Pramlintide in the treatment of diabetes mellitus

Intranasal pramlintide matches intraperitoneal effects on food intake and gastric emptying in mice

PURPOSE

Pramlintide is an amylin analog developed as a complementary treatment for diabetes. However, it requires several subcutaneous injections, reducing patients' adherence. Since the intranasal route might be an alternative for drug administration, we evaluated whether intranasal pramlintide treatment exerts comparable actions with intraperitoneal administration.

METHODS

Adult male Swiss mice were submitted to a refeeding test in a dose-response study with intraperitoneal (PRAM i.p.) or intranasal (PRAM i.n.) pramlintide administration. Intraperitoneal liraglutide served as a positive control (LIRA). Then, the selected dose was administered to analyze gastric emptying after an acute exposure. We also evaluated an 8-day treatment (once daily) to determine food intake and body mass. Blood glucose and plasma triacylglycerides were measured on the euthanasia day.

RESULTS

In the refeeding test, the anorexigenic dose for the PRAM i.p. or LIRA i.p groups was 200 µg/kg and 400 µg/kg, respectively. The PRAM i.n. group (200 µg/kg) exhibited a trend for that. The reduction in gastric emptying occurred for all treated groups compared with their respective controls (vehicle-treated). Neither the PRAM i.p. nor the PRAM i.n. groups exhibited reduced body mass and food intake in the subchronic experiment. No impact on biochemical parameters was observed regardless of the route of pramlintide administration.

CONCLUSION

Although intranasal pramlintide is not comparable in magnitude to intraperitoneal administration at an equivalent administered dose, our evidence corroborates the development of novel intranasal formulations destined to overpass the bioavailability issue and potentially serve as an alternative route.

Intranasal administration of dextran-pramlintide polyelectrolyte complex-coated nanoemulsions improves cognitive impairments in a mouse model of Alzheimer's disease

Nasal delivery has emerged as a non-invasive route to administer drugs for brain delivery. In particular, polyelectrolyte complexes-based nanocarriers have been demonstrated to be advantageous for nasal delivery of peptide drugs and vaccines. Pramlintide (Pram) is a peptide that emerges as a novel neuroprotective strategy to modify the pathogenesis of Alzheimer's disease (AD). In this study, we examined the effects of the intranasal administration of dextran-pramlintide polyelectrolyte complex-coated nanoemulsions (PEC-NEDexS/Pram) in an experimental model of AD induced by intracerebroventricular (i.c.v.) infusion of amyloid-beta (Aβ1-42) peptide in mice. PEC-NEDexS/Pram displayed droplet size lower than 200 nm and a negatively charged surface. The locomotor activity of the animals was not affected by the i.c.v. Aβ1-42 injection or Pram treatment. On the other hand, the intranasal administration of PEC-NEDexS/Pram at a dose of 100 μg/day for 14 consecutive days restored the impairment induced by Aβ1-42 injection in the discriminative learning and the short-term spatial reference memory of mice. However, Pram treatment did not alter the Aβ1-42-induced anhedonic behavior, oxidative stress parameters, or the pre-synaptic SNAP-25 and post-synaptic PSD-95 levels in the hippocampus and prefrontal cortex. These findings indicate cognitive-enhancing properties of intranasal Pram administration in an animal model of AD.

Polypeptides-Based Nanocarriers in Tumor Therapy

Cancer remains a worldwide problem, and new treatment strategies are being actively developed. Peptides have the characteristics of good biocompatibility, strong targeting, functional diversity, modifiability, membrane permeable ability, and low immunogenicity, and they have been widely used to construct targeted drug delivery systems (DDSs). In addition, peptides, as endogenous substances, have a high affinity, which can not only regulate immune cells but also work synergistically with drugs to kill tumor cells, demonstrating significant potential for application. In this review, the latest progress of polypeptides-based nanocarriers in tumor therapy has been outlined, focusing on their applications in killing tumor cells and regulating immune cells. Additionally, peptides as carriers were found to primarily provide a transport function, which was also a subject of interest to us. At the end of the paper, the shortcomings in the construction of peptide nano-delivery system have been summarized, and possible solutions are proposed therein. The application of peptides provides a promising outlook for cancer treatment, and we hope this article can provide in-depth insights into possible future avenues of exploration.

An insight into the pharmacology of cysteine/methionine containing peptide drugs

Since last century, peptides have emerged as potential drugs with >90 FDA approvals for various targets with several in the pipeline. Sulphur, in peptides is present either as thiol (-SH) from Cys or thioether from Met. In this review, all the peptides approved by FDA since 2000 containing sulphur have been included. Among them ∼50 % contains disulphide bridges. This clearly demonstrates the significance of disulphide bonds in peptide drugs. This can be achieved synthetically by using orthogonal protecting groups (PGs) for -SH. These PGs are compatible with Solid Phase Peptide Synthesis (SPPS), which is still the method of choice for peptide synthesis. The orthogonal PGs used for Cys thiol side chain protecting for disulphide bond formation have been included which are currently in use both by academia and industry from small scale to large scale synthesis. In addition, the details of the FDA approved drugs containing Cys and Met (or both) have also been discussed.

