Gastrointestinal hormones and their role in obesity

Hunger & satiety signals: another key mechanism involved in the NAFLD pathway

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent metabolic disease, although prevalence could change according to region, nowadays is considered a public health problem whose real impact on the health system is unknown. NAFLD has a multifactorial and complex pathophysiology, due to this, developing a unique and effective pharmacological treatment has not been successful in reverting or avoiding the progression of this liver disease. Even though NAFLD pathophysiology is known, all actual treatments are focused on modifying or regulating the metabolic pathways, some of which interplay with obesity. It has been known that impairments in hunger and satiety signals are associated with obesity, however, abnormalities in these signals in patients with NAFLD and obesity are not fully elucidated. To describe these mechanisms opens an additional option as a therapeutic target sharing metabolic pathways with NAFLD, therefore, this review aims to describe the hormones and peptides implicated in both hunger-satiety in NAFLD. It has been established that NAFLD pharmacological treatment cannot be focused on a single purpose; hence, identifying interplays that lead to adding or modifying current treatment options could also have an impact on another related outcome such as hunger or satiety signals.

The Impact of Dietary Glycemic Index and Glycemic Load on Postprandial Lipid Kinetics, Dyslipidemia and Cardiovascular Risk

Many recent studies have acknowledged postprandial hypetriglyceridemia as a distinct risk factor for cardiovascular disease. This dysmetabolic state is the result of the hepatic overproduction of very low-density lipoproteins (VLDLs) and intestinal secretion of chylomicrons (CMs), which leads to highly atherogenic particles and endothelial inflammation. Postprandial lipid metabolism does not only depend on consumed fat but also on the other classes of nutrients that a meal contains. Various mechanisms through which carbohydrates exacerbate lipidemia have been identified, especially for fructose, which stimulates de novo lipogenesis. Glycemic index and glycemic load, despite their intrinsic limitations, have been used as markers of the postprandial glucose and insulin response, and their association with metabolic health and cardiovascular events has been extensively studied with contradictory results. This review aims to discuss the importance and pathogenesis of postprandial hypertriglyceridemia and its association with cardiovascular disease. Then, we describe the mechanisms through which carbohydrates influence lipidemia and, through a brief presentation of the available clinical studies on glycemic index/glycemic load, we discuss the association of these indices with atherogenic dyslipidemia and address possible concerns and implications for everyday practice.

Appetite-regulating hormones and anthropometric indicators of infants according to the type of feeding

It has been accepted that satiety- and appetite-stimulating hormones play a role in the regulation of food intake and body composition during and after the lactation stage. Therefore, the purpose was to demonstrate that serum appetite-regulating hormones in infants differ according to anthropometric indicators and type of feeding. In a nonrandom cohort study, 169 mother-newborn dyads whose pregnancy and birth were attended at the Hospital Civil de Guadalajara were enrolled. According to the type of feeding, infants were classified as full breastfeeding (FBF), partial breastfeeding (PBF), and infants receiving human milk substitutes (HMS). Serum concentrations of ghrelin (pg/ml), leptin (ng/ml), peptide YY (pg/ml), and glucagon-like peptide-1 (GLP-1) (pM) were measured. Anthropometric measurements including weight, length, cephalic, arm circumference, tricipital, and subscapular skinfolds were obtained. Weight/age, weight/height, height/age, and BMI Z-score indexes were estimated. We performed one-way ANOVA, unpaired Student's t test, post hoc Tukey test, and Pearson correlation tests. The ANOVA comparison of the three feeding types showed significant differences in most anthropometric indicators (z-scores), especially between infants receiving FBF versus HMS and particularly on indicators of adiposity; no differences were observed in length and cephalic circumference z-scores at 8th and 16th weeks. Further, significant correlations were found between most of the adiposity indicators with ghrelin, leptin, and GLP-1, especially in infants who received FBF. There were differences in anthropometric and body composition parameters among infants receiving FBF, PBF, and HMS. There were significant correlations between body composition indicators with ghrelin, leptin, and GLP-1 mainly in infants receiving FBF.

