Enteroendocrine Hormone Secretion and Metabolic Control: Importance of the Region of the Gut Stimulation

Proximal small intestinal bypass outperforms Roux-en-Y and jejunoileal bypass in glucose regulation in streptozotocin induced diabetic rats

BACKGROUND

The efficacy of various bariatric surgeries varies in reducing blood glucose levels. Given the distinct mechanisms and anatomical alterations associated with each procedure, it is crucial to compare their glycemic control outcomes. We hypothesize that proximal small intestinal bypass (PSIB) is superior in blood glucose reduction over Roux-en-Y gastric bypass (RYGB) and jejunoileal bypass (JIB).

AIM

To compare the effectiveness of PSIB, RYGB, and JIB in lowering blood glucose.

METHODS

Rats with streptozotocin-induced diabetes were randomly divided into PSIB, RYGB, JIB, and sham-operated groups. Body weight, food intake, fasting blood glucose level, oral glucose tolerance test, insulin tolerance test, liver enzymes, and blood lipids were measured.

RESULTS

Postoperatively, only the JIB group had a lower body weight compared to the sham group. The food intake of the rats in all three surgical groups was significantly less than that in the sham group. Fasting blood glucose was reduced in all surgical groups and was lower in the PSIB group than in the RYGB and JIB groups. Glucose tolerance and insulin sensitivity improved in all three surgical groups compared to the sham group, but the improvement appeared earliest in the PSIB group. At six weeks post-surgery, the PSIB group showed a reduction in alanine transaminase levels and maintained a normal lipid profile.

CONCLUSION

PSIB demonstrated excellent hypoglycemic effects in the early postoperative period, and had better efficacy than RYGB and JIB.

Select microbial metabolites in the small intestinal lumen regulate vagal activity via receptor-mediated signaling

The vagus nerve is proposed to enable communication between the gut microbiome and the brain, but activity-based evidence is lacking. We find that mice reared germ-free exhibit decreased vagal tone relative to colonized controls, which is reversed via microbiota restoration. Perfusing antibiotics into the small intestines of conventional mice, but not germ-free mice, acutely decreases vagal activity which is restored upon re-perfusion with intestinal filtrates from conventional, but not germ-free, mice. Microbiome-dependent short-chain fatty acids, bile acids, and 3-indoxyl sulfate indirectly stimulate vagal activity in a receptor-dependent manner. Serial perfusion of each metabolite class activates both shared and distinct neuronal subsets with varied response kinetics. Metabolite-induced and receptor-dependent increases in vagal activity correspond with the activation of brainstem neurons. Results from this study reveal that the gut microbiome regulates select metabolites in the intestinal lumen that differentially activate vagal afferent neurons, thereby enabling the microbial modulation of chemosensory signals for gut-brain communication.

Evaluation of l-cell activity in the small intestine according to the extension of the biliopancreatic loop in patients undergoing Roux-en-Y gastric by-pass

BACKGROUND

Individuals with severe obesity and type 2 diabetes mellitus have reduced secretion of incretins by L cells. Studies suggest an increase in L cell activity according to the length of the Biliopancreatic Loop (BPL).

OBJECTIVE

Compare the effect of biliopancreatic loop extension on the number and expression of L cells in patients undergoing RYGB METHODS: Subjects (n = 13) undergoing RYGB with a BPL of 100 cm (G1) or 200 cm (G2). Intestinal biopsies were done before (T1) and 6 months after (T2) RYGB in 3 segments: gastro-enteric anastomosis (A), entero-enteric anastomosis (B) and terminal ileum (C). Analyzes of intestinal biopsies by immunohistochemistry and qRT-PCR.

RESULTS

There was an increase (p < 0.0001) in L cells marked by PYY and GLP1 between T1 (17 ± 10.5) and T2 (23.5 ± 10.7) only at point C. There was no difference in L cells expression between groups G1 and G2 at points A (A1: 17.3 ± 2.9; A2: 19.9 ± 1.9; p = 0.09), B (B1: 13.7 ± 6.6; B2: 14.1 ± 4.9; p = 0.89) and C (C1: 13.2 ± 2.2; C2: 11.4 ± 3.4; p = 0.32) in PYY and GLP1 gene expression (A1: 20.8 ± 4, 1; A2: 23.7 ± 3.6; p = 0.2), B (B1:14.3 ± 7.9; B2: 22.7 ± 11.8; p = 0.1), (C1: 17±4.1; C2: 21.1 ± 4.8; p = 0.2).

CONCLUSIONS

Both techniques lead to an increase in the number of active L cells.