Effects of newer-generation anti-diabetics on diabetic retinopathy: a critical review

Diabetic retinopathy (DR) is the leading etiology of blindness in the working population of the USA. Its long-term management relies on effective glycemic control. Seven anti-diabetic classes have been introduced for patients with type 2 diabetes (T2D) in the past two decades, with different glucose-lowering and cardiovascular benefits. Yet, their effects specifically on DR have not been studied in detail. A systematic review of the literature was conducted to investigate this topic, focusing on the available clinical data for T2D. Published studies were evaluated based on their level of statistical evidence, as long as they incorporated at least one endpoint or adverse event pertaining to retinal health. Fifty nine articles met our inclusion criteria and were grouped per anti-diabetic class as follows: alpha-glucosidase inhibitors (1), peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists (8), amylin analogs (1), glucagon-like peptide-1 (GLP-1) receptor agonists (28), dipeptidyl peptidase 4 (DPP-4) inhibitors (9), and sodium glucose co-transporter-2 (SGLT-2) inhibitors (9), plus one retrospective study and two meta-analyses evaluating more than one of the aforementioned anti-diabetic categories. We also reviewed publicly-announced results of trials for the recently-introduced class of twincretins. The available data indicates that most drugs in the newer anti-diabetic classes are neutral to DR progression; however, there are subclasses differences in specific drugs and T2D populations. In particular, there is evidence suggesting there may be worse diabetic macular edema with PPAR-gamma agonists, potential slight DR worsening with semaglutide (GLP-1 receptor agonist), and potential slight increase in the incidence of retinal vein occlusion in elderly and patients with advanced kidney disease receiving SGLT-2 inhibitors. All these warrant further investigation. Longer follow-up and systematic assessment of at least one DR-related endpoint are highly recommended for all future trials in the T2D field, to ultimately address this topic.

Oxidant-modified amylin fibrils and aggregates alter the inflammatory profile of multiple myeloid cell types, but are non-toxic to islet β cells

Diabetes mellitus currently affects ∼10% of the population worldwide, with Type 2 predominating, and this incidence is increasing steadily. Both Type 1 and 2 are complex diseases, involving β-cell death and chronic inflammation, but the pathways involved are unresolved. Chronic inflammation is characterized by increased oxidant formation, with this inducing protein modification, altered function and immunogenicity. Amylin, a peptide hormone co-secreted with insulin by β-cells, has attracted considerable interest for its amyloidogenic properties, however, the effects that oxidants have on amylin aggregation and function are poorly understood. Amylin was exposed in vitro to hypochlorous acid, hydrogen peroxide and peroxynitrous acid/peroxynitrite to investigate the formation of post-translational oxidative modifications (oxPTMs, via mass spectrometry) and fibril formation (via transmission electron microscopy). Amylin free acid (AFA) was also examined to investigate the role of the C-terminal amide in amylin. Oxidant exposure led to changes in aggregate morphology and abundance of oxPTMs in a concentration-dependent manner. The toxicity and immunogenic potential of oxidant-modified amylin or AFA on pancreatic islet cells (INS-1E), human monocyte cell line (THP-1) and monocyte-derived dendritic cells (moDCs) were examined using metabolic activity and cytokine assays, and flow cytometry. No significant changes in vitality or viability were detected, but exposure to oxidant-modified amylin or AFA resulted in altered immunogenicity when compared to the native proteins. THP-1 and moDCs show altered expression of activation markers and changes in cytokine secretion. Furthermore, oxidant-treated amylin and AFA promoted maturation of THP-1 and pre-mature moDCs, as determined by changes in size, and maturation markers.

Recent developments in adjunct therapies for type 1 diabetes

INTRODUCTION

There have been many recent advances in the treatment of type 1 diabetes (T1D) including in insulin formulations, continuous glucose monitoring (CGM) technology and automated insulin delivery. However, long-term optimal glycemic control is still only achieved in a minority.

AREAS COVERED

Adjunct therapy - the use of therapeutic agents other than insulin - is one strategy aimed at improving outcomes. An ideal adjunct agent would improve glycemic control, reduce weight (or weight gain), reduce insulin requirement and prevent complications (e.g. cardiorenal) without increasing hypoglycemia. The amylin analogue pramlintide has been licensed in the USA, while the sodium glucose co-transporter-2 inhibitor (SGLT2i) dapagliflozin, was briefly (2019 - 2021) licensed for type 1 diabetes in Europe and the UK. However, other agents from the type 2 diabetes (T2D) arena including metformin, other SGLT2is, glucagon-like peptide-1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-IV (DPP-4) inhibitors have been investigated.

EXPERT OPINION

As evidence emerges for cardiorenal protection by SGLT2is and GLP-1RAs in T2D, it has become increasingly important to know whether people with T1D can also benefit. Here, we review recent trials of adjunct agents in T1D and discuss the efficacy and safety of these agents (alone and in combination) in an era in which continuous glucose monitoring is becoming standard of care.

New Horizons: Emerging Antidiabetic Medications

Over the past century, since the discovery of insulin, the therapeutic offer for diabetes has grown exponentially, in particular for type 2 diabetes (T2D). However, the drugs in the diabetes pipeline are even more promising because of their impressive antihyperglycemic effects coupled with remarkable weight loss. An ideal medication for T2D should target not only hyperglycemia but also insulin resistance and obesity. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and the new class of GLP1 and gastric inhibitory polypeptide dual RAs counteract 2 of these metabolic defects of T2D, hyperglycemia and obesity, with stunning results that are similar to the effects of metabolic surgery. An important role of antidiabetic medications is to reduce the risk and improve the outcome of cardiovascular diseases, including coronary artery disease and heart failure with reduced or preserved ejection fraction, as well as diabetic nephropathy, as shown by SGLT2 inhibitors. This review summarizes the main drugs currently under development for the treatment of type 1 diabetes and T2D, highlighting their strengths and side effects.

