diabetes or metabolic dysregulation. An intricate relationship between the liver and thyroid has been reported in both health and disease. Simultaneously, there is a strong correlation between obesity and both MAFLD and thyroid dysfunction. In this narrative review, we highlighted the relationship between MAFLD and thyroid function in children and adolescents with obesity in order to explore how thyroid hormones (THs) act as predisposing factors in the onset, progression, and sustainability of MAFLD. THs are integral to the intricate balance of metabolic activities, ensuring energy homeostasis, and are indispensable for growth and development. Regarding liver homeostasis, THs have been suggested to interact with liver lipid homeostasis through a series of processes, including stimulating the entry of free fatty acids into the liver for esterification into triglycerides and increasing mitochondrial β-oxidation of fatty acids to impact hepatic lipid accumulation. The literature supports a correlation between MAFLD and obesity, THs and obesity, and MAFLD and THs; however, results in the pediatric population are very limited. Even though the underlying pathogenic mechanism involved in the relationship between MAFLD and thyroid function remains not fully elucidated, the role of THs as predisposing factors of MAFLD could be postulated. A potential vicious circle among these three conditions cannot be excluded. Identifying novel elements that may contribute to MAFLD could offer a practical approach to assessing children at risk of developing the condition.

GLP-1 receptor agonists in the treatment of diabetic non-alcoholic steatohepatitis patients

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is the most common hepatic disease affecting almost 30% of the world population. Approximately 25% of people with NAFLD develop nonalcoholic steatohepatitis (NASH), the fulminant version of the disease. Diabetes mellitus is present in 22.5% of people with NAFLD and 44.60% of individuals with NASH. This review was undertaken to examine the current contribution of glucagon-like peptide 1 (GLP-1) receptor agonists to the pharmacotherapy of diabetic nonalcoholic steatohepatitis.

AREAS COVERED

The author analyzed the current status of GLP-1 receptor agonists for pharmacotherapy of diabetic NASH. Research data and literature reports were taken from the database and or websites of Diabetes UK, American Diabetes Association, ClinicalTrials.gov, PubMed, and Scopus. The keywords utilized included type 2 diabetes, GLP-1, NASH, NAFLD, and clinical trials.

EXPERT OPINION

Since diabetic NASH is associated with obesity, diabetes mellitus, oxidative stress and inflammation, drugs capable of mitigating all of these conditions simultaneously, are most ideal for the treatment of diabetic NASH. These drugs include (in order of relevance), GLP-1 receptor agonists, GLP-1 and GIP dual receptor agonists, sodium-glucose co-transporter-2 (SGLT2) inhibitors, and pioglitazone. The future, FDA-approved drug for diabetic NASH treatment will likely be GLP-1 agonist, which could be used as monotherapy or in combination with other drugs.

Liver fibrosis in NAFLD/NASH: from pathophysiology towards diagnostic and therapeutic strategies

Liver fibrosis, as an excess deposition of extracellular matrix (ECM) components, results from chronic liver injury as well as persistent activation of inflammatory response and of fibrogenesis. Liver fibrosis is a major determinant for chronic liver disease (CLD) progression and in the last two decades our understanding on the major molecular and cellular mechanisms underlying the fibrogenic progression of CLD has dramatically improved, boosting pre-clinical studies and clinical trials designed to find novel therapeutic approaches. From these studies several critical concepts have emerged, starting to reveal the complexity of the pro-fibrotic microenvironment which involves very complex, dynamic and interrelated interactions between different hepatic and extrahepatic cell populations. This review will offer first a recapitulation of established and novel pathophysiological basic principles and concepts by intentionally focus the attention on NAFLD/NASH, a metabolic-related form of CLD with a high impact on the general population and emerging as a leading cause of CLD worldwide. NAFLD/NASH-related pro-inflammatory and profibrogenic mechanisms will be analysed as well as novel information on cells, mediators and signalling pathways which have taken advantage from novel methodological approaches and techniques (single cell genomics, imaging mass cytometry, novel in vitro two- and three-dimensional models, etc.). We will next offer an overview on recent advancement in diagnostic and prognostic tools, including serum biomarkers and polygenic scores, to support the analysis of liver biopsies. Finally, this review will provide an analysis of current and emerging therapies for the treatment of NAFLD/NASH patients.

