The role of gut hormones in glucose homeostasis

Calorie restriction activates a gastric Notch-FOXO1 pathway to expand ghrelin cells

Calorie restriction increases lifespan. Among the tissue-specific protective effects of calorie restriction, the impact on the gastrointestinal tract remains unclear. We report increased numbers of chromogranin A-positive (+), including orexigenic ghrelin+ cells, in the stomach of calorie-restricted mice. This effect was accompanied by increased Notch target Hes1 and Notch ligand Jag1 and was reversed by blocking Notch with DAPT, a gamma-secretase inhibitor. Primary cultures and genetically modified reporter mice show that increased endocrine cell abundance is due to altered Lgr5+ stem and Neurog3+ endocrine progenitor cell proliferation. Different from the intestine, calorie restriction decreased gastric Lgr5+ stem cells, while increasing a FOXO1/Neurog3+ subpopulation of endocrine progenitors in a Notch-dependent manner. Further, activation of FOXO1 was sufficient to promote endocrine cell differentiation independent of Notch. The Notch inhibitor PF-03084014 or ghrelin receptor antagonist GHRP-6 reversed the phenotypic effects of calorie restriction in mice. Tirzepatide additionally expanded ghrelin+ cells in mice. In summary, calorie restriction promotes Notch-dependent, FOXO1-regulated gastric endocrine cell differentiation.

Hydrogen sulfide produced by the gut microbiota impairs host metabolism via reducing GLP-1 levels in male mice

Dysbiosis of the gut microbiota has been implicated in the pathogenesis of metabolic syndrome (MetS) and may impair host metabolism through harmful metabolites. Here, we show that Desulfovibrio, an intestinal symbiont enriched in patients with MetS, suppresses the production of the gut hormone glucagon-like peptide 1 (GLP-1) through the production of hydrogen sulfide (H2S) in male mice. Desulfovibrio-derived H2S is found to inhibit mitochondrial respiration and induce the unfolded protein response in intestinal L cells, thereby hindering GLP-1 secretion and gene expression. Remarkably, blocking Desulfovibrio and H2S with an over-the-counter drug, bismuth subsalicylate, improves GLP-1 production and ameliorates diet-induced metabolic disorder in male mice. Together, our study uncovers that Desulfovibrio-derived H2S compromises GLP-1 production, shedding light on the gut-relayed mechanisms by which harmful microbiota-derived metabolites impair host metabolism in MetS and suggesting new possibilities for treating MetS.

Rebalancing the Gut: Glucagon-Like Peptide-1 Agonists as a Strategy for Obesity and Metabolic Health

Obesity significantly impacts gut microbial composition, exacerbating metabolic dysfunction and weight gain. Traditional treatment methods often fall short, underscoring the need for innovative approaches. Glucagon-like peptide-1 (GLP-1) agonists have emerged as promising agents in obesity management, demonstrating significant potential in modulating gut microbiota. These agents promote beneficial bacterial populations, such as Bacteroides, Lactobacillus, and Bifidobacterium, while reducing harmful species like Enterobacteriaceae. By influencing gut microbiota composition, GLP-1 agonists enhance gut barrier integrity, reducing permeability and systemic inflammation, which are hallmarks of metabolic dysfunction in obesity. Additionally, GLP-1 agonists improve metabolic functions by increasing the production of short-chain fatty acids like butyrate, propionate, and acetate, which serve as energy sources for colonocytes, modulate immune responses, and enhance the production of gut hormones that regulate appetite and glucose homeostasis. By increasing microbial diversity, GLP-1 agonists create a more resilient gut microbiome capable of resisting pathogenic invasions and maintaining metabolic balance. Thus, by shifting the gut microbiota toward a healthier profile, GLP-1 agonists help disrupt the vicious cycle of obesity-induced gut dysbiosis and inflammation. This review highlights the intricate relationship between obesity, gut microbiota, and GLP-1 agonists, providing valuable insights into their combined role in effective obesity treatment and metabolic health enhancement.

Fructooligosaccharides benefits on glucose homeostasis upon high-fat diet feeding require type 2 conventional dendritic cells

Diet composition impacts metabolic health and is now recognized to shape the immune system, especially in the intestinal tract. Nutritional imbalance and increased caloric intake are induced by high-fat diet (HFD) in which lipids are enriched at the expense of dietary fibers. Such nutritional challenge alters glucose homeostasis as well as intestinal immunity. Here, we observed that short-term HFD induced dysbiosis, glucose intolerance and decreased intestinal RORγt+ CD4 T cells, including peripherally-induced Tregs and IL17-producing (Th17) T cells. However, supplementation of HFD-fed male mice with the fermentable dietary fiber fructooligosaccharides (FOS) was sufficient to maintain RORγt+ CD4 T cell subsets and microbial species known to induce them, alongside having a beneficial impact on glucose tolerance. FOS-mediated normalization of Th17 cells and amelioration of glucose handling required the cDC2 dendritic cell subset in HFD-fed animals, while IL-17 neutralization limited FOS impact on glucose tolerance. Overall, we uncover a pivotal role of cDC2 in the control of the immune and metabolic effects of FOS in the context of HFD feeding.

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.

Analytical Methods and Effects of Bioactive Peptides Derived from Animal Products: A Mini-Review

Peptides with bioactive effects are being researched for various purposes. However, there is a lack of overall research on pork-derived peptides. In this study, we reviewed the process of obtaining bioactive peptides, available analytical methods, and the study of bioactive peptides derived from pork. Pepsin and trypsin, two representative protein digestive enzymes in the body, are hydrolyzed by other cofactors to produce peptides. Bicinchoninic acid assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, chromatography, and in vitro digestion simulation systems are utilized to analyze bioactive peptides for protein digestibility and molecular weight distribution. Pork-derived peptides mainly exhibit antioxidant and antihypertensive activities. The antioxidant activity of bioactive peptides increases the accessibility of amino acid residues by disrupting the three-dimensional structure of proteins, affecting free radical scavenging, reactive oxygen species inactivation, and metal ion chelating. In addition, the antihypertensive activity decreases angiotensin II production by inhibiting angiotensin converting enzyme and suppresses blood pressure by blocking the AT1 receptor. Pork-derived bioactive peptides, primarily obtained using papain and pepsin, exhibit significant antioxidant and antihypertensive activities, with most having low molecular weights below 1 kDa. This study may aid in the future development of bioactive peptides and serve as a valuable reference for pork-derived peptides.

Gut-Brain Axis Modulation of Metabolic Disorders: Exploring the Intertwined Neurohumoral Pathways and Therapeutic Prospects

A significant rise in metabolic disorders, frequently brought on by lifestyle choices, is alarming. A wide range of preliminary studies indicates the significance of the gut-brain axis, which regulates bidirectional signaling between the gastrointestinal tract and the cognitive system, and is crucial for regulating host metabolism and cognition. Intimate connections between the brain and the gastrointestinal tract provide a network of neurohumoral transmission that can transmit in both directions. The gut-brain axis successfully establishes that the wellness of the brain is always correlated with the extent to which the gut operates. Research on the gut-brain axis has historically concentrated on how psychological health affects how well the gastrointestinal system works. The latest studies, however, revealed that the gut microbiota interacts with the brain via the gut-brain axis to control phenotypic changes in the brain and in behavior. This study addresses the significance of the gut microbiota, the role of the gut-brain axis in management of various metabolic disorders, the hormonal and neural signaling pathways and the therapeutic treatments available. Its objective is to establish the significance of the gut-brain axis in metabolic disorders accurately and examine the link between the two while evaluating the therapeutic strategies to be incorporated in the future.

GPR119 agonists for type 2 diabetes: past failures and future hopes for preclinical and early phase candidates

INTRODUCTION

Type 2 diabetes (T2D) is metabolic disorder associated with a decrease in insulin activity and/or secretion from the β-cells of the pancreas, leading to elevated circulating glucose. Current management practices for T2D are complex with varying long-term effectiveness. Agonism of the G protein-coupled receptor GPR119 has received a lot of recent interest as a potential T2D therapeutic.

AREAS COVERED

This article reviews studies focused on GPR119 agonism in animal models of T2D and in patients with T2D.

EXPERT OPINION

GPR119 agonists in vitro and in vivo can potentially regulate incretin hormone release from the gut, then pancreatic insulin release which regulates blood glucose concentrations. However, the success in controlling glucose homeostasis in rodent models of T2D and obesity, failed to translate to early-stage clinical trials in patients with T2D. However, in more recent studies, acute and chronic dosing with the GPR119 agonist DS-8500a had increased efficacy, although this compound was discontinued for further development. New trials on GPR119 agonists are needed, however it may be that the future of GPR119 agonists lie in the development of combination therapy with other T2D therapeutics.

GLP-1(7-36) protected against oxidative damage and neuronal apoptosis in the hippocampal CA region after traumatic brain injury by regulating ERK5/CREB

BACKGROUND

Glucagon-like peptide-1 (GLP-1) (7-36) amide, an endogenous active form of GLP-1, has been shown to modulate oxidative stress and neuronal cell survival in various neurological diseases.

