Recent advances in clinical practice challenges and opportunities in the management of obesity

Precision Bariatrics: Toward a New Paradigm of Personalized Devices in Obesity Therapeutics

The prevalence and complexity of obesity and its associated metabolic complications highlight the importance of building a rigorous investigative framework for the development of novel weight loss therapies. Device-based interventions in particular constitute a market poised for rapid expansion in the coming years. Optimizing outcomes for this new class of therapies requires attention to an evolving taxonomy of subdivisions within the broader obesity phenotype and a means for stratifying patients toward maximally effective interventions. Extant bariatric devices implicitly prioritize anatomic variables as surrogates for physiology, a somewhat arbitrary assumption that merits empiric validation. Utilizing the governing principles of systems biology and recent innovations in clinical trial design, a robust and precise research infrastructure can and should be developed to more effectively mitigate this contemporary epidemic.

Gastrointestinal traits: individualizing therapy for obesity with drugs and devices

BACKGROUND AND AIMS

The aims of this article were to review the discrepancy between numbers of people requiring weight loss treatment and results and to assess the potential effects of pharmacologic treatments (recently approved for obesity) and endoscopically deployed devices on quantitative GI traits in development for obesity treatment.

METHODS

We conducted a review of relevant literature to achieve our objectives.

RESULTS

The 2013 guidelines increased the number of adults recommended for weight loss treatment by 20.9% (116.0 million to 140.2 million). There is an imbalance between efficacy and costs of commercial weight loss programs and drug therapy (average weight loss about 5 kg). The number of bariatric procedures performed in the United States has doubled in the past decade. The efficacy of bariatric surgery is attributed to reduction in the volume of the stomach, nutrient malabsorption with some types of surgery, increased postprandial incretin responses, and activation of farnesoid X receptor mechanisms. These GI and behavioral traits identify sub-phenotypes of obesity, based on recent research.

CONCLUSIONS

The mechanisms or traits targeted by drug and device treatments include centrally mediated alterations of appetite or satiation, diversion of nutrients, and alteration of stomach capacity, gastric emptying, or incretin hormones. Future treatment may be individualized based on quantitative GI and behavioral traits measured in obese patients.

Exenatide in obesity with accelerated gastric emptying: a randomized, pharmacodynamics study

Obesity is associated with differences in satiety, gastric emptying (GE), gastric volume, and psychological traits. Exenatide, a short-acting glucagon-like peptide 1 (GLP-1) receptor agonist, is associated with variable weight loss. We compared the effects of exenatide, 5 μg, and placebo SQ, twice daily for 30 days on GE of solids and liquids (scintigraphy), satiety (ad libitum buffet meal), satiation (nutrient drink test, maximum tolerated volume [MTV]), and weight loss in 20 participants with documented accelerated GE of solids (T1/2 < 90 min). Exenatide delayed GE of solids (T1/2 [Δ] 86 min relative to placebo, P < 0.001) and reduced calorie intake at buffet meal ([Δ] 129 kcal compared to placebo). Median weight loss was -0.95 kg (IQR -0.7 to -2.1) for exenatide and -0.55 kg (0.3 to -2.1) for placebo (P = 0.23); 80% of exenatide group had documented reduction in weight. In the exenatide treatment group, there was an inverse correlation between gastric emptying T1/2 and MTV (R = -0.548, P = 0.089). The univariate association of weight change with posttreatment MTV was borderline (Rs = 0.43, P = 0.06); in the multiple regression model, posttreatment MTV was associated with weight change (P = 0.047). The effect of the short-acting GLP-1 receptor agonist, exenatide, on GE is associated with the change in food intake, and the latter impacts weight loss in response to exenatide treatment.

Variation in blood levels of hormones in obese patients following weight reduction induced by endoscopic and surgical bariatric therapies

BACKGROUND

Beneficial clinical effects of weight reduction following bariatric therapies is not fully understood and maybe related to the complex interactions between leptin, adiponectin, visfatin, omentin, and ghrelin. The aim of study was to investigate their timeline changes associated with weight reduction and their profile in relation to the type of treatment and its efficacy.