An Overview of Herbal-Based Antidiabetic Drug Delivery Systems: Focus on Lipid- and Inorganic-Based Nanoformulations

Diabetes is a metabolic pathology with chronic high blood glucose levels that occurs when the pancreas does not produce enough insulin or the body does not properly use the insulin it produces. Diabetes management is a puzzle and focuses on a healthy lifestyle, physical exercise, and medication. Thus far, the condition remains incurable; management just helps to control it. Its medical treatment is expensive and is to be followed for the long term, which is why people, especially from low-income countries, resort to herbal medicines. However, many active compounds isolated from plants (phytocompounds) are poorly bioavailable due to their low solubility, low permeability, or rapid elimination. To overcome these impediments and to alleviate the cost burden on disadvantaged populations, plant nanomedicines are being studied. Nanoparticulate formulations containing antidiabetic plant extracts or phytocompounds have shown promising results. We herein aimed to provide an overview of the use of lipid- and inorganic-based nanoparticulate delivery systems with plant extracts or phytocompounds for the treatment of diabetes while highlighting their advantages and limitations for clinical application. The findings from the reviewed works showed that these nanoparticulate formulations resulted in high antidiabetic activity at low doses compared to the corresponding plant extracts or phytocompounds alone. Moreover, it was shown that nanoparticulate systems address the poor bioavailability of herbal medicines, but the lack of enough preclinical and clinical pharmacokinetic and/or pharmacodynamic trials still delays their use in diabetic patients.

MultiPep: a hierarchical deep learning approach for multi-label classification of peptide bioactivities

Peptide-based therapeutics are here to stay and will prosper in the future. A key step in identifying novel peptide-drugs is the determination of their bioactivities. Recent advances in peptidomics screening approaches hold promise as a strategy for identifying novel drug targets. However, these screenings typically generate an immense number of peptides and tools for ranking these peptides prior to planning functional studies are warranted. Whereas a couple of tools in the literature predict multiple classes, these are constructed using multiple binary classifiers. We here aimed to use an innovative deep learning approach to generate an improved peptide bioactivity classifier with capacity of distinguishing between multiple classes. We present MultiPep: a deep learning multi-label classifier that assigns peptides to zero or more of 20 bioactivity classes. We train and test MultiPep on data from several publically available databases. The same data are used for a hierarchical clustering, whose dendrogram shapes the architecture of MultiPep. We test a new loss function that combines a customized version of Matthews correlation coefficient with binary cross entropy (BCE), and show that this is better than using class-weighted BCE as loss function. Further, we show that MultiPep surpasses state-of-the-art peptide bioactivity classifiers and that it predicts known and novel bioactivities of FDA-approved therapeutic peptides. In conclusion, we present innovative machine learning techniques used to produce a peptide prediction tool to aid peptide-based therapy development and hypothesis generation.

Multifactorial Basis and Therapeutic Strategies in Metabolism-Related Diseases

Throughout the 20th and 21st centuries, the incidence of non-communicable diseases (NCDs), also known as chronic diseases, has been increasing worldwide. Changes in dietary and physical activity patterns, along with genetic conditions, are the main factors that modulate the metabolism of individuals, leading to the development of NCDs. Obesity, diabetes, metabolic associated fatty liver disease (MAFLD), and cardiovascular diseases (CVDs) are classified in this group of chronic diseases. Therefore, understanding the underlying molecular mechanisms of these diseases leads us to develop more accurate and effective treatments to reduce or mitigate their prevalence in the population. Given the global relevance of NCDs and ongoing research progress, this article reviews the current understanding about NCDs and their related risk factors, with a focus on obesity, diabetes, MAFLD, and CVDs, summarizing the knowledge about their pathophysiology and highlighting the currently available and emerging therapeutic strategies, especially pharmacological interventions. All of these diseases play an important role in the contamination by the SARS-CoV-2 virus, as well as in the progression and severity of the symptoms of the coronavirus disease 2019 (COVID-19). Therefore, we briefly explore the relationship between NCDs and COVID-19.

Proglucagon-Derived Peptides as Therapeutics

Initially discovered as an impurity in insulin preparations, our understanding of the hyperglycaemic hormone glucagon has evolved markedly over subsequent decades. With description of the precursor proglucagon, we now appreciate that glucagon was just the first proglucagon-derived peptide (PGDP) to be characterised. Other bioactive members of the PGDP family include glucagon-like peptides -1 and -2 (GLP-1 and GLP-2), oxyntomodulin (OXM), glicentin and glicentin-related pancreatic peptide (GRPP), with these being produced via tissue-specific processing of proglucagon by the prohormone convertase (PC) enzymes, PC1/3 and PC2. PGDP peptides exert unique physiological effects that influence metabolism and energy regulation, which has witnessed several of them exploited in the form of long-acting, enzymatically resistant analogues for treatment of various pathologies. As such, intramuscular glucagon is well established in rescue of hypoglycaemia, while GLP-2 analogues are indicated in the management of short bowel syndrome. Furthermore, since approval of the first GLP-1 mimetic for the management of Type 2 diabetes mellitus (T2DM) in 2005, GLP-1 therapeutics have become a mainstay of T2DM management due to multifaceted and sustainable improvements in glycaemia, appetite control and weight loss. More recently, longer-acting PGDP therapeutics have been developed, while newfound benefits on cardioprotection, bone health, renal and liver function and cognition have been uncovered. In the present article, we discuss the physiology of PGDP peptides and their therapeutic applications, with a focus on successful design of analogues including dual and triple PGDP receptor agonists currently in clinical development.

The effect of pramlintide, an antidiabetic amylin analogue, on angiogenesis-related markers in vitro

Background and purpose:

Irregularities of angiogenesis may participate in the pathogenesis of diabetes complications. Pramlintide is an amylin analogue administered for the treatment of type 1 and type 2 diabetes. The present investigation aimed at surveying the effect of pramlintide on angiogenesis-related markers in human umbilical vein endothelial cells (HUVECs).