Network pharmacology, molecular docking and experimental validation to elucidate the anti-T2DM mechanism of Lanxangia tsaoko

Lanxangia tsaoko (L. tsaoko) is a natural medicine which could be used to treat type 2 diabetes mellitus (T2DM). However, there is no systematic and comprehensive research on the its active compounds and mechanism. This study aimed to investigate the active ingredients and potential mechanism of L. tsaoko for the treatment of T2DM. The chemical constituents of L. tsaoko were identified by UPLC-Q-Exactive Orbitrap/MS. The active compounds and mechanism of L. tsaoko were predicted by network pharmacology. Then the docking modes of key components and core targets were analyzed by molecular docking. Finally, animal experiments were conducted to verify the efficacy and targets of L. tsaoko in T2DM treatment. 70 compounds from L. tsaoko were identified. We obtained 37 active components, including quercetin, genistein and kaempferol, 5 core targets were AKT1, INS, TP53, TNF and IL-6. Mainly involved in PI3K/Akt, MAPK, RAGE/AGE, HIF-1, FoxO signaling pathways. Molecular docking results showed that the L. tsaoko had good binding potential to TNF. Therefore, we took the inflammatory mechanism as the prediction target for experimental verification. Animal experiments showed that L. tsaoko could alleviated colon injury of T2DM mice, improve glucose metabolism and decrease inflammatory levels. L. tsaoko exerted therapeutic effects on T2DM through multi-component, multi-target and multi-pathway regulation. Its action mechanisms were related to PI3K/Akt, MAPK, RAGE/AGE, HIF-1 and FoxO signaling pathways. This study provided new insights for the clinical treatment of T2DM.

Manipulation of Post-Prandial Hyperglycaemia in Type 2 Diabetes: An Update for Practitioners

This review paper explores post-prandial glycemia in type 2 diabetes. Post-prandial glycemia is defined as the period of blood glucose excursion from immediately after the ingestion of food or drink to 4 to 6 hours after the end of the meal. Post-prandial hyperglycemia is an independent risk factor for cardiovascular disease with glucose "excursions" being more strongly associated with markers of oxidative stress than the fasting or pre-prandial glucose level. High blood glucose is a major promoter of enhanced free radical production and is associated with the onset and progression of type 2 diabetes. Oxidative stress impairs insulin action creating a vicious cycle where repeated post-prandial glucose spikes are key drivers in the pathogenesis of the vascular complications of type 2 diabetes, both microvascular and macrovascular. Some authors suggest post-prandial hyperglycemia is the major cause of death in type 2 diabetes. Proper management of post-prandial hyperglycemia could yield up to a 35% cut in overall cardiovascular events, and a 64% cut in myocardial infarction. The benefits of managing post-prandial hyperglycemia are similar in magnitude to those seen in type 2 diabetes patients receiving secondary prevention with statins - prevention which today is regarded as fundamental by all practitioners. Given all the evidence surrounding the impact of post-prandial glycemia on overall outcome, it is imperative that any considered strategy for the management of type 2 diabetes should include optimum dietary, pharma, and lifestyle interventions that address glucose excursion. Achieving a low post-prandial glucose response is key to prevention and progression of type 2 diabetes and cardiometabolic diseases. Further, such therapeutic interventions should be sustainable and must benefit patients in the short and long term with the minimum of intrusion and side effects. This paper reviews the current literature around dietary manipulation of post-prandial hyperglycemia, including novel approaches. A great deal of further work is required to optimize and standardize the dietary management of post-prandial glycemia in type 2 diabetes, including consideration of novel approaches that show great promise.

The central role of the gut microbiota in the pathophysiology and management of type 2 diabetes

The inhabitants of our intestines, collectively called the gut microbiome, comprise fungi, viruses, and bacterial strains. These microorganisms are involved in the fermentation of dietary compounds and the regulation of our adaptive and innate immune systems. Less known is the reciprocal interaction between the gut microbiota and type 2 diabetes mellitus (T2DM), as well as their role in modifying therapies to reduce associated morbidity and mortality. In this review, we aim to discuss the existing literature on gut microbial strains and their diet-derived metabolites involved in T2DM. We also explore the potential diagnostics and therapeutic avenues the gut microbiota presents for targeted T2DM management. Personalized treatment plans, driven by diet and medication based on the patient's microbiome and clinical markers, could optimize therapy.