METHODS

Circulating hormones levels were analyzed before and after endoscopic and surgical procedures in 67 obese patients and compared to non-obese healthy controls.

RESULTS

Obese patients had higher leptin levels and lower levels of adiponectin, visfatin, omentin, and ghrelin than non-obese controls. During the consecutive follow-up visits after treatment, there was a gradual decrease in leptin levels and an increase in adiponectin levels to the levels observed in non-obese. At 50-54weeks, the ghrelin levels were lower and the levels of adiponectin and visfatin, but not omentin, were higher compared to their baseline values. BMI correlated with ghrelin and leptin levels. The percentage of total weight loss correlated positively with adiponectin levels and negatively with leptin levels. Patients with adequate weight loss had a significantly lower leptin concentration than those with treatment failure. There were timeline variations in hormone levels between endoscopic and bariatric therapies, however there were no significant differences in the median their concentration at 50-54weeks after therapy.

CONCLUSION

Our study supports observations that weight loss itself, rather than the procedure type, is responsible for hormonal variation. The leptin levels reflect the best the body weight changes after bariatric therapies.

Long-term effects of bariatric surgery on type II diabetes, hypertension and hyperlipidemia: a meta-analysis and meta-regression study with 5-year follow-up

BACKGROUND

The first aim of the study was to estimate weight loss and major modifiable risk factors after bariatric surgery. The second aim was to investigate the relationship between the reduction in cardiovascular risk and weight loss over time.

METHODS

A random effect of meta-analysis and dose-response meta-regression was used to evaluate weight loss and the risk of type II diabetes, hypertension and hyperlipidemia, 2-5 years after surgery.

RESULTS

A search of the literature led to the selection of 22 papers. The body mass index (BMI) at the end of the observation period was 31.7 (95 % CI = 29.7-33.7; I(2) = 6 %). The risk of type II diabetes, hypertension and hyperlipidemia decreased after bariatric surgery, with relative risks of, respectively, 0.33 (95 % CI = 0.26-0.41; I(2) = 42 %), 0.54 (95 % CI = 0.46-0.64; I(2) = 68 %) and 0.33 (95 % CI = 0.22-0.46; I(2) = 74 %). Nonlinear meta-regression revealed different patterns of risk: Hypertension risk reached a minimum when the BMI fell 10 units. The risks of all cardiovascular outcomes reached a plateau, 20-40 months after surgery.

CONCLUSIONS

The reduction in arterial hypertension reached a nadir earlier than the risk of diabetes and hyperlipidemia, thus indicating a possible link between weight reduction and positive hemodynamic effects.

The stomach in health and disease

The stomach is traditionally regarded as a hollow muscular sac that initiates the second phase of digestion. Yet this simple view ignores the fact that it is the most sophisticated endocrine organ with unique physiology, biochemistry, immunology and microbiology. All ingested materials, including our nutrition, have to negotiate this organ first, and as such, the stomach is arguably the most important segment within the GI tract. The unique biological function of gastric acid secretion not only initiates the digestive process but also acts as a first line of defence against food-borne microbes. Normal gastric physiology and morphology may be disrupted by Helicobacter pylori infection, the most common chronic bacterial infection in the world and the aetiological agent for most peptic ulcers and gastric cancer. In this state-of-the-art review, the most relevant new aspects of the stomach in health and disease are addressed. Topics include gastric physiology and the role of gastric dysmotility in dyspepsia and gastroparesis; the stomach in appetite control and obesity; there is an update on the immunology of the stomach and the emerging field of the gastric microbiome. H. pylori-induced gastritis and its associated diseases including peptic ulcers and gastric cancer are addressed together with advances in diagnosis. The conclusions provide a future approach to gastric diseases underpinned by the concept that a healthy stomach is the gateway to a healthy and balanced host. This philosophy should reinforce any public health efforts designed to eradicate major gastric diseases, including stomach cancer.

GLP-1: a mediator of the beneficial metabolic effects of bariatric surgery?

There has been increasing interest in the role that gut hormones may play in contributing to the physiological changes produced by certain bariatric procedures, such as Roux-en-Y gastric bypass and sleeve gastrectomy. Here, we review the evidence implicating one such gut hormone, glucagon-like peptide-1, as a mediator of the metabolic benefits of these two procedures.

