Lithocholic Acid-Based Peptide Delivery System for an Enhanced Pharmacological and Pharmacokinetic Profile of Xenopus GLP-1 Analogs

A lipid nanoparticle platform incorporating trehalose glycolipid for exceptional mRNA vaccine safety

The rapid development of messenger RNA (mRNA) vaccines formulated with lipid nanoparticles (LNPs) has contributed to control of the COVID-19 pandemic. However, mRNA vaccines have raised concerns about their potential toxicity and clinical safety, including side effects, such as myocarditis, anaphylaxis, and pericarditis. In this study, we investigated the potential of trehalose glycolipids-containing LNP (LNP S050L) to reduce the risks associated with ionizable lipids. Trehalose glycolipids can form hydrogen bonds with polar biomolecules, allowing the formation of a stable LNP structure by replacing half of the ionizable lipids. The efficacy and safety of LNP S050L were evaluated by encapsulating the mRNA encoding the luciferase reporter gene and measuring gene expression and organ toxicity, respectively. Furthermore, mice immunized with an LNP S050L-formulated mRNA vaccine expressing influenza hemagglutinin exhibited a significant reduction in organ toxicity, including in the heart, spleen, and liver, while sustaining gene expression and immune efficiency, compared to conventional LNPs (Con-LNPs). Our findings suggest that LNP S050L, a trehalose glycolipid-based LNP, could facilitate the development of safe mRNA vaccines with improved clinical safety.

Ribosomal Incorporation of Lithocholic Acid into Peptides for the De Novo Discovery Of Peptide-Lithocholic Acid Hybrid Macrocyclic Peptides

Peptide-bile acid hybrids offer promising drug candidates due to enhanced pharmacological properties, such as improved protease resistance and oral bioavailability. However, it remains unknown whether bile acids can be incorporated into peptide chains by the ribosome to produce a peptide-bile acid hybrid macrocyclic peptide library for target-based de novo screening. In this study, we achieved the ribosomal incorporation of lithocholic acid (LCA)-d-tyrosine into peptide chains. This led to the construction of a peptide-LCA hybrid macrocyclic peptide library, which enabled the identification of peptides TP-2C-4L3 (targeting Trop2) and EP-2C-4L5 (targeting EphA2) with strong binding affinities. Notably, LCA was found to directly participate in binding to EphA2 and confer on the peptides improved stability and resistance to proteases. Cell staining experiments confirmed the high specificity of the peptides for targeting Trop2 and EphA2. This study highlights the benefits of LCA in peptides and paves the way for de novo discovery of stable peptide-LCA hybrid drugs.

The Effect of Lithocholic Acid on the Gut-Liver Axis

Lithocholic acid (LCA) is a monohydroxy bile acid produced by intestinal flora, which has been found to be associated with a variety of hepatic and intestinal diseases. LCA is previously considered to be toxic, however, recent studies revealed that LCA and its derivatives may exert anti-inflammatory and anti-tumor effects under certain conditions. LCA goes through enterohepatic circulation along with other bile acids, here, we mainly discuss the effects of LCA on the gut-liver axis, including the regulation of gut microbiota, intestinal barrier, and relevant nuclear receptors (VDR, PXR) and G protein-coupled receptor five in related diseases. In addition, we also find that some natural ingredients are involved in regulating the detoxification and excretion of LCA, and the interaction with LCA also mediates its own biological activity.

Stapled, Long-Acting Xenopus GLP-1-Based Dual GLP-1/Glucagon Receptor Agonists with Potent Therapeutic Efficacy for Metabolic Disease

Novel peptidic glucagon receptor (GCGR) and glucagon-like peptide 1 receptor (GLP-1R) dual agonists are reported to have increased efficacy over GLP-1R monoagonists for the treatment of diabetes and obesity. We identified a novel Xenopus GLP-1-based dual GLP-1R/GCGR agonist (xGLP/GCG-13) designed with a proper activity ratio favoring the GLP-1R versus the GCGR. However, the clinical utility of xGLP/GCG-13 is limited by its short in vivo half-life. Starting from xGLP/GCG-13, dual Cys mutation was performed, followed by covalent side-chain stapling and serum albumin binder incorporation, resulting in a stabilized secondary structure, enhanced agonist potency at GLP-1R and GCGR, and improved stability. The lead peptide 2c (stapled xGLP/GCG-13 analogue with a palmitic acid albumin binder) exhibits balanced GLP-1R and GCGR activations and potent, long-lasting effects on in vivo glucose control. 2c was further explored pharmacologically in diet-induced obesity and db/db rodent models. Chronic administration of 2c potently induced body weight loss and hypoglycemic effects, improved glucose tolerance, increased energy expenditure, and normalized lipid metabolism and adiposity in relevant animal models. These results indicated that 2c has potential for development as a novel antidiabetic and/or antiobesity drug. Furthermore, we propose that the incorporation of a proper serum protein-binding motif into a di-Cys staple is an effective method for improving the stabilities and bioactivities of peptides. This approach is likely applicable to other therapeutic peptides, such as glucose-dependent insulin-tropic peptide receptor (GIPR) and GLP-1R dual agonists or GLP-1R/GCGR/GIPR triagonists.