OXM-104, a potential candidate for the treatment of obesity, NASH and type 2 diabetes

OBJECTIVE

Dual glucagon-like peptide-1 (GLP-1) and glucagon receptor agonists are therapeutic agents with an interesting liver-specific mode of action suitable for metabolic complications. In this study, dual GLP-1 and glucagon receptor agonist OXM-104 is compared head-to-head with the once-daily dual GLP-1 and glucagon receptor agonist cotadutide and GLP-1 receptor agonist semaglutide to explore the metabolic efficacy of OXM-104.

METHODS

The in vitro potencies of OXM-104, cotadutide and semaglutide were assessed using reporter assays. In addition, in vivo efficacy was investigated using mouse models of diet-induced obesity (DIO mice), diabetes (db/db mice) and diet-induced NASH mice (MS-NASH).

RESULTS

OXM-104 was found to only activate the GLP-1 and glucagon with no cross-reactivity at the (GIP) receptor. Cotadutide was also found to activate the GLP-1 and glucagon receptors, whereas semaglutide only showed activity at the GLP-1 receptor. OXM-104, cotadutide, and semaglutide elicited marked reductions in body weight and improved glucose control. In contrast, hepatoprotective effects, i.e., reductions in steatosis and fibrosis, as well as liver fibrotic biomarkers, were more prominent with OXM-104 and cotadutide than those seen with semaglutide, demonstrated by an improved NAFLD activity score (NAS) by OXM-104 and cotadutide, underlining the importance of the glucagon receptor.

CONCLUSION

These results show that dual GLP-1 and glucagon receptor agonism is superior to GLP-1 alone. OXM-104 was found to be a promising therapeutic candidate for the treatment of metabolic complications such as obesity, type 2 diabetes and NASH.

Perspectives in weight control in diabetes - Survodutide

Glucagon-like peptide-1 receptor (GLP-1R) agonists are approved treatments for Type 2 diabetes mellitus, with liraglutide and semaglutide also approved for the treatment of obesity. The natural gut hormone oxyntomodulin is a weak dual agonist of the glucagon receptor (GCGR) and GLP-1R. Development of poly-agonists mimicking oxyntomodulin, such as the novel dual GCGR/GLP-1R agonist survodutide, represents an important step towards a more effective treatment for people with Type 2 diabetes mellitus and obesity. Survodutide is a 29-amino acid peptide derived from glucagon, with the incorporation of potent GLP-1 activities. It contains a C18 diacid which mediates binding to albumin, thereby prolonging the half-life to enable once-weekly subcutaneous dosing. The utilisation of GCGR agonism aims to enhance body weight-lowering effects by increasing energy expenditure in addition to the anorectic action of GLP-1R agonists. Glucose-lowering efficacy of survodutide has been demonstrated in a Phase II trial in patients with Type 2 diabetes mellitus and obesity and was associated with clinically meaningful body weight loss. These data highlight the potential of dual GCGR/GLP-1R agonism for reducing glycated haemoglobin and body weight in patients with Type 2 diabetes mellitus, and for greater therapeutic efficacy compared with GLP-1R agonism alone.