Impact of the timing of metformin administration on glycaemic and glucagon-like peptide-1 responses to intraduodenal glucose infusion in type 2 diabetes: a double-blind, randomised, placebo-controlled, crossover study

AIMS/HYPOTHESIS

Metformin lowers postprandial glycaemic excursions in individuals with type 2 diabetes by modulating gastrointestinal function, including the stimulation of glucagon-like peptide-1 (GLP-1). The impact of varying the timing of metformin administration on postprandial glucose metabolism is poorly defined. We evaluated the effects of metformin, administered at different intervals before an intraduodenal glucose infusion, on the subsequent glycaemic, insulinaemic and GLP-1 responses in metformin-treated type 2 diabetes.

METHODS

Sixteen participants with type 2 diabetes that was relatively well-controlled by metformin monotherapy were studied on four separate days in a crossover design. On each day, participants were randomised to receive a bolus infusion of metformin (1000 mg in 50 ml 0.9% saline) via a nasoduodenal catheter at t = -60, -30 or 0 min (and saline at the other timepoints) or saline at all timepoints (control), followed by an intraduodenal glucose infusion of 12.56 kJ/min (3 kcal/min) at t = 0-60 min. The treatments were blinded to both participants and investigators involved in the study procedures. Plasma glucose, insulin and total GLP-1 levels were measured every 30 min between t = -60 min and t = 120 min.

RESULTS

There was a treatment-by-time interaction for metformin in reducing plasma glucose levels and increasing plasma GLP-1 and insulin levels (p<0.05 for each). The reduction in plasma glucose levels was greater when metformin was administered at t = -60 or -30 min vs t = 0 min (p<0.05 for each), and the increases in plasma GLP-1 levels were evident only when metformin was administered at t = -60 or -30 min (p<0.05 for each). Although metformin did not influence insulin sensitivity, it enhanced glucose-induced insulin secretion (p<0.05), and the increases in plasma insulin levels were comparable on the 3 days when metformin was given.

CONCLUSIONS/INTERPRETATION

In well-controlled metformin-treated type 2 diabetes, glucose-lowering by metformin is greater when it is given before, rather than with, enteral glucose, and this is associated with a greater GLP-1 response. These observations suggest that administration of metformin before meals may optimise its effect in improving postprandial glycaemic control.

TRIAL REGISTRATION

www.anzctr.org.au ACTRN12621000878875 FUNDING: The study was not funded by a specific research grant.

Effect of vegetable consumption with chewing on postprandial glucose metabolism in healthy young men: a randomised controlled study

Although thorough chewing lowers postprandial glucose concentrations, research on the effectiveness of chewing vegetables in different forms on postprandial glucose metabolism remains limited. This study examined the effects of vegetables consumed in solid versus puree forms on postprandial glucose metabolism. Nineteen healthy young men completed two 180-min trials on separate days in a random order: the chewing trial involved the consumption of shredded cabbage with chewing and the non-chewing trial involved the consumption of pureed cabbage without chewing. Energy jelly was consumed immediately after the consumption of shredded or puree cabbage. Blood samples were collected at 0, 30, 45, 60, 90, 120 and 180 min. Circulating concentrations of glucose, insulin, total glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) concentrations were measured from the plasma. Although plasma glucose concentrations did not differ between the trials, the plasma insulin and GIP incremental area under the curve values were higher in the chewing than in the non-chewing trial. Postprandial total GLP-1 concentrations were higher in the chewing than in the non-chewing trial at 45, 60 and 90 min. This study demonstrates that consuming shredded cabbage while chewing enhances postprandial incretin secretion but has no effect on postprandial glucose concentration.Trial registration: Clinical trial registration ID.: UMIN000052662, registered 31 October 2023.

Secretome Analysis: Reading Cellular Sign Language to Understand Intercellular Communication

A significant portion of mammalian proteomes is secreted to the extracellular space to fulfill crucial roles in cell-to-cell communication. To best recapitulate the intricate and multi-faceted crosstalk between cells in a live organism, there is an ever-increasing need for methods to study protein secretion in model systems that include multiple cell types. In addition, posttranslational modifications further expand the complexity and versatility of cellular communication. This review aims to summarize recent strategies and model systems that employ cellular coculture, chemical biology tools, protein enrichment, and proteomic methods to characterize the composition and function of cellular secretomes. This is all geared towards gaining better understanding of organismal biology in vivo mediated by secretory signaling.

