CNS-targeting pharmacological interventions for the metabolic syndrome

Revving the engine: PKB/AKT as a key regulator of cellular glucose metabolism

Glucose metabolism is of critical importance for cell growth and proliferation, the disorders of which have been widely implicated in cancer progression. Glucose uptake is achieved differently by normal cells and cancer cells. Even in an aerobic environment, cancer cells tend to undergo metabolism through glycolysis rather than the oxidative phosphorylation pathway. Disordered metabolic syndrome is characterized by elevated levels of metabolites that can cause changes in the tumor microenvironment, thereby promoting tumor recurrence and metastasis. The activation of glycolysis-related proteins and transcription factors is involved in the regulation of cellular glucose metabolism. Changes in glucose metabolism activity are closely related to activation of protein kinase B (PKB/AKT). This review discusses recent findings on the regulation of glucose metabolism by AKT in tumors. Furthermore, the review summarizes the potential importance of AKT in the regulation of each process throughout glucose metabolism to provide a theoretical basis for AKT as a target for cancers.

The 'Behavioral Balance Model': A new perspective on the aetiology and therapy of obesity

Obesity is a debilitating disease of global proportions that necessitates refined, concept-driven therapeutic approaches. Policy makers, the public and even health care professionals, but also individuals with obesity harbour many misconceptions regarding this disease, which leads to prejudice, negative attitudes, stigmatization, discrimination, self-blame, and failure to provide and finance adequate medical care. Decades of intensive, successful scientific research on obesity have only had a very limited effect on this predicament. We propose a science-based, easy-to-understand conceptual model that synthesizes the complex pathogenesis of obesity including biological, psychological, social, economic and environmental aspects with the aim to explain and communicate better the nature of obesity and currently available therapeutic modalities. According to our integrative 'Behavioral Balance Model', 'top-down cognitive control' strategies are implemented (often with limited success) to counterbalance the increased 'bottom-up drive' to gain weight, which is triggered by biological, psycho-social and environmental mechanisms in people with obesity. Besides offering a deeper understanding of obesity, the model also highlights why there is a strong need for multimodal therapeutic approaches that may not only increase top-down control but also reduce a pathologically increased bottom-up drive.

Benchmarking causal reasoning algorithms for gene expression-based compound mechanism of action analysis

BACKGROUND

Elucidating compound mechanism of action (MoA) is beneficial to drug discovery, but in practice often represents a significant challenge. Causal Reasoning approaches aim to address this situation by inferring dysregulated signalling proteins using transcriptomics data and biological networks; however, a comprehensive benchmarking of such approaches has not yet been reported. Here we benchmarked four causal reasoning algorithms (SigNet, CausalR, CausalR ScanR and CARNIVAL) with four networks (the smaller Omnipath network vs. 3 larger MetaBase™ networks), using LINCS L1000 and CMap microarray data, and assessed to what extent each factor dictated the successful recovery of direct targets and compound-associated signalling pathways in a benchmark dataset comprising 269 compounds. We additionally examined impact on performance in terms of the functions and roles of protein targets and their connectivity bias in the prior knowledge networks.

RESULTS

According to statistical analysis (negative binomial model), the combination of algorithm and network most significantly dictated the performance of causal reasoning algorithms, with the SigNet recovering the greatest number of direct targets. With respect to the recovery of signalling pathways, CARNIVAL with the Omnipath network was able to recover the most informative pathways containing compound targets, based on the Reactome pathway hierarchy. Additionally, CARNIVAL, SigNet and CausalR ScanR all outperformed baseline gene expression pathway enrichment results. We found no significant difference in performance between L1000 data or microarray data, even when limited to just 978 'landmark' genes. Notably, all causal reasoning algorithms also outperformed pathway recovery based on input DEGs, despite these often being used for pathway enrichment. Causal reasoning methods performance was somewhat correlated with connectivity and biological role of the targets.

CONCLUSIONS

Overall, we conclude that causal reasoning performs well at recovering signalling proteins related to compound MoA upstream from gene expression changes by leveraging prior knowledge networks, and that the choice of network and algorithm has a profound impact on the performance of causal reasoning algorithms. Based on the analyses presented here this is true for both microarray-based gene expression data as well as those based on the L1000 platform.

Obesity medication lorcaserin activates brainstem GLP-1 neurons to reduce food intake and augments GLP-1 receptor agonist induced appetite suppression

OBJECTIVE

Overweight and obesity are endemic in developed countries, with a substantial negative impact on human health. Medications developed to treat obesity include agonists for the G-protein coupled receptors glucagon-like peptide-1 (GLP-1R; e.g. liraglutide), serotonin 2C (5-HT2CR; e.g, lorcaserin), and melanocortin4 (MC4R) which reduce body weight primarily by suppressing food intake. However, the mechanisms underlying the therapeutic food intake suppressive effects are still being defined and were investigated here.