Potential therapeutic targets for nonalcoholic fatty liver disease: Glucagon-like peptide 1

Nonalcoholic fatty liver disease (NAFLD) is the most rapidly growing contributor to liver mortality and morbidity. Hepatocellular injury in nonalcoholic steatohepatitis (NASH) is caused by an increase in metabolic substrates (glucose, fructose, and fatty acids), leading fatty acids to participate in pathways that cause cellular injury and a poor response to injury. The pathogenesis of this disease is largely associated with obesity, type 2 diabetes, and increasing age. To date, there are no Food and Drug Administration-approved treatments for NAFLD/NASH or its associated fibrosis. Since one of the pathogenic drivers of NASH is insulin re-sistance, therapies approved for the treatment of type 2 diabetes are being evaluated in patients with NASH. Currently, the glucagon-like peptide-1 receptor agonist (GLP-1RA) semaglutide is a safe, well-studied therapeutic for NAFLD/ NASH patients. Existing research demonstrates that semaglutide can increase the resolution of NASH but not improve fibrosis. However, improving the fibrosis of NAFLD is the only way to improve the long-term prognosis of NAFLD. Given the complex pathophysiology of NASH, combining therapies with complementary mechanisms may be beneficial. Researchers have conducted trials of semaglutide in combination with antifibrotic drugs. However, the results have not fully met expectations, and it cannot be ruled out that the reason is the short trial time. We should continue to pay increasing attention to GLP-1RAs.

What Does Sarcopenia Have to Do with Nonalcoholic Fatty Liver Disease?

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease. As the second stage of developing steatosis, nonalcoholic hepatitis (NASH) carries the risk of fibrosis, cirrhosis, and hepatocellular carcinoma. Sarcopenia is defined as a condition characterized by a decrease in muscle mass and functional decline. Both NAFLD and sarcopenia are global problems. The pathophysiological mechanisms that link the two entities of the disease are insulin resistance, inflammation, nutritional deficiencies, impairment of myostatin and adiponectin, or physical inactivity. Furthermore, disorders of the gut-liver axis appear to induce the process of developing NAFLD and sarcopenia. The correlations between NAFLD and sarcopenia appear to be bidirectional, so the main objective of the review was to determine the cause-and-effect relationship between the two diseases.

Incretins (GLP-1 receptor agonists and dual/triple agonists) and the liver

The principle pathological drivers of metabolic dysfunction-associated steatohepatitis (MASH) are obesity and associated insulin resistance, rendering them key therapeutic targets. As glucagon-like peptide 1 receptor agonists (GLP-1RAs) have been licensed for the treatment of diabetes and obesity, they were one of the first drug types to be evaluated in patients with MASH, and successful phase IIa and IIb studies have resulted in progression to phase III clinical trials. Alongside GLP-1RAs, newer combinations with glucagon agonists and/or glucose-dependent insulinotropic peptide (GIP) agonists have been explored in related patient groups, with evidence of improvements in weight, insulin resistance and non-invasive liver parameters. Whether GLP-1RAs have direct, independent effects on MASH or whether they impact on pathophysiology through improvements in weight, insulin resistance and glycaemic control remains a matter of debate. Combinations are being explored, although the potential improvement in efficacy will need to be weighed against the cumulative side-effect burden, potential drug-drug interactions and costs. There is also uncertainty regarding the optimal ratio of glucagon and GIP agonism to GLP-1 agonism in combination agents, and as to whether GIP agonism or antagonism is the optimal approach. Finally, there are also multiple hypothetical permutations combining gut hormone agonists with other emerging assets in the field. Given that the likely dominant mode of action of gut hormone agonists is upstream on weight, initial combinations might focus on agents which have been shown to have a more direct effect on fibrosis, which would include FGF21 and pan-PPAR agonists.