Exploring motivation for bariatric surgery among Indigenous Māori women

INTRODUCTION

Bariatric surgery is the most effective intervention for alleviating obesity and its complications. Indigenous people worldwide experience higher rates of obesity and obesity disease burden. However, few studies exploring bariatric surgery among Indigenous peoples are published. In this study we aimed to explore the motivation of Māori women in coming forward for bariatric surgery.

METHODS

Māori women who had bariatric surgery prior to December 31, 2014, were invited to participate in semi-structured interpersonal interviews. Kaupapa Māori research, an Indigenous Māori research methodology, informed this study. Interviews were recorded, transcribed and subject to inductive thematic analysis.

RESULTS

Twenty-nine Māori women participated in semi-structured interpersonal interviews. The majority of women reported that the presence of obesity-related disease alongside the desire for a better quality of life served as the greatest sources of motivation for having bariatric surgery. Whānau (family) were key for participants achieving the preoperative milestones needed to be accepted for bariatric surgery. Interpersonal experiences of fat-shaming and yo-yo dieting also impacted their choice to have surgery.

CONCLUSION

This study is one of the first to describe the motivations of Indigenous Māori women to have bariatric surgery. Our study conveys the importance of health, a desire to have a better quality of life and whānau in motivating Māori women to come forward for bariatric surgery.

A randomized controlled trial for overweight and obesity in preschoolers: the More and Less Europe study - an intervention within the STOP project

Background

Childhood overweight and obesity is a serious public health issue with an increase being observed in preschool-aged children. Treating childhood obesity is difficult and few countries use standardized treatments. Therefore, there is a need to find effective approaches that are feasible for both health care providers and families. Thus, the overall aim of this study is to assess the acceptance and effectiveness of a parent support program (the More and Less, ML) for the management of overweight and obesity followed by a mobile health (mHealth) program (the MINISTOP application) in a socially diverse population of families.

Methods/design

A two-arm, parallel design randomized controlled trial in 300 2-to 6-year-old children with overweight and obesity from Romania, Spain and Sweden (n = 100 from each). Following baseline assessments children are randomized into the intervention or control group in a 1:1 ratio. The intervention, the ML program, consists of 10-weekly group sessions which focus on evidence-based parenting practices, followed by the previously validated MINISTOP application for 6-months to support healthy eating and physical activity behaviors. The primary outcome is change in body mass index (BMI) z-score after 9-months and secondary outcomes include: waist circumference, eating behavior (Child Eating Behavior Questionnaire), parenting behavior (Comprehensive Feeding Practices Questionnaire), physical activity (ActiGraph wGT3x-BT), dietary patterns (based on metabolic markers from urine and 24 h dietary recalls), epigenetic and gut hormones (fasting blood samples), and the overall acceptance of the overweight and obesity management in young children (semi-structured interviews). Outcomes are measured at baseline and after: 10-weeks (only BMI z-score, waist circumference), 9-months (all outcomes), 15- and 21-months (all outcomes except physical activity, dietary patterns, epigenetics and gut hormones) post-baseline.

Discussion

This study will evaluate a parent support program for weight management in young children in three European countries. To boost the effect of the ML program the families will be supported by an app for 6-months. If the program is found to be effective, it has the potential to be implemented into routine care to reduce overweight and obesity in young children and the app could prove to be a viable option for sustained effects of the care provided.

Trial registration

ClinicalTrials.gov NCT03800823; 11 Jan 2019.