Experimental approach:

The proliferation of cells was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) method. The effect of pramlintide on migration was estimated by Transwell® assay. in vitro evaluation of angiogenesis was performed by tube formation assay. The secretion of vascular endothelial growth factor (VEGF) to the supernatant of HUVECs was measured by an enzyme- linked immunosorbent assay (ELISA) kit. All experiments were performed in triplicate.

Findings / Results:

Pramlintide exhibited no inhibitory effect on HUVECs proliferation. It significantly increased cell migration at the concentration of 1 μg/mL. Pramlintide (1 μg/mL) also enhanced average tubules length, size, and the mean number of junctions. However, there was not any significant change in VEGF release from HUVECs.

Conclusion and implications:

Findings of this research revealed the effect of pramlintide on angiogenesis- related markers via enhancing migration and tubulogenesis in vitro, suggesting a worthwhile proposition for further clinical researches on improving vascular complications and healing of diabetic wounds.

Current molecular aspects in the development and treatment of diabetes

Diabetes mellitus (DM) leads to microvascular, macrovascular, and neurological complications. Less is understood about the mechanisms of this disease that give rise to weak bones. The many molecular mechanisms proposed to explain the damage caused by chronic hyperglycemia are organ and tissue dependent. Since all the different treatments for DM involve therapeutic activity combined with side effects and each patient represents a unique condition, there is no generalized therapy. The alterations stemming from hyperglycemia affect metabolism, osmotic pressure, oxidative stress, and inflammation. In part, hemodynamic modifications are linked to the osmotic potential of the excess of carbohydrates implicated in the disease. The change in osmotic balance increases as the disease progresses because hyperglycemia becomes chronic. The aim of the current contribution is to provide an updated overview of the molecular mechanisms that participate in the development and treatment of diabetes.

An amylin analogue attenuates alcohol-related behaviours in various animal models of alcohol use disorder

Recent findings have identified salmon calcitonin (sCT), an amylin receptor agonist and analogue of endogenous amylin, as a potential regulator of alcohol-induced activation of the mesolimbic dopamine system and alcohol consumption. Providing that the role of amylin signalling in alcohol-related behaviours remains unknown, the present experiments investigate the effect of sCT on these behaviours and the mechanisms involved. We showed that repeated sCT administration decreased alcohol and food intake in outbred rats. Moreover, single administration of the potent amylin receptor antagonist, AC187, increased short-term alcohol intake in outbred alcohol-consuming rats, but did not affect food intake. Acute administration of sCT prevented relapse-like drinking in the "alcohol deprivation effect" model in outbred alcohol-experienced rats. Additionally, acute sCT administration reduced operant oral alcohol self-administration (under the fixed ratio 4 schedule of reinforcement) in selectively bred Sardinian alcohol-preferring rats, while it did not alter operant self-administration (under the progressive ratio schedule of reinforcement) of a highly palatable chocolate-flavoured beverage in outbred rats. Lastly, we identified differential amylin receptor expression in high compared to low alcohol-consuming rats, as reflected by decreased calcitonin receptor and increased receptor activity modifying protein 1 expression in the nucleus accumbens (NAc) of high consumers. Collectively, our data suggest that amylin signalling, especially in the NAc, may contribute to reduction of various alcohol-related behaviours.

Is the management of diabetes different in dialysis patients?

Diabetes is highly and increasingly prevalent in the dialysis population and negatively impacts both quality and quantity of life. Nevertheless, the best approach to these patients is still debatable. The question of whether the management of diabetes should be different in dialysis patients does not have a clear yes or no answer but is divided into too many sub-issues that should be carefully considered. In this review, lifestyle, cardiovascular risk, and hyperglycemia management are explored, emphasizing the possible pros and cons of a similar approach to diabetes in dialysis patients compared to the general population.

Amylin Acts in the Lateral Dorsal Tegmental Nucleus to Regulate Energy Balance Through Gamma-Aminobutyric Acid Signaling

BACKGROUND

The pancreatic- and brain-derived hormone amylin promotes negative energy balance and is receiving increasing attention as a promising obesity therapeutic. However, the neurobiological substrates mediating amylin's effects are not fully characterized. We postulated that amylin acts in the lateral dorsal tegmental nucleus (LDTg), an understudied neural processing hub for reward and homeostatic feeding signals.

METHODS

We used immunohistochemical and quantitative polymerase chain reaction analyses to examine expression of the amylin receptor complex in rat LDTg tissue. Behavioral experiments were performed to examine the mechanisms underlying the hypophagic effects of amylin receptor activation in the LDTg.

RESULTS

Immunohistochemical and quantitative polymerase chain reaction analyses show expression of the amylin receptor complex in the LDTg. Activation of LDTg amylin receptors by the agonist salmon calcitonin dose-dependently reduces body weight, food intake, and motivated feeding behaviors. Acute pharmacological studies and longer-term adeno-associated viral knockdown experiments indicate that LDTg amylin receptor signaling is physiologically and potentially preclinically relevant for energy balance control. Finally, immunohistochemical data indicate that LDTg amylin receptors are expressed on gamma-aminobutyric acidergic neurons, and behavioral results suggest that local gamma-aminobutyric acid receptor signaling mediates the hypophagia after LDTg amylin receptor activation.

CONCLUSIONS

These findings identify the LDTg as a novel nucleus with therapeutic potential in mediating amylin's effects on energy balance through gamma-aminobutyric acid receptor signaling.