Primary endoscopic therapies for obesity and metabolic diseases

PURPOSE OF REVIEW

Endoscopic approaches to obesity may help fulfill the unmet need of over half the US adult population who would benefit from therapy for obesity but are not receiving it. Endoluminal approaches have the potential to be more efficacious than antiobesity medications and have a lower risk-cost profile compared with bariatric surgery. This review outlines the current state of primary endoscopic weight loss and metabolic therapies and sheds light on the challenges faced toward making endoscopic bariatric therapies 'ready for prime time'.

RECENT FINDINGS

Endoscopic approaches to obesity are being increasingly modeled on the proposed mechanisms contributing to the benefits of bariatric surgery.Therapies targeted at the stomach induce weight loss with only a proportional benefit to underlying metabolic disorders.Therapies targeting the proximal small bowel appear to modulate various neurohormonal pathways resulting in an improvement in metabolic profile in excess to that accounted for by weight loss itself.

SUMMARY

Rigorous scientific assessment of endoscopic approaches to obesity is necessary to allow its integration into the treatment algorithm of obesity. The endoscopic armamentarium against obesity continues to evolve with the endoscopist poised to be a key player in the management of this disease.

VIDEO ABSTRACT

http://links.lww.com/COG/A12.

GLP-1 receptor agonists: Nonglycemic clinical effects in weight loss and beyond

OBJECTIVE

Glucagon-like peptide-1 (GLP-1) receptor agonists are indicated for treatment of type 2 diabetes since they mimic the actions of native GLP-1 on pancreatic islet cells, stimulating insulin release, while inhibiting glucagon release, in a glucose-dependent manner. The observation of weight loss has led to exploration of their potential as antiobesity agents, with liraglutide 3.0 mg day(-1) approved for weight management in the US on December 23, 2014, and in the EU on March 23, 2015. This review examines the potential nonglycemic effects of GLP-1 receptor agonists.

METHODS

A literature search was conducted to identify preclinical and clinical evidence on nonglycemic effects of GLP-1 receptor agonists.

RESULTS

GLP-1 receptors are distributed widely in a number of tissues in humans, and their effects are not limited to the well-recognized effects on glycemia. Nonglycemic effects include weight loss, which is perhaps the most widely recognized nonglycemic effect. In addition, effects on the cardiovascular, neurologic, and renal systems and on taste perception may occur independently of weight loss.

CONCLUSIONS

GLP-1 receptor agonists may provide other nonglycemic clinical effects besides weight loss. Understanding these effects is important for prescribers in using GLP-1 receptor agonists for diabetic patients, but also if approved for chronic weight management.

Association of UCP-3 rs1626521 with obesity and stomach functions in humans

OBJECTIVE

To examine the association of gene variants of uncoupling proteins (UCP)-2 and -3 with obesity and gastrointestinal (GI) traits.

METHODS

In 255 overweight or obese adults, the associations of gene variants in UCP-2 (-3474, rs659366) and UCP-3 (rs1626521, rs2075577, rs15763) with body weight (BW) and GI traits were studied. Gene variants were genotyped by TaqMan® assay. The associations of genotypes with BW and GI traits (gastric emptying, gastric volume, satiety by buffet meal, satiation by nutrient drink test and GI hormones) were assessed using ANOVA corrected for false detection rate (FDR).

RESULTS

A novel UCP-3 gene variant, rs1626521, was identified; it was associated with BW (P = 0.039), waist circumference (P = 0.035), and significantly higher postprandial gastric volume (P = 0.003) and calories ingested at buffet meal (P = 0.006, both significant with FDR). In a subgroup of 11 participants, rs1626521 was also associated with reduced mitochondrial bioenergetics efficiency in skeletal muscle (P = 0.051). In an in vitro study in HEK293 cells, rs1626521 reduced UCP-3 protein expression (P = 0.049). Associations detected between other genotypes and GI traits were nonsignificant with FDR.

CONCLUSIONS

A newly identified functional variant (rs1626521) in UCP-3 affects postprandial gastric functions and satiety and may contribute to weight gain and alter human mitochondrial function.