Cotadutide promotes glycogenolysis in people with overweight or obesity diagnosed with type 2 diabetes

Cotadutide is a dual glucagon-like peptide 1 and glucagon receptor agonist under development for the treatment of non-alcoholic steatohepatitis and type 2 diabetes mellitus (T2DM) and chronic kidney disease. Non-alcoholic steatohepatitis is a complex disease with no approved pharmacotherapies, arising from an underlying state of systemic metabolic dysfunction in association with T2DM and obesity. Cotadutide has been shown to improve glycaemic control, body weight, lipids, liver fat, inflammation and fibrosis. We conducted a two-part, randomized phase 2a trial in men and women with overweight or obesity diagnosed with T2DM to evaluate the efficacy and safety of cotadutide compared with placebo and liraglutide. The primary endpoints were change from baseline to day 28 of treatment in postprandial hepatic glycogen (part A) and to day 35 of treatment in fasting hepatic glycogen (part B) with cotadutide versus placebo. Secondary endpoints in part B were changes in fasting hepatic glycogen with cotadutide versus the mono glucagon-like peptide 1 receptor agonist, liraglutide, and change in hepatic fat fraction. The trial met its primary endpoint. We showed that cotadutide promotes greater reductions in liver glycogen and fat compared with placebo and liraglutide. Safety and tolerability findings with cotadutide were comparable to those of previous reports. Thus, this work provides evidence of additional benefits of cotadutide that could be attributed to glucagon receptor engagement. Our results suggest that cotadutide acts on the glucagon receptor in the human liver to promote glycogenolysis and improve the metabolic health of the liver. ClinicalTrials.gov registration: NCT03555994 .

Obeticholic acid treatment of mice to promote fertilization and reproduction

Obeticholic acid (OCA), a farnesoid X receptor (FXR) agonist, has been demonstrated to ameliorate the histopathological characteristics of liver damage. Nonetheless, the systemic safety profile of OCA with regard to reproduction and development remains poorly understood. In the present study, we conducted a dose-response experiment by administering OCA at doses of 5 mg/kg, 10 mg/kg, or 20 mg/kg through tube feeding to investigate its effect on reproductive development and fertilization rate in both male and female mice. Furthermore, we evaluated the levels of protein and mitochondrial function in the placenta through western blot, qPCR, and scanning electron microscopy. The results showed that 10 mg/kg and 20 mg/kg OCA doses significantly reduced the rate of placental implantation (P < 0.05). Also, OCA increased maternal body weight. In addition, OCA increased levels of FXR and TGR5 and produced changes in oxidative stress levels (P < 0.05). Mitochondrial activity result found that 10 mg/kg and 20 mg/kg of OCA significantly reduced the mitophagy autosomes/nucleus compared with the normal control group (P < 0.05). What is more, there was no significant difference in sperm count after OCA intervention in either C57BL/10 mice or BALB/c mice. Overall, we demonstrated that OCA treatment protected against placental implantation by suppressing placental oxidative stress and mitochondrial activity.

[Smeglutide inhibits high glucose-induced proliferation of myocardial fibroblasts by downregulating TGFβ/Smad3 signaling]

OBJECTIVE

To investigate the effect of semaglutide on high glucose-induced proliferation of cardiac fibroblasts (CFs) and explore its possible mechanism.

METHODS

Primary mouse CFs, identified by detecting vimentin expression, were stimulated with 25 mmol/L and treated with 5-20 nmol/L semaglutide, and the cell proliferation was examined with CKK-8 assay for concentration screening.Cultured CFs exposed to high glucose (25 mmol/L) were treated with 5 nmol/L semaglutide, and the changes in cell cycle were detected using Cell Cycle Staining Kit; The mRNA expressions of α-smooth muscle actin (α-SMA), transforming growth factor-β1(TGF-β1) and Smad3 were detected using RT-qPCR, and the levels of type Ⅰ collagen (CoLⅠ) and type Ⅲ collagen (CoLIII) in the cell cultures were determined with ELISA.

RESULTS

Compared with the control cells, the CFs cultured in high glucose exhibited significantly enhanced proliferative activity (P<0.05) with increased percentage of S-phase cells.Semagutide treatment obviously inhibited high glucose-induced proliferation of the CFs (P<0.05) and reduced the percentage of S-phase cells.High glucose stimulation significantly increased the mRNA expressions of α-SMA, CoL Ⅰ and CoLIII in the cells (P<0.01), which were effectively lowered by semaglutide treatment (P<0.01).The expressions of TGF-β1 and Smad3 were significantly increased in high glucose-stimulated CFs (P<0.01) and were lowered by semaglutide treatment (P<0.01).