Serum concentration of appetite-regulating hormones of mother-infant dyad according to the type of feeding

Satiety and appetite-stimulating hormones play a role in the regulation of food intake. Breastfed infants may have a different profile of serum appetite-regulating hormones than formula-fed infants. We propose to demonstrate that the serum concentration of appetite regulatory hormones differs according to the type of feeding and that there is a correlation between the serum concentrations of these hormones in mothers and in infants at 4 months of age. In a cross-sectional analysis, 167 mother-newborn dyads at the Hospital Civil de Guadalajara were enrolled: 74 full breastfeeding (FBF), 56 partial breastfeeding (PBF), and 37 receiving human milk substitutes (HMS). Serum levels of ghrelin (pg/ml), leptin (ng/ml), peptide YY (pg/ml), and glucagon-like peptide-1 (GLP-1) (pM) were measured. We performed one-way analysis of variance, unpaired Student t test, post hoc Tukey test, and Pearson correlation. The total sample at 16 weeks postpartum included 167 dyads. The mean age was 16 ± 1 weeks. The concentrations of GLP-1 (pM) and peptide YY (pg/ml) were higher in the FBF group (42.6 and 442.9) than in the HMS group (35.2 and 401.9), respectively, p = 0.046 and p = 0.056. And, the FBF group had higher correlation coefficients of ghrelin (r = 0.411 vs. 0.165), GLP-1 (r = 0.576 vs. 0.407), and peptide YY (r = 0.218 vs. 0.067), respectively, than the HMS group. The concentrations of GLP-1 and peptide YY were higher in the FBF group when compared with the HMS group. Mother-infant dyads fed by FBF had more significant direct correlations of appetite-regulating hormones than those who received HMS.

Whey Proteins Reduce Appetite, Stimulate Anorexigenic Gastrointestinal Peptides and Improve Glucometabolic Homeostasis in Young Obese Women

Introduction: Proteins, particularly whey proteins, represent the most satiating macronutrient in animals and humans. A dietetic regimen based on proteins enriched preload before eating might be a strategy to counteract obesity. Aims and Methods: The aim of the present study was to evaluate the effects of an isocaloric drink containing whey proteins or maltodextrins (preload) on appetite (satiety/hunger measured by a visual analogue scale or VAS), glucometabolic control (blood glucose/insulin), and anorexigenic gastrointestinal peptides (pancreatic polypeptide or PP, glucagon-like peptide 1 or GLP-1 and peptide YY or PYY) in a cohort of obese young women (n = 9; age: 18.1 ± 3.0 years; body mass index, BMI: 38.8 ± 4.5 kg/m²). After two and a half hours, they were administered with a mixed meal at a fixed dose; satiety and hunger were measured by VAS. Results: Each drink significantly augmented satiety and reduced hunger, and the effects were more evident with whey proteins than maltodextrins. Similarly, there were significant increases in GLP-1 and PYY levels (but not PP) after the ingestion of each drink; these anorexigenic responses were higher with whey proteins than maltodextrins. While insulinemia identically increased after each drink, whey proteins induced a lower glycemic response than maltodextrins. No differences in satiety and hunger were found after the meal, which is presumably due to the late administration of the meal test, when the hypophagic effect of whey proteins was disappearing. Conclusions: While whey proteins actually reduce appetite, stimulate anorexigenic gastrointestinal peptides, and improve glucometabolic homeostasis in young obese women, further additional studies are mandatory to demonstrate their hypophagic effects in obese subjects, when administered as preload before eating.

Relevance of the Glycemic Index and Glycemic Load for Body Weight, Diabetes, and Cardiovascular Disease

Despite initial enthusiasm, the relationship between glycemic index (GI) and glycemic response (GR) and disease prevention remains unclear. This review examines evidence from randomized, controlled trials and observational studies in humans for short-term (e.g., satiety) and long-term (e.g., weight, cardiovascular disease, and type 2 diabetes) health effects associated with different types of GI diets. A systematic PubMed search was conducted of studies published between 2006 and 2018 with key words glycemic index, glycemic load, diabetes, cardiovascular disease, body weight, satiety, and obesity. Criteria for inclusion for observational studies and randomized intervention studies were set. The search yielded 445 articles, of which 73 met inclusion criteria. Results suggest an equivocal relationship between GI/GR and disease outcome. The strongest intervention studies typically find little relationship among GI/GR and physiological measures of disease risk. Even for observational studies, the relationship between GI/GR and disease outcomes is limited. Thus, it is unlikely that the GI of a food or diet is linked to disease risk or health outcomes. Other measures of dietary quality, such as fiber or whole grains may be more likely to predict health outcomes. Interest in food patterns as predictors of health benefits may be more fruitful for research to inform dietary guidance.