METHODS

We profiled PPG neurons in the nucleus of the solitary tract (PPGNTS) using single nucleus RNA sequencing (Nuc-Seq) and histochemistry. We next examined the requirement of PPGNTS neurons for obesity medication effects on food intake by virally ablating PPGNTS neurons. Finally, we assessed the effects on food intake of the combination of liraglutide and lorcaserin.

RESULTS

We found that 5-HT2CRs, but not GLP-1Rs or MC4Rs, were widespread in PPGNTS clusters and that lorcaserin significantly activated PPGNTS neurons. Accordingly, ablation of PPGNTS neurons prevented the reduction of food intake by lorcaserin but not MC4R agonist melanotan-II, demonstrating the functional significance of PPGNTS 5-HT2CR expression. Finally, the combination of lorcaserin with GLP-1R agonists liraglutide or exendin-4 produced greater food intake reduction as compared to either monotherapy.

CONCLUSIONS

These findings identify a necessary mechanism through which obesity medication lorcaserin produces its therapeutic benefit, namely brainstem PPGNTS neurons. Moreover, these data reveal a strategy to augment the therapeutic profile of the current frontline treatment for obesity, GLP-1R agonists, via coadministration with 5-HT2CR agonists.

Clinical Research Evidence Supporting Administration and Dosing Recommendations of Medicinal Cannabis as Analgesic in Cancer Patients

The analgesic potential of Cannabis sativa L.-based medicinal cannabis products for treatment of cancer associated chronic pains has gained increased interest in recent years. To ensure a controlled distribution of these products and investigate their therapeutic potential, several countries have established so-called pilot trials. Many doctors, however, are hesitant to prescribe medicinal cannabis primarily due to lack of research evidence regarding the products' efficacy, safety and thus questionable dosing guidelines. This review aims to elucidate clinical research supporting administration of medicinal cannabis in cancer patients for analgesic purposes. The cannabinoids' effects on the endocannabinoid system (ECS) and its implication in pain regulation is included to illustrate the complexity related to this research field. Published clinical studies on medicinal cannabis primarily consist of observational studies and only one pilot randomized controlled trial (RCT), where more RCTs exist on the cannabis-based product, Sativex^® (GW Pharma Ltd., Cambridge, UK). The studies indicate analgesic potential, however non-significantly, for most patients and with acceptable safety profile. Summarizing, high-quality RCTs are scarce in this research field, and the limitations of the observational studies complicates interpretation of clinical outcomes. Despite discrepancy among the studies, they do show indications for administration and dosing regimens providing analgesic effects for some cancer patients.

The relationship between n-3 polyunsaturated fatty acids and telomere: A review on proposed nutritional treatment against metabolic syndrome and potential signaling pathways

Metabolic syndrome (MetS), a cluster of metabolic abnormalities composed of central obesity, elevated blood pressure, glucose disturbances, hypercholesterolemia and dyslipidaemia, has increasingly become a public health problem in the 21st century worldwide. The dysfunction of telomeres, the repetitive DNA with highly conserved sequences (5'-TTAGGG-3'), is remarkably correlated with organismal aging, even suggesting a causal relationship with metabolic disorders. The health benefits of n-3 polyunsaturated fatty acids (PUFAs) in multiple disorders are associated with telomere length in evidence, which have recently drawn wide attention. However, functional targets and pathways for the associations of n-3 PUFAs and telomere with MetS remain scare. Few studies have summarized the role of n-3 PUFAs in DNA damage repair pathways, anti-inflammatory pathways, and redox balance, linking with telomere biology, and other potential telomere-related signaling pathways. This review aims to (i) elucidate how n-3 PUFAs ameliorate telomere attrition in the context of anti-oxidation and anti-inflammation; (ii) unravel the role of n-3 PUFAs in modulating telomere-related neuron dysfunction and regulating the neuro-endocrine-immunological network in MetS; (iii) epidemiologically implicate the associations of metabolic disorders and n-3 PUFAs with telomere length; and (iv) suggest promising biochemical approaches and advancing methodologies to overcome the inter-variation problem helpful for future research.