CONCLUSION

Semaglutide can inhibit high glucose-induced proliferation and collagen synthesis in mouse CFs possibly by downregulating the TGFβ/Smad3 signaling pathway.

The Novel Tetra-Specific Drug C-192, Conjugated Using UniStac, Alleviates Non-Alcoholic Steatohepatitis in an MCD Diet-Induced Mouse Model

Non-alcoholic steatohepatitis (NASH) is a complex disease resulting from chronic liver injury associated with obesity, type 2 diabetes, and inflammation. Recently, the importance of developing multi-target drugs as a strategy to address complex diseases such as NASH has been growing; however, their manufacturing processes remain time- and cost-intensive and inefficient. To overcome these limitations, we developed UniStac, a novel enzyme-mediated conjugation platform for multi-specific drug development. UniStac demonstrated high conjugation yields, optimal thermal stabilities, and robust biological activities. We designed a tetra-specific compound, C-192, targeting glucagon-like peptide 1 (GLP-1), glucagon (GCG), fibroblast growth factor 21 (FGF21), and interleukin-1 receptor antagonist (IL-1RA) simultaneously for the treatment of NASH using UniStac. The biological activity and treatment efficacy of C-192 were confirmed both in vitro and in vivo using a methionine-choline-deficient (MCD) diet-induced mouse model. C-192 exhibited profound therapeutic efficacies compared to conventional drugs, including liraglutide and dulaglutide. C-192 significantly improved alanine transaminase levels, triglyceride accumulation, and the non-alcoholic fatty liver disease activity score. In this study, we demonstrated the feasibility of UniStac in creating multi-specific drugs and confirmed the therapeutic potential of C-192, a drug that integrates multiple mechanisms into a single molecule for the treatment of NASH.

Nonalcoholic fatty liver disease: Current therapies and future perspectives in drug delivery

Nonalcoholic fatty liver disease (NAFLD) affects approximately 25% of the adult population worldwide. This pathology can progress into end-stage liver disease with life-threatening complications, and yet no pharmacologic therapy has been approved. NAFLD is commonly characterized by excessive fat accumulation in the liver and is in closely associated with insulin resistance and metabolic disorders, which suggests that NAFLD is the hepatic manifestation of metabolic syndrome. Regarding treatment options, the current validated strategy relies on lifestyle modifications (exercise and diet restrictions). Although there are no approved drug-based treatments, several clinical trials are ongoing. Novel targets are being discovered, and the repurposing of drugs that show promising effects in NAFLD is starting to gain more interest. The field of nanotechnology has been growing at an increasing rate, with new and more efficient drug delivery strategies being developed for NAFLD treatment. Nanocarriers can easily encapsulate drugs that need to be better protected from the organism to exert their effect or that need help at reaching their target, thereby helping achieve a better bioavailability. Drug delivery systems can also be designed to target the site of the disease, in this case, the liver. In this review, we focus on the current knowledge of NAFLD pathology, the targets being considered for clinical trials, and the current guidelines and ongoing clinical trials, with a specific focus on potential oral treatments for NAFLD using promising drug delivery strategies.

A phase IIa active-comparator-controlled study to evaluate the efficacy and safety of efinopegdutide in patients with non-alcoholic fatty liver disease

BACKGROUND & AIMS

This study assessed the effects of the glucagon-like peptide-1 (GLP-1)/glucagon receptor co-agonist efinopegdutide relative to the selective GLP-1 receptor agonist semaglutide on liver fat content (LFC) in patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

This was a phase IIa, randomized, active-comparator-controlled, parallel-group, open-label study. A magnetic resonance imaging-estimated proton density fat fraction assessment was performed to determine LFC at screening and Week 24. Participants with an LFC of ≥10% at screening were randomized 1:1 to efinopegdutide 10 mg or semaglutide 1 mg, both administered subcutaneously once weekly for 24 weeks. Participants were stratified according to the concurrent diagnosis of type 2 diabetes mellitus (T2DM). Both drugs were titrated to the target dose over an 8-week time period. The primary efficacy endpoint was relative reduction from baseline in LFC (%) after 24 weeks of treatment.