The impacts and mechanisms of dietary proteins on glucose homeostasis and food intake: a pivotal role of gut hormones

Glucose and energy metabolism disorders are the main reasons induced type 2 diabetes (T2D) and obesity. Besides providing energy, dietary nutrients could regulate glucose homeostasis and food intake via intestinal nutrient sensing induced gut hormone secretion. However, reviews regarding intestinal protein sensing are very limited, and no accurate information is available on their underlying mechanisms. Through intestinal protein sensing, dietary proteins regulate glucose homeostasis and food intake by secreting gut hormones, such as glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY (PYY) and glucose-dependent insulinotropic polypeptide (GIP). After activating the sensory receptors, such as calcium-sensing receptor (CaSR), peptide transporter-1 (PepT1), and taste 1 receptors (T1Rs), protein digests induced Ca2+ influx and thus triggered gut hormone release. Additionally, research models used to study intestinal protein sensing have been emphasized, especially several innovative models with excellent physiological relevance, such as co-culture cell models, intestinal organoids, and gut-on-a-chips. Lastly, protein-based dietary strategies that stimulate gut hormone secretion and inhibit gut hormone degradation are proposed for regulating glucose homeostasis and food intake.

Disparities in the Glycemic and Incretin Responses to Intraduodenal Glucose Infusion Between Healthy Young Men and Women

CONTEXT

Premenopausal women are at a lower risk of type 2 diabetes (T2D) compared to men, but the underlying mechanism(s) remain elusive. The secretion of the incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), from the small intestine is a major determinant of glucose homeostasis and may be influenced by sex.

OBJECTIVES

This study compared blood glucose and plasma insulin and incretin responses to intraduodenal glucose infusions in healthy young males and females.

DESIGN

In Study 1, 9 women and 20 men received an intraduodenal glucose infusion at 2 kcal/min for 60 minutes. In Study 2, 10 women and 26 men received an intraduodenal glucose at 3 kcal/min for 60 minutes. Venous blood was sampled every 15 minutes for measurements of blood glucose and plasma insulin, GLP-1 and GIP.

RESULTS

In response to intraduodenal glucose at 2 kcal/min, the incremental area under the curve between t = 0-60 minutes (iAUC0-60min) for blood glucose and plasma GIP did not differ between the 2 groups. However, iAUC0-60min for plasma GLP-1 (P = 0.016) and insulin (P = 0.011) were ∼2-fold higher in women than men. In response to intraduodenal glucose at 3 kcal/min, iAUC0-60min for blood glucose, plasma GIP, and insulin did not differ between women and men, but GLP-1 iAUC0-60min was 2.5-fold higher in women (P = 0.012).

CONCLUSION

Healthy young women exhibit comparable GIP but a markedly greater GLP-1 response to intraduodenal glucose than men. This disparity warrants further investigations to delineate the underlying mechanisms and may be of relevance to the reduced risk of diabetes in premenopausal women when compared to men.

Gut Molecules in Cardiometabolic Diseases: The Mechanisms behind the Story

Atherosclerotic cardiovascular disease is the most common cause of morbidity and mortality worldwide. Diabetes mellitus increases cardiovascular risk. Heart failure and atrial fibrillation are associated comorbidities that share the main cardiovascular risk factors. The use of incretin-based therapies promoted the idea that activation of alternative signaling pathways is effective in reducing the risk of atherosclerosis and heart failure. Gut-derived molecules, gut hormones, and gut microbiota metabolites showed both positive and detrimental effects in cardiometabolic disorders. Although inflammation plays a key role in cardiometabolic disorders, additional intracellular signaling pathways are involved and could explain the observed effects. Revealing the involved molecular mechanisms could provide novel therapeutic strategies and a better understanding of the relationship between the gut, metabolic syndrome, and cardiovascular diseases.

Involvement of Intestinal Enteroendocrine Cells in Neurological and Psychiatric Disorders

Neurological and psychiatric patients have increased dramatically in number in the past few decades. However, effective treatments for these diseases and disorders are limited due to heterogeneous and unclear pathogenic mechanisms. Therefore, further exploration of the biological aspects of the disease, and the identification of novel targets to develop alternative treatment strategies, is urgently required. Systems-level investigations have indicated the potential involvement of the brain–gut axis and intestinal microbiota in the pathogenesis and regulation of neurological and psychiatric disorders. While intestinal microbiota is crucial for maintaining host physiology, some important sensory and regulatory cells in the host should not be overlooked. Intestinal epithelial enteroendocrine cells (EECs) residing in the epithelium throughout intestine are the key regulators orchestrating the communication along the brain-gut-microbiota axis. On one hand, EECs sense changes in luminal microorganisms via microbial metabolites; on the other hand, they communicate with host body systems via neuroendocrine molecules. Therefore, EECs are believed to play important roles in neurological and psychiatric disorders. This review highlights the involvement of EECs and subtype cells, via secretion of endocrine molecules, in the development and regulation of neurological and psychiatric disorders, including Parkinson’s disease (PD), schizophrenia, visceral pain, neuropathic pain, and depression. Moreover, the current paper summarizes the potential mechanism of EECs in contributing to disease pathogenesis. Examination of these mechanisms may inspire and lead to the development of new aspects of treatment strategies for neurological and psychiatric disorders in the future.