Design of novel Xenopus GLP-1-based dual glucagon-like peptide 1 (GLP-1)/glucagon receptor agonists

Dual activation of the glucagon receptor (GCGR) and glucagon-like peptide 1 receptor (GLP-1R) has the potential to lead to an effective therapy for the treatment of diabetes and obesity. Here, we report the discovery of a series of peptides with dual activity on GLP-1R and GCGR that were discovered by rational design. Structural elements of oxyntomodulin (OXM), glucagon or exendin-4 were engineered into the selective GLP-1R agonist Xenopus GLP-1 (xGLP-1) on the basis of sequence analysis, resulting in hybrid peptides with potent dual activity at GLP-1R and GCGR. Further modifications with fatty acid resulted in a novel metabolically stable peptide (xGLP/GCG-15) with enhanced and balanced GLP-1R and GCGR activations. This lead peptide was further explored pharmacologically in both db/db and diet-induced obesity (DIO) rodent models. Chronic administration of xGLP/GCG-15 significantly induced hypoglycemic effects and body weight loss, improved glucose tolerance, and normalized lipid metabolism, adiposity, and liver steatosis in relevant rodent models. These preclinical studies suggest that xGLP/GCG-15 has potential for development as a novel anti-obesity and/or anti-diabetic candidate. Considering the equal effects of xGLP/GCG-15 and the clinical candidate MEDI0382 on reverse hepatic steatosis, it may also be explored as a new therapy for nonalcoholic steatohepatitis (NASH) in the future.

Stapled and Xenopus Glucagon-Like Peptide 1 (GLP-1)-Based Dual GLP-1/Gastrin Receptor Agonists with Improved Metabolic Benefits in Rodent Models of Obesity and Diabetes

Diabetes is characterized by pancreas dysfunction and is commonly associated with obesity. Hypoglycemic agents capable of improving β-cell function and reducing body weight therefore are gaining increasing interest. Though glucagon-like peptide 1 receptor (GLP-1R)/cholecystokinin 2 receptor (CCK-2R) dual agonist ZP3022 potently increases β-cell mass and improves glycemic control in diabetic db/db mice, the in vivo half-life (t_1/2) is short, and its body weight reducing activity is limited. Here, we report the discovery of a series of novel GLP-1R/CCK-2R dual agonists. Starting from Xenopus GLP-1, dual cysteine mutation was conducted followed by covalent side chain stapling and albumin binder incorporation, resulting in a stabilized secondary structure, increased agonist potency, and improved stability. Further C-terminal conjugation of gastrin-6 generated GLP-1R/CCK-2R dual agonists, among which 6a and 6b showed higher stability and hypoglycemic activity than liraglutide and ZP3022. Desirably, 6a and 6b exhibited prominent metabolic benefits in diet-induced obesity mice without causing nausea responses and exerted considerable effects on β-cell restoration in db/db mice. These preclinical studies suggest the potential role of GLP-1R/CCK-2R dual agonists as effective agents for treating diabetes and related metabolic disorders.

Discovery of lixisenatide analogues as long-acting hypoglycemic agents using novel peptide half-life extension technology based on mycophenolic acid

Noncovalent binding of peptides to human serum albumin protects against renal clearance and enzymatic degradation. Herein, we investigated the effect of mycophenolic acid (MPA) albumin binders for improving the stability of peptides. For proof-of-principle, the short acting glucagon-like peptide-1 (GLP-1) receptor agonist lixisenatide was selected and functionalized with different MPA albumin binders. In vitro, all lixisenatide analogues showed well preserved GLP-1 receptor activation potency. High performance affinity chromatography (HPAC) and ultrafiltration analyses indicated that DiMPA was able to confer high albumin affinity to lixisenatide and revealed that affinity is increased for DiMPA modified lixisenatide analogues containing OEG spacers. In db/db mice, the selected peptide 2c showed comparable efficacies to lixisenatide with respect to glucose-lowering and insulinotropic activities. Furthermore, the duration of action of glucose homeostasis of 2c was comparable to semaglutide in db/db mice. Importantly, DiMPA albumin binder did not bring significant toxicity of lixisenatide, as reflected by the comparable toxicity indexes in 2c and semaglutide groups after 2 weeks dosing in normal Kunming mice. Short-term study (21 days) conducted on db/db mice showed the better therapeutic efficacies of 2c than semaglutide on pancreas islets protection. Importantly, in chronic studies (84 days) on db/db mice, 2c exhibited a sustained improvement in glycaemic control, to a greater extent than that of semaglutide. Thus, we propose DiMPA modification as a novel and general method for development of long-acting GLP-1 receptor agonists for type 2 diabetes treatments, and 2c as a promising antidiabetic candidate.

DiMPA albumin binders were effectively applied to lixisenatide to make 2c as a long-acting antidiabetic agent.