OBJECTIVE

This study investigated the potential effects of GLP-1(7-36) on oxidative stress and apoptosis in neuronal cells following traumatic brain injury (TBI) and explored the underlying mechanisms.

METHODS

Traumatic brain injury (TBI) models were established in male SD rats for in vivo experiments. The extent of cerebral oedema was assessed using wet-to-dry weight ratios following GLP-1(7-36) intervention. Neurological dysfunction and cognitive impairment were evaluated through behavioural experiments. Histopathological changes in the brain were observed using haematoxylin and eosin staining. Oxidative stress levels in hippocampal tissues were measured. TUNEL staining and Western blotting were employed to examine cell apoptosis. In vitro experiments evaluated the extent of oxidative stress and neural apoptosis following ERK5 phosphorylation activation. Immunofluorescence colocalization of p-ERK5 and NeuN was analysed using immunofluorescence cytochemistry.

RESULTS

Rats with TBI exhibited neurological deterioration, increased oxidative stress, and enhanced apoptosis, which were ameliorated by GLP-1(7-36) treatment. Notably, GLP-1(7-36) induced ERK5 phosphorylation in TBI rats. However, upon ERK5 inhibition, oxidative stress and neuronal apoptosis levels were elevated, even in the presence of GLP-1(7-36).

CONCLUSION

In summary, this study suggested that GLP-1(7-36) suppressed oxidative damage and neuronal apoptosis after TBI by activating ERK5/CREB.

Meckel's Diverticulum in Adult Geese (Alopochen egyptiacus): A Comprehensive Study of Structure Using Histological, Electron Microscopy, and Immunohistochemical Methods

INTRODUCTION

The intestine plays an important role in mediating between the bird and its nutritional environment. The yolk stalk, also known as Meckel's diverticulum, is a landmark between the jejunum and ileum. This work aimed to investigate the anatomical, histological, and electron microscopical features of cellular components of the Meckel's diverticulum (MD) in adult geese.

METHODS

The intestine was dissected from the bird's body cavity, and Meckel's diverticulum was exposed and prepared for light and electron microscopical examinations.

RESULTS

Our results revealed that the MD mucosa is thrown up into villi and crypts, and the mucosal epithelium is a columnar epithelium with goblet cells as well as intraepithelial lymphocytes. Lymphoid follicles and numerous immune cells were demonstrated within the lamina propria. The mucous glands were also observed within the lamina propria and among the lymphoid follicles. The lining epithelium of MD appeared with different staining affinities: dark cells (electron-dense) and light cells (electron-lucent) contained few mitochondria and more secretory vesicles, while dark cells contained more mitochondria and fewer secretory vesicles. Immunohistochemical analysis of MD revealed positive immunoreactivity for several markers, such as CD117, chromogranin, PLCβ, cytokeratin, MHC II, and S100.

CONCLUSION

Taken together, our findings suggest that MD is considered an immune organ in adult geese.

Glucagon-like peptide agonists: A prospective review

BACKGROUND

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have emerged as promising therapeutic options for addressing Type-2 diabetes, obesity, and related conditions. Among these, semaglutide, tirzepatide, liraglutide etc., all notable GLP-1RA, have gained attention owing to their favourable pharmacological properties and clinical efficacy.

AIMS

This comprehensive review aims to provide a detailed analysis of both the currently available GLP-1RAs in the market and those undergoing clinical trials. The focus is on examining their mechanism of action, pharmacokinetics, efficacy in glycemic control and weight management, safety profile, and potential applications.

MATERIALS & METHODS

The review employs a systematic approach to gather information on GLP-1RAs. Relevant literature from the currently literature and ongoing clinical trials is thoroughly examined. Detailed scrutiny is applied to understand the mechanism of action, pharmacokinetic properties, and clinical outcomes of these agents.

RESULTS

The review presents a comprehensive overview of the GLP-1RAs, highlighting their distinct mechanisms of action, pharmacokinetic profiles, and clinical effectiveness in glycemic control and weight management. Safety profiles are also discussed, providing a holistic understanding of these therapeutic agents.

DISCUSSION

The findings are discussed in the context of advancements in the field of GLP-1RAs. Potential applications beyond diabetes and obesity are explored, shedding light on the broader implications of these agents in managing related conditions.

CONCLUSION

In conclusion, this review underscores the significance of GLP-1RAs, with a specific focus on semaglutide, in the management of type 2 diabetes, obesity, and beyond. By synthesizing information on their mechanisms, pharmacokinetics, efficacy, and safety, this review provides valuable insights into the potential benefits these agents offer, contributing to the ongoing discourse in the field.

Association of Genetic Variants of HLA-DQA1 with Bullous Pemphigoid Induced by Dipeptidyl Peptidase-4 Inhibitors

Bullous pemphigoid (BP) is the most common autoimmune blistering disorder. Several factors, including an antidiabetic (dipeptidyl peptidase-4 inhibitor [DPP-4i]), have been reported to trigger BP. To identify the genetic variants associated with BP, GWAS and HLA fine-mapping analyses were conducted. The 21 cases of noninflammatory BP induced by DPP-4i (i.e., DPP-4i-induced noninflammatory BP) and 737 controls (first cohort) and the 8 cases and 164 controls (second cohort) were included in the GWAS. Combining GWAS satisfied the genome-wide significant association of HLA-DQA1 (chromosome 6, rs3129763 [T/C]) with the risk of DPP-4i-induced noninflammatory BP (allele T carrier of 72.4% [21 of 29] in cases vs. 15.3% [138 of 901] in controls; dominant model, OR = 14, P = 1.8 × 10-9). HLA fine mapping revealed that HLA-DQA1∗05 with serine at position 75 of HLA-DQα1 (Ser75) had the most significant association with the combined cohort of DPP-4i-induced noninflammatory BP (79.3% [23 of 29] cases vs. 16.1% [145 of 901] controls; dominant model, OR = 21, P = 2.0 × 10-10). HLA-DQα1 Ser75 polymorphism was located inside the functional pocket of HLA-DQ molecules, suggesting the impact of HLA-DQα1 Ser75 on DPP-4i-induced noninflammatory BP.

Glucagon-Like Peptide-1 (GLP-1) Rescue Diabetic Cardiac Dysfuntions in Human iPSC-Derived Cardiomyocytes

Glucagon-like peptide-1 (GLP-1) can improve cardiac function and cardiovascular outcomes in diabetic cardiomyopathy; however, the beneficial effect of GLP-1 on human diabetic cardiomyocytes (DCMs) and its mechanism have not been fully elucidated. Here, the DCMs model by human-induced pluripotent stem cells-derived cardiomyocytes is developed. Two subtypes of GLP-1, GLP-17-36 and GLP-19-36 , are evaluated for their efficacy on the DCMs model. Diabetogenic condition is sufficient to induce most characteristics of diabetic cardiomyopathy in vitro, such as cardiac hypertrophy, lipid accumulation, impaired calcium transients, and abnormal electrophysiological properties. GLP-17-36 and GLP-19-36 can restore cardiomyocyte hypertrophic phenotype, impaired calcium transient frequency, abnormal action potential amplitude, depolarization, and repolarization velocity. Interestingly, RNA-seq reveals different pathways altered by GLP-17-36 and GLP-19-36 , respectively. Differentially expressed gene analysis reveals that possible targets of GLP-17-36 involve the regulation of mitotic nuclear division and extracellular matrix-receptor interaction, while possible targets of GLP-19-36 involve kinetochore assembly, and the complement and coagulation cascades. This study demonstrates the therapeutic effects of GLP-1 on human DCMs and provides a novel platform to unveil the cellular mechanisms of diabetic cardiomyopathy, shedding light on discovering better targets for novel therapeutic interventions.

SIRT1 Controls Enteroendocrine Progenitor Cell Proliferation in High-Fat Diet-Fed Mice

BACKGROUND & AIMS

We aimed to investigate how sirtuin 1 (SIRT1), a conserved mammalian Nicotinamide adenine dinucleotide+-dependent protein deacetylase, regulates the number of enteroendocrine cells (EECs). EECs benefit metabolism, and their increase potentially could treat type 2 diabetes and obesity.

METHODS

We used mice with specific Sirt1 disruption in the intestinal epithelium (VilKO, villin-Cre+, and Sirt1flox/flox mice) or enteroendocrine progenitor cells (EEPCs) (NgnKO, neurogenin 3-Cre+, Sirt1flox/flox mice) and mice with increased SIRT1 activity owing to overexpression (Sir2d mice) or 24-hour fasting. Mice were fed a high-fat diet (HFD), and blood glucagon-like peptide 1 (GLP-1) and glucose levels were measured. Intestinal tissues, EECs, and formed organoids were analyzed using quantitative polymerase chain reaction, immunoblotting, and immunohistochemistry.

RESULTS

In HFD-fed VilKO and NgnKO mice, an increase in EECs (42.3% and 37.2%), GLP-1- or GLP-2-producing L cells (93.0% and 61.4%), and GLP-1 (85.7% and 109.6%) was observed after glucose loading, explaining the improved metabolic phenotype of HFD-VilKO mice. These increases were associated with up-regulated expression of neurogenin 3 (EEPC marker) in crypts of HFD-VilKO and HFD-NgnKO mice, respectively. Conversely, Sir2d or 24-hour fasted mice showed a decrease in EECs (21.6%), L cells (41.6%), and proliferative progenitor cells. SIRT1 overexpression- or knockdown-mediated change in the progenitor cell proliferation was associated with Wnt/β-catenin activity changes. Notably, Wnt/β-catenin inhibitor completely suppressed EEC and L-cell increases in HFD-VilKO mice or organoids from HFD-VilKO and HFD-NgnKO mice.