Effects of ileal glucose infusion on enteropancreatic hormone secretion in humans: relationship to glucose absorption

BACKGROUNDS

The distal small intestine plays an important role in regulating the secretion of entero-pancreatic hormones that are critical to the control of glucose metabolism and appetite, but the quantitative contribution of a specific segment to these effects is unknown.

PURPOSES

To determine the effects of 30 cm of the ileum exposed to glucose on the secretion of ghrelin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) insulin, C-peptide and glucagon, in relation to glucose absorption in non-diabetic subjects.

BASIC PROCEDURES

10 non-diabetic subjects with a loop ileostomy after early-stage rectal cancer resection were studied on 2 days in a double-blind, randomized and crossover fashion, when a catheter was inserted retrogradely 30 cm from the ileostomy for infusion of a glucose solution containing 30 g glucose and 3 g 3-O-methylglucose (as a marker of active glucose absorption), or 0.9% saline, over 60 min. Ghrelin, GIP, GLP-1, insulin, C-peptide, glucagon and ileal glucose absorption (from concentrations of 3-O-methylglucose in serum and glucose in ileostomy effluent) were measured over 180 min.

MAIN FINDINGS

12.0 ± 1.2 g glucose was absorbed over 180 min. Compared to saline, ileal glucose resulted in minimal increases in blood glucose and plasma insulin and C-peptide, but substantial increases in plasma GLP-1, without affecting ghrelin, GIP or glucagon. The magnitude of the GLP-1 response to glucose was strongly related to the increase in serum 3-O-methylglucose.

PRINCIPAL CONCLUSIONS

Stimulation of the terminal ileum by glucose, even over a short length (30 cm), induces substantial GLP-1 release, coupled primarily to active glucose absorption.

CLINICAL REGISTRATION

NCT05030376 (ClinicalTrials.gov).

Serum bile acid response to oral glucose is attenuated in patients with early type 2 diabetes and correlates with 2-hour plasma glucose in individuals without diabetes

AIM

To determine the serum bile acid (BA) response to 75-g oral glucose in individuals without diabetes, and whether this is attenuated in patients with 'early' type 2 diabetes (T2D) and related to the glycaemic response at 2 hours in either group.

METHODS

Forty newly diagnosed, treatment-naïve Han Chinese T2D subjects and 40 age-, gender-, and body mass index-matched controls without T2D ingested a 75-g glucose drink after an overnight fast. Plasma glucose and serum concentrations of total and individual BAs, fibroblast growth factor-19 (FGF-19), total glucagon-like peptide-1 (GLP-1), and insulin, were measured before and 2 hours after oral glucose.

RESULTS

Fasting total BA levels were higher in T2D than control subjects (P < .05). At 2 hours, the BA profile exhibited a shift from baseline in both groups, with increases in conjugated BAs and/or decreases in unconjugated BAs. There were increases in total BA and FGF-19 levels in control (both P < .05), but not T2D, subjects. Plasma glucose concentrations at 2 hours related inversely to serum total BA levels in control subjects (r = -0.42, P = .006). Total GLP-1 and the insulin/glucose ratio were increased at 2 hours in both groups, and the magnitude of the increase was greater in control subjects.

CONCLUSIONS

The serum BA response to a 75-g oral glucose load is attenuated in patients with 'early' T2D, as is the secretion of FGF-19 and GLP-1, while in individuals without T2D it correlates with 2-hour plasma glucose levels. These observations support a role for BAs in the regulation of postprandial glucose metabolism.

Enteroendocrine cell differentiation and function in the intestine

PURPOSE OF REVIEW

The intestinal enteroendocrine cells (EECs) are specialized hormone-secreting cells that respond to both circulating and luminal cues. Collectively, EECs constitute the largest endocrine organ of the body and signal to a multitude of targets including locally to neighboring intestinal cells, enteric neurons, as well as systemically to other organs, such as the pancreas and brain. To accomplish their wide range of downstream signaling effects, EECs secrete multiple hormones; however, the mechanisms that influence EEC development in the embryo and differentiation in adults are not well defined.