Ventromedial hypothalamic OGT drives adipose tissue lipolysis and curbs obesity

The ventromedial hypothalamus (VMH) is known to regulate body weight and counterregulatory response. However, how VMH neurons regulate lipid metabolism and energy balance remains unknown. O-linked β-d-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation), catalyzed by O-GlcNAc transferase (OGT), is considered a cellular sensor of nutrients and hormones. Here, we report that genetic ablation of OGT in VMH neurons inhibits neuronal excitability. Mice with VMH neuron-specific OGT deletion show rapid weight gain, increased adiposity, and reduced energy expenditure, without significant changes in food intake or physical activity. The obesity phenotype is associated with adipocyte hypertrophy and reduced lipolysis of white adipose tissues. In addition, OGT deletion in VMH neurons down-regulates the sympathetic activity and impairs the sympathetic innervation of white adipose tissues. These findings identify OGT in the VMH as a homeostatic set point that controls body weight and underscore the importance of the VMH in regulating lipid metabolism through white adipose tissue-specific innervation.

Signaling pathways in obesity: mechanisms and therapeutic interventions

Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.

Turning the clock forward: New pharmacological and non pharmacological targets for the treatment of obesity

AIMS

Obesity and its main metabolic complication, type 2 diabetes, have attained the status of a global pandemic; there is need for novel strategies aimed at treating obesity and preventing the development of diabetes. A healthy diet and exercise are basic for treatment of obesity but often not enough. Pharmacotherapy can be helpful in maintaining compliance, ameliorating obesity-related health risks, and improving quality of life. In the last two decades, the knowledge of central and peripheral mechanisms underlying homeostatic and hedonic aspects of food intake has significantly increased. Dysregulation of one or more of these components could lead to obesity.

DATA SYNTHESIS

In order to better understand how potential innovative treatment options can affect obesity, homeostatic and reward mechanisms that regulate energy balance has been firstly illustrated. Then, an overview of potential therapeutic targets for obesity, distinguished according to the level of regulation of feeding behavior, has been provided. Moreover, several non-drug therapies have been recently tested in obesity, such as non-invasive neurostimulation: Transcranial Magnetic Stimulation or Transcranial Direct Current Stimulation. All of them are promising for obesity treatment and are almost devoid of side effects, constituting a potential resource for the prevention of metabolic diseases.

CONCLUSIONS

The plethora of current anti-obesity therapies creates the unique challenge for physicians to customize the intervention, according to the specific obesity characteristics and the intervention side effect profiles; moreover, it allows multimodal approaches addressed to treat obesity and metabolic adaptation with complementary mechanisms.

Novel Noninvasive Approaches to the Treatment of Obesity: From Pharmacotherapy to Gene Therapy

Recent insights into the pathophysiologic underlying mechanisms of obesity have led to the discovery of several promising drug targets and novel therapeutic strategies to address the global obesity epidemic and its comorbidities. Current pharmacologic options for obesity management are largely limited in number and of modest efficacy/safety profile. Therefore, the need for safe and more efficacious new agents is urgent. Drugs that are currently under investigation modulate targets across a broad range of systems and tissues, including the central nervous system, gastrointestinal hormones, adipose tissue, kidney, liver, and skeletal muscle. Beyond pharmacotherapeutics, other potential antiobesity strategies are being explored, including novel drug delivery systems, vaccines, modulation of the gut microbiome, and gene therapy. The present review summarizes the pathophysiology of energy homeostasis and highlights pathways being explored in the effort to develop novel antiobesity medications and interventions but does not cover devices and bariatric methods. Emerging pharmacologic agents and alternative approaches targeting these pathways and relevant research in both animals and humans are presented in detail. Special emphasis is given to treatment options at the end of the development pipeline and closer to the clinic (ie, compounds that have a higher chance to be added to our therapeutic armamentarium in the near future). Ultimately, advancements in our understanding of the pathophysiology and interindividual variation of obesity may lead to multimodal and personalized approaches to obesity treatment that will result in safe, effective, and sustainable weight loss until the root causes of the problem are identified and addressed.

Reciprocal control of obesity and anxiety-depressive disorder via a GABA and serotonin neural circuit