CONCLUSIONS

Intestinal SIRT1 in EECs modulates the EEPC cycle by regulating β-catenin activity and can control the number of EECs in HFD-fed mice, which is a previously unknown role.

The insulin receptor regulates the persistence of mechanical nociceptive sensitization in flies and mice

Early phase diabetes is often accompanied by pain sensitization. In Drosophila, the insulin receptor (InR) regulates the persistence of injury-induced thermal nociceptive sensitization. Whether Drosophila InR also regulates the persistence of mechanical nociceptive sensitization remains unclear. Mice with a sensory neuron deletion of the insulin receptor (Insr) show normal nociceptive baselines; however, it is uncertain whether deletion of Insr in nociceptive sensory neurons leads to persistent nociceptive hypersensitivity. In this study, we used fly and mouse nociceptive sensitization models to address these questions. In flies, InR mutants and larvae with sensory neuron-specific expression of RNAi transgenes targeting InR exhibited persistent mechanical hypersensitivity. Mice with a specific deletion of the Insr gene in Nav1.8+ nociceptive sensory neurons showed nociceptive thermal and mechanical baselines similar to controls. In an inflammatory paradigm, however, these mutant mice showed persistent mechanical (but not thermal) hypersensitivity, particularly in female mice. Mice with the Nav1.8+ sensory neuron-specific deletion of Insr did not show metabolic abnormalities typical of a defect in systemic insulin signaling. Our results show that some aspects of the regulation of nociceptive hypersensitivity by the insulin receptor are shared between flies and mice and that this regulation is likely independent of metabolic effects.

Preparation, structural properties, and in vitro and in vivo activities of peptides against dipeptidyl peptidase IV (DPP-IV) and α-glucosidase: a general review

Diabetes is one of the fastest-growing and most widespread diseases worldwide. Approximately 90% of diabetic patients have type 2 diabetes. In 2019, there were about 463 million diabetic patients worldwide. Inhibiting the dipeptidyl peptidase IV (DPP-IV) and α-glucosidase activity is an effective strategy for the treatment of type 2 diabetes. Currently, various anti-diabetic bioactive peptides have been isolated and identified. This review summarizes the preparation methods, structure-effect relationships, molecular binding sites, and effectiveness validation of DPP-IV and α-glucosidase inhibitory peptides in cellular and animal models. The analysis of peptides shows that the DPP-IV inhibitory peptides, containing 2-8 amino acids and having proline, leucine, and valine at their N-terminal and C-terminal, are the highly active peptides. The more active α-glucosidase inhibitory peptides contain 2-9 amino acids and have valine, isoleucine, and proline at the N-terminal and proline, alanine, and serine at the C-terminal.

Biomedical importance of the ubiquitin-proteasome system in diabetes and metabolic transdifferentiation of pancreatic duct epithelial cells into β-cells

The ubiquitin-proteasome system (UPS) is a major pathway for cellular protein degradation. The molecular function of the UPS is the removal of damaged proteins, and this function is applied in many biological processes, including inflammation, proliferation, and apoptosis. Accumulating evidence also suggests that the UPS also has a key role in pancreatic β-cell transdifferentiation in diabetes and can be targeted for treatment of diabetic diseases. In this review, we summarized the mechanistic roles of the UPS in the biochemical activities of pancreatic β-cells, including the role of the UPS in insulin synthesis and secretion, as well as β-cell degradation. Also, we discuss how the UPS mediates the transdifferentiation of pancreatic duct epithelial cells into β-cells as the experimental basis for the development of new strategies for the treatment of diabetes in regenerative medicine.

Calorie Restriction activates a gastric Notch-FOXO1 pathway to expand Ghrelin cells

Calorie restriction increases lifespan. While some tissue-specific protective effects of calorie restriction have been described, the impact of calorie restriction on the gastrointestinal tract remains unclear. We found increased abundance of chromogranin A+, including orexigenic ghrelin+, endocrine cells in the stomach of calorie-restricted mice. This effect coincided with increased Notch target Hes1 and Notch ligand Jag1 and was reversed when Notch signaling was blocked using the γ-secretase inhibitor DAPT. Using primary cultures and genetically-modified reporter mice, we determined that increased endocrine cell abundance was due to altered stem and progenitor proliferation. Different from the intestine, calorie restriction decreased gastric Lgr5+ stem cells, while increasing a FOXO1/Neurog3+ subpopulation of endocrine progenitors in a Notch-dependent manner. Further, calorie restriction triggered nuclear localization of FOXO1, which was sufficient to promote endocrine cell differentiation. Taken together, the data indicate that calorie restriction promotes gastric endocrine cell differentiation triggered by active Notch signaling and regulated by FOXO1.

Dipeptidyl Peptidase-4 Inhibitor Sitagliptin Phosphate Accelerates Cellular Cholesterol Efflux in THP-1 Cells

Cholesterol efflux is a major atheroprotective function of high-density lipoproteins (HDLs) which removes cholesterol from the foam cells of lipid-rich plaques in Type 2 diabetes. The dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin phosphate increases plasma glucagon-like peptide-1 (GLP-1) concentrations and is used to treat Type 2 diabetes. GLP-1 plays an important role in regulating insulin secretion and expression via the GLP-1 receptor (GLP-1R), which is expressed in pancreatic islets as well as freshly isolated human monocytes and THP-1 cells. Here, we identified a direct role of GLP-1 and DPP-4 inhibition in HDL function. Cholesterol efflux was measured in cultivated phorbol 12-myristate 13-acetate-treated THP-1 cells radiolabeled with ³H-cholesterol and stimulated with liver X receptor/retinoid X receptor agonists. Contrary to vildagliptin, sitagliptin phosphate together with GLP-1 significantly (p < 0.01) elevated apolipoprotein (apo)A1-mediated cholesterol efflux in a dose-dependent manner. The sitagliptin-induced increase in cholesterol efflux did not occur in the absence of GLP-1. In contrast, adenosine triphosphate-binding cassette transporter A1 (ABCA1) mRNA and protein expressions in the whole cell fraction were not changed by sitagliptin in the presence of GLP-1, although sitagliptin treatment significantly increased ABCA1 protein expression in the membrane fraction. Furthermore, the sitagliptin-induced, elevated efflux in the presence of GLP-1 was significantly decreased by a GLP-1R antagonist, an effect that was not observed with a protein kinase A inhibitor. To our knowledge, the present study reports for the first time that sitagliptin elevates cholesterol efflux in cultivated macrophages and may exert anti-atherosclerotic actions that are independent of improvements in glucose metabolism. Our results suggest that sitagliptin enhances HDL function by inducing a de novo HDL synthesis via cholesterol efflux.

RNA binding protein HuD mediates the crosstalk between β cells and islet endothelial cells by the regulation of Endostatin and Serpin E1 expression

RNA binding protein HuD plays essential roles in gene expression by regulating RNA metabolism, and its dysregulation is involved in the pathogenesis of several diseases, including tumors, neurodegenerative diseases, and diabetes. Here, we explored HuD-mediated differential expression of secretory proteins in mouse insulinoma βTC6 cells using a cytokine array. Endostatin and Serpin E1 that play anti-angiogenic roles were identified as differentially expressed proteins by HuD. HuD knockdown increased the expression of α chain of collagen XVIII (Col18a1), a precursor form of endostatin, and Serpin E1 by associating with the 3'-untranslated regions (UTRs) of Col18a1 and Serpin E1 mRNAs. Reporter analysis revealed that HuD knockdown increased the translation of EGFP reporters containing 3'UTRs of Col18a1 and Serpin E1 mRNAs, which suggests the role of HuD as a translational repressor. Co-cultures of βTC6 cells and pancreatic islet endothelial MS1 cells were used to assess the crosstalk between β cells and islet endothelial cells, and the results showed that HuD downregulation in βTC6 cells inhibited the growth and migration of MS1 cells. Ectopic expression of HuD decreased Col18a1 and Serpin E1 expression, while increasing the markers of islet vascular cells in the pancreas of db/db mice. Taken together, these results suggest that HuD has the potential to regulate the crosstalk between β cells and islet endothelial cells by regulating Endostatin and Serpin E1 expression, thereby contributing to the maintenance of homeostasis in the islet microenvironment.