RESULTS

Among 145 randomized participants (efinopegdutide n = 72, semaglutide n = 73), 33.1% had T2DM. At baseline, mean BMI was 34.3 kg/m2 and mean LFC was 20.3%. The least squares (LS) mean relative reduction from baseline in LFC at Week 24 was significantly (p <0.001) greater with efinopegdutide (72.7% [90% CI 66.8-78.7]) than with semaglutide (42.3% [90% CI 36.5-48.1]). Both treatment groups had an LS mean percent reduction from baseline in body weight at Week 24 (efinopegdutide 8.5% vs. semaglutide 7.1%; p = 0.085). Slightly higher incidences of adverse events and drug-related adverse events were observed in the efinopegdutide group compared with the semaglutide group, primarily related to an imbalance in gastrointestinal adverse events.

CONCLUSIONS

In patients with NAFLD, treatment with efinopegdutide 10 mg weekly led to a significantly greater reduction in LFC than semaglutide 1 mg weekly.

CLINICAL TRIAL NUMBER

EudraCT: 2020-005136-30; NCT: 04944992.

IMPACT AND IMPLICATIONS

Currently, there are no approved therapies for non-alcoholic steatohepatitis (NASH). The weight loss associated with glucagon-like peptide-1 (GLP-1) receptor agonists has been shown to decrease hepatic inflammation in patients with NASH. In addition to reducing liver fat content (LFC) indirectly through weight loss, glucagon receptor agonism may also reduce LFC by acting on the liver directly to stimulate fatty acid oxidation and reduce lipogenesis. This study demonstrated that treatment of patients with non-alcoholic fatty liver disease with the GLP-1/glucagon receptor co-agonist efinopegdutide (10 mg weekly) led to a significantly greater reduction in LFC compared to treatment with the GLP-1 receptor agonist semaglutide (1 mg weekly), suggesting that efinopegdutide may be an effective treatment for NASH.

Mitochondrial oxidative stress regulates LonP1-TDP-43 pathway and rises mitochondrial damage in carbon tetrachloride-induced liver fibrosis

Carbon tetrachloride (CCl4)-mediated liver damage has been well recognized, but the sources and mechanisms of mitochondrial damage during this progress still remain poorly understood. Accumulating evidence has revealed that LonP1-TDP-43 pathway affect proper mitochondrial integrity and function in neurodegenerative diseases. The current study aims to investigate whether mitochondrial oxidative stress regulate LonP1-TDP-43 pathway and the possible roles of this pathway in CCl4-driven liver fibrosis. We found that TDP-43 interacted with LonP1 in chronic CCl4 exposure-induced hepatic fibrogenesis. Moreover, CCl4 led to deficiency of LonP1 and excessive accumulation of TDP-43 on mitochondria. Particularly, the gene correlation analysis for liver fibrosis patients RNA sequencing (RNA-seq) results (GSE159676) showed an obvious negative correlation between LonP1 and TDP-43. By contrast, MitoQ enhanced the occurrence of mitochondrial unfolded protein response (mtUPR), especially the activation of LonP1 after CCl4 treatment. Importantly, mitochondrial antioxidant also promoted the degradation of TDP-43 and alleviated mitochondrial damage. In addition, our results showed that CCl4 induced the release of mitochondrial DNA (mtDNA) and effectively elevated cGAS-STING-mediated immune response, which can be inhibited by MitoQ. Finally, MitoQ prevented CCl4-induced liver fibrosis. Together, our study revealed that LonP1-TDP-43 pathway mediated by mitochondrial oxidative stress participated in the progress of CCl4-drived liver fibrosis. Therefore, mitigating or reversing mitochondrial damage through targeting LonP1-TDP-43 pathway may serve as a promising therapeutic strategy for CCl4 exposure-induced liver diseases.