Novel therapeutic interventions for p53-altered tumors through manipulation of its family members, p63 and p73

TP53 is highly mutated in human cancers, thus targeting this tumor suppressor pathway is highly desirable and will impact many cancer patients. (1,2) Therapeutic strategies to reactivate the p53-pathway have been challenging, (3,4) and no effective treatment exists. (5) We utilized the p53-family members, p63 and p73, which are not frequently mutated in cancer, to treat p53-defective cancers. The N-terminal splice variants of p63 and p73 are denoted as the TA and ΔN isoforms. We recently demonstrated that deletion of either ΔNp63 or ΔNp73 in p53-deficient mouse tumors results in tumor regression mediated by metabolic programming. Using this strategy, we identified pramlintide, a synthetic analog of amylin, as an effective treatment for p53 deficient and mutant tumors. Here, we show the utility of using pramlintide, as a potential cancer preventive option for p53-deficient tumors in mouse models. Additionally, we found that in vivo inhibition of both ΔNp63 and ΔNp73 in combination accelerates tumor regression and increases survival of p53-deficient mice. We report that inhibition of both ΔNp63 and ΔNp73 in combination results in upregulation of 3 key metabolic regulators, IAPP, GLS2, and TIGAR resulting in an increase in apoptosis and tumor regression in ΔNp63/ΔNp73/p53 deficient thymic lymphomas. These data highlight the value of generating inhibitors that will simultaneously target ΔNp63 and ΔNp73 to treat cancer patients with alterations in p53.

Structural Basis for Receptor Activity-Modifying Protein-Dependent Selective Peptide Recognition by a G Protein-Coupled Receptor

Association of receptor activity-modifying proteins (RAMP1-3) with the G protein-coupled receptor (GPCR) calcitonin receptor-like receptor (CLR) enables selective recognition of the peptides calcitonin gene-related peptide (CGRP) and adrenomedullin (AM) that have diverse functions in the cardiovascular and lymphatic systems. How peptides selectively bind GPCR:RAMP complexes is unknown. We report crystal structures of CGRP analog-bound CLR:RAMP1 and AM-bound CLR:RAMP2 extracellular domain heterodimers at 2.5 and 1.8 Å resolutions, respectively. The peptides similarly occupy a shared binding site on CLR with conformations characterized by a β-turn structure near their C termini rather than the α-helical structure common to peptides that bind related GPCRs. The RAMPs augment the binding site with distinct contacts to the variable C-terminal peptide residues and elicit subtly different CLR conformations. The structures and accompanying pharmacology data reveal how a class of accessory membrane proteins modulate ligand binding of a GPCR and may inform drug development targeting CLR:RAMP complexes.

Pathway to artificial pancreas systems revisited: moving downstream

Artificial pancreas (AP) systems, a long-sought quest to replicate mechanically islet physiology that is lost in diabetes, are reaching the clinic, and the potential of automating insulin delivery is about to be realized. Significant progress has been made, and the safety and feasibility of AP systems have been demonstrated in the clinical research center and more recently in outpatient "real-world" environments. An iterative road map to AP system development has guided AP research since 2009, but progress in the field indicates that it needs updating. While it is now clear that AP systems are technically feasible, it remains much less certain that they will be widely adopted by clinicians and patients. Ultimately, the true success of AP systems will be defined by successful integration into the diabetes health care system and by the ultimate metric: improved diabetes outcomes.

KBP-042 improves bodyweight and glucose homeostasis with indices of increased insulin sensitivity irrespective of route of administration

KBP-042 is a synthetic peptide dual amylin- and calcitonin-receptor agonist (DACRA) developed to treat type 2 diabetes by inducing a significant weight loss while improving glucose homeostasis. In this study the aim was to compare two different formulations: An oral formulation (1mg/kg) to subcutaneous formulations of KBP-042 (2.5μg/kg, 5.0μg/kg and 7.5μg/kg) with comparable pharmacokinetic profiles. Furthermore to examine if differences in mode of action between the two different routes of administration in high-fat fed Sprague-Dawley rats were present. It was established that the subcutaneous administrations of KBP-042 were able to dose-dependently cause a significant weight-loss, reduce food intake, and improve glucose homeostasis without increasing insulin secretion, effects comparable to those observed with oral administration. At the same time, s.c. KBP-042 suppressed the inappropriate glucagon response better than the oral formulation. Furthermore, KBP-042 was found to reduce incretins GLP-1 and GIP and considerably, improve gastric emptying, and to alleviate leptin resistance, as well as insulin resistance. In conclusion, the subcutaneous route of administration was found to have the same beneficial effects on blood glucose homeostasis and weight loss as well as resistance towards important insulin and leptin, albeit with a markedly lower variation in both exposure and biological responses. These data support the application of subcutaneously delivered peptide for mechanistic studies, and highlight the potential of developing s.c. KBP-042 as a therapy for T2D.

IAPP-driven metabolic reprogramming induces regression of p53-deficient tumours in vivo

TP53 is commonly altered in human cancer, and Tp53 reactivation suppresses tumours in vivo in mice (TP53 and Tp53 are also known as p53). This strategy has proven difficult to implement therapeutically, and here we examine an alternative strategy by manipulating the p53 family members, Tp63 and Tp73 (also known as p63 and p73, respectively). The acidic transactivation-domain-bearing (TA) isoforms of p63 and p73 structurally and functionally resemble p53, whereas the ΔN isoforms (lacking the acidic transactivation domain) of p63 and p73 are frequently overexpressed in cancer and act primarily in a dominant-negative fashion against p53, TAp63 and TAp73 to inhibit their tumour-suppressive functions. The p53 family interacts extensively in cellular processes that promote tumour suppression, such as apoptosis and autophagy, thus a clear understanding of this interplay in cancer is needed to treat tumours with alterations in the p53 pathway. Here we show that deletion of the ΔN isoforms of p63 or p73 leads to metabolic reprogramming and regression of p53-deficient tumours through upregulation of IAPP, the gene that encodes amylin, a 37-amino-acid peptide co-secreted with insulin by the β cells of the pancreas. We found that IAPP is causally involved in this tumour regression and that amylin functions through the calcitonin receptor (CalcR) and receptor activity modifying protein 3 (RAMP3) to inhibit glycolysis and induce reactive oxygen species and apoptosis. Pramlintide, a synthetic analogue of amylin that is currently used to treat type 1 and type 2 diabetes, caused rapid tumour regression in p53-deficient thymic lymphomas, representing a novel strategy to target p53-deficient cancers.