The high comorbidity between obesity and mental disorders, such as depression and anxiety, often exacerbates metabolic and neurological symptoms significantly. However, neural mechanisms that underlie reciprocal control of feeding and mental states are largely elusive. Here we report that melanocortin 4 receptor (MC4R) neurons located in the dorsal bed nucleus of the stria terminus (dBNST) engage in the regulation of mentally associated weight gain by receiving GABAergic projections from hypothalamic AgRP neurons onto α5-containing GABAA receptors and serotonergic afferents onto 5-HT3 receptors. Chronic treatment with a high-fat diet (HFD) significantly blunts the hyperexcitability of AgRP neurons in response to not only hunger but also anxiety and depression-like stimuli. Such HFD-mediated desensitization reduces GABAergic outputs from AgRP neurons to downstream MC4RdBNST neurons, resulting in severe mental dysregulation. Genetic enhancement of the GABAAR-α5 or suppression of the 5-HT3R within the MC4RdBNST neurons not only abolishes HFD-induced anxiety and depression but also robustly reduces body weight by suppression of food intake. To gain further translational insights, we revealed that combined treatment of zonisamide (enhancing the GABAAR-α5 signaling) and granisetron (a selective 5-HT3R antagonist) alleviates mental dysfunction and yields a robust reversal of diet-induced obesity by reducing total calorie intake and altering food preference towards a healthy low-fat diet. Our results unveil a neural mechanism for reciprocal control of appetite and mental states, which culminates in a novel zonisamide-granisetron cocktail therapy for potential tackling the psychosis-obesity comorbidity.

Microglia-Neuron Crosstalk in Obesity: Melodious Interaction or Kiss of Death?

Diet-induced obesity can originate from the dysregulated activity of hypothalamic neuronal circuits, which are critical for the regulation of body weight and food intake. The exact mechanisms underlying such neuronal defects are not yet fully understood, but a maladaptive cross-talk between neurons and surrounding microglial is likely to be a contributing factor. Functional and anatomical connections between microglia and hypothalamic neuronal cells are at the core of how the brain orchestrates changes in the body's metabolic needs. However, such a melodious interaction may become maladaptive in response to prolonged diet-induced metabolic stress, thereby causing overfeeding, body weight gain, and systemic metabolic perturbations. From this perspective, we critically discuss emerging molecular and cellular underpinnings of microglia-neuron communication in the hypothalamic neuronal circuits implicated in energy balance regulation. We explore whether changes in this intercellular dialogue induced by metabolic stress may serve as a protective neuronal mechanism or contribute to disease establishment and progression. Our analysis provides a framework for future mechanistic studies that will facilitate progress into both the etiology and treatments of metabolic disorders.

Potential Role of Dexamphetamine in the Treatment of Non-alcoholic Fatty Liver Disease: Hopes and Pitfalls

Non-alcoholic fatty liver disease (NAFLD) is one of most frequent causes of chronic liver disease. Global prevalence of NAFLD and nonalcoholic steatohepatitis (NASH) with advanced fibrosis is increasing day by day. Patients with NAFLD are more susceptible to encounter cardiovascular morbidity and mortality. Apart from lifestyle changes and dietary modifications, no effective pharmacotherapy is available to prevent the progression of NAFLD to NASH and advanced stages of hepatic fibrosis and cirrhosis. Dexamphetamine is the d-isomer of amphetamine, which acts by inhibiting monoamine reuptake and direct stimulation of dopamine and noradrenaline release. Presently, dexamphetamine is indicated for the treatment of attention deficit hyperactivity disorder and narcolepsy, but since its use was found to be associated with weight loss, it is also now used as an off-label drug for the treatment of obesity. Direct or indirect evidence is present in the form case reports, case series and from effects of related drugs to support the potential role of dexamphetamine in NAFLD. There is an urgent need to initiate preclinical and clinical studies involving robust methodology and adequate sample sizes to explore the potential of dexamphetamine in patients with NAFLD. In this review, we will discuss the therapeutic potential of dexamphetamine for the treatment of NAFLD.

[An orally administered glucagon-like peptide 1 (GLP1) analogue: A landmark in the treatment of type 2 diabetes]

Semaglutide is the first peptide to receive European marketing authorization for oral administration in the treatment of type 2 diabetes. The active molecule is the same as the one marketed for weekly subcutaneous administration. It is associated with a new excipient, which protects it from degradation by gastric pepsin and allows its absorption in the stomach. This article presents the pharmacological characteristics of this drug, as well as a critical analysis of the results of the main phase III clinical trials.

Potential Role of Dexamphetamine in the Treatment of Non-alcoholic Fatty Liver Disease: Hopes and Pitfalls

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Diabetes type 2 risk gene Dusp8 is associated with altered sucrose reward behavior in mice and humans

BACKGROUND

Dusp8 is the first GWAS-identified gene that is predominantly expressed in the brain and has previously been linked with the development of diabetes type 2 in humans. In this study, we unravel how Dusp8 is involved in the regulation of sucrose reward behavior.