Synergistic Combinations of Gut- and Pancreas-Hormone-Based Therapies: Advancements in Treatments for Metabolic Diseases

Metabolic diseases, such as obesity, type 2 diabetes mellitus (T2DM), cardiovascular disease, and liver disease, have become increasingly prevalent around the world. As an alternative to bariatric surgery, glucagon-like peptide 1 (GLP-1) receptor agonists have been at the forefront of weight loss medication to combat these metabolic complications. Recently, there has been an exciting rapid emergence of new weight loss medications that combine GLP-1 receptor (GLP-1R) agonists with other gut- and pancreatic-derived hormones, such as glucose-dependent insulinotropic polypeptide (GIP) and glucagon (GCG) receptor agonists. Dual-agonist (GLP-1/GIP and GLP-1/GCG) and tri-agonist (GLP-1/GIP/GCG) administration generally result in greater weight loss, reduction of blood sugar and lipid levels, restoration of tissue function, and improvement in whole-body substrate metabolism compared to when GLP-1R agonists are used alone. The aim of this review is to summarize the recent literature of both preclinical and clinical studies on how these emerging gut-peptide therapies further improve weight loss and metabolic health outcomes for various metabolic diseases.

Combination of an ACLY inhibitor with a GLP-1R agonist exerts additive benefits on nonalcoholic steatohepatitis and hepatic fibrosis in mice

Increased liver de novo lipogenesis (DNL) is a hallmark of nonalcoholic steatohepatitis (NASH). A key enzyme controlling DNL upregulated in NASH is ATP citrate lyase (ACLY). In mice, inhibition of ACLY reduces liver steatosis, ballooning, and fibrosis and inhibits activation of hepatic stellate cells. Glucagon-like peptide-1 receptor (GLP-1R) agonists lower body mass, insulin resistance, and steatosis without improving fibrosis. Here, we find that combining an inhibitor of liver ACLY, bempedoic acid, and the GLP-1R agonist liraglutide reduces liver steatosis, hepatocellular ballooning, and hepatic fibrosis in a mouse model of NASH. Liver RNA analyses revealed additive downregulation of pathways that are predictive of NASH resolution, reductions in the expression of prognostically significant genes compared with clinical NASH samples, and a predicted gene signature profile that supports fibrosis resolution. These findings support further investigation of this combinatorial therapy to treat obesity, insulin resistance, hypercholesterolemia, steatohepatitis, and fibrosis in people with NASH.

Computational Peptide Design Cotargeting Glucagon and Glucagon-like Peptide-1 Receptors

Peptides are sustainable alternatives to conventional therapeutics for G protein-coupled receptor (GPCR) linked disorders, promising biocompatible and tailorable next-generation therapeutics for metabolic disorders including type-2 diabetes, as agonists of the glucagon receptor (GCGR) and the glucagon-like peptide-1 receptor (GLP-1R). However, single agonist peptides activating GLP-1R to stimulate insulin secretion also suppress obesity-linked glucagon release. Hence, bioactive peptides cotargeting GCGR and GLP-1R may remediate the blood glucose and fatty acid metabolism imbalance, tackling both diabetes and obesity to supersede current monoagonist therapy. Here, we design and model optimized peptide sequences starting from peptide sequences derived from earlier phage-displayed library screening, identifying those with predicted molecular binding profiles for dual agonism of GCGR and GLP-1R. We derive design rules from extensive molecular dynamics simulations based on peptide-receptor binding. Our newly designed coagonist peptide exhibits improved predicted coupled binding affinity for GCGR and GLP-1R relative to endogenous ligands and could in the future be tested experimentally, which may provide superior glycemic and weight loss control.