RECENT FINDINGS

This review highlights the recent discoveries in EEC differentiation and function while also discussing newly revealed roles of transcription factors and signaling networks involved in the allocation of EEC subtypes that were discovered using a combination of novel intestinal model systems and genetic sequencing. We also discuss the potential of these new experimental models that study the mechanisms regulating EEC function and development both to uncover novel therapeutic targets.

SUMMARY

Several EEC hormones are being used to treat various metabolic disorders, such as type 2 diabetes and obesity. Therefore, understanding the signaling pathways and gene regulatory networks that facilitate EEC formation is paramount to the development of novel therapies.

Plasma GLP-1 Response to Oral and Intraduodenal Nutrients in Health and Type 2 Diabetes-Impact on Gastric Emptying

CONTEXT

Both gastric emptying and the secretion of glucagon-like peptide-1 (GLP-1) are major determinants of postprandial glycemia in health and type 2 diabetes (T2D). GLP-1 secretion after a meal is dependent on the entry of nutrients into the small intestine, which, in turn, slows gastric emptying.

OBJECTIVE

To define the relationship between gastric emptying and the GLP-1 response to both oral and small intestinal nutrients in subjects with and without T2D.

METHODS

We evaluated: (i) the relationship between gastric emptying (breath test) and postprandial GLP-1 levels after a mashed potato meal in 73 individuals with T2D; (ii) inter-individual variations in GLP-1 response to (a) intraduodenal glucose (4 kcal/min) during euglycemia and hyperglycemia in 11 healthy and 12 T2D, subjects, (b) intraduodenal fat (2 kcal/min) in 15 T2D subjects, and (c) intraduodenal protein (3 kcal/min) in 10 healthy subjects; and (iii) the relationship between gastric emptying (breath test) of 75 g oral glucose and the GLP-1 response to intraduodenal glucose (4 kcal/min) in 21 subjects (9 healthy, 12 T2D).

RESULTS

The GLP-1 response to the mashed potato meal was unrelated to the gastric half-emptying time (T50). The GLP-1 responses to intraduodenal glucose, fat, and protein varied substantially between individuals, but intra-individual variation to glucose was modest. The T50 of oral glucose was related directly to the GLP-1 response to intraduodenal glucose (r = 0.65, P = 0.002).

CONCLUSION

In a given individual, gastric emptying is not a determinant of the postprandial GLP-1 response. However, the intrinsic gastric emptying rate is determined in part by the responsiveness of GLP-1 to intestinal nutrients.

Patient-Wise Methodology to Assess Glycemic Health Status: Applications to Quantify the Efficacy and Physiological Targets of Polyphenols on Glycemic Control

A growing body of evidence indicates that dietary polyphenols could be used as an early intervention to treat glucose-insulin (G-I) dysregulation. However, studies report heterogeneous information, and the targets of the intervention remain largely elusive. In this work, we provide a general methodology to quantify the effects of any given polyphenol-rich food or formulae over glycemic regulation in a patient-wise manner using an Oral Glucose Tolerance Test (OGTT). We use a mathematical model to represent individual OGTT curves as the coordinated action of subsystems, each one described by a parameter with physiological interpretation. Using the parameter values calculated for a cohort of 1198 individuals, we propose a statistical model to calculate the risk of dysglycemia and the coordination among subsystems for each subject, thus providing a continuous and individual health assessment. This method allows identifying individuals at high risk of dysglycemia—which would have been missed with traditional binary diagnostic methods—enabling early nutritional intervention with a polyphenol-supplemented diet where it is most effective and desirable. Besides, the proposed methodology assesses the effectiveness of interventions over time when applied to the OGTT curves of a treated individual. We illustrate the use of this method in a case study to assess the dose-dependent effects of Delphinol® on reducing dysglycemia risk and improving the coordination between subsystems. Finally, this strategy enables, on the one hand, the use of low-cost, non-invasive methods in population-scale nutritional studies. On the other hand, it will help practitioners assess the effectiveness of an intervention based on individual vulnerabilities and adapt the treatment to manage dysglycemia and avoid its progression into disease.

Inflammatory bowel disease and diabetes: Is there a link between them?

Patients with inflammatory bowel disease (IBD) are reported to have an increased risk of diabetes. IBD therapies may also modulate blood glucose substantially. These observations are indicative of mechanistic connection(s) between IBD and diabetes.