METHODS

Female, chow-fed global Dusp8 WT and KO mice were tested in an observer-independent IntelliCage setup for self-administrative sucrose consumption and preference followed by a progressive ratio task with restricted sucrose access to monitor seeking and motivation behavior. Sixty-three human carriers of the major C and minor T allele of DUSP8 SNP rs2334499 were tested for their perception of food cues by collecting a rating score for sweet versus savory high caloric food.

RESULTS

Dusp8 KO mice showed a comparable preference for sucrose, but consumed more sucrose compared to WT mice. In a progressive ratio task, Dusp8 KO females switched to a "trial and error" strategy to find sucrose while control Dusp8 WT mice kept their previously established seeking pattern. Nonetheless, the overall motivation to consume sucrose, and the levels of dopaminergic neurons in the brain areas NAcc and VTA were comparable between genotypes. Diabetes-risk allele carriers of DUSP8 SNP rs2334499 preferred sweet high caloric food compared to the major allele carriers, rating scores for savory food remained comparable between groups.

CONCLUSION

Our data suggest a novel role for Dusp8 in the perception of sweet high caloric food as well as in the control of sucrose consumption and foraging in mice and humans.

Dual-Core Prebiotic Microcapsule Encapsulating Probiotics for Metabolic Syndrome

Designing strategies to utilize the synergistic effect of probiotics and prebiotics is a promising way in treating metabolic-related diseases. Here, inspired by the mutually promotable but mutually incompatible characteristics of Yin and Yang, dual-core microcapsules that encapsulate Lactobacillus and Bacillus subtilis into separate compartments were presented through electrostatically driven microfluidics. The microcapsules showed acid resistance and preserved probiotic activity. They also fostered the proliferation of probiotics while creating an anaerobic environment and promoted lactic acid fermentation without affecting each other. It has been demonstrated that the microcapsules could reduce inflammation, improve fat metabolism, and restore intestinal barrier functions, thus contributing to the treatment of metabolic syndrome in vivo. These features make the dual-core microcapsules an ideal candidate for treating metabolic syndrome and related diseases.

Regulation of energy intake and mechanisms of metabolic adaptation or maladaptation after caloric restriction

Despite their critical role in susceptibility to metabolic diseases such as obesity and type 2 diabetes, mechanisms regulating energy balance are extremely complex and far from being fully understood. Both central and peripheral feedback circuits are involved and, despite it was traditionally thought that the energy balance of an organism depends on the equality between calorie intake within the system and energy expenditure, the regulation of energy content in biological systems oversteps the classical physical laws of thermodynamics. The fine-tuned mechanism for body weight and energy storage regulation is aimed to preserve survival chances in response to the variations of energy availability, as expressed by the metabolic flexibility of this system adapting subjects to both starvation and overfeeding. However, these mechanisms can lose their flexibility, with consequent maladaptation to both increased energy intake and calorie restriction leading to the development of several metabolic disturbances.

Insights into incretin-based therapies for treatment of diabetic dyslipidemia

Derangements in triglyceride and cholesterol metabolism (dyslipidemia) are major risk factors for the development of cardiovascular diseases in obese and type-2 diabetic (T2D) patients. An emerging class of glucagon-like peptide-1 (GLP-1) analogues and next generation peptide dual-agonists such as GLP-1/glucagon or GLP-1/GIP could provide effective therapeutic options for T2D patients. In addition to their role in glucose and energy homeostasis, GLP-1, GIP and glucagon serve as regulators of lipid metabolism. This review summarizes the current knowledge in GLP-1, glucagon and GIP effects on lipid and lipoprotein metabolism and frames the emerging therapeutic benefits of GLP-1 analogs and GLP-1-based multiagonists as add-on treatment options for diabetes associated dyslipidemia.

Transaminase-mediated synthesis of enantiopure drug-like 1-(3′,4′-disubstituted phenyl)propan-2-amines

Transaminases (TAs) offer an environmentally and economically attractive method for the direct synthesis of pharmaceutically relevant disubstituted 1-phenylpropan-2-amine derivatives starting from prochiral ketones. In this work, we report the application of immobilised whole-cell biocatalysts with (R)-transaminase activity for the synthesis of novel disubstituted 1-phenylpropan-2-amines. After optimisation of the asymmetric synthesis, the (R)-enantiomers could be produced with 88–89% conversion and >99% ee, while the (S)-enantiomers could be selectively obtained as the unreacted fraction of the corresponding racemic amines in kinetic resolution with >48% conversion and >95% ee.

Immobilised whole-cell (R)-transaminases (TAs) enabled synthesis of either (R)- or (S)-enantiomers of drug-like amines from prochiral ketones or from racemic amines, respectively, in >95% ee.