Interventions Against Posttransplantation Diabetes: A Scientific Rationale for Treatment Hierarchy Based on Literature Review

Posttransplant diabetes (PTD) is a common medical complication after solid organ transplantation. Because of adverse outcomes associated with its development and detrimental impact on long-term survival, strategies to prevent or manage PTD are critically important but remain underresearched. Treatment hierarchies of antidiabetic therapies in the general population are currently being revolutionized based on cardiovascular outcome trials, providing evidence-based rationale for optimization of medical management. However, opportunities for improving medical management of PTD are challenged by 2 important considerations: (1) translating clinical evidence data from the general population to underresearched solid organ transplant cohorts and (2) targeting treatment based on primary underlying PTD pathophysiology. In this article, the aim is to provide an overview of PTD treatment options from a new angle. Rationalized by a consideration of underlying PTD pathophysiological defects, which are heterogeneous among diverse transplant patient cohorts, a critical appraisal of the published literature and summary of current research in progress will be reviewed. The aim is to update transplant professionals regarding medical management of PTD from a new perspective tailored therapeutic intervention based on individualized characteristics. As the gap in clinical evidence between management of PTD versus type 2 diabetes widens, it is imperative for the transplant community to bridge this gap with targeted clinical trials to ensure we optimize outcomes for solid organ transplant recipients who are at risk or develop PTD. This necessary clinical research should help efforts to improve long-term outcomes for solid transplant patients from both a patient and graft survival perspective.

Periodontitis and implant complications in diabetes

Epidemiologic evidence indicates that periodontitis is more frequent in patients with uncontrolled diabetes mellitus than in healthy controls, suggesting that it could be considered the "sixth complication" of diabetes. Actually, diabetes mellitus and periodontitis are two extraordinarily prevalent chronic diseases that share a number of comorbidities all converging toward an increased risk of cardiovascular disease. Periodontal treatment has recently been shown to have the potential to improve the metabolic control of diabetes, although long-term studies are lacking. Uncontrolled diabetes also seems to affect the response to periodontal treatment, as well as the risk to develop peri-implant diseases. Mechanisms of associations between diabetes mellitus and periodontal disease include the release of advanced glycation end products as a result of hyperglycemia and a range of shared predisposing factors of genetic, microbial, and lifestyle nature. This review discusses the evidence for the risk of periodontal and peri-implant disease in diabetic patients and the potential role of the dental professional in the diabetes-periodontal interface.

The Metabolic Role and Therapeutic Potential of the Microbiome

We are host to an assembly of microorganisms that vary in structure and function along the length of the gut and from the lumen to the mucosa. This ecosystem is collectively known as the gut microbiota and significant efforts have been spent during the past 2 decades to catalog and functionally describe the normal gut microbiota and how it varies during a wide spectrum of disease states. The gut microbiota is altered in several cardiometabolic diseases and recent work has established microbial signatures that may advance disease. However, most research has focused on identifying associations between the gut microbiota and human diseases states and to investigate causality and potential mechanisms using cells and animals. Since the gut microbiota functions on the intersection between diet and host metabolism, and can contribute to inflammation, several microbially produced metabolites and molecules may modulate cardiometabolic diseases. Here we discuss how the gut bacterial composition is altered in, and can contribute to, cardiometabolic disease, as well as how the gut bacteria can be targeted to treat and prevent metabolic diseases.

Reprogramming—Evolving Path to Functional Surrogate β-Cells

Numerous cell sources are being explored to replenish functional β-cell mass since the proof-of -concept for cell therapy of diabetes was laid down by transplantation of islets. Many of these cell sources have been shown to possess a degree of plasticity permitting differentiation along new lineages into insulin-secreting β-cells. In this review, we explore emerging reprograming pathways that aim to generate bone fide insulin producing cells. We focus on small molecules and key transcriptional regulators that orchestrate phenotypic conversion and maintenance of engineered cells.

Factors associated with hypertension remission after gastrectomy for gastric cancer patients

BACKGROUND

Previous studies reported hypertension remission after gastrectomy for gastric cancer patients, and the remission rate was 11.1%-93.8%. We have reported the factors of hypertension remission previously, however, the follow-up time was six months. It is necessary to identify risk factors for hypertension for a relatively longer follow-up time.

AIM

To analyze the predictive factors for hypertension remission one year after gastrectomy of gastric cancer patients and to construct a risk model for hypertension remission.

METHODS

We retrospectively collected the medical information of patients with concurrent gastric cancer and hypertension in a single clinical center from January 2013 to December 2020. Univariate and multivariate logistic regression of hypertension remission were conducted, and a nomogram model was established.

RESULTS

A total of 209 patients with concurrent gastric cancer and hypertension were included in the current study. There were 108 patients in the remission group and 101 patients in the non-remission group. The hypertension remission rate was 51.7% one year after gastrectomy. The remission group had younger aged patients (P = 0.001), larger weight loss (P = 0.001), lower portion of coronary heart disease (P = 0.017), higher portion of II-degree hypertension (P = 0.033) and higher portion of total gastrectomy (P = 0.008) than the non-remission group. Younger age (P = 0.011, odds ratio = 0.955, 95%CI: 0.922-0.990), higher weight loss (P = 0.019, odds ratio = 0.937, 95%CI: 0.887-0.989) and total gastrectomy (P = 0.039, odds ratio = 2.091, 95%CI: 1.037-4.216) were independent predictors for hypertension remission. The concordance index of the model was 0.769 and the calibration curve suggested great agreement. Furthermore, decision curve analysis showed that the model was clinically useful.

CONCLUSION

Younger age, higher weight loss and total gastrectomy were independent predictors for hypertension remission after gastrectomy for gastric cancer patients. The nomogram could visually display these results.

The promising role of probiotics/prebiotics/synbiotics in energy metabolism biomarkers in patients with NAFLD: A systematic review and meta-analysis

Background

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease with a high prevalence worldwide, seriously harming human health, and its pathogenesis remains unclear. In recent years, increasing evidence has indicated that intestinal microbiota plays an important role in the occurrence and development of NAFLD. The regulation method of probiotics/prebiotics/synbiotics can alter the intestinal microbiota and has been suggested as an option in the treatment of NAFLD.

Methods

Five databases of PubMed, Embase, the Cochrane Library, clinicaltrails.gov, and China National Knowledge Infrastructure were searched initially, and then the eligible studies were screened. Finally, the data of included studieswere extracted, combined and analyzed

Results

A total of 29 randomized controlled trials involving 2,110 patients were included in this study. The results showed that using probiotics/prebiotics/synbiotics in the intervention group could reduce the levels of glucose (SMD = −0.23, 95% CI [−0.45, −0.01], P = 0.04), HOMA-IR (SMD = −0.47, 95% CI [−0.63, −0.31], P < 0.00001) and insulin (SMD = −0.46, 95% CI [−0.76, −0.16], P = 0.002) in sugar metabolism; in terms of lipid metabolism, the levels of TC (SMD = −0.62, 95%CI [−0.87, −0.36], P < 0.00001), and LDL-C (SMD = −0.57, 95%CI [−0.85, −0.28], P < 0.00001) were decreased; and the level of ALB was decreased in protein metabolism (SMD = −0.34, 95%CI [−0.61, −0.06], P = 0.02).

Conclusions

Based on the current evidence, probiotics/prebiotics/synbiotics may improve energy metabolism biomarkers in the NAFLD population, but these effects still need to be confirmed by further research.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/#aboutpage.

Identification of the DPP-IV Inhibitory Peptides from Donkey Blood and Regulatory Effect on the Gut Microbiota of Type 2 Diabetic Mice

After being treated with protease K, peptides extracted from donkey blood were separated, identified, and characterized. The results showed that Sephadex G-25 medium purified with MW < 3 kDa had the highest dipeptidyl peptidase IV (DPP-IV) inhibition capacity. Three-hundred-and-thirty-four peptides were identified with UPLC−MS/MS. Peptide Ranker and molecular docking analysis were used to screen active peptides, and 16 peptides were finalized out of the 334. The results showed that the lowest binding energy between P7(YPWTQ) and DPP-IV was −9.1, and the second-lowest binding energy between P1(VDPENFRLL) and DPP-IV was −8.7. The active peptides(MW < 3 kDa) could cause a reduction in the fasting blood glucose levels of type 2 diabetic mice, improve glucose tolerance, and facilitate healing of the damaged structure of diabetic murine liver and pancreas. Meanwhile, the peptides were found to ameliorate the diabetic murine intestinal micro-ecological environment to a certain extent.

Oncometabolic surgery in gastric cancer patients with type 2 diabetes

The rates of early gastric cancer and type 2 diabetes mellitus(T2DM) are sharply increasing in Korea. Oncometabolic surgery in which metabolic surgery is conducted along with cancer surgery is a method used to treat gastric cancer and T2DM in one-stage operation. From 2011 to 2019, a total of 48 patients underwent long-limb Roux-en-Y gastrectomy (LRYG) in Inha University Hospital, and all data were reviewed retrospectively. A 75 g oral glucose tolerance test and serum insulin level test were performed before and 1 week and 1 year after surgery. One year after LRYG operation, 25 of 48 patients showed complete or partial remission and 23 patients showed non-remission of T2DM. The preoperative HbA1c level was significantly lower and the change in HbA1c was significantly greater in the T2DM remission group. Insulin secretion indices(insulinogenic index and disposition index) were increased significantly in the T2DM remission group. In contrast, the insulin resistance indices (homeostatic model assessment of insulin resistance (HOMA-IR) and Matsuda index) changed minimal. In the case of LRYG in T2DM patients, remnant β cell function is an important predictor of favorable glycemic control.