Antidiabetic agents: past, present and future

Treatment of diabetes mellitus requires, at a certain stage of its course, drug intervention. This article reviews the properties of available antidiabetic medications and highlights potential targets for developing newer and safer drugs. Antidiabetic agents are grouped in the article as parts I, II and III according to the history of development. Part I groups early developed drugs, during the 20th century, including insulin, sulfonylureas, the metiglinides, insulin sensitizers, biguanides and α-glucosidase inhibitors. Part II groups newer drugs developed during the early part of the 21st century, the past decade, including GLP-1 analogs, DPP-VI inhibitors, amylin analogs and SGLT2 inhibitors. Part III groups potential targets for future design of newer antidiabetic agents with less adverse effects than the currently available antidiabetic drugs.

Efficacy and safety of lixisenatide in the treatment of Type 2 diabetes mellitus: a review of Phase III clinical data

Lixisenatide is a novel glucagon-like peptide-1 receptor agonist developed for the treatment of Type 2 diabetes mellitus (T2DM). In its clinical development program, once-daily lixisenatide has been associated with significant improvements in HbA_1c (change from baseline to week 24: up to -0.92%) and postprandial plasma glucose (PPG; change from baseline to week 24 as add-on to basal insulin: up to -7.96 mmol/l) with beneficial weight effects (change from baseline to week 24: up to -2.0 kg as add-on to oral antidiabetic agents and -1.8 kg as add-on to basal insulin) and a low incidence of severe hypoglycemia (from 0 to 1.2% over 24 weeks). Pharmacodynamic data highlight differences between lixisenatide and other glucagon-like peptide-1 receptor agonists, demonstrating more pronounced effects on PPG than liraglutide, with less frequent dosing and a better tolerability profile than exenatide. Lixisenatide has recently been evaluated in a comprehensive Phase III clinical trial program in patients with T2DM, which included three large-scale studies of once-daily lixisenatide in combination with basal insulin. Lixisenatide has been studied as a monotherapy or oral agent combination, or with insulin. It may become a treatment option for certain patient groups in the near future, including those that are unable to reach target HbA_1c goals despite treatment with basal insulin and a fairly well-controlled fasting plasma glucose, indicating that additional PPG control could be needed. This article reviews clinical data for lixisenatide to date, both as monotherapy and in combination with basal insulin, and discusses the implications of lixisenatide for the management of T2DM.

Oral salmon calcitonin attenuates hyperglycaemia and preserves pancreatic beta-cell area and function in Zucker diabetic fatty rats

BACKGROUND AND PURPOSE

Oral salmon calcitonin (sCT), a dual-action amylin and calcitonin receptor agonist, improved glucose homeostasis in diet-induced obese rats. Here, we have evaluated the anti-diabetic efficacy of oral sCT using parameters of glycaemic control and beta-cell morphology in male Zucker diabetic fatty (ZDF) rats, a model of type 2 diabetes.

EXPERIMENTAL APPROACH

Male ZDF rats were treated with oral sCT (0.5, 1.0 or 2 mg·kg(-1) ) or oral vehicle twice daily from age 8 to 18 weeks. Zucker lean rats served as control group. Fasting and non-fasted blood glucose, glycosylated haemoglobin (HbA1c) and levels of pancreas and incretin hormones were determined. Oral glucose tolerance test and i.p. glucose tolerance test were compared, and beta-cell area and function were evaluated.

KEY RESULTS

Oral sCT treatment dose-dependently attenuated fasting and non-fasted hyperglycaemia during the intervention period. At the end of the study period, oral sCT treatment by dose decreased diabetic hyperglycaemia by ∼9 mM and reduced HbA1c levels by 1.7%. Furthermore, a pronounced reduction in glucose excursions was dose-dependently observed for oral sCT treatment during oral glucose tolerance test. In addition, oral sCT treatment sustained hyperinsulinaemia and attenuated hyperglucagonaemia and hypersecretion of total glucagon-like peptide-1 predominantly in the basal state. Lastly, oral sCT treatment dose-dependently improved pancreatic beta-cell function and beta-cell area at study end.

CONCLUSIONS AND IMPLICATIONS

Oral sCT attenuated diabetic hyperglycaemia in male ZDF rats by improving postprandial glycaemic control, exerting an insulinotropic and glucagonostatic action in the basal state and by preserving pancreatic beta-cell function and beta-cell area.