MEDI0382, a GLP-1 and glucagon receptor dual agonist, in obese or overweight patients with type 2 diabetes: a randomised, controlled, double-blind, ascending dose and phase 2a study

BACKGROUND

Weight loss is often key in the management of obese or overweight patients with type 2 diabetes, yet few treatments for diabetes achieve clinically meaningful weight loss. We aimed to assess the efficacy, tolerability, and safety of treatment with MEDI0382, a balanced glucagon-like peptide-1 and glucagon receptor dual agonist developed to provide glycaemic control and weight loss, in patients with type 2 diabetes.

METHODS

This randomised, placebo-controlled, double-blind, combined multiple-ascending dose (MAD) and phase 2a study was done at 11 study sites (hospitals and contract research organisations) in Germany. We enrolled patients aged 18-65 years with controlled type 2 diabetes (glycated haemoglobin A_1c [HbA_1c] levels of 6·5-8·5% at screening) and a body-mass index between 27 kg/m² and 40 kg/m². An interactive web-response system was used to randomly assign patients to receive MEDI0382 or placebo. Patients were randomly assigned 2:1 in cohorts A-C and 3:1 in cohorts D and E in the MAD portion of the study, and 1:1 in the phase 2a portion. Randomisation was done by a contracted third-party operator who was not involved in the clinical operations of the study. The pharmacists, participants, and study site personnel involved in treating and assessing participants were masked to treatment allocation. Patients received once-daily subcutaneous injections of the study drug at doses of no more than 300 μg for 22 days or less in the MAD portion of the study, and a dose of no more than 200 μg for 41 days or less in the phase 2a portion. The two primary endpoints of the phase 2a portion were the change from baseline to day 41 in glucose area under the curve at 0-4 h (AUC_{0-4 h}) after a mixed-meal tolerance test (MMTT), assessed in all participants who received at least one dose of study drug and whose measurements were taken at baseline and day 41, and change from baseline in bodyweight, assessed in the intention-to-treat (ITT) population. Safety analyses were done in all participants who received any study drug analysed according to the treatment they received. This study is registered with ClinicalTrials.gov, number NCT02548585.

FINDINGS

Patients were recruited between Dec 9, 2015, and Feb 24, 2017. 61 patients were randomly assigned to the MAD part of the study (42 to MEDI0382 and 19 to placebo). 51 patients were randomly assigned to the phase 2a part, of whom 25 were randomly assigned to MEDI0382 and 26 to placebo. In the phase 2a study, three patients in the MEDI0382 group and one in the placebo group discontinued, all as a result of adverse events. 22 (88%) patients in the MEDI0382 group and 25 (96%) in the placebo group received at least one dose and had measurements taken at baseline and day 41. Glucose AUC_{0-4 h} post MMTT decreased significantly with MEDI0382 versus placebo (least squares [LS] mean -32·78% [90% CI -36·98 to -28·57] vs -10·16% [-14·10 to -6·21], and the mean difference was -22·62% [-28·40 to -16·85]; p<0·0001). In the ITT population, reduction in bodyweight was significantly greater with MEDI0382 than with placebo (LS mean -3·84 kg [90% CI -4·55 to -3·12] vs -1·70 kg [-2·40 to -1·01] and mean difference of 2·14 kg [-3·13 to -1·31]; p=0·0008). The proportion of patients who had a treatment-emergent adverse event (TEAE) was similar between treatment groups (22 [88%] of 25 in the MEDI0382 group vs 23 [88%] of 26 in the placebo group); gastrointestinal disorders (18 [72%] vs 13 [40%]) and decreased appetite (five [20%] vs none) occurred more frequently with MEDI0382 than placebo. No participants in the MEDI0382 group had a grade 3 or worse TEAE (vs two [8%] in the placebo group).