Dietary Glucose Ameliorates Impaired Intestinal Development and Immune Homeostasis Disorders Induced by Chronic Cold Stress in Pig Model

Endotherms are easily challenged by chronic cold stress. In this study, the development and injury of the small intestine in the Min pig model and Yorkshire pig model under chronic cold stress, and the molecular mechanisms by which glucose supplementation reduces small intestinal mucosal damage were investigated. The results showed that morphological structure lesions of the jejunal mucosa and ileal mucosa were visible in Yorkshire pigs under chronic cold stress. Meanwhile, the Occludin mRNA and protein expression in jejunal mucosa of Yorkshire pigs was decreased. Chronic cold stress enhanced the expression of Toll-like receptor 4 (TLR4), the myeloid differentiation main response 88 (MyD88), nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3), cleaved caspase-1, mature-IL-1β, and high-mobility group box 1 (HMGB 1) mRNA and protein expression in jejunal mucosa of Yorkshire pigs, whereas the mRNA and protein of Bax was triggered in ileal mucosa. In Min pigs, no such deleterious consequences were observed. Dietary glucose supplementation ameliorates small intestinal mucosal injury, declined TLR4 and MyD88 expression in jejunal mucosa. In conclusion, chronic cold stress induced the small intestinal mucosa damage in Yorkshire pigs, whereas glucose supplementation mitigated the deleterious effects of chronic cold stress on the small intestine.

Interrupting Prolonged Sitting with Intermittent Walking Increases Postprandial Gut Hormone Responses

INTRODUCTION

Continuous exercise can increase postprandial gut hormone such as glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) responses, but it is unknown whether interrupting prolonged sitting with intermittent walking elicits this effect.

METHOD

Ten participants with central overweight/obesity (7 men and 3 postmenopausal women, 51 ± 5 yr; mean ± SD) completed a randomized crossover study in which they consumed breakfast and lunch in the laboratory while either sitting continuously for the entire 5.5-h period (SIT) or the prolonged sitting interrupted every 20 min by walking briskly (6.4 km·h-1) for 2 min (BREAKS). Blood samples were collected at regular intervals to examine postprandial plasma GLP-1, PYY, and glucose-dependent insulinotropic polypeptide concentrations. Adipose tissue samples were collected at baseline and at the end of the trials to examine changes in net dipeptidyl peptidase 4 secretion from primary explants.

RESULTS

Mean (95% confidence interval) postprandial GLP-1 and PYY incremental area under curve values were elevated by 26% and 31% in the BREAKS trial versus SIT (8.4 [0.7, 16.1] vs 6.7 [-0.8, 14.2], P = 0.001, and 26.9 [8.1, 45.6] vs 20.4 [5.1, 35.8] nmol·330 min·L-1, P = 0.024, respectively) but without any such effect on glucose-dependent insulinotropic polypeptide (P = 0.076) or net adipose tissue dipeptidyl peptidase 4 secretion (P > 0.05).

CONCLUSIONS

Interrupting prolonged sitting with regular short bouts of brisk walking increases postprandial GLP-1 and PYY concentrations in healthy middle-age men and women with central adiposity.

Effects of Three Different Modes of Resistance Training on Appetite Hormones in Males With Obesity

Purpose

This study explored the effect of three different modes of resistance training on appetite hormones [leptin, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide tyrosine–tyrosine (PYY)], cardiometabolic and anthropometric measures in males with obesity.

Methods

Forty-four males with obesity (age: 27.5 ± 9.4 yrs.; mean weight: 93.2 ± 2.2 kg, body mass index: 32.9 ± 1.2 kg/m²) were randomized to traditional resistance training (TRT, n = 11), circuit resistance training (CRT, n = 11), interval resistance training (IRT, n = 11) or control (C, n = 11) groups. All resistance training groups received 50 min of supervised training per session, three days per week, for 12 weeks. Measurements were taken at baseline and after 12 weeks of training.

Results

Plasma levels of leptin, ghrelin, CCK, and PYY decreased significantly in all three different modalities of resistance training groups when compared to the control group (p < 0.05). GLP-1 increased significantly in both CRT and IRT groups compared to TRT and C groups (p < 0.05). Glucose-dependent insulinotropic polypeptide decreased significantly in CRT and IRT groups compared to the C group (p < 0.05). Adiponectin levels increased significantly in all resistance training groups compared to the C group (p < 0.05).

Conclusion

Overall, CRT and IRT protocols had the greatest impact on appetite hormones compared to individuals who engaged in TRT or did not exercise (C).

Adansonia digitata L. (Baobab Fruit) Effect on Postprandial Glycemia in Healthy Adults: A Randomized Controlled Trial

Baobab fruits have been traditionally used in Africa due to their therapeutic properties attributed to their high polyphenol content. The aim of the study was to investigate the effect of baobab fruit on postprandial glycaemia in healthy adults and to measure its bioactive compounds and antioxidant activity. The study (NCT05140629) was conducted on 31 healthy subjects. The participants were randomly allocated in the control group (oral glucose tolerance test (OGTT); n = 16) and in the intervention group (OGTT, followed by administration of 250 mL baobab aqueous extract (BAE); n = 15). Total phenols, proanthocyanins, hydrolyzable tannins, and antioxidant activity (FRAP, DPPH, ABTS, and inhibition of O2^•− and NO^• methods) were quantified. Repeated measures ANOVA of mixed type and independent samples t-test were used. Glycemia incremental area under the curve (p = 0.012) and glucose maximum concentration (p = 0.029) was significantly lower in the intervention group compared to the control group. The BAE revealed high total contents of phenols, proanthocyanins, and hydrolyzable tannins, as well as a strong capacity to scavenge superoxide anions and nitric oxide radicals and a high antioxidant activity. In conclusion, this study encourages the use of this food component as a promising source of natural antioxidants and a hypoglycemic agent under glucose load acute conditions.

Intestinal HIF-2α Regulates GLP-1 Secretion via Lipid Sensing in L-Cells

BACKGROUND & AIMS

Compelling evidence shows that glucagon-like peptide-1 (GLP-1) has a profound effect in restoring normoglycemia in type 2 diabetic patients by increasing pancreatic insulin secretion. Although L-cells are the primary source of circulating GLP-1, the current therapies do not target L-cells to increase GLP-1 levels. Our study aimed to determine the molecular underpinnings of GLP-1 secretion as an impetus to identify new interventions to target endogenous L-cells.

METHODS

We used genetic mouse models of intestine-specific overexpression of hypoxia-inducible factor (HIF)-1α and HIF-2α (Vhl^ΔIE), conditional overexpression of intestinal HIF-2α (Hif-2α^{LSL;Vilin-Cre/ERT2}), and intestine-specific HIF-2α knockout mice (Hif-2α^ΔIE) to show that HIF signaling, especially HIF-2α, regulates GLP-1 secretion.

RESULTS

Our data show that intestinal HIF signaling improved glucose homeostasis in a GLP-1-dependent manner. Intestinal HIF potentiated GLP-1 secretion via the lipid sensor G-protein-coupled receptor (GPR)40 enriched in L-cells. We show that HIF-2α regulates GPR40 in L-cells and potentiates fatty acid-induced GLP-1 secretion via extracellular regulated kinase (ERK). Using a genetic model of intestine-specific overexpression of HIF-2α, we show that HIF-2α is sufficient to increase GLP-1 levels and attenuate diet-induced metabolic perturbations such as visceral adiposity, glucose intolerance, and hepatic steatosis. Lastly, we show that intestinal HIF-2α signaling acts as a priming mechanism crucial for postprandial lipid-mediated GLP-1 secretion. Thus, disruption of intestinal HIF-2α decreases GLP-1 secretion.

CONCLUSIONS

In summary, we show that intestinal HIF signaling, particularly HIF-2α, regulates the lipid sensor GPR40, which is crucial for the lipid-mediated GLP-1 secretion, and suggest that HIF-2α is a potential target to induce endogenous GLP-1 secretion.

Psidium guajava leaf extract improves gastrointestinal functions in rats and rabbits: an implication for ulcer and diarrhoea management

PURPOSE

Psidium guajava L. (Family, Myrtaceae) is reportedly used in ethnomedicine for the treatment of diarrhoea, inflammation, and gastroenteritis.

OBJECTIVE

This study evaluated the gastrointestinal function of Psidium guajava leaf extract (PGLE) in rats and rabbits.

MATERIALS AND METHODS

Crude ethanolic PGLE was subjected to phytochemical and toxicity tests (acute and sub-acute). Standard analytical procedures were employed to evaluate the in vivo gastrointestinal motility, and gastroprotective effect of PGLE against aspirin-induced ulcers.

RESULTS

In the phytochemical analysis, phenols were the highest (48.32 mg) followed by flavonoids (32.74 mg) and least in tannins (7.31 mg). The acute toxicity of PGLE was >6000 mg/kg. Administration of PGLE decreased significantly (p < 0.05) the body weight, while the liver biomarkers were not significantly altered (p > 0.05) when compared to the control. PGLE significantly increased extractible mucus weight and lowered gastric acid secretion in rats (p < 0.05). PGLE decreased significantly (p < 0.05) ulcer scores and indexes, and increased percentage ulcer inhibition in a dose-dependent manner compared to the negative and omeprazole-treated groups. PGLE dose-dependently inhibited basal amplitudes of contractions, and significantly inhibited acetylcholine-induced contractions, terminating them completely at higher doses.