Gut peptide hormones and pediatric type 1 diabetes mellitus

The aims of our study were to evaluate plasma levels of gut hormones in children with Type 1 diabetes mellitus (T1DM) in comparison with healthy controls and to correlate plasma concentrations of gut hormones with blood biochemistry, markers of metabolic control and with anthropometric parameters. We measured postprandial levels of specific gut peptide hormones in T1DM children. Amylin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), ghrelin, leptin, pancreatic polypeptide (PP), and polypeptide YY (PYY) were assessed in 19 T1DM children and 21 healthy reference controls. Multiplex assay kit (LINCOplex(®)) was used for determination of the defined plasma hormone levels. T1DM subjects had significantly reduced amylin (p<0.001) and ghrelin (p<0.05) levels, whereas GIP (p<0.05) was elevated when compared with healthy controls. Plasma levels of other measured hormones did not differ statistically between the studied groups. Further analysis of T1DM patients demonstrated an association between body mass index and GLP-1 (r=0.4642; p<0.05), leptin (r=0.5151; p<0.05), and amylin (r=0.5193; p<0.05). Ghrelin levels positively correlated with serum HDL cholesterol (r=0.4760; p<0.05). An inverse correlation was demonstrated with triglycerides (TG) (r= -0.5674; p<0.01), insulin dosage (r= -0.5366; p<0.05), and HbA1c% (r= -0.6864; p<0.01). Leptin was inversely correlated with TG (r= -0.6351; p<0.01). Stepwise regression analysis was performed to enlighten the predictive variables. Our study demonstrated an altered secretion pattern of gut peptide hormones in T1DM children. A close correlation was revealed between these peptides as well as with blood biochemistry, markers of metabolic control and with anthropometric parameters. Further studies are essential to explore this issue in T1DM children.

Changes in dynamic insulin and gastrointestinal hormone secretion in obese children

BACKGROUND

Disturbed satiety and hunger perception in obese individuals has been reported, however data on the dynamic changes of hormonal mediators are sparse.

OBJECTIVE

To evaluate the secretion pattern of insulin, ghrelin, peptide-YY (PYY), and amylin via 0 to 180 min oral glucose tolerance testing in obese and lean children.

SUBJECTS AND METHODS

A prospective clinical study was conducted on lean (n=9) and obese (n=20) Caucasian children of comparable age, gender, and pubertal stage. Serial blood samples were collected.

RESULTS

Compared to baseline, levels of acylated ghrelin showed a significant decrease in lean (p<0.05) but not in obese children. PYY increase was blunted and of shorter duration (60 min) in obese children. Amylin levels increased in both groups, and attained significantly higher levels in obese children (p<0.05).

CONCLUSION

Glucose stimulated gut hormone secretion differed between obese and lean children, and may explain the disturbed satiety observed in obese children.

Oral salmon calcitonin--pharmacology in osteoporosis

IMPORTANCE OF THE FIELD

Osteoporosis is a slow progressive disease with develops over decades, and where intervention is needed for an extended number of years. This highlights the need for safe intervention possibilities, which have sustained beneficial effects post-treatment.

AREAS COVERED IN THIS REVIEW

Articles on salmon calcitonin appearing on Pubmed from 1960 until today, with focus on a newly developed oral formulation showing increased exposure and efficacy compared with nasal formulation is reviewed. The second half focuses on long-term phenomena, such as bone quality and resolution effects. The final part discusses potential additional benefits of salmon calcitonin.

WHAT THE READER WILL GAIN

Insight into the clinical development of an orally formulated peptide, as well as a detailed understanding of why this approach could revive salmon calcitonin as a treatment for osteoporosis.

TAKE HOME MESSAGE

The oral formulation of salmon calcitonin provides additional benefits and increased efficacy on bone based on Phase I and II clinical trials data, as compared with the nasal formulation. Hence, the results on the ongoing Phase III fracture trial are awaited with great interest.

Diabetes mellitus: new challenges and innovative therapies

Diabetes mellitus is a widespread disease prevalence and incidence of which increases worldwide. The introduction of insulin therapy represented a major breakthrough in type 1 diabetes; however, frequent hyper- and hypoglycemia seriously affects the quality of life of these patients. New therapeutic approaches, such as whole pancreas transplant or pancreatic islet transplant, stem cell, gene therapy and islets encapsulation are discussed in this review. Regarding type 2 diabetes, therapy has been based on drugs that stimulate insulin secretion (sulphonylureas and rapid-acting secretagogues), reduce hepatic glucose production (biguanides), delay digestion and absorption of intestinal carbohydrate (alpha-glucosidase inhibitors) or improve insulin action (thiazolidinediones). This review is also focused on the newer therapeutically approaches such as incretin-based therapies, bariatric surgery, stem cells and other emerging therapies that promise to further extend the options available. Gene-based therapies are among the most promising emerging alternatives to conventional treatments. Some of these therapies rely on genetic modification of non-differentiated cells to express pancreatic endocrine developmental factors, promoting differentiation of non-endocrine cells into β-cells, enabling synthesis and secretion of insulin in a glucose-regulated manner. Alternative therapies based on gene silencing using vector systems to deliver interference RNA to cells (i.e. against VEGF in diabetic retinopathy) are also a promising therapeutic option for the treatment of several diabetic complications. In conclusion, treatment of diabetes faces now a new era that is characterized by a variety of innovative therapeutic approaches that will improve quality-life and allow personalized therapy-planning in the near future.

Resistance exercise training lowers HbA1c more than aerobic training in adults with type 2 diabetes

BACKGROUND

The aim of this study was to compare the effects of 10 weeks of resistance or treadmill exercises on glycemic indices levels prior to and immediately following exercise in adults with type 2 diabetes.

RESEARCH DESIGN AND METHOD

Twenty inactive subjects (mean age 53.5 years) with type 2 diabetes enrolled in the study. Baseline HbA1c, blood glucose levels, heart rate, and blood pressure were measured for each subject prior to the initiation of the exercise program. Subsequently, subjects were matched to age, waist circumference and sex and assigned to either isocaloric resistance or treadmill exercise groups, which met 3 times per week for 10 weeks.