Emerging treatments in Neurogastroenterology: relamorelin: a novel gastrocolokinetic synthetic ghrelin agonist

BACKGROUND

Synthetic ghrelin agonists, predominantly small molecules, are being developed as prokinetic agents that may prove useful in the treatment of gastrointestinal motility disorders. Relamorelin (RM-131) is a pentapeptide synthetic ghrelin analog that activates the growth hormone secretagogue (GHS)-1a (also called the ghrelin) receptor with approximately sixfold greater potency than natural ghrelin. The ability of relamorelin to stimulate growth hormone (GH) release is comparable to that of native ghrelin. Relamorelin has enhanced efficacy and plasma stability compared to native ghrelin.

PURPOSE

In this review, we discuss the pharmacokinetics, pharmacodynamics and potential indications for relamorelin. Relamorelin is administered subcutaneously, dosed daily or twice daily. Relamorelin is being studied for the treatment of patients with gastrointestinal motility disorders. Phase IIA pharmacodynamic studies have demonstrated acceleration of gastric emptying in patients with type 1 diabetes mellitus (T1DM) and type 2 DM (T2DM) and upper gastrointestinal symptoms. In a phase IIA study in patients with diabetic gastroparesis, relamorelin accelerated gastric emptying and significantly improved vomiting frequency compared to placebo and improved other symptoms of gastroparesis in a prespecified subgroup of patients with vomiting at baseline. In patients with chronic idiopathic constipation with defined transit profile at baseline, relamorelin relieved constipation and accelerated colonic transit compared to placebo. These characteristics suggest that this new ghrelin analog shows great promise to relieve patients with upper or lower gastrointestinal motility disorders.

Quantitative gastrointestinal and psychological traits associated with obesity and response to weight-loss therapy

BACKGROUND & AIMS

Weight loss after pharmacotherapy varies greatly. We aimed to examine associations of quantitative gastrointestinal and psychological traits with obesity, and to validate the ability of these traits to predict responses of obese individuals to pharmacotherapy.

METHODS

In a prospective study, we measured gastric emptying of solids and liquids, fasting and postprandial gastric volume, satiation by nutrient drink test (volume to fullness and maximal tolerated volume), satiety after an ad libitum buffet meal, gastrointestinal hormones, and psychological traits in 328 normal-weight, overweight, or obese adults. We also analyzed data from 181 previously studied adults to assess associations betwecen a subset of traits with body mass index and waist circumference. Latent dimensions associated with overweight or obesity were appraised by principal component analyses. We performed a proof of concept, placebo-controlled trial of extended-release phentermine and topiramate in 24 patients to validate associations between quantitative traits and response to weight-loss therapy.

RESULTS

In the prospective study, obesity was associated with fasting gastric volume (P = .03), accelerated gastric emptying (P < .001 for solids and P = .011 for liquids), lower postprandial levels of peptide tyrosine tyrosine (P = .003), and higher postprandial levels of glucagon-like peptide 1 (P < .001). In a combined analysis of data from all studies, obesity was associated with higher volume to fullness (n = 509; P = .038) and satiety with abnormal waist circumference (n = 271; P = .016). Principal component analysis identified latent dimensions that accounted for approximately 81% of the variation among overweight and obese subjects, including satiety or satiation (21%), gastric motility (14%), psychological factors (13%), and gastric sensorimotor factors (11%). The combination of phentermine and topiramate caused significant weight loss, slowed gastric emptying, and decreased calorie intake; weight loss in response to phentermine and topiramate was significantly associated with calorie intake at the prior satiety test.

CONCLUSIONS

Quantitative traits are associated with high body mass index; they can distinguish obesity phenotypes and, in a proof of concept clinical trial, predicted response to pharmacotherapy for obesity. ClinicalTrials.gov Number: NCT01834404.

Does bariatric surgery improve ovarian stimulation characteristics, oocyte yield, or embryo quality?

Background

Obesity is a major global health concern associated with multiple co-morbidities. Bariatric surgery has been considered a good treatment option in cases of morbid obesity. This preliminary study aims to investigate the effect of bariatric surgery on ovarian stimulation characteristics and IVF treatment cycle outcome.