CONCLUSION

PGLE may be a good anti-ulcer and anti-diarrhoeal agent, raising the prospect of novel drug development for such applications.

Association of single nucleotide polymorphisms with insulin secretion, insulin sensitivity, and diabetes in women with a history of gestational diabetes mellitus

Background

This study investigated whether single nucleotide polymorphisms (SNPs) reported by previous genome-wide association studies (GWAS) to be associated with impaired insulin secretion, insulin resistance, and/or type 2 diabetes are associated with disposition index, the homeostasis model assessment of insulin resistance (HOMA-IR), and/or development of diabetes following a pregnancy complicated by gestational diabetes mellitus (GDM).

Methods

Seventy-two SNPs were genotyped in 374 women with previous GDM from Southern Sweden. An oral glucose tolerance test was performed 1–2 years postpartum, although data on the diagnosis of diabetes were accessible up to 5 years postpartum. HOMA-IR and disposition index were used to measure insulin resistance and secretion, respectively.

Results

The risk A-allele in the rs11708067 polymorphism of the adenylate cyclase 5 gene (ADCY5) was associated with decreased disposition index (beta = − 0.90, SE 0.38, p = 0.019). This polymorphism was an expression quantitative trait loci (eQTL) in islets for both ADCY5 and its antisense transcript. The risk C-allele in the rs2943641 polymorphism, near the insulin receptor substrate 1 gene (IRS1), showed a trend towards association with increased HOMA-IR (beta = 0.36, SE 0.18, p = 0.050), and the T-allele of the rs4607103 polymorphism, near the ADAM metallopeptidase with thrombospondin type 1 motif 9 gene (ADAMTS9), was associated with postpartum diabetes (OR = 2.12, SE 0.22, p = 0.00055). The genetic risk score (GRS) of the top four SNPs tested for association with the disposition index using equal weights was associated with the disposition index (beta = − 0.31, SE = 0.29, p = 0.00096). In addition, the GRS of the four SNPs studied for association with HOMA-IR using equal weights showed an association with HOMA-IR (beta = 1.13, SE = 0.48, p = 9.72874e−11). All analyses were adjusted for age, body mass index, and ethnicity.

Conclusions

This study demonstrated the genetic susceptibility of women with a history of GDM to impaired insulin secretion and sensitivity and, ultimately, to diabetes development.

Is Colectomy Associated with the Risk of Type 2 Diabetes in Patients without Colorectal Cancer? A Population-Based Cohort Study

Type 2 diabetes might be influenced by colonic disease; however, the association between colonic resection and type 2 diabetes has rarely been discussed. This population-based cohort study explored the association between colectomy and type 2 diabetes in patients without colorectal cancer. A total of 642 patients who underwent colectomy for noncancerous diseases at any time between 2000 and 2012 in the National Health Insurance Research Database of Taiwan were enrolled. The enrolled patients were matched with 2568 patients without colectomy at a 1:4 ratio using a propensity score that covered age, sex, and comorbidities. The risk of type 2 diabetes was assessed using a Cox proportional hazards model. The mean (standard deviation) follow-up durations in colectomy cases and non-colectomy controls were 4.9 (4.0) and 5.6 (3.6) years, respectively; 65 (10.1%) colectomy cases and 342 (15.5%) non-colectomy controls developed type 2 diabetes. After adjustment, colectomy cases still exhibited a decreased risk of type 2 diabetes (adjusted HR = 0.80, 95% CI: 0.61–1.04). A stratified analysis for colectomy type indicated that patients who underwent right or transverse colectomy had a significantly lower risk of developing type 2 diabetes (adjusted HR = 0.57, 95% CI: 0.34–0.98). In the present study, colectomy tended to be at a reduced risk of type 2 diabetes in patients without colorectal cancer, and right or transverse colectomies were especially associated with a significantly reduced risk of type 2 diabetes.

Theories behind the effect of starch‑ and sucrose‑reduced diets on gastrointestinal symptoms in irritable bowel syndrome (Review)

Increased amounts of starch and sugar have been added to the diet in the Western world during the last decades. Undigested carbohydrates lead to bacterial fermentation and gas production with diffusion of water, causing abdominal bloating, pain and diarrhea. Therefore, dietary advice is the first line of treatment of irritable bowel syndrome (IBS), a disease characterized by abdominal pain and altered bowel habits without any organic findings. Recently, a diet with a reduction of starch and sucrose led to a marked effect on gastrointestinal (GI) symptoms. The mechanism is unknown, but three possible mechanisms are presented in the present review. First, functional variants of the enzyme sucrase‑isomaltase (SI) have been described in IBS. A subgroup of patients with IBS may thus suffer from partial SI deficiency with reduced digestion of starch and sucrose. Second, fructose absorption is less efficient than glucose absorption, which may lead to a physiological fructose malabsorption when ingesting high amounts of sucrose. A third mechanism is that high‑sugar diets causing hyperglycemia, hyperinsulinemia and weight gain have led to painful neuropathy in animal models; whereas, improved metabolic control in humans has led to improvement of neuropathy. Starch‑ and sucrose‑reduced diets lead to decreased levels of C‑peptide, insulin, gastric inhibitory peptide, leptin and weight reduction. These metabolic changes may reduce the excitability of the hypersensitive nervous system often found in IBS and, thereby, lead to the reduced symptoms found after the diet. In conclusion, further studies are needed to investigate the pathophysiology behind development of symptoms after starch and sucrose intake, and the mechanisms behind symptom relief after reduced intake.

Progress in treatment of type 2 diabetes by bariatric surgery

The incidence of type 2 diabetes (T2D) is increasing at an alarming rate worldwide. Bariatric surgical procedures, such as the vertical sleeve gastrectomy and Roux-en-Y gastric bypass, are the most efficient approaches to obtain substantial and durable remission of T2D. The benefits of bariatric surgery are realized through the consequent increased satiety and alterations in gastrointestinal hormones, bile acids, and the intestinal microbiota. A comprehensive understanding of the mechanisms by which various bariatric surgical procedures exert their benefits on T2D could contribute to the design of better non-surgical treatments for T2D. In this review, we describe the classification and evolution of bariatric surgery and explore the multiple mechanisms underlying the effect of bariatric surgery on insulin resistance. Based upon our summarization of the current knowledge on the underlying mechanisms, we speculate that the gut might act as a new target for improving T2D. Our ultimate goal with this review is to provide a better understanding of T2D pathophysiology in order to support development of T2D treatments that are less invasive and more scalable.

Identification of Multiple Pancreatic and Extra-Pancreatic Pathways Underlying the Glucose-Lowering Actions of Acacia arabica Bark in Type-2 Diabetes and Isolation of Active Phytoconstituents

Acacia arabica is used traditionally to treat a variety of ailments, including diabetes. This study elucidated the antidiabetic actions of A. arabica bark together with the isolation of bioactive molecules. Insulin secretion and signal transduction were measured using clonal β cells and mouse islets. Glucose uptake was assessed using 3T3-L1 adipocytes, and in vitro systems assessed additional glucose-lowering actions. High-fat-fed (HFF) obese rats were used for in vivo evaluation, and phytoconstituents were isolated and characterised by RP-HPLC followed by LC-MS and NMR. Hot-water extract of A. arabica (HWAA) increased insulin release from clonal β cells and mouse islets by 1.3-6.8-fold and 1.6-3.2-fold, respectively. Diazoxide, verapamil and calcium-free conditions decreased insulin-secretory activity by 30-42%. In contrast, isobutylmethylxanthine (IBMX), tolbutamide and 30 mM KCl potentiated the insulin-secretory effects. The mechanism of actions of HWAA involved membrane depolarisation and elevation of intracellular Ca2+ together with an increase in glucose uptake by 3T3-L1 adipocytes, inhibition of starch digestion, glucose diffusion, dipeptidyl peptidase-IV (DPP-IV) enzyme activity and protein glycation. Acute HWAA administration (250 mg/5 mL/kg) enhanced glucose tolerance and plasma insulin in HFF obese rats. Administration of HWAA (250 mg/5 mL/kg) for 9 days improved glucose homeostasis and β-cell functions, thereby improving glycaemic control, and circulating insulin. Isolated phytoconstituents, including quercetin and kaempferol, increased insulin secretion in vitro and improved glucose tolerance. The results indicate that HWAA has the potential to treat type 2 diabetes as a dietary supplement or as a source of antidiabetic agents, including quercetin and kaempferol.