RESULTS

Both groups showed a reduction in pre and post-exercise blood glucose and HbA1c values. There was no change in resting blood pressure or heart rate in either group during the course of the 10 week intervention. The group receiving resistance exercises showed significant differences in the daily pre-exercise plasma glucose readings between the beginning and end of the exercise protocol (p < 0.001). There were significant improvements in the mean HbA1c reading pre and post training in both groups (p < 0.001). However, the greater reduction was noted in the resistance exercise group, and at 10 weeks their HbA1c levels were significantly lower than the group that received treadmill exercises (p < 0.006).

CONCLUSION

Ten weeks of resistance exercises were associated with a significantly better glycemic control in adults with type 2 diabetes compared to treadmill exercise.

Amylin suppresses acetic acid-induced visceral pain and spinal c-fos expression in the mouse

Amylin is a member of calcitonin or calcitonin gene-related peptide (CGRP) family. Immunohistochemical study revealed a dense network of amylin-immunoreactive (irAMY) cell processes in the superficial dorsal horn of the mice. Numerous dorsal root ganglion (DRG) and trigeminal ganglion cells expressed moderate to strong irAMY. Reverse transcriptase-polymerase chain reaction (RT-PCR) revealed amylin receptor mRNA in the mouse spinal cord, brain stem, cortex, hypothalamus and hippocampus. The nociceptive or antinociceptive effects of amylin were evaluated in the acetic acid-induced writhing test. Amylin (0.1, 0.5 and 1 mg/kg, intraperitoneally (i.p.) or 1-10 microg, intrathecally (i.t.)) reduced the number of writhes in a dose-dependent manner. Pretreatment of the mice with the amylin receptor antagonist salmon calcitonin (8-32), either by i.p. or i.t., antagonized the effect of amylin on acetic acid-induced writhing test. Locomotor activity was not significantly modified by amylin injected either i.p. (0.01-1 mg/kg) or i.t. (1-10 microg). Measurement of c-fos mRNA by RT-PCR or proteins by Western blot showed that the levels were upregulated in the spinal cord of mice injected with acetic acid and the increase was attenuated by pretreatment with amylin (10 microg, i.t.). Collectively, our result demonstrates that irAMY is expressed in DRG neurons with their cell processes projecting to the superficial layers of the dorsal horn, and that the peptide by interacting with amylin receptors in the spinal cord may be antinociceptive.

Davalintide (AC2307), a novel amylin-mimetic peptide: enhanced pharmacological properties over native amylin to reduce food intake and body weight

OBJECTIVE

The current set of studies describe the in vivo metabolic actions of the novel amylin-mimetic peptide davalintide (AC2307) in rodents and compares these effects with those of the native peptide.

RESEARCH DESIGN AND METHODS

The anti-obesity effects of davalintide were examined after intraperitoneal injection or sustained peripheral infusion through subcutaneously implanted osmotic pumps. The effect of davalintide on food intake after lesioning of the area postrema (AP) and neuronal activation as measured by c-Fos, were also investigated.

RESULTS

Similar to amylin, davalintide bound with high affinity to amylin, calcitonin and calcitonin gene-related peptide receptors. Acutely, davalintide displayed greater suppression of dark-cycle feeding and an extended duration of action compared with amylin (23 versus 6 h). Davalintide had no effect on locomotor activity or kaolin consumption at doses that decreased food intake. Davalintide-induced weight loss through infusion was dose dependent, durable up to 8 weeks, fat-specific and lean-sparing, and was associated with a shift in food preference away from high-fat (palatable) chow. Metabolic rate was maintained during active weight loss. Both davalintide and amylin failed to suppress food intake after lesioning of the AP and activated similar brain nuclei, with davalintide displaying an extended duration of c-Fos expression compared with amylin (8 versus 2 h).

CONCLUSION

Davalintide displayed enhanced in vivo metabolic activity over amylin while retaining the beneficial properties possessed by the native molecule. In vitro receptor binding, c-Fos expression and AP lesion studies suggest that the metabolic actions of davalintide and amylin occur through activation of similar neuronal pathways.

What are the risks and the benefits of current and emerging weight-loss medications?

Obesity is epidemic; new medications and therapeutic options are urgently needed to reduce the associated health care burden. The initial clinical strategy for weight loss is lifestyle modification involving a combination of diet, exercise, and behavior change. However, it is difficult for many to achieve and maintain weight loss solely through this approach. Only two drugs, orlistat and sibutramine, have been approved by the US Food and Drug Administration (FDA) to treat obesity long term, and both medications have undesirable side effects, leaving an enormous unmet need for efficacious and safe therapy for obesity. Other medications with weight-loss effects have been approved by the FDA for short-term treatment of obesity or for disorders other than obesity, but these also have potential adverse effects. This article discusses the perceived benefits and risks of these approved medications along with emerging drugs that have shown weight-loss effects.

Synthesis of chemically modified bioactive peptides: recent advances, challenges and developments for medicinal chemistry

Although not complying with Lipinski’s rule, peptides are to an increasing extent being developed into new active pharmaceutical ingredients. This is mainly due to novel application routes, formulations and chemical modifications, which confer on the peptides improved uptake and increased metabolic stability. A brief survey of currently approved peptide drugs and the present scope of the application of peptides as drugs is provided. Cyclic peptides are emerging as an interesting class of peptides with conformational rigidity and homogeneity, high receptor affinity and selectivity, increased metabolic stability and – in special cases – even oral availability. Challenges and new methodology for the synthesis of cyclic peptides are outlined and an overview of approaches toward the design of peptide conformation and peptide modification by nonproteinogenic building blocks is given.