Methods

A retrospective study that was performed in a tertiary, university-affiliated medical center and included all patients who underwent IVF treatment both before and after bariatric surgery. Data on ovarian stimulation variables of IVF treatment cycle prior and following the bariatric surgery were reviewed and compared.

Results

From January 2005 to June 2014, seven women fulfilled the inclusion criteria. After the operation, BMI was significantly reduced (mean ± SD) (43.1 ± 3.3 vs. 29.6 ± 7.33, p = 0.018), as was the number of gonadotropin ampoules required during stimulation (69.3 ± 10.5 vs. 44.5 ± 17, p = 0.043). No between-cycle differences were observed in peak estradiol level, the number of oocytes retrieved, and percentage of mature oocytes.

Conclusions

To the best of our knowledge, this preliminary case series is the first comparison of IVF cycle characteristics prior to and following bariatric surgery. The operation seems to reduce treatment costs without affecting oocyte or embryo quality. Further large studies are required to establish the surgery’s effect on IVF outcome among infertile women.

Gut microbiota and obesity: role in aetiology and potential therapeutic target

Obesity is epidemic; chronic energy surplus is clearly important in obesity development but other factors are at play. Indigenous gut microbiota are implicated in the aetiopathogenesis of obesity and obesity-related disorders. Evidence from murine models initially suggested a role for the gut microbiota in weight regulation and the microbiota has been shown to contribute to the low grade inflammation that characterises obesity. The microbiota and its metabolites mediate some of the alterations of the microbiota-gut-brain axis, the endocannabinoid system, and bile acid metabolism, found in obesity-related disorders. Modulation of the gut microbiota is an attractive proposition for prevention or treatment of obesity, particularly as traditional measures have been sub-optimal.

Intestinal deletion of leptin signaling alters activity of nutrient transporters and delayed the onset of obesity in mice

The importance of B-isoform of leptin receptor (LEPR-B) signaling in the hypothalamus, pancreas, or liver has been well characterized, but in the intestine, a unique site of entry for dietary nutrition into the body, it has been relatively ignored. To address this question, we characterized a mouse model deficient for LEPR-B specifically in intestinal epithelial cells (IECs). (IEC)LEPR-B-knockout (KO) and wild-type (WT) mice were generated by Cre-Lox strategy and fed a normal or high-fat diet (HFD). The analyses of the animals involved histology and immunohistochemistry of intestinal mucosa, indirect calorimetric measurements, whole-body composition, and expression and activities of nutrient transporters. (IEC)LEPR-B-KO mice exhibited a 2-fold increase in length of jejunal villi and have normal growth on a normal diet but were less susceptible (P<0.01) to HFD-induced obesity. No differences occurred in energy intake and expenditure between (IEC)LEPR-B-WT and -KO mice, but (IEC)LEPR-B-KO mice fed an HFD showed increased excreted fats (P<0.05). Activities of the Na(+)/glucose cotransporter SGLT-1 and GLUT2 were unaffected in LEPR-B-KO jejunum, while GLUT5-mediated fructose transport and PepT1-mediated peptide transport were substantially reduced (P<0.01). These data demonstrate that intestinal LEPR-B signaling is important for the onset of diet-induced obesity. They suggest that intestinal LEPR-B could be a potential per os target for prevention against obesity.

Gastrointestinal morbidity in obesity

Obesity is a complex disease that results from increased energy intake and decreased energy expenditure. The gastrointestinal system plays a key role in the pathogenesis of obesity and facilitates caloric imbalance. Changes in gastrointestinal hormones and the inhibition of mechanisms that curtail caloric intake result in weight gain. It is not clear if the gastrointestinal role in obesity is a cause or an effect of this disease. Obesity is often associated with type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). Obesity is also associated with gastrointestinal disorders, which are more frequent and present earlier than T2DM and CVD. Diseases such as gastroesophageal reflux disease (GERD), cholelithiasis, or nonalcoholic steatohepatitis are directly related to body weight and abdominal adiposity. Our objective is to assess the role of each gastrointestinal organ in obesity and the gastrointestinal morbidity resulting in those organs from the effects of obesity.