Therapeutic potential of targeting intestinal bitter taste receptors in diabetes associated with dyslipidemia

Intestinal release of incretin hormones after food intake promotes glucose-dependent insulin secretion and regulates glucose homeostasis. The impaired incretin effects observed in the pathophysiologic abnormality of type 2 diabetes have triggered the pharmacological development of incretin-based therapy through the activation of glucagon-like peptide-1 (GLP-1) receptor, including GLP-1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase 4 (DPP4) inhibitors. In the light of the mechanisms involved in the stimulation of GLP-1 secretion, it is a fundamental question to explore whether glucose and lipid homeostasis can be manipulated by the digestive system in response to nutrient ingestion and taste perception along the gastrointestinal tract. While glucose is a potent stimulant of GLP-1 secretion, emerging evidence highlights the importance of bitter tastants in the enteroendocrine secretion of gut hormones through activation of bitter taste receptors. This review summarizes bitter chemosensation in the intestines for GLP-1 secretion and metabolic regulation based on recent advances in biological research of bitter taste receptors and preclinical and clinical investigation of bitter medicinal plants, including bitter melon, hops strobile, and berberine-containing herbs (e.g. coptis rhizome and barberry root). Multiple mechanisms of action of relevant bitter phytochemicals are discussed with the consideration of pharmacokinetic studies. Current evidence suggests that specific agonists targeting bitter taste receptors, such as human TAS2R1 and TAS2R38, may provide both metabolic benefits and anti-inflammatory effects with the modulation of the enteroendocrine hormone secretion and bile acid turnover in metabolic syndrome individuals or diabetic patients with dyslipidemia-related comorbidities.

The gut microbiota regulates hypothalamic inflammation and leptin sensitivity in Western diet-fed mice via a GLP-1R-dependent mechanism

Mice lacking a microbiota are protected from diet-induced obesity. Previous studies have shown that feeding a Western diet causes hypothalamic inflammation, which in turn can lead to leptin resistance and weight gain. Here, we show that wild-type (WT) mice with depleted gut microbiota, i.e., germ-free (GF) and antibiotic-treated mice, have elevated levels of glucagon-like peptide-1 (GLP-1), are protected against diet-induced hypothalamic inflammation, and have enhanced leptin sensitivity when fed a Western diet. Using GLP-1 receptor (GLP-1R)-deficient mice and pharmacological inhibition of the GLP-1R in WT mice, we demonstrate that intact GLP-1R signaling is required for preventing hypothalamic inflammation and enhancing leptin sensitivity. Furthermore, we show that astrocytes express the GLP-1R, and deletion of the receptor in glial fibrillary acidic protein (GFAP)-expressing cells diminished the antibiotic-induced protection against diet-induced hypothalamic inflammation. Collectively, our results suggest that depletion of the gut microbiota attenuates diet-induced hypothalamic inflammation and enhances leptin sensitivity via GLP-1R-dependent mechanisms.

Effect of oligofructose on resistance to postoperative high-fat diet-induced damage of metabolism in diabetic rats after sleeve gastrectomy

BACKGROUND

Sleeve gastrectomy (SG) can induce prominent remission of type 2 diabetes mellitus. However, the long-term remission rate of diabetes usually decreases over time. Oligofructose has been verified to modulate host metabolism. The aim of this study was to explore the protective effect of oligofructose on high-fat diet (HFD)-induced metabolic dysfunction after SG.

AIM

To study the effect and mechanism of oligofructose on diabetic remission in diabetic rats after SG.

METHODS

SG and SHAM operation were performed on diabetes rats induced with an HFD, nicotinamide, and low-dose streptozotocin. Then the rats in the SHAM and SG groups were continuously provided with the HFD, and the rats in sleeve gastrectomy-oligofructose group were provided with a specific HFD containing 10% oligofructose. Body weight, calorie intake, oral glucose tolerance test, homeostasis model assessment of insulin resistance, lipid profile, serum insulin, glucagon-like peptide 1 (GLP-1), total bile acids, lipopolysaccharide (LPS), and colonic microbiota levels were determined and compared at the designated time points. All statistical analyses were performed using Statistic Package for Social Science version 19.0 (IBM, United States), and the statistically significant difference was considered at P < 0.05.

RESULTS

At 2 wk after surgery, rats that underwent SG exhibited improved indexes of glucose and lipid metabolism. Compared with the SG group, the rats from SG-oligofructose group exhibited better parameters of glucose and lipid metabolism, lower body weight (526.86 ± 21.51 vs 469.25 ± 21.84, P < 0.001), calorie intake (152.14 ± 9.48 vs 129.63 ± 8.99, P < 0.001), homeostasis model assessment of insulin resistance (4.32 ± 0.57 vs 3.46 ± 0.52, P < 0.05), and LPS levels (0.19 ± 0.01 vs 0.16 ± 0.01, P < 0.05), and higher levels of insulin (1.17 ± 0.17 vs 1.58 ± 0.16, P < 0.001) and GLP-1 (12.39 ± 1.67 vs 14.94 ± 1.86, P < 0.001), and relative abundances of Bifidobacterium (0.0034 ± 0.0014 vs 0.0343 ± 0.0064, P < 0.001), Lactobacillus (0.0161 ± 0.0037 vs 0.0357 ± 0.0047, P < 0.001), and Akkermansia muciniphila (0.0050 ± 0.0024 vs 0.0507 ± 0.0100, P < 0.001) at the end of the study. However, no difference in total bile acids levels was observed between the two groups.

CONCLUSION

Oligofructose partially prevents HFD-induced glucose and lipid metabolism damage after SG, which may be due to the changes of calorie intake, insulin, GLP-1, LPS, and the gut microbiota in rats.

Assessing Different Temporal Scales of Calcium Dynamics in Networks of Beta Cell Populations

Beta cells within the pancreatic islets of Langerhans respond to stimulation with coherent oscillations of membrane potential and intracellular calcium concentration that presumably drive the pulsatile exocytosis of insulin. Their rhythmic activity is multimodal, resulting from networked feedback interactions of various oscillatory subsystems, such as the glycolytic, mitochondrial, and electrical/calcium components. How these oscillatory modules interact and affect the collective cellular activity, which is a prerequisite for proper hormone release, is incompletely understood. In the present work, we combined advanced confocal Ca2+ imaging in fresh mouse pancreas tissue slices with time series analysis and network science approaches to unveil the glucose-dependent characteristics of different oscillatory components on both the intra- and inter-cellular level. Our results reveal an interrelationship between the metabolically driven low-frequency component and the electrically driven high-frequency component, with the latter exhibiting the highest bursting rates around the peaks of the slow component and the lowest around the nadirs. Moreover, the activity, as well as the average synchronicity of the fast component, considerably increased with increasing stimulatory glucose concentration, whereas the stimulation level did not affect any of these parameters in the slow component domain. Remarkably, in both dynamical components, the average correlation decreased similarly with intercellular distance, which implies that intercellular communication affects the synchronicity of both types of oscillations. To explore the intra-islet synchronization patterns in more detail, we constructed functional connectivity maps. The subsequent comparison of network characteristics of different oscillatory components showed more locally clustered and segregated networks of fast oscillatory activity, while the slow oscillations were more global, resulting in several long-range connections and a more cohesive structure. Besides the structural differences, we found a relatively weak relationship between the fast and slow network layer, which suggests that different synchronization mechanisms shape the collective cellular activity in islets, a finding which has to be kept in mind in future studies employing different oscillations for constructing networks.

Molecular mechanisms of β-cell dysfunction and death in monogenic forms of diabetes

Monogenetic forms of diabetes represent 1%-5% of all diabetes cases and are caused by mutations in a single gene. These mutations, that affect genes involved in pancreatic β-cell development, function and survival, or insulin regulation, may be dominant or recessive, inherited or de novo. Most patients with monogenic diabetes are very commonly misdiagnosed as having type 1 or type 2 diabetes. The severity of their symptoms depends on the nature of the mutation, the function of the affected gene and, in some cases, the influence of additional genetic or environmental factors that modulate severity and penetrance. In some patients, diabetes is accompanied by other syndromic features such as deafness, blindness, microcephaly, liver and intestinal defects, among others. The age of diabetes onset may also vary from neonatal until early adulthood manifestations. Since the different mutations result in diverse clinical presentations, patients usually need different treatments that range from just diet and exercise, to the requirement of exogenous insulin or other hypoglycemic drugs, e.g., sulfonylureas or glucagon-like peptide 1 analogs to control their glycemia. As a consequence, awareness and correct diagnosis are crucial for the proper management and treatment of monogenic diabetes patients. In this chapter, we describe mutations causing different monogenic forms of diabetes associated with inadequate pancreas development or impaired β-cell function and survival, and discuss the molecular mechanisms involved in β-cell demise.

Endothelial Cell-Derived Triosephosphate Isomerase Attenuates Insulin Secretion From Pancreatic Beta Cells of Male Rats

Insulin secretion from pancreatic beta cells is tightly regulated by glucose and paracrine signals within the microenvironment of islets of Langerhans. Extracellular matrix from islet microcapillary endothelial cells (IMEC) affect beta-cell spreading and amplify insulin secretion. This study was aimed at investigating the hypothesis that contact-independent paracrine signals generated from IMEC may also modulate beta-cell insulin secretory functions. For this purpose, conditioned medium (CMp) preparations were prepared from primary cultures of rat IMEC and were used to simulate contact-independent beta cell-endothelial cell communication. Glucose-stimulated insulin secretion (GSIS) assays were then performed on freshly isolated rat islets and the INS-1E insulinoma cell line, followed by fractionation of the CMp, mass spectroscopic identification of the factor, and characterization of the mechanism of action. The IMEC-derived CMp markedly attenuated first- and second-phase GSIS in a time- and dose-dependent manner without altering cellular insulin content and cell viability. Size exclusion fractionation, chromatographic and mass-spectroscopic analyses of the CMp identified the attenuating factor as the enzyme triosephosphate isomerase (TPI). An antibody against TPI abrogated the attenuating activity of the CMp while recombinant human TPI (hTPI) attenuated GSIS from beta cells. This effect was reversed in the presence of tolbutamide in the GSIS assay. In silico docking simulation identified regions on the TPI dimer that were important for potential interactions with the extracellular epitopes of the sulfonylurea receptor in the complex. This study supports the hypothesis that an effective paracrine interaction exists between IMEC and beta cells and modulates glucose-induced insulin secretion via TPI-sulfonylurea receptor-KATP channel (SUR1-Kir6.2) complex attenuating interactions.