One Giant Leap from Mouse to Man: The Microbiota-Gut-Brain Axis in Mood Disorders and Translational Challenges Moving towards Human Clinical Trials

The microbiota–gut–brain axis is a bidirectional communication pathway that enables the gut microbiota to communicate with the brain through direct and indirect signaling pathways to influence brain physiology, function, and even behavior. Research has shown that probiotics can improve several aspects of health by changing the environment within the gut, and several lines of evidence now indicate a beneficial effect of probiotics on mental and brain health. Such evidence has prompted the arrival of a new term to the world of biotics research: psychobiotics, defined as any exogenous influence whose effect on mental health is bacterially mediated. Several taxonomic changes in the gut microbiota have been reported in neurodevelopmental disorders, mood disorders such as anxiety and depression, and neurodegenerative disorders such as Alzheimer’s disease. While clinical evidence supporting the role of the gut microbiota in mental and brain health, and indeed demonstrating the beneficial effects of probiotics is rapidly accumulating, most of the evidence to date has emerged from preclinical studies employing different animal models. The purpose of this review is to focus on the role of probiotics and the microbiota–gut–brain axis in relation to mood disorders and to review the current translational challenges from preclinical to clinical research.

Sensing Intra‐ and Extra‐Cellular Ca2+ in the Islet of Langerhans

Calcium ions (Ca2+) take part in intra‐ and inter‐cellular signaling to mediate cellular functions. Sensing this ubiquitous messenger is instrumental in disentangling the specific functions of cellular sub‐compartments and/or intercellular communications. In this review, the authors first describe intra‐ and inter‐cellular Ca2+ signaling in relation to insulin secretion from the pancreatic islets, and then outline the development of diverse sensors, for example, chemically synthesized indicators, genetically encoded proteins, and ion‐selective microelectrodes, for intra‐ and extra‐cellular sensing of Ca2+. Particular emphasis is placed on emerging approaches in this field, such as low‐affinity Ca2+ indicators and unique Ca2+‐responsive composite materials. The authors conclude by remarking on the challenges and opportunities for further developments in this field, which may facilitate a more comprehensive understanding of Ca2+ signaling within and outside the islets, and its relevance in health and disease.

New Insights of Anti-Hyperglycemic Agents and Traditional Chinese Medicine on Gut Microbiota in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is a widespread metabolic disease characterized by chronic hyperglycemia. Human microbiota, which is regarded as a “hidden organ”, plays an important role in the initiation and development of T2DM. In addition, anti-hyperglycemic agents and traditional Chinese medicine may affect the composition of gut microbiota and consequently improve glucose metabolism. However, the relationship between gut microbiota, T2DM and anti-hyperglycemic agents or traditional Chinese medicine is poorly understood. In this review, we summarized pre-clinical and clinical studies to elucidate the possible underlying mechanism. Some anti-hyperglycemic agents and traditional Chinese medicine may partly exert hypoglycemic effects by altering the gut microbiota composition in ways that reduce metabolic endotoxemia, maintain the integrity of intestinal mucosal barrier, promote the production of short-chain fatty acids (SCFAs), decrease trimethylamine-N-oxide (TMAO) and regulate bile acid metabolism. In conclusion, gut microbiota may provide some new therapeutic targets for treatment of patients with diabetes mellitus.

The science of plant-based foods: Constructing next-generation meat, fish, milk, and egg analogs

Consumers are increasingly demanding foods that are more ethical, sustainable and nutritious to improve the health of themselves and the planet. The food industry is currently undergoing a revolution, as both small and large companies pivot toward the creation of a new generation of plant-based products to meet this consumer demand. In particular, there is an emphasis on the production of plant-based foods that mimic those that omnivores are familiar with, such as meat, fish, egg, milk, and their products. The main challenge in this area is to simulate the desirable appearance, texture, flavor, mouthfeel, and functionality of these products using ingredients that are isolated entirely from botanical sources, such as proteins, carbohydrates, and lipids. The molecular, chemical, and physical properties of plant-derived ingredients are usually very different from those of animal-derived ones. It is therefore critical to understand the fundamental properties of plant-derived ingredients and how they can be assembled into structures resembling those found in animal products. This review article provides an overview of the current status of the scientific understanding of plant-based foods and highlights areas where further research is required. In particular, it focuses on the chemical, physical, and functional properties of plant-derived ingredients; the processing operations that can be used to convert these ingredients into food products; and, the science behind the formulation of vegan meat, fish, eggs, and milk alternatives.

Gender and gut microbiota composition determine hepatic bile acid, metabolic and inflammatory response to a single fast-food meal in healthy adults

BACKGROUND & AIMS

Regular consumption of fast-food (FF) as a form of typical Western style diet is associated with obesity and the metabolic syndrome, including its hepatic manifestation nonalcoholic fatty liver disease. Currently, it remains unclear how intermittent excess FF consumption may influence liver metabolism. The study aimed to characterize the effects of a single FF binge on hepatic steatosis, inflammation, bile acid (BA), glucose and lipid metabolism.