INTERPRETATION

MEDI0382 has the potential to deliver clinically meaningful reductions in blood glucose and bodyweight in obese or overweight individuals with type 2 diabetes.

FUNDING

MedImmune.

Breastfeeding and Maternal Hypertension

BACKGROUND

Little is known about the relationship between breastfeeding and hypertension. We performed this study to identify whether breastfeeding itself influenced maternal hypertension and whether degree of obesity or insulin sensitivity would contribute to the relationship between breastfeeding and hypertension in postmenopausal women.

METHODS

Our study population comprised 3,119 nonsmoking postmenopausal women aged 50 years or above in the 2010-2011 Korea National Health and Nutrition Examination Survey. We performed logistic regression analyses to examine the relationship between breastfeeding and hypertension and mediation analyses to examine the contributions of obesity and insulin sensitivity to the breastfeeding-hypertension relationship.

RESULTS

The odds ratios, with 95% confidence intervals, for hypertension among the highest quintile of number of breastfed children (5-11) and the highest quintile of duration of breastfeeding (96-324 months) were 0.49 (0.31-0.75) and 0.55 (0.37-0.82), respectively, compared to each of lowest quintile groups. The population attributable fractions of hypertension caused by breastfeeding 3 or fewer children and breastfeeding for 56 months or less were 10.2% (P < 0.001) and 6.5% (P = 0.017), respectively. In the mediation analysis, unexpectedly, increased insulin resistance significantly attenuated the protective effect on hypertension of having breastfed more children; additionally, greater obesity and insulin resistance significantly attenuated the protective effects on hypertension of having breastfed for longer.

CONCLUSIONS

More children breastfed and longer duration of breastfeeding were associated with lower risk of hypertension in postmenopausal women, and degree of obesity and insulin resistance moderated the breastfeeding-hypertension association.

Chimeric peptide EP45 as a dual agonist at GLP-1 and NPY2R receptors

We report the design and target validation of chimeric peptide EP45, a novel 45 amino acid monomeric dual agonist peptide that contains amino acid sequence motifs present within the blood glucose-lowering agent exendin-4 (Ex-4) and the appetite-suppressing agent PYY(3-36). In a new high-throughput FRET assay that provides real-time kinetic information concerning levels of cAMP in living cells, EP45 recapitulates the action of Ex-4 to stimulate cAMP production via the glucagon-like peptide-1 receptor (GLP-1R), while also recapitulating the action of PYY(3-36) to inhibit cAMP production via the neuropeptide Y2 receptor (NPY2R). EP45 fails to activate glucagon or GIP receptors, whereas for cells that co-express NPY2R and adenosine A2B receptors, EP45 acts in an NPY2R-mediated manner to suppress stimulatory effects of adenosine on cAMP production. Collectively, such findings are remarkable in that they suggest a new strategy in which the co-existing metabolic disorders of type 2 diabetes and obesity will be treatable using a single peptide such as EP45 that lowers levels of blood glucose by virtue of its GLP-1R-mediated effect, while simultaneously suppressing appetite by virtue of its NPY2R-mediated effect.

Gastric bypass surgery mimetic approaches

Gastric bypass surgery is effectively a polypharmacological approach for treatment of obesity, type 2 diabetes and nonalcoholic steatohepatitis (NASH). The gastric bypass mimetic approaches reviewed are fixed-dose combinatorial pharmacological approaches. There are two key concepts incorporated into these gastric bypass surgery mimetic approaches. The first key concept is that the combination of glucagon-like peptide 1 (GLP-1) and fibroblast growth factor 21 (FGF21) is essential for success of any gastric bypass surgery mimetic approach. This combination affords the potential for durable weight loss, glycemic control and reduction in liver lipids. The second key concept is that a fixed-dose combination approach is preferred over post-approval combination of the individual components because the individual components alone often lack sufficient efficacy for development.