The Emerging Role of Polyphenols in the Management of Type 2 Diabetes

Type 2 diabetes (T2D) is a fast-increasing health problem globally, and it results from insulin resistance and pancreatic β-cell dysfunction. The gastrointestinal (GI) tract is recognized as one of the major regulatory organs of glucose homeostasis that involves multiple gut hormones and microbiota. Notably, the incretin hormone glucagon-like peptide-1 (GLP-1) secreted from enteroendocrine L-cells plays a pivotal role in maintaining glucose homeostasis via eliciting pleiotropic effects, which are largely mediated via its receptor. Thus, targeting the GLP-1 signaling system is a highly attractive therapeutic strategy to treatment T2D. Polyphenols, the secondary metabolites from plants, have drawn considerable attention because of their numerous health benefits, including potential anti-diabetic effects. Although the major targets and locations for the polyphenolic compounds to exert the anti-diabetic action are still unclear, the first organ that is exposed to these compounds is the GI tract in which polyphenols could modulate enzymes and hormones. Indeed, emerging evidence has shown that polyphenols can stimulate GLP-1 secretion, indicating that these natural compounds might exert metabolic action at least partially mediated by GLP-1. This review provides an overview of nutritional regulation of GLP-1 secretion and summarizes recent studies on the roles of polyphenols in GLP-1 secretion and degradation as it relates to metabolic homeostasis. In addition, the effects of polyphenols on microbiota and microbial metabolites that could indirectly modulate GLP-1 secretion are also discussed.

Electronic medical records-based comparison of glycemic control efficacy between sulfonylureas and dipeptidyl peptidase-4 inhibitors added on to metformin monotherapy in patients with type 2 diabetes

Sulfonylurea (SU) and dipeptidyl peptidase-4 (DPP-4) inhibitors are most common secondary agents that are added to metformin monotherapy. Real-world studies have become increasingly important in providing evidence of treatment effectiveness in clinical practice and real-world data could help appropriate therapeutic information. Therefore, this study aims to compare the glycemic effectiveness of SU and DPP-4 inhibitors, which are added to metformin monotherapy in real clinical practice using electronic medical record (EMR) data. EMR data of type 2 diabetes patients treated at Seoul National University Hospital from December 2002 to December 2012 were retrieved and analyzed. The patients were divided into three groups: patients who maintained metformin monotherapy (M), and patients who added SU (MS) or DPP-4 inhibitors (MD) to metformin monotherapy. The mean change in HbA1c level, the proportion of patients achieving the HbA1c target < 7.0%, proportion of patients with treatment failure, and probability of treatment failure occurrence and changes in prescription were evaluated to compare glycemic control efficacy between SU and DPP-4 inhibitors. The MS showed significantly greater reduction in the Hb1Ac level than MD. The proportion of patients achieving HbA1c < 7.0% is higher in MD, whereas the proportion of patients with treatment failure was greater in MS. The probability of the treatment failure and probability of changes in the prescription were lower in MD than MS with hazard ratio of 0.499 and 0.579, respectively. In conclusion, this real-world study suggested that DPP-4 inhibitors are expected to show more durable glycemic control efficacy than SU in long-term use.

Morph-anatomic and histochemical study of ileum of goose (Alopochen egyptiacus) with special references to immune cells, mucous and serous goblet cells, telocytes, and dark and light smooth muscle fibers

The morphological characteristics of the ileum of 20 adult male Egyptian geese were determined using LM, SEM, and TEM. The mean length of the ileum in the male goose was approximately 158.71 mm, representing nearly 10.19% of the total length of the small intestine. The ileum is composed of four layers: mucosa, submucosa, muscular layer, and serosa. The mucosal layer comprises the epithelium, lamina propria, and muscularis mucosa. The mucosa forms finger-like villi and is invaginated at the bases, forming the crypts of Lieberkühn. The ileum is lined by simple columnar epithelium that contains absorptive dark and light enterocytes with two types of goblet cells (mucous and serous varieties) microfold like cells, dendritic reticulum cells, Paneth cells, and a closed type of enteroendocrine cells. The lamina propria has diffuse lymphoid tissue containing lymphocytes, macrophages, mast cells, plasma cells, and heterophils as well as telocytes. The muscularis mucosa comprises circular smooth muscle fibers extending into the core of the villi. The submucosa is a thin layer of elastic-rich connective tissue. The muscular level consists of four layers, with light and dark smooth muscle fibers. We described in detail the structure of all cellular components and histomorphometric measurements.

To Assess Liraglutide's Therapeutic Effect in Patients with Type 2 Diabetes Mellitus Using Flash Glucose Monitoring System

PURPOSE

Liraglutide, a type of glucagon-like peptide-1 receptor agonist, has significant anti-hyperglycaemic activity without increasing the incidence of hypoglycaemia. In addition, it can improve β-cell function and insulin resistance. The flash glucose monitoring system (FGMS) is a novel method to document consecutive and detailed interstitial glucose levels, further reflecting blood glucose levels. This study aimed to investigate the therapeutic effect of liraglutide on blood glucose management (glucose variability, hyperglycaemia, and the incidence of hypoglycaemia), β-cell function, and insulin resistance in patients with diabetes.

PATIENTS AND METHODS

Thirty-three patients with type 2 diabetes mellitus were recruited in this study. On the basis of metformin monotherapy, these patients received liraglutide add-on treatment for 3 months. The FGMS was used to document glucose levels before and after add-on treatment. Parameters of glucose variability, blood glucose levels at specific time periods, and the incidence of hypoglycaemia were assessed according to FGMS data and compared before and after liraglutide add-on treatment. Further, β-cell function and insulin resistance were assessed and compared before and after liraglutide add-on treatment.

RESULTS

According to FGMS monitoring data, liraglutide add-on treatment significantly improved general, within-day, and day-to-day glucose variability and the glucose-target-rate. Further, the specifically analysed blood glucose levels at different time periods showed that blood glucose levels significantly decreased at nocturnal, fasting, and postprandial periods after add-on treatment. The incidence of hypoglycaemia was comparable during the whole day, daytime, and night-time according to the prespecified cutoffs (3.9 mmol/L and 3.0 mmol/L) before and after add-on treatment. Analysis of other assessed parameters revealed significant differences in glycosylated hemoglobin A1c and fasting blood glucose levels as well as parameters of β-cell function and insulin resistance before and after add-on treatment.

CONCLUSION

In type 2 diabetes mellitus, liraglutide treatment can effectively decrease glucose variability and ameliorate hyperglycaemia without increasing the incidence of hypoglycaemia. In addition, liraglutide can significantly improve the β-cell function and insulin resistance.

A carbohydrate-restricted diet for patients with irritable bowel syndrome lowers serum C-peptide, insulin, and leptin without any correlation with symptom reduction

Alterations in gut endocrine cells and hormone levels have been measured in patients with irritable bowel syndrome (IBS). The hypothesis of the present study was that hormone levels would change after 4 weeks of a starch- and sucrose-reduced diet (SSRD) intervention corresponding to decreased carbohydrate intake and symptoms. Among 105 IBS patients from primary and tertiary healthcare, 80 were randomized to SSRD, while 25 followed their ordinary diet. Food diaries, Rome IV, and IBS-symptom severity score (IBS-SSS) questionnaires were completed, and blood samples were collected at baseline and after the intervention. Serum C-peptide, gastric inhibitory peptide, glucagon, glucagon-like peptide-1, insulin, leptin, luteinizing hormone, polypeptide YY, and glucose were measured, along with the prevalence of autoantibodies against gonadotropin-releasing hormone; its precursor, progonadoliberin-2, and receptor; and tenascin C. Carbohydrate intake was lower in the intervention group than in controls at week 4 (median: 88 [66-128] g vs 182 [89-224] g; P < .001). The change in carbohydrate intake, adjusted for weight, was associated with a decrease in C-peptide (β: 14.43; 95% confidence interval [CI]: 4.12-24.75) and insulin (β: 0.18; 95% CI: 0.04-0.32) levels. Glucose levels remained unchanged. The IBS-SSS scores were lower in the intervention group but not in controls (P < .001), without any association with changes in hormone concentrations. There was no difference in autoantibody prevalence between patients and healthy controls. In conclusion, the hypothesis that reduced carbohydrate intake corresponded to altered hormonal levels in IBS was accepted; however, there was no relationship between hormonal concentrations and symptoms.