METHODS

Twenty-five healthy individuals received a FF meal and were asked to continue eating either for a two-hour period or until fully saturated. Serum levels of transaminases, fasting BA, lipid profile, glucose and cytokine levels as well as transient elastography and controlled attenuation parameter (CAP; to assess hepatic steatosis) were analyzed before (day 0) and the day after FF binge (day 1). Feces was collected prior and after the FF challenge for microbiota analysis.

RESULTS

The FF meal induced a modest increase in CAP, which was accompanied by a robust increase of fasting serum BA levels. Surprisingly, levels of cholesterol and bilirubin were significantly lower after the FF meal. Differentiating individuals with a relevant delta BA (>1 μmol/l) increase vs. individuals without (delta BA ≤1 μmol/l), identified several gut microbiota, as well as gender to be associated with the BA increase and the observed alterations in liver function, metabolism and inflammation.

CONCLUSION

A single binge FF meal leads to a robust increase in serum BA levels and alterations in parameters of liver injury and metabolism, indicating a novel metabolic aspect of the gut-liver axis.

Role of Bile Acids in the Regulation of Food Intake, and Their Dysregulation in Metabolic Disease

Bile acids are cholesterol-derived metabolites with a well-established role in the digestion and absorption of dietary fat. More recently, the discovery of bile acids as natural ligands for the nuclear farnesoid X receptor (FXR) and membrane Takeda G-protein-coupled receptor 5 (TGR5), and the recognition of the effects of FXR and TGR5 signaling have led to a paradigm shift in knowledge regarding bile acid physiology and metabolic health. Bile acids are now recognized as signaling molecules that orchestrate blood glucose, lipid and energy metabolism. Changes in FXR and/or TGR5 signaling modulates the secretion of gastrointestinal hormones including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), hepatic gluconeogenesis, glycogen synthesis, energy expenditure, and the composition of the gut microbiome. These effects may contribute to the metabolic benefits of bile acid sequestrants, metformin, and bariatric surgery. This review focuses on the role of bile acids in energy intake and body weight, particularly their effects on gastrointestinal hormone secretion, the changes in obesity and T2D, and their potential relevance to the management of metabolic disorders.

Regional Intestinal Drug Absorption: Biopharmaceutics and Drug Formulation

The gastrointestinal tract (GIT) can be broadly divided into several regions: the stomach, the small intestine (which is subdivided to duodenum, jejunum, and ileum), and the colon. The conditions and environment in each of these segments, and even within the segment, are dependent on many factors, e.g., the surrounding pH, fluid composition, transporters expression, metabolic enzymes activity, tight junction resistance, different morphology along the GIT, variable intestinal mucosal cell differentiation, changes in drug concentration (in cases of carrier-mediated transport), thickness and types of mucus, and resident microflora. Each of these variables, alone or in combination with others, can fundamentally alter the solubility/dissolution, the intestinal permeability, and the overall absorption of various drugs. This is the underlying mechanistic basis of regional-dependent intestinal drug absorption, which has led to many attempts to deliver drugs to specific regions throughout the GIT, aiming to optimize drug absorption, bioavailability, pharmacokinetics, and/or pharmacodynamics. In this Editorial we provide an overview of the Special Issue "Regional Intestinal Drug Absorption: Biopharmaceutics and Drug Formulation". The objective of this Special Issue is to highlight the current progress and to provide an overview of the latest developments in the field of regional-dependent intestinal drug absorption and delivery, as well as pointing out the unmet needs of the field.

Role of intestinal glucose absorption in glucose tolerance

Intestinal glucose absorption is integral to postprandial glucose homeostasis. Glucose absorption is dependent on a number of factors, including the exposure of carbohydrate to the mucosa of the upper gastrointestinal tract (determined particularly by the rates of gastric emptying and small intestinal transit), the digestion of complex carbohydrate into monosaccharides, and glucose sensing and transport by the intestinal mucosa. The absorption of glucose in the small intestine is not only a determinant of the appearance of exogenous glucose in the peripheral circulation, but is also coupled to the release of gastrointestinal hormones that in turn influence postprandial glucose metabolism through modulating gastrointestinal motor function, insulin and glucagon secretion, and subsequent energy intake. This review describes the physiology and pathophysiology of intestinal glucose absorption in health and type 2 diabetes, including its relevance to glucose tolerance and the management of postprandial hyperglycaemia.