Control of Food Intake by Gastrointestinal Peptides: Mechanisms of Action and Possible Modulation in the Treatment of Obesity

This review focuses on the control of appetite by food intake-regulatory peptides secreted from the gastrointestinal tract, namely cholecystokinin, glucagon-like peptide 1, peptide YY, ghrelin, and the recently discovered nesfatin-1 via the gut-brain axis. Additionally, we describe the impact of external factors such as intake of different nutrients or stress on the secretion of gastrointestinal peptides. Finally, we highlight possible conservative—physical activity and pharmacotherapy—treatment strategies for obesity as well as surgical techniques such as deep brain stimulation and bariatric surgery also altering these peptidergic pathways.

Future Therapies in Obesity

Although diet and exercise have been the cornerstone of therapy for obesity, efficacy is suboptimal and short lived. Surgical procedures are durable but invasive therapy for obesity. Supplemental therapies for obesity that are minimally invasive, low risk, and effective are needed. Several therapeutic options are being developed that offer obese patients and their health care providers alternatives to what is currently available.

Increased GLP-1 response to oral glucose in pre-pubertal obese children

BACKGROUND

Gastrointestinal hormones, such as glucagon-like peptide (GLP-1), have been hypothesized to play a role in the pathogenesis of obesity-related complications. However, few data are available in youth. The objective of this study was to investigate the GLP-1 response to oral glucose load in obese pre-pubertal children and its relationship with insulin secretion.

METHODS

Ten pre-pubertal obese children [five boys; 10.5±1.6 years; body mass index-standard deviation score (BMI-SDS): 2.2±0.5] and 10 controls (eight boys; 9.9±1.2 years; BMI-SDS: -0.7±0.5) underwent a modified oral glucose tolerance test (OGTT) to evaluate post-load glucose, insulin and GLP-1 responses. Insulin sensitivity [homeostasis model assessment of insulin resistance (HOMA-IR), whole body insulin sensitivity index (WBISI)] and secretion [HOMA-beta, insulinogenic index (IGI)] indexes, area under the curve (AUC) for glucose, insulin and GLP-1 were calculated.

RESULTS

In obese children GLP-1 AUC values were higher and correlated with BMI-SDS (r=0.45; p=0.04), HOMA-IR (r=0.53; p=0.01) and fasting glucose (r=0.68; p=0.001).

CONCLUSIONS

Obese children showed an increased GLP-1 response to oral glucose. These changes might likely represent a compensatory mechanism to avoid post-prandial hyperglycemia and allow a normal glucose tolerance.

Gut Microbiota and Metabolic Health: The Potential Beneficial Effects of a Medium Chain Triglyceride Diet in Obese Individuals

Obesity and associated metabolic complications, such as non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2D), are in constant increase around the world. While most obese patients show several metabolic and biometric abnormalities and comorbidities, a subgroup of patients representing 3% to 57% of obese adults, depending on the diagnosis criteria, remains metabolically healthy. Among many other factors, the gut microbiota is now identified as a determining factor in the pathogenesis of metabolically unhealthy obese (MUHO) individuals and in obesity-related diseases such as endotoxemia, intestinal and systemic inflammation, as well as insulin resistance. Interestingly, recent studies suggest that an optimal healthy-like gut microbiota structure may contribute to the metabolically healthy obese (MHO) phenotype. Here, we describe how dietary medium chain triglycerides (MCT), previously found to promote lipid catabolism, energy expenditure and weight loss, can ameliorate metabolic health via their capacity to improve both intestinal ecosystem and permeability. MCT-enriched diets could therefore be used to manage metabolic diseases through modification of